THE LIBRARY 
 OF 
 
 THE UNIVERSITY 
 
 OF CALIFORNIA 
 
 LOS ANGELES
 
 


 
 ENGINEER'S AI*B MECHANIC'S
 
 THE 
 
 ENGINEER'S AND MECHANIC'S 
 
 ENCYCLOPAEDIA, 
 
 COMPREHENDING 
 
 PRACTICAL ILLUSTRATIONS 
 
 OF 
 
 THE MACHINERY 
 
 AND 
 
 PROCESSES EMPLOYED IN EVERY DESCRIPTION OF MANUFACTURE 
 
 OF THE i 
 
 BRITISH EMPIRE. 
 
 2Uttf) upfoarfcs of Sfoo t^tousantr lEngrabtngs. 
 
 BY LUKE HEBERT, 
 
 CIVIL ENOINEER, 
 
 IStJt'tfon, 
 
 WITH CONSIDERABLE ADDITIONS AND 'IMPROVEMENTS. 
 
 IN TWO VOLUMES. 
 VOL. I. 
 
 " How much useful knowledge is lost by the scattered forms in which it is ushered 
 to the world ! How many solitary students spend half their lives in making discoveries 
 which had been perfected a century before their time, for want of a condensed 
 exhibition of what is known." BUFFON. 
 
 LONDON : 
 THOMAS KELLY, 17, PATERNOSTER ROW. 
 
 MDCCCXLIX.
 
 T 
 
 9 
 
 PREFACE TO THE NEW EDITION. 
 
 THE rapid progress of Mechanical Science has developed 
 many most important facts since the first publication of 
 this Encyclopaedia. The inventions and discoveries recently 
 made have engaged the sedulous attention of the Editor : 
 for, as the value of each was tested by experiment, a 
 description was accordingly prepared. By the selection of 
 new articles, and care in the abridgement and revision of 
 old ones, this Edition has become systematically enriched : 
 so that it may be received, as fully and faithfully ex- 
 pressing " the existing state of Engineering and Mechanism," 
 adapted to the wants of Practical Men. 
 
 The unexampled sale of the early edition, and numerous 
 successive reprints, urgently demand another suited to the 
 present state of science. The Author has therefore cheerfully 
 obeyed the commands of his patrons in placing before 
 them in this new Edition the result of his late active and 
 pleasing occupation, in a form re-modelled, enlarged, and, as he 
 believes, considerably improved. 
 
 The article " RAILWAY " has been entirely re-written, and 
 divided into numerous explanatory Sections. These Sections, 
 although separate and independent, collectively form one 
 continuous and perfect Treatise on this important national 
 subject, capable of easy and immediate reference on the most 
 minute points. 
 
 Many alterations have been suggested, improvements 
 introduced, and inventions patented, connected with Loco- 
 motive Engines and Railway Carriages, calculated, it is 
 hoped, if carried into practice, to prevent the recurrence of 
 future calamitous accidents. On this momentous subject the 
 
 1159885
 
 y j PREFACE. 
 
 To accomplish an undertaking of such great convenience to 
 the scientific, as well as of real utility to operative men, in a 
 form adapted to instant reference and ready application, has 
 been my chief aim in the present work, which will com- 
 prehend, in addition to the usual matter contained in cyclo- 
 paedias on the mechanical and chemical sciences, upwards of 
 two thousand modern inventions and discoveries of merit and 
 originality, illustrated by Engravings carefully executed from 
 accurate working drawings. 
 
 Notwithstanding the extent and variety of subjects which 
 this work embraces, it may be necessary to remark, that by 
 the adoption of a small type, and close printing, the economy 
 of space is so far attained as to admit of each subject 
 receiving the consideration due to its importance, and to 
 comprise the whole in two thick octavo volumes. Thus, the 
 preparation and numerous manufactures of that invaluable 
 metal, the indispensable material of our machinery, (!RON,) 
 has received particular attention : so have, likewise, the 
 various manipulations and mechanism employed in our great 
 staple commodities, COTTON, SILK, WOOLLEN, and LINEN. 
 The construction of ENGINES (particularly STEAM ENGINES), 
 
 MILLS, RAILWAYS, CARRIAGES, SHIPS, BOATS, DOCKS, CANALS, 
 BRIDGES, FURNACES, BOILERS, GAS MACHINERY, LOOMS, 
 PRESSES, PUMPS, PADDLES, PLOUGHS, STILLS, WATCHES, 
 CLOCKS, WATER-WORKS, WHEELS, CRANES, STOVES, and a 
 
 thousand other subjects, receive, in like manner, their share 
 of attention. The various important processes of DYEING, 
 
 DISTILLING, BLEACHING, BREWING, TANNING, and numerous 
 
 other chemical manufactures, present also conspicuous 
 features in the contents of this work, the whole of which 
 may be said to combine an exposition of the entire series of 
 ihe Mechanical and Chemical Arts of the British Empire. 
 
 LUKE HEBERT.
 
 . ' ^ m
 
 THE IRON TUBULAR BRIDGE OVER THE RIVER CONWAi. 
 
 This surprising and unique example of engineering skill has been con- 
 structed across the river Conway, and forms a portion of the Chester and 
 Holyhead line of railway. The enormous iron tube, or more properly trunk 
 or chest, is made of wrought iron plates, varying in thickness from a quarter 
 of an inch to one inch, riveted together and strengthened by T irons, and, to 
 give additional strength to the whole, a series of cells is formed, both at the 
 top and at the bottom of the tube, between an inner ceiling and floor, and the 
 exterior plates. The upper cells, eight in number, are nearly square, being 
 1ft. 9in. high, and 1ft. 8in. wide. The lower cells, six in number, are 2ft. 
 3 Jin. wide, by 1ft. 9in. high. The space between wall and wall of the tube, if 
 we may so speak, is 14ft.; and the height of the whole, inclusive of the cells, 
 is 22ft. 3Jin. at the ends, and 25ft. 6in. at the centre ; the total length of the 
 tube is 4 12ft. 
 
 One end of this gigantic tube is fixed to the masonry of one of the stone 
 piers on which it is supported, and the other end is so arranged as to allow 
 for the expansion of the metal, owing to the variations of atmospheric 
 temperature, and rests on eleven iron rollers, lying on a bed plate ; but, in 
 order that the weight of the whole tube may not be carried by these rollers, 
 six girders are carried over the tube, and riveted to the upper part of its sides ; 
 the extremities projecting from the sides, and resting on twelve balls of gun 
 metal, running in grooves, which are fixed to iron beams let into the masonry. 
 The weight of the Conway tube is about 1300 tons. For the purpose of 
 constructing this triumph of engineering skill, an enormous platform was 
 raised on piles, on a piece of land projecting into the Conway, and about 100 
 yards from the site of the piers of the bridge, and on this the work of erecting 
 the tube was carried on ; its construction occupied twelve months, and when 
 complete it was floated to the piers on which it was to be raised, on six 
 huge pontoons, three at either end,^:onstructed near the spot where the tube 
 was erected; each of these pontoons was 100 feet in length, 25 feet in width, 
 10 feet high; they were floated at low water under the platform on which the 
 tube rested. The piles supporting the platform being taken away, the whole 
 mass of the tube rested upon two stone piers, temporarily erected at either end 
 for that purpose, and as the tide rose, the pontoons lifted the tube from these 
 piers, and transported it to the shelf prepared for it, on the permanent piers, 
 and below two enormous hydraulic presses, by means of which it was after- 
 wards raised into the place it was intended permanently to occupy. 
 
 At each end of the tube two strong lifting beams were fixed transversely, to 
 which the lifting apparatus of the hydraulic pa-esses was attached ; the chains 
 by which this was effected were of wrought iron, each link being 6 feet in 
 length from pin hole to pin hole ; at each lift the tube was raised 6 feet ; the 
 cylinder in which the ram of the press worked was 3 feet 1J inches outside 
 measure, and the hollow for the ram 1ft. Sin. in diameter. The space allowed 
 for water all round the ram was very narrow, and at the top of the cylinder 
 was a deep collar, at which part the space for water was stopped, and a 
 water-tight joint formed by means of a leather packing in it. The aperture 
 for the entrance of water into the cylinder was bored through the collar, and 
 only three-eighths of an inch in diameter, and the quantity of water each 
 cylinder held, was 66 gallons ; each press, being worked at the pressure of 
 tons to the inch, was capable of lifting 972 tons ; but as it was calculated 
 they would bear 4 tons to the inch, each of them, in that case, would have 
 been able to support the enormous weight of 1296 tons. 
 On Monday, the 6th of March, 1848, the operation of moving this enormous 
 lass, and placing it m its proper position, began, and on the first of May it 
 was firmly seated on the permanent piers, and formed part of the railway. 
 The Engineer by whom this great work was effected is Robert Stephenson, Esq. 
 issrs. haston and Amos were the engineers on whom devolved the 
 onerous duty of lifting this tube, by means of the hydraulic apparatus. 
 
 See other side.
 
 A CURIOUS CLOCK BY ISAAC HABRECHT, ANNO 1589. 
 
 THIS ingenious piece of workmanship was for more than two centuries in the 
 possession of the Court of the Popes of Rome ; and was subsequently the 
 property of William the First, King of the Netherlands. It was sent to 
 England for sale in 1847, at the fixed price of 5,000 guineas. It was exhibited 
 at the Marquis of Northampton's soiree, in March 1848, to the members of the 
 Royal Society, and many other distinguished savans. It was first engraved 
 for the " Illustrated London News" and a correct exterior representation of 
 this ancient curiosity is now presented to the subscribers of the Engineer's and 
 Mechanic's Encyclopedia, and forms a suitable Frontispiece to our article 
 Horology, page 683. 
 
 Its construction is very interesting, as showing the state of clock-making 
 towards the close of the sixteenth century. If, bears decided proof of having
 
 ISAAC HABRECHT'S CURIOUS CLOCK. 
 
 been produced by manual labour, without any other assistance than the bench 
 of the turner and the tile. 
 
 It is obvious this clock had the ancient motive power ; the pendulum being 
 a later invention of the celebrated Christian Huygens, in 1657. 
 
 The design consists of a tower, divided into three stories, with doors of 
 strongly gilt copper, tastefully chased and ornamented, and supported by twelve 
 columns of strongly gilt copper. In front of the lower story, within a square 
 chamber, is a large dial plate, which moves round its whole circuit only once a 
 year : it shows also the date of the month, and all the Catholic feasts and holy 
 days throughout the year. In the centre is a small plate, very curiously chased, 
 representing the twelve signs of the zodiac, with the sun and moon pursuing 
 their course, so that at one glance it may be ascertained in what sign of the zodiac 
 they are at the time. Within this circle is a small globe, pointing out the 
 proper phases and aspects of the moon ; and within all this are the fixed stars. 
 The four corners of this chamber are emblematically engraved with the names 
 of those nations who have conquered kingdoms at an early period, 
 
 In front of the second story are the minutes and minute-hand, and on each 
 side are two silver figures, one hand of these figures pointing to the minutes, 
 the other hand being set in motion by mechanism : during the striking of the 
 clock, the one figure turns the hour-glass, as an emblem of time, the other 
 wields the sickle of death. Above each of the silver figures is a Latin verse ; 
 and in the middle of the plate is a simple yet correctly mathematical represen- 
 tation of how the globular form of the earth is perceptible to the eye. Above, 
 the minute-hand describes a circuit of 24 hours, each half of the dial-plate con- 
 taining 12 hours; the day hours being marked with the image of the sun, and 
 the hours of the night with the image of the moon. On the four corners of the 
 dial-plate are engraved the four seasons of the year. 
 
 The third story also consists of four divisions, which project in the manner 
 of a balcony. Round the centre of the lower division move the seven silver 
 figures of heathen gods, in chariots : every deity makes its appearance once in 
 seven days, exactly in front, where it remains for 24 hours, when it is relieved 
 by the next ; these godheads represent the seven days of the week. 
 
 In the centre of the second division is an image of the Virgin, holding her 
 son Jesus in her arms ; two angels placing crowns and garlands on her head ; 
 and during the performance of the bells several angels make their appearance, 
 making their obeisance before the image of Mary and the Saviour. 
 
 Within the centre of the third division is a metal bell pending on a gilt plate 
 on which is represented the judgment day. Round this plate move 
 
 . 
 
 silver figures, set in motion by mechanism, representing the four states of 
 It. Im ages point out the quarters of the hour by striking the 
 
 bell : the first quarter is represented by a youth, the second by a grave citizen, 
 the third by a Roman soldier, and the fourth by a priest. 
 
 In the fourth division is a metal bell, on the sides of which there are 
 chambers ; on the left side is the renrespntati n f n Q fl, ,, 
 
 ' ^ eautifull y *ed in filagree ; on the top 
 the chiming, spreads its wings, and crows. 
 
 with fl *
 
 THE 
 
 ENGINEER'S AND MECHANIC'S 
 
 ENCYCLOPAEDIA. 
 
 ABACUS. An instrument employed by the ancients for facilitating calcula- 
 tions; similar to that now frequently employed for teaching children the 
 rudiments of arithmetic, and which is commonly sold in our stationers' shops. 
 It usually consists of twelve parallel wires, fixed in a light rectangular frame ; 
 each wire carrying 12 beads or balls. There are thus 12 times 12, answering 
 to the common multiplication-table, all the results of which it demonstrates to 
 the dullest capacity. All the operations of addition or subtraction are likewise 
 performed by it, by merely moving the beads from one side to the other of the 
 frame. By thus smoothing the difficulties of acquiring arithmetical knowledge 
 at the very outset, and rendering it quite obvious and amusing at the same time, 
 the apparatus becomes one of considerable importance in education. 
 
 Another kind of Abacus consists of a series of parallel wires fixed in a frame 
 like the former. On each wire there are nine little balls ; the lowest stand for 
 units, the next above for tens, the next hundreds, and so on up to any number. 
 The frame is divided into two compartments a and 6, by a cross wire at c, which 
 
 c b 
 
 Millions . : . . . 
 Hundreds of Thousands 
 Tens of Thousands . . 
 
 Thousands 
 
 Hundreds 
 
 Tens 
 
 Units . 
 
 
 
 
 
 
 
 000000000= 
 
 
 
 
 
 
 
 is sufficiently raised above the wires to allow the little balls to slide under it. 
 Suppose the whole 63 balls to be placed in the compartment a, and it be pro- 
 posed to note the sum of 4,346,072 : it is effected by sliding the balls shown 
 in b from their previous situation in a. 
 
 A variety of machines for facilitating arithmetical computations, have been 
 from time to time introduced and extensively used. Among the most celebrated 
 of these are the inventions of Napier, Gunter, Lamb, Pascal, Stanhope and 
 Babbage; some account of which we have introduced under the article, 
 
 CALCULATING MACHINES. 
 
 ABATTOIR. A name given by the French to their commodious public 
 slaughter-houses. The many serious evils occasioned by the driving of cattle
 
 2 ABATTOIR. 
 
 and other animals intended for the food of the people, through the crowded streets 
 of a city, and slaughtering them in private buildings in densely populated 
 districts, were so notorious as to induce the French Government in the year 1810 
 to prohibit private slaughtering, as well as the passage of cattle in Paris. Public 
 abattoirs in the suburbs were in consequence established, where all the cattle, 
 sheep, &c., destined for the supply of the city, were slaughtered before entering 
 it. These abattoirs are five in number, and are situated nearly on a circle of 
 about two miles radius from the centre of the city. Within each are included 
 utables, stalls, and pens for the animals, and manufactories of various animal 
 substances. The largest assemblage of abattoirs are those of the district of 
 Montmartre, which covers a space 1200 feet in length and 270 in breadth. 
 The slaughter rooms are individually 32 feet long, and 16 broad, and have an 
 entrance at each end ; one for the living animals, and the other for the removal 
 of the meat. They are built of stone, and every interstice is carefully stopped 
 with a hard impervious cement, so as to prevent the lodgment of any offensive 
 matter. Each room has an abundant supply of water, and is adapted by its 
 structure to be easily and thoroughly cleansed, ventilated, and drained. The stone 
 floors are inclined into channels to conduct the blood into reservoirs. For the 
 purpose of raising and moving the carcases, the most convenient mechanical aids 
 are provided. The roofs project 9 feet beyond the outside walls, to afford shelter 
 from the sun and rain. The total number of slaughter rooms in the five abattoirs 
 before mentioned is 240. Contiguous to each, are stalls and pens for the animals, 
 and places for forage ; which are let separately at a rent to the butchers, 
 thereby enabling each butcher to keep his animals in full health for any re- 
 quired length of time. Adjoining, or near to the abattoirs, are manufactories 
 of tallow, glue, size, horn, oil, &c., so that all the various animal substances, 
 besides the meat, are at once disposed of, and applied to their best uses, and, 
 owing to the proximity, with great economy. A resident inspector is appointed 
 to each abattoir, under whose jurisdiction it is placed, and whose paramount 
 duty it is to prevent cruelty to the animals, and see that they are in full health 
 previous to being slaughtered, that the public health may not be affected thereby. 
 The best authorities state, that the health of the Parisians has been greatly 
 improved by the abolition of private slaughter-houses. Now, in most of the 
 large cities of Europe there are establishments of a similar nature ; yet in 
 London, the boasted emporium of the arts and sciences, having -a population 
 nearly double that of any city in Europe ; private interest has been hitherto 
 allowed to triumph over the public good; and, to the disgrace of the Corporation, 
 as well as the government of the empire, London is to this day without a sin- 
 gle abattoir ! The existence of our great cattle market in nearly the centre of 
 the city has been for many years the subject of complaint, and a committee 
 appointed by the House of Commons in 1828 to inquire into the state of 
 Smithfteld Market reported it to be apublic nuisance. Nineteen more years have 
 passed since that report was made, but the nuisance remains. The passage of 
 numerous droves of cattle through our crowded thoroughfares always occasions 
 great alarm and inconvenience to the inhabitants and persons in the streets, 
 who frequently suffer bodily injuries therefrom, and occasionally sacrifices of 
 life. The poor animals also suffer exceedingly from cruel treatment and want 
 of rest ; and the quality of the meat is considerably deteriorated from these 
 causes. The slaughtering is conducted, in many cases, in ill-drained, ill-venti- 
 lated cellars ; where, again, much needless pain is caused to the animals by the 
 indifference and want of skill of the persons employed. The effluvia from some 
 of these places and from the drains in the vicinity is abominable, and is the 
 fruitful source of disease and mortality. There appears at last, however, some 
 ground for hope that this disgraceful state of things has reached its term, and 
 that public convenience, public health, and humanity, will be at length preferred 
 ) the imaginary interests of a few individuals, by the establishment of a cattle 
 market and abattoirs in suitable localities in the suburbs. The adjoining cut 
 represents a plan for an abattoir and cattle market, which will convey to the 
 reader some insight to the arrangements necessary. 
 
 At a is the chief entrance to the cattle market, with gate-keeper's lodge, toll
 
 ABATTOIR. 3 
 
 office, &c : b b b, principal roads traversing the market, c, assemblage of 
 buildings in the centre, containing exchange, bank, post-office, cofi'ee and 
 
 refreshment rooms, and apartments for the officers of the market ; and replete 
 with every convenience for conducting the business of the establishment with 
 efficiency and regularity, d d, market for horned cattle and. horses, calculated 
 for about 8000 heads, e e e is the sheep market, computed to contain about 
 50,000. f is the calves market, and g the space appropriated to swine, h h urine
 
 4 ABSORBING AND PRODUCTIVE CASCADE. 
 
 tanks for liquid manure, collected from the gutters, and conducted by pipes from 
 all parts of the market, i i, sheds for sheep and cattle, with forage lofts above. 
 Jckk, walls surrounding the market and the abattoirs; I, engine for constantly 
 supplying every part of the market and abattoirs with water; connected with 
 which is a forge, workshop, and fire-engine, m m, exit gates from the market, 
 , entrances from the market to the abattoirs ; o o, abattoirs ; pp, meat pre- 
 serves and refrigeratories ; q q, reservoirs of blood conducted by pipes from 
 each abattoir; r r, superintendent and officers' houses, stables, and various 
 offices ; *, entrance gate to abattoirs, with toll and gate-keeper's house. 
 
 ABSORBING AND PRODUCTIVE CASCADE; an apparatus of great 
 utility and elegance, invented by M. Clement. It is known that the absorption 
 or solution of the gases takes place in proportion to the pressure on the absorbing 
 liquid, the extent of surface exposed to the absorbing action, and to the length 
 of time in which it ia exposed. If the pressure, however, be very great, the 
 vessels are liable to rupture; and it therefore becomes an important object to 
 strengthen the influence of the other two principles just mentioned, which has 
 been obtained in a very eminent degree by the invention of M. Clement. In this 
 apparatus, which is represented in the annexed diagram, the gas has no pressure 
 to sustain, but the surfaces of its contact are exceedingly multiplied and extended. 
 
 rcelain, 
 
 The column a is filled with a great number of small bulbs of glass or por 
 ts lower extremitv resting in another cylinder b, of greater diameter, in which 
 is a cavity adapted to the reduced diameter of the column, which communicates 
 ttb two small tubes c, d, the former being employed to introduce the gas, and 
 he latter to d.scharge the hqu,d. At e is a reservoir of water, with a conducting 
 Jpe/, the supply therefrom bemg regulated by a cock g. The 
 passage to the lower part of. the column, successivel moistens 
 
 water, in its 
 moistens all the small
 
 ACCELERATION. 5 
 
 spheres, and being thus impeded in its progress, a very considerable time i. 
 occupied in its descent. On the other hand, the gas, as it is introduced, occu- 
 pying all the vacant interstices, becomes infinitely divided ; and therefore as it 
 can only pass through the intermediate spaces very slowly, the duration of the 
 contact is much prolonged, and the absorption promoted. The inventor calcu- 
 lates that the absorbing power of this apparatus is 322 times greater than the 
 ordinary simple vessels used for the purpose. Although M. Clement, in making 
 this comparison, has unquestionably selected the most unfavourable case, it must 
 be admitted that his absorbing cascade possesses great advantages. To the 
 apparatus thus described, M. Clement adapts another, which he calls " the 
 Productive Cascade," shown in combination in our diagram. It is intended to 
 produce gas for a considerable period of time, and in a more convenient and 
 less expensive manner than by the ordinary methods. Suppose, for example, 
 it is required to prepare oxymuriatic acid or chlorine; a large vessel h, provided 
 with four openings, is filled with oxide of manganese, broken into large pieces; 
 the opening i is by a tube connected to a leaden vessel k, containing common 
 salt and sulphuric acid. By the tube /, a small stream of water is made to flow 
 from the reservoir above, which gradually moistens the whole surface of the 
 pieces of manganese, and permits the muriatic acid gas to attack and dissolve it 
 very easily. The chlorine which is produced passes by the tube n, into the 
 absorbing cascade, while the muriate of manganese is carried off as it forms, by 
 the water, through the tube o, into the reservoir p. By this arrangement, there 
 is no occasion to reduce the manganese to powder, and a much larger quantity 
 may be operated on at the same time, without the operator being under the neces- 
 sity of frequently renewing the charge of materials, and dismounting his apparatus. 
 ABUTMENT is a term commonly applied by engineers to those fixed parts 
 of mechanism whence a resisting or reacting force is obtained. Thus each of the 
 endsof the cylinderofareciprocatingsteam engine forms areacting point, causing 
 the steam to impel the piston the contrary way. In a rotatory engine, the steam 
 stop is the abutment, and in a screw press, the stationary head through which 
 the screw passes. The term abutment is also applied to the land piers of a 
 bridge, and many other objects which it would be needless to advert to. 
 
 ACCELERATION is the increase of velocity in a moving body, caused by 
 the continued action of the motive force. When bodies in motion pass through 
 equal spaces in equal times, or, in other words, when the velocity of the body 
 is the same during the period that the body is in motion, it is termed uniform 
 motion, of which we have a familiar instance in the motion of the hands of a 
 clock over the face of it ; but a more correct illustration is the revolution of the 
 earth on its axis. In the case of a body moving through unequal spaces in 
 equal times, or with a varying velocity, if the velocity increase with the duration 
 of the motion, it is termed accelerated motion ; but if it decrease with the 
 duration of the motion, it is termed retarded motion. A stone thrown up in the 
 air, affords an illustration of both these cases, the motion during the ascent 
 being retarded by the force of gravity, and accelerated by the same during the 
 descent of the stone. All bodies have a tendency to preserve their state, either 
 of rest or of motion ; so that if a body were set in motion, and the moving 
 force were withdrawn, the body, if unopposed by any force, would continue to 
 move with the same velocity it had acquired at the instant the moving force 
 was withdrawn. And if a body in motion be acted upon by a constant force 
 (as the force of gravity), the motion becomes accelerated, the velocity increasing 
 as the times, and the whole spaces passed through increasing as the square of 
 the times ; whilst the proportional spaces passed through during equal portions 
 of time, will be as the odd numbers, 1, 3, 5, 7, &c. ; and the space passed over 
 in any portion of time will be equal to half the velocity acquired at the end of 
 such time : which results will be better brought to view in the following Table. 
 Times. Velocities. Spaces for each Time. Total Space. 
 
 1 1 1 1 = 1 
 
 223 3 + l=4=2 2 ' 
 
 335 5+3+l=9=3 2 
 
 447
 
 ACCELERATION. 
 
 It has been ascertained by experiment, that a body falling freely by its own 
 weight from a state of rest, will descend through 16-Jg feet in the first second of 
 
 time, and will have acquired a velocity 
 of 32 feet; but from the rapidity 
 with which the velocity increases, we 
 cannot extend the experiment, for in 
 only four seconds a body falling 
 freely would pass through a space of 
 256 feet. But by an ingenious con- 
 trivance of the late Mr. Attwood, of 
 Cambridge, the laws of motion above 
 laid down may be verified experiment- 
 ally. The machineis called" Attwood's 
 machine," after the name of the in- 
 ventor ; and the principle of its action 
 consists in counteracting a portion of 
 the gravitating power of a body, by 
 the gravitating power of a smaller 
 body; so that the absolute velocity, and 
 the spaces passed through, shall be less 
 than in the case of bodies descending 
 freely, whilst, as the force is constant, 
 the same ratio of progression will hold 
 in both cases. The annexed figure 
 represents one of these machines, as 
 constructed by Mr. Toplis. a a a is a 
 triangular frame, upon three movable 
 legs ; b, a small platform suspended 
 from it by a universal joint c c, and 
 supporting two upright standards d d, 
 in which the axis of a light brass wheel 
 e revolves- with very little friction. 
 Over a groove in the periphery of the 
 wheel passes a very light and pliable 
 silk thread, from the ends of which 
 hang two equal weights/, g. Into the 
 under side of b is screwed a square rod 
 h, descending to the floor, to which it 
 is secured in a perpendicular position 
 by small pins passing through holes in 
 the claws at i i. On the face of the 
 rod is a scale of inches, k is a brass 
 guide, fixed at the upper part of the 
 rod h, so that when the top of the 
 weight g touches the lower side of fc, 
 the under side of g is on a level with 
 the top, or commencement of the scale ; 
 / is a small stage, movable along the 
 rod h, and having a hole in it suffi- 
 ciently large for the weight g to pass : 
 on one side is a tightening screw m. 
 n is another movable stage, fitted with 
 a tightening screw o, as also a fork p, 
 turning upon a hinge. The experi- 
 ments are conducted as follows: A 
 small circular weight is placed upon g, 
 which is pulled up to the top of the 
 scale, and the stage n is screwed to the 
 rod A, on a level with the lower part 
 of the weight /, which is held down
 
 ACCORDION. 
 
 upon it by the fork p. Upon releasing /from the fork, the weight g descends 
 with a slow, but gradually accelerated motion, and the number of inches the 
 weight has descended, at each successive beat of a pendulum (suspended from 
 another triangle), is observed upon the scale ; and if the additional weight be 
 such as to cause g to descend through three inches in the first second, then it 
 will cause it to descend through 1 foot in two seconds, and through 6j feet in 
 five seconds. If the additional weight be removed, and a small bar of equal 
 weight, but of a length exceeding the diameter of the hole in /, be placed upon 
 g, and the stage I beset at any division of the scale, at which the weight would 
 arrive at the end of any number of seconds, the stage will intercept the bar in 
 its descent, and the weight will continue to descend with the velocity it had 
 acquired upon reaching /. Thus if the velocity at the end of the second second 
 be two feet, in which case the weight would have descended one foot in that 
 time, if the stage be set at one foot upon the scale, it will intercept the bar at 
 the end of the second second, and the weight g will move with a uniform 
 velocity of two feet per second, through the remaining portion of its descent. 
 Tf it is required to illustrate the case of retarded motion, the small circular 
 weight is placed upon the weighty, and a similar small weight upon the weight 
 f, so that^r, still outweighing/ will descend; but as soon as the stage /inter- 
 cepts the bar with the small weight upon it, /becomes the heaviest, and g will 
 descend with a velocity decreasing as the squares of the times, counted from 
 the time of g passing the stage /. 
 
 With the view of diminishing as much as possible the friction of the axis of 
 the wheel e, Mr. Attwood supported its extremities upon the peripheries of 
 four antifriction wheels. Mr. Toplis, in a new arrangement of the machine, 
 adopted simple fixed bearings, formed of studs, and so shaping them in the 
 lathe to a conical configuration, that the extent of rubbing surface was 
 actually less than in the complex arrangement of Mr. Attwood ; in whose 
 machine, nevertheless, there was much to be admired. 
 
 ACCORDION. A musical instrument, of the class called " Free-reed " 
 instruments, in which the sound is produced by the vibrations of thin tongues 
 or slips of metal. The invention is very recent, of German origin, and the 
 instruments are, for the most part, manufactured in Germany. They are 
 variously constructed, with a greater or less number of reeds and keys, thereby 
 producing a greater or less range of notes; but the most common form is 
 similar to that shown in the 
 accompanying engravings : of 
 which Fig. 1 affords a front 
 view, Fig. 2 a plan exhibit- 
 ingthe arrangement of the sys- 
 tem of- reeds, and Fig. 3 a 
 vertical section of Fig. 1. 
 Fig. 4 shows a plan of a single 
 pair of reeds, of the full size, 
 and Fig. 5 a vertical section 
 of the same, a a represents 
 a rectangular box, the lower 
 portion of which, b, is com- 
 posed of an air-tight flexible 
 material, forming the bellows 
 and wind chest; c is a hori- 
 zontal partition of wood form- 
 ing the top side of the wind 
 chest, on the upper surface of 
 which are formed one large 
 cell d, and ten smaller cells ee. 
 In the bottom of each cell 
 there are two apertures cut 
 through the partition c ; each 
 of these apertures is covered 
 
 Fig. 2. 
 
 111111
 
 ACOUSTICS. 
 
 Fig. 3. 
 
 
 Fig. 4. 
 
 e 
 
 on one side by a thin metallic 
 plate/ having an oblong piece 
 cut out of the middle of it ; 
 and this oblong hole is im- 
 perfectly stopped by an elastic 
 tongue g (made of thin brass), 
 rivetted at one end to the 
 metallic plate / as shown in 
 the figures 4 and 5. The 
 tongue g is thus made (by 
 the current of air driven 
 through the aperture) to vi- 
 brate freely in the oblong 
 space cut out of the plate/ 
 and is technically termed a 
 "Free-Reed." On the other 
 side of each aperture there is cemented at one 
 edge a flap or valve of thin leather. The reeds 
 in each cell are fixed one to the upper side of the 
 partition, and one to the lower side, as shown in 
 the figures 4 and 5, so that notes are produced 
 both by the expansion and the contraction of the 
 wind-chest. The larger cell d likewise contains 
 two plates/ with valves h adapted to each as in 
 the smaller cells; but the plates in this large 
 cell contain each three reeds, so toned as to form 
 chords with the other notes. The partitions of 
 the cells are faced on the upper side with buff 
 leather, over which the cover i i slides, and forms 
 therewith an air-tight joint. In the cover over 
 each of the small cells is a hole closed by a key k, 
 and over the larger cell are two holes, one at 
 each end, closed by the keys II, which are moved 
 simultaneously by the knob m. The notes are 
 produced either by the distension or by the com- 
 pression of the bellows, according to the note 
 required ; and two or more notes can be sounded 
 at once as on the piano or organ. There is a valve or key , in the bottom of 
 the wind-chest, by the opening of which the action of the air upon the reeds is 
 prevented, and the bellows may be extended or contracted without producing 
 any sound ; so that when a succession of ascending or descending notes are 
 required, each occupying the whole range of the bellows, the wind-chest can be 
 filled or discharged during the return stroke between each note, without pro- 
 ducing any sound. The keys II are generally kept open, thereby producing 
 chords ; but they may be closed, in which case the air alone is played. The 
 instrument is extremely portable, and when well made, the sounds are but little 
 inferior to those of an organ. There are numerous other instruments made on 
 the same principle, as the Concertina, Seraphine, ./Elophon, &c. 
 
 ACOUSTICS. See PHONICS. In this place we take the opportunity of 
 introducing a notice of an extraordinary machine lately invented by Professor 
 Faber, and now being exhibited in this country. It is called the Euphonic, or 
 Speaking Automaton, as it imitates most of the sounds of the human voice with 
 considerable accuracy ; also sings, whispers, laughs, &c. The principal organs 
 of articulation are composed of caoutchouc, and a wind-chest performs the 
 functions of lungs. An arrangement of keys similar to those of a piano- 
 forte, communicate with the organs of speech, and when pressed by the 
 fingers of the operator in the proper combinations, cause them to utter 
 syllables, words and sentences. It far exceeds all previous attempts to 
 produce speech by mechanism. Although such attempts at imitating nature 
 em at first as a misdirection of ingenuity and labour, let us not overlook
 
 ACID ACETIC. 9 
 
 the fact, that we are indebted to ihe visionary alchemist for many of out 
 important chemical discoveries. 
 
 ACETATES. The salts formed by the combination of the acetic acid with 
 alkalies, earths, and metallic oxides. See their different bases, and the article, 
 Acia, ACETIC. 
 
 ACHROMATIC. A term applied to those lenses of telescopes, and other 
 optical instmments, in which the aberrations of light common to ordinary lenses 
 are remedied, and the colours justly reflected. 
 
 ACIDS. A most important class of chemical compounds, which have for the 
 most part the following properties. They have a sour, or sourish taste, the 
 stronger kinds being acrid and corrosive. They change the vegetable blues and 
 purples to a bright red. They unite with water in almost every proportion 
 With a few exceptions, they are decomposed or volatilized by a moderate heat 
 They combine with all the alkalies, and most of the metallic earths and oxides, 
 and form with them that class of bodies termed salts. The varieties of acids 
 are extremely numerous, and willbe generally noticed under the head CHEMISTRY. 
 The four principal acids of commerce, viz. the acetic, sulphuric, nitric, and 
 muriatic, which are manufactured on the great scale, we shall describe in this 
 place. 
 
 ACID, ACETIC, is the acid contained in common vinegar, but in a very dilute 
 state, and in combination with other vegetable principles. It is found united 
 with potash in a great variety of plants, also in several animal secretions. It 
 is likewise the result of a spontaneous fermentation, to which liquid, vegetable, 
 and animal matters, are liable. Strong acid, as the sulphuric and nitric, develope 
 the acetic by their action on vegetables. Dry vegetable substances generally, 
 when subjected to a red heat in close vessels, yield it copiously. The proportion 
 of the products varies not only from employing different substances, but they are 
 different when only one substance is employed, according as the heat is greater 
 or less, or the operation is differently managed. When a vegetable substance is 
 distilled in close vessels, at first the water comes over which existed ready formed, 
 and then water formed by union of the oxygen and hydrogen of the substance. 
 Afterwards, a quantity of carbon is separated ; and by the continued application 
 of heat, this unites with the oxygen and hydrogen, and forms an acid, formerly 
 supposed to be a particular acid, and then called pyroligneous acid, but it is now 
 known to be the acetic acid, united with empyreumatic oil, which rises somewhat 
 brown, and grows thicker and darker, augmenting in density as the quantity of 
 carbon increases. At the same time, a small quantity of carbonic acid gas, much 
 Ciirburetted hydrogen, and, towards the closr>, a great quantity of gaseous oxide 
 of carbon, are disengaged. All the carbon not carried off in these various forms 
 remains in the still, and generally preserves the form of the vegetable substance 
 employed. Since we have learned the nature of all these products, the process 
 has been much improved, and particularly by charring the wood, and by turning 
 the other products to advantage. In the forests, the wood is first charred, so as 
 to dissipate all the water of vegetation. It is then introduced into a large 
 circular vessel, a, made of iron plates riveted together, and having at its upper 
 part a small lateral iron cylinder ; an iron cover is closely fitted to this pot, 
 and then is lifted by means of a crane, or other mechanical power, and placed 
 in a cast-iron retort, c, set over a furnace ef the same shape. The furnace is 
 then covered with a lid, e, constructed in masoiiry. A moderate heat being 
 applied to the furnace, at first the vapour of the wood is dissipated, but this 
 vapour soon ceases to be transparent, and becomes sooty At this time a 
 tube or cylinder, enclosed in another of brick-work or tiles, is affixed to the 
 lateral cylinder, and forms the condensing apparatus. This is different in different 
 places : in some, the condensation is effected by the air, the vapour being made 
 to pass through a long extent of cylinders, and sometimes of casks, adapted to 
 each other; but most generally the condensation or cooling is effected by water, 
 when it can be procured in sufficient quantities. The most simple apparatus for 
 this purpose consists of two cylinders//, enclosed one within the other, and 
 having between them & space sufficient to allow a large quantity of water to flow 
 backwards and forwards, and thus cool the vapour. These cylinders are adapted 
 
 VOL. i. c
 
 10 
 
 ACID ACETIC. 
 
 iclined to the horizon. To this first 
 
 to the distilling apparatus, and pla_- 
 
 apparatus a second, and sometimes a third is adapted, and placed in a zig-zag 
 form, in order to occupy as little space as possible. The water is made to cir 
 culate in the following manner. At the lower extremity g of the condensing 
 apparatus, there is a tube which ought to be somewhat higher than the upper 
 part of the whole of this apparatus, where at h there is another short tube 
 curved towards the ground. Water from a reservoir is made to run through the 
 
 perpendicular tube to the lower part of the condensing apparatus, and fills all 
 the space between the cylinders. When the operation is going on, as the vapours 
 are condensed, they raise the temperature of the water, which, becoming lighter 
 in consequence, flows out of the curved tube h. The condensing apparatus 
 terminates in a covered brick canal i, underground, at the end of which is a bent 
 tube /t, that conducts the liquid products into the first cistern; when this is full, 
 it discharges itself by means of a syphon into a large reservoir; the tube which 
 terminates the canal plunges into the liquid, and thus cuts off the communication 
 with the interior of the apparatus. The gas hereby disengaged is conveyed by 
 means of the tube II under the ash-hole of the furnace. This tube is furnished 
 with a cock, to regulate the flow of the gas, and cut off the communication at 
 pleasure. That end of the tube which terminates in the ash-hole, rises a few 
 inches perpendicularly, and is furnished at its extremity with a perforated rose, 
 for distributing the gas uniformly under the vessel, without being itself liable to 
 become choked with the ashes, or to obstruct the feeding of the fire. The 
 degree of heat necessary to effect carbonization is not very great, yet, towards 
 the end of the process it must be raised sufficiently to make the vessel red-hot, 
 and the length of the operation is necessarily regulated by the quantity of wood 
 to be carbonized at the time. By the colour of the gas flame it is ascertained 
 when the carbonization is complete ; at first it is of a reddish yellow colour, but 
 afterwards \t becomes blue, as it throws off more oxide of carbon than carbu- 
 retted hydrogen ; at last it becomes entirely white, probably caused by the 
 vessel being hottest at this period, and the combustion, therefore, may then be 
 considered as quite finished. There is also another method of ascertaining the 
 completion of the operation, which is more frequently had recourse to; that is,
 
 ACID MURIATIC. 11 
 
 'the cooling of the upper part of the tubes,. which is not surrounded with water ; 
 some drops of water are then thrown upon it, and if these evaporate without 
 noise, the operation is considered to be finished. The adapting short tube is 
 next removed from the vessel, and the opening into it immediately closed by an 
 iron-plate cover, which is then luted with loam. The lid which covers the fur- 
 nace is next removed, and then the vessel itself is lifted out of the furnace by 
 means of the crane, which should be immediately replaced by another similar 
 retort got ready for the purpose. When the retort which has been taken out 
 has become cold, it is uncovered, and the charcoal taken out. Whatever may 
 be the kinds of wood employed in this operation, nearly the same results are 
 obtained, as far as respects the acid ; not so, however, with regard to the char- 
 coal. The denser the wood, the better the charcoal ; and it has been remarked, 
 that when the wood has been long left in contact with the open air, the charcoal 
 produced from it is of a much worse quality than from that wood which is car- 
 bonized the same year it was cut. An acetic acid of very considerable strength 
 may also be prepared by saturating perfectly dry charcoal with common vinegar, 
 and then distilling. The water easily comes off, and is separated at first, but a 
 stronger heat is required to expel the acid. If vinegar be exposed to very cold 
 air, or to a freezing mixture, its water will be separated in the form of ice, and 
 the interstices be filled with a strong acetic acid, which may be collected by 
 draining. The radical vinegar of the apothecaries, made by dissolving in it a 
 little camphor, or fragrant essential oil, has a specific gravity of about 1.070, 
 and consists of one part of water to two of the crystallized acid. The pungent 
 smelling salt is made by moistening the sulphate of potash with a little con- 
 centrated acetic acid. Acetic acid acts upon iron, zinc, copper, and nickel, in 
 the metallic state, and upon the oxides of various other metals; its combination 
 with the latter being usually effected by mixing a solution of their sulphates 
 with that of an acetate of lead. It has a very slight action upon metallic tin, 
 when highly concentrated. The strongest acetic acid will, we are informed, 
 dissolve metallic lead, which is contrary to the statements of chemical authors. 
 Acetic acid dissolves resins, gum-resins, camphor, and essential oils. Its odour 
 is employed in medicine to relieve nervous headache, fainting, and sickness 
 from crowded rooms. Its anti-contagious powers are not now so confidently 
 relied upon as formerly. It is extensively used in calico-printing. It unites 
 with all the alkalies, and most of the earths, and with these bases it forms com- 
 pounds, some of which are crystallizable, and others have not yet been reduced 
 to a regularity of figure. For the properties and uses of these combinations we 
 refer the reader to Dr. Ure's Dictionary of Chemistry. 
 
 ACID, MURIATIC, may be obtained by distillation from a mixture of com- 
 mon salt with clay or bole, which is the original process ; but it is now only 
 used where fuel and pottery earths are cheap, and oil of vitriol dear. The 
 method most commonly practised at present to obtain it, is to decompose the 
 muriate of soda, or common salt, by sulphuric acid, and condensing the 
 muriatic acid gas in water, for which it has a great affinity. The annexed en- 
 gravings represent the most approved apparatus for this purpose. 
 
 Fig. 1 is a transverse, and Fig. 2 a longitudinal section of a bench of cast- 
 iron retorts a, (generally twenty in number,) resembling those used in gas-works. 
 They are placed in pairs, each pair having a separate fire-place e, grate/, and 
 ash-pit g. Every part of the cylinder should be equally heated, that the decom- 
 position of the salt may be simultaneous, and the iron be as little as possible 
 injured by the acid. For this purpose, a plate of cast-iron, k, is placed between 
 the cylinders ; and the flues h are constructed so as to produce an equal draught 
 throughout every part of the furnace. The cylinders are closed at each end by 
 a plate of cast-iron luted into the rim of the cylinder. Each end plate has a 
 handle b, of cast-iron, and a small tube m, projecting from the upper part of the 
 plate, for the purpose at one end of pouring in the sulphuric acid, and of con- 
 veying away the products at the other. The first cylinder communicates by the 
 bent glass pipe c, with the earthen vessel d, which has three mouths, and which 
 again communicates by two other bent tubes c, with two similar vessels. All the 
 gas not condensed in the first bottle d, passes into the other bottle d ; at the
 
 12 
 
 ACID-NITRIC. 
 
 same time the second bottle d receives the gas from the second cylinder, and 
 transmits the gas which it does not condense to a third bottle, and so on to the 
 last bottle, which receives the gas not condensed in all the others, as also the 
 gas from the last cylinder. From this bottle whatever gas is not condensed is 
 
 Kg. I. 
 
 Fig. 2. 
 
 transmitted through a second range of bottles half nlied with water, which will 
 absorb two-fifths of its weight of- muriatic acid ; and in this second range the 
 whole of the gas is condensed. The first range, it should be observed, is placed 
 in a trough I, through which is maintained a current of cold water. The purest 
 acid is obtained in the second range of bottles ; that which is condensed in the 
 first range containing always a little sulphuric acid, and sometimes sulphate of 
 soda and muriate of iron. Each cylinder is charged with about 160lbs. of com- 
 mor. salt, and the end is luted with clay, and the fire is kindled ; 128lbs. of sul- 
 phuric acid at 66, Baume's areometer, are then poured on the salt. After the 
 gas ceases to come over, the end plate is taken off, the sulphate of soda removed, 
 and the operation repeated : thus ISOlbs. of muriatic acid, of the spec. grav. 1.190, 
 may be obtained from 1 OOlbs. of salt. Muriatic acid, mixed with nitric acid, 
 forms aqua regia, which is a solvent for gold and platinum : it is also used to 
 prepare muriate of tin for dyers, to scour metals, and numerous other purposes. 
 ACID, NITRIC, may be made in various ways, but that most commonly 
 employed is to decompose saltpetre, or nitrate of potash, by concentrated 
 sulphuric acid, in an apparatus similar to that used in the preparation of 
 muriatic acid, except that four cylinders are usually heated by one fire. The 
 cylinders communicate by tubes with three or four rows of earthen vessels, 
 the two first of which are plunged in water. The tubes which proceed from 
 the cylinders must be of glass, that the colour of the gas which passes may be
 
 ACID SULPHURIC. 13 
 
 seen, as it shows the progress of the operation ; the other tubes may be of 
 earthenware. Each cylinder is charged with ITOlbs. of nitrate of potash, and 
 lOOlbs. of sulphuric acid, of 1.845 spec. grav. The heat must be equally applied, 
 and the fire conducted slowly. As the operation advances, the vapours become 
 red ; and it is finished when these vapours are no longer visible : a bnVk fire is 
 made towards the close to disengage all the gas. The acid condensed in the first 
 row of bottles is always the least pure : that contained in the second range and 
 in part ot the third contains only nitrous acid ; this is disengaged by carrying it 
 to ebullition in glass retorts ; the ebullition is gradually stopped when it becomes 
 white, and it is in this state sold in commerce. All the weak acid in the last 
 vessels is again put into the first or second range instead of pure water, and water 
 is always put in the last row to complete the condensation. The acid thus ob- 
 tained is not sufficiently pure for all purposes for which it is wanted, but requires 
 to be distilled in glass retorts, taking care to separate the products. The first 
 portions which are volatilized are chlorine and nitrous acid ; these are separated 
 when the liquor in the retorts becomes white, after which the pure nitric acid 
 comes over. The distillation should be stopped when nine-tenths of the acid in 
 the retort is volatilized. Nitric acid is employed in the manufacture of sulphuric, 
 oxalic, and other acids, in the composition of aqua regia, in making the red pre- 
 cipitate, in dyeing, gilding, assaying money, in parting gold, and numerous other 
 processes. 
 
 ACID, SULPHURIC, is obtained either by simple distillation from copperas, 
 (which was the original method,) or by the combustion of sulphur, in large 
 leaden chambers, in combination with substances yielding a large supply of 
 oxygen ; which is the method generally practised at the present day. The latter 
 process is conducted in various ways; the most usual method in this country is 
 the following. Common brimstone, coarsely ground, is mixed with saltpetre, in 
 the proportion of 8lbs. of the former to lib. of the latter; the mixture is spread 
 upon iron plates set upon stands of lead, in a large chamber, lined with lead, and 
 covered at the bottom with a thin sheet of water. The materials are ignited by 
 means of a hot iron, and the door is closed. The sulphur in vapour, then com- 
 bining with the oxygen of the nitre, forms sulphuric acid, and condenses in the 
 water, which is afterwards drawn off and concentrated, first in leaden vessels, 
 and then in glass retorts (which are sometimes lined internally with platinum); 
 but some manufacturers dispense with the leaden boilers altogether. In some 
 of the more recently established manufactories in France, the following process 
 has been employed with very advantageous results : The sulphur is burned upon 
 an iron plate, set over a furnace, beneath a leaden cylinder, opening into a 
 leaden chamber, containing about 20,000 cubic feet : at the same time, a retort, 
 placed in a sand bath, and containing 9| Ibs. of nitric acid, and 1 J Ib. of molasses, 
 is heated, the nitrous gas disengaged being conducted into the leaden cylinder 
 about 2 feet above the burning sulphur, and this operation being continued 
 until all the nitrous gas is disengaged. From the residue in the retort oxalic 
 acid is ottained. About two hours after the combustion has commenced, steam 
 is admitted into the chamber by a pipe, which enters about the middle of the 
 chamber. Soon after the introduction of the steam, a condensation is perceived 
 in the chamber, and a small hole is opened to admit a supply of atmospheric 
 air. When the condensation is completed, which is commonly in about three 
 hours' time from the commencement of the operation, a door in the cylinder, 
 and two valves placed under a tall chimney, are opened, in order to renew the 
 air in the chamber, after which the operation may be repeated. The bottom of 
 the chamber should always be covered with liquid, and it is inclined to the hori- 
 zon, so that the liquid may be 9 inches deep at one end, and only 1^ at the other, 
 and only the overplus is drawn off daily. The acid may be concentrated in the 
 chambers to about 1.450 spec. grav. ; after which it is removed to leaden boilers, 
 and brought to a spec. grav. of 1.600; the remaining requisite concentration 
 is effected in glass and platinum retorts. A quantity of acid comes over during 
 the evaporation, which is condensed by a leaden worm fixed to the neck of the 
 retort. The annexed cut represents the apparatus employed in this process. 
 a la a portion of the chamber lined with lead ; 6 the leaden cylinder entering
 
 ADHESION. 
 
 over a furnace I. m is a door in the leaden cylinder, and w, an air-hole in the 
 door, fitted with a stopper; r, a glass mattress, containing the nitric acid and 
 molasses; s, the steam boiler ; f, the steam pipe. Sulphuric acid is very exten- 
 sively used in the chemical arts, particularly in bleaching, and some of the 
 processes of dyeing; in the manufacture of the nitric and muriatic acids, and in 
 numerous other brandies of manufacture. The combinations of this acid with 
 various bases are called sulphates, many of which are of great utility in 
 medicine and the arts. The acidulous sulphate of alumina, combined with 
 potash or ammonia, forms the important article called ALUM, which see. 
 
 ACRE. A measure of land, amounting to 4 square roods, or 160 square 
 poles or perches. The English statute acre is about 3 roods and 6 falls standard 
 measure of Scotland. The Welsh acre contains commonly 2 English ones. The 
 Irish acre is equal to 1 acre 2 roods and 19^/ T perches English. The number 
 of acres in England, according to Dr. Grew, amounts to 46,080,000. 
 
 ADAMANT. The ancient name of the diamond. This term is also sometimes 
 applied to the scoriae of gold, and to a species of iron ore. 
 
 ADAMANTINE SPAR. There are two varieties of this important mineral 
 known in Europe, one of which is brought from China, the other from India. 
 They are both remarkable for their extreme hardness, which approaches to that 
 of the diamond, anC are therefore used in polishing gems and steel. In India, 
 corundum powder i* formed into a paste with lac resin, and moulded into 
 grindstones of a very durable nature. 
 
 ADHESION denotes a union, to a certain degree, between two distinct 
 substances, and differs from cohesion, (with which the former word is often con- 
 founded,) inasmuch, as the latter term is alone properly applicable to the retaining 
 together of the component particles of the same mass. Adhesion is, however,
 
 ADHESION. 
 
 15 
 
 of two kinds ; the one, a species '61 natural attraction, which takes place between 
 the surfaces of bodies, whether similar or dissimilar, and which, in a certain 
 degree, connects them together ; the other, the joining or fastening together ot 
 two or more bodies, by the application of external force. With respect to the 
 first-mentioned, it has been proved, that the power of adhesion is proportionate 
 to the number of touching points ; and this, in solid bodies, depends upon the 
 degree in which their surfaces are polished and compressed. The effects of this 
 power are extremely curious, and in many instances astonishing. It is stated 
 by Musschenbroek, that two cylinders of glass, of rather less than 2 inches 
 diameter, being heated to the temperature of boiling water, and brought into 
 contact, with melted tallow between their surfaces, required a force of 130 Ibs. 
 to separate them ; pieces of lead, of the same area of surface, required 275 
 Ibs. ; and soft iron, 300 Ibs. The experiments made and described by 
 Mr. Martin, in the Philosophla Britannica, make the force of this kind of 
 adhesion much greater than Musschenbroek. He took two leaden balls, and 
 having carefully scraped off, with the edge of a sharp pen-knife, so much of 
 their spherical surfaces as to form two planes of one-thirtieth of an inch in 
 area, he pressed them together forcibly, and with a gentle turn of the hand. 
 The adhesion of these small surfaces was such, that he lifted, with the balls so 
 united, above 150 Ibs. weight. The adhesion between two brass planes 4^ 
 inches in diameter, with grease smeared over their surfaces, was such, that he 
 could never meet with two men strong enough to separate them by pulling 
 against each other. The editor of this work had put into his hand many years 
 ago two brass plates, of about 2 inches diameter, having their surfaces so per- 
 fectly flat, that, without any interposing matter, he could only separate them by 
 sliding them edgeways. With respect to the second-mentioned kind of adhesion, 
 some useful experiments were made by Mr. B. Bevan, on the adhesive force of 
 iron nails, screws, and pins ; also of the common cements, glue, and sealing- 
 wax, which that gentleman communicated to the editor of the London Mecha- 
 nics' Magazine. The following is a condensed account of them : 
 
 ADHESION OF IRON NAILS, in which Mr. Bevan's object was to determine, 
 first, the adhesive force of different kinds of nails, when driven into wood of 
 different species : second, the actual weight, without impulse, necessary to force 
 a nail a given depth; third, the force requisite to extract a nail when so driven. 
 Mr. Bevan observes, that the theoretical investigation points out an inequality 
 of resistance to the entrance and extraction of a nail, supposing the thickness 
 to be invariable ; but as the general shape of nails is tapering towards their 
 points, the resistance of entrance necessarily becomes greater than that of 
 extraction ; in some experiments he found the ratio to be about 6 to 5. The 
 following Table exhibits the relative adhesion of nails of various kinds when 
 driven into dry Christiana deal, at right angles to the grain of the wood. 
 
 Description of Nails used. 
 
 Number 
 to the Ib. 
 avoirdupois. 
 
 Inches long. 
 
 Inches 
 forced into 
 the wood. 
 
 Pounds 
 required to 
 extract. 
 
 Fine s ii-s 
 
 4560 
 
 044 
 
 40 
 
 22 
 
 Ditto 
 
 3200 
 
 0.53 
 
 044 
 
 37 
 
 Threepenny brails 
 Cast-iron nails 
 Sixpenny nails 
 Ditto 
 
 618 
 380 
 73 
 
 1.25 
 1.00 
 2.50 
 
 0.50 
 0.50 
 1.00 
 1 50 
 
 58 
 72 
 187 
 327 
 
 Ditto 
 
 
 
 200 
 
 530 
 
 Fivepenny nails 
 
 139 
 
 2.00 
 
 1.50 
 
 320 
 
 
 
 
 
 
 The percussive force required to drive the common sixpenny nail to the depth 
 of 1$ inch into dry Christiana deal, with a cast-iron weight of 6.275 Ibs. was 
 four blows or strokes falling freely the space of 12 inches; and the steady 
 pressure to produce the same effect, was 400 Ibs. A sixpenny nail driven
 
 16 ADHESION. 
 
 into dry elm, to the depth of one inch across the grain, required a pressure of 
 3->7 Ibs. to extract it ; and the same nail driven endways or longitudinally into 
 the same wood, was extracted with a force of 257 Ibs. The same nail driven 
 2 inches endways into dry Christiana deal, was drawn by a force ot 2a7 Ibs. ; 
 and to draw out 1 inch, under like circumstances, took 87 Ibs. only. 1 he 
 relative adhesion, therefore, in the same wood, when driven transversely and 
 longitudinally, is 100 to 78, or about 4 to 3 in dry elm, and 100 to 46, or about 
 2 to 1 in deal ; and in like circumstances, the relative adhesion to elm and 
 deal is as 2 or 3 to 1. The progressive depths of a sixpenny nail into dry 
 Christiana deal, by simple pressure, were as follows : 
 
 One quarter of an inch, a pressure of . . - 24 Ibs. 
 
 Half an inch 76 
 
 One inch 235 
 
 One inch and a half 400 
 
 Two inches 610 
 
 In the above experiments, great care was taken by Mr. Bevan to apply the 
 weights steadily, and towards the conclusion of each experiment, the additions 
 did'not exceed 10 Ibs. at one time, with a moderate interval between, generally 
 about one minute, sometimes ten or twenty minutes. In other species of wood, 
 the requisite force to extract the nail was different. Thus, to extract a common 
 sixpenny nail, from a depth of one inch, out of 
 
 Dry oak, required 507 Ibs. 
 
 Dry beech 667 
 
 Green sycamore 312 ,, 
 
 From these experiments, we may infer that a common sixpenny nail driven 
 two inches into dry oak, would require a force of more than half a ton to extract 
 it by a steady force. 
 
 ADHESION OF IRON PINS. The force necessary to break or tear out a half-inch 
 iron pin, applied in the manner of a pin to a tenon in the mortice, has likewise 
 obtained the attention of the same celebrated experimentalist. The thickness 
 of the board was 0.87 inch, and the distance of the centre of the hole from the 
 end of the board, 1.05 inch. The force required was 976 Ibs. As the strength of 
 a tenon from the pin-hole may be considered to be in proportion to the distance 
 from the end, and also as the thickness, we may, for this species of wood, obtain 
 the breaking force in pounds nearly, by multiplying together one thousand times 
 the distance of the hole from the end, by the thickness of the tenon in inches. 
 
 ADHESION OF GLUE. Mr. Bevan glued together by the ends two cylinders 
 of dry ash wood, one-fifth of an inch in diameter, and about 8 inches long. 
 After they had been glued together twenty-four hours, they required a force of 
 1260lbs. to separate them ; and as the areas of the circular ends of the cylinders 
 were 1.76 inch, it follows that the force of 715 Ibs. would be required to separate 
 one square inch. It is proper to observe, that the glue used in this experiment 
 was newly made, and the season very dry ; for in some former experiments on 
 this substance, made in the winter season, and upon some glue which had been 
 frequently made, with occasional additions of glue and water, he obtained a 
 result of 350 to 500 Ibs. to the square inch. The present experiment was, how- 
 ever, conducted upon a larger scale, and with care in the direction of the resultant 
 force, so that it might be, as near as practicable, in a line passing at right angles 
 through the centre of the surfaces in contact. The pressure was gradually 
 applied, and was sustained two or three minutes before the separation took place. 
 Upon examining the separated surfaces, the glue appeared to be very thin, and 
 did not entirely cover the wood, so that the actual adhesion of glue must be 
 something greater than 715 Ibs. to the square inch. Upon comparing with this, 
 the natural cohesive force laterally of wood of the same kind, Mr. Bevan found 
 it to be only 562lbs. : consequently, if two pieces of this wood were well glued 
 together, the wood would have yielded in its substance before the glue. From 
 a subsequent experiment made on solid glue, the cohesive force was found to be 
 4,000 Ibs. per square inch; from which it may be inferred, that the application 
 of this substance as a cement is susceptible of improvement.
 
 AERATED WATERS. 
 
 17 
 
 ADHESION OF SEALING-WAX. The best red sealing-wax was proved to have 
 a cohesive force equal to l,500lbs. per square inch, aud the black sealing-wax 
 was rather more than 1,000 Ibs. to the square inch ; the deficiency in the latter, 
 we suppose, was owing to the diminished quantity of lac resin used in the 
 composition. 
 
 AEOLIAN HARP, or harp of jEolus, is a musical instrument, which pro- 
 bably received its name from the effects produced upon it by the air without 
 human aid. It consists of a slight box of fibrous wood, usually deal, containing 
 a low bridge at each end, over which is stretched, upon pegs, a series of fine 
 cat-gut strings, generally about fifteen in number, which, being of equal size 
 and length, are therefore unisons. Its length should correspond with the size 
 of the window or other aperture where it may be placed ; its width need not be 
 more than from 4 to 6 inches, and in depth from 3 to 4 inches. It should be 
 placed between the lower sash and sill of a window, with its strings uppermost, 
 under which is a circular opening, as in the belly of the guitar. When the 
 wind blows athwart the strings, it produces the effect of a choir of music in the 
 air, swelling or diminishing its sounds according to the strength or weakness of 
 the blast. 
 
 -iEOLIPILE. A name that has been given to an instrument variously 
 modified, for converting in a close vessel water into steam. The first individual 
 who used it, appears to have been Hero the elder, a Grecian mechanic, who 
 settled in Alexandria about 130 years prior to the Christian era, whose ingenuity 
 and talents being fostered by the Egyptian monarch, was the probable cause of 
 his interesting discoveries being handed down to us in his work entitled Spiri- 
 talia, or Pneumatica. Although in the state that he has presented it to us in 
 his seolipile, it cannot be regarded as one of his most useful inventions, (his foun- 
 tain for raising water by compressed air possessing far more intrinsic merit,) 
 still as being the earliest germ of that great mechanic power which seems 
 destined to change the face of the entire civilized world, it is well deserving of 
 a description in this place, which we shall give with reference to the subjoined 
 figure. Over a small furnace was 
 placed a vase or caldron a, containing 
 water, from the cover of which pro- 
 ceeded two arms b c, forming the axis 
 of a hollow globe d. The arm b is a 
 .'team pipe, the other arm c is solid, 
 having its extremity formed into a 
 conical pivot. At right angles to the 
 axis of the hollow globe, there pro- 
 ceed from it two tubes ee, bent at their 
 extremities, which form the outlets of 
 the steam. Heat being applied to the 
 caldron, raises the steam, which flow- 
 ing through the tubular axis b, enters 
 the globe ; thence the steam finds its 
 way through the tubes e e into the 
 atmosphere, the reaction of the latter 
 producing a rotatory motion of the 
 globe, the velocity of which will de- 
 pend upon the strength of the steam. ' 
 
 AERATED WATERS. This term being popularly applied to a variety of 
 acidulous and alkaline beverages more or less impregnated with fixed air, or 
 carbonic acid gas, we introduce our article on the subject in this place; and as 
 the manufacture of these liquids has of late years become of considerable extent, 
 owing to their agreeable as well as medicinal properties, we purpose describing 
 
 everal ingenious apparatuses that have been used, or are still employed, for the 
 purpose. Water absorbs under the natural pressure of the atmosphere about 
 its own bulk or volume of carbonic acid gas. If a pressure be applied equal to 
 two atmospheres, the water will absorb double its own volume, its absorbing 
 power increasing as the pressure. Water thus impregnated acquires a pleasant
 
 18 
 
 AERATED WATERS. 
 
 acid taste, to which is usually added a small quantity of potash or soda, and 
 
 such flavouring or other ingredients as may be required to imitate the natural 
 
 mineral waters. Noottis apparatus was one of the earliest contrivances, and is 
 
 adapted to the preparation of smallquantitiea of aerated 
 
 water. It is represented in the subjoined cut, and 
 
 consists of three vessels ; the lowest a, is flat and 
 
 broad, so as to form a good basis ; in this is put a quan- 
 tity of chalk or pounded marble, and some dilute 
 
 muriatic or other acid is introduced through a screwed 
 
 stopper b. The gas being thus generated, passes 
 
 through the tube c, in which a glass valve opens up- 
 wards into d, which contains the water or solution to 
 
 be impregnated, and is provided with a stop-cock to 
 
 draw off the liquid. The tube of the uppermost 
 
 vessel e, dips into d, occasioning therein some pressure; 
 
 and the gas which is not absorbed in the latter, passes 
 
 up into e, which being provided with a heavy stopper, 
 
 acts as a valve, and causes a considerable pressure of 
 
 the gas upon the water within it. The gas which is 
 
 not absorbed by the water in c or d, escapes by the 
 aperture at top. Another apparatus of great simpli- 
 city, and adapted to operating upon a more extended 1 ' 
 scale, is delineated in the following cut. 
 
 A is a strong plank on which the vessels are fixed ; B is a bottle, containing 
 a quantity of pulverised carbonate of lime or chalk ; C is the tubulure and 
 stopper of the bottle; D a bent tube for conveying the gas into the bellows E, 
 which are supported by the upright stand F; G is a stop-cock connected with 
 the tube D, which passes^ from thence into the strong iron-hooped air-tight 
 barrel H, suspended by its axis on the upright pillars I I. In using this 
 apparatus, the cask is to be half filled with distilled or spring water- the 
 
 ofeo 
 
 and secured by a bolt or key
 
 AERATED WATERS. l9 
 
 weight of water, over the chalk, and close the aperture by the screw-stopper C. 
 Having taken off* the weight from the bellows, the carbonic acid extricated 
 from the chalk by the action of the acid passes out of the bottle into the 
 bellows through the tube D, which has an orifice opening under them. When 
 the bellows are fully distended, the cock G is to be turned, and the weight 
 being placed upon the bellows, the gas is thereby pressed downwards into the 
 barrel, and is there absorbed by the water, which is accelerated by giving the 
 barrel a few quick turns by the winch J. The contents of the barrel may then 
 be drawn off into stone bottles, which should be quickly corked, and bound 
 down with copper wire, to be preserved for use. 
 
 A very complete machine, invented by Mr. Cameron, of Glasgow, calculated 
 to offer a strong resistance to the pressure of the gas, and force a considerable 
 quantity into water, is shown below. The gas generator a, is made of cast 
 iron, three quarters of an inch thick, and lined interiorly with sheet lead, 
 (of 9lbs. weight to the foot,) to prevent the action of the acid upon the iron. 
 This vessel contains about 15 gallons, and is filled up to the dotted linebya mixture 
 of whiting and water; it has an agitator b, also lined with sheet lead, and which 
 works on a pivot at the bottom, the axis passing through the stuffing-box c, at 
 the top of the vessel. The acid holder e, is formed of lead, of the capacity of two 
 gallons, and is filled with oil of vitriol up to the dotted line. The acid is kept from 
 running down into the generator by means of the conical plug /, which fits into 
 a conical opening in the leaden pipe g. This plug is attached to a rod, and 
 moves up and down through the stuffing-box h, and is prevented from turning 
 
 round by means of a pin Ic, moving in a slit in the bridle I, and the screw-nut m 
 is riveted loose into the top of the bridle. The pipe n, which forms a com- 
 munication between the top of the acid-holder e, and the pipe s, in which the 
 plug-rod moves, preserves an equilibrium of pressure, so as to prevent the acid
 
 20 AERATED WATERS. 
 
 from rising higher in the pipe s than the level of the acid in the acid-holder, 
 by which means the brass work of the stuffing-box is preserved from injury. 
 To prevent any of the sulphuric acid frombeing carried over by the effervescence, 
 an intermediate vessel o, containing about three gallons, is formed either of thick 
 sheet lead alone, or of cast iron, lined with lead. This intermediate vessel is 
 filled with water up to the dotted line. The impregnator v should contain 
 about 16 gallons. It may be made either of copper tinned, or of cast iron, 
 lined with sheet-lead; and the agitator m may either be of tinned copper, or of 
 maple-wood ; which last, giving no taste to the water, is for that reason pre- 
 fc'able. This impregnator is filled up to the dotted line with water, to which, 
 in making saline waters, the proper proportion of sesqui-carbonate of soda, 
 carbonate of magnesia, or other ingredient, is to be added. A pressure-gauge 
 t, of quicksilver, is to be placed at a little distance, and connected by means of 
 a leaden pipe. The operation of this apparatus is very simple. By turning the 
 nut m the plug is raised, allowing the sulphuric acid to run down into the 
 generator a, where it acts upon the whiting, disengaging the carbonic acid gas 
 in proportion to the quantity of sulphuric acid admitted at a time. The nut m 
 being turned the other way, lowers the plug, and stops the descent of the sul- 
 phuric acid, thus regulating the disengagement of the gas, and preventing too 
 violent an effervescence. The disengaged gas passes through the intermediate 
 vessel into the impregnator v, where it is absorbed by the water. The impreg- 
 nated water is then drawn off into strong half-pint bottles, by means of a cock, 
 which descends to the bottom of the bottle; on withdrawing the bottle, it should 
 be instantly corked, and the corks be wired or tied down. 
 
 A patent has just been granted to Mr. F. C. Bakewell, of Hampstead, for a 
 very compact and ingenious apparatus for the preparation of aerated waters, the 
 peculiarity of which consists in the gas-generating and the gas-impregnating 
 apparatus being inclosed in the same vessel, and in the whole operation being 
 effected by a simple oscillating motion. A correct idea of this machine may 
 be formed by the annexed figure, (representing a vertical section of its principal 
 
 parts,) together with the subjoined explanation, a a exhibits an external section 
 a cylindrical form, with spherical ends, made strong enough to resist the pros-
 
 AEROSTATION. 21 
 
 sure of several atmospheres ; b is a partition, about two-thirds from the top of 
 the vessel, separating it into two parts. The bottom part c is a receptable for 
 the chalk, or other suitable material, mixed into a pasty consistency with water; 
 d is a vessel containing dilute muriatic or sulphuric acid, which is made to pass 
 out in small quantities, as required, at the aperture e into the vessel c ; / is a 
 guard to prevent the aperture e from being choked up; g is a pipe, of the form 
 of a truncated cone inverted, being about an inch diameter at bottom, and two 
 inches at the top. This pipe is fitted into an aperture in the partition b, and is 
 closed at the upper end ; its object is for the ascent of the gas as it is generated, 
 which passes from the top down an external pipe, into the lower part i of a 
 vessel k, and through a small aperture the tenth of an inch diameter, (or through 
 several apertures whose total areas do not exceed the tenth of an inch,) through 
 the partition into the upper part of the vessel h. This vessel, which is deno- 
 minated the washing vessel, is furnished with two shelves, sloping in opposite 
 directions near its top, to detain the gas longer in its passage through the aper- 
 ture to an external pipe, furnished with a perforated rose, for distributing the 
 gas as it escapes into the water to be impregnated, contained in the vessels oo; r 
 p is a stop-cock for drawing off the impregnated water as required ; q is an 
 aperture for the introduction of the chalk and water; r, another for the intro- 
 duction of the acid ; and *, another for the water to be aerated : each of- these 
 apertures is provided with a screwed cap, to stop them securely after the re- 
 spective vessels have been charged. The apparatus is made to swing on two 
 pivots, one of which is shown in section at t. When the chalk and acid recep- 
 tacles are to be supplied with those ingredients, the apparatus is to be turned 
 on its pivots to a horizontal position, with the aperture r upwards, and a funnel 
 or hopper, with a bent stem, is to be employed in filling the vessel c c', n is an 
 end view of a pendulum or agitator, of the form of an arc of a circle, ex- 
 tending across tlie bottom of the vessel, and suspended at its two extremities; 
 one of the suspension wires is shown in the drawing. The apparatus having 
 been charged as above described, it is to be put into vibration on its pivots, by 
 which thegchalk and water will be effectively agitated by the motion of the 
 pendulum, while a small portion of acid will escape from the vessel d into the 
 vessel e, to keep up the generation of the gas as it passes off to the water in a, 
 which will, at the same time, by the vibration of the apparatus, be thoroughly 
 mixed with the gas as it escapes through the rose n. An elegant apparatus, 
 adapted for saturating liquids with the carbonic acid, as well as other gases, 
 was invented by M. Clement, for which see the article ABSORBING AND PRO- 
 DUCTIVE CASCADE. Some manufacturers of aerated waters employ mechanical 
 means to force the gas into the water, by the use of a transferring pump or 
 syringe, which is connected at one end with a bladder, or other reservoir of the 
 gas, and at the other, with a vessel, or single bottle of water ; the up-stroke of 
 the pump extracting the gas from the bladder, and the down-stroke transferring 
 it into the water. 
 
 AEROMETER. An instrument, to which this name has been given by the 
 inventor, Dr. M. Hall, for making the necessary corrections in pneumatic ex- 
 periments to ascertain the mean bulk of the gases. It consists of a bulb of 
 glass, of^ 4r| cubic inches capacity, blown at the end of a long tube, whose 
 capacity* is 1 cubic inch. This tube is inserted into another tube of nearly 
 equal length, which is supported on a sole ; and the first tube is sustained at 
 any required height within the second by the pressure of a spring. Five cubic 
 inches of atmospheric air, at a medium pressure and temperature, are to be 
 introduced into the bulb and tube, of the latter of which it will occupy one- 
 half. The other half of this tube, and part of the tube in which it is inserted, 
 are to be occupied by the fluid of the pneumatic trough, whether water or 
 mercury. The point of the tube at which the air and fluid meet, is to be marked 
 by the figure 5, to denote 5 cubic inches. The upper and lower halves of the 
 tubes are each divided into five parts, representing tenths of a cubic inch. The 
 external tube has a scale, of inches attached. 
 
 AEROSTATION. The art of navigating the air in aerostatic machines. 
 See BALLOONS.
 
 22 AGRICULTURE. 
 
 AGATE. A mineral whose basis is calcedony, blended with variable pro- 
 portions of jasper, amethyst, quartz, opal, heliotrope, and carnelian. Ribbon 
 agate consists of alterate and parallel layers of calcedony with jasper, or quartz, 
 or amethyst. The most beautiful comes from Liberia and Saxony ; it occurs 
 in porphyry and gneiss. Brecciated agate is of Saxon origin ; it has a base of 
 amethyst, containing fragments of ribbon agate, constituting the beautiful 
 variety. Fortification agate, found in Scotland and on the Rhine, is in nodules 
 of various shapes, imbedded in amygdaloid. On cutting it across, and 
 polishing it, the interior zig-zag parallel lines bear a considerable resemblance 
 to the plan of a modern fortification. In the very centre, quartz and amethyst 
 are seen in a splintery mass, surrounded by the jasper and calcedony. Mocha 
 stone, from Mocha, in Arabia, where it is chiefly found, is translucent calcedony, 
 containing dark outlines of arborization, like vegetable filaments. Moss agate, 
 so called from its ramifications of a vegetable form, is a calcedony, variously 
 coloured, and occasionally traversed with irregular veins of red jasper. An 
 onyx agate set in a ring belonging to the earl of Powis contains the chrysalis 
 of a moth. Agate is found in most countries, chiefly in trap rocks and serpen- 
 tine, The oriental agate is almost transparent, and of a vitreous appearance, 
 The occidental is of various colours, and often veined with quartz or jasper. 
 Agates are most prized when the internal figure nearly resembles some animal 
 or plant. Agates are artificially coloured by immersion in metallic solutions. 
 They are extensively used in Paris for making cups, rings, seals, handles for 
 knives and forks, sword-hilts, beads, smelling-bottles, snuff-boxes, &c. At 
 Oberstein, on the Rhine, where the stones are abundant, they are cut and 
 polished on a considerable scale, and at a very moderate price. The surface to 
 be polished is first coarsely ground by large millstones of a hard reddish sand- 
 stone, moved by water. The polish is afterwards given on a wheel of.soft wood, 
 moistened and imbued with a fine powder of hard red tripoli, found in the 
 neighbourhood. Antiquaries use the term agate to denote a stone of the kind 
 engraved by art. In this sense agates make a species of antique gems, in the 
 workmanship of which we find eminent proofs of the great skill and dexterity 
 of the sculptor. Several agates of exquisite beauty are preserved in the cabinets 
 of the curious. 
 
 AGRICULTURE is the art of cultivating the earth, so as to preserve and 
 increase the natural fertility of the soil, as well as to render sterile tracts pro- 
 ductive of vegetation useful to man ; and the perfection of this art may be said 
 to consist in obtaining the greatest quantity of the required product from a 
 given quantity of land at the least possible expense of labour and material. 
 Besides the production of grain and leguminous plants, which usually forms the 
 chief business of the farmer, agriculture includes the culture of trees, and 
 every description of plants; their planting, pruning, grafting, &c. ; hence 
 horticulture, or gardening, is a branch of this art. It includes also the breeding 
 and management of cattle, since their manure and their labour are essential to 
 the business of husbandry. Nothing would tend more to the successful practice 
 of this the most important of all arts than the study of chemistry by the farmers. 
 If a soil be unproductive, it must be owing to some defect in its constitution] 
 which may not be apparent even to the eye of the most experienced hus- 
 bandrnan. Not all his observation, nor all his practice, without the aid of 
 chemical knowledge, will afford him any means either of ascertaining the cause 
 
 , 
 
 clay and calcareous matter will improve it ; if vegetable matter be in excess 
 liming or paring and burning, will be advantageous. The excellent rules laid 
 down by Sir Humphry Davy, in his Agricultural Chemistry, are particularly 
 deserving of attention. In cases where a barren soil is examined with a 
 view to its improvement it ought, if possible, to be compared with an 
 extremely fertile so, in the neighbourhood, and in a similar situation. The 
 difference given by their analyses would indicate the methods of cultivation and 
 thus the plan of improvement would be founded upon accurate scientific Win
 
 AGRICULTURE. 23 
 
 ciples. If the fertile soil contained a large quantity of sand in proportion to the 
 barren soil, the process of melioration would depend simply upon a supply of 
 this substance ; and the method would be equally simple with regard to soils 
 deficient in clay or calcareous matter. In the application of clay, sand, loam, marl. 
 or chalk, to lands, there are no particular chemical principles to be observed ; but 
 when quick-lime is used, great care must be taken that it is not obtained from 
 the magnesian limestone, for in this case, as has been shown by Mr. Tennant, 
 it is exceedingly injurious to land. The magnesian Ihnestone may be distin- 
 guished from the common limestone by its greater hardness, and by the length 
 of time that it requires for its solution in acids; and it may be analyzed by the 
 process for carbonate of lime and magnesia. When the analytical comparison 
 indicates an excess of vegetable matter as the cause of sterility, it may be 
 destroyed by much pulverization and exposure to air, by paring and burning, 
 
 or the agency of recently made quick-lime. The deficiency of either animal or 
 vegetable matter must, of course, be supplied by animal or vegetable manure. 
 The general indications of fertility and barrenness, as found by chemical expe- 
 
 riments, must necessarily differ in different climates and under different cir- 
 cumstances. The power of soils to absorb moisture, a principle essential to 
 their productiveness, ought to be much greater in warm and dry countries than 
 in cold and moist ones; and the quantity of fine aluminous earth they contain 
 should be larger. Soils, likewise, that are situated on declivities, ought to be 
 more absorbent than those in the same climate on plains or in valleys. The pro- 
 ductiveness of soils must likewise be influenced by the nature of the subsoils, 
 or the earthy or stony strata on which they rest ; and this circumstance ought 
 to be particularly attended to in considering their chemical nature and the 
 system of improvement. Thus, a sandy soil may owe its fertility to the power 
 of the subsoil to retain water ; and an absorbent clayey soil may occasionally 
 be prevented from being barren in a moist climate by the influence of a sub- 
 stratum of sand or gravel. Those soils that are most productive of corn contain 
 always certain proportions of aluminous or calcareous earth in a finely-divided 
 state, and a certain quantity of vegetable or animal matter. The quantity of 
 calcareous earth is, however, very various, and, in some cases, exceedingly small. 
 A very fertile corn soil from Ormesten, in East Lothian, afforded in 100 parts 
 only 11 parts of fine calcareous earth ; the finely-divided clay amounting to 45 
 parts. It lost 9 parts in decomposed animal and vegetable matter, and 4 in 
 water, and exhibited indications of a small quantity of phosphate of lime. This 
 soil was of a very fine texture, and contained very few stones and vegetable 
 fibres. It is not unlikely that its fertility was in some measure connected with 
 the phosphate, for this substance is found in wheat, oats, and barley, and may 
 be a part of their food. A soil from the lowlands of Somersetshire, celebrated 
 for producing excellent crops of wheat and beans without manure, Sir Humphry 
 Davy found to consist of one-ninth of sand, chiefly silicious, and eight-ninths 
 of calcareous marl, tinged with iron, and containing about five parts in the 
 hundred of vegetable matter. He could not detect in it any phosphate or 
 sulphate of lime, so that its fertility must have depended principally upon its 
 power of attracting principles of vegetable nourishment from water and the 
 atmosphere. In some experiments made by Mr. Tillet on the composition of 
 soils about Paris, he found that a soil, composed of three-eighths of clay, two- 
 eighths of river sand, and three-eighths of the parings of limestone, was very 
 proper for wheat. In general, bulbous roots require a soil much more sandy 
 and absorbent than the grasses. A very good potato soil, from Varsel, in 
 Cornwall, afforded seven-eighths of silicious sand, and its absorbent power was 
 so small that 100 parts lost only 2 by drying at 400 Fahrenheit. Plants and 
 trees, the roots of which are fibrous and hard, and capable of penetrating deeply 
 into the earth, will vegetate to advantage in almost all common soils that are 
 moderately dry, and do not contain a very great excess of vegetable matter. 
 The soil taken from a field at Sheffield-place, in Sussex, remarkable for pro- 
 ducing flourishing oats, was found to consist of 6 parts of sand, and 1 part of 
 clay and finely divided matter; and 100 parts of the entire soil, submitted to 
 analysis, produced water, 3; silex. 54; alumina, 28 ; carbonate of lime, 3;
 
 24 AIR ATMOSPHERIC. 
 
 oxide of iron, 5 ; decomposing vegetable matter, 4 ; loss, 3. From the great 
 difference of the causes that influence the productiveness of lands, it is obvious, 
 that in the present state of science no certain system can be devised for their 
 improvement, independent of experiment ; but there are few cases in which the 
 labour of analytical trials will not be amply repaid by the certainty with which 
 they denote the best methods of melioration ; and this will particularly happen, 
 when the defect of composition is found in the proportions of the primitive 
 earths. In supplying animal or vegetable manure, a temporary food only is 
 provided for plants, which is in all cases exhausted by means of a certain 
 number of crops ; but when a soil is rendered of the best possible constitution 
 and texture, with regard to its earthy parts, its fertility may be considered as 
 
 ermanently established. It becomes capable of attracting a very large portion 
 of vegetable nourishment from the atmosphere, and of producing its crops with 
 comparatively little labour and expense. For the mode of proceeding, and the 
 instruments required in making analytical experiments on soils, we can refer 
 the reader to the before-mentioned work of the late illustrious chemist ; very 
 accurate information on this subject will, however, be found in Dr. Ure's ex- 
 cellent Dictionary of Chemistry. But to those whose business it may be to 
 pursue this most important of studies in all its interesting details, we strongly 
 recommend the perusal of the articles AGRICULTURE in the Oxford Encyclopaedia 
 and Supplement, which form together an elaborate compendium of the best 
 works on the subject in the English language, enriched throughout by thejudi- 
 cious observations of its learned editors. 
 
 AIR, ATMOSPHERIC. From the remotest antiquity, until a comparatively 
 recent period, the air was considered as one of the four elements of which all 
 things were compounded; and it was generally held to be an invisible, impon- 
 derable, and simple substance. Some of the ancients, it is true, had vague 
 notions of its gravitating power and of its elasticity ; amongst others may be 
 mentioned Aristotle, who says, that a bladder filled with air weighs more than 
 when quite empty; and Hero also says, that the air, in a given cavity, may be 
 rarefied by sucking out a part of it ; but still their ideas were very imperfect, 
 and their opinions were abandoned by their followers, for various absurd hypo- 
 theses by which they attempted to account for the phenomena produced by the 
 acticn of the atmosphere. It was not until near the middle of the seventeenth 
 century, that the real nature and properties of the atmosphere were ascertained 
 with precision and confirmed by experiment. For these discoveries we are 
 principally indebted to Galileo, and his pupil Torricelli. Galileo taught that 
 the air had weight, but does not appear to have applied this idea to explain 
 those pneumatic phenomena which were then absurdly attributed to an imagi- 
 nary principle of nature, termed a horror of a void : but Torricelli, following up 
 the principle, showed, by incontrovertible experiment, that the rise of fluids in 
 pumps was owing to the pressure of the atmosphere, and that the height to 
 which fluids would rise in vacua, was exactly proportionate to their weight, 
 which would, in all cases, be exactly equal to a column of air of the same base 
 and of the height of the atmosphere. These great principles were successfully 
 followed up by various eminent philosophers, and numerous important con- 
 clusions and useful applications of them were the result. Towards the close of 
 the eighteenth century, the air was discovered to be a compound of two gases, 
 to which the names of oxygen and azote were given, and this discovery aerved 
 as the basis of the modern system of chemistry, which has been so fertile in 
 brilliant scientific results. Under the articles CHEMISTRY and PNEUMATICS 
 will be found the demonstrations of the chemical and physical properties of the 
 atmosphere ; we shall, therefore, in this place, merely state what are its prin- 
 cipal characteristics, and the uses to which they are made subservient in many 
 processes of the arts and manufactures. Air, then, is an invisible elastic and 
 ponderable gaseous fluid, its bulk and density depending upon its temperature 
 and the pressure to which it is exposed. Under a pressure of 30 inches of 
 mercury, and at a temperature of 60 Fahrenheit, its spec. grav. as ascertained 
 with great care and accuracy by Messrs. Aragoand Biot, is .00122, water being 
 ] 0.0000, or it is 820 times higher than water; and if we take a cubit inch of
 
 AIR-GUN. 
 
 23 
 
 water to weigh 252.525 grains, then 100 cubic inches of air will weigh 30.080 
 grains, and a cubic foot will weigh 532.36 grains. Mariotte ascertained thut 
 its bulk is inversely as the pressure, a double pressure reducing a given volume 
 to half its bulk. The applicability of this law to air under very great pressure 
 has been questioned, but not satisfactorily disproved ; and for all practical pur- 
 poses it may be safely received ; whilst, from its simplicity, it may be remem- 
 bered with ease and applied with facility. Air expands by an increase of 
 temperature, the rate of expansion is not exactly equal for equal increments 
 of heat, but on an average, the increase of bulk above 32 Fahrenheit is ^|^ of 
 its bulk, for each degree of heat on the same scale. The expansion or rare- 
 faction of air is accompanied by a decrease of its temperature, and in its conden- 
 sation or compression it gives out a proportional quantity of heat Air can take 
 up and hold in solution a portion of water depending upon the temperature. 
 
 AIR-BEDS. A bag of the size of a bed, divided into several compartments, 
 and rendered air-tight by a composition, of which caoutchouc, or Indian-rubber, 
 forms the greatest part. This bag may be inflated by bellows, a syringe, or any 
 other means, and is furnished with stop-cocks to retain the air or let it out at 
 pleasure. These beds will be found extremely convenient to travellers, espe- 
 cially in warm climates, from their portability, and not being liable to vermin; 
 also to invalids, from their perfect elasticity, which maybe regulated at pleasure 
 by an attendant without disturbing the occupant. 
 
 AIR-FOUNTAIN. There are two kinds of fountains produced by the 
 elastic pressure of the air. One consists in compressing the air in a close vessel, 
 and causing it to act on the surface of the water -as in the force pump. The 
 other is represented in the annexed figure, and is an 
 apparatus commonly employed at lectures for illustrating 
 the properties of air. a the glass receiver, in which the 
 fountain is seen to play, which must be made to fit air-tight 
 to the ground brass plate b beneath. The stop-cock c must 
 then be screwed into the plate of an air-pump, and a 
 vacuum formed. After turning the stop-cock to prevent 
 the entrance of air, the lower extremity should be immersed 
 in a vessel of water ; and on again opening the communica- 
 tion, the pressure of the atmosphere on the surface of the 
 water will cause it to rise in a stream, and form a beautiful 
 jet-d'eau. 
 
 AIR-GUN. A machine in which highly-compressed 
 air is substituted for gunpowder to expel the ball, which 
 will be projected forward with greater or less velocity, 
 according to the state of condensation, and the weight of 
 the body projected. The effect will, therefore, be similar 
 to that of a gun charged with gunpowder, for inflamed 
 gunpowder is nothing more than air very greatly condensed, 
 so that the two forces are exactly similar. The elasticity 
 of the air generated by the inflammation of gunpowder has 
 been estimated by Mr. Robins as equal to about 1,000 times 
 that of common air ; it would therefore be requisite to con- 
 dense air into one-thousanth part of its original bulk to 
 produce the effects of gunpowder. There is, however, this important considera- 
 tion to be attended to, viz. that the velocities with which balls are impelled are 
 directly proportional to the square root of the forces ; so that if the air in an 
 air-gun be condensed only ten times, the velocity will be equal to -fa of that 
 arising from gunpowder; if condensed twenty times, the velocity would be f that 
 of gunpowder, and so on. Air-guns, however, project their balls with a much 
 greater velocity than that assigned above, and for this reason, that, as the 
 reservoir or magazine of condensed air is commonly very large in proportion to 
 the tube which contains the ball, its density is very little altered by passing 
 through that narrow tube, and consequently the ball is uiged all the way by 
 nearly the same force as at the first instant; whereas the elastic fluid arising 
 from inflamed gunpowder is but very small indeed in proportion to the tube or 
 VOL. i. E
 
 26 AIR-GUN. 
 
 barrel of the gun, and therefore, by dilating into a comparatively large space as 
 it urges the ball along the barrel/its force is proportional y weakened and it 
 alwaf s acts less and less on the ball in the tube. Hence it happens that anr 
 condensed only ten times into a pretty large receiver, will project its ball with 
 a velocity little inferior to that of gunpowder. Having thus explained the 
 principle of the machine, we shall proceed to describe the construction of one : 
 5 a" by Martin is perhaps the bestf and h as follows :-It consists of a ock, 
 stock/barrel, ramrod, &c., of about the size and weight of a common fowling- 
 piece! Under the lock at b is screwed on a hollow copper ball c. perfectly 
 air-tight. This ball is fully charged with condensed air, by means of the syringe 
 B previous to its being applied to the tube at b. Being charged and screwed 
 on as above stated, if a bullet be rammed down in the barrel, and the trigger a 
 be pulled, the pin in b will, by the spring-work in the lock, forcibly strike 
 out into the ball, and thence by pushing it suddenly, a valve within it will let 
 out a portion of the condensed air, which, rushing through the aperture la the 
 
 lock, will act forcibly against the ball, impelling it to the distance of 60 or 7(F 
 yards, or farther if the air be strongly compressed. At every discharge only a 
 portion of the air escapes from the ball ; therefore, by re-cocking the piece 
 another discharge may be made, which may be repeated for a number of times 
 proportioned to the size of the ball. The air in the copper ball is condensed by 
 the syringe B in the following manner. The ball is screwed quite close on the 
 top of the syringe ; at the end of the steel-pointed rod a is a stout ring, through 
 which passes the rod k ; upon this rod the feet should be firmly set; then the 
 hands are to be applied to the two handles i i fixed on the side of the barrel of 
 the syringe, when, by moving the barrel B steadily up and down on the rod a, 
 the ball c will become charged with condensed air, and the progress of con- 
 densation may be estimated by the increasing difficulty in forcing down 
 the syringe. At the end of the rod k is usually a square hole, that the 
 rod may serve as a key for attaching the ball to either the gun or syringe. In 
 the inside of the ball is fixed a valve and spring, which gives way to the 
 admission of the air, but upon its emission, conies close up to the orifice, 
 shutting out the external air. The piston rod works air-tight by a collar of 
 leather on it, in the barrel B ; it is therefore obvious that when the barrel is 
 drawn up, the air will rush in at the hole A; when it is pushed down, it 
 will have no other way to pass from the pressure of the piston but into the 
 ball c at the top. The barrel being drawn up, the operation is repeated, until 
 the condensation is so great as to resist the action of the piston. If air be very
 
 AIR-PRESSURE ENGINES. 27 
 
 suddenly compressed into a small compass, the heat given out is so considerable 
 as to be sufficient to ignite inflammable substances. This discovery was made, 
 accidentally, by a French soldier, who, in cleaning his musket with some wadding 
 fastened to the ramrod, found, after thrusting the ramrod suddenly down the 
 piece, that the wadding had ignited. The fact he communicated to the National 
 Institute, and repeated the experiment in their presence. This property has 
 been turned to advantage in an apparatus denominated, " An Instantaneous 
 Light Machine," constructed in a walking stick, which consists of a piston 
 .accurately fitted and worked in a cylinder, by the sudden stroke of which the 
 volume of air contained in the cylinder becomes so much compressed as to give 
 out sufficient heat to set fire to a piece of the substance termed German tinder. 
 A patent was also taken out, in 1826, by Mr. Newmarch, of Cheltenham, for a 
 similar method of exploding fire-arms, by means of a cylinder and piston, 
 enclosed in the stock behind the breech, which has a small hole, closed by a 
 valve. The piston is forced back, by means of a lever, against a powerful 
 spring, and upon being released, is impelled forward into the cylinder with such 
 force as to cause the air before it to give out its caloric in the state of sensible 
 heat or fire at the aperture in the breech, which, passing the valve, enters the 
 barrel, and instantly ignites the charge of powder. 
 
 AIR-PRESSURE ENGINES. Engines in which the difference of pressure 
 of air of different densities is employed as a motive force. From the extreme 
 lightness and mobility of air, it has been frequently proposed to employ it as a 
 medium for transmitting motion to machinery at a considerable distance from 
 the prime mover. Amongst the first who attempted this is the celebrated 
 Papin, who invented the steel-yard safety-valve. He employed a fall of water 
 to compress the air in a cylinder, through the medium of an intervening piston; 
 and he connected this cylinder to another, at the mouth of a mine a mile dis- 
 tant, by means of a pipe of that length. In the second cylinder was another 
 piston, the rod of which was intended to work a set of pumps ; but, contrary to 
 expectation, the compression of the air in tlie first cylinder produced no move- 
 ment in the piston of the second. Papin subsequently attempted to bring his 
 scheme into use in England, but did not succeed. Afterwards, however, he 
 erected great machines in Auvergne and Westphalia for draining mines, but 
 so far from being effective machines, they would not even begin to move. He 
 attributed the failure to the quantity of air in the pipe, which must be condensed 
 before it can condense the air in the remote cylinder ; he therefore dimin- 
 ished the size of this pipe, and made his water machine exhaust instead of 
 condense, and had no doubt that the immense velocity with which air rushes 
 into a void, would make a rapid and effectual communication of power. But 
 the machine stood still as before. Near a century after this, an engineer at an 
 iron-foundry in Wales erected a machine at a powerful fall of water, which 
 worked a set of cylinder bellows, the blow-pipe of which was conducted to the 
 distance of a mile and a half, where it was applied to a blast furnace; but not- 
 withstanding every care to make the conducting pipe very air-tight, of great 
 size, and as smooth as possible, it would hardly blow out a candle. The failure 
 was ascribed to the impossibility of making the pipe air-tight; but above ten 
 minutes elapsed after the action of the piston in the bellows, before the least 
 wind could be perceived at the end of the pipe, whereas the engineer had cal- 
 culated that the interval would not exceed six seconds. The foregoing particulars 
 are taken from l)r. Robinson's Natural Philosophy, art. Pneumatics, and an 
 explanation is offered of this curious phenomenon; but on account of its 
 prolixity, we omit it; but the following remarks, which appeared in the Franklm 
 
 the blow-pipe is 3 inches in diameter, and only a mile long, the air at one end 
 must be kept constantly condensed by a pressure equal to 5^ atmospheres to 
 produce a velocity of 128 feet per second; and yet this velocity gives only 2,304 
 gallons per minute, only about half the quantity used in the furnaces of Europe; 
 a blast furnace there expels 720 cubic feet of air per minute, (Mech. Philos.
 
 28 
 
 AIR-PRESSURE ENGINES. 
 
 Vol. VIII. p. 784.) if we calculate the velocity of water issuing from a pipe a 
 mile long, and 3 inches in diameter, under a 9-foot head and fall, to be ] .foot 
 per second. Now, as equal velocities are known to be generated in all flu.ds 
 bvequal heads, all other circumstances being equal, it will follow that a 9-foot 
 head^f air, or ^ of a head of 9 feet of water, will generate in r a velocity 
 of 1 foot per second in a tube 3 inches in diameter, and a mile long. Again, it 
 is known both from theory and experiment, that the heads of pressure gener- 
 tin" velocities in fluids, are as the squares of the velocities ; now the square of 
 
 1 is 1, and the square of 128 is 16384, therefore the head of pressure due to 
 the velocity of 128 feet, is obtained by the following proportion, as 1 : 16384 
 : : 9 : 147456, and tins number divided by 800 gives 184^ equal to a pressure 
 of 5^- atmospheres, as before said : now if we suppose this velocity doubled, 
 or 256 feet a second, in order to discharge air enough for a blast furnace, the 
 head of pressure must be four times as great, or upwards of 21 atmospheres.
 
 AIR-PRESSURE ENGINES. 
 
 2ft 
 
 This would require a machine of 3425 horse power, provided a horse can work 
 eight hours a-day, raising 140 Ibs. 200 feet per minute. Notwithstanding the 
 
 failure of both of the plans of Papin, and the plausible arguments against them 
 just quoted, they have been recently revived in this country. Mr. Samuel 
 Wright has taken out a patent for transmitting power to machinery by means 
 
 of condensed air ; but we have not heard of any erections on the principle. 
 Mr. Hague, however, has taking out patents for effecting the same object by 
 the rarefaction of air by an air-pump, and has established several machines 
 upon this* principle, the successful operation of which leaves no doubt that the 
 failure of Pain must have arisen from some defective arrangements or imper- 
 
 e arrange 
 We have selected a few of those machines to which Mr. 
 
 apn 
 
 fect workmanship. 
 Hague considers the principle as peculiarly applicable. 
 
 The first of these which we shall describe, is a crane for raising goods into 
 lofty warehouses. In the engraving on page 28, a represents a working cylinder 
 vibrating upon gudgeons, one of which has passages leading to the top and 
 bottom of the cylinder ; b piston rod connected to the crank ; d d guide rods; 
 e pinion on axis of the crank, driving / a toothed wheel on the axis of the 
 drum g; i the valve-box, in which the hollow gudgeon of the cylinder turns, 
 and, admitting the atmosphere to press upon one side of the piston whilst the 
 
 air is drawn from the opposite side by an air-pump worked by a steam-engine; 
 k the spanner for reversing and regulating the motions of the machine ; e pipe 
 leading to the air-pump ; m fly-wheel. Mr. Hague proposed to erect a series 
 ef these cranes round Docks and Basins, the whole to communicate with a large
 
 30 AIR-PRESSURE ENGINES. 
 
 main or pipe, in which a vacuum should be maintained by pumps worked by a 
 steam-engine. The advantage consisted in the employment of steam power, 
 where no shafting can be introduced. Mr. Hague erected some engines of this 
 description in some collieries at Stourbridge, which we have heard gave great 
 satisfaction. 
 
 The figure on page 29 presents a swing-round crane, upon the same principles 
 as the former, and may be supposed to form one of a range round a dock basin, 
 a is a hollow cast-iron post, upon which the crane turns, and is firmly imbedded 
 in masonry; from the upper end proceeds a pipe b turning air-tight in a 
 stuffing-box, and communicating with a cylinder d by means of a three-way 
 cock c. The cylinder vibrates upon gudgeons, in one of which are formed 
 two hollow passages, the one leading to the top, and the other to the bottom, 
 of the cylinder. A pipe e proceeds from an aperture/ in the crane post to an 
 air-pump, worked by a steam-engine, or any other power, and which may be 
 situated in any part of the docks, the air being rarefied alternately above and 
 below the piston of the vibrating cylinder, whilst the atmosphere presses upon 
 the opposite side of the piston ; the alternate motion of the latter turns the 
 crank g and the piston fi, which drives the wheel k fixed upon the axis of the 
 chain barrel /, and thus raises the load ; m is a fly-wheel, by means of which 
 the reciprocating motion of the cylinder imparts a rotatory action to the crank. 
 
 The last example we shall give of the application of Mr. Hague's patent, is 
 that of a tilting or powerful forge-hammer, which is raised by the atmosphere 
 pressing upon a piston connected to the hammer, (the air on the opposite side 
 being rarefied by means of an air-pump situated at a distance,) and which falls, 
 by its own weight, upon the admission of the atmosphere above the piston. 
 
 a b is the hammer turning upon a fulcrum at b; c the anvil; d a cylinder, 
 situated immediately over the hammer ; ethe piston, connected with the hammer 
 by the bar/, and the slings g; h a slide valve, worked by the lever I, which is 
 struck by a pin on the bar/ when the piston arrives at the top of the cylinder 
 which depresses the valve so as to shut off the communication with the air- 
 pump, and admit the atmosphere, permitting the hammer and piston to fall 
 by their own weight. Towards the close of the descent, the hammer, by means 
 ot a line attached to it and to the lever /, reverses the position of the lever / 
 and of the slide valve, thus re-opening the communication between the cylinder
 
 AIR-PRESSURE ENGINES. 31 
 
 and air-pump, k is the pipe leading from the cylinder to the air-pump, and m 
 a cock for shutting off the communication with the air-pump when the hammer 
 is not at work ; n n spanners for opening and shutting the cock. 
 
 Pneumatic Transport. In the year 1810, Mr. Medhurst took out a patent 
 for conveying letters and goods by the pressure of air ; and shortly afterwards 
 he issued a prospectus, to show the practicability of conveying persons and 
 goods with ease and safety at the rate of fifty miles an hour. The plan was to 
 propel a carriage through a long tube or tunnel, by forcing air into the tube 
 behind the carriage ; these two parts being made so nearly to fit that very little 
 air would escape past the carriage. No attempt, that we have heard of, was 
 made to carry out this scheme ; but in 1824, Mr. John Vallence obtained a 
 patent for a different mode of applying the air as a means of transport. Instead 
 of forcing the air at the back of the carriage, he exhausted the tube in front of 
 the carriage or train, and allowed the natural pressure of the atmosphere to 
 operate at the back. This arrangement appeared more feasible than Mr. 
 Medhurst's ; and we have heard that Mr. Vallence set up a large model in his 
 garden, to demonstrate the practicability of his plan ; the eligibility, however, 
 of travelling through a continuous tube was not satisfactorily shown, and it 
 shared the fate of its precursors. The last-mentioned objection was subse- 
 quently completely obviated by Mr. Henry Pinkus, a highly^ngenious American 
 gentleman. His invention consists in transferring the action produced upon a 
 piston or diaphragm, moving in the interior of a tunnel or tube, to its exterior, 
 by connecting a vehicle or machine, (termed the dynamic traveller,) situated 
 within the tube, with a car or carriage without, (denominated the governor,) to 
 which the train of transport carriages is attached. The pneumatic railway 
 admits of several methods of application, in each of which the dimensions, 
 economy, and details, vary. It will be sufficient in this place to describe one, 
 in doing which, we shall avail ourselves of a condensed extract from the 
 specification. 
 
 " The length of the pneumatic tube will be equal to the whole length of the 
 railway or canal to which it may be applied, and it should be cast in portions 
 of the greatest length possible, in smooth metal moulds, so that their inner 
 sides should be very even and true, and they are to be connected by the ordinary 
 socket joint. Fig. I of the annexed wood-cuts exhibits a perspective sketch of 
 a portion of a line of pneumatic railway, laid down, exhibiting the ' governor ' 
 drawing a train of carriages along it. The upper half only of the air tunnel a a 
 is seen, the other half being imbedded in a semicircular trench ; on the edges 
 of which trench rest strong projecting ledges, which are cast to the outsides of 
 the tunnel, in a longitudinal direction. These ledges are about three inches 
 wide on their upper surfaces, and constitute the railway upon which the wheels 
 h h of the governor or drag, and those of the train, run. To explain the mode 
 adopted of communicating the motive force generated in the interior of the 
 tunnel to the governor on the outside, we must refer the reader to Fig. 2, which 
 represents a sectional perspective of a portion of the tunnel ; wherein it will be 
 seen that a strong flat bar/ is bolted to the governor, so as to depend vertically 
 through a longitudinal chase made in the top of the tunnel, and reaching to the 
 centre of it. Here it is firmly fastened to a species of carriage, of the form of 
 a velocipede, which operates as a guide and stiffening-frame to the piston or 
 diaphragm c, that receives the impulse of the atmosphere ; the expanding piston 
 having a conical steel ring around its periphery, one foot wide, and placed at an 
 angle of about 15 from the surface of the cylinder, against which one edge of 
 the cone acts with a slight pressure of the air, so as to conform to any slight 
 inequality of the cylinder. A more exact comprehension of these arrangements 
 will be afforded by the subjoined fig. 3, which exhibits a transverse section of 
 the pneumatic railway; an end elevation of the governor, its connexions and 
 position ; also the rear wheel of the dynamic traveller ; its position within the 
 cylinder; the guide rail (cast to the interior of the cylinder) on which it runs; 
 and the piston in advance, a a a is the cylinder, the lower semi-circumference 
 of which is of greater thickness than the upper, to enable it to withstand the 
 greater strain on this part, to which it is subjected by the weight of thr carriages
 
 AIR-PRESSUUE ENGINES.
 
 AIR-rRESSURE ENGINES. 
 
 3.J 
 
 rolling upon the projecting ledges or rails b b ; cc c shows the area of the piston 
 strengthened by cross bars ; dddd stay rods, connecting the piston to the frame 
 of the dynamic traveller, the hind wheel only, e, of which can be seea in this 
 
 7.3. 
 
 view, /exhibits an edge view of the bar that connects the dynamic traveller to 
 the governor g, of which h k are the running wheels, connected by a cranked 
 axle-tree. .In connexion with the vertical arm /are inflexible horizontal arms, 
 from which are suspended by pivots or vertical axles anti-friction wheels i i, 
 whose peripheries roll on the outer sides of the longitudinal chase, and keep 
 the vertical arm in the centre, so as to prevent its touching on either side. 
 This figure also shows the shape of the longitudinal chase or aperture, through 
 which the connexion is made from the interior to the exterior ; this chase is 
 cast with the cylinders, and is necessarily continued the whole length of the 
 tunnel. In order that the running wheels of the governor, as well as those 
 of the train of carriages that follow it, may be kept truly upon the centre line 
 of the projecting rails, and never rub against the sides of the tunnel, metallic 
 arms are projected from their frames, carry ing anti- friction wheels, the peripheries 
 of which roll against the outer sides of the longitudinal chase and underneath 
 the flange : this latter circumstance affords a great security against upsetting. 
 And for the purpose of keeping the peripheries of these anti-friction wheels 
 always in contact with the chase, whatever curves may be made in the line of 
 VOL. i. t
 
 34 AIR-PRESSURE ENGINES. 
 
 railway, their axles turn in slots, and are pressed inward by springs. Into the 
 trough, an elastic flexible padded chain, called by the patentee, the valvular cord, 
 is fitted the whole length of the tunnel, forming, as it were, a continuous valve. 
 In the annexed figure, this valve is shown in section on a greater scale, with 
 
 the flexible cord I in its place. The sides of this cord, when not compressed, 
 have a curved figure, as represented by the dotted lines : it is surrounded with 
 a coat of felt, and on the top is attached a jointed band m of iron, resembling a 
 continuous series of hinge-flaps, the joints admitting of the utmost pliability to 
 the cord, and affording a compensation for the expansion or contraction of the 
 metallic portion of the band ; the other materials of the valvular cord are of too 
 soft and yielding a nature to require any provision against the changes of 
 temperature, and these are smeared over, or saturated with, unctuous matter, to 
 keep them soft and more effectually air-tight. By reference to Fig. 2 it will be 
 seen that the piston precedes the dynamic traveller in the tunnel ; and by 
 reference to Fig. 1 it will be perceived that there is a small wheel in the centre, 
 (shown also at k, Fig. 3,) with the valvular cord I passing over its periphery, 
 while there is another similar wheel in front, and a third at the hind part, 
 which constantly keeps the valvular cord in its trough. The office of the centre 
 wheel is, therefore, simply to keep continually lifting out the valvular cord from 
 its seat, and thereby expose the back of the piston to the full and direct action 
 of the proximate atmosphere ; the fore wheel, by its pressure upon the valvular 
 cord, preserving the partial vacuum effected before the piston, and the hind 
 wheel, by its pressure, restoring the valvular cord to its previous station. To 
 enable the conductor to retard or stop the progress of the vehicle at pleasure, 
 the patentee proposes to form a valve in the lower quadrant of the piston, to be 
 opened or closed at pleasure by means of a lever, or a chain and pulleys. With 
 a view to facilitate the operation of transit, and enable various parts of the same 
 line of the pneumatic tunnel to be used simultaneously, the patentee proposes 
 to divide it into sections, (of convenient lengths, which may be determined by 
 the stations of the operating engines,) by intercepting station valves, which may 
 be made similar in form and construction to the common gas valves usually 
 applied to mains; and the connexion may, in this case also, be similar. The 
 patentee, however, prefers station valves of the nature of vertically sliding 
 shutters, running down into sills below the line of the tunnel, as these admit of 
 readier working than the gas main valves. Stationary exhausting engines, or 
 air-pumps, are to be put in action by attached local steam-engines, or-other con- 
 venient first mover; communications between the exhausting engine and the 
 pneumatic tunnel to be made by means of lateral tubes : and the connexions 
 are to be made in the common manner upon the lower side, at the distance of 
 about 200 feet from the station valve, and on the side of it that lies nearest to 
 the station whence the governor, with its train of carriages, is to be drawn. The 
 stations for the engines may be at three, four, or five miles apart, according to 
 the power of the engines, the capacity of the pneumatic tunnel, the degree of 
 rarefaction necessary, the average weight to be conveyed, the velocity required, 
 and the height of any inclined plane to be surmounted. As the power to be 
 produced is by the pressure of the atmosphere acting against the piston, in 
 advance of the dynamic traveller, by the rarefaction within the tube before it, 
 the pressure will depend upon the degree of rarefaction ; and that may be con- 
 stantly ascertained by means of barometers placed at the different stations, 
 which will indicate the approach of the governor and its train, and about its
 
 AIR-PRESSURE ENGINES. 35 
 
 distance from the station. A barometer placed on the governor, and commu- 
 nicating by a small tube with the interior of the pneumatic cylinder, and through 
 the piston to its vacuum side, will likewise indicate the degree of rarefaction, 
 and, consequently, the pressure upon the piston, the sufficiency of power to 
 propel, and the time for moving off. Action being given to the exhausting 
 engines connected with the section of the tube through which propulsion is to 
 be effected, the station valve being closed, and the air abstracted from that end 
 of the section of the pneumatic cylinder, rarefaction will take place throughout 
 the whole of the included atmosphere contained in the space lying between the 
 station valve and the piston, which is attached to the dynamic traveller. The 
 partial vacuum thus effected at the station will cause the included column of 
 air to move rapidly towards it ; and the incumbent atmosphere pressing upon 
 the valvular cord, will tend to aid the action of the weight of the cord in making 
 the pneumatic valve sufficiently close to prevent the ingress of the external air, 
 and preserve the required degree of rarefaction on the vacuum side of the piston. 
 The unincluded atmosphere rushing into the cylinder through the aperture in 
 the pneumatic valve over the dynamic traveller, (which is laid open by the lifting 
 of the valvular cord over the central wheel of the governor, as before mentioned,) 
 .ind impinging on the plenum side of the piston, will produce a pressure pro- 
 portional to the degree of rarefaction on its opposite side, and consequently draw 
 the train of carriages connected thereto after it. On the near approach of a 
 train to a station valve, the latter will be quickly let down into its recess, to 
 allow the former to pass. The valve may then be again raised ; and the same 
 engine continuing to abstract the air, as before, from the same section of the 
 railway, it will be again soon prepared for another train in like manner; while 
 the train that had passed into the next section is being operated upen in like 
 manner by the engine belonging to it, and so on, from one section to the other, 
 throughout the whole line of railway. For further remarks on this interesting 
 proposition, we must refer the reader to the article RAILWAY. 
 
 Fig. I. 
 
 It has been already explained that air expands, or has its elastic press 
 increased by the application of heat, and that its volume contracts, and
 
 36 AIR-PRESSURE ENGINES. 
 
 pressure becomes less, by a decrease of temperature ; and several attempts have 
 been made by taking advantage of tin's property of air, to substitute it for steam, 
 as a prime mover of machinery. Could this be effected, it would be a great 
 advantage in many situations; as, for instance, where water is scarce, or in 
 steam vessels or locomotive engines, where (the machinery forming a part of 
 the load,) it is desirable to reduce the weight as much as possible. Having said 
 thus much of the principle of these machines, we shall proceed to describe one 
 or two of the latest arrangements for the purpose. 
 
 The first we shall notice is Messrs. R. and J. Stirling's air-engine, for which 
 those gentlemen obtained a patent in 1827. This machine resembles the steam- 
 engine in the construction and application of many of its parts, such as the 
 piston and cylinder, reciprocating beam and parallel motion, crank, and fly 
 wheel, as shown in Fig. 1. Motion is communicated to the piston in the cylin 
 der by alternately heating a portion of air connected with one side of the piston, 
 and at the same time cooling that in connexion with the other. This is effected 
 by means of the air-vessels a a, one of which communicates with the uppei 
 part, and the other with the lower part of the cylinder, through curved nozzles, 
 the pipe M forming the communication between one of the nozzles and the top 
 of the cylinder. Fig. 2 represents a section of one of the air-vessels whose sides 
 
 are cylindrical and top and bottom spherical. This air vessel, wllich h made 
 ., '[ "st-iron, and supported in the brick-work by the projecting ledge / /, is fur- 
 n shed with a plunger c C c The top and bottom of the plunger is made of 
 
 The Sir? ??i P", 6d W S r er ? numerous mall holes to admit the air. 
 
 tenor of the plunger .. fil ed with very thin plates of sheet-iron, so bent 
 
 TfA t e ! r flat T faCe9 J r m c g in contact, that the air may have 
 
 a free passage between them. These are also perforated with small holes/which
 
 AIR-PRESSURE ENGINES. 37 
 
 holes are not placed opposite to each other, but so arranged as to cause the air 
 to pass through the plunger in a zig-zag direction. The plunger is formed cir- 
 cular, to fit the top and bottom of the air-vessel when drawn up and down. The 
 rim c c of the plunger, which moves in a cylindrical receptacle at the circum- 
 ference of the air-vessel, as represented, is not perforated as the other part. It 
 is kept steady by a spring at / /, consisting of a belt of thin sheet-iron, attached 
 at its upper edge to the rim c c; a. number of slits are made at the lower edge 
 of the belt, to admit of its being bent outwards to rest against the air-vessel, and 
 act as a spring. The plunger is also kept steady, in its ascent and descent, by 
 the plunger rod d passing through the stuffing-box at the top of its case, and 
 by the guide- rods g g, which work in the guide cases i i, Figs. 1 and 2. The 
 guides are fixed to a ring h h which is attached to the plunger and the plunger 
 rod by the arras//, four in number. The guides are supplied with oil by the 
 oil-cup and stop-cock at the top of their cases. The top e e of the air-vessel is 
 flanged down in the manner represented at k, with a thin ring of sheet lead 
 between the flanges, to keep the joining air tight. The lower part of the air 
 vessel is heated by a fire placed under it, and its upper part kept cool by a 
 current of cold air, by water, or by other means. The plunger rods of the air 
 vessels a a. Fig. 1, are attached by slings to the end of the beam v, so that the 
 motion which elevates one plunge'r in one of the vessels, depresses that in the 
 other. When the plunger is raised, the cold air in the upper part of the vessel 
 will be heated in passing through the interstices of the plunger in its ascent, 
 which has itself been heated on reaching the hot or lower part of the air-vessel; 
 and during this time the air in the other vessel will be cooled bypassing through 
 the interstices of the plunger in its descent, which has itself been cooled by 
 reaching the cold or upper part of the air-vessel. These changes of temperature 
 are i'urther augmented by portions of the air being alternately changed from the 
 hot to the cold, and from the cold to the hot parts of the vessels, by the alter- 
 nate occupation of the hot and cold parts by the plunger. Now, as one of the 
 air-vessels is connected with the top and the other with the bottom of the 
 working cylinder, there will be a motion produced on the piston by the alternate 
 application of the expansive force of heated air : and this motion is commu- 
 nicated to the beam v through the piston rod and parallel motion, and joins the 
 beam to the fly-wheel s s. On the axis of the fly-wheel is fixed an eccentric t. 
 which communicates motion to the plungers in the air-vessels through the 
 system of levers 1, 2, 3, 4, and the beam v, and this motion is adjusted so that 
 the change of the plungers shall be effected whenever the piston reaches the 
 top or bottom of the cylinder ; thus applying to that end of the cylinder where 
 the piston is, the hot air, which, by its increased elasticity, will drive the piston 
 to the other end. This engine is also furnished with an air-pump, the piston 
 rod of which is shown at x, for condensing the air into the reservoir w w. The 
 air is permitted to pass through self-acting valves into the curved nozzles," and 
 thence into the cylinder, or the air-vessels a a, but is not permitted to return 
 from these vessels or the cylinder into the reservoir w w, which is also provided 
 with a safety valve for the escape of superfluous air, when more is pumped in 
 than is necessary to supply the air-vessels. The air-pump is only occasionally 
 required to be set to work. 
 
 In 1828, Messrs. Parkinson and Crossley took out a patent for an air-engine, 
 which differs considerably in the arrangement of its parts from the one just 
 described ; and as it appears to be of a somewhat simpler construction, we shall 
 lay a description of it before our readers. Fig. 1 shows a front elevation of so 
 much of the engine as is necessary to explain the invention. Fig. 2 is an end 
 elevation, and Fig. 3 a section (upon an enlarged scale) of a differential vessel, 
 and its transferrer, exhibiting also a mode of heating and cooling the differential 
 vessel. The same letters in each figure where they occur, refer to the same 
 parts. The differential vessel a a is of the form of a hollow cylinder witn 
 convex ends, of such a length as to preserve an essential difference of tempera- 
 ture between one end and the other, and nearly one-half being exposed to a hot 
 and the other half to a cold, medium. The vessel has a stuffing-box at the 
 end/, and at the other end is an opening or pipe / m or / , for the purpose of
 
 AIR-PRESSURE ENGINES. 
 o 
 
 tormina a communication with the working cylinder and piston. The transfer- 
 e Tfis a hoTow vessel, air-tight, and so much shorter, as to leave a sufficient 
 space in the differential vessel for containing a volume of air, which, when 
 
 expanded by heat passing through the pipes I mar In, will also fill the working 
 cylinder, and force the piston from one end of it to the other. The transferrer 
 is also made only so much less in diameter than the differential vessel as to 
 illow it to move freely from one end of the differential vessel to the other. To 
 one end of the transferrer is fixed a rod e, passing through a stuffing-hox/, for 
 the purpose of moving it from one end of the differential vessel to the other, 
 thereby causing the air to pass in a thin stratum against its hot and cold parts 
 alternately, thus producing the force or power to be employed against the 
 working piston. The rod g, Fig. 3, which is fixed on the upper part of the dif- 
 ferential vessel, is intended to guide the transferrer in its proper direction, by
 
 AIR-PRESSURE ENGINES. 
 
 39 
 
 means of a tube which is inserted in the upper end of the transferrer, the lower 
 end of the tube being made air-tight. Motion is given to the transferrer by 
 means of the eccentric on the shaft p being connected with the beam r, which 
 
 beam is connected to the rod e of the transferrers by the links s s. The work- 
 ing cylinder M with its piston, side rods, cranks, shafts, fly-wheel, and eccentric 
 motion, are the same as those commonly used in steam-engines, and therefore 
 require no particular description. The pipe Im forms a communication between 
 the differential vessel, No. 1, and the top of the cylinder; and the pipe In 
 connects the differential vessel, No. 2, with the bottom of the cylinder. The 
 operation of the engine will be as follows : Supposing the eccentric discon- 
 nected from the beam r, and the upper part of the differential vessels heated, 
 and their lower parts cold, and the transferrers of the two differential vessels 
 placed by hand in the situations shown in the figure, and the volume of air
 
 40 
 
 AIR-PRESSURE ENGINES. 
 
 ying the hot part of the differential vessel, No. 2, and being increased in 
 v in proportion to its temperature, whilst the volume of air m the dit- 
 feaf ves el P No. 1, is occupying the coldest part, the working piston will be 
 foced upwards by a power corresponding with the d.fference of the elast.c force 
 
 of the air in the two differential vessels ; and when the working piston has been 
 forced to the top, the situation of the transferrers should be reversed by hand, 
 so that the air in the differential vessel, No. 1, will occupy the hot part, and 
 communicate its force to the upper side of the working piston, and thereby 
 produce a returning stroke ; and the eccentric being then by hand re-connected 
 with the beams, the alternate expansion and contraction of the air in the two 
 differential vessels will keep the engine in motion ; and then, by working the 
 transferrer in the same way as the valves in steam-engines, the engine may be 
 either stopped or put in motion. For the purpose of heating the differential 
 vessels, the inventors prefer the employment of inflammable gas, a mode of 
 applying which is shown at Fig. 3, where d d is a hollow ring, surrounding the 
 differential vessel, andcommunicating with the tube by which the gas is supplied; 
 this ring is perforated for the emission of jets of gas, to flow, when ignited, all 
 round and against the differential vessel, or nearly so ; c c is an iron vessel, for 
 directing the heat to the differential vessel, which casing is open at bottom for 
 the admission of air, having also an opening at top, to serve as a chimney or 
 flue ; k is an outer covering of polished metal, of about two or three more 
 inches in diameter than the casing c c, for the purpose of lessening the radiation 
 of heat The working cylinder h may be kept hot by means of a current of 
 heated air being conducted to it from the flues of the differential vessels, t t 
 represent the differential vessel placed in a cistern of cold water, with a con- 
 stant current running in at the bottom u agains't the differential vessel, and 
 passing off at the top v. We are not aware that the engine just described has 
 been brought into practical operation, but that invented by Mr. Stirling was 
 employed in a stone quarry ; it has, however, we learn, been replaced by a 
 steam-engine, in consequence of its inferiority to the latter in the economy of
 
 AIR-PUMP. 
 
 41 
 
 working, particularly as respects the consumption of fuel. One objection to 
 air-engines is, that the changes of volume do not take place with sufficient 
 rapidity, and that when water is employed to accelerate such changes, the 
 quantity necessary for that purpose is greater than would be required to supply 
 the boiler of a high-pressure steam-engine; so that in situations where either 
 water is scarce, or the weight of it an objection, the latter engines would, on 
 those accounts, be found superior to the former. 
 
 AIR-PUMP. An instrument or machine for exhausting or rarefying the air 
 in closed vessels, and very generally employed to illustrate the properties of air, 
 and to explain the various phenomena connected with the science of pneumatics. 
 The inventopof the air-pump was Otto Guericke, a magistrate of Magdeburgh; 
 
 his machine was of a rude and inconvenient structure, and worked under 
 water, but a description of it having been received by Mr. Boyle, he, with the 
 assistance of Dr. Hook, introduced such improvements in the construction as 
 to render the machine extremely serviceable in philosophical experiments upon 
 VOL. i. G
 
 4 . 2 
 
 AIR-PUMP. 
 
 ,h, nature .nd -ope ,Ue, of .*. 
 
 
 Kg. 4. 
 
 and %*. 4 and 5, parts of the piston, shown detached for the sake of perspicuity. 
 In ig. 2, C D represents the barrel, F the collar of leathers, G a hollow cylin- 
 drical vessel to contain oil ; Ris also an oil- vessel to receive the oil which is drawn 
 along with the air from the barrel when the piston is drawn upwards, and 
 when this vessel is full the oil is carried over with the air along the tube T 
 into the oil vessel G ; c c is a wire which is driven upwards from the hole, by 
 the passage of the air, and as soon as this has escaped, it falls down again by 
 its own weight, shuts the hole, and prevents the return of the air into the 
 barrel ; at d are fixed two pieces of brass to keep the wire c c in a vertical 
 position, in order that it may accurately shut the hole. H is the piston rod,
 
 AIR-PUMP. 43 
 
 Laving a rack on the upper end, and made hollow to receive a long wire g, 
 which opens and shuts the hole L ; on the lower end of this wire is screwed a 
 nut o, which, by stopping in the narrowest part of the hole, prevents the wire 
 g from being drawn up too far. This nut and screw are seen more distinctly 
 in Fig. 3 ; the wire slides in a collar of leathers shown in Figs. 3 and 5 in the 
 middle piece of the piston. Figs. 4 and 5 are the two main pieces which com- 
 pose the piston, which is shown entire in Fig. 3 ; Fig. 5 is a conical piece of 
 brass having a shoulder at bottom ; a long hollow screw is cut about two-thirds 
 of its length, and the remaining part of the hole, in which there is no screw, is 
 about the same diameter as the screwed part, except a thin plate at the end, 
 where the diameter of the hole is just equal to that of the wire gg. That part 
 of the inside of the conical brass in which no screw is cut, is filled with oiled 
 leathers, having holes in them, through which the wire can slide stiffly; a short 
 external screw, working in the internal screw, and a washer with holes in them, 
 through which the wire g passes, serve to compress the leathers, a a, Figt. 3 
 and 4, is the core cf the piston, the inside of which is turned so as exactly to 
 fit the outside of Fig. 5 ; b b, Fig. 3, are round leathers, about 60 in number 
 of the same diameter as the barrel C D, and having holes in the centre to 
 receive a a ; a circular plate, or washer, c c, Fig. 3, is placed over the leather, 
 and a nut d d, upon a screw cut upon the upper end of a a, serves to compress 
 them. The piston rod H is screwed into the middle piece of the piston, Fig. 5, 
 and when drawn upwards, it will cause Fig. 5 to shut close into Fig. 4, and 
 drive out the air above it ; but when pushed down it will open as far as the 
 shoulder on the rod will allow, and permit the air to pass between Figs. 5 and 
 4. Having thus described at large the several parts of this machine, we proceed 
 to explain the process of rarefaction, which is carried on in the following man' 
 ner : Conceive the piston to be at the bottom of the barrel, the inside of which 
 contains common air. Now when the rod is drawn up, the upper part of the 
 piston sticks fast in the barrel, till the conical part connected with the rod shuts 
 the conical hole, and its shoulder applies close to its bottom. The piston being 
 now shut, the whole is drawn up by the rack-work driving the air before it 
 through the aperture, into the oil vessel at r, and out into the atmosphere by the 
 tube T. The piston will then be at the top of the barrel, and the wire g 
 will stand nearly as shown in the figure, just raised from the hole L, where it 
 is prevented from rising higher by the nut O. During this motion, the air will 
 expand in the receiver, and come along the bent tube into the barrel ; by 
 this means the barrel will be again filled with air, which, as the piston rises, 
 will be rarefied in the proportion of the capacity of the receiver, pipes, and 
 barrel together, to that of the latter alone. When the piston is moved down 
 again by the rack-work, it will force the conical part, Fig. 5, out of the hollow 
 part, Fig. 4, as far as the shoulders a a. Fig. 3 will rest on a a, Fig. 4, which 
 will then be so far open as to permit the air to pass freely through it, while at 
 the same time the end of gg is forced against the top of the hole, and, by 
 shutting, prevents any air from returning into the receiver ; thus the piston 
 moving downwards suffers the air to pass out between the sides of Figs. 4 and 5, 
 and when it is at the bottom of the barrel, it will have the column of air above 
 it, and, consequently, when drawn up, it will shut and drive out the air, and by 
 opening the hole at L, will at the same time give a free passage to more air 
 from the receiver. This process being continued, the air of the receiver will 
 be rarefied as far as its expansive powers will permit, for in this machine there 
 are no valves to be forced open by the elasticity of the air in the receiver, 
 which at last it is unable to effect ; there is, therefore, nothing to prevent the 
 air from expanding to its utmost degree, which is the peculiar excellency of 
 this construction. 
 
 Although the machine just described is equally adapted for condensing air 
 as for rarefying it, by merely connecting the bent pipe with the oil vessel R, 
 instead of the lower part of the pump, yet as the former operation seldom 
 requires the same delicacy of process, it is frequently effected by a simpler 
 machine, termed a condensing syringe. The following description will give an 
 idea of the ordinary construction of this instrument, a is a cylindrical tube of
 
 AIR-PUMP. 
 
 small diameter, open at one end, the other end being perforated with a very small 
 hole b, and turned externally to a very small cylinder. A strip of bladder, or of 
 thin leather, soaked in a mixture of oil and tallow, must be tied over the hole. 
 On the end of the cylinder is cut an external screw, to attach it to the vessel 
 in which the air is to be condensed, c is the piston moving air-tight ma; d, 
 
 the piton rod screwing into c ; this rod is perforated with a small hole throughout 
 its length, the lower end of the hole having a valve e, similar to the valve b in 
 the cylinder, and opening into the cylinder. To the upper end of the rod is 
 fixed a handle, g is the neck of the receiver, having a hollow screw fitting the 
 solid screw on the end of the cylinder. Now when the piston is drawn up, a 
 void is left below it, and the external air rushing through the perforation of the 
 piston rod, opens the valve e, and fills the cylinder. Then, on pushing down 
 the piston, the valve e closes ; the air being compressed into less space, presses 
 on the valve g, shuts it, and none escaping through the piston, it is gradual!}' 
 condensed as the piston descends till it opens the valve b, and is added to the 
 air already accumulated in g. We may thus force into the vessel any quantity 
 of air consistent with its strength; and if the receiver be furnished with a stop- 
 cock, the cock may be turned, and the receiver be detached from the syringe, 
 and thus be in a state to be transferred to any other purpose required. In all 
 cases where considerable force is required, and, consequently, a great conden- 
 sation of air, it will be requisite to have the condensing syringe of small bore, 
 perhaps not exceeding half an inch diameter, otherwise the force requisite to 
 produce the compression will become so great, that the operator will not be able 
 to work the machine ; for as the pressure against each square inch is about 
 15lbs. for each additional volume of air forced into the receiver, 121bs. upon 
 each circular inch, if the syringe be of 1-inch diameter, it will require a force 
 of 120lbs. to condense ten volumes of air into the barrel, whereas with a half- 
 inch bore it would only require 30lbs. 
 
 We insert the following description of an air-pump on account of its extreme 
 simplicity. It is the invention of Mr. W. Ritchie, and has no artificial valves, 
 which, as commonly constructed, are very liable to be deranged, and the repairs 
 are attended with considerable trouble and expense. The machine consists of 
 a barrel shut at the lower end, and having a small 
 aperture at c, forming a free communication with the 
 receiver at/; the piston d is solid, and stuffed in the 
 usual way. The piston rod worksinasmall stuffing-box at 
 a, so as to render it completely air-tight. There is a small 
 aperture at e, in the top of the barrel, to allow the air to 
 make its escape when the piston is raised. The air-pump 
 may be worked in the usual way, or by the method of 
 continued motion. In commencing the exhaustion of the 
 receiver, the piston is supposed to be below the small 
 aperture at c. The piston is then raised, and the air 
 which occupied the barrel is forced out through the 
 aperture at e. The point of one of the fingers is applied 
 to the perforation in the same manner as in playing 
 the German flute. The air easily passes by the finger 
 which, when the piston begins to descend, shuts the 
 opening, and completely prevents the entrance of the 
 external air. The piston is again forced down below 
 the opening c, the air in the receiver rushes into the
 
 AIR-PUMP. 45 
 
 barrel, and is again expelled by the ascending piston. Since the air in the 
 receiver has no valve to open by its elasticity, it is obvious that there is no limit 
 to the degree of exhaustion, as in the common construction. The simplicity 
 and economy of this arrangement alike recommend it. 
 
 For a long time the use of the air-pump was confined to the purposes of 
 philosophical experiment: the first application of it to mechanical purposes was 
 made by Bolton and Watt, in their steam-engines, where it is used for drawing 
 off the air extricated from water by boiling, as also the water used for con- 
 densing the steam ; and about twenty years ago, the Hon. E. Howard, availing 
 himself of a well-known principle, that liquids enter into ebullition at a much 
 lower degree of temperature in vacuo, than when under the pressure of the 
 atmosphere, introduced a most important improvement in the process of sugar- 
 refining, by concentrating the syrup in close vessels, in which a vacuum is main- 
 tained by means of an air-pump ; and subsequently, Messrs. Allen & Co. of 
 Plough Court, have adopted the principle in preparing the more delicate medi- 
 cinal extracts. A patent has also been taken out for more speedily tanning leather, 
 by enclosing the skins in boxes, and exhausting the air from the upper surface of 
 the skins whilst the lower surface is exposed to the tanning liquor, which is 
 forced into the pores by the pressure of the atmosphere. Dr. Church, of Birming- 
 ham, also has a patent for improvements in casting metals, which t consists in 
 exhausting the air from the moulds ; and patents have been taken out for dis- 
 tillation in vacuo, all of which applications of the air-pump we propose to explain 
 in detail when we come to treat of the above-named manufacturing processes. 
 
 In the description of Cuthbertson's air-pump it was stated that it was equally 
 applicable to the condensation of air, as to its exhaustion. We now present to 
 our readers (page 46) a condensing air-pump of a different description, which is the 
 invention of the late Mr. D. Gordon, of the Portable Gas Works, where it was 
 used for compressing the gas into the portable gas-holders, and will be found 
 very effective in subjecting any air or gas to a great compression, as the whole 
 volume of gas taken into the pump at each stroke is effectually discharged, the 
 mercury employed in the pump completely excluding every portion from below 
 the delivery valve. The figure represents a vertical section of one of the 
 pumps with the plunger a at its lowest immersion, or down-stroke, as it is called. 
 At this moment of time every part of the syphon is completely filled with the 
 fluid it contains to the entire exclusion of atmospheric air, the deeply shadowed 
 part c being water, and the lighter tint, quicksilver. It will therefore be easily 
 conceived that when the plunger is withdrawn by the up-stroke, an empty- 
 space or vacuum, equal to the cubic admeasurement of the plunger, will be left 
 in the syphon ; and as mercury is a much heavier body than water, the latter 
 is pushed up by the former, and follows the plunger as it ascends. The mercury, 
 consequently, sinks below its present level, which causes the "suction valve" e 
 to open, and to let in a volume of gas at the ordinary pressure, which flows 
 from a gasometer, or gas-holder, through the pipe /. At the down-stroke of 
 the plunger, the gas is then compressed and forced through the discharge valve, 
 (which opens only outward) into the pipe h, which leads to a strong recipient 
 into which the gas is condensed. The action of the pumps being continued, 
 the compression of the gas is effected to whatever degree may be required, 
 provided the power of the gas engine, or other first mover, be adequate. In 
 the Portable Gas Works above mentioned, there were recently nine pumps", in 
 operation, worked by a 10-horse engine. The quicksilver and water are poured 
 into the syphon by means of the basin and perforation at i, the aperture at k 
 being opened to allow the air to escape ; the aperture k is next made perfectly 
 tight by a plug, which is screwed into the orifice, during which time the water is 
 continually being poured in at i, to expel the air completely, and fill up every 
 crevice with the fluid ; another plug is then screwed into the orifice at i, with 
 the water above it. After this, the first down-stroke of the plunger expels the 
 atmospheric air on the surface of the mercury, in the short leg of the syphon, 
 and the pump is then ready to perform the office of alternately di awing in the 
 gas from the gas-holder, and compressing it into the portable lamps. The gas 
 sent out by the company was compressed into ^ of its original volume.
 
 AIR-STOVE. 
 
 AIR-STOVE. A stove, the hea: of which is employed to heat a stream of 
 air directed against its surface. The principle of tbe construction is, to enclose the 
 stove containing the fuel in a casing somewhat larger than the stove, so as to have 
 a space of a few inches between them. At the lower part of the cavity is an 
 aperture filled with a register to regulate the admission of the air, and at the 
 upper part is a similar opening to allow of its exit. When the air-stove is not 
 fixed in the apartment which is to be heated, a pipe is fitted to the upper aper- 
 ture of the casing, to convey the air to the apartment. The construction may 
 be varied to suit circumstances; the following cut is a representation of one which 
 has been used with very good effect to heat the Infirmary at Derby. It is upon 
 a plan which was first introduced in this country by Mr. Strutt, of Derbyshire, 
 who employed it for the purpose of warming his extensive cotton works more 
 uniformly and with greater economy than formerly. Fig. 1 is a section of the 
 air-stove and cockle; and Fig. 2, a transverse section of the stove, exhibiting the 
 disposition of the masonry surrounding the cockle, a, the cockle, is made of a 
 cubical form, with a dome, or rather a groined arch top, about 3 or four feet high,
 
 AIR-STOVE. 
 
 47 
 
 and is made of plate or wrought iron about -^ of an inch thick, riveted together 
 like the ordinary boilers of steam-engines. The smoke passes off by a narrow 
 passage at b, at the base of the cockle into the flue c, which leads to the chimney. 
 The brick-work surrounding the cockle is built with alternate openings, as 
 represented in the side view at/, at about 8 inches distant from the sides of the 
 cockle. Through these apertures pipes are inserted which may be made either 
 of sheet-iron or of common earthenware, so as to extend within an inch of the 
 
 cockle, by which means the air to be heated may be thrown near, or in imme- 
 diate contact, with the surface of the cockle if desirable, which was found by 
 Mr. Strutt to double the effect derivable from the same quantity of fuel. The 
 horizontal partition of the air chamber at d cuts off the communication between 
 the lower and the upper half of the chamber. The arched openings in the lower 
 half g g exhibit the openings of the main air flues leading from the exterior 
 atmosphere. The air passing from these lower flues g through the apertures 
 beneath the horizontal partition d d, and coming in immediate contact with the 
 body of the stove, must find its way into the upper air chamber h, through the 
 numerous apertures or pipes in the upper division, by which circuit its velocity 
 will be retarded sufficiently to obtain the necessary elevation of temperature
 
 48 AIR-STOVE. 
 
 from the heated cockle. In order that the air may not be injured for the 
 purposes of respiration, the size of these Belper stoves, as they are ca.led, must 
 be so regulated as not to heat the cockle or hody of the stove at an average 
 above 280o Fahr., according to Mr. Sylvester, or 250 according to Mr. i redgold, 
 when the air is intended to supply living rooms ; but for drying rooms more 
 heat may be given, if the saving of time is an object; but still it is far more 
 economical to dry at a lower temperature. From the upper, or hot-air chamber 
 h, a main flue i leads to each of the floors to be heated. The horizontal and 
 inclined parts of these main flues should be made of brick or stone, and if they 
 have to pass under ground, should be secured in a case. The vertical parts may 
 be of sheet iron, or even of well-seasoned wood. An opening over the door of 
 each room allows the entrance of the heated air into it, and a flue from the 
 bottom of each room proceeds to the roof of the building, from whence the 
 whole of the air is discharged by a turncap, the mouth of which is kept con- 
 stantly from the wind by a vane. Provided a stove of this construction is well 
 built, and so managed as not to allow the heated air to attain too great a tem- 
 perature, it is not only much more economical than any other mode of warming 
 extensive buildings, but it is equally salubrious with the more recent method of 
 employing steam pipes for this purpose, if not more so. As the air passages of 
 this kind of stove ought to be several feet under ground, it affords also a con- 
 venient mode of admitting a portion of cold air to the interior of the building 
 in the summer season, as well as supplying heated air in the winter. The 
 change in the temperature of the air by passing in this way, Mr. Sylvester says, 
 is greater than could be supposed. The cold air flue at the Derby Infirmary is 
 about 4 feet square, and its length 70 yards. In the month of August, when 
 the thermometer in the shade stood at 80, the air which entered the air flue 
 underground at the same temperature, was found to be 60 at the extremity 
 where it entered the stove-room ; the current at this time was sufficient to blow 
 out a lighted candle. In another experiment, when the outer air was 54, this 
 air was reduced to 51 by passing through the flue. This is a great advantage 
 of the air-stove above the use of the steam apparatus, since this last only supplies 
 the deficiency of heat in winter, but has no tendency to check it when the tem- 
 perature of the atmosphere is beyond the mean temperature of the earth. 
 
 But although close stoves, and air-stoves in particular, are decidedly more 
 effective and economical than open fire-places, still the prejudice is so strong in 
 England in favour of the latter, from their more cheerful appearance, and their 
 freedom from any unpleasant and confined smell, which is apt to arise from stoves 
 when they become highly heated, that there seems but little chance of the latter 
 superseding the former. It is therefore desirable, if possible, to derive from an 
 open fire-place a portion of the advantages of an air-stove, arid accordingly, many 
 combinations with that object have been devised. The following one is by 
 Mr. Ricketts, of the Strand ; besides the grate, it comprises an oven, boiler, and 
 hot-air chamber, all heated by one fire, without flues. No. 1 represents the 
 range, as fixed ; No. 2, the hot-air chamber distinct ; No. 3, a vertical elevation 
 of the same chamber : the same letters in each figure refer to similar parts, a 
 the hot-air chamber; b cold-air drain, or aperture, at bottom of the chamber; 
 c thin iron plates or ribs 2f inches wide, to direct the passage of the air against 
 the heated back of the chamber, producing a current of hot air which may be 
 communicated by pipes to any part of the building ; /conducting oven, heated 
 by an iron knob g ; h an iron boiler to which the steamers may be applied. 
 
 Fig. 2. 
 
 r
 
 It has been mentioned, that stoves are liable to the objection of sometimes 
 causing an unpleasant sensation from the air becoming over-heated, or, as it 
 is termed, burnt. This may be obviated by heating the air destined to circulate 
 in the apartments by steam, instead of employing the direct action of the fire. 
 An apparatus of this description, patented by Mr. Stratton, is shown in the 
 following figures. Fig. 1 is an elevation, and Fig. 2 a section of the apparatus. 
 It consists of an exterior tube of copper a, Fig. 2, within which is a smaller 
 tube b of equal length, soldered to end plates c c, forming thereby a steam-tight 
 vessel, surrounding the interior tube b. dd is a spiral apparatus of copper, 
 coiling round the upright rod e ; the periphery of this spiral exactly fits the 
 
 fig. I
 
 50 AIR-STOVE. 
 
 interior tube b, so that no air can pass up or down without taking a winding 
 course through the spaces formed by the spiral. / is a semi-globe of copper, 
 perforated with holes; and gg are two movable plates, in which are cut 
 oblong apertures, so that when the holes in each coincide the air has a free 
 passage through them ; but when they are moved by the lever h, so that the 
 holes in one are covered by those in the other, the passage is stopped, and the 
 air ceases to flow, i is a steam pipe, for the purpose of admitting steam 
 from a small boiler; and j is another pipe, for allowing the water formed 
 by condensation to run back into the boiler or elsewhere. Steam being 
 admitted into the compartment formed between the two tubes by turning the 
 cock, instantly heats the interior tube b, and (by radiation) the spiral dd, by 
 which the air already filling the tube is expanded, and rises by its diminished 
 gravity, escaping into the open atmosphere through the holes in the cap /. 
 The air underneath rushes in to fill the partial vacuum, and in its turn becomes 
 heated ; by this means a constant current can be kept up so long as the com- 
 partment is supplied with steam ; but this current would, in an unimpeded 
 passage, be much too rapid in its motion to become sufficiently heated for the 
 purpose intended. The spiral dd is therefore introduced, which causes the air 
 (as we have said) to take a winding course, and thus traverse the whole heated 
 surface of the spiral before its exit into the air. By this contrivance the air 
 is made to traverse over a considerable surface of heated material, while 
 the steam required to act therein is confined to a very short vessel, and, con- 
 sequently, but a small portion of its surface is exposed uselessly. It may 
 be cased" in wood or other non-conducting material, if desired, for ornament or 
 any other reason, without any diminution of its effect in warming the 
 apartment. 
 
 The following simple and ingenious air-stove is the invention of Mr. 
 Perkins, of Fleet-street, and the engraving represents a stove upon his 
 plan, which was put up on the premises of Messrs. Coe and Moore, printers, 
 Old Change. Fig. 1 represents the stove, flue, and building, in which 
 it is fixed. Fig. 2, a continuation of Fig. 1, on a smaller scale, extending 
 it above the roof of the building. The letters of'reference designate similar 
 parts in each figure. The stove a is of a cylindrical form, fixed vertically in 
 the brickwork ; it is closed above by the lid b, which is removed as often as may- 
 be required to supply the stove with fuel (coke is preferred), c c is the flue, 
 which is a tube of wrought iron, excepting that curved portion immediately 
 connected to the furnace cylinder, which is of cast iron, d is the ash pit. At i is 
 an elliptical aperture, for the supply of air to the fire, which may be admitted 
 in a greater or smaller volume by wholly or partially removing the cover k. I is 
 a furnace door, for affording convenient means for clearing out the ashes. The 
 grating on which the fuel is laid, is not fixed, as usual, immovably in the brick- 
 work, but is connected to the frame by hinges on one side, and held up on 
 the other by a cross-bar, which rests on a button m. This button being turned 
 one quarter round, the grating immediately falls as a trap door, discharging 
 all the fuel into the ash-pit, by which the fire is almost immediately extin- 
 guished without trouble. The stove is placed on the floor of the basement or 
 cellar, which is kept thoroughly warm and dry, so as to make it a good 
 store room for paper, although it is under ground; from thence the flue 
 ascends through the ground-floor re, the first floor o, the next floor p, and 
 passes through the roof, as shown. The flue for the smoke cccis surrounded, 
 as shown, by a larger tube, at about 3 inches apart, for the conveyance of 
 heated air to the several apartments. To effect this, cold air is freely admitted 
 through a large aperture r in the wall, which enters the chamber s, and im- 
 pinging upon a strongly heated surface, it immediately acquires a much higher 
 temperature. To increase this effect, the curved cast-iron neck of the flue 
 adjoining the stove is considerably flattened or expanded, so as to expose to 
 the ascending column of air a more extended surface of heated metal. The 
 caloric given out by the burning fuel, instead of being chiefly earned off by 
 the flue, as in ordinary stoves, is rapidly abstracted by the current of air, which 
 air, thus heated, may be wholly or partially given out into any one apartment,
 
 AIR BEDS. 
 
 51 
 
 *r distributed in the several apartments, as may be desired (either for 
 drying the printed sheets, or for warming the persons at work,) by a few sim- 
 ple valves or registers. These regis- 
 ters are made of two separate annular 
 plates, sliding circularly on their flat 
 surfaces one over the other. The lower 
 one is fixed by rivets to the sides of 
 the external tube, and the upper one lies 
 on the lower one, and is made to slide 
 over it by moving to the right or left a 
 small handle, which projects horizon- 
 tally through a slot mortice in the ex- 
 ternal tube. The size of the interstices 
 in these plates is both alike, as shown 
 in the separate Fig. u. By these registers, 
 it will be seen that the whole of the hot 
 air may be confined to one apartment, 
 or distributed over several. The aper- 
 tures through which the heated air flows 
 into the rooms, are 10 or 12 inches in 
 diameter, and each one is provided with 
 a cover like a saucepan-lid t, to prevent, 
 at pleasure, the hot air from entering 
 any particular chamber. In the upper- 
 most floor the flue of the hot-air tube 
 terminates at w, about 3 feet above the 
 floor ; from thence the smoke flue alone 
 ascends, which first rises a few feet, 
 then takes a horizontal course, and 
 afterwards passes through the roof; the 
 upper extremity is provided with a 
 canopy or cowl to keep out the rain, 
 and to prevent the smoke from being 
 forced downwards by sudden gusts of 
 wind. The premises before mentioned 
 are thoroughly warmed throughout the 
 winter, at as high a temperature as is 
 consistent with the comfort of the 
 persons employed therein, at an ex- 
 pense of less than nine pence per day 
 for fuel. But one of the chief advantages 
 that results from this apparatus, is the 
 convenient and facile manner by which 
 the heat can be augmented to the re- 
 quired degree in any apartment, for the 
 purpose of quickly drying the freshly 
 printed sheets of paper, an advantage 
 evidently of the first importance to 
 printers, as it enables them to print 
 their work with extraordinary despatch. 
 But when a stove of this kind is not 
 employed for drying moist substances, 
 the hot air should be first brought into 
 contact with a vessel of water, to render 
 the air sufficiently humid for healthful 
 respiration. 
 
 AIR BEDS. A bag of the size of a 
 bed, divided into several compartments, 
 and rendered air-tight by a composition, of which caoutchouc, or Indian-rubber, 
 orras the greatest part. This bag may be inflated by bellow*, a syringe, or any
 
 52 AIR THERMOMETER. 
 
 other means, and is furnished with stop-cocks to retain the air or let it out at 
 pleasure. These beds will be found extremely convenient to travellers, espe- 
 cially in warm climates, from their portability, and not being liable to vermin ; 
 also to invalids, from their perfect elasticity, which may be regulated at pleasure 
 by an attendant, without disturbing the occupant. 
 
 AIR VESSEL, IN HYDRAULICS^ contrivance to continue 
 the flowing of water after the impelling force has ceased 
 to act, as in the return stroke of a forcing pump or in 
 Bramah's hydrostatic press, thus preventing the shocks 
 which would arise from the sudden stoppage of the water 
 whilst in motion, and also avoiding the loss of power in 
 moving it from a state of rest at each effective stroke, it 
 consists of a vessel containing air, which is placed between 
 the delivery valve and the mouth of the delivery pipe, 
 and the water being forced through the pipe faster than 
 it can escape at the orifice, rises in the air vessel, com- 
 pressing the air therein with a pressure proportionate to 
 the pressure on the delivery valve. On the return stroke, 
 when the piston ceases to act, the air expands and continues 
 the flow of water until the pressure of the air is only equal 
 to the pressure of the column of water between the air 
 vessel and the mouth of the delivery pipe. See the cut, 
 in which a is the air vessel ; b a flange by which it is 
 
 attached to the delivery pipe or main; and c the exit 
 pipe. 
 
 AIR TRAP. A contrivance for excluding the effluvia arising from drains, 
 &c. The most simple and effectual trap for this purpose consists of what is 
 termed a water joint, which may be variously arranged. Fig. 1 represents the 
 construction commonly adopted for sinks in kitchens, &c. a is the pipe leading 
 to the drain, the upper end passing through the bottom of a small metal cup 
 
 b, the rim of which rises somewhat higher than the top of the pipe, and i< 
 cemented or soldered into the sink. Over the mouth of the pipe is inverted a cup 
 
 c, somewhat smaller than the other, and descending to 
 within a short distance of the bottom of b, and on 
 the top of this is fixed a strainer to prevent the pas- 
 sage of substances which would choke the pipe. Now 
 as the water in passing off by the pipe will always 
 leave the cup b full up to the top of the pipe, the cup 
 c will always be immersed to a certain depth in the 
 water, which will effectually prevent the escape of foul 
 air from the pipe a, for air being lighter than water, 
 cannot of course descend through it. Fig. 2 repre- 
 sents an air trap, which, instead of being made of 
 
 metal, is fabricated of the common red pottery, and is particularly adapted for 
 
 Fig. I. 
 
 Fiy. 2. 
 
 falling into a course of the " flooring 
 quarries," used in many parts of the 
 country, which are cleansed by washing 
 and sluicing them with water. In its 
 superficies it presents a square of 9 inches, 
 the same as the ordinary quarries, a is 
 the grating; b the trap frame. It will 
 be evident no foul air can pass up the 
 grating, as the only passage for it is 
 through the water, over the stop c, and 
 under d. 
 
 AIR THERMOMETER. The great sensibility of air to the influence of 
 heat, has induced the chemist to employ it in substitution of mercury and spirit 
 of wme in the construction of thermometers. The instrument is exhibited 
 in Fig. 1 on the following page, and consists of a tube with a bulb at the 
 upper end containing air. The cup beneath is to contain a little coloured
 
 ALARUM. 
 
 fluid, and if a portion of the air in the bulb be expelled by heat, it will, 
 on cooling, re-ascend the tube, and indicate changes in the temperature of 
 
 Fig. 1. 
 
 rise or fall 
 
 the surrounding bodies, by t 
 of the coloured fluid. 
 
 The double air, or differential thermo 
 meter of Leslie, consists of a small 
 tube, bent into the shape of the letter U 
 (Fig. 2,) and terminating at each extremity 
 in a small hollow ball. The tube contains 
 sulphuric acid, tinged red with carmine, 
 sufficient to fill the greatest part of it. 
 The glass balls are full of air, and both 
 communicate with the intermediate tube. 
 To one of the legs of the tube is fixed a 
 small ivory scale, divided into 100 degrees ; 
 and the sulphuric acid is so disposed, that 
 ^ ie g ra( ^ uate d l e ' ts u PP er surface stands 
 
 pposite to that part of the scale marked 0. 
 
 rmo- it ] 
 glass \/ 
 
 fig. 2. 
 
 The glass ball attached to the graduated 
 f the instrument is, by way of dis- 
 tinction, termed the focal ball. Supposing 
 
 this instrument to be brought into a warm room, the heat will act upon both balls, 
 
 and, expanding the included air in each equally, the liquid will remain stationary. 
 
 But suppose the focal ball to be exposed to heat, while the other ball is not ; the 
 
 air included in the focal ball will expand, while that in the other remains 
 
 unaffected. The air in the focal ball will therefore press more 
 
 upon the liquid in the tube, which will, of course, advance 
 
 towards the cold ball, and, therefore, the liquid will rise 
 
 in the tube above 0, and the rise will be proportional to the 
 
 degree of heat applied to the focal ball. This thermometer 
 
 is, therefore, peculiarly adapted for ascertaining the degree 
 
 of heat accumulated in a particular point, while the sur- 
 
 rounding atmosphere is but little affected, as happens in 
 
 the focus of a reflecting mirror. No change in the tem- 
 
 perature of the room in which the instrument is kept 
 
 is indicated by it, whilst the slightest alteration in the 
 
 spot where the focal ball is placed is immediately shown 
 
 by it. 
 
 AIR THERMOMETER, IN ELECTRICITY. This in- 
 strument, as arranged by Mr. Ronalds, is made more 
 substantially than the chemical thermometer just described, 
 and the bulb is larger in proportion to the other parts. It 
 consists of a stand supporting the tube and bulb, the latter 
 being furnished with two wires and rings, as shown in the 
 cut The tube contains a coloured fluid, and is provided 
 with a graduated scale. If it be required to assign the 
 amount of expansion by the electric shock when passed 
 through the common air, a communication is made between 
 the electrical machine and the rings by a chain, and the 
 expansion is shown by the depression of the coloured fluid 
 in the tube. 
 
 When thermometers are contrived to measure very great degrees of heat 
 by the expansions they produce in substances, or, on the contrary, the 
 expansion corresponding to different temperatures, they are characterized 
 by the name of Pyrometers ; for descriptions of several kinds of which see" 
 PYROMETER. 
 
 ALARM, OR ALARUM, is a term applied to a variety of instruments con- 
 structed for the purpose of producing sufficient sound or noise to awaken a 
 person from sleep, or otherwise to give notice of some occurrence, or warning, 
 of the state of the time, &c.
 
 54 ALARUM. 
 
 Colbert's Fire Alarm. This consists of a column of mercury in a tube, with 
 a floating piston, which ascends and descends as the mercury expands and con- 
 tracts A rod from the piston is connected at its upper end to a lever, which, 
 on be'ine raised, releases a click or retent, and discharges the alarm. The 
 apparatus is provided with a dial plate and index, pointing to the degrees of 
 
 at which is to be adjusted to a few degrees of heat above the temperature of 
 the atmosphere, or above the utmost height to which it is expected the mercury 
 might rise from natural causes during the night. It is enclosed in a case of 
 open fret-work, for the purpose of readily transmitting the heat, and is to be 
 deposited in the well of a stair-case, or other desirable place. 
 
 Congreve's Fire Alarm. The late Sir William Congreve suggested the em- 
 ployment of two metal plates placed in contact, with a cement between them, 
 that would melt at a low temperature. These plates were to be suspended by a 
 thread to opposite corners of a room, when it was considered that a slight 
 increase of heat would melt the cement, cause the plates to fall asunder, 
 and discharge the alarm. If the reader will refer to the experiments detailed 
 under the article ADHESION, he will find abundant reason to doubt the certainty 
 of the ready separation of the plates under the circumstances mentioned ; and 
 he will then probably give the preference to the following suggestion of our own. 
 Provide a common house-bell and spring. To that end of the spring by which 
 it is fixed to any object, tie a short piece of tape, sufficient to reach, when ex- 
 tended, only half way to the bell ; and to that end of the spring next to the bell 
 tie another piece of tape of the same length as the former. Then compress the 
 spring, so that the tapes can overlap each other, and insert between them a piece 
 of wax, (made of equal parts of common resin and bees'- wax,) which may be com- 
 pressed together by the fingers. The overlapping may be to such an extent as 
 will cause the wax to soften and the tapes to separate, on applying a heated 
 atmosphere to them of about 100 Fahr., when the elasticity of the spring will 
 produce the required clattering of the bell. 
 
 We shall now proceed to give a few examples of alarums for giving notice of 
 the arrival of predetermined periods of time, by means of easily constructed 
 mechanism, referring the reader to CLOCKS AND WATCHES for those of a more 
 
 elaborate nature. The above figure represents a watch alarum, which the 
 inventor states he has made several of, and that they answer extremely well. 
 In a solid frame of wood p q about 8 inches by 4, and 1 thick, is inserted a 
 metallic rod, bent into a right angle at b, to which are attached a small rod k, 
 and two fixed pulleys de. /is a cylindrical piece of wood, having inserted at 
 one end the pipe of a watch key, by which it may be made to rest on the pivot 
 of the watch, (the watch being sunk a little into the frame,) and turns with the
 
 ALARUMS 55 
 
 minute hand, and at the other, a pin which keeps it steady by passing through 
 a hole in the rod k. A thread which is fixed to the piece /, and may be rolled 
 roxind it, passes under the pulley e over d, and round the moveable pulley I, to 
 which the weight w is attached ; and being brought through a hole in the rod b a 
 is fixed there by the pin g. This pin is used to regulate the length of the thread 
 so that when it is completely wound off the cylinder /, the weight w may rest 
 on the plane h, which is moveable on a pin at m. The bell is fixed to one end 
 of a long spring r s t, the other end of which is fastened to the board at r; at 
 t is fixed a string, which keeps the bell in the position represented in the figure, 
 by means of a bit of wood o inserted into two notches, one in the plane h, and 
 the other in the horizontal part of the frame ; the friction of the bit o pre- 
 venting the plane h from falling. It will be easily perceived that by winding 
 the thread a certain number of times round /, the weight w will be raised to a 
 height from which it will take it so many hours to descend to the plane h, and that 
 when it does reach that plane, and press upon it, the bit o will be released from 
 the notch, and the elasticity of the spring will make the bell ring with consi- 
 derable violence. 
 
 An improved mode of releasing the bell, described in the foregoing plan, is 
 exhibited in the subjoined diagram, wherein the parts are drawn upon a larger 
 
 n 
 
 scale. In this figure the bit of wood o is supposed to be tightly pulled by the 
 string attached to the spring of the bell, its lower end being detained by a fixed 
 piece b b, and its upper end held by a bent piece of brass, which turns upon a 
 centre at c c, and whose other end sustains the plane h by pressing against the 
 piece a a. The descent of the weight depressing the plane h, causes the bent 
 piece of brass to swing loose and release the piece of wood which is connected 
 to the bell. 
 
 The annexed figure represents 
 a watch alarum that is sold in 
 the shops of London, and which 
 we have seen perform with con- 
 siderable accuracy. The expense 
 of it is only seven shillings, a a 
 is a turned mahogany stand ; b 
 the watch laid in a velvet cush- 
 ioned cavity adapted to receive 
 it, and placed in such a position, 
 that the hour at which a person 
 may wish to rise, shall be placed 
 opposite to a fixed index c. A 
 fine line, consisting of a single horse hau, with a loop at the end of it, is then 
 laid into the notch of a guide piece d, and the loop is then slipped over thehonr
 
 ALBUMEN. 
 
 passed over the extremity of the lever, and put on to the upright pin i. Wliei 
 DV the process of time, the hour hand has arrived at the period proposed, which L 
 opposite to the point of the index, the horse hair slips from it, the little weight 
 thereby becomes unsupported, pulls down the ivory lever, raising the hook of 
 the pin, which, releasing the spring, sets the bell ringing. 
 
 The periodical journals a few years ago abounded with plans of simple alarums; 
 and any person having a taste for such trifles in mechanics might easily multiply 
 them, as the materials as well as the arrangements of parts may be almost in- 
 finitely varied. Sand, passing through a minute perforation, (as in the hour-glass, ) 
 and charging a receptacle, whose weight in due time gave motion to a bell, was 
 a common expedient. The substances used for domestic light have also been 
 called into use, to show by their uniform decrease of quantity the time passed, 
 and by their decrease of weight in consequence allow the reaction of a constant 
 force to give motion to an alarum. The most perfect and elegant piece of 
 mechanism for this purpose, is Berrollas's patent watch alarum, which we have 
 fully described under the head HOROLOGY. 
 
 ALBUMEN. A viscous ropy fluid, found in its greatest purity in white of 
 eggs, from whence it derives its name. The serum or colourless part of the 
 blood, the crystalline humours of the eye, and all animal matters, contain it in 
 great abundance. It is also found in many vegetables, more particularly in 
 those which undergo spontaneous fermentation. The juice of the papau tree, 
 mushrooms, and many other fungi, contain considerable quantities. Pure 
 albumen may be obtained by agitating the white of an egg with alcohol, which 
 separates the aqueous particles. From the liquid thus obtained, it does not, 
 however, appear that more than 15J per cent, of dry albumen exists ; for if it 
 be exposed to a low gradual heat, it will lose about 80 per cent, of water, and 
 4J*of a liquid uncoagulable matter. According to the best analysis, it is 
 composed of 
 
 Carbon 52.883 
 
 Oxygen 23.872 
 
 Hydrogen 7.540 
 
 Nitrogen 15.705 
 
 100. 
 
 The most remarkable property of albumen is that of its coagulating or forming 
 a white solid substance, by the application of gentle heat. At the temperature of 
 1 60 Fahr. it solidifies, and is then insoluble in water. On this account, its existence 
 in water may be easily detected. According to Dr. Bostock, if water contain 
 < f of its weight of albumen, it becomes opaque on boiling, by the coagulation 
 \>f this substance. It may also be coagulated by a powerful voltaic battery. If, 
 after coagulation, a continued heat be applied, a semi-transparent horny sub- 
 stance is formed Albumen is soluble in water by agitation, but the coagulum 
 is not, unless artificial pressure be applied ; this may, however, be dissolved by 
 most of the acids. It is generally supposed that a minute quantity of sulphur 
 exists in albumen. If the serum of blood is evaporated in a silver vessel, a coat 
 of sulphuret of silver is formed : this also occurs when a spoon has been dipped 
 frequently in a boiled egg. Albumen is a delicate and valuable test for that 
 fatal poison, corrosive sublimate, which it precipitates from its solution in white 
 flocculi. It also renders the poison inert, and is therefore employed as a remedy, 
 A valuable cement for joining earthenware, china, stone, &c. is made by mixing 
 albumen diluted with water and quick lime. This cement will harden under 
 water, and sets in the open air almost immediately. Albumen is very extensively 
 employed in clarifying wines, and also in rendering leather supple, "it undergoes 
 decomposition rapidly if exposed to the atmosphere, and emits a very rauseous 
 odour. The coagulated albumen is not liahlp *o decomposition.
 
 ALCOHOL. 57 
 
 ALCHEMY. The word is derived from the Arabic al (the) and kemia 
 (excellent), and signifies the most exalted science. It is a branch of chemistry, 
 the objects of which were the transmutation of inferior metals to gold; the 
 discovery of an elixir vitae, or universal medicine ; an universal solvent ; and 
 other visionary and impracticable schemes. The Saracens are supposed to have 
 first introduced the art into Europe ; and so eagerly was it pursued by many 
 of the most exalted in station and even in knowledge, that monarchs have not 
 been ashamed to practise it, or to be duped by it. It is said that the Emperor 
 Caligula endeavoured to obtain gold from the sulphuret of arsenic; and Edward I. 
 witnessed an attempt made by Raymond Lully to obtain the precious metal 
 from iron, which it was believed he accomplished. Most of the alchemists 
 imagined that gold was the only elementary metal, and that the others were 
 merely gold contaminated by foreign matters, from which it was possible to 
 separate it. It was also imagined that mercury might be solidified, and that 
 silver would be the result. In these futile pursuits many lives were spent, and 
 splendid fortunes sacrificed. The art of the professors of alchemy was shrouded 
 in mystery, which none but the initiated could penetrate. Their language was 
 symbolical, and they either believed or propagated the notion that supernatural 
 influence was necessary, and might be commanded in their pursuits. The student 
 was sometimes required to qualify himself for the attainment of his object by 
 acts of devotion and charity. The operations were by some only attempted when 
 planetary influence was supposed favourable to success. So many exalted per 
 sons became the dupes and victims of the professors of alchemy, that in the reign of 
 Henry IV. an act was passed prohibiting all attempts to make gold or silver under 
 the pain of felony. From the numerous well-authenticated instances of persons 
 having procured gold by certain mystical operations with the aid of fire, it is 
 generally believed that a fraudulent slight of hand was practised. A hollow 
 rod, containing gold dust, is said to have been employed in stirring the contents 
 of the crucible, or the precipitated solution of gold used as a component in the 
 powder of projection. In these ridiculous attempts, however, many valuable 
 chemical discoveries were accidentally made. Porcelain china was first obtained 
 by an alchemist in search of the philosopher's stone. 
 
 ALCOHOL. The purely spirituous part of liquors, which have undergone 
 the vinous fermentation. It is the product of the saccharine principle formed 
 by the successive processes of vinous fermentation and distillation ; and all fer- 
 mented liquors will afford it. Although brandy, rum, arrack, malt spirits, and 
 the like, differ much in colour, taste, smell, and other properties, the spirituous 
 part, or alcohol, is the same in each. The chief properties of alcohol are the 
 following : It is a colourless transparent liquor, very movable and light, from 
 which cause the bubbles formed by shaking it subside instantly. Its smell is 
 poignant and agreeable, and its taste hot and pungent. It is so exceedingly 
 volatile as to be converted into vapour by the heat of the hand ; when exposed 
 to the air, it evaporates at 10 above the freezing point, and leaves no residue 
 except a little water, when not quite pure. It boils at about 165 Fahr., and it is 
 generally supposed that it cannot be frozen, although Dr. Huttou asserts that he 
 succeeded in freezing it ; but as he kept his method a secret, no one has been 
 able to repeat the process. Alcohol, when heated in contact with ah-, if it 
 be pure, burns with a light flame, without leaving any residue, and yielding by 
 the combustion a vapour, which is found to be nothing but water, and the weight 
 of which Lavoisier found to exceed by ] part the weight of the alcohol consumed. 
 Alcohol mixes with water in any proportion, giving out heat by the mixture ; 
 and a mutual penetration of the parts takes place, so that the bulk of the two 
 liquors, when mixed, is less than when separate. So strong is the affinity 
 between these two fluids, that water is capable of separating alcohol from many 
 of the substances which may be united with it; and again alcohol decomposes most 
 saline solutions, and precipitates the salts. The following substances are soluble 
 in alcohol in different proportions : all the alkalies, when pure ; several of the 
 neutral earths and metallic salts ; sulphur in vapour ; phosphorus slightly ; the 
 essential oils ; and the odorous part of vegetables, resins, and gum-resins, wax, 
 spermaceti, biliary calculi, &c. The following substances are insoluble in alcohol : 
 
 *H
 
 58 ALCOHOL. 
 
 the alkaline carbonates ; all the sulphates ; some of the nitrates and muriates; 
 metals ; metallic oxides and metallic acids ; all the pure earths ; the fixed oils, 
 unless when united to alkalies, or converted into drying oils by metallic oxides; 
 muscular fibre ; the coagulum of blood ; and albumen. To ascertain the purity 
 of alcohol, various methods have been devised. It has been thought that alcohol 
 which burns readily and leaves no residue is very pure, but this test is fallacious, 
 for the heat produced is sufficient to dry up part of the water. Another method 
 is, to drop a small quantity of it on gunpowder, and set fire to the spirit, and if 
 the spirit be pure, it will burn quietly on the powder, and the last portion of it 
 will ignite the powder, but if the spirit be watery, the powder will not explode. 
 This proof is, also, not to be depended upon ; for if any considerable quantity 
 of even the best alcohol be poured on a small quantity of powder, the water 
 which it affords as it burns, moistens the powder and prevents it from kindling ; 
 and if it be only barely moistened, any spirit that will burn will inflame it. 
 The most accurate method is to find its specific gravity by a hydrometer, noting 
 carefully at the same time its temperature. The uses of alcohol are very 
 numerous, and it is extensively employed in medicine and the arts. In com- 
 bination with copal, resin, &c. it forms varnishes. From its antiseptic power it 
 is well calculated to preserve anatomical preparations. Its gentle and steady 
 heat, unaccompanied by smoke, renders it eligible for burning in lamps ; and 
 from the impossibility of freezing it in any known degree of cold, it is well 
 adapted for indicating the lower degrees of temperature in the thermometer. 
 Having thus briefly noticed the properties and uses of alcohol, we shall proceed 
 to describe the process by which it is obtained, giving, at the same time, an 
 account of several modifications of the apparatus employed, which have been 
 recently invented, and embracing a description of the most improved French 
 distilling apparatus. The substances from which alcohol is chiefly prepared, 
 are the juice of the grape, molasses, grain, and the farina of potatoes ; these 
 substances containing a large portion of saccharine matter, which is the basis of 
 the vinous fermentation. The mode of extracting this saccharine matter depends 
 upon the nature of the substance operated upon ; but a saccharine solution 
 being obtained, the mode of converting it into alcohol is the same for them all. 
 The solution is first set to ferment, a certain quantity of yeast or other fermenting 
 principle being in some cases added. During the fermentation particular 
 attention must be paid to the temperature ; if it exceed 77 Fahr. the fermen- 
 tation will be too rapid ; if below 60 Fahr. the fermentation will cease. The 
 mean between these points is considered as the most favourable, and the fer- 
 mentation must be continued until the liquor grows fine and pungent to the 
 taste, but not so long as to permit the acetous fermentation to commence. 
 When the fermentation is finished, the liquor, if it be the juice of the grape, 
 is termed wine ; but if the produce of other substances, it is termed wash. The 
 wine or wash is put into a still (of which it should occupy about three- 
 fourths,) and distilled with a gentle fire, as long as any spirit comes over, 
 which is generally until about half the wash is consumed. The form of the 
 common still is too well known to need any particular description ; it generally 
 consists of a large boiler, made of copper, and fixed in masonry over a fire- 
 place. The boiler has a head of a globular form, to which is soldered a neck, 
 which, forming a complete arch, curves downwards, and fits into what is called 
 the worm. The worm is a long tube, generally made of pewter, of a gradually 
 decreasing diameter, and is curled round into a spiral form ; it is enclosed in a 
 tub which is kept filled with cold water during the distillation. The produce of 
 the first distillation forms what is termed low wines ; consisting of alcohol com- 
 bined with a large portion of water, on an average about one part of alcohol to 
 five parts of water. This is re-distilled, and affords proof spirit, consisting of 
 equal portions of spirit and water. The proof spirit being returned to the still 
 and re-distilled, the product is called spirits of wine or alcohol, being alcohol 
 combined with a very small portion of water, from which it is impossible to 
 free it by distillation, but which may be wholly or in great part removed by other 
 processes, to be hereafter described. The first important improvement in the 
 process of obtaining alcohol was introduced by a French chemist named Adam,
 
 ALCOHOL. 51 
 
 who, by a happy application of scientific principles, was enabled to dispense wit! 
 the tedious re-distillations, and to obtain alcohol highly concentrated by a singl< 
 oration ; economising time, labour, fuel, and (what in many 
 
 operation ; economising time, laoour, mei, ana \wutK in many situations is 
 highly important,) water for condensation; besides obtaining spirits of a superior 
 quality, with an increase in the quantity produced. The principle of his in- 
 vention consists in causing the vapour of the wine, with which the still is 
 charged, to pass through a quantity of wine contained in a vessel placed between 
 the still and the refrigerator, by which the vapour is condensed, and imparts its 
 heat and alcohol to the wine, until at length it enters into ebullition ; and as 
 this wine, besides its natural portion of alcohol, has received the alcohol con- 
 tained in the vapour of the wine in the still, its vapour will be more highly 
 charged with alcohol than the former, and this vapour in its turn is condensed 
 in another vessel similar to the former, and so on through a number of vessels 
 in succession, until it arrives at the refrigerator highly concentrated. His 
 apparatus in its arrangement resembled " Wolfe's apparatus :" between the still 
 and the refrigerator were placed three or four strong copper vessels, named 
 eggs, from their shape. From the head of the still a pipe proceeded to nearly 
 the bottom of the first egg, and from the top of each egg, a similar pipe pro- 
 ceeded to nearly the bottom of the next egg in succession, the pipe from the top 
 of the last egg being connected to the worm, which first traversed a vessel or 
 reservoir containing wine, and then passed through a vessel containing cold 
 water. From the wine reservoir a pipe went to the still, communicating also 
 with the bottom of the eggs, by means of cocks, for the purpose of charging the 
 still and eggs with the liquid for distillation, the several vessels being each filled 
 about three-fourths. When ebullition takes place in the still, the vapour issuing 
 from it is condensed by the wine in the first egg gradually raising its tem- 
 perature until it likewise boils, and its vapour (which is richer in alcohol than 
 the vapour from the still) is in like manner condensed in the wine of the second 
 egg, and so on through the remaining eggs, the vapour issuing from the last 
 into the refrigerator being highly concentrated. The upper part of the refri- 
 gerator being immersed in the wine reservoir, the alcoholic vapour in its passage 
 through the refrigerator gives out a portion of its heat to the wine by which it 
 is surrounded, and is finally condensed by the cold water in which the lower 
 portion of the refrigerator is immersed. When the vapour from the still no 
 longer contains alcohol, the contents of the still are discharged, and the still is 
 re-charged from the first egg, which is charged in its turn from the second, and 
 so on throughout the series, the last egg being charged from the wine reservoir, 
 the wine in which has been already considerably heated by the passage of the 
 alcoholic vapour through the refrigerator. Although the principle of this in- 
 vention is admirable, and has served as the basis of a great part of the subsequent 
 improvements in distillatory apparatus, yet, as was to be expected, improvements 
 have been introduced in the construction and arrangement of the parts, several 
 of which we shall lay before our readers, for which reason we omit giving a 
 drawing of the original. 
 
 About the same time that Adam introduced the important improvement just 
 described, M. Solimani, Professor of Natural Philosophy in the Central School 
 of the Gironde, contrived to obtain the same results by a different method. 
 The principle upon which lus invention is based is, that water to exist in the 
 state of vapour requires a temperature of 212 Fahr., whilst alcohol boils at 
 about 165 ; and that if a mixture of the two vapours be exposed to any tem- 
 perature between these two points, a portion of the watery vapour will be 
 condensed, which will be greater in proportion as the temperature is below 212. 
 The annexed figure represents Solimani's still, as improved by Curadau. a is 
 the door of the furnace; b the ash-pit; c the boiler, with a large cylindrical 
 head d; e the exit tube for the vapours, connected by a union joint to the worm 
 / in the tub g. This tub is filled with water, which is to be maintained at a 
 temperature depending upon the strength of the spirit required, and the spirituous 
 vapour that passes upwards through the worm /along the tube h, then descends 
 through the worm i i surrounded with wine, in the vessel k, where it becomes 
 condensed. The liquid spirit then runs through another yorm /, surrounded bv
 
 CO 
 
 AT.COHOL. 
 
 cold water, which completely cools it before it is discharged by the pipe n into 
 the recipient o. To prevent the water in the tub g from becoming too hot by 
 the passage of the heated vapours through the worm/, and to preserve it at an 
 even temperature, cold water from an elevated cistern is introduced at the 
 
 bottom by a pipe p, the quantity being regulated by a stop-cock; and the wine 
 which surrounds the worm i i in the tub k is supplied from a vessel above, by 
 means of the pipe q. This wine in the course of distillation grows hot : it is 
 therefore used to charge the still as often as the former charge is worked off, 
 and the spent wine drawn off by the cock t; and as it is economical to take off 
 the hottest portion, the cock q is opened, when the cold wine from the cistern 
 above enters at the bottom of k, and forces the upper or heated portion along 
 the pipe u into the boiler of the still. The spirituous vapours formed in the tub 
 k are conducted by the head r and the curved neck s into the worm /, where it 
 takes the course of the vapours which proceed from the still. The tub m is 
 kept as cold as possible by an ingenious contrivance of M. Curadau. A number 
 ?>f spiral pipes surround the tub on the inside, the ends of only two of which 
 are shewn in the figure to avoid confusion. Now, as the upper part of the tub 
 is always the warmest, a current of air is produced in these pipes, which serves 
 to cool the water in which they are placed. The worm / being surrounded 
 with a medium of about 180 Fahr. returns to the still the greater portion of 
 the watery part of the vapours, so that by this apparatus spirits of great strength 
 may be obtained at a single operation. 
 
 Berard's Improved Still. This invention consisted in the application of a lofty 
 neck and head to the body of a common still, which, being exposed to the 
 cooling influence of the air, a considerable condensation took place in those 
 parts, but the liquor thus re-formed was not permitted to run back immediately 
 into the boiler, but to fall upon partitions with raised ledges, so that the ascending 
 vapour had to traverse over the successive layers of fluid in the partitions, and 
 became for the most part condensed in its passage, only the strongest or purest 
 spirit passing beyond the head. 
 
 Instead of a more particular description of Berard's method, we shall proceed 
 
 ) the notice^ of Mr. Derome's still, in which the method is introduced with 
 
 considerable improvements. This apparatus consists of seven vessels or parts
 
 ALCOHOL. 01 
 
 performing separate offices : namely, a boiler A ; a distilling column B C ; a 
 rectificator C C ; a condenser I Q ; a refrigerator p ; and a reservoir s ; in 
 which the supply from another vessel U is regulated. It is considered prefer- 
 able to have two coppers like that at A, set in the masonry close to each other 
 
 so that the heated air from the burning fuel under one copper may be conducted 
 under the other. Two communications are also to be made between the two 
 coppers, the first by a pipe proceeding from the bottom of A to the upper part 
 of the other ; the second by another pipe rising from the top of the latter, (not 
 represented) and descending through the top of A to the bottom of the vessel, 
 to carry all the vapour generated underneath the liquid therein. At a b is a 
 glass tube to show the exact height of the liquid in the copper. The interior of 
 the distillery column, B C where the separation of the alcohol takes place, is full 
 of shelves perforated with small holes, through which the vapour from A neces- 
 sarily passes as it ascends, and comes in contact with the wine or liquid to be 
 distilled, that passes through the same apertures; both the wine and the spirit 
 are thus retarded in their progress, and become intimately mixed. The small 
 tube c d is of glass, to show the state of the process going forward in the rec - 
 tificator C C, which is only an extension upwards of the column beneath, 
 containing similar perforated shelves, and provided with a glass tube e f to 
 show the state of the process in this part. The vapour rising to the top of the 
 rectificator passes out through the neck H into a long worm, coiled horizontally 
 in the condenser I Q, which is a copper cylinder. This vessel contains wine
 
 62 ALCOHOL. 
 
 that becomes heated oy passing through the worm. To collect the spirit that 
 becomes condensed in the worm, the lower side of each coil has an opening 
 into a short tube, of which there are as many as there are coils to the worm. 
 To these tubes there are cocks, to draw off, as may be required, the products of 
 any or all of them (the most distant from the rectificator being of course the 
 strongest spirit,) either into the refrigeratory, by the upper long inclined tube 
 represented, or by the lower one back again into the rectificator for a second 
 rectification. The condenser is divided into two chambers, by a partition o, 
 with a communication between them at the lower part ; there are also three 
 manholes closed by lids M N O in the condenser, for the convenience of having 
 it cleaned ; and it has a cock F to draw off its contents. Thwine is constantly 
 supplied to the condenser by the pipe K L, and as constantly flows off by the 
 tube D E. p constitutes the refrigeratory or cooler, and is also a copper 
 cylinder containing a worm, that receives the condensed vapours through the 
 pipe I m, and delivers the cooled product through the opening V. The cooler 
 is constantly supplied with cold wine by the pipe R, which enters at the bottom 
 of the vessel, and the wine passes off at the top of the vessel by the pipe K L 
 into the condenser I Q. W is a cock, to empty the cooler ; S is the reservoir 
 
 which contains the wine ; it has a cock p, by the opening of which the quantity 
 >paratus is regulated; and in order that this 
 rm height by means of a ball cock q T, 
 the" pipe to which is connected with the principal reservoir, which, for example, 
 
 of wine to be supplied to the apparatv 
 
 may be equal, the liquid is kept at a uniform hei 
 
 may be the vessel U. 
 
 Mode of conducting the operation. The cock p being opened, the wine from 
 U passes through all the vessels into the two coppers, to the desired height, 
 which is ascertained by the two glass gauges. The distilling column is charged 
 with as much wine as will prevent a free passage of the vapour ; and when the 
 condenser and cooler are full, the entrance of more wine is stopped, and the 
 communication is not re-established by the cock p until the wine in the coppers 
 has parted with its alcohol, and the liquid in the condenser is hot enough to be 
 introduced into the distilling column. After this, a small stream, proportioned 
 to the size of the apparatus and the rapidity of the work, is kept constantly 
 running from S, and then begins what is termed the continued process, all the 
 previous work being only preparatory. After this, the supply of the vessels 
 with wine, the evaporation, condensation, and cooling, go on independently, 
 requiring only attention to the fire. 
 
 Winters Patent Distilling Apparatus consists of two vessels of a peculiar 
 construction, which may be applied to stills of every form ; and will enable the 
 distiller to extract the whole of the spirit contained in the wash at one operation, 
 instead of the repeated distillations necessary in the usual mode. These two 
 vessels contain condensers, which, as in Solimani's apparatus, are surrounded 
 by a fluid maintained at such temperatures, as to condense any desired portion 
 of the aqueous parts of the vapour from the still before it enters the refrigerator. 
 The apparatus is shown in the annexed Fig. 1. A is a tube by which the vapours 
 enter from the still into the first receiver B ; C a conical surface or plate ; D 
 the principal vapour tube, which being closed at the top, the vapours descend 
 by the small tubes G into the chamber F. These small tubes are placed all 
 around the principal tube, which are inserted in the holes shown in the engraving 
 iust above D. The apparatus is surrounded with water heated to 170, and is 
 contained in the tub or bath T, shown in section ; and as the vapours contained 
 in the tubes are, by this arrangement, separated into small portions, a rapid 
 condensation of the aqueous parts takes place. A number of bent tubes, as at 
 H, are fixed in the annular plate, which covers the receiver at B with their 
 upper ends, a little above the surface, which serve to carry off the condensed 
 liquid back into the receiver B. The vapour improved in its spirituosity, is 
 then collected in the chamber F, and passes from thence by the tube I into the 
 second receiver K. The top plate of this receiver K, as well as the bottom 
 plate of the third receiver N, have a number of openings or apertures forming 
 concentric circles, as at L L, Fig. 2, in the plan of the apparatus, which we also 
 annex. Into each of these annular apertures L L are fixed two copper cylinders,
 
 ALCOHOL. 
 
 one within the other, and only a quarter of an inch apart ; and as there are 
 tour such apertures, there are consequently eight cylinders, or four pairs in the 
 apparatus, which are exhibited in section in the annexed Fig. 1 . at M M. CO 
 
 Fig. 1. 
 
 are tubes which pass through the receiver at K, to convey water between the 
 
 cylinders ; similar tubes are passed through the receiver N, by which means 
 
 the water is diffused over every part of the extended surface of the apparatus, 
 
 Flg.9. 
 
 effecting thereby almost as rapid a condensation of the aqueous portion of the 
 vapour, as if the water were in actual contact with it. ..The vapours from the
 
 M ALCOHOL. 
 
 lower receiver K ascend, as before mentioned, through the narrow spaces 
 between the cylinders into the upper receiver N, in a high state of purity and 
 strength. From this last hold it proceeds into the worm by the tube P, where 
 it is instantly condensed by the refrigerating effect of the cold water, by which 
 this part of a distillatory apparatus is always surrounded. The water contained 
 in the second bath T, shewn in section, is heated to 140 (or less, as the strength of 
 the spirit may require,) that being a temperature at which the vapour of water, 
 as well as that from the empyreumatic oils, cannot exist. This apparatus is stated 
 to be so effective, that in an experiment made at an eminent distillery in London, 
 in the presence of several experienced distillers, " feints 80 per cent, under proof 
 were put into the still, and came out at one operation at 55 per cent, over proof." 
 Grimble's Patent Distilling Apparatus consists of a series of very small 
 tubes, fitted to the mouth of an ordinary still, the upper ends being received 
 
 into a clo^e box, from whence the uncondensed vapour passes on to the worin 
 whilst the condensed portion is returned to the still. It is shewn in the accom- 
 panying engraving where A is the still ; B the bottom box of the apparatus.
 
 ALCOHOL. 65 
 
 fitting on the still ; , b b a plate of copper, fitting on the box 13 ; c c c are open 
 tubes, through which the vapour ascends into the top box D, where the sepa 
 ration of the aqueous vapour takes place from the spirits ; the tubes ccc project 
 through the bottom plate of the box D, so that the oily and aqueous matter-, 
 are not allowed to return by the small tube, which would impede the vapour 
 issuing from the still, but run back into the still by the larger corner tubes d d, 
 which are on a level with the bottom plate at e e. The lower ends of these 
 tuoes are turned up syphon-wise, to prevent the ascent of the vapour from the 
 still, c c is a stay plate for the tubes ; in the box B is a range of tubes g g g, 
 through which a current of cold water is maintained when the spirit is required 
 very strong, (but not generally used) having its egress and exit at / h. F is 
 the pipe that conveys the spirituous vapour into the worm, and a thermometer 
 at E serves to regulate the operations. We understand that an apparatus of 
 this description is or was in use at Messrs. Booth and Co.'s distillery, but di 
 not know how far it answered the proposed end. 
 
 Evans's Patent Distilling Apparatus. The object of this invention is to 
 effect a more equal and uniform distribution of heat to the liquid under dis- 
 tillation, than is obtained in stills as hitherto constructed, as well as obtaining 
 spirits of great strength at a single operation. As the plan is totally different 
 from any of the preceding ones, and as some of the arrangements evince great 
 ingenuity on the part of the inventor, we lay it before the reader, without, 
 however, expressing an opinion as to its applicability in practice. The engraving 
 represents the whole operation at one view, a is a pipe which conveys the 
 wash or fermented liquor into a reservoir b, where it is maintained at a certain 
 level by the ball valve c. d is the still, which is a revolving copper cylinder, 
 with ledges fixed in horizontal lines against the inner surface, to increase the 
 agitation of the wash as it turns upon its hollow axis/^r; its motion is derived 
 from the spur-wheel h acting upon the pinion i fixed upon its hollow axis ; j 
 is the rectifier ; this is formed of a large pipe of uniform bore, coiled up into 
 the spiral figure exhibited, with the ends bent, so as to form axes for rotation, 
 on one of which a pinion k (corresponding to that at i) is fixed ; and this 
 pinion is acted upon by another spur-wheel /on the same shaft as the other; m 
 is the common distiller's refrigeratory ; and n a receiver for the distilled spirit. 
 The figure represented in dotted lines, is intended to show the position in 
 which the still is drawn up when it is necessary to cleanse it. For this purpose 
 there is at o a unive -sal joint, of a peculiar construction, which enables it to be 
 easily done, after having separated the connecting tubes at the union joint, 
 represented contiguous thereto. The rectifier j communicates with the still 
 through the hollow axle g, and with the refrigeratory through a stuffing-box ; 
 and the still communicates with the reservoir by means of a syphon passing 
 through the hollow axis f. The outward part of the syphon has two unequal 
 limbs ; the short one is inserted in the reservoir for the purpose of charging 
 the still with wash, and the long limb for discharging the spent liquor. In 
 order to charge the still, the ball of the valve is pressed downward, so as to 
 raise the liquid above the top of the syphon ; this sets the syphon in action, 
 and causes it to fill the still to the same level as the liquid in the reservoir. 
 Thus prepared the fire is lighted, and a slow rotatory motion i? given to the 
 still by hand or any other convenient first mover, applied to the shaft upon 
 which the spur-wheels h and I are fixed. The continuous motion of the liquid 
 prevents the formation of empyreuma, however fierce the fire may be ; and by 
 the agitation of the liquid, and the intensity of the heat applied, a rapid pro- 
 duction of vapour is caused, which immediately enters the hollow axis g, and 
 passes into the coiled worm of the rectifier^'. It is here necessary to observe, 
 that this capacious worm revolves in the direction pointed out by the arrow : 
 consequently whatever portion of the vapour becomes condensed in it, runs out 
 at every revolution back through the hollow axis g into the still, and the hollow 
 axis g is for this purpose made tapering wider towards the still, so as to giv c 
 the liquid a descent to run freely into it. The vessel j is, therefore, properly 
 termed a rectifier, as it separates the water from the diluted alcohol before 
 passing out of it into the refrigeratory m. In this it arrives in a stP f ? more 01
 
 ALCOHOL. 
 
 vapourized ; and this operation is unitbrmlv continue 1 Curing the rotation of 
 the vessel, owing to its passing through a tubular axis. The syphon in like 
 manner enables the still to be discharged without stopping the machinery. 
 When it is necessary to recharge the still with the fire under it, a thick cast- 
 iron sliding plate is drawn from the back, so as to interpose itself between the fire 
 and the still, and thus prevent any injurious effects to the contents of the latter
 
 ALCOHOL. 
 
 67 
 
 The following cngravmg represents an apparatus whi.h has been proposed 
 for distillation by means of steam or heated air, acting through the medium of an 
 extensive metallic surface upon a thin film of liquid, in 01 d?r to promote a speedy 
 evaporation at a comparatively low temperature, a is a tall cylindrical vessel 
 containing the fermented wash to be distilled, which is supposed to be supplied 
 
 regularly by a pipe from the brewhouse. By turning the cock in the pipe b, 
 the wash flows upon the exterior surface of the conical evaporator c, formed of 
 thin copper. The liquid is first received into a small basin, surrounding the cone 
 near its apex, having numerous small perforations at the bottom, by which 
 means the liquid is equally diffused in a thin stratum over the surface of the 
 cone c. d is the opening into the cone c, by which the heating medium is 
 admitted, and provided with a valve or cock for regulating the temperature ; 
 and the heat being maintained at about 180 but a small portion of aqueous 
 vapour would rise with the spirituous, and the spirit would thus be separated 
 at the commencement of the process from those matters which usually con- 
 taminate spirits of home manufacture. That portion of the wash that escapes
 
 68 ALCOHOL. 
 
 evaporation owing to the low heat, (and which would consist chiefly of water 
 and extractive matter,) will run off at the bottom of the cone by a circular 
 gutter, and from thence pass out by an aperture or pipe, as at e, while the 
 more spirituous rises between the inner cone c and the outer cone //, enters 
 the neck g, and from thence proceeding through the spiral worm, shown in 
 the wash vat a, is received into the recipient h, partly in the form of vapour, 
 and partly in the liquid state ; having in its passage through the worm com- 
 municated so large a portion of its heat to the wash in which the worm is 
 immersed, that a slight additional heat will be sufficient to separate its alcoholic 
 constituents. A small portion of strong spirituous vapour will collect in the 
 upper part of the vat a, which may be conducted off by the tube o into a separate 
 recipient or refrigeratory, as the spirits thus produced will be of superior purity. 
 The more volatile portion of the vapour passes onvyards through the open tube 
 i into the great refrigeratory k. This is a large cylindrical vessel or vat, with a 
 strong false bottom at /, into which are soldered a great number of small thin 
 pipes t t rising vertically and open at both ends, the upper extremities being 
 soldered into the bottom plate of the chamber m. The portion of the vat above 
 the false bottom I is kept filled with cold water by a service-pipe inserted at the 
 lower part, the vapour, therefore, rising up through the pipes t t, is exposed 
 very much subdivided to a very extended metallic surface, surrounded by cold 
 water, by which its caloric wul be very rapidly abstracted ; the condensed 
 liquid which then runs back down the pipes, meets with the rising vapour in 
 its progress, and, by that means, condenses a further portion at a higher tem- 
 perature than would have otherwise been accomplished, which is the object of 
 causing the vapour to proceed upwards instead of forcing it downwards, as in 
 the ordinary practice. By these arrangements it is expected that very little 
 vapour will reach the upper chamber m if the water is not allowed to get above 
 80 ; but if the supply of cold water should be insufficient for the purpose, the 
 vapour must proceed, of course, from the tube n to another refrigeratory. To a 
 bevelled wheel at q are attached two long bars, or scrapers r r, the edges of 
 which scrape or brush against the surface of the cone to clear it of sediment or 
 incrustrations, which will then fall to the bottom ; the bars are connected by a 
 ring at s ; such an apparatus will be useful in the distillation of liquids that 
 contain much extractive matter. From the above description it will be seen 
 that the distillation is carried on without intermission, the wash being admitted 
 in a small stream, in such quantity as to allow the alcoholic portion to be 
 evaporated in its passage over the heated surface of the cone c, and the remain- 
 ing portion to pass off in a stream by the waste pipe at e, as long as fermented 
 wash is supplied from the brewhouse. It has been stated, though we know not 
 upon what authority, that it has been found difficult to separate the alcoholic 
 from the aqueous parts of fermented liquors, by simply causing them to flow 
 over a heated surface ; and that preference has therefore been given to stills 
 constructed upon the combined principles of Adam and Solimani. 
 
 We have already mentioned the pulp of potatoes as amongst the substances 
 from which alcohol may be obtained ; and the manufacture has been for some time 
 past carried on in various places with great success. The apparatus and process 
 which we are now about to describe, are both of foreign invention, and were intro- 
 duced into this country by the patentee, M. Saintmarc, of the Belmont Distillery, 
 Vauxhall. The potatoes being first washed clean, are taken to a mill and ground 
 into pulp. This pulp is then mixed with a large quantity of water, which takes 
 up the chief part of the contaminating brown colouring matter, and it is then 
 poured through a coarse sieve, which, detaining those pieces that have escaped 
 the mill without being ground into pulp, they are rejected as ineligible for fer- 
 mentation, and applied to the feeding of pigs. The pulpy liquid thus freed 
 from the coarser pieces, runs into a trough containing a number of small holes, 
 and lined in the inside with a linen cloth sufficiently fine to prevent the floating 
 particles of starch from passing through , the water then drains through the 
 linen, leaving the pulp and starch to settle in a mass. When it has sufficiently 
 drained, and become solid and compact, it is removed from thence and laid 
 upon a plastered floor, which rapidly absorbs a great portion of its moisture.
 
 ALCOHOL. 
 
 09 
 
 To dry it entirely, it is afterwards placed in ft kiln or stove, which completes 
 that part of the process. In the dry state the pulp may be kept uninjured for 
 years, and may therefore be stored away for future use. The wet pulp being, 
 however, equally serviceable for immediate fermentation, there is no occasion to 
 dry it if the several processes in distillation can be carried forward at the tim* 
 
 Supposing the pulp to be used in the dry state, it is cut, or broken to pieces, 
 and mixed in the vat a, with sufficient hot water to bring it to the consistence 
 of cream. The vessel b, lined with lead, and called the decomposing vessel, is 
 then to be supplied with water to the depth of about six inches ; to this, a quantity 
 of sulphuric acid is to be added, in the proportion of three pounds of acid 
 to every hundred pounds of dry pulp ; hut only ten pounds of the acid to 
 every hundred pounds of the wet pulp. The diluted pulp is then to be dis- 
 charged from the vessel a, through the cock into b, containing the diluted 
 acid ; steam is then to be admitted from a boiler, (not shown in the engrav- 
 ing,) by turning the cock in the pipe e, which descends to the bottom of the 
 vessel, where it is made to issue from a steam-box ; the heat causes the mix- 
 ture to boil, and, after four or five hours' ebullition, the decomposition is con- 
 sidered complete. Before, however, describing the next part of the process, we 
 should notice that a worm-tub d, supplied with water from a service-pipe, is 
 placed on the top of the decomposing vessel ; the vapours from the boiling 
 liquid beneath enter this worm, and are therein condensed by transmitting 
 their caloric to the surrounding water ; and the water thus made hot, serves 
 for replenishing the vat a with fresh portions from time to time, as it may be re- 
 quired, by means of a connecting tube/furnished with a stop-cock. The contents 
 of the vessel b, after decomposition, are discnarged into the saturating vessel g, 
 and, during the time that it is running, a quantity of lime, or chalk, in solution, 
 may be poured in among it as long as any effervescence continues, which will 
 vary according to the degree of concentration of the acid ; but, in general, three 
 pounds of chalk, or lime, will be found sufficient to saturate each pound of sul 
 phuric acid employed in the preceding part of the process. The liquid in the 
 saturating vessel having now become transparent, it is to be drawn off into the 
 fermenting vat h, placed beneath, leaving the precipitated sediment undisturbed
 
 70 
 
 ALCOHOL. 
 
 at the bottom while the clear liquor is running. The discharge cock being 
 closed, the sediment may be stirred up with a quantity of water, to take up 
 whatever saccharine or fermentable matter it may contain ; this should be 
 allowed to subside again, and the clear liquor then to be added to the former in 
 the vat beneath. To promote the fermentation, a quantity of yeast is now to 
 be added to the liquid, in the proportion of three pounds to every hundred 
 pounds of potatoe pulp.. During the fermentation, which usually occupies from 
 fifteen to twenty days, the temperature of the liquid should be preserved at 
 from 90 to 100 Fahr., and the atmosphere of the room where it is conducted, 
 at from 80 to 85. The patentee having discovered that the introduction of 
 hydrogen gas facilitates the fermentative process,, besides increasing and 
 improving the product, further directs that the vat should be furnished with a 
 tube i, along which the gas is to be forced, by means of a pump, into the 
 liquid. The tube, after descending to the bottom of the vessel, takes a hori- 
 zontal serpentine course; in this part it is perforated with numerous small 
 holes, through which the gas escapes and bubbles up through the liquid. This 
 injection of the gas should be continued until the carbonic acid gas, in the 
 upper part of the vat, contains an excess of the hydrogen. The patentee is of 
 opinion that the introduction of hydrogen gas may be very advantageously 
 used, not only in this process, but in the fermentation of all matters from 
 which spirit or alcohol is to be extracted. When the vinous fermentation has 
 ceased, the liquor is to be drawn off through the tube into the still k. This 
 still is of the ordinary construction, except that instead of having a large head, 
 or capital, it has a long neck rising perpendicularly from the body, the object 
 of which is, that the aqueous part of the vapours may be condensed before 
 entering the inclined part, and fall back into the still, while the more volatile 
 or smrituous pass on alone into the bent arm, and from thence into the refri- 
 gerator or worm-tub /, where it is converted into the ordinary first product of dis- 
 tillation, called low wines (which is a very weak spirit). The low wines are 
 then taken to another called the low wine-still, a section of which is shewn in 
 the accompanying engraving. 
 
 m is the body of the still fixed in brick-work over a furnace ; a long perpen- 
 dicular neck proceeds from this as in the wash-still, the object of which is, that 
 the aqueous part of the vapour may be condensed as it ascends, and fall back 
 again into the still, while the more volatile and spirituous passes on through 
 the tube to the bo.ttom of the vessel o. This last-mentioned vessel has a tub 
 of cold water placed on the top of it, which is kept supplied by the service- 
 pipe p, and as the tube n passes through this tub, the greater part of the vapour 
 atnrst condenses and is received into the vessel o in a liquid form ; but as the 
 vapour is continually coming over from the still, the condensed liquor is at 
 length made to boil : the vapour filling the upper part of the vessel, from thence 
 passes up the tube r into the long cylindrical vessel s, which is partly immersed 
 ir a long cistern constantly supplied with cold water by the usual means. The
 
 ALCOHOL. 71 
 
 cylindrical vessel s is divided by five vertical partitions into six compartments, 
 but having a communication from one to the other by means of bent tubes pro- 
 ceeding from the upper part of the first compartment, to the lower part of the 
 second ; and, in the same manner, from the second to the third, the third to 
 the fourth, and so on. It will now be readily seen that the most aqueous part 
 ot the vapour will be condensed in the first compartment, while the more vola 
 tile passes to the second, where another portion of the vapour assumes a liquid 
 form ; the more volatile still will proceed to the third, and thence to the fourth, 
 fifth, and sixth, according as the spirit is more or less divested of aqueous particles, 
 all depending, of course, upon the degree of heat employed in the furnace fo? 
 raising the vapour in the still m, and upon the degree of coldness of the water 
 surrounding the condensing vessels. To ensure, however, the condensation of 
 all the vapour, a tube g proceeds from the upper part of the sixth compart- 
 ment, rises to a considerable height, then takes a horizontal course, and, 
 finally, descends into a spiral worm placed in a tub of cold water, where, 
 making a long circuitous passage, it is delivered from the bottom into a receiver 
 in so concentrated a form, as to be nearly in the state of pure alcohol. At 
 the bottom of the cylindrical vessel s, a separate short pipe, with a cock, pro- 
 ceeds from each compartment, leading into the long pipe u, which being also 
 furnished with a cock at either end, the spirit contained in any compartment 
 may be drawn off distinctly ; the contents of any, or all of the pipes, may like- 
 wise be drawn off by the pipe u into the vessel o for redistillation ; and the 
 vessel o may be discharged back into the still when desired, by the pipe v 
 having a cock for that purpose. Although this apparatus is well adapted for its 
 intended purpose, and is new in this country (where the vexatious nature of the 
 excise laws preclude, in a great measure, any improvements in the art of 
 distillation) we must observe that little invention has been displayed on the part 
 of the patentee,, as almost every part of it is copied from apparatus long since 
 invented, and in use in France. For a further account of distillatory appa- 
 ratus, we refer our readers to the article DISTILLATION, under which head will 
 be found a description of a great variety of stills and apparatus connected there- 
 with, which the length to which we have extended the present article prevents 
 our noticing in this place. 
 
 When, by repeated distillation, the alcoholic mixture is brought to a certain 
 degree of concentration, the affinity of the alcohol for the water with which it 
 is still combined, aided by the great excess in the proportion of the alcohol to the 
 water, becomes so great, that no further separation of the constituent parts of 
 the mixture can be effected by distillation. Alcohol being much lighter than 
 water, its spec. grav. is used as a test of its purity. Fourcroy considered it as 
 rectified to the highest point when its spec. grav. was 829, that of water being 
 1000 ; and this is, perhaps, nearly as far as it can be carried by mere distil- 
 lation. Alcohol, however, is not in this state pure (nor, indeed, is any process 
 known by which it may be rendered anhydrous, or perfectly free from water) ; 
 but it may be freed from a further portion of water by means of an alkaline 
 salt For this purpose, muriate of soda (common salt), may be advantageously 
 employed, by first depriving it of its water of crystallization by heat, and 
 adding it hot to the spirit. It is, however, considered preferable to employ the 
 sub-carbonate of potash. About a third part of the weight of the alcohol 
 should be added to it in a glass vessel, be well shaken, and then allowed to 
 subside. The salt will be found to have absorbed water from the alcohol 
 which being decanted, more of the salt is to be added, and the process con 
 tinued until the salt falls dry at the bottom of the vessel. The alcohol must 
 now be subjected to final distillation in a water-bath, to deprive it of the red 
 tint derived from the potash, as well as to free it from the alkali held in solu 
 tion. A most important improvement upon this method of rectification ha 
 been invented by a French chemist. It consists in placing a quantity of dry 
 muriate of lime, or other deliquescent salt, in a large shallow-covered vessel; 
 in this is placed another vessel of smaller dimensions, and resting upon the 
 bottom on short legs, and containing the diluted spirit (brandy for instance) to 
 be concentrated; the outer, or larger vessel, is then covered down, and properly
 
 72 ALCOHOL. 
 
 luted, to prevent the escape of the spirit. A series of double vesse.s aiv 
 arranged beneath the former, charged with the deliquescent salt only; and 
 pipes of communication lead from one to the other, and are furnished with 
 stop cocks. These arrangements, as well as the process, will be perfectly welj 
 understood upon reference to the annexed diagram, a is the vessel contain inj 
 the deliquescent salt; b, that containing the 
 dilute spirit ; the cover of a being well closed and 
 luted, it is left for several days to attract the 
 water from the spirit; and when the former is 
 supposed to be fully saturated with aqueous 
 particles, the spirit in b (considerably improved 
 in strength) is drawn off into d by turning the 
 cock c. This second vessel being also provided 
 with a stratum of muriate of lime, the process of 
 concentration recommences by a farther abstrac- 
 tion of the water contained in the spirit. In like 
 manner the spirit may be successively operated | f \. 
 
 upon by the salts contained in the vessels e and """ 
 
 /, and, if required, by an additional number of vessels, until alcohol of the 
 greatest purity is obtained. As each vessel is successively emptied, the satu- 
 rated salt is taken away and replaced with a fresh quantity of dry salt, when 
 it is ready to operate upon another portion of spirit let on from above. There 
 is another method by which the strongest alcohol may be obtained, although 
 the process, as usually conducted, is rather dilatory. It has been ascertained 
 that bladder is impervious to alcohol, although pervious to water ; so that if a 
 portion of alcohol be confined in a bladder, the water will be evaporated in the 
 course of a few days, whilst the alcohol remains, but in a highly concentrated 
 state. The following information on the subject is extracted from Ferrusac's 
 Bulletin, Mai, 1828, and, we doubt not, may be turned to practical advantage. 
 M. Soemmering, in a memoir to the Academy of Sciences at Munich, states 
 that alcohol in a vessel covered with a bladder, the latter not being in contact 
 with the fluid, loses, when exposed to a dry atmosphere, much of its water, and 
 becomes stronger ; but if the vessel thus closed be exposed to a damp air, the 
 alcohol attracts humidity and becomes weaker. In a second memoir the author 
 states more particularly the effect of bringing alcohol into more immediate con- 
 tact with the membrane. If a bladder be filled with 16 oz. of alcohol at 75, 
 and be well closed and suspended over a sand bath, or placed near a warm 
 stove, so as to remain at the distance of more than an inch from the hot surface, 
 it becomes in a few days reduced to a fourth of its volume, and is nearly or 
 quite anhydrous. M. Soemmering prepares for this purpose (Salves' or beeves' 
 bladders, by steeping them first in water, washing, inflating, and cleansing 
 them from grease and other extraneous matters, tying the ureters carefully, and 
 then returning them to the water to clear off more fully the interior mucosity. 
 After having inflated and dried the bladders, M. Soemmering covers them with 
 a solution of iclhyocolla, one coating internally and two externally. The 
 bladders thus become firmer, and the concentration succeeds better. It is better 
 not to fill the bladder entirely, but to leave a small space empty. The bladder 
 is not moist to the touch, and gives out no odour of alcohol. If the latter be 
 below 16 Baume", the bladder then softens a little, and appears moist to the 
 touch. Bladders prepared as above may be employed more than a hundred 
 times, although they at length acquire a yellowish brown colour, and become a 
 little wrinkled and leathery. The swimming bladder of the salmon is not fit 
 for these experiments. Alcohol of 72 was put into one of them, and after an 
 exposure of thirty-two hours, it had lost more than one-third of its volume, and 
 was weakened 12 : the alcoholic vapour was perceived by the smell. Of two 
 bladders of equal size, into one was put 8 oz. of water, and into the other 8 oz. 
 of alcohol. They were placed side by side exposed to a slight heat. In tour 
 days the water had entirely disappeared, whilst the alcohol had scarcely lost an 
 ounce of its weight. Mineral waters, and the water of wells, evaporate ana 
 deposit on the interior of bladders the saline particles which they contain.
 
 ALCOHOL. 
 
 73 
 
 the heat be conveniently managed, absolute alcohol may be obtained in from 
 six to twelve hours. Solar heat is even sufficient to procure anhydrous alcohol. 
 Wine placed in prepared bladders contracts no bad odour ; it assumes a deeper 
 colour, acquires more aroma and a milder taste, and becomes generally stronger 
 Spirits of turpentine of 75 contained in a glass vessel closed with a bladder, 
 lost nothing in four years. Concentrated vinegar lost the half of its volume in 
 four months ; the other half acquired more consistency, and had no longer an 
 acid taste. The water of orange flowers was about one-third evaporated in a 
 few months, appeared to have a stronger odour, and, consequently, had lost 
 nothing of its volatile principle. These experiments of M. Soemmering clearly 
 establishing the fact that bladder is impervious to alcohol, we have no doubt 
 that on account of the little heat necessary to effect this rectification, it may 
 be one of great economy, if an apparatus can be devised for conducting 
 the process extensively and with little labour. For this purpose we would 
 suggest that, instead of the ordinary animal bladder, the oesophagus of oxen 
 should be employed, as exposing a larger surface to the air, and as more con- 
 venient for fixing into a suitable framing, which might be placed in a heated 
 apartment, or, in warm climates, to the heat of the sun. Such an arrangement 
 u shewn in the following diagram, a a are the oesophagus bladders, distended 
 
 between a framing b b and c c, which is exhibited as broken away towards the 
 middle, to show that it may be made of any convenient length or width. The 
 bars d d connect the upper and lower pieces, and carry the pivots or axles 
 which turn in the cross beams or supports e e, shewn in section. The upper 
 side of the frame I b represents a square or round tube, in which are made cir- 
 cular apertures for the reception of the upper ends of the bladders a a, kepi 
 open and distended by wooden rings, and properly secured by cement The 
 lower ends of the bladders pass through similar apertures in the bottom rail, 
 where they are cemented and kept closed up and secured from injury by a 
 board screwed over them into the rail c c. We will now suppose that fifty (or 
 any other number) of such bladders are fixed to a frame, and charged with 
 diluted spirit, by means of a hose and nozzle connected to the cock /; that 
 done, the cock / is to be closed. In the same manner let all the other frames 
 in the apartment or manufactory be charged, of which there may be any number. 
 In 100 frames 2000 or 3000 gallons might be suspended. The whole should 
 then be submitted to a moderate heat, as of the sun, or a stove, &c. When it 
 is found that the spirit has parted with its aqueous fluid in any of the frames, 
 they are to be turned half way round on their pivots, by which the upper side
 
 74 ALCOHOL. 
 
 bb becomes the under, and the cock being opened, the concentrated spirit may 
 be discharged by means of a hose into suitable recipients. Instead of a movable 
 or swinging frame, a fixed one might be used, by forming the bottom rail (into 
 which the lower ends of the bladders are inserted) of a tube similar to the 
 upper one, and fitting it with a discharge cock. 
 
 From the circumstance of alcohol boiling at a temperature considerably 
 below the boiling point of water, many persons have supposed that its vapour 
 might be advantageously substituted for steam as a prime mover of machinery. 
 The first suggestion to this effect we think originated with the Rev. E. Cart 
 wright ; but we are not aware of any attempts to carry it into effect previous 
 to those of Mr. Howard, who took out a patent in 1825, for an apparatus for 
 the purpose, and endeavoured with great perseverance to bring it to perfection, 
 but, we believe, without success, as we cannot find that any engines of this 
 description have been brought into use. The following description, with the 
 annexed engravings, will explain the nature of the apparatus. A and B are 
 
 Fig. 1. 
 
 two cylinders of equal capacity, communicating at the lower part by a pipe, or 
 passage C. These cylinders contain a quantity of oil, mercury, or other fluid, 
 (which will not rise in vapour at the temperature to which it is to be exposed,) 
 sufficient to fill the base of one cylinder, and nearly the whole of the other 
 cylinder. Within the cylinder B is a piston exposed' above to the pressure oi 
 the atmosphere ; it has a piston rod, and is packed in the asual manner. In 
 the other cylinder A is a thin metallic dish D floating freely upon the surface 
 of the oil, or other fluid, before-mentioned. This latter cylinder has a top, per 
 fectly air-tight, fastened down upon it, and through a stuffing-box in the 
 centre of the top, passes a tube E terminating within the cylinder in a small 
 nozzle, pierced with numerous small holes. In the cover of the cylinder is a 
 flap-valve G, which is opened by a rod H striking it ; the valve is kept up to 
 its scat by a crane neck-spring above it ; the valve-rod works through an air-
 
 ALCOHOL 
 
 7') 
 
 light stuffing-box I ; a safety-valve K is placed on the top of the cylinder. la 
 the piston is an orifice fitted with a plug, by means of which the height of the 
 fluid above the piston (it should always be kept a little above the piston) may 
 be regulated ; and at N is a cock, by which the fluid may be withdrawn from 
 the cylinders. The cylinders, and the fluid contained therein, are heated by a 
 sufficient number of argand lamps placed beneath them; and the cylinder A, 
 and the lower part of the cylinder B, are surrounded by a casing, leaving a 
 small space between them, so as to confine and carry the heated air entirely 
 around them. On the top of the casing is a chimney P provided with a 
 register Q, the better to regulate the heat of the air within the casing. By 
 means of a small force-pump R, which is worked by the engine, a small quan- 
 tity of alcohol is drawn from the condenser, and thrown suddenly through the 
 pipe E on to the floating -dish D, which, being previously heated by the oil, or 
 other fluid medium, on which it floats quickly, converts the alcohol into vapour, 
 which, pressing upon the dish, and the oil on which it floats, forces the oil 
 through the horizontal passage, and raises the piston to its highest point of 
 elevation. The valve in the cylinder A being now opened, the vapour escapes 
 by a tube S into a separate vessel, and is there condensed ; the piston then 
 descends by the pressure of the atmosphere, and the dish D is carried again to 
 the top of the vapour cylinder A. The tube S is divided in the middle by a 
 flat ring a of wood, cork, or other non-conducting substance, making an air- 
 tight joint, and is inserted into a circular tube, or hollow ring V V, from which 
 a number of small thin copper pipes U U descend. The lower ends of these 
 pipes are inserted into another vessel W, which forms a reservoir for the 
 vapour when condensed. The liquid formed by the condensation of the 
 vapour, may be drawn off by the pipe and cock d. The outer and upper part 
 of the condenser, has upon it a circular open basin X, which is kept supplied 
 with water by a pump, or any convenient means. The small tubes U are each 
 
 wrapt round with flannel, or other porous sub- 
 stance of like nature, the upper end of which 
 hangs over the bason X into the water ; and, 
 acting like a syphon, conducts the water over 
 the surface of the tubes U, down into a vessel 
 Y below them. Within the circle, formed by 
 the small tubes, is a fanner kept in rapid motion 
 by the engine, by which means a stream of air 
 is thrown upon the wet flannel, and the heat is, 
 consequently, more rapidly extracted from the 
 condenser. Previously to setting the engine to 
 work, it is necessary to withdraw the air from 
 the vapour cylinder and condenser, which is 
 done by means of an exhausting pump or sy- 
 ringe, applied at c, to a pipe with a stop-cock 
 6 fitted on the top of the condenser. The liquid 
 to be converted into vapour for working the 
 engine, is introduced into the reservoir at the 
 bottom of the condenser, through a tube e 
 closed by a screw cap /. Fig. 2, shows a method 
 of affecting the condensation by injection. The 
 pipe * conveys the vapour from the vapour 
 cylinder into the condenser g, which is formed 
 of copper as thin as the pressure will admit of, 
 and which contains a portion of alcohol, which 
 may be introduced by the tube e as before, or 
 by a funnel o and a stop-cock p on the top of 
 g. A lifting pump h is put in motion by the 
 engine, at the same time that the valve G (in 
 
 Fig. 2. 
 
 Fw. 1) is opened, and the pump withdrawing a quantity of the alcohol from 
 the lower part of the condenser g, injects it into the same vessel at the top, 
 after passing it through a pipe or worm /, the end of which k being pierced with
 
 f(5 ALKANET. 
 
 many smaL holes, the liquid is dispersed throughout the vessel ff, and condensing 
 the vapour therein, falls with it to the bottom. Part of this liquid is again thrown 
 into the vapour cylinder by the pump R, to be converted into vapour, as before- 
 described ; and part of it is again employed to condense the vapour, as last 
 mentioned The condenser g and the tubes connected therewith, are placed m 
 a cistern which is kept constantly full of cold water. The engine above described 
 acts against the pressure of the atmosphere, which also effects the return stroke of 
 the piston. The following diagram presents an 
 outline of an arrangement for avoiding this, 
 and producing a double action, a a are the 
 vapour vessels ; b is the piston cylinder ; c the 
 piston working horizon tally. The arrangement 
 of the lamps, injecting tubes, &c. is upon the 
 same principle as before. The vapour is 
 alternately generated with the two vessels a a, 
 and withdrawn from them, and acts upon the 
 
 Siston through the medium of the oil or other 
 uid, upon which, or upon the thin copper 
 floats d d, the small quantity of fluid to be evaporated is injected, as before 
 described. The patentee states that aether or essential oils might be substituted 
 for alcohol, although he considers the latter preferable upon the whole, as it is 
 more readily and effectually condensed. We have seen an alcoholic engine, 
 intended for a 24-horse power, in occasional operation at the Iron Works at 
 Rotherhithe, where the patentee perseveringly continues his experimental efforts 
 on the great scale. 
 
 ALE. The name given to a species of malt liquor. See BEER. 
 
 ALEMBIC. The name formerly given to a common distillatory apparatus, 
 now termed a still. See ALCOHOL and DISTILLATION. 
 
 ALKALI. The term is derived from an Arabic word kali, the name of a 
 plant containing an alkali. The alkalies possess these general properties in 
 their pure state. They are caustic and acrid to the taste. They dissolve animal 
 matter, and form a saponaceous compound with oils or fat. They combine with 
 acids in definite proportions ; the respective properties of each are destroyed, 
 and a neutral salt is the result. On this account, they precipitate most metals 
 from their acid solutions. They change most of the vegetable blues to green, 
 and restore the colour of a vegetable blue reddened by an acid. They combine 
 with water in any proportion. The most important of the alkalies in commerce 
 and in the arts, are potash, soda, and ammonia. The two former of these are 
 generally called the fixed alkalies, and the latter, the volatile. Some of the 
 earths possess powerful alkaline properties, and have, therefore, by some writers 
 in chemistry, been classed with the alkalies: these are lime, magnesia, barytes, 
 and strontites. Many vegetables also contain matter decidedly alkaline ; such 
 as morphia, hyosciama, strychnia, &c. The properties and uses of these 
 bodies, will be found under their respective heads. 
 
 ALKALIMETER. An instrument for ascertaining the strength of alkalies. 
 The best, perhaps, is a tube graduated into a number of equal parts. Acid of 
 a known specific gravity, diluted with water, and coloured with infusion of 
 litmus, is poured in until a given number of parts is occupied. The alkali 
 to be tried is accurately weighed, and gradually added to the dilute acid, until 
 the original blue of the litmus, reddened by the acid, is restored. The relative 
 quantity of an alkali requisite to neutralize a given portion of acid of uniform 
 strength, is a test of its strength. 
 
 ALKANET, or BUGLOSS. A genus of the Monogynia order, belonging to 
 the Pentandria class of plants. It is found chiefly in the warmer regions of the 
 continent ; that which grows in England is inferior in the colouring power of 
 its roots, for which the plant is chiefly valuable. The greatest quantity is raised 
 in France, from whence it is principally obtained. If the root of this plant is 
 digested in oil, alcohol, or unctuous matter, a deep red colour is extracted, 
 which is extensively employed in colouring various unguents, and also in 
 staining mahogany and marble. The colouring matter exists in the l/ark of
 
 ALLOY. 77 
 
 the plant ; and as the roots contain most bark, a greater quantity of colouring 
 matter is extracted from them than from the other parts. 
 
 ALLOY. A combination of two or more metals. The term ia sometimes 
 employed to denote the inferior metal combined with gold or silver. Thus it 
 is said the standard gold of jewellers is 18 carats of gold and 6 of alloy, what- 
 ever metal the alloy may be. When metals are combined either by fusion or 
 cementation, the alloy formed generally possesses properties and characters 
 very different from those of the respective components. The density is some- 
 times greater, sometimes less ; the fusing point in some cases is considerably 
 lower than the mean. Elasticity is sometimes communicated, sometimes de- 
 stroyed ; and the malleability and ductility of the alloy seldom correspond 
 with those of the metals forming it. These important changes would lead to 
 the inference, that alloys are chemical combinations, and not mechanical mix- 
 tures; but there are many objections to this supposition, the most important 
 of which are, that metals may be combined in any proportions, and that they 
 may be separated by the process called eliquation, if there is a great difference 
 in the respective temperature of their fusing points. Thus, silver and lead may 
 be separated from copper by heat, the copper requiring a higher temperature 
 for its fusion than the other two metals combined ; and an alloy containing a 
 volatile metal, as mercury, or zinc, may be decomposed by a strong heat, the 
 fixed metal remaining when the more volatile is expelled. In many cases, a 
 very small proportion of one metal is sufficient to change the most important 
 characters of another. A quarter of a grain of lead will render an ounce of 
 gold perfectly brittle, although neither gold nor lead are brittle metals. If a 
 crucible containing arsenic be placed in the same fire with a crucible containing 
 gold, the fumes of the arsenic will render the gold brittle. Some of the changes 
 thus produced are of the utmost importance in the arts, as many of the alloys 
 are far more valuable on account of the newly-acquired properties, than any of 
 the simple metals. Gold and silver, in their pure state, would be totally unfit 
 for the useful purposes to which they are applied, if they were unalloyed, on 
 account of their softness. Even the standard current coin of the realm i 
 alloyed, to render it hard, otherwise the impression would be speedily effaced, and 
 the coin, by abrasion, would soon become deficient in weight. Pure copper 
 would be unfit for many of the purposes to which it is so extensively applied in 
 the arts, if it were not alloyed by some metal to give it hardness ; and it is sin- 
 gular that the metals employed for this purpose are all soft metals. Brass, 
 bell-metal, gun-metal, &c. are all alloys of copper with soft metals. Some 
 metals which will not combine together immediately, may be united by the 
 intervention of a third. Thus, mercury will not combine directly with iron ; 
 but if zinc or tin is first added to the iron, an amalgam may be formed of it 
 with mercury. It may here be observed, that when mercury is united to any 
 other metal, the compound is called an amalgam. In order to make a perfect 
 alloy, a very intimate admixture, by mechanical agitation, should be effected 
 while the metals are in the fluid state. They should, therefore, be either con- 
 stantly stirred with an infusible rod, or repeatedly poured from one hot crucible 
 to another. Mr. Hatchett found that the lower end of a bar of standard gold 
 was of inferior specific gravity and value to the upper extremity, which would 
 be formed by the last portions of the metal in the crucible. The surface of 
 metals, also, should be carefully defended, while in the fluid state, from the 
 action of the atmosphere, by a stratum of wax, pitch, or resin, if the fusing 
 point be low; or by a layer of salt, pounded glass, borax, &c, if it be high. In 
 this article we shall merely give a brief account of the nature and composition 
 of the most important alloys, and their respective uses. Where the mode of 
 manufacture is complicated, and requires peculiar processes, we shall more fully 
 describe them under their several heads. 
 
 Brass is composed of variable proportions of zinc and copper, according to the 
 use for which it is required. In general, about9 parts of zinc are added to!6 of cop- 
 per when melted. The best brass is not made by the direct combination of the two 
 fluid metals, but by the process called cementation (See CEMENTATION). The 
 vapour of the zinc ore by this mode combines more intimately with the copper
 
 78 ALLOYS. 
 
 Manheim Gold. Three parts copper, 1 part zinc, and a small quantity of tin 
 If these metals are pure, and are melted in a covered crucible containing char- 
 coal, the alloy bears so close a resemblance to gold as to deceive very skilful 
 persons* 
 
 Tombac, or White Copper, is formed of variable proportions of copper, 
 arsenic, and tin. 
 
 Pinchbeck. five oz. pure copper, and 1 oz. zinc. The copper must be first 
 melted before the zinc is added. 
 
 Prince's Metal is made of from 2 to 3 parts of copper, and 1 of zinc ; or of 
 common brass, with an extra portion of zinc. -^^\^ 
 
 Bell Metal. Six to 10 parts copper, and 2 parts one. 'For small bells, a 
 little zinc is added, and sometimes silver. 
 
 Tutania, or Britannia Metal. Four oz. plate brass, and 4 oz. tin ; when fused, 
 add 4 oz. bismuth, and 4 oz. antimony This composition is added at discretion 
 to melted tin. 
 
 German Tutania. Two drms. copper, 1 oz. antimony, and 12oz. tin. 
 
 Spanish Tutania. Eight oz. scrap iron, or steel, 1 Ib. antimony, and 3 oz. 
 nitre. The iron or steel must be heated to whiteness, and the antimony and 
 nitre added in small portions. Two oz. of this compound are sufficient to 
 harden 1 Ib. of tin. 
 
 Queen's Metal. Four and a half Ibs. tin, Ib. bismuth, Ib. antimony, and 
 Jib. lead. Or, 100 Ibs. tin, 8 Ibs. antimony, lib. bismuth, and 4 Ibs. copper 
 This alloy is used for making tea-pots, and other vessels, which imitate silver. 
 
 Red Tombac. Five and a half Ibs. of copper, and Ib. zinc. The copper 
 must be fused in a crucible before the zinc is added. This alloy is of a red 
 colour, and possesses greater durability than copper. 
 
 White Metal. Ten oz. lead, 6 oz. bismuth, and 4 drms. antimony. Or, 2 Ibs. 
 antimony, 8 oz. brass, and 1 oz. tin. 
 
 Gun Metal, One hundred and twelve Ibs. Bristol brass, 14 Ibs. zinc, and 
 7 Ibs. block tin. Or, 9 Ibs. copper, and 1 Ib. tin. Lead was formerly used in 
 this alloy to facilitate the casting, but at the battle of Prague it was found that 
 some of the pieces of ordnance formed of this metal were actually melted by 
 the frequency of firing. 
 
 Blanched Copper. Eight oz. copper, and oz. neutral arsenical salt, fuser" 
 together under a flux of calcined borax and pounded glass, to which charcoal 
 powder is added. 
 
 Specula Metal. Seven Ibs. copper, 3 Ibs. zinc, and 4 Ibs. tin. These metals 
 form an alloy of a light yellow colour, possessing much lustre. 
 
 Metal for Flute Key Valves. Four oz. lead, and 2 oz. antimony. 
 
 Printing Types. Ten Ibs. lead, and 2 oz. antimony. The antimony is added 
 while the lead is in a state of fusion. The antimony gives hardness to the lead, 
 and prevents its contraction when cooling. Some manufacturers employ different 
 proportions of these rnetals, and some add copper or brass. 
 
 Small Type Metal Nine Ibs. lead, 2 Ibs. antimony, and 1 Ib. bismuth. The 
 antimony and bismuth are added when the lead is melted. This alloy expands 
 in cooling ; the mould is, therefore, entirely filled when the metal is cold, and no 
 blemish is found in the letters. Stereotype plates are formed of this alloy. 
 Some manufacturers employ tin instead of bismuth. 
 
 Common Pewter. Seven Ibs. tin, 1 Ib. lead, 6 oz. copper, and 2 oz. zinc. The 
 copper must be first melted before the other metals are added. 
 
 Best Pewter. One hundred parts tin, and 17 parts antimony. 
 
 Hard Pewter. Twelve Ibs. tin, 1 Ib. antimony, and 4 oz. copper. 
 
 Common Solder Two Ibs. lead, and 1 Ib. tin. 
 
 Soft Solder. Two Ibs. tin, and 1 Ib. lead, 
 
 Solder for Steel Joints. Nineteen dwts. fine silver, 1 dwt. copper, and 2 dwts. 
 brass. 
 
 Silver Solder for Jewellers. Nineteen dwts. fine silver, 1 dwt. copper, and 
 10 dwts. brass. 
 
 Silver Solder for Plating. Ten dwts. brass, and 1 oz. pure silver. 
 
 Gold Solder. Twelve dwts. pure gold, 2 dwts. pure silver, and 4 dwts. copper.
 
 ALLOYS. 79 
 
 Bronze. Seven Ibs. copper, 3 Ibs. zinc, and 2 Ibs. tin. The copper must be 
 melted before the other metals are added. 
 
 Mock Platinum. Eight oz. brass, and 5 oz. zinc. 
 
 Alloy of Platinum with Gold. Fifteen parts pure gold, and 1 part platinum. 
 The gold must be melted before the platinum is added. This alloy is whiter 
 than gold. Platinum has the singular property of depriving gold of its peculiar 
 colour; if ten parts of gold are combined with only one of platinum, the alloy 
 will appear of the colour of platinum. There is another remarkable property 
 attending this alloy of gold and platinum, that it is soluble in nitric acid, which 
 does not act upon either of the metals in a separate state. 
 
 Ring Gold. Six dwts. 12grs. pure copper, 3 dwts. 16grs. fine silver, and 
 1 oz. 5 dwts. pure gold. Jeweller's gold is made of variable proportions of pure 
 gold and copper, and sometimes of silver. 
 
 Imitation of Silver. One Ib. copper, and } oz. tin. This alloy will be of a 
 deeper colour than silver, but in other respects it is very similar. 
 
 Alloy of Platinum with Steel. Platinum although the most infusible of 
 metals, when in contact with steel melts at a comparatively low temperature, 
 and combines with it in any proportion. This alloy does not rust or tarnish 
 by exposure to a moist atmosphere, for many months. The alloy is malleable, 
 and is well adapted for instruments which would be injured by slight oxidation 
 as mirrors for dentists, &c. The best proportions do not yet appear to be known , 
 out it appears that if much platinum be used, the alloy has a damask or wavy 
 appearance. Steel for cutting instruments is much improved by even ^th of 
 platinum. 
 
 Alloy of Silver and Steel. Steel 500 parts, and silver 1 part. If a large 
 proportion of silver is employed, the compound appears to be a mechanical 
 mixture only. The silver is distinctly seen in fibres mixed with the steel, and 
 the alloy is subject to voltaic action. When the proportion does not exceed 
 (jjj, the compound appears to be a chemical union ; the steel is rendered much 
 narder, forges remarkably well, and is infinitely superior to the best cast steel 
 for cutting instruments, &c. 
 
 Alloy of Steel with Rhodium. If from 1 to 2 per cent, of rhodium be com- 
 bined with steel, the alloy possesses great hardness, with sufficient tenacity to 
 prevent cracking, either in forging or hardening. This alloy requires to be 
 aeated about 73 Fahr. above the best English cast steel in tempering. It ie 
 superior to that metal ; but the scarcity of rhodium will prevent the extensive 
 use of this valuable compound. 
 
 Fusible Alloys. Four oz. bismuth, 2J oz. lead, and 1 J oz. tin. Melt the lead 
 first, and then add the other metals. This alloy will melt in boiling water, 
 although the melting temperature of the several components is much higher ; 
 viz. lead, 612; bismuth, 476; tin, 442. 
 
 ALMOND. The well-known kernel of certain fruit trees, of which there 
 's great variety. Almonds contain a considerable quantity of oil, on which 
 account they are chiefly valuable. As an article of food, they possess little 
 nutritious matter, and if taken immoderately, are indigestible, and even poisonous, 
 on account of the prussic acid they contain. Bitter almonds yield a greater 
 quantity of this poison than the sweet ; they are therefore poisonous to some 
 birds and small animals. Water distilled from almonds and other kernels, is 
 found to be destructive of human life. Noyeau and other cordials flavoured by 
 these substances, contain much of the bitter principle, or prussic acid. The 
 oil of almonds may be extracted by simple pressure ; if they are heated, a 
 greater quantity is obtained. The oil from the bitter kernel is as tasteless as 
 that from the sweet ; the bitter principle is soluble in, and may be extracted by, 
 water. Sweet almonds are extensively employed in medicine in the form of 
 emulsion. They are skinned, and triturated in a mortar with a small quantity 
 of water. After standing a short time, a thick cream separates, which will 
 render many resinous substances mixible in water. The almond emulsion is 
 generally combined with gum or sugar. 
 
 ALOES. The aloe is a plant of the Monogynia order, belonging to tne 
 Hexandria class. The medical substance called aloes, is the inspissated juice
 
 80 ALTITUDE. 
 
 of the plant. There aie three sorts of this, viz. socotrina, hepatica, and cabal- 
 lina. The first of these, which is considered the best, comes from the island 
 Socotora, whence its name. It is of a glossy appearance, and in a slight degree 
 pellucid ; if reduced to powder, it is of a bright golden colour. The hepatica 
 is so called from its liver colour, and is chiefly brought from Barbadoes in large 
 gourd shells. Its taste is intensely bitter and nauseous. The caballina is 
 principally used as a medicine for horses, from which circumstance it derives 
 this appellation. It is cuarser and more impure than the others, and has a 
 rank strong smell. The three varieties have, however, all been obtained from 
 the same plant, at Morviedro, in Spain. The first, from the liquid which flows 
 spontaneously from the incised leaf; the second, from the juice afterwards 
 extracted by pressure ; and the third, by mixing the expressed juice with the 
 dregs of the former. Pure aloes are nearly soluble in water and in alcohol. 
 They are powerfully aperient, and in large doses produce much irritation : small 
 doses are tonic and aperient. 
 
 ALTITUDE. The height of any place or thing ; one of the three dimen- 
 sions of solid bodies ; elevation of the celestial bodies, &c. In geometry, the 
 altitude of a figure, or a solid, is the perpendicular distance between its vertex 
 and base. The altitude of buildings, trees, &c. may be measured like that of 
 geometrical solids, from the base to the vertex, but the altitude of lofty moun- 
 tains or elevated plains is reckoned from the level of the ocean. There are 
 various means for determining altitudes, such as geometrical construction ; by 
 observation of shadows ; by trigonometrical calculation ; and by the use of the 
 barometer. For an account of the various instruments employed as quadrants, 
 sextants, theodolites, barometers, &c., with the methods of applying them, con- 
 sult their respective names. The altitude of terrestrial bodies may be either 
 accessible or inaccessible. When the object viewed is accessible, and on the 
 same horizontal plane as the observer stands, its altitude may be found in the fol- 
 lowing way : Provide two deal rods, one longer than the other ; fix the shorter 
 one vertically in the ground, and having placed your eye at its top, let an 
 assistant move towards the tower in a direct line, till the top of the second rod 
 is seen on a line with the summit of the object whose altitude is required. Next 
 measure the distance between the two rods, and also between the shorter rod 
 and the tower. Then say, as the distance between the two rods is to the dis- 
 tance of the shorter rod from the tower, so is the difference in length of the 
 rods to the difference between the height of the tower and the shorter rod. 
 Hence, if to this difference we add the length of the shorter rod, it will give 
 the altitude required. The result may, however, be more conveniently, as well 
 as more accurately obtained, by means of a quadrant, or other instrument to 
 measure angles, in the following manner. Measure the distance of the observer's 
 place from the foot of the tower, and take the angular elevation by means 01 
 the quadrant ; then say, as the cosine of the observed angle is to the measured 
 distance, so is the sine of the observed angle to the altitude required. Altitude, 
 in astronomy, signifies the angular distance of a celestial body from the horizon, 
 measured on a vertical circle. The altitude is either true or apparent, accord- 
 ingly as it is measured from the rational or the sensible horizon. The observed 
 or apparent altitude varies from the true on two accounts. First, the body is 
 seen from the surface of the earth, instead of from the centre, which causes it 
 to appear lower than its true place, by a quantity which is denominated the 
 horizontal parallax. Secondly, the rays of light by which the body is perceived, 
 are refracted by the terrestrial atmosphere, and, consequently, it appears higher 
 than it otherwise would. To obtain the true altitude, therefore, of a celestial 
 body, we must add the parallactic angle to the apparent altitude, and from the 
 sum subtract the refraction. The fixed stars, from their great distances, have 
 no sensible parallax, and hence the preceding remark applies only partially to 
 them. But the difference between the true and apparent altitude of the moon, 
 is, from its proximity to us, about 52. Altitude of the eye, in perspective, is 
 the height of that point in the perspective plane which would be made by a right 
 line drawn from the eye and cutting the plane perpendicularly. 
 
 A I.TO FAGOTTA. or Octave Fagotto. A new musical instrument. It is
 
 ALUM. 
 
 81 
 
 very sonorous, the upper notes approximating ' 
 closely to those of a horn, though much softer; 
 the lower notes blending very harmoniously with 
 those of the voice, piano-forte, &c. The compass 
 of the instrument is three octaves, commencing 
 with the C in the second space bass clef, or four 
 notes lower than the fourth string of the violin, 
 continuing to the C the second ledger line above 
 the treble stave, with their intermediate semi- 
 ;ones. It is played with a reed and mouth-piece 
 similar to a clarionet. The annexed represen- 
 tation, although like the small bassoon, differs 
 materially in its tone and compass. There are 
 three keys and key-holes on the opposite side to 
 that delineated. 
 
 ALUDEL. The recipient of vapourizing sub- 
 stances subjected to the operation of heat. They are 
 generally of earthenware, and of various forms and 
 
 size. Sometimes tubes are employed as aludels, and 
 
 sometimes vessels of large capacity, according to the nature of the substance 
 which is to be condensed in them. The process of condensing the product is much 
 facilitated by keeping the aludel constantly cool by wet cloths or a stream of water. 
 
 ALUMINA. A primitive earth existing in great abundance in clays, earths, 
 ochres, rocks, &c. Soils containing much of this substance are called argil- 
 laceous. It is found in a state of great purity in many precious gems, as the 
 sapphire, topaz, emerald, garnet, beryl, &c. When pure, it is of a white colour, 
 pulverulent, and soft to the touch. It adheres to the tongue, but is tasteless. 
 It is insoluble in water, but is readily dissolved by acids, and also by caustic, 
 potash, or soda. If moistened with water, a very ductile and tenacious paste 
 is formed, which, by heating, becomes exceedingly hard, and is, therefore, ex- 
 tensively employed in the manufacture of porcelain, earthenware, and all kinds 
 of pottery. Bricks, tiles, crucibles, and stone ware, contain large quantities of 
 alumina. It is infusible, per se, in the strongest heat of a furnace, but small 
 quantities may be fused by the oxy-hydrogen blow-pipe. If mixed, however, 
 with certain proportions of lime and silica, it fuses readily. Pure alumina may 
 be obtained easily from the triple salt, containing ammonia instead of potash, 
 by heating it intensely. The acid and the alkali are dissipated by the heat, and 
 the pure earth remains. It is usually procured by adding a small quantity of solu- 
 tion of bicarbonate of potash to a solution of common alum, which precipitates 
 the iron contained generally in that salt. The filtered liquid is then to be added 
 to the liquid ammonia, which combines with part of the sulphuric acid of the 
 alum, and precipitates the earth in a spongy mass. This must be washed fre- 
 quently in distilled water, and then heated to dryness. According to the expe- 
 riments of Sir H. Davy, it appears, that, like the other earths, alumina 
 is a metallic oxide. By passing potassium in vapour over alumina heated to 
 whiteness, a great part of the vapourized metal was converted into the alkali 
 potash : a decisive proof that alumina contains oxygen. By treating the 
 chloride of aluminum with potassium, a grey powder is obtained, which, by 
 burnishing, acquires metallic lustre. This powder burns with much splendour 
 if heated to redness, and is converted to alumina by absorption of oxygen. The 
 metallic base is called aluminum ; and it is found that 100 parts combine with 
 8 of oxygen. Alumina has the unusual property of contracting by heat, and 
 
 On this property the 
 pyrometer fo 
 
 temperatures. See PYROMETER. This useful earth has a powerful affinity for 
 colouring matter, and also for greasy substances. Fuller's earth and pipe-clay 
 owe their useful properties to the large quantities of alumina they contain. 
 
 ALUM, a triple salt of great importance in the arts, is composed of sulphuric 
 acid, alumina, and potash. It is sometimes found native, but only in small 
 Quantities, and is artificially manufactured, chiefly from the mineral called alum- 
 
 :'n pretty exact proportion with the intensity applied. 
 
 ingenious Mr. Wedgewood constructed his pyrometer for estimating very high
 
 82 
 
 ALUM. 
 
 slate. This is found' in great abundance in the nprth-east district of Yorkshire, 
 more particularly between Whitby and Stockton. In the reign of Queen 
 Elizabeth, Sir Thomas Chaloner established a manufactory of alum at Gis- 
 borough, in Yorkshire, and engaged several expert workmen, acquainted with 
 the mode of manufacture, from the dominions of his Holiness the Pope, who 
 fulminated bulls and anathemas against him and them in vain. The alum- 
 slate is also found in abundance at Beckel, in Normandy. There are other 
 aluminous minerals from which alum may be obtained ; but none appear so well 
 adapted, nor so plentiful, as the alum-slate, or aluminous schist. The mineral 
 from which alum is manufactured, is broken into small pieces, and placed on a 
 bed of fuel, until it is about 4 feet high. The fuel is then ignited, and as the 
 calcination proceeds, more of the mineral is added from time to time, until an 
 enormous pile, sometimes equal in area to 200 square feet at the base, is formed 
 The combustion proceeds so rapidly, that it is necessary to prevent access of air, 
 by plastering the crevices with small schist (alum-slate,) made into a lute with 
 water. It requires about 1 30 tons of the mineral to produce one ton of alum. 
 When the calcination is effected, the residue is digested in pits containing large 
 quantities of water. The liquid is withdrawn by pumps, and added to fresh 
 calcined ore. This is repeated until its spec. grav. becomes about 1.15. 
 This saturated liquor is sometimes placed in pits, to deposit sulphate of lime, and 
 other earthy matter, which may contaminate it, and sometimes boiled to pro- 
 duce the same effect. The purified liquid is then concentrated at a boiling heat, 
 in large sloping leaden pans. This is then removed to a settling cistern, and a 
 solution of muriate of potash, or the impure alkali of the soap-maker, is added 
 to it. The quantity necessary is ascertained by experiment with a small portion 
 in a basin. The alkaline solution reduces the spec. grav. from 1.4 or 1.5 
 to 1.35. The quantity of alkali required is, therefore, easily ascertained by an 
 hydrometer. If the spec. grav. of the liquid be more than 1.35, it does 
 not yield crystals, but a solid magma resembling grease, and it becomes 
 necessary to reduce it and re-crystallize. Urine is sometimes added for this 
 purpose ; it is crystallized in the usual manner by slow evaporation. These 
 crystals are purified by washing and boiling in a leaden vessel. The saturated 
 solution is then poured into casks, and in about a fortnight the casks are 
 unhooped and taken to pieces, the alum remaining in a solid mass. This last 
 process is called roching. It is calculated that 22 tons of muriate of potash, 
 or 31 tons of the black ashes of the soap boiler, or 73 of kelp, are necessaiy 
 to make 100 tons of alum. Ammonia may be employed instead of potash, but 
 it is more expensive. The impure sulphate of soda formed in the manufactu r e 
 of aqua fortis, may be economically employed in the manufacture of alum, as 
 it contains two out of the three ingredients necessary to its formation. The 
 celebrated Chaptal manufactured alum artificially in France to a great extent. 
 A chamber of very large dimensions was constructed of masonry, and floored 
 with brick ; the bricks being cemented with a composition of pitch, wax, and 
 turpentine. The roof was of timber, but the planks were closely grooved into 
 each other, no nails being employed. Lastly, the whole of the interior was 
 covered with a thick coating of the above-mentioned cement, applied as hot as 
 possible. The purest and whitest clay is then, after calcination, strewn on the 
 floor, and sulphur burned in the chamber. By this process sulphuric acid is 
 formed, which in a few days saturates the alumina of the clay, converting is 
 into sulphate of alumina. This is known by the efflorescence that takes place. 
 The salt is then removed and exposed to the air, that the acid may penetrate 
 more effectually the alumina. It is then lixiviated, treated with potash, and 
 crystallized as before described. One of the most ancient manufactories of 
 alum was at Roche, in Lyria, whence is derived the term Roche-alum. 
 According to the analysis of Berzelius alum consists of 
 
 Sulphuric acid 34.33 
 
 Alumina 10.86 
 
 Potash 9.81 
 
 Water 45.00 
 
 100.00
 
 AMADOU <M 
 
 Or, Sulphate of alumina 36.85 
 
 Sulphate of Potash 18.15 
 
 Water 45.00 
 
 100.00 
 
 The taste of alum is rather sweet, but astringent. It is a super-sulphate, and 
 reddens the vegetable blues. The spec. grav. is about 1.71. It is soluble 
 in 16 parts of water at 60, and in fths of its weight of boiling water. By long 
 exposure to air, the surface effloresces, but the interior will remain a long time 
 unchanged. A moderate degree of heat expels its water of crystallization, but 
 an intense heat decomposes it, by separating a great part of its acid. The alum 
 of commerce generally contains much impure matter, particularly if kelp or 
 urine has been used in the manufacture. The sulphate of iron is, perhaps, the 
 most injurious foreign ingredient in its composition ; this may be detected by 
 ferro-prussiate of potash. Alum is of great use and importance in many pro- 
 cesses of the arts. It is very extensively employed in dyeing, as a mordant. 
 Most of the vegetable colours employed in dyeing have no affinity for the 
 material intended to be dyed. In most of these cases alum is employed as the 
 intermediate medium by which the colouring matter may be fixed, as it has an 
 affinity both for the material and the colouring matter. An acetate of alumina 
 is frequently employed by the dyer, instead of the ordinary sulphate. The 
 acetate does not act so corrosively on delicate articles as the common alum, 
 and its affinity for some colours is greater. It is easily prepared by the double 
 decomposition of a solution of the sulphate of alumina and potash, and a solu- 
 tion of the acetate of lead. When these two solutions are mixed together, the 
 sulphuric acid of the alum combines with the lead, forming an insoluble preci- 
 pitate, which is sulphate of lead, while the liberated acetic acid unites with the 
 alumina and potash, forming the required acetate, which is separated by filtration 
 from the solid substance. If paper, linen, or wood, be soaked in a solution of 
 alum, it is rendered nearly incombustible, and less liable to be affected by mois- 
 ture. Paper thus prepared is advantageously employed in wrapping gunpowder 
 and is also useful in whitening silver. Alum has the property of hardening 
 tallow, for which purpose it has been sometimes advantageously employed. It 
 is used with much success in the preparation of skins for tanning, giving them 
 firmness after they have become flaccid by immersion in the lime pits. Turbid 
 water is rendered limpid and transparent by the addition of a small quantity of 
 alum in solution ; its purity, however, is by no means promoted by the process. 
 It is usefully combined with the salt by which cod fish are cured, as it prevents 
 a deliquescence which would otherwise take place. It is used in the manu- 
 facture of London bread rather extensively, as it enables the baker to employ 
 flour of inferior quality ; the alum promotes a white colour and closeness of 
 texture in the bread, qualities much admired, although they generally indicate 
 impurity. It improves the colour of the beautiful pigment, Prussian blue, and 
 is extensively employed in the preparation of that article. In medicine it is 
 administered as an astringent and tonic, and also as a collyrium. Alum, deprived 
 by heat of its water of crystallization, which, in medicine, is called alumen ustum 
 (burnt alum), has been greatly extolled as a remedy in cases of colic, and some 
 other disorders. A remarkable substance, called Homberg's pyrophorus, is 
 prepared from alum. Equal parts of alum and brown sugar are melted over a 
 clear fire, and stirred constancy until they become dry. When cold the mixture 
 is finely powdered, and placed in a phial coated with clay, having an open 
 glass tube luted into its neck. This is to be intensely heated in a crucible con- 
 taining sand, when gas will issue from the tube, which may be inflamed. When 
 this ceases to come over, the crucible is removed, and the tube stopped by 
 moistened clay until the bottle is sufficiently cold to be corked. The substance 
 thus formed is a black and light powder, which takes fire when poured from the 
 bottle into the air. If poured into oxygen gas a more vivid combustion takes 
 place. 
 
 AMADOU. This substance is, perhaps, better known by the familiar appel
 
 94 AMBERGRIS. 
 
 lation of German tinder, and is chiefly employed in procuring a light speedily, 
 as it ignites immediately with a feeble spark from the flint and steel, or by con- 
 densation of atmospheric air, and burns with slow and smouldering heat for a 
 considerable time. It is formed of a spongy excrescence, or mushroom, found 
 on old treeS, particularly the oak, ash, and fir. This is washed and boiled in 
 fair water, and afterwards beaten by a mallet until it resembles very spongy 
 leather ; it is then soaked in a saturated solution of saltpetre, and dried in an 
 oven. A good substitute for this may be formed of coarse brown paper, soaked 
 in the solution of saltpetre, and dried in an oven. 
 
 AMALGAM. A combination of mercury with any other metal. 
 
 AMBER. A hard, solid, semi-transparent substance, found in several 
 mines of Prussia, in a bed of argillaceous mineral. It is also found in Poland, 
 France, Italy ; on the shores of the Baltic and Mediterranean, in the neighbour- 
 hood of London, and in various other parts. It is generally considered to be 
 of vegetable origin, and to be composed of bituminous vegetable matter in a 
 state of congelation. The extraordinary property which amber possesses of 
 attracting, when excited by friction, light bodies, such as feathers, bits of 
 paper, pith, dust, &c., was known to Thales, the celebrated philosopher of 
 Miletus, who flourished 600 years before the birth of Christ. The Greek term 
 for amber is election ; and from this word is derived the title of our modern 
 science, electricity, the effect of excited amber in attracting light substances, 
 being attributed to its elective powers. This mineral is found of various 
 colours, but the most abundant is of a deep yellow or orange. When broken, 
 the fracture is smooth and glossy, and it is susceptible of a beautiful polish. If 
 gently rubbed, it emits a peculiar and agreeable odour. At a temperature of 
 550 Fahr. it melts, and its transparency is destroyed. It is insoluble in water ; 
 but alcohol, if highly rectified, extracts a small quantity of its colouring matter. 
 Sulphuric acid will dissolve it, and it may be then precipitated by water. Pure 
 caustic alkalies also dissolve it, and some of the essential oils. Various speci- 
 mens of amber have been found containing portions of animal, vegetable, or 
 mineral matter, imbedded in the mass. This fact seems to prove that it has 
 once been in the fluid state. From the appearance of insect remains in amber, 
 it would seem that they have attempted to escape from a viscid or congealing 
 mass. In some, the legs, or wings, only, have been found, which seems to prove 
 that the animal has been entangled in the viscid mass, and has left the fragile 
 parts of the body in attempting to wade through it. Drops of water, leaves of 
 plants, native gold, silver, and various other substances, have been found imbedded 
 in amber. Dr. Girtanner promulgated a very ingenious opinion on the formation 
 of amber, which appears plausible. He imagined that a species of ant called 
 formica rufa, formed this substance by the deposition of their peculiar wax, or 
 honey. These ants are found in immense numbers in the pine forests, where 
 amber is obtained in the mineral state. The wax, although soft, hardens by 
 immersion in salt water, and then bears a great resemblance to amber. Dr. 
 Brewster, however, considers, from the optical properties of amber, that it is 
 established beyond doubt, to be an indurated vegetable juice. By careful dis- 
 tillation, an empyreumatic oil, equal to one-third in weight of the amber, is 
 obtained. This oil is brown and thick if a strong heat is applied, and requires 
 re-distillation ; but if the heat do not exceed 212, and water be employed, it is 
 limpid and colourless. It is used in medicine as an antispasmodic. The spec. 
 grav. of amber varies from 1.065 to 1.100. For its use in varnish-making, see 
 VARNISH. 
 
 AMBERGRIS, or AMBERGREASE. A solid, opake, fatty substance, found 
 on the sea-coast, or sometimes floating on the sea, chiefly in the tropical 
 regions. It is of various colours, but generally of a deep ash-coloured yellow. 
 It is most frequently obtained in small fragments, but large masses, weighing 
 from 100 to 180 Ibs. have been found. It has frequently been discovered in 
 the intestines of the spermaceti whale, and is supposed to be the cause, or the 
 result of disease in the animal. Healthy fish, which void their excrements 
 when they are hooked, seldom contain amber ; but diseased fish, unable to per- 
 form this function when caught, generally yield it; and it is almost always found
 
 AMMONIA 85 
 
 in the faeces of the whale when dead and floating on tli& waters. There can 
 be little doubt that this substance informed in the intestines of the animal, not 
 swallowed by it as some have supposed ; for no large piece has yet been found 
 iu the whale, which does not contain the beaks of the Sepia octopodia, the com- 
 mon food of the spermaceti whale. When first obtained, ambergris has the 
 foetid smell peculiar to the faeces of the animal ; but after a short exposure to 
 the air and washing, its odour is fragrant, and is increased by heating. It is 
 not a little extraordinary that Mr. Homberg obtained, by long digestion of 
 human excrement, a substance which possessed, in a very intense degree, the 
 perfect smell of ambergris. The spec. grav. of ambergris varies from 0.780 
 to 0.926. It melts at 144 Fahr. and at 212 Fahr. is volatilized in the form 
 of a white vapour. If thrown on hot coals, it burns and is entirely dissipated. 
 It is not soluble either in water or the acids. Ether, ammonia, and oil, 
 dissolve it, but alcohol acts only on a portion, and is therefore useful in analyzing 
 it. Caustic alkalies combine with it and form a soap. According to La Grange, 
 it is composed of adipocere resin, benzoic acid, and coal. By later analysis it 
 lias been found that some specimens do not contain benzoic acid. The alcoholic 
 solution is used in cosmetics, &c., to communicate its peculiar odour. 
 
 AMETHYST. A natural gem, of a violet colour and great brilliancy, as 
 hard as the ruby or sapphire, from which some say it only differs in colour. The 
 Asiatic are of a deep purple hue, and are deemed the most valuable. The 
 German are violet. Some amethysts are, however, made colourless by art, 
 when they are often mistaken for diamonds; the superior hardness of the 
 latter will, however, enable any person to detect the imitation. 
 
 AMMONIA. A powerful alkali, sometimes called the volatile. In its pure 
 state it is a gas transparent and colourless, and possessing all the mechanical 
 properties of ordinary atmospheric air. Its smell is pungent and suffocating, 
 and its taste extremely caustic. It extinguishes combustion, and immediately 
 destroys animal life. One hundred cubic inches weigh 18.16 grs. Its spec, 
 grav. is 0.5954. If the gas is passed through an ignited porcelain tube, con- 
 taining iron, it is decomposed, and its volume doubled ; it is then found to con- 
 sist of 1J volume of hydrogen, and J volume nitrogen, which are condensed 
 into the bulk of one volume as ammoniacal gas. It is rapidly absorbed by cold 
 water, which, when impregnated with gas, is called liquid ammonia, or spirits 
 of hartshorn. At a temperature of 50, water absorbs about 670 times its 
 volume of the gas, and its spec. grav. is reduced to 0.875. This liquid, by 
 heating, parts with the ammoniacal gas, hence it is called the volatile alkali. 
 The manufacture of liquid ammonia is a very important one. As this alkali is 
 very extensively employed in medicine, chemistry, and the arts, we shall, 
 therefore, briefly describe the process. Into a retort connected with a series of 
 Woolfe's bottles, put two parts of slaked lime, mixed with one part of muriate 
 of ammonia (sal ammoniac). The Woolfe's bottles must be filled with pure 
 water, and if they are surrounded by cold water, frequently renewed ; if by ice, 
 a more highly saturated liquid will be obtained. The muriate of ammonia is 
 decomposed by the lime, and the ammonia passes into the water in the bottles 
 in the state of gas, where it is immediately absorbed. The addition of hot 
 water, and application of moderate heat, ensure complete decomposition of the 
 salt. The liquid ammonia may be obtained by a more direct process, but not 
 so economically. The following mode is recommended by Mr. R. Phillips, as 
 being superior to that recommended in the London Pharmacopoeia. Pour half 
 a pint of water on 9 oz. of well burnt lime, and when it has remained in a close 
 vessel an hour, add 12 oz. of sal ammoniac, and 3| pints of boiling water. 
 Filter the solution when cool, and distil from it 20 fluid oz. This will have a 
 spec. grav. of 0.954, which is as strong as it can be conveniently kept. The 
 spec. grav. of liquid ammonia is a sure test of its strength. That above-men- 
 tioned will contain about 11 per cent, of ammonia. If the spec. grav. be .850, 
 the liquid will contain about 35 per cent. ; intermediate densities indicate 
 intermediate proportions of ammonia. The muriate of ammonia, cr sal ammo- 
 niac, from which the above-described liquid is obtained, was formerly brought 
 from Egypt almost exclusively. In the neighbourhood of the temple of Jupitet
 
 86 ANCHORS 
 
 Ammon, were many inns for the accommodation of 'pilgrims and their camels. 
 From the sublimed dung of these animals the salt was obtained, and its name 
 was derived from the locality of its manufacture. In modern times, ammonia 
 has been procured by the dry distillation of bones, horns, and other animal 
 matters ; arid, more recently, from the waste liquor of the gas works, which con- 
 tains large quantities of impure ammoniacal salts. The muriate of ammonia 
 is employed in chemical analysis, in dyeing, and in tinning or soldering. It is 
 the most delicate test for the presence of platinum, and is generally used by the 
 chemist to precipitate that metal from its combinations in solution. There are 
 many other valuable salts of ammonia, the most important of which are the 
 nitrate and carbonate. The nitrate, when heated to 400 Fahr. is decomposed, 
 and yields the nitrous oxide, or laughing gas, in abundance. It is also used in 
 the preparation of frigorific mixtures : if mixed with an equal weight of water, 
 the thermometer sinks above 30 Fahr. The carbonate is a useful chemical 
 agent, and is used in medicine as a stimulant. This substance is the common 
 smelling-salts of the shops. All the salts of ammonia are decomposed at a red 
 heat. Chlorine decomposes liquid ammonia, or the gas, with great energy. 
 If a bottle containing chlorine gas be brought in contact with the surface of 
 liquid ammonia, the hydrogen of the latter substance combines with the chlo- 
 rine, forming muriatic acid, which unites with another portion of ammonia, and 
 nitrogen is left in the bottle. If this experiment be formed in a dark room, a 
 flash of light will be seen at the moment of combination. If the mouth of a 
 bottle containing chlorine gas be brought in contact with the mouth of another 
 containing ammoniacal gas they combine with explosive violence, a flash and 
 report accompany the action, and the bottles are sometimes broken. 
 
 AMMONIAC GUM is a concrete gummy-resinous juice. This gum has a 
 nauseous sweetish taste, succeeded by a sensation of bitter, somewhat resembling 
 galbanum, but more grateful. It is usually brought from the East Indies, in 
 large masses composed of lumps, or tears ; it acquires a yellowish appearance 
 on exposure to the air. When chewed, it softens in the mouth, and becomes 01 
 a white colour. It may be partially dissolved in water, or in vinegar, with 
 which it assumes the appearance of milk ; but the resinous part, amounting to 
 about one-half, subsides when suffered to rest. In medicine, it is prescribed for 
 removing obstructions of the abdominal viscera ; in hysterical complaints, and 
 in long and obstinate colics, proceeding from viscid matter lodged in the intes- 
 tines. Externally, it is used for the purpose of discussing indolent tumours ; 
 and, with a mixture of squill vinegar, forms a plaster sometimes successfully 
 applied in the case of white swellings. 
 
 ANACARDIUM. The cashew-nut tree ; a genus of plants of the class 
 Enneandria, and order Monogynia. At one extremity of the fruit of this tree 
 there is a flattish kidney-shaped nut, between which and the shell is a small 
 quantity of liquor, which is useful for marking linen, being very black and 
 durable. 
 
 ANACLASTIC GLASSES. A kind of sonorous glasses, chiefly made in 
 Germany. They have the property of being flexible, and emitting a vehe- 
 ment noise by the human breath. The anaclastic glasses are a low kind of 
 phials, with flat bellies, resembling inverted funnels, whose bottoms are very 
 thin, scarcely surpassing the thickness of an onion-peel ; this bottom is not 
 quite flat, but a little convex. On applying the mouth. to the orifice, and 
 gently inspiring, or, as it were, sucking out the air, the bottom gives way with 
 a tremendous crash, and the convex becomes concave. On the contrary, upon 
 expiring or breathing gently into the orifice of the same glass, the bottom, 
 with no less noise, bends back to its former place, and becomes gibbous as 
 before. 
 
 ANACLASTICS. That part of Optics which considers the refraction of 
 light, and is commonly called Dioptrics. 
 
 ANCHOR. A heavy curved instrument, used for retaining ships in a required 
 position. The forms of anchors, and the materials of which they are made, are 
 various. In many parts of the East Indies the lower part of the anchor is 
 formed of a cross of a very strong and heavy kind of wood, the extremities of
 
 ANCHORS. 
 
 87 
 
 which are made pointed. About the middle of each arm of the cross is inserted a 
 long bar of the same wood, the upper ends of which converge to a point, and are 
 secured either by ropes or an iron hoop, and the space between the bars is filled 
 up with stones to make the anchors sink more deeply and readily. In Spain, 
 and in the South Seas, anchors are sometimes formed of copper, but generally 
 in Europe they are made of forged iron. Anchors may be divided into two 
 classes mooring anchors, and ships' anchors. Mooring anchors are those 
 which are laid down for a permanency in docks and harbours, and are consi- 
 derably heavier than ships' anchors, from which they differ in form, having 
 sometimes but one arm, and sometimes, instead of arms, having at the extremity 
 a heavy circular mass of iron and no stock; these latter are called mushroom 
 anchors. The general form of ships' 
 anchors is shewn in the annexed 
 figure, a is a long bar of iron, 
 called the shank, from the lower 
 extremity of which branch two 
 curved arms b b in opposite direc- 
 tions, and forming an angle of 60 
 each with the shank. Upon each 
 arm, towards the end, is laid a 
 thick triangular piece of iron c c, 
 termed the fluke. In the upper 
 end of the shank is an eye, through 
 which passes a ring d, to which the 
 cable is attached. The stock e is 
 composed of two strong beams of 
 wood, embracing the shank imme- 
 diately below the ring, and secured 
 together by iron hoops and tree- 
 nails; the stock stands at right 
 angles to the plane of the arms, 
 and serves to guide the anchor in 
 its descent, so as to cause one of 
 the flukes to enter the ground. 
 Ships are generally provided with 
 three large anchors, named the 
 best bower, the small, and the 
 sheet anchor; a smaller anchor, 
 termed the stream anchor ; and 
 
 another, still smaller, named the kedge, which latter has generally an iron stocK 
 passing through an eye in the shank, secured thereto by a key, or forelock, 
 which admits of its being readily displaced : its principal use is in changing the 
 position of a ship in harbour, and in an operation termed kedging. From the 
 great mass of iron in large anchors (some weighing from 3 to 4 tons), the per- 
 fect forging of them becomes a matter of much difficulty ; as from the great 
 heat necessary to weld such masses, the iron is liable to become "burnt," as it 
 is termed. Workmen also cannot always observe what is going on in the forge, 
 where the iron is exposed to ignition from the blasts of the bellows, or to the 
 presence of sulphur in quantity among the coals. When the welding of a large 
 mass, like the shank of an anchor, is to be completed by the sledge hammer, 
 the workmen are subjected to a scorching heat radiating therefrom, which 
 renders it impossible to make a very close inspection, and the consequence fre- 
 quently is, the beating up of cinders within the body of the iron. To this cause, and 
 to burning, may be often attributed the breaking of anchors, followed too fre- 
 quently by a distressing loss of lives and property. Many attempts have been 
 made of late years to construct anchors not liable to these defects, by dividing 
 the mass into separate parts, and by a more judicious arrangement. The 
 following is the invention of Mr. Hawkes, a surveyor of shipping, in the 
 Commercial- road, London. 
 
 Mr. Hawkes observes, " The anchors at present in use are marie by forming
 
 ANCHORS. 
 
 the shank and flukes separately ; and by the rapid action of heavy hammers, they 
 are united or welded into each other, and the cable is fastened to a ring passed 
 through the shank sideways. The stocks, if of wood, are let or scored over 
 each side, and bolted and hooped over the shank of the anchor ; if of iron, the 
 eye or ho'le for it is formed by punching a hole through the shank of the anchor ; 
 the palms are made separately, and welded on to the flukes. The improvement 
 consists in making one fluke and half the shank in one length, and to bend them 
 to the form required, and then hooping the two halves together. This method of 
 making the anchor in separate parts, admits of the forming of a groove up the 
 middle of the shank, for a chain to pass through, and of an eye of great 
 strength for the reception of a wooden stock, which is also made in two pieces, 
 and passed into the shank in reverse directions ; these having iron shoulders 
 abutting against the eye, are kept immovably in that position by being braced 
 together with an iron hoop at each end. The construction is shown in the annexed 
 engraving, a the cable ring ; 
 b the eye which holds the 
 stock, made out of the whole 
 substance of the shank, by 
 bending each of the halves 
 into a semicircle, in opposite 
 directions. The anchor is 
 shewn to be divided into two 
 equal parts, by a line which 
 passes down the middle of 
 the shank, as at o o ; c the 
 wooden stock, made also in 
 two equal parts (as before 
 described), and firmly se- 
 cured in their places by the 
 hoops and shoulders; dddd 
 are four strong hoops which 
 bind the shank together; the 
 upper one is made square, 
 and the others circular; a 
 portion of the shank is sup- 
 posed to be removed, to ex- 
 hibit the situation of the 
 chain which passes up the 
 centre, and is connected at 
 the upper end to the cable 
 ring, and at the lower end 
 to the buoy ring. /, in the 
 small separate figure, gives 
 a transverse section of the 
 shank of the anchor, show- 
 ing it to be of an oval form, 
 the longest diameter of which is in a line with the flukes ; this figure conferring 
 upon it great strength to withstand the powerful strains to which an anchor is 
 frequently exposed in that direction, h h are the palms, bolted to the respective 
 flukes, each ot which is connected in one piece with a brace t , passing in oppo- 
 site directions round the shank of the anchor, thereby strengthening the flukes 
 in a great degree, and giving a collateral support to each hah" of the anchor 
 k is a strong plate of iron bolted on to the crown ; I the buoy ring." 
 
 An anchor, .differing materially in form and construction from the ordinary, 
 was invented by Mr. R. F. Hawkins, and is represented in the subjoined en- 
 gravings. The shank of the anchor a is forked at the lower part or crown, 
 into two parts or loops b and c, in each of which is formed a hole or eye; 
 between the loops is a block of iron d, termed a crown piece, having a circular 
 ture to receive the arms, and a square aperture at right angles to the former, 
 into which is screwed a stout bar of iron e, termed a toggle, projecting equally
 
 ANCHORS. 
 
 89 
 
 on each side of the crown piece ; on the end of the crown piece, opposite to 
 that in which is inserted the toggle, is a ring / for the huoy rope. The arms 
 g h are formed in one piece, and before the palms t i are attached, one end of 
 the arms must be passed through the eyes in the loops of the shanks, and through 
 the ey-e of the crown piece ; the palms are then to be put on, and must both 
 
 Fig. 1. 
 
 lie in tne same plane ; after which the arms are to be curved in the same plane 
 with the palms. The crown piece is firmly keyed to the arms, and the toggle 
 must be of such a length and form as to make it bear firmly against the fore 
 part of the fork in the shank, so as to prevent the crown piece and arms from 
 turning round upon it, and to retain them at an angle of 50 with the shank. 
 When the anchor is let go, one end of the toggle will come in contact with the 
 ground, which puts the flukes in a position to enter ; and when the strain is 
 upon the cable, that end of the toggle which is upwards comes in contact with 
 the throat of the shank, and sets the anchor in the holding position, as shown 
 in perspective at Fig. 3. The advantage of this mode of constructing anchors 
 is, that both arms take the ground, and therefore the weight of metal may be 
 diminished, and yet an equal, if not a greater, effect be obtained ; also as there 
 is no stock, and no projecting upper fluke, there is little risk of fouling, as it is 
 termed ; that is, of the cable entwining round the arms. The only objection 
 which occurs to us, is the probability that, when at single anchor, it might not 
 so readily turn in the ground at the turn of the tide, as the ordinary anchor, 
 and therefore might be likely to trip ; but for moorings we have no doubt that 
 it would be found very effective. 
 
 An anchor upon a similar principle, but of a somewhat different con- 
 struction, was invented by Mr. Soames, a front and side elevation of which 
 is exhibited in the subjoined cuts. In this anchor there is but one fluke a, 
 which is T shaped, and works on a pivot in a triangular frame, composed of 
 the two sides b and c, forged in one piece, and a stay d, which serves as 
 a stock; //are loops, or eyes, for the reception of the chains that unite
 
 90 
 
 ANCHORS, 
 
 the ring g, to which the cable is to be fastened. For general purposes, 
 
 this anchor is, perhaps, preferable to the former, it being free from the objection we 
 
 made to that one, as it admits 
 
 of detaching the arm, which 
 
 renders it more convenient 
 
 to stow away ; also, as the 
 
 shank is formed in two parts, 
 
 instead of one of equal area, 
 
 they are more easily forged, 
 
 soundly, and, consequently, 
 
 less liable to breakage. 
 
 The anchor invented by 
 Lieut W. Rogers, R.N. is de- 
 serving of notice in this place. 
 Its main peculiarity consists 
 in its having a hollow shank, 
 formed out of six bars of iron, 
 of such a thickness as to in- 
 sure the forging of them per- 
 fectly sound for anchors of 
 the largest dimensions. The 
 construction we shall describe 
 with reference to the subjoined 
 figures. Fig. I represents 
 a side view of the anchor, 
 and Fig. 2 a plan of the stock. The two principal pieces a a are bent GO 
 \s to form a part of the arms or flukes ; the other four are formed into a 
 Hollow tube b b (as shown in section at Fig. 3) for a centre-piece, and the whole 
 
 Fig.4. 
 
 are firmly welded together at both ends of the shank. The intermediate parts 
 are secured by strong hoops i i, so that every piece must bear its proportion of the 
 entire strain. The patentee states, that so great is the strength thus obtained for 
 the shank, that both arms have been broken off by the testing machine, without 
 altering the shank in the least degree. On the llth of June, 1829, an experi- 
 ment was made at the Gateshead iron-works, in the presence of several respect- 
 able ship-owners, when the patent anchor, weighing 9 cwt. 19 qrs. 4 Ibs. broke 
 in succession the following anchors on the old construction, without receiving 
 the least injury ; viz. one of 10 cwt. 3 qrs. 4 Ibs. for hempen cables ; one of
 
 ANCHORS. 
 
 91 
 
 10 cwt. 2 qrs. 12 Ibs. and one of 12 cwt. 4 Ibs. for chain cables. In place of 
 the usual ring, there is a bolt and shackle c, Figs. 1 and 4, when the anchor 
 is to be used with chain cables ; but when hempen cables are to be used, a ring 
 d is connected to the shackle c by an additional shackle and bolt e. The anchor- 
 stock/may be formed either of a single piece, or of two pieces hooped together, 
 and is secured in its place as follows: The bolt and shackle c being withdrawn, 
 the small end of the shank is passed through the eye of the stock /, (which is 
 defended by an iron plate g on each side) ; the collar h is then put over, and 
 the stock is keyed up against the hoop i by the forelock key k passing through 
 a hole in the shank ; by this means the anchor may be stocked or unstocked 
 without the assistance of a carpenter, which is a great recommendation, as 
 a considerable length of time is required to stock an anchor in the common 
 way. These anchors have been pretty extensively adopted, and several parties 
 who have made trial of them have given satisfactory certificates of their effi- 
 ciency. In connexion with improvements on anchors, it may not be altogether 
 out of place to mention some improvements in the method of letting them go. 
 
 Two improved methods of letting go anchors are described in the Transactions 
 of the Society of Arts. The principle is the same in each, and consists in sup- 
 porting the end of what is termed the standing part of the cat-head stopper and 
 shank-painter, by bolts turning upon pivots, and retained in a proper position 
 by a catch, which being withdrawn, the bolt turns upon its pivot, and the stopper 
 slips off, by which means all risk of jamming the turns of the stopper (as in the 
 common method of letting go the running end) is avoided; the danger to the men 
 on the forecastle is done away, and the anchor can be let go at a moment's warning. 
 
 The arrangements in each of these inventions being the same, whether 
 applied to cat-head stoppers or shank-painters, we shall therefore show one in- 
 vention as applied to cat-head stoppers, and the other to shank-painters. The 
 subjoined cuts show Capt. Burton's method of letting go a cat-head stopper a 
 
 is the cat-head ; b c a bolt, turning upon a pivot d ; the end c forms an oblique 
 plane, and is held down by the clamp e turning upon a pivot/, the clamp being 
 secured by a hasp g and pin h. i is the standing end of the stopper, having an 
 eye formed in it, which passes over the end b of the bolt be; the other end of 
 the stopper passes through the ring of the anchor, and over the thumb-cleat k, 
 and is made fast round the timber-head I. When it is required to let go the 
 anchor, a hand-spike is inserted between the thumb-cleat k, so as to nip the 
 clamp e, and the hasp g is cast off; then upon withdrawing the hand-spike, the 
 bolt being no longer held by the clamp e, turns upon its pivot d, by the weight 
 of the anchor on the stopper, and the eye of the stopper slips off the end of the bolt. 
 The following cut represents Mr. Spence's invention for letting go a shank 
 Tenter. Fig. 1 is an elevation, and Fig. 2 the plan, a is a cast-iron carriage,
 
 ANEMOMETER. 
 
 bolted through the ship's side 
 
 and supporting the hook b Fig, 
 
 by a pin or pivot at c; d e 
 
 alever turning upon a centre 
 
 /, the end d being formed 
 
 into a hook, which clasps the 
 
 upper end of the bolt b, the 
 
 lever being retained in the 
 
 position shewn in the plan, 
 
 by a pin g ; h is part of a Fig. 2. 
 
 chain forming the standing 
 
 part of the shank-painter, 
 
 and supported by the bolt b. 
 
 To the other end of the chain is spliced the running part of the shank-painter. 
 
 which passes round the shank of the anchor, and is made fast to a timber-head. 
 
 When it is required to let go the shank-painter, an iron bar is inserted into the 
 
 end c of the lever de, which is made hollow for the purpose, and the pin g being 
 
 withdrawn, the lever is turned round its centre until the bolt is released from 
 
 the hook d, when it falls, and the chain end of the shank-painter slips off. 
 
 ANCHUSA. Yellow anchusa, or blue-flowered bugloss. The juice of its 
 corolla or flower, gives out, on the addition of acids, a beautiful green. An 
 infusion of these flowers is given in inflammatory bilious diseases. 
 
 ANIL. The plant from which indigo is prepared. See INDIGO. 
 
 ANIME is a resinous substance, commercially, but improperly, called gum 
 anime ; for, like resins, it is totally soluble in alcohol, and also in oil, while 
 water will not take up more than a sixteenth part by weight. There are two 
 kinds, distinguished by the terms oriental and occidental. The former is dry, 
 and of colours varying from green to red and brown. The latter is of a yel- 
 lowish white, transparent, and somewhat unctuous, tears, and partly in large 
 masses, brittle, of a light pleasant taste, easily melting in the fire, and burning 
 with an agreeable smell. The 
 spirit of the alcoholic solution, 
 when drawn off by distillation, 
 preserves the taste and flavour 
 of the anime ; the distilled water 
 exhibits on its surface a portion 
 of essential oil. This resin is 
 much used in perfumery. It 
 has also been imagined to be of 
 important service in plasters, em- 
 ployed to relieve nervous affec- 
 tions of the head and other parts. 
 
 ANEMOMETER. An in- 
 strument for measuring the 
 strength or velocity of the wind. 
 Among various machines which 
 have been constructed for this 
 purpose, the following one has 
 been found to answer very well. 
 It consists of an open frame a b c, 
 supported by a shaft d, upon 
 which it turns by the action of 
 the wind upon the vane e. ff 
 are sails, fixed to one end of the 
 axis g, and disposed to be influ- 
 enced by the wind in the usual 
 manner. Upon this axis is also 
 fixed a conical barrel of wood hk, 
 on the smaller end of which k 
 s attached a line I, with a weight
 
 ANEMOMETER. 93 
 
 appended to it. The wind acting upon the sails, causes the barrel to revolve, 
 and the line to be wound up on its superfices. To prevent any retrograde motion, 
 a ratchet wheel o is fixed to the base or larger end of the cone, having a clicker 
 falling into the notches as it revolves. It is evident that the power of the weight 
 will continually increase as the line advances towards the base of the cone, as 
 the weight acts at a greater distance from the axis or fulcrum ; consequently, 
 the variable force of the wind may be readily ascertained by fixing the line at 
 the smallest end, and marking the barrel with spiral lines, as taken up by the 
 coiling of the rope round its superficies, placing also between the lines numerals 
 to denote the force of the wind, which may be calculated with tolerable pre- 
 cision upon the principles of the lever. The diameter of the cone should be 
 such in comparison with its smallest end, that the force of the strongest wind 
 should have scarcely sufficient force to bring the line on to the base of the 
 cone. 
 
 Although the instrument above described gives an accurate idea of the com- 
 parative force of the wind at different times, it does not point out the actual 
 force exerted on a given surface, nor can observations made with one instrument 
 in a particular place, be compared with observations made by another instru- 
 ment elsewhere. It is also cumbersome, and not portable. In the Philosophical 
 Transactions for 1775, Dr. Lind gives a description of a very ingenious portable 
 wind gauge, which indicates the actual force of the wind by the column of watei 
 which it will support. This instrument consists 
 of two glass tubes abed, which should not be 
 less than 8 or 9 inches long, the bore of each 
 being about ^ of an inch diameter, and connected 
 together by a small bent glass tube e of about only 
 |- of an inch bore, to check the undulations of the 
 water caused by. a sudden gust of wind. On the 
 upper end of the tube a b is fitted a thin metal 
 tube / which is bent at right angles, and has its 
 mouth open to receive the wind blowing into it 
 horizontally. The two branches of the tube are 
 at liberty to turn round a steel spindle g, which 
 passes through two slips of brass h i near the top 
 and bottom of the instrument. The spindle is 
 fixed into a block of wood by a screw in its bot- 
 tom. When the instrument is used, a quantity 
 of water is poured in until the tubes are about 
 half full, and the instrument being then held 
 perpendicularly, with its mouth exposed to the 
 wind, the water will be depressed in the tube a b, 
 and proportionably elevated in the tube c d ; and 
 the distance between the surfaces in the two tubes 
 measured by a sliding scale of inches, and parts 
 k attached to the instrument, will be the height 
 of a column of water which the wind is capable 
 of sustaining at that time ; and as a~cubic foot of 
 water weighs 1000 oz. or 62 J Ibs. nearly, the 
 twelfth part of which is 5Jj Ibs., therefore every 
 inch the surface of the water is raised, the force 
 of the wind will be equal to so many times 5,- Ibs. 
 on the square foot. This instrument shows the 
 force, but not the velocity, of the wind; but as 
 the force is as the square of the velocity, if the 
 
 velocity due to a given force be ascertained, a table of the velocities corresponding 
 to each inch the water is elevated, may be calculated and engraved upon 
 the scale of equal parts. The following table, showing the corresponding 
 height of water, velocity of the wind, and the force exerted upon a square 
 foot of surface, has been calculated from some experiments made by Dr. 
 Hutton.
 
 94 ANTI-ATTRITION. 
 
 Height of Water. 
 Inches* 
 
 Force of Wind. 
 Ibs. 
 
 Telocity per Koos. 
 
 1 
 
 . . . . 1.3 ... 
 
 18 
 
 j 
 
 . . . . 2.6 ... 
 
 25.6 
 
 i ... . 
 
 . . . . 5.2 ... 
 
 36 
 
 2 
 
 . . . . 10.4 . . . 
 
 50 
 
 3 
 
 . . . . 15.6 . . . 
 
 62 
 
 4 
 
 , . . . 20.8 . . . 
 
 76 
 
 5 
 
 . ... 26. . . . 
 
 80.4 
 
 r> 
 
 , . . . 31.25 . . . 
 
 88 
 
 7 
 
 , . . . 36 5 . . . 
 
 95.2 
 
 8 
 
 . . . 41.7 . . . 
 
 101.6 
 
 9 
 
 ... 46.9 . . . 
 
 108 
 
 10 
 
 . . . 52.1 . . . 
 
 113.6 
 
 11 
 
 . . . 57.3 . . . 
 
 119.2 
 
 12 
 
 . . . 62.5 . . . 
 
 124 
 
 ANISEED. A medicinal seed produced from a species of pimpinella which 
 grows naturally in Egypt, Syria, and other eastern countries. In France it is 
 cultivated for culinary and medicinal uses. Aniseeds are roundish and striated, 
 flatted on one side, and pointed at one end ; of a pale colour, inclining to green. 
 They have an aromatic smell, and a pleasant warm taste. Their virtue is 
 entirely given out to alcohol, when it forms, combined with syrup, the well- 
 known cordial of this name. 
 
 ANNEALING. The process by which metallic, and other mineral produc- 
 tions, are converted from a brittle to a comparatively tough quality, presumed 
 to be caused by a new arrangement of their constituent particles. In a con- 
 siderable number of bodies that will bear ignition, it is found that sudden cooling 
 renders them hard and brittle, while, on the contrary, if they are allowed to 
 cool very gradually, they become softened or annealed. We have, however, 
 noticed several alloys of copper (brass in particular) in which sudden cooling 
 has the reverse effect, that of annealing it. The process of annealing requires 
 some address and experience to perform it in the best manner; and varies in 
 the degree of heat applied, as well as in the period of cooling, according to the 
 nature of the metal or other substance operated upon. In the annealing of 
 steel and iron, the metal is heated to a low redness, and suffered to be gradually 
 reduced in its temperature, covered up, on a hearth. Ovens are constructed 
 for this purpose, wherein the pieces of metal, according to their massiveness, 
 and the quality it is desired they should possess, are placed and retained at a 
 low heat for days, and sometimes weeks together. The annealing of glass ia 
 performed precisely in the same manner. 
 
 ANNOTTA. The pellicles of the seeds of a lilaceous shrub. The annotta com- 
 monly met with among us, is moderately hard, of a brown colour en the out- 
 side, and a dull red within. It is used for giving an orange cast to the simple 
 yellows ; as an ingredient in varnishes ; and besides its use in dyeing, is em- 
 ployed for colouring cheese. 
 
 ANTHRACITE. A species of coal called by a variety of names, of which 
 the most common are, stone coal, blind coal, glance coal, Kilkenny coal. There 
 are several varieties, and they possess generally the property of burning without 
 flame or smoke. See COAL, 'FURNACE, and STOVE. 
 
 ANTI-ATTRITION. A patent for a composition under this name was 
 taken out in this country some years back : it was introduced as a substitute for 
 oil or grease, in lubricating the axle-trees of carriages, and is, of course, equally 
 applicable to the rubbing parts of other machinery. Its composition is simply 
 a mixture of hog's lard with "black lead" (plumbago), in the proportion of four 
 parts of the former to one of the latter. It appears from a Munich journal,' 
 that the manufacture of this article in Germany is conducted with more exact- 
 ness ; ten and a half parts are there melted over a moderate fire, when two 
 parts of finely powdered and sifted plumbago are to be added by degrees, and 
 be well stirred with a wooden spatula, until the incorporation of the two sub-
 
 ANVIL. .95 
 
 stances is unifoira and complete ; the mixture is then to be taken from the fire, 
 and the stirring continued until it is quite cold, to prevent the subsidence of the 
 plumbago. When this composition was applied by means of a brush in the 
 cold state to pivots and toothed wheels, the expense was, in consequence, found 
 to be reduced from six florins twenty-nine kreutzers, to one florin thirty 
 kreutzers. 
 
 ANTIMONY. A brilliant white metal of a laminated or striated texture. 
 It is very brittle, and cannot be rolled into sheets, or drawn into wire. The 
 spec. grav. of the metal, is 6.712 ; it melts at 810, and crystallizes in pyramids 
 when cooling. At an intense heat it is volatilized. The ores of antimony are 
 chiefly found in the north of Europe. There are several varieties, but the sul- 
 phuric or grey antimony is the most abundant, and yields the metal of com- 
 merce. It is reduced to powder, and heated in a reverberatory furnace ; the 
 melted sulphuret then flows from the infusible stony or earthy matter, and is 
 then smelted and purified. The metal is used in the manufacture of printers' 
 types, music plates, specula for telescopes, and is a component of several useful 
 alloys. See ALLOT. A difference of opinion exists among chemists respecting 
 the number of oxides of antimony, some being of opinion that there are only 
 two ; others, among whom is Berzelius, that there are four. We shall only 
 deserve here the two which appear indisputable. To obtain the protoxide, 
 dissolve the metal in muriatic acid, and pour it into a large quantity of distilled 
 water; this separates the protoxide as a white precipitate, which must be washed 
 with a weak solution of carbonate of potash, to remove any muriatic acid it may 
 contain. This is the basis of all the useful antimonial medicines. The per- 
 oxide may be obtained by digesting antimony in nitric acid, and drying the 
 white powder which results at a moderate heat. Antimony is soluble in most 
 of the acids, and combines also with chlorine, iodine, phosphorus, and sulphur. 
 If filings of the metal are thrown in f o a vessel containing chlorine gas, they 
 burn vividly. Basil Valentine first introduced this substance into medicine, and 
 is said to have performed many extraordinary cures by it. Its virtues he dis- 
 covered accidentally. Having thrown a preparation of it into a hog-trough, 
 the hogs were violently purged bv it, but afterwards fattened with surprising 
 rapidity. Seeing this effect, it is said he administered it to his brother monks 
 in such quantities that they all died : the medicine was therefore .called 
 anti-moine, or anti-monk. By more cautious and skilful use, he obtained for it 
 a great reputation ; but in 1566 its employment in medicine was prohibited in 
 Park by an edict of the parliament. The sulphuret of antimony was employed 
 in very early times by the eastern females, and even occasionally by men, for 
 the purpose of staining the eye-brow and lashes, and even the lids, to make the 
 eye appear larger. This practice is frequently alluded to in the Scriptures. 
 Tliere are many valuable medical preparations of, antimony, the most important 
 of which, perhaps, is the medicine called Dr. James's Powder. This is a compound 
 of protoxide of antimony, and phosphate of lime. The precise mode of pre- 
 paring it is not known to chemists ; the pulvis antimonialis of the shops is, in 
 composition, similar to James's powder, but its effects as a medicine are not so 
 certain nor so powerful. Tartar emetic, or tartarized antimony, is a triple salt, 
 composed of tartaric acid, potash, and antimony. Powder of algaroth is the pro- 
 toxide of antimony precipitated from the muriate by water. Kerme's mineraf is a 
 nydro-sulphuret of the metal. Antimony is much valued as a medicine for 
 cattle. 
 
 ANVIL. A large solid mass of iron, of indispensable use in smiths', as 
 well as many other workshops, for hammering or forging work upon. They 
 are made of various sizes, from the weight of a few pounds (or even ounces,) up 
 to many hundred weights each ; and they are much varied in form, to adapt 
 them to the nature of the work they are designed for. Their general figure is 
 that of a parallelopipedon, with its lowest side spread out at the corners to 
 steady its seat upon a wooden block upon which they are mounted, and confined 
 by large nails or staples. The face, or upper side, of most anvils are perfectly 
 flat and smooth, and are made of steel, and so hard as to resist the file. At 
 one end of the anvil is a "beak-iron," which is a projecting piece, tapering tp
 
 96 APOLLONICON. 
 
 a point, for the purpose of turning or bending the metal under operation ; and 
 there are also one or more holes made on the face, for the convenience of 
 punching holes in the work, or for the reception of fixed cold chisels, stakes, or 
 indeed any kind of tool that it may be desirable to adapt to it. 
 
 APIARIES. A place where bees are kept ; the term is considered to apply 
 to a collection of hives, and not to a single one. See BEEHIVE. 
 
 APOLLONICON. A musical machine, on the principle of the organ, 
 which, by peculiar modification of the pipes, produces an excellent imitation 
 of the tones of all the most admired wind instruments ; the combined effect of 
 the whole being similar to that of a numerous and well-chosen orchestra. This 
 magnificent contrivance, unrivalled in this or any other country, is the invention 
 of Messrs. Flight and Robson, who spent five years in its completion ; and as 
 a popular description of it has not yet appeared, and cannot fail to be acceptable 
 to the amateurs both of musical and mechanical science, we propose to give 
 such an account of the instrument as may serve to convey a general idea of its 
 construction. In the apollonicon, as in the organ, the sound is produced by a 
 current of air, urged by bellows, through several series of vertical pipes. In 
 the apollonicon there are two pair of bellows, placed below the floor of the 
 apartment in which the instrument stands ; the wind from which passes through 
 a reservoir and a tube, called a wind trunk, into an air-tight compartment, 
 called a wind chest. The pipes which, by various modifications of their con- 
 struction, produce the sounds of the different instruments, are ranged in rows 
 one behind the other, parallel to the front of the machine, in the order of the 
 gamut, each note and half note having its separate pipe, and each parallel row 
 representing a different instrument ; the pipes producing the same note in 
 every instrument lying in a straight line from front to back of the instrument, 
 or parallel to its sides. Thus the pipes producing the note A on the flute, 
 clarionet, bassoon, &c., all lie in a line parallel to the sides of the instrument. 
 From the upper part of the wind chest proceeds a horizontal platform, termed 
 the bottom board, having a series of channels cut in its upper surface, cor- 
 responding to each note of the different scales, and extending longitudinally 
 from front to rear of the machine. Above the bottom board, and at right 
 angles to the channels, are a series of grooves, corresponding to the transverse 
 ranges of pipes, or the number of the different instruments in each groove, are 
 three slides, placed one over the other, and through all three are cut narrow 
 passages, opening into each of the wind channels in the bottom board. 
 Over the slides is placed the top board, into which the pipes are inserted, 
 communicating with the wind channels through the apertures in the slides. 
 The use of these slides is to cut off occasionally the communication of any 
 particular instrument with the wind chest, so as to cause that instrument to 
 cease playing, which is effected as follows : the space between each aperture 
 in the slides is somewhat greater than the width of the wind channels, so as to 
 cover the channels completely, and thereby cutting off the communication with 
 the instrument to which the slide belongs. Only one slide in each set of slides 
 is in operation at one time ; the apertures in the other two sets being over the 
 wind channels, and below the apertures of the instruments. One set of slides being 
 used when the instrument is played by the mechanical action of the machine, 
 another set is moved by pedals, and the third set by hand, when it is played by 
 the keys. At that end of each wind groove that opens into the wind chest, are 
 two hanging valves, called pallets, which admit the air into, or exclude it from, 
 the wind grooves ; and the art of performing upon the machine consists in the 
 management of the pallets and stops before described ; the air or tune being 
 produced by the pallets, and the stops regulating the instruments, upon which 
 the air is played. We shall now proceed to describe the means by which this is 
 effected. The machine may be played in two ways, either by performers 
 seated at ranges of keys, as in other organs, or by mechanical means : and as 
 *his latter method is the distinguishing character of the machine, and has called 
 forth so much ingenuity in its execution, we shall describe it first. The prin- 
 ciple is as follows : to one set of the pallets is attached a series of wires (one to 
 each pallet) passing through holes in a brass plate in the bottom of the wind chest,
 
 APOLLONiCON. 97 
 
 which are just sufficiently large to allow tlie wires to move easily, without 
 allowing the air to escape from the wind chest. These wires (GO in num- 
 ber, being one to each note of the scale of the machine,) are connected to 
 on? end of a series of small steel levers, set in a frame below the wind 
 chest, the outer end of the levers resting upon the surface of a cylinder 
 somewhat longer than the key-frame ; a number of small pins and bent 
 wires or brackets project a short distance beyond the circumference of the 
 cylinder, ranged in lines across the axis, and by the revolution of the cylinder, 
 one or more of these pins or brackets are brought in contact with the outer 
 end of the keys, which are thus raised, whilst the other end of the keys, and 
 the pallets corresponding, are proportionably depressed ; the wind passes from 
 the wind chest into the wind passages. The length of time the pallets continue 
 open is regulated by the length of the brackets ; and when, by the revolution 
 of the cylinder, the brackets come clear of the keys, the outer end of the key 
 falls upon the cylinder, the pallet is closed by a spiral spring, and the com- 
 munication with the wind grooves is cut off. Beyond the keys, and towards 
 the end of the key-frame, is a set of similar keys, moved by brackets on the 
 surface of the cylinder, similar to the former, only projecting somewhat more; 
 these keys (called shifting keys,) by an ingenious arrangement (which we shall 
 afterwards describe at length), give motion to an equal number of levers, each 
 one of which moves in or out one or more of the set of stops which are 
 governed by the cylinder, and thus opens or cuts off the communication of the 
 corresponding instrument or set of pipes. For the sake of simplicity, we describe the 
 brackets as ranged in h'nes standing right across the axis, which is not quite correct, 
 as, in this case, the same keys would be moved at the corresponding part of each 
 revolution of the cylinder, and consequently only very short pieces could be 
 performed, or the cylinder must be of an inconveniently large diameter. To 
 remedy this, the cylinder is allowed to move endways in its bearings, a space 
 equal to the distance between two keys ; on its axis is cut a screw, containing 
 nine threads, and the bevelled edge of a lever, called a knife, taking in one of 
 the threads of the screw, the cylinder would be moved endways, at each revo- 
 lution, a space equal to the distance between two threads ; or one-ninth of the 
 distance between two keys, at each revolution ; and the ends of each key would 
 trace a spiral line on the barrel, likewise deviating from a straight line one-ninth 
 of the distance between two keys ; thus nine revolutions of the cylinder would 
 be made before the spiral traced by one key could be brought under the next 
 key. Now the brackets and pins being ranged on the cylinder along these 
 spiral lines, it is clear a different key may be moved at each corresponding part 
 of a revolution, for nine revolutions, which renders the barrel equal to one of 
 nine times its diameter, in which the brackets should be placed in right lines 
 surrounding the cylinder ; and as the cylinder revolves very slowly, it is suffi- 
 cient for the performance of most compositions. If it is required to repeat the per- 
 formance, the key-frame is turned back upon a hinge, which raises the keys clear 
 of the pins, and the knife being lifted out of the screw cut on the axis, the cylinder is 
 moved endways into its original position, the knife replaced in the screw, and the 
 key-frame again brought down to the cylinder, when the piece may be repeated. 
 Having thus explained the principles of the mechanical action of the machine, we 
 shall proceed to notice some of the details of the arrangement. There are three 
 cylinders, each 2 feet in diameter, and each having a separate wind chest and 
 key frame placed over it, furnishing wind to particular portions of the scale. 
 The main cylinder occupies the centre of the front of the machine ; it is 8 feet 
 long, and comprises a range of five octaves : viz. from G G an octave below first G 
 in the bass clef up to G, and eighth above G in the treble clef. In a line with 
 this, and concentric with it, is another cylinder, 3 ft. 9 in. for the bass notes 
 extending from G G G, or an octave below the former, up to gamut G, being 
 two octaves. The third cylinder lies at the back of the machine, parallel to 
 the main cylinder ; it is 8 feet long, and comprises two octaves. Below the two 
 front cylinders extends a shaft, or axis, having two pinions, which work in two 
 wheels, one on the end of each cylinder, and a similar shaft lies below the third 
 cylinder, in the rear of the machine ; and beneath these shafts, and at right
 
 98 APOLLONICON. 
 
 angles to them, is another shaft, extending from the front to the back of the 
 machine, having on it two endless screws working in worm-wheels on the 
 two shafts ; this last shaft receives its motion by a band from the driving-shaft, 
 (which has a fly-wheel, and is turned by manual labour), and causes the cylinders 
 to revolve. The key-frame is made in distinct pieces, to allow for the unequal 
 
 Fig. L 
 
 contraction of the wood, and any inequalities which may exist in the cvlinder : 
 
 and to take the weight off the key, it is supported on the cylinder by anti-friction 
 
 rollers, it remains now to explain the connexion of the finger-keys with the 
 
 lets. The toy-boards are five in number, the central largest comnrisuig a
 
 AFOLLON1CON. 99 
 
 Kale of five octaves, and the smaller ones disposed two on each side of the 
 larger, these containing a scale of three octaves. These keyboards stand in 
 front of the instrument, and detached from it, so that the performers sit with 
 their backs to the instrument, and their faces to the audience. From the 
 
 Fig. 2.
 
 100 
 
 APOLLONICON. 
 
 fore end of the finger keys descend wires to the fore end of a series of levers 
 below the floor, and to the other end of these levers are attached wires, which 
 pass through holes in the wind chest, and are fastened to their set of pallets, 
 and thus tfie depression of the finger keys draws down the hinder ends of 
 the lower levers, and opens the pallets. Within reach of the performers at 
 the keys, are a number of levers for moving by hand the draw-stops as are 
 termed the slides which throw off or on any particular instrument; hut, in 
 addition to thesp, are a set of pedals five in number, which move a set of stops, 
 called compound pedal stops. These are the invention of Mr. Robson, and 
 are for the purpose of enabling the performer suddenly to throw on or off 
 a number of instruments by a single movement, and thereby add greatly to the 
 brilliancy of effect. The operation of these stops requiring a figure for its elu- 
 cidation, will be deferred until afterwards. To enable the reader more fully to com- 
 prehend the foregoing description, we have subjoined two engravings, Fig. 1 being 
 a section of the machine parallel to the barrels, or to the front ; and Fig. 2 a 
 section across the barrels, or at right angles to the former. In these figures, 
 we have not strictly adhered to the actual arrangement of the parts which are 
 used in the instrument itself, but have rather endeavoured to give a general 
 idea of the principle of the construction, which is all that our limits will allow. 
 In each figure the same letters denote similar parts, a a are the reservoirs 
 immediately over the bellows ; b the wind trunk ; c the wind chest ; d d 
 strengthening bridges ; e e pallets ; ffff wind grooves or channels ; g g g the 
 stops or slides ; h h the groove board, into which are inserted the foot of the 
 pipes jjj.; k the driving shaft, turned by a band I, from a wheel below the 
 floor ; m m endless screws working into worm wheels n n on the transverse 
 shafts o o; pp pinions driving the cylinders q; r the knife or guide; s the key- 
 frame ; 1 1 anti-friction rollers ; u u the keys ; v v stops to prevent the keys 
 striking the cylinder ; w w shifting keys with the connexion to their stops ; x 
 connexion of the pallets with the finger keys ; y connexion of draw stops ; z 
 connexion of compound pedal stops. Having thus explained the genera! 
 mechanical arrangement of the instrument, we shall proceed to explain mor:,> 
 minutely the manner of throwing on or off; the different instruments or ranges 
 of pipes, both by the shifting keys, and by the compound pedal stops. The 
 Fie. 3. 
 
 anove cuts represent one of the shifting keys, %. 3 being a front view, and 
 *iy. 4 a side view, a represents a portion of the cylinder; b one of the shifting
 
 APOLLONICON. 
 
 101 
 
 keys, kept in contact with the barrel by the spring c. On the spindle d is keyed 
 a T-shaped lever e, in the horizontal arms of which are two projecting studs//, 
 with a wire passed through them from one to the other. A piece of brass g is. 
 attached at its lower end to the key b, and the upper end passing between the 
 lever ; the wire rests by one of its shoulders on one of the projecting studs ; a 
 steel spring blade h is inserted at its lower end into a cleft in the piece g, and 
 passes through a slit in a stud in the lower end of the lever e, and by its ten- 
 dency to recover a right line in the direction of the arm, it forces the piece g 
 out of the perpendicular, so that it shall always rest against one or other of the 
 studs, k is an arm upon the spindle d, connected by a bar I to the lever (not 
 shown) which works the slide or stop. Now when the tooth of the key is raised 
 by one of the studs of the barrel passing under it, the other end of the key is 
 depressed, and drawing down the piece g, shifts the lever e into the position 
 shown by the dotted lines, and thus reverses the position of the slide. When 
 the stud has passed the key, the spring c returns the key to its former position, 
 and the piece g in rising is thrown by the spring h against the stud in the upper 
 arm of the lever e. The compound pedal stops are a most admirable invention 
 of Mr. Robson's, by means of which the performer is enabled to throw off in- 
 stantaneously a number of instruments, and to bring into play a number of 
 others, as the varying nature of the music may require, with an effect and pre- 
 cision equal to that of the best appointed orchestra. The mechanism is extremely 
 ingenious, as well as beautifully simple. The arrangement will be easily under- 
 stood by referring to the annexed cuts, which represent one set of pedal levers, 
 
 Fig. 5. 
 
 Fig. 6. 
 
 Fiy 5 being a side view, and Fig. 6 an end view. On the upper axis a is a 
 number of arms b b acting upon slits in a corresponding number of slides c c; 
 on the lower axis d is likewise one or more arms e acting on one or more slides 
 f ; on the axis d is a tooth g acting upon a similar tooth h on the axis a; the 
 length of each tooth being proportional to the length of the arms b and d. k 
 is an arm, connected by wires and bell-cranks to the pedal beneath the key- 
 boards Now \ipon depressing this arm, it will be seen that the arms b b and d d 
 will move over equal spaces in opposite directions; one set of slides will there- 
 fore open the communication between the wind grooves and the instruments to 
 which they belong, and the other set will close the passages to which they belong, 
 and thus throw out of play the corresponding instruments; and there being five 
 of these compound pedal stops, an amazing variety of changes may be obtained 
 by varying the combinations of the slides. The whole number of the keys acted 
 upon by the cylinders is about 250. There are upwards of 1900 pipes, 45 draw- 
 stops, and 2 kettle-drums. To the musical amateur the following list of the 
 stops will doubtless prove interesting. 
 On the first cylinder, 
 
 1. Open Diapason. 4. Principal. 7. Flute. 
 
 2. Ditto ditto. 5. Twelfth. 8. Sesqui Altera. 
 
 3. Stop ditto. 6. Fifteenth. 9. Cornet Trumpet. 
 On the second cylinder are two octaves of wooden pipes, of large dimensions. 
 
 termed double diapason pedal pipes : the largest is 24 inches long, and 23
 
 , oa AQUEDUCT. 
 
 square ; this is 8 feet longer than the corresponding pipe in the great organ at 
 Haarlem. The range of the scale is from G G G to G. 
 On the third cylinder are the following stops, 
 
 Diapason, or Corni Stop. Trumpet. Hauthoys. 
 
 Stop Diapason. Cremonas. Piccolais. 
 
 Violoncello. Flutes. Trumpets. 
 
 German Flute. Vox hum ana. Diapason. 
 
 Wood Fifteenth. Octave Flute. Principal, &c. 
 
 The mechanism is enclosed in a case, 20 feet broad by 18 feet deep, and 
 24 feet high. The front is divided into three compartments by pilasters of 
 Grecian Doric, surmounted by others of the Ionic order. Between the upper 
 pilasters are three paintings ; that in the centre representing Apollo, and those 
 on the sides the Muses, Clio and Erato, somewhat larger than life, which do 
 much credit to the artist (Mr. John Wright) by whom they were painted. The 
 mechanical action of the apollonicon was first exhibited to the public in June, 
 1817, when the overtures to Anacreon and to the Clemenza di Tito were 
 performed by the cylinders in a style that called forth the most marked appro- 
 bation from large and scientific audiences. From that period to the present 
 time it has maintained its well-deserved popularity, and continues an object of 
 interest alike to the musician and the mechanist, offering to the former some of 
 the grandest combinations of harmony, and to the latter some of the most 
 curious and complicated specimens of his art. 
 
 AQUA EORTIS. The old and still popular name for nitric acid. The 
 article sold in the shops under this name is generally prepared by mixing 
 common nitre with an equal weight of sulphate of iron, and half its weight of 
 the same sulphate calcined, and distilling the mixture ; or by mixing nitre with 
 twice its weight of dry powdered clay, and distilling in a reverberatory furnace. 
 Two kinds are found in the shops, one called double aqua fortis, which is about 
 hah the strength of nitric acid ; the other simply aqua, fortis, which is half the 
 strength of the double. See ACID, NITRIC. 
 
 AQUA REGIS. This having been the first solvent that was discovered for 
 gold, the king of metals, was called by this name, signifying the king's water. 
 The original and proper aqua regis is made by adding four ounces of common 
 salt to an avoirdupois pound of aqua fortis. Homberg says, aqua regis is of 
 proper strength to dissolve gold, when a bottle, holding sixteen ounces of water, 
 holds seventeen ounces of the acid ; that is to say, when it is of the specific 
 gravity 1.062. 
 
 AQUA TINTA. See ENGRAVING. 
 
 AQUA VIT.3L Ardent spirit of the first distillation has been distinguished 
 in commerce by this name. The distillers of malt and molasses spirits call it 
 low wines. 
 
 AQUEDUCT. A conduit for water, constructed of different materials, built 
 on uneven ground, for preserving the level of water, and conveying it from one 
 place to another. Aqueducts art- distinguished into two classes ; the visible, or 
 such as are built on arches across valleys and marshes, and the subter- 
 raneous, which are formed by piercing mountains, and conveying the water 
 below the surface of the earth. These constructions were formed of brick, 
 stone, &c., and covered either with vaulted roofs, or flat stones, which served 
 to shelter the water from the influence of the sun and rain. They were, in some 
 cases, paved, and, in others, the water was conveyed through a natural channel 
 formed in the clay. It was also frequently conducted by leaden pipes into 
 reservoirs of the same metal, or into troughs of hewn stone. Some aqueducts 
 are supported on single, others on double, or triple, ranges of arches. Of the 
 .atter kind is the Pont du Gard in Languedoc, supposed to have been built by 
 the Romans, to convey water to the city of Nismes ; that at Constantinople, 
 and that which, according to Procopius, was constructed by Cosroes, king of 
 Persia, near Petra, in Mingrelia, and which had three conduits in the same 
 direction, each elevated above the other. The Romans had many magni- 
 ficent aqueducts, surprising on account of their magnitude and number, as 
 well as their construction and length ; some bringing water through a distance
 
 AQUEDUCT. 103 
 
 of from thirty to one hundred miles, either upon a series of arches, or hy means 
 of excavations through mountains and rocks. This is well expressed by Piiny 
 in the following language : " If we consider the incredible quantity of water 
 brought to Rome for the uses of the public, for fountains, bathg, fishponds, 
 private houses, gapdens, and country seats ; if we represent to ourselves the 
 arches constructed at a great expense, and carried on through a long distance; 
 mountains levelled, rocks cut through, and valleys filled up ; it must be acknow- 
 ledged that there is nothing in the whole world more wonderful." The waters 
 of the Tiber, with the wells and fountains in the neighbourhood, had supplied 
 the wants of the Romans for four centuries and a half, when Appius Claudius, 
 the censor, advised and constructed the first aqueduct. His example was 
 speedily followed, and the courses of rivers were thus changed and diverted 
 towards Rome, to supply the daily increasing wants and luxuries of the Roman 
 people. At certain distances, vents were provided, in order that the water, 
 which was accidentally obstructed in its progress, might be discharged till its 
 ordinary passage was cleared ; and, in the canal of the aqueduct itself, there 
 were cavities into which the water was precipitated, and where it might remain 
 till its mud was deposited, and the water become clear. A considerable variety 
 was observable in the construction of aqueducts. The aqueduct of the Aqua 
 Marcia had an arch of sixteen feet diameter. The whole was composed of 
 three different kinds of stone ; one of them reddish, another brown, and a third 
 of an earth colour. The entire edifice is 70 Roman feet in height. Above 
 them appeared two canals, the highest of which was fed by the waters of the 
 Tiverone, and the lower, by what was called the Claudian River. Near this 
 aqueduct, Montfaucon gives the plan of another with three canals ; the highest 
 supplied by the Aqua Julia, that in the middle from Tepula, and the lowest 
 from the Aqua Martia. The arch of the aqueduct of the Aqua Claudia was of 
 hewn stone, very beautiful ; that of the aqueduct of the Aqua Meronia was of 
 brick. Each of these was 72 feet high. The Aqua Appia deserves notice for 
 the singularity of its construction, it not being plain or gradual in its descent, 
 but much narrower at the lower than at the upper end. The consul Frontinus, 
 who superintended the aqueducts under the emperor Nerva, mentions nine, each 
 of which had 13,594 pipes of an inch diameter; and it is stated by Vigerus, 
 that, in the space of twenty-four hours, Rome received, by means of these erec- 
 tions, 500,000 hogsheads of water. In modern times, the aqueduct of Legovia 
 is considered the most magnificent. There still remain 159 arcades, wholly 
 consisting of stones, enormously large, and joined without mortar. These 
 arcades, with what remain of the edifice, are 102 feet high ; there are two 
 ranges of arcades, one above the other. In 1684, Louis XIV. caused an aque- 
 duct to be commenced near Maintenon, for carrying water from the river Kure 
 to Versailles ; but the work was abandoned in 1 688. This would, probably, 
 have been the largest aqueduct in the world, the whole length being 60,000 
 toises ; the bridge 2,070 fathoms in length, 220 feet in height, and consisting 
 of 632 arches. The principal ancient aqueducts now in being, are those of the 
 Aqua Virginia, Aqua Felice, and Aqua Paulina. The quantity of water sup- 
 plied by the whole of the aqueducts in ancient Rome, is calculated to have 
 amounted to the enormous quantity of 50,000,000 cubic feet daily ; which, 
 reckoning the population of Rome at 1,000,000, allows 50 cubic feet for the 
 daily consumption of each individual. The supply of water to London in 1790, 
 amounted to 2,626,560 cubic feet daily ; and even at the present day, it does 
 not exceed 4,000,000 feet. This quantity, although found abundantly sufficient for 
 our use, is little more than a twelfth part of the quantity consumed by the Romans. 
 The daily supply of water to Paris is still less, being about 293,000 feet, or half a 
 cubic foot for the daily use of each inhabitant. The Greeks of the lower empire 
 simplified the general mode of conducting water, and reduced the expense to a 
 fifth part, chiefly by the introduction of the Soulerazi, or water-balance, a sort 
 of hydraulic obelisk. The water runs down a gentle slope in covered drains, 
 till it reaches an obelisk constructed of masonrv, and rising up one side in a 
 narrow channel, discharges itself into a bason at the top, from which again, at 
 a level 8 inches lower, it descends by a similar channel on the other side.
 
 ,04 ARCHIL. 
 
 he charge of the water- works at Constantinople is entrusted to a body of 300 
 Turks, and certain Albanese Greeks, who make it almost an hereditary pro- 
 fession. The supply for each person is stated to be about two-thirds of a cubic 
 foot, or 42 pounds daily. There are two ancient cisterns still extant in Con- 
 stantinople : the subterranean cistern, built of hand-brick, vaulted, and resting 
 on marble columns; and the cistern of 101 columns, anciently called Philoxene. 
 The latter consists of three rows of columns, one above another, and is capable 
 of holding five days' supply of water for the whole inhabitants of this spacious 
 city. Among the most modern must be noticed the aqueduct of Chirk, in Den- 
 bighshire, constructed by Mr. Telford for the purpose of carrying on the navi- 
 gation of the Ellesmere canal. It consists of 10 arches, supported by 
 pyramidal stone piers, and extends to about 600 feet in length. The summit 
 of the central arch is 65 feet above the level of the water. 
 
 ARABIC GUM. lliis gum, which flows naturally from the acacia, in 
 Egypt, Arabia, and elsewhere, forms a clear transparent mucilage with water : 
 it is insoluble in alcohol and ether. It is used in medicine, and is considered as 
 a specific against the strangury occasioned by blisters; it constitutes, under 
 particular forms, a nutritious food, and it is an important article in various 
 manufactures. 
 
 ARCH, or ARC. In geometry, a part of a curve line, as of a circle or an 
 ellipse, &c. Arch, in architecture, an aperture, the upper portion of which is 
 bounded by curve lines, as we see in porches, bridges, &c. ; they are of various 
 forms, and are designated by various names, according to their figure, as 
 circular, elliptical, cycloidal, &c. Arch of equilibrium, in the theory of bridges, 
 is that arch which is in equilibrio in all its parts, and therefore equally strong 
 throughout, having no tendency to break in one part more than another. The 
 arch of equilibration is not of any determinate curve, but varies according to 
 the figure of the extrados; every different extrados requiring a particular 
 intrados, so that the thickness in every part may be proportional to the 
 pressure. The subject has occupied the attention of several eminent mathe- 
 maticians, and has been fully treated by Dr. Hutton, in his " Principles of 
 Bridges," and in some of his tracts; where the proper intrados is investigated for 
 every particular form of extrados ; and it shews, that in semicircular and semi- 
 elliptical arches, and, in fact, in all arches springing perpendicularly from a 
 horizontal line, the line of their extrados becomes assymptotical as it approaches 
 a perpendicular passing through the points from which they spring, and that 
 such arches require to be loaded infinitely over the haunches. But the 
 researches of mathematicians upon this subject, although they are not without 
 utility, have not been of any great service to the practical builder, who, guided 
 by a set of maxims which are the fruits of observation and experience, constructs 
 arches of immense span, differing widely from the form assigned by theory, 
 which are, nevertheless, stable and durable. This arises, perhaps, not from the 
 
 difficult to estimate their several quantities. Hence in practice it is found 
 sufficient if the arch of equilibrium be comprised within the boundaries of the 
 youssoir, or stones, forming the arch, without its being necessary for either the 
 intrados or extrados to conform exactly to that curve. For good practical 
 views on this subject, we refer our readers to Gtvilt's Equilibrium of Arches, and 
 to the article " Bridges," in the Edinburgh Encyclopedia. 
 
 ARCHIL. A whitish lichen, growing upon rocks in the Canary and Caps 
 Verd Islands, which yields a rich purple tincture, fugitive, indeed, but extremely 
 beautiful. This weed is imported to us as it is gathered : those who prepare it 
 for the use of the dyer grind it betwixt stones, so as to thoroughly bruise, but 
 not to reduce it into powder, and then moisten it occasionally with urine, or 
 mix quick lime with the urine : in a few days it acquires a purplish red, and at 
 length a blue colour; m the first state it is called archil, in the latter, lacmus, 
 or litmus. The dyers rarely employ this drug by itself, on account of its 
 dearness, and the perishableness of its beauty. The chief use they make of
 
 ARSENIC. 105 
 
 it is for giving a bloom to other colours, as pinks, &c. This is effected by 
 passing the dyed cloth or silk through hot water, slightly impregnated with the 
 archil. The bloom thus communicated, soon decays upon exposure to the air. 
 By the addition of a little solution of tin, this drug gives a durable dye ; 
 its colour is at the same time changed toward a scarlet, and that is the more 
 permanent, in proportion as it recedes the more from its natural colour. Prepared 
 archil very readily gives out its colour to water, to volatile spirits, and to alcohol ; 
 it is the substance principally made use of for colouring the spirits of ther- 
 mometers. As exposure to the air destroys its colour upon cloth, the exclusion 
 of the air produces a like effect in those hermetically sealed tubes, the spirits 
 of large thermometers becoming in a few years colourless. The Abbe" Nollet 
 observes (in the French Memoirs for 1742), that the colourless spirit, upon 
 breaking the tube, soon resumes its colour, and this for a number of times 
 successively ; that a watery tincture of archil, included in the tube of ther- 
 mometers, lost its colour in three days ; and that in an open deep vessel it 
 became colourless at the bottom, while the upper part retained its colour. A 
 solution of archil in water, applied on cold marble, stains it of a beautiful violet 
 or purplish blue, colour, far more durable than the colour which it communicates 
 to other bodies. There is a large establishment at Glasgow for an article of 
 this kind, which is much esteemed ; it is sold by the name of cudbear. Silks 
 thus dyed with it are said to be very permanent, of various shades, from pink 
 and crimson to a bright mazarine blue. 
 
 ARGAL. Crude tartar, in the state in which it is taken from the inside of 
 wine vessels, is known in the shops by this name. 
 
 ARGAND BURNERS. See LAMPS. 
 
 AROMATIC VINEGAR. An acetic solution of camphor, oil of cloves, 
 oil of lavender, and oil of rosemary ; a sufficient quantity of each to make it 
 pleasant. 
 
 ARRACH. A spirituous liquor, imported from the East Indies; it is chiefly 
 manufactured at Batavia and at Goa, upon the Malabar coast. 
 
 ARROWROOT. The pure starch of a bulbous-rooted plant, growing in 
 the West Indies, and other warm climates. The starch of the potatoe has pre- 
 cisely the same properties, and, from the superior cheapness of the latter in 
 this country, it forms a common substitute for the foreign production, which is 
 difficult to obtain in the retail shops unadulterated. Under the article POTATOE 
 will be found a full description of the mechanical process employed in extracting 
 the stavch from that root. 
 
 ARTESIAN WELLS. A name given by the French, and extensively 
 adopted here, to artificial fountains, made by boring the earth, and permitting 
 the confined water to rise. See BORING THE EARTH. 
 
 ARCOGRAPH. An instrument for drawing a circular arc without a central 
 point. There are various ways of performing this, but the following is the most 
 simple, and is often practised by bricklayers and masons. Two nails are driven 
 into the face of the wall upon which the curve is to be struck, the nails being 
 at each extremity of the curve ; two laths or straight rods are then nailed 
 together at such an angle as that the apex shall touch the crown of the arch 
 when the two sides are in contact with the nails at the extremities of it ; then 
 if the apex of the laths be gradually moved round from one nail to the other, 
 the laths being kept continually in contact with the nails, a tracer placed at the 
 apex will describe the required arch. An instrument of this kind, invented by 
 Mr. Rotch, and rewarded by the Society of Arts, will be found very serviceable 
 for drawing upon paper arcs of very large circles, whose centres lie beyond the 
 limits of the drawing board. It consists of two straight rulers, connected by a 
 joint similar to that of a sector, in the centre of which joint is a socket to carry 
 the tracer. The two limbs are connected to two graduated arcs, sliding upon 
 each other, by means of which the limbs may be set to any angle so as to describe 
 an arc containing any required number of degrees. 
 
 ARSENIC. A brittle metal of a bluish white colour, possessing very little 
 lustre. By exposure to the atmosphere it becomes nearly black, and slightly 
 pulverulent. It is very fusible, and is frequently employed to assist the fusion
 
 10 6 ARSENIC. 
 
 of other metals. At 356 Fahr. it is volatilized in white fumes, which constitute 
 the arsenious acid, or white arsenic. It is from this substance that the metal 
 of commerce is obtained, and is imported in large quantities from Saxony, the 
 cobalt works of which supply Europe with arsenic. The ores of cobalt contain, 
 with many other impurities, much arsenic. This is dissipated by torrefying 
 them when reduced to powder in a furnace with a long horizontal flue. 
 The arsenious acid becomes condensed in this, and is removed by condemned 
 criminals, the employment being very dangerous, and even fatal to life, on 
 account of the impossibility of preventing particles of this powerful poison from 
 entering the mouth or nostrils. When first volatilized, it is contaminated with 
 sulphur, &c., from which it is separated by mixing with impure potash, and 
 subliming again in close vessels. It then constitutes the white arsenic of the 
 shops. The metal is obtained from this by incorporating it with carbonaceous 
 matter, and heating in a vessel provided with a receiver, to condense the arsenic 
 which rises in vapour. The ores of arsenic are numerous and abundant, and it 
 is a component of an endless variety of minerals. The process of roasting the 
 ores of copper, iron, &c. is unhealthy, chiefly on account of the quantity of 
 arsenic liberated. The minerals called realgar and orpiment (sulphurets of 
 antimony) possess much beauty. Arsenic combines with oxygen in two pro- 
 portions, the first of which, the arsenious acid consists of arsenic 76 + oxygen 24. 
 The second arsenic, acid of arsenic, 76 -f- oxygen 40. Both these compounds 
 possess the characteristics of acid bodies ; they redden vegetable blues, and 
 combine with many salifiable bases, forming neutral salts. The first of these 
 deserves particular attention, as it is the fatal poison so frequently employed in 
 the destruction of human life by the suicide or the assassin. It is nearly inso- 
 luble in cold water, and is, therefore, generally taken in the state of turbid 
 mixture. It adheres with singular obstinacy to the coats of the stomach and 
 intestines, and produces speedy corrosion and inflammation. The symptoms of 
 the poison are generally manifested within a quarter of an hour after it lias been 
 swallowed : these are sickness, pain at the stomach, thirst, burning heat in the 
 mouth and fauces, faintings, cold sweats, debility and at last cramp, and contrac- 
 tions of the limbs. Most, and frequently all, of these symptoms are displayed by the 
 sufferer before death. The only medicines likely to be effectual, are sulphuretted 
 hydrogen water, and copious draughts of bland mucilaginous liquids. Carbonate of 
 magnesia and opium have been on more than one occasion found highly beneficial. 
 In cases of suspected poisoning by this mineral, the contents of the stomach, 
 or the ejected matter, should be carefully saved and digested in distilled water. 
 This must be filtered through porous paper, and, if highly coloured with beer, 
 coffee, or other description of food, a small quantity of newly prepared pure 
 animal charcoal, in powder, must be mixed with it until the colouring matter is 
 destroyed. A second filtration produces a limpid and transparent fluid, suscep- 
 tible to the action of tests, which must now be applied. To one portion in a 
 test-tube, add a small quantity of transparent lime-water ; in a short time, if 
 arsenic is present, the fluids will become turbid and opaque. To another portion, 
 add a few drops of liquid ammonia, and a solution of sulphate of copper ; this 
 will produce a bright green precipitate, which is the pigment called Scheele's 
 S^. 6 "; . Pass a current of sulphuretted hydrogen gas through another portion, 
 which will convert the arsenic into a sulphuret of a lemon yellow colour. To 
 another portion add a few drops of ammoniated nitrate of silver, which will 
 throw down a golden yellow precipitate, the arsenite of silver. If all these 
 tests produce the effects here described, the corroboration will leave no room to 
 doubt that aresenic was present ; but it is advisable, and especially where 
 human lite depends on the testimony, to place the matter beyond the possibility 
 ol doubt, by reducing the arsenic to the metallic state. This is effected by taking 
 any of the before-named precipitates, and, when carefully dried, mixing it with 
 about an equa quantity of black flux (finely divided charcoal and potash). A 
 few grains of this must be carefully placed at the bottom of a test-tube, so that 
 none shall adhere to the side. The flame of a spirit lamp must now be directed 
 by a blow-pipe against the matter in the tube, and, in a short time, the arsenic 
 will be sublimed, and coat the interior of the glass with the reduced metal of a
 
 a piece oi 
 white clo' 
 
 *SSAY. 107 
 
 shining grey colour ; or any of the precipitates may, when dry, be placed on 
 iece of ignited charcoal, when the arsenic will be volatilized, forming a dense 
 oud, and emitting a powerful odour, like that of garlic, which is peculiar 
 to this metal. Arsenic is a metal easily combustible, and, in some cases, burns 
 with singular intensity. If a small quantity is mixed in a mortar with chlorate 
 of potash, a violent explosion takes place. When thrown into chlorine gas, it 
 takes fire spontaneously if finely divided. The spec. grav. of arsenic is 5.763. 
 A sulphuret of arsenic, called orpiment, is extensively used in dyeing. It is 
 prepared by digesting arsenious acid in muriatic acid, and precipitating by sul- 
 phuret of ammonia. It is of a bright yellow colour, and produces a permanent 
 dye. Arsenic is used for various purposes in the arts (see ALLOY) ; it promotes 
 the fusion of other metals, and occasions many that are very refractory to melt 
 at low temperatures. It is employed in the manufacture of lead shot, which it 
 renders more brittle, and more easy to granulate. 
 
 ASAFCETIDA is the concentrated juice of a large umbelliferous plant, which 
 is found in several parts of Asia. The root is of a black colour, and resembles 
 a parsnip; on cutting this transversely, a thick white juice exudes, which, by 
 exposure to the air, becomes of a dark brown colour. The fresh juice has even 
 a more powerful odour than the concrete asafcetida, which resembles that of 
 garlic. The Persians, who export large quantities of it, are compelled to hire 
 vessels on purpose, as its effluvia penetrates every article on board, and spoils 
 many productions. Asafcetida is of a yellowish brown colour, of an acrid taste, 
 and powerful smell. It consists chiefly of gum, resin, and earthy matter. In 
 medicine it is used as a deobstnient, and sometimes as an anthelmintic, and is 
 useful in nervous and hysterical affections. 
 
 ASBESTOS (amianthus). A fibrous mineral, found in large quantities in 
 Corsica. It is also procured from Savoy, France, Scotland, Sweden, and other 
 places, but is nowhere so abundant as in Corsica. The fibres of asbestos 
 were formerly manufactured into cloth, which was employed in wrapping the 
 dead body intended to be burned ; the asbestos being incombustible by fire of 
 the ordinary kind, the ashes of the corpse were thus preserved distinct. Nap- 
 kins were also made of it, which were cleansed, after use, by burning instead of 
 washing. Wicks of lamps were also made of this material, and are now, in 
 some cases, used with advantage. The art of making the cloth of asbestos 
 seems to have been entirely lost during the middle ages. The Chevalier 
 Aldini has, however, by the agency of steam, succeeded in rendering the tough 
 and brittle fibres sufficiently pliable for weaving into cloth, and exhibited in 
 London gloves, caps, and other parts of dress made of asbestos, which, as being 
 incombustible, and a very bad conductor of heat, he proposed should be worn 
 by firemen. 
 
 ASPHALTUM. Called also mineral pitch, Jew's pitch, and bitumen, is a 
 hard black substance, resembling pitch in appearance, but having a higher 
 internal polish. It is found on the shores of the Dead Sea, in China, America, 
 and some parts of Europe. Asphaltum was anciently employed in embalming 
 dead bodies. The Temple of Jerusalem, and the walls of Babylon, are said to 
 have been built of stones cemented together with asphaltum, for which purpose 
 it is well adapted. It is sometimes employed in making black varnish, and is 
 a component of the beautiful black liquid used in printing the numbers on 
 watch and clock faces. The spec. grav. varies from 1 07 to 1.65. It is soluble 
 in oils and ether, if pure Asphaltum was formerly employed in medicine, but 
 it is now seldom administered. 
 
 ARTILLERY, in its most extended sense, is applied not only to the guns, 
 projectiles, powder, carriages, &c. used in warfare, but to the men employed in 
 working them. Military engineering, however, not according with the object 
 and scope of this work, the information afforded therein on the subject of artil- 
 lery is confined to the construction of the most improved FIRE-ARMS, GUNS, 
 PROJECTILES, &c. which see under their separate heads. 
 
 ASSAY. The separation of a valuable metal from its alloy or impurities. 
 The art of assaying differs from that of analysis in this respect : by analysis 
 the various component parts of the mineral or alloy are separated, and their
 
 108 ASSAY. 
 
 respective quantities estimated ; by assay only the valuable metal or ruetals it 
 sought for. Jn the assay of gold or silver alloys, for example, the inferior 
 metals are dissipated, and the quantity estimated only by the loss of weight. 
 There are two modes by which the art of assaying is performed, and sometimes 
 one is employed to corroborate the other. The one is called the humid process, 
 by which a solution of the metals is effected by means of acids, after which those 
 sought for are precipitated by proper re-agents ; the other is called the dry 
 process, and is performed by the agency of fire. In the mining districts, the 
 comparative value of some ores is roughly estimated by the dry process of 
 assaying. In London, the mode is seldom resorted to, except for the purpose of 
 estimating the quantity of gold or silver in an alloy. The quantity of these 
 metals, or of platinum, in any alloy, may be as correctly estimated by the dry, 
 as by the humid, process ; we shall therefore describe the mode of assaying 
 those alloys in this article, and refer the reader to the analysis of ores (see ORE) 
 for the most correct mode of assaying other metallic compounds. An alloy of 
 gold is assayed by detaching from different parts of the article a small portion, 
 by a knife or a file, until the requisite number of grains for the experiment is 
 obtained. These being carefully weighed, are wrapped in a piece of sheet lead, 
 and placed in the bowl of a cupel, and exposed under a muffle to an intense 
 heat. The cupel is a small cubic or circular solid, with a cavity on the upper 
 surface to receive the metal ; it is made of a very porous material ; the ashes 
 of burnt bones, made into a paste with water and slowly dried, are generally 
 employed for this purpose. When the alloy and lead are exposed to intense 
 heat, as before described, fusion of the whole ensues, but the lead speedily 
 becomes converted into a vitreous oxide or glassy fluid ; this powerfully promotes 
 the oxidation and vitrification of any inferior metal contained in the alloy, and 
 when they are thus changed, they percolate through the porous cupel, and leave 
 only a globule of metal not oxidable by heat. This globule, therefore, will be 
 of gold or silver, or a compound of them, these metals, as well as platinum, 
 not being affected by the action of fire and air. To separate the silver from 
 the gold, the alloy is hammered or rolled into thin plates, and digested with 
 dilute nitric acid; this dissolves the silver, but does not act on the gold. When 
 the first solution is poured off, another portion of nitric acid is added, to effect 
 a perfect solution of all the silver. The gold is now left as a porous spongy 
 mass, and when washed and dried, its quantity is ascertained by weighing. 
 If the quantity of silver in the alloy be small, the excess of gold defends it 
 from the action of the nitric acid ; the process called quartation must therefore 
 be resorted to. This consists in adding three parts of silver to the mass, and 
 fusing them together. The silver, then, being in excess, is all separated by the 
 mode before described. The quantity of silver may be ascertained by pre- 
 cipitating it from the solution with muriate of soda. An insoluble substance, 
 chloride of silver, is thus formed, which, when carefully washed, dried, and 
 weighed, will indicate the quantity of the metal, 100 parts of the chloride con- 
 taining 75$ of silver. In estimating the commercial value of gold and silver 
 articles, they are said to be so many carats fine : the carat does not denote any 
 specific weight, but a part. Each article is said to contain 24 carats, whatever 
 may be its weight; and the quantity of alloy in carats, or parts, is deducted from 
 the whole. Thus, if an alloy contain 4 parts of inferior metal, it is said to be 
 20 carats fine; if it contain 6, it is of 18 carats fine, which is the standard of 
 jewellery in England. In France, where every small article of gold is assayed 
 before it is permitted to be sold, a different mode of assay is adopted. The 
 trinket is rubbed on a black touchstone, formed of the black basaltes ; black 
 flint or pottery will answer the purpose as well. The jeweller states the quan- 
 tity and nature of the alloy employed in the article, and the mark it makes on 
 the touchstone is compared with a similar mark made by a needle composed of 
 the same metals and the same proportions. If they correspond in appearance, 
 and are not differently affected by nitric acid or heat, the alloy is pronounced 
 to be of a similar kind to the needle. A great number of assay needles, formed 
 of different proportions of alloys, are necessary for this mode of assay, and long 
 practice and experience in the artist are indispensable. He is guided in the
 
 ATMOMETER. 109 
 
 operation, not merely by the appearance of the stroke on the touchstone, but 
 also by the comparative roughness or smoothness, dryness or greasiness, which 
 is observed in rubbing. The gold coin of Great Britain is 22 carats fine : 
 silver coin is composed of 12$ silver and 1 of copper. An alloy of silver with 
 an inferior metal is assayed by cupellation alone, the process of quartation not 
 being necessary. A given portion is placed in the cupel with a sufficient 
 quantity of lead, and exposed under a muffle to intense heat, until the lead 
 and other inferior metals are vitrified and absorbed by the cupel. The workman 
 Js guided in this operation by the appearance of the melted globule. Until the 
 last portions of the alloy have passed through the cupel, the mass appears to 
 be in a state of commotion or ebullition; but when they are absorbed, the silver 
 becomes quiescent, and exhibits brilliant prismatic colours. 
 
 ASTRINGENT. A substance possessing a peculiar rough austere taste. 
 This is remarkable in the tincture of galls, bark, the husks of walnuts, green 
 tea, port wine, &c. Leguin first observed that the astringent principle might 
 be separated from the tincture of galls by albumen, with which it forms an in- 
 soluble compound. Astringents are sometimes called tannin, and are extensively 
 employed in tanning leather. Astringents are used in medicine to relieve 
 diarrhoea, and as tonics. 
 
 ASTROSCOPE. An astronomical instrument, composed of two cones, on 
 whose surfaces are exhibited the stars and constellations, by means of which 
 they are both easily found in the heavens. 
 
 ATHANOR. A kind of furnace, which has long since fallen into disuse. 
 The very long and durable operations of the ancient chemists rendered it a 
 desirable requisite that their fires should be constantly supplied with fuel in pro- 
 portion to the consumption. The atlianor furnace was peculiarly adapted to 
 this purpose. Beside the usual parts, it was provided with a hollow tower, 
 into which charcoal was put. The upper part of the tower, when filled, was 
 closely shut by a well-fitted cover, and the lower part communicated with the 
 fire-place of the furnace. In consequence of this disposition, the charcoal sub- 
 sided into the fire-place gradually, as the consumption made room for it ; but 
 that which was contained in the tower was defended from combustion by the 
 exclusion of a proper supply of air. A variety of domestic stoves for burning 
 bituminous coal, on the same principles, but with a different object, that of 
 burning the smoke, have of late years been introduced and patented. See 
 STOVE, and GRATE. 
 
 ATMOMETER. The name given to an instrument, by its inventor, Pro- 
 fessor Leslie, to measure the quantity of exhalation from a humid surface in 
 a given time. A thin ball of porous earthenware, 2 or 3 inches in diameter, 
 with a small neck, has cemented to it a long and rather wide tube of glass, 
 bearing divisions, each of them corresponding to an internal section, equal 
 to a film of liquid that would cover the outer surface of the ball to the thick- 
 ness of ^ part of an inch. These divisions are ascertained by a simple calcu 
 lation, and numbered downwards to the extent of 100 or 200. To the top of 
 this tube is fitted a brass cap, having a collar of leather, and which, after the 
 cavity has been filled with distilled or boiled water, is screwed tight. The out- 
 side of the ball being now wiped dry, the instrument is suspended out of doors 
 to the free action of the air. The quantity of evaporation from a wet ball is 
 the same as from a circle having twice the diameter of the sphere. In the 
 atmometer, the humidity transudes through the porous substance just as fast as 
 it evaporates from the external surface ; and this waste is measured by the cor- 
 responding descent of the water in the stem. As the process goes on, a corre- 
 sponding portion of air is likewise imbibed by the moisture on the outside, and 
 being introduced into the ball, rises in a small stream to replace the water. The 
 rate of evaporation is nowise effected by the quality of the porous ball, but 
 continues the same, whether the exhaling surface appears almost dry, or glisters 
 with superfluous moisture. When the consumption of water is excessive, it may 
 be allowed to percolate gradually, without dropping, by unscrewing the cap. In 
 a review of Leslie's Meteorology, published in the Journal of Science, for Oct. 
 1822. the writer recommends a vessel of porous earthenware, of a given surface
 
 110 ATTRACTION. 
 
 filled with water, to be poised at tlie end of a balance, ind the loss of weight 
 which it suffers by evaporation in a given time, to be noted. A thermometer 
 being inserted into the mouth of the vessel, will indicate the temperature of the 
 evaporating mass, and would form, at the same time, a good hygrometer, on 
 Dr. Black's principle, that the degree of cold generated by evaporation is pro- 
 portional to the dryness of the air. See Leslie on Heal and Moisture ; also Ure's 
 Dictionary, 
 
 ATTAR OF ROSES. An essential oil, obtained from roses, of great value, 
 and possessing wonderful odoriferous properties. Gareepon is celebrated 
 throughout India for the beauty and extent of its rose gardens ; the rose-iields 
 occupy many hundred acres; the roses are cultivated for distillation, and foj 
 making attar. The price of a sieve, or two pounds' weight, (a large quart) of 
 the best rose-water, is eight lenas, or a shilling. The attar is obtained after 
 the rose-water is made, by setting it out during the night, until sunrise, in large 
 open vessels, exposed to the air, and then skimming off the essential oil, which 
 floats on the top. To produce one rupee's weight of attar, 200,000 well-grown 
 roses are required. The juice, even on the spot, is extravagantly dear, a 
 rupee's weight being sold at the bazaar (where it is often adulterated with 
 sandal-wood oil) for 80 s. r., and at the English warehouse for 100 s. r. or 101. 
 sterling. Mr. Mellville, who made some for himself, said he calculated that the 
 rent of the land and price of utensils really cost him 51. for the above quantity. 
 
 ATTRACTION denotes the tendency which is observed in bodies to approach 
 and adhere to each other; it is also sometimes employed to signify the unknown 
 cause of this tendency. It assumes various names, according to the circum- 
 stances in which it acts. Thus we have the attraction of gravitation the 
 attraction of electricity, or electrical attraction the attraction of magnetism 
 cohesion, and chemical affinity. The first three of these act at sensible dis- 
 tances, but the range of the other two is too limited to be appreciated by the 
 unassisted senses. 
 
 The Attraction of Gravitation is the power that upholds the whole planetary 
 system, and retains bodies on the surface of our earth ; its action is perceptible 
 at the remotest part of the solar system, and is even manifest among the 
 fixed stars and nebulae. The laws to which the manifestations of this power 
 are subject will be stated under the article on GRAVITY: at present, we shall 
 confine ourselves to a statement of two experiments connected with this 
 subject, which will clearly evince the existence of this power as inherent, not 
 only in the earth, as a distinct body, but in small, and even detached portions 
 of its surface. The first of these experiments was made by Dr. Maskeline, on 
 the mountain Shebralien, in Scotland. A long plumb-line, attached to a 
 telescope, was suspended successively on the north and south sides of the 
 mountain, when it was found, on each occasion, that the plumb-line did not 
 hang perpendicularly, but was deflected towards the mountain. The other 
 experiment was made by Mr. Cavendish, who, by means of a long and fine 
 silver wire, suspended a slender deal rod, so that it might, by twisting the wire, 
 vibrate freely in a horizontal plane. Small balls of lead were attached to the 
 ends of the deal rod, and, by means of mechanism, larger balls of that metal 
 were carefully brought near to the smaller ones. At each approach of the 
 larger balls, the small ones were sensibly attracted, made to vibrate, and finally 
 arrange themselves in a new position. 
 
 Attraction of Electricity is that which occurs between two bodies, one of 
 which is electrified positively, and the other negatively ; or one of which is 
 positive or negative, and the other in its natural state. It is probable, however, 
 that this last case is merely apparent, since every body, when brought near to 
 an electrized body, becomes itself electrical by induction. See ELECTRICITY. 
 
 Attraction of Magnetism is that which takes place when a loadstone or an arti- 
 ficial magnet is approximated to a piece of iron or steel. It also occurs when 
 the south pole of one magnet is made to approach the north pole of another. 
 
 Cohesive Attraction is that which subsists among the minutest particles or 
 atoms of a body, forming them into a solid mass. In gases, this power appears 
 to be wholly deficient, or at least more than counteracted by the effects of an
 
 AUGER. ill 
 
 antagonist power repulsion. In liquids there are but small manifestations of 
 its existence, but in solids it evinces itself in the most decided and conspicuous 
 manner. The intensity of the cohesive force varies in different bodies, whether 
 solid or liquid, a circumstance which renders a knowledge of its laws of the 
 greatest importance to mechanics, engineers, and other practical men. For the 
 elucidation of these laws, and the facts on which they are founded, see COHESION. 
 
 Chemical Attraction is that which connects the particles of different bodies, 
 and forms them into compound substances. Thus, the power that unites the 
 particles of a mass of copper is called cohesion ; but that which causes the union 
 of copper with sulphuric acid, or nitric acid, so as to form sulphate or nitrate of 
 copper, is denominated chemical attraction, affinity, elective attraction, or attrac- 
 tion of composition. Hence we see that chemical attraction and cohesion co- 
 exist in the same body. Thus, in the sulphate of copper, one particle of sulphate 
 of copper is connected with another particle by cohesion ; while, at the same 
 time, the particles of sulphuric acid are connected with those of copper by 
 chemical affinity. See CHEMISTRY. 
 
 AUGER. The name of a very efficient instrument, extensively used by car- 
 penters, and other mechanics, for boring holes in wood. There are several 
 varieties adapted to their peculiar offices, or to the prejudices of workmen. The 
 oldest, or common auger, has a long iron shaft, with a large cross handle at 
 right angles to it, at the top, for enabling the workman to apply both his hands 
 with a considerable leverage, in turning round the shaft, into which is welded a 
 semi-cylindrical piece of steel, from 3 to 6 inches in length, which varies with 
 the size or diameter of the hole made by the instrument ; the extremity of this 
 niece is furnished with a sharp tooth, and a cutting edge, which is a small 
 portion of a spiral, and inclined so as to cut as a chisel, the edge operating upon 
 u radical line proceeding from the centre of the hole ; and, as it is being con- 
 stantly turned in a circular direction, the chips of wood are turned out in spiral 
 pieces, and are received into the semi-cylinder above, which has usually one of 
 its longitudinal edges a little sharp to keep the sides of the perforator clean. The 
 upper portion of the shaft is made smaller than the lower, or steel part, for facili- 
 tating the escape of the chips, and to enable the instrument to pass the bore freely. 
 
 Another instrument, differing from the foregoing, is provided at its extremity 
 with a conical screw, like a gimlet, for piercing the wood the more readily and 
 truly. We have, indeed, frequently noticed in well-made augers of this kind, 
 that no pushing, or rectilineal force whatever is required, the screw keeping 
 them always up to their work. 
 
 In a third instrument, chiefly used by shipwrights, that portion of steel, al- 
 ready described, as of a semi-cylindrical form in the common auger, is altogether 
 in this made of a spiral figure, and is found to facilitate the boring materially, 
 besides preventing all liability of the chips becoming jammed or clogged in the 
 tool, which pass freely through the spiral channels, and are discharged exter- 
 nally as the perforation is continued. 
 
 A patent for an improvement upon the last-mentioned auger was taken out 
 about ten years ago, by Dr. Church, of Birmingham ; but the originality of his 
 invention has been the subject of dispute. In the specification of the patent, 
 the principle of the inventor is stated to consist in forming an instrument of a 
 helical figure, by winding a bar of steel of a " mixtilinear trapezoid" shape, 
 round a cylindrical mandrel, by which a circular hole is formed throughout 
 its length, for the insertion of a movable central guide-pin ; the upper end of 
 this central pin is screwed into the shank of the auger, and the lower, or 
 working part, is furnished with a wood screw ; the office of the latter is to draw 
 the auger into the wood as it is turned, the cutting edges on the helical part at 
 the same time clearing the wood as this auger deepens in the perforation. In 
 grinding and sharpening the edges of the auger, the central pin is, of course, 
 removed for the purpose ; and it is obvious that the edges may be ground and 
 sharpened as long as any of the spiral steel bar remains, which renders the 
 instrument extremely valuable, as one, with proper care, may be made to last 
 a man's life-time. This auger, besides, far surpasses all others by the rapidity 
 and facility of its operation.
 
 11? AUGER. 
 
 sittgerfor making square holes. It appears that endeavours to supersede the 
 tedious and somewhat difficult process of truly forming square and other shaped 
 holes, varying from the circular, by means of mortice-chisels, were made both 
 in this country, and in America, at about the same period of time. A machine 
 tor this purpose, invented by Mr. A. Branch, of New York, was described in 
 the Franklin Journal of Philadelphia, in the year 1826. It was stated to con- 
 sist of an auger, formed like the American screw auger, with the twisted part 
 inclosed in a case or socket, extending from the upper part of the twist to the 
 cutting edge, allowing the small entering screw to project beyond it. The ex- 
 ternal form of the socket is either square, or otherwise, according to the 
 intended shnpe of the hole to be bored, a large portion of its sides being cut 
 away to allow the chips to escape. The lower end of the socket is of steel, with 
 a sharp cutting edge, bevelled towards the inside. The cutting-edges are not 
 allowed to terminate in right lines, but are made concave, so as to admit the 
 angular points to enter the wood first, this causing it to cut with greater ease, 
 and more smoothly than it otherwise would. The upper part of the socket 
 forms a collar, which works freely on the shank of the auger, just above the 
 twisted part, and is retained in its place by a pin and other appendages. When 
 a longitudinal hole, or mortice, is wanted, two or more augers are placed side 
 by side, furnished with their appropriate sockets, and retained in their places 
 by obvious contrivances." The same journal stated that it was very efficient in 
 its operation, boring a square hole with well defined angles, with nearly the 
 same rapidity as a round one of the same diameter, and forming it with a 
 degree of truth unattainable by the ordinary methods. Upon the publication of 
 Mr. Branch's invention in this country, the editor was invited by Mr. Thomas 
 Hancock, of Goswell-Street Road, to see, in his manufactory, a similar machine, 
 constructed by him several years previous ; and having proved its efficacy by 
 boring a considerable number of square holes with great facility, and finding 
 that the angles were perfect, and the holes clean, and exactly uniform through- 
 out, we were induced to make a precise drawing of it, a representation of 
 which, on a scale of one-third (lineal measure) of the original, is given in the 
 subjoined engraving. At a a, Fig. 1, is a strong iron frame or support, fixed 
 by screw-bits b b to the work-bench c ; d is an octagonal iron socket, containing 
 a brass bush, tapped to receive the vertical screw e e ; to this screw is affixed, 
 by a circular tenon and mortice, the square perforating instrument /, which 
 accurately fits and slides up and down through a rectangular hole, in a guide of 
 brass g, when the screw e is turned by the cross handle at top; so that the 
 square incision is made by direct pressure downwards, at the same time that 
 the revolving centre-bit m cuts out a completely round hole, the chips rising up 
 and passing out at the two open sides of the square cutter ; h represents a piece 
 of wood in the act of being bored, the dotted lines showing the depth to which 
 the perforation has reached ; a small piece of wood i is placed underneath, to 
 prevent injury to the cutting-tool, by coming in contact with the cross iron 
 plate k ; the bolts b b passing through i as well as Jc, secure both firmly to the 
 bench c. Fig. 2 exhibits the cutting part of the instrument, separately, on an 
 enlarged scale, with the lowermost portion in section ; the tenon i is inserted 
 into a cavity in the screw e, Fig. 1, and made fast by a cross pin, which goes 
 through both ; by this arrangement the instruments can be readily exchanged 
 for others of different dimensions ; the lower extremity of this revolving piece 
 is formed into a centre-bit m, which, owing to the collars n n, cannot ascend 
 or descend without the square instrument, which accurately cuts out the angles 
 beyond the range of the circular incision made by the former. The square 
 cutting-tool is made of a bar of steel, with a hole drilled out of the solid, in the 
 manner shown by the end view, Fig 3, and the edges are then formed by filing 
 and grinding them to the bevels, or angles, shown in section by Fig. 2. Fig. 4 
 represents a similar view of the end of the instrument, but with the centre- bit 
 in its place. It will be readily perceived that a square tool, by repeating the 
 
 ncisions side by side, close together, may be made to produce a cavity of the 
 ngure of any rectangular parallelogram of any length or breadth, larger than 
 
 . instrument employed. The same effect may likewise be produced by a
 
 AUGER. 
 
 113 
 
 tilineal cutter, embracing all the centre bits, would then suffice for the purpose. 
 In like manner, any acute or obtuse-angled figure, any polygon, or any figure 
 with curved sides, might be made of any size whatever. By the construction 
 of the machine described, it will be perceived that it is necessary, in changing 
 
 Fig. 2. 
 
 the tool, to change also the guide-piece through which it slides. The screwing 
 and unscrewing of the guides may, however, be avoided, by having tenons it, 
 the latter of an uniform size, to fit in a mortice in the upright iron frame ; and 
 in manufactories where a great variety of mortices have to be made, we would 
 suggest another mode, in which the trouble of changing the guides would be 
 still less : it is to have a guide wheel turning horizontally upon the upright bar 
 a as its axis ; on the circumference of the wheel should be made a series of 
 apertures, corresponding with the form of the tools and of the mortices required. 
 By this arrangement- indeed, most of the tools might be left in the giu'de-wheel,
 
 1H AUTOMATON. 
 
 ready to bring any one of them into action under the screw, by just turning the 
 wheel round. In those branches of business wherein a great number of mor- 
 tices are required of one size, a machine of the kind described will be most 
 valuable ; and as it requires no skill in the operator, a boy, or a mere labourer, 
 will perform the operation as well as the most experienced workman. Chair 
 makers might adapt a machine on this principle to their work with important 
 advantages; wheelwrights, also, for morticing out their naves. In the large 
 workshops of carpenters, an instrument of the kind described would forward a 
 great deal of work in framing, as it might easily be so modified- as to perfoi-m 
 the office also of a cramp to draw the jointed parts of the work into close con- 
 tact. It is to be observed, that Mr. Branch's instrument is the same in principle 
 as Mr. Hancock's, but that it will require some modifications to render it as 
 efficient an instrument. 
 
 AURUM MUSIVUM, or MOSAICUM, is a combination of tin and sulphur, 
 having the appearance of bright gold in powder. It is used by japanners, and 
 for varnished works, as snuff-boxes, tea-trays, &c., also to statue and plaster 
 figures. The usual process of preparing it is as follows : amalgate 12 parts of 
 the purest tin with 3 parts of mercury ; the amalgam is then triturated in a 
 stone mortar with 7 parts of the flour of sulphur, and 3 parts of muriate of 
 ammonia. The mixture is next put into a matrass, and the whole exposed to a 
 gentle sand heat, until no more white fumes arise. After this, the heat is 
 somewhat raised, and cinnabar sublimes, together with some oxygenated muriate 
 of tin, while at the same time the remaining tin and sulphur unite, forming the 
 aurum musivum, exhibiting a golden yellow, and flaky scaly matter of a metallic 
 lustre. The principal point to be attended to is the regulation of the fire ; for 
 if the heat be too great, the aurum musivum fuses to a dark-coloured sulphuret 
 of tin. The process of the Marquis de Bouillon, as described by Chaptal, differs 
 from the foregoing in the proportions; and the experiments of the latter chemist 
 are also worthy of notice. The marquis's process consisted in amalgamating 
 8 oz. of tin with 8 oz. of mercury, and mixing with this 6 oz. of sulphur, and 
 4 oz. of muriate of ammonia. This mixture is to be exposed for three hours to 
 a sand heat, sufficient to render the bottom of the matrass obscurely red hot. 
 Chaptal, however, found that if the matrass containing the mixture were exposed 
 to a naked fire and violently heated, the mixture took fire, and a sublimate was 
 formed in the neck of the matrass, consisting of the most beautiful aurum 
 musivum in large hexagonal plates. Bergman mentions a native aurum musivum 
 from Siberia, consisting of tin, sulphur, and a small proportion of copper. 
 According to Dr. John Davy, the aurum mosaicum, or mosaic gold, consisted 
 of 100 tin, and 56.25 sulphur. Berzelius makes the proportions 100 tin, and 
 52.3 sulphur. The mean of those results, viz. 100 tin -f- 54.2 sulphur, may 
 therefore be regarded as the correct proportions. A few years ago a patent was 
 taken out by Messrs. Parker and Hamilton, for an alloy of copper and zinc, which 
 they termed the true mosaic gold. The specification directs that equal quantities 
 of copper and zinc are to be melted at the lowest temperature at which the 
 former will fuse, when they are to be well stirred and mixed together ; small 
 quantities of zinc are then added by degrees, until the alloy assumes the desired 
 colour. It is essential that the heat should be as low as possible, to prevent the 
 rapid evaporation of the zinc. The alloy first assumes a yellow colour; the 
 addition of more zinc turns it first to a purplish tint, which ultimately becomes 
 perfectly white/which is the colour it should have when in a state of fusion. It 
 may then be cast into ingots for use ; but it is preferable to cast the alloy, in 
 the first instance, into the forms required, as a portion of the zinc flies off on 
 remelting. 
 
 AUTOMATON. In the strict sense of the word, a piece of mechanism in 
 which the effects are produced by some inanimate force contained within it ; 
 the word is, however, more commonly used to signify a piece of mechanism 
 made to resemble some animal, whose motions it imitates by means of internal 
 machinery, which being concealed from the spectator, gives it an apparent 
 power of acting by volition. Numerous descriptions of automata of this class 
 are to be found in the writings of various authors, amongst the most admirable
 
 AUTOMATON. 115 
 
 of which may be ranked the automaton flute-player of M. Vaucauson, of 
 which the ingenious inventor published a very full description. It is to be 
 regretted that this description was not, at least as far as we can find, accom- 
 panied by drawings, which were desirable for the better elucidation of the sub- 
 ject We are, on this account, induced to relinquish our desire to give place to 
 it here, and must content ourselves merely by observing, that the figure was of 
 the natural size, and that the different notes were produced by a current of air, 
 urged by bellows contained within the pedestal on which it was placed, and 
 passing through the lips into a flute, the holes of which were stopped by the 
 motion of the fingers of the figure, whose tongue and lips were likewise movable, 
 and aided in the modulation of the sounds. The same artist also subsequently 
 produced another figure, representing a Provenfal shephei'd playing on a pipe, 
 and beating a tabor, which he describes as attended with greater difficulty in the 
 execution than the preceding one. But of the many inventions of this description, 
 none have attained such celebrity as the automaton chess player of Baron de 
 Kempelen, of Vienna. It was a figure, representing a Turk seated at a square 
 table, or chest, the top of which formed the chess-board, on which the automaton 
 made the various movements. It was exhibited in most of the leading cities of 
 Europe, but the principles of its construction were never disclosed ; nor, although 
 it had been frequently asserted by many persons that the whole was a trick, and 
 that the motions were produced by an individual concealed within the figure, 
 various ways in which this might be effected being pointed out, was any exami- 
 nation permitted sufficiently strict to lead to the exposure of the deception, if 
 any was practised. The exhibiter affected great apparent openness in displaying 
 the various machinery of wheel-work and levers which the interior certainly 
 did contain ; but this might have been placed there as much for the purpose of 
 aiding in a deception, as for any useful object. When the writer saw the figure, 
 during its exhibition in the Haymarket, in 1816, it was shown in a manner which 
 precluded any close examination ; the spectators were ranged upon a series of 
 rising benches, at a considerable distance from the figure ; the attendant first 
 opened several doors in the machine in succession, to show that no person was 
 concealed within it ; the doors being then closed, the machine was wheeled" 
 round the room, that it might be seen there was no connexion with the floor. 
 The game then commenced; the person who played against the figure was 
 seated at a small table, railed off at some distance from it, and had before him 
 a chess-board, with the full complement of black and white chess-men ; the 
 chess-board before the figure was furnished in a similar manner. When the 
 player made a move, the attendant made a similar move upon the chess-board 
 of the automaton ; and when the latter moved, the attendant repeated the move 
 upon the chess-board of the person playing. Without pretending to explain the 
 manner in which the motions of the figure were produced, we think that from 
 the very nature of the thing we may assert that they were not effected by the 
 mechanism contained within it, for we consider mere machinery utterly incom- 
 petent to produce the requisite effects. We shall proceed to state the grounds 
 on which we have come to this conclusion. Any variety of movements which 
 are required to follow each other in a certain order of succession, may doubtless 
 be produced by mechanism, as, for instance, the striking parts of a clock, or, 
 more especially, in the calculating machine of Mr. Babbage ; nor is it necessary 
 that the succession be in any regular order, provided, as in the kaleidoscope, 
 the results may be altogether arbitrary, or the effect of accidental combinations; 
 but the moves at chess, although they follow no regular order of succession, 
 for they may be infinitely varied, may yet not be made indiscriminately, but 
 depend upon circumstances beyond the control of the machine, such, for 
 instance, as the moves of the antagonist, or the number and position of the 
 pieces on the board. From these considerations, we conclude either that the 
 motions are governed by some person from without, by means of some inge- 
 niously contrived and concealed mechanism, or by some person secreted within 
 the machine. The author of a pamphlet on the subject, published in 1821, 
 maintains the latter supposition to be the fact; and by the aid of several diagrams, 
 shows that not merely a dwarf, as was at one time supposed, but even an ord'v-
 
 nc 
 
 AXLE-TREES. 
 
 nary-sized man, might be concealed ; and this opinion is further corroborated by 
 the proprietor refusing to exhibit the figure in action, with the several doors of 
 the machine open, when requested to do so by a scientific gentleman, whose 
 object was to satisfy himself and some friends that the movements were really 
 produced by machinery. 
 
 AXE. A heavy steeled instrument, employed for cutting down trees, and 
 by carpenters and other mechanics for cutting large masses of wood, when 
 attention to much exactness is unnecessary, or the saw cannot be conveniently 
 used. It consists of a broad blade of iron, with a loop, or eye, for the recep- 
 tion of a long wooden handle, which passes through it at right angles. The 
 cutting-edge is steeled to about an inch in breadth and to the back of the eye, 
 in some kinds, is welded a solid lump of steel, called the poll, which serves the 
 carpenter as a very efficient heavy hammer for driving spikes, forcing up large 
 tenons, mortices, &c. The form of axes are very various, being adapted to 
 peculiar trades, and accommodated to provincial prejudices. The most perfect 
 instruments we have seen of this kind, are the productions of several tool- 
 smiths, distributed over the county of Kent. One we recollect at Seal, another 
 at Seven Oaks. We have thought it proper to mention this fact, as the article 
 alluded to has a very decided superiority over those made in our great manu- 
 facturing towns. The smaller kind of axes, weighing under 2 Ibs. each, are 
 denominated hatchets. 
 
 AVIARIES. A place appropriated to the feeding and rearing of birds, suf- 
 ficiently extensive to allow them scope for flight The inclosure is usually made 
 of net-work, duly supported, but preferably of wire-work. The interior is 
 sometimes provided with trees, and other objects of nature ; and the floor 
 covered with turf, to avoid the appearance of dirt. 
 
 AXIOM. A self-evident truth, or one that neither requires nor admits of a 
 proof, because it cannot be made plainer by demonstration ; as, for instance, " a 
 whole is greater than a part." 
 
 AXIS, in Geometry, is the straight line about which a plane figure revolves, 
 so as to produce or generate a solid ; or it is a straight line drawn from the 
 vertex of a figure to the middle of the base. The axis of a circle or sphere is 
 a straight line passing through the centre, and terminating at the circumference 
 on the opposite sides. The axis of a cone is the line from the vertex to the 
 centre of the base. The axis of a cylinder is the line from the centre of the 
 one end to that of the other. Transverse axis, in the ellipse and hyperbola, is 
 the diameter passing through the two foci, and the two principal vertices of the 
 figure. In the hyperbola it is the shortest diameter, but in the ellipse it is the 
 longest Conjugate axis, in the ellipse and hyperbola, is the diameter passing 
 through the centre, and perpendicular to the transverse axis. It is the shortest 
 of all the conjugate diameters. 
 
 AXIS, in Mechanics, is a line about which a body may turn : by workmen, 
 the term axis is generally considered to imply a cylindrical bar, around or upon 
 which a wheel, or other body, rotates. 
 
 AXIS, in Peritrochio, a pedantic name which has been given to one of the 
 mechanical powers, commonly called the wheel and axle. 
 
 AXLE-TREE. The pivot, or centre, upon which a carriage wheel turns. They 
 were formerly made of wood, and, we believe, are to this day, in some parts of 
 the country, but are now generally constructed of iron. Numerous improve- 
 ments have, of late years, been introduced in their construction, some of which 
 we shall notice, after a few words upon their more ancient construction. One 
 very old plan was to fix the axle immovably into the naves of both wheels, the 
 axle revolving in bearings attached to the carriage; by this means the nave 
 was less weakened, and the wheels had less play, than if the axle-tree was fixed 
 to the carnage, and worked in a box in the nave, but were inconvenient in 
 
 rnmg, as both wheels revolved with the same speed ; the axle-trees were, 
 heretore, attached to the carriage, and each wheel revolved separately upon its 
 axle, by which means, in turning short, the inner wheel could remain sta- 
 nnary and serve as the centre of motion to the carriage. Axles -were 
 originally made straight, their arms lying in the same horizontal plane, and
 
 AXLE-TREES. 
 
 117 
 
 the wheels, of course, perpendicular to them ; but as carriages came more gene- 
 rally into use, more room was required ; and the roads being narrow and bad, 
 and the wheels being, therefore, required to keep in the beaten track, recourse 
 was had to splaying the wheels, by bending the axles downwards, by which 
 means the upper part of the rims of the wheels were further apart than the 
 lower ; and this method continues in general use to this day, although the im- 
 proved state of the roads no longer requires it, and the draft is made heavier, 
 and the roads more quickly destroyed by it. The objects chiefly aimed at in 
 the various improvements in axle-trees, is to diminish the friction by decreasing 
 the amount of rubbing surface, and by carefully excluding dirt from the boxes ; 
 in keeping them well oiled, and to attach the wheel so securely as to avoid 
 the fatal consequences arising from the linch pin falling out We shall now 
 proceed to describe two constructions of axle-trees, invented by Mr. Mason, of 
 Margaret Street, Cavendish Square; the first adapted to what are commonly 
 called Collinge's, or patent axles ; and the second, to the description of axles 
 called mail-coach axles. The first construction is shown in Figs. 1, 2, 3, and 4. 
 
 Fig. 1 represents a perspective view of the axle, with its principal append- 
 ages arranged in a line to show the mode of their application. Fig, 4 repre- 
 sents a longitudinal section of the axle-tree, with its several appendages screwed 
 up into their respective places, and lying inclosed in the box peculiarly con- 
 structed for that purpose. Figs. 3 and 4 give sections of certain parts of the 
 axle-tree and box, hereafter to be described. The like letters refer to similar 
 parts in each figure, a <z, the main part of the axle-tree ; b, a fixed shoulder ; 
 c, a movable shoulder formed upon a metal collet, and rendered capable of 
 being slided backwards and forwards, but not of turning round. This collet is 
 adjusted and retained in any required situation, as will be presently shown ; d 
 is a screw formed uj:on the "outer end of the axle-tree ; e is a nut, hexagonal on 
 the outside, and screwed in the inside to fit d. Around the inside of the hex- 
 agonal nut are cut longitudinal, and at equal distances, six semicircular 
 grooves (as partly shown in Fig. 1), but more distinctly seen in the section 
 Fig. 2; the screw d lias, likewise, two similar grooves cut into its thread, and 
 flo placed with regard to each other, that when one groove corresponds with 
 one of the grooves in the nut, the other groove shall be midway between two 
 9
 
 118 
 
 AXLE-TREES. 
 
 other grooves in the nut ; and, in order to fix this nut in the required position, 
 a cylindrical pin, which is rivetted to the hexagonal plate/, is inserted into one 
 of the holes formed by the union of a groove in the nut with a groove on the 
 axle, which entirely prevents any rotation of the nut so long as the pin remains 
 in the hole ; and there being two grooves in the axle, and six in the nut, the 
 position of the nut may be regulated to ^ of a turn, equal to ,-^j of an inch, 
 if the screw has 1 threads per inch. To prevent this pin coming out, a collar 
 of leather g is first put on the long hexagonal-headed screw h, when the latter 
 being screwed into the internal screw of the axle-tree (seen at Figs. 2 and 4), the 
 whole is thus made fast. Having thus described the construction of the axle- 
 tree, it remains for us to explain the construction of the box, which we have put 
 in section in its proper place, around the axle-tree in Fig. 4. k k k k show the 
 cylindrical parts of the box, with a cap / / screwed on its outer extremity, which 
 serves to contain oil for those parts of the axle-tree which are contiguous, o o 
 are long grooves also for oil ; two of these are brought into view in the longi- 
 tudinal section, Fig.\\ but there are four of them, as may be seen in the trans- 
 verse section at Fig. 3, which section is made where the dotted line divides 
 Fig. 4. p p is another reservoir for oil. The whole of the arrangements in 
 this invention appear to us excellent. The quantity of oil contained in the 
 reservoirs, and which is constantly circulating round the axle, is greater than in 
 any other wheel-box that we recollect, and must greatly reduce the friction. 
 The ease and safety with which the wheel may be let out when travelling on 
 bad roads, is another great advantage, and which we believe to be peculiar to 
 this axle, whilst the method of securing the wheel upon the axle seems to leave 
 nothing to be desired on that bead. This last part of the invention may be 
 also usefully employed in various parts of machinery, as where wheels run upon 
 studs, or pivots, &c. The figure beneath represents Mr. Mason's improved mail 
 
 axles, although some parts of the invention are applicable to the patent axles. 
 a is the box cap, which constitutes at the same time an oil cup with a conical 
 end c, which fits into the conical part g of the axle /; when that is fitted into 
 the box e and the cup screwed into d, the oil then flows through an aperture 
 in the end of the cup c into the hollow part of the axle, and passes out to 
 the box at an aperture h, supplying the long reservoirs in the interior of the 
 box. There is, likewise, a very small groove cut longitudinally on the axle, 
 extending both ways from h, so that the oil may be readily distributed over all 
 the bearing parts. This lubricating arrangement is, evidently, applicable to 
 both kinds of axles, but the other part of the contrivance, which has for its 
 object the better security of the wheel, and the prevention of end-play, so as 
 not to allow the escape of oil from the box, nor the admission of dust, or other 
 impurities into it, applies exclusively to the mail axles, or those which are kept 
 in the box by means of screws at its inner end. Three wrought-iron screws 
 are cast into three legs on the box, two of which are shown in the figure at 
 n re. When the axle is introduced into the box, the conical part t fits the 
 conical partj, and tends to preserve the leather collar between i and k, while 
 the loose plate m fits upon, and is firmly secured by, the screws n n to the end 
 of the box, and thus the box is kept in its place by the collar k, which works in 
 the recess I, and the wheel is prevented from coming off by the plate mm.
 
 AXLE-TREES. 
 
 119 
 
 Formerly, this plate was fastened by short screw-bolts passing through it and 
 the legs of the box, a method which was found defective on account of their 
 liability to shake loose by the constant jarring of the coach. To remedy this, 
 and to facilitate the removal of the wheel when desirable to take it off, the back 
 plate was fastened by long bolts passing through the nave and screwed on the 
 outside ; but this, too, was found to be objectionable, on account of the injury 
 caused to the nave by the bolt holes, and their occasional removal, when 
 the wheel required taking off; and to remedy these defects, is the object 
 of the invention which we have been describing. An objection to the 
 present mode of locking the fore wheels of four-wheeled carriages from the 
 centre, is, that in sharp turns, the fore-wheels are brought so nearly in a line 
 with the perch, that the coach has little better than three points of support, and 
 is, therefore, very liable to be overturned. Another inconvenience arising from 
 this method is, that it requires the fore -wheels to be made much smaller than 
 the hind ones, which greatly increases the draft, and has, at the same time, an 
 inelegant appearance. These objections are obviated by a construction, for 
 which Mr. Ackerman took out a patent in 1816, the principle of which is as 
 follows : The fore axle-tree of the carriage does not turn, but is fixed to the 
 perch in the same manner as the hind one ; each of the fore wheels revolve 
 upon one end of a short arm, the other extremity of which is turned up at a right 
 angle, and turns in a hinge joint at each extremity of the fixed axle-tree ; from 
 the back of each of the short axles, a lever projects, and the coach-pole being 
 carried back beyond the pin in the fixed axle-tree, an iron bar connects the 
 extremities of the two levers, and of the coach-pole, so that when the coach- 
 pole turns upon its fulcrum, the short axles turn upon their upright arms as 
 
 centres, and if the length of the connecting bar be equal to the distance between 
 the vertical arms of the axles, the two wheels will always stand parallel to each 
 other; but by varying the length of the connecting bar, the inner wheel, in
 
 120 AXLE-T EES. 
 
 turning, may be made to perform a shorter curve than the outer one. The cut 
 represents one of these arms, Fig. 1 being a front view, and Fig. 2 a side view ; 
 a is a portion of the fixed axle-tree ; b the horizontal arm upon which the wheel 
 revolves ; c the vertical arm ; d the lever ; e connecting bar. In the diagram, 
 Fig. 3, the dotted lines represent the position of the fore wheels when locked to the 
 utmost extent ; and the other lines, their position in the same circumstances, with 
 axles on Mr. Ackerman's plan, from which it will be seen that the latter afford a 
 much wider base to the carriage than the former; the wheels may also be made 
 of nearly the same diameter as the hind wheels, without hanging the body of 
 the carriage higher. A B is the line of the perch. Patents for axle-trees upon 
 the same principle have since been taken out by Miss Knowles, and by Mr. 
 Mason, varying slightly in the details. There have been many plans proposed 
 for diminishing the friction at the axle by means of anti-friction rollers ; but, 
 from the experiments made upon rail-roads, of the resistance of running wheels 
 thereon, as compared with those on common roads, it appears, the amount of 
 friction of the axes of wheels made in the common way, was so extremely 
 trifling in comparison with the resistance at the peripheries, that it became 
 absolutely impossible to gain any practical advantage of moment by such a re- 
 duction of the axles as they are susceptible of. It should be borne in mind, that 
 the weight of the carriage must be supported on some of the rubbing, or re- 
 volving, parts ; and these parts being already, comparatively, very small, their 
 surfaces cannot be much reduced without impairing the requisite strength. By 
 anti-friction rollers, we only transfer the friction, without materially lessening 
 it ; whilst we incur complexity, increased expense, and greater liability to de- 
 rangement. For these reasons, we shall notice only one out of the many con- 
 trivances on this subject ; it is the invention of Mr. Spong, and is selected as 
 being the simplest in construction, a e is the revolving axle-tree made square 
 
 at a for inserting into the nave of the wheel, to which it is made fast, by means 
 of the nut b screwing it close up to the shoulder c. The circular part of the 
 axle revolves in two bearings ; one in plummer blocks at d, regulated by screws 
 at I ; the other at e, in a solid piece projecting from the axle-tree /. The thick 
 end of the axle at o, carries an anti-friction roller k, which turns on a short pivot, 
 or axis, at i (shown by white dots). Oil is applied to the bearings and axis, by 
 means of perforations at h h, which are closed by screw stoppers. 
 
 From an account of some experiments made by Mr. H. R. Palmer, now 
 engineer to the London Dock Company, it would appear that the forms of the 
 cavities, or interstices, through which 'the lubricating matter is applied to the 
 axes of wheels, is of considerable importance. During a succession of 
 experiments occasionally for many months, he invariably perceived that when 
 fresh oil was applied to the axles of the carriage, the resistance was increased, 
 and it required the ordinary motion of the carriage for several days to restore 
 the resistance to its usual standard. No other presumption occurred to account 
 for this fact, than the possibility of the oil being better adapted for its office 
 after being some time exposed to use. It was suggested to him that the oil 
 became thickened, or less fluid, after exposure to the air, and was therefore 
 better able to resist the contact of surfaces. In order to prove this, he thick- 
 ened some oil artificially, by the admixture of a small quantity of bees'-wax, 
 but the appearances were the same as before. It then occurred to him, that 
 there was not sufficient play, or difference of diameters, between the axle and
 
 AZIMUTH. 121 
 
 the nave in which it worked; he therefore had the axles slightly reduced. On 
 again measuring the resistance, he found circumstances as before, but differing 
 in amount, the resistance being slightly increased. He was by this time con- 
 vinced that the quantity, rather than quality, of oil, occasioned the appear- 
 ances ; to prove which, the axles were made perfectly clean, and then simply 
 moistened with oil by the finger, previous to inserting them in the wheel. In 
 this state the resistance was again measured, and found to be similar to the 
 standard wually observed after the carriage had been some days in motion, as 
 before described. It being, then, proved that the quantity of oil occasioned the 
 difference of resistance, the following solution of the manner in which the addi- 
 tional quantity could produce such an effect, appeared reasonable. Let A B C D, 
 'a. 1, represent the circle of the hole in the nave of the wheel, and E C the 
 Fig. 1. Fig. 2. 
 
 A A 
 
 section of the axle. The circle E C touches A B C D only in the point C. A 
 very acute angular space then remains between A E and C on either side of 
 E C. If that space be filled with oil, the oil may be considered as a wedge, and 
 if the outer circle be set in motion, that wedge will endeavour to pass the point 
 C. But it cannot pass in its present form without raising the circle E C ; but 
 E C having the weight of the carriage upon it, would resist its passage. Now 
 this continual and unsuccessful endeavour to pass the point C will occasion an 
 impediment to the motion. To put this solution to the test, the axles were 
 formed as in Fig. 2. A B C D is the hole in the nave as before, and E F C G 
 the section of the axle. The lower semicircle of the axle here corresponds with, 
 or is parallel to, the outer circle, but no further, because if it corresponded 
 throughout the circle, the axle would be liable to jamb, as other experiments have 
 proved. The coincidence then ceases abruptly, as at B F G D, and the space 
 above which contains the oil is not angular, but the quantity of oil which is to 
 pass toward the lower semicircle is determined at B or D. On measuring the 
 resistance with the axle thus formed, he found it not increased by any quantity 
 of oil that might be inserted ; but by dispensing with the angular space, ana 
 consequent wedge-like action of the oil, the resistance was one-tenth less than the 
 former standard. In cases where the difference of diameters is considerable, he 
 does not apprehend the obstruction from the quantity of oil would be of conse- 
 quence ; but it is desirable to make the bearing surfaces nearly to correspond, 
 to obtain a greater width of touching surface, and the more perfectly to govern 
 the motion. The form of axle just described is, in fact, the converse of a well- 
 made plummer block, used in machinery. 
 
 AZIMUTH, in Astronomy, is an arch of the horizon intercepted between the 
 meridian of a place, and the azimuth, or vertical circle, passing through the 
 given object ; or it is the angle formed at the zenith by the meridian and ver- 
 tical circle. The azimuth of the sun, or a star, at the time of the equinox, is 
 found by the following proportion. As the radius is to the tangent of the lati- 
 tude of the place of observation, so is the tangent of the sun's, or star's, 
 altitude, to the cosine of the azimuth from the south. 
 
 AZIMUTH, Magnetic, is an arch of the horizon included between the mag- 
 netic meridian, and a vertical circle passing through the object. It differs from 
 the true azimuth, on account of the variation of the magnetic needle. The 
 magnetic azimuth may be determined by observations with the azimuth com- 
 pass, and the true azimuth calculated therefrom
 
 122 
 
 BALANCE. 
 
 AZOTE, or NITROGEN. The phlogisticated air of Dr. Priestley. It contains 
 four-fifths of atmospheric air, and one-fifth of oxygen. See CHEMISTRY, and 
 NITROGEN GAS. 
 
 AZURE. The blue colour of the sky, and the name given to a celebrated 
 Egyptian pigment, which has preserved its brilliancy of tint for upwards of 
 seventeen hundred years. The late Sir Humphrey Davy, who experimented 
 on the constitution of this substance, found that it might be easily and cheaply 
 imitated. Thus take 15 parts of the carbonate of soda, 20 of powdered opaque 
 flints, and 3 of copper filings ; strongly heat them together for two hours, when 
 a substance will be produced, which, when powdered, affords a fine deep-coloured 
 blue pigment, closely resembling the Egyptian azure. 
 
 AZURE-STONE, or LAPIS-LAZULI, is a massive mineral, of a fine azure 
 blue colour. Lustre, glistening. Fine grained, even fracture. Scratches glass, 
 but scarcely strikes fire with steel. Opaque, or translucent, on the very edges. 
 Easily broken. Spec. grav. 2.85. It consists, according to Mes. Clement and 
 Desormes, of 34 silicia, 33 alumina, 3 sulphur, 22 soda, loss 8,=100 parts. 
 The finest specimens are brought from Persia and China. It is from these 
 stones that me beautiful unchangeable blue pigment, ultramarine, is prepared. 
 The stones are first made red hot, then thrown into water to cool them sud- 
 denly, which enables them to be easily pulverized. The fragments are then re- 
 duced to a very fine powder in a mortar, and intimately combined with a 
 varnish composed of resin, bees-wax, and linseed oil. It is then of the con- 
 sistence of paste, and is put into a linen cloth, and repeatedly kneaded with hot 
 water. The first water is thrown away, the second gives a blue tint of the first 
 quality, and the third yields one of less value. This processis founded on the pro- 
 perty which the colouring matter of the lapis-lazuli has of adhering less firmly 
 to the resinous cement, than the other matter with which it is combined 
 
 B. 
 
 BAKING, in its true sense, implies the process of applying a dry or scorching 
 heat to any substance in a close vessel or chamber ; but the term is generally 
 understood to mean the art of preparing bread, for which see BREAD, OVEN, &c. 
 BALANCE. A simple machine, in which the lever is employed to determine 
 the equality or difference of two given weights. Balances are of various kinds, 
 differing in their form, and in the perfection of their construction, according to 
 the nature of the objects for which they are employed. The common balance 
 or scales are well known to consist of a lever 
 or beam a b, turning on its axis in a ver- 
 tical plane, and having two dishes or scale- 
 pans d e suspended at its two ends. The 
 distances between the centre of the beam 
 and the extremities a and b are made as 
 nearly equal as possible : hence it is clear, 
 from the nature of the lever, that the 
 weights placed in the two scales will be 
 equal to each other when the beam rests in 
 a horizontal position. Although, theoreti- 
 cally speaking, the balance is exceedingly 
 simple, consisting merely of a right line 
 turning on its centre, yet in practice it 
 becomes a matter of considerable difficulty 
 SSFS!?^ hs construction to that perfection which theory points out, and 
 which the nicer operations of philosophical research demand. Although it is 
 not necessary on all occasions to use a balance capable of detecting differences 
 in weight equivalent to the ^ of a grain, yet the more perfect our model is, 
 and the nearer we approach to it, the greater chance there is of obtaining the 
 oDject oi our search, viz. an exact indication of the weight of any given sub- 
 nee. In the most perfect balances, one of which is represented in the annexed 
 engraving, the beam I, L is a bar of tempered steel, so strong as not sensiblv
 
 BALANCE. 123 
 
 to bend with the weights usually placed in it If G is the centre of gravity of 
 the beam, the arms G L G L should be of precisely the same length. At the 
 extremities, silk cords of the same length and weight support the scale-pans A A, 
 which are also equal. That the slightest motion of the beam may be distin- 
 guished, an index S C is attached to the beam exactly perpendicular to it, and 
 in the same plane with the centre of gravity. The whole is sustained on an 
 
 axis perpendicular to the beam at C ; and in order that the line around which 
 the beam turns may not change its place, and thus vary the lengths of the arms, 
 the axis is formed below into a sharp knife edge of hardened steel, and moves 
 on planes of polished crystal, agate, or other hard substance. Now if a perfect 
 equality were established between the parts of the balance on each side the 
 centre G, an equilibrium would naturally occur when the beam L L' was in a 
 horizontal position ; for the centre of gravity of the whole would then be in the 
 same vertical line as the point C ; hence if weights were placed in the scale, 
 and the beam retained its horizontal position, we might infer their equality. 
 But an experiment of this kind may be possible or not, according to the posi- 
 tion in the vertical line of the points C and G. If the centre of gravity G 
 coincided with the centre of motion C, the beam would rest in any position 
 into which it might be thrown. Or if the centre G were above the centre C, 
 the beam would remain horizontal when placed so, but its equilibrium would 
 be unstable, and the least additional weight to either side would cause that side 
 to descend indefinitely. But if the centre of gravity be below the centre of 
 support, then, if the horizontality of the beam be deranged, it will be recovered 
 after a succession of oscillations of continually diminishing amplitude. The 
 delicacy, or stability, of the beam, will depend, in a great measure, on the dis- 
 tance between these two points. Thus, if G be much below C, a considerable 
 weight will be required to turn the beam, but it will soon regain its state of 
 rest. On the other hand, if the point G be only a short distance below C, a 
 slight additional weight will cause the arm to descend, but it will be longer in 
 regaining its quiescent position. The sensibility is increased by lengthening 
 the arms, diminishing the distance between the centre of support and centre of 
 gravity, and lessening the weight of the beam, and the quantity of matter to be 
 weighed. The stability also increases with the weight, and the distance between 
 the two centres. As another step towards the perfection of the balance, we 
 must be careful that the centre C and the knife edges that support the scale- 
 pans at L L, be in the same right line. Ifthis be neglected, the beam becomes
 
 T24 BALANCE. 
 
 a bent lever, and the weight of the body will appear to vary with the position 
 of the beam. The great difficulty of attaining an exact equality in the length 
 of the arms of a balance, renders it almost hopeless to attempt to obtain the 
 exact weight of any mass of matter by this means. It is fortunate, therefore, 
 that there is a method of weighing which will enable us to dispense with one of 
 these, and uot the least difficult of attainment. The method of double weigh- 
 ing, introduced by Borda, renders the equality in the length of the arms a 
 matter of indifference. To ascertain the weight of a body by his method, we 
 place the body hi one scale, as A, for example, then exactly counterbalance it 
 by small shot, sand, &c. placed in the other scale A, till the index points to O 
 on the scale at the foot of the pillar supporting the beam. The body is next 
 carefully removed from the scale A, and its place supplied by known weights, 
 until the beam again stands horizontal. The weights then in the scale will indi- 
 cate the weight of the body. As the weights, and the body to be weighed, have 
 both been placed in the same scale, and, consequently, at the same distance 
 from the centre, it is manifest, whatever may be the length of the arms, or their 
 weight, that the true weight of the body has been ascertained. That this method 
 may be completely efficient, only two conditions are required to be fulfilled. 
 The one is, that the distances between the centre C, and the points L L , con- 
 tinue the same during the operation of weighing ; and the second is, that the 
 balance be exceedingly sensible, i. e. that it turn with the smallest possible 
 quantity of matter. The first of these conditions is fulfilled by making the 
 points L and I/, of hardened steel, and sharpened to a knife edge, like the 
 point C, as, in this case, the motion of the beam will not sensibly change the 
 points of support, and, consequently, the distance between C and L will be 
 accurately preserved. The second condition is to make the balance sufficiently 
 sensible, which is accomplished by attention to the centre C, diminishing its 
 friction as much as possible. For this purpose, the planes that support the 
 knife-edge are highly polished ; and, in order that they may be preserved in 
 their original state, the beam is not suffered to rest upon its centre but when in 
 actual use. To sustain it when not in use, the two forks, F F are employed, 
 which raise it from its support, and preserve it in a horizontal position. These 
 forks are movable by means of the handle N. When the balance is to be used, 
 the forks are lowered, and the beam set at liberty ; and, as soon as the obser- 
 vation is completed, the forks are raised, and the beam elevated from its sup- 
 ports till again required. To preserve the balance from the motions that would 
 result from currents of air, it is sometimes inclosed in a glass case, having aper- 
 tures in it large enough to admit the substance to be weighed to be put into the 
 pans. When the instrument is not in use, it is recommended to place within 
 the case a small saucer filled with muriate of lime, or some other substance ot 
 strong hygrometric power, to absorb the moisture that would otherwise settle on 
 the instrument, and destroy its polish by oxidation. In order to ascertain the 
 value of a balance, the scales may be removed from the beam, to see whether 
 the beam balances without them. They may then be put on again in opposite 
 sides, and tried. Equal weights should then be placed in each scale, and after- 
 wards changed to the opposite one ; and if the beam maintains its horizontal 
 position during all these trials, it may be considered as accurate. The utility 
 of good balances for weighing different substances, is not limited to the accu- 
 rate performance of delicate experiments, but applies also to the saving of much 
 time in weighing, when a smaller degree of accuracy is required. If a pair of 
 Bcales, loaded with a certain weight, be barely sensible to one-tenth of a grain, 
 it will require a considerable time to ascertain the weight to that degree of 
 accuracy, because the turn is email, and must be observed several times over ; 
 but, if a balance were used that would turn with the hundredth part of a grain, 
 and the weight was not required to any greater accuracy than the tenths of 
 grains, a single tenth of a grain, more or less, would make so great a differ- 
 ence in the position of the beam, that it would be seen immediately. If a 
 balance be found to turn with a certain additional weight, and is not moved by 
 any smaller weight, a greater sensibility may be given to it by producing a 
 vibratory, or tremulous motion, in its parts. If the edge of a blunt saw, file,
 
 BALANCE. 125 
 
 or similar instrument, be drawn along any part of the case, or support, of a 
 balance, it will produce a jarring which will diminish the friction on the moving 
 parts so much, that the balance will turn with a third or fourth of the addition 
 that would otherwise be required. In this way, a beam that would barely 
 turn with one-tenth of a grain, may be made to turn with a thirtieth ot 
 fortieth of that quantity. The improvement in the balance has progressed 
 with the general advance of the mechanic art, to such an extent, that it would 
 seem impossible to attain a higher degree of perfection than that which has 
 been attained in the construction of some modern balances. Mr. Read's balance, 
 described in the sixty-sixth volume of the Philosophical Transactions, readily 
 turned with one pennyweight, when loaded with fifty-five pounds, but distinctly 
 turned with four grains, when tried more patiently. This is about ^ part of 
 the weight. In the same volume, a balance, by Mr. Whitehurst, is described, 
 which weighed one pennyweight, and turned with ^ of a grain, or ^'555 f its 
 weight. Ramsden's balance, turning on points instead of edges, is described in 
 the seventy-fifth volume of the Philosophical Transactions. With a load of four 
 or five ounces, a difference of one division in the index was made by ^ of a 
 grain This is 3sl ^ of the weight, and, consequently, this beam will ascertain 
 the weight correctly to five decimal places. The Royal Society's balance, which 
 was recently constructed by Ramsden, turns on steel edges upon planes of 
 polished crystal. Dr. Ure states, " I was assured that it ascertained a weight 
 to the seven millionth part. I was not present at this trial, which must have 
 required great care and patience, as the point of suspension could not have 
 moved over much more than the two hundredth of an inch in the first half 
 minute ; but from some trial, which I saw, I think it probable that it may 
 be used in general practice, to determine weights to five places and better. The 
 assay balance is of a similar kind to that which is here described in detail, but 
 small, and extremely delicate. It is used in docimastical operations, to deter- 
 mine exactly the weight of minute bodies. The beam should be made of the 
 best steel, and of the hardest kind, as this metal is less apt to be spoiled with 
 rust than iron, and it more easily takes a perfect polish, which, at the same 
 time, prevents the rust. The longer the beam is, of course, the more exactly 
 may the weight be determined ; but, in general, ten or twelve inches is con- 
 sidered a sufficient length. The thickness of it should be so small, that two 
 drachms might hardly be hung at either end without its bending ; for the largest 
 weight put upon it seldom exceeds one drachm. The whole surface of the beam 
 should be without ornament, as these only collect dust, and render the balance 
 inaccurate. The whole apparatus is, when used for nice experiments, enclosed 
 in a case with glass faces, and which are opened only so far as may be neces- 
 sary to introduce the weights and the body to be weighed. 
 
 Balance Hydrostatic, is a balance furnished with apparatus adapted to ascer- 
 tain the specific gravity of bodies, by weighing them in liquids, as well as in air. ^ 
 A common balance, of a good construction, and furnished with a small hook * 
 beneath one of the pans, is, with the usual appendages, quite sufficient for a 
 hydrostatic balance. An accurate and delicate balance, that may be adapted 
 to this purpose, and is easily constructed, is thus described in Brewster's Philo- 
 sophical Journal. Let a slender beam of wood 
 be procured, about eighteen, or twenty-four 
 inches long, and tapering a little from the 
 middle to each end. Let a fulcrum of tem- 
 pered steel, resembling the blade of a pen- 
 knife, be made to pass through the middle of 
 the beam a little above the centre of gravity. 
 Similar steel blades are also made to pass 
 through the ends of the beam for suspending 
 the scales. The fulcrum rests on two small 
 portions of thermometer tubes, fixed horizon- 
 tally on the upright support ef. The support 
 has a slit along the middle, to allow the needle at efto play freely between the 
 aides. A small scale, made of card, and divided into any number of parts, is
 
 120 
 
 BALANCE. 
 
 placed at /for the purpose of ascertaining the point at which the needle remains 
 stationary. This balance possesses extreme delicacy. It may even be made 
 more sensible than that belonging to the Royal Society of London. I have said 
 nothing of the perfect equality of the two ends, as this condition is not at all 
 necessary to the accuracy of the balance, according to the method of double 
 weighing. To ascertain the weight of, any body, place it in one of the scales, 
 and bring the needle to any point by means of small shot placed in the other 
 scale ; observe the point opposite to which the needle rests, or the middle, be- 
 tween its extreme points of oscillation; remove the body, and put into the 
 same scale as many known weights as will bring the needle to the same division 
 as before. These weights will, evidently, be equal to the weight of the body, 
 whether the arms of the balance be equal or not. This method of weighing is 
 due to Borda. The steelyard is sometimes employed to ascertain specific 
 gravities, as in the balances of Lukin and Coates. 
 
 Lukiris Hydrostatic Balance is extremely simple, and is considered to be a 
 very accurate instrument. The appearance is given in the accompanying 
 figure. When unloaded, the arms are equipollent. C the body, whose specific 
 
 gravity is to be found, is suspended to the shorter arm of the instrument. On 
 the longer arm, the movable weight D indicates the weight of the substance in 
 air or water. If great accuracy is required, a second weight,, which is a sub- 
 multiple of the first, may be added on the longer arm. Then the division 
 marked by the larger weight may be units, and that of the smaller, tenths, or 
 hundredths, as may be thought proper. 
 
 Coates's Hydrostatic Balance is upon the same principle as Lukin's, but differs 
 in the mode of graduation. This being adapted for finding the specific gravity of 
 minerals, instead of pointing out the actual and relative weights, it shows at 
 once their specific gravity. The instrument is accurately balanced when un- 
 loaded, by making the shorter arm much larger than the longer one ; and the 
 latter is graduated, and marked with numbers, which every where show the 
 quotient of the entire length of the longer arm, divided by the distance of the 
 given mark from the end. Thus, at half the length, is marked the number 2 ; 
 at one-third, the number 3 ; and so on. These numbers extend on the scale to 
 rather more than 20, in order to render the instrument applicable to the heavier 
 metals. In using this instrument, a weight is suspended by a hook at A, and 
 the body under examination is to be hung by a horse hair on the shorter arm, 
 and slid along as on the steelyard, till an equipoise is obtained, say at D. Then 
 without altering its situation on the beam, the body is to be immersed in water, 
 and balanced a second time, by sliding the weight C along the graduated arm, 
 till the two are again in equilibrio. The hook of the weight will then at once 
 ndicate, by its situation on the scale, the actual specific gravity of the body, 
 water being considered as unity. The instrument being supposed in equilibrio,
 
 BALANCE. 
 
 127 
 
 and the distance B D and the weight of the counterpoise being constant, the 
 weight of the body varies as the distance of the counterpoise from B. Thus, if 
 the counterpoise have to be removed nearer to the centre B, to balance the 
 body when weighed in water, the specific gravity, as seen on the scale, will b> 
 
 4, or four times greater than that of water. If it have to be removed i nearer, 
 the specific gravity is 12, and so on. The truth of the principle will appear, if 
 we consider that the specific gravity of any body, as compared with water, is 
 found by dividing its weight in air by its loss of weight jn water. Now its loss 
 of weight in water is proportional to the approximation of the weight C towards 
 the centre. If, therefore, the whole arm, which always represents the weight 
 in air, be divided by the quantity by which the weight approximates to the 
 centre, it is clear that the quotient which is marked on the scale will be the 
 true specific gravity required. 
 
 The annexed figure represents a balance beam, invented by Mr. J. H. Patten, 
 Rhode Island, United States, for the purpose of taking the specific gravities of 
 different bodies, and for the accurate weighing of minute quantities. The 
 manner of using the instrument, it will be seen, is similar to that of Lukin* 
 
 balance, just described. The beam a b c is made of steel sufficiently strong, 
 but light. The dish is suspended at a ; the beam itself upon an axis at b ; at 
 e is the milled head of a long screw, which is fitted with a shoulder and axis, 
 and goes through the slide e that traverses upon b c, and carries the weight d. 
 Now, suppose it required to obtain ten grains, place that weight in the dish/, 
 and screw back the weight d until it exactly counterbalances it. If the weight 
 be now removed, and a quantity of the substance to be weighed be substituted, 
 until the index points to where it did at first, there will then be very nearly thn
 
 128 
 
 BALANCE 
 
 exact weight, differing only by the amount of the friction of the instrument 
 This beam may be used as a steelyard, by screwing the weight d to any number 
 marked upon the scale ; and should a greater quantity be required than that 
 marked in the first line, another weight, double that of d, may be substituted. 
 The ancient balance was the statera, or steelyard, in which the arms are of 
 unequal length, and one movable weight is used, placed at different distances 
 from the centre of motion, or fulcrum. The annexed figure represents the 
 common steelyard, in which c is the 
 fulcrum, or centre ; c b the longer arm, 
 and c a the shorter, e is the article to 
 be weighed, suspended to the shorter 
 arm, and d the constant weight. Now, 
 if the shorter arm, by its additional 
 thickness, be a counterpoise to the 
 longer, so that the beam, when un- 
 loaded, may hang in a horizontal 
 position, it is manifest, that equal weights, hung at equal distances from the 
 centre, will balance each other; but if one of the weights be removed further 
 from the centre, that side will preponderate. From this, it appears that a large 
 weight e suspended at b, may be counterpoised by a small one suspended at d. 
 If the distance between c and d be nine times greater than that between c and e, a 
 weight of 10 Ibs. at d will counterbalance one of 90 Ibs. at e. To prevent the 
 necessity for calculation, the longer arm is graduated, so that the exact weight 
 may be known by inspection. 
 
 The Danii/t Balance is also a steelyard, but in this the weight is fixed at one 
 end, the article to be weighed at the other, and the fulcrum, or support, movable 
 between them. In the annexed cut, 
 b represents the standard weight, and 
 a the hook, to which the article 
 whose weight is required, may be sus- , 
 
 pended, and d is tbe movable fulcrum. fi_ _ , ,11 5) ""^v 
 
 If a b were supposed a perfectly JSP =1-0 
 
 straight rod without weight, the gra- 
 dations on it should be at equal dis- 
 tances; but as this cannot be the 
 case in practice, a different arrange- 
 ment is required. If c be the centre of gravity of the beam, and the fulcrum 
 be placed at this point, it is clear that the beam will be supported in an hori- 
 zontal position ; but if a weight be appended to the hook a, the centre of gravity, 
 which in all cases must be supported, will be removed to d, for example, and, 
 consequently, the fulcrum must be moved to the same point. In this case, 
 there is not only a difference in the leverage, or length of the arms, but there 
 is the weight of the portion c d taken from one side and added to the other. 
 The best method of graduating this instrument is by experiment, by applying 
 known quantities at the point a, and marking the place of the fulcrum d when 
 an equilibrium takes place. 
 
 The Chinese Balance is a steelyard, somewhat different from the Roman 
 statera. It is much used by the Eastern merchants in weighing gems and 
 precious metals. The beam is a small rod of wood or ivory, about a foot in 
 length. Upon this there are three lines of measure, made of delicate silver 
 studded work. The scales commence at the end of the beam, whence the first 
 extends to 8 inches ; the second to 6 ; and the third to 8 \. The first indicates 
 European weight, and the other two Chinese. At the other end of the beam a 
 scale is suspended ; and at three several distances from this end are fastened so 
 many fine strings, forming so many different points of suspension. The distance 
 of the first point from the end is | of an inch ; the second ^ ; and the third ^. 
 When the instrument is used, it is hung up by one of the strings, and a sealed 
 weight of about 1J oz. is hung upon some one of the divisions of the rule, so as 
 to counterbalance the weight of the article, which is indicated by the graduations 
 yf the scale.
 
 BALANCE. 
 
 The Bent Lever Balance is represented in 
 tlie annexed figure, in which a c b is a bent 
 lever, moving on the centre c as its fulcrum, 
 or axis, of motion. To the shorter arm of the 
 lever at 6, a scale-pan e is appended, while 
 the other arm has a heavy weight affixed to 
 its other extremity a, which passes over the 
 quadrantal arch / g. The substance to be 
 weighed being placed in the scale e, the end 
 a will indicate the weight by the height to 
 which it rises on the graduated arch. A little 
 attention to the diagram will show that, as the 
 end b descends, the other extremity a ascends, 
 and, at the same time, removes to a greater 
 distance, from a vertical line passing through 
 the centre of motion. In the present posi- 
 tion of the balance, the effective length of the arm c b, is k i, and of the arm 
 c a, is k d. Now, as these are of equal lengths, the weight a (omitting ihe 
 weight of the lever itself) will be equal to that of the substance placed in the 
 scale. But as the weight approaches the point g, the effective length of a c will 
 be represented by k h, and the weight a will therefore act with as much more 
 power, as the length of k h exceeds that of k d. If the point continued at the 
 same distance from the vertical line, passing through c, the efficacy of the 
 weight would, at any point in the arch, be proportional to the length of a per- 
 pendicular drawn from that point to the vertical line ; but as the distance of b 
 is constantly varying, we can only state, generally, that the divisions will be 
 nearer together as we approach the upper part of the scale. 
 
 Paynes Weighing Machine is of the steelyard kind ; the longer arm is divided
 
 130 
 
 BALANCE 
 
 by lines denoting the various weights, as usual ; but, instead of the weights 
 being suspended by hooks immediately on the beam, they are attached to a long 
 case, or box, which slides with some friction along the beam. Beneath one enc 
 of this sliding box is a large hook, to which is suspended the heavy weight, 
 which is used to measure the larger quantities, as hundred weights, and quar- 
 ters, which are denoted by the divided lines on the beam, as the sliding box is 
 drawn over it. To measure the smaller quantities, as pounds and ounces, there 
 is a light scale of parts fixed to the top of the sliding box, to which a hook and 
 weight are hung, which are applied in the same manner as the common steel- 
 vard. In the preceding engraving we have given a view of the whole arrange- 
 ment, the longer arm of the beam being somewhat shortened to save room. In 
 this representation, a a is the beam ; c is the fulcrum ; d a long rectangular 
 loop through which the arm a a passes, and which serves to support it when not 
 in use, or to limit its vibrations when employed in weighing ; e is the sliding- 
 box, with its graduated scale, for the minuter quantities, which are to be ascer- 
 tained by the smaller weight g ; f the larger weight, which may be secured at 
 pleasure, at any point, by means of a thumb-screw above, half a turn of which 
 fixes the slide against the beam, while the more minute quantities are being 
 taken. The goods are placed in the scale h, which may then be raised from 
 the ground by turning the handles k k, which causes the screw i to enter the 
 nut above. Machines qn this principle are made of all sizes, to weigh either 
 tons or ounces. 
 
 Brabijs Balance, or Weighing Apparatus, unites the properties of the bent 
 lever balance, and the steelyard. It has been termed a domestic balance by the 
 
 inventor, from its being peculiarly adapted for family purposes, such as weigh- 
 ing meat, bread, butter, &c. In the figure A B C is a frame of cast-iron, 
 which has the greater part of its weight towards A, in consequence of ita
 
 BALANCE. 131 
 
 greater thickness at that part. F is a fixed fulcrum, and E H a movable sus- 
 pender, which has a scale and hook at its lower extremity. E K G are three 
 distinct points to which the suspender E H may be applied, and to which belong, 
 respectively, the three graduated scales of weights / C, c d, ab. When the 
 suspender is applied at G, the apparatus is in equilibrio with the edge A B hori- 
 zontal, and the suspender cuts the zero of the scale ab. If a weight be now 
 placed in the scale, the whole apparatus turns about F, and the point en the side 
 B C descends till the equilibrium is again established. The weight placed in 
 the scale may now be read off from the point where the suspender cuts the 
 scale a b, which registers to ounces, and is adapted to bodies whose weight does 
 not exceed two pounds. If the weight of the body exceeds two pounds, but is 
 under eleven, the suspender is placed at K ; and when the upper edge of the 
 balance is horizontal, the weight, or number 2, is found a little to the right of 
 the index of the suspender ; if, now, weights exceeding two pounds be placed in 
 the scale, the whole again turns about F, and the weight of the body is shown 
 on the graduated arc c d, which extends to eleven pounds, and registers to 
 every two ounces. If the weight of the body exceeds eleven pounds, the sus- 
 pender is hung on at E, and the weights are ascertained in the same manner 
 on the scale/ C to thirty pounds ; the subdivisions on this scale are quarters of 
 pounds. The same principle might be extended to weights greater than the above. 
 To prevent mistake, the three points of support, G, K, E, are numbered 1, 2, 3; 
 din arcs are respectively numbered in the same manner. 
 
 When the hook is used instead of the scale, the latter is turned upwards, there 
 being a joint at H for that purpose. 
 
 Balance of Torsion. If a piece of very fine wire, silk, or spun glass, ex- 
 tended by a weight, be suspended to any fixed point, and then twisted, it will, 
 when released, begin to untwist itself, and, by its momentum acquired in the 
 act of untwisting, will twist in the opposite direction. It will afterwards return, 
 and thus, by a series of oscillations, continually diminishing in amplitude, it 
 will at length come to a state of rest in its original position. Now, if a needle, 
 or an index similar to the hand of a watch, be attached to the lower extremity 
 of the suspended wire, and a circle, having its circumference graduated into 
 degrees, or other equal divisions beneath it, it will form the balance of torsion. 
 To measure small forces, as those of electricity, magnetism, &c., with this 
 balance, they are made to act on one extremity of the index ; and when the 
 force is in equilibrio with the tendency of the wire to untwist, the angle which 
 the index makes with its quiescent position, which is called the angle of torsion 
 is the measure of the force employed. In the annexed 
 cut, let a b c g represent the graduated circle, and a g 
 the index suspended by the silver wire at the point e. 
 Suppose any force act upon a so as to move it to b, then 
 will the arcs a b represent the angle of torsion. Sup- 
 pose another force to act at the same distance, and 
 move the ball to c, then will the latter force be mea- 
 sured by the arc a c; and hence the intensity of the 
 former force is to that of the latter, as a b to a c. To 
 preserve the index from disturbance by the air, the whole is enclosed in a glass 
 cylinder, at the upper part of which, where the wire is attached, there is an index 
 and a divided circle, which is used to twist the wire, when the measure of a force 
 becomes greater than a whole circumference. The sensibility of this instrument 
 will depend on the dimensions of the suspending wire. Thus, if the length of the 
 wire be doubled, the sensibility will be increased in fhe same proportion, *. e. 
 only half the force will be required to twist the wire a given number of degrees. 
 If the diameter of the wire be increased, the sensibility is diminished in a great 
 degree ; thus, if there be two wires of the same length, but one twice the thick- 
 ness of the other, the latter will require sixteen times more power than the former 
 to twist ty through a given number of degrees ; the force of torsion being pro- 
 portional to the fourth power of the diameter, and sixteen it will be seen is the 
 fourth power of two. If the wire be increased three times in diameter, the 
 sensibility^will be decreased 3X3X3X3 81 times.
 
 132 
 
 BALING MACHINE 
 
 Balance of a .catch, is that part 
 which, by its motion, regulates and 
 determines the vibrations. The cir- 
 cular part is called the rim, and its 
 spindle the verge; there also belong 
 to it two pallets, that play in the 
 fangs of the crown-wheel. In 
 pocket watches, the strong stud in 
 which the lower pivot of the verge 
 plays, and in the middle of which 
 one pivot of the crown-wheel runs, 
 is called the potent* ; the wrought 
 piece, which covers the balance, 
 and in which the upper pivof of the 
 balance plays, is the cock ; and the 
 small spring in the new pocket- 
 watches, is called the regulator. 
 The motion of a balance, like that 
 of a pendulum, being reciprocating, 
 while the pressure of the wheels is / 
 in one direction, it is obvious that 
 some contrivance must be used to 
 accommodate one to the other 
 When a tooth of the wheel has 
 given the balance a motion in one ., 
 direction, it must quit it, that it 
 may obey an impulsion in the op- 
 posite direction. The balance, or 
 pendulum, thus escaping from the 
 tooth of the wheel, or the tooth 
 escaping from the balance, has 
 given to the general construction 
 the name of scapement. See Houo 
 LOGY. 
 
 BALING MACHINE. A ma- 
 chine for raising water from the 
 hold of ships. When, from the 
 pumps being rendered useless by 
 an accident, or from the extent of 
 a leak, the water gains upon the 
 pumps, the method usually resorted 
 to for getting rid of it, is to bale it 
 out at the several hatchways, by 
 means of canvas buckets ; but from 
 the difficulty of filling and raising 
 the buckets, from the heavy rolling 
 of the vessel, the most painful and 
 long continued exertions prove in- 
 sufficient to save a ship from foun- 
 dering. An apparatus, of great 
 simplicity of construction, and faci- 
 lity of application, for the purpose 
 of baling, has been invented by Mr. 
 J. Dennett, of the Isle of Wight, 
 which will, no doubt, be found a 
 powerful auxiliary to a ship's pumps 
 in cases of danger. The annexed 
 figure is a perspective view of this 
 machine, a and b are part of the 
 hatchways of the upper and lower
 
 BALLISTIC PENDULUM. 133 
 
 <tecks ; c c is a long rebated slide, in an inclined position, reaching from a little 
 above the coamings of the upper deck, to the ballast in the hold ; e is a square 
 bucket, made to slide on the rebate cc; its bottom is a flap valve, so that when 
 it slides down into the water, it opens, and the bucket fills instantly, and closes, 
 upon being drawn up full of water, without any attention on the part of the work- 
 men. The upper portion / of the rebate of the long slide is made detached, and is 
 fixed in its place by the pin g, on which it turns as on an axis. The bucket is shown 
 discharging the water on the upper deck ; and when the rope h i k is let go, the 
 bucket falls down, rights itself, and the upper portion /of the slide falling with 
 it, and joining the lower part, the bucket runs down the whole of the slide into 
 the water, is instantly filled, and drawn up again by pulling the parts i k of the 
 rope, the part k passing through a leading block m on the deck. A pin is fixed 
 on the top of the rebate, so that when the bucket rises up, and is only in the loose 
 portion /, it is stopped by the pin ; and the loose" portion /, by farther pulling, 
 rises out of its place, and upsets the bucket. To prevent the bucket being raised 
 higher than is necessary to discharge the water, a knot is worked in the rope, 
 which forms a stop against the block 1. The block / is made fast to a yard- 
 arm, and the upper end of the rope k is secured to the same, or elsewhere, with 
 just length enough to let the bucket reach the bottom of the slide. 
 
 BALLAST. Heavy substances placed in the lowest part of the hold of a 
 ship, to preserve the vessel in an upright position, when under sail. It consists 
 generally either of masses of cast-iron 3 feet long and 6 inches square or of 
 small round stones, which is called shingle ballast. 
 
 BALLAST LIGHTER. A vessel employed to remove sand, silt, or other 
 depositions from the beds of rivers, harbours, docks, &c. which is effected as 
 follows : The vessel, which is a species of open barge, being moored, a leather 
 bag, the mouth of which is distended by an iron hoop, fastened to a pole of 
 sufficient depth to reach the bottom, is put over the side, and descends to the 
 bottom in an inclined position ; two or three turns are taken with a rope 
 round the pole, and a timber-head near the stern of the boat. A rope attached 
 to the hoop of the bag, and passing over a small crow at the fore part of the 
 vessel, is then brought to a winch, and the bag is gradually wound up by a man 
 at the stern slowly slacking the rope which passes round the pole, thus allowing 
 it to rise as it approaches the vertical position ; at the same time causing such 
 friction, that the edge of the hoop digs into the ground, and the leather bag 
 receives whatever passes through the hoop. When the bag is raised above the 
 side of the boat, it is swung into the boat by the crane, and its contents dis- 
 charged into the bottom of the vessel. 
 
 BALLISTA. A machine used in ancient warfare for throwing stones or 
 darts. It in some measure resembled the cross-bow, but possessed far greater 
 projectile power. It has been thus described : An iron cylinder was fastened 
 between two planks, from which proceeded a hollow square beam, placed cross- 
 wise, and fastened with cords, to which were added screws. At one end of this 
 stood the engineer, who put a wooden shaft with a large head into the cavity of 
 the beam ; this done, two men bent the engine, by turning some wheels. When 
 the top of the head was drawn as far as the cords would allow, th'e shaft was 
 driven out of the ballista. The ballista depended and acted upon the same 
 principles as the catapulta, the moving power of which depended on the elas- 
 ticity of twisted cords, made with women's hair, that of horses, or the entrails 
 of animals. The ballista was usually employed in throwing darts, though, lika 
 the catapulta, it sometimes was used in projecting large stones. It is recorded 
 by Vegetius, that the ballista discharged darts with such velocity and force, that 
 nothing could resist their power : and Athenaaus adds, that Agistratus made one 
 of little more than two feet long, which shot darts 500 paces. 
 
 BALLISTIC PENDULUM. An ingenious machine, invented by Mr. Ben- 
 jamin Robins, for ascertaining the velocity of military projectiles, or the force of 
 fired gunpowder. It consists of a large block of wood, fixed to the end of an iron 
 lod, and suspended like the pendulum of a clock. When the pendulum is at rest, 
 a gun is pointed towards the centre of the block, and a ball fired point blank 
 into it In consequence of the magnitude of the block, compared with the ball
 
 j 34 BALLOON. 
 
 or bullet, a very small velocity is given to the former, which being accurately 
 measnred, the velocity of the ball is easily deduced ; for, as the weight of the 
 ball is to the sum of the weights of the ball and block, so is the observed velocity 
 of the block to a fourth quantity, which is the velocity of the ball sought. A 
 variety of experiments have been made by Dr. Hutton with this pendulum, 
 from which a number of useful rules have been deduced relative to the velocity 
 produced with different charges of powder, with guns of different lengths, and 
 with different sized balls. A complete series of experiments was also instituted 
 relative to the resistance of the air to different velocities, varying from to 2,000 
 feet in a second. Among other results, he ascertained that inflamed gunpowder 
 expands itself with a velocity of about 5,000 feet in a second. 
 
 BALLOON, in Chemistry, a glass vessel to receive the product of distillation. 
 
 BALLOON, AIR. A bag made of silk, paper, or other light material, for 
 containing heated air, or gas, of less specific gravity than the atmosphere. If 
 the weight of the balloon, and of the heated air or gas which it contains, be less 
 than that of an equal bulk of atmospheric air, the balloon will ascend in con- 
 sequence of the equilibrium of atmospheric pressure being disturbed ; the pressure 
 of the column of which the balloon forms a part, being less than that of the 
 ordinary atmosphere. The ascending, or upward pressure, therefore, carries the 
 lighter body up until it arrives at a more attenuated medium, which is of the 
 same specific gravity. After the discovery of hydrogen gas, the lightest of all 
 ponderable substances, it occurred to Dr. Black, that a thin bag filled with this 
 would ascend in the air. He suggested the employment of the allantois of a 
 calf for this purpose, but Mr. Cavallo, who performed various experiments on 
 this subject, found that this, and the lightest bladders he could procure, were all 
 too heavy. Chinese paper was also tried, but the gas escaped rapidly through 
 it. By filling soap-sud bubbles with hydrogen gas he succeeded, and these 
 balloons rapidly ascended to the ceiling. Within these few years small experi- 
 mental balloons have been formed of the crop of a turkey, which, when the 
 fat, &c. have been separated, are sufficiently light to ascend if filled with hy- 
 drogen gas, although some of them do not contain more than a pint. At about 
 the same period of time, two brothers, named Montgolfier, natives of Annonay, 
 in France, were trying experiments with balloons filled with heated air, the 
 specific gravity of which is less than that of air at the ordinary temperature. 
 They were led to these experiments by observing the rapid ascent of smoke 
 from chimneys, and imagined that if the smoke were confined in a large and 
 light bag, it would be borne upwards. A bag of fine silk, in the shape of a paral- 
 lelepiped, was constructed, and burning paper was held under the aperture, 
 until the balloon contained a sufficient quantity of rarefied air to carry it up to 
 the ceiling of the apartment. When this experiment was repeated in the open 
 air, the vessel ascended to an altitude of about 70 feet. Other balloons on a 
 larger scale were constructed, and a public exhibition of one containing 23,000 
 cubic feet was made at Annonay, on the 5th of June, 1783. This was formed 
 of linen lined with paper, and when filled with heated air, was capable of raising 
 500 Ibs. appended to the extremity. One of the Montgolfiers shortly after this 
 visited Paris, and as the affair had excited much attention, he was invited by 
 the Academy of Sciences to repeat the experiment at the expense of the Society. 
 A large balloon, of elliptic shape, was filled with heated air, in the presence of 
 the members, and in this state it would have ascended with a weight of 500 Ibs. 
 if the cords which prevented it had been liberated. As it was intended to 
 exhibit the ascent before the king of France and his court, this was not done, 
 and the balloon was subsequently so much damaged by wind and rain, that it 
 became necessary to construct another. This was nearly 60 feet in height, and 
 43 in diameter, and a wicker cage was attached to it, containing a sheep, a 
 cock, and a duck. The balloon, when duly prepared, ascended with these to an 
 altitude of about, 1,400 feet, and would have ascended to a greater height had 
 not a violent gust of wind torn the cloth, and permitted the heated air to escape. 
 The facility of ascending in the atmosphere being thus fully established, Pilatre 
 de Rozier offered personally to ascend in another balloon, to be constructed by 
 Montgolfier. Accordingly another balloon was completed, of enormous mag-
 
 BALLOON. 135 
 
 oitude. The height was 74 feet, and the diameter 48 ; and its weight, including 
 the car and necessary fuel for continuing the fire, was 1600 Ibs. By this the 
 intrepid Pilatre de Rozier made several ascents to an altitude of from 200 to 330 
 feet, but in these preliminary attempts the balloon was confined by cords. 
 Subsequently he ascended in company with the Marquis d'Arlandes, with the 
 balloon unrestrained, and they continued in the air about 25 minutes, and 
 descended at a distance of about five miles from the place of their departure. 
 The difference between the specific gravity of air heated by the means employed, 
 and that of air at ordinary temperatures, not being veiy considerable, the buoyant 
 power of a balloon thus filled, was comparatively small, and therefore it was 
 indispensable to employ a large quantity, and, consequently, a large machine to 
 contain it. To double the volume of air by heat, requires a temperature of 
 nearly 480 Fahr. Messrs. Charles and Roberts therefore tried the experiment 
 of filling a silk bag only 13 feet in diameter, with hydrogen gas, which is only 
 i the weight of ordinary air. The experiment was perfectly successful. This 
 small balloon was capable of raising 35 Ibs., and on being liberated, it ascended 
 to a considerable height, and after remaining three-quarters of an hour in the 
 air, descended at a distance of fifteen miles from the spot where it had ascended. 
 A balloon formed of silk, and varnished with a solution of Indian rubber, was 
 then constructed, which was filled with hydrogen gas. The diameter was 27J 
 feet, and it was covered with a net-work, to which a car, capable of holding two 
 persons, was attached. Messrs. Charles and Roberts ascended from Paris in 
 this, in December 1783, and after remaining in the air an hour and three 
 quarters, they alighted at a distance of 27 miles without accident. A sufficient 
 quantity of gas still remained in the balloon to carry up one person, and 
 Mr. Charles again ascended alone, and attained an altitude of more than 10,000 
 feet. Shortly after this successful effort, attempts were made to guide or impel 
 a balloon in any required direction ; and if this could have been accomplished 
 the invention would have introduced a new era in science. Mr. Blanchara 
 applied a species of wings to the car, but was unsuccessful in his attempt to 
 travel against the direction of the wind; nor was Morveau more fortunate with 
 large oars or sails, introduced with the same design. Numerous contrivances 
 have been since adopted, but all have been ineffectual in practice ; and, indeed, 
 when the great extent of surface which a balloon presents to the impulsive 
 force of air in motion is duly considered, the probability of overcoming that 
 force by any means which can be commanded by the aerial voyager, seems very 
 remote. Endeavours have also been made to economize the gas which the 
 balloon contains. A much larger quantity than is necessary to create the 
 buoyant power required to carry up the voyagers, is introduced, and to occasion 
 the descent of the machine, the gas is permitted to escape by a valve ; but if 
 the aeronaut require again to ascend in consequence of the unfavourable nature of 
 the ground on which he is likely to descend, or from any other cause, he 
 must part with ballast, which may be essential to his safety. The Duke de 
 Chartres, accompanied by Charles and Roberts, ascended in a balloon filled with 
 hydrogen gas, which contained a smaller within it, to be filled with common 
 air, by means of a pair of bellows, as occasion might require. By inserting 
 common air into the small balloon, the specific gravity of the machine would 
 be increased, and it would descend without loss of gas, and reascend by with- 
 drawing the common air. However ingenious the contrivance, it was not 
 found successful in practice, chiefly, perhaps, on account of the unfavourable 
 state of the wind, which was tempestuous when the experiment was made. 
 Pilatre de Rozier and Mr. Romaine, with the same design introduced a bal- 
 .'.oon filled with healed air below the ordinary balloon containing hydrogen 
 gas. The buoyant power of the heated-air balloon was equal to about 60 Ibs. ; 
 and by removing the source of heat, the specific gravity of the whole machine 
 was increased, so that it was not necessary to part with any gas during a voyage. 
 The attempt to carry this plan into execution was fatal to both voyagers. The 
 upper balloon, by means unknown, took fire, and the intrepid De Rozier 
 and his companion were precipitated to the earth and killed. It is not our 
 purpose to describe the various attempts that have been subsequently made to
 
 136 
 
 BALLOON 
 
 improve the construction of balloons, or to render them subset rient to scientific 
 purposes, since little has been effected towards accomplishing these objects. We 
 cannot, however, omit a description of an addition to the balloon, called a 
 parachute, which was first employed, with daring courage, by M. Garnerin. 
 The balloon was of the usual form, made of oiled silk, and filled with inflam- 
 mable gas: it was covered, as represented in the annexed engraving, with a 
 netting, from which cords proceeded that were tied together at a few feet below 
 the balloon ; the several cords thus collected were then twisted so as to form a 
 
 single rope, which was passed through the parachute, and fastened to the car, 
 r basket Ihe real structure of the parachute is best seen in its expanded 
 state, as shown in the descent, forming a near resemblance to a large umbrella; 
 it was made of canvass, and about thirty feet in diameter; it had no ribs, 
 
 .V-' " -"g^iici, Wits auoui ou reet; and from this point of connexion, 
 
 other shorter ropes proceeded, which were attached to the edges of the circulat 
 basKet in which the aeronaut was situated. In the place of the handle of a com- 
 mon umbrella a long tin tube was fixed in the parachute, through which the 
 single rope before-mentioned was passed, to prevent its becoming entangled, 
 aud to allow it to slip away with certainty when severed for the purpose of de- 
 scending The ascent took place on the 21st of September, 1802, from St. George's 
 ;ft fii, 7 l 1 ^-? le ^ Str f ,*' The balloon be & an ^ be filled about two o'clock" 33 
 i filled with diluted sulphuric acid, together with a quantity of iron filings, were
 
 BALLOON. 
 
 137 
 
 employed for the production of the hydrogen gas. These communicated with three 
 other casks, or general receivers, to each of which was affixed a tube that emptied 
 itself into the main tube connected to the balloon. At six o'clock the balloon 
 was completely filled ; when it rose with its long appendage of the parachute, the 
 aeronaut in the little basket closing the train. Thousands of acclamations rent 
 the air, while the eyes of tens of thousands of spectators were fixed in astonish- 
 ment and admiration at the gallant adventurer ; feelings which could be only 
 surpassed by the most intense and painful anxiety for his safety. The weather 
 was beautifully fine, with scarcely any wind. For eight minutes this intrepid man 
 continued to ascend, till he arrived at such an immense height as to be scarcely 
 visible, when he cut away the balloon. The parachute did not expand imme- 
 diately, and he fell with great velocity for a short space of time ; when it opened, 
 and his descent became gradual, but attended with a remarkable oscillation, like 
 the pendulum of a clock, to that degree, at one time, that the parachute, cords, 
 basket, and aeronaut, appeared to be stretched in an horizontal line. At length, 
 as he approached the earth, these vibrations were less extended, and continued 
 to diminish till he reached the ground, which he did without any injury to him- 
 self, or the apparatus, which he brought down with him, in a field near the 
 Small Pox Hospital, at Pancras. The balloon was observed to ascend rapidly 
 after separation from the parachute, and was soon out of sight. It has been 
 suggested to combine the parachute with the balloon so as to add nothing to the 
 bulk, and but little to the weight of the macliine ; it is as follows : The band 
 which divides the upper hemi- 
 sphere of the balloon from the 
 lower one, is to be formed of a 
 wooden hoop, to which the 
 net-work which covers the If 
 upper hemisphere, is to be|^ 
 firmly attached ; the cords =^ 
 which descend from this hoop, 
 are to be fastened together in 
 the usual manner, below the-_ 
 balloon, but not attached to =_ 
 the lower hemisphere ; now, if | 
 the upper hemisphere of the ' 
 balloon should burst, the gas 
 would escape, the balloon would 
 begin to fall, and the lower 
 hemisphere would immediately 
 fall into the direction here re- 
 presented, lining the upper 
 one, and forming a complete 
 parachute. Should the lower 
 part burst, the escape of the 
 gas would not be so sudden as 
 in the former instance ; but when it had escaped, and the balloon began to fali, 
 it would immediately form itself into the same shape as before : in this latter 
 case, it would, perhaps, be better to open the valve at the top, by which means 
 the balloon would sooner be formed into the shape of a parachute. This plan 
 has, perhaps, these advantages over the common parachute; viz. 1st. That of 
 taking up less room : 2d. Being less weighty : and 3d. Not being subject to 
 that great and sudden fall which must render the use of the common parachute 
 not only unpleasant, but extremely dangerous. 
 
 Mr. Green, who has made more than two hundred successful ascents, first 
 employed the ordinary coal gas, in lieu of hydrogen, or heated air, to gain tho 
 buoyant power. As the specific gravity of this is considerably greater than that 
 of hydrogen, it is necessary to employ a large balloon when coal gas is used. 
 Mr. Green's present balloon contains about 24,000 cubic feet. There is much 
 economy in using this substitute, as the cost price of sufficient coal gas does 
 not exceed twenty pounds ; but the expense of generating as much hydrogen
 
 j 3 8 BAMBOO. 
 
 gas as the balloon requires, amounts to nearly a hundred pounds. The latter 
 product of the distillation of coal, when the more valuable illuminating gas ia 
 evolved, answers the purpose best, as it contains much less carbon, and ip. con- 
 sequently, considerably lighter. The best material for constructing a balloon, 
 is the silk stuff called lustring. When cut into gores it should be stretched by 
 weights, or other means, and kept in this state several hours before it is var- 
 nished or sewn. It is usual to apply boiled linseed oil, containing a small 
 quantity of oxide of lead, for the first coat of varnish, and a solution of caout- 
 chouc (Indian rubber) in oil of turpentine, for the last. The seams should 
 be doubly sewn and overlapped; and, when finished, a hot smoothing-iron 
 should be passed over them, the silk being protected by an intervening sheet of 
 paper. The gores should be cut with great precision. A net-work of strong 
 hempen twine should be accurately fitted to the balloon, the meshes at the 
 upper extremity being smaller than those below. To the separate cords which 
 terminate the net-work, a circular hoop is attached, from which the car is sus- 
 pended by strong ropes. The whole of the net-work and ropes should be so 
 adjusted, that the strain, or pressure, is equalized over the whole surface of the 
 balloon. The valve for permitting the escape of gas must be retained in its 
 place by a sufficient spring ; and to render it perfectly air-tight, a luting of wax 
 and oil is generally employed around the edges. The cord by which the valve 
 is opened passes through the interior of the balloon ; and great care is neces- 
 sary to prevent it being entangled. The extremity of this cord should never be 
 fastened to the car, as in the event of its oscillation, the valve might be opened, 
 and retained in that state until the greater part of the gas escaped. A grap- 
 pling-iron, attached to a strong rope, is an indispensable appendage to a bal- 
 loon. As much ballast as can be taken should always be employed. It 
 frequently occurs that the aerial voyager is far above the clouds, and loses sight 
 entirely of the earth by their intervention ; on passing through them, he may 
 find that the spot on which he is descending is unfavourable. A few pound's 
 of ballast thrown out, will occasion the balloon again to ascend, and pass over the 
 inappropriate landing-place. The writer of this article was thus situated ; and 
 all the ballast being discharged, he was in imminent danger of descending in an 
 arm of the sea. A contrary current, near the surface of the earth, however, 
 gave the balloon another direction, when escape seemed almost impossible. 
 The appearance of the scenery below to an aeronaut is inexpressibly beautiful ; 
 but as a bird's-eye view only can be taken, no correct opinion can be formed of 
 the altitude of buildings, hills, or trees. On this account, much of the grandeur of 
 an extensive prospect is lost. The chief inconvenience experienced is from 
 the sudden variations of temperature. The upper regions of the atmosphere 
 are intensely cold when the sky is cloudless, even although the sun be shining in 
 meridian splendour. In an ascent made in August, when the thermometer was 
 74 in the sun at the time of ascent, the writer observed, in less than twenty 
 minutes, that the mercury indicated a temperature of 31. 
 
 BALLUSTRADE. A series, or row, of hallusters, joined by a rail, serving 
 both as a rest, and as a fence or enclosure, to stair-cases, balconies, &c. 
 
 BALSAMS are vegetable juices, either liquid, or which spontaneously 
 become concrete, consisting of a substance of a resinous nature, combined with 
 benzoic acid, or which are capable of affording benzoic acid, by being heated 
 alone, or with water. They are insoluble in water, but readily dissolve in 
 alcohol and ether. The liquid balsams are copaiva, opo-balsam, Peru, styrex, 
 and tolu; the concrete are benzoin, dragon's blood, and storax. 
 
 BALSAM OF SULPHUR. A solution of sulphur in oil. 
 
 BALDWIN'S PHOSPHORUS. Ignited nitrate of lime. 
 
 BAMBOO is a native of the hottest regions of Asia. It is likewise to be 
 found in America, but not in that abundance with which it flourishes in the old 
 world. It is never brought into this country in sufficient supply, though it is ad- 
 mirably adapted for many purposes. In the countries of its production, it is one of 
 the most universally useful plants, and of the most rapid growth, rising from fifty 
 to eighty feet the first year, and the second, perfecting its timber in hardness 
 and elasticity. It grows in stools which are cut every two years. Its young
 
 BANDANNAS 130 
 
 shoots and roots make an Indian pickle ; its light, graceful, knotted stalk, it 
 used in many articles of furniture for the rich ; and its timber forms almost 
 entire houses for the lower orders. The quantity of timber furnished by an acre 
 of bamboo is immense. Bridges, boats, masts, rigging, agriculture, and other 
 implements and machinery ; carts, baskets, troughs, pipes for conveying water, 
 pumps, fences for gardens and fields; tables, chairs, bedsteads, bedding, barrows, 
 fences, sacking, cordage, oakum, candle-wicks, whips, &c. are made of it. 
 Macerated in water it forms paper ; the leaves? are generally put round the tea 
 sent to Europe ; the thick inspissated juice is a favourite medicine. It is said 
 to be indestructible by fire, to resist acids, and, by fusion with alkali, to form a 
 transparent glass. In Malabar, the bamboos are trained over iron arches, and 
 when they have assumed the curve of the mould, are used for roofs to palan- 
 quins, and sell at five or six hundred rupees a set. 
 
 BAMBOO HABIT. A Chinese contrivance, by which a person who cannot 
 swim, may easily keep himself above water. Four pieces of bamboo, about a 
 man's length, placed horizontally, and at right angles, in parallel pairs, and 
 tied firmly at the four corners, the opening being just sufficient to admit the 
 head and shoulders to get through, is then tied securely to the body of the 
 person using it. 
 
 BANDANNAS. A name given to a certain description of silk handker- 
 chiefs manufactured in the East Indies, the patterns of which generally consist 
 of square or circular spots, variously arranged upon a red, blue, or yellow 
 ground. An imitation of these handkerchiefs upon cotton, produced by first 
 dying fine calico of a brilliant Turkey red, and after discharging the colour from 
 those parts which, in the pattern, are white, by means of liquid chlorine, now 
 forms a considerable branch of the cotton manufacture of this country, and an 
 important article for exportation. A correct account of this process will be 
 found in the following description of the great bandanna gallery, in the Turkey 
 red manufactory of Messrs. Monteith & Co. of Glasgow, who obtained a patent 
 for the process. Their new arrangement of their hydrostatic presses in theii 
 discharging gallery, was completed in 1818, under the direction of Mr. G. 
 Ridger, sen. manager of the works. It consists of sixteen of these engines, 
 beautifully constructed, placed in subdivisions of four ; the spaces between each 
 set serving as passages to admit the workmen readily to the back of the press. 
 Each subdivision occupies 25 feet ; hence the total length of the whole appa- 
 ratus is 1 00 feet. To each press is attached a pair of patterns in lead (or plates 
 as they are called) in which all those parts of the design which are to be white 
 are cut away, so as to form recesses in the plates. One of these plates is at- 
 tached to the upper block of the press, which block turns on a kind of universal 
 joint, so as to apply exactly to the under plate. The latter rest on the sill or 
 movable part of the press ; when this is forced up, the two patterns close on 
 each other with the greatest nicety, by guide pins at the corners fitted with the 
 utmost care. The power which impels this great hydrostatic range, is placed 
 in a separate apartment, called the machinery room. This machinery consists 
 of two cylinders of a peculiar construction, called the prime cylinder, having 
 pistons very accurately fitted to them. To each of these cylinders three small 
 force-pumps, worked by a steam engine, are connected. The piston of the 
 larger cylinder is 8 inches in diameter, and is loaded on the top with a weight 
 of 5 tons ; it can rise through a space of 2 feet. The piston of the other cylinder 
 is only 1 inch in diameter, and is, likewise, loaded with 5 tons, and can also rise 
 through a space of 2 feet. The pistons being at their lowest point, water is in- 
 jected by the force-pumps into the prime cylinders, until the loaded pistons have 
 arrived at their highest points, in which state they are ready for working the 
 hydrostatic discharge presses ; the water-pressure being conveyed from one apart- 
 mtnt to the other, through strong copper tubes of small calibre passing beneath 
 the floor. Two valves are attached to each press, one opening a communication 
 between the large prime cylinder and the press cylinder, and the other 
 between the small prime cylinder and the press. The function of the first is 
 simply to lift the under block of the press into contact with the upper block ; 
 that of the second, to give the requisite compression to the cloth. A third
 
 140 
 
 BANDANNAS. 
 
 valve is attached to the press for the purpose of discharging the water from its 
 cylinder, when the press is to be relaxed in order to remove or draw through 
 the cloth. From twelve to fourteen pieces of cloth previously dyed Turkey 
 red, are stretched over each other as parallel as possible, by a particular 
 machine. These parallel laytrs are then wound round a wooden cylinder, or 
 drum, which is then placed at the back of the press. A portion of the four- 
 teen layers of cloth, equal to the area of the plates, is next drawn through 
 between them, by hooks attached to the two corners of the web. On opening 
 the valve connected with the 8-inch prime cylinder, the water enters the 
 press cylinder, and instantly lifts its lower block, so as to apply the under 
 piate with the cloth close to the upper one. This valve is then shut, and the 
 other is opened. The pressure of 5 tons in the 1-inch prime cylinder is now 
 brought to bear on the piston of the press, which is 8 inches diameter. The 
 effective force here, therefore, will be 5 tons X 8=320 tons, to compress the 
 cloth between the plates. The next step is to admit the bleaching or discharg- 
 ing liquor (aqueous chlorine, obtained by adding sulphuric acid to the solution 
 of chloride of lime) to the cloth. This liquor is contained in a large cistern in 
 an adjoining house, from which it is run at pleasure into small lead cisterns at- 
 tached to the presses ; which cisterns have graduated index-tubes for regulating 
 the quantity of liquor according to the discharge pattern. The stop-cocks on 
 the pipes and cisterns containing this liquor, are all made of glass. From the 
 measure cistern the liquor is allowed to flow on to the surface of the upper plate, 
 and percolating through the portions of the cloth which lie under the open parts 
 of the pattern, it extracts the Turkey red dye. The liquor is finally conveyed 
 to the waste-pipe from a groove in the under block. As soon as chlorine liquor 
 has passed through, water is admitted in a similar manner to wash away the 
 remains of it ; otherwise, on relaxing the pressure, the outline of the figure 
 discharged would become ragged. The passage of the discharge liquor, as well 
 as of the water, is occasionally aided by a pneumatic apparatus, or blowing 
 machine, consisting of a large gasometer, from which air, subjected to a moderate 
 pressure, is allowed to issue and act in the direction of the liquid in the folds. By 
 an occasional twist of the air stop-cock, the workman can also ensure the equal 
 distribution of the discharging liquor over the whole excavations in the upper 
 plate. When the demand for goods is pressing, the air apparatus is much em- 
 ployed, as it enables the workman to double his product. The time requisite 
 for completing the discharging process, in the first press, is sufficient to 
 enable the other three workmen to put the remaining fifteen presses in opera- 
 tion. The discharger proceeds now from press to press, admits the liquor, the 
 air, and the water ; and is followed, at a proper interval, by the assistants, who 
 relax the presses, move forwards another square of the cloths, and then restore 
 the pressure. When the sixteenth press has been liquored, it is time to open 
 the first press. In this routine, about ten minutes are employed ; that is, 224 
 handkerchiefs (16 X 14) are discharged in ten minutes. The whole cloth is 
 successively drawn forward to be treated in the above method. When the 
 cloth escapes from the press, it is passed between two rollers in front, from 
 which it falls into a trough of water placed below. It is finally carried off to 
 the washing and bleaching department, where the lustre both of the white and 
 the red is considerably heightened. By the above arrangement of presses, 
 1600 pieces of 12 yards each=19,200 yards are converted into bandannas in 
 the space of ten hours, by the labour of four workmen. The following engraving 
 exhibits an elevation of one of the presses, a is the top of the entablature; 
 bbb cheeks of ditto, or pillars ; c upper block for fastening the upper pattern 
 to ; d lower or movable block ; e the cylinder ; / the sole or base ; g the water 
 trough for the discharged cloth to fall into ; h h tubes to admit the water ; i 
 tube for the air ; j cock to admit the liquor from the meter ; k cistern, or liquor-- 
 meter, having two glass tubes for indicating the quantity of liquor in the cistern; 
 / 1 glass stop-cocks for admitting the liquor into the cistern ; o o stop-cocks for 
 admitting water; pp pattern plates ; qq screws for setting the patterns parallel 
 to each other; the snuffs are perforated with a i-inch drill ; the lower frame has 
 pins corresponding with these perforations, so that the patterns are guided into
 
 BANDANNAS. 
 
 HI 
 
 exact correspondence with each other; r r rollers, which receive, and pull 
 through, the discharged cloth, from which it falls into the water trough ; s stop- 
 cock for filling the trough with water ; tt t waste tubes for water and liquor. 
 The patterns, or plates, which are put into the presses to determine the white 
 figures on the cloth, are made of lead, in the following way: A trellis frame of 
 
 
 cast iron, one inch thick, with turned-up edges, forming a trough rather larger 
 than the intended lead pattern, is used as the ground work. Into this trough is 
 put a lead plate, and firmly secured by screws passing from below. To the 
 edges of this lead plate, the 'borders of the piece of sheet lead which covers the 
 whole outer surface of the frame are soldered : thus a strong trough is formed, 
 about one inch deep. The upright border gives strength to the lead plate, and 
 serves to confine the liquor. A thin sheet of lead is now laid on the thick plate 
 of lead, and is soldered to it round the edges. Both sheets must be made very 
 smooth beforehand, by hammering them on a smooth stone table, and then 
 finishing them with a plane. The surface of the thin sheet (now attached) is 
 to be covered with drawing paper pasted down upon it, and upon this the 
 pattern is to be drawn. It is now ready for the cutter, who, in the first place, 
 fixes down with brass pins all the parts of the pattern which are to be left 
 solid. He then proceeds with the little tools used generally by block cutters, 
 which are fitted to the different curvatures of the pattern, and cuts perpen- 
 dicularly quite through the thin sheet. The pieces thus detached are easily 
 lifted out, and thus the channels are formed which design the white figures on 
 the red cloth. At the bottom of the channels a sufficient number of small 
 perforations are made through the thicker sheet of lead, so that the discharging
 
 142 
 
 BARK. 
 
 plates constitutes a set, which may be put into the presses, and removed at 
 pleasure. 
 
 BARILLA. A substance imported, in considerable quantities, from Spain, 
 and extensively used in soap-works, glass-works, and various other chemical 
 arts. It is obtained by the incineration of the salsola soda, a marine plant, 
 which is cultivated with great care in the neighbourhood of Alicant and Car- 
 thagena; that of Alicant is generally the most esteemed. An inferior species 
 of Barilla is also manufactured in many parts of North Britain, from the salsola 
 of Linnaeus, or common sea-wrack, and forms such an important article of 
 commerce, that it is said Lord Mac Donald, of the Isles, realizes 10,0001. a 
 year from his kelp shores alone, which his ancestors looked upon as of no value 
 whatever. The following account of the manufacture " on the farm of Strond, 
 in Harris" possessed in tack by Mrs. Anne Campbell, is taken from the Trans- 
 actions of the Highland Society of Scotland. " 1. The ware is cut off the rocks 
 with a common hook, similar to those used for reaping, but stronger, and having a 
 rougher edge. It is then landed on a clean spreading ground, and if any sand 
 or mud adhere to the weed, it is carefully washed before landing. The ware, 
 or weed, is then spread out every dry day, and made into small cocks at night ; 
 and when it is found to be pretty dry, it is made into larger cocks, and left to 
 heat for six or eight days; after which, a dry day, with a good breeze of wind, is 
 selected for burning it ; which operation is performed in kilns, constructed roughly 
 of middle-sized stones, the outside being covered with turf; the length of each kiln 
 is from 15 to 18 feet; breadth, 2 feet; and height, 2 feet. The process of 
 burning is as follows : A small bundle of straw, or heather, is set on fire ; the 
 driest part of the ware is placed over this, and gradually added until the flames 
 become general through the kiln ; then the ware to be burnt is tin-own in, little 
 by little, till the whole is reduced to ashes. If, however, it happens that the 
 day is too calm, or that the ware is not sufficiently dry, so that the ashes cool 
 and cake into white crusts, the manufacturer stops burning any more until he 
 rakes all the ashes out of the kiln ; he then commences burning again, and goes 
 on in this way until the whole is thoroughly burnt. The last process is the 
 raking or working of the ashes with an iron with a wooden handle, made for 
 the purpose, until the whole is brought into a vitrified state ; the mass is after- 
 wards broken into pieces of about 2 cwt., in which state it is ready for shipment. 
 BARIUM. A metal discovered by Sir H. Davy, in the earth barytes, in 
 which it is combined with oxygen, thus constituting a metallic oxide. The fol- 
 lowing is the mode of obtaining it : take pure barytes, make it into a paste with 
 water, and place it on a plate of platina. Form a cavity in the middle of the 
 barytes, and in it drop a globule of mercury. Touch the globule with the nega- 
 tive wire, and the platina with the positive wire, of a voltaic battery of about 
 100 pairs of plates in good action. In a short time, an amalgam will be formed 
 consisting of mercury and barium. This amalgam must be introduced into a 
 bent glass tube, filled with the vapour of naphtha, and the end must then be 
 hermetically sealed ; heat being applied to the received end in which the amalgam 
 lies, the mercury will distil over, leaving the barium, which is of a dark grey 
 colour, and of a lustre inferior to cast iron. Dr. Clarke asserts, that he obtained 
 metal by exposing pure barytes to the flame of the oxy-hydrogen blow-pipe, 
 but no one has since succeeded in the experiment, and it is generally believed 
 that the Doctor was mistaken, and that the globules which he formed, owed 
 their lustre and polish to the fusion the earth had undergone. 
 
 BARK. In Botany, the outer skin or covering of trees, the ingredients com- 
 posing which vary much in the different species, which are, accordingly, appli- 
 cable to various purposes of the arts. Some are highly medicinal, as Jesuit's 
 bark ; some are used for tanning leather, as the bark of the oak and Spanish 
 chesnut, &c. ; some in dyeing, as the bark of alder and walnut trees ; some 
 afford spices, as cinnamon, and cassia lignea ; and others are applicable to divers 
 uses, as the bark of the cork tree. The Japanese make paper of the bark of a
 
 BARKER'S MILL. 
 
 143 
 
 mulberry tree; and in Otaheite, a species of cloth is made from the bark of the 
 paper mulberry tree, of the bread-fruit tree, and of the cocoa-nut tree. 
 
 BARKER'S MILL. A simple and ingenious hydrostatic machine, invented 
 more than a century ago, by Dr. Barker, and forming one of the most simple 
 
 ii _i_j TAT i I__:.-A i i :_ A- 1,1 i 
 
 water mills ever constructed. 
 
 it has been warmly eulogized and recommende 
 
 hydraulics. In the annexed engraving, which is a perspective view of the machine, 
 
 It has been rarely introduced in practice, although 
 d by most writers on the subject of 
 
 a b represents a vertical axis, moving on a pivot at b, which would be best made 
 of steel, and to run in a brass step let into a block of stone, as at c ; this axis 
 passes freely through the lower mill-stone d, and is then fixed to the upper 
 stone e. To the axis is also fixed the large vertical tube g, the upper part of 
 which is expanded into the shape of a funnel or basin, for receiving the water 
 from the mill-course or pipe ; at the lower part g, this tube has an open com- 
 munication with the hollow horizontal arms A h, each of which has an 
 opening near its extremity on one side, and so adjusted by stop-cocks for 
 regulating the discharge, that the vertical tube shall always be kept full of 
 water, in order that the utmost force may be obtained, as a lateral pressure will 
 be exerted in all directions in the hori/ontal arms, proportionate to the altitude 
 of the column. Now this pressure being removed from the space forming the 
 area of the aperture of the arms, by the water being allowed to issue through 
 it, there will be an excess of pressure on the opposite side of the arm, in which 
 there is no pressure equal to the force with which the water would spout from 
 the aperture, were the machine fixed, and the water permitted to pass through 
 it. In the preceding form of Barker's mill, the length of the axis must always
 
 144 
 
 BARLEY. 
 
 exceed in height the elevation of the pipe i, which in some cases might render 
 the execution of such a machine difficult. To remove this difficulty, it was 
 proposed by M. Mathon de la Cour, in Rozier's Journal de Physique, for August, 
 1 775, to introduce the water from the mill course into the horizontal arms h h, 
 which are fixed to an upright spindle /, as represented in the annexed diagram, 
 and without any revolving vertical tube, as in the previously described arrange- 
 
 ment. The water will now obviously issue from the apertures at the extremities 
 of h h in the same manner as if it had been introduced at the top of the tube, 
 in the former figure ; hence the spindle may be made as short as we please. 
 The practical difficulty, in this arrangement, is to give to the arms h h a motion 
 round the mouth of the feeding pipe, which enters the arms without any great 
 friction, or any considerable loss of water. In this form of the mill, o is the 
 reservoir ; p the mill stones ; / the vertical axis ; q r s the feeding pipe, the 
 mouth of which enters the horizontal arm at s. In a machine of this kind, 
 constructed at Bourg Argental, the tubular arms h h were each 46 inches long, 
 and their inside diameter 3 inches ; each of the orifices 1 inch diameter, and 
 the height of the head of water above the points of discharge was 21 feet. 
 Though the fall was so great, the consumption of water was small, since it was 
 supplied by a 2-inch pipe ; and when the machine was not loaded, and had but 
 one orifice open, it made 115 turns in a minute. Thus a prodigious centrifugal 
 force is produced in the arms, and a corresponding velocity far exceeding that 
 of a simple fall of water with a pressure of 21 feet head. The machine, when 
 empty, weighed 80 Ibs., and it was half supported by the upward pressure of 
 the water. It is to be regretted that no extensive and accurately conducted 
 experiments have been instituted to determine the comparative powers of this 
 machine, and that great difference exists in the opinions both of theoretical 
 writers and practical engineers upon the subject. L. Euler, J. Bernoulli, and 
 A. Euler, consider it to be the most powerful of all hydraulic machines. Whilst 
 the Abbe Bossut reckons the overshot-wheel as upon the whole superior to it, 
 Mr. P. Ewart says, that " the effect of this mill is much superior to that of an 
 under-shot water wheel, consuming the same quantity of water, but inferior to 
 that of an over-shot wheel, in which the water is applied to the best advantage; 
 but Mr. Waring makes the effect to be equal only to that of a good under-shot 
 wheel, when driven by an equal quantity of water falling from the same height. 
 
 BARK STOVE is a kind of hot-house, containing a bed of tanners' spent bark, 
 mixed, according to circumstances, with a proportion of earth and other matters , 
 in which are placed the plants, in pots or otherwise. The bed is usually gently 
 heated from a flue underneath, which together with its disposition to ferment of 
 itself (when kept moist), forms a powerful stimulant to accelerate and perfect 
 the growth of exotic plants. 
 
 BARLEY. A well known kind of grain, chiefly used in this country in the
 
 BAROMETERS. 145 
 
 preparation of malt, for which see MALTING. The meal is also used in bread 
 and soups. Whiskey, gin, and other spirits, are distilled from it. The barley- 
 sugar of the shops is merely sugar boiled in barley-water to a consistency that 
 will cause it to solidify in the cold state ; it is poured upon a stone slab, anointed 
 with oil of sweet almonds, rolled out into little cylinders, and twisted. 
 
 BARM, or YEAST, is a substance which separates under the form of a froth, 
 more or less viscid, from all the juices and infusions which experience the 
 vinous fermentation. It is commonly procured from the beer manufactories, 
 and is hence called the barm of beer. If left to itself for some days, in a close 
 vessel, at a temperature of from 55 to 70, it is decomposed, and undergoes 
 the putrid fermentation. To prevent this decomposition, it is the custom, in 
 Paris, to evaporate it to a solid form, in which state it is sold under the name 
 of levure, which article, however, comprises not only yeast, but the bottoms 
 of the beer in the working-tun and store-casks. This is purchased by the yeast 
 merchants, the beer drained from it through sacks, and the remainder of the 
 beer washed out by putting the sacks in a stream of water; the solid matter 
 left in the sacks is then dried in the open air. The tme yeast, or froth of the 
 beer, is also dried for use in the same mar.ner, as the bakers in Paris prefer it in 
 a solid state. Dry levure ought to be yellow, brownish, or greyish white, by no 
 means black or bitter. It should not yield to pressure by the fingers, and be 
 equally dry throughout, so as to break with a smooth surface. When dissolved 
 in hot water, and a few drops of the solution are poured into boiling water, 
 they should immediately rise to the surface. See BEER, and BREAD. 
 
 BAROMETER. An instrument by which the pressure or elasticity of the 
 air is ascertained. It consists essentially of a glass tube, not less than 34 inches 
 in length, closed at one end. The tube is completely filled with mercury, and 
 then inverted in a cup or box of the same metal. By inverting the tube, a 
 portion of the mercury will fall out, but a column varying in height from 28 to 
 31 inches above the surface of the metal will still remain, and which, being 
 supported by the pressure of the air, will be an indication of its amount at the 
 time. The barometer has assumed a variety of forms, the construction of the 
 most important of which we shall endeavour to explain ; but we deem it neces- 
 sary, previously, to enter a little more minutely into the nature and operation of 
 that form of the instrument to which we have just referred. The common baro- 
 meter was the discovery (for it can scarcely be called an invention) of Torricelli, 
 a disciple of the celebrated Galileo. It is, from this circumstance, frequently 
 called the Torricellian tube ; and the vacuous space above the surface of the 
 mercury in the tube, is called the Torricellian vacuum. In the construction of 
 the barometer, the principal object to be attained is a perfect vacuum in the 
 upper part of the tube. To effect this, we must first make the tube perfectly 
 free from moisture by exposing it gradually to the heat of a charcoal fire. The 
 tube must have a bore sufficiently large to render the effect of capillary attraction 
 insensible. The mercury employed to fill the tube must be rendered as pure 
 as possible, by pressing it through the pores of chamois leather, and afterwards 
 distilling it. A small portion of the purified mercury may now be put into the 
 tube, and heat gradually applied to it, till the mercury boils. Another portion 
 may then be added, and boiled in a similar manner ; and this process continued 
 till the tube is completely filled. By these means, the mercury itself will be 
 purged of any air it may have acquired, and the air which adheres to the sides 
 of the tube will also be effectually expelled. If the tube be now inverted into 
 a cup or other vessel of mercury, the barometer, as far as its construction is 
 concerned, will be complete. In the annexed cut, a c represents the barometric 
 tube inverted in its cup. The mercury has subsided to the point /; and the 
 next object is, to ascertain the precise length of the column from c to /. For 
 this purpose, a scale a b is attached to the barometer near the top. In the 
 ordinary use of this instrument as a weather-glass, the rise and fall of the mercury 
 seldom exceeds a range of 3 inches, the height of the column varying with 
 the atmospheric pressure from 28 to 31 inches. If, therefore, a scale of about 
 4 inches long, carefully graduated to tenths of an inch, be attached at the height 
 that accords with the number of inches we have mentioned, it will be sufficient to
 
 11( j BAROMETERS. 
 
 determine the ordinary changes of atmospheric pressure. There is, 
 however, one circumstance to which it is necessary to attend, in 
 measuring the height of the mercurial column. It will be seen, 
 that as the column fc falls, it will necessarily raise the level of the 
 fluid in the cistern ; and contrariwise, when the column rises, it will 
 depress the level of the cistern. On this account, the initial point of 
 the scale is perpetually changing its position, and, consequently, the 
 numbers on the scale cannot indicate the true distance between the 
 surface of the mercury in the cistern and that of the supported column. 
 To obviate this inconvenience, the horizontal sectional area of the 
 cup is made considerably greater than a like section of the tube, 
 by means of which a considerable fall in the tube produces but an 
 inconsiderable alteration in the level of the fluid in the cup. For 
 example, if the diameter of the tube be of an inch, and that of the 
 cup be 2 inches, the respective areas will be as ^ to 4, or as 1 to 
 64 ; hence a fall of I inch in the tube will cause a rise of g of an 
 inch in the cup. In ordinary observations, this degree of accu- 
 racy would be sufficient ; but in the nicer operations of science, a 
 greater degree of precision is essential ; hence different contri- 
 vances have been employed for the purpose of ascertaining more 
 exactly the difference of levels. The most general mode of 
 effecting this object is to make the bottom of the cistern movable, 
 so as to be raised or depressed by means of a screw e. An ivory 
 index d may be attached to the top of the cup, and which being 
 finely pointed at the lower end, will serve to indicate a fixed level. 
 Before an observation is made with the barometer, the screw e is 
 turned until the surface is brought exactly to coincide with the poin t of the index, by 
 raising or depressing the bottom according as the surface was below or above that 
 point. By this means, the surface of the mercury always stands at the same level, 
 and hence the divisions on the scale a b will represent the actual changes in the 
 height of the barometric column. Having attained a method of fixing the initial 
 point of the scale, the next object to be attained is a means of reading offits indica- 
 tions with the utmost precision. In our description, we have supposed the scale 
 divided into tenths of an inch, but this is not sufficiently accurate for experimental 
 research. It would therefore be necessary to divide each of these tenths into hun- 
 dredths of an inch, and adapt a small microscope to the instrument, in order to 
 obtain the precise height of the column. The usual mode, however, of obtaining 
 these smaller subdivisions of the scale, is by means of a vernier, or small gra- 
 duated plate, which is movable by a screw, or otherwise, on F - 2 
 the divided scale of the barometer. The principle of the ver- 
 nier will be seen by reference to the accompanying engraving. 
 Let ab represent a portion of the scale divided into tenths of 
 an inch ; let c d be the sliding scale, or vernier, equal in 
 length to 11 divisions on the principal scale, but divided 
 into only 10 equal parts. From this arrangement, it will be 
 seen that every division on the vernier will be the tenth part 
 of 11 tenths of an inch, or every division is equal to 11 
 nundredths of an inch, and, consequently, every division on 
 the vernier exceeds, by one hundredth of an inch, every 
 division on the principal scale. Suppose the vernier placed, 
 as in the diagram, so that its upper edge d may be exactly 
 even with the surface e of the mercury in the tube. If we 
 examine the principal scale, we shall perceive that the mer- 
 cury stands somewhat higher than 29 inches and 4 tenths. 
 If we now look at the vernier, we shall find that the divi- 
 sion 4, on its surface, coincides with a particular division on 
 the scale. Now, as we have seen that each division on the 
 vernier is one hundredth of an inch greater than one division 
 on the scale, it follows that the space from 29 up to the level 
 of the mercury, is 4 tenths and 4 hundredths of an incb
 
 BAROMETERS. 
 
 and, consequently, the true altitude of the column 
 is 29 inches, 44 hundredths. In using the vernier, 
 considerable precision must be employed in making 
 its upper edge a tangent to the curved surface of the 
 mercury in the tube, and, consequently, its accuracy 
 will still depend upon the skilful manipulation of 
 the observer. To obviate this, and render the baro- 
 meter self-regulating, Mr. Christie, Secretary to 
 the London Mechanics' Institution, has invented 
 and constructed a barometer, in which, by means 
 of a float, the vernier is set at its proper height 
 by the rising or falling of the mercury itself. 
 The annexed sketch will show in what the 
 improvement consists. Here a b c represents a 
 glass barometer tube about 35 inches long, exclu- 
 sive of the part b c. It is not less than a quarter 
 of an inch diameter inside, and enlarged at the 
 top a to about two inches. On the surface of the 
 mercury, shown by the shading, rests a small glass 
 ball, or float d, supporting a slender steel wire, d e 
 with its attached vernier/. This wire passes loosely 
 through a guide hole in the projection g to keep it 
 close to the scale of inches h i. In other respects, 
 the scale and vernier are similar to those of the 
 common barometer. The upper part of the en- 
 larged tube being vacuous, the mercury is pre- 
 vented from descending by the pressure of the 
 atmosphere on the surface at d ; and as the pres- 
 sure increases, it will force down the mercury in 
 the part c b of the tube, and, consequently, cause 
 it to rise in the leg a b. As the surface at d falls, 
 the float carrying the vernier falls with it, and thus 
 the edge of the vernier being always kept at a 
 given distance from the surface of the mercury, 
 will indicate the precise amount of any changes 
 that may occur in atmospheric pressure. 
 
 In order to increase the extent of the baro- 
 metric changes, a contrivance is sometimes adopted, 
 called the diagonal barometer, which is represented 
 in Fig. 4. b c d is the glass tube bent at c, the 
 altitude of which is less than 28 inches ; hence c b 
 includes the whole barometric range in the present 
 form, while a c is the range it would have were 
 the whole of the tube vertical. Now it is mani- 
 fest, that by decreasing the angle at c, so as to 
 bring b c nearer the horizontal position, we can 
 make its proportionate length to a c as great as we 
 please. Suppose b c so inclined that its length 
 shall be three times greater than a c, then every 
 rise or fall of 1 inch in a c would be equivalent 
 to a rise or fall of 3 inches in b c. The difficulty, 
 however, of observing the precise height of the 
 mercury in this arrangement, more than counter- 
 balances the advantage resulting from the extended 
 range, and this form is, therefore, seldom adopted. 
 
 The wheel barometer is another contrivance for 
 enlarging the scale, and rendering minute changes 
 more easily observed. This, which is the common 
 domestic barometer, is represented in Fig. 5, in which 
 d b is the longer leg, a b the shorter, in which the 
 
 147 
 
 Fig. S. 
 
 Fig. 4.
 
 148 
 
 BAROMETERS. 
 
 Fig. 5. 
 
 changes of altitude occur : for as the diameter of the 
 bulb d at the top is very large, compared with the 
 diameter of the tube at c, a small fall in d will be 
 equivalent to a considerable rise in the tube a b. Thus 
 the surface at c may rise 3 inches, and thereby 
 shorten to that amount the distance between the two 
 surfaces of the column, which is the true height sus- 
 tained by atmospheric pressure, without sensibly af- 
 fecting the level at d. At c there is an iron ball, 
 floating on the surface of the mercury, and partly 
 supported by means of a thread passing over the 
 pulley^), and carrying a small counterpoise at w. On 
 the axis of the pulley, an index i is fastened, which 
 moving with it, branches the circumference of the 
 circular plate, on which a scale is drawn, to repre- 
 sent the rise or fall in inches ; and also the terms 
 fair, change, rain, fyc., which certain altitudes have 
 'been improperly considered to indicate. In this 
 arrangement, it is manifest that as the column is 
 supported by the air's pressure on the surface c, 
 any diminution of that pressure will cause the mer- 
 cury in the longer leg to fall, and that in the shorter 
 to rise. On the other hand, if the atmospheric 
 pressure increases, the mercury will rise in the 
 longer, and fall in the shorter, leg ; but, as before 
 observed, the change of level will be scarcely per- 
 ceptible in the former, on account of the enlarged diameter of the upper part. 
 The changes, then, that occur in the shorter leg, may, without material error, 
 be considered the representatives of the changes that are continually occurring 
 in the atmosphere. Now it will be evident, on inspection, that as the ball c is 
 partly supported by the mercury, it will partake of its motion. If the pressure 
 of the air increase, the surface at c will be depressed, and as the iron ball must 
 sink with it, the thread to which it is attached will, at the same time, communicate 
 its motion to the pulley p, and through it, to the index, which will, consequently, 
 move from the right towards the left of the graduated circle. On the other 
 hand, if the atmospheric pressure decrease, the surface at c will rise, and, with 
 the assistance of the counterpoise w force up the iron ball, and, by this means, 
 turn the pulley and index in an opposite direction. There are two sources of 
 error in this instrument, that render it inferior to the simple vertical barometer. 
 These are, the pressure of the iron ball on the surface of the mercury, which 
 necessarily increases the height of the shorter column, and the friction of the 
 pulley. It is impossible entirely to annihilate these causes of error, and hence, 
 for philosophical purposes, the straight barometer is preferred. 
 
 The Syphon Barometer is an instrument used 
 to ascertain the pressure of air in the partially 
 exhausted receiver of an air-pump. It consists 
 of a tube bent as in the accompanying engrav- 
 ing, Fig. 6. Each leg may be about 4 inches in 
 length, and one a b completely filled with puri- 
 fied mercury. When the instrument is con- 
 nected with the air-pump by means of the screw 
 at d, and the air partly exhausted, the mercury 
 in the leg a b will begin to fall, and, conse- 
 quently, rise in the branch c b ; every inch, 
 therefore, that it falls in a b, must be reckoned 
 equal to two inches in the straight barometer. 
 This instrument does not begin to act till the 
 air is reduced to about 1 of its original density ; 
 but this is no inconvenience, as its indication 
 eilia istion is nearly complete. If the leg 
 
 Fig, 6. 
 
 are seldom required till \tlie 
 b be lengthened, and left open at the
 
 BAROMETERS. H9 
 
 lop, as in Fig. 7, this barometer becomes a useful appendage tc the steam 
 engine, in ascertaining the pressure of steam within the boiler. When it is 
 attached to the boiler by the screw d, and the air or steam in the boiler has 
 the same elasticity as the external air, the mercury stands at the same height in 
 both legs ; but as soon as the steam increases in elasticity, the mercury will be 
 depressed in the leg c b, and rise in a b, and the difference between the two 
 levels will be proportional to the difference between the external and internal 
 pressure. If the common barometer stands at 30 inches, and the difference of 
 level between the two surfaces is 6 inches, the elasticity of the steam will be 
 jj or ~ greater than the pressure or elasticity of the atmosphere. 
 
 There are other forms of the barometer, but their comparative unimportance 
 renders it unnecessary to describe them here. We shall, therefore, proceed to 
 consider the most important purposes to which this instrument is applied. 
 
 The most immediate use of the barometer, for scientific purposes, is the ascer- 
 tainment of the amount and variation of atmospheric pressure. The fluctuations 
 in the pressure being observed in connexion with changes in the state of the 
 weather, a general correspondence is supposed to prevail between these effects. 
 The instrument has, from this circumstance, been called a weather glass. Rules 
 have been attempted to be established, by which the approaching state of the 
 weather may be predicted from the height of the mercury, and the words rain, 
 fair, changeable, &c. are engraved on the scales of common barometers. These 
 marks are, however, entitled to no attention, since it is the changes that occur 
 in the height, and not the absolute height, that indicates approaching changes, 
 in the weather. The variation in the altitude of the barometer in a given place, 
 together with the corresponding changes of the weather, have been regularly 
 recorded for a considerable time ; and it is by an exact comparison of these 
 results that general rules are to be found*- At present, the best rules are liable 
 to some uncertainty at times. Those which have been considered least liable to 
 error are the following: 1. Generally, the rising of the mercury indicates fair 
 weather ; its fall shows the approach of foul weather. 2. In sultry weather the 
 fall of the mercury indicates coming thunder. In winter, a rise indicates frost. 
 In frost, its fall indicates thaw, and its rise indicates snow. 3. Whatever change 
 of weather suddenly follows a change in the barometer, may be expected to last 
 but a short time. Thus, if fair weather follow immediately the rise of the mer- 
 cury, there will be very little of it ; and in the same way, if foul weather follow 
 the fall of the mercury, it will last but a short time. 4. If fair weather con- 
 tinue for several days, during which the mercury continually falls, a long suc- 
 cession of foul weather will probably ensue ; and again, if foul weather continue 
 for several days, while the mercury continually rises, a long succession of fair 
 weather will probably succeed. 5. A fluctuating and unsettled state in the mer- 
 curial column indicates changeable weather. The other important purpose to 
 which the barometer is applied, is the measurement of altitudes. If the atmo- 
 sphere were a liquid of nearly equal density, like water, the measurement of 
 heights by the barometer would be the simplest process imaginable : for we 
 should have then only to make one experiment to ascertain how much the mer- 
 cury would fall, in rising to the height of 100 feet for example, and then the fall 
 for 200 or 300 feet would, of course, be double or triple the former one. But 
 the density of air is well known to decrease as we ascend from the earth, so 
 that at the height of 3J miles, it is only one half its density on the surface of 
 the earth. From this it must be evident that if the mercury fall one-tenth of an 
 inch in rising through the height of 100 feet, we must rise through a greater 
 height to cause a fall of another tenth. The height of the surface of the atmo- 
 sphere above that of the earth is considered to be about 50 miles ; and we have 
 already observed, that at the height of 3J miles the density is reduced to one- 
 half. Hence we should find, by ascending to the height of 3$ miles in the 
 atmosphere, the mercury would stand at one-half the height of another 
 barometer at the surface of the earth. If, however, the decrease of density 
 were affected by the height alone, the determination of altitudes would be com- 
 paratively easy, as a simple formula may be given, which would immediately 
 how the relation between the height and density. The circumstance that 
 
 u
 
 150 BARREL. 
 
 interferes with barometric observations, is temperature, which affects them in 
 two ways. 1. Increase of temperature expands the mercury in the barometer, 
 and thereby causes the column to be longer than at lower temperatures. 2. 
 The air itself becomes expanded by heat; and hence the column becomes 
 lengthened without any increase in its absolute weight. It might be thought 
 that these effects were too trivial to influence sensibly the results of our obser- 
 vations; but it must be remembered, that as we ascend from the earth, the 
 temperature of the air rapidly decreases, so that at a certain height, dependent 
 on the latitude of the place, a freezing temperature constantly prevails. 
 Putting aside the effect of change of temperature, the simplest rule for deter- 
 mining heights is as follows: Observe the height of the mercury at the 
 bottom and top of the altitude to be ascertained ; take the logarithms of these 
 heights, and multiply their difference by 10,000, the product is the answer in 
 fathoms. Then suppose the mercury at the foot of a mountain to stand at 29,5 
 inches, and at its summit 26.4 inches, the calculation would be as follows : 
 
 Lower barometer. . . 29.5 log. .469822 
 
 Upper ditto 26.4 log. .421604 
 
 Difference .048218 
 
 10000 
 
 482,180,000 Fathoms, 
 or, 2893 feet, 
 
 which is the altitude, supposing the temperature to be at 31 Fahr. If the 
 temperature differ from this, it must be observed at the upper and lower station, 
 and a mean of the two taken, by adding them together, and dividing the sum 
 by 2. If the mean thus obtained exceed 31, the altitude before obtained must 
 be increased ^ for every degree of difference between them, and vice versa. If 
 we wish to correct the other error arising from the expansion or contraction of the 
 mercury in the barometer, we must observe the temperature of the mercury at the 
 upper and lower station ; then the altitude of the lower one must be increased, o^ 
 the higher one diminished, ^_ part for each degree of difference between their 
 temperatures. To those who are unaccustomed to the use of logarithms, the fol- 
 lowing rule may be preferred : Take the sum and difference of the upper and 
 lower barometric heights, and divide one by the other ; multiply the q-aotient by 
 55000, and it will then answer in feet for a temperature of 55. Suppose, as 
 before, the height at the lower station to be 29.5, and at the upper, 26.4 then 
 29.526.4 
 
 = 0554 
 
 29.5 + 26.4 
 
 And .0554 X 5500 = 3047 feet. 
 
 This result, it will be seen, exceeds the other by 154 feet; it is not so exact, 
 but, in many cases, it may serve to furnish a tolerable approximation, when 
 logarithmic tables are not at hand. The corrections for temperature may be 
 applied as in the other formula. 
 
 BAROSCOPE. An instrument for shewing the weight of the atmosphere, 
 frequently confounded with the Barometer : the former, however, only proves 
 that the atmosphere has weight; while the latter determines its true quantity. 
 
 BARREL. This article, as made by coopers, is too well known to need a de- 
 scription; but the air and water-tight metallic barrels employed in the British navy 
 for preserving provisions, from their peculiarity of structure and utility, require a 
 place in this work. Those which we shall describe are of the most improved 
 kind, and were patented by the late Mr. Robert Dickenson, of the Eagle Foundry, 
 Southwark. These barrels are made of wrought iron, of a cylindrical form, 
 with a seam, soldered or rivetted, in the usual way. To strengthen the figure, 
 and adapt it for the reception of the heads, a strong iron hoop is rivetted to 
 each end of the cylinder. These hoops are prepared at the iron works, by 
 rolling them into the form of a rebate, shown in section at b, Fig. 1. By this 
 diagram it is also shown that the hoop is fastened with its thickest part against 
 the side of the ban-el a, about an inch below the extreme edge of the same: 
 thus forming a deep groove between the sides of the barrel, and the thinnest
 
 BARREL. 
 
 part of the rebated hoop, for the reception of the flange of the head e, which 
 appears to be made by bending the periphery of the circular iron plate to a right 
 
 Fig. 1. 
 
 Fig- 2. 
 
 angle with its plane. Previous to the driving down of this head, a sort of pack- 
 ing, composed of hemp-bands, or currier's leather-shavings, is to be rammed 
 into the groove, so as effectually to exclude both air and moistufe. To secure 
 the bottom head in its place, the thin projecting edge of the hoop is to be ham- 
 mered down upon the bottom, and over this is to be rivetted a flat iron ring, to 
 serve the purpose of the ordinary chimes of barrels, the exterior edge of which 
 should extend a little beyond the periphery of the cylinder, to defend the sides 
 of the barrel in rolling it. The upper head of the barrel is so constructed as to 
 be removable at pleasure, the hoop which circumscribes it being the same as 
 that on the bottom ; but, instead of being hammered down, it is left erect, as 
 shown at fig. 2. The head is placed also within a similar groove, and is fastened 
 down by means of a number of latch-bolts. These latch-bolts are attached to 
 the head, or movable cover, by means of a pivot at one end, upon which they 
 turn, and are driven sideways into long slots made through the projecting hoop, 
 which slots are not made in a parallel line with the top of the cask, but aslant, 
 so that when the latch-bolts are driven into them by a hammer, they draw the 
 flanged head into the deep groove, which, being previously packed in the 
 manner before-mentioned, makes the junction perfectly air and water-tight. 
 This kind of cover, likewise, admits of its being very readily removed, by 
 driving back the latch-bolts with a hammer ; and the inconvenience formerly 
 experienced in the smallness of the apertures in air-tight vessels, is herein com- 
 pletely removed, the opening being as wide as the barrel itself, so that larger 
 matters may be stowed in it, and the packing and removing of the contents 
 greatly facilitated. Metal casks, heretofore employed for similar purposes, were 
 usually coated with paint to prevent oxidation, and render them water-tight, 
 which was found to communicate a bad flavour to the flour, biscuit, or other 
 materials which they contained. To remedy this inconvenience, the patentee 
 coats the barrels, both inside and outside, with any of the well-known water- 
 proof compositions, which, while they effectually prevent oxidation, will not 
 communicate any unpleasant taint to the articles of food, even in the hottest 
 climates. The patentee has selected the following : To 1 pound of caoutchouc 
 (Indian rubber) add 8 oz. of black resin, and 2 oz. of Venice turpentine; let 
 the caoutchouc be cut into small pieces, and expose the mixture to a heat of 
 160 for the space of 24 or 36 hours. When dissolved, it is to be spread upon 
 canvass, or other fibrous material, and then passed between cylindrical rollers 
 to give it an even consistency. With this material the ban els are to be coated 
 both within and without, except in the case of dry goods, such as biscuits, 
 flour, &c., when the coating of the exterior alone is considered sufficient, and 
 the interior surface of the iron may be bronzed in the same manner as gun- 
 barrels. For oils, tar, varnish, &c. the insides of the barrels have no coating, 
 those materials being, of themselves, preservatives against oxidation. In some 
 cases of dry gopds, the inside may be coated with the thinnest and cheapest 
 woven material, or even paper ; and these may be attached, by any cheap kind 
 of cement, that will effectually exclude the air and moibture.
 
 152 
 
 BARROW. 
 
 BARROW. A machine for carrying loads by manual labour. Barrows 
 are of two classes : hand-barrows, and wheel-barrows. Hand barrows consist 
 merely of a small platform attached to two poles projecting equally from each 
 end, and carried by two men in the manner of a sedan chair. Wheel-barrows 
 are made of various 
 forms, widely dif- 
 fering from each 
 other, to suit the 
 particular work for 
 which they are 
 intended, as ex- 
 cavator's barrows, 
 brickmaker's bar- 
 
 rows, &c., but all 
 of them are con- 
 structed with a single wheel in front, and two 
 handles behind. Barrows are an advantageous 
 mode of employing the power of men ; accord- 
 ing to Coulumb, a man with a barrow will do 
 half as much more work as he can do with a 
 hod. The longer the arms of the barrow, the 
 less is the labour of wheeling it. A great 
 improvement has been made in wheel-barrows, 
 by the addition of two long leaf-springs, in the 
 outer end of which the pivot of the wheel 
 turns, instead of being carried by stiff inflexible 
 arms, as heretofore. In the construction of 
 docks, canals, embankments, &c , one very 
 great portion of the labour consists in raising 
 the earth from a lower to a higher level, and 
 this is mostly done by barrows ; but the common 
 mode of barrowing, by which one man is drawn 
 almost vertically up an inclined plane, along with 
 a loaded barrow, whilst another man descends a 
 similar plane with an empty barrow, is extremely- 
 dangerous, many men having lost their lives, or 
 having been seriously injured by it. In the 
 following plan, invented by Mr. Matthews, and 
 which has been rewarded by the Society of 
 Arts, by an honorary gold medal, these evils 
 are entirely avoided, as the burrows are alter- 
 nately drawn op and let down without an 
 workman accompanying them, a a is a plank 
 10 or 11 inches wide, laid at a small angle suf- 
 ficient to keep the barrow-wheel in contact 
 with it, and two strips b b are spiked to the 
 edge of the plank, so as to form a groove for 
 the wheel of the barrow to run in ; two pieces 
 of quartering, or small spars c c, are fixed on 
 each side, at a proper distance, to guide the 
 handle, by which the barrow is kept in a 
 proper position against the plank upon which 
 the wheel runs; about 10 or 15 feet from the 
 top of the plank, i'lv-i v i . <cr T- 
 
 4 *? f ? r>^^/^Tn 
 
 where the load- , ""^ ^ "* ^ _Jl_^ 
 ed barrow is to 
 land, a pulley 
 d is fixed to a 
 pole e, through
 
 BASKET. US 
 
 which the rope, or chain, is passed down to the barrow ; to the end of the rope 
 is fastened a hook, which goes into an eye /fixed upon the point of the barrow. 
 A pair of slings are slid upon the handles of the barrow, previously fastened 
 upon the rope at a proper distance, to keep the barrow in a right position to be 
 drawn up the plane, or plank, which is when the handles of the barrow are a 
 little below the horizontal line with the wheel of the barrow while running up 
 the plank. The rope, after passing over a pulley d, passes through another 
 leading pulley g, at a proper height to suit the draft of a horse, and is con- 
 nected to a similar apparatus at another inclined plane, situated at a distance 
 from the former, somewhat exceeding the length of the planes on which the 
 barrows run. A horse is attached by a rope to the middle of the horizontal 
 part of the rope g g, and alternately traversing between the two stations, raises 
 a loaded barrow at one station, or plane, whilst an empty one descends at the 
 other, unaccompanied by a man. The pulley d is elevated so high as to let the 
 rope from the barrow clear the bank, and yet incline so much inward that the 
 barrow clears the bank as it swings in, and lands itself as shown by the dotted 
 lines. The man has only to fix the ropes to the empty barrow, and wheel the 
 full one away. 
 
 BARYTES. An alkaline earth, most commonly found combined with sul- 
 phuric acid, forming sulphate of barytes, or heavy spar. The experiments of 
 Sir H. Davy show barytes to be an oxide of a metal to which he gave the 
 name of Barium, which see. See also CHEMISTRY. 
 
 BASALTES, in Natural History, a heavy hard stone, most commonly black, 
 or greenish, consisting of prismatic crystals, the number of whose sides is uncer- 
 tain. It is distributed over the whole world, but nowhere exists in greater 
 variety than in Scotland. A celebrated range of columnar basalt exists in 
 Ireland, and is known by the name of the Giant's Causeway. It consists of 
 three piers of three columns, which extend several hundred feet into the sea. 
 These columns are, for the most part, hexagonal, and fit very accurately 
 together, but, generally not adherent to each other, although water cannot 
 penetrate between them. Basaltes, when calcined and pulverized, forms a 
 good substitute for puzzolana, in the composition of hydraulic cement, having 
 the property of hardening under water ; and it has also been converted into 
 glass, from which wine bottles have been manufactured. 
 
 BASE is a term usually applied to the lowest part of any thing ; thus, in 
 Geometry, it is the lowest side of the perimeter of a figure ; in Architecture, 
 the lowest part of a column, or pedestal ; in Building, the lowest apartment is 
 also called the basement. 
 
 BASE, in Surveying, is a line measured with the greatest exactness, on which 
 a series of triangles are constructed, in order to determine the position of objects 
 and places. 
 
 BASE, in Chemistry. Any body which is dissolved by another body, which it 
 receives and fixes, and with which it forms a compound, may be called the base 
 of that compound. Thus, for example, the base of neutral salts, are the alka- 
 line, earthy, and metallic matters, which are saturated by the several acids, and 
 form, with them, these neutral salts. 
 
 BASKET. A fabrication woven of straw, rushes, canes, and other elastic 
 materials ; but, in this country, principally of willow ; which last, according to 
 their growth, are called osiers and sallows. Osiers for white work are deprived 
 of their bark by an instrument called the braker, and afterwards are cleaned 
 by a common knife. They are then exposed to the sun and air in order to dry 
 them thoroughly ; after which they are housed, and kept carefully from mois- 
 ture, which, if attended to, will preserve them for years. The same precautions 
 against moisture are necessary for preserving osiers with their bark on. When 
 these osiers are intended to be used, they are soaked for a few days, according 
 to their age and dryness. Osiers deprived of their bark are assorted by the 
 basket- maker into large and small rods, according to the work for which they 
 are intended ; the larger ones forming the slat and skeleton of the basket, and 
 the smaller ones for weaving the bottom and sides. For common work, such as 
 clothes-baskets, market-baskets, &c., the rods are used whole ; but, for the finer
 
 154 BATH. 
 
 work, as table-mats, fruit and work baskets, and the like, the osiers are divided 
 into four parts, lengthways, which are called splits, and these are afterwards 
 reduced to various degrees of fineness, when they are called skeins. The 
 method of making a basket of the ordinary kind is as follows : The workman 
 having cut off the large ends of as many osiers as he deems necessary, and of 
 a length somewhat more than the width of the bottom, lays them on the floor 
 in pairs, all ranging the same way ; he then places on them two of the longest 
 osiers, with their largest ends towards him, crossing the direction of the former; 
 on the large ends of the two long osiers he places his foot, weaving each alter- 
 nately under and over the short ends, which confines them in their places, and 
 forms whut is called the slat, or slate, which is the foundation of the basket. 
 He next takes the long end of one of the two rods, and proceeds to weave it 
 under and over the pairs of short ends all round the bottom, until he has wove 
 the whole of it; this is, likewise, done with the remaining osier, and after this 
 is exhausted, other long osiers are wove in, until the bottom is of a size sufficient 
 for the intended basket. The workman next proceeds to sharpen the ends of as 
 many long and stout osiers as may be necessary to form the ribs, or skeleton of 
 the basket ; the sharpened ends are planted, or forced, between the rods of the 
 bottom, and are turned up in the direction of the sides, and the other rods are 
 woven in and out, between each of the uprights, until the basket is raised to 
 the intended height. To finish the edge, or brim of the basket, the ends of the 
 ribs, which are now standing up perpendicularly, are turned down over each 
 other in a manner easily understood by inspecting a basket, although difficult 
 to describe. There remains only to add the handle ; this is done by planting 
 or forcing down close to each other, between the weaving of the sides, two or 
 three osiers, cut to a proper length ; when in their place, a hole is made through 
 them, about two inches from the brim, into which a pin is put, to prevent their 
 being drawn out; they are then covered, or bound together with skeins, some- 
 times of various colours, forming different kinds of platting on the handle. 
 Basket-work is well adapted to many other purposes than those to which it is 
 at present applied, as it combines, in an eminent degree, the three qualities of 
 strength, lightness, and elasticity. 
 
 BASSOON, a musical wind instrument, blown with a reed, furnished with 
 eleven holes, and used as a bass to hautboys, flutes, &c. 
 
 BASSOR1NE. A name given to a substance which is extracted from the gum 
 resins, by successively treating them with water, alcohol, and ether. The bassorine 
 being insoluble in these liquids, remains mixed merely with the woody particles, 
 from which it is easy to separate it by repeated washings and decantations, 
 because one of its properties is to swell extremely in the water,, and to become 
 very buoyant. Ihis substance swells up in cold as well as boiling water, without 
 any of its parts dissolving. It is soluble, however, almost completely by the 
 aid of heat in water sharpened with nitric or muriatic acid. 
 
 BATH. A receptacle of water in which to plunge, wash, or bathe the body. 
 The practice of bathing, although not so common in this country as on the 
 continent, is daily becoming more general; and, in most large towns, there are 
 public establishments, where, at a very short notice, warm, cold, and vapour 
 oaths, either plain, saline, or medicated, may be had. From the beneficial 
 effects of hot baths, in sudden cases of inflammation of the bowels, and of 
 cholera, portable baths, of various kinds, have been constructed, by means of 
 which a hot bath may be speedily prepared in a sick chamber ; and the appa- 
 ratus occupying but little space, can be easily stowed away when not in use. 
 I he annexed cut represents a simple and effectual apparatus of this description, 
 invented by Mr. Benham, of Wigmore Street, Cavendish Square, a represents 
 the ordinary bath filled with water to the proper height ; b a furnace for heating 
 the water; and c a fender to keep in the fuel and ashes; at the end d e the 
 bath has a double case, at top and bottom of which there are apertures com- 
 municating with a double-cased boiler that entirely surrounds the fire. The 
 water thus heated naturally ascends and enters the bath at e, while the cold 
 water to supply us place enters the boiler at d; thus a continued circulation of 
 He water is effected by tins arrangement, so as to heat it very quickly, and by
 
 BATTERING RAM. 
 
 155 
 
 a small fire, more conveniently and agreeably situated, than if placed under the 
 bath as usual ; / is a pump, the lower end of which dips into a small well at 
 the bottom of the bath for discharging the water ; g is a small wrought-iron flue ; 
 the whole runs upon castors. 
 
 In Mr. Hick's portable baths, a broad shallow flue of metal is constructed 
 underneath the bath, and in the flue is ignited a determinate quantity of the 
 oil of turpentine, or other inflammable liquid, supplied from a reservoir above, 
 in the side of the bath, and regulated by a stop-cock. The vapour arising from 
 the combustion is earned oft* by means of a tube, into the apartment in which 
 the bath is placed. By a slight modification of the foregoing plan, the patentee 
 purposes to employ the flame of condensed inflammable gas for heating the 
 water rapidly ; and in the water may be infused herbs, or other medicaments, 
 for patients who may be labouring under cutaneous diseases. By these arrange- 
 ments, a portable warm bath is prepared in a few minutes. 
 
 BATHS in Chemistry, a contrivance for subjecting different substances 
 either to a steady heat, not liable to sudden fluctuations, or to a temperature 
 which shall never exceed the boiling point of water. In the first case, the 
 vessel containing the substance to be heated is imbedded in a vessel containing 
 sand, or other slow conductor of caloric, and set in a furnace, and this is called 
 a sand hath; but if it is desired that the temperature shall not exceed 212, 
 water is substitute for sand, and this is called a water-bath. A familiar example 
 of a water-bath is the common 
 glue-pot, which consists simply 
 of a vessel containing water, in 
 which is immersed another ves- 
 sel containing the glue. Mr. 
 Vazie recently patented culi- 
 nary vessels on the same prin- 
 ciple, an illustration of which is 
 subjoined; a being the external 
 vessel containing water; b the 
 internal vessel containing the 
 food ; and c the cover. The 
 principle of this method of limit- 
 ing the temperature has received 
 a more extensive application, by 
 Messrs. Beale and Porter, who 
 have obtained a patent for em- 
 ploying, as a heating medium, 
 various substances, which rise in vapour at different degrees of the thermometric 
 scale, some exceeding, and others falling, below the boiling point of water, such 
 as alcohol, ether, naphtha, turpentine, and various essential oils. Under the 
 head BOILER will be found a description of an apparatus upon this principle. 
 
 BATTERING RAM. An ancient military engine, used for destroying the 
 walls of fortified places, but which, since the invention of gunpowder, ;s no
 
 15R 
 
 BEAMS. 
 
 longer used for that purpose, as, by means of cannon, the attack can be made 
 from a much greater distance; but machines of this description are still some- 
 times employed in taking down old and massive walls. The battering rams of 
 the ancients were of two kinds : the first consisted merely of a heavy beam, 
 with a head of iron, which the soldiers bore in their arms, and assailed the 
 walls by main strength. The second sort was much more powerful and effective. 
 In these the beam was suspended by chains from a frame ; the centre of gravity 
 of the mass of the beam being pulled out of the perpendicular by ropes, they 
 were suddenly let go, causing the head of the ram to strike the wall with a 
 force proportional to the weight of the mass, and the space through which it 
 moved. Some of these instruments were of enormous dimensions, and of 
 immense power. That of Vespasian is said to have been 120 feet long, and to 
 have weighed 1 00,000 Ibs. The effect of some of these instruments, was much 
 superior to any we can produce by our breaching cannon ; for if the weight of a 
 battering ram, moving with a velocity of 10 feet in a second, were no more 
 than 170 times that of a cannon ball, moving at the rate of 1700 feet in a 
 second, the momenta of both forces would be equal ; but as the weight of these 
 ancient machines was much greater than 170 times that of our heaviest cannon 
 balls, their momentum, or impetus, to overturn walls, and demolish buildings, 
 was much sirperior to that exerted by our modern artillery. 
 
 BEAM, in Building, a piece of timber resting upon walls, and used to sup- 
 port the floors or fronts of houses, to suspend weights from, &c. The strength 
 of beams to each other is inversely as the length, and directly as the breadth 
 and the square of their depth ; their depth, therefore, is generally made greater 
 than their breadth, as, by this means, greater strength may be obtained with 
 less material ; thus diminishing both the weight and the cost. Beams are 
 variously named, according to the situations they occupy in a building. A tie- 
 beam is a horizontal beam, extending from the opposite walls of a building, and 
 having notches near the extremities against which the lower ends of the prin- 
 cipal rafters of the roof abut, by which means the thrust of the rafters is exerted 
 against the tie-beam, instead of acting against the walls. A girder is a stout 
 beam, extending from one side of a building to the opposite one, and used to 
 carry the joists : when the distance between the walls is great, it at the same 
 time serves as a tie to the walls. A bressummer is a beam used to support a 
 portion of a building above a considerable opening similar to a lintel over a 
 door-way. When a beam projects from a wall, the outer end being unsupported, 
 it is termed a cantilever. In cases where the distance between the points of 
 support is great, and the load to be sustained by a beam is considerable, instead 
 of a beam formed of one piece, a frame of timber, called a truss, is employed, 
 which, in its simplest form, consists of two inclined beams, abutting against 
 notches in a horizontal beam near its extremities ; and the upper ends of the 
 beams meeting in a point upon which the load rests, by which means the pres- 
 sure is transferred from the centre of the beam, to the part of it which is over 
 the points of support, and the stress upon the beam is changed from a transverse 
 strain to a tensile strain, operating in the direction of the fibres. Roofs and centres 
 of bridges are specimens of trusses, and are framed upon the same principle, 
 although more complex in the form. The methods of forming trusses are very 
 
 Fig. 1. 
 
 varied, depending partly upon the uses for which they are intended ; the following 
 description of a very neat, simple, and effectual method of constructing rafters for
 
 BEAMS. 
 
 137 
 
 a nearly flat roof, invented by Mr. Smart, of the Ordnance Wharf, West- 
 minster Bridge, is an extract taken from the inventor's communication 
 to the Society .of Arts. " I take a square spar of the usual size for a rafter, 
 and, by means of a circular saw, make an incision in it as shown at b b, Fig. 1 
 
 Sage 156. I then make the cut c at right angles to the former, and equi- 
 istant from the two ends ; lastly, I make the two cuts d d, taking out a 
 thin wedge from each place. The two pieces c d are then to be gently 
 raised up, till they form an angle of 10 or 12, with the piece b b, 
 and are secured in their place by the insertion of a key-wedge e of 
 seasoned oak, as represented at Fig. 2. It is obvious that a weight 
 pressing on the key-wedge of this rafter (the ends being properly sup- 
 ported), will be sustained till either the fibres of the wood forming 
 the string are drawn asunder, or till the lateral cohesion of the wood 
 forming the butt-ends of the rafters be destroyed : at the same time 
 there is no lateral pressure on the wall." The above rafter is com- 
 monly known by the name of the " Bow and String Rafter." 
 
 Another rafter upon the same principle, by the inventor of the fore- 
 going, is shown in the margin. The rafter, which is 56 feet between 
 the bearings, is made out of a scantling 10 inches by 4. An incision 
 is made by a circular saw, from the middle nearly to each end ; a 
 transverse cut is then made at a, through the middle of the upper 
 part of it, and at each end b b of the incision, a transverse piece, of a 
 wedge shape, is cut out, reaching nearly to the longitudinal incision, 
 but not so near as to separate the parts. Short pieces of wood are 
 then inserted between the upper and under part of the rafter, and the 
 whole are secured by iron straps. It appears that Mr. Smart was led 
 to the foregoing method of forming rafters, by the following experi- 
 ment, which he made for the purpose of ascertaining whether the 
 strength of a beam is increased in the proportion of three to two, as 
 stated by Belidor, by fastening its ends so as to prevent their 
 approach when loaded in the middle. He placed a lath, an eighth of 
 an inch thick, in a strong frame, as shown by the annexed cut, which 
 broke with a load of ,>. ,->. 
 
 lllbs.placedonitsmid- VI I? fl 17 
 
 die. He next took a lath ' 
 
 of the same wood, and 
 
 fixed it firmly at the 
 
 ends, by means of the 
 
 projecting pieces b b 
 
 and the wedges c c, and 
 
 ascertained that it 
 
 would sustain, by this 
 
 arrangement, a load of 
 
 270 Ibs. whence it appears that the strength of the lath was increased 
 
 nearly 25 times, by merely securing it well at the ends. 
 
 The following figure represents a trussed girder of wrought iron, 
 similar in construction to the foregoing. This girder is made by 
 welding an arched bar of wrought iron to a longer straight bar, and 
 then turning the ends of this latter either up or down, as may be most 
 convenient for the particular use to which the girder is to be applied. 
 / / are the places where the bars are welded together that compose 
 the girder ; u u the ends of the straight bar turned either up or 
 down. The arch is prevented from buckling, when the weight presses 
 upon it, by means of blocks of well-seasoned wood, inserted at inter- 
 vals between the two bars, and secured in their places by the iron straps
 
 158 
 
 BEAMS. 
 
 t; v. Beams of wrought iron made in this way will, in Mr. Smart's opinion, 
 support a weight so much greater than cast iron ones of equal dimensions, 
 that they may be made of any given strength at half the cost of equivalent 
 beams of cast iron. 
 
 The cut on the left represents one of the iron girders employed in building the 
 London University. The whole length is 36 feet, and cast in one piece ; it 
 rises in the middle about 25 inches, and is provided with a wrought iron tie or 
 wniffin circular bolt of about 3 inches diameter, which passes 
 -< through apertures in the series of projecting pieces 
 fj shown, and is strongly screwed up at the ends c c, 
 On each side of the girder are bolted wooden scant- 
 U lings, into which the joists are framed. 
 
 Fig. 1 represents a trussed girder, invented by 
 Mr. J. Conder, on the principle of suspension ; and 
 O Figs. 2, 3, 4, 5, represent separate parts of the plan of 
 trussing, and the same letters refer to similar parts in 
 M all the figures. The girder a a Fig. 1 is furnished with 
 cast iron plates,, turned down at right angles, to extend 
 ] over its ends. These end plates have on their upper 
 surfaces circular hooked projections, shown in elevation 
 by Fig. 2, and in plan by Fig. 3. The use of these 
 Fig. 2. Fig. 3. 
 
 o 
 
 o 
 
 o 
 
 hooked projections is to receive round rods of wrought ! 
 iron, bent in the middle to correspond and fit into the fc 
 hooked projections, as represented by ft Fig.3. The 
 ? 4- 
 
 Fig. S. 
 
 iron rods extend along each side of the girder one- 
 
 third r>f lf-9 lono-fVi ; 1 i. .. ^5""=i vui;- 
 
 rom b to d. 
 iss pieces of 
 
 ron ros exen aong each side of th 
 third of its length, , a sloping direction from b to d. 
 1 where their ends pass through holes in c
 
 BEAMS. 
 
 159 
 
 iron, and are secured by screwing thereon nuts, as shown at Fig. 4. Between 
 the pieces d d and the lower side of the girder are placed prism-shaped blocks 
 of oak c e, shown in section by Fig. 5, which vary in size according to the depth 
 of the roof or floor which the girder is intended to support. Below the middle 
 of the girder, and parallel thereto, extends a single rod/, equal in strength to a 
 double rod e e ; this rod passes through the middle of the cross pieces d d, and 
 is secured by nuts screwed en its ends, as represented by Fig. 4. All the parts 
 of the truss may be brought to any required tension, and the girder made to 
 camber simply by screwing up one of the nuts on the rod f. A somewhat 
 simpler plan is represented in the following figure, whilst it possesses the sam 
 
 advantages as to strength and durability. The girder d to be trussed, is divided 
 longitudinally into two flitches, and between them is introduced a single rod of 
 iron c, the ends of which pass through the kneed plates b b, and are then 
 secured by screwed nuts ; the ends of the flitch are bevelled off at right angles, 
 to the direction of the trussed rod. Beneath the girder are placed two triangular 
 blocks d d, proportionate to the strength required. The two flitches are kept 
 apart the thickness of the truss rod by the introduction of slips of wood between 
 them, and kept in their places by straps at e e e e. 
 
 e truss, with one of the flitches removed 
 
 rig. 5.
 
 160 
 
 BEAMS. 
 
 to show the iron work ; and Fig. 2 is a section of the girder, a a the two sus- 
 pension links, connected with the two tie links b b by bolts and keys, through 
 the cast iron saddle pieces d d. The upper 
 ends are united to the abutment pieces 
 r. c by bolts passing through them ; the 
 beam is adjusted to its bearing, or cam- 
 bered, if necessary, by the folding wedges 
 (seen at e e Fig. 2) at the back of the 
 saddle pieces, which it may be found ne- 
 cessary to steady sideways by blockings 
 spiked to the beams. Figs. 3 and 4, eleva- 
 tion and plan of another mode of connect- 
 ing the tie links and adjusting them by 
 wedges. Fig. 5, anotherform of link, which 
 maybe used, instead of the double bar link. 
 The subjoined figures represent one 
 of the girders employed at Messrs. Nichol- 
 son's distillery, to support a liquor back 
 containing 19000 gallons, which, when 
 full, weighs nearly 100 tons. Fig. 1 
 is the elevation of the girder, with one 
 of the flitches removed. Fig. 2 a plan of 
 the truss, a a a Fig. 1 are three strong 
 plates of cast iron, forming a sort of arch, 
 of which the centre piece may be con- 
 sidered the key-stone, and b b cast iron 
 plates, resting on the wall, as the abut- 
 ments, c c cast iron blocks, in which the 
 upper ends of the two side plates a a, and 
 the ends of the middle plate are lodged ; 
 d d blocks of cast iron, which are screwed 
 up against the under side of the girder, 
 by nuts on the end of the screw-bolts 
 passing through the blocks c c. e is one 
 of two wrought-iron tie bars, passing 
 through the blocks d d and b b, and se- 
 cured by nuts at the ends e, and which 
 ends, as a further security, are chained. 
 The blocks b b have protuberances // 
 which are let into the bearing timbers g 
 on the walls h. The ends / b of the 
 blocks incline outwards about 10 degrees, 
 on which account the flitches of the 
 girder cannot slip down, but must press 
 at the angle b, as must also the points 
 between bf of the plates a a, when the 
 weight presses down the queens by the 
 part of the girder bearing on their 
 shoulder or on the blocks dd, thus giving 
 the whole weight to the bars e in the 
 direction of their length, just as if the 
 weight were suspended vertically from 
 those bars, or nearly so, the girder beino- 
 merely a rest for the base of the back. 
 Fig. 3 is the end, with the girder trussed 
 oo ; 4 is the end view of the blocks d d, 
 through *hich the tie bars pass; 5 a 
 section of the inner part of the end 
 
 block, when trussed ; 6 is one of ^ fo^ fc^ which saddle over 
 to keep them to at top ; and 7 is one , )f the piece3 of oak which fit into
 
 BEAMS. 
 
 J61 
 
 apertures between the flitches to preserve the bearing. The bars e are 2 inches 
 in diameter, or upwards of 3$ inches area. 
 
 We shall conclude this article with a description of a trussed girder proposed 
 by Mr. Gutteridge, and which we insert rather for the novelty 
 of the contrivance, than for any great merit which we can 
 discover in it. a is a beam of wood or girder to be trussed, 
 lodging on the walls h. bg b a wrought iron plate or bar lying 
 on the beam, and attached to iron levers b c d by pivots at b. 
 These levers are attached to the ends of the beam by iron plates 
 i, which are fulcra, c being the centre. To the lower extremity 
 or pivots of the arm c d is attached a bar of iron / at each end, 
 and these are connected by pivots at ef to a similar bar m, and 
 are kept below the beam by cast iron blocks k. The object of 
 this construction is to cause any weight laid upon the beam at 
 g to counteract its own tendency to bend the beam, by its in- 
 creasing the tension of the suspension rods I m I, which would 
 cause the blocks k k to rise ; but the weight of any load is 
 made to increase the tension of the tie-bar by much simpler 
 means in some of the trusses previously described, as in Smart's 
 bow and string rafter, or in the girders at Mr. Nicholson's 
 distillery. 
 
 BEDSTEAD. The forms of bedsteads are so numerous, 
 and at the same time, so well known, as to render description at 
 once tedious and unnecessary ; we shall, therefore, merely notice 
 a bedstead designed especially for the use of invalids. It is the 
 invention of Mr. Rawlins, of Pentonville, and is named by him 
 the Patent Invalid Bedstead. In the engraving in the next page, 
 which is a perspective representation of this invention, A repre- 
 sents the bedstead ; B, swing frame, showing the head and foot 
 frames raised ; C, rising head frame ; D, rising foot frame ; E 
 in the figures underneath shows the elevation of the knee-joint ; 
 F, folding side frame. The patient lies on the mattress on the 
 swing-frame, which may rest on the mattress beneath ; or, if 
 desirable to be softer, on a bed ; and, for the convenience of per- 
 forming the offices of nature with cleanliness and comfort, the 
 swing- frame is raised up by turning the handles at the head and 
 foot of the bedstead (one, or both, as the occasion may require), 
 so as to admit a bed-pan to be placed beneath a circular hole 
 in the mattress (the cushion which fastens in underneath with 
 a buckle and strap having been previously removed). By 
 raising the swing frame higher, the bed beneath can be shaken 
 up without inconvenience to the patient. In asthmatic and 
 other complaints, where a difficulty of breathing is experienced, 
 the rising head frame may be elevated so as to give the utmost 
 relief the nature of the disorder will admit of. As persons long 
 confined to bed grow weary of lying in one position, a change 
 may be readily obtained by the aid of the attendants, and, in 
 some cases without it. If, for example, it is wished to raise the 
 feet, the attendant raises the rising foot frame by the hand hole 
 in the foot board, and the swing bracket fixed beneath drops 
 into the racks cut on each side of the swing frame, and supports 
 it at the desired elevation ; again, if the knees require to be 
 raised, the frame is raised as shown in the figure E, the ends of the frame 
 dropping into the rack before-mentioned ; if it is wished to raise and support 
 the body on one side, the folding frame being introduced between the mattress 
 and the swing frame, and the upper leaf of it raised, the patient is quietly 
 turned on his side, and supported in that position by the bracket dropping into 
 the racks cut in the lower leaf as shown in the figure F ; in short, the appa- 
 ratus may be arranged to suit any position which may be desired ; and for the 
 accommodation it affords to the- invalid, and for the facility with which the
 
 152 
 
 BKEHIVR. 
 
 requisite changes are effected, we think this apparatus superior to any invention 
 of the kind which has come under our notice. 
 
 BEEHIVE. An artificial habitation for bees, usually constructed of straw. This 
 description of hive is so well known, that we shall only remark upon one or two 
 essential points. First, care should be taken to have the hive made of clean 
 and good straw, and of suitable thickness ; and, secondly, it should be well 
 sheltered from cold winds, and rains, for if once the wet penetrates the hives, 
 it affects the combs, and the bees getting a distaste for their home, will work 
 slowly, and often desert it altogether. The culture of bees has, for some years 
 past, been an object of much attention in this country, and numerous improve- 
 ments have taken place in the construction of the hives, by which the cruel 
 practice of destroying the bees to obtain their honey is obviated, and the pro- 
 duce is very considerably increased by the management of the hives and their 
 inmates. Amongst those who have turned their attention to this subject, Mr. 
 Mott, of Moulton Chapel, Lincolnshire, stands distinguished for the improve- 
 ments he has introduced in the structure of beehives, and the management of 
 the bees. The most essential part of his plan consists in regulating the heat of 
 the hives by means of ventilation, so as to prevent the swarming of the bees ; 
 at the same time obliging them to exchange a hive filled with honey for an 
 empty one placed by the side of it. The cut represents an elevation of one of 
 the forms of hives adopted by Mr. Mott, inclosed in a frame like that of a 
 watchman's box, but surrounded by trellis-work (not shown) instead of close 
 boards. The lower portion g I being the warmest, is the apartment for the 
 queen and the larvae. The entrance for the bees is at a narrow hole at the 
 back of the hive, as at e, near to the ventilators v v, which are tin tubes open 
 on the outside of the hive, and perforated internally with minute holes (to
 
 BEER MACHINE. 
 
 163 
 
 prevent the bees from passing through) project- 
 ing horizontally towards the centre of the 
 hive; above there is a floor, with large apertures, 
 shown by the dots, which are covered by the 
 receptacles for the honey rrrr, into which 
 the bees, therefore, enter from beneath. 
 The compartment of the hive where these 
 vessels are placed, is made to open and shut 
 as a box, the lid of which is shown as 
 opened an inch or two, and so retained by 
 the cord and pulley. 
 
 BEER. A fermented liquor, which is 
 most commonly prepared from malted bar- 
 ley, although it is sometimes made from 
 other kinds of grain, either raw, or malted, 
 as wheat, maize, millet; also from sugar 
 and molasses ; and, recently, from mangel 
 wurzel ; in fact, it may be obtained from 
 most vegetable substances which contain 
 saccharine matter, uncombined with any 
 acid. Beer, or a fermented liquor prepared 
 from grain, was known to the ancient Egyp- 
 tians, with whom, indeed, the art of pre- 
 paring it is supposed to have had its rise. 
 Beer was also in use with the ancient Gauls, 
 Saxons, Britons, and other nations of the north 
 and west of Europe ; and is, at the present, a 
 common beverage in most countries where grain is plentiful, and where the 
 grape does not flourish. Park and Lander both mention it as extensively used 
 in various parts of the interior of Africa. It does not appear that either the 
 Egyptians, or any of the nations of antiquity, used hops, or any similar sub- 
 stance, with their worts, on which account their beer would not be well adapted 
 for keeping. This improvement in the art of brewing was introduced in 
 England about the beginning of the sixteenth century ; at the outset the prac- 
 tice encountered some prejudice ; and, in an old act of parliament, hops are 
 denounced as a poisonous weed. In England, two distinct sorts of beer are 
 known, called ale, and porter, or beer, and of each sort there are numerous 
 varieties. Although the difference in the flavour of ale and of porter is suffi- 
 ciently marked, it is difficult to say in what way it is produced ; that it is not 
 altogether owing to pale malt being used for brewing ale, as some assert, is 
 clear from the fact that, in many parts of the country, ale is brewed from brown 
 malt ; neither is it owing to a larger quantity of hops being used in making 
 porter, for the pale ale, which is exported in large quantities from this country 
 to India, contains a larger proportion of hops than the porter exported to the 
 same place ; neither will a difference in the proportions of the malt to the 
 water account for it, since some ales are stronger, and others weaker, than 
 porter. It is also singular that, although capital ale may be brewed in private 
 families, few persons but the London brewers, who have very large establish- 
 ments, can make good porter. Although the various causes we have just 
 noticed may have some effect, we imagine that the difference is principally 
 caused by the addition of certain ingredients to the worts during the process of 
 fermentation. This practice, although not openly avowed, is, nevertheless, well 
 known to be pretty general ; and it is also certain that some of these additional 
 ingredients are of a very noxious and unwholesome description. For the process 
 of making beer, see BREWING. 
 
 BEER MACHINE. An ingenious contrivance, of comparatively recent 
 introduction, for drawing beer from different casks, situated in an apartment or 
 cellar beneath, without descending for that purpose ; by which means mud 
 trouble and great waste of liquor is avoided. The machine consists of three 
 or four small lift and force pumps, firmly bedded in two blocks of wood, and
 
 164 BENZOIN. 
 
 inclosed in a handsome mahogany case. To the lower end of each pump is 
 attached a suction pipe, which is inserted in a cask of beer, (each pump being 
 employed to draw a particular quality of beer,) and from the upper end of the 
 pump proceeds a pipe connected to a nozzle in front of the case of the machine. 
 The piston rod passes through a small stuffing box on the cover of the barrel, 
 and through a guide, by which its parallel movement is secured; and it is con- 
 nected by slings to a bent lever, by which it is worked. This lever consists of 
 a short arm, to which the slings are attached, and stands at an angle of about 
 130 with the long arm or handle, which works through a slit in the semicircular 
 head of the case. A small cistern of white metal is fitted to the case beneath 
 the nozzles, and from it a pipe conveys the drippings to the waste-butt 
 
 BELL. A hollow vessel of metal, formed to produce a sound by the act of 
 striking it. The principal uses to which bells are applied, are to sound the 
 hours, and to summon persons from a distance. The forms of bells vary con- 
 siderably, some being segments of spheres, others truncated cones, but the most 
 common form is that in which the sides diminish in a curve line from the base 
 to the upper edge, the crown being slightly convex. The use of bells is 
 very ancient and extensive, as they were to be found amongst Jews, Greeks, 
 Romans, Christians, and Heathens, variously employed. Their first application 
 to ecclesiastical purposes is said to have been about the year 400, and in the 
 city of Nola. In Britain, bells were used in churches before the close of the 
 seventh century. Abroad are bells of dimensions greatly exceeding any to be 
 met with in this country. At Rouen, in Normandy, was a bell said to weigh 
 36,000 Ibs. At Erfurth is one weighing 28,200 Ibs.; its periphery is 14 j 
 ells, and its height, 4f ells. In the church of St. Ivan, at Moscow, is a bell 
 weighing 127,836 Ibs. ; but the largest bell in the known world, is the unsus- 
 pended bell in the Kremlin of that city. It is computed to weigh 443,772 Ibs. 
 In England, the largest is " Great Tom," of Christ Church, Oxford, weighing 
 17,000 Ibs.; the great bell of Lincoln weighs 9,894, and that of St. Paul's, 
 8,400 Ibs. 
 
 BELL, DIVING. See DIVING APPARATUS. 
 
 BELLOWS. An instrument for directing a current of air against burning 
 fuel, to increase the combustion. The ordinary bellows, for domestic use, are so 
 well known, as scarcely to require description, consisting merely of two flat 
 boards, united by a sort of hinge joint, and having a piece of leather, (broad in 
 the middle, and narrow at the two ends,) nailed round the sides of the boards, 
 to allow them to separate or move through a small angle. In the lower board 
 is a hole, through which the air enters, upon raising the upper board ; but being 
 prevented from escaping on pressing down the upper, by a leather flap valve, 
 which covers the hole, it is forced through a pipe or nozzle fitted at the junction of 
 the boards, and having a small valve behind it, opening outwards. For bellows 
 for manufacturing purposes, see BLOWING MACHINES. 
 
 BEN, OIL OF. This is obtained from the ben nut by simple pressure. It ii 
 remarkable for its not growing rancid in keeping, or at least not until it has 
 stood for a number of years ; and on this account it is used in extracting the 
 aromatic principle of such odoriferous flowers as yield little or no essential oil 
 in distillation. 
 
 BENZOIC ACID. An acid commonly obtained from benzoin, although it 
 exists in various substances, as vegetable balsams, cinnamon, the urine of horses, 
 cows, &c. It is usually procured from benzoin, either by sublimation, or by 
 digesting the powdered benzoin in lime water, and afterwards separating the 
 lime by the addition of muriatic acid. It crystallizes in fine silky filaments, of 
 a white and shining appearance, and of a spec. grav. of 0.667; it is soluble 
 in sulphuric and nitric acids, alcohol, oils, and tallow, but is only slightly soluble 
 in water. It unites easily with the earthy and alkaline bases. 
 
 BENZOIN, or BENJAMIN. A resin which exudes from incisions made 
 in a certain species of tree growing in the East Indies, particularly Siam, and 
 the island of Sumatra. This resin is moderately hard and brittle, and yields an 
 agreeable smell when rubbed or warmed. It is totally soluble in alcohol, from 
 vhich, like other resins, it may he precipitated by the addition of water.
 
 BINNACLE. 
 
 165 
 
 BERYL. A precious mineral, commonly green, but of various shades, pass- 
 ing into honey yellow and sky blue. Its spec. grav. is 2.7. It differs from 
 emerald in hardness and colour. It has been called aqua marine, and greenish 
 yellow emerald. It is electric by friction, and not by heat 
 
 BEVIL. An instrument for measuring and transferring the angle formed 
 by two surfaces ; it consists merely of two straight legs, turning upon a com- 
 mon centre, and is used by the two limbs coinciding with the surfaces where an 
 angle is to be ascertained. The annexed engraving represents an instrument 
 by which curved surfaces may be gauged, or the curve transferred to any kind 
 
 of work, or to paper, a and b Fig. 1, are two rulers connected together by a cir 
 cular joint ; c is an arch of brass fixed to b, and sliding through a mortise or 
 slit in a, to which it is fastened at pleasure, at any required angle, by means of 
 the screw in a pressing upon it. The rule a has six or more square mortises 
 made through it, (shewn in section in the drawing,) in which are placed as 
 many nuts moving on pivots ; each of these nuts is tapped to receive a long 
 screw (as at/,) working within them ; and each of the long screws is fixed at 
 one end to a flexible steel blade, e e, by means of a kind of swivel joint which 
 admits of the screw turning round in it without advancing, and allows it to 
 press either direct or aslant. Consequently, when the opposite ends of the 
 screws are turned by the thumb and forefinger, the steel blade is pressed out so 
 as to adapt itself to any given curve ; and being thereby fixed in the same 
 position, the curved line can be transferred therefrom to any kind of work, 
 or on to paper. Fig. 2 shews a contrivance for drawing the radii of wheels 
 with great expedition ; it is formed of a slip of thin brass, and the central 
 hole must be in the line o o ; if now a needle point passing through the 
 hole be inserted in the centre of the circle representing the wheel, the radii 
 nay be drawn with great facility and exactness along either of the lines o o, 
 to the different points or degrees previously marked upon the circumference. 
 
 BINNACLE. A small case, in which is placed the compass- box. It is fixed 
 to the deck in front of the steersman, and is furnished with glazed apertures to 
 admit light upon the compass, and exclude rain in the day, and at night is 
 lighted up by a lamp placed within it. These lamps are variously constructed
 
 1G<3 BISCUJT. 
 
 sometimes a hole is cut through the deck immediately below the compcss, 
 and a lamp is so placed as to give light to the compass and the cabin also; in 
 this case the card of the compass is formed of a semi-transparent material. 
 
 BINOCULAR TELESCOPE, is a telescope to which both eyes may be 
 applied at once, and consequently, the same object observed at the same time 
 with both. It consists of two tubes, with two sets of glasses, of the same 
 power, and adjusted to the same axis, which has been said to exhibit objects 
 larger and more distinct than a single or monocular glass. There are also 
 microscopes of the same construction, but they are very seldom used. 
 
 BIRD-LIME. The best bird-lime is made of the middle bark of the holly, 
 boiled seven or eight hours in water, and, when soft, it is laid in pits in the 
 ground, and covered with stones, and left to ferment till it is reduced to a kind 
 of mucilage. It is afterwards kneaded till it is freed from extraneous matter, 
 and then washed in a running stream till no impurities appear. In this state it 
 is left four or five days in earthen vessels to ferment and purify itself, when it 
 is fit for use. It may likewise be obtained from the misletoe, young shoots of 
 elder, and other vegetable substances. It is sometime's adulterated with turpen- 
 tine, oil, vinegar, and other matters. Good bird-lime is of a greenish colour, 
 and sour flavour ; gluey, stringy, and tenacious ; and, in smell, resembling lin- 
 seed oil. 
 
 BISCULT. A species of unleavened bread. There are several sorts of bis- 
 cuit, each having a distinguishing name ; but the most important, from its very 
 great consumption, is the sea biscuit, destined for the use of shipping. A new 
 baking establishment having been recently formed at the Royal Clarence Vic- 
 tualling Establishment, at Weevil, near Portsmouth, upon a scale of magnitude 
 nearly sufficient to supply the whole royal navy with biscuit, and that of a very 
 superior description, the following account, taken from the United Service Journal 
 will, we trust, be acceptable to our readers. " It having been discovered that the 
 flour supplied togovernmentby contract had, in many instances, been most shame- 
 fully adulterated, the corn is ground at mills comprised within the establish- 
 ment, and by which means the introduction of improper ingredients is prevented, 
 and precisely the proportion of bran which is requisite in the composition of 
 good sea-biscuit is retained, and no more. The flour-mill is furnished with 10 
 pair of stones, by which 40 bushels of flour may be ground and dressed, ready for 
 baking, in an hour. The baking establishment consists of 9 ovens, each 13 feet 
 long by 11 feet wide, and 17J inches in height. These are each heated by sepa- 
 rate furnaces, so constructed, that a blast of hot air and fire sweeps through 
 them, and gives to the interior the requisite dose of heat in an incredibly short 
 space of time. The first operation in making the biscuits consists in mixing 
 the flour, or rather meal and water; 13 gallons of water are first introduced 
 into a trough, and then a sack of the meal, weighing 280 Ibs. When the whole 
 has been poured in by a channel communicating with an upper room, a bell 
 rings, and the trough is closed. An apparatus, consisting of two sets of what 
 are called knives, each set ten in number, are then made to revolve amongst 
 the flour and water by means of machinery. This mixing lasts one minute and 
 a half, during which time the double set of knives, or stirrers, make twenty-six 
 revolutions. The next process is to cast the lumps of dough under what are called 
 the breaking-rollers huge cylinders of iron weighing 14 cwt. each, and moved 
 horizontally by the machinery along stout tables. The dough is thus formed into 
 large rude masses, 6 feet long, by 3 feet broad, and several inches thick. At 
 this stage of the business the kneading is still very imperfect, and traces of dry 
 flour may still be detected. These great masses of dough are now drawn out, 
 and cut into a number of smaller masses about a foot and a half long by a foot 
 wide, and again thrust under the rollers, which is repeated until the mixture is 
 so complete that not the slightest trace of any inequality is discoverable in any 
 part of the mass. It should have been stated that two workmen stand one at 
 each side of the rollers, and as the dough is flattened out, they fold it up, or 
 double one part upon another, so that the roller, at its next passage, squeezes 
 these parts together, and forces them to mix. The dough is next cut into small 
 portions, and being placed upon large fiat boards, is, by the agency of
 
 BIT. 167 
 
 machinery, conveyed from_ the centre to the extremity of the baking-room. 
 Here it is received by a workman, who places it under what is called the sheet- 
 roller, but which, for size, colour, and thickness, more nearly resembles a 
 blanket. The kneading is thus complete, and the dough only requires to be 
 cut into biscuits before it is committed to the oven. The cutting is effected by 
 what is called the cutting-plate, consisting of a net-work of 52 sharp edged 
 hexagonal frames, each as large as a biscuit. This frame is moved slowly up 
 and down by machinery, and the workman watching his opportunity, slides 
 under it the above described blanket of dough, which is about the size of the 
 leaf of a dining-table ; and the cutting-frame, in its descent, indents the sheet, 
 but does not actually cut it through, but leaves sufficient substance to enable 
 the workman at the mouth of the oven to jerk the whole mass of biscuits, un- 
 broken, into the oven. The dough is prevented sticking to the cutting-frame, by 
 the following ingenious device ; between each of the cutter frames is a small 
 flat open frame, movable up and down, and loaded with an iron ball, weighing 
 several ounces. When the great frame comes down upon the dough, and cuts 
 out 52 biscuits, each of these minor frames yield to the pressure, and are raised 
 up ; but as soon as the great frame rises, the weight of the balls acting upon the 
 little frames thrusts the whole blanket off, and allows the workman to pull it 
 out. One quarter of an hour is sufficient to bake the biscuit, which is after- 
 wards placed for three days in a drying room, heated to 85, or 90, which 
 completes the process." The following statement of the performance of the 
 machinery is taken from actual experiment : in 1 16 days, during 68 of which the 
 work was continued for only 7J hours, and during 48, for only 5f hours each day, 
 in all 769 working hours, equal to 77 days of 10 hours each, the following quan- 
 tity of biscuit was baked in the 9 ovens ; viz. 12,307 cwt.=l,378,400 Ibs. The 
 wages of the men employed in baking this quantity amounted to 2731. 10*. 9\d. ; 
 if it had been made by hand the wages would have been 933/. 5s. lOd ; saving 
 in the wages of labour, 659/. 7s. O^d. In this is not included any part of the 
 interest of the sum laid out upon the machine, or expended in keeping it in 
 order. But in a very few years, at such an immense rate of saving, the cost of 
 the engine and other machinery would be repaid. This admirable apparatus 
 is the invention of T. T. Grant, Esq. Storekeeper of the Royal Clarence Vic- 
 tualling Establishment, who, we believe, has been rewarded by a grant of 2,000/. 
 from Government. 
 
 BISMUTH. A brittle metal, of a yellowish white colour ; it is somewhat 
 harder than lead, and melts at 480 Fahr. Urged by a strong heat in a close 
 vessel, it sublimes entire, and crystallizes very distinctly when gradually cooled. 
 Bismuth unites with most metallic substances, and renders them, in general, 
 more fusible. 8 parts of bismuth, 5 of lead, and 3 of tin, form what is called 
 fusible metal, which melts in boiling water. Bismuth is used in the composition 
 of pewter, in the fabrication of printers' types, and, combined with lead and tin, 
 forms plumbers' solder. 
 
 BISTOURY, in Surgery, an instrument for making incisions, of which there 
 are different kinds, some straight and fixed in a handle like a knife ; some are 
 of the form of a lance, while others are crooked, with the sharp edge on the 
 inside. 
 
 BISTRE. A brown pigment, consisting of the finest part of wood-soot, pul- 
 verized, and passed through a fine sieve, then mixed with a little gum-water, 
 made into cakes, and baked. It is a fine transparent colour, and has much the 
 same effect in water-painting, where alone it is used, as brown pink in oil. 
 The best is prepared from dry beech wood, by grinding it with water into a 
 smooth paste, then diluting it with more water. After the grosser liquor has 
 subsided, the liquor is poured off, and left to settle for a few days; the fine 
 matter that remains is the bistre. 
 
 BIT. The iron which is put into a horse's mouth, and to which the bridle 
 is attached. There are various descriptions of bits, but they may all be ranged 
 under two headsj the snaffle and the curb ; in the snaffle, the bit is formed 
 slightly curved, and frequently jointed in the middle, and the bridle, or rein, is 
 attached to rings in the extremities of the bit. Curb bits are generally formed
 
 168 
 
 BIT. 
 
 with a small semicircular bend in the centre of the mouth-piece, and with arms 
 or cheek-pieces formed at the ends of the mouth-piece. To the upper part of 
 the cheek-pieces is hooked a chain passing under the lower jaw of the hone, 
 and to the lower end of the cheek-pieces is attached the rein, by pulling which, 
 the upper ends of the cheek-piece are thrown forward, and the curb chain 
 pressed forcibly against the lower jaw. Curb bits are very powerful in checking 
 a horse, from the leverage afforded by the cheek-piece, but they tend greatly to 
 injure the mouth, and cause much uneasiness to the animal. Mr. George 
 Diggles, of Westminster, took out a patent, some years back, which, for ordinary 
 riding or driving, is attended with no more injury or irritation to the horse's 
 mouth than the ordinary snaffle, but which, when occasion requires, instantly 
 acts as a very powerful curb. This effect is obtained by means of a sliding 
 piece, with a ring attached to each cheek of the bit, to which ring the rein or 
 bridle is connected in the usual way ; and when it is found necessary to exert a 
 considerable force in curbing the horse, the pulling of the rein will draw the 
 slider towards the bottom of the cheek, thus lengthening the lever so consider- 
 ably that the horse is arrested by an irresistible power. The annexed, Fig. 1, 
 represents a side view of the improved bit, applied to a horse's head, and in 
 the ordinary position, when riding or driving ; the dotted lines show the position 
 of the parts when the rein is pulled with considerable force. Fig. 2 gives a 
 
 Fig. 2. 
 
 LflJ 
 
 front view of the improved oil a is the riding or driving rein attached to the 
 ring b, which instead of being fixed to some particular part of the bit, as in the 
 ordinary bit, is attached to a sliding piece c. A convoluted spring d acts upon 
 this sliding piece, and keeps it and the ring b up to that part of the cheek 
 which is near the mouth-piece, Fig. 2, where the leverage being small, the 
 riding or driving rein will act in the ordinary manner ; but when it becomes 
 necessary to exert an extraordinary power upon the horse's mouth, the rein a 
 is forcibly pulled back, by which the cheek of the bit is moved out of its per- 
 pendicular position, and the sliding piece e, with the ring, slides downwards 
 towards the lower part of the cheek, as shewn by the dotted lines. To prevent 
 the ring and slider from being drawn too low, a stop is placed on the bit at e 
 for a riding bit, but for a driving bit, the bar at the bottom of the bit, as seen 
 at/, answers the purpose. When the tension of the rein is relaxed, the elastic 
 force of the spring draws up the sliding piece c, with the ring b, and the rein a, 
 to its ordinary place, as represented in Fig 1. The cases i i, which contain 
 the springs, are made to slide up and down in grooves, formed on opposite sides 
 of the cheeks, for the convenience of oiling, exchanging, cleaning, or repairing 
 
 the 
 
 ings
 
 BLASTING. 169 
 
 BITTERN. The mother water which remains after the crystallization of 
 common salt in sea water, or in the water of salt springs. It abounds with 
 sulphate and muriate of magnesia, to which its bitterness is owing. 
 
 BITUMEN. A term including a considerable range of mineral substances, 
 which burn with flame in the open air. They vary, in consistency, from a thin 
 liquid to a solid ; but the solids are for the most part liquifiable at a moderate 
 heat. It also forms a component part of various substances, as jet, amber, and 
 all the varieties of pit-coal. 
 
 BLANKET. A warm, woolly sort of stuff, light and loosely woven, used in 
 bedding. The manufacture is chiefly confined to Witney, in Oxfordshire, where 
 it is the principal article of trade. The excellent quality of Witney blankets 
 has been attributed to the abstersive nitrous water of the river Windrush, 
 wherewith they are scoured. Blankets are made of felt wool, that is, wool from 
 sheep skins, which they divide into several sorts. Of the head wool, and bay 
 wool, they make blankets of twelve, eleven, and ten quarters broad ; of the 
 ordinary and middle sort, blankets of eight and seven quarters broad ; of the 
 best tail wool, blankets of six quarters broad, commonly called cuts, serving for 
 seamen's hammocks. 
 
 BLASTING. An operation resorted to in mines and quarries for the pur- 
 pose of detaching large masses of earth or stones. The implements employed, 
 (which are few and simple,) are shown in the engraving. Fig. 1. The sledge 
 
 2. & 3. 
 
 hammer, or mallet. Fig. 2. The borer, or chisel. Fig. 3. The wedges. Fig. 
 4. The scraper. Fig. 5. The claying bar. Fig. 6. The needle. Fig. 7. The 
 tamping bar. Fig. 8. The shovel. Fig. 9. The fusee inserted in the charge. 
 To perform the operation of blasting, two men only are requisite. The miner's 
 judgment directs him to the fittest place for the charge, and a hole is bored or 
 cut in the rock, in the following manner, to receive it. The borer, or chisel, Fig.2, 
 is held by one man, whilst the other man strikes it with the hammer or mallet; 
 the man holding the chisel turning it at every blow, so as to cross the previous cut, 
 by which means the stone is chipped away by degrees. The boring, or cutting, 
 is occasionally suspended to clear out the hole, which is done by the scraper, 
 Fig. 4. When the perforation is of the required depth, (which varies from one 
 to three feet, the diameter being about an inch and a half,) if the hole be wet, 
 some tough dry clay is introduced, and the claying bar, Fig. 5, is driven in with 
 great violence, by which means the clay is forced into all the crevices, absorb- 
 ing the moisture, and preventing the entrance of more ; on withdrawing the 
 claying-bar, the hole is left dry, and of a smooth uniform surface, which adapts 
 it for receiving the charge. This consists of gunpowder alone, or mixed with 
 some quicklime, (which it is said increases the force of the explosion) ; it is 
 inclosed in paper as a common cartridge, to fit the bore ; but in very wet situa-
 
 170 BLEACHING. 
 
 tions, a tin case is sometimes used to contain it. The charge being now intro- 
 duced, and thrust to the bottom of the hole by means of a thin tapering copper roi 
 called the needle, Fig. 6, which is also driven down with the charge. The next 
 operation is to exclude as much of the air as possible, by reducing the size of 
 the vent; for this purpose, the tamping bar, Fig. 7, is employed in ramming 
 round the needle some yielding yet compact substance, so that when the needle 
 is withdrawn, a very small vent or touch-hole remains. Into this perforation is 
 dropped a fusee, or rush, charged with powder, on the top of which is fixed a 
 " snuft," as it is called, or some other contrivance, so adjusted as to burn a suffi- 
 cient time to permit the man who fires it to retreat to a proper distance. Pre- 
 vious to firing, it is usual to give notice to all persons in the immediate 
 neighbourhood, by blowing a horn or ringing a bell, that they may have the 
 opportunity of retiring to some place of security. 
 
 BLEACHING. The art of freeing cloths and various other substances 
 from their natural brown or dusky tinge, and rendering them perfectly white. 
 The most ancient, and at one time the only known, method of bleaching linen, 
 or cotton cloths, consists in frequently wetting them, and exposing them upon 
 the grass to the rays of the sun ; the powerful action of which in the destruction 
 of colours is well known. This process, which is distinguished by the term of 
 " Grass bleaching," has, however, been nearly superseded by another termed 
 " Gas, or Chemical bleaching," founded upon one of those brilliant and useful 
 discoveries, by which modern chemical science has so honourably distinguished 
 itself, and rendered such service to the arts of life. Before proceeding to 
 describe the new, (and now the ordinary process,) we shall give a brief descrip- 
 tion of the method of grass bleaching, as, although not generally practised, it is 
 still in use in some parts. The details of the process vary of course with the 
 nature of the goods ; but the following is the process for bleaching flax-yarn, 
 which constitutes an important branch of business. The first operation, called 
 steeping, consists in immersing the brown yarn in hot water, or in allowing it 
 to macerate in cold water, or in alkaline ley. This occasions a kind of fermen- 
 tation, which loosens the saliva employed in spinning the yarn, and so far 
 separates the other impurities attached to it, that the whole may be easily 
 removed by washing in river or spring water. The next operation is that of 
 bucking, or boiling in an alkaline lye, after which the skeins are exposed on the 
 grass, for two or three weeks, which latter operation is called crofting. These 
 alternate operations of bucking, washing, and crofting, are generally repeated 
 four or five times, each time lessening the strength of the alkaline solution in 
 which the bucking was performed. The next process is that of scouring, which, 
 as more anciently practised, consisted in soaking the yarn in milk, which had 
 become acidulous by age, which was usually employed, for the first time, 
 immediately after the fourth or fifth bucking. In this liquor, which was tech- 
 nically called the first sour, the goods generally lay for three weeks, or until 
 such time as the scum began to crack and subside, when they were usually 
 taken out and submitted to a repetition of the processes already described. Thus, 
 whenever the goods had been once soured, the operations of bucking, washing, 
 scouring, and crofting, were repeated in regular rotation, until the yarn came to a 
 good colour, and was esteemed perfectly clear. These tedious operations have been 
 much shortened by substituting very dilute sulphuric acid for the sour milk. This 
 improvement (suggested by Dr. Home,) so much accelerated the process, that one 
 souring by sulphuric acid may be performed in from 12 to 24 hours ; whilst every 
 souring by the milk process required from two to six weeks ; and the whole process 
 may by this means be completed in four months, which before required seven or 
 eight months. We shall now proceed to give a slight history and description of 
 the new system of bleaching, founded upon the property which chlorine pos- 
 sesses, of rapidly destroying vegetable colours. By this system, (which fur- 
 nishes one of the most beautiful illustrations of the immense benefits which 
 science may render to the useful arts,) the practice of bleaching is con- 
 ducted with a degree of precision before unknown, and with the most surpri- 
 sing expedition. For the discovery of chlorine, we are indebted to Scheele, 
 who, in the year 1774, first formed it by art, and afterwards ascertained its
 
 BLEACHING. Ml 
 
 powers in destroying vegetable colours. But the first person who made experi 
 merits upon this gas, with a view to its application in the arts, was Mr. Ber 
 thollet, who, in the Journal de Physique, for June, 1785, and again in the 
 number for August, 1786, "explained the nature of its action on vegetable 
 Colours, and suggested how it might be applied with advantage to the process 
 of bleaching. The subject soon attracted the attention of various scientific 
 persons and enterprising manufacturers, and numerous establishments were 
 formed, in which the process of Berthollet (modified by subsequent discoveries,) 
 was adopted. Amongst the first to introduce and perfect the new process in 
 this country, were Professor Copland, the celebrated Watt, and Mr. Henry, of 
 Manchester. Mr. Watt, so early as 1787, had introduced it in the bleaching 
 field of Mr. Macgregor, at Glasgow ; and in his first attempt, he bleached 
 500 pieces of cloth ; and Mr. Henry, in the year 1788, published an account of 
 the process, as practised by himself, which account comprehends every thing at 
 this time known respecting the use of chlorine gas in bleaching, excepting the 
 condensation of the gas, by means of lime. At the first introduction of the new 
 process, the chlorine was employed in the state of gas, but this method was 
 found to be attended with many inconveniences ; the fumes occasioning consi- 
 derable annoyance to the workmen, and the texture of the cloth being frequently 
 injured by the too great energy of the gas. It was also found extremely diffi- 
 cult to expose all the surfaces equally to its action, without which no perfect 
 bleaching can ever be effected. The first remedy for these inconveniences 
 consisted in condensing the gas in water, and subsequently in a solution of potash, 
 which imbibed the gas more readily than water alone, and formed a more 
 concentrated liquor. This latter process was invented by some manufacturers 
 at Javelle, whence the liquid was named " Liquer de Javelle." 
 
 In the year 1798, Mr. Tennant, of Glasgow, took out a patent for a new 
 bleaching liquor, which consisted of a solution of chlorine of lime, instead of 
 oxy muriate of potash, which, besides being equally efficacious with the former for 
 general purposes, has the advantage of being much cheaper. It is not, however, 
 applicable where cottons are subsequently to be dyed with madder : for bleach- 
 ing these, the oxymuriates of potash or soda must be employed. The peculiar 
 advantages of combining chlorine with lime, or the alkalies, consists in the cir- 
 cumstance that the saline solution gives out the gas gradually to the goods which 
 -equire bleaching, but does not part with it to the atmosphere with the same 
 facility. In consequence of this, the operation of bleaching is now not inju- 
 rious, nor even very disagreeable, to the workmen; whereas, in the former 
 process, when the gas was merely received into water, it was so freely given out 
 again that no man could long endure to work in it, or even, for any consider- 
 able time, to superintend the operations. This advantage of the new process 
 more than compensates for the diminution of the bleaching power of chlorine, 
 which results from the aforesaid combinations. Mr. Tennant's patent for the 
 liquid chloride of lime was afterwards set aside ; but he subsequently obtained a 
 patent for combining chlorine with lime in the dry state. This is a most valuable 
 improvement, the dry chloride being less liable to decomposition than the liquid, 
 and being so much more portable, the smaller manufacturers find it more 
 advantageous to purchase the article of those whose business it is to prepare it, 
 than to establish works for the preparation of the article themselves. The fol- 
 lowing is the process as practised in bleaching linen, or cotton cloth, or yarn. 
 The same methods are followed as far as the fourth or fifth bucking, as 
 described in the process of grass bleaching, only good washing is substituted 
 for crofting. The goods are then immersed in a solution of chloride of lime, 
 or of the chlorides of potash or soda, and are then well washed, by machinery, 
 in pure water. They are then taken to the souring vessels, containing a portion 
 of very dilute sulphuric acid, and when taken out of these vessels, are again 
 well washed in water ; and, lastly, they are submitted once more to the alkaline 
 process already described. Linen goods require, at least, three immersions in 
 the solution of chloride of lime, followed by an equal number of alternate 
 immersions in the sours and in the alkaline solutions, carefullv and thoroughly 
 washing them in pure water between each of these processes. Cottons, however,
 
 172 BLEACHING. 
 
 require fewer immersions in the bleaching liquor, which may likewise be 
 more diluted with water for cottons than for linens. By this method of 
 bleaching, linen goods constantly acquire a yellowish tinge ; this, however, is so 
 superficial, that mere exposure to the air for a few days generally removes it. 
 The goods are then finished by boiling them for a short time in a diluted solu- 
 tion of pearlash and white soap, which removes the disagreeable odour which 
 would otherwise be attached to articles bleached by this process. Cotton goods 
 do not require crofting, as the yellow tinge, just mentioned, does not appear 
 in them when finished, being removed by the sulphuric acid, although this acid 
 will not remove it from linen goods. But the routine just described, Mr. 
 Parkes (from whose essay on bleaching much of the preceding account is 
 taken,) observes, is not sufficient for bleaching calicoes intended for the best 
 madder work. The following outline of a process adopted by a scientific 
 printer in Scotland, for bleaching calicoes for madder work, or resist work, or 
 for pale blue dipping, was communicated by him to Mr. Parkes, with an assur- 
 ance that it may be relied on. The goods, after being singed, steeped, and 
 squeezed, by passing between rollers, are boiled four times, ten or twelve hours 
 each time, in a solution of caustic potash of a spec. grav. from 1.0127 to 2.0156, 
 washing them carefully and thoroughly between each boiling. They are then 
 immersed in a solution of thp chloride of potash, originally of the strength of 
 1.00625, and afterwards reduced, with twenty-four times its weight of water ; 
 but as the specific gravity alone is not a perfect guide, the bleaching power of 
 the liquid is tested by a solution of indigo of a known strength. In the above 
 preparation, the goods are allowed to remain 12 hours, and are then, by some 
 printers, laid, whilst wet, on the grass, and exposed to the sun and weather for 
 two or three days. From thence they are removed to the sours, made of the 
 spec. grav. of about 1.0254, at the temperature of 110 Fahr. ; and after 
 lying five or six hours, are taken to the wheel, and washed. The four boilings 
 in caustic potash, with the washings between each, are then repeated, and the 
 goods, after being again immersed in the diluted chloride of potash, are well 
 washed in pure water, and then rinced in common sours for half an hour. The 
 last process is that of careful washing in clean water, after which they are 
 immediately hung up in the airing sheds to dry gradually. Various articles, 
 besides cloth, such as wax, paper which has become mildewed, &c. are now 
 bleached by means of chlorine, either in the state of gas, or combined with 
 alkalies or alkaline earths. The annexed engraving represents the apparatus 
 employed for the preparation of chloride of potash, or soda, for the use of calico 
 printers, a is the furnace for heating the materials which furnish the chlorine ; 
 b a cast iron vessel containing water, and forming a water bath for the recep- 
 tion of the still ; c the body of the still made of lead, and the upper part sur- 
 rounded by a deep cup d d formed in one piece with it, and containing a portion 
 of water into which the head of the still descends to the depth of about six 
 inches, thus forming what is termed a water-joint, which prevents the escape of 
 the gas ; e is the still head descending, as we have just stated, into the water ; 
 in the cup /is a bent funnel, through which the acid is poured into the still ; g 
 an agitator for stirring the materials in the still, working through an air-tight 
 aperture ; and h the eduction pipe, by which the gas passes into i, an inter- 
 mediate vessel, partly filled with water", and designed to arrest any uncombined 
 muriatic acid which may occasionally rise from the still during the process ; /: a 
 safety tube ; and I the pipe which conveys the gas into m, the large receiver 
 made of lead, and charged with the alkaline solution; n the agitator for con- 
 stantly stirring the alkaline solution ; this is necessary to promote the absorption 
 ot the gas ; and, in large works, the agitator is moved by power from a steam- 
 engine ; o an opening for filling the receiver, occasionally cleaning it out, &c. ; 
 p discharge cock for drawing off the saturated solution. The junction of all the 
 various pipes and openings are rendered air-tight by water-joints. At the first 
 introduction of the new process, the chlorine was obtained by distilling muriatic 
 acid upon the black oxide of manganese ; but it is now procured in a simpler 
 and more economical manner, by mixing together black oxide of manganese, 
 common salt, and diluted sulphuric acid ; various proportions are used by
 
 BLEACHING. 173 
 
 different manufacturers : Mr. Tennant recommends equal weights of salt, oxide, 
 and acid, and a quantity of water equal to the measure of acid. Silk ana 
 
 woollen goods being animal productions, different processes are employed in 
 bleaching them. The colouring principle of silk being resinous, M. Baume" has 
 proposed a process for extracting it by digesting the silk in alcohol acidulated by 
 muriatic acid, but the ordinary method of bleaching silk is the following. The 
 silk being still raw, is inclosed in a linen bag, and boiled in a solution of soap 
 for two or three hours, the bag being frequently turned. It is then taken out 
 and beaten, and next washed in cold water ; and, after being slightly wrung, it 
 is a second time put into the boiler filled with cold water, mixed with soap and 
 a little indigo, which gives it that bluish cast commonly observed in white silk. 
 When the silk is taken out of this second water, they wring it hard with a 
 wooden peg to press out all the soap and water ; after which they shake it to 
 untwist it, and separate the threads. It is then suspended in a kind of stove 
 constructed for that purpose, in which sulphur is burning, the vapour of which 
 gives the last degree of whiteness to the silk. Woollen cloths are sometimes 
 bleached by simply scouring them with soap and water after the operation of the 
 fulling mills, and sometimes by sulphuric acid gas, which is effected as follows : 
 The stuffs are first well washed and cleansed in river water, and then put upon 
 poles to dry. When half dry, they are exposed to the vapour of burning sul- 
 phur, or sulphurous acid gas, in a very close stove ; the gas gradually adhering to 
 the surface of the stuff, renders it beautifully white. An improvement upon this 
 method is to condense the sulphurous acid in water, and immerse the stuffs 
 therein ; by which means the acid acts more equally over the whole surface, 
 than when in the state of gas. The gas may also be obtained by digesting sul- 
 phuric acid upon chopped straw, saw-dust, or other carbonaceous matter, in a 
 retort, and the gas may be condensed by an apparatus similar to that used for 
 condensing the chlorine gas. High pressure steam has been lately employed 
 instead of chlorine for bleaching cloths. It is said that this method of bleaching 
 has long been practised in the east, but Chaptal is the first writer who recom- 
 mended it to the European bleacher ; and Mr. S. Wright has taken out a patent 
 in this country for an apparatus for washing and bleaching upon this principle,
 
 bleach 
 
 BLEACHING. 
 
 ,tus is represented in the annexed engraving. The goods to be 
 are first packed closely into a conical vessel, through which the steam 
 
 is caused to pass for a while ; the steam is then made to force an alkaline solu- 
 tion through the goods, to remove the impurities and colouring matter (which 
 operation is repeated as often as may be necessary) ; hot water is next im- 
 pelled through the goods to remove all the alkaline matter ; and, lastly, steam 
 of a high pressure is forced through to expel the water, by which the goods 
 
 in this vessel, the lid of which is then
 
 BLINDS. 176 
 
 B is a vessel (also of copper, as well as the other vessels and tubes repre- 
 sented), containing soap and water, or the usual alkaline solutions of pearl-ash, 
 soda, &c. ; C is a pipe leading from a steam boiler, through which is introduced 
 steam at a pressure of 50 Ibs. on the inch, which is first to be gradually admitted 
 into the apparatus, by partially opening the stop-cock a, when it passes into the 
 vessel A, where it is allowed to act upon the goods therein deposited, for half 
 an hour ; after which the cock a may be completely opened, and the full force 
 of the steam allowed to operate, first opening the cocks b, c, d, e, when the 
 steam will pass up the pipe D into the vessel B containing the alkaline solution. 
 The pressure of the steam upon the surface of the liquid in this vessel will 
 now cause it to descend through the pipe E into the vessel A, and herein the 
 stean: continuing to press, will force the alkaline liquid through the goods, satu- 
 rating every part, and carrying the dirt and other impurities to the bottom, the 
 liquid passing off through the pipe F into the receiver G underneath. The 
 pressure of steam is next employed to refill vessel B with the discharged alkaline 
 liquor ; for this purpose the cocks b, c, d, e, are to he closed, and the cocks / 
 and g, to be opened ; the steam will now pass down the pipe H, and operate 
 with its full force upon G, thereby forcing the liquid up the pipe I I again into 
 B, from whence it is again forced through the goods in the vessel A, repeating 
 the operation as often as may be necessary, in order perfectly to cleanse them. 
 The dirt, and other impurities, being removed, the next process is that of rinsing, 
 which is effected by closing the cocks b, c, d, e,f,g, and opening those at h, i, k, 
 when the steam from C passes up the pipe K into the vessel L, which is filled 
 with clean hot water ; the full pressure of the steam being now transferred to the 
 surface of the hot water, forces it through the pipe M and through the goods in 
 the conical vessel A, carrying away all the alkaline and other impurities through 
 the pipe N into the vessel O. The hot liquor in O is now to be returned into 
 L, by closing the cocks i, k, k, and opening those at /, m, when the steam 
 passes down the pipe P, and forces the liquor contained in O, up the pipe Q Q, 
 again into L, for the renewal of the operation ; this part of the process being also 
 repeated as many times as may be deemed desirable, which will depend upon the 
 condition of the goods. The next stage of the process is drying, which is effected 
 by closing all the cocks, except those at d, e, and allowing steam, at a 
 reduced pressure, to pass direct from C into the vessel A again, by which all 
 the water is driven out from the goods, leaving them nearly all in a dry state, 
 the steam passing off through the pipe F, and escaping at R. In this part of 
 the process it is necessary to observe that steam should not be employed at a 
 greater pressure than 20 Ibs. on the inch, and that its action should not be pro- 
 longed beyond the time necessary to drive off the water. For the bleaching of 
 piece goods, in lieu of the circular-sided vessel A, the patentee recommends 
 one with straight sides, diminishing downwards ; in this vessel the goods having 
 been carefully folded are to be closely packed, and, in addition to the steaming 
 and washing, by means of alkaline solutions, currents of cold air, produced by 
 a blowing machine, are to be admitted through the pipe S, which, it is said, 
 greatly assists in whitening the fabric. 
 
 BLINDS. Screens composed of various materials, and fixed in window 
 frames, either to exclude a too strong light, or to screen the interior of an 
 apartment from the observation of persons on the outside, without obstructing 
 the view of those within. The contrivances for these purposes are numerous, 
 and so well known as to require no particular description ; we shall, therefore, 
 only notice a blind for circular headed windows, as these windows are common 
 in modern churches, chapels, and public building, and the heads have hitherto 
 been either left entirely without blinds, or the blinds have been awkwardly 
 contrived, and unsightly in their appearance. Fig. 1 is an elevation of the 
 arch of a window ; a o a metal tube bent so as to fit the head of the window, 
 and serving as a circular curtain rod; this rod is open all along the upper edge, 
 as shown in the section Fig. 2 ; the ends fit into holes at b and c, made through 
 the window bar at d; at b, a pulley is fixed, corresponding with the holes and 
 bore of the bent tube a ; an endless band e e e Figs. 1 and 2 enters the tube a 
 by the end c, goes out at the other end, passes under the pulley b, then crosses
 
 176 
 
 BLOCK MACHINERY. 
 
 the window below the bar d, passes over the pulley c, and then over a spring 
 catch, or rack pulley, not shown in the drawing. In order to make the hiind, a 
 piece' of cloth is taken a little wider than the height of the arch, and rather 
 longer than its circumference, and is folded like a fan ; a nail is then passed at the 
 
 Pig- I- 
 
 bottom through all the folds into the middle of the window bar at d, forming a cen- 
 tre to the semicircular tube a a ; holes are made at the other end in the folds, which 
 allow the blind to slide along the tube ; the bottom fold is tacked to the window 
 bar near the end b ; two pieces of tape connect the upper fold with the endless 
 band by passing through the split tube as shown. The blind is drawn over the 
 window, or withdrawn from it, according as one side or other of the endless 
 band is pulled, as in the common roller blind. The inventor of this excellent 
 contrivance, Mr. H. Goode, of Ryde, Isle of Wight, was presented by the Society 
 of Arts with the Silver Vulcan Medal. 
 
 BLOCK MACHINERY. The machinery at the Royal Dock-yard, at 
 Portsmouth, invented by Mr. Brunei, for manufacturing blocks, is deservedly 
 celebrated. The following is a concise account of it. The machines are sepa- 
 rated into four classes. 1 . The sawing machine, for converting the large timber 
 into proper dimensions for the small machines to operate upon. 2. The machi- 
 nery to form the shell. 3. The sheave-forming machines. And 4. The pin- 
 forming machines. The machinery is capable of completing three sets of 
 blocks of different sizes at the same time, and is worked by two steam-engines 
 of 30-horse power each. The order of the process is this : the elm trees are 
 first cut into short lengths proper to form the various sizes of the blocks, by two 
 large sawing machines, one a reciprocating, and the other a circular saw. These 
 Jengths of trees are next cut into squares, and ripped or split up into proper 
 sizes by four sawing benches, with circular saws, and'one very large reciprocating 
 saw, which is employed in cutting up the pieces for very large blocks. The 
 scantlings of the blocks being thus prepared, the next process is that of 
 
 Making the Shells. The centre hole for the pin of the sheave is first bored by 
 a centre bit in the boring machine, whilst a number of others, corresponding to 
 the number of sheaves which the block is to contain, is bored at right angles to 
 the former, to admit the first stroke of the chisel, and, at the same time, form
 
 BLOCK MACHINER . 177 
 
 the head of the mortises. The blocks are then removed to the mortising 
 machine ; here they are firmly fixed to a movable carriage, beneath cutting 
 chisels, set in a frame moving up and down with extreme rapidity, making, 
 according to Dr. Gregory, 400 strokes per minute. Each time that the chisel 
 frame ascends, the moving carriage advances a small space, bringing a fresh 
 portion of wood under the chisel, until the mortise is cut to the proper length, 
 when the machine is stopped with the chisel frame at its highest elevation. 
 The chips cut are thrust out of the mortise by small pieces of steel projecting 
 frc-m the back of the chisels, which are also armed with two cutters, called 
 scribes, placed at right angles to the chisels, which mark out the breadth of the 
 chip to be cut at each stroke, and at the same time leave the sides of the mor- 
 tise so true as to require no further trimming. The corners of the block are 
 next taken off at a circular saw table, and it is then removed to the shaping 
 machine ; here the blocks are fixed in grooves in the peripheries of, two equal 
 wheels fixed upon the same axis, the distance between them admitting of regu- 
 lation to suit various sizes of blocks, each wheel having ten grooves, so that ten 
 blocks are shaping at once. These wheels are made to revolve with great velo- 
 city against a cutter set in a slide rest, which, moving in a curved direction to 
 the line of the axis, cuts those outward faces of the block to their required 
 figure. As soon as the tool has traversed the whole length of the block, the 
 machine is thrown out of gear, and the blocks are (without removing them) 
 each turned one-fourth part round, and another fourth-part of their surface is 
 exposed to the cutter. When the remaining portions of the surface are shaped, 
 the ten blocks are removed, and the last operation is performed by the scoring 
 machine, which, by means of a cutter, scoops out a groove round the longest 
 diameter of the block deepest at the ends, and vanishing at the central hole for 
 the pin. There only remains to remove any little roughnesses, and give the 
 surface a kind of polish, which is done by hand, and the shell is then complete. 
 Of the Sheaves. These are mostly made of lignum vitae, which is cut into 
 slabs of a proper thickness by circular saws, and then removed to a crown saw, 
 which bores the centre hole, and at the same time reduces the circumference to 
 a circular figure. The sheave is then placed in the coaking machine, which 
 forms a recess on each side of the block to receive the bush or coak, which is a 
 triangular form, with the ends rounded off. The machinery for effecting this is 
 extremely ingenious, and acts with such accuracy, and the coaks are cast so true, 
 that a single tap with a hammer is sufficient to fix the coak in its place. Three 
 holes are then drilled through the two coaks and the intervening wood, and pins 
 being inserted in the holes, they are placed under the riveting hammer, which 
 strikes the pins with a velocity proportioned to the pressure which the workman 
 exerts upon the treadle. The centres of the coaks are next broached by a steel 
 drill, and the sheave being removed to a lathe, which cuts the groove on the 
 periphery whilst it faces the sides, the sheave is completed. There remains now 
 only the iron piu, which, passing through the two sides of the shell, serves as the 
 axis on which the sheave turns. These pins are also made, turned, and polished, 
 by a machine for the purpose; so that, with the exception of strapping by rope 
 or iron, the block is now complete. The whole cost of the machinery, steam- 
 engine, buildings, interest of money, &c. was 53,000/., and which, by the saving 
 effected by the machine, was completely cleared in four years : Mr. Brunei 
 received on the whole about 20,000/. It'is calculated that the machine made 
 140,000 blocks of various descriptions per annum, from the year 1808 to the 
 conclusion of the war, which was found to be not only sufficient for the service 
 of the navy, but also of the ordnance department. 
 
 Although the foregoing account of the operations of the several machines will 
 convey to the intelligent reader a sufficiently clear idea of the whole process by 
 which the blocks are made, we doubt not that a representation of some of the 
 principal machines will be acceptable to our readers. To give engravings of 
 the whole of them would cause us to extend this article to too great a length ; 
 as, independently of the various saws by which the trees are cut up into blocks 
 and slabs of the proper dimensions, (which saws may be considered as applicable 
 to other purposes), there are a great variety of machines employed in tho
 
 178 BLOCK MACHINERY. 
 
 subsequent operations. These may be said to constitute the block-making machi- 
 nery, properly so called; and from these we have selected two of the principal, to 
 form the subject of the accompanying engravings. Fig. 1 is a side elevation of the 
 
 mortising machine, in which the mortises for the sheaves are cut. a a the bed 
 of the machine ; b & sliding carriage ; c the block to be mortised, securely held 
 in the sliding carriage by the screw e ; f one of the cutters, the number of 
 which depend on the number of sheaves the block is to contain ; g the cutter 
 frame, moving vertically in guides fastened to the two front pillars of the 
 machine, one of which pillars is removed in the figure, in order to show the 
 cutter frame ; h a guide rod attached to the upper part of the cutter frame, and 
 moving in a collar.;; k connecting rod, attached at the upper end to the cutter 
 frame, and at the crank I fixed upon the shaft m, which is driven by a strap 
 from the steam-engine passing round the drum , which is bolted to the fly- 
 wheel o. The fly-wheel is loose upon the shaft, which is attached to, or detached 
 from, the fly-wheel, by a friction-clutch p, which enters the conical interior of 
 the drum , and which is moved by the levers q q; r is a double-threaded 
 screw, by which the sliding carnage is advanced ; it works in a nut s, which 
 turns in a bearing t ; to this nut are attached the rachet-wheel v and the cog- 
 wheel w ; x a pinion acting upon w, and turned by the handle y, and only used 
 to bring the blocks under the cutters for the first cut, after which the carriage is 
 advanced by the machine in the following manner : Upon the shaft m is an 
 eccentric 1, which acts upon a roller 2 in a vertical lever 3, to the lower end of 
 which is jointed a horizontal bar 4, which has a tooth acting upon the teeth 
 of the ratchet-wheel, so thaft at each revolution of the axis the eccentric
 
 BLOCK MACHINERY. 
 
 179 
 
 thrusting out the upper end of the lever 3, moves in an opposite direction the 
 ratchet-wheel v, which, by means of the nut s, turns the screw, and advances 
 the sliding carriage, so as to bring a fresh portion of the block under the 
 cutters. When the whole length of the mortise is cut, the advance of the 
 carriage further is prevented as follows : The extremity of the bar 4 is pro- 
 longed beyond the ratchet-wheel, and rests upon the lever 5, which turns upon 
 a pin in one of the upright columns of the frame. The lever 5 is supported by 
 the curved end of the lever 6, the other end of which rests upon an adjustable 
 slide 7, which is screwed to the sliding carriage, and which is so fixed, that when 
 the mortise is completed, the long arm of the lever 6 is no longer supported by 
 the slide ; the long arm of the lever consequently descends, and, by its descent, 
 raises the lever 5, which lifts the bar 4 clear of the teeth of the ratchet-wheel. 
 Fig. 2 is a side elevation of the shaping machine ; a is a large circular rim, or 
 
 chuck, firmly keyed upon the shaft ; b a similar chuck ; c (which cannot be 
 shown in the drawing) is placed upon the shaft behind a. This chuck is not 
 made fast, but may be set upon the shaft at any required distance from a to suit 
 the diffei ent sizes of the blocks ; d d are stay bolts passing through the chucks 
 a and c, and having nuts at the back of c to retain it at the requisite distance 
 from a; ee are the blocks which are to be shaped ; they are retained between the two 
 chucks a and c, as follows :// are a number of short maundrils, set in the chuck 
 a, and each carrying on the farther end a small cross, the extremities of which 
 have two sharp steel rings ; in the chuck c is a screw, opposite to, and concentric 
 with, the maundrils //; the inner end of these screws having a sharp steel ring 
 loosely fitted upon them. Each block, in the operation of boring the holes pre- 
 vious to passing to the mortising machine, has had the line of its axis deter- 
 mined, by the marks of two steel rings impressed on one end, and of a single 
 ring upon the other. The marks of the two rings are applied to the steel ring 
 on the cross, and the ring on the screw is advanced by the screw to the single 
 mark on the other end of the block ; g is a slide rest, supported upon the bed 
 A, and attached to the radial bar .;', which turns upon a centre directly beneath 
 the line of the axis of the shaft b ; k is the bar carrying the cutter /, and sliding
 
 ISO BLOCKS. 
 
 in a mortise ; m a steel spindle, passing through a socket in k, and having a 
 small horizontal roller n fitted upon its lower end ; o one of two pillars sup- 
 porting two curved hars p q, called shapes ; the curve on one bar determining 
 the shape of the faces of the blocks, and that of the other bar the shapes of the 
 sides of the blocks, r is a lever by which the cutter bar is moved along its 
 mortise, so as to cause the roller n to press against one of the shapes p or q ; s 
 is a bar attached to the slide rest, by which the rest is made to traverse the bed 
 h, describing a portion of a circle of which the pivot of the radial bar is the 
 centre. The operation of the machine is as follows : the chucks being filled 
 with a number of blocks corresponding to the number of maundrils, the chucks 
 are set in motion by a strap from the engine passing round the drum t keyed 
 upon the shaft b. The cutter / being previously adjusted to the proper distance, 
 the attendant holding the bar * in his right hand, causes the slide rest slowly to 
 traverse the bed h, whilst, by the lever r, held in his left hand, he keeps the 
 roller n in contact with the shape p or q, and consequently causes the cutter / to 
 describe a curve similar to that of the shape ; and that face of the blocks which 
 is exposed to the cutter revolving with extreme rapidity against the cutter, is 
 cut to a corresponding shape. "When the first side is completed, the blocks and 
 the chucks are stopped, and the blocks are turned one-fourth round, so as to 
 present the next side to the cutter. This is effected by the following means : on 
 the outer end of each maundril is fixed a worm wheel v, upon which an endless 
 screw upon the outer end of the spindle w acts ; upon the other end of each 
 spindle is fixed a bevilled pinion y, gearing with a bevilled wheel x, fitted loose 
 upon the axis. When it is required to turn the block, the wheel x is locked to 
 the frame by a catch pull (not shown) and the attendant turns round the chucks 
 a and c four times, and the bevilled pinions revolving round the wheel x cause 
 the spindles on which the endless screw is cut to turn the worm wheels one- 
 quarter round. The roller n is then by a simple movement pushed down, so as 
 to act against the lower shape ; the chucks are again set in motion, and the slide 
 rest being made to traverse back over the bed, the second face is shaped, and 
 the operation is repeated for the other two sides. 
 
 BLOCKS, in the Navy, and Marine Architecture, a species of pulley very 
 extensively used for moving heavy weights, by means of ropes or chains passing 
 over the pulleys ; also occasionally in architectural and other works. A block 
 consists of one or more pulleys, called sheaves, which are generally formed of 
 lignum vitae, or some hard wood inserted between cheek-pieces forming what is 
 called the shell of the block, and turning upon a pin passing through the shell 
 and the centres of the sheaves. Blocks are of various forms, each having a par- 
 ticular name ; the following cut represents a common single block ; a is the shell, 
 b the sheave, c the pin. Blocks are suspended by straps, either of rope or iron ; 
 the latter are called iron-strapped blocks, and have frequently a swivel-hook. A 
 combination of two blocks, one of which is attached to the load to be raised, is 
 called a tackle, and the power is to be estimated by the space through which 
 the fall (which is that part of the rope to which the power is applied) passes, 
 compared with the space through which the load is raised, deducting for 
 friction, which is great, owing to the rigidity of the ropes, and the small 
 diameter of the sheaves ; these, for nautical purposes, are necessarily limited by 
 considerations as to weight and space. The friction is also considerably in- 
 creased, in certain circumstances, under which blocks are applied. When there 
 is more than one sheave in the same block, the fall comes last over the outside 
 sheave ; and that sheave, if the exertion of power be in a line nearly parallel 
 to the direction in which the load is drawn, always endeavours to get into a line 
 with the point of suspension ; for the great friction to be overcome preventing 
 the equal transmission of the power throughout the combination, and the outside 
 sheave having to sustain not only the pressure of its own share of the load, 
 but also the additional strain sufficient to overcome the friction of the other 
 sheaves, and the vis inertiae of the entire load; it must, therefore be consi- 
 derably depressed, and in consequence of this oblique direction of the block, 
 the lateral friction of the sheaves becomes so great, as in some cases nearly to 
 equal the power. Figs. 1 and 2 represent blocks so constructed as to allow
 
 BLOCKS. 
 
 181 
 
 the fall to pass over the middle 
 sheave, by which means it will be 
 immediately beneath the point of 
 suspension, fig. 1 is the invention 
 of the celebrated Smeaton, who 
 employed blocks of this description 
 in erecting the Eddystone Light- 
 house. The upper block a contains 
 6 sheaves ranged in two tiers, and 
 the lower block b contains also 6 
 sheaves, also ranged in two tiers ; 
 the lower tier of sheaves in a, and 
 the upper tier of sheaves in b, being 
 more than two diameters of the rope 
 smaller than the other sheaves, the 
 mode of reeving the rope is as fol- 
 lows. Beginning in the middle, the 
 rope is reeved over the large sheaves 
 as far as it will go; thence going 
 to the first of the smaller sheaves, 
 they are reeved throughout ; thence 
 again to the outer one of the re- 
 maining large sheaves, and ending 
 upon the middle sheave of the upper 
 block. The principal objection to 
 this method is, that it requires a 
 combination of at least twelve sheaves, and is not therefore applicable to general 
 purposes. The construction shewn in Fig. 2, which is the invention of Mr. Jones, 
 of High Holborn, can be applied to any number of sheaves from 4 upwards. 
 The cut represents a pair of blocks of 2 sheaves each. To the upper block 
 a is attached another block b, the sheave of which stands at right angles to th 
 former, and is called the cross-sheave ; the lower 
 block c contains two sheaves abreast, (shewn di- 
 verging,) in order that the cross sheave may not be 
 of a very small diameter. The method of reev- 
 ing is to begin upon the middle upper sheave, 
 and when arrived at the outer sheave, to pass to 
 the cross sheave, which carries the rope over to the 
 outer sheave, on the opposite side, and then proceed 
 again in the order of the sheaves. 
 
 The annexed figure represents an improved cat- 
 block, invented by Mr. Bothway, and rewarded by 
 the Society of Arts. The advantages which this 
 block possesses over those in common use, are 
 thus stated by Mr. Bothway. " In all large class 
 ships in the royal navy, the unwieldy nature of the 
 usual cat-block requires that two men should be 
 sent out on the anchor, a most perilous service in 
 rough weather ; whereas mine only requires one 
 man at any time, because he has not to sustain the 
 whole weight of the block, as in the former case, 
 but only that of the hook. And in vessels smaller 
 than line of battle ships, in blowing weather, when 
 the ship pitches heavily, the anchor may be hooked 
 without a man going on it, by his standing on the 
 head, and gxiiding the hook of the block to the 
 anchor, by a staff and hook, similar to a boat-hook. 
 This facility > is gained by the mobility of the 
 swivel in its socket, so that the man has not the 
 weight cf the block to turn, in order to insert the
 
 182 
 
 BLOCKS. 
 
 hook in the ring of the anchor. Should the anchor, when hooked in the dark, 
 or otherwise, cause a turn in the fall, the hook being on a swivel joint, the turn 
 will come out before the strain comes on the block ; and when the anchor is 
 foul it can also be hooked with great facility. In my thirty-two years' service 
 I have seen the wooden cat-blocks swell so much in cold climates, that the 
 sheaves have become immovable ; mine, being of metal, are liable to no such 
 inconvenience." Another great advantage may be derivable from Bothway's 
 cat-block being applicable to other uses ; whereas the old ones are not. For 
 instance, by merely having a spare socket or two fitted with hooks of various 
 sizes, it may take a strap for gear-blocks, or it may be converted into a lashing- 
 block without the hook and socket, but with the socket bolt. In the figure, 
 which represents a perspective view of the block, it will be seen that the hook, 
 instead of being formed in one with the strap, turns with a swivel head, in a 
 socket which hangs from a pin passing through the lower end of the shell. 
 Although entirely formed of metal, they are lighter than wooden ones with 
 their iron bindings, and capable of the same service. 
 
 There is another species of blocks, which are termed "Dead eyes" and are 
 used for tightening or setting up, as it is called, the standing rigging of ships. It 
 consists merely of a circular block of wood, with a groove on its circumference, 
 
 Fig. 1. 
 
 Fig.*. 
 
 round which the lower end of the shroud, or an iron strap, is fastened ; three 
 
 holes passing through the face, (ranged in a triangle,) to receive the laniard 
 
 or smaller rope, which forms a species of tackle for tightening the shrouds. 
 
 There are no sheaves in the dead eye, but the edges of the 
 
 holes are rounded off to prevent cutting the laniard, but this 
 
 very imperfectly answers the purpose ; as from the roughness 
 
 of the grain of the wood, which is usually elm, and from the 
 
 stiffness of the rope, the laniard renders with difficulty, and 
 
 from the great strain to which it is subjected, it is frequently 
 
 broken. A very simple and effectual improvement has been 
 
 made in this respect by Mr. Carey, Surveyor of Shipping, 
 
 at Bristol, by inserting a half sheave of lignum vitae into each 
 
 of the holes, which causes the laniard to render with greater 
 
 facility, and the shroud to be set up in half the usual time. 
 
 Fig. 1 shews the dead e>e ; Fig. 2 a section of the same ; 
 
 and Fig. 3 one of the half-sheaves. It will be seen from the 
 
 manner of inserting the half sheaves, as shown in Fig. 2, that 
 
 they cannot faL 1 out, for the more pressure there is on them, 
 
 the faster they will be. 
 
 The annexed figure represents a block of a peculiar 
 description, intended for forming a kind of rope-road to a 
 stranded ship. When a vessel thus circumstanced has had 
 a rope thrown over by Capt. Man by 's apparatus, or any other 
 means, considerable difficulty has been found in reeving an 
 ordinary pulley for the conveyance of the crew to the shore. 
 In the figure, it .will be seen that the pulley divides at the 
 hook, or shackle, into two equal parts, so that it may be
 
 BLOWING MACHINES. 183 
 
 instantaneously passed on to a stretched rope, and, by means of a cord from 
 the ship, persons may pass securely and quickly backwards and forwards. 
 The little bar which traverses the opening is fixed at one end by a joint 
 and fits into a mortise, as shown ; the use of it being to confine the rope 
 in its place, when any vehicle, or other apparatus, is slung or suspended 
 to it. 
 
 BLOOD. The principal use of blood in the arts is for making Prussian blue, 
 or sometimes for clarifying certain liquors. It is also recommended in agriculture, 
 as an excellent manure for fruit trees. A mixture of blood with lime makes an 
 exceedingly strong cement ; and hence its use in the preparation of some che- 
 mical lutes, the making floors, &c. 
 
 BLOOM. A mass of iron after having undergone the first hammering, 
 called bloomary. It requires many subsequent hammerings or rollings to render 
 it fit for smiths' use. See IRON. 
 
 BLOTTING PAPER. A species of paper made without size, serving to 
 imbibe the wet ink in books of account, &c. See PAPER MAKING. 
 
 BLOWING MACHINES. Machines employed for producing a rapid com- 
 bustion of fuel, by furnishing a more copious supply of air than can be obtained 
 by the mere draft of the ordinary chimneys. Although the common bellows is 
 undoubtedly a blowing machine, yet the term is generally restricted in its appli- 
 cation to those machines which are employed at large furnaces, as in foundries 
 forges, &c. Blowing machines are constructed of various forms, the great 
 object in all being, that the blast should be as continuous and uniform as possible. 
 The method of producing such blast by a centrifugal force has long been known, 
 out the first blowing machine on this principle, of which we have a distinct 
 account, is that invented by Mr. Teral, in 1729. It consists of a number of 
 vanes or fanners, radiating from a horizontal shaft, and enclosed within a cylin- 
 drical box, having two apertures at opposite sides of the cylinder, to one of 
 which is fitted a conical pipe leading to the furnace, whilst the air enters by the 
 other aperture, and the shaft being turned with great rapidity, a copious and 
 uniform current of air may be impelled through the conical pipe to the furnace. 
 From the great simplicity and cheapness of these machines they have recently 
 been coming into more general notice. 
 
 Another kind of blowing machine, and which is very extensively used for 
 smiths' forges, is the double bellows. This machine in form resembles an ordi- 
 nary single bellows, but is divided into two parts by a middle board, similar to 
 the bottom board, and like it furnished with a valve opening upwards. The 
 upper and under boards are each loaded with weights, which compress the upper 
 and distend the lower compartments, and the middle board is supported in a 
 horizontal position upon a frame. The pipe or nozzle of the bellows commu- 
 nicates with the upper compartment of the bellows only whilst the air is admitted 
 by the valve in the lower compartment. The action of the machine is as 
 follows : The lower board being raised by the brake or handle, the air contained 
 in the lower compartment is driven through the valve in the middle board into 
 the upper compartment, and not escaping from it through the nozzle, as fast as 
 it is forced into it, it elevates the upper board, and thus distends the upper com- 
 partment. Upon the descent of the lower board, the valve in the middle board 
 closes, and the upper board descending by the pressure of the weights upon it, 
 the air beneath it is urged through the nozzle in a continuous current. During 
 the descent of the lower board, the air enters by the valve in the board, and fills 
 the lower chamber of the bellows ; and upon the rise of the board it is forced 
 into the upper chamber as before, and thus a continuous blast is maintained. 
 But although continuous, it is not quite equal, or of a uniform force ; for during 
 the up-stroke the air is compressed by a force exceeding that of the weights on 
 the upper board, since it causes the upper board to ascend ; but upon the descent 
 of the lower board, the air is expelled by the pressure of the weights alone, 
 which, being at all times the same, the current is then nearly uniform. 
 
 Another species of blowing machine is the water bellows, invented by 
 Hornblower, several of which machines have been erected in various parts of 
 the country. The nature of these machines will be readily understood by the
 
 184 
 
 BLOWING MACHINES. 
 
 help of the following diagram 
 The side figure 13 a vertical 
 section of the machine, a is 
 the fulcrum of the lever or 
 beam, with two inverted vessels 
 b and c suspended from its ex- 
 tremities ; these vessels are 
 open underneath, but air-tight 
 above, d and e are two larger 
 vessels, filled with water to the i 
 same level in which the vessels j 
 b and c rise and fall alternately, j 
 ff h i is a tube or pipe, which j 
 passes through the vessels d and 
 e, and reaches above the surface 
 of the water ; at the extremities are two valves, (omitted by mistake) which 
 respectively open outwards into the inverted vessels, with a pipe at h open to 
 the atmosphere, k and / are pipes passing through the bottom of d and e, and 
 extending a little above the surface of the water; they are open at top, and have 
 valves at bottom opening into the trunk o, to which the pipe is fitted which con- 
 ducts the blast to the furnace. An alternating motion being imparted to the 
 beam by a steam engine or other first mover, the air passes up the tubes g h i 
 and fills each inverted vessel as they are successively drawn up out of the water ; 
 the descent of the inverted vessel closes the valves at g and i, and opens those 
 at the bottom of the tubes k and /, through which the air is driven forward by 
 the trunk o, and thus, by the reciprocation of the beam, a continual blast is 
 maintained through the trunk o and the tuyere of the furnace. 
 
 But the most perfect blowing machines are those in which the blast is pro- 
 duced by the motion of pistons in a cylinder. The annexed engraving represents 
 a blowing machine of this description, erected by Mr. Paterson, of Lanark. It 
 consists of two double acting force pumps, placed at right angles to each other, 
 to equalize the draft ; they are driven by a water-wheel of 5-horse power, a is 
 
 the vertical cylinder j b the horizontal cylinder; cc two connecting rods united 
 to the crank d ; e the working beam ; / the parallel motion ; g the pipe for con- 
 veying the blast to the cupola or furnace h; is. small wheel, running in a groove 
 in a cast iron plate ; j frame supporting the vertical cylinder, between which the 
 lowermost connecting rod c passes. At k k are placed valves, to admit the air 
 into the vertical cylinder; similar valves are placed at the ends of the horizontal 
 cylinder into it The operation is simply this : by the revolution of the crank 
 the air is drawn in at each end alternately of both cylinders, and at the same 
 time it is forced out at the opposite extremity along the pipe g into the furnace ; 
 and the cylinders being placed at right angles, one piston will be moving with 
 its greatest velocity whilst the other is moving with its least velocity, by which 
 means the blast is rendered nearly uniform, and an air chamber or reservoir 
 rendered unnecessary. The first cylinders of magnitude used as blowing 
 machines, were erected by Mr. Smeaton, in 1760, at the Carron Iron Works, 
 the cylinders being four in number, 4 feet 6 inches in diameter, and the piston 
 making a stroke of 4 feet 6 inches in length ; but the blowing machine lately
 
 BLOW PIPES. 185 
 
 erected at the Smithery, in the Royal Dockyard at Woolwich, is perhaps the 
 most powerful and the most complete in the kingdom. 
 
 In this machine there are three blowing cylinders, of 4 feet 8 inches diameter, 
 with a stroke of 4 feet 8 inches, and each cylinder making 20 strokes per 
 minute, expelling near 5000 feet of air per minute. Over the wind chest is 
 fixed a regulating cylinder, which has no bottom, being open to the wind chest; 
 and its piston, which weighs 700 Ibs. serves only to regulate the pressure, which 
 amounts to about Ib. per square inch. When the pressure exceeds this, the 
 piston rises, and opens an escape valve at the back of the cylinder. 
 
 BLOW PIPE. An instrument for exciting intense combustion upon a small 
 scale ; it is extensively used in many branches of the arts, and also in philoso- 
 phical experiments upon metallic substances. In its simplest form it is merely 
 a conical brass tube, curved at the small end, in which is a very minute aperture ; 
 and a stream of air being urged through it by the mouth against the flame of a 
 lamp or candle, a heat equal to that of the most violent furnaces may be pro- 
 duced. The body intended to be operated upon should not exceed the size of a 
 peppercorn, and should be supported upon a piece of well-burned close-grained 
 charcoal, unless it be of such nature as to sink into the pores of the charcoal, 
 or to have its properties affected by its inflammable quality. Such bodies may 
 be placed in a small spoon made of pure gold, silver, or platinum. Many 
 advantages may be derived from the use of this simple and valuable instrument. 
 It is portable ; the most expensive materials, and the minutest specimens of 
 bodies, may be used in the experiments ; and the whole process is under the eye 
 of the observer. In the blow pipes used by enamellers, glass-blowers, and 
 others, the current of air is maintained by a small pair of double bellows. 
 
 Early in the present century, Dr. Hare, of Philadelphia, made a most im- 
 portant improvement in the blow pipe, by substituting for the flame of a lamp 
 that arising from a mingled current of oxygen and hydrogen, by which means 
 he succeeded in producing a more intense heat than had ever been obtained 
 before, except by the concentration of the sun's rays in very large and powerful 
 lenses. As these gases, however, can only be procured by chemical means, a 
 more perfect method of supplying the currents of gas than by means of the 
 common bellows became desirable, on account of the great leakage of the 
 latter, and the Doctor, turning his mind to the subject, devised a machine 
 equally applicable for supplying either oxygen gas or common air. This machine, 
 which he denominated the Hydrostatic Blow Pipe, is represented in the annexed 
 engraving, of which the following is an explanation. 
 
 The Hydrostatic Blow Pipe consists of a cask, divided by a horizontal diaphragm 
 into two parts D D. From the upper apartment, a pipe of about 3 inches dia- 
 meter (its axis coincident with that of the cask) descends, until within about 
 6 inches of the bottom. On this is fastened by screws, a hollow cylinder of 
 wood B B, externally 12 inches in diameter, and internally 8 inches. Around 
 the rim of this cylinder a piece of leather is nailed, so as to be air-tight On 
 one side a small groove is made in the upper surface of the block, so that a 
 lateral passage may be left when nailed on each side of the groove. This lateral 
 passage communicates with a hole bored vertically into the wood by a centre 
 bit ; and a small strip of leather being extended so as to cover this hole, is 
 made, with the addition of some disks of metal, to constitute a valve opening 
 upwards. In the bottom of the cask there is another valve opening 
 upwards. A piston rod, passing perpendicularly through the pipe from the 
 handle h, is fastened near its lower extremity to a hemispherical mass of lead 
 L. The portion of the rod beyond this proceeds through the centre of the 
 leather which covers the cavity of the wooden cylinder, also through another 
 mass of lead like the first, which, being forced up by a screw and nut, subjects 
 the leather between it and the upper leaden hemisphere to a pressure sufficient 
 to render the juncture air-tight. From the partition, an eduction pipe E is carried 
 under the table, where it is fastened by means of a screw to a cock which 
 carries a blow-pipe, so attached by a small swivel joint, as to be adjusted in any 
 required direction. A suction pipe passes from the opening covered by the 
 lower valve, under the bottom of the cask, and rises vertically close to it on the
 
 186 BLOW PIPES. 
 
 mtside terminating in a union joint for the attachment of any flexible tube 
 whkh mayTe necfssary. The apparatus being thus arranged and the casK 
 uinith water until the partition is covered to abou the depth of 2 inches, 
 tf Etaon be lifted, the leaker will be bulged up, and will remove m some 
 atmospheric pressure from the cavity beneath it, consequently the 
 r through the lower cavity to restore the equilibrium. When the 
 
 piston is depressed, the leather being bulged in an opposite direction, the cavity 
 beneath it is diminished, and the air being thus compressed, forces its way 
 through the lateral valve into the lower compartment of the cask, which com- 
 partment being previously full of water, a portion of the fluid is pressed up 
 through the pipe into the upper apartment. The same result ensues each time 
 that the stroke is repeated, so that the lower compartment soon becomes filled 
 with air, which is retained by the cock until its discharge by the blow pipe is 
 necessary. Dr. Hare, in his oxy-hydrogen blow pipe did not mix the gases in 
 nis gas reservoir, but supported the flame of the hydrogen by a current of 
 oxygen issuing from different jets. Subsequently, it was found that the heat pro- 
 duced was materially affected by the proportions in which the gases were mixed, 
 and that the greatest intensity of heat was obtained by two volumes of hydrogen 
 united with one of oxygen ; and various attempts were made to mix and burn 
 the gases in their due proportion, but with little success, until the important im 
 provement effected in the instrument by Dr. Clarke, Professor at Cambridge. 
 This improvement consisted in first mixing the gases in a bladder, in the exact 
 proportions to form water, and afterwards condensing them in a strong iron 
 chest, by means of a condensing syringe. To an opening at the end of this chest 
 he attached a great number of layers of fine wire gauze, through which the 
 mixed gases were driven by their elastic force into a small tube, at the end of 
 which they were inflamed. By this arrangement he obtained a much greater 
 heat than had been effected by Dr. Hare's invention, and was enabled to make 
 a great number of experiments highly interesting to science. Unfortunately, 
 however, for the general adoption of his plan, it was soon found that his in- 
 strument was unsafe to use ; that the wire gauze would not prevent the explosion 
 of the gases; that in several cases, when used by the most experienced and 
 cautious operators, tin- instruments were burst. The explosions were tre- 
 mendous, and resembled the bursting of a bomb, the fragments of the iron
 
 BLOW PIPES. 187 
 
 chest being scattered with great force m all directions. After trying various 
 plans to render the invention safe, the Doctor, as a protection, had the iron chest 
 placed behind a brick wall at the back of the operator, the gases being conveyed 
 through a tube passing through the wall. In this state the instrument remained, 
 until Mr. Goldsworthy Gurney applied himself to its improvement, and after 
 numerous experiments, which are highly interesting, and are fully detailed in 
 his published lectures, he succeeded in producing an instrument unattended with 
 the slightest danger in its use, and admirably adapted both for scientific inves- 
 tigation, and for various operations in the arts. The annexed engraving is a 
 
 representation of the instrument. A is the safety chamber ; B a water trough, 
 through which the gas is made to pass from the gasometer D by the cock C, 
 through a tube which reaches to the bottom of the water trough ; E is a cock 
 fitted into the neck of the same, from which it is thrown out should an explosion 
 take place on the surface of the water. F is a gauge, to indicate the necessary 
 height of the column of water in the trough. G is a transferring bladder, which 
 is made to screw and unscrew to and from the stop-cock H, for the purpose of 
 supplying the gasometer with gases, which may be charged and recharged at 
 pleasure, by an assistant, during its action, so as to keep up the most intense 
 flame for any length of time. A valve is placed between the gasometer and the 
 transferring bladder, which prevents the return of the gas. I I is a light 
 wooden or stiff pasteboard cap, which combines sufficient strength with great 
 lightness, so that in case an explosion of the gasometer should happen, it is 
 merely thrown a short height into the air, by the force breaking the strings 
 which connect the cap to the press board. To these strings are attached small 
 wires, which pass through the table of the instrument, as at L, into the press- 
 board below, where they are secured ; this press-board is kept in a horizontal 
 position by the stand, so that when the requisite ~ * '" 
 
 I I is brought to bear equally on the gasometer D. The gasometer bladder (or 
 silk bag) is tied to a piece of bladder, which screws into a long tube laid into 
 and across the table, which permits it to be unscrewed at pleasure from the body 
 of the instrument, and immersed in water when it requires softening, affording 
 also the means of fixing on another bladder, if any accident should render it 
 necessary. The stop-cock of the charging bladder G is fixed to one end of the 
 tube just described, and the stop-cock of the water trough on the other end. To 
 operate with this instrument, pressure by the hand is applied to the press-board, 
 which draws down the cap I I on the gasometer D, and forces the gas which it 
 contains through the stop-cock C, and through the water tube and safety chamber 
 A, to the jet at the end, where it is burned. When the pressure on the press- 
 board is too slight, or when the hand is taken off, the flame returns into the 
 safety chamber, and is extinguished. When it is required to suspend the ope- 
 ration, the hand need only be taken off the pressing board, the water in the 
 trough acts as a self-acting valve in preventing the escape of gas from the 
 instrument, and saves the necessity of turning the stop-cock. A silk tube is 
 attached to the end of the tube before described, in the water trough, which
 
 188 
 
 prevents the splashing of the water, sometimes occasioned by unskilful manage- 
 ment We omitted to state that the safety chamber A is filled with numeroui 
 discs of very fine wire gauze closely packed, and should the flame be driven in, 
 which will sometimes happen, it will not enter the bag or reservoir D, but will 
 explode above the surface of the water in the chamber B, merely driving out 
 the cork. An improvement has, however, been since introduced in the con- 
 struction of the safety chamber, by Mr. Wilkinson, of Ludgate-hill, by which 
 the retrogade motion of the flame appears to he effectually prevented, and a 
 much larger jet may be employed than heretofore with perfect safety. This im- 
 provement consists in filling the chamber A with alternate layers of wire gauze 
 and of asbestos, previously beaten with a mallet, and pulled out to resemble floss 
 silk. Mr. Wilkinson received from the Society of Arts a silver medal, for his 
 communication on the subject, and we understand that Mr. Hemming has 
 recently made some further improvements in the construction of the instrument. 
 We must here advert to the wonderful effects produced by the oxy-hydrogen blow 
 pipe, which almost instantaneously reduces the hardest and most refractory sub- 
 stances. Gun flints are instantly fused by it, and formed into a transparent glass ; 
 china melts into a perfect crystal. All kinds of porcelain are readily fused, pre- 
 viously assuming a beautiful crystallized appearance. Rock crystal is quickly 
 melted, giving out a beautiful light. Emerald, sapphire, topaz, and all the 
 other precious stones, melt before it into transparent glassy substances. Barytes, 
 strontian, lime, and alumina, exhibit very striking and beautiful phenomena. 
 Magnesia fuses into hard granular particles, which will scratch glass. The 
 metals, even platina, are all quickly fused by it ; and all descriptions of stones, 
 slates, and minerals, are melted, sublimed, or volatilized, by its all-subduing power. 
 
 BLUBBER, in Physiology and Commerce, the fat which invests the bodies 
 of all large cetaceous fishes, serving to furnish an oil. The blubber lies imme- 
 diately under the skin, and over the muscular flesh. In the porpoise it is firm 
 and full of fibres, and invests the body about an inch thick. In the whale its 
 thickness is ordinarily 6 inches, but about the under lip it is found two or three 
 feet thick.. The quantity yielded by one of these animals ordinarily amounts to 
 forty, or fifty, sometimes to eighty or more hundred weight. Its use in trade and 
 manufactures is to furnish train-oil, which it does by boiling down. Formerly 
 this was performed ashore in the countries where the whales were caught, but 
 lately the fishers do not go ashore ; they bring the blubber home stowed in 
 casks, and boil it down there. A machine expressly designed for expressing the 
 oil from blubber is given under the word OIL. 
 
 BLUE (PRUSSIAN). A very fine blue pigment, extensively used in the arts. 
 It is composed of prussiate of iron, and the earth precipitated from alum or 
 pure alumine. It is commonly obtained by calcining blood or other animal 
 substances, as hoofs, horns, parings of leather, &c. by which a black coaly resi- 
 duum is obtained. Three parts of this are added, at intervals, to four parts of 
 potash, kept in a state of fusion in a stout iron vessel, the mixture being con- 
 stantly stirred during the process. At first a reddish flame appears upon the 
 surface of the mass ; this afterwards changes to a bluish tinge, denoting the 
 formation of prussiate of potash, when the whole is to be removed as speedily 
 as possible into a large vessel of boiling water, and stirred, to promote the dis- 
 solution of the prussiate of potash. After allowing the dregs to settle, the clear 
 liquor is drawn off, and fresh quantities of water boiled upon the residuum, until 
 it ceases to impart much taste to the water ; and the whole of the liquor thus 
 obtained being mixed together, a solution of alum and green vitriol is added, when a 
 precipitate of Prussian blue is immediately formed, which is washed repeatedly to 
 free it from the sulphate of potash ; after which it is put into bags and pressed, 
 and then exposed to the air to dry, during which process it assumes a deeper 
 colour, and acquires a hard stony consistence. 
 
 BLUE (POWDER or STONE), used in washing linen, is the same with smalt, 
 either in the lump or powder. When the smalt is taken from the pot, it is 
 thrown into a large vessel of cold water ; this makes it more tractable, and more 
 easily powdered. When examined after cooling, it is found to be mixed with a 
 greyish matter resembling ashes, which must be separated by washing and
 
 BOATS 189 
 
 then the blue substance being powdered and sifted through fine sieves, forms 
 what is called powder blue. 
 
 BLUE (SAXON). The best Saxon blue may be prepared as follows : mix 
 I oz. of the best powdered indigo with 4 oz. of sulphuric acid in a glass bottle 
 or matrass, and digest it for one hour in a water bath, shaking the mixture at 
 different times; then add 12 oz. of water to it, stir the whole well, and when 
 cold, filter it. 
 
 BOAT. A small vessel for the conveyance of goods or passengers to short 
 distances, and which may be impelled either by oars or sails at pleasure. They 
 are for the most part open or without decks ; but the varieties in their form and 
 construction, according to the purposes for which they are intended, are so 
 great as to preclude enumeration. Boats always fonn part of a ship's equipment ; 
 
 the number depending upon the size of the vessel, and the service for which it 
 is intended. Of these the cutters, gig, and jolly boat, are principally employed 
 for the conveyance of officers and crews on any service ; and the long boat or 
 
 launch, for the conveyance of heavy stores of every description to and from the 
 vessel. The engraving represents an improvement in this latter class of boats, 
 when employed for laying out and weighing heavy anchors, and for landing 
 and embarking cannon. The usual mode of laying out anchors by means of 
 a ship's launch is, to place the anchor over the boat's stern, and to coil the cable 
 on the gunwale ; but this lumbers up the boat, overloads it, and exposes it to the 
 danger of being swamped in a high sea. To obviate this, attempts have been 
 made to sling the anchor beneath the boat, as near as possible in the centre of 
 gravity of the boat ; none of these, however, succeeded so as to encourage their 
 adoption. Subsequently, Mr. Cow (master boat-builder of the Royal Dock, at 
 Woolwich,) devised the present arrangement, which was so much approved by 
 the Navy Board, that they have directed that every ship of war of a certain 
 class shall be furnished with a launch fitted on Mr. Cow's principle, and the 
 Society of Arts have rewarded him with a gold medal for the invention. The 
 former method (alluded to above) for carrying an anchor under a boat's bottom, 
 was to have only one fixed trunk, which was in the middle of the boat, close to 
 the side of the keel; the windlass, therefore, could only be supported at the 
 ends, and was unequal to the heaving up any great weight ; the great strain also 
 was entirely on the sides of the boat. By Mr. Cow's plan there are two movable 
 trunks at a proper distance from the keel, thereby allowing a strong stanchion 
 to be placed on the kelson, which stanchion supports the middle of the windlass, 
 and consequently makes it of sufficient strength to weigh any weight that the 
 boat is able to sustain. Fig. 1 pives a perspective view of <i 74-pun ship's 
 
 Fig. I. 
 
 launch, with a bower anchor suspended under the bottom, and a bower cable 
 coiled into the boat, a is the cable ; b b the anchor ; c c the buoy rope ; d a
 
 190 BOATS. 
 
 rope by which the anchor is hove up when weighing, or suspended when 
 carrying, by the windlass. Fig. 2 gives a mid-ship section of the launch, with 
 two32-pounders suspended from the windlass. 
 h h the guns lashed to wooden slides; Hi 
 ropes by which the guns are hove up to the 
 boat's bottom ; k k water-tight removable 
 wood trunks, through which the ropes pass to 
 the windlass; //the windlass in two parts 
 connected by a wrought iron gudgeon and 
 socket ; m a removable strong wrought iron 
 stanchion, which supports the middle of the 
 windlass. The application of the invention 
 to the purpose of landing and embarking 
 heavy guns is also of great importance, as Tt\ 
 
 it enables this operation to be conducted 
 on a beach with perfect safety to the men and boats, at times when the surf 
 is so great as to preclude the possibility of boats approaching near enough to 
 land or to embark in the usual way ; for the boat (with two guns suspended 
 one on each side of the keel, as shown in Fig. 2) being brought to anchor 
 without the surf, a small line is the only connexion necessary with the shore, 
 by which line the larger hauling ropes are conveyed, which being made fast 
 to the guns, the latter are lowered from the boat, and hauled upon the 
 beach. Should the operation be carried on where there is a rise and fall of 
 the tide, and the guns should not be immediately wanted, it will be only neces- 
 sary to take the boat in at high water, and drop the guns, which may be 
 taken up as the tide leaves them ; in either case the boat is fit for any other 
 service, without risk of damage by being kept afloat. The interior of the boat 
 is kept clear for stowing the carriages and other stores. The embarking of 
 guns is performed in the same way, care being taken to have anchors of suffi- 
 cient power to moor the boat withput the surf, so as to counteract the weight of 
 the guns, and the resistance it meets with in being hauled off from the shore. 
 Boats and small vessels are son*times built flat-bottomed, to allow of their 
 going into shoal water when required; and in order that they may carry 
 a sufficient quantity of sail, and to prevent their making lee-way, they are 
 fitted with what are termed sliding keels. These were first introduced into this 
 country by Admiral Schank, at whose instance a government vessel, which was 
 destined for a surveying vessel at New Holland, was fitted with them. These 
 sliding keels consisted of three stout planks, descending through water-tight 
 wells to a considerable depth below the ship's bottom, and fitted with apparatus 
 for raising or lowering them at pleasure. The narrow edge of the plank being 
 in the line of the vessel's keel, presented but little resistance to the vessel's 
 sailing, whilst the pressure of the water upon the broad surface of the keels 
 tended to counterbalance the effect of the wind upon the sails, to depress the 
 ship, and materially lessened the rolling, and also prevented the vessel going 
 to leeward, as she must otherwise have done, owing to her extreme light draft 
 of water. Although a favourable report was made of the invention, it was 
 never very generally adopted, but it has since been made the subject of a patent, 
 under a somewhat different form, by Moncrieffe Willoughby, Esq. In his 
 arrangement a sliding keel of iron, made very massive, is firmly attached to 
 strong perpendicular iron bars, which are made to slide up and down in water- 
 tight grooves made through the centre of the hull, thus permitting the keels to be 
 projected to any required depth in the water, and to be drawn up at pleasure 
 by means of a simple rack and pinion worked by a winch upon the deck. The 
 sliding keel is further secured or supported by four chain stays, two on each 
 side, which pass over the gunwales, and are tightened on board. Fig. 1 is a 
 side elevation of a vessel fitted with a sliding keel on Mr. Willoughby's con- 
 struction. Fig. 2 a cross section of the vessel, through one of the water- 
 tight trunks of which the suspending bars pass. Fig. 3 a cross section, 
 exhibiting the guys or stays attached to the sliding keel. In Fig. 4 the ballast 
 keel in front of the suspenders is cut off, for the purpose of preventing the
 
 BOATS. 
 
 191 
 
 Fig. I. 
 
 sollection of sea weeds, which would impede the vessel's sailing. The sketch 
 of a patent ballast-keeled lugger under a press of sail requires no elucidation, 
 except to remark that the portion below the boundary line of the water repre- 
 sents the keel under water. Lieut. R. Shuldham's metallic sliding keel resembles
 
 1&2 
 
 BOATS. 
 
 the common lee board in its shape, and is shown in the annexed diagram, a 
 represents the sliding keel lowered down into the water ; the dotted line b the 
 
 iccess into which the keel is raised or deposited when not used ; c the joint or 
 fulcrum upon which it turns on being raised or lowered. One great objection 
 to the plans of sliding keels is, their interfering with the keel and floor timbers, 
 which must be cut through, thereby weakening the vessel; for instance, in 
 Lieut. Shuldham's plan, the keel must be cut through longitudinally, or formed 
 into two parts throughout nearly the whole length of the vessel, or at least 
 through a portion as long as the sliding keel ; they are also liable to be carried 
 away, owing to the powerful leverage they afford to the water, and the difficulty 
 of staying them sufficiently, without forming an obstruction to the speed of the 
 vessel. The annexed engraving represents a simple plan for preserving the 
 tholes or rowing pins of a boat, the loss of which is not only teasing, but often 
 productive of serious inconvenience. Fixed tholes cannot be well used when 
 
 boats are to be hoisted in alongside, as they are subject to be broken ; they are 
 also often inconvenient in getting in water casks, as well as in many other 
 cases. Hence pins which can be unshipped are preferred ; these are often lost, 
 and the want is not always discovered until it cannot be replaced ; or it is not 
 replaced without a loss of that time which is so valuable at sea. Very often, 
 also, the delay of a minute is rendered inconvenient or even dangerous when 
 the boat is dragging alongside by the painter in a heavy sea, and the vessel is 
 either drifting or standing on. The drawing requires little explanation. By 
 pulling at the lower ^in the two upper ones are fixed at once, and on being 
 unshipped they hang~secure from loss, while the lower one serves as a spare 
 thole should any be broken. 
 
 Before we close this article we must briefly notice Mr. Clint's ballasted masts 
 for small sailing vessels, the object of which invention is to enable the boat 
 constantly to retain an upright position, the mast alone yielding to the force of the 
 wind. Fig. 1 is a section of the vessel, and Fig. 2 a plan of the same, a represents 
 the hull of the vessel ; b an oblong caisson of a semicircular section, suspended 
 at each end upon pivots in the deck beams, at the point c. The mast is stepped 
 in a trunk in this caisson, and secured by shrouds brought down to the sides of 
 the caisson, and by a fore-stay proceeding to the stern of the vessel, and by a 
 back-stay to the stern. The ballast is placed evenly in the bottom of the 
 caisson. Among the advantages claimed by Mr. Clint for this construction are, 
 first, perfect safety, as he considers it impossible a vessel can ever capsize. 
 Secondly, the vessel being always upright, is constantly on what are termed her 
 lines, and is always in trim, whereby she will sail faster and go better to wind- 
 ward ; and lastly, that the ballast being suspended in air, is of mrre effect than
 
 BOATS. 
 
 Kfr.l. 
 
 Fig. 2. 
 
 ballast placed in the bottom, 
 which latter being identified 
 with the vessel in the water, 
 loses as much of its weight 
 as is equivalent to its bulk 
 of water, whilst the sus- 
 pended ballast retaining its 
 whole weight, a smaller 
 quantity will be required 
 to steady the mast, and the 
 vessel itself requiring none, ' 
 a great degree of buoyancy 
 is obtained. Mr. Clint con- 
 structed a small vessel on 
 this principle, and made a 
 regular series of experi- 
 ments during the summer 
 of 1825, in presence of a 
 number of scientific per- 
 sons, and officers and sea- 
 men of the navy, some of 
 whom accompanied him to 
 Gravesend, when it blew 
 fresh ; and from the great satisfaction given by its performances, the Society of 
 Arts voted Mr. Clint their large medal, or twenty guineas. This invention is 
 only intended for such vessels as are not employed in carrying cargoes, of which 
 class are revenue cutters, pleasure yachts, &c. ; nor is it intended for vessels 
 above seventy tons, which may have the box decked in. 
 
 BOAT (LIFE). A boat invented by Mr. Henry Greathead, of South Shields, 
 for the purpose of preserving the lives of shipwrecked persons ; and so well has 
 it answered, and indeed, exceeded, every expectation in the most tremendous 
 broken sea, that since its invention not fewer than 200 lives have been saved at the 
 entrance of the Tyne alone, which otherwise must have been lost; and in no 
 instance has it failed. The principle of this boat appears to have been suggested 
 by the following simple facts : Take a prolate spheroid and divide it into 
 quarters, in the line of its longer axis ; each quarter is elliptical, and nearly 
 resembles the half of a wooden bowl, having a curvature with projecting ends; 
 this being thrown into the sea or broken water, cannot be upset, or lie with the 
 bottom upwards. The length of the boat is 30 feet, the breadth 10 feet, the 
 depth from the top of the gunwale to the lower part of the keel amidships, 3 feet 
 3 inches ; from the gunwale to the platform within 2 feet 4 inches ; from the 
 top of the sterns (both ends being alike) to the horizontal line of the bottom of 
 the keel 5 feet 9 inches. The sides from the under part of the gunwale along 
 the whole length of the regular shear extending 21 feet 6 inches, are cased with 
 layers of cork to the depth of 1 foot 4 inches downwards, and the thickness at 
 the top 4 inches, projecting a little without the gunwale ; the cork on the out- 
 side is secured with thin plate or slips of copper, and the boat is fastened with 
 copper nails. The thwarts or seats are five in number, double banked, that is, 
 two rowers sit upon each thwart, so that the boat can be rowed by ten oars. 
 The side oars are short, with iron tholes and rope grommets, so that the rower 
 can pull either way. The boat is steered by an oar at each end, and the steering 
 oar is one-third longer than the side oars. The platform along the bottom is 
 horizontal, the length of the midships, and elevated at the ends for the con- 
 venience of the steersman. The internal part of the boat next the sides, from 
 the under part of the thwarts down to the platform, is cased with cork, the 
 whole quantity of which affixed to the life-boat is nearly 7 cwt. The parti- 
 cular construction of this boat will be best understood by referring to the 
 engraving, Fig. 1 representing a cross section of the boat, and Fig. 2 a longi- 
 tudinal elevation. F F the outside coatings of cork ; G G the inside cork 
 fittings ; H H the outside planks of the boat ; I I the stems ; K the keel
 
 191 
 
 BOATS. 
 
 N N timber heads ; P the thwarts, or rowers' seats ; R stanchion to support 
 the thwart ; S section of a gang-board, which crosses the thwarts and forms 
 the passage from one end of the boat to the other. T the platform for the 
 rowers' feet ; U U the two bilge pieces, nearly level with the keel ; W W the 
 
 Fig 1 
 
 fig.*. 
 
 gunwales ; X X ring bolts for the headfast, one at each end j Y platform for the 
 steersman ; E E E the sheer or curve of the boat ; L L the aprons, to strengthen 
 the stems ; M M the sheets, or places for passengers ; O O O the tholes on which 
 the oars are hung by grommets. After the value of the invention was attested 
 by the presentation of a gold medallion to Mr. Greathead, by the Society of 
 Arts, as also one by the Royal Humane Society, and various gratuities in money, 
 parliament in 1802 unanimously voted him 1,2001. The Committee of Under- 
 writers at Lloyd's Coffee House, having voted Mr. Greathead 100 guineas, 
 appropriated 20001. of their funds for the purpose of encouraging the building 
 of life-boats on different parts of the coasts of the kingdom. Great numbers 
 of these boats have since been constructed for all parts of our coasts, as well as 
 for those of foreign nations. But as it most frequently happens that vessels 
 are wrecked on coasts where there are no life-boats, or that from the darkness 
 of the night or the strength of the wind and sea a life boat may not be able to 
 reach the vessel in time to afford succour, it is highly desirable that all vessels 
 should carry with them the means of safety for their crews ; and accordingly 
 numerous plans have been suggested of converting the ordinary boats of a ship 
 into life-boats to meet these emergencies. Of these plans we select that of 
 Captain Henry Gordon as amongst the most simple and efficacious, whilst it in 
 nowise interferes with the ordinary services for which the boats may be required. 
 It consists in attaching to the exterior of the boat a species of buoy, of a trian- 
 gular form, which, whilst it adds greatly to the buoyancy of the boat, saves it 
 from concussions, offers little obstruction to its progress, and can be attached or 
 removed as occasion may require, with great facility and dispatch. Fig. 1 (page 
 195) shows the buoy ; Fig. 2 an end view of the same ; and Fig. 3 represents it 
 fitted to a boat. The buoy is composed of fine Spanish cork, and consists of 
 eight rows, each row being a foot longer than that immediately below it. Each 
 row is constructed of pieces of cork 1 foot long, 6 inches wide, and about 
 1J inch thick, laid three thicknesses together, and then placed end to end till 
 of the required length, (which in the drawing is represented at nine feet for the 
 upper streak,) and then formed into one streak by lengths of split bamboo, 
 laid on all four sides, and well sewed together by strong cord covered with shoe- 
 maker's wax. The different streaks are fastened together by four ropes, which 
 are seized together between each streak ; when used, the ends are drawn under 
 the keel till the lower streak touches it, and then brought up over the side and 
 fastened to the thwarts ; the other triangle is in like manner drawn up under 
 the boat's bottom on the opposite side and fastened. Two buoys to the scale of 
 that shown in the engraving contain 14f cubic feet of water; and if attached 
 to a boat 28 feet long, and capable of containing twenty-four men, would leave 
 a buoyancy of 718 Ibs. for their support. Large boats, such as those capable
 
 BOILERS. 
 
 195 
 
 of containing 100 men, instead of a single large triangle on each side, should 
 have three of 9 feet length each, hy which means the same triangles might be 
 made to serve boats of different sizes, by which the expenses of outfit would be 
 materially reduced, and triangles of the above dimensions would also be more 
 
 manageable, easier put on or taken off, and more easily stowed away than large 
 ones. Thus the launch, rowing twenty-four oars, with seventy-five men on 
 board, might be fitted in the following manner : the barge's triangle fixed 
 amidships, the cutter's on the bow, and the jolly boat's on the quarter; the 
 launch would then be rendered completely buoyant without any additional 
 expense. The contrivance combines several advantages ; it is extremely 
 simple, and offers the best security under similar circumstances; it is so reason- 
 able in its cost as to admit of every merchant vessel being supplied with it; and 
 not being a fixture, it can be at any time removed, so as to be no additional 
 weight when a boat is being hoisted in or out. It is particularly advantageous 
 for the preventive service, to approach vessels and visit them when no other 
 boat can ; for a blow that would stave a boat, would not penetrate the triangle 
 owing to its elasticity. At sea, also, it might take up a drowning man in a gale 
 of wind, when no other boat could live. 
 
 BOILER, in its most extended sense, implies any vessel employed for pro- 
 ducing the ebullition of liquids ; thus the ordinary domestic pots and kettles, 
 brewing and washing coppers, as wellas all kinds of vessels used for heating liquids 
 in various manufacturing operations, come under this denomination. Our business 
 in this place is, however, the description of that important apparatus wherein 
 is generated the source of that power which is regulated and applied by the 
 steam engine ; previous to which, we shall make a few observations on the 
 requisite properties of steam boilers in general. The first and most important 
 quality we consider to be safety from explosion, for unless this be attained, so 
 as to render personal danger improbable, such boilers should not be used at all.
 
 ig c BOILERS. 
 
 The next in importance is effectiveness, or that which will produce the required 
 quantity of steam by the consumption of the least quantity of fuel. Cheapness 
 in the cost of construction, and durability in the wear, may be ranked as the 
 third requisite. The fourth is, perhaps, convenience, or that which can be worked 
 with the utmost facility, that will require the least personal attention, and will 
 occupy the least space. That boiler which combines the four qualities just 
 mentioned, and possesses each in the most eminent degree, may be deemed a 
 perfect one. The materials principally used at present for the construction of 
 boilers are iron and copper, though boilers have been made of wood and stone. 
 In those formed of wood the furnace was of necessity placed internally, sur- 
 rounded by the water ; and as wood is an extremely bad conductor of heat, 
 but little loss of it was sustained by radiation therefrom, while a considerabb 
 economy of fuel was consequently effected. The cost of such was also small, 
 compared to those of metal ; they were introduced in America by Chancellor 
 Livingstone and Mr Anderson. Boilers of stone were introduced by Mr. Brindley, 
 who, in 1756, erected a steam engine near Newcastle-under-Lyne, with a boiler 
 of this description. It was composed of brick and stone firmly cemented 
 together, and the water was heated by iron flues. The material of which a 
 boiler is constructed is of more consequence, in an economical point of view, than 
 is usually supposed, as the heat cannot be communicated to the water without 
 being first transmitted through the substance of which it is formed. M. Despretz, 
 who made a series of very accurate experiments to determine the comparative 
 power of different substances for conducting heat, obtained the following results : 
 
 Gold 1000.0 
 
 Silver 973.0 
 
 Platina 981.0 
 
 Copper 898.2 
 
 Iron 374.3 
 
 Zinc 363.0 
 
 Tin 303.9 
 
 Lead 179.6 
 
 Marble 23.6 
 
 Porcelain 12.2 
 
 Firebricks 11.4 
 
 The conducting power of copper being thus more than double that of iron, offers 
 very great advantages ; but there are other considerations to be entered into 
 before determining to which the preference is due, especially their comparative 
 cohesive strength and cost. A ccording to some experiments the copper was found to 
 be the strongest, but that was probably owing to the iron being of inferior quality, 
 as most philosophers have agreed in attributing superior cohesive strength to 
 iron. Notwithstanding this circumstance, from the greater uniformity of the 
 texture of sheet copper over that of iron, manufacturers usually construct copper 
 boilers of thinner plates than those of iron, that have to withstand the same 
 pressure of steam. Experience has, we believe, established this as a rule, pro- 
 bably from observing that when a copper boiler bursts, it only tears open, while 
 a boiler of wrought iron plates is often blown to pieces. The cost of copper is, 
 however, four times that of iron ; but if it be admitted that the quantity of heat 
 passing through iron in a given time can be doubled in copper, it follows that 
 a copper boiler having only half the superficies of one of iron, exposed to the 
 action of the fire, will be adequate to the generation of the same quantity or 
 force of steam. This circumstance, therefore, greatly reduces the weight of the 
 copper boiler, and, consequently, its first cost is made to approximate more to 
 that of the iron boiler of double the size. Increased strength is likewise acquired 
 by the reduced dimensions of the copper boiler, so as to permit of a decrease of 
 the pre-supposed thickness of metal ; and thus the greatly enhanced price 
 per pound of a copper boiler over that of an iron one, which alarms many steam 
 engine proprietors from ordering them, is very much disproportioned to the cost 
 of the entire vessel. When an iron boiler is worn out, the old metal is scarcely 
 worth the expense of removal ; but when one of copper is decayed, the old
 
 BOILERS. 197 
 
 metal is worth three-fourths of its original cost. These considerations, together 
 with the increased safety and reduced bulk of copper boilers, inclines us to 
 believe that in a course of years their use will be found more economical than 
 those of iron. In the construction of boilers of the ordinary form (that is, such 
 as consist of a capacious single chamber), the bottom surface should be of suffi- 
 cient extent to be capable of absorbing as much heat as will be necessary to pro- 
 duce the required quantity of steam, what little heat may be given out laterally 
 serving to prevent condensation in the upper part of the vessel ; and the smoke, 
 before it enters the chimney, should be robbed as much as possible of its heat by 
 being brought into contact with the conduit pipe, by which the boiler is supplied 
 with cold water. It has been stated by a scientific authority that there is a cocr- 
 siderable waste of fuel in producing steam by intensity of heat upon a smal! 
 surface, and that the application of a moderate heat (800 Fahr.) is far more 
 economical. A cubic foot of water converted into steam per hour was reckoned 
 by Mr. Watt as equivalent to one horse's power, who observed that this quantity 
 of steam could be raised per hour by 8 feet of surface of boiler and flue, in a 
 judiciously constructed furnace. In practice, it is usual to allow from 4 to 5 feet 
 of bottom surface of boiler to raise 1 cubic foot of water into steam per hour. 
 1 1 is considered essential that a boiler should contain four or five times as much 
 water as it boils off per hour ; and it is obvious that it should have a space above 
 the water capable of containing as much steam as will supply the engine at each 
 stroke, without materially diminishing its elastic force. For this purpose, the steam 
 room (or space above the water) should hold a volume equal to the supply of eight 
 or ten strokes of the engine : in large engines it is not unusual to employ two, 
 three, or more boilers, to supply them with steam ; one of them being reserved foi 
 use, in case of repairs being required to the others. In fact, a spare boilei 
 should be provided wherever stoppages are of serious importance in a concern. 
 The strength of low-pressure boilers should be twice the regulated pressure on 
 the safety-valve ; but high-pressure boilers should be proved to at least three 
 times their working pressure. Upon the form of boilers much of their strength 
 and their efficacy in the generation of steam depend. The earliest boilers 
 employed for generating steam, and applied as a motive force, with which we are 
 acquainted, were either globular or hemispherical, with flat or concave bottoms ; 
 and many of these are still in use for the supply of high-pressure engines. In 
 situations where fuel is so abundant as to render needless any economy of it, 
 they may continue to be used with advantage, as their form adapts them to 
 withstand steam of great elastic force. The waste of fuel caused by them, 
 elsewhere, led to a very general substitution of boilers of an oblong form ; and those 
 known by the term of " waggon boilers," from their shape, formed one of the 
 many improvements of the steam engine introduced by Watt. A longitudinal 
 section of a boiler of this kind is represented by fig. 1 in the subjoined engraving, 
 fitted up with all the appendages now generally applied, and set in a furnace of 
 the usual construction, a a a is the boiler, having a cylindrical return flue b 
 throughout its length ; the form of these parts will be best understood by con- 
 sidering them with reference to Fig. 2, which shows the figure of the boiler in 
 its cross section, b being the return flue ; this portion of the boiler should be 
 always placed near to the bottom, and be constantly kept covered with the water, as 
 seen at c in the drawing. The flame and smoke from the furnace d first passes 
 under the boiler, then returns through the flue b to the front, where the current 
 is divided, and passing to the right and left through lateral flues in the brick- 
 work (one of which is brought into view at e e) before it enters the chimney//. 
 The water is supplied to the boiler by the feed-pipe g, which is made to contain 
 a column of water equal to the amount of pressure in the boiler. On the top of 
 this pipe is a cistern h ; i is a float, made of stone, suspended by a wire passing 
 through a stuffing-box j, which is attached to one extremity of a lever, whose 
 fulcrum is at k, a weight / being suspended to the extremity of the other arm 
 of the lever sufficient to counterbalance the difference between the specific gravity 
 of the stone and the water, causing the former to lie on the surface of the latter. 
 By this arrangement, when the water sinks below the proper level in the boiler, 
 the stone float descends with it, causing the attached wire te operate upon the
 
 198 BOILERS 
 
 lever above, and lift the valve shown in the cistern h, which then affords a fresn 
 supply of water. The feed pipe likewise contains an iron bucket, hung by a 
 chain that passes over two pulleys o o ; the other end of the chain is attached 
 to a plate of iron p, called the da'mper, which is used to enlarge or contract, and, 
 
 Fig. 1. 
 
 when required, entirely close the throat of the chimney. By this contrivance, 
 when the steam in the boiler is urged to too great an extent, its pressure forces 
 the water in the feed pipe upwards, thereby raising the bucket m, and causing 
 its counterbalance, the damper, to descend in the throat of the chimney, and 
 reduce the intensity of the fire. At q and r are two guage-cocks, by which the 
 proper height of the water in the boiler may be always ascertained. If q dis- 
 charges water, and r steam, the water is at the proper height ; if both cocks 
 discharge water, it is above its proper height ; and if both discharge steam, it 
 is below its proper height. This latter circumstance, which can only take place 
 by the defective action of the last described apparatus, is of serious moment, 
 and requires an immediate remedy ; the most safe is, in our opinion, the reduction 
 of the fire, by stopping up, by the readiest means at hand, all access of air to 
 the grate, after which, attention may be paid with confidence to removing the 
 cause of the defect. For the purpose of showing at all times the pressure acting 
 upon the boiler, a steam-guage is employed. This is usually made of an iron 
 tube, bent into the form represented, one end communicating with the steam- 
 room of the boiler, and the other open to the atmosphere. This tube is partly 
 filled with mercury, and into the externally open end is put a slight rod of wood, 
 which floats perpendicularly in the mercury, and shows by its altitude, on a 
 divided scale of inches affixed to that leg of the tube, the pressure of the steam. 
 If the steam raises the mercury or rod one inch, it proves that the pressure is 
 one half pound per square inch on the internal surface of the boiler, tending to 
 burst it; for if the section of the bore of the pipe was just one inch, the pressure 
 would be supporting one cubic inch of mercury, which will be found to weigh 
 iarly hah a pound ; therefore, for every two inches rise, one pound pressure
 
 BOILERS. 
 
 199 
 
 may be reckoned; and as condensing engines seldom work wkh more than 
 three or four pounds pressure upon the inch, the scale need not be longer than 
 eig^ht or nine inches For preventing the pressure becoming greater than the 
 boiler is calculated to sustain without incurring danger, a safety-valve is pro- 
 vided. This is usually a circular piece of metal, with a conical periphery ground 
 to fit into a conical seat, and kept there by the pressure of a lever, loaded with 
 a determinate weight, that will not suffer it to rise until the steam has acquired 
 an excess of force above that required for working the engine, or would endanger 
 the bursting of the boiler. In large boilers, especially those in steam boats, it 
 is usual to have another safety valve, inclosed in a box under lock, the key being 
 kept by the chief manager, to prevent the possibility of improper interference 
 with it, by ignorant or imprudent persons : by the neglect of which precaution 
 many serious accidents have occurred. The steam which escapes from 
 safety valves is generally conducted by a pipe from the valve boxes into the 
 chimney. At v v is the steam-pipe by which the engine is supplied, the quantity 
 being regulated by a throttle-valve at w, and a screw-down valve at x. For the 
 purpose of cleaning out or examining the condition of the boiler, a circular or 
 oval hole y is made sufficiently large to admit a man to pass through, and 
 therefore called the man-hole. It is covered by a strong plate of iron bolted 
 down, in which plate is usually fitted the atmospheric or vacuum safety valve z, 
 which opens inwards by the pressure of the atmosphere, preventing the latter 
 force from injuring the boiler, should a vacuum be formed by condensation 
 within. A cock and pipe leading from the bottom of the boiler is employed 
 for discharging it of its contents. Next to the waggon-shaped boilers of Watt, 
 those of a long cylindrical form have been the most extensively employed, 
 especially for high-pressure engines, on account of their superior strength ; 
 besides as affording a considerable surface for the direct action of the fire and 
 heated gases. They are usually known in this country by the term " Trevithick 
 
 boilers,' from the supposition that Mr. Trevithick was the inventor. We, how- 
 ever, observe, that Mr. Oliver Evans, of America, describes them as being used 
 
 by him in his high-pressure engine, prior to the patents of Mr. Trevithick, and 
 
 as Mr. Evans does not claim them, we may suppose they were in use before his 
 
 time. Cylindrical boilers are 
 
 frequently made of a great 
 
 length, ten, twelve, or more 
 
 times their diameter, and are 
 
 preferable of such proportions, 
 
 where their situation will admit 
 
 of it, for the reasons before 
 
 mentioned. In this country 
 
 their extremities are usually 
 
 made hemispherical; but in 
 
 America the ends are usually 
 
 closed by flanged disks of great 
 
 thickness, on account, we sup- 
 pose, of the greater facility 
 
 of construction by ordinary 
 
 workmen. These boilers are 
 
 generally provided with an in- 
 ternal flue, through which the 
 
 heated air and flames, after tra- 
 versing the length of the under 
 
 side of the boiler, pass before 
 
 entering the chimney. The 
 
 annexed diagram represents a 
 
 transverse section of a small 
 
 high-pressure cylindrical boiler, 
 
 as manufactured by Mr. Saun- 
 
 ders, late of Sheffield, but now 
 
 of New York, U. S. The furnace
 
 2 00 BOILERS; 
 
 door is at a; b the furnace , c the ash pit ; d the boiler ; e the stone float (shown 
 by dotted lines), for regulating the supply of water, by means of the counterpoise 
 g; f is the internal flue, which returns the flame and heated air through the 
 boiler; h the steam pipe leading to the engine. 
 
 The boiler figured in the annexed cut, is of a cylindrical figure in the lower 
 part, but combines some peculiarities that are deserving of notice. It is a 
 patented arrangement by Messrs. Horton and Fisher, who are large boiler 
 manufacturers, near Birmingham. The object of it is to form a reservoir of 
 steam within the boiler, surrounded by the hot water, in order that the pressure 
 of the steam may not be reduced by radiation, which the inventors presume to 
 be the case in a greater dagree in boilers of the ordinary construction. Fig. 1 
 
 represents a longitudinal section of the boiler, and Fig. 2 a transverse section 
 of the same : the letters of reference apply to similar parts in each view, aaa 
 shows the external form around which the furnace and flues are to be con- 
 structed ; b b b is the internal vessel or reservoir, for containing the steam 
 generated, surrounded by the water which is supplied by the tube o o from 
 another reservoir placed above, but not introduced into the drawing. The heat 
 having caused the steam to fill the upper part of the boiler d, it passes thence 
 through the bent tube c into the steam reservoir b below, from whence it is con- 
 ducted to the engine by the steam pipe e, the top of which n is designed for 
 the situation of the safety valve. At /is a cock for drawing off whatever water 
 may be condensed in the steam chamber, and at k may be placed another for 
 discharging the boiler. At II are man-holes for gaining access into the interior. 
 We do not ourselves perceive how the intention of the patentees to make the 
 internal vessel b b a store of high steam for the supply of the engine, can be 
 effected by this arrangement, for the hottest steam will be rather disposed to 
 obey the laws of nature, and ascend into the upper vessel through the bent tube, 
 than descend through the same to the lower vessel, according to the desire of the 
 contrivers. It must, however, be admitted that there is a considerable degree of 
 originality in this boiler, and it may prove a useful and effective generator of steam. 
 In 1803, Mr. Woolf patented his boiler, which has obtained much deserved 
 celebrity. It has been for many years very extensively and successfully employed 
 in Cornwall, for the production of steam for the large mining engines there. 
 We have already observed that the long cylindrical boilers possess great advan- 
 tages over those of a cubiform or rotund figure. To increase their safety, and 
 their capability of producing steam at very high pressures, Mr. Woolf greatlv 
 extended the principle of the cylindrical form. One of the most simple of this 
 gentleman's construction consists of eight tubes of cast iron (of six or more 
 inches in diameter), connected to each other by a bent tube at their extremities, 
 with communications to a larger cylinder above them, employed as a reservoir 
 for the steam. The furnace is divided by a wall longitudinally into two parts, 
 and the eight tubes are fixed horizontally across both these. The fuel chamber 
 is at one extremity of one of the divisions, and arched above the two first tube*,
 
 BOILERS. 201 
 
 o as to reverberate the flames and heated vapours, which then pass under the 
 third tube, over the fourth, under the fifth, over the sixth, under the seventh, 
 and partly over and partly under the eighth tube, when the flue turns into the 
 second division of the furnace, on the other side of the wall, built under, and 
 in the direction of, the large steam cylinder before mentioned. Passing now 
 under the seventh cylinder, the course of the flue is over the sixth, under the 
 fifth, over the fourth, under the third, over the second, and partly over and 
 partly under the first, when it enters the chimney. To produce this long ser- 
 pentine reverberation, the upper and under side of the brick-work is formed in 
 arches, alternately reversed, their extremities abutting against the tubes, covering 
 about a sixth part of their circumferences, but exposing the rest to the action 
 of the current of heated matters from the fire. Each of the tubes is provided 
 with a flanged disk at one end, fastened on by screw bolts, that they may bo 
 easily removed, and the tubes cleaned out at pleasure from sediment and in- 
 crustations. The water carried oft* by evaporation is replaced by the usual 
 means of a force pump, and the steam generated is conducted to the engine or 
 other object, by a tube connected to the steam reservoir. " It may not be im- 
 proper," says Mr. Woolf, " to call the attention of those who may hereafter wish 
 to construct such apparatus, to one circumstance : namely, that in every case, 
 ihe tubes composing the boiler should be so combined and arranged, and the 
 furnace so constructed, as to make the fire, the flame, and the heated air, to act 
 around, over, and among, the tubes, embracing the largest possible quantity of 
 their surface. It must be obvious to any one that the tubes may be made of 
 any kind of metal ; but I prefer cast iron as the most convenient The size of 
 the tubes may be varied ; but in every case care should be taken not to make 
 their diameter too great; and it must be remembered, that the larger the 
 diameter of any single tube in such a boiler, the stronger it must be made in 
 proportion, to enable it to bear the same expansive force as the smaller cylinders." 
 Mr. Woolf also directs that the lower tubes should be always kept filled, and 
 the upper, or steam cylinders, half filled with water, that is, as high as the fire 
 is allowed to reach, and that in no case the water ought to be allowed to get so low 
 as not to keep full the branches which join the lower tubes to the upper cylinder. 
 The annexed engraving exhibits an arrangement of parts combining the 
 leading features of several previous inventions, and was patented by Mr. Thomas 
 Tippet, of Gwennap, in Cornwall, in 1828. Fig. \ represents an end view, and 
 Fig I. Fig. 2. 
 
 . , 
 
 which contwns water, proceed three rows of open vertical pipes b b b, which 
 support a semi-cylindrical steam vessel c. At the farthest extremity of the 
 cylinder a there proceeds horizontally a short open pipe d, communicating with 
 a small supplementary boiler, which is a cylinder of the same area as a, but 
 very short. This boiler is built in a furnace, in which the flues are so arranged 
 that the heated air, in passing out at the end /of the furnace flue, shall impinge 
 against the flat side of the supplementary boiler; the flue thence proceeds 
 upwards, and along the underneath flat side of the semi-cylindrical vessel.
 
 202 BOILERS. 
 
 between the vertical tubes to the front of the boiler, where it descends, passing 
 under the bottom of the latter, then round the back of the supplementary boiler, 
 and over the top of the semi-cylinder to the chimney, which is in front, nearly 
 over the furnace doors. 
 
 An ingenious attempt to expose water in thin sheets over an extended surface 
 of metal, was made by Mr. John M'Curdy, from the United States, who patented 
 it in this country. It consisted of a series of cylinders, with spherical ends, 
 arranged horizontally like retorts, in a pyramidal form, in a furnace, so as to 
 cause the heat as much as possible to impinge against their surfaces, in its 
 ascent amongst them to the flue above. Each of these cylinders contained 
 within it another cylinder, of so much less diameter than the outer, as to leave 
 between them throughout a very narrow space, the uniformity of which space 
 was preserved by coiling a spiral band upon the outside of the inner cylinder, or 
 other suitable contrivance. These latter cylinders were hermetically closed at each 
 of their ends, and were placed inside the former to produce between them hollow 
 cylindrical sheets of water. The water was forced into one of the lower cylinders, 
 and made, by the action of the pump, to circulate through the others of the 
 series. By this arrangement of disposing the water in thin sheets, it was pre- 
 sumed that steam of a very high pressure would be generated with extraordinary 
 rapidity. We have, however, never been informed of the cause of this boiler 
 not having been brought into practical operation, and are therefore left to con- 
 jecture that it was probably owing to the great expense of construction ; the 
 liability to deposits and incrustations in the narrow spaces between the internal 
 and external cylinders; the difficulty of cleansing them; and, by the neglect of 
 the latter operation, causing an irregular generation of steam, the heating red 
 hot the incrusted parts, and, as a consequence, the blowing out of the water, 
 and the rapid destruction of the metal. To these causes may be added the 
 waste of fuel by the shortness of the flue. The contrivance is, nevertheless, not 
 devoid of merit, and may afford a useful hint to succeeding inventors The 
 superior strength and safety of boilers made of small tubes have within the last 
 few years led to their introduction in almost every possible variety of form, a great 
 many of which have been the subjects of unproductive patents. Those which 
 possess the most distinct character from each other, and have been more or less 
 brought into public use, we shall proceed to notice. 
 
 The first we shall describe is the invention of Mr. W. H. James, patented 
 in 1823. It consisted of a series of annular tubes of equal capacity and 
 diameter, placed side by side, and bolted together, so as to form by their union 
 along cylindrical boiler, in the centre of which, at one end, the fire-place was 
 situated. The tubes were made of the toughest wrought iron, three sixteenths 
 of an inch thick ; and being of only one inch in diameter, they were capable, 
 as was proved, of sustaining a pressure of several thousand pounds per inch. 
 In some of these boilers, the tubes were made square in their transverse section, 
 consequently, when their flat sides were placed together as described, there 
 were no open spaces between them; and tie annular tubes were connected 
 together by means of long bolts passing through the end-plates of the cylinder, 
 where they were screwed up firmly by nuts on the outside. Communications 
 from tube to tube were made by making two perforations in them lengthways 
 of the cylinder ; one on the upper side, for the free passage of the steam, and 
 one on the lower, for the flow of the water. When it was desired to construct a 
 boiler of greater power in a compact form, to adapt it more particularly to loco- 
 motion, Mr. James preferred making two concentric cylinders, each composed 
 of a series of annular tubes, like those described, and as delineated in the 
 annexed diagram, which exhibits a transverse section of such a boiler. The 
 annular tubes are distinguished by the water drawn therein. The upper per- 
 forations or steam passages are shown at b b, and the lower, or water passages, 
 at c c. The water was maintained at the desired level by the action of a 
 float, in an adjoining vessel, not shown in the figure. The furnace bars formed 
 two inclined planes, as shewn, at one end of the cylinders, and the flue 
 descended at the other end. These latter parts were made so as to be easily 
 detached at pleasure. The entire boiler turned upon an axis, and rested upon
 
 BOILERS. 203 
 
 rollers, fixed in a circular stand; every tube was furnished with some shot, 
 mixed with angular pieces of metal, so that when it was desired to cleanse the 
 boiler of deposit, the furnace and chimney tube were drawn out, the con- 
 necting pipes unscrewed, when the cylinder was turned round by a winch, in 
 
 the manner of the common scouring barrel, used for brightening metallic articles 
 To prevent the loss of heat by radiation, the boiler was surrounded by a double 
 case, the spaces between which were filled up with a mixture of clay and char- 
 coal. We have repeatedly seen a boiler of Mr. James's construction, on the 
 principle of the last described, but consisting of only one cylinder of annular 
 tubes, 3 feet 6 inches long, and 20 inches diameter, effectively working a very 
 small high pressure engine, (having only a 3 inch piston of 1 2 inch stroke,) up to 
 three horses' power. This boiler had circular tubes, and each annulus was made 
 out of two semicircular pieces, connected at their extremities to an upper and 
 a lower transverse horizontal tube, the length of the cylinder ; the upper one 
 forming the principal and the connecting steam tube, and the lower one the 
 water tube. Into these horizontal tubes, conical perforations were drilled, to 
 receive the extremities of the semicircular tubes to which they were united, 
 steam and water tight, by means of bolts and rivetted keys. However firm 
 this mode of uniting appeared to the eye, and however accurate the workman- 
 ship, when the fire came to act upon the joints they often became leaky, and 
 were the source of great trouble and inconvenience. Since the period alluded 
 to, Mr. James has invented another boiler, to which he gives the preference, 
 and will be described under the article STEAM. Before, however, we quit this 
 part of the subject, we would draw the reader's attention to the circumstance of 
 the steam chambers in Mr. James's boiler, as shewn in the preceding engraving, 
 by which it is evident that the surfaces of the water are pressed upon by the 
 steam, and that the latter derives an increase of heat and of elasticity subsequently 
 to its formation, by the action of the most intense part of the fire ; consequently 
 it would appear that this arrangement is eminently calculated to prevent the 
 water rising, or being forced over into the engine ; an inconvenience which 
 had been experienced in most boilers made of small tubes. Although the in- 
 convenience never occurred in Mr. James's boilers whilst the fire was kept 
 steady, the supply of water regular, and the tubes clean ; yet from the neglect
 
 204 
 
 BOILERS. 
 
 or failure of some one of these conditions, the water did occasionally conn 
 over. The observations we have been enabled to make upon these facts, incline 
 us to the opinion that it would be better not to make boilers of tubes of a less 
 diameter than two inches ; because the much larger body of water such contain 
 are not so suddenly and violently affected by ordinary variations of temperature 
 occasioned by unskilful firing, or by the irregular supply of water ; nor are the 
 tubes so liable to become choked, as the joints can be made with greater 
 accuracy without filling up the water or steam way, to the danger of the tubes 
 becoming red-hot, and the destruction of the boiler. Tubes of two inches can 
 be much more easily cleansed ; and as respects safety, it is scarcely possible to 
 burst them, if only a quarter of an inch thick, by any pressure of steam that 
 can be beneficially applied. 
 
 The contrivance we shall next notice is the invention of Mr. Goldsworthy 
 Gurney, a gentleman of. the medical profession, but more generally known to 
 the public by his persevering attempts for the establishment of steam carriages 
 on the common road ; and the boiler we shall describe is especially designed for 
 
 Fig. 3. 
 
 that purpose. Fig. I shows a vertical section of the boiler. Fig. 2, an ex- 
 ternal end view of the same. Fig. 3, the manner in which the series of pipes 
 composing the boiler are fixed, and open into horizontal chambers. Fig. 4, a 
 portion of one of the horizontal chambers, partly broken away to exhibit the 
 apertures of the pipes, and their arrangement. The same letters on each 
 figure refer to corresponding parts. In the section Fig. 1 the semi-elliptical 
 form in which the pipes are bent, and the manner in which they respectively 
 cross 1 each other, is seen ; the ends of these pipes have screw threads on the 
 outside, to repeive nuts, which secure them to the horizontal chambers b, as 
 shown in Fig. 3 ; a packing composed of pounded asbestos, mixed with red lead 
 and litharge, in about equal parts, is interposed between the nuts and the end 
 plate, applied in hollow washers of a saucer-like form, which it is said makes 
 perfectly steam, water-tight, as well as fire-proof joints. The chambers b have
 
 BOILERS. 
 
 206 
 
 direct communication one with another, by means of the vertical pipes c; d d, 
 are two bent tubes, leading from b b into the steam vessels or "separators" e e 
 (as Mr. Gurney calls them.) From thirty to fifty, (according to the size of the 
 apparatus) of the small pipes a, are arranged in the manner shown in Figs. I 
 and 4, in which the fuel is placed as at h, the heated air and flames being 
 directed by a bridge i, to take the course delineated before entering the 
 chimney k ; but a considerable portion of the heat passes freely between and 
 round about the pipes, the whole of them being exposed to the powerful effects 
 of a furnace so circumstanced ; o is the furnace door, and i the ash-pit. During 
 the working of the engine, the steam chambers e are by the usual means kept sup- 
 plied with water up to the level shewn, which being higher than the pipes in the 
 furnace, the latter are always kept full of water, as judiciously recommended by 
 Woolf in his specification, quoted in the preceding part of this article. The steam 
 generated in the small pipes ascends by its superior levity through the water in the 
 steam vessels e, or it may be, transmits its caloric to other particles of water, which 
 escape at the surface of the fluid in the form of vapour, which passes off through 
 the branches //into a common pipe g, that leads to the engine. In fixed 
 engines the iron casing represented as surrounding the boiler is dispensed with, 
 the apparatus being set in the usual manner in brick-work. To obviate a com- 
 mon objection to tubular boilers, of their becoming choked with a deposition of 
 earthy matter, Mr. Gurney purposes to clean them out when they become foul, 
 by the following chemical treatment. If the tubes are of iron, one part of 
 muriatic acid, with 100 parts of water, are to be left in the boiler, a sufficient 
 time to dissolve the incrustations ; if of copper, the following solution is to be 
 used in a similar way, one pound of common salt, half a pound of sulphuric 
 acid, in four gallons of water. To expedite the operation of cleansing, a small 
 fire may be made in the boiler, and the steam be employed to blow the contents 
 out of the tubes. One of the most prominent advantages attending the use of 
 this boiler, is the great facility with which repairs are executed ; when a tube is 
 injured or burned, the removal of it or the substitution of a new one are only the 
 work of an hour. Like other tubular boilers, it is safe from the effects of rup- 
 ture ; but the " separator " being in fact a steam reservoir, that part is as liable 
 to explosion as other boilers of the same capacity and thickness of metal. The 
 small tubes exposed to the fire, if always kept full of water, are not likely to be 
 soon burned out. The merit of this arrangement is however, due to Mr. Woolf, 
 (see page 201,) and were Mr. Gurney's steam reservoirs defended like thai 
 gentleman's, from the o o c 
 
 cooling influence of the ' a^fl.R Afl.Q AnHH H.EU 
 atmosphere, the effect " [o \ \ \ \ \ i j j j j ; ; j j j \ j j i ; j Q~\ 
 of their contents upon 
 the engine would be 
 improved. 
 
 The annexed diagram 
 is explanatory of a boiler 
 which has been em- 
 ployed for the gene- 
 ration of steam in the 
 locomotive carriage of 
 Messrs. Summers and 
 Ogle, who have taken 
 out a patent for it. 1 1 
 consists of a series of 
 tubes, placed vertically, 
 with a flue passing up ______..__ 
 
 the centre of each ; a a a represents the external tubes containing the water and 
 steam ; b b b the interior tubes or flues, for the passage of a portion of the heated 
 air, &c., the remainder passing off between the exterior tubes ; and thus the water 
 of the boiler disposed in thin hollow cylinders is continually exposed to an extensive 
 surface of heated metal on-both sides, c c c are the ends of the internal tubes 
 passing through the screwed nuts dd<l&t the top, and e e at the bottom, and by 
 
 D 
 
 o rr
 
 206 
 
 BOILERS. 
 
 which both the exterior and interior tubes are secured in their places. The water 
 is supplied to the boiler through the pipe /, by a force pump; and the steam when 
 generated, passes off to the engine, by the pipe . Although the heated matters 
 from the tire have but a short passage to the chimney, it is obvious that the 
 obstruction to the current formed by so many tubes crowded together must be 
 considerable, and cause a great portion of the heat to be absorbed, it being, as it 
 were, wire-drawn. Economy of fuel is, however, not a matter of such important 
 consideration in a steam carriage, as in fixed engines ; there being in the present 
 infant state of locomotion, on the common road, no competition. It is obvious 
 that the different parts of this boiler can be put together with facility, and that 
 a defective tube can be instantly removed, and a sound one substituted, by simply 
 unscrewing the interior flue or tube. The manufacture, however, requires the 
 utmost exactness, especially in making all the tubes of precisely the same 
 length, and the other parts corresponding with each other of uniform dimensions; 
 otherwise a source of imperfection would arise, from the longer tubes preventing 
 the shorter ones from being screwed sufficiently close to render them steam-tight. 
 Although the inventions of Mr. Jacob Perkins (who has distinguished himself 
 by numerous ingenious attempts to generate and work steam at pressures far 
 beyond that of any other experimentalist or engineer,) have not been attended 
 with that success which the public were led to believe, many of his arrange- 
 ments possess considerable merit, and ought to have a place in this work. We 
 allude in particular to his having brought steam of enormous pressure under 
 the most perfect control. The annexed diagram is explanatory of a boiler 
 
 employed by Mr. Perkins, which we saw working a small engine on the high 
 pressure and expansion principle, calculated by him at 30 horses' power. A 
 series of cast-iron bars. 5 ioehps =mmrp. nerforated throughout longitudinally,
 
 BOILERS. 
 
 207 
 
 with 1 1 inch circular holes, were arranged in three tiers, A, B, and D, across a 
 furnace, of sufficient length to come through the opposite walls, where their 
 extremities were connected together in a peculiar manner, so as to form one 
 continuous vessel. By the operation of a forcing pump water was continually 
 injected under the pressure of a heavily loaded valve into the two upper tiers 
 of tubes, so as to keep them always full ; the third or lowest tier of tubes con- 
 tained no water, and were to be kept at a temperature of about 1000 Fahrenheit 
 At each stroke of the engine, a certain quantity of the water contained in the 
 two upper tiers, (supposed to have acquired a temperature of 700 or 800,) was 
 discharged into a valve box at C, communicating with the lowest tier of tubes 
 D, wherein it flashed into steam, and passing successively through those tubes, 
 exposed to the intensity of the fire, it was received into a steam chamber L for 
 the supply of the engine. The object of the. inventor in introducing such great 
 masses of metal into his apparatus is not very apparent, unless it be the pre- 
 vention of sudden and great variations of temperature in the tubes, which 
 perhaps could not otherwise be effected, as the body of water they contain is 
 too small to maintain much uniformity of heat, and Mr. Perkins must be well 
 aware that the perfect safety of such generators is not increased by form- 
 ing them of a square figure instead of circular. 
 
 To obviate the destructive effects of the direct action of the fire upon the 
 substance of which a boiler is constructed, and by which action the liability to 
 
 Staffordshire, for which he had a patent in the year 1821. "It is well known 
 that oil and other fatty matters are capable of being raised in temperature far 
 above that of boiling water, without undergoing decomposition; this property in 
 oil having never before been applied to the working of a steam engine, formed 
 the groundwork of Mr. Manby's patent. The construction of his apparatus is 
 explained by the annexed diagram ; where a represents an oblong boiler, sup-
 
 "208 
 
 BOILERS. 
 
 posed to be set in brickwork, over a fire-place of the usual construction. This 
 vessel is to contain the oil, which is to be heated to about 300 Fahrenheit. The 
 vessel above b is a strong cylinder, containing the water to be converted into 
 steam, inside of which is fixed a system of pipes, connected into one continuous 
 line ; through these pipes the oil is made to flow by the action of a pump at 
 c, (worked by the engine, or other first mover,) which raises it by the pipe d, 
 and discharges again into the boiler by the pipe e. The heated oil in its pas- 
 sage through the pipes elevates the temperature of the surrounding water, and 
 converts it into steam of several atmospheres' pressure. The patentee states, 
 that by this apparatus steam of very high pressure may be generated without 
 the possibility of danger, and that a smaller quantity of fuel is consumed than 
 when the fire operates in immediate contact with the water vessel. In what 
 manner, however, this economy is effected is not very apparent; and although 
 the danger of explosion in the steam vessel is considerably lessened, the liability 
 to accidental conflagration is so far increased by the contiguity of the furnace 
 to such an inflammable substance as oil, (which was liable also to become thick 
 and glutinous) as to render it imprudent to use the apparatus in buildings that 
 are not fire-proof. 
 
 The second invention we have to notice is that of Dr. Ernst Alban, a 
 physician of Rostock, in Germany, a patent for which was obtained in this 
 country in 1825. The heating medium is, in this case, such a mixture of tin 
 and lead as will remain in a fused state at the temperature required for the 
 steam, which is generated in small vertical tubes suspended in the bath of liquid 
 metal. The subjoined diagrams exhibit two baths of this kind connected 
 together, in each of which are deposited eight generating tubes. Fig. I shows 
 
 a longitudinal section of one of the vessels, and Fig. 2 a transverse section of 
 both ; they are made of cast iron, in the form represented at a a a, b b indi- 
 cating the metallic mixture. Supported upon the cover of the metal vessel, is 
 a strong top c c of the generator, containing a cylindrical chamber of 2 inches 
 in diameter ; d d d, are the wrought-iron generating tubes, suspended in the 
 metallic mixture ; they are of 1^ inch bore and are screwed into the top
 
 BOILERS. 
 
 c e, so that they may be taken out whenever they require cleaning; e is the 
 injection pipe, through which the water is conducted into the generating tubes, 
 through a small perforation made over each. The double vessel, as best seen 
 in Fig. 2, is suspended in the furnace, so as to expose all its four sides and ends to 
 
 Fig. 2. 
 
 Fig. 3. 
 
 the action of the fire ; so that although it is but 4 feet long, 3 feet 6 inches high, and 
 9 inches wide, it exposes a surface of 64 feet to the fire. The two injection 
 tubes are connected externally, and communicate in one pipe with the forcing 
 pump. This pump is of the usual construction, furnished with a lever and 
 weight, which are raised by the engine. If the production of steam in the 
 generators be too great for the wants of the engine, the pressure in the steam 
 chamber will act against the injection, and the weight will be insufficient to 
 force down the piston of the pump, which will thus remain inactive, until the 
 pressure is diminished by the ceasing of production and the expenditure of the 
 engine. To prevent the metallic fusion from being overheated, in cases where 
 a smaller supply of steam is required, or where a suspension of steam genera- 
 tion takes place, by the stoppage of the engine or otherwise, the inventor has 
 arranged a heat regulator, which governs the intensity of the fire. The apparatus 
 indicates the temperature of the fused metal, upon which solely its action 
 depends, and the generation of steam in the generators has no influence what- 
 ever upon it, the regulator continuing to act when the generation of steam has 
 ceased, on which account it appears to be essentially different from any heat 
 regulator previously used. Its application to this apparatus is indispensable, to 
 prevent such a heating of the generating tubes as might occasion a decompo- 
 sition of the water injected therein. It consists of two pipes filled with atmo- 
 spheric air, one of each being inserted into each vessel, {Fig. 1, g) and 
 surrounded by the metallic medium. To both pipes, very narrow tubes are 
 fixed, shown at h, Fig. 1, and i, Fig.3; these are joined externally into one 
 tube, which opens inside the mercurial cistern a, Fig. 3. Within the mercury 
 therein contained is immersed a vertical tube b, with a float c swimming on the 
 top of the mercury. This float is connected, by means of the rod d, with the 
 rod e, and acts by the rod/, upon the damper g, which regulates the draught of 
 the fire in the ash-hole. When the air in the pipes, Fig. 1, g g, becomes heated 
 by the fusion, it expands progressively as this becomes hotter, presses on the 
 mercury in a, Fig. 3, and causes it to ascend in the tube b. By the rising of 
 the mercury, the float c is made to ascend likewise, and acts by the rod d on 
 the lever e , and thereby on the damper g, so that should the temperature of
 
 210 
 
 BOILERS. 
 
 the fusion be greater than is required, it gradually closes the aii-hole h, by 
 which the supply of air to the fire is prevented, and the heat consequently 
 diminished. Although the intelligent inventor of this apparatus was, as we are 
 informed, unsuccessful in the introduction of it, yet it has strong claims upon 
 the attention of engineers for the originality and ingenuity of many of its 
 arrangements. The employment of a fluid metal, possessing a high conducting 
 power, for the heating medium, instead of an inflammable substance like oil, 
 possessing but feeble conducting power, promised much better results, while it 
 rendered the use of the apparatus perfectly safe. 
 
 Mr. Porter, a scientific gentleman, who was connected with Dr. Alban in the 
 last described project, subsequently invented, in conjunction with Mr. Beale, an 
 engineer, the third plan we have alluded to. In this apparatus, the arrange- 
 ment is such as to render it impossible to impart a higher degree of heat to the 
 generator than the boiling point of the fluid employed as the medium, as the vapour 
 from the latter is allowed to escape as it is formed. The annexed figure affords a 
 longitudinal section of the apparatus ; a a is the vapour chest, formed of thin plats 
 
 Iron ; 5 the generator, which this drawing may be considered as representing by 
 an edge view of a system or coil of wrought iron tubes ; the dotted line c marks 
 the height of the fluid medium ; d the " breathing-pipe," which in the event of 
 injudicious firing, serves as an outlet and condenser, for such portion of the 
 vapour as may not otherwise be condensed by the lower temperature of the boiler; 
 e an ordinary furnace and flue ; /, the ash-pit ; g the chimney ; h the supply pipe to 
 the generator, through which water is injected by means of a forcing pump, worked 
 by the engine ; i is the steam pipe communicating with the engine. The water 
 injected through the supply pipe h being exposed, during its progress through 
 the generator, to the heat of the vapour furnished by the boiling fluid under- 
 neath, is thereby converted into steam, with a temperature and elastic force 
 answering to the temperature of the vapour, which, losing a portion of its 
 heat, resumes the liquid form, and falls to the bottom of the chest a, while the 
 partial vacuum formed by its condensation causes a fresh portion of vapour to 
 supply the void, and thus keep up a constant action. It is manifest that the 
 temperature of the steam must be uniform, and that no greater degree can be 
 communicated than the boiling point of the fluid medium chosen, and all 
 injury to the machinery is therefore avoided, while, from the same cause, all those 
 sudden accessions of elastic force, which have frequently proved so disastrous, 
 are rendered impossible. This mode of heating has, we are informed, been 
 very successfully employed in the preparation of vegetable extracts, and in other 
 chemical operations where regulated degrees of heat are essential. As respects
 
 BOILERS. 211 
 
 its application to the generation of steam for engines, we are not aware of its 
 having been so used by any other persons besides the patentees. Objections have 
 probably been raised to the combustible media employed in the vapour chest, and 
 the expense attending the supplying the loss of it occasioned by evaporation. 
 These media were chiefly the spirit of turpentine, naphtha, naphthaline, and 
 other products of coal tar, forming a variety of mixtures, whose boiling points 
 vary from 200 to 700 Fahrenheit. 
 
 In the former part of this article, we have had occasion to notice the incon- 
 venience arising from the deposit in boilers, and to mention some of the modes 
 adopted for cleansing them. Occasionally these deposits are several inches in 
 thickness, and as hard as the artificial stone pottery, caused by the baking they 
 receive while in contact with the metal of the boiler, which receives the direct 
 action of the fire. To remove these incrustations is a work of considerable 
 labour; it being a general practice for workmen to get inside the boilers, and 
 break up the stony matter, by means of heavy hammers and cold chisels. 
 These deposits are also the cause of other serious inconveniences ; they form 
 a non-conducting shield between the fire and the water, rendering the boiler 
 liable to become red-hot, by which its destruction or premature wearing out is 
 effected, and a considerable waste of fuel is made. To obviate these injurious 
 tendencies, a variety of plans have been proposed. Some engineers throw into 
 the boiler a quantity of some fibrous and mucilaginous vegetable matter, such 
 as bran or husks, to which the earthy matter in the water adheres, and is 
 thereby prevented from becoming concrete and hard, and consequently more 
 easy to be removed. 
 
 In the year 1828, Mr. Anthony Scott, of the South wark Pottery, Durham, 
 took a patent for a very obvious and effective contrivance to abate this evil. 
 His plan is to place a number of slabs or trays of metal stone or wood near to 
 the bottom of the boiler, which it is said so reduces the agitation of the water 
 during the ebullition, that nearly the whole of the sediment descends by its own 
 gravity, and deposits itself in the trays, instead of on the bottom of the boiler. 
 The transmission of the heat is not intercepted by this arrangement, while the 
 trays are removable at pleasure, for clearing them of the sediment deposited 
 upon them. 
 
 More recently, (in 1830,) Mr. William Taylor, of Wednesbury, took out a 
 patent, having for one of its leading objects the prevention of the incrustation 
 and removal of the sediment, without stopping the operation of the boiler. It 
 consists of a sediment trough or vessel, extending the whole length of the 
 boiler, immediately under it, with a valve opening at one end, through which a 
 portion of water is occasionally permitted to escape with great velocity, arising 
 from the pressure of the steam, that it may carry with it whatever deposit may 
 have settled in the bottom. This arrangement is represented in the annexed 
 sketch ; a a is a cylindrical boiler, having a 
 fire place b, and a flue within it ; c is the 
 deposit vessel below the fire. When this in- 
 vention is applied to boilers which have the 
 fire under, instead of inside them, the patentee 
 applies a deposit trough on each side, and these 
 must be shielded from the action of the fire. 
 The claim to invention under this patent is 
 limited to the particular modifications de- 
 scribed; as deposit vessels have, before the 
 date of Mr. Taylor's patent, been applied to 
 boilers ; and they are undoubtedly appendages 
 of great utility. On account of the great deposition of salts, and other earthy 
 matters, on the bottom and sides of boilers employed in steam boats at sea, it 
 becomes expedient, in long voyages, to stop the progress of the vessel, in order 
 to discharge the contents of the boilers, and fill them anew ; for if the heat be 
 continued after a considerable deposition has taken place, the steam can only 
 be raised by a greatly increased expenditure of fuel, &nd the augmentation of 
 the heat materially injures the tenacity of the metal of which the boilers are
 
 212 BOILERS. 
 
 composed. To obviate so great an inconvenience, Messrs. Maudslay and 
 Field have proposed an arrangement of apparatus, by which the water is con- 
 tinually being changed, and for which they took out letters patent in 1824, 
 These gentlemen state that from 20 to 30 per cent, of the quantity of water 
 evaporated, being taken from the concentrated brine, will keep the water within 
 a degree of saltness from which no practical evils will result, however long the 
 boiling be continued; the quantity thus abstracted from the boiler being of 
 course replaced by a like quantity of sea-water in its natural state. The abstrac- 
 tion of the brine is made by means of a small pump, with a loaded discharge 
 valve, worked by the engine, and so proportioned as to draw from the lowest 
 part of the boiler the quantity determined on, which may be regulated by a 
 meter, shewing the quantity of water driven off in the form of steam. The 
 operation of the pump is, however, not to commence until the brine has attained 
 a considerable degree of concentration; it should for instance contain five 
 times as much salt as common sea water does ; after this, every stroke may 
 be made by means of the pump, to take as much salt out of the boiler as is 
 deposited in the boiler by the separation of the steam used in that stroke. By 
 these means, the water in the boiler can never exceed a certain predetermined 
 degree of saturation ; and whether the engine be working quickly or slowly, 
 the quantity withdrawn may always be made to bear the same proportion to the 
 quantity left in, thus avoiding one of the greatest evils to which steam vessels 
 in making long voyages have been subjected. To economise the heat and con- 
 sequent expenditure of fuel, Messrs. Maudslay and Field further propose that 
 the hot brine extracted by the pump be discharged into a vessel containing a 
 series of metal pipes of small calibre, similar to a refrigeratory. Through these 
 pipes, which lie immersed in hot brine, the supply water is to be made to pass 
 in order to abstract the heat in its progress, and deliver the sea-water into the 
 boiler in a heated state. 
 
 In the year 1 824, Mr. Smith introduced, in some of the salt works of Lan- 
 cashire, a mode of evaporating brine, by the application of high-pressure steam 
 under the salt pans ; and as the surfaces of these vessels are very extensive, they 
 are incapable of sustaining much pressure. Mr. Smith, therefore, tied the 
 bottom of the boiler to the bottom of the pan (which also formed the top of the 
 boiler), by means of screw bolts and nuts, in the manner shewn at b in the sub- 
 joined sectional figure. Finding this arrangement productive of a safe and 
 
 efficient generator of high pressure steam, he subsequently took out a patent 
 for a modification of it, to be applied to steam engines. This modification 
 chiefly consisted in the addition of the upper vessel a. The plan of these vessels 
 is supposed to be a parallelogram, and the screw bolts about 9 inches apart in 
 each tier, over their whole surfaces. The water is supplied by a force pump, as 
 represented, and a number of guage cocks are fixed at different elevations, as 
 shewn in the drawing, to ascertain the height of the water, and the state of the 
 steam in each vessel, e e are steam pipes; / is a safety valve to the lower 
 chamber b, and g another to the upper chamber a. The" patentee states, that 
 "about two inches of water are put into the lower vessel, and the other being 
 half filled, the fire is lighted, which quickly raises the water in the lower vessel 
 to ebullition, the steam of which acts upon the lower surface of the upper boiler, 
 giving out its heat to the water contained therein, and is thereby itself condensed;
 
 BOILERS. 213 
 
 and being thus alternately vapourized and condensed, the upper vessel is con- 
 verted into a steam chamber of uniform temperature." Although this boiler is 
 calculated to generate steam with rapidity, owing to the extensive surface of 
 metal exposed to the direct action of the fire ; and notwithstanding it muse be 
 deemed safer than most others of equal capacity and effect, by reason of the 
 numerous tie bolts; it must, we think, be expensive in construction, and very 
 difficult to preserve free from leakages. 
 
 In the generality of boilers the flue first takes a horizontal direction, more or 
 less extended, and afterwards ascends the chimney ; sometimes it is also made 
 to descend ; and in almost every way that ingenuity could devise, the flues have 
 been made to encompass the water, for the purpose of transmitting their heat 
 thereto. Mr. Joseph Gibbs, of Crayfoi'd, in Kent, has, however, invented a 
 boiler, (patented in 1830,) which possesses some claims to originality of arrange- 
 ment ; and as it probably confers some advantages, we shall here notice it. The 
 form of the upper portion of this boiler is circular, with a descending cylindrical 
 branch of considerable magnitude and length, the latter being quite full cf 
 water, and the upper filled to about four-fifths its depth, the remaining one-fifth 
 being reserved for steam room. In the middle of the upper vessel is the fire- 
 place, the air for combustion being supplied by a vertical pipe, passing upwards 
 through the descending cylindrical branch of the boiler. The products of com- 
 bustion first act upon the water in the upper vessel, whence the flue descends 
 in a curvilinear direction around the vertical air pipe in the midst of the water 
 contained in the descending branch of the boiler, to the bottom thereof, and 
 thence into the chimney. For the ready passage of the smoke, a temporary 
 flue, which proceeds in a direct line to the chimney, is opened whilst lighting 
 the fire, after which it is stopped by a damper or valve, which causes the current 
 of heated matters to take the descending course described. By this arrange- 
 ment, Mr. Gibbs extracts the gaseous products of the fuel, till they are reduced 
 to nearly the temperature of cold water, the supply water being introduced 
 where the flue terminates. In the specification of this patent, Mr. Gibbs has 
 also represented a long cylindrical boiler, placed horizontally, with three 
 descending branches, and another with a flue is a zigzag direction, through 
 the descending part of the boiler, which, although it has the advantage over 
 the others of being of more easy manufacture, is not so favourable to the 
 descent of the current. The partial action, owing to the unequal distribution 
 of heat upon the different parts of a boiler, it was long since observed had a 
 tendency to produce circulating currents of water throughout the vessel. This 
 motion of the fluid has of late years been deemed of so much importance in 
 the economical generation of steam, as to have induced several engineers to 
 obtain patent privileges for their schemes : amongst these, Mr. Jacob Perkins 
 is most conspicuous, for having taken out two patents for the same object, one 
 in 1831, and the other in 1832. But as nature is inclined to perform the cir- 
 culatory process pretty well without the assistance of art, we shall dismiss the 
 subject with a brief notice of the above-mentioned gentleman's plans. In the 
 first of these, Mr. Perkins placed a thin metallic lining inside of the boiler, at a 
 small distance from the bottom and sides, but leaving an opening in the lining 
 at the bottom, where the heat of the fire is the strongest. Here, therefore, the 
 water will acquire the greatest levity, and consequently ascend, while the water 
 next to it, which is that between the lining and sides of the boiler, will occupy 
 the bottom of the rising column, and thus a constant circulation will be kept up 
 through the whole of the fluid in the vessel. In Mr. Perkins's second patent, 
 which is stated to be for improvement on his former one, the aforesaid linings 
 are to be augmented so as to cover a more extended surface, and form nearly 
 a complete internal vessel at a few inches distance from the external one. It 
 would require a large volume to describe the multiplicity of forms that have 
 been introduced in the construction of boilers and their appendages, with the 
 view of economising the production of steam. Those which we have already 
 given, however, afford a general outline of the whole, with the exception of 
 such as are employed in steam navigation. In these, it is an essential condition 
 that the fire-place and flues should be entirely surrounded wHh water, so as to 
 
 E E
 
 314 BOILERS. 
 
 prevent any contact of those parts with the wood-work of the vessel. We shall 
 rive two examples of boilers of this description. 
 
 Fig. I 
 
 m 
 
 The above engraving is descriptive of the boiler used in the United Kingdom 
 steam packet, of 1,000 tons burthen, measuring in her keel 148 feet, and breadth 
 of beam 14 feet, and propelled by two engines of 100 horses each, manu- 
 factured by Mr. Napier, of Glasgow. The boiler is of wrought iron plates,
 
 BOILERS. 
 
 215 
 
 25 feet 6 inches long, 19 feet broad, and 8 feet 6 inches high. There are eight 
 rectangular tuhes b b ninning lengthways of the boiler ; in each of tnese is a 
 fire at one end on the bars c c, shown in section. At the farther end of ths tubes 
 is a transverse one d, extending the whole breadth of the boiler, which commu- 
 nicates with every one of the tubes containing the fire ; at each end of d on 
 the top, a return tube e e carries off the smoke and fire into another transverse 
 tube/, out of the centre of which the chimney g rises. The cocks h h h are for 
 ascertaining the height of the water in the boiler ; but there is added a simple 
 contrivance, by which the necessity of employing the cocks h is avoided. There 
 are two cocks i i which are placed the one considerably above, and the ' her as 
 much below, the assumed level of the water; these cocks communicat nth a 
 vertical tube of glassj of sufficient strength to withstand the force of the steam. 
 On the cocks i i being opened, water enters into the lower one, and steam into 
 ihe upper one, and the pressure being the same in the boiler, the water stands 
 at the same level in the glass tube, which indicates the height of the water in 
 the boiler. 
 
 In the subjoined engraving, which represents a patented arrangement by 
 Mr. Steenstrup, a Swedish gentleman, in this country, the boiler is divided into 
 
 Fig. I. 
 
 Fig. 2. 
 
 an upper and lower chamber, in connexion with the side chambers, and by 
 means of vertical tubes. Fig. 1 is an end elevation of the boiler; Fig. 2 a 
 transverse section ; and Fig. 3 a longitudinal section, the same letters designating 
 similar parts in each, a is the upper division, or steam chamber ; b the lower 
 chamber, connected with the upper by the side vessels, and by the vertical tubes 
 c c, as shown in the section; at d is the fire bars, on which the fuel is deposited; 
 e the fire bridge ; / the ash pit ; g part of the chimney, likewise surrounded 
 with water at the lower end, which is in contact with the vessel ; h is the steam
 
 216 
 
 BOLOGNIAN STONE. 
 
 pipe, and k the man-Viole. It will be observed that the vertical tubes c e besides 
 forming a support to the weight of water in the upper chamber, and opening a 
 free communication with it, receive, from their position in the fire-place, the 
 strongest heat, and consequently give off steam quicker than the other parts of 
 the boiler, in particular those whioh pass through the fire bars, producing thereby 
 those ascending and descending currents, which are deemed so advantageous in 
 the generation of steam : also, from the great capacity of the fire chamber, that 
 fuel of any kind, however bulky, may be easily employed, by merely shifting 
 the fire bridge accordingly. In the description of the common waggon-shaped 
 boiler in the early part of this article, the manner usually adopted of feeding 
 boilers with water was explained. The necessity of a due supply of the fluid 
 is so great, as to have induced numerous inventors to devise plans for insuring 
 its accomplishment. Several of the most approved arrangements for this purpose 
 are detailed in Galloway and Hebert's History of the Steam Engine ; and we 
 shall close the present article by the description of another of great simplicity 
 and effectiveness, which was patented by Mr. W.Taylor of Wednesbury since the 
 
 publication of the before-mentioned work. In the above figure, a shows a portion 
 of the boiler ; b a water reservoir or feeding vessel, made steam tight ; c a pipe 
 through which b is supplied with water, having a valve d opening inwards, e is 
 a steam pipe, extending from the boiler to nearly the top of the close vessel b, 
 and c is a water pipe extending from the bottom of the close vessel to the 
 interior of the boiler. In both these pipes are stop cocks e and /, with levers 
 extending to g, by which they are opened and closed. In these levers are two 
 longitudinal slits, for the reception of a pin fixed in a rod extending from the 
 float h, through a stuffing box in the top of the boiler. Now when the water in 
 the boiler evaporates till its surface descends, and permits the weight of the 
 float to bring down the levers to the position represented, the cocks will be 
 opened, and the steam will rise through the pipe e, by which the pressure will 
 be equalized in the boiler a an<4 the supply vessel b, and water will descend 
 through /till its surface in the boiler rises sufficiently high to raise the float and 
 shut the valves; and then the condensation of steam in b will cause a partial 
 vacuum, permitting a fresh dose of water to pass through c into the feed vessel. 
 BOLOGNIAN STONE. This stone is the ponderous spar, or native sul- 
 phate of barytes, the phosphoric property of which was first discovered by an 
 Italian shoemaker. If it be first heated to ignition, then finely powdered, and 
 made into a paste with mucilage, and this paste divided into pieces a quarter 
 of an inch thick, and dried in a moderate heat, be exposed to the heat of a wind 
 furnace, by placing them loose in the midst of the charcoal, a pyrophorus
 
 BOLTING MACHINE. 
 
 217 
 
 will be obtained, which, after a few minutes' exposure to the sun's rays, will 
 give light enough in the dark to render the figures on the dial-plate of a watch 
 visible. 
 
 BOLTING MACHINE. A part of the machinery of a flour mill, by 
 which the flour is separated from the meal, which operation is termed dressing 
 the flour. It usually consists of an hexagonal reel, over which is drawn a sack, 
 called the bolting cloth, of considerably larger diameter* than the reel, and 
 composed of a peculiar species of duck made for the purpose. The reel is placed 
 in an inclined position, and made to revolve rapidly within six bars of wood, 
 called beaters, fixed to a case or box, within which the reel revolves. The 
 
 reel being turned with great velocity, the centrifugal force would throw out the 
 bolting cloth to its utmost extent were it not intercepted by the beaters ; the 
 repeated blows from these first force the flour through the interstices of the 
 cloth, and subsequently, at the tail end of the reel, the offal consisting of bran, 
 pollard, and sharps. The above engraving represents Ayton's improved 
 Flour Bolting Mills, constructed upon the principle just described, but provided 
 with the means of more easily and effectually regulating the tension and elas-
 
 218 BONES. 
 
 ticity of the bolting cloth, so as to produce in it a uniform and powerful vibra- 
 tion, which is effected by secured loops at one end of the cloth to six elastic 
 steel arms or springs, instead of the stiff arms of the common construction. 
 Fig. 1 is a plan or front view of the steel arms a a, and Fig. 2 a side view 
 of the same in section. These arms are rivetted to a ring of metal c, and at 
 their outer extremities are formed into broad flat hooks to receive the loops of 
 the bolting cloth, for which purpose they are nicely rounded and smoothed. 
 The ring c is secured by two conical pointed screws to another ring d, placed 
 within c, sufficient space being left between the two rings to allow a small degree 
 of play. The ring d is in like manner secured to the central socket e by means 
 of two other conical pointed screws, with a similar allowance for play ; the two 
 rings c and d forming a kind of universal joint. The socket. e is put over the 
 square part of the spindle of the reel, and fixed at any part of its length by 
 means of a tightening screw. Fig. 3 represents the improved bolting machine, 
 with the front pannels of the case in which it is inclosed in order ; the beaters 
 h h h h are fixed, the two which are in front of the machine being shown in 
 dotted lines ; i is the revolving axis or spindle, to which is fixed a light hemi- 
 spherical frame m, over which the bolting cloth is drawn, and made fast to the 
 circular ring or curb n, by means of a string running in a band of leather 
 sewed to the head of the cloth to strengthen it ; the loops to the " tail leather " 
 at the other end of the machine are fixed to the spring arms a a, already 
 described and shewn in their place upon the axis i, by which means the most 
 perfect and equal tension of the bolting cloth is obtained, and the beaters being 
 adjusted to a proper distance, the operation of bolting is very effectually per- 
 formed. Another improvement, although not claimed in the patent, is the sub- 
 stitution of four cloth fanners for the wooden rails, which compose the reel in 
 the ordinary machine. The fanners are constructed as follows: upon the spindle 
 i are fixed two " maces " or bosses k k, from each of which radiate four arms ; 
 from each of the arms on the mace, a piece of duck, about six inches broad, is 
 stretched to the arms of the other mace as shewn at / I. When a rapid motion 
 is given to the reels, the pieces of duck / / set the air in brisk motion, by which 
 much of the flour is forced through the bolting cloth, the tension and tremulous 
 motion of which, by the elasticity of the springs, tend to prevent the clogging up 
 the interstices of the cloth, and the operation of bolting proceeds with great 
 regularity and expedition. Accompanying the description of the machine in 
 the patentee's circular, are several certificates from respectable millers of its 
 superior efficacy, which state that nearly double the quantity of meal is bolted 
 in a given time. There is another description of dressing machine, in which a 
 cylinder composed of wire gauze of various degrees of fineness is employed to 
 sift the meal instead of a bolting cloth. 
 
 BOMBASINE. A well known stuff, produced by various mixtures of cotton 
 and silk. 
 
 BONE ASH. The residue of burnt bones. The process is conducted in 
 the open air, in large heaps, and the earthy salt which remains forms on an 
 average about half the weight of the fresh bone. It is composed chiefly of 
 phosphate of lime, and is used by the assayers as the material for cupels, and 
 for other purposes. 
 
 BONES. The hard insensible substance of which the frame or skeleton of 
 animal bodies is formed. Although the proportion of the ingredients vary in 
 the bones of different animals, as also in different parts of the same animal, the 
 general constituents of bones are as follows : gelatin or jelly, soluble in hot 
 but not in cold water ; fat, separable by boiling, when it rises to the top of the 
 water, and becomes concrete in cooling ; phosphate of lime in large quantity ; a 
 little sulphate and carbonate of lime ; and a cartilaginous substance retaining 
 the form of the bone after every thing else has been extracted, by boiling and 
 by acids. The uses of bones in the arts are very numerous. Both in their 
 natural state and dyed, they are made into knife handles and various articles of 
 turnery ware. They are extensively used in the manufacture of ammonia, the 
 refuse forming bone black ; or calcined to whiteness in the open air, they form 
 bone ash, which see. They are also employed in the preparation of milky
 
 BONE MILL. 
 
 219 
 
 glasses and porcelains, for the rectification of volatile oils, and in the preparation 
 of glue ; and recently in France, large quantities of gelatin have been extracted 
 from bones, which has been subsequently made into soups for hospitals, soldiers, and 
 restaurateurs. The process is as follows : the bones are first broken into small 
 pieces, and then thrown into a kettle of boiling water, and boiled for a quarter of 
 an hour. When this has become cold, a quantity of fat, amounting in some in- 
 stances to nearly a fourth of the weight of the bones, is found at the surface of the 
 liquor,and is applicable to manyuseful purposes. After this, thebones are ground, 
 and boiled in eight 01 ten times their weight of water, until about one half is wasted, 
 when a very nutritious jelly is obtained. M. Darcet recommends, instead of 
 grinding the bones, which is a work of great labour, to treat them with dilute 
 muriatic acid, which dissolves the salts of lime, leaving the gelatin untouched, 
 and retaining the form of the bones ; this is afterwards to be repeatedly washed 
 in clear cold water to free it from all taste of the acid, and then if not required 
 for immediate use, to be thoroughly dried by long exposure to a gentle heat, after 
 which it is little affected by the atmosphere, and will keep for a great length of 
 time. It should be observed, that the bones should not be boiled in copper 
 vessels, as gelatin quickly attacks that metal. Bones are likewise extensively 
 used in agriculture as a manure, when reduced to a coarse powder ; and large 
 quantities are collected for this purpose from various parts of the kingdom, as 
 well as from abroad, and sent to Yorkshire, where most of the bone mills are 
 established, to be ground. The annexed, Fig. 1, represents a side elevation 
 
 of a bone mill of an approved construction, a a is one of the side frames, b 
 the driving shaft carrying a pinion c, which turns the wheels d to the axis e, 
 and the wheel / upon the axis g ; h i are a pair of fluted rollers fixed to their 
 respective shafts e and k, and turning in contrary directions by the action of 
 the two wheels I and m, also affixed to the same shafts; n and o are another
 
 220 BOOKBINDING. 
 
 pair of rollers affixed to the shafts q and p respectively, and likewise turned in 
 contrary directions by a pair of wheels upon the same axes. These rollers are 
 composed of a series of wrought iron discs, with teeth resembling those of a 
 ratchet-wheel, and fixed up the shaft, with a plain disc of smaller diameter 
 interposed between each pair of the toothed disc, as shewn in Fig. 2, and so 
 arranged that the toothed discs on one shaft shall face the plain discs on the 
 other. The most valuable part of the bones is first removed by a circular saw, 
 and set apart for the uses of turners and others; the joints and refuse are then 
 put into the hopper q, and descending upon the rollers h i, are crushed, and fall 
 into the hopper r, whence they pass between the rollers I m, where they are 
 reduced to a coarse powder, which is conducted by the shute s (in dotted lines) 
 to the receiver. To prevent the teeth of the rollers being broken by any 
 excessive resistance, the plummer blocks, which support the shafts k and p, are 
 not fixed to the side frame, but are retained in their places by pins passing 
 through chase mortises in the frames, allowing the blocks to slide along the 
 frame, and the rollers are kept in contact by means of weighted levers to a, 
 pressing upon short studs y z, attached to the plummer blocks, which carry the 
 shafts k p. 
 
 BOOKBINDING is the art of securing together a number of separate leaves 
 into one book, and is of very great antiquity, the invention being generally 
 attributed to one of the kings of Pergamus, to whom we are also said to be 
 indebted for the invention of parchment Bookbinding, properly so called, 
 includes the binding of all printed books ; while vellum-binding is the term 
 applied to the binding of every description of account books. The two branches 
 are quite distinct, and seldom, if ever, successfully practised by the same in- 
 dividual; we shall therefore describe each brancn separately, beginning with 
 bookbinding. Although the limits of this work preclude the possibility of 
 entering minutely into all the practical details of the subject, yet it is hoped 
 that the following account will be found to contain a clear and connected view 
 of the nature of each process, and of the tools employed, with a brief notice of 
 some of the more striking attempts at improvement. 
 
 In binding printed books, they are generally received by the binder in sheets, 
 which are folded into quartos, octavos, duodecimos, &c., as the case may be. 
 This process is assisted by certain catch-marks or signatures, printed at the 
 bottom of each sheet, by attending to which, and keeping the folio of one page 
 on the folio of another, and at the same time preserving the necessary corre- 
 spondence between the foot of each page, the work will be properly folded, and 
 an uniformity of margin preserved throughout the work. The book having been 
 folded and pressed, is next beaten on a large smooth stone, with a cast iron 
 bell-shaped hammer, weighing from twelve to fourteen pounds. This beating 
 requires great care and skilfulness on the part of the workman, and various 
 attempts have been made, at different periods, to supersede the process, by the 
 use of hydraulic and other powerful presses ; these, however, have proved unfit 
 for the purpose, generally creasing and disfiguring the work. Mr. Burn, of 
 Hatton Garden, has, however, succeeded in rendering books extremely compact 
 and solid, by passing the sheets, when folded, between a pair of powerful 
 rollers; and this method will eventually supersede the old laborious and imperfect 
 one of hammer -beating. The apparatus of Mr. Burn consists of two iron 
 cylinders, about 12 inches in diameter, adjustable in the usual manner by 
 screws, and worked by manual labour applied to one or two cranked handles. 
 A boy sits in front of the press, who gathers the sheets into packets by placing 
 two or more upon a piece of tin plate of the same size, and covering them with 
 another piece, and thus proceeding, by alternating tin plates and bundles of 
 sheets, till a sufficient quantity have been put together, which will depend 
 greatly on the thickness and hardness of the paper, &c. The packet so formed 
 is then passed between the rollers, and is received by the man who turns the 
 winch, and who has time to lay the sheets on one side, and hand over the tin 
 plates, by the time that the boy has prepared a second packet. The time 
 occupied in this process is about one-twentieth of that requisite for beating. It 
 is not merely a saving of time, however, that is gained by using the rolling-
 
 BOOKBINDING. 
 
 221 
 
 press, for the paper is rendered much smoother, and" the compression of the 
 book is one-sixth greater than could have been obtained by beating. The 
 Society of Arts presented Mr. Burn with their silver Vulcan medal for his 
 invention, which is now in very general and extensive use. Newly-printed 
 works will not admit of beating or rolling, and books which are only to be 
 boarded, do not require more than a good pressing. After beating or rolling, 
 the book is collated, and the plates (if any) put in their respective places. It 
 is then put in the standing press, and after remaining there a short time, is taken 
 out, and the waste leaves added at the beginning and end. The book is then 
 taken up between the extended fingers of each band, and the back and head 
 knocked up nice and square'; one side of the book is then laid upon a pressing 
 board as large as the book itself, beyond which the back must project about half 
 an inch ; a second pressing-board, corresponding in size and position with the 
 former, is placed upon the upper side, and the board being firmly grasped with 
 the left hand, the book is lowered into the cutting-press, which is screwed up 
 tight, and a certain number of grooves, according to the size of the book, are 
 cut in the back with a tenon saw, for the reception of the cords on which the 
 book is to be sewed. After sawing, the sections are parted by passing a folding 
 stick up and down between them. The book is then taken to the sewing-press, 
 of which the accompanying is a representation. It consists of a stout flat 
 
 board a a, and two upright screws b b, with a long opening between them. A 
 top rail c rises and falls upon the screws by means of two nuts d d. Several 
 cords, suited in size and number to the kind of books which are to be sewn, are 
 attached to the rail c, and set to correspond with the sawed grooves in the 
 back of the book; the cords being carried down through the aperture in the 
 bed of the press, are fastened underneath by means of brass keys, of which e 
 is a representation. The number and distances of the bands are quite arbitrary, 
 and are disposed according to the fancy of the workman ; it may, however, in 
 general, be regulated as follows: 32mos. three bands; 18mos., 12mos, 8vos., 
 and two-leaf 4tos. four bands ; royal 8vos. and whole-sheet 4tos. five bands ; 
 and folios from five to seven bands. In sawing the back two extra grooves are 
 made, one at each end of the book, for the catch or kettle-stitch. The book 
 being placed with the back towards the sewer, and the title uppermost, the fly- 
 leaf or end paper is first laid upon the press and sewed to the cords, by passing 
 the needle in the first right-hand groove or catch-stitch mark, with the right 
 hand ; the left hand being kept in the middle of the section, receives the needle
 
 222 BOOKBINDING. 
 
 and draws it through, leaving two or three inches of the thread undrawn. The 
 needle is then returned out on the head side of the band, received by the right 
 hand, and passed through on the other side of the band, by which the thread is 
 conducted round each band in succession. The needle being carried along the 
 inside of the section, and led round each band in this manner, is at last brought 
 out of the last groove or left hand catch-stitch mark. The first section of the 
 book is then taken and sewed to the bands in the same way; when the needle 
 comes out at the catch-stitch mark, over the end of the thread left out of the 
 fly-leaf in the first sewing, the thread is tied to it in a knot. The remaining 
 sections are then sewn, the thread being fastened through the catch-stitch of 
 each preceding section. Care must be taken not to draw the thread of the 
 catch-stitches too tight, but to keep the back equally swelled. A number of 
 books may be sewed one on another, till the press is three parts full, care being 
 taken to finish off the sewing of each book, and not to catch- stitch them together. 
 The proper number of books being sewed, the strings are cut from the rail, and 
 unfastened at the bottom ; the books are then separated and the bands cut apart, 
 leaving about two inches on each side of the book. After sewing, the back of 
 the book is glued; and when that is dry, the ends of the bands are opened and 
 scraped. If the book is to be lined, which is customary with all half-extra and 
 other superior work, it is now done, either with fine coloured or marble paper. 
 If with marble paper, the sheet is folded with the plain side outwards, one half 
 of it being pasted ; it is laid between the fly-leaves, into the fold of which it is 
 closely worked ; the other half is then pasted, and the next fly-leaf rubbed 
 down upon it, any superfluous edges being cut off with the shears. This done, 
 the back is next to be rounded, which is effected by laying the book on the 
 press cheek, with the fore-edge towards the workman, who presses the fingers 
 of his left hand upoii the book, and at the same time draws it towards him, 
 gently tapping the back up and down with a hammer, alternately changing the 
 sides until the book is uniformly and effectually rounded. The back is then 
 squeezed in the cutting press for a few minutes, which sets it, and the book is 
 then ready for baching. This consists in forming a projection of the back on 
 each side of the book, sufficient to cover the boards, and is done by placing 
 cutting boards on each side of the book, within about a quarter of an inch of 
 the back, or according to the size of the book, care being taken that the boards 
 are parallel with the back, and at equal distances from it. The boards being 
 tightly grasped by the left hand, are lowered into the cutting-press and screwed 
 tight ; the back is then hammered gently and uniformly all over, which causes 
 it to spread over the boards so as to form the required ledge or projection. If 
 any roughness appears on the back, it is removed by scraping, and cleaned off 
 with paste and paper shavings. The boards for the cover, which are brown 
 milled boards, having been cut to the required size with shears, or ploughed in 
 the cutting press, two holes are pricked with a bodkin for each band, one of 
 them directly opposite the band, the other about an inch beyond it. The first, 
 for 8vos , should be about half an inch from the edge of the board, the others 
 about an inch, or for larger works still forwarded. The bands are then drawn 
 through the outer side of the board, and passed through the other hole to the 
 outside again, where the ends are spread and pasted. Each board is then opened, 
 and laid separately on a smooth piece of iron, and the strings hammered flat. 
 The boards, which should not be put on too tightly, having been properly 
 adjusted, and the back examined to see that it has not been deranged, and the 
 defects, if any, remedied with the backing hammer, the next step is cutting 
 the fore-edge. For this purpose the boards are thrown out of the grooves or 
 ledges, and then brought to a perfect level with the back by knocking on the 
 cheeks of the press ; a cutting-board (of oak or beech, and rather wedge-shaped) 
 is then placed on the left hand side of the book, and another, called a runner, 
 on the right ; the whole is then placed in the cutting-press, the runner being 
 brought even with the right cheek of the press, and when properly adjusted, 
 the press is screwed up, and the fore-edge ploughed. After cutting the fore- 
 edge, the book is taken out, and the back rounded as before, when a corresponding 
 groove will be formed in the front. The head is next cut by knocking the
 
 BOOKBINDING. 
 
 223 
 
 boards straight up with it, keeping them in the ledge produced by backing ; 
 the cutting-board and runner are then applied as before, and the head ploughed. 
 For cutting the opposite 
 end, the hoards are slipped 
 below the head as much 
 again as it is intended they 
 shall project, which should 
 be rather less than on the 
 fore-edge. A small piece 
 is then taken off the inner 
 corner of each board ; and 
 the boards being replaced, 
 there will be found a suffi- 
 cient projection for both 
 ends. 
 
 The cutting-press which 
 has been referred to, con- 
 sists of two strong wooden cheeks / g, connected by two slide bars h h, and 
 two wooden screws i i. Upon the cheek / are two guides for the plough to 
 work in. 
 
 The plough, which is the cutting 
 instrument, consists of two sides, k I, 
 connected by a screw m, and two slide 
 bars, n n. A knife o is fastened to the 
 under side of the cheek I, by a strong 
 square bolt, which takes into a groove 
 cut on the circumference of the screw 
 m, and prevents it from moving later- 
 ally in the eheek. When the screw 
 is turned, therefore, the two sides of 
 the plough approach to or recede from 
 each other. 
 
 Various attempts have at different 
 times been made to improve the cutting- 
 press and its appurtenances. Mr. 
 Baxter, of Lewes, proposed to obviate 
 most of the inconveniences attending 
 the use of the common plough-knife. 
 His improved knife consisted of a brass 
 or gun-metal stock p, having a dove- 
 tailed groove on its under surface, in 
 which slides a steel blade or cutter r, 
 which is kept in any required position 
 by a set screw on the upper part of the stock at *. The great advantage 
 of this knife is, that when once properly adjusted, the blade may be changed 
 and ground ad infinitum, without deranging the adjustment of the stock. 
 
 In the year 1806, the Society of Arts presented Mr. J. Hardie, of Glasgow, 
 with a reward for an improved cutting- press for bookbinders, which is delineated 
 in the cut at the top of page 224. t is the left hand cheek of the press, con- 
 nected with a frame v v v, having two grooves on the inside, in which the cheek 
 w slides backward and forward by means of the iron screw x, which is secured 
 to it by a collar at y. z are the guides for the plough. The advantages 
 claimed for this press are its simplicity, great power, and increased facility of 
 use, as compared with other presses. 
 
 But the most striking improvement is in a cutting-press recently constructed 
 by an ingenious mechanic named Penny, which promises to be of great practi- 
 cal utility; for with this press, an indifferent workman will cut the edges of 
 books or paper with mathematical accuracy and precision, which the very best 
 cutter with the old press could never accomplish. Penn'ys press consists of 
 two cheeks, with screws and slide bars, as in the ordinary machine ; but to the
 
 22f 
 
 BOOKBINDING 
 
 tmder side of the left hand cheek, a framing A A is attached, which projects 
 some distance under the other cheek. Within this frame, a platform B rises and 
 falls, perfectly parallel with the 
 upper surface of the press, by 
 means of a rack to which the 
 platform is attached. A pinion 
 at C, gives motion to the rack. 
 On the axis of the pinion, and 
 on the left hand side of the 
 press, there is a large wheel D 
 which the workman turns with 
 his hand, to give the platform 
 the necessary elevation, fixing 
 it in any position, by means of 
 a small catch. As the platform 
 moves perfectly parallel with 
 the surface of the press, and at 
 right angles to the frame A A, 
 it follows that any thing resting on the platform will be cut true throughout its 
 whole thickness. This has been shewn to be the case, by taking off consecu- 
 tively, shavings from paper the thirty-second of an inch wide, which were per- 
 fectly accurate throughout, from first to last. The surprising accuracy of this 
 press, however, would be of little avail with ploughs and knives of the usual 
 description. Mr. Penny has therefore so far improved the plough as to make it 
 a fit accompaniment to his press. For this purpose, the sides, screw, and slide- 
 bars are made with considerable care, the under surface of the sides being shod 
 with metal, which on the 
 right hand side is formed 
 into an appropriate bed for 
 the knife, as at E. The 
 knife is of the form shewn 
 at F; the blade is placed 
 directly unde* the screw, 
 and secured by two screw 
 bolts, in lieu of one. The 
 bed for the knife being 
 metal, and the knife itself 
 being accurately finished, 
 no tedious adjustment is 
 ever necessary. The knife 
 being in the centre, stands
 
 BOOKBINDING. 22.1 
 
 to its work well, and the plough does not twist about like the old ones. Mr. Penny 
 received a reward from the Society of Arts, in 1832, for his improved plough. 
 The standing-press employed by bookbinders is usually the common screw-press, 
 worked by a long lever, to which the power of a windlass is sometimes added. 
 Having thus briefly noticed some of the machinery which is employed by the 
 bookbinder, we return to the book, the edges of which had just been cut ; the 
 next thing, therefore, is to ornament its edges, which is done either by colouring, 
 sprinkling, marbling, or gilding. The first of these processes is the most 
 simple, and is that usually adopted for the commonest work. The books being 
 laid one on the other, or screwed in the cutting-press, the colour is applied with 
 a sponge. The colours mostly employed for this purpose, are Spirit-blue, 
 Brown-umber, King's-yellow, Dutch-pink, Spanish-brown, and Vermilion, mixed 
 with size. Sprinkling is performed by dipping a stiff brush in the colour, and 
 striking it upon the press-nin held in the left hand, by which means the colour 
 is thrown upon the books in fine spots, and a little practice enables the workman 
 to distribute them very equally all over the edges. Better kinds of books, however, 
 are generally marbled on the edges, the patterns being made to correspond with 
 the marble paper lining. Marbling is performed as follows : a trough is pro- 
 vided of a convenient size, about two inches deep, which is filled with clean gum- 
 water ; various coloured pigments, ground in spirits of wine, and mixed with a 
 small quantity of ox-gall, are then thrown upon the snrface of the gum-water, and 
 disposed in various forms, according to the pattern that is desired, with a quill 
 and comb. The proper pattern being obtained, the book is tied between two 
 boards, and the edges dipped into the trough, when the floating colours become 
 transferred to the book; cold water is immediately dashed over the edges, 
 which sets the colours, and gives them a clear appearance. If the edges are to 
 be gilt, they are nicely cut and tied between two boards ; they are then sponged 
 over with yellow-ochre, which is scraped off, and the edges rubbed dry with 
 paper shavings. Parchment size, or a size composed of equal parts of water 
 and white of eggs, is laid upon the book edge, and covered with gold leaf; it 
 is then dried gradually, and before it gets quite hard, is buniished with an agate 
 burnisher. The edges are then protected from injury during the remainder of 
 the process by a paper covering. Head-banding then follows. Head-bands are 
 of two kinds, stack on and worked. The stuck-on head-band is formed by 
 cutting a piece of striped or coloured linen about an inch deep, and equal in 
 length to the thickness of the book ; one side is pasted, and a piece of well-twisted 
 cord laid across one third of its width; it is then folded over, enclosing the 
 string, and worked well up to it. The back of the book being glued, the 
 linen is laid upon it, the cord or head-band being placed flat upon the end of 
 the leaves. For all extra work, however, the head-bands are worked in the 
 following manner. A strip of thick vellum, board, or string, prepared by rolling 
 it tight in pasted paper, is taken of a dimension suited to the size of the book ; 
 stout well-twisted silk, of two or more colours, is then taken ; if two colours are 
 used, they are doubled and tied together by the ends, one of them being previously 
 equipped with a needle. The book is then placed in the cutting-press with the 
 back uppermost, the head towards the workman, and considerably elevated ; the 
 needle is then passed through the middle of the second section, on the left-hand 
 side, just below the catch-stitch, and drawn out far enough to bring the knot 
 joining the two silks close into the middle of the section ; the needle is then brought 
 up, and passed again through the same place, and the silk drawn nearly close ; 
 the round strip is placed in the loop thus formed, and the silk drawn tight 
 with the left hand ; the other silk is brought over with the right, and passed 
 under and over the head-band, when that is held tight with the left hand ; the 
 other silk is now put over that, and also under and over the head-band ; they 
 are thus worked alternately over each other, as far as the middle section of 
 the book, through which the needle is passed below the catch-stitch, and 
 brought over the head-band, when the working is proceeded with as before, as 
 far as the last section but one; the needle is passed through this section, and 
 over the head-band twice, and finally fastened on the back. The ends of the 
 head-band are then cut off, almost close to the silk at each end. The part
 
 22G BOOKBINDING. 
 
 produced by working one silk over the other is called the braiding, which forms 
 the principal beauty of the head-band, and should be ranged close down upon 
 the leaves of the book on the inside of the band, which is easily managed. 
 Both ends of the book having been worked in this way, the glue brush is 
 drawn across the back of the bands, which strengthens them and keeps them 
 in their proper places. It is now the usual practice to make a hollow back, on 
 account of its enabling the book to open better, and also preserving the leather 
 from cracking. The hollow back is formed by cutting a strip of cartridge 
 paper twice the width of the back, and the same length ; this is folded in half, 
 and the back being fresh glued, one half of the folded paper is stuck on, the 
 other half being doubled upon it. If the book is to have raised bands, they 
 are now put on ; they are formed of strips of thick leather, as wide, and at 
 such distances from each other, as taste directs ; they are glued on the loose 
 back, and pared down at the ends, the sides being kept sharp and square. 
 They are used to give a neat appearance to the back, and are a great improve- 
 ment on the old method of sewing the book on raised bands in lieu of the 
 sunken cords. The book is then ready for covering, with leather, if to be 
 whole bound, or with leather and paper, if to be only half-bound. For whole 
 binding the leather is cut about half an inch larger all round than the book, 
 and carefully pared round the edge with a sharp knife on a piece of smooth 
 marble ; it is then pasted, folded together, and left a few minutes for the paste 
 to soak in ; it is then opened out, and the book laid on one half (the fore-edge 
 being towards the workman), while the other half is carefully and tightly drawn 
 over the back and uppermost cover; the covers being then adjusted at the 
 head and foot, and pulled forward, the edges are turned down and the ends 
 tucked in ; the corners being raised are worked together, and the part so raised 
 cut off, and the head and foot pieces being smoothed down, the fore-edge part 
 is folded over them. The head of the book is then neatly set with the folding- 
 stick, pressing it inwards in the joint where the corner was taken off the boards, 
 and flatting the leather over the top of the head-bands ; the form thus given in 
 the damp state is permanently retained when dry. If the raised bands, previously 
 described, are used, a piece of fine cord is tied round the book, (the edges being 
 guarded with a piece of board), pressing on the upper and lower side of each 
 band, which brings the cover close upon the back, and preserves the distinctness 
 of the bands. For half-bound books a strip of leather is cut, about an 
 inch longer than the back of the book, and of sufficient jridth to lay well over 
 the boards ; the leather corner pieces are cut of an oblong quadrangular shape. 
 The leather being pared, the corner pieces are put on first, and the back 
 afterwards, being worked in the same manner, and with the same care, as the 
 whole-hound book. Marble, coloured, or other fancy paper, is cut of a proper 
 size and form, and pasted on the sides. Smooth sheep and calf bindings are 
 frequently ornamented by marbling or sprinkling, which is performed by throwing 
 various colouring liquids on the cover while it is wet with water : but there is 
 so great a variety in these processes, both of colours and patterns, that there is 
 not space for their enumeration here ; nor are they of much importance at this 
 time, the coloured leathers having been brought to such perfection, and in so 
 general use, as to render the employment of sprinkling, &c. of more rare 
 occurrence than formerly. The forwarding of the book is now completed, and 
 it is handed over to the finisher. The first step of the finisher is to wash the 
 cover of the book with paste or glue water, to prevent the glaire from sinking 
 in and staining the cover ; when the sizing is dry the cover is glaired. Morocco 
 and roan require to be glaired but once, sheep twice, and calf three times ; this 
 done, the book is ready for gilding and lettering. The places where the gilding 
 is to be applied, are then slightly greased with palm or sweet oil, and covered 
 with gold leaf. While lettering and gilding the back, the book is placed in the 
 cutting-press, with the head a little elevated. The brass letters having been selected 
 and laid in their proper order before a fire, are moderately heated ; before using, 
 they are tried on a piece of waste leather ; when at the proper temperature, 
 they are forcibly impressed upon the gold, one after the other, care being taken to 
 keep them straight, upright, and at uniform distances a process which requires
 
 BOOKBINDING. 
 
 227 
 
 great practical skill. The whole of the letters being worked, the superfluous 
 gold is wiped off with an oiled rag, to which it adheres, and when saturated, 
 the rag is sold to the refiner, who recovers the gold which it contains. Common 
 words of frequent use, such as Bible, Prayer, Album, &c. &c. are cut in one 
 piece, and worked oft' at once, which greatly facilitates the process of lettering, 
 while it insures a uniformity of appearance not otherwise attainable. Metal 
 types are sometimes used as an excellent substitute for the brass letters ; with 
 the former, any word may be set up in a frame and worked at once, but it is 
 essentially necessary that the types are clean and bright ; there is also some 
 difficulty in giving them the proper temperature ; it would therefore be a great 
 improvement to have brass letters cut so that they might be set up in a frame, 
 in the same manner as the types. These would combine the beauty and accuracy 
 of the brass letter, with the convenience of the types. The lettering having 
 been completed, the remainder of the book is gilt with appropriate tools ; these 
 in general consist of straight lines or fillets, rolls of various breadths and patterns, 
 and single ornamental devices, all cut in brass, and used the same way as the 
 letters. The tools are frequently heated, and worked upon the leather without 
 the interposition of any gold, which produces a neat and elegant contrast to the 
 gilding ; it is denominated blind-tooling. Whole bound books are frequently 
 very handsomely gilt on the sides as well as the back, frequently by running a 
 broad gold roll round the edges of the cover, and sometimes by means of corner 
 and centre pieces, with or without lines. The following ingenious method of 
 working these ornaments was designed by Mr. Bain, of Broad-court, Long-acre, 
 who received the silver Isis medal and five pounds, from the Society of Arts, 
 for his invention. The brass ornaments used for the covers are mostly triangular 
 ones for the corners, the centre being formed by the combination of the same 
 or other four pieces. In the ordinary manner of working, a single tool is used, 
 which requires to be applied eight times on each cover, or sixteen times in all 
 on each book. This occasions the loss of much time ; to save the greater part 
 of which, Mr. Bain employs four triangular blocks, capable of being fixed in a 
 simple adjustable frame, so as to suit any sized book. The frame a a in the 
 accompanying engra- Fi 2 p - j 
 
 ving, is made to hold 
 the rods b b parallel to 
 each other, and allow 
 them to be set at any 
 required distance apart. 
 cccc are the stamps, 
 which are perforated 
 to slide on the rods b b 
 quite even with each 
 other ; they are fixed 
 at the proper distances 
 on the rods by small 
 set screws at their back, 
 which bind upon the 
 rods. The frame a a 
 has two long apertures, 
 seen in Fig. 2, to receive 
 the rods b b, which have 
 square shoulders and 
 fins to traverse along, 
 and are bound fast by the screwed nuts, dd shows one of the rods, with its nut 
 separate. The small nuts e screw on after the stamps, to keep them from falling 
 off the rods before they are adjusted. It will be seen that by sliding the stamps 
 c along the rods b, and these rods along the frame a, they may be adjusted to 
 suit any size and form of book. When the corners are done, if the same stamps 
 are to be used for the centre, they may be transposed on the rods, and adjusted 
 to suit the centre, as shown at//; but it will save time, and do the work truer, 
 to have four rods b b and// to hold the corners and centre stamps at the same
 
 228 BOOKBINDING. 
 
 time, for then once putting in the press does one side of the book, and all will 
 be exactly alike, without much care on the part of the workman. If the frame 
 a a is made a little wider than the thickness of the stamp on the pattern side, 
 it might be adjusted to touch the fore-edge of the book, which would keep the 
 pattern quite straight and equidistant on each book. By this contrivance, not 
 only is time saved, but the patterns are registered much more accurately than 
 they could possibly be by any other method. When very large lettering pieces, 
 ornaments, or coats of arms, &c. are to be gilt upon the covers of books, manual 
 pressure is inadequate to the working of them, and a press is employed, called 
 an arming press. A very perfect machine of this description has recently been 
 constructed by Messrs. Cope and Sherwin, of London, to which they have given 
 the name of the " Imperial Arming and Embossing Press," which is not only 
 capable of working every description of gilding, but is also sufficiently powerful 
 to emboss the elegant arabesque covers, at present so much employed for 
 ornamental bookbinding. The largest description of these covers are embossed 
 by means of a fly-press of enormous power, but for all smaller work the imperial 
 press is amply sufficient. In its construction it resembles the improved printing 
 press invented by the same parties, but with the addition of a contrivance for 
 raising or lowering the bed to suit the thickness of the book, and the platten 
 likewise having receptacles for the heating irons. By means of a screw-and- 
 wedge adjustment in the piston, and the rising and falling bed-plate, a considerable 
 range, with the power of very accurate adjustment, is obtained with great facilitv 
 This machine is exceedingly simple in principle and construction, elegant in 
 appearance, and effective in operation, and is a valuable auxiliary to the book- 
 binder. The book having been gilded, it is polished with a hot iron* and the 
 edges, if coloured or marbled, are burnished with an agate burnisher: the book 
 is then finished. If the book was only intended to be put in boards, or, as it is 
 technically called, boarded, it is folded, sewed, glued, the covers cut to the size 
 and put on, and then covered with coloured paper, the edges of the book 
 remaining uncut. Extra boarding has stouter boards than the former, and is 
 finished with rather more care ; sometimes the edges are cut, and the book 
 covered with a neat coloured and embossed or printed cloth, which gives a very 
 neat appearance at a cheap rate. 
 
 VELLUM BINDING, as was before observed, is the term applied to the binding 
 of every species of account book. The first step is to fold and count the paper 
 into sections, which in foolscap generally consists of six sheets ; above that 
 size, of four sheets, which are sewed upon strips of vellum. Small books, up 
 to foolscap folio, usually have three strips ; above that size the number is 
 increased. Account books are sewed much in the same way as printed books, 
 except that vellum slips are used in lieu of the cords, and a much stronger thread 
 and wax are employed. After sewing, the first ruled leaf at each end is 
 pasted to the waste paper, and the marble paper lining introduced ; the back is 
 then glued in the usual manner. When the glue is dry, the fore-edge of the 
 book is cut, and the back rounded, a deeper hollow and rounder back being 
 formed in account books than in printed ones. The two ends are then cut, and 
 the edges marbled. The head-bands are worked on a slip of stout board, as 
 before described, care being taken in this instance to form a deep narrow, rather 
 than a round band. Strong pieces of canvass or buckram are then glued at the 
 top and bottom of the back, and between each of the vellum slips. A hollow 
 back is prepared by taking a slip of milled board, about a quarter of an inch 
 wider than the back of the book, and soaking it in water ; it is then glued on 
 both sides, and left in this state for about ten minutes : having been laid on a 
 sheet of paper, a roller corresponding in dimension with the back of the book 
 is placed upon it, and the whole worked backward and forward on the roller, 
 which gives the milled board a semicircular shape ; it is then dried hard before 
 the fire. _ Another method, which is a very good one, and frequently adopted, 
 consists in taking a roller (an assortment of the most useful sizes being kept for 
 the purpose), and winding round it thick paper and wrappers well pasted, until 
 the requisite thickness is obtained; the roll is then thoroughly dried and 
 divided longitudinally, which forms two good firm semicircular backs. Milled
 
 BORING BIT. 229 
 
 boards of a thickness proportionate to the size of the book are then taken, and 
 the tty-leaf of the book being pasted, the board is laid on in its proper place ; 
 the same course is also pursued with the other side. It is customary with 
 large books to use two thin boards pasted together, instead of one thick one : 
 in this case the vellum slips on which the book is sewn, are inserted between 
 them, which adds greatly to the strength of the binding. After the boards have 
 been squared, the back, formed in the manner described above, exactly fitting 
 the back of the book, is placed upon it, and a piece of canvass being cut suffi- 
 ciently large to extend half the width of the back on one side of the book to 
 the same distance on the other side, is glued on the boards and over the back, 
 which contributes to strengthen the book, and hold the hollow back firmly in its 
 place. The back is sometimes formed of sheet iron, which, in large books, is 
 an improvement : this kind of back was first introduced by Mr John Williams, 
 who took out a patent for his invention. The book is now ready for covering : 
 the leather for the cover is carefully pared all round, and put on as before 
 described under the head of Bookbinding. The covers mostly used by vellum- 
 binders are forril and vellum, white and coloured ; smooth and rough calf and 
 sheep ; basil, smooth and grained, and Russia ; in any of which books may be 
 either whole or half-bound. Forril and vellum covers are lined with paper and 
 pressed smooth ; when dry, they are fitted on the back, and creased in the 
 joints ; the boards are then pasted, and the covers pressed on them; when dry, 
 the edges of the cover are pasted and turned in, and the book again pressed ; 
 the cover is then washed with a sponge and paste-water, and then ruled off. If 
 the cover is rough calf or sheep, it is dressed with pumice-stone and a clothes 
 brush. Smooth calf, basil, &c. are glaired and polished as described in book- 
 binding. Rough calf books are usually ornamented by passing a roller round 
 the edges and sides of the cover, with sometimes an ornament added ; for this 
 purpose, the tools must be used nearly red hot. To increase the strength of 
 large books, they sometimes have, in addition to the leather or vellurn cover, 
 bands of Russia leather, which ar worked on with thongs of vellum, and give 
 the book a very neat appearance. The lettering of account books is precisely 
 the same as before described. 
 
 BORACIC ACID. An acid which, combined with soda, forms borax, or 
 borate of soda. As obtained by the action of sulphuric acid upon a solution of 
 borax, it is in the form of thin irregular hexagonal scales, of a silvery whiteness, 
 having some resemblance to spermaceti, and the same greasy feel. By fusion, 
 it is converted into a hard transparent glass, which is used in the composition 
 of false gems. 
 
 BORAX. A compound of soda and boracic acid, and of considerable use 
 in various metallurgic operations. It enters into the composition of reducing 
 fluxes, and is of the greatest use in analysis by the blow-pipe. It is more 
 especially used in soldering; it assists the fusion of the solder, causes it to flow, 
 and keeps the surface of the metal in a soft clean state, which facilitates the 
 operation. It may also be applied with advantage in glass manufactories ; for 
 when the fusion turns out bad, a small quantity of borax re-establishes it. 
 
 BORING BIT. A tool or instrument used for making aper ures in wood, 
 metal, or other hard substances. They are of various shapes, too common to 
 
 workmen to need description ; but one of a very peculiar and effective kind, 
 represented above, was brought from Germany by Mr. Donkin, and is described 
 in the Transactions of the Soc'tety of Arts. Fig. 1 is a front view of the boring
 
 230 BORING MACHINES. 
 
 bit ; a a the cutting edge ; b b a thread or fin, winding round the back, which 
 acts as a screw to draw the bit into the wood, fig- 2 is a side view of the same. 
 The instrument is very simple, enters the wood rapidly, and forms a clean hole. 
 BORING MACHINES. A name usually confined to machines for giving 
 a perfect form to metallic cylinders, as pump barrels, blowing machines, &c., 
 which machines differ from lathes in the circumstance of the tool revolving, 
 whilst the work either remains stationary, or advances in a right line. In all 
 boring machines, a long bar, called the boring bar, passes through the cylinder, 
 and revolves in bearing or supports. To the boring bar are fixed a number ot 
 steel cutters, which, as they revolve, receive also a motion endways, and are 
 carried through the whole length of the cylinder to be bored. The boring 
 machine used for the smaller and coarser description of pump work is extremely 
 simple in its construction. It consists of a boring bar, somewhat more than 
 double the length it will ever be required to bore, and supported by bearings 
 distant from each other not quite half its length, A mortise is cut through the 
 boring bar, and the cutters are firmly fixed in it by wedges or keys. Into a 
 socket in one end of the bar is keyed a screw about half as long as the bar, 
 and its outer extremity supported in a nut fixed in a standard, the axis of the 
 screw and of the bar exactly coinciding or forming a continuous right line. 
 The bar being passed through the cylinder to be bored, and the cylinder being 
 secured upon beds so as to be concentric with the bar, the latter is turned round 
 either by a winch or a wheel, fitted upon the end opposite the screw ; and the 
 screw making a revolution in its nut for each revolution of the bar, advances 
 the bar and cutters through a corresponding space along the cylinder. For 
 cylinders of larger diameter, and requiring more accuracy in the boring, a 
 different construction becomes necessary. The cutters are fixed upon the cir- 
 cumference of a short cylinder, termed the cutter-block, through which the 
 boring bar passes; and either the two, as they revolve together, receive a slow 
 end motion, or the cutter block only advances whilst the bar revolves, but remains 
 stationary. There are various modes of advancing the cutters in either case. 
 The following extremely ingenious arrangement, in which the boring bar and 
 cutter advances, carrying with it the cutter block, is, we believe, the invention 
 of Mr. Murray, of Leeds. Upon the extremities of a horizontal bed of cast 
 iron are fixed two upright standards, supporting brass bearings, in which the 
 boring bar turns. Upon the cast iron, bed are two blocks, for supporting the 
 ends of the cylinder, with arrangements for adjusting it, so that its centre shall 
 coincide with the axis of the boring bar, and to these blocks the cylinder is 
 firmly secured by straps or chains. The boring bar is turned perfectly cylin- 
 drical, and has a groove extending from one end more than half its length. 
 The cutter block, which is a disk nearly of the same diameter as the cylinder, 
 and armed at the circumference with a number of steel cutters, is firmly keyed 
 upon the bar in the space lying between the standard. Upon the grooved end 
 of the bar, and close to the outer face of the standard, is the driving wheel, the 
 centre of which is bored of the same diameter as the bar, so as to allow the 
 latter to slide within it freely, but without shaking, whilst the wheel is prevented 
 from turning without causing the bar to revolve, by means of a steel key, fitting 
 into the groove in the bar, and into a similar groove in the boss of the wheel. 
 A screw, half as long as the bar, is supported at the outer end by a nut, which 
 is at liberty to turn in bearings placed upon a vertical standard, whilst the inner 
 end of the screw, formed into a square, is keyed into the end of the boring bar. 
 Parallel to the screw is a small shaft, having at one end firmly fixed a small 
 wheel geering into another small wheel fixed upon the face of the nut, whilst 
 another wheel, which turns with the shaft, but is at liberty to slide along it, 
 geers into a wheel fixed upon that end of the bar to which the screw is attached. 
 The operation of the machine is as follows: The driving wheel turns the 
 boring bar, and with it the screw. Now if the nut were to remain at rest, the 
 screw would advance through a space equal to the rake of the screw, and draw 
 after it the boring bar ; but if the nut, by properly proportioning the diameters 
 of the small wheels, revolve in the same direction as the cutter bar, but with a 
 Jess velocity, then the cutter bar and screw will advance through a space
 
 BORING MACHINES. 
 
 231 
 
 proportioned to the difference between the velocities; so that if the speed of the 
 cutter bar exceed that of the nut by one-tenth, the screw and cutter bar will 
 advance through only one-tenth of the rake of the screw. In the boring 
 machines for cylinders of very large dimensions, the cutter block usually 
 advances, whilst the boring bar remains stationary. In these machines the 
 boring bar is sometimes placed horizontally, but we think a vertical position 
 preferable, as the weight of a long horizontal bar occasions a tendency to sink 
 in the middle ; also when the bar is vertical the cylinder is more easily fixed, 
 and the borings, instead of clogging the cutters, fall upon the base plate. The 
 annexed engraving represents a vertical boring machine of a new and improved 
 construction, which was erected in an extensive engineering establishment, and 
 of which we believe no description has yet appeared in print. Upon a foundation 
 
 plate a are bolted three standards, of which only two b c are shown, the third 
 being removed to show the boring bar. These standards support the top plate 
 d, formed of three radiating arms ; e is a steadying bridge, which may be set at 
 any height, by means of screws passing through the mortises in the standards, 
 and secured at the back by nnti ; / is the bed to which the work is bolted, for 
 which purpose it has a numbc/ of mortises radiating from the centre ; it is 
 supported by brackets gg projecting from the standard; h is the boring, turning 
 in collars in the top plate d and in the bridge e, and supported by the step t ; 
 k the cutter-block, which is a stiff wheel, bored out accurately to receive the 
 boring bar, so as to slide upon it easily, yet without any shake. On the 
 periphery of the block are eight notches, in which the cutters are fixed by 
 wedges ; I a bevelled wheel, and m a pinion by which a rotatory motion is 
 given to the boring bar and cutter block, the latter being made to advance along 
 the former by the following means : Upon the top plate d is a small triangular
 
 ? 33 BOUINCi MACiilNKS. 
 
 frame n, to which is bolted the bevelled wheel o, in which another wheel p 
 geers. p revolves in bearings fixed upon the head of the boring bar, and has 
 upon its axis an endless screw driving the worm-wheel q, which is fixed 
 upon a long screw r, lying in a mortise cut in one side of the boring bar. 
 This screw turns in collars s and t, and works in a nut fitting into the mortise 
 in the boring bar, and attached to the cutter block at v ; the bevelled wheel 
 p is 10 inches in diameter, and the wheel o 16 inches ; therefore in ten 
 revolutions of the boring bar, the wheel p will perform sixteen revolutions on 
 its axis, and at each revolution the endless screw upon its axis will move the 
 worm wheel q one tooth forward ; and as the worm wheel has sixteen teeth, in 
 ten revolutions of the boring bar the screw r, to which the worm wheel is 
 attached, will make one turn, and will advance the cutter block through a space 
 equal to the space between the threads of the screw, a; is a strong spindle 
 screwed into the frame n, and formed with a conical point, which is received 
 into a conical steel bush in the centre of the head of the boring bar, and prevents 
 the bar from rising. 
 
 BORING THE EARTH FOR WATER. An economical process has been practised 
 of late years for obtaining water from great depths, without the expense of 
 sinking a well. This process consists simply in boring the earth with an auger 
 and other proper instruments, to a considerable depth ; and in most situations 
 water will flow either to the surface, or to within a short distance from it ; in 
 some places it has been known to spout to a considerable height above it. It 
 has long been a question whence these springs derive their supply, and how 
 they acquire the power of ascension. The most natural supposition is, that 
 they are connected by subterraneous channels with some elevated reservoir ; 
 but this explanation is not altogether free from difficulty. These "Artesian wells," 
 as they are termed, are to be met with in the middle of extensive plains, at a 
 great distance from any hills, and upon the sides of mountains, which require 
 to be bored to a great depth before the water is attained. At Mount Rouge, at 
 Paris, 80 feet above the level of the Seine, there is one of these wells 315 feet 
 deep. If, therefore, these wells be supplied from an elevated reservoir, it must 
 lie at a very considerable distance from the wells. The implement* made use of in 
 the process are extremely simple, and are represented iu the engraving on the 
 following page. A is the cross handle of the borer, for twamen to work ; B the chisel 
 borer, which is made to screw into A ; C the auger, which also screws into A; D a 
 lengthening rod, having at one end an external screw fitting the screw of A, 
 and at the other end a hollow screw like that in A, so that all the instruments 
 which fit into A may, as occasion requires, be screwed into the lengthening 
 piece D. A great number of these lengthening rods are kept in readiness, 
 which can be screwed one into the other, so as to descend to the depth of 
 several hundred feet. E a forked iron, used to lay across the hole to support 
 the rods at the joints, while the pieces are being screwed and unscrewed ; F a 
 spanner, used to screw on and unscrew the various tools and lengths of rods , 
 G a clearing chisel, with a probe or piercer attached to guide it ; H a spring 
 bar, used to produce a vibrating up-and-down motion to the chisel, when used 
 to peck away hard or rocky ground ; I iron chain to connect the cross handle 
 of the tools to the spring bar ; J two men at work, boring with the chisel ; K 
 the lower pulley of a pair of blocks, suspended to a pair of shears or a triangle 
 above ; L the shears or compasses ; M winch or crane, to work the blocks 
 when great weights are to be raised; O three lengths of rods, and the chisel in 
 the act of boring, perforation about 42 feet. As a preparatory measure, a 
 large hole is usually dug to the depth of seven or eight feet ; at the bottom of 
 which a floor is formed, by means of some planks, for the men to stand on and 
 pace round whilst using the instruments. If the earth is very soft, the only 
 tool requisite is the auger C of three or four inches diameter, which is screwed 
 into the cross handle A, and the perforation is easily effected by the mere 
 turning of it round by two men, as shewn in the drawing. When the auger 
 has penetrated to nearly the depth of the tube, it is withdrawn, and cleared of 
 its contents. It is then let down again, and the perforation is in this manner 
 continued to the whole length of the instrument. To proceed to a greater
 
 BORING MACHINES. 
 
 233 
 
 depth, the lengthening rods, before described, are put in requisition. The auger 
 is detached from the handle by unscrewing it ; a piece of rod D is screwed in 
 its place, and the auger screwed on to the rod. With the instrument thus 
 lengthened seven or eight feet, the boring is renewed by means of the auger, as 
 long as the earth is found to be sufficiently soft and yielding. Whenever it proves 
 otherwise, or hard and rocky, the auger is detached from the rod, and the 
 chisel B, which is from three to four inches in diameter at its edges, is screwed 
 on in its place. If the ground is not very hard, the boring may be continued 
 
 by the chisel, by the workmen pressing upon it as they turn it round ; but when 
 the earth is too hard to be operated upon by a chisel in this way, recourse is 
 had to pecking, which is done by lifting up the instrument, and striking it against 
 the opposing substance till it is chipped away, or reduced to powder to a certain 
 depth. The rod and chisel are then again drawn up, and the auger substituted 
 for the chisel, for the purpose of extracting the pulverized stony matter contained 
 in the hole. The chisel and auger are thus employed alternately where the 
 ground is hard and stony, the one for chipping away or pulverizing, and the 
 other for clearing out. As the perforation deepens, the process of pecking
 
 234 BOTTLE. 
 
 becomes very laborious; recourse is therefore had to the spring bar H, which is 
 a strong pole placed horizontally over the well, at the height of three or four 
 feet from the ground, with one end inserted into a post or other stronghold. 
 The chain I is attached to this bar, and the borer is suspended by the handle 
 to the hook of the chain which supports its weight ; a slight vertical motion is 
 then given to the bar by the workmen, which causes the chisel to peck away 
 with great rapidity. As the weight of the implements becomes too great to be 
 drawn up by hand, when the boring has proceeded to a great depth, the 
 mechanical aid of a pair of pulley blocks K is used for the purpose, which are 
 usually suspended from a triangle or a pair of shears fixed over the hole. The 
 higher these shears are the better, so as to enable the workmen to raise a great 
 length of rod, without unscrewing at each joint of the rod. In the manner 
 described the boring proceeds, changing the tools from time to time for such as 
 may be best suited to cut through the various strata, whether of a soft, indurated, 
 or stony texture, until the main spring is arrived at, when the water flows up 
 the newly-formed tube to the height of the distant spring from which it is 
 derived. If that be at a greater altitude than the surface of the earth bored, 
 the water rises above the ground, producing a perpetual fountain ; on the con- 
 trary, if it be below the surface, a well must be sunk of some capacity, down 
 lower than the level of the spring ; into this well the water flows and forms a 
 reservoir, and may be raised to the surface by means of a pump. The earth is 
 sometimes bored by the before-mentioned simple apparatus to the depth of two, 
 three, or four hundred feet, either for the purpose of obtaining water, or to 
 ascertain the presence of minerals. To carry on the operation at these great 
 depths, a corresponding increase of power is required, which is obtained in a 
 variety of ways. When the hole is bored, a pipe of cast iron or other metal is 
 forced down it, to prevent its being filled up again by the falling in of the 
 surrounding earth, and likewise to keep out the impure land springs which 
 might taint the water. Although the process conducted as above described is 
 extremely simple, it is very tedious and laborious, owing to its being necessary 
 to withdraw and unscrew the whole of the rods each time the earth requires to 
 be removed from the boring tool, and to screw them together again upon 
 returning the borer. To obviate these inconveniences the editor has suggested 
 a method by which the operation may be carried forward at great depths, 
 and the earth extracted without withdrawing the rods, by which also full 
 three-fourths of the time and labour may be saved. The means by which it is 
 proposed to effect this desirable object are as follows : An auger is to be made 
 with a spiral worm winding round a cylinder which forms its centre. The 
 cylindrical part is not to be solid, but perforated throughout its whole length by 
 a square hole of two or more inches diameter, for the purpose of receiving 
 within it an iron bar of the same figure and admeasurement. The bar will 
 thus serve the double purpose of a spindle or shaft to work the auger or cause 
 it to bore, and of a slide upon which the auger may be drawn up with facility 
 to the surface from very great depths in a few seconds of time, its contents be 
 discharged, and the auger be let down again as quickly, to proceed in the perfora- 
 tion of a fresh portion of earth. That a part of the contents of the spiral auger 
 may not fall out when being drawn up, the worm or thread is not to be left open, 
 but is to have a perpendicular border, raised upwards at right angles to the 
 plane of the thread ; the aperture between the upper edge of this border and 
 the next thread is left open for clearing out the auger with facility. The 
 construction will be easily understood by referring to the engraving, in which 
 P represents the exterior of the spiral worm or auger ; Q the square iron bar 
 passing through the square tube of the auger ; R chains to draw up the spiral 
 worm along the bar ; S top plate, to which the chains are attached ; T upper 
 view of the plate, showing the square hole through which the bar passes ; U 
 angular point of the square bar ; V V cutting edges of the auger ; W under 
 side view of the bottom cutting parts of the auger. Various kinds of tools may 
 be attached to the bottom of this auger so as to peck, &c. 
 
 BOTTLE. A vessel with a narrow mouth or aperture, used to contain 
 liquids; and usually composed of "lass or earthen ware. Under these two
 
 BOTTLE. 
 
 235 
 
 Leads will be found a description of the process of manufacturing them ; we 
 shall, therefore, in this place, briefly notice some inventions connected with 
 them, and which we could not introduce under separate heads. 
 
 The first is Master-man's patent apparatus for bottling wine or beer, which, as 
 usually performed, is a tedious and wasteful process ; but by the apparatus 
 which we are about to describe, the bottles may be filled uniformly to a precise 
 point, as fast as they can be changed, without the necessity of any examination 
 on the part of the workman. In the annexed engraving, a is the cask con- 
 
 taining the liquid to be bottled ; this cask must be closed perfectly air tight ; b a 
 cock, having a nozzle about 4 or 5 inches in length, and of a bore greater 
 than the area of the whole of the syphons, (hereafter mentioned ;) c a trough 
 about 14 inches long, 6 inches wide, and 4 inches deep, It is attached to the 
 frame d d in such a manner that its distance from the foot thereof may be 
 increased or dimished at pleasure ; e e e e are four metal syphons, having each 
 a leg of nearly equal length ; one leg of each is fixed to the inside of the front 
 of the trough, the other leg is outside of the trough about 3 inches from the 
 front of it ;/ is a trough to catch the liquid which may be spilt whilst changing 
 the bottles ; it can be slided up and down the frame, and has a rail g for the 
 bottles to stand on while filling; h h represents what the patentee terms an air 
 tube ; the cross piece i is of solid brass, bored only so high as to pass the end 
 of the tube soldered into it. The horizontal part of the tube is made of pure 
 tin, on account of its flexibility ; it is connected to the vertical part by a union 
 joint at fc ; I is an iron brace placed across the trough, to retain the air tube firmly 
 in its proper situation. The mode of using the machine is as follows; the trough 
 c is fixed so high in its frame, that the bottom comes within an inch of the oi'ifice 
 of the cock, and the air tube is fixed in the brace, so that its lower orifice may be at 
 least one inch above the orifice of the cock, and at least one inch below the top of 
 the trough, and the other end of the air tube is driven air tight into a hole either 
 through the bung of the cask, or through a hole made for the purpose in the cask 
 above the surface of the liquid therein. Upon opening the cock, the liquid flows
 
 236 BOTTLE. 
 
 into the trough until it rises so high as to close the orifice of the air tuhe, when the 
 air no longer having admission to the cask, the liquor ceases to flow. The syphons 
 are then put in action by exhausting the air out of them successively "by the 
 mouth applied to a bent tube, one end of which is placed against the syphon so 
 as to form an air tight tube within it. The outer end of each syphon, as it is 
 brought into action, is inserted in the neck of a bottle, and the point to which 
 the bottles are to be filled is brought to a level with the orifice of the air tube, 
 the rail g being adjusted so as to retain the bottles at this elevation. As the 
 bottles fill, the surface of the liquid in the trough sinks until it descends below 
 the orifice of the air tube, when the air rushes into the cask, and the liquid 
 recommences flowing ; and thus by this alternate action, the liquid in the trough 
 is always preserved nearly on a level with the orifice of the air tube. As each 
 bottle fills, it is withdrawn quickly from the syphon and replaced by an empty 
 one ; but if the bottles are suffered to remain, they will never fill higher than 
 the level of the orifice of the air tube, which it has been shown is the level to 
 which the liquid in the trough is confined. Another method of maintaining the 
 liquid in the trough at always the same level is described in the specification, 
 which we think is upon the whole preferable to that described above. It con- 
 sists in substituting for the air tube a species of valve, adapted to the lower 
 orifice of the cock, and regulated by a float on the surface of the liquid in the 
 trough, so that as the liquid rises in the trough, the float also rises, and causes 
 the valve to shut when the surface of the liquid has attained its proper level ; 
 and as the level sinks the float also sinks and opens the valve, causing the liquid 
 to flow again. When the float and valve are substituted for the air tube the 
 cask must have vent. 
 
 A most useful appendage to the foregoing apparatus, is the patent machine 
 for corking bottles, invented by Mr. J. Masterman, by the use of which all risk 
 of breaking the bottles is avoided ; the necessity of biting the corks, (a practice 
 highly injurious to the health of the workmen,) is done away with, the bottles are 
 corked in a very superior manner, and the whole operation conducted with 
 cleanliness, economy, and unprecedented dispatch. The following is a descrip- 
 tion of the machine, (with reference to the annexed engraving,) and of the man- 
 ner in which it is worked : a a a a represents the frame, b b two vertical guide 
 rods, connected at top by the bridging piece c ; d a cross head sliding upon the 
 upper ends of the guide rods, and connected by the side rod k k, to the levers g g, 
 which are united at the handle h, and which have their fulcrum at i. In the 
 cross head d are secured by nuts on its upper face three cylindrical metal 
 bolts, termed by the patentee " impellers ;" / is a cross piece of wood firmly 
 fixed to the guide rods, at such distance from their tops, as that when d is raised 
 close to the bridging piece c, there may be a space between the bottom of the 
 impellers, and the top of/, at least equal to the length of a cork. In/, are fitted 
 three conical metal tubes, immediately beneath, and concentric with, the 
 impellers. These tubes have their mouths larger, and their lower apertures 
 smaller than the corks, and are of three different sizes, which is sufficient to 
 meet the variations in the size of the bottles, whether for wine or beer ; I is a 
 treadle which, by means of the iron rod m fixed to its axis, raises and depresses 
 the wedge n ; this wedge slides on a cross piece of wood, (firmly fixed to each 
 side of the frame a,) in such a manner that the upper surface of the wedge is 
 always preserved in a horizontal position ; a loop of iron is fixed below its 
 thicker end, and in it the upper end of the bar m works. To use the machine, 
 the workman seats himself beside it with his right foot on the treadle ; he then 
 places a bottle so that its mouth is under, and in contact with, that tube which 
 is of the proper size for introducing the cork into it, and retains the bottle in 
 that position by raising the wedge against its bottom by means of his foot 
 acting on the treadle ; then raising the impellers by means of the lever, he puts 
 a proper sized cork into that tube which is in contact with the mouth of the 
 bottle, he depresses the lever, by which action the cork is forced by the impeller 
 into the neck of the bottle; then lowering the wedge bv the pressure of his 
 foot on the treadle, he removes the bottle, which completes the operation. This 
 we think is a most meritorious invention, and one deserving of general adop-
 
 BOTTLE. 
 
 237 
 
 tion. The patentee states, that " more than half the time is saved, owing 
 principally to the compression of the cork, and the impelling it into the bottle 
 being effected at one operation or motion of the lever. Twelve bottles have 
 been corked in one minute by way of experiment, and thirty dozen in an hour; 
 but one workman could cork with ease at the rate of five and twenty dozen per 
 
 hour throughout the day. The bottles also are better corked, partly owing tc 
 the corks being compressed and compacted, instead of being crushed or broken, 
 as in the common methods ; and partly from the corks, at the moment of entering 
 the bottle, being subjected to a pressure both on their tops and sides, which 
 causes them to become firmer and closer in the bottles, than when driven in 
 after being crushed by any of the common methods. 
 
 A patent has been obtained by Mr. H. Berry for forming bottle stoppers of 
 fndia rubber with the view of preventing the escape of volatile and other 
 thuds, which cannot be well retained by the usual means of stopping. To effect 
 this object several methods are described by the patentee in his specification ; 
 that which is shewn in the engraving represents the section of an ink bottle for
 
 238 
 
 BREAD. 
 
 the pocket, a is the glass bottle with the extre- 
 mity of the neck ground to an angular edge, where 
 it is brought into contact with a disc or button of 
 caoutchoc b fixed into the top of the exterior case, 
 which is of hard wood; the top being screwed 
 down as shewn in the figure, the glass edges of the 
 bottle are forced into the elastic substance, so as to 
 form a close and perfectly air-tight stopper. For 
 volatile salts, the patentee uses the ordinary glass 
 stoppers, and applies a collar of caoutchoc under 
 a projecting flange of the stopper, which presses 
 upon the upper surface of the neck. 
 
 BRAKE. In Mechanics, a contrivance for 
 retarding or arresting machinery in motion, by 
 means of friction. It generally consists of a sim- 
 ple or compound lever, pressing forcibly upon the 
 periphery of a broad wheel fixed upon one of the 
 shafts or' axes of the machine. 
 
 BRAN. The inner husk or skin of wheat, 
 which is separated from the flour by the boulting machine. It is employed in 
 the manufacture of starch, and also by dyers in making what they call the 
 sour water with which they prepare their several dyes. 
 
 BRANDY. The spirituous liquor obtained by distillation of wine, and 
 which, by further concentration, may be converted into alcohol. The best 
 brandy is made in France ; that made in Spain and Portugal is distinguished 
 by an acrid and disagreeable taste. 
 
 BRASS. An elegant yellow-coloured compound metal, consisting of copper 
 combined with about one-third of its weight of zinc. The best brass is made 
 by cementation of the ore of zinc with granulated copper. See ALLOY. 
 
 BRAZIL WOOD. A red-coloured wood, chiefly used in the process of 
 dyeing. The tree that affords it is the growth of the Brazils, in South America. 
 The wood is capable of a pood polish, and is so hard that it sinks in water Its 
 colour is pale when newly cut, but it becomes deeper by exposure to the air. 
 The various specimens differ in the intensity of their colour, but the heaviest is 
 reckoned the most valuable. It has a sweetish taste when chewed, and is 
 distinguished from red sanders or sandal, by its property of giving out its 
 colour to water, which this last does not. If the Brazil wood be boiled in 
 water for a sufficient time, it will communicate a fine red colour to that fluid. 
 The residue is very dark coloured, and gives out a considerable portion of 
 colouring matter to a solution of alkali. Alcohol extracts the colour from 
 Brazil wood, as does likewise the volatile alkali ; and both these are deeper 
 than the aqueous solution. The spirituous tincture stains warm marble of a 
 deepish red, inclining to purple, which on a greater heat becomes violet ; and if 
 the stained marble be covered with wax, and considerably heated, it changes 
 through all the shades of brown, and at last becomes fixed of a chocolate 
 colour. The colours imparted to cloth by Brazil wood are of little permanence. 
 A very minute portion of alkali, or even soap, darkens it into purple. Hence 
 paper stained with it may be used as a test of saturation with the salts. Alum 
 added to the decoction of this wood occasions a fine crimson red precipitate or 
 lake, wliich is increased in quantity by the addition of alkali to the liquor. The 
 crimson red colour is also precipitated by muriate of tin, but it is darkened by 
 the salts of iron. Acids change it to yellow, from which, however, solution of 
 tin restores it to its natural hue. A strong decoction of Brazil wood, with as 
 much alum as it can dissolve, and a little gum, forms a good red ink ; some 
 manufacturers add cochineal to give the colour more permanence and brilliancy : 
 good red ink may, however, be made without this addition. 
 
 BREAD. Various preparations of farinaceous substances bear this denomi- 
 nation ; but those which are chiefly used in this country may be distinguished 
 into three principal kinds. In the first, called unleavened bread, either flour 
 and water alone are mixed, or with the addition of some other substance, such
 
 BREAD. 239 
 
 as butter, eggs, sugar, and afterwards baked, by which the mass is reduced into 
 a solid state, sometimes flakey, but never cellular or spongy. Biscuit, or sea- 
 bread, is of the unleavened kind, for the process of making which see BISCUIT 
 In the second kind of bread, called leavened bread, the flour and water being 
 mixed together, is either left for some hours in a thin and almost liquid state 
 to ferment, that the saccharine matter contained in the flour may be spontaneously 
 changed into alcohol and carbonic acid gas, which expand by the heat of the 
 oven, and render the bread vesicular or spongy. Although this intestine change 
 will take place naturally at the temperature employed in the vinous fermentation, 
 it is usual to add certain substances, termed ferments, of which the barm of 
 beer, or yeast, is preferred, where it can be obtained. These accelerate the 
 fermentation of the dough, and cause it to take place simultaneously throughout 
 the whole mass of dough. In the third kind of bread, a vesicular appearance 
 is given to it by the addition to the dough of some ammoniacal salt, (usually 
 the sub-carbonate,) which becomes wholly converted into a gaseous substance 
 during the process of baking, causing the dough to swell out into little air 
 vessels, which finally bursting, allow the gas to escape, and leave the bread 
 exceedingly porous. Mr. Accum, in his Treatise on Culinary Poisons, has 
 stigmatized this process as "fraudulent," but, in our opinion, most unjustly. 
 The bakers would never adopt it but from necessity : when good yeast cannot 
 be procured, it forms an admirable and perfectly harmless substitute ; costing 
 the baker more, it diminishes his profit, while the consumer is benefited by the 
 bread retaining the solid matter, which by the process of fermentation is 
 dissipated in the form of alcohol and carbonic acid gas. To persons un- 
 acquainted with the nature of the flour of wheat, it is necessary to state that it 
 is composed of three distinct substances, which are easily separable by art : 
 first, a mucilaginous saccharine matter, soluble in cold water; much starch, 
 which will scarcely combine with water without the aid of heat ; and an elastic 
 adhesive grey substance, called gluten, which is insoluble in cold water, alcohol, 
 oil, or ether, and resembles an animal substance in many of its properties. To 
 the gluten in wheat flour is supposed to be owing its property of making so 
 tenacious a paste, and its peculiar facility of rising or expanding by the addition 
 of leaven. From the flour of barley, rye, oats, or potatoes, no gluten has been 
 extracted, probably from their containing too small a quantity ; and as these 
 substances are very difficult of fermentation by any of the ordinary processes, 
 it has been supposed that the presence of gluten is the cause of fermentation. 
 It is, however, more reasonable to suppose that the tenacious dough formed by 
 the admixture of gluten prevents the escape of the gaseous products of the 
 fermentation, and that these, by their expansion, swell the dough into a 
 vesicular mass, producing what is technically called light bread. M. Beccari, 
 of Bologna, and Dr. Cullen, inform us that by the addition of gluten to barley 
 and potatoes, they produced better bread from each than could be obtained 
 without this addition. Parmentier asserts that bread may be made from 
 potatoes alone ; but Mr. Edlin and Dr. Pearson, two very enlightened experi- 
 mentalists, state decidedly that this root cannot be fermented so as to make 
 bread, without the addition of wheaten flour ; and that no farinaceous substance 
 can be made into good bread that has not the three constituent parts of wheat 
 before-mentioned: for if to the starch of potatoes some of this glutinous 
 substance be added, with yeast and water, it will not form a bread, owing to 
 the absence of the saccharine or sugary extract on which the process of fermen- 
 tation depends, and which, if this last substance be added, even in a concentrated 
 state, will immediately commence. Although we have no knowledge of Par- 
 mentier's process, we believe that his assertion is perfectly correct ; for since 
 the experiments were made by Mr. Edlin and Dr. Pearson, the farina of potatoes 
 has been converted, on a great scale, into sugar and alcohol ; and it has been 
 long known that potatoe starch may be transformed, by the application of dry 
 heat, into a species of tapioca, of great tenacity and elasticity. With such 
 materials, we should imagine the skill of a Parmentier would hardly be necessary 
 in order to make good bread. In the making of leavened bread without the 
 addition of any article for exciting the speedy fermentation of the paste . a
 
 240 BREAD. 
 
 great deal of attention and skill are requisite. The spontaneous decomposition 
 is extremely slow ; the various parts of the mass are differently affected, 
 according to the humidity, the thickness or thinness of the part, the vicinity 
 or remoteness of fire, and other circumstances less easily investigated. The 
 saccharine part is disposed to become converted into alcohol ; the mucilage has 
 a tendency to become sour and mouldy ; while the gluten, in all probability, 
 verges towards the putrid state. An entire change in the chemical attractions 
 of the several component parts must then take place in a progressive manner, 
 not altogether the same in the internal and more humid parts, as in the external 
 parts, which not only become dry by simple evaporation, but are acted upon by 
 the surrounding air. The outside may therefore become mouldy or putrid, 
 while the inner part may be only advanced to an acid state. Occasional 
 admixture of the mass would of course not only produce some change in the 
 rapidity of this alteration, but likewise render it more uniform throughout the 
 whole. The effect of this commencing fermentation is found to he, that the 
 mass is rendered more porous by the disengagement of elastic fluid, which 
 separates its parts from each other, and greatly increases its bulk. The operation 
 of baking puts a stop to this process, by evaporating great part of the moisture 
 which is requisite to favour the chemical attractions, and probably by still 
 further changing the nature of the component parts. Bread thus made will 
 not possess the uniformity which is requisite, because some parts may be 
 mouldy, while others are not sufficiently changed from the state of dough. The 
 same means are used in this case as have been found effective in promoting the 
 uniform fermentation of large masses. This consists in the use of a leaven or 
 ferment (as before mentioned), which is usually a small portion of dough of the 
 same kind, but in a more advanced stags of the fermentation. To prepare an 
 original leaven, take 8 oz. of flour, and two pints of blood-warm water, and as 
 soon as the sponge begins to rise on the second day, add 1 Ib. of flour, and four 
 pints of water ; and thus proceed for a day or two more, when a mixture will 
 be obtained, which, being added to a quantity of flour and water intended for 
 bread, will determine the fermentation to take place throughout the mass in 
 three or four hours. It is only under peculiar circumstances that a recourse to 
 an original ferment is necessary ; for this ferment having been once obtained, 
 and the dough nearly ready for baking made from it, the fermentation of the 
 next parcel of bread is readily put in action by reserving some of the fermented 
 dough or leaven, as it is called, and using it for that purpose. To preserve this 
 leaven from becoming sour, several methods are adopted. In the north of 
 England, the leaven for the next week's baking is kept fit for use by being 
 buried a few inches deep in a sack of flour. In Italy it is said to be kept fresh 
 even for three months by being buried deep in flour. The French, if they 
 intend to use the leaven in a few days, keep it in a warm place between two 
 bowls, and add every day as much flour as the leaven weighs, and a sufficient 
 quantity of water to restore the original consistence ; but if it is not to be used 
 for a week, or longer, the scrapings of the kneading trough are cut into small 
 pieces, dried by a gentle heat, and when wanted, rubbed down with warm 
 water. It appears from the Scriptures, that the practice of making leavened 
 bread is of extreme antiquity ; but the addition of the scum that arises in the 
 vinous fermentation of beer, called barm or yeast, seems to be of modern date, 
 and is now in general use throughout the north of Europe. In this country 
 this yeast is generally used in the proportion of a pint to a 1 00 Ibs. of flour, and 
 is dissolved in the first parcel of water with which the flour is mixed, and no 
 leaven is used ; but at Paris, and other great towns in France, the dough is 
 made first with leaven, and a little yeast is added to the last parcel of water, 
 merely to increase the sponginess of the bread. Although we have given under 
 the head BARM an account of the nature of this useful ferment, and various 
 modes of preparing it, we shall here add some further information which more 
 immediately appertains to the manufacture of bread. If yeast is not to be 
 purchased, original yeast may be obtained by boiling a quarter of a peck (3 Jibs.) 
 of meal for eight or ten minutes in three pints of water, and pouring off' two 
 pints, which is to be kept in a warm place ; the fermentation will commence
 
 BREAD. 241 
 
 in about thirty hours, at which time four pints more of a similar decoction of 
 malt are to be added, and when this ferments, another four pints are to be 
 added, and so on, until a sufficient quantity of yeast is obtained. In Edinburgh 
 the bakers multiply their yeast daily, by mixing 10 Ibs. of flour with two gallons 
 of boiling water, and covering it up for about eight hours. Two pints of yeast, 
 made the day before, are then stirred in, and in about six or eight hours as 
 much new yeast will be generated as will suffice for 420 Ibs. of flour. When 
 original yeast is prepared from malt, the fermenting wort may be added to the 
 flour as well as the yeast, according to Mr. Stock, whose patent substitute 
 for yeast is merely wort in a state of fermentation. This wort is made from 
 2 Ibs. of malt, \ oz. of sugar, and 1 oz. of hops, to each gallon. Two gallons 
 of this wort are sufficient for 12 bushels of wheaten flour. The Hungarians 
 prepare a similar ferment for keeping all the year, by boiling in water in the 
 summer wheat bran (obtained in grinding for household flour,) along with hops; 
 the decoction soon ferments, and then a sufficient quantity of bran is flung in 
 to drink up all the liquid, and allow it to be formed into balls, which are dried 
 in a gentle heat. When wanted for use, some of these balls are broken, and 
 boiling water poured upon them, which, after some time, is strained off and used 
 to make up the dough. In like manner, the Romans prepared their ferment by 
 drawing off in vintage time a quantity of grape juice, while at the height of its 
 fermentation, pouring into it a sufficient quantity of millet flour to absorb it all, 
 and forming into small balls, which, when wanted, were broken, infused in 
 boiling water, and the whole then mixed with the dough. A similar ferment 
 may be prepared in this country from a decoction of raisins, which must sub- 
 sequently be either pressed between boards with a heavy weight, or be mixed 
 up with ground millet, as otherwise the strongest part of the must would remain 
 amongst them. In summer, the leaven, yeast, and even dough, is apt to turn 
 sour, and to communicate that taste to the bread ; this is remedied by stirring 
 a few tea-spoons-full of carbonate of magnesia into the ferment or dough. 
 
 Wheaten Bread. The nature of wheaten bread when raised with yeast has 
 been explained already at the commencement of this article ; but the importance 
 of the subject demands a more exact account of the established processes em- 
 ployed in the manufacture. Mr. Edlin wishing to obtain every information on 
 this subject, procured access to a bakehouse, and has given us the following 
 account " At three o'clock, they prepared to set the sponge, for which pur- 
 pose two sacks of household flour were carefully sifted through a brass wire 
 sieve. The following mixture was then prepared ; two ounces of alum was first 
 put into a tin vessel with a little water, and dissolved over the fire ; this was 
 poured into the seasoning tub, and nine pounds of salt were thrown in, over 
 which they poured two pails full of hot liquor ; when cooled to 84 of Fahren- 
 heit, six pints of yeast were added ; this composition was then stirred well 
 together, strained through the seasoning sieve, and emptied in a hole made in 
 the flour, with which it was mixed to the consistency of thick batter. Some 
 flour was sprinkled over the top, when it was covered up to keep in the heat 
 This operation is called setting quarter sponge. In three hours two pails 
 full more of warm liquor were stirred in, and the mass covered up as before ; 
 this is termed setting half sponge. Five hours afterwards five more pails of 
 warm liquor were added ; and when the whole was intimately blended, it was 
 kneaded for upwards of an hour. The dough was then cut into pieces, and 
 thrown over the sluice board and penned to one side of the trough ; some dry 
 flour being sprinkled over, it was left to prove, till about three o'clock in the 
 morning, when it was again kneaded for the space of half an hour. The dough 
 was taken out of the trough, put on the lid, and cut into pieces. It was then 
 weighed, and 4 Ibs. 15 oz. was allowed for each quartern loaf, the baker obser- 
 ving that a loaf of that size loses from 10$ to 11 ounces while in the oven. 
 It was then worked up, and the separate masses were laid in a row till the 
 whole were weighed, and in counting them afterwards, he found they were 
 equal to 163J quarteni loaves; but this circumstance is variable, as some flours 
 kneaded better than others. It should have been mentioned, that the fire was 
 kindled at two o'clock, and continued burning till near four, when the oven was
 
 242 BREAD. 
 
 cleansed from dirt and ashes. The bread being put in, the oven was close 
 stopped till seven o'clock, when it was opened, and the bread withdrawn." 
 
 Hoik. Mr. Edlin has likewise furnished the following mode of making rolls, 
 as witnessed by him in a London bakehouse. " The flour was sifted and mixed 
 in the same manner as was done for the bread ; at half-past six o'clock, they were 
 moulded up, and a slit was cut along the top of each with a knife ; they were 
 then set in rows on a tin, and placed in a proving oven to rise till a quarter of 
 an hour before eight, when they were drawn and set in the oven which was 
 closed as before ; at eight o'clock they were taken out, and were slightly 
 brushed over with a buttered brush, which gave the top crust a shining appear- 
 ance ; they were then covered up with a flannel till wanted for sale." 
 
 Brawn Bread, called also home-made, is usually fabricated of inferior or 
 coarse flour, including more or less of the bran ground over again into pollard ; 
 and the brown tint of the latter is usually heightened by the public bakers, by 
 the addition of the raspings of the burnt crust from other loaves. It has been 
 a fashion of late years to give the preference to this bread, under the notion of 
 its superior purity and wholesomeness, overlooking the obvious circumstance, that 
 its dingy colour affords a protection to the discovery of all sorts of adventitious 
 mixtures, besides that of dirty raspings. In making brown bread at home, the 
 case is of course different ; but here, owing to the deficient kneading it usually 
 receives, it acquires an anomalous taste, which some call sweet, others sour. 
 Being unsatisfactory to the appetite, the good lady in the country flatters her self- 
 love in observing the increased appetite of her metropolitan visitors, and 
 ascribes it to the excellence of her home-made bread, when, in fact, it arises 
 from its imperfections. Brown bread retains more water after baking ; hence 
 it keeps moist longer, but the middle usually crumbles away. 
 
 French Rolls, 8fc. That extremely delicate and vesicular small bread called 
 French is made in the following manner. To a peck of flour sifted through a 
 fine wire sieve, three quarters of a pound of butter are added, and rubbed 
 together in a kneading trough ; when these are intimately blended, two quarts 
 of warm milk, a quarter of a pound of salt and a pint of yeast are well mixed 
 with it, and a sufficient quantity of warm water to knead it into a dough ; it 
 must then stand two hours to prove, when it may be moulded into rolls or 
 bricks, which are to be placed in tins, and set for an hour in the prover. They 
 are afterwards put into a brick oven for twenty minutes, and when drawn 
 rasped. 
 
 Household Bread undergoes the same preparation as wheateti bread, with 
 this difference, that instead of being made with fine flour, it is made of an 
 inferior sort, called seconds flour. 
 
 Substitutes for Wheaten Bread. Numerous attempts have been made to find 
 a substitute for wheaten bread, that should wholly or partially supply its place 
 in times of scarcity. With this view, the annexed table has been prepared, 
 by which will be seen the proportion of farina and of bran the following vege- 
 table substances contain. 
 
 Kind of Gr 
 Harley . . . 
 
 ain a Bushel of, 
 am - weighs 
 
 Weight of Flour 
 in a bushel. 
 38ft lO^OZ. 
 38 9 
 43 
 44 
 60 
 23 5 
 43 5J 
 47 
 8 
 
 Weight of Brai 
 in a bushel. 
 
 51b lOJoz. 
 5 5 
 9 5J 
 8 10J 
 
 13 101 
 12 
 12 5 
 
 Buck Wheat . 
 Rye. . . . 
 
 . . . . 46* 
 . . 54 
 
 Maize. . . 
 
 
 Rice . . . 
 
 
 Oats . . . , 
 Beans . . . 
 
 1 01 t 
 . . . 38i 
 57! 
 
 Peas . . . 
 
 
 Potatoes . . 
 
 . ... 58 
 
 \\ e shall now proceed to shew how these several vegetable substances may 
 be employed as substitutes for wheaten flour. 
 
 Barley Bread. Next to wheat, barley is the most profitable of the farinaceous 
 grains, and when mixed with a small proportion of that flour, makes a much
 
 BREAD. 243 
 
 cheaper, and as good bread as that grain, as respects its nutritious properties ; 
 which is attested by the numerous robust peasantry who make it their chief 
 sustenance. Barley is, however, made into bread without the admixture of any 
 other grain, and forms the principal diet of the miners of Cornwall, and of the 
 rural population of many districts in this country. It is thus made: forty-four 
 pounds of barley meal are kneaded up into dough, with water, yeast, and salt, 
 and divided into eight loaves ; when thoroughly baked, drawn out of the oven, 
 and left to cool, they weigh about 60 pounds. Such food must, however, be 
 heavy ; and to remedy this defect, it is always best to set the sponge with 
 wheat flour altogether, as barley flour does not readily ferment with yeast; 
 and add the barley flour when the yeast is going to be made. Barley bread 
 is also made by a mixture of one peck of rice to two pecks of the barley 
 flour : also, by the addition of 14 pounds of the drained pulp of potatoes, 
 to the same weight of barley flour ; knead into dough with warm water and 
 a sufficient quantity of yeast and salt, and give the mass time to prove before 
 baking. 
 
 Buck-wheat Bread. Buck-wheat is so little used as an aliment in this coun- 
 try, that there is little opportunity of studying its effects ; but from all appear- 
 ance, it has the common quality of other grain. In Norfolk it is grown for 
 fattening poultry. In France, it is made into bread for human sustenance. 
 This grain is covered with a hard, black, triangular husk, of which it is deprived 
 by an operation, previous to grinding the farina. It is effected by high 
 drying the grain either by the sun's rays, or by the heat of a kiln, and after- 
 wards by being what is technically called run through the mill stones ; the husks 
 are then blown away by a winnowing machine, and the residual grain treated asin 
 the preparation of wheat corn. The manner of making bread from it alone is as 
 follows : boil a gallon of water, add thereto by degrees a peck of buck-wheat 
 flour, constantly stirring it, to prevent lumps forming, till a thick batter is 
 formed like that of Scotch or Yorkshire pottage. Add some salt, and boil the 
 mass for an hour and a half. Then pour into an iron kettle, hanging over the 
 fire, the due proportion for a cake, and bake it, turning it frequently to prevent 
 burning. An excellent mixed bread is made by the addition of a peck of wheat 
 flour to the before-mentioned quantity of buck-wheat. After the latter has been 
 made into batter, and cooled down to blood-heat, it may be poured into the 
 trough containing the wheat flour and yeast ; being there well kneaded, it 
 should stand two hours to prove, divided into loaves, and baked rather longer 
 in the oven than for wheat bread alone. 
 
 Rye Bread. Bread from rye alone is not, we believe, eaten in this country, 
 though in many parts of the north of Europe it is the ordinary diet of the 
 people ; a mixture of rye and wheat, however, forms excellent bread, and is 
 very sweet and nutritious. To make the bread, knead together equal parts of 
 wheat and rye flour, with a sufficient quantity of yeast, salt, and warm water ; 
 it should be covered up warm to ferment and prove, divided into loaves, and 
 baked in the usual way. A mixture of rice with rye makes good bread, in the 
 proportion of 15 pounds of rice to 60 pounds of rye. It is to be fermented 
 with yeast, &c. kneaded, formed into loaves, and baked in the usual way : the 
 product will be at the least 120 Ibs. of bread. 
 
 Maize, or Indian Corn Bread. Some authorities inform us that one half 
 maize, and one-half barley, with a leaven of wheat flour, of one-fifth of the 
 total weight, form a bread that is extensively eaten in the United States of 
 America and in many parts of Europe; but that a superior bread is made with 
 an equal quantity of wheat flour and maize. The late Mr. William Cobbett 
 (to whom this country is indebted for the successful culture of a species of 
 Indian corn,) directs the bread to be made of only one-third maize to two-thirds 
 of wheat or rye flour. " Set your sponge," he says, " with the wheat flour 
 only. As soon as you have done that, put the water (warm in cold weather 
 and cold in hot weather) to the corn flour, and mix the flour up with the water, 
 and there let it be for the present. When the wheat sponge has risen, and has 
 fallen again, take the wetted-up corn flour and work it in with the wheat sponge, 
 and with the dry wheat flour that has been round the sponge. Let the whole
 
 244 BREAD. 
 
 remain fermenting together for about half an hour, and then make up the 
 loaves, and put them in the oven." 
 
 Mice Bread. Boil a small quantity of rice in water until it becomes very 
 thick and glutinous ; with this solution knead up the rice flour in the trough, 
 to which is to be added sufficient yeast and salt. The dough being then covered 
 warm with cloths, is suffered to stand till it rises. During the fermentation, 
 this paste, which, when kneaded, was quite firm, becomes so soft and liquid as 
 to render it necessary to be put in some shallow vessel, like a stew-pan, having 
 a long handle, by which it is to be turned over in the oven, having first covered 
 the rice paste with a sheet of paper ; the heat of the oven operates so quickly 
 upon the paste, as to cause it to retain the form of the vessel whence it was 
 discharged. In this manner pure rice bread may be made ; it is of a fine 
 yellow colour, and of an agreeable taste. Its nutritive properties are sufficiently 
 attested by the well-known fact that whole nations live entirely upon it. Rice, with 
 a great variety of mixtures, produces excellent bread. The following combinations 
 have been successfully employed : First, to half a peck of rice flour add one 
 peck of wheat seconds flour ; mix with yeast, salt, &c. ; knead, ferment, and 
 bake in the usual way. Second, to a peck of rice, boiled over- night till soft, 
 and which in the morning will be found considerably swelled, add a peck of 
 potatoes well mashed into a fine pulp, and a peck of wheat flour; a sufficient 
 quantity of yeast and salt being added, and the whole kneaded, it may be left 
 two hours to prove, before making up into loaves and baking. 
 
 Oat Bread. Take a peck of oatmeal and an ounce of salt ; stir them up into 
 a stiff paste with warm water ; roll it out into thin cakes, and bake in an oven, 
 or over the embers. The Scotch peasantry live chiefly on this bread, though in 
 some cottages they cause it to undergo a fermentation by sour leaven, which 
 renders it more spongy and easy of digestion. Dr. R. Pierson has recommended 
 the following as a good and economical bread : To a peck of oatmeal add the 
 same quantity of seconds flour, and half a peck of potatoes skinned and 
 mashed ; knead up into a dough with yeast, salt, and warm milk ; make up 
 into loaves, and bake in the usual way. Equal quantities of oatmeal and rice 
 flour made up the same as the foregoing in other respects, is stated to be 
 very palatable, and must of course be very wholesome. 
 
 Bean Bread. Bean flour does not essentially differ from other farina, but 
 it has an unpleasant taste ; this is, however, scarcely perceptible if the flour be 
 steeped in water before it is used for making into bread. This flour, so treated, 
 made up into cakes or bread with yeast and salt, is tolerable ; but a good bread 
 with a mixture of wheat and bean flour is thus made : Soak the flour for three days 
 in water before it is required, changing the water every day, to carry off the 
 peculiar flavour of the bean ; then put the flour to drain over a sieve ; during 
 this operation put a peck of wheat flour into the kneading trough, and mix it 
 up with yeast and salt. After it has been properly fermented, knead the bean 
 flour with it into dough, and after it has stood a sufficient time to prove, divide 
 it into loaves, and bake. 
 
 Pea Bread may be made in the same manner as directed in the foregoing 
 article for beans ; it is sometimes mixed up with oatmeal and made into cakes ; 
 but equal quantities of pea flour (that has been steeped), potatoe flour, and 
 seconds wheat flour, afford a good bread. The sponge should be set with the 
 wheat flour, and after fermentation the other flours kneaded in, allowed time to 
 prove, then divided and baked. 
 
 Potatoe Bread. fare the potatoes, boil them well, beat them to a pulp, and 
 knead with double their weight of wheat flour, adding a sufficient quantity of 
 yeast and salt ; ferment, make up, and bake. The introduction of potatoes in 
 moderate quantity into the best wheaten bread is by no means prejudicial to 
 its quality. We believe that most persons find such bread, when well made, 
 more palatable than that which contains none. It is not quite so dry, when new 
 as wheat flour alone ; it retains its moisture much longer, and will keep for ten 
 days without any trace of sourness. The following is the process employed by 
 most bakers for introducing them : A cask is prepared by boring holes in its 
 bottom ; and the bottom made to fit into the mouth of a boiler containing water
 
 BREAD. 245 
 
 of the quantity of floui to be baked be four cwt., the quantity of potatoes that 
 can be properly used is five stone. The potatoes are thrown into the cask, a 
 cover is applied, the water is made to boil, and the steam ascending through 
 the holes of the cask boils the potatoes. The boiling is continued until the 
 potatoes crack and become mealy. They are then withdrawn, and are pounded 
 with a wooden instrument until they become quite fine. While this potatoe- 
 meal is still very hot, cold water is added in such quantity as to reduce the 
 whole to the thickness of butter milk. To this liquid, still warm, a gallon of 
 yeast is to be added. A fermentation commences ; and after it has continued 
 sufficiently long, during which the potatoe-meal rises to the top and forms a 
 tough mass, the whole is to be well mixed; and being now a homogeneous 
 liquid, it is to be strained, first through a coarse hair sieve, and afterwards 
 through a finer. To this strained matter, one half of the whole quantity of 
 flour is to be added, and well worked up with the hands so as to form sponge. 
 When the sponge has duly fermented, the other half of the flour is to be added, 
 along with some more water holding salt dissolved: this mixture is to be 
 worked up into dough, and treated in the usual manner. An extremely light 
 and beautiful bread is made by the introduction of the pure starch of the 
 potatoe, in various proportions (to the extent of one fifth part), to wheaten 
 flour. The best mode of separating this starch from the root with which we 
 are acquainted, is by the employment of a simple machine that we contrived 
 for the purpose many years ago, engravings of which are given in the next 
 page. Fig. 1 represents a vertical section of the machine. Fig. 2 is a perspective 
 view of the grinding cylinder, with a part of the perforated covering turned 
 back, to show the internal construction ; a a is a strong square frame or stand, 
 made of wood ; b, a square cistern containing water, under which the grinding 
 cylinder c is partly immersed ; this cylinder, shewn separately in Fig. 2, is 11 
 inches in diameter, and 24 inches long ; it is covered with a sheet of iron e, 
 perforated throughout with small holes, produced by means of a steel punch, 
 Laving a quadrangular pyramidical point, which raises four distinct burs or 
 teeth, particularly adapted to the purpose of rasping ; this perforated plate is 
 nailed to the peripheries of four turned discs of wood, which thus produce the 
 cylindrical figure, and each disc has a series of large holes d made through it, 
 for the free passage of the water throughout the cylinder. The axis is mounted 
 in plummer blocks, fixed on the frame, (not seen in the drawing,) and is turned 
 by a winch handle /, or any other convenient means. G is a fly wheel, to 
 equalise the motion. The potatoes are put into a hopper h, the lower extremity 
 of which is formed into a square frame which encompasses the upper half of the 
 cylinder in an exact manner, but not so as to touch it, in order that it may 
 turn round freely. The hopper is also provided with a movable curved por- 
 tion i, turning upon a joint, and serves to press the potatoes r against the cylin- 
 der, as the latter is turned round by the agency of a lever k, on which a 
 weight is suspended, a traversing weight to vary the pressure. The curved side 
 of the hopper is made of sheet iron, and has a long slit in the middle to allow 
 the lever k to traverse, and as a guide to it. In setting this machine to work, 
 the hopper is to be filled with potatoes washed perfectly clean, and the cistern 
 is to be about two thirds filled with water, or so that the cylinder dips two or 
 three inches into it. The weight being then applied to the lever k, the opera- 
 tion of grinding is commenced, and continued until the cistern is nearly filled 
 with the pulp ; but before this takes place, the water in the cistern rises so 
 much that a portion of it must be run off, or ladled out into another vessel, as 
 the water which is not then clear contains a portion of the finest starch, that 
 takes an hour or more to subside. The grinding of a bushel of potatoes into 
 pulp by a machine of this size takes a man about a quarter of an hour, from 
 which fact it will be seen, that one horse power is adequate to the reduction 
 of about 24 bushels per hour. The next process to grinding down is the sepa- 
 ration of the starch from the fibre, and other extraneous parts. For this pur- 
 pose, the cistern, which is upon rollers, is drawn forward out of its situation 
 about 6 inches, which allows sufficient room for the pulp being emptied out by 
 means of a bowl into a sieve ; or instead of the latter, into a piece of lawn
 
 246 
 
 BREAD. 
 
 stretched over a tall tub, (the best form of which is, that of the inverted 
 frustrum of a cone ;) the lawn being tied down by a cord passing round 
 beneath a hoop on the top of the tub. The operation is thus performed ; a bowl- 
 ful of the pulp is first thrown on the strainer, (which is rendered concave by 
 the pressure,) and immediately another bowlful of clear water, from a reservoir 
 at hand, is dashed down upon the former ; the dilution which it thus receives 
 causes the starch to pass rapidly through the strainer, this effect being increased 
 
 Fig 
 
 Fig.2. 
 
 by the operator continually stirring up the mixture with his left hand. A 
 small portion of starch remains after the first aSusion, but which is entirely 
 removed by a second dose; the fibrous remains are then cleared off the strainer, 
 and a fresh portion of the pulp from the cistern is thrown on the filter, and 
 treated as the former, and the operation thus continued until the cistern is 
 emptied. The cistern is again filled with water as before, the hopper reple- 
 nished with potatoes, and thus the grinding and washing away of the starch is 
 alternately performed : this variation in the process affording the man an
 
 BREAD. 247 
 
 agreeable change from the labour of turning the mill. It is advisable to use 
 two tall tubs like that already described, and to employ them alternately; 
 which will afford sufficient time for the starch to settle at the bottom of each 
 in a solid cake, while the process is being continued with the other tub. About 
 four inches above the bottom of each tub there should be a stop-cock to draw 
 off the supernatant liquid, which is of a reddish brown colour. The starch 
 should, next be removed from the bottoms of the tubs, (as it is inclined in warm 
 weather to undergo very soon the acetous fermentation, whilst wet, with the 
 coloured water deposited between its particles,) and placed in large glazed 
 pans, wherein it should be washed or stirred up again with fresh water, and 
 allowed to settle again in solid cakes ; and this operation should be repeated 
 until the water runs off colourless, which will usually be at the third or fourth 
 time of drawing off. The starch then settles quickly into a firm and beautifully 
 white cake. It has next to be dried, which is preferably done in the open air, 
 or exposed to the rays of the sun, in a situation free from dust. The mass 
 should be made into lumps with the fingers, and spread out on rectangular 
 frames of wood, over which is stretched any cheap cloth: these, from their 
 form, are very portable, and stand well upon one another, like the frames 
 used by glue boilers for drying their manufacture. When thoroughly dry, 
 it may be stowed away into casks ; and if kept unexposed to damp, may be 
 preserved good for a century. In constructing an apparatus for conducting this 
 manufacture on a large scale, many improvements on the foregoing might be 
 made to expedite the work and facilitate the labour, which are too obvious 
 to need our entering further into the subject. It is, however, due to Mr. Whately, 
 of Cork, to observe that that gentleman had invented a machine very similar to 
 the foregoing, some time previous to its publication, but unknown to the author. 
 The difference between the two machines is quite immaterial, excepting that in 
 Mr. Whately's the grinding cylinder works out of water, which renders it liable 
 to clog up, an effect which is prevented by the arrangement of the other. In 
 a communication made by Mr. Whately to the Society of Arts, (who presented 
 him with their honorary gold medal for the invention,) he states, that " it is 
 capable of the most satisfactory proof that the same quantity of land will yield 
 above one-half more of farina, or flour, where potatoes are cultivated, than if 
 the same quantity of land was applied to the production of wheat." He further 
 states, " I have proved from experiment, that 2,619 Ibs. of pure farina, or flour, 
 may be produced from an acre of land planted with potatoes, and only 1,600 Ibs. 
 of flour from an acre of wheat. It will therefore be obvious, that if we can 
 apply this great excess to the same purposes as the flour of wheat, the advan- 
 tages arising from it will be of the greatest importance to the community." It 
 is, besides, well known that many poor light soils, which are considered unfit for 
 the cultivation of wheat, will produce good potatoes abundantly. The cost of 
 producing potatoe flour from the root, Mr. Whately estimates at only half that 
 of obtaining the flour from the wheat In the introduction of a small portion 
 of potatoe flour in the manufacture of sea-biscuit, it is said the quality is mate- 
 rially improved, and that they will keep good for a much longer period of time ; 
 and it may be fairly urged, that if potatoes in the gross improve (as it is gene- 
 rally admitted they do) the quality of wheat bread, that they must be still 
 more beneficial when deprived of the refuse matter they contain. This article 
 is, nevertheless, considered legally as an adulteration of bread, as well as many 
 others, some of which we shall proceed to notice. The most common sophis- 
 tication in bread is alum. Some writers state that as much as 4 oz. are put 
 into every quartern loaf by the public bakers ; but bread containing so large a 
 quantity could not be eaten without serious constipation. From the best 
 information afforded to us, we are inclined to believe the quantity of alum 
 varies with the quality of the flour, the worst flour receiving the most alum to 
 improve the colour ; and that the quantity put to a sack of flour (though it 
 varies from 4 oz. to 4 Ibs.) is usually about 2 Ibs. ; and as this will assign to each 
 4 Ib. loaf nearly | oz., it is very probable the before-mentioned statement of 
 4 oz. to each loaf arose from an uncorrected error of the press. It has been 
 asserted that bones burned to whiteness, and ground to an impalpable powder,
 
 2 IS BREAKWATER. 
 
 are used to adulterate thirds flour ; this we trust, however, is a very rare occur 
 rence. Chalk and whiting, in small quantity, are also, it is said, sometimes 
 mixed with flour. Salt, although a necessary ingredient in bread, is sometimes 
 added to such an excess that it becomes an adulteration ; the object attained 
 by it is the causing the bread to retain a portion of the water which, without 
 it, would be evaporated in the process of baking. If bread contain an unusual 
 proportion of starch, it absorbs and retains more water from that cause. Such 
 bread, therefore, is deficient in solid matter, and is technically termed hungry 
 bread, as an equal bulk and weight does not satisfy the appetite like bread 
 which holds less water. The bakers prefer flour that has been made about 
 three months, or such a mixture of old and new flour as will make an equi- 
 valent. Weak inferior flour requires the dough to be made up as dry as 
 possible. If the usual quantity of water required for the best flour be used, 
 there is a liability to the fermentation running into the acetous stage, which of 
 course renders the bread sour. In all cases, if the dough has been made too 
 soft, it should be cooler than usual, otherwise the high heat of the oven quickly 
 forms a crust imperviable to vapour, and thus locks up the water in the bread. 
 Bread in this state is very common amongst the home-made, for want of due 
 experience in the operator. In the employment of flour made from wheat that 
 has undergone germination, it becomes necessary to have recourse to some 
 extraordinary means to render the bread light. Mr. E. Davy, who made many 
 experiments with a view to determine the best remedy for such malted flour, 
 ascertained that the carbonate of magnesia of the shops, when well mixed with 
 the new flour, in the proportion of from 20 to 40 grains to 1 Ib. of flour, materially 
 improves it for the purpose of making bread. Loaves made with it rise well in the 
 oven ; they are light and spongy, and keep well. To the worst flour as much as 
 40 grains may be added to 1 Ib. of flour. Care should be taken to mix them inti- 
 mately together. When too little yeast has been added to the dough, the fermen- 
 tation is slow and incomplete ; when it has been added in too great a quantity, 
 the fermentation becomes too rapid, and renders it liable to sourness; to remedy 
 which, Mr. Chaptel has recommended the kneading up some carbonate of potash 
 with the dough, which neutralizes the excess of acid. Dividing the dough into 
 small masses, and exposing it to the air, also has a tendency to check the fermen- 
 tation. Under the several heads of CORN, DOUGH, MILL, OVEN, &c. a variety of 
 improvements in the mechanism and processes of making bread will be found. 
 BREAKWATER. An artificial wall or rampart carried nearly across the 
 mouth of an open harbour or bay, to protect vessels moored behind it from the 
 violence of the sea. The two most celebrated structures of this kind are those 
 of Cherbourg and Plymouth. The breakwater at Cherbourg was commenced 
 about the year 1783 : it was to consist of a series of truncated cones of timber, 
 approximating at their bases, and presenting to the sea, as they rose to its 
 surface, alternate obstacles and openings. The number of cones, as originally 
 projected to cover a front of 2,000 toises, was ninety, which were after- 
 wards reduced to sixty-four; but this number was never completed. Each 
 cone was to be 150 feet in diameter at the base, and 60 feet at the top, and 
 from 60 to 70 feet in height, the depth of water at spring tides, in the line in 
 which they were to be sunk, varying from about 56 to 70 feet. The cones were 
 to be formed without bottoms, and being floated off by means of casks attached 
 to them, were to be towed to the spots whereon they were to be sunk ; they 
 were then to be filled with stones to the tops, and left to settle for a while ; 
 after which the upper part, commencing at low-water mark, was to be built with 
 masonry laid in pozzolana, and encased with granite stone. The first cone 
 was sunk June 1784, and by the year 1788 eighteen cones had been sunk, 
 occupying a line of 1,950 toises in length; but owing to the disasters which 
 
 Subsequently a plan for casing over the whole length of the old work with blocks 
 of stone was so far acted upon, that in 1803 the centre of the dyke had been 
 brought above high-water mark, and here were placed a battery and a small
 
 BREWING. 249 
 
 garrison, the whole 01 which were swept away by the sea in a heavy gale of 
 wind in 1809. Small spots only of the breakwater are now visible above the 
 surface of the sea at low-water spring tides, except near the middle, where a 
 shapeless mass (extending about 100 yards in length) rises to the height of 
 from 1 8 to 24 feet above high water. Plymouth Sound is very much exposed ; 
 and the heavy swell constantly rolling in is much increased when the wind 
 blows fresh from any point between S.E. and S.W. In the year 1806 the 
 improvement of the anchorage in Plymouth Sound, by the erection of a break- 
 water, was suggested by the late Earl St. Vincent to Earl Grey, then first lord 
 of the Admiralty; and in the same year Messrs. Itennie and Whidbey were 
 directed to report on the practicability of the plan. Their report was favourable ; 
 but from various causes the work was not decided upon until 1811. The 
 method which was recommended for constructing the work was to sink very 
 large blocks of stone in the line of the intended breakwater, allowing them to 
 find their own base, and to assume those positions which gravity would permit, 
 and that blocks of stone from 1J to 2 tons weight would be sufficiently heavy 
 to resist the action of a stormy sea. The immense beds of limestone east of 
 Catwater, which were capable of affording stones of still larger dimensions, 
 were bought by government for the sum of 10,000/., and were opened on the 
 7th of August, 1812, under the superintendence of Mr. Whidbey: five days 
 after the first stone was deposited in the Sound, and on the 31st March, 1813, 
 the breakwater was first seen above the surface of the sea at low water. Thj 
 breakwater consists of a central part of 1,000 yards in length, and of two wings, 
 each of 350 yards, forming, with the middle portion angles of 158, the angular 
 points being turned towards the ocean. The transverse section is of the form 
 of a trapezoid, whose base on an average extends to about 290 feet; its breadth 
 at top 48 feet; and its average depth about 56 feet. The rise of the slope 
 facing the sea is 1 in 7 ; that of the slope facing the harbour 1 in 5. The 
 average depth of water is 36 feet at low water spring tides, and the breakwater 
 is carried about 20 feet higher, which somewhat exceeds the greatest rise of the 
 tide. The whole length is now (1833) completed, and on the surface the blocks 
 are formed into a convenient path from end to end ; but it is decided to build 
 or encase the upper part in solid masonry, commencing at low water mark, 
 and to erect a lighthouse near the centre. The quantity of limestone required 
 for its construction, was estimated by Messrs. Rennie and Whidbey at about 
 2,000,000 tons, and the probable expense 1, 171,0001. 
 
 BREWING. The art of preparing ale or beer. The materials commonly 
 
 used for this purpose are malted barley and hops. The ingredients serve as 
 the basis of all ale and beer, and, indeed, are the only ones permitted by law ; 
 but most public brewers, in addition, make use of a variety of other articles 
 to improve the appearance of the beer, or to suit the taste of their customers. 
 Each brewer has his own recipes for these purposes, which he endeavours to 
 keep secret ; but many of the substances so employed are known to be of a 
 very noxious nature. The brewing of beer of all kinds is conducted by the 
 same general process ; the principal variations in it depend upon the scale upon 
 which the operation is carried on ; we shall therefore first give an outline of the 
 process as adapted to private families, and afterwards a description of the 
 manner in which the operation is conducted in public breweries on a large 
 scale. The method usually followed in brewing on a small scale is as follows : 
 The malt coarsely ground, or rather crushed, is strewed evenly over the bottom 
 of a broad tub, called the mash-tub, which is furnished with a wooden spigot 
 or cock, near the bottom, over the inner end of which is fitted a strainer of 
 basket-work to keep out the grains. A quantity of water, proportioned to the 
 quantity of malt and the strength intended for the beer, is then boiled in a 
 copper, and afterwards allowed to cool down to about 1 70 Fahr. ; this is then 
 poured gradually over the malt, which is stirred all the time with a sort of rake 
 of a triangular form. When the whole of the water has been poured on the 
 malt, the tub is covered with matting or sacking to retain the heat, and the 
 malt is stirred from time to time. When the water has been two hours on the 
 malt, it will have dissolved the greatest portion of the saccharine matter of the
 
 250 BREWING. 
 
 grain ; the solution is called wort, which is drawn off into a tub beneath the 
 mash-tub, and another portion of water, less than the first, and at about 180 
 Fahr., is poured over the malt. After this has stood for about an hour, it is 
 likewise drawn off, and may either be mixed with the former worts, or kept 
 separate to form an inferior description of beer. A third water is sometimes 
 given, which should be at 190 Fahr. When the whole of the saccharine 
 matter is extracted from the malt, the remainder is called grains, and is used 
 for feeding pigs. The worts are then removed to the copper, and either boiled 
 with the hops, in the proportion of 1^ Ib. of hops to a bushel of malt, or (which 
 is a better way) an infusion of hops, previously prepared at a gentle heat, is 
 added to the worts, and the whole is boiled rapidly until the liquor parts, as it 
 is called, that is, the mucilaginous parts which were suspended in the liquor, 
 and rendered it turbid, separate from it, appearing like a quantity of white worms 
 swimming through the liquor, and if a small portion of it be taken in a glass, 
 the liquor quickly becomes clear, and a thick sediment is precipitated. The 
 liquor is then poured through a coarse strainer (to separate the hops) into 
 shallow tubs, placed, if possible, where there is a current of air, in order to cool 
 as rapidly as possible ; and when it has come down to about 60" Fahr. it is 
 collected into the fermenting tun, and the yeast (first mixed with a small 
 quantity of worts) is added to the liquor, and well incorporated with it by 
 stirring it with a new birch broom ; the tun is then covered up with cloths, and 
 the temperature of the room maintained a little above 60. In a short time 
 fermentation commences, forming a white head on the surface of the worts, 
 and a large portion of carbonic acid gas is evolved, accompanied by a strong 
 vinous odour. As soon as the head begins to fall, the beer is removed into 
 casks, with the bungs left out for the escape of the yeast, which comes over in 
 considerable quantities ; the casks being replenished at intervals to compensate 
 for the portion of beer which is carried over with the yeast; and when the 
 yeast ceases to come over, the casks are first lightly, and afterwards securely, 
 bunged up for future consumption. 
 
 We shall now proceed to describe the process as usually conducted in a 
 brewing establishment on a moderately large scale. The first operation is the 
 proper grinding, or rather crushing of the malt ; this is sometimes performed 
 between mill-stones, in the manner in which corn is ground, only the stones 
 are set rather further asunder; but of late years it has become more common 
 to crush the malt between two cylinders. The malt is then suffered to lie some 
 time in a bin or cool room, to mellow, as it is called. Grist thus exposed to the 
 air it is said requires less mashing, and the strength of the malt is more per- 
 fectly obtained. Mashing in the large way is usually performed in a circular 
 wooden or cast iron vessel, called the mash tun, and furnished with a false 
 bottom perforated with holes. Between the real and false bottom, which are 
 generally a few inches asunder, are two side openings ; to one is fixed a pipe 
 for conveying hot water into the tun, and to the other a pipe and cock for dis- 
 charging the liquor into another vessel. The mashing is performed by machinery 
 invented for that purpose. These machines are variously constructed ; the 
 following is one of the most approved description. In the centre of the tun is 
 a vertical axis, which is turned round by wheel-work at the top. Upon this 
 axis is a bevelled wheel, which turns a horizontal axis extending from the centre 
 to the circumference of the tun. This axis has four wheels upon it, over which 
 pass four endless chains, which also pass round wheels on a horizontal axis 
 near the bottom of the tun. Upon the endless chains are fixed iron rakes, 
 which, as the wheels revolve, bring up the malt from the bottom of the tun to 
 the top. These also receive a slow progressive motion round the tun by the 
 following means : the outer ends of these axes are supported in bearings in a 
 vertical frame, which rises to the top of the mash tun, and is braced to a collar 
 on the vertical shaft. On the top of this frame is a bearing, to support the 
 outer extremity of a horizontal shaft, on the inner end of which shaft is a 
 bevelled wheel, which works in another bevelled wheel on the vertical shaft. 
 The horizontal shaft, by means of another bevelled wheel fixed at its outer 
 extremity, gives motion to an endless screw, supported by a carriage attached
 
 BREWING. 251 
 
 to the vertical frame, and the endless screw acting upon a ring of teeth fixed 
 upon the curb of the mash tun, causes the mashing apparatus slowly to perform 
 the circuit of the tun. After mashing, the tun is generally covered, to prevent 
 the escape of heat, and the whole remains untouched until the insoluble parts 
 separate from the liquor, when the wort is discharged into another vessel 
 usually placed beneath the mash tun, and called the underback. To extract 
 entirely the saccharine matter from the malt, a second, and sometimes a third, 
 mashing is taken, and the whole extract is received into the underback, and 
 thence conveyed to the copper. For heating the water and boiling the wort, 
 large establishments use a copper crowned with a hemispherical dome, surrounded 
 by a pan which will contain a succeeding wort. The liquor is generally boiled 
 by steam in the following way : From the centre of the dome rises a perpen- 
 dicular pipe, and from the upper extremity of this pipe four inclined pipes 
 descend, the lower extremities of which terminate near the bottom of the pan, 
 and consequently in the water or wort contained therein. By this contrivance 
 the steam which rises from the copper must bubble up through the fluid in the 
 pan, and speedily heat it. The advantages of this plan are, that the instant 
 the copper is emptied, a fresh supply of liquor can be let in to cover it, 
 in order to prevent the intense heat of the fire from injuring the bottom of 
 the copper, while the successive fluids are heated by one fire. The copper is 
 provided with two man-holes, fitted with lids which screw tight down. One of 
 these is for the purpose of admitting a man to clean the copper, and by the 
 other the hops are introduced ; the general proportion is 1 Ib. of hops to a 
 bushel of malt. After the first boiling with hops the liquor is let off, and the 
 wort is conveyed into the jack or hop-back, furnished generally with a cast iron 
 floor full of holes, so as to drain the wort from the hops. Then those left in the 
 hop-back are filled by men into tubs which are drawn up by a tackle worked by 
 the engine, and again boiled in the copper with the second and third worts. 
 From the hop-back the worts are next conveyed to the coolers. These usually 
 consist of several floors or stages, erected in the most airy and exposed situation 
 which the premises afford. They are surrounded by shallow ledges, and the 
 worts are pumped on to these to the depth of a few inches, and by the aid of a 
 current of air operating upon a very extended surface, they are in the course of 
 seven or eight hours cooled down to about 60, which is the average temperature 
 for setting to work. There are several inconveniences attending this method of 
 cooling : a considerable loss arises from evaporation ; the process is tardy and 
 uncertain, depending greatly upon the temperature of the atmosphere ; and the 
 erection of such extensive and lofty buildings as are necessary adds considerably 
 to the expense of the plant. To obviate these evils, many persons have pro- 
 posed to cool the worts by causing them to flow through thin metal pipes sur- 
 rounded by cold water, and many arrangements for the purpose have been 
 patented. The following one is the invention of Mr. Bundy. A is a tub filled 
 with cold water, in which is fixed a series of metal pipes, capable of cooling a 
 certain quantity of wort per hour, according to the size of the apparatus. The 
 wort may be let to run either direct from the boiler into the hop-back, or (as 
 convenience may permit) be ladled into B after straining from the hops. The 
 wort then passes from B through the main conducting pipe C into the series of 
 pipes, and is delivered out through the cock D into the gyle tun, adjusting the 
 quantity by opening the cock more or less, by which means the heat of the 
 wort may also be regulated, so that it may run out of the proper temperature 
 to be immediately fermented. The other vessel H is a longitudinal section of 
 a precisely similar vessel and apparatus as A, and consequently exhibits a section 
 of all the series of pipes, their spiral winding and situation. Now if, instead 
 of drawing the wort off at D, as before mentioned, that cock were kept shut, 
 
 the wort would flow out of the first series of pipes contained in the vessel A, 
 into the pipe Y, and there ascending to its level, it would descend and be dis- 
 1 il ~- second series of pipes at E, contained in vessel H, which 
 ly filled with cold water, condenses the vapours, whilst it 
 uid wort in its extended circuitous passage through the 
 pipes, till it is discharged at the cock G, where it arrive*
 
 2.V2 
 
 BREWING. 
 
 properly refrigerated, in more than double the quantity in a given time thar. 
 would be delivered at D if the vessel A alone were used. A continual supply 
 of cold water is indispensable, which may be pumped into the tub H by passing 
 
 along the shoot I, and descending by means of the trunk K to the bottom, 
 which being left open, drives the water that has been made warm by the wort 
 in the pipes, to the upper part of the vessel, from whence it flows by the shoot 
 L into the trunk of the vessel A, which is similar to that in H. By these 
 means the water which is driven off at the 
 top of the tub A is much hotter, and, con- 
 sequently, has deprived the wort passing 
 through the pipes of much more heat than 
 in the case of the single tub A being used. 
 When the tub A is sufficient by itself for 
 the purpose required, the cold water is then 
 of course to be pumped into the shoot L. 
 An apparatus for the same purpose, in- 
 vented by Mr. Wheeler, of High Wycombe, 
 Bucks, is represented in the accompanying 
 cut A series of copper plates tinned are 
 first soldered together lengthwise, and 
 another similar series are connected with 
 the former, by soldering t.heir longitudinal 
 edges together in such manner as to leave 
 between them (except at the edges) a space 
 of about a quarter of an inch ; they are 
 afterwards convoluted into the form shown 
 in the engraving, and placed in a tub or 
 cylindrical vessel ; within the narrow and 
 continuous chamber thus formed, the wort 
 is made to flow from a copper or reservoir, 
 while the water or other cooling fluid runs 
 in a contrary direction, by which arrange- 
 ment the two fluids will nearly exchange 
 their temperatures, the water becoming 
 heated and the wort cooled, a represents
 
 BRICKS 
 
 253 
 
 the service pipe and cock, which brings on the water from a cistern above ; it 
 enters at the bottom of the vessel, in the centre of the convolute, from thence 
 passing round the coils it abstracts the heat from the wort contained in the flat 
 chambers, and passes off in a heated state at the upper part of the pipe b, and 
 descends into the trough c. The wort is received at d, the lower part of which 
 pipe has an opening into the narrow convoluted chamber ; the wort circulating 
 through all these coils arrives at the centre, from whence it descends and passes 
 out by a pipe / in a cool state. At g there is a small curved pipe, to allow the 
 air in the wort chambers to escape ; at h is a pipe and cock for discharging the 
 water in the tub whenever needful. We are not aware of any brewing esta- 
 blishments having entirely dispensed with the cooling stages, but several com- 
 bine with them the plan of cooling by water, by surrounding the pipe which 
 conveys the worts to the fermenting vessels with another pipe of a few inches 
 larger diameter, and maintaining a current of cold water through the same. 
 From the coolers the worts pass to the large fermenting square, where the yeast 
 is added, and where the first fermentation is carried on. When the violence of 
 it begins to subside, the liquor is conveyed by a pipe to a series of circular or 
 square vats, ranged in double rows in a large building, called the fermenting- 
 house. In these vats (which are all of an equal height) the liquor purges itself, 
 throwing up the yeast in large quantities, which, running over the tops of the 
 vats, together with a portion of the beer, is conveyed by drains formed between 
 every double row of vats, to cisterns formed to receive it. The beer which is 
 thus carried over is replaced by a fresh quantity from a small reservoir on a 
 level with the large fermenting square, and the liquor is maintained at the same 
 level in all the fermenting vats by means of a ball cock. When the fermentation 
 in the vats has ceased, the beer is in some establishments received into cisterns 
 of wrought stone, built at some depth below the surface, in which the beer is 
 left to mellow ; in others it is pumped into immense vats, the heads of which 
 are covered with sand to the depth of a foot, to preserve them air-tight. 
 
 BRICK. A kind of factitious stone, made of a fatty earth formed into a 
 parallelogram about 4 inches broad by 8 or 9 inches in length, by a wooden 
 mould, and then baked or burnt either in a kiln or a clamp, to serve the purposes 
 of building. Bricks appear to have been used for architectural purposes at a 
 very remote period, as we learn from the Scriptures that the Israelites were 
 employed to make bricks in Egypt ; and some of the most durable of the Greek 
 and Roman monuments which have come down to us, are wholly, or in great 
 part, constructed of this material. In the East they bake their bricks in the 
 sun ; the Romans used them crude, only leaving them a long time in the air to 
 dry, about four or five years. In modern times, brickmaking is no where carried 
 to greater perfection than in Holland, where most of the floors of the houses, 
 and frequently the streets, are paved with excellent and very durable bricks. 
 Loam and marl are in England considered the best materials for bricks. The 
 former is a natural mixture of sand and clay, which may be converted at once 
 into bricks; marl is a mixture of limestone and clay in various proportions 
 The neighbourhood of London is remarkably adapted for the making of bricks, 
 the soil of the whole surrounding country being clay at a certain depth, gene- 
 rally below a bed of gravel, and the bottom of the Thames yielding the sand 
 which is used in this manufacture ; but great practical carelessness seems to 
 pervade the whole business as conducted there. The following is a description 
 of the process as it is usually conducted around the metropolis : The earth is 
 dug up in the autumn, and suffered to remain in a heap until the next spring, 
 that it may be well penetrated by the air, and particularly by the winter frosts, 
 which, by pulverising the more tenacious particles, greatly assists the operations 
 of mixing and tempering. In making up this heap for the season, the soil and 
 ashes, or sand, are laid in alternate layers or strata, each stratum containing 
 such a thickness as the stiffness of the soil may admit or require. In tempering 
 the earth, much judgment is required as to the quantity of sand to be thrown 
 into the mass, for too much renders the bricks heavy and brittle, and too little 
 leaves them liable to shrink and crack in the burning. The addition of sea- 
 coal ashes, as practised about London, not only makes it work easy but saves
 
 254 BRICKS. 
 
 fuel, as when the mixture is afterwards sufficiently heated these bricks are 
 chiefly burned by the fuel contained in the clay. When the brick-making 
 season arrives, the heap is dug up, the stony particles carefully removed, and 
 the mass properly tempered by a thorough incorporation and intermixture of 
 rials, with the additic 
 
 the materials, with the addition of as little water as possible, so as to form a 
 tough viscous paste. If, in this operation, too much water be used, the paste 
 will become almost as dry and brittle as the soil of which it is composed. In 
 order more effectually and regularly to mix the loam and ashes, it is now 
 generally performed in a sort of mill, named a pug mill. This consists of a 
 large tub or tun, fixed perpendicularly in the ground, and having an upright 
 bar, fitted with knives, placed obliquely. The upright bar is turned by a hori- 
 zontal lever, to which a horse is attached, and the soil being put in at top, is, 
 by the revolution of the knives, forced through a hole in the side of the tub 
 near the bottom, whence it is removed to the mould table, which is placed under 
 a movable shed, and is strewed with dry sand. A girl rolls out a lump some- 
 what larger than the mould will contain. The moulder receives this lump from 
 the girl, throws it into his mould previously dipped in dry sand, and with a flat 
 smooth stick about 8 inches long, kept for the purpose in a pan of water, he 
 strikes off the overplus of the soil ; he then turns the brick out of the mould 
 upon a thin board rather larger than the brick, upon which it is removed by tt 
 boy, who places it on a light barrow of a particular construction, which being 
 loaded with a certain number of bricks, they are sprinkled with sand, and 
 wheeled to the hacks. The hacks for drying are each wide enough for two 
 bricks to be placed edgeways across, with a passage between the heads for the 
 admission of the air, to facilitate the circulation of which the bricks are usually 
 laid in an angular direction. The hacks are usually carried eight bricks high ; 
 the bottom bricks at the ends are usually old ones. In showery weather the 
 hacks must be carefully covered with wheat or rye straw, unless sheds or roofs 
 be built over the hacks, as is done in some parts of the country, but in London 
 this is impracticable, from the very great extent of the grounds. In fine 
 weather the bricks will be ready for turning in a few days, in doing which they 
 are reset more open than at first, and in six or eight days more they will be 
 ready for burning. In the vicinity of London bricks are commonly burned in 
 clamps. In building the clamps, the bricks are laid after the manner of arches 
 in the kilns, with a vacancy between every two bricks for the fire to play 
 through. The flue is about the width of a brick, carried straight up on both 
 sides for about three feet ; it is then nearly filled with dry bavins or wood, on 
 which is laid a covering of sea coal and cinders (or, as they are termed, breeze) ; 
 the arch is then overspanned, and layers of breeze are strewed over the clamp, 
 as well as between the rows of bricks. When the clamp is about six feet 
 wide, another flue is made in every respect similar to the first. This is repeated 
 at every distance of six feet throughout the clamp, which, when completed, is 
 surrounded with old bricks, if there be any on the grounds, if not, with some 
 of the driest of the unbaked ones reserved for the purpose ; on the top of all, a 
 thick layer of breeze is laid. The wood is then kindled, which sets fire to the 
 coal ; and when all is consumed, which will be in about twenty or thirty days 
 if the weather be tolerable, the bricks are concluded to be sufficiently burned. 
 To prevent the fire burning too furiously, the mouths of the flues are stopped 
 with old bricks, and the outside of the whole clamp plastered with clay ; and 
 against any side particularly exposed to the rain, &c. screens are laid, made of 
 reeds worked into frames about six feet high, and of a width to admit of being 
 moved about with ease. This is the mode of manufacturing the ordinary 
 descriptions of bricks; but the superior sort, termed washed malms or marls, 
 are tempered with greater care and attention. For this purpose a circular 
 recess is built about four feet high, and from ten to twelve feet diameter, paved 
 at bottom, with a horse wheel placed in its centre, from which a beam extends 
 to the outside for the horse to turn it by. The earth is then raised to a level 
 with the top of the recess, and forms a platform for the horse to walk upon. 
 Contiguous to the recess a well is formed for supplying the recess with water, 
 which is raised by a pump worked by the horse wheel. A harrow made to fit
 
 BRICKS. 255 
 
 the interior of the recess, thick set with long iron teeth, and well loaded, is 
 chained to the beam of the wheel to which the horse is harnessed. The soil 
 prepared in the heap in the usual manner is brought in barrows, and distributed 
 regularly round the recess, and a quantity of chalk is added, and a certain 
 portion of water; and the horse being set in motion, drags the harrow, which 
 forces its way into the soil, admits the water into it, and by tearing and sepa- 
 rating the particles, not only mixes the ingredients, but also affords an opportunity 
 for stones and other heavy matters to fall to the bottom. Fresh clay, chalk, and 
 water, continue to be added until the recess is full. On one side of the recess, 
 and as near, it as possible, several hollow square pits are prepared about 18 
 inches or 2 feet deep. The soil, reduced to a kind of liquid paste, is discharged 
 from the recess by a sluice, and conveyed by wooden troughs to this pit. In 
 these pits the fluid soil diffuses itself, settling of an equal thickness, and remains 
 until wanted for use, the superfluous moisture being drained or evaporated away 
 by exposure to the atmosphere. The remainder of the process is the same as 
 for the common sort of bricks. In the country, bricks are always burned in 
 kilns, whereby much waste is prevented, less fuel is consumed, and the bricks 
 are more expeditiously burned. A kiln is usually 13 feet long by 10 feet 6 inches 
 wide, about 12 feet in height, and will burn 20,000 bricks at a time. The walls 
 are about 14 inches square, and incline inwards towards the top. The bricks 
 are set on flat arches, having holes left between them resembling lattice work. 
 The bricks being set in the kiln, and covered with pieces of broken bricks or 
 tiles, some wood is put in and kindled to dry them gradually ; this is continued 
 till the bricks are pretty dry, which is known by the smoke turning from a 
 darkish to a transparent colour. The burning then takes place, and is effected 
 by putting in brush-wood, furze, heath, faggots, &c. ; but before these are put 
 in, the mouths of the kiln are stopped with pieces of brick called shinlog, piled 
 one upon another, and closed over with wet brick earth. This shinlog is carried 
 just high enough to leave room sufficient to thrust in a faggot at a time ; the 
 lire is then made up, and continued till the arches assume a whitish appearance, 
 and the flames appear through the top of the kiln, upon which the fire is 
 slackened, and the kiln cooled by degrees. This process is continued, alternately 
 heating and slackening, till the bricks are thoroughly burned, which is usually 
 in the space of forty-eight hours. Many attempts have been made of late 
 years to supersede, by the aid of machinery, a portion of the manual labour 
 now employed in the manufacture of bricks ; and although only the most recent 
 of the machines invented for this purpose have been found to answer in practice, 
 several of them are worthy of notice. The engraving on the following page repre- 
 sents Messrs. Choice and Gibson's brickmaking machine, a a a a is an upright 
 frame, with cross beams at top and bottom ; b c are two vertical shafts, carrying two 
 horizontal spur wheels d and e, the teeth of which take into one another; these 
 are put in motion by the horse shaft f, or any other convenient power. Near 
 the bottom of the shaft 6 is fixed a large cast iron collar g, having three deep 
 mortices; into each of these the end of an iron arm h is fitted, with a bolt 
 passing through them to form a centre, as in a hinge joint To the other 
 extremity of each of the arms h is firmly fixed, by screw-bolts, a cast-iron mould 
 box i, having three divisions for three bricks, in which work three stocks or 
 false bottoms, having upright bolts passing through holes in the top. By the 
 revolution of the shaft, these mould boxes, with their arms, are successively 
 carried up and over the risers k k k, which form circular curves in the plan, 
 and appear so in the perspective, but are in reality inclined planes. At /, near 
 the bottom of the shaft, is a small bevelled wheel, which actuates a pinion fixed 
 on the spindle of the drum wheel m that passes under the floor of the machine ; 
 an endless strap passing round the drum m, and another placed at the required 
 distance, continually carries the bricks forward to their destination as fast as 
 they are made, and deposited upon it. o is a crank or lever, attached by a 
 joint to the framing, as shown, at the upper end of which is fixed a roller ; by 
 the revolution of the wheel above the three circular bars or cams r r r, attached 
 to the wheel, successively act upon the roller, and depress the crank o, which 
 first raises the rod and weight q, and afterward*- as soon as the crnk is relieved
 
 -25& BRICKS. 
 
 of the pressure, allows it to drop and strike the mould boxes, by which the 
 bricks are discharged out of them, s is a box of cast iron, containing water, 
 into which the mould boxes dip ; t is a cushion, upon which they next fall in 
 succession, by which the superfluous water is taken off; and j is a box of dry 
 sand, into which the mould boxes afterwards fall, their surfaces becoming in 
 consequence slightly coated with sand previous to becoming charged with clay. 
 The horizontal wheel e worked by d actuates the shaft c bearing the knives in 
 the pug mill. At the lower end of the shaft c is fixed the large circular revolving 
 
 bottom plate u, the periphery of which being furnished with teeth or cogs, as 
 shown, take into the teeth of a circular revolving plate v, over which, as the 
 mould box passes, the lower surface of the bricks becomes smoothed. At x is 
 a small frame, working up and down in a casing, with a pulley and counter- 
 balance weight, like a sash window ; it is raised by the crank y as each mould 
 box passes, when three little boards are placed across the frame by a boy, for 
 Ihe reception of the bricks. 'When these are deposited by the means described,
 
 BRICKS. 257 
 
 the frame drops below the level of the endless strap n ; the latter then receives 
 them, and carries them off to their destination. At z is fixed a flat box, which 
 acts as a gauge to regulate the thickness of the stratum of clay revolving upon 
 the bottom plate n of the pug mill. The operation of this machine is as follows : 
 the clay being worked in the ordinary manner through the pug mill, it passes 
 out at the mouth, (not shown, being on the opposite side,) from thence under a 
 flap which partly regulates the quantity on the bottom plate, and next under 
 the gauge, which determines it precisely. A mould box having passed over the 
 highest inclined plane or riser k first falls on the stratum of clay, and chops out 
 three bricks, filling the moulds therewith by the false bottoms rising up to the 
 determined point from the pressure of the clay against them ; the moulds, with 
 the bricks in them, then slide over the polishing plate r, (which is kept wet by 
 water constantly dripping upon it from a tub) ; from thence the moulds pass on 
 to the frame x, when the weight q strikes against the protruded bolts of the 
 false bottoms, and pushes out the bricks upon the boards on the frame ; the 
 frame then descends two or three inches by their weight, and delivers the boards 
 upon the endless strap, which, being constantly in motion, carries the bricks 
 away to be deposited on the hacks. The mould box being discharged is then 
 carried upon its roller up the first riser k, drops into the water, thence rises again, 
 falls upon the cushion, next into the sand box, whence ascending again, the 
 highest inclined plane being duly prepared, it falls again upon the bottom plate 
 of the pug mill, and chops out three more bricks, during which period each 
 mould box has operated in a similar manner. 
 
 We shall now proceed to describe the brick-making machinery invented by 
 Mr. Leahy, and erected by him for the Patent Brick Company; it is represented 
 in the accompanying figure, a is the main horizontal shaft in direct commu- 
 nication with the steam engine or other first mover ; b is a hopper-formed vessel, 
 technically termed the pug mill, in which the clay and other materials are tem- 
 pered and mixed up : it is for this purpose furnished with cross iron bars, or 
 blades of steel ; part of these are firmly fixed to the hollow vertical shaft c, and 
 the remainder bolted to the sides of the pug mill, and they are so arranged, 
 that those fixed to the shaft cut in as they revolve between the others. The 
 clay is delivered into the hopper or pug mill by an endless chain of buckets (in 
 the same manner as ballast is raised in the Thames) ; it is then cut up and 
 tempered by the knives and bars in the pug mill, and gradually descending, it falls, 
 or rather is forced by the superincumbent pressure upon the circular inclined 
 plane d, which consists of a single thread or spiral turn of a very large screw, 
 occupying the whole internal space of the lower cylindrical end of the mill, 
 where it is exhibited in section. This screw or circular inclined plane is fixed to 
 the central shaft passing longitudinally the hollow shaft, and a slow reversed 
 motion is given to it, by means of an intermediate wheel acting upon pinions in 
 the upper part of the frame. The blades on the hollow shaft, revolve in the 
 pug mill at the rate of fifteen turns in a minute, grinding and dividing the 
 materials much more completely than in the ordinary mode of brick-making. In 
 this attenuated state the materials are forced upon the circular inclined plane of 
 the screw, and as this slowly revolves in a contrary direction at the rate of five 
 turns in a minute, it takes hold of the clay (by a peculiar adaptation not easily 
 described), and forces it out of the mill, in a very compact state, into a recep- 
 tacle below : of this, one side is always in immediate contact with the moulds, 
 and those two sides which are at right angles to the former side are closed by 
 iron cheeks, between which the lever or forcing flap n acts by pressure, and, 
 fitting closely, prevents the escape of the clay, so that it can only pass into the 
 moulds. These moulds are placed round the periphery of a circular frame e 
 made of flat iron rings, fixed upon bars or spokes, and turning upon a fixed 
 shaft. There are twenty-five of these moulding boxes in one circle ; but as the 
 frame e may be of any breadth, it may contain twice twenty-five or thrice 
 twenty-five on the circumference of the cylinder, provided that the engine is 
 capable of affording sufficient power or force to cut or mould so many bricks at 
 each revolution. Each moulding box is furnished with a false or movable 
 bottom to which rods are attached, for the purpose of pushing out the brick
 
 258 
 
 BRICKS. 
 
 when moulded, and drawing back the bottom to its place to receive a fresh 
 portion of the clay. The manner in which these operations are performed is 
 extremely simple and ingenious. The ends of each of the moulding-box rods 
 are bent at right angles, and an eccentric piece /is so fixed, that, as the moulds 
 revolve, and at the moment that the surface of each is covered by being in 
 contact with the clay, it gradually draws back the false bottom, and with it the 
 clay, which is also urged on by the circular inclined plane d; and to render the 
 bricks solid and compact, a powerful pressure is applied to them by means of 
 
 the flap forcer n, to which a backward and forward motion is given by the 
 thrusting of a rod attached to a revolving crank. The moulding boxes, imme- 
 diately they are thus filled, are subjected alternately to the action of a stee! 
 scraper, which levels and smooths their surface, and is made to operate by the 
 pressure of springs. The bricks, now completely formed and fast in their 
 moulds, pass downwards in their revolution, which brings the ends of the rods 
 under the operation of a cylindrical roller, with grooves made round it at equal
 
 BRICK MAKING, 2.59 
 
 distances ; into these grooves the ends of the rods successively pass, which in 
 their revolution force out the rods, and thereby push out the bricks from the 
 moulds on to boards placed nnderneath to receive them. The bricks thus made 
 are carried forward to the hacks or drying house, upon an endless web or chain 
 i i, to which a continued motion is communicated by the revolution of the two 
 polygonal drums or wheels k k placed at the requisite distance asunder. The 
 upper part of the engraving shows a side elevation of the machine, and the 
 lower part a section of it; and although these views serve to give a general 
 idea of the construction of the apparatus, it has been impracticable to show the 
 gearing by which the several motions are produced ; we will therefore attempt 
 to describe it as follows : Upon the horizontal shaft a (which makes 2 } revolutions 
 per minute,) is fixed a toothed, bevelled wheel, which drives a bevelled pinion or. 
 an upright shaft (not shown) ; nearly at the top of this a spur wheel is fixed 
 which works into a pinion fixed upon the upper end of the hollow shaft c, 
 which carries the knives or blades in the pug mill. Upon the upper end of this 
 upright shaft is also fixed a pinion, which works into an intermediate pinion 
 turning upon an axis. This intermediate pinion acts upon another pinion 
 affixed to the internal bhaft, communicating a slow and reversed motion to it, and 
 also the circular inclined plane affixed to it ; at the lower end, on the main hori- 
 zontal shaft, is fixed a spur wheel m, which gives motion to the crank and to the 
 flap forcer connected to it. o, in the separate figure, gives the form of the 
 shelves comprising the drying apparatus, Mr. Leahy proposing to dry bricks 
 either by flues or by steam, instead of ranging them in hacks exposed to the 
 variations and inclemences of the weather, by which means it is presumed that 
 the bricks will be rendered dry enough for burning, either in kilns or clamps, 
 in a much shorter time than in the common method, and the process may be 
 carried on in winter as well as in summer. If drying by flues be resorted to, 
 a drying house must be furnished with proper stages, and shelves must be pro- 
 vided. Around and across the lower part of these, flues framed either of bricks 
 or cast iron are to be placed, through which flame or heated air is to be conveyed. 
 In drying by steam, the vapour is conveyed from the boiler through cast iron 
 pipes throughout the drying house, and boards are arranged upon stages (similar 
 to those in the separate figure), so as to leave intervals between the rows of 
 bricks, and to prevent their touching one another. 
 
 Nash's Patent Brick-making Machinery. This invention, which we have 
 now to describe, is the only one we believe that has yet been brought into suc- 
 cessful operation ; owing probably to the circumstance of the patentee (who is 
 a large tile and brick manufacturer at Market Rasen, in Lincolnshire,) having 
 perseveringly applied that intimate knowledge of his art which can only be 
 acquired by long practical experience. The leading features of Mr. Nash's 
 mechanism consist in the application of separate or detached moulds of a par- 
 ticular construction to a series of mould boxes, which are consecutively brought 
 into action, in the employment of heaters, placed in contact with, or contiguous 
 to, the fresh bricks, during the process of their being moulded ; and in lieu of 
 sand, which is generally used to prevent the adhesion of the bricks to the 
 moulds, employing elastic absorbent substances, such as cloth saturated with 
 water. In the subjoined engravings, Fig, 1 represents a front elevation, and 
 Fig. 2 an end elevation of the principal parts of the machine. A vertical shaft 
 a is made to revolve in the cylinder or pug mill b by any adequate force acting 
 upon the bevelled wheel c, A number of broad steel or iron blades d d d are 
 attached to the shaft a, their surfaces being set at such an angle as will cause 
 them during their revolution to pass nearly in contact with the edges of two 
 other sets of knives e e e fixed on opposite sides of the cylinder, by which 
 means the clay and other materials with which the mill is charged are tempered 
 and amalgamated, and then forced into the hopper /, fixed to the lower extre- 
 mity of the pug mill. This hopper is divided into two equal chambers by a 
 vertical blade or knife, which separates the materials into equal portions, which 
 *re supplied to the moulds in a compact state. The moulds are lodged in 
 rectangular cavities at equal distances in the periphery of two polygonal drums 
 g h ; these cavities are marked 1 to 1 2. To one face or side of the drums ara
 
 260 
 
 BRICK MAKING. 
 
 attached two toothed wheels, gearing into each other so as to revolve in opposite 
 directions when motion is communicated to one of them. These wheels lying 
 at the back of Fig. 1 cannot be seen, but one of them is shewn at i in Fig. 2. 
 The moulds, after being filled with the plastic material, are pushed out from their 
 
 1. 
 
 recesses by means of pistons at mm, easily fitting the recesses, and sliding upon 
 parallel rods fixed to the rims of each drum. To each piston is attached, by 
 a short rod, a cross head, sliding upon the parallel rods, and having at each end
 
 BRICK MAKING. 
 
 261 
 
 email anti-friction wheels p p, which, by the motion given to the machinery, 
 come in contact with a larger wheel q placed eccentrically, which thus raise* 
 
 Fig. 2. 
 
 the pistons, and the moulds which lie upon them are then removed by hand and 
 emptied. During this latter process the emptied mould receiver will have pased
 
 262 BRICK MAKING. 
 
 ever the centre of the eccentric wheel g, and the piston will be descending when 
 the attendant places the emptied mould in its former situation, to be filled again 
 from the hopper as it passes under it. Between each of the rectangular mould 
 boxes are formed a series of wedge-shaped boxes, termed by the patentees 
 "hollow sectors," into each of which is placed a red-hot iron, the object of which 
 is to expel the superfluous moisture from the newly-formed brick, &c. in order 
 that the manufacture may be conducted in the winter as well as the summer. 
 These irons are heated in the kiln fires. The axes of the polygonal drums 
 revolve in plummer-blocks, supported upon a strong frame s ; but as the poly- 
 gonal drums revolve in close contact, the plummer-blocks are free to slide in 
 grooves in the frame, and the wheels are kept in contact by the action of strong 
 helical springs t, which press against the plummer-blocks, the other end of the 
 springs abutting against a regulating screw. In the middle of, and underneath, 
 the horizontal frame s, is fixed a knife u (supported in its place by a spiral 
 spring), which separates the whole or a portion of the superfluous materials 
 from each mould, as the latter passes over the edge of the former. As some 
 redundancy of material may still be left after the operation of the knife u, 
 the exposed surface of the moulds in motion undergoes a similar treatment 
 from two other knives v v, fixed to the foundation plate w of the machine. A 
 trough or cistern k k containing water, is placed under each of the drums, the 
 lowest sides of which come in contact with a cylinder /, covered with strong 
 coarse cloth or other suitable absorbent substance, which, as it revolves, takes up 
 the water and delivers it to the moulds, as before mentioned. These cylinders 
 are mounted on elastic bearings, and derive their motion from pinions on their 
 axes, actuated by the toothed wheels on the drums. In the centre of the foun- 
 dation plate there is a cavity, or pit, for the reception of the superfluous clay or 
 other materials, which are removed at pleasure. The pug mill has a door in it, 
 for the convenience of cleaning it out when requisite ; and the whole of the 
 upper part of the machine is supported by three columns z z z. The polygonal 
 drums are driven by a set of wheels lying at the back of Fig. 1, and therefore 
 in that figure shown by dotted circles. No. 1 is a band wheel, which drives the 
 rest; it is affixed to one of the columns, and has a pinion 2 attached to it, that 
 drives a larger wheel 3, running loose on the shaft of one of the drums. This 
 last propels another large wheel 4, fixed on the shaft of the other drum, gearing 
 into each other; they are driven round together, but in opposite directions. 
 Since our drawings of this machine were taken, we understand that the patentee 
 has made some improvements in the arrangement of his driving wheel, which 
 renders the action of the parts very steady and uniform. In case of negligence 
 on the part of the boys, or other attendants of the machine, in not removing the 
 bricks or tiles after the moulds containing them have passed the centre of the 
 eccentric wheel, they fall back into their former position, and pass round to the 
 place of delivery, as before, without any damage whatever being done to the 
 machine. Having explained the general arrangement and operation of the 
 machine, there remains to be described the construction of the detached moulds. 
 Fig. 3 represents a side view, and Fig. 4 an end view, of one of these. The ends 
 
 Fig. 3. 
 
 of the mould 18, 18, are made of wood, plated at the edges with iron, and fastened 
 on by screws, as seen in Tig. 3. The bottom 19 is also of wood, but cased in a 
 strong frame of cast iron, and at its two extremities are jointed to the ends 18, 1 8, 
 so as to open only a little way, for allowing the brick to separate freely from it
 
 BRICK MAKING. 
 
 268 
 
 pon inverting the mould. This effect is facilitated by lining the interior of the 
 mould with cloth, which, although constantly in a wet state, admits air to pass 
 through its interstices when the clay is forced into the mould, so that when the 
 brick is afterwards forced out, the moisture of the cloth, and the spring of the 
 confined air, delivers the brick uniformly clean, without the adhesion of any 
 clay. It will be observed that the two ends 18 of the mould have each a 
 cavity ; these cavities receive the fingers of the workman when he takes hold 
 of the mould, which he afterwards inverts, drawing back the ends 18 at the 
 instant, and pressing with his thumb upon the screw heads 21 21, the other ends 
 of which are attached to a plate 22 underneath the cloth lining of the bottom, 
 as shown by dots, causing the brick to be immediately disengaged. The two 
 sides of the brick not included in the detached mould are formed by the par- 
 tition between the mould boxes and the hollow sectors. The forms and dimen- 
 sions of the detached moulds are varied according to the nature of the articles 
 to be produced therefrom. For adapting the machine to make tiles, or other 
 articles of a greater length than a brick, two movable blocks, which usually lie 
 inside the hopper, to contract its lower dimensions, are taken out. In the 
 making of drain tiles, and other articles having cavities within them, jointed 
 horses or cores are employed ; the plastic matter is forced around them by the 
 action of the machine in the same manner as in forming a brick, and the sub- 
 sequent operations are also the same, except that in the removal or delivery of 
 such tiles from their moulds, suitable adaptations are made to prevent their being 
 pressed or even touched by the hand. The annexed Fig. 5 exhibits another 
 arrangement employed by Mr. Nash for making flat tiles, flooring tiles, &c. 
 of any required breadth and thickness. This cut only represents the lower 
 
 part of the machine, the upper being the same as in the previously described 
 apparatus. To the bottom of the pug mill is fixed a funnel-shaped hopper 23, 
 the materials in which, after being forced through a mouth 24, formed of the 
 required shape, are received upon boards 25, and when cut to the proper length, 
 are removed to sheds for drying. In order to equalize the surface of the clay 
 after it has come out of the hopper, a roller 26 turning in bearings oa a curved 
 arm, which is fixed to a hinge joint, gives to the material any pressure that may
 
 264 BRIDGES. 
 
 be required, by loading it accordingly. The dotted lines 27, 27 in the same 
 figure, exhibit another funnel-shaped hopper, for the purpose of making pipes 
 or tubes, by means of a centre core 28, between which and the cylindrical 
 continuation of the hopper, the material is forced by the action of the pug mill, 
 and produces a tube, which, after having made a certain length of, is cut off, the 
 tube being turned round, to render the inside smooth previously to its being 
 removed. The patentee states that this machine may be used with either one or 
 two horse power ; that when used with one horse power, the product is about 700 
 per hour, or 8000 per day ; to do which requires the services of two men and 
 eight boys, occasioning an expense not exceeding two shillings and sixpence 
 per 1000. With two horse power employed, the production is double, or 16,000 
 per day; but the quality of the bricks, which the editor has seen, is equal to 
 those which are usually finished by grinding the surfaces by hand. The saving 
 of labour in the production is about two shillings per 1000; but the quality 
 rendering them worth five shillings per 1000 more in the market, the advantage 
 of making by the machine, where good bricks are required, is equal to seven 
 shillings per 1000. 
 
 BRIDGE. A structure with one or more transverse apertures, raised for 
 the convenience of passing a river, canal, valley, &c., and formed of various 
 materials, as timber, stone, iron, &c. It is highly probable that the first bridges 
 were composed of lintels of wood stretching from bank to bank, or, if this were 
 impracticable, resting on piers or posts fixed in the bed of the river ; and in 
 China many considerable structures of this kind are still to be seen. As 
 experience showed the defects of these early attempts, improved modes of 
 construction naturally followed. In a strong current, the frequent piers or posts 
 necessary for the support of lintels, would, by contracting the water way, increase 
 it to a torrent, obstructive of navigation, and ruinous to the piers themselves. 
 In constructing bridges over rapid rivers, it would, therefore, be found essential 
 to their stability that the openings between the supporters should be as wide as 
 possible, and every facility given to the free passage of the water ; and as this 
 could only be effected by arches or trusses, there can be no doubt that these 
 inventions were perfected before bridges became common. The most ancient 
 bridges which we know of, are the work of the Romans, unless we except some 
 of the stone bridges in China, with whose antiquity we are unacquainted ; some 
 of these latter are turned on arches in the usual manner, and others built with 
 stones from 5 to 10 feet in length, so cut as each to form the segment of an arch. 
 The Roman bridges generally consisted of a horizontal road, supported on one 
 or more semicircular arches. Of the bridges of antiquity, that built by Trajan 
 across the Danube is allowed to have been the most magnificent. It is described 
 by Dion Cassius as consisting of twenty- piers of squared stone, each of them 
 rising 120 feet above the foundations, GO'feet in width, with a water way between 
 every two of 170 feet, which was consequently the span of the arch, so that the 
 whole length of the bridge was nearly 1,500 yards. It was destroyed by Adrian, 
 lest it should afford a passage to the barbarians into the empire, and some of 
 the piers are still to be seen near the town of Warkel, in Hungary. The next 
 considerable Roman work of this kind is the Pont du Garde, which serves the 
 double purpose of a bridge over the Gardon, and an aqueduct for supplying the 
 people of Nismes with water. The bridge, which consists of six arches, is 465 
 feet in length, and supports a second series of eleven arches, which are con- 
 tinued beyond the extremities of the bridge, and form a junction with the slope 
 of the mountain on each side ; it is about 780 feet long. Over these is a third 
 series of thirty-five arches, much smaller than those below, 850 feet in length, 
 supporting a canal on a level with two mountains, along which the water is 
 conveyed to Nismes by a continued aqueduct. This extraordinary edifice is 
 built with very large stones, held together by iron cramps without cement, and 
 remains in excellent preservation to the present day. The whole height is 190 
 feet above the lower river. We may also briefly notice the bridge of St. Esprit, 
 near Lyons, which is of Roman origin, and is 800 yards in length ; it is very 
 crooked, and bends in several places, forming many unequal angles in those 
 parts where the river has the strongest current. The bridge over the Tajo, at
 
 BRIDGES. 264 
 
 Valenza de Alcantara, about 25 miles from Madrid, built in the time of Trajan, 
 is raised 200 feet above the water, is 670 feet in length, and consists of only six 
 arches. Near the old town of Brionde, in the department of the Upper Loire, is 
 a stupendous bridge of one arch, the largest with which we are acquainted. The 
 span of the arch is 181 feet ; its greatest height from the level of the water to the 
 intrados 68 feet 8 inches ; and the breadth 13. It is attributed to the Romans 
 The following are amongst the most celebrated bridges of modern date : The 
 bridge of Avignon, over the Rhone, begun in 1176, and finished in 1188. It 
 consisted of eighteen arches, and was about 1000 feet in length. It was destroyed 
 by a violent inundation of the Rhone in 1699 ; many of the ruinous decayed 
 arches still remain. The Rialto, at Venice, was begun in 1588, and finished in 
 1591, after a design of Michael Angelo Bonarotti. It consists of a bold flat arch, 
 nearly 1 00 feet wide, and only 23 feet in height from the level of the water. The 
 aqueduct bridge of Alcantara, near Lisbon, begun in 1713, and finished in 1732, 
 consists of thirty-five arches, of various dimensions; the eighth is the grand 
 arch, which is 108 feet 5 inches in the span, and 227 feet in height ; the other 
 arches run from 21 feet 10 inches to 72 feet in width; the total length of the 
 piers and arches is 2464 feet. The bridge of Neuilly, which crosses the Seine, 
 built between the years 1768 and 1780, by M. Perronet. It is level on the top, 
 and consists of five equal arches, 128 feet (English), with a rise of 32 feet 
 (English). The arches, which are elliptic, are composed of 1 1 arcs, or circles, 
 of different diameters. The upper portion of the arch was formed with a circle 
 of 160 feet radius, but after removing the centres, became flattened to an arc 
 of a circle of 259 feet radius, the rise of the curve in a length of 33 feet 
 amounting to no more than 6 inches. The bridge of Orleans, over the Loire, 
 built by M. Hupean, between the years 1750 and 1760. It comprises nine oval 
 arches, described from three centres which spring at 12 inches above low water. 
 The centre arch is 106 feet span, with a rise of 30 feet; the others gradually 
 decrease in width as they approach the shores. The whole length of the bridge 
 is 1,100 feet We shall now proceed to notice some of the most remarkable 
 bridges in our own country, beginning with those of the greatest antiquity. The 
 Gothic triangular bridge of Croyland, in Lincolnshire, is supposed to be the 
 most ancient structure remaining entire in this country, and for singularity of 
 construction and boldness of design may vie with any bridge in Europe. It 
 was erected about the year 860, and is formed by three semicircles, whose bases 
 stand in the circumferences of a circle, equidistant from each other, and uniting 
 at top. The ascent on either side of the semicircular arches is by steps paved 
 with small stones, and so steep that foot passengers only can go over the bridge. 
 The first bridge over the Thames at London was of wood, and was built in the 
 reign of Ethelred II., between the years 993 and 1016 ; in 1163 it was repaired, 
 or rather rebuilt of timber ; and in 1 1 76 the late stone bridge was begun under 
 Henry II., and was finished in the reign of John, A.D. 1209. It had originally 
 twenty small locks or arches. The length was 940 feet, the height 44, and the 
 clear width between the parapets 47 feet. In 1758 the bridge underwent a 
 very extensive repair, and two of the centre arches were thrown into one. The 
 piers were from 15 to 35 feet thick, with enormous starlings projecting on each 
 side, so that when the tide was above the starlings the greatest water way was 
 only 540 feet, scarcely half the breadth of the river ; and when the water was 
 below them, the water way became reduced to 204 feet, causing a most dan- 
 gerous fall at low water. In 1823 further repairs having become necessary, and 
 the obstructions which the old bridge opposed to the navigation of the river 
 becoming the subject of much complaint, an Act of Parliament was obtained 
 for the construction of a new bridge, of which we shall presently give a full 
 account. The longest bridge in England is that built by Bernard, abbot of 
 Burton, over the Trent, at Burton, in the twelfth century. It is all of squared 
 free-stone, is strong and lofty, and is 1545 feet in length, consisting of thirty- 
 four arches. One of the most extraordinary bridges in Great Britain is that 
 over the Taaf, in Glamorganshire, called, in Welsh, Pont y ty Prydd, built by 
 William Edwards, an uneducated mason of the country. Two bridges which he 
 had constructed at the same spot had failed ; the first, after standing 1\ years
 
 266 BRIDGES. 
 
 had been carried away by a sudden and extraordinary rise of the Taaf, swelled 
 by heavy rains and considerable tributary streams ; the second failed in con- 
 sequence of the ponderous work over the haunches forcing out the key stones 
 before the parapet was finished. Undismayed by these misfortunes, Edwards 
 resumed the attempt, and by means of cylindrical holes through the haunches, 
 so reduced their weight, that there was no longer any danger from them ; and 
 the third bridge, which he completed in 1751, has stood ever since. The present 
 bridge consists of a single arch of 140 feet span, and 35 feet high, being a seg- 
 ment of a circle of 1 75 feet diameter. In each haunch there are three cylindrical 
 openings running through from side to side. The diameter of the lowest is 9 
 feet, of the next 6 feet, and of the uppermost 3 feet. The width of the bridge 
 is about 1 1 feet. To strengthen it horizontally, it is made widest at the abut- 
 ments, from which it contracts towards the centre by seven offsets, so that the 
 roadway is 1 foot 9 inches wider at the extremities than in the middle. The 
 bridge over the Thames at Westminster, was constructed by Mr. Labalye. It is 
 1,220 feet long, and 44 feet wide, and consists of thirteen large, and two small 
 arches. The span of the centre arch is 76 feet, that of the next is 4 feet less ; 
 and in the others it goes on progressively decreasing 4 feet in each, except the 
 two small arches, which are 25 feet each. The arches are semicircular, and 
 spring from about 2 feet above low water mark, leaving a free water way of 
 870 feet. It was opened to the public in 1750, and cost 218,800^. Blackfriars 
 bridge was planned and built by Mr. R. Mylne, between 1760 and 1771. It is 
 999 feet long, and 43 feet 6 inches wide, and has 9 elliptical arches. The centre 
 arch is 100 feet, and the four arches on either side decrease gradually towards 
 the shore, being 98, 93, 83, and 70 feet respectively, leaving a clear water way 
 of 788 feet. The cost of erection amounted to 152,840/. Numerous neat and 
 elegant stone bridges have since been erected in various parts of Great Britain 
 and Ireland. Of these we shall briefly mention the Tees bridge, at Winston, 
 in Yorkshire, consisting of a single arch of 108 feet span, designed by Sir T. 
 Robinson ; one at Kiln, of five elliptical arches, of 72 feet span each ; and the 
 aqueduct bridge on the river Lune, consisting of five arches of 70 feet span, 
 both by Mr. Rennie; Essex bridge, Sarah's bridge, and Carlisle bridge, each 
 over the Liffey ; that at Aberdeen, designed by Mr. Telford ; and another, 
 over the Dee, by the same gentleman. But the most magnificent structure 
 of the kind in this country, and, possibly, in Europe, is that across the 
 Thames, nearly midway between Blackfriars and Westminster bridges, named 
 Waterloo bridge. The project for a bridge at this part of the river originated 
 with Mr. G. Dodd, about the year 1805, but from the opposition made by 
 various parties whose interests were affected by the scheme, it was not until 
 June 1809 that an Act of Parliament was obtained, incorporating a company 
 for carrying the idea into effect ; and Mr. Rennie having been appointed engi- 
 neer to the company in June, 1810, he furnished two designs, one of seven, 
 and the other of nine arches, the latter of which was finally approved by the 
 committee, and ordered to be put in execution. This noble bridge has a 
 level roadway, and contains nine elliptical arches, each having a span of 1 20 
 feet, and a rise of 35 feet, leaving a clear height of 30 feet above high water 
 spring tides, and forming a water way of 1080 feet. The length of the bridge 
 between the abutments is 1380 feet, and its width between the parapets 42 
 feet 4 inches. The roads or approaches to each end of the pier are 70 feet 
 wide throughout, except just at the entrance from the Strand, and are carried 
 over a series of semicircular brick arches of 16 feet span each. The approach 
 on the Surrey side is formed by thirty-nine of these arches, besides an ellip- 
 tical arch of 26 feet span, over the Narrow-Wall road, and a small embank- 
 ment about 165 yards long, having an easy and gradual ascent of not more 
 than 1 foot in 34. 
 
 The length of the brick arches in the Surrey approach is 766 feet. 
 
 Ditto Strand approach . 310 
 
 Length of bridge between the abutments 1380 
 
 Total length of bridge and bnVk arches . . 2456 feet.
 
 3EIDGES 
 
 267 
 
 It should be mentioned as a proof of the excellent manner in which thia 
 noble structure has been executed, that on removing the centering, the greatest 
 settlement did not exceed 1| inch, which is unprecedently small in arche 
 
 of such great span. We shall now proceed to notice the New London 
 bridge, erected by the present Mr. John Rennie, from the design of the late 
 Mr. Rennie, his father, who died shortly before the work was commenced. 
 According to the original plan, the new bridge was to have been built on the
 
 BRIDGES. 
 
 site of the old one, but the corporation of London decided that the bridge 
 should be built 180 feet higher up the stream. The bridge was also made 6 
 feet wider, and the abutment arches carried 2 
 feet higher than in the original design. The 
 foundations of the bridge were laid in coffer 
 dams, and the first pile for the dam of the 
 south pier was laid March 15, 1824. As the 
 works proceeded, it was found expedient that 
 two of the small arches of the old bridge, on each 
 side, should be thrown into one, to compensate 
 for the additional obstruction which the works 
 occasion to the navigation of the river. This 
 was effected with such skill, that the usual 
 traffic was never once interrupted during the 
 operation, the heaviest carriages passing over 
 the bridge, and vessels passing through it, 
 with the same facility as before; whilst such 
 was the promptitude and despatch used, that 
 the whole operation only occupied six weeks. 
 The engraving on page 267, with the following 
 description, will explain the manner in which 
 the alteration was effected. The roadway was 
 first boarded in and taken up one half at a 
 time, and a space cleared away for the recep- 
 tion of a transverse iron girder A. A set of 
 transverse timber principals B B was then laid 
 on to this girder from the extreme piers of the 
 two arches, bestriding, as it were, the central 
 pier, which was to be removed ; and these, 
 instead of being placed at intervals as in roofs, 
 were all fixed and bolted close together from one 
 side of the roadway to the other, forming one 
 unbroken mass of timber. Above the girder 
 there was inserted what may not be unaptly 
 termed the brestsummer C, into which the pur- 
 lins D D were mortised at intervals for the 
 support of a substantial planking, on which 
 the pavement was laid as before. The strength 
 of the truss-work was farther augmented by a 
 number of counter-principals, as 1, 2, some of 
 the struts being fixed close together, and 
 others with an interval of one width between 
 them. The bridge itself was nearly completed 
 before the line of the approaches to it were 
 decided upon ; it was at length finally settled that 
 the approach on the London side should com- 
 mence at Cannon-street, Eastcheap, passing 
 over Thames-street by means of a dry arch, 
 and that on the Borough side the road should 
 form an inclined plane, supported on a series 
 of brick arches, commencing near St. Thomas's 
 Hospital, with a large dry arch facing Tooley- 
 street. On the 1st of August, 1831, the bridge 
 was opened to the public, the period occupied in 
 its erection from the time of driving the first 
 pile, being seven years, five months, and 
 thirteen days. The engraving in the margin is 
 an elevation of the new bridge ; it is formed of 
 five semi-elliptical arches, the least of which is larger than any other elliptical 
 fttone arch ever before erected. The centre arch is 152 feet span, with a rise
 
 BRIDGES. . 209 
 
 *f 29 feet 6 inches abuve high water mark ; the two arches next the centre are 
 140 feet in span, with a rise of 27 feet 6 inches ; and the two ahutment arches 
 are 130 feet span, with a rise of 24 feet 6 inches ; thus the clear water way at 
 all times of the tide is 692 feet, which is above 60 feet more than the old 
 bridge afforded at high water mark. The whole length of the bridge from the 
 extremities of the abutments, is 928 feet ; within the abutments, 782 feet ; and 
 the width between the parapets is 53 feet. The engraving represents the new bridge. 
 Towards the close of the eighteenth century some bridges were erected, the 
 arches of which were constructed entirely of cast iron. The honour of this 
 invention is due to this country, and the first of these structures was the bridge 
 over the Severn, at Colebrook Dale, erected by Mr. Darby, in 1779. Some 
 years after (about 1790,) the celebrated Thomas Paine had one constructed at 
 the same place, which he intended for America, and which was put together 
 in a meadow near that place ; but he not being able to pay for it, it was taken 
 down, and part of the materials were employed in the construction of the 
 Sunderland Bridge, erected by Mr. Burdon over the river Wear, in 1793. 
 Subsequently, numerous iron bridges have been erected: the principal ones 
 are Build was (Colebrook Dale Company), 1795-6 ; Tame, Herefordshire (failed), 
 1795-6; Parret, at Bridgewater, 1796; Staines (twice failed), 1800; Tees, at 
 Yarm (failed) ; Boston, in Lincolnshire ; New River at Bristol (two) ; Vaux- 
 hall Bridge, over the Thames ; but the most celebrated of these structures is 
 the magnificent one over the Thames, called the Southwark Bridge, designed 
 and erected by the late Mr. Rennie. This noble bridge consists of three 
 circular arches of cast iron, supported by piers of granite ; the centre arch is 
 of 250 feet span, and the side arches 210 feet each. The piers are 24 feet 
 thick. The bridge is 718 feet long between the abutments, and 42 wide 
 between the parapets. There is a dry arch over the road on the Southwark 
 side. The work was begun in 1814, and completed in 1824. The annexed cut 
 is a view of the centre arch. 
 
 Iron Suspension Bridges were in use in Europe at the time of Scamozzi, the 
 architect, who mentions them in his work Del Idea Archi, 1615; but the 
 knowledge requisite to determine the properties of this kind of bridge was not 
 published till the time of Bernouilli. Suspension bridges are described as 
 existing in various parts of Asia, Africa, and America, before this species ot 
 construction began to be practised in Europe. The first chain bridge erected 
 in England is supposed to be that over the Tees, forming a communication 
 between the counties of Durham and York. Since that time the number of 
 these structures has been increasing, some of which, in size and magnificence, 
 exceed any thing of the kind in the known world. Of these, the most cele- 
 brated is the one recently erected over the Straits of Menai, by Mr. Telford. 
 The bridge consists of one opening of 560 feet between the points of suspension, 
 and 100 feet in height between the high-water line and the under side of the 
 road-way, which is horizontal. In addition, there are four arches on the western 
 side, and three on the eastern side of the main opening, each of 50 feet span
 
 270 
 
 BRIDGES. 
 
 The roadways consist of two carriage ways, each 12 feet in breadth, with a foot- 
 
 S v ,h of 4 feet between them, so that the platform is about 30 feet in breadth, 
 e whole is suspended by perpendicular iron rods, from four lines of strong 
 cables of malleable iron, passing over a pyramidal support or pier, at each end 
 of the main opening, the versed sine of the curve being 37 feet, or about ^ of 
 the chord line or span. The weight of the bridge between the points of suspension, 
 including the weight of the cables, is 489 tons, and the suspending power being 
 calculated at 2,016 tons, leaves a disposable force of 1,674 tons to meet any 
 stress the bridge may be exposed to. T he-iron bar suspension bridge erected 
 
 Fig 
 
 over the Thames at Hammersmith, is inferior only in magnitude to the one just 
 described. It was designed and executed by Mr. T. Clarke, civil engineer, and 
 was opened for public use in August, 1827. The above cut Fig. 1, represents 
 a perspective view, and Fig. 2 an elevation of the bridge, and some of the
 
 BRIDGES. 
 
 271 
 
 details of its construction. This bridge consists of two suspension piers or 
 lowers, built in the river, having an opening of 400 feet between them. On 
 the opposite shores are two strong abutments, over which a nearly level road- 
 way passes through archways 
 in the suspension towers. It is 
 suspended by four lines of 
 strong chains, hanging in curves 
 from the abutments over the 
 towers, and down between them, 
 the roadway being supported 
 from them by vertical rods. The 
 principle of construction is as 
 follows : D D Fig. 3, are the 
 suspension chains, which con- 
 sist of bars of iron 5 inches deep 
 by 1 in thickness ; these are 
 10 feet in length, and con- 
 nected together, as shown in 
 the plan beneath, by plates of 
 iron having a strong bolt passing 
 through them, and turned at the 
 ends; these saddle pieces are placed ten feet asunder, and are so arranged 
 that those in the upper chain are not immediately over those in the lower 
 chain, but over the middle space between each two on the lower chain. From 
 each saddle piece in each of the chains hangs a suspending rod C C, 1J inch 
 thick, so that they are 5 feet Fig. 4. 
 
 asunder. The suspending rods are 
 furnished with a joint where they 
 are inserted into the opening 
 between the chains or plates, ena- 
 bling them to accommodate them- 
 selves to any extraordinary weight 
 on the bridge. At the height of 
 about 40 feet from the road 
 the chains pass through the 
 sonry of the archways before men- 
 tioned, and over friction rollers, 
 and are secured to the ballast plates Fig. 4, which are sunk to a considerable 
 depth behind the abutments. The roadway consists of transverse beams in two 
 thicknesses, 4 J by 12 inches, with an interval of 2| inches between them; these 
 
 are fastened at the bottom by keys to strong iron plates ; along each side of the 
 bridge extends a pair of strong beams, which are firmly bolted to the flooring 
 joists ; this connexion is shown at E E, Fig. 3. The roadway of the bridge is
 
 272 
 
 BRIDGES. 
 
 slightly raised towards the centre of the river, and the whole is boarded lon- 
 gitudinally with 3-inch planks, as shewn at Fig. 5, with a small space between 
 each to prevent any water from settling on the bridge. There are two pairs 
 of chains on each side of the bridge; the inner pair consists of six links or bars, 
 and the outer of only three, as represented in Fig. 5. The total length of the 
 bridge is as follows : 
 
 Feet. Inches. 
 
 The central opening . . 400 3 
 
 The two suspension towers, each 22 feet . . 44 
 
 The opening on the Surrey side ]45 6 
 
 The opening on the Middlesex side .... 142 1 1 
 The two abutments, each 45 feet 90 
 
 Total . . .'pHRmi 
 
 The towers are 48 feet high above the level of the 
 roadway, 22 feet wide, and 42 feet broad. The road- 
 way is 16 feet above the water, and consists of a 
 carriage-way 12 feet wide, and two foot-paths, each 
 4 feet wide. The versed sine of the curve of the sus- 
 pending chains is 29.6. Several bridges on the 
 suspension principle, composed of iron wire, have 
 also been erected, and on a small scale will no 
 doubt answer ; but if of great extent, the vibra- 
 tion becomes so great as to render them unsafe. 
 Some of these, instead of being suspended from 
 chains hanging in a curve between their* points of 
 suspension, are supported by diagonal braces, pro- 
 ceeding direct from the supporting towers to 
 different parts of the platform forming the road- 
 way. The wire bridge of Dryburgh, which was 
 constructed in this manner, had one of its largest 
 radiating chains broken off at the point of suspen- 
 sion, by some mischievous persons shaking it vio- 
 lently." Shortly after it was repaired, a high wind 
 again broke the chains, and completely destroyed 
 the bridge. From the evidence of many persons, 
 it appeared that in this gale the vertical motion of 
 the bridge was equal to its lateral motion, and was 
 sufficient to precipitate a person into the river. 
 The bridge has been since replaced by one on the 
 Catenarian principle. At Vienna there has been 
 erected a steel suspension bridge over the Danube. 
 The span is 234 feet, and the versed sins 15 feet. 
 It is the work of M. Ignace Von Mitiz, who calcu- 
 lates that the total weight of steel is less than half 
 the weight of iron which would be necessary for 
 a bridge of the same dimensions. 
 
 A model of an iron suspension bridge, upon a 
 new construction, was exhibited in the year 1829 
 It was constructed by Mr. Mottley as a design 
 for a bridge across the Thames, from Scotland 
 Yard, on the Middlesex side, to the King's Arms, 
 on the Surrey shore. The annexed design for 
 an ornamental bridge for parks or pleasure- 
 grounds, will serve to explain the nature of Mr. 
 Mottley's plan, which consists in a combination of 
 the principles of tension and compression. The 
 arch represented by the curved line is confined 
 between two parallel lines, and those lines are 
 connected together by vertical bars, to which the 
 
 . 822
 
 BRIDGES. 273 
 
 arch is inflexibly attacned, and the parallel lines or bars also inflexibly jointed, 
 and the whole combined by strong bolts at the top and bottom of every vertical 
 bar, rendering it a skeleton of a trussed beam ; thus affording an opportunity of 
 having two paths across a river, the lower one of which may be used as carriage 
 way, and the upper may serve for a footway or promenade. This second floor 
 is not an absolutely necessary part of the structure ; but if it be not adopted, it 
 will be needful to have diagonal braces placed horizontally to stiffen the upper 
 part. By this mode of construction, it will be seen that the stress or pressure 
 instead of acting upon the highest point of the structure (as in the case of 
 bridges where the main chains pass over lofty towers) exerts its force at the 
 lowest point, viz. at the springing of the supporting arch, whilst the piers have 
 only to support the weight of the bridge, the thrust being counteracted by tie 
 bars, which connect the two extremities of the arch. 
 
 The accompanying engraving represents a portion of a bridge, or of a jetty, 
 supported upon floating piers, as proposed by Messrs. Delafons and luittlewort, 
 
 for situations where the water is too deep for the erection of piers, and where 
 the expanse of water is too great to be passed over by chains, without any other 
 support than that at the abutments, a represents the river or channel to be 
 crossed ; b the bed of the same ; c the suspension bridge ; d one of the floating 
 piers, of which there may be any number, according to the distance between 
 the shores ; e the mooring chains, which are attached to the heads of piles 
 driven perpendicularly into the earth. The piers are supported upon rows of 
 properly constructed boats, whose buoyancy is sufficient to bear the weight, that 
 is, without their being submerged at low water ; and these boats are confined in 
 this situation by the mooring chains. By this arrangement, when the tide 
 rises, the piers cannot ascend and lift the bridge, which would be the case were 
 the boats not tied down to the extreme point of low water, while the bridge is 
 supported by their buoyancy in either case. The machinery by which the piles 
 may be driven at considerable depths under water, forms the subject of a patent 
 taken out by Messrs. Delafons and Littlewort. 
 
 The readiest, and probably the most ancient material for the construction of 
 bridges, is timber ; and, in most countries, wooden bridges are common ; but, in 
 their construction, Germany and America appear to take the lead of all other 
 countries. The most celebrated of these structures was that over the Rhine at 
 SchafFhausen, which was destroyed by the French in 1799. It was designed 
 and executed by Ulric Grubenman, a common carpenter, who produced a 
 model of a bridge to consist of only one arch of 364 feet span ; but the magis- 
 trates insisting that the bridge should, near its middle, be supported by a 
 pier, the remains of a former bridge at the same place, he seemingly complied, 
 but executed the work in such manner as to leave it doubtful whether the 
 bridge really received any support from the pier. John, the brother of Ulric, 
 about the same time constructed a timber bridge of the same sort at Kui- 
 chenaw, 240 feet in length ; and they afterwards conjointly constructed one near 
 Baden, of 200 feet in length, and another at Wuttenghen, 198 feet in length. 
 Several timbew bridges were erected in Germany during the years 1807, 1808
 
 274 
 
 BRILLIANT. 
 
 and 1809, by Wiebekiiig. The widest span is that over the Regnitz, at Bam- 
 berg, which is 208 feet. There have been many capital timber bridges con- 
 structed in America. The Trenton bridge, over the Delaware, built by Burr in 
 1 804, is a segment of a circle of 345 feet diameter, its chord measuring 200 
 feet, its versed sine 32 feet, and the height of the timber-framing at the vertex 
 only 2 feet 8 inches. That called the Colossus, over the Schuylkill at Phila- 
 delphia, is of the extraordinary span of 340, and is the segment of a circle of 
 1 465 feet diameter ; its versed sine being only 20 feet, and height of the wooden 
 framing of the arch at the vertex only 7 feet: it was finished in 1813. 
 
 Bridges of Boats are made of boats composed of either copper, tin, or wood, 
 fastened across the stream by means of anchors or stakes, and laid over with 
 planks. At Beaucaire, Rouen, and Seville, are very fine stationary bridges of 
 boats, which rise and fall with the tide ; that at Rouen, is nearly 300 yards 
 long, and paved with stone, so that laden carriages and horses go over it in safety. 
 Another kind of bridge of boats is that called flying bridges, the use of which 
 is mostly confined to those rivers in which the stream is always running down. 
 A flying bridge generally consists of one or more boats, covered over by a platform, 
 and connected by a long 1 cable to an anchor midway of the river, and considerably 
 higher up the stream than the landing place on either side ; upon putting the 
 helm over to one side, the side of the boat is presented obliquely to the stream, 
 which impels it across the river to the opposite shore. Sometimes, instead of 
 laying down an anchor in the stieam, two stout shears or masts are erected, 
 one on each bank, and firmly secured by guys. A stout hauser is then stretched 
 tight from the top of one mast to the top of the other. Upon the hauser is a 
 large iron ring or grommet, to which is attached one end of the boat rope, the 
 other end of which is made fast to the boat, or boats, of which the bridge is 
 composed. By the action of the tide upon the rudder the boat is sheered 
 across the stream, dragging the grommet along the hauser. The annexed cut 
 
 represents another species of flying bridge, which has been proposed for 
 crossing valleys, rivers, &c. It consists of a strong wire chain, iron rod, or 
 cord e e e, which passes over the supports a a, to which one of the ends is 
 firmly fixed as at/, and adjustable by tightening screws asat^r; c is an endless 
 cord passing over the pulleys b b on the supports and round the pulley i, which 
 is attached to a light car, in which the passengers sit. The car is supported on 
 eee by the pulleys h h ; it is attached to the endless cord by the stem k I, 
 which is furnished with two holes to admit the cords at k and I. These holes 
 pass through the stem at right angles to each other, so that when the upper 
 hole k is placed in the direction of the cord, it will pass freely along it, while 
 the lower hole is placed across the cord, and thereby holds it fast, and the car 
 is dragged along by it : but if the stem be turned (which may be done by the 
 handle at I,) the reverse operation will take place, and the vehicle will be 
 dragged along by the upper cord. The endless cord may be put in motion 
 either by persons in the car turning the pulley at i, or by persons turning the 
 wheel at the station /, which is connected by an endless chain or band to the 
 pulley b. 
 
 BRILLIANT. The purest kind of diamond ; which sec.
 
 BUILDING 275 
 
 BRIMSTONE. See SULPHUR. 
 
 BRINE. Water impregnated with saline particles, and is either native, as 
 in the sea and in salt springs, or it is artificially formed by dissolving salt in 
 water. 
 
 BRONZE. A mixed metal, consisting chiefly of copper, with a small pro- 
 portion of tin, and sometimes of other metals. It is used for casting statues, 
 cannons, bells, and other articles, in all of which the proportions of the ingre- 
 dients vary. See ALLOT. 
 
 BUILDING is the art of constructing edifices, the decorative part of which 
 has received the more imposing name of Architecture. As the main design 
 of this work is, however, to furnish the most extended accounts within its 
 limits of the mechanism and manufacturing processes of the empire, we shall 
 confine ourselves to the sketching of a mere outline of this subject, and refer 
 the reader to those works from which he may fill up the details. The origin of 
 all buildings may be deduced from the construction of the meanest huts. 
 Small trees tied together at their tops, or connected by poles, and then covered 
 with such materials as nature most readily presented, as brushwood, turf, leaves, 
 and grass, were probably the primitive habitations, in temperate climates, of 
 uncivilized man ; indeed, such rude fabrics are still used by various tribes of 
 Indians of the present day. As population increased, and agriculture improved, 
 it became necessary for the inhabitants of woods to seek situations in the open 
 country more favourable to their occupations ; hence other means for constructing 
 their dwellings became necessary; and finding the advantage of living in society, 
 gradual refinements took place : amongst these, the employment of stone as 
 a preferable material to wood for the floor and the roof. By degrees, elegance 
 succeeded to, and was combined with, convenience. The earliest regular 
 buildings of which any information is given, were erected by the Egyptians. 
 The Assyrians and Persians added splendour and richness to the architecture of 
 Egypt, but it was reserved to the Greeks to impart to this art elegance and 
 symmetry ; to them we are indebted for three out of the five orders of architec- 
 ture, namely, the Doric, Ionic, and Corinthian. The Tuscan and the Composite 
 orders, which complete the five, are rejected by some writers on architecture, 
 because they differ but little from the other three. The Tuscan resembles the 
 Doric deprived of some of its mouldings ; and the Composite differs from the 
 Corinthian by the introduction of the Ionic volute into its capital. When about 
 to build, choice of situation is the first thing to be considered. For dwelling- 
 houses, a spot should be chosen sufficiently elevated to be free from damps and 
 noxious vapours, and, at the same time, sheltered from the severity of the 
 winter : the neighbourhood of fens and stagnant waters should, if possible, 
 be avoided. It should, however, be a spot where water can be easily procured ; 
 where drains may be made with facility ; and where the principal apartments 
 may have the advantages of southern and western aspects. The nature of the 
 soil should be likewise carefully examined, by boring or sinking wells, in order 
 to determine if a firm foundation can be had. The situation being chosen, 
 attention to the various arrangements of the edifice becomes the next point of 
 consideration. Drawings should be prepared, exhibiting every part correctly in 
 plan, elevation, and section ; and rf it be a considerable building, a model 
 also. The principal difficulty in architecture appears to consist in properly 
 combining utility with ornament. Of course in buildings solely designed for 
 ornament, as columns, obelisks, triumphal arches, &c. beauty alone should be 
 regarded. On the other hand, in buildings solely intended for utility, every 
 part ought to correspond with that intention. The least deviation from use, 
 though contributing to ornament, is improper, and very disagreeable to persons 
 of correct taste. The construction of the drains to carry off the rain and waste 
 water should be the first proceeding ; next, the foundation for the walls, in 
 which the utmost care is requisite that the floor on which they are made to 
 rest should be perfectly level and solid. When the board plat is laid, the first 
 course of brick or stone should be laid without mortar, for lime disposes wood 
 to rot, that in some soils would last for ages. After this, all the courses should 
 follow with the same evenness and regularity. The thickness of foundations in
 
 276 BUILDING. 
 
 general ought to be double that of the walls which they tivfe to support. The 
 looser the ground, the thicker the foundation wall ought to be ; which may 
 be diminished as it rises, as well as the wall that is raised above it, which 
 diminishes the expense without reducing the strength. The doors and windows 
 should be proportioned to the magnitude of the building. The doors of dwelling- 
 houses are usually from 7 to 8 feet high, and from 3 to 4 feet wide. Builders 
 consider the proportion of three to seven in small, and one to two in large doors, 
 to be the most eligible. With regard to windows, their number and size should 
 be so arranged as to admit neither more nor less light than may be requisite. 
 Their width in all the storeys should be the same ; but the different heights of the 
 rooms make it desirable to vary their height also ; but in this much must 
 depend upon the reigning taste or fashion. The windows in all the stories of 
 the same aspect must be placed exactly over one another. The mathematical 
 rule for apportioning light to rooms is as follows : multiply the length of the 
 room by the breadth, and multiply the height by the product of the length and 
 breadth, and out of that product extract the square root, which is the light 
 required. For example : suppose a room to be 36 feet by 24, and 15 feet in 
 height, the square root of the product of these numbers, when multiplied as 
 described, will be 113 feet, which, divided into four parts, will give 28 feet 3 
 inches to each window. A good proportion for this area is 8 feet 6 by 3 feet 4, 
 and so for any others by the same rules of proportion. For the construction 
 and proportions of chimneys, see CHIMNEY. The simplest form of a roof that 
 will resist the influence of the weather is the inclined plane ; yet, independently 
 of its want of symmetry, it does not admit of the greatest strength from a given 
 quantity of timber. The best figure is that which consists of two inclined 
 planes, meeting at the top over the middle of the building in a ridge or hori- 
 zontal line. High pitched roofs being most suitable to the pointed architecture, 
 were introduced at the same time," and form one of the most striking features of 
 the Gothic style. This equilateral triangular roof prevailed in private as well 
 as public buildings till the introduction of the Roman style by the celebrated 
 Inigo Jones, and the consequent expulsion of the Gothic architecture. The 
 chief advantages of high pitched roofs are, that they throw oft' the rain and 
 snow more quickly ; they may be covered with smaller slates, and are not so 
 liable to be injured by heavy winds ; while low roofs, as they require shorter 
 timbers, are much cheaper, and have less pressure upon the walls. When 
 executed with judgment, the roof is one of the principal ties to a building, as 
 it connects the external walls, binds the whole into one mass, and preserves 
 it from the injuries and decay which would soon be occasioned by rain and 
 frost. Trusses are strong frames of carpentry, so contrived as to act like a solid 
 body, and support certain weights at given immovable points, the truss being 
 suspended from two such immovable points; they are generally made of a 
 triangular form, and placed at equal distances on the wall plates, in vertical 
 parallel lines, at right angles to the walls, borne excellent examples of trussing, 
 especially on the suspension principle, are given under the article BEAM. See 
 also ROOF. Various methods are adopted for the construction of floors accord- 
 ing to the different bearing of the timbers. In small rooms the floors consist 
 in general of single joists, but in large rooms two rows of joists are employed, 
 one supporting the other above, and fixed at one end into a beam called the 
 girder, which is usually placed transversely in the middle of the space ; if the 
 size of the room requires three compartments of joisting, two girders will be 
 needful. _ The upper row of joists is called bridging joists, and the lower, 
 binding joists. Stairs are used as the means of communication to the different 
 storeys of a house, and the space in which they are enclosed is called the stair- 
 case. The utmost attention on the part of the builder is necessary in fixing 
 the staircase, and in determining all its just proportions. The steps, whether of 
 marble, free-stone, or wood, &c., may be supported at both ends, or at one only ; 
 when the latter, it is usually the broadest, though in small wooden stairs the 
 steps are sometimes made to project from a newel, to which the narrow ends 
 are fixed. The height of large steps must never be less than 6, or more than 
 7| inches. The breadth should not be less than 10, and never exceed 18
 
 BUILDING. . 277 
 
 inches. The length of them cannot conveniently be less than 3 feet, or more 
 than 12 feet. Geometrical stairs have their outer ends fixed in the wall, and 
 the under edge of every step supported by the edge of the one below it. The upper 
 part of the joint may be level from the face of the riser to about 1 inch within the 
 joint ; the plane of the tread of each step is thus continued about an inch 
 within the surface of each riser ; the lower part of the joint has a narrow sur- 
 face perpendicular to the rake of the stair at the end next the newel. Geometrical 
 
 will become relatively immovable ; such is the case in a geometrical stair ; one 
 end of the step is always tailed into the wall, and one edge rests either on the 
 ground, or on the edge of the inferior step or platform. The methods of 
 forming staircases are so various that it would be impossible to give even an 
 intelligible definition of them that would be compatible with our limits ; we 
 shall, therefore, at once refer the reader for information on this and all the 
 other departments of this subject to The New Practical Builder, which unques- 
 tionably is the most complete modern work upon this important art, whether as 
 respects the plainest or the most magnificent structures. 
 
 Building en Pise. An extremely simple, durable, and economical method of 
 building walls, in very general use in the neighbourhood of Lyons, and which 
 has been introduced into this country. It consists simply in ramming earth 
 firmly between moulds formed of boards set upon the ground-plan of the 
 walls ; and although it may seem that buildings erected upon this plan must 
 resemble the mud cabins which disfigure many parts of this country, they 
 nevertheless differ widely both in appearance and durability, since they may be 
 made as neat as brick buildings, and equally durable, nouses of 150 years 
 standing, built in this manner, being by no means rare in France. The follow- 
 ing instructions for this mode of building are taken from a paper in the Trans- 
 actions of the Society of Arts, Vol. XXVII. by Mr. Salmon, who has practised 
 it to some extent on the estate of the Duke of Bedford, at Woburn. The only 
 tools necessary for building en pise, besides the ordinary ones used in building, 
 are the moulds and rammers. The mould consists of two side pieces, each 
 composed of two planks 12 feet long, 10 inches wide, 1 inch thick, strengthened 
 by several pieces of board nailed across them on the outside, at equal distances 
 apart. Holes are made through these pieces of board at top and bottom, to 
 receive iron bolts, which hold the two boards parallel to each other, 14 or 16 
 inches asunder, which is the thickness of the walls intended to be formed 
 between them. The bolts have a large head at one end, and a key passes 
 through the other to keep the planks together. Two boards, equal in length to 
 the thickness of the wall, are placed between the planks at the ends to form 
 the ends of the mould. The rammer consists of a short staff with an iron 
 head, which should not be more than half an inch wide on the edge, in order 
 that it may more forcibly compress the earth in every part, which a flat rammer 
 could not do so well. In forming the angles of a building, four mould boards 
 are requisite : each of the boards for the internal angle have two eye-bolts 
 through, and the boards being set together at the proper angle, a bolt is passed 
 through the four eye-bolt, forming a kind of hinge ; the boards are retained in 
 their position by an iron stay, hooked into a staple in each of the boards. The 
 boards for the outer angle are connected by two short pieces of iron projecting 
 from one of the boards which pass through corresponding holes in the sides of 
 the other board near the end, and are keyed up on the outer side of the mould. 
 The process is conducted as follows : the foundations of the intended building 
 must be laid of brick work, stone or rubble, and be carried at least 9 inches above 
 the surface to protect the pisd from the rain ; the mould frames are then set up 
 on the foundation walls and bolted together, the thickness of the foundation 
 regulating the distance at bottom, which distance is maintained at the upper 
 part of the mould by pieces of wood cut to the proper length, which are laid 
 upon the upper connecting bolts ; head boards are also placed at each end to 
 retain the earth. Loose earth is then thrown into the mould to the depth of
 
 278 . BUILDING. 
 
 about 3 indies, which is afterwards drawn back, and cleared from the face of 
 the mould, and the space filled up with a facing composition, forming, on an 
 average, about an inch in thickness ; the whole is then firmly rammed (on 
 which, and properly preparing the facing stuff, the perfection of the work will 
 greatly depend,) until it is quite hard, when it will be compressed to about 1 
 inch in thickness. The common facing stuff is composed of lime, one part, 
 and earth, the same as that used for walling, three parts. These are mixed 
 together, and slaked the same as mortar, and the more it is wetted and slaked 
 the better, provided time can be allowed for it to dry again and pulverize, so as 
 to be fit for ramming. The better sort of facing stuff may have a small quan- 
 tity more of lime in it. When by the repeated addition of layers of earth, 
 well rammed down, as before described, the mould is filled, the keys are to 
 be taken out of the bolts, and the bolts drawn out ; the planks are then removed, 
 and put together again another length along the wall ; but the bolts at one end 
 being put through the holes left in the wall, only one of the end boards is now 
 required ; the earth is then thrown in and rammed as before, and the process 
 is continued until one course of all the walls is completed. When the lower 
 course is finished, the mould is taken to pieces and put together upon that 
 course, the lower bolts of the frame being put through the holes which the 
 upper bolts made in the wall at the first operation ; but in order that the ver- 
 tical joints formed between each mould should not coincide in the several 
 courses, the end board is in the first set of the moulds for a new course, set at 
 the middle of the length of the moulds, so that the work shall form a break- 
 joint, as it is termed in brick-work, with the course below. Windows and doors 
 may be left in the walls by fixing the heads of the moulds, and carrying up 
 quoins to form the same ; in erecting which some bond timber should be laid 
 in coarse mortar, and rammed in with the earth ; lintels may also be laid at the 
 proper height. This method is the cheapest where only one window or door of 
 a size is wanted ; but if many are required, the readiest way would be to make 
 ome rough frames of boards, of equal width to the thickness of the walls, and 
 place them in the situations of the windows and doors. When done, the earth 
 is rammed up to them, laying bond timber on the sides, and lintels over them. 
 In both cases the windows and door frames are to be put in their places, and 
 fastened to the bond timber after the walls are up. The bond timber, lintels, 
 and plates, should be kept as thin as possible in order to prevent any disagree- 
 ment between the earth and timber in the shrinking or drying of the same. 
 The bond timbers may be 4 inches by 1J ; floor or wall plates 6 inches by 2 ; 
 lintels about 4 inches thick. For common cottages, when the whole of the walls 
 are up and covered in, the holes should be stopped with very coarse mortar, 
 made the same as the facing stuff, but used wetter, and after standing some 
 time to become thoroughly dry, may be ekher lime washed or finished with 
 rough cast ; but if it be required to make the finishing as perfect as possible, 
 the following is the best mode ; viz. with water and a brush thoroughly wet and 
 soak the wall for two or three yards, in superficies, at a time ; all which parts, 
 during the said wetting, should be worked about with a hand float until the face 
 be rubbed smooth and even, by which the facing composition will so wash up 
 as to become a pleasant regular colour, the face smooth and hard when dry, 
 and not liable to scale off as a coat of plastering would do. It should have 
 been mentioned before, that, as it frequently happens that the top of one course 
 becomes too dry to attach to the succeeding course, it is advisable that, as soon 
 as the frame is set for the succeeding course, a small quantity of thick grout, 
 composed of ] lime and | earth, be poured on the top of each course imme- 
 diately before the first layer of earth is put in. A very small quantity is 
 sufficient, and will add much to the strength of the work by cementing the 
 courses well together at the joints. The workman should also, with the corner 
 of his rammer, in ramming home to the upright joints, cut down a little of that 
 part of the wall up to which he works : this will make the upright joints key 
 together, and unite in a solid manner. The earth proper for this work should 
 be neither sand nor clay singly, but a mixture of both. Clay is very objec- 
 tionable, as is also chalk, or calcareous earth of any sort. Sand is also not
 
 BUOYS. 279 
 
 proper, unless accompanied by some binding property ; tlie bolder and coarser 
 the sort of earth the better. When used, it should retain no more moisture 
 than just to make it adhere under the pressure of the thumb and finger. Where 
 the earth is not by itself proper, it may generally be rendered so by admixture 
 with either clay or with coarse sand, as the case may require. With respect to 
 the expense of this sort of walls, Mr. Salmon observes that, as labour is the 
 principal part of that expense, and as in some places labour is dearer than in 
 other, the best mode of estimating it at different places is from the quantity 
 that a man should do in a day, which he has found is 1J yard in the common 
 day's labour of ten hours. At Woburn he estimated the expense as under: 
 Labour, to making facing composition, fitting in, and 
 ramming to a 16-inch wall, when the earth is at 
 hand, (labourers being at Is. lOd. per day,) per ,. <j. 
 
 yard superficial 2 '2 
 
 Lime for facing composition, at 8d. per bushel ..003 
 Lime and labour in facing the outside of wall ... 3 
 
 Total, if finished and faced on one side only ... 2 8 
 If faced and finished on both sides, add .... 8 
 
 Total expense for walls finished on both sides ... 3 4 
 
 At the same place, the value of a yard of brickwork is more than ten shillings, 
 of walling only 14 inches thick, the bricks being forty- two shillings per 1000, 
 and lime eightpence per bushel; consequently the economy of pis6 must 
 appear ; and the same difference will be found in any other place where lime 
 and bricks bear the same price, and proper earth can be found at hand. But 
 it must not be concluded that the entire expense of a building will be in the 
 same proportion ; the economy of pis over brickwork applies only to the walls 
 of a building, the roof, floors, fittings, &c. will be nearly the same in both 
 cases, and even as regards the walls, the brickwork of the foundations must be 
 taken into the calculation. 
 
 BUOY. A floating mark to point out the position of objects beneath the 
 water, as shoals, anchors, &c. ; also any light body used to support in the water 
 another body, whose specific gravity exceeds that of water, as the buoys used 
 to support the swivel rings of mooring chains, &c. The buoys used to mark 
 the position of shoals, and to point out the right channel, are generally large 
 and strong conical casks, made water tight, and are retained in their proper 
 situation by a rope from the apex, made fast to an anchor dropped in the 
 desired spot. These buoys are variously distinguished, either by their colour, or 
 numbers painted on them ; also sometimes by small beacons rising from their upper 
 urface. All these buoys are under the superintendence of the Corporation of 
 the Trinity House. Ships' buoys are generally formed as double cones attached 
 at their bases, and are mostly composed of wood ; but these being very liable 
 to sink by leakage, buoys made of plate iron have for some time past been 
 extensively used both in the royal and mercantile navy. They are attached by 
 ropes, termed buoy-ropes, to the anchor, care being taken that the length of the 
 buoy-rope exceeds the depth of water in which the ship is to anchor. Their 
 principal use is for weighing the anchor in cases where the cable has broken 
 or been let go. 
 
 BUOY (Life). A buoy intended to support persons who have fallen into 
 the water, until a boat can be dispatched to their assistance. The forms and 
 materials of which life buoys are composed are very numerous. The annexed 
 cut represents a very simple and effectual machine of this kind invented by 
 Mr. Scheffer. Fig. 1 is the machine inflated with air. It is made of skins, 
 without any seam, (by a process of which the inventor retains the secret,) and 
 is perfectly air and water tight ; it is provided with an ingeniously contrived 
 stop-cock, which screws into the hole shown in the engraving, by means of 
 which the machine may be readily inflated by blowing with the mouth, and its 
 escape afterwards rendered impossible. The buoyancy of the machine is suffi
 
 380 BUOYS. 
 
 cient to support two persons ; so that a man equipped with one, even if totally 
 unacquainted with swimming, need not hesitate to proceed to the assistance of 
 a person struggling in the water ; and it is put on in a moment, by merely 
 stepping into it, and passing it up to the chest, where it may be worn without 
 
 Fig. 1. Fig. 2. 
 
 inconvenience, or in the least impeding the full action of the limbs. Fig. 2 
 represents another construction, by which the machine can be more easily put 
 on over the clothes. The following cut represents the air cock, a is the nozzle 
 
 of the cock, which is screwed into the elastic air vessel ; b an ivory pipe screwed 
 into the barrel, used, when required, as a mouth-piece to inflate the vessel ; when 
 that is effected, the handle d of the plug is turned, so that the hole e of the plug 
 is brought round opposite to the bolt/, when the spiral springy projects the bolt 
 into e, and locks it fast. The hole e is perforated through the plug, so that the 
 locking takes place whether the plug be turned to the right or to the left : thus 
 the cock is secured from being opened by accident, and the escape of the air is 
 prevented. To open the air passage it is necessary to draw and hold back the 
 
 rng-bolt with one hand, while the other turns the handle d into the position 
 wn. Another important purpose to which these buoys may be applied is 
 that of floating a rope from a stranded ship, by which means a communication 
 with the shore is more easily established than when it is attempted to convey a 
 rope from the shore to the ship, as the wind and sea assist in the transmission 
 of the rope in the first case, whilst in the latter, they form a serious obstacle to 
 it. Spars and casks are sometimes employed to float the rope, but are much 
 inferior to the present invention, as the lives of the men passing along the 
 floating line are greatly endangered by their being struck with them. The 
 weight of such apparatus likewise keeps the floats deep in the water, con- 
 sequently less exposed to the action of the wind, so that the tide may carry the 
 rope in a wrong direction ; but with ScheiFer's buoyant vessels lying on the 
 surface of the sea, the wind would have so powerful an effect as to render th
 
 BUOYS. 
 
 281 
 
 course of the tide immaterial ; the passengers and crew might then with security 
 pass along the rope to the shore, a the air vessel, or float for the rope b, 
 
 which is suspended by the rings to the bands c c c ; dd the water line, or depth 
 at which it lies immersed when the rope is attached. 
 
 A most admirable life buoy, for the preservation of men who may have the 
 misfortune to fall overboard at sea, by day or night, has been invented by Lieut. 
 Cook, R.N. and is so much approved, that the lords of the Admiralty have given 
 orders that every ship in the royal navy shall be fitted with one. The buoy is so 
 fitted to the stern or quarter of the ship, that in the event of an accident by 
 night, it can be detached from its position into the water in about ten seconds, 
 with a fusee at the head of the staff", giving a brilliant light, which a sea passing 
 over it cannot extinguish. Ships may on these occasions frequently nave to 
 run a mile before they can sufficiently shorten sail so as to heave to with safety ; 
 but the buoy having fallen close to the man, the light blazing above his head will 
 direct the boat to the spot without loss of time : this is a most valuable feature 
 in the invention, invaluable, as from the great difficulty of finding a man in the 
 water in a dark night, under these circumstances, men have been left to perish 
 when there has been every reason to conclude that they had reached whatever 
 might have been thrown to their assistance. The apparatus consists of two 
 hollow copper spheres, connected together by a horizontal bar, through the 
 middle of which is fixed, vertically, a strong staff) formed of a metallic tube ; 
 
 the upper extremity ot this tube supports the fusee, and the lower portion contains 
 the balance rod and weight, which drop out of the tube when the apparatus is 
 released from the ship, and preserves it upright in the water; the fusee is 
 lighted at the same instant by a gun lock. The above cut represents
 
 282 
 
 BURNING GLASS. 
 
 the life buoy suspended at the stem of a vessel. In many ships, the communi- 
 cation with the triggers for firing and for letting it go, is so contrived, that the 
 man at the helm can detach it without quitting his post. The following cut 
 
 represents the lifebuoy in use, with the fusee blazing over trie head of the man, 
 who is seen standing on the balance plate. 
 
 BURNING GLASS and BURNING MIRROR. Instruments for concentrating 
 upon a very small surface the rays of the sun, which fall upon a much more 
 extended one, by which means such an intense heat may be produced as to 
 fuse, burn, or volatilize most substances. Burning glasses are convex lenses, 
 which, acting according to the laws of refraction, transmit the rays, but 
 incline or refract them towards a common point in the axis, called the focus. 
 These were not entirely unknown to the ancients, although we have no minute 
 accounts of their construction or performances ; but in modern times very 
 powerful instruments of this description have been constructed. The most 
 celebrated is that made by Mr. Parker, of Fleet-street, at an expense of 700?., 
 and several years of labour and research. It consisted of a lens composed of 
 flint glass, which, when fixed in its frame, exposed a surface of 32 inches 
 diameter in the clear; the distance of the focus was 6 feet 8 inches, and its 
 diameter one inch. The rays from this large lens were received and transmitted 
 through a smaller one, of 13 inches diameter in the clear within the frame, its 
 focal length 29 inches, and the diameter of the focus | of an inch. Amongst 
 other remarkable effects produced by this instrument were the following: 3 
 grains of cast iron were fused in ten seconds ; 20 grains of gold in four seconds; 
 10 grains of steel in twelve seconds; and 10 grains of common limestone in 
 fifty-five seconds. Ten cut garnets, taken from a bracelet, began to run the one 
 into the other in a few seconds, and at length formed into one globular garnet. 
 The clay used by Mr. Wedgwood, to make his pyrometric test, run, in a few 
 seconds into a white enamel. We are sorry to add to the account of this
 
 BUTTONS. 283 
 
 wonderful instrument, that, after being offered for sale to several learned 
 societies, we believe it was sent to China, either on speculation, or amongst the 
 presents which accompanied Lord Macartney's embassy, and was there left. 
 Burning mirrors are concave mirrors or reflectors, formed of polished metal or 
 silvered glass, and which, acting by the laws of reflection, throw the rays back 
 into a point or focus before the glass. These instruments were not only well 
 knowpi to the ancients, but, if we may credit the accounts which have come 
 down to us, the effects of some of their contrivances were superior to any pro- 
 duced in modern times by the same me^ins. Archimedes, it is said, reduced 
 the Roman fleet under Marcellus to ashes, by burning mirrors, at a bowshot 
 distance ; and Proclus is said to have burned the fleet of Vitellius at the siege of 
 Byzantium by the same means. Of the moderns, the most remarkable burning 
 mirrors are those of M. de Villette, and of Buffon. That of M. de Villette was 
 3 feet 11 inches diameter, and its focal distance 3 feet 2 inches. It was com- 
 posed of tin, copper, and tin glass. Some of its effects, as found by Dr. Harris 
 and Dr. Desaguliers, are, that a silver sixpence melted in 7J minutes ; a 
 halfpenny melted in 16 minutes, and ran in 34 minutes, and a diamond 
 weighing 4 grains lost j of its weight. That of M. Buffon is a polyhedron, 
 6 feet broad, and as many high, consisting of 168 small mirrors, or flat pieces 
 of looking glass, each 6 inches square, by means of which, with the faint 
 rays of the sun, in the month of March, he set on fire boards of beech wood 
 at 150 feet distance. At another time he burned wood at 200 feet distance; 
 he also melted tin and lead at the distance of above 120 feet, and silver at 
 50 feet. 
 
 BUTTON. A fastening for various parts of dress. Buttons may be divided 
 into two general classes, those with shanks, or loops of metal, for the purpose 
 of attaching them to garments, and those without shanks ; and each class is 
 manufactured from a great variety of materials, and by a variety of methods. 
 Of buttons with shanks the greater number are composed of metal, although 
 glass and mother of pearl are also employed for the purpose. Metal buttons 
 are formed in two different ways, the blanks or bases of the buttons being either 
 cast in a mould, or stamped out of a sheet of metal ; the former method is 
 generally employed for making white metal buttons, and the latter for plated 
 and gilt buttons. To cast buttons, a great number of impressions of the pattern 
 of the button are taken in sand, and in the centre of each impression is 
 inserted a shank, the ends of which project a little above the surface of the 
 sand, and fused metal is poured over the mould. When cool, the buttons are 
 taken from the moulds, and after being cleansed from sand by brushing, are 
 placed in lathes, the edges are turned, the face and back smoothed, and the pro- 
 jecting part of the shank also turned. The buttons are then polished by rubbing 
 the faces upon a board spread with rotten stone of different degrees of fineness, 
 and afterwards by being held against a revolving board covered with leather, 
 upon which is spread a very fine powder of the same materials ; finally, they are 
 arranged on a sieve or grating of wire, and immersed in a boiling solution of 
 granulated tin and cream of tartar, by which means their surfaces become 
 covered with a thin layer or wash of the metal, which improves their whiteness 
 without injuring their polish. The blanks of plated buttons are cut by a fly-press 
 out of copper plate, coated on one side with silver. They are then annealed 
 in a furnace, and afterwards stamped by the descent of a weight, as in a pile- 
 driving machine, the die being fixed in the lower surface of the weight. The sol- 
 dering of the shank is performed on each button separately, by the flame of a 
 lamp and a blow-pipe : the edges of plain buttons are next filed smooth in a lathe, 
 and the buttons are afterwards boiled in a solution of cream of tartar and silver; 
 they are then placed in a lathe, and the backs brushed, and afterwards burnished 
 with blood-stone. The metal used for gilt buttons is an alloy of copper and zinc. 
 This metal is rolled out into sheets, and the blanks stamped out, which are then 
 planished if intended for plain buttons, but if for figured buttons, the impres- 
 sion is now given. The shanks are next attached, which is effected as follows : 
 each blank is furnished with a pair of small spring tweezers, which hold the 
 shank down upon it on the proper place, and a small quantity of solder and
 
 284 
 
 BUTTONS. 
 
 resin is applied to each. They are then exposed upon an iron plate to a heat 
 sufficient to melt the solder, by which the shank becomes fixed to the button ; 
 and whilst still warm they are plunged into nitric acid, to remove the oxide 
 formed on the surface by the heat employed in soldering the shanks. They are 
 then placed in a lathe, the edges rounded, and the surfaces rough burnished, 
 which renders them ready for gilding. Five grains of gold are fixed by Act 
 of Parliament as the least' quantity to be employed in gilding a gross of bujtona 
 of 1 inch in diameter. An amalgam is formed of gold and mercury, and the 
 buttons are placed in an earthen vessel along with the amalgam, together with 
 as much aquafortis as will moisten the whole, and the mixture is stirred with 
 a brush until the buttons are completely whitened. To dissipate the quicksilver 
 the buttons are shaken in an iron pan, placed over a fire, until the quicksilver 
 begins to melt, when they are thrown into a felt cap and stirred with a brush, 
 to spread the amalgam equally over their surfaces; after which, they are returned 
 to the pan, and the mercury volatilized completely by the increased heat, leaving 
 the gold evenly spread in a thin film over the surface of the buttons ; they are 
 then burnished in a lathe, which completes the operation. The better sort of 
 buttons undergo the gilding process twice or thrice, and are distinguished 
 accordingly as " double " or " treble gilt." Glass buttons are formed of glass 
 compressed, while in the fluid state, in moulds, in which the shank is inserted, 
 and when the glass becomes cold, the shank is firmly retained in its place. In 
 mother-of-pearl buttons the method of inserting the shank is extremely inge- 
 nious : a hole is drilled at the back and undercut, that is, larger at the bottom 
 than at top, and the shank being driven in by a steady stroke, its extremity 
 expands ; on striking against the bottom of the hole, it becomes firmly rivetted 
 into the button, forming a kind of dove-tail joint. 
 
 Buttons without shanks are of two kinds; the first are simply discs of horn, 
 bone, wood, or other material, with four holes drilled through the face, for the 
 purpose of sewing them to the garment. Horn buttons of this description are 
 made from cow-hoofs by pressing them into heated moulds. The hoofs having 
 been boiled in water until they are soft, are first cut into plates of the requisite 
 thickness, and after into squares of the size of the diameter of the button, and 
 afterwards reduced to an octagonal form by cutting off the corners. They are 
 then dyed black by immersing them in a cauldron of logwood and copperas 
 mixed. A quantity of moulds somewhat resembling bullet moulds, and each 
 furnished with a number of steel dies, are then heated a little above the point 
 of boiling water, and one of the octagonal pieces of horn is placed between each 
 pair of dies, and the mould being shut is compressed in a small screw press, 
 and in a few minutes, the horn becoming softened by the heat, receives the 
 impression of the die, after which the edges are clipped off by shears, and then 
 rounded in a lathe. The holes in buttons of this description are drilled by 
 means of a lathe, represented in the annexed engraving. Four spindles, of which 
 
 two only a a can be seen, are supported in bearings at J, and by the centre 
 points cc are made to revolve with great velocity by means of two bands d d 
 passing over pulleys e e fixed upon each of the spindles, each band driving two 
 spindles, and receiving motion from a wheel worked by a treadle. At the end
 
 BUTTONS. 
 
 285 
 
 of each of the spindles a, is a hook uniting them to four other spindles //by 
 similar hooks at one end, the other end of the spindles passing through four 
 small holes in the plate g, and the projecting points being formed into small 
 drills. The button is placed in a concave rest h, and pushed forward against 
 the drills by a piece of wood. The standard g can be exchanged for another 
 with holes more or less apart, and the rest A can be set at any height to suit 
 different sized buttons. As the spindle holes in the plate g are nearer together 
 than the holes in the standard b, the spindles // converge ; the hooks in the 
 spindles are therefore necessary to form a universal joint. The second descrip- 
 tion of buttons without shanks consists of thin discs of wood or bone called 
 moulds, covered with silk, cloth, or other similar materials. The bone -for the 
 moulds is made from refuse chips of bone sawn into thin flakes, and brought 
 into a circular form by two operations, illustrated by the accompanying 
 engraving. On one end of the spindle a, which revolves in bearings at b b, is 
 
 screwed a tool c, and on the other are two collars d d, between which a forked 
 lever e embraces the shaft, the fulcrum of which is at/. The spindle a is put 
 in rapid motion by a band g passing over the pulley h, and over a band wheel 
 worked by a treadle ; and the workman, holding the material i for the mould in 
 his right hand, against a piece of wood k firmly held down in the iron standard I 
 by two screws, by means of the lever held in his left hand, he advances the tool 
 c against the material i of the mould ; the central pin of the tool drills a hole 
 through the centre of the intended mould, whilst the other two points describe 
 a deep circle cutting half through the thickness of the material, and the flat 
 surface is cut smooth by the intermediate parts of the tool. The tool is then 
 drawn back a little by the lever e, and the material shifted to bring a fresh 
 portion of the surface opposite the tool, and when as many moulds as the plate 
 of the material will afford, are thus half cut through, the other side is presented to 
 the tool, and the central point of it being inserted in the hole made in the first part 
 of the operation, the other two teeth cut another deep circle exactly opposite the 
 former one through the remaining substance of the material, and the mould is 
 left sticking on the tool ; by drawing back the lever e the tool recedes, and the 
 mould, meeting a fixed iron plate, is pushed off the tool, and falls into a small box in. 
 Covered buttons having come into very general use, various improvements 
 nave been introduced in the manufacture of them, and patents for this purpose 
 have been granted to various parties, as 
 Sanders, Needham, Aingworth, Church, 
 and others. The following is Mr. Sanders' 
 method of making covered buttons : a 
 piece of the material with which the mould 
 is to be covered is cut of a circular shape, 
 somewhat larger than the intended button ; 
 upon this is placed a disc of card of the 
 exact size of the button, and next a disc of 
 naper coated with an adhesive composition, c \ 
 Which will become soft and sticky by heat ;
 
 286 CABLES. 
 
 and upon these is laid a button mould e having four holes, through which 
 threads or strings have been passed to form the flexible shank. These circular 
 discs being put together, are then laid over a cylindrical hole in a metal 
 block a; this hole being exactly the size of the intended button, and the 
 covering of the button being larger than the hole, when the discs are pushed 
 down into the hole, the material of the covering will wrinkle up on the edges 
 round the other discs. The tube b b is then introduced into the cylindrical 
 hole, and its lower edge being bevilled inwards, will, as it is pressed down, 
 gather the plates of the cloth on the edge of the button ; towards the centre 
 is a metal ring or collar c, having teeth round its edge; somewhat like a crown 
 saw is now passed down the tube b, and driven with considerable force by 
 the punch d, and the block a having been previously heated, the adhesive 
 matter will be softened, and cause the several discs to stick together, which, 
 when taken out and become cold, will be very firm and retain its shape. 
 
 C. 
 
 CABLE. A rope of large diameter, by which ships are held to their anchors 
 or moorings. The materials of which cables are formed are very various, as 
 bass, hemp, sunn, and coir, or. the husk of the cocoa nut, and latterly iron 
 chains, of a particular construction, have been extensively used, and are com- 
 monly called chain cables. Cables are composed of either three or four ropes 
 twisted together, each rope consisting of either three or four strands, each strand 
 containing an equal number of yarns, which number depends upon the diameter 
 of the cable. Cables are denominated by their circumference in inches, as a 
 22-inch cable, meaning a cable 22 inches in circumference. The length of all 
 cables is the same, viz. 120 fathoms. The larger class of ships in the navy 
 and in the East India Company's service are usually provided with the following 
 cables : viz. two spliced together, for the best bower anchor ; two for the small 
 bower anchor ; two for the sheet ; one spare cable ; and one cable for the stream 
 anchor. The chains employed for cables have a short stay bar in the middle 
 of each link, to prevent the sides collapsing when the cable is exposed to a 
 heavy strain. The form of the links and stays, and the mode of applying the 
 latter, have formed the subjects of numerous patents. The annexed figures 
 represent or>' of the links of Mr. Hawks's " Patent Chains for Cables and 
 Hawser." ' and also illustrates the method of forming them. The novelty 
 
 \ 
 
 i,n the form of these links consists in their being thicker at the bends than at the 
 sides; whereas in most other chain cables the links are either the same thickness 
 throughout, or are smallest at the bends. The iron rod a a of which the link 
 is formed, it will be seen has bulbous en- 
 largements at regular distances asunder: 
 these are produced either by cavities in the 
 rollers between which the rod is drawn, or 
 by swaging or forging. The rods being cut 
 into exact lengths, they are turned round 
 into links, and the ends welded together, 
 when th? bulbs should be situated exactly 
 .it the ends, as represented by the annexed 
 f'gure at a a, and the stay-bar b inserted. 
 Chains for. cables are commonly made in lengths of 10 fathoms, connected by 
 a bolt and shackle, for the convenience of slipping on in an emergency, as cutting 
 is of course out of the question ; and at every 30 fathoms is a swivel, that the 
 chain may not become twisted. A simple and effectual stopper for chain cables 
 is much wanted, as considerable difficulty is frequently experienced in " bringing 
 ft. ship up," as it is termed, when it blows bard. The ordinary stopper consists 
 of two concave plates of iron, between which the chain passes ; the lower plate
 
 C:>COA. 
 
 287 
 
 is firmly secured to the deck, and the upper plate turns upon a hinge. A long 
 iron bar is inserted into a socket cast upon the upper plate and to the outer 
 ead of the bar is attached a tackle, hooked to a bolt in the deck ; and a number 
 of men being stationed at the tackle, by hauling upon it they compress the 
 cable so tightly between the plates, as to prevent the cable running out, or, 
 by slacking it, allow it to run freely. This apparatus frequently gives way, 
 and occasions serious damage. The following substitute, invented by Lieut 
 Kooystra, R.N., has been approved by the Society of Arts, who have presented 
 ta inventor with the silver Vulcan medal. The figure represents an under- 
 view of the part of the deck where the stopper a a fixed; tins stopper ,s 
 formed of an iron hook or clip, turning upon a bolt at b, and has a few links , of 
 i-haiu at the other end ; d and e are portions of two beams ; / part of the chau. 
 
 L 
 
 cable, held fast by the stopper ; g a square bar, sliding through the beam d, and 
 through square holes in the metal facing plates h h; i the hook in the end of 
 the bar g, which takes the link,; of the stopper; k a double-threaded screw, on 
 the other end of the bar g ; I the screwed end of a crank handle m, fitted on 
 the screw k ; the other end turns freely in the plate o o ; p p the bolts which 
 secure this plate to the beam e. By turning the crank one way, it will be seen 
 that the cable will be tightly pressed by the stopper against the iron knee q, and 
 by turning it the other way the pressure is relaxed. The sliding bar g is shown 
 separate above. 
 
 Mr. William Shelton Burnett had a patent for a cable-stopper, of which the 
 following is a description. This apparatus consists of a metallic box a, con- 
 taining a spirally coiled spring, through the centre of which passes longitudinally 
 
 a bar ; one end of this is strongly rivetted to an iron plate, and the other ter- 
 minates in a large eye, for the reception of a hook or a rope. Now, supposing 
 the cylinder a to be made fast at b to some staple part of a ship, and the cable 
 c, which passes over the side of a ship d, to have an anchor attached to the other 
 extremity, when any strain comes upon it, the bar is drawn more or less out of 
 the cylinder, compressing the spring, thus affording an elastic resistance, which, 
 continually increasing with the force applied, will prevent those accidents of 
 tearing away the fastenings, which might, without such apparatus, be the result. 
 It is of course that this contrivance is equally applicable to any other tackle, 
 which it will always keep in a proper state of tension after the cause of the 
 adventitious strain has ceased to operate. 
 
 CACAO NUT, or COCOA. An oblong roundish nut, nearly the shape of an 
 almond, but larger ; the shell dark-coloured, brittle, and thin ; the kernel both 
 externally and internally brownish. It is the produce of a small tree, the 
 Obrama Cacao, bearing a large fruit like a cucumber, which contains thirty :r
 
 288 
 
 CAISSON. 
 
 more of these nuts Chocolate is prepared from these nuts. A patent was 
 lately obtained for a preparation of cocoa, called " Marshall's Extract of Cocoa." 
 The specification, which is dated the 10th February, 1830, describes the process 
 to consist in boiling, for an hour, a pound of powdered cocoa in a gallon of 
 water; the mixture is then to be passed through a sieve, and the oily matter to 
 be skimmed from the surface. It is next to be evaporated in a water bath, till 
 it assumes the consistence of treacle, when it is to be preserved for use in 
 bottles well corked and sealed, so as to render them impervious to the ah-. 
 
 CAISSON. A kind of chest-framed or flat-bottomed boat, sometimes used 
 in laying the piers of bridges in deep or rapid rivers. The caissons for this 
 purpose consist of a very strong platform of timber, to which are attached the 
 two sides, in such a manner as to admit of their removal when no longer 
 required. These sides, which are also very strongly framed of timber, to resist 
 the great pressure of the water, are curved towards their extremities, so as to 
 
 meet each other, and form a salient angle up and , 
 
 down the stream, and inclosing a space somewhat [~ 
 wider than the foundation of the pier of the 
 bridge. The site of the pier being levelled by 
 dredging or otherwise, the caisson is brought 
 over the spot, and moored in the proper 
 position ; two or three of the lower courses of 
 masonry are then built upon the platform of 
 the caisson, and the water is then slowly ad- 
 mitted by a sluice in the caisson, so as to cause 
 the caisson to settle into its place ; and to prevent 
 the effects of too great a pressure of water when 
 the rise and fall of the tide is considerable, the 
 water is generally admitted some time before high 
 water, and pumped out again after the ebb tide 
 has commenced, so that the workmen may resume 
 their labours before low water. When the masonry 
 is brought up as high as the level of the water, 
 the sides of the caisson are detached from the 
 bottom, and removed. Westminster and Black- 
 friars bridges were built on caissons, but the 
 preference is now generally given to coffer dams. 
 A patent was obtained by Mr. Deeble, for con- 
 structing jetties, piers, quays, &c. by means of 
 what he terms "metallic caissons," or a peculiar 
 description of cast iron boxes, variously combined 
 by dovetails ; these boxes, when fixed in their 
 places to form a pier, or quay, &c. are filled with 
 liquid lime and rubble, which soon sets hard, and 
 forms a solid mass girt with metal. For the 
 better elucidation of the plan, a few of the more 
 simple forms of caissons, and their mode of 
 uniting, as exemplified in the construction of a 
 pier, are engraved herewith. The caisson is open 
 generally both at top and bottom ; the thickness 
 of the sides proportioned to the strength and 
 gravity required. It is proposed that each caisson 
 
 7 feet in length, 5 feet in height, and from 2 
 5 feet in width, according to the nature of 
 
 the work in which it is to be used. Caissons 
 
 constituting foundations should be closed at 
 
 bottom, and in raising one tier above another, each layer would become united 
 
 to those immediately above and below it, by commencing the alternate vertical 
 
 courses with a half caisson. Fig. 1 is the plain oblong square, with dovetails at 
 
 the ends, only applicable to straight lines, either in banking exposed to the water, 
 
 or to the interior of heavy works, as cross forts, or in bracings and buttresses to be
 
 CALCULATING MACHINES. 289 
 
 kuried in the earth. This form admits but little variation in its application, 
 and none in its strength or gravity beyond what may be gained by increasing 
 the thickness of its sides. Fig. 2 is the most universal form ; it may be mul- 
 tiplied to any extent, yet is perfect in itself, requiring no change of form on 
 the side to finish a work, and the ends may be conveniently completed by 
 filling up the dovetail groove with a portable half dovetail. Fig. 3 is the 
 radiated form, which may be used in a waved line along the coast, where great 
 strength is required ; it also applies to piers and bastions. The dotted projection 
 is the half dovetail, which would be required to attach it to the cross fort ; or 
 the radiated caisson, should it be considered necessary to add another waved 
 line, would give the effect of arch and counterarch. Fig. 4 is a radiated caisson, 
 having extra dovetails for uniting the main line to the bastion. Any angle may 
 thus be gained, simply by mooring this caisson in the bastion, in the direction 
 required. Fig. 5 is the termination of a pier with a bastion : the external dotted 
 
 Fig. 5. 
 
 line shows the boundary of the sloped bank ; the cross forts are introduced at 
 suitable distances to insure great stability; and the inner dovetailed grooves 
 being left in the inner lines, will enable the engineer to add cross forts and 
 buttresses to any extent that may be required. 
 
 CALAMINE. An ore of zinc, principally used in making brass. 
 
 CALCINATION. The process by which some bodies are rendered reducible 
 to powder ; it consists in exposing the substances to a strong heat, so as to dissi- 
 pate the water of crystallization and other volatile portions. 
 
 CALCULATING MACHINES. Machines devised for facilitating arith- 
 metical computations. From a remote period of antiquity, various mechanical 
 devices were resorted to for this purpose. Amongst the Greeks and Romans, 
 an instrument called " abacus" was employed, consisting of a -number of 
 parallel threads, upon which were strung a number of beads for counters, to 
 represent units, tens, hundreds, &c. The Chinese at the present day use in 
 their computations an instrument called a swanpan, nearly resembling the 
 Greek abacus, and which may now be met with in the toy-shops of London. 
 There are large and small swanpans ; those for mercantile purposes consist of 
 many rows of small balls strung on wires, containing fifteen balls on each, with 
 space for their being moved up and down with ease. These rows of balls are 
 divided by a cross bar of wood extending from side to side, leaving five balls 
 above and ten below. Each ball of the upper row is of the value of the ten 
 balls on the lower row, and by moving down to the bar one of the upper balls, 
 the ten lower balls which had been moved up to the bar, are at liberty to repre- 
 sent any further sum until they have all again reached the bar, when a second 
 ball is brought down from the upper row, and so on until the five balls are 
 engaged, when their value is represented by one ball on the adjoining wire on 
 the left hand, and so on to any amount. These instruments are universally 
 employed throughout China for the purposes of computation ; and so expert 
 are the Chinese in the use of them, that few Europeans, with the assistance of 
 pen and ink, can keep pace with them. The celebrated Napier, the inventor of
 
 290 CALCULATING MACHINES. 
 
 logarithms, contrived an instrument by which the operation of multiplication is 
 much facilitated, the product of any single figure with the multiplicand being 
 represented at once by a very simple mechanical operation. This instrument, 
 which consisted of a number of detached rods, each bearing at the top some one 
 unit with the products of the same, multiplied by the nine units ranged in a 
 line beneath it, is commonly known by the name of Napier's rods or bones. But 
 by far the most useful contrivance of this kind is the Gunter's scale, so named 
 after the inventor, Mr. Edmund Gunter, an eminent English mathematician, 
 who likewise was the author of several other very useful inventions. In the extent 
 to which the Gunter's scale has been adopted, it rivals the Chinese swanpan, 
 whilst its powers far exceed those of the latter instrument. It consists of a flat 
 ruler of box wood, 2 feet long, having various lines laid down upon it, by means 
 of which all the various problems relating to arithmetical trigonometry, and their 
 depending sciences, may be performed by the extent of the compasses only. 
 This will be best explained by a description of the line, culled the line of 
 number, or Gunter's line, which is adapted to the solution of arithmetical 
 questions, and exhibiting a few practical examples. The line of numbers is 
 the logarithmic scale of proportionals, which, being graduated upon the ruler, 
 serves to solve problems in the same manner as logarithms do arithmetically. 
 It is usually divided into 100 parts, every tenth of which is numbered, beginning 
 with 1 and ending with 10 ; so that if the first great division stand for the 
 i of an integer, the next great division will stand for ,|, and the intermediate 
 divisions will represent hundredths of an integer, whilst the large divisions beyond 
 10 will represent units; and if the first set of large divisions represent units, 
 the subdivisions will represent tenths, whilst the second set of large divisions 
 will represent tens, and the subdivisions units, and so on. The general rule for 
 using this instrument is as follows : since all questions are reducible to propor- 
 tions, if the compasses be extended from the first term to the third, the same 
 extent will reach from the second to the fourth term. The following are a few 
 examples of some of the uses of this line. 1. To find the product of any two 
 numbers, as 4 and 8: extend the compasses from 1 to the multiplier 4, anu the 
 same extent applied the same way from 8, the multiplicand will reach the 
 product 32. 2. To divide one number by another, as 36 by 4: extend the 
 compasses from 4 to 1, and the same extent will reach from 9 to 36. 3. To 
 find a fourth proportional to three given numbers, as 6, 8, 9 : extend the com- 
 passes from 6 to 8, and this extent laid the same way from 9, will reach 12, die 
 fourth proportional required. 4. To extract the square root of a number, say 
 25 : bisect the distance between 1 on the scale and the point representing 25, 
 then half this set off from 1 will give the point 5 = the root required. In the 
 same manner the cube root, or the root of any higher power, may be found by 
 dividing the distance on the line between 1 and the given number, into as many 
 equal parts as the index of the power expresses, then one of those parts set 
 from 1, will extend to the number representing the root required. A great 
 improvement has been made in this instrument, by means of which compasses 
 are rendered unnecessary. It consists in having two lines of numbers placed 
 one over the other, one of which lines is engraved upon a slider moving in a 
 groove, and is applied as follows : the first term of the proportional upon the 
 slider being set against the third term upon the fixed scale, the second term of 
 the proportion npon the slider will stand opposite the fourth term on the fixed 
 scale. Instruments of this description, with scales suited to almost every 
 branch of art in which calculation is required, are now common amongst in- 
 telligent workmen, and the scale of chemical equivalents, by which the labours 
 of the chemist are so much facilitated, is constructed upon the same principle. 
 Mr. Lamb has recently arranged the logarithmic scale in a circular form, by 
 which the portability of the instrument, and the facility of its application, is so 
 much increased, that an instrument much smaller than the following represen- 
 tation of it, and which can be conveniently carried in the waistcoat pocket, 
 contains divisions larger and easier to read than those usually placed on the 
 2-feet sliding rule. On the face of the instrument (which Mr. Lamb calls a 
 circular proportioner,) are engraved one double and two single logarithmic
 
 CALCULATING MACHINES. 29] 
 
 lines in concentric circles. The middle circle, which is the moving piece, and 
 is marked A. has both edges divided, for the convenience of ,'icting with the 
 inner or outer circles, which are marked M and L. The moving and inner 
 circles A and M are both numbered 1, 2, 3, 4, 5, 6, 7, 8, and 9. The space 
 
 oetwixt each numbered division is divided into 10, find those divisions read 
 for a second figure. From 1 to 2 each of those divisions is subdivided into 5, 
 standing for the even numbers in the third places of figures. From 2 to 5 
 each tenth division is halved for the 5, in the third place of figures. The spaces 
 must be subdivided by estimation for the intermediate figures. The outer 
 circle, marked L, has a double line of numbers ; the first half circle numbered 
 1, 2, 3, 4, 5, 6, 7, 8, 9, and the second half marked 10, 20, 30, 40, 50, 60, 70, 
 80, 90. The figures on A and M may cither signify 1,2, 3, &c., or 10, 20, SO, 
 &c., or 100, 200, 300, &c., and as the figured divisions alter, so, of course, 
 must the subdivisions; sometimes they stand for decimals. In passing unity 
 to the right, the numbers will contain a figure more, and in passing to the 
 left they will contain a figure less; the first significant figure in a decimal 
 will vary in like manner. Two numbers in a proportion which have the same 
 name must always be taken on the same circle. For multiplication, division, 
 and common proportion, A must work with M ; for the square root and dupli- 
 cate proportion, A must work with L. In direct proportion, the first and second 
 terms will stand together ; but in indirect proportion, the second and third terms 
 will stand together. 
 
 Various machines have likew.se been contrived by Pascal and others, by 
 which arithmetical calculations were made by means of trains of wheels and
 
 292 CALENDERING. 
 
 similar arrangements ; and the late Earl Stanhope invented a machine of this 
 sort, by which he verified his calculations respecting the national debt. But 
 none of these contrivances can bear a moment's comparison with the stupendous 
 machine designed by Mr. Babbage, and now nearly completed, the functions of 
 which are to embody in machinery the method of differences, which has never 
 before been done. It consists of two parts, a calculating, and a printing part, 
 both of which are necessary to the fulfilment of the inventor's views ; for the 
 whole advantages would be lost if the computations made by the machine were 
 copied by human hands, and transferred to type by the common process. The 
 greater part of the calculating machinery, of which the drawings alone cover 
 400 square feet of surface, is already constructed, but less progress has been 
 made in the printing part. The practical object of this machine is to compute 
 and print a great variety and extent of astronomical and navigation tables, 
 which could not otherwise be done but at an enormous expense, whilst it would 
 be impossible to insure the same accuracy. It can also compute the powers and 
 products of numbers, and integrate innumerable equations of finite differences ; 
 that is, when the equation of differences is given, the engine, after being properly 
 set, will produce in a given time any distant term which may be required, or 
 any succession of terms commencing at a distant point. In order to convey 
 some idea of the powers of the machine, we may mention the effects produced 
 by a small trial engine, constructed by the inventor, and by which he computed 
 the following table from the formula x* + x + 4l. The figures, as they were 
 calculated by the machine, were not exhibited to the eye as in sliding rules 
 and similar instruments, but were actually presented to it on two opposite sides 
 of the machine, the number 383, for example, appearing in figures before the 
 person employed in copying. The table is as follows : 
 
 41 131 383 797 1373 
 
 43 151 421 853 1447 
 
 47 173 461 911 1523 
 
 53 197 583 971 1601 
 
 61 223 547 1033 1681 
 
 71 251 593 1097 1763 
 
 83 281 641 1163 1847 
 
 97 313 691 1231 1933 
 
 113 347 743 1301 2021 
 
 Whilst the machine was occupied in calculating this table, a friend of the 
 inventor undertook to write down the numbers as they appeared. At first he 
 rather more than kept pace with the machine; but as soon as five figures 
 appeared, the machine was at least equal in speed to the writer. At another 
 trial, 32 numbers of the same table, containing 82 figures, were computed in 
 2 minutes 30 seconds, or 33 figures per minute. On a subsequent occasion it 
 produced 44 figures per minute, and this rate of computation could be main- 
 tained for any length of time. 
 
 CALENDERING. The operation by which all accidental wrinkles and 
 creases are removed from various kinds of cloths, and their surfaces rendered 
 smooth and uniform previous to packing for transport: calicoes are likewise 
 calendered before printing. The common calendering machine nearly resembles 
 the ordinary mangle, but worked by a horse-wheel, on account of its greater 
 dimensions and weight ; but the more improved machines consist of a series of 
 rollers, between which the cloth passes, the rollers being subjected to heavy 
 pressure, and turning simultaneously either by simple contact, or by means of 
 wheel work. Machines on this principle we believe are of foreign invention, 
 but have received two important improvements in this country ; first, by the 
 introduction of tubular cast iron rollers, into which heaters can be inserted when 
 requisite, which greatly assists the operation with some kind of goods ; and 
 secondly, in the substitution of rollers formed of pasteboard for wooden roller*, 
 the former not being liable to crack or warp like the latter, and being susceptible 
 also of an astonishing degree of polish. These paper or pasteboard rollers are 
 formed as follows: the axis or shaft is formed of a square L;ir of wrought a on,
 
 CALENDERING. 
 
 293 
 
 turned cylindrical at the bearings ; a circular iron plate, of the exact size of the 
 intended roller, is placed upon the square part of the shaft, and near to the 
 end, and a great number of discs of pasteboard, somewhat larger than the 
 intended roller, and having square holes in the centre, are next put upon the 
 shaft, and then another iron plate, and the whole are screwed together by nuts 
 at the ends of four long iron bolts extending from one iron plate to the other. 
 In this manner a cylinder is formed, considerably longer than the intended 
 cylinder ; this is removed to a stove or hot room, and as the paper shrinks by 
 the heat, the plates are gradually screwed up. When, at the end of some days, 
 the paper ceases to shrink, the cylinder is removed from the stove, and becoming 
 exposed to the humidity of the atmosphere, it has a tendency to expand, and 
 becomes exceedingly dense and solid, and is completed by turning in a lathe 
 to the intended size. Some goods are required to have a high polish, called glazing, 
 upon one side ; this glazing was formerly effected by rubbing the cloth with a 
 smooth flint stone, but is now generally performed in the calendering machine, by 
 an addition of wheels, which causes one of the rollers to move slower than the 
 rest, and the cloth consequently rubbing over the polished surface of the 
 
 Fig. I. 
 
 Fig. 2 
 
 lowest mover, becomes glazed, a a Fig. 1, are two paper rollers, each of 20 inches 
 diameter; b b two hollow cast iron cylinders, 8 inches diameter, and 2 inches 
 thick, the exteriors of which are turned perfectly smooth ; c a paper roller, 
 14 inches diameter; d d the framing of cast iron, containing the bushes or 
 bearings, in which the journals of the rollers revolve ; these are firmly pressed 
 together whilst the cloth is passing through, by means of weighted levers. 
 Fig. 2 is an end view of the same calender, with the wheels for glazing the 
 cloth; the wheel on the upper cylinder b is 10 inches diameter, that on the 
 under cylinder b is 13 inches diameter, and both are connected by the wheel/; 
 so that the wheel on the under cylinder being nearly one-third more in diameter 
 than that on the upper cylinder, the difference of their motions retards the
 
 294 CALICO PRINTING. 
 
 centre paper roller, by which means the upper cylinder passes over the cloth 
 one-third quicker than the cloth passes through the calender, and polishes it in 
 consequence. For dressing muslins, gauzes, and other light, transparent fabrics 
 a smaller species of calender is employed. It consists of only three cylinders, 
 of equal diameters, (generally about 6 inches,) and is easily moved by a common 
 winch or handle. The middle cylinder is of iron ; they are all moved with 
 equal velocities by small wheels. This machine is always used in a cold state. 
 Calendering forms one part of the business of a packer ; in the subsequent 
 stages the goods are folded into certain forms, depending upon the nature of 
 them, and the markets for which they are intended ; they are then subjected to 
 the action of a very powerful press, and whilst under pressure are corded, 
 so that when removed from the press they occupy much less room than they 
 otherwise would do. 
 
 CALICO PRINTING. The art of producing upon calico or cotton cloths 
 patterns or designs combining a variety of colours, so as to produce an agreeable 
 and pleasing effect This ingenious business, as at present conducted, may be 
 considered as one branch of the art of dyeing ; and as it depends chiefly upon 
 the proper application of a few compounds, called mordants, we shall commence 
 our description of the process by explaining briefly the nature of colours, and 
 the uses of mordants. The colouring substances employed in this art may be 
 divided into two classes, viz. substantive and adjective. A substantive colour is 
 one which of itself is capable of producing a permanent dye ; such are woad 
 and indigo, and the solutions of some metals, particularly those of iron, cobalt, 
 gold, platinum, and silver, which give various colours, according to the processes 
 by which they are prepared. By adjective colours are meant all those which 
 are incapable of imparting permanent colours witbout the aid of certain inter- 
 media, which having a greater affinity both for the colouring matter and for the 
 cloth, than the colouring matter has for the cloth, forms, as it were, a bond of 
 union between the two latter substances. These intermedia are called mordants : 
 the principal ones at present in use in this country are the acetate of iron, the 
 acetate of alumina, and the various solutions of tin. In the usual process of 
 dyeing with adjective colours, the entire piece of cloth is steeped in the mordant, 
 and some time afterwards is submitted to a bath of the particular kind of 
 colouring matter which is to be imparted to it; but in printed goods, certain 
 parts require to be left white, a pattern, therefore, of those parts which are to 
 be coloured is cut in relief on blocks of wood, or plates of metal, and the 
 mordant being applied over the whole surface of the pattern, the pattern is then 
 impressed upon the cloth, and when the cloth is subsequently passed through 
 the colouring bath, only those parts to which the mordant has been applied 
 will receive a permanent stain ; for although the whole piece will be coloured, 
 those parts which are untouched by the mordant will be easily restored to their 
 original whiteness by washing and exposure to the air. Previous to printing, 
 the cloth undergoes a variety of processes, termed the preparation. The first 
 of these is termed dressing, and consists in passing the cloth very rapidly over 
 a cylinder of iron, at nearly a white heat, or over a broad flame of gas. It is 
 next steeped for twenty-four hours in a weak alkaline lye, at the temperature of 
 about 100, and is afterwards boiled in a solution of potash, which is called 
 ashing, and is then well washed, to free it entirely of the alkali. The next 
 process is called sburing, which consists in immersing the cloth in water con- 
 taining about one-twenty fifth part of its weight of sulphuric acid, and being again 
 well washed and dried, the preparation is completed. Previous to the ordinary 
 description of printing, the goods are calendered, which consists in passing 
 them through a set of rollers, which gives them a gloss; but for what is termed 
 copper-plate printing, or cylinder work, the calendering is omitted. In printing 
 fast colours, the printer proceeds as follows: he lays the calico, which has 
 been already smoothed by calendering, upon a strong thick table, covered with 
 a woollen cloth, and proceeds to apply one or more mordants, as the case may 
 require, for fixing the intended colours. The mordants are applied by means 
 of wooden blocks, to the surface of which the pattern, cut out of thick plates 
 of brass or copper, is firmly fixed. When the mordant is ready, it is either
 
 CALICO PRINTING. 
 
 296 
 
 mixed with flour paste, or a thick aqueous solution of gum Arabic, gum Senegal, 
 gum tragacanth, or of what is called British gum, which is merely common 
 starch calcined and pulverized. In this state the mordant is spread upon a 
 piece of fine woollen cloth, strained tight upon a broad hoop. This is called 
 the sieve, and is placed within another hoop, called the case, covered with sheep 
 skin, or oil cloth, and the sieve within its case is placed in a tub of gum water, 
 and is ready for use. The mordant is applied to the surface of the sieve by 
 means of a brush, which is called teezing; and should the mordant be colourless, 
 as, for instance, the acetate of alumina, some fugitive dye is mixed with it, to 
 make the pattern obvious to the workman, who, taking the block containing the 
 pattern in one hand, applies it gently to the surface of the sieve, so that a 
 sufficient quantity of the thickened mordant may adhere to the figures. He 
 then applies the block thus charged to the calico, giving it a blow with a small 
 mallet, and continues applying the block alternately to the sieve and to the 
 calico, until he has gone over the whole piece. When the piece is intended to 
 contain a variety of colour, several different mordants are thus applied, as the dif- 
 ferent colours require different mordants to fix them and render them permanent. 
 The calico is now removed to a room heated by flues, in order to be dried ; but 
 this is much better effected by an apparatus shown in the annexed engraving, 
 and consisting of a series of cylinders a a made of copper or United iron, and 
 
 filled with steam, and round which the calico is made to pass in succession. 
 Beneath every two cylinders is a vane b b moved by a steam engine, which 
 agitates the air, so as very much to facilitate the drying ; indeed, so rapidly are 
 the goods dried by this mode, that although the fabrics be wound from the heap 
 c on to the first cylinder perfectly wet, they become thoroughly dry by the time 
 they have passed over the whole apparatus, and fall in a perfect state on the 
 heap d. After drying, the pieces are passed by means of a winch through 
 water at various temperatures, with a little cow-dung mixed with it, in order to 
 remove that portion of the mordant which is not actually combined with the 
 cloth, and which might otherwise stain the white or unprinted parts. The pieces 
 are then taken to the river or wash-wheels, to be more effectually cleansed, and 
 afterwards passed through tepid water, in order to insure every impurity being 
 removed. A quantity of madder is next broken into a copper boiler of pure 
 cold water, and a fire is lighted beneath. The ends of several pieces of calico 
 are then skewered together, and immersed in the madder bath, and are kept in 
 constant motion by an apparatus (shown in the article DYEING), driven by a 
 steam engine until the whole attains the boiling temperature, or even for some 
 time after : the colour being by this means uniformly distributed, the pieces are 
 taken out and thoroughly washed. This process, which is called maddering, 
 has the effect of imparting all the requisite colours at one operation, which may 
 be thus explained: while one mordant precipitates the colouring matter to a 
 red, another precipitates a different portion of it of a purple colour ; another 
 precipitates it black, and so of every possible shade from a lilac to a black, and 
 from a pink to a deep red. If a portion of weld or quercitron bark be added 
 to the madder, every shade from an orange to a brown may be produced ; 
 whereas, if weld or bark alone be employed, all colours between a dark olive 
 and a bright lemon can be imparted to the cloth. The mordants generally used 
 in calico printing are acetate of iron for browns, blacks, lilacs, &c., and acetate 
 of alumina for all the different shades of reds and yellows When the good
 
 296 CALICO PRINTING. 
 
 have passed through the madder or weld copper, they are usually carried to a 
 boiler containing wheat bran and water, for the purpose of freeing the white 
 grounds from the stain which they always acquire from the madder, bark, or 
 weld, employed in dyeing the print. It, however, frequently is the case that 
 goods will not bear to be sufficiently branned to clear the whites by that one 
 operation, as branning in some measure impairs the intensity of the colours ; 
 such goods, therefore, are partially cleansed in the branning copper, and are then 
 either laid on the grass for some days, until they become perfectly clean and 
 white, or (which is a much more expeditious process) they are immersed for a 
 short time in a very weak solution of one of the bleaching salts, as oxy-miiriate 
 of potash, soda, magnesia, &c. There is another method of calico printing 
 styled resist work, which is the reverse of that just described, the pattern being 
 printed on a cloth with a certain preparation which resists the colour, when the 
 goods are immersed in the dye vat, so that the grounds only are dyed, the 
 pattern remaining white. This process is practised for printing goods in which 
 the grounds are intended to be blue instead of white. To comprehend the 
 principles of this process, it should be understood that indigo, in its natural or 
 oxygenized state, has no affinity for cloth, but that it is deprived of its oxygen 
 by iron, which has a greater affinity for oxygen than indigo has, and the 
 deoxygenized indigo becomes soluble, and is readily fixed on the cloth. Copper, on 
 the contrary, has a less affinity for oxygen than indigo has ; the oxides of copper, 
 therefore, when dissolved, give up their oxygen to indigo in solution, which thus 
 acquiring oxygen, is restored to its natural state, and can no longer impart its 
 colour to the cloth. The process of resist work is conducted in the following 
 manner : a solution of some of the salts of copper, as the sulphate, nitrate, 
 muriate, or acetate, is thickened with flour paste and gum, or with pipe-clay 
 and gum ; and with this composition applied to the blocks which contain the 
 pattern, the pieces are printed in the manner before described of printing 
 with mordants. The pieces, when thoroughly dried, are then repeatedly dipped 
 in the blue vat, as it is called, which is formed by mixing indigo with lime and 
 sulphate of iron, in such proportions as shall most effectually deoxidize the 
 indigo. In this vat the grounds receive the required depth of colour, but the 
 parts printed with the solution of copper remain undyed, because the deoxidized 
 indigo becomes oxygenated the moment it touches the copper, which parts with 
 its oxygen to the indigo, and^occasions it to become insoluble, and consequently 
 incapable of forming a dye. After the goods have been sufficiently immersed 
 in the blue vat, they are washed and passed through diluted sulphuric acid, 
 when those parts which had been printed with the preparation of copper are 
 found to be preserved of a good white, the preparation having effectually resisted 
 the operation of the indigo, although all the other parts of the cloth have 
 received a permanent dye. When the pattern contains a variety of colours, 
 the white parts are subsequently printed by the method already described, (of 
 mordants,) and a bath of madder, weld, or quercitron bark, as the case may be. 
 Resist work, as we have already stated, is employed when blue is to be the 
 predominant colour or ground of the piece ; but if the ground is to be white, 
 and the pieces to have only a small object in indigo blue, the colour is printed 
 with indigo deoxidized by orpiment, and commonly called pencil blue, because 
 formerly whatever objects were done with it, were put in with a pencil. This 
 preparation requires to be fixed on the calico before the indigo has time to 
 recover its oxygen from the atmosphere ; to protect it from which an apparatus 
 has been contrived, in which the sieve which furnishes the colour to the blocks 
 floats within the colour contained in a vessel, in which the liquid is supplied 
 from an air-tight reservoir, on the principle of a bird fountain, so as always to 
 maintain the liquid in which the sieve floats at the same height. A third 
 method of printing calicoes is that called discharge work, which consists in first 
 dyeing the cloth of some uniform colour, by means of some of the common 
 vegetable dyes, and iron liquor, which is always used in such quantity as to 
 cover, or at least to disguise in a great measure, the colours employed with it. 
 The cloth is then washed, dried, and calendered, and then printed with a solution 
 of one or more of the metals in some of the mineral acids, which, dissolving the
 
 CALICO PRIIsriNG. 
 
 297 
 
 iron in the parts to which the pattern is applied, restores the cloth to the colour 
 with which it was originally dyed. Thus, if a piece, treated with a decoction 
 of Brazil wood, and dyed black by being passed through iron liquor, be afterwards 
 printed with a peculiar solution of tin, the ferruginous part of the dye will be 
 dissolved, and the printed part will instantly be converted from a deep black to 
 a brilliant crimson. This process is only applicable where all the purposes are 
 attained by simply dissolving the iron which forms part of the colour that is to be 
 discharged ; whereas, for the fine and more expensive work, citric acid, mixed 
 with gum or flour paste, is printed on the cloth, and wherever it attaches, the 
 mordant, whether iron or alumine, is discharged, and a delicate white is left in its 
 place. There is another species of discharge work by which the patterns on 
 the beautiful Turkey red bandannas are produced ; but as this cannot be pro- 
 perly called a printing process, we refer our reader for a description of it to the 
 article BANDANNA. The ordinary sorts of what is called chintz furniture are 
 produced by the process first described, which is repeated one or more times 
 for the superior sorts, varying each time the mordants and the dyeing stuffs ; 
 and when the greatest possible variety of colouring is desired, a portion of the 
 white ground is sometimes coloured blue, by putting in with a pencil the pre- 
 paration called pencil blue ; and green is in the same manner produced by 
 applying some of the same colour to parts previously dyed yellow. We shall 
 conclude this article by noticing an improvement which has been made of late 
 years by the introduction of cylinder printing, which has the advantages of 
 superior accuracy and neatness, as well as of greater expedition. In these 
 
 printing machines the pattern is engraved on cylinders of copper, or brass, o 
 wood, which supply themselves with the prepared colour during their revolutions, 
 which colour is transferred to the cloth by the latter rolling over the printing 
 cylinder as it is wound from one roller on to another. Many of these machine*
 
 298 CAMERA LUCIDA. 
 
 are contrived so as to carry two of these cylinders, each of which has a trough 
 of colour attached to it, by which means two different colours may be printed 
 at a time on one piece of calico, and Mr. A. Parkinson, of Manchester, has 
 invented a machine capable of printing at one time, by means of one cylinder 
 and two surface rollers, or by two of the former and one of the latter, three 
 distinct colours. The leading arrangements of this machine are exhibited in the 
 engraving on the preceding page, a the main roller of iron, round which the calico 
 passes to receive the impression from the three smaller rollers ; b one of the 
 screws, to give proper pressure to the main roller ; c a copper roller, with one 
 of the patterns engraved on it, and pressed against the main roller by the screw 
 d. The roller c receives colour from a small box at the top, which could not be 
 shown in the engraving, e and e two wooden rollers, on each of which is cut 
 a pattern ; //two blankets, to supply colour to the rollers e e. These blankets 
 receive the colour by revolving in contact with the rollers g g, turning in the 
 colour boxes h h, and the colour is uniformly spread by the rotatory motion, by 
 the time it arrives at the rollers on which it is to be deposited, i i are guiding 
 and stretching rollers to the two colour blankets; k the guide roller to the 
 blanket which is interposed between the main cylinder and the calico ; / the 
 roller from which the plain calico is unwound during the process of printing ; 
 m the calico passing from the printing rollers in a printed state. Mr. Parkes 
 (from whose Essay on Calico Printing the foregoing description of the process 
 is taken,) observes, that not only is the printing more correctly performed by 
 the cylinders than can possibly be done by means of the block, but also the 
 saving of time and labour is so great, that a piece of calico which would take 
 a man and a boy three hours to print with one colour, or six hours to finish with 
 two colours, may be printed by the machines in three minutes, or three minutes 
 and a half, and the work will be much more completely done than could have 
 been even imagined before the introduction of this invention. 
 
 CALLIPERS. A sort of compasses, made with bowed or arched legs, and 
 used for measuring the diameter of cylindrical bodies. 
 
 CALOMEL. Chloride of mercury, frequently called mild muriate of mercury. 
 
 CALORIC. A modern term to denote heat, or the cause by which the 
 phenomena of heat are produced. See CHEMISTRY. 
 
 CAMBER. A term applied to that slight degree of arching which is usually 
 given to beams, which see. 
 
 CAMEL. A contrivance for lifting ships over a bar or bank obstructing the 
 navigation of a river. It is used in Holland, and some other parts, particularly 
 at the Dock at St. Petersburgh. A camel is composed of two separate parts, 
 whose outside is perpendicular, and the inside concave, so as to embrace the 
 hull of a ship on both sides. They are braced to a ship underneath, by means 
 of cables, and 0i*Utly enclose its sides and bottom. They are then towed to 
 the bar, and the water being pumped out of them, the camel rises, lifts up the 
 vessel, and the whole is towed over the bar. 
 
 CAMEO. The name given to stones of various colours, which contain 
 ancient sculptures in relief. 
 
 CAMERA LUCIDA. An ingenious and elegant invention of the late 
 Dr. Wollaston, for the purpose of facilitating the delineation of objects, by 
 producing a reflected picture of them upon the paper. It consists of a solid 
 prismatic piece of glass, mounted upon a stem capable of elongation or con- 
 traction, and which can be screwed at the foot to a table or drawing board. The 
 prism has its angles so arranged, that the rays from the object are reflected upon 
 the paper, and is covered at top by a metallic eye-piece, the hole in which lies 
 half over the edge of the prism, so as to afford to a person looking through, 
 a view of the picture reflected through the glass, and a direct view of his pencil 
 or tracing point. By means of this instrument, a person unacquainted with 
 drawing may delineate objects with great ease and accuracy. For specimens 
 of the capabilities of this instrument, we would refer to the volume of plates to 
 Capt. Basil Hall's Voyage to the United States of America, the whole of which, 
 consisting of representations of scenery, animals, portraits, &c. were sketched 
 by means of this instrument by Capt. llall, who had no knowledge of drawing.
 
 CANALS. 299 
 
 CAMERA OBSCURA. An instrument for a similar purpose as the foregoing, 
 but constructed upon different principles, the rays from the object being caused 
 to pass through a convex glass, on to a white surface placed opposite to the 
 glass, in a darkened chamber. A camera obscura may be constructed as 
 follows : darken a chamber, and into a small aperture made for the purpose in 
 one of the window shutters, fit a lens, either plano-convex, or convex OH both 
 sides ; and at a due distance, to be determined by experience, place a paper or 
 white cloth, and the objects opposite the lens will be shown upon the paper in 
 their natural colours and proportions, but in an inverted position ; by placing a 
 concave lens between the centre and the focus of the first lens, the images will 
 be shown erect. If the aperture do not exceed the size of a pea, the objects 
 will be represented without a lens. 
 
 CAMPHOR. There are two kinds obtained from the East, one from Sumatra 
 and Borneo, the other from China and Japan It is extracted from the roots, 
 wood, and leaves of the laurus camphora, the roots affording the greatest quantity. 
 It is distilled in large iron pots, to which earthen heads, stuffed with straw, are 
 adapted, and provided with reservoirs. Most of the camphor becomes con- 
 densed in the solid form amongst the straw, and part comes over with the water. 
 The refinement of this camphor is performed by sublimation in low flat-bottomed 
 glass vessels placed in a sand bath, and the camphor becomes concrete in a pure 
 state against the upper part, whence it is separated after breaking the glass with 
 a knife. Lewis asserts that no addition is necessary in the purification of 
 camphor, but that the chief point consists in managing the fire, so that the 
 upper part of the vessel may be hot enough to bake the sublimate together in 
 a cake. Chaptal says, that the Dutch mix one ounce of quick lime to every 
 pound of camphor, previous to distillation. Mr. Gray states, that two pounds 
 of quick lime should be added to each hundred weight of rough camphor, and 
 the sublimation be performed in a very gentle heat. Camphor is likewise 
 obtained from thyme, rosemary, and other vegetable substances. Purified 
 camphor is a white, concrete, transparent, extremely volatile, and inflammable 
 substance, of a powerful fragrant odour, and acrid taste. It is insoluble in 
 water, but soluble in alcohol, ether, and the essential oils. It is used in the arts 
 for assisting the solution of resins ; also in medicine. 
 
 CAMPHORIC ACID. An acid obtained by repeated distillation of nitric 
 acid upon camphor. It appears in the form of crystals, soluble in alcohol, oils, 
 and mineral acids. It also dissolves easily in hot water, but requires about 200 
 parts for its solution at the ordinary temperature. 
 
 CANAL. An artificial cut in the ground, supplied with water from rivers 
 or springs, &c. in order to form a navigable communication between one place 
 and another, and also for supplying towns with water. The advantages to be 
 derived from canals were not unknown to the ancients. Egypt, from the 
 remotest antiquity, contained a number of canals, dug to receive and distribute 
 the waters of the Nile at the time of the inundation ; but the most celebrated 
 canal in that country was that which connected the Nile with the Red Sea, 
 which was completed under the second Ptolemy, and was four days' journey in 
 length. It was subsequently neglected, but was afterwards re-opened by one of 
 the caliphs, in 635, after which it was again neglected, so that it is difficult to 
 trace the remains of it at the present day. The aqueducts of the Romans were 
 a species of canal, and they had many also for draining the water from over- 
 flowed grounds ; and attempts were made (although unsuccessfully) by one of 
 the emperors, to cut through the Isthmus which joins the Peloponnessus to 
 Greece. But China, in the number and extent of its canals, far exceeds all 
 other nations, there being scarcely a town or village that is not washed by the 
 sea or by a river, but has a canal. The Great, or Royal Canal, is the most 
 magnificent work of the kind in the world; it is 825 miles in length, 50 feet in 
 width, and 9 feet deep, and extends from Canton to the northern frontiers of 
 the empire. Most of the countries in Europe are provided with one or more 
 works of this kind : those of Holland, from their number and the admirable 
 mode in which they are managed, have long been the theme of travellers ; but 
 perhaps the most stupendous work of the kind is the canal of Languedoc, in
 
 300 CANALS. 
 
 France, which forms a junction between the Mediterranean and the Atlantic. 
 It was begun in 1666, and finished in fifteen years. The breadth is 144 feet, 
 including the towing paths; the depth is 6 feet," and the length 64 French leagues, 
 and it has 114 locks. Although this country at the present day is superior to 
 any nation in Europe (with perhaps the exception of Holland), in the number 
 and magnitude of its canals, it was one of the last to adopt this important 
 improvement ; for if we except the New River Cut for supplying London with 
 water, England, up to the middle of the last century, had not a canal worthy 
 of notice ; and the honour of their introduction is due jointly to the spirit and 
 perseverance of the Duke of Bridgewater, and to the skill and talents of the 
 celebrated Mr. Brindley. The duke had at Worsley, about seven miles from 
 Manchester, a large estate, rich in coal, which had been hitherto useless, on 
 account of the expense of land carnage ; he therefore consulted Mr. Brindley 
 as to the practicability of forming a communication by water, who, having sur- 
 veyed the ground, and declared the scheme to be practicable, the duke, in 1758, 
 obtained an act to make a navigable cut or canal from the township of Salford, 
 to or near Worsley Mill, and to a place called Hollens Ferry, in Lancashire ; 
 but extending his views as the work advanced, he subsequently obtained two 
 other acts, the first to carry it over the Irwell to a place called Longford-bridge, 
 and the second to extend it from Longford-bridge to a place on the Mersey 
 River, called the Hempstones. The whole navigation was then proceeded in 
 and completed, being more than 29 miles in length, and having, at its fall into 
 the Mersey, locks which let it down 95 feet. It should be remarked that the 
 locks were formed at Runcorn, instead of the Hempstones. The completion of 
 these works quickly rendering apparent the important advantages of canals to 
 the commercial and manufacturing interests, new undertakings of the kind 
 succeeded each other with such rapidity, that the bare enumeration of those 
 existing at the present day would occupy more space than we could spare for 
 the purpose. Amongst the principal are the Grand Trunk, or Staffordshire 
 Canal, forming a communication between the Trent and the Mersey, and, con- 
 sequently, between the German Ocean and the Irish Sea ; the Thames and 
 Severn; the Birmingham Canal; Peak Forest and Grand Junction, in England ; 
 and the Caledonian Canal, in Scotland. The total number of canals in Great 
 Britain is 103 ; the total extent 2688 miles ; and the capital sunk in their con- 
 struction is computed at upwards of thirty millions sterling. With two or three 
 exceptions, they were all constructed by the combined exertions of private 
 individuals ; and important as these works are now become, none of them were 
 projected prior to 1755. The particular operations necessary for making arti- 
 ficial canals depend upon a variety of circumstances. When the ground is 
 naturally level and unconnected with rivers, the execution is easy, and the 
 navigation not liable to be disturbed by floods ; but when the ground rises and 
 falls, and cannot be reduced to a level, artificial means of raising and lowering 
 vessels must be employed. The ordinary expedients are either inclined planes 
 or locks. The first of these methods, viz. the inclined planes, is chiefly resorted 
 to in cases where the canal is so very scantily supplied with water that its 
 economy becomes an object of the first importance. For this purpose, an 
 inclined plane of masonry is constructed, extending from one level to the surface 
 of the next above it, and the boats are hauled up the plane upon a kind of 
 cradle or sledge, furnished with rollers, and this, it is said, was the only method 
 employed by the ancients, who appear to have been ignorant of the nature and 
 utility of locks. The engraving on the opposite page represents an improvement 
 upon this method of passing boats from one level to another, by which the boats 
 maintain their parallelism whilst ascending the inclined planes. It is the 
 invention of Mr. J. Underbill, of Parkfield Iron Works, near Wolverhampton. 
 The following is a description of the engraving : a the higher level of the 
 water of the canal; b the lower level; the bottom of the canal is a little 
 excavated at each of these places, to admit of a kind of cradle carriage to be 
 sunk sufficiently deep for a boat to be floated on to or off it. At c is represented 
 a laden boat, placed upon the upper level in its carriage //; and at d another, 
 similarly circumstanced upon the lower level, in its carriage gg. Each of them
 
 CANALS. 
 
 is attached by strong chains to a drum-wheel h, properly mount <1 in a strong 
 
 framing, and worked by a steam engine or other adequate power. The carriages 
 
 are mounted upon two pairs of solid iron wheels, which run upon railways 
 
 tli at connect the upper 
 
 and lower levels. These 
 
 railways form two inclined 
 
 planes for the ascent of 
 
 the carriage, and the same 
 
 for its descent, whilst the 
 
 two slopes are connected 
 
 at top by a horizontal 
 
 plane. This will be clearly 
 
 understood by reference 
 
 to the diagram. The boat 
 
 c is there represented in 
 
 its carriage, and ascend- 
 
 ing the double rails or 
 
 planes r, the hind wheels 
 
 being on the top r 
 
 the fore wheels -on the 
 
 on the top rails, and 
 
 bottom rails, but confined 
 in their track by the pa- 
 rallel bars o above, which 
 preserve the carriage from 
 shifting out of the hori- 
 zontal position. Before 
 arriving at the top, the 
 fore wheels open two 
 latches /, having counter- 
 balance weights, and both 
 hind and fore wheels 
 arrive together on the top 
 of the horizontal line of 
 rail. On drawing it for- 
 ward for the descent into 
 the lower level of the 
 canal, the latches / become 
 closed, and the carriage is fj 
 sent forward, as shown by 
 the dotted lines at e, before 
 descending, when the fore 
 wheels open the latches j| 
 for the hind wheels to 
 enter between the parallel 
 bars ; g g shews the boat III v 
 and carriage delivered on 1| 
 to the lower level of water, 
 where the carriage sinks 
 to a sufficient depth to 
 allow the boat to float 
 away from it. The pa- 
 tentee proposes to employ 
 similar machinery for 
 raising weights on land. 
 But where canals have an 
 abundant supply of water, 
 the usual method of trans- 
 mitting boats from one level to another is by locks. A lock is a long narrow 
 passage connecting two contiguous levels, of sufficient width and length to 
 receive a boat, and in depth extending from the top of the upper level to the 
 Q Q
 
 302 CANALS. 
 
 bottom of the lower level. The sides are usually formed of masonry, and at 
 each end is a pair of strong gates, turning upon centres strongly secured to the 
 walls. The gates next the upper level extend only to the bottom of that level, 
 but those at the lower level extend the whole depth of the lock. These gates 
 are opened and shut by means of tong projecting arms or levers, and when 
 closed, the gates meet in an angle pointing up the stream. At the upper end of 
 the lock is a sluice, by which the water can be admitted into the lock from the 
 upper level ; and at the lower end is another sluice, by which the water can be 
 discharged from the lock into the lower level. The operation of passing a boat 
 from one level to another is as follows : suppose it be required to pass the boat 
 from the upper level to the lower, and that the water in the lock is at the same 
 height with the water in the lower level, and that the gates at each end of the 
 lock are closed; the sluice at the upper end is first opened, and the water 
 admitted into the lock from the upper level ; and when it attains the same height 
 in the lock as in the upper level, the sluice is shut, the upper gates opened, and 
 the boat hauled into the lock. The upper gates are then closed, the sluice at 
 the lower end of the lock opened to discharge the water into the lower level, 
 and when the water stands at the same height in the lock as in the lower level, 
 the sluice is shut, the lower gates opened, and the boat hauled out of the lock 
 into the lower level. In the reverse operation, or passing a boat from the lower 
 level to the upper, the water in the lock is first reduced to the height of the 
 water in the lower level, when the lower gates are opened to admit the boat 
 into the lock, after which they are closed, and water admitted into the lock 
 from the upper level, until it stands at the same height in each, when the upper 
 gates are opened, and the boat passed into the upper level. The operation just 
 described is extremely simple and easy, but it will be seen that at each transit 
 of a boat in either direction, a lock full of water is drawn from the upper pond 
 and lost. This loss is of such consequence on some canals, that the water is 
 pumped back to the upper level by a steam 1 engine, and numerous plans have 
 been proposed for avoiding or lessening this loss. On the Regent's Canal the 
 locks are double, and placed side by side, with a sluice in the middle pier to 
 admit the water from one lock into the other. In passing a boat from the upper 
 to the lower level by these locks, the water is not discharged from the full lock 
 into the lower level, in the first instance, but it is admitted into the empty lock 
 until it stands at the same height in each ; after which the sluice in the middle 
 pier is shut, and the remainder of the water discharged into the lower level, by 
 which means only about half a lock full is lost at each transit. Mr. Brownill, 
 of Sheffield, has proposed a plan for passing boats from one level to another, 
 with very little loss of water, which we shall endeavour to describe with the 
 assistance of the engraving on the following page, which represents a vertical 
 section of the apparatus, a is the upper level of the canal ; b the lower level ; 
 cc section of the end walls of the shaft in which the cradle works ; d one of the 
 side walls of the same ; e the gate of the upper level ; / the gate of the lower 
 level ; g g a number of bearings, supporting the horizontal axis h, on which 
 are placed the large sheaves kk, over which the suspending chains run ; to one 
 end of these chains is attached the cradle o, and to the other end is hung the 
 counterbalance I (shown in dotted lines), which rises and falls in a side shaft, 
 there being a similar counterbalance in another shaft on the opposite side of 
 the main shaft d ; these two counterbalances are made to act together by 
 means of the large wheel n acting on a similar wheel on the axis of the opposite 
 counterbalance. This arrangement the inventor terms his double union lift. 
 The cradle o has a sluice at each end, fitted with smaller sluices p p ; it has 
 also a double bottom q; r is a short lever at the lower end of the cradle, 
 which does not prevent its ascent, but as soon as it arrives above the inclined 
 plane *, its upper end turns over, and rests against the dotted lever t, termed 
 the release lever ; and upon allowing the cradle to descend a little, the lever 
 r, acting upon the inclined plane s, forces the cradle over against the sill of 
 the gate of the upper level. At the opposite corner of the cradle is a similar 
 apparatus (not shown in the drawing,) to act upon the inclined plane x. To 
 pass a boat from the lower level to the upper one, the cradle is forced by
 
 CANALS. 
 
 303 
 
 the pressure of the lever upon the inclined plane x, close over to the entrance of 
 the lower level ; the small sluices p p are then opened to admit the water into 
 the cradle, until it stands at the same height in it as in the upper Jevel, when 
 the larger sluice in the cradle and the gate/ are opened. The boat is now hauled 
 into the cradle, after which the gate and sluices are again closed, and the 
 counterbalances (which consist of large iron tanks filled with water), being at 
 the top of their shafts, as much water is let out from the double bottom q of 
 the cradle o as will cause the counterbalances to preponderate when they descend, 
 and thereby cause the cradle containing the boat to ascend and pass the inclined 
 
 planes s ; but as there is a small portion of water in the side shafts, the coun- 
 terbalances are checked in their descent on reaching this water ; they then rise 
 slightly, and allow the cradle to settle on the inclined plane s, which forces it 
 against the upper level ; the small sluice p is next opened, and as soon as the 
 water stands at the same level on each side of the large sluice, the latter and 
 the gate of the canal are opened, and the boat can then pass into the upper 
 level. If now a boat is to be passed from the upper to the lower level, it is hauled 
 into the cradle ; the gate e and the large sluice, and the smaller sluice p are all
 
 304 CANDLES 
 
 shut, and as much water is admitted in the double bottom p of the cradle (from 
 a side reservoir, shown dotted,) as will give the cradle a preponderance; and the 
 release lever being let go, the lever r turns over, and the cradle descends, and 
 on reaching the bottom of the shaft it is passed into the lower level in the 
 mariner described for passing it into the upper one. The ends of the cradle 
 must be covered with stuffing of some kind, to prevent as much as possible the 
 escape of the water when the sluices are open. 
 
 CANDLE. A cylindrical mass of tallow, or other concrete oleaginous 
 matter, having in its axis a cotton or other wick, and employed to afford 
 artificial light Next to tallow, the substances most extensively used are wax 
 and spermaceti* Some valuable substitutes for these have recently been dis- 
 covered and introduced in the manufacture of candles, which we shall give 
 an account of in this article, after having described the processes employed in 
 the production of the former. There are two sorts of tallow candles, dips and 
 moulds; the former being made by dipping the wicks in melted tallow, the 
 latter, by casting, or pouring the fluid tallow into moulds containing the wicks 
 stretched longitudinally throughout their centres. The cotton used for making 
 the wicks is loosely twisted, and is prepared for the manufacturer in large balls 
 who draws out a thread from each of five, six, or more balls, (according to the 
 'thickness of wick required,) and cuts them off to the length of the intended 
 candle. The apparatus for cutting the cotton is simply a smooth board, made 
 to fix on the knees ; on the upper surface is the blade of a razor, and at the 
 required distance a piece of cane is fixed, around which the cotton is carried, 
 and being thence brought over the edge of the razor, is instantly separated. 
 The next operation, called "pulling the cotton," consists in drawing the threads 
 through the hand, and removing knots or other unevenesses. The cotton is 
 next "spread," or extended between two rods, about half an inch diameter, a/id 
 three feet long ; these are called broaches. In dipping candles by hand, the 
 workman takes two broaches at a time, strung with the proper number of wicks, 
 and holding them equidistant by means of the second and third fingers of each 
 hand, he immerses them in a vat containing the fluid tallow, three times suc- 
 cessively for the first lay or coat, then holds them for a while over the vessel 
 to drain, and afterwards suspends them on a rack above, where they continue to 
 drain. When this first coating of tallow has solidified, the workman proceeds 
 in like manner to give them their second coat, by dipping them twice before 
 hanging them again to drain and cool. The number of lays or coats thus given 
 to the candles depends upon the thickness they are required to be. During the 
 operation the vat is supplied from time to time with fresh tallow, kept at a 
 proper temperature by means of a gentle fire underneath it. Tallow-chandlers 
 have of late years, however, generally availed themselves of a very simple and 
 convenient piece of mechanism for aiding them in their dipping process. Five 
 or six of the broaches, filled with the cotton wicks as already described, are 
 fixed at both their ends into a movable frame, which is suspended over the vat 
 upon one extremity of a lever, and is counterbalanced at the other by weights 
 in a scale, which are increased as the candles become heavier. By this arrange- 
 ment it is obvious that the workman has only to guide the frame in dipping the 
 candles, and not to support the weight between his fingers, as before mentioned. 
 It is said that other mechanical contrivances have been introduced for the same 
 purpose, but we are not aware of any so simple and efficient. The mould in 
 which moulded candles are cast consists of a frame of wood, and several hollow 
 metal cylinders, generally made of pewter, of the diameter and length of the 
 candle wanted, and having an aperture at each end for the cotton to pass 
 through, which is performed by a wire, the cotton being fastened so as to keep 
 it straight and in the centre of each mould. Tallow being poured into these 
 moulds, the candles are suffered to cool and harden, when they are readily 
 withdrawn out of the tubes. The kind of candles called rush-lights, differ only 
 by their containing a rush as a substitute for the cotton wick, which prevents 
 the necessity of snuffing. Lately, however, small cotton wicks have been 
 introduced, which do not require snuffing ; these burn with a steadier light, and 
 are not so liable to go out as those with rushes.
 
 CANDLES. 305 
 
 Wax caudles arc also of various kinds ; they are made of cotton or flaxen 
 wicks, and covered with white or coloured wax, which is performed either by 
 the ladle or by the hand. In making them by the ladle, a dozen of them are 
 tied by the wick at equal distances round an iron ring, suspended over a large 
 basin of copper, tinned on the inside, and full of melted wax ; a large ladleful 
 of this wax is gently poured on the tops of the wicks one after another, and the 
 operation continued till the candles arrive at their destined dimensions. The 
 Arst three ladlesful are poured on to the tops of the wicks, the fourth at the 
 height of three-fourths, the fifth at one half, and the sixth at one-fourth, in 
 order to give the candles their proper form, whicli are then taken down and 
 smoothed by rolling upon a walnut-tree table, with a smooth box-wood instru- 
 ment, which is continually moistened with hot water to prevent the adhesion of 
 the wax. In making wax candles by the hand, the workmen begin to soften 
 the wax by working it several times in hot water, contained in a deep narrow 
 cauldron. A piece of the wax is then taken out and disposed by little and little 
 around the wick, which is hung on a hook in the wall, by the extremity opposite 
 to the neck, so that they begin with the large end, diminishing still as they descend 
 towards the neck. In other respects, the method is nearly the same as in the before- 
 mentioned. There is, however, this difference, that in the former case, water 
 is used to moisten the instruments, while in the latter, the hands are lubricated 
 with oil of olives, or lard, to prevent the adhesion of the wax. Wax tapers are 
 drawn after the manner of making wire. By means of two large wooden rollers 
 the wick is repeatedly passed through melted wax contained in a basin, pro- 
 vided on one side with an instrument full of holes, through which the cylinder 
 of wax also traverses until it has obtained the required size. 
 
 Candles are made from spermaceti, the process being very similar to that 
 employed in making them of tallow ; they are also made of various 
 mixtures of tallow, spermaceti, and wax; certain proportions of which con- 
 stitute the article termed composition candles. The meritorious investi- 
 gations of M. Chevreul, concerning the true nature of fatty substances, which 
 were published a few years ago in the Annales de Chimie, appear to have 
 opened a wide and diversified field for the operations of the manufacturer and 
 the experimentalist. By dissolving fat in a large quantity of alcohol, and 
 observing the manner in which its different portions were acted upon by this 
 substance, and again separated from it, M. Chevreul found that fat is composed 
 of an oily substance, which remains fluid at the ordinary temperature of the 
 atmosphere, and of another fatty substance which is much less fusible. Hence 
 it follows that fat is not to oe regarded as a simple principle, but as a combi- 
 nation of the above two principles, which may be separated without alteration. 
 To the former of these substances, which melts at 450 Fahr., and has 
 very much the appearance and properties of vegetable oil, M. Chevreul 
 gave the name of elain, and to the latter, which melts at 100, he gave 
 the name of stearin ; this is separated from the former by crystallization 
 in the form of small silky needles, while the elain is obtained by evaporating 
 the spirit. M. Bracconet subsequently employed a simpler process to obtain the 
 elain and stearin ; he squeezed the tailor between folds of porous paper, which 
 absorbed the elain, leaving the stearin between ; the paper being afterwards 
 soaked in water, yielded up its oily impregnation. The principle of M. Brac- 
 conet's process is now extensively applied by manufacturers, who employ 
 powerful presses to squeeze the fluid oil from the tallow In the year 1825, 
 M. Gay Lussac, the celebrated French chemist, also took out a patent for this 
 country for the employment of the stearin (termed likewise margaric acid from 
 its chemical properties) in the manufacture of candles ; the patent likewise ex- 
 tending to a new mechanical construction of candles. Of the several processes 
 that may be employed for obtaining the margaric acid for this purpose, two are 
 particularly descriptive in the specification, namely, saponification and distilla- 
 tion. The first is to be effected by incorporating any of the alkalies with the 
 fat, as is done in the making of soap, and then decomposing the soapy fluid by 
 an acid that has the greatest affinity to the peculiar alkali employed. It is 
 recommended that the decomposition be effected in a large quantity of water,
 
 306 
 
 CANDLES. 
 
 heated by steam, which should be kept well stirred. Being afterwards allowed 
 to rest, the products will float on the surface in a condensed and solid form. Jf 
 the tallow or fat, thus purified from the matters soluble in water, should still 
 contain any of the salts employed in the previous process, it is to be washed by 
 additions of fresh quantities of warm water, until they are perfectly discharged. 
 This being done, and the mass of fat having become solid by cooling, it is to be 
 subjected to the action of a powerful press, similar to those used for expressing 
 oil from seeds, when the fluid oleic acid (or elain) will run off, leaving the mar 
 garic acid in the press, from which product the candles are to be made. The 
 distilling process is conducted by exposing the fat, in an ordinary still, to the 
 heat of a furnace. Steam is also to be introduced into the still to facilitate the 
 operation, and to carry over those products which are soluble in it, through the 
 worm or condenser, into a receiver. Care must be taken in regulating the heat 
 of the furnace, to prevent discolouring the materials in the still The fat thus 
 prepared is to be purified by washing, and then subjected to pressure as in the 
 previously described process. For the more perfect purification of the fat, both 
 the foregoing operations of saponification and distillation may be combined, and 
 the residue after subjected to pressure. The margaric acid may also be bleached 
 by exposure to the air and sun the same as in the bleaching of wax ; the oleic 
 acid, or fluid oil, may also be whitened by similar means, and be applied 
 generally to the same purposes as the vegetable oils. The form of M. Gay 
 Lussac's candles is that of hollow cylinders, through which a stream of air 
 passes to the wick (on the principle of the argand burner in lamps) for the pur- 
 pose of producing a perfect and vivid combustion of the tallow. He directs that 
 the wick be formed of cotton yarn twisted rather more closely than usual; this yarn 
 is to be wound spirally round a metallic rod or thick wire, in the same manner as 
 wire is sometimes coiled round the large strings of musical instruments. These 
 rods, covered as described, are to be inserted into the moulds 
 used for making candles ; and when the candles have been cast, and 
 the tallow become hard, the wires are to be withdrawn, leaving 
 the wicks behind in the candles with a perforation, or air passage, 
 equal to the size of the rods, throughout their whole length. 
 We have thought it proper to introduce this account of M. Gay 
 Lussac's specification of his patent, because it affords clear and 
 judicious instructions in conducting similar operations. The pro- 
 cesses possess scarcely any originality in the mode of procedure ; 
 and as regards the invention of the candle itself, the French 
 chemist is just twenty years behind two of our own countrymen, 
 namely, Messrs. Desonneaux and Hutchings, who took out a 
 
 Cut for the identical contrivance in the year 1805. It is per- 
 worthy of notice here, that this invention affords a very 
 remarkable proof that many individuals may, without communi- 
 cation or knowledge of each others' ideas, invent precisely the 
 same thing. The writer^of this article, about ten years ago, spon- 
 taneously thought of the same contrivance, and made a candle of 
 the kind, which is represented in the annexed cut. The dotted 
 lines at a mark out the central aperture for the air; and the 
 wick, which is bedded in the middle of the thickness of the hollow 
 cylinder of tallow, is a common argand wick. This candle, 
 although not fabricated in a workmanlike manner, gave good 
 indications of success under proper management. Upon mention- 
 ing the project to some friends, we learned to our surprise that 
 several other persons had entertained the same propositions, each 
 person imagining himself to be the sole inventor. In like 
 manner we were informed by the before-mentioned gentleman, 
 Mr. Desormeaux, that he had patented the invention at the time 
 stated ; that a large manufactory was commenced for the purpose 
 of making the article, with every probability of success ; and that 
 the reason why the manufacture of them was not carried forward, had no refer- 
 ence to the practicability of the scheme. Seeing that the subject has beeu
 
 CANDLES. 307 
 
 taken up by scientific as well as practical men, we are confirmed in our opinion 
 that important results may yet flow from prosecuting the plan, if undertaken 
 by some intelligent person. We are not wholly indebted to the animal kingdom 
 for a supply of the material for candles, several vegetable oleaginous substances 
 having been recently introduced as valuable substitutes. On the 2d of Novem- 
 ber, 1829, a patent was granted to Mr. John Soames, jun. of Spitalfields, for 
 the right of separating the constituent principles of the cocoa-nut oil of com- 
 merce, which, from its consistence at ordinary temperature, is also called 
 " butter of cacao." Before the date of this patent, cocoa-nut oil was of very 
 limited utility, owing to the presumed necessity of artificial heat to render the 
 mass sufficiently fluid to be burned in lamps, and to that apparent want of 
 solidity which is required in the manufacture of candles. Mr..Soames's pro- 
 cess for separating the fluid from the solid matter in cocoa-nut oil is as follows : 
 the oil is put into strong linen bags, 2 feet long, 6 inches wide, and 1 J inch thick; 
 these are covered with stout sack-cloths made for the purpose, and are laid 
 flat upon the horizontal bed of a hydrostatic press, leaving a small vacant space 
 between the bags. Pressure is then given to them, and continued until the oil 
 ceases to flow, or is only given out by drops slowly. This oil being received 
 into a cistern, is allowed to stand a little time to deposit its impurities, after 
 which it is drawn off clear, and preserved for burning in lamps, &c. The solid 
 portion being now taken out of the bags in the press, is next to be purified from 
 the other vegetable principles with which it is usually combined, such as fibre, 
 mucilage, &c. For this purpose it is put into a covered boiler of tinned 
 copper, which is immersed in a water-bath to prevent the liability of an excess 
 of heat ; there is then added to it two parts, (or two per cent.) by weight, of 
 sulphuric acid, of spec. grav. 1 .8, diluted with six parts of water. Boiling then 
 coagulates and precipitates the foreign matters, which may be separated by 
 skimming, straining, or filtering, while warm in the fluid state, and by allowing 
 them to settle in the cold state. The substance thus obtained is of firm con- 
 sistence, and forms ft valuable material in the making of candles that are now 
 extensively used. In the Quarterly Journal of Science, an interesting account 
 is given of the piney tallow tree of India, which we introduce in this work, as 
 the writer observes, that " it may be imported into this country at less than 
 one-fourth the price of wax ; and that although it does not possess all the 
 advantages of that substance, it is considerably superior to animal tallow." This 
 substance, he says, "is a concrete inflammable, partaking of the nature of wax 
 and oil, which, from its appearance, may not inaptly be termed a tallow. It is 
 in use only in the town of Mangalore (province of Canara), and is there em- 
 ployed medicinally as an external application for bruises and rheumatic pains ; 
 and likewise, when melted with the resin of the same tree, is used as a substi- 
 tute for tar in paying the bottoms of boats. The method of preparing this 
 material is simply to boil the fruit in water, when the tallow is soon found to 
 rise to the surface in a melting state, and on cooling forms a solid cake. Thus 
 obtained, the piney tallow (piney is the native name of the tree which produces 
 it) is generally white, sometimes yellow, greasy to the touch, with some degree 
 of waxiness, almost tasteless, and has a rather agreeable odour, somewhat 
 resembling common cerate. It melts at a temperature of 97j, and conse- 
 quently remains solid in the climate of India, in which respect it differs from 
 palm or cocoa-nut oil : wrapped up in folds of blotting paper, and submitted to 
 strong pressure, scarcely sufficient oil, or elain, as it is termed by M. Bracconot, 
 is expressed to imbue the inmost fold. Its tenacity and solidity are such, 
 that when cast in a rounded form of nine pounds' weight, the force of 
 two strong men was not sufficient to cut it asunder with a fine iron wire, 
 and even with a saw there was considerable difficulty in effecting a division. 
 When manufactured into candles, it comes with facility from the moulds, thus 
 differing from wax, which does not readily admit of being cast; it gives as 
 bright a light as tallow, and has the advantage of that material in being free 
 from unpleasant smell, and in not emitting a disagreeable odour when extin- 
 guished. It unites, in all proportions, with wax, spermaceti, and tallow ; and 
 forms compounds with the two former, intermediate in their melting points.
 
 808 CANDLES 
 
 according to the proportion in their ingredients, and better adapted to the 
 purpose of making candles than the pure and more fusible substance itself." 
 With the view of ascertaining the comparative combustibility of piney tallow 
 candles of the materials undermentioned were cast ; one mould was used for 
 all, and the wicks were composed of an equal number of threads. Having 
 been accurately weighed, they were burned for one hour in an apartment in 
 which the air was unagitated, and at a temperature of 55. 
 
 1 
 
 8 r; 
 
 Wax 
 
 height in 
 tins when 
 lighted. 
 
 840 
 770 
 760 
 777 
 811 
 792 
 763 
 812 
 
 Weight at 
 the end of 
 one hour. 
 
 719 
 631 
 604 
 625 
 703 
 681 
 640 
 702 
 
 Los. 
 
 121 
 139 
 156 
 152 
 108 
 111 
 123 
 110 
 
 Half wax, half piney tallow . 
 Spermaceti 
 Half sperm, half piney tallow . 
 Animal tallow 
 Half tallow, half piney tallow . 
 Cape wax . 
 
 Piney tallow 
 
 In the year 1830, a solid substance, resembling wax in most of its properties, 
 was obtained by M. Manicler, a French chemist (lately deceased), from 
 palm oil, an English patent for which was taken out in conjunction with 
 Mr. James Collier. The specification states that the process consists in pkcing 
 the palm oil, or butter of palm, in a metallic vessel or boiler, made of tinned 
 iron, and provided with a close cover and safety valve, upon the principle of 
 Papin's Digester ; water, in the proportion of about one-sixth part to the sub- 
 stance being added. The vessel being well closed, it is submitted to the action 
 of fire, so as to raise the steam to a pressure of two or three atmospheres, 
 which operation is to be continued for two hours. After the material has been 
 thus prepared, it is to be put into wrappers of linen or woven horse hair, or 
 both may be used, and submitted to powerful pressure: by this means the 
 elain, or fluid oil, is separated, and the stearin remains in the wrappers in a 
 solid state. Both these products are of a yellowish brown colour, and require 
 a process of bleaching to deprive them of it. We have seen candles made from 
 the stearin of palm oil, which were very little inferior to wax in illuminating 
 power ; they were cast in moulds, from which they readily separated by con- 
 traction when cold, in this respect possessing an advantage over wax. The 
 odour emitted by the substance is like palm soap, and is generally considered 
 rather agreeable than otherwise. It may, perhaps, be necessary to explain to the 
 general reader that the palm oil of commerce, and that to which the last 
 mentioned patent relates, is the produce of a tree growing abundantly in Africa 
 and South America, where, as well as in other parts of the world, it is obtained 
 from the outer shell or pulpy rind of the palm nut, while the kernel of the nut 
 contained within the inner indurated shell is thrown away as useless in the 
 preparation of oil or other oleaginous articles of commerce. These kernels, 
 however, have been recently found to abound in oleaginous matter of superior 
 quality, eminently calculated for the production of candles, besides generally for 
 those purposes for which fluid and'concrete oils are used. For the introduction 
 and application of this valuable (refuse) matter, the public is indebted to 
 Mr. John Demeur, who has recently taken out a patent for this interesting 
 discovery. The process described by the patentee in his specification is as 
 follows : " I first subject the kernels to a slight heating in an oven, or other 
 convenient apparatus, carrying the process only so far as to render the kernels 
 comparatively crisp and brittle when cold, which facilitates the subsequent 
 operation of grinding them to a paste in a mill. This paste I dilute with one- 
 fourth of its weight of boiling water, and then put it into bags (of the usual 
 kind employed in oil mills), wherein I subject it to mechanical pressure by the 
 ordinary mechanism employed for similar purposes, preferring, however, to 
 place the said bags containing the paste between heated metallic plates. By 
 the joint action of heat and pressure so applied, rhe oleaginous matter in
 
 CANDLES. 309 
 
 copiously exuded through the interstices of the bags, and is collected in suitable 
 receivers to undergo a purification. This purification I usually effect by remelting 
 the last mentioned product, and filtering it whilst in a fluid state ; and if it be 
 desired to purify or refine it still farther, or to remove the slight tinge of colour 
 it may yet possess, I again melt it in a metallic vessel coated with tin, and mix 
 therewith, by agitation or stirring, some very dilute sulphuric acid. By this 
 process the impurities are precipitated, or subside, by rest, to the bottom of the 
 vessel, and the oleaginous matter floats above the water, whence it is removed, 
 and subsequently consolidated, by evaporating the aqueous particles that were 
 commixed with it in the previous operation. The product resulting from the 
 last described process is a white and partially concrete matter, as it consists of 
 the two distinct substances, termed elain and stearin, the former of which is 
 fluid, and the latter solid, at our ordinary atmospheric temperature. To separate 
 these, they are subjected again in bags to mechanical pressure, without the aid 
 of artificial heat, if the weather be warm ; but if the air be under 65, the 
 application of a slight degree of heat will assist the operation, and cause a fine 
 fluid oil to be expressed, leaving the stearin in the bags of a similar consistence 
 to wax or spermaceti, and from whicli candles, scarcely inferior to those fabri- 
 cated of the last mentioned substances, and very superior to those of tallow, 
 are made. Having noticed the several important materials that have been 
 introduced into the modern manufacture of candles, we shall proceed to describe 
 some very recent and ingenious improvements in their construction and com- 
 position, which have been the subject of patents. 
 
 Dr. Bulkeley, of Richmond, in Surrey, took out a patent, dated January 26, 
 1830, for a plan of making tallow candle.s with an exterior casing of wax, and 
 also for effecting a saving in the material used for wicks, as well as to obviate 
 the necessity of snuffing. He uses a metallic mould, of the description generally 
 employed in the manufacture of mould candles, and fills it with melted wax. 
 Now, as the portion of the wax which is in contact with the interior surface of 
 the mould will become, by the conducting powers of the metal, first cooled or 
 set, as it is termed, the wax remaining fluid in the centre of the mould is poured 
 off, leaving within the mould a hollow cylinder of wax, which is afterwards 
 filled with tallow, or any other material which melts at a lower temperature 
 than wax. With respect to the wick, the patentee introduces a small thread up 
 the centre of the candle, for the purpose of constituting a guide for a short 
 cotton wick, which is plaited with a piece of straw within it, to receive the 
 thread. This short wick rests on the surface of the tallow, which it raises by 
 its capillary attraction for the supply of the combustion ; and as it descends 
 upon the thread as the tallow is melted, the top of it is never removed so far 
 from the tallow as to carbonize and require snuffing, which is the case with 
 wicks of the ordinary construction. The ordinary mode of manufacturing wax 
 candles, described in the early part of this article, has, we understand, been 
 resorted to, on account of the presumed difficulty of removing them from the 
 moulds, to which they firmly adhere, if cast therein. To obviate this difficulty, 
 Dr. Bulkeley places a block of box-wood, having a cavity in it to receive the 
 lower ends of the candle, in contact with the annular edge of the mould ; then 
 striking the block a few smart blows with a mallet, he detaches the candles from 
 the moulds. 
 
 A patent was also granted on the 4th February, 1830, to Mr. Charles T. 
 Miller, of Piccadilly, Westminster, for certain improvements in making candles. 
 These consist in the use of a small glass ring, which is placed over the wick, 
 and descends as the candle burns. The object in view is to prevent the candle 
 from wasting or guttering, which it effects by the glass ring conducting a greater 
 quantity of heat to the centre of the candle than that which reaches the exterior; 
 so that candles provided with this ring burn hollower in the centre than others, 
 and the exterior tallow, or composition of which the candles are made, stands 
 higher, and descends to the wick as soon as it is melted. The method of manu- 
 facturing the candles with the glass rings, as described by the patentee, consists 
 in putting the ring over the wick after it has been placed in the centre of the 
 mould, which, being inverted, as it is while being filled with the oleaginous 
 R R
 
 310 CANDLES. 
 
 matter, the ring descends until it reaches that part of the conical extremity of 
 the mould which is equal in diameter to the exterior of the ring, when it rests, 
 and becomes fixed in the candle. From an experiment which we have witnessed 
 with spermaceti candles, made by Mr. Miller according to the plan described, 
 they appear to answer the purpose intended. 
 
 Mr. John Murray, in a letter to the editor of Brewsler's Journal, states that 
 tallow candles may be materially improved by previously steeping the cotton 
 wicks in lime water, in which there has been dissolved a considerable quantity 
 of the nitrate of potass. The chlorate of potass is preferable to the nitrate, 
 but the great expense of the former salt precludes its employment on the large 
 scale. The wicks should be well dried before the tallow is put to them. By 
 this process, Mr. Murray states that the candles afford a purer flame and a more 
 brilliant light; the combustion of the wick is so complete as to render the 
 snuffing of them nearly superfluous ; and that they do not run or gutter. 
 
 With similar objects in view, Mr. William Palmer, of Wilson-street, Finsbury- 
 square, London, obtained a patent, dated 10th August, 1830. He applies to 
 about a tenth portion of the strands composing the wick, a quantity of bismuth 
 in a finely divided state, or else the nitrate, or any other similar preparation of 
 bismuth. The portion of wick thus prepared is to be surrounded with more 
 strands, till it becomes half the thickness required for the wick. It is then to 
 be cut into pieces, corresponding in length with twice that of the candle for 
 which it is intended. The wick is next twisted spirally round a thick wire in 
 contrary directions, a notch being made in the lower end of the wire to receive 
 the middle of the wick ; and the upper end is bent into a rectangular loop, to 
 retain the two ends of the wire together, and to facilitate its removal when the 
 making of the candle is completed, which is to be effected by either moulding 
 or dipping in the usual manner. The combustion of the wicks of candles 
 manufactured in this way, with a portion of bismuth in combination with the 
 wick made of the double spiral form, causes the two upper extremities of the 
 spiral, in the act of burning, to curl over to the opposite sides of the candles, 
 where they are accessible to an additional quantity of oxygen, and the com- 
 bustion is in consequence so intense as to leave no carbonaceous matter to 
 impede the light, or to require removal by snuffers. We shall close our 
 article on this subject by the translation of a French Brevet < Invention, granted 
 to M. Lorraine, of Paris, for the manufacture of perfumed imitative wax candles, 
 which we think is calculated to afford some useful practical hints to the British 
 tallow chandler. " Candles made of tallow only," observes M. Lorraine, " are 
 unctuous, opaque, greasy, little sonorous, especially in summer, liable to run or 
 gutter, and readily acquiring a rancid smell. These inconveniences are avoided 
 by putting fat, which has been melted and run into cakes, to ferment in a stove 
 where the heat is moderate ; this fat distils, and throws off an oily liquor, which 
 is removed with a piece of linen or a sponge. To free the grease from the 
 fleshy and fibrous parts by which it is accompanied, it is first chopped, and 
 after being washed in several waters, it is boiled with a given quantity of Roman 
 alum. The alum soon separates and destroys the heterogeneous parts, and we 
 obtain a pure clear fat, which will last a very long time. The fat chopped and 
 melted, is run into buckets full of water distilled from aromatic simples, such 
 as lavender, thyme, rosemary, &c. The fat and water are beaten together with 
 a spatula, to effect an union. After forty-eight hours the fat is separated from 
 the water, by means of a water bath ; the water alone is disengaged, and the 
 aromatic and odoriferous parts remain incorporated with the fat. To complete 
 the purification, the fat is liquefied and scummed, till no foreign substance nor 
 water remains : this will be known by the limpid state of the fat, which then 
 yields only a pure white scum. Still greater purity is obtained by a second 
 quantity of alum incorporated with the tallow. Before casting or running the 
 candles, a composition is made of half wax and half spermaceti, which serves to 
 prepare the wicks. This composition, harder and more cohesive than the tallow, 
 ,1-akes the candles less subject to gutter, to become firmer, last longer, and 
 require less snuffing. At the moment of removing the pure liquefied tallow from 
 the fire to cast the candles, a certain quantity of gum Arabic, dissolved in water,
 
 CANNON. 311 
 
 and united with a small quantity of wax and alum, is incorporated with it. The 
 whole are beaten together; and when the tallow has settled well, and cooled to a 
 certain temperature, it is poured into the moulds. By this preparation, in pro- 
 portion as the cooling takes place, the foreign substances proceed to, and fix at 
 the surface of the candles, forming a kind of covering pleasant to the touch, 
 like wax candles. This covering also prevents the candles from guttering, and 
 enables a person to handle and even rub them without greasing the fingers, and 
 without communicating any other smell than that of the aromatics entering into 
 the composition. The last operation for preventing the guttering of the candles 
 when burning, and giving more solidity to them, is to prepare some glover's size 
 very weak, and boiled with another quantity of gum and alum, and to pass a hair 
 pencil dipped in this size, all over the candles, and the next day after they may be 
 used. Candles prepared in this way are clear, transparent, sonorous, and last 
 longer than others ; they feel like bougies, and have the colour of pure wax." 
 CANNON. In military affairs, a long cylindrical tube for throwing projec- 
 tiles by the explosion of gunpowder, of such dimensions as to require to be 
 supported upon a carriage, with liberty to recoil after firing ; in which circum- 
 stance it differs from fire-arms of the smaller sort, as pistols, carabines, &c. 
 which may be fired from the hand or shoulder, and from an intermediate class, 
 as musketoons, duck guns, &c., which are fired from a rest. The date of the 
 invention, and the name of the inventor, are unknown : it is certain that 
 Edward employed cannon at the battle of Cressy, A. D. 1346 ; but records are 
 extant showing that they were known in France as early as the year 1338 ; and 
 Isaac Vossius asserts that they were used in China 1700 years ago. For some 
 time after the invention of cannons in Europe, they were formed of bars of 
 wrought iron, fitted together lengthways, or of sheets of iron, rolled up and 
 fastened together ; and in both cases hooped with iron rings. They were ex- 
 tremely heavy and cumbersome, and principally used for throwing large stones 
 to short distances, like the machines of the ancients which they succeeded. 
 These were gradually supplanted by brass cannon of much smaller calibre, and 
 which threw iron and leaden balls instead of stones. These guns were first cast 
 of a mixture of tin and copper, and from that circumstance called gun-inetal ; 
 but subsequently, as the use of cannon became more general, cast iron guns 
 were used on account of their being much cheaper ; and at present, guns for 
 the naval service, and for batteries, are generally cast of iron, whilst field 
 pieces and horse artillery, are mostly formed of brass. When the process of cast- 
 ing guns was first resorted to, the guns were cast with hollow chambers, which 
 were afterwards perfected by boring ; but the present practice is to cast them 
 solid, and form the cavity entirely by boring. In 1 828 a patent was granted to 
 Mr. Joshua Horton, for a method of forming cannon, and other large cylinders, 
 of wrought iron or steel, or mixtures of both. The process is as follows: A 
 number of bars a a are to be bound together by binding hoops b b, as shown in 
 Figs. 1 and 3, and placed in a furnace. When they have acquired a welding 
 heat, they are to be withdrawn and placed on a maundrel, and hammered 
 together by heavy hammers, and if necessary, heated again until they are per- 
 fectly united ; the bars should be wedge shaped, or wider on the outside than 
 on the side which is to form the interior of the cylinder; but any of the forms 
 shown in Fig. 1 will do. If the cylinder is intended for a cannon, the bars 
 should be thickest at the breach end; and if deemed necessary, the interior may 
 be formed of steel, by placing a layer of steel bars within the iron bars. The 
 breach-piece may either be formed in one piece with the rest, or it may be forged 
 separately and screwed into the gun, as shown in Fig. 4. The trunnions 
 may also be formed with the gun ; but the patentee recommends that they 
 should be formed in a separate ring, and attached to the gun either by an ex- 
 ternal screw cut on the gun, and fitting into an internal screw in the ring, as 
 shown in Fig. 4, or by keys, as in Fig. 2. These separate trunnions the 
 patentee recommends as possessing great advantages, from the facility with 
 which the gun may be rendered useless by removing the trunnions, when 
 necessary to abandon it to the enemy. After the welding is completed, the 
 piece is to be finished by turning and boring. At the first mention of thia
 
 312 
 
 CAKNuN. 
 
 method of constructing guns, it seems similar to that followed at the first intro- 
 duction ; but the earlier cannon formed of iron bars were merely hooped 
 together, and not welded, as may be seen in several which are preserved at the 
 Tower of London : nevertheless, it is certain that cannon of smaller calibre, 
 
 Fig. 2 
 
 Fig. 1. 
 
 Fig. 3, 
 
 forged of iron, were very early known. In proof of this we may cite the following 
 curious fact : In the year 1827, a fisherman whilst fishing in a boat eight miles 
 to the eastward of Calais, brought up in his net from the bottom of the sea a 
 small piece of ordnance of a very singular construction, resembling exactly the 
 representations of cannon in three ancient historical paintings in the dining 
 parlour at Cowdry, in Sussex, one of the seats of the late Lord Viscount Montagu. 
 The first painting represents the march of King Henry VIII. from Calais towards 
 Boulogne ; the second, the encampment of the English forces at Marqueson ; and 
 the third, the taking of Boulogne, in 1544. The resemblance will be instantly 
 perceived by referring to the sketch on the following page ; Fig. 1 representing 
 the cannon as seen in the paintings, and the other figures exhibiting with all its 
 details the cannon taken by the fisherman. Fig. 1 represents a carriage sup- 
 porting two pieces of ordnance, which are nearly covered by a kind of hood in 
 form somewhat like half a cone, the broadest end being next to the shafts, and 
 the smaller end being constructed with sharp points ; the hood probably being 
 intended as a shield to protect tire artillery men from the fire and arrows of the 
 enemy, and the points as some defence against a charge. Fig. 2 is a horizontal 
 view of the new found gun ; Fig. 3 a longitudinal section of the same ; and 
 Fig. 4 a bird's-eye view of it ; I representing the tail bit, also of iron, forming 
 part of the cannon, and serving to adjust it with ease in taking aim. The 
 gun when first brought up from the bottom of the sea was covered with a 
 sort of petrified rust, about two inches thick, which being removed, the diameter 
 of the gun at the middle was found to be 3 inches, its bore for the passage of 
 the bullet 1 inch, and the length, including the tail-piece, 5 feet 11 inches, and 
 its weight 64 Ibs. Upon examination it was found to be still charged, having 
 m it powder and a leaden bullet; from which circumstance we may conclude 
 that cast iron balls were not known at the time when the cannon had been
 
 CANNON. 313 
 
 charged. The bullet had a covering of tow, and weighed 9 ounces ; its diameter 
 1.4 inch. A A and C in Figs. 2, 3, and 4, are three different views of a shifting 
 breech, which was detached and taken out of the after part of the gun when 
 required to be loaded with powder ; this being charged, and the cartridge pro- 
 perly secured by driving down an oaken plug over it, the bullst was put into 
 the gun at the breech, and the shifting breech replaced in its original position, 
 and firmly secured by an iron wedge D D D, Figs. 2, 3, 4, driven in behind it 
 horizontally across the gun. The shifting breech is shewn separately in Fig. 5, 
 
 
 and the wedge in Fig.6. E, Fig. 7, is the figure of the after part of the barrel 
 of the gun, and F is the other half within the dotted circumference, this being 
 cut off so as to take out and replace the shifting breech with facility, g g, Figs. 2 
 and 3, show the leaden bullet in front of the shifting breech. It is a remarkable 
 fact that the shifting breech appertaining to this cannon is similar in principle 
 to the patent shifting breech on some fowling-pieces of modern times. 
 
 We shall conclude this subject with a description of the apparatus employed for 
 boring cannon. Formerly the cannons were suspended in sliding frames vertically 
 over the boring tool, and the tool was made to revolve, the sannon descending
 
 314- 
 
 CAOUTCHOUC. 
 
 gradually as the tool bored the interior; but in the present method of boring, the 
 gun is supported horizontally in a lathe, and revolves, the cutter advancing 
 in a right line. An apparatus of this description is represented in the accom- 
 panying figure. The cannon a is accurately centered in the chuck 6, and the 
 collar c, which may be set at any part of the bed d of the lathe to suit the 
 
 length of the gun ; e is the boring tool, supported by bearings in the frame /, 
 and connected to the rack g. The rack is made to advance in a chase mor- 
 tice h, by means of a pinion k actuated by a weighted lever I. The cannon is 
 caused to revolve by a band passing over the rigger m, and the operations of 
 boring the interior, and turning the exterior, are carried on at the same 
 time. 
 
 CANOE. A sort of boat or vessel used by the natives of various uncivilized 
 countries. They are generally composed of the trunk of a tree hollowed out, 
 and are usually impelled by paddles instead of oars. The most singular canoes 
 are those of the Ladrone Islands, which are adapted to sail with either end 
 foremost, so as always to expose the same side to the wind. From their great 
 velocity when sailing, they are commonly called the " Flying Boats," the 
 Spaniards declaring that they have been known to go 35 miles per hour. 
 
 CANTHARIDES. Insects vulgarly called Spanish flies : they are chiefly 
 used on account of their vesicating or blistering properties. The insect is about 
 two-thirds of an inch in length and one-fourth in breadth, oblong, and of a 
 gold shining colour, with soft wing sheaths, marked with three longitudinal stripes, 
 and covering brown membranous wings. The genuine cantharides are sometimes 
 mixed with other insects of a square form, with black feet, which possess no 
 vesicating property. 
 
 CANTILEVERS. In architecture, pieces of timber projecting horizontally, 
 used to support the eves of a house, a balcony, &c. 
 
 CANVASS. A cloth of hemp, unbleached, and of various degrees of fine- 
 ness ; used principally to form the sails of ships, but also by painters, and for a 
 variety of other purposes. 
 
 CAOUTCHOUC. A soft, dense, elastic, resinous substance, usually called 
 India rubber, but sometimes very improperly elastic gum. It is obtained from 
 the milky juice of several plants, the chief of which are the Jatropha elastica, 
 and Urceola elastica. The juice, which is obtained by incision, is received in 
 successive coatings on pieces of clay, and dried by the sun, or a fire made from 
 dried leaves : as fast as one layer is dried, another is added, until it obtains the 
 required thickness, when the clay mould is broken, and the tough leather-like 
 substance taken out. The wonderful elasticity of this substance, and its resist- 
 ance to water, has of late years brought it into extensive use for making water 
 proof garments, besides many other purposes. Its solvents are ether, volatile 
 oils, and petroleum. The ether, however, must be washed with water repeat- 
 edly, when it dissolves it completely. Pelletier recommends the caoutchouc to 
 be boiled in water for an hour, then to be cut into thin shreds, then boiled again, 
 and afterwards put into rectified sulphuric ether in a vessel closely stopped. 
 Berneard considers the nitrous ether as preferable. When this solution is 
 spread upon any object, the ether quickly evaporates, and leaves the surface 
 perfectly covered with the elastic resin. A solution of caoutchouc in five times 
 its weight of oil of turpentine, and this solution dissolved in eight times Us 
 weight of drying linseed oil, is said to form the varnish of air balloons.
 
 CAPSTAN. 315 
 
 Caoutchouc may be formed into various articles without undergoing the process 
 of solution. If it be cut into a uniform slip of a proper thickness, and wound 
 spirally round a glass or metal rod, so that the edges shall be in close contact, 
 and in this state be boiled for some time, the edges will adhere so as to form a 
 tube. Pieces may be firmly united by merely heating their e 
 ;her. Within these few years Messrs. Hancock 
 
 them together. Within these few years Messrs. Hancock and Mackintosh 
 have obtained several patents for various modes of applying this valuable sub- 
 stance, which are daily rising into notice. The patent caoutchouc pipes are 
 formed of alternate layers of solid or dissolved caoutchouc and canvass, or other 
 suitable medium, and by pressure united into very tough pipes of any required 
 bore or strength, without any stitch or seam, the weakest of which it is said is 
 capable of bearing a pressure of 600 Ibs. per square inch. 
 
 CAPILLARY TUBES, in Physics, are very small pipes, whose canals or 
 bores are exceedingly narrow, their usual diameter not exceeding one-twentieth 
 or one-thirtieth of an inch, and in some cases being made so small as to be 
 scarcely perceptible. One of the most singular phenomena of these tubes is, 
 that if they are left open at both ends, and one end immersed in water, the 
 water will rise in the tube to a considerable height above the surface of that 
 into which they are immersed, the height being inversely as the diameters of 
 the tubes. Different fluids, however, attain different heights, and quicksilver 
 does not rise, but, on the contrary, stands higher outside the tube than within. 
 Various hypotheses have been invented to account for this ascent of fluids : at 
 the present day it is attributed to a species of attraction, supposed to exist 
 between the fluid and the tubes, and which is hence denominated capillary 
 attraction. 
 
 CAPSTAN. A machine employed in large vessels, principally for " heaving 
 up or weighing " the anchor. It consists of a drum or barrel, revolving upon 
 an upright spindle, and having holes cut in the upper part or drum head, to 
 receive the ends of a series of horizontal levers, named capstan bars. The cable, 
 or, in very large vessels, a smaller rope, called the messenger, attached to the 
 cable, is wound two or three times round the barrel, and as the capstan is turned 
 round by a portion of the crew distributed at the capstan bars, another portion 
 of them take in the slack of the cable or messenger, as it is unwound off the 
 barrel of the capstan. The capstan is superior to the windlass in point of 
 expedition, owing to the circumstance of the latter requiring the levers to be 
 shifted into fresh holes four times in each revolution ; and more men can also 
 be employed at the capstan bars than at the hand-spikes of a windlass ; but the 
 men exert their strength more effectually at the windlass than at the capstan, 
 since in the latter case they are employed to draw horizontally, when they exert 
 a force of about 35 Ibs. only, but at the windlass they may apply their whole 
 weight at the extremity of the lever, and the average weight of a man is about 
 150, or more than four times his power of traction. In Hawkes' Patent Capstan, 
 which we are about to describe, is combined the advantageous action of the wind- 
 lass, with the continuous movement of the capstan ; and the power or velocity 
 may be varied according to circumstances. The engraving on the next page repre- 
 sents the patent capstan complete for one deck, a is the drum head of cast iron, 
 with holes for the insertion of the capstan bai-s in the ordinary way, if from any 
 cause that mode of turning the capstan should be preferred ; b is the paul head, 
 round the periphery of which are ranged ten pauls, five of which are in opera- 
 tion at a time, as that shown at d ; the other five are kept turned up in readi- 
 ness for use when the motion of the capstan is reversed. Each paul has two 
 clips, which take into two teeth at the same time at every half inch of the 
 revolution. The inner circle of teeth is for one set of pauls, and the outer 
 circle for the other set, the notches being in contrary directions ; both circles 
 are inclosed within the paul-rim /. The barrel is composed of a number of 
 projecting ribs named whelps, having a projection c in the middle, which divides 
 the barrel into two parts ; the upper portion is of a smaller diameter than the 
 lower, so that by shifting the cable from the lower to the upper part of the 
 barrel, an increase of power is obtained. In the figure the capstan is repre- 
 sented divided into six sections; but the number of these sections may be
 
 31fl 
 
 CAPSTAN. 
 
 varied according to the size and weight of the capstan ; the divisions are made 
 
 vertically through the whole length of the capstan, dividing also the whelps, 
 
 the plates of which being strongly bolted together, unite it into one firm and 
 
 compact body, and admit of its being easily disunited and removed, h is the 
 
 central shaft of wrought iron, made square, except at the bearings, which are 
 
 properly turned. Ill are three iron standards for supporting the gearing, 
 
 which gives motion to the capstan, and may be worked either by means of a 
 
 winc 
 
 bars, suppor 
 
 n n fixed on the same axle as the crank ; 
 
 , 
 
 ch or crank, as shown by the dotted lines at m, or by means of capstan 
 s, suorted horizontally in holes at the circumference of two vertical wheels 
 
 the circumference of these wheels 
 being scored in a proper manner for allowing the bars to be dropped in and 
 secured by pins, and to be quickly removed at pleasure. The bars when secured 
 
 in the rims of the wheels nn, form a kind of drum or reel, the men on one side 
 
 bears also two pinions, one of which is shown in gear with the smallest circle 
 of a double cogged wheel ; and on the same shaft as the latter is placed a 
 pinion, which takes into the circle of cogs fixed on the upper surface of the 
 paul-head, and causes it to revolve : if the small pinion is brought into gear 
 with the large wheel, a great addition of power is gained ; and according a? 
 the one or the other set of the wheels, and as the larger or smaller of the 
 barrels of the capstan, are employed, the power admits of several variations to 
 uit different circumstances
 
 CARDS. 317 
 
 CARABINE, or CARBINE. A fire-arm, something like a small musket ; it 
 is usually borne by cavalry soldiers, slung by a belt over the left shoulder. 
 
 CARAWAY. A plant much cultivated, particularly in Essex, for its seed, 
 which is greatly esteemed for its agreeable flavour, pungent warmth, and medi- 
 cinal properties. By distillation it affords an odoriferous essential oil, which is 
 much used in white soap, and therewith constitutes the article termed Windsor 
 soap. 
 
 CARBON. The name given in the modern chemical nomenclature to a 
 simple combustible, which constitutes a large portion of all animal and vegetable 
 substances, and which is found in the greatest state of purity in the diamond, 
 which is composed solely of it. Carbon unites with all the simple combustibles, 
 and with azote, forming a series of important compounds. From its affinity for 
 oxygen, it is employed for disoxygenating metallic oxides, and restoring their 
 bases to a metallic state. With iron it forms steel and plumbago ; and with 
 copper it likewise forms a carburet In the state in which it i commonly ob- 
 tained it is termed charcoal, which see. 
 
 CARBONATES. Compounds of carbonic acid with salifiable bases com- 
 posed either of one prime of acid and one of base, or one of acid to two of 
 base. The former set of compounds are termed carbonates, and the latter bi- 
 carbonates. 
 
 CARBONIC ACID. An acid composed of oxygen and carbon. It abounds 
 in great quantities in nature, and appears to be produced in a variety of cir- 
 cumstances. It composes forty-four hundredth^ of the weight of limestone, 
 marble, and other natural specimens of calcareous earth, from which it may be 
 extricated by the simple application of heat, or by the superior affinity of some 
 other acid, most acids having a stronger action on bodies than this. It is com- 
 posed of 72 parts of oxygen, and 28 of carbon, and its spec. grav. is 1-5236, 
 that of atmospheric air being I'OOOO. See AERATED WATERS. 
 
 CARBONIC OXIDE. A gaseous compound of oxygen and carbon, con- 
 sisting by weight of 75 of the former, and 100 of the latter. Its spec. grav. is 
 0.9569. Carbonic oxide may be procured by subjecting to a strong heat in a 
 retort or gun-barrel, a mixture of an earthy carbonate and metallic filings ; the 
 most convenient mixture is equal parts of dry chalk, and iron or zinc filings ; it 
 is given out also in large quantities from brick kilns, and may be seen burning 
 with a dark blue flame. It is, when respired, fatal to animal life. 
 
 CARBUNCLE. An elegant gem whose colour is deep red, with an ad- 
 mixture of scarlet It is usually found pure and faultless, and is of the same 
 degree of hardness as sapphire. It is naturally of an angular figure, and is 
 found adhering by its base to a heavy and ferruginous stone of the emery 
 kind. It bears the fire unaltered ; is found only in the East Indies, and there 
 but rarely. 
 
 CARBURETS. Combinations of carbon with any of the simple substances. 
 
 CARDS. In the manufactures of cotton and wool, an instrument used for 
 preparing those substances for being spun into thread, by strengthening the 
 fibres, and rendering them parallel to each other. They are a species of brush, 
 composed of wires stuck through strips of leather, and not standing erect, but 
 inclined to the surface of the leather, and are used by filling the teeth of one 
 card with the cotton or wool, and drawing another card along in a direction 
 against the inclination of the teeth, by which means the fibres are drawn out 
 in a parallel direction, and transferred from the one card to the other. Carding 
 was originally performed by hand with sheets of cards nailed upon thin boards, 
 which were drawn against each other. Stock cards were subsequently intro- 
 duced : in these one card was nailed to an inclined post or bend, and a hand 
 card drawn over it ; but at present the cards are generally arranged upon cylin- 
 ders, which revolve either against other card cylinders, or against fixed cards. 
 Cards are fastened upon the cylinders either in parallel strips in the line of the 
 axis, or they form a continuous spiral band covering the entire surface of the 
 cylinder. From the immense number of cards required in cotton mills, the 
 manufacture is one of great extent and importance, and several very curious 
 machines have been invented for facilitating the processes, though they have
 
 328 CARPENTRY. 
 
 not yet come into common use. In general the leather is pierced by machinery 
 at the manufacturers', who send it out to the cottagers, together with the wire, 
 which they cut and bend into form, and afterwards insert in the holes of the 
 leather. The workman first takes a skein or bundle of wire, consisting of 30 
 or 40 wires, and placing them against a gauge, cuts the whole at one operation to 
 the same length, by means of a strong pair of shears. The wires thus cut are then 
 placed in another gauge, and a piece of steel, of the same width as the two 
 legs are to be asunder, is then pressed across the middle of them, and the ends 
 of the wires, first on one side, and then the other, are turned up against the 
 
 sides of the bridge, forming the wire into a staple like this | | ; they are then 
 
 given the knee bend, which brings them into this shape (_ t by an ingenious 
 machine kept in motion by a weight, like a roasting jack, after which they are 
 inserted in the leathers by women or children. 
 
 CARMINE. A very bright crimson pigment, obtained by precipitating the 
 colouring matter of cochineal. The preparation is as follows : Take 4 ounces 
 of cochineal, finely pulverized, which pour into 4 quarts of rain or distilled 
 water, boiled previously in a pewter kettle, and boil the whole for six minutes, 
 adding, during the boiling, 2 drachms of pulverized crystals of (artar. Eight 
 scruples of Roman alum, in powder, must then be added, and the whole be kept 
 on the fire one minute longer. As soon as the gross powder has subsided, and 
 the decoction become clear, decant it into large cylindrical glasses covered over, 
 and keep it undisturbed till a fine powder is observed to have settled at the 
 bottom. Then pour off the liquor from this powder, which is to be gradually 
 dried. From the liquor still coloured, the rest of the colouring matter may be 
 separated by the solution of tin, when it yields a carmine little inferior to the 
 former. 
 
 CARPENTRY is the art of cutting out, framing, and joining large pieces of 
 wood to be used in building. The only difference between Carpentry and 
 Joinery is, that whilst the former includes the larger and rougher description of 
 work, which is essential to the construction and stability of an edifice, the 
 .atter term comprehends the exterior finishing and ornamental wood-work. To 
 enter into a detailed account of the numerous tools used in Carpentry, and the 
 processes of forming, by their application, the almost illimitable variety of 
 matters that are comprehended in constructive carpentry, would of course 
 require a volume to itself; and as the subject is foreign to the leading objects of 
 this work, we shall under this head confine ourselves to some general obser- 
 vations of a practical nature, alike useful to the engineer as well as the car- 
 penter. With regard to the tenacity or strength of wood, it has been found by 
 Muschenbroek and other eminent experimentalists, first, that the wood which 
 surrounds immediately the pith or heart of the tree is the weakest, and that this 
 weakness is greater as the tree is older. It is of importance that this fact be 
 known, as a common notion exists of a contrary nature. Secondly, the fibres 
 next to the bark, commonly called the white or blea, are also weaker than the 
 rest ; and the wood gradually increases in strength as it recedes from the centre 
 to the blea. Thirdly, the wood is stronger in the middle of the trunk than 
 at the springing of the branches, or at the root ; and the wood forming a branch 
 is weaker than that of the trunk. Fourthly, the wood on the northern sides of 
 all trees that grow in Europe is the weakest, while that on the south-eastern 
 side is the strongest ; this difference is most remarkable in hedge-row trees, and 
 such as grow singly. The heart of a tree never lies in its centre, but always 
 towards its northern side, and the annual coats of wood are thinner on that 
 side. In conformity with this, it is a general opinion of carpenters that timber 
 is stronger in proportion to the thickness of its annual plates. The trachea, or 
 air vessels, being the same in diameter and number of rows in trees of the same 
 species, occasion the visible separation between the annual plates; for which 
 reason, when these are thicker, they contain a greater portion of the simple 
 ligneous fibres. Fifthly, all woods are most tenacious whilst green, but after 
 the trees are felled, that tenacity is considerably diminished by their drying. By 
 the experiments of Muschenbroek, it appears that the absolute strengths of a 
 square inch of the following different kin<te of wood are as stated
 
 CARPENTRY. 
 
 319 
 
 Locust . . . . . 20,100 
 
 Jujeb 18,500 
 
 Beech and Oak . . 17,300 
 
 Orange . . . . 15,500 
 
 Alder 13,900 
 
 Elm 13,200 
 
 Mulberry and Willow 12,500 
 
 Ash 12,000 
 
 Plum 11,800 
 
 Elder 10,000 
 
 Pomegranate . . 9,750 
 
 Lemon . . . 9,250 
 
 Tamarind . . 8,750 
 
 Fir . . . . 8,330 
 
 Walnut . . 8,130 
 
 Pitch pine . . 7,650 
 
 Quince 6,750 
 
 Cypress .... 6,000 
 
 Poplar ..... 5,500 
 
 Cedar 4,800 
 
 The woods mentioned were all formed into slips of uniform dimensions, and 
 as much cut away from each, as to form a parallelepiped of one-fifth of an inch, 
 that is, one-twenty-fifth of a square inch in section ; and the weights which were 
 required to tear these asunder, formed the data of the above calculations. 
 Muschenbroek gives a very minute detail of his experiments on the ash and 
 walnut, in which he states the weights required to tear asunder slips taken from 
 the four sides of these trees, and on each side in a regular progression from the 
 centre to the circumference. The numbers in the foregoing, corresponding 
 with these two woods, may be considered, therefore, as the average of more 
 than fifty trials of each. He mentions, also, that all the other numbers were 
 calculated with the same care. For these reasons some confidence may be 
 placed in the results, though they carry the degree of tenacity considerably 
 higher than those enumerated by some other writers. Pitot and Parent state, 
 that a weight of 60 Ibs. will just tear asunder a square line of sound oak, but 
 that it will bear 50 Ibs. with safety. This gives 8640 for the greatest strength 
 of a square inch, or rather less than one-half of Muschenbroek's estimate ; 
 but the latter is, we think, the most entitled to confidence, as the experiments 
 were made upon greater masses of the material. It should, however, be 
 observed, that two-thirds of the actual weight which may be sustained by a 
 body, will greatly impair the strength after a considerable time, and that one- 
 half the absolute tenacity indicated by experiment, should be the utmost that an 
 engineer should calculate upon in his constructions. Woods of the same 
 denomination often differ greatly in their tenacity ; those with a very straight 
 fibre suffer less injury from a load that is insufficient to break them immediately. 
 Mr. Emerson mentions the following as the loads which may be safely suspended 
 to an inch square of the several bodies hereafter enumerated ; but the term 
 safely can hardly apply to the four first-named bodies. 
 
 Red fir, holly, elder, plane, 
 
 and crab 5,000 
 
 Cherry and hazel . . . 4,760 
 Alder, asp, birch, and 
 
 willow 4,290 
 
 Lead 450 
 
 Freestone 914 
 
 Iron 76,400 
 
 Brass 35,600 
 
 Hempen rope .... 1 9,600 
 
 Ivory 15,700 
 
 Oak, box, and yew . . 7,850 
 
 Elm, ash, and beech . . 6,070 
 
 Walnut and plum . . . 5,360 
 
 The same ingenious author has laid down as a practical rule, that a cylinder 
 of one inch diameter will carry, when loaded to one-fourth of its absolute 
 strength, as follows : iron, 135 cwt. ; good rope, 22 cwt. ; oak, 14 cwt. ; and fir, 
 9 cwt. Parent has shown that the force required to crush a body is nearly 
 equal to that which will tear it asunder. This may be an approximation to the 
 truth as respects woods, but it will not apply to any other bodies. Glass, for 
 instance, will carry a hundred times more on it than oak in this way, but will 
 not bear suspended above four or five times as much. Oak will suspend a great 
 deal more than fir, but fir will carry twice as much as a pillar. Some woods 
 which are very soft, and consequently yield to pressure, possess very strong 
 fibres, and will resist a longitudinal strain. The softness of texture is chiefly 
 owing to the crooked nature of their fibres, and to the existence of considerable 
 vacuities between each fibre, so that they are more easily bent in a lateral 
 direction and crushed. In all cases where the fibres lie oblique to the strain,
 
 320 CARRIAGES. 
 
 the strength is considerably diminished, which may be ascribed to the circum- 
 stance, that the parts in such case slide on each other, and the connecting force 
 of the cementing matter is for that reason easier overcome. The strain which most 
 commonly acts on materials of any nature, is that which tends to break them in a 
 transverse direction. For the results derived from experiment in strains of this 
 nature, we must refer the reader to the article STRENGTH OF MATERIALS ; but 
 the complete investigation of the resistance of materials, according to the 
 direction and situation of the forces applied, would require a volume. The reader 
 who wishes for full information on this subject, cannot do better than consult 
 Mr. Barlow's valuable Essay on the Strength and Stress of Timber. Some 
 excellent practical rules on this important subject will, however, be found in 
 The New Practical Builder, by Nicholson, and in the works of Banks, Emerson, 
 and Roberson. 
 
 CARPET is a sort of stuff wrought with the needle, or on a loom, and 
 forms the ordinary furniture of a house, being commonly laid upon the floor. 
 The Persian and Turkey carpets have hitherto been in the greatest esteem, but 
 some of the manufacturers of France and Great Britain are making rapid 
 advances in imitating them, to which they are, in some respects, superior. A 
 splendid example of this fine spirit of rivalry amongst our own countrjmen is 
 now exhibiting at the Museum of National Manufactures and of the Mechanical 
 Arts, in Leicester Square, London. The carpet measures 8 yards by 6, and is 
 called Scoto-Persian by the manufacturers, Messrs. Deans, of Stewarton, in 
 Ayrshire. In the usual mode of weaving carpets, the design or pattern is traced 
 in its proper colours on cartoons, tied before the workman, who looks at them 
 every moment, because every stitch is marked upon them as it is to be in his 
 work. By this means he always knows what colours and shades he is to use, 
 and how many stitches of the same colour. In this he is assisted by squares, 
 into which the whole design is divided ; each square is divided into ten vertical 
 lines, corresponding with the parcels of ten threads of the warp ; and besides, 
 each square is ruled with ten horizontal lines crossing the vertical lines at right 
 angles. The workman having placed his spindles of thread near him, begins 
 to work on the first horizontal line of one of the squares. The lines marked 
 in the cartoon are not traced on the warp, because an iron wire, which is longer 
 than the width of a parcel of ten threads, supplies the place of a cross line. 
 This wire is managed by a crook at one end, at the workman's right hand ; 
 towards the other end it is flatted into a sort of knife with a back and edge, and 
 grows wider at the point. The weaver fixes his wire horizontally on the warp, 
 by twisting some turns of a suitable thread of the woof around it, which he 
 passes forward and backward behind a fore thread of the warp, and then behind 
 the opposite thread, drawing them in their turn by their leashes. Afterwards, 
 he brings the woof-thread round the wire in order to begin again to thrust it 
 into the warp. He continues in this manner to cover the iron rod or wire, and 
 to fill up a line to the tenth thread of the warp. He is at liberty either to stop 
 here, or to go on with the same cross line in the next division, according as he 
 passes the thread of the woof round the iron wire, and into the warp, the threads 
 of which he causes to cross one another at every instant ; when he comes to 
 the end of the line he takes care to strike in the woof he has used. This row 
 of stitches is again closed and levelled, and in the same manner the weaver 
 proceeds ; then with his left hand he lays a strong pair of shears along the 
 finished line, cuts off the loose hairs, and thus forms a row of tufts perfectly 
 even, which, together with those before and after it, form the shag. Thus the 
 workman follows, stitch for stitch and colour for colour, the plan of his pattern, 
 which he is attempting to imitate ; and he paints magnificently without having 
 he least notion of painting or drawing. 
 
 CARRIAGE. A vehicle for the transport of persons and goods by land. 
 Although the varieties of carriages are very great, yet they may be ranged 
 under two heads, viz. sledges, or carriages without wheels, and wheeled carriages. 
 The earliest carriages were doubtless of the first class, or without wheels ; and 
 although they are now very generally superseded by carriages mounted upon 
 wheels, and indeed have become nearly obsolete in this country yet they are
 
 CARRIAGES. 321 
 
 till extensively used in the more northern parts of Europe, where the ground 
 is for a considerable portion of the year covered with snow, and the rivers frozen 
 over so as to allow carriages to travel upon them. In these cases sledges are 
 found superior to wheel carriages, as the friction upon the surface of the snow 
 or ice is small, and as, from the greater extent of bearing surface, they do not sink 
 so deep as wheel carriages, in which the whole weight presses upon two, or at 
 most, four points. The motion is also found to be much more easy, as from 
 their length of bearing they do not rise and fall with every slight inequality in 
 the roads, in the manner of wheel carriages. But for general purposes, and on 
 roads composed of rough materials, which offer great resistance to bodies sliding 
 over them, it is found highly advantageous to place the carriages upon wheels, 
 as by this means the sliding motion is converted into a rolling motion, and the 
 rubbing surfaces, when the friction takes place, are reduced in the proportion of 
 the diameter of the wheel to that of its axle, and the friction is stifl further 
 reduced by the rubbing surfaces being polished, and admitting of lubrication, 
 which tends materially to diminish friction. The friction being diminished in 
 proportion to the difference between the diameters of the wheels and the axles, 
 it is evidently advantageous to employ wheels of large diameter, which are also 
 beneficial in another respect, as they experience less resistance from the in- 
 equalities of the surface over which they roll, as the leverage to which the 
 power of the horse is applied, is as the diameter of the wheel ; and as any 
 obstacle on a road will sooner come in contact with a large wheel than with 
 a small one, in consequence of the curvature of the former being flatter than 
 that of the latter, so the power by which the wheel is drawn over the obstacle 
 is exerted through a greater space with the large than with the small one. 
 We shall endeavour further to explain tlu's by a little diagram. Let the 
 circle a represent a small wheel, 
 whose axle is at b, and c a stone 
 lying in the road, over which the 
 wheel is to pass ; and the dotted 
 circle to represent a large wheel, 
 whose centre is at /; now the 
 obstacle Jc is already in contact with 
 the large wheel, but the small wheel 
 has no* yet arrived at it : the horse 
 would therefore move through a 
 greater space in bringing the centre 
 of the large wheel perpendicularly 
 over the obstacle, than in bringing 
 the centre of the small wheel over the 
 object after it had come in contact 
 with the periphery ; thus the horse 
 exerts more power, or what is the same, exerts the same power through a 
 greater space with the large wheel than with the small one. And again, as 
 the angle k fh, at which the obstacle Jc interrupts the large wheel, is the same 
 as the angle c b d, at which the obstacle c interrupts the small wheel, the same 
 force which will draw the small wheel over the obstacle c, will, by the increased 
 leverage, draw the large wheel over the obstacle k. The advantages above attri- 
 buted to large wheels over small ones are not merely theoretical, but have been 
 confirmed in a variety of instances in practice. We therefore insert the diagram 
 on the following page, exhibiting a method of applying hind wheels of larger 
 diameter than ordinary to waggons, without carrying the floor higher than usual. 
 a a represents the hind wheels ; b b the bended axletree, of a crank form, passing 
 under the bed of the carriage, which lies between the two extremities of the 
 axletree, and permits the floor of the carriage to lie close to the upper side of the 
 axletree, the floor being usually as much above the latter as the thickness or 
 depth of the bed. The modes by which carriages are or have been propelled are 
 various as the force of animals, of wind, of men, exerted upon machinery con- 
 tained within the carriage, and that of steam. Carriages propelled by wind 
 acting upon sails are not common for land travelling, although such have been
 
 322 
 
 CARRIAGES. 
 
 constructed ; but in some parts of Holland, boats mounted upon long skids 
 are frequently employed for sailing o-er the ice, and have sometimes been known 
 
 to go at the rate of eighteen miles per hour. In 1826 a patent was obtained 
 by Col. Viney and G. Pocock, for a carnage, to be impelled by the force of the 
 wind acting upon one or more kites attached to the carriage, which they de- 
 nominated the " Charvolant." It is represented in Fig. 2 in the engraving on the 
 following page. The kite, a, Fig. 1, is jointed in the middle, that it may be folded 
 up, and carried or stowed away with greater facility, b b b b are four cords for 
 regulating the position of the kite, and to assist the steerage ; they are brought 
 together by passing through the dead eye c, whence they proceed to the carriage, 
 where they are regulated to the proper lengths by the persons therein. By 
 shortening the cords on the right-hand "side of the kite, the car may be turned 
 to the right, and by shortening the left-hand cords it will be turned to the left. 
 But the charvolant, by the cross handle eand stem ef, which acts on the axis 
 of the fore wheels by means of an endless band or cord passing about a pulley 
 / fixed on the lower end of the stem ef, and the pulley g fixed on to the bed of 
 the axletree of the fore v/heels. The machine is stopped, or its motion re- 
 tarded by the drag k, which is attached to the perch by a spring to keep it 
 off the ground till it is required to retard the motion or to stop the carriage, 
 when the fluke end is pressed into the earth by the lever h acting on the 
 connecting piece i. The patentees several times exhibited a carriage similar 
 to the above, in Hyde Park, and, we believe, performed a journey from South- 
 ampton to London with it, but we do not recollect the particulars. The scheme 
 is not altogether original. Dr. Franklin employed kites to assist swimmers, 
 and was of opinion thai with such aid a man might swim across the Channel 
 from Dover to Calais. Attempts have also been made before the present to 
 move both boats and cars by the same means ; but we believe the present is 
 the first attempt to trim or "regulate the position of the kite according to the 
 direction in which the carriage is to move.
 
 CARRIAGES. 
 
 323 
 
 In no class of carriages does this country so much excel all other nations as 
 in the stage coaches, which, for beauty, compactness, lightness, strength, and 
 easy draught, are far superior to the public vehicles of any other country. In 
 a nation so eminently commercial, where dispatch and punctuality are of the 
 first necessity in conducting all transactions, every thing which tends to 
 advance the means of communication becomes an object of consideration ; 
 and numerous improvements have of late years therefore been introduced in the 
 structure and arrangement of our stage coaches. The engraving in the following 
 page represents a model of an improved stage coach, by Mr. Skinner, for which 
 he was presented with the sum of thirty guineas by the Society of Arts. The 
 lowering of the centre of gravity, by removing the heavy luggage and outside 
 passengers from the roof of the carriage ; the convenient accommodation of the 
 latter ; the adoption of high fore-wheels to ease the draught ; and several minor 
 conveniences ; will be found to have been duly attended to, and to be combined 
 in the model of which the following is a description. The engraving gives a 
 perspective view of the vehicle. The front wheels are 5 feet 9 inches in 
 diameter. The inside and outside passengers are seated on the same level, the 
 floor being as near to the axletree as the play of the springs will admit, a is 
 the door through which the hind passengers get up, the seats being situated as 
 shown at 4 / c is a seat for the guard, attached to the door a ; dd iron bars 
 attached to the top and bottom of the dqor, and projecting enough to be firmly 
 held by turn buckles e e ; the steps g h and i, serve for the front passengers and 
 coachman to ascend by ; the passengers step upon the boards ^ on either side, 
 and over the side rails into the compartment k; the steps I m no serve for 
 ascending the hind part of the coach ; pp boards on each side over the hind 
 wheels; there are similar ones j j over the front wheels, which have iron rail*
 
 324 
 
 CARRIAGES. 
 
 to hold small luggage. To allow of locking the front wheels, the floor is nar- 
 rowed in the manner delineated ; q is the hind boot ; r r "he front boot ; s boxes 
 opening in the floor of the coach; t and v boxes opening in the guard's seat; u 
 a roll of leather to cover the front passengers ; it has a slip of iron along its 
 
 front, which catches on to the hooks w w ; it is wound up and held tight by a 
 ratchet wheel and pall x; ythe locking pin, which plays through the axletree; 
 the locking plate is under the floor and above the springs. There are five springs 
 in front, and five at the back ; two across each axletree, four across the coach 
 answering to them, and two more, one over each axletree, and rubbing on them. 
 The following engraving represents a stage coach of a very novel appearance, 
 invented by Mr. P. Birt, of the Strand, and distinguished by an improved 
 method of yoking the horses, and also by a drag which can be put into action 
 at pleasure, without any person descending for that purpose. The inside pas- 
 sengers occupy the seats at ins, which are at a higher level than those for tlie 
 
 outside passengers at o u t. There are three doors, one opening into the inside, 
 behind the seat n, and two opening into the outside at d d. The receptacle for 
 the luggage is at the bottom cc;/is the coachman's seat, where he is provided 
 with the means of putting the drag in action at pleasure, by means of the
 
 CARRIAGES. .?2.'i 
 
 lever g, the extremity of which is connected by a rope or chain to the skid iron, 
 and the latter is supported by a spring arm.;, which is fixed to the axletree or 
 the hind wheels. The usual method of yoking the horses to a coach, is to 
 attach the two ends of the traces to two fixed points on the long front splinter- 
 
 Fig. 2. 
 
 bar. In this way, if the traces are not exactly of a length, the horse pulls only 
 on one side when going in a straight line, and invariably so when making a 
 curve in the road ; the traces are, in consequence, subject to double the strain, 
 and the horses have all the work thrown upon one shoulder, instead of it being 
 equalized on both. To remedy this disadvantage Mr. Birt fixes two bent elastic 
 pieces to the splinter-bar, as shown in Fig. 3, which turn upon central pivots ; 
 and the traces being attached to the extremities of these elastic bars, the pull is 
 made from a single point, like that of the leaders in a four-horsed coach. The 
 advantage derived from this alteration is, greater freedom to the action of the 
 horses, and a better direction of their power ; the elastic bars likewise prevent 
 a great deal of unpleasant jolting, usually communicated to the carriage by the 
 motion of the horses. 
 
 The annexed engraving represents a four-wheeled carriage, invented by Mr. 
 
 Fig. 1
 
 326 
 
 CARRIAGES. 
 
 Fuller, of Bath, so constructed as to prevent the upsetting by those irregula- 
 rities in the road which are sufficient to overturn carriages of the usual construc- 
 tion, and, at the same time, to lessen considerably the unpleasant jolting motion 
 arising from the same cause. The construction may be described as follows : 
 Immediately over the axles of the fore wheels is placed a bar c c (which the in- 
 ventor calls the bed of the axle) ; this bar is attached to the axle by the springs 
 
 hh. On this bar is placed the locking wheel a a, which turns on the pivot b, 
 and is supported on the bar and frame-work as shown in Fig. 2. To the 
 locking wheel is firmly fixed the horizontal bar dd, at right angles to the axle- 
 bed, when the carriage is going straight forward. The ends of this cross-bar 
 are turned and fitted into the plummer block cc, which are attached by means 
 of the connecting pieces //and y g, to the fore part of the carriage as repre- 
 sented in Fig. 1. This permits the axle of the fore wheels, with the locking 
 wheel, to take an inclined position, while the body of the carriage remains 
 level ; and it will be seen from the carriage represented in Fig. 1, (which is a 
 front view,) that the axle of the fore wheels^, with the locking wheel and its 
 attachments, is inclined considerably by the wheel q passing over an elevation 
 in the road, while the body of the carriage remains horizontal, and its weight 
 is equally supported by both the wheels, instead of being all thrown on the 
 lower wheel, as would be the case were it not permitted to turn on the pivots of 
 the bar d. The other parts of the carriage are not different from those in 
 common use, and therefore need not be particularly described, o o are the 
 hind wheels; 1 1 part of the seats; Jc the dashing-iron and leather, and m the 
 foot-board. 
 
 The engraving on the followingpage represents a method of firmly fixing the poles 
 to Carriages, and, when required, of readily releasing them, great inconvenience 
 being frequently experienced from the poles sticking fast in wet weather when 
 fitted on the common plan, and being also subject to premature destruction in 
 those parts, a is the pole of the carriage ; b the splinter bar ; cc the fetchels ; 
 d part of the wooden^flxletree. An iron frame e e is fixed between the fetchels; 
 in the front of this iron frame there is a proper aperture to receive the tapered 
 part of the carriage pole, and another at the back, of less dimensions, to receive 
 the extreme end, which is shod with an iron bolt for that purpose ; this bolt or 
 pin is fixed on to the extremity of the pole by two long straps, which clasp the
 
 CARRIAGES. 
 
 327 
 
 top and the bottom, and have bolts passing through both. When the pole is 
 inserted into its place, it is secured there by turning the screw/, which forces 
 
 two iron wedges into recesses made in the frame, from whence they cannot be 
 withdrawn, or the pole detached, but by turning the pole the reverse way. 
 
 A patent was obtained in 1825 by Mr. Corbet, of Glasgow, for an improve- 
 ment upon the steps of carriages ; which is applicable to coaches generally, but 
 is peculiarly adapted to such, the proprietors of which do not employ a footman 
 
 Fig. 2. 
 
 to open and shut the door and steps, as the act of opening the door causes the 
 steps to open out, and that of shutting it shuts the steps up again. For 
 this reason the invention may be found of great convenience to medical and 
 other professional gentlemen. In the above engraving, Fig. 1 is intended to
 
 328 CARTRIDGE. 
 
 represent the back view of a coach, on one side of which the steps and door 
 are both open, and on the other side are both shut. Fig. 2 gives a side view of 
 the steps, only on a larger scale, and will, we trust, enable the reader to under- 
 stand their construction. At a is the coach body ; b a part of the coach door 
 open ; c is a bent iron fixed to the bottom of the door, connected to a curved 
 rod d, at the extremity of which is a joint e attaching it to the lever/, which 
 moves upon a fulcrum in the middle; atg is another joint, by which and ar 
 intermediate rod it is attached to one of the horns of the crank h ; the other 
 horn of this crank is connected by a joint to the long curved lever i i, which 
 gives motion to the short levers k /c, and these last being in one piece with the 
 steps II, they move together. The long curved bar o, (of which there are two, 
 one on each side of the steps,) and its short branch H are fixtures, being bolted 
 to the body of the carriage p p. The reader having noticed the train and con 
 nexion of the levers just mentioned, will readily perceive that the act of 
 shutting the door of the carriage will cause the lever /to assume another angle, 
 by which the crank h, and consequently the bar i i, will be thrown into the 
 position shown by the dotted lines ; and that it necessarily follows the steps will 
 be forced into the situation shown by the dotted lines at //. 
 
 CARNELIAN is a sub-species of calcedony. Its colours are white 
 yellow, brown, and red. It has a conchoidal fracture, and a spec. grav. of 2.6. 
 It is semi-transparent, and has a glistening lustre. It is found in the chan- 
 nels of torrents in India, in nodules of a blackish olive, passing into grey. 
 After exposure for some weeks to the sun, they are subjected to heat in 
 earthen pots, whence proceed the lively colours for which they are valued in 
 
 jewellery. 
 CARRC 
 
 CARRONADE. A short piece of ordnance, intended principally for close 
 combat at sea. 
 
 CARTHAMUS, SAFFLOWER, or BASTARD SAFFRON. Watery menstrua 
 take up the yellow, and leave the red colour, which may afterwards be extracted 
 by alcohol, or by a weak solution of alkali ; such particularly are the saffron 
 coloured flowers of carthamus. These, after the yellow matter has been ex- 
 tracted by water, are said to give a tincture to ley, from which, on standing at 
 rest for some time, a deep red fecula subsides, called safllower ; and from the 
 countries whence it is commonly brought to us, Spanish red and China lake. 
 The pigment impregnates alcohol with a beautiful red tincture, but communi- 
 cates no colour to water. Rouge is prepared from carthamus. For this purpose 
 the red colour is extracted by a solution of the sub-carbonate of soda, and pre- 
 cipitated by lemon juice, previously depurated by standing. This precipitate 
 is dried on earthen plates, mixed with French chalk, reduced to a powder by 
 means of the leaves of shave grass, triturated with it till they are both very 
 fine, and then sifted. The fineness of the powder, and proportion of the pre- 
 cipitate, constitute the difference between the finer and the cheaper rouge. It 
 is likewise spread very thin upon saucers, and sold in that state for dying. 
 Carthamus is used for dying silk of a poppy, cherry, rose, or bright 
 orange red. 
 
 CARTOON, or CARTON. A design drawn on strong paper, to be afterwards 
 chalked through, and transferred on the fresh plaster of a wall, to be painted 
 in fresco. It is also used for a design coloured for working mosaic tapestry, 
 carpets, &c. The word is from the Italian, cartoni, large paper, denoting many 
 sheets of paper pasted on canvass, on which large designs are made, whether 
 coloured or with chalks only. The most celebrated performances of this kind 
 are those by Raphael. 
 
 CARTOUCHE is a general term in the military art, applicable to a variety 
 of projectiles contained in differently formed cases. 
 
 CARTRIDGE. A case containing a charge of powder for fire-arms. For 
 pistols and muskets the case is made of-strong paper manufactured for the pur- 
 pose, and called therefore cartridge-paper, and the cartridges are called ball 
 or blank cartridges, accordingly as they contain or not a ball or bullet, with the 
 powder in the case. For cannon, the case for the powder is made of serge or 
 flannel ; but the Americans, during the last war, are said to have employed for
 
 CARVING. 
 
 32!) 
 
 that purpose " tea-kad," similar to that used for lining tea-chests ; the advantage 
 of which is, that the guns do not require sponging, and that no ignited portions 
 of the cartridge can remain in the chamber, from which most dreadful accidents 
 sometimes happen. For cannon, the cartridges are always made up without the 
 shot, between which and the cartridge, a 
 wad made of old rope is placed in charging 
 the cannon. The annexed engraving re- 
 presents an ingenious and well-contrived 
 machine, invented by W. Caffin, Esq., of 
 Woolwich, for filling cartridges, but which, 
 if constructed on a larger scale, may be 
 applied to measure grain, seed, and all Fig. 
 other articles that are estimated by strike 
 measure. Fig. 1 represents a perspective 
 view of the instrument, and Fig. 2 an 
 elevation in section. The measures d d 
 are fixed vertically in a circular plate / 
 opposite to each other, with an axis be- 
 tween them, upon which they work be- 
 tween two other plates. On the top plate 
 y y a hopper w is fixed, communicating 
 alternately with the measures, and filling 
 them ; and on the opposite side, in the 
 bottom plate a, is a hole with a spout z, 
 through which the discharge takes place. 
 The plates are framed together by three 
 pillars bbb, having double adjusting nuts 
 cc on each to regulate the distance of the 
 plates. The measures are moved by a 
 handle or lever e, the motion of which is 
 limited by two pins g g, which, while it 
 presents one under the hopper to receive, 
 places the other immediately over the 
 discharge hole for delivery, so that the 
 two operations of filling and discharging, 
 are going on at the same time. The bot- 
 tom of each measure is contracted, to re- 
 tard, in a small degree, the discharge, so fig. 2 
 as to secure one measure being filled be- y j 
 fore the other is emptied. A hole is cut 
 in the top plate over the discharging 
 measure, by which it may be ascertained 
 that it is always perfectly filled, as well 
 as that the whole of its contents are de- 
 livered ; x is the hook by which the 
 machine is supported. Some of these 
 machines have been used a long time for 
 filling cartridges, and a boy delivers with 
 ease 12,500 measures daily, from one ma- 
 chine, in the most perfect and accurate 
 manner, and supplies his hopper himself. 
 
 CARVING, in a general sense, is the art of cutting or fashioning a hard 
 body by means of some sharp instrument ; but in a more particular sense it is 
 usually understood to be the art of cutting figures and designs in wood. 
 A carver should possess some knowledge of drawing and modelling, in order 
 that he may be able to copy from nature. A rough imitation of the object or 
 design should first be modelled in clay by the fingers, and afterwards completed 
 with the modelling tools. A mould is then to be made, and a cast taken from 
 the model in plaster of Paris, as clay is difficult to preserve unless baked in a 
 kiln. The mould is made in the following manner : Plaster of Paris, which
 
 330 CASTING. 
 
 easily mixes with water, should be made of the thickness of cream, and should 
 be spread all over the model. When the plaster is set, the model should be 
 removed, the clay carefully picked out, and a mould will be obtained, called a 
 waste mould, which must be left in cold water for a quarter of an hour. When 
 used as a cast, it should be rubbed over with a mixture of hog's lard and the 
 droppings of sweet oil. The plaster of Paris is to be mixed as before, and 
 poured into the mould, which afterwards should be knocked off with a chisel and 
 mallet, by small pieces at a time ; the design will then appear of the same form 
 as that modelled in clay, which the carver may proceed to copy in any sort of 
 wood, but lime-tree is the best suited to beginners. The tools used in carving 
 are of various forms and sizes, and may be procured of good quality in the 
 shops, ready made. The instruments used by sculptors for measuring the dif- 
 ferent parts of their work, particularly the heights and depths, may be very 
 advantageously employed by the carver. Carving is an extremely fascinating 
 employment, and the young artist of taste soon becomes astonished and 
 delighted with the effect he produces by a few cuts of his chisel, 
 
 CASCABEL. The knot of metal behind the breech of a cannon ; it serves 
 as a handle to elevate or direct the piece, and likewise to sling and 
 fasten it. 
 
 CASCADE. A steep fall of water from a higher to a lower place : cascades 
 are both natural and artificial ; those which fall with great noise are usually 
 called cataracts, which see ; also FOUNTAIN. 
 
 CASE. In printing, a large oblong frame, placed aslope, divided into several 
 little square compartments, in each of which are kept a quantity of type or 
 letters of the same kind, whence the compositor takes them as he requires them 
 to compose his matter. 
 
 CASE-HARDENING is a term applied to the process of converting the 
 external surface of articles or masses of iron into steel, with the view of com- 
 bining the hardness of the latter with the toughness and comparative cheapness 
 of the former. See IRON. 
 
 CASEMATES. Vaulted apartments of masonry made in the bastions of 
 fortifications. 
 
 CASEMENT. A small window made to open or turn upon hinges. 
 
 CASERNS. A term frequently used synonymously with barracks, but which 
 more strictly applies to the huts or lodgings of soldiers in the ramparts of for- 
 tified places. 
 
 CASE SHOT, or CANISTER SHOT. Tin canisters filled with small balls, 
 which are discharged from cannon, and make sad havock with human life. 
 
 CASHEW-NUT. See ANACARDIUM. 
 
 CASK. A vessel of capacity, for holding both liquid and dry goods. See 
 BARREL and COOPERING. 
 
 CASTING AND MOULDING. Under this head we shall give the art of taking 
 impressions from sculptures, medals, and other delicate works of art ; also the 
 taking of casts from the face, and other natural objects. For the process of 
 casting articles of metal in the large way, see FOUNDRY. To procure a cast 
 from any figure, bust, medal, &c. it is necessary to obtain a mould, by pressing 
 upon the thing to be copied some substance capable of being forced into all the 
 cavities or hollows of the sculpture. When this mould is dry and hard, some 
 substance, which will fill all the cavities of the mould, is poured into it : the 
 form of the original from which the mould was taken, is now accurately repre- 
 sented. Moulding in any particular manner depends upon the form of the 
 subject. When there are no projecting parts, but such as rectilineal angles 
 with the principal surface of the body, nothing more is necessary than to cover 
 it over with the substance of which the mould is to be formed, and to take it off 
 clean, and without bending. It may be laid horizontally, and will bear to be 
 oiled without injury. The substances used for moulding are various, according 
 to the nature and the situation of the sculpture ; as wax, metal, plaster of 
 Paris, &c. This last is prepared in a fine powder, mixed with water, and 
 poured over the mould to a convenient thickness, after oiling it to prevent the 
 plaster from sticking. A composition of bees' wax, resin, and pitch, makes a
 
 CASTING. 831 
 
 very desirable mould, if many casts are to be taken. If the situation of the 
 sculpture be perpendicular, clay, or some similar substance, must be used. The 
 best kind of clay is that with which sculptors make their models ; it is worked 
 to a due consistence, and having been spread out to a size sufficient to cover all 
 the surface, it is sprinkled over with whiting, to prevent it from adhering to the 
 original. Bees' wax and dough, or the crumb of new bread, may also be used 
 for moulding some small subjects, as impressions of seals and bijoux. When 
 there are under-cuttings in the has relief, they must be first filled up before it 
 can be moulded, otherwise the mould could not be got off. When the casts are 
 taken afterwards, the places must be worked out with a proper tool. When the 
 model or original subject is of a round form, or projects so much that it cannot 
 be moulded in this manner, the mould must be divided into several parts; and 
 it is frequently necessary to cast each of them separately, and afterwards to join 
 them together. In this case the plaster must be tempered with water to such a 
 consistence that it may be worked like soft paste, and laid on with some con- 
 venient instrument, compressing it till it adapt itself to all parts of the surface. 
 When the model is thus covered to a convenient thickness, the whole is left at 
 rest till it becomes sufficiently firm to bear dividing, without falling to pieces 
 by any slight violence ; it must then be separated into pieces to be taken from 
 the model, which is done by cutting it with a thin bladed knife. Being now 
 divided, it must be cautiously taken off and kept till dry ; but before the separa- 
 tion of the parts is made, they are notched across the joints at proper distances, 
 that they may with certainty be put together again. The art of properly 
 dividing the moulds to make them separate from the model, requires dexterity 
 and skill. Where the subject is of a round or spheroidal form, it is best to 
 separate the mould into three parts, which will then easily come off from the 
 model; and the same will hold good of a cylinder, or any regular curved 
 figure. The mould being thus formed and dry, and the parts put together, it 
 must be first oiled and placed in such a position that the hollow may be 
 upwards. It is then filled with plaster mixed with water, and repaired where 
 necessary. This finishes the operation. In larger masses, where there would 
 otherwise be a great thickness of the plaster, a core may be put within the 
 mould, as was observed in regard to the casting of statues, to produce a hollow 
 in the cast : this saves expense of plaster, and renders the cast lighter. In the 
 same manner, figures, busts, &c., may be cast of lead, or any other metal, in 
 the moulds of plaster or clay ; the moulds must be perfectly dry, for should 
 there be any moisture, the sudden heat of the metal will convert it into vapour, 
 and produce by its expansion an explosion that would blow the melted metal 
 about to the great danger of the artist. 
 
 To take a Cast in Metal from any smatt Animal, Insect, or Vegetable. Prepare 
 a box sufficiently large to hold the animal, in which it must be suspended by a 
 string ; the legs, wings, &c. of the animal, or the tendrils, leaves, &c. of the 
 vegetable, must be separated and adjusted in their right position by a pair of 
 pincers. A due quantity of plaster of Paris, mixed with talc, must be tem- 
 pered to a proper consistence with water, and the sides of the box oiled. Also 
 a straight piece of stick must be put to the principal part of the body, and 
 pieces of wire to the extremities of the other parts, that they may form, when 
 drawn out after the matter of the mould is set and firm, proper channels for 
 pouring in the metal, and vents for the air, which, otherwise, by the rarefac- 
 tion it would undergo, from the heat of the metal, would blow it out, or 
 burst the mould. In a short time the plaster will set and become hard ; the 
 stick and wires may now be drawn out, and the frame in which the mould was 
 cast taken away ; the mould must then be put, first into a moderate heat, 
 and afterwards, when it is as dry as it can be rendered by that degree, removed 
 into a greater, which may be gradually increased until the whole be red hot. 
 The animal or vegetable inclosed in the mould will then be burnt to a coal, 
 and may be totally calcined to ashes by blowing for some time into the charcoal 
 and passages made for pouring in the metal and giving vent to the air. This 
 operation, at the same time that it destroys the remainder of the animal orvegetable 
 matter, will force out the ashes. The mould is then allowed to cool gently ; the
 
 832 CASTING. 
 
 destruction of the substance that had been included in it has now produced a cor- 
 responding hollow ; but it may, nevertheless, be proper to shake the mould, 
 and blow with bellows into each of the air vents, to free it wholly from any 
 remaining ashes : when there may be an opportunity of filling the hollow with 
 quicksilver, it will be found an effectual method of cleaning the cavity, as all 
 the dust and ashes must rise to the surface of the quicksilver, and be poured 
 out with it. The mould being thus prepared, must be heated very hot when 
 used, if the cast is to be made of copper or brass, but a less degree of heat will 
 serve for lead and tin. The metal being poured into the mould, it must 
 be gently struck, and then suffered to rest till it be cold ; it is then carefully 
 taken from the cast, but without force : such parts of the matter as appear to ad- 
 here more strongly, are to be softened by soaking in water until they be loosened, 
 that none of the more delicate parts of the cast may be broken off or bent. 
 When talc cannot be obtained, plaster alone may be used ; it is apt, however, 
 to be calcined by the heat used in burning the animal or vegetable from which 
 the cast is taken, and to become of too incoherent and fusible a texture. Stour- 
 bridge clay, washed perfectly fine, and mixed with an equal part of fine sand, 
 may be employed. Pounded pumice-stone and plaster of Paris, in equal 
 quantities, mixed with washed clay in the same proportion, make excellent 
 moulds. 
 
 To take a Cast in Plaster from a Person's Face. The person from whom the 
 cast is to be taken should lay down on his back, with his hair tied back, so that 
 none may cover his face. Into each nostril a conical piece of stiff paper, open 
 at each end, is placed to allow of breathing. The face is then to be lightly oiled 
 over with salad oil, to prevent the plaster from sticking to the skin. Fresh burnt 
 plaster is mixed with water to a proper consistence, and poured in spoonsful all 
 over the face (taking care that the eyes be shut), till it is entirely covered to 
 the thickness of a quarter of an inch. This substance will grow sensibly hot, 
 but this inconvenience is of short duration as, in a few minutes, the plaster 
 will set hard, and may be taken off in a complete mask, which will form a 
 mould, in which a head of clay may be moulded, wherein the eyes may be 
 represented as open, and such other additions or corrections made as may be 
 found necessary. Then this second face being anointed with oil, a second 
 mould of plaster is made upon it, consisting of two parts, jointed lengthwise 
 along the ridge of the noise, and in this a cast in plaster is taken, which is an 
 exact likeness of the original. 
 
 To take Casts from Medals, a mould must first he made of plaster of Paris, 
 or of melted sulphur. After having oiled the surface of the medal with a little 
 cotton, or a camel's hair pencil dipped in oil of olives, a hoop of paper must be 
 put round the medal, standing up above the surface, of the thickness you wish 
 the mould to be. Take now some plaster of Paris, mix it with water to the 
 consistence of cream, and with a brush rub it over the surface of the medal, to 
 prevent air-holes from appearing ; then immediately afterwards make it to a 
 sufficient thickness by pouring in more plaster. Let it stand half an hour, 
 when it will have grown so hard that you may take it off; then pare it smooth 
 on the back and round the edges, neatly : in cold or damp weather it should be 
 dried before a fire. When the mould is large, if you cover its face witli fine 
 plaster, a coarse sort will do for the back ; but no more plaster should be 
 mixed up at one time than can be used, as it will soon get hard, and cannot be 
 softened without being burned over again. Sulphur must not be poured upon 
 silver medals, as this will tarnish them. To prepare your mould for casting 
 sulphur, put plaster of Paris in it ; take half a pint of boiled linseed oil, and one 
 ounce of oil of turpentine, and mix them together in a bottle, dip the surface 
 of the mould into this mixture, take the mould out again, and when it has ab- 
 sorbed the oil, dip it again ; repeat this till the oil will no longer be absorbed. 
 Then wipe off the oil with cotton wool, and set the mould in a dry place for a 
 day or two, when it will be a hard surface. To cast plaster of Paris in this 
 mould, proceed with it in the same manner as above directed for obtaining the 
 mould itself, first oiling the mould with olive oil. When casts are wanted in 
 sulphur, the material must be melted in an iron ladle
 
 CATOPTRICS. 
 
 333 
 
 Fig. 1 
 
 To take Casts with Isinglass. Dissolve isinglass with water over the fire. With 
 a hair pencil lay the solution carefully over the surface of the medal, and let it 
 dry When hard, raise the isinglass with the point of a knife, and it will fly 
 oiF with a spring, leaving a sharp impression of the medal. The isinglass may be 
 coloured with any of the water colours while in solution, or yon may breathe 
 on the concave side, and lay gold loaf upon it, which, by shining through, 
 will give it the appearance of a gold medal. A little carmine mixed with the 
 isinglass gives the appearance of copper, particularly if gold leaf be placed inside. 
 
 CASTORS. Small wheels fixed to heavy household furniture, as tables, 
 sofas, &rc. to admit of moving them with facility. The annexed engraving 
 represents an improvement upon the common con- 
 struction, by the introduction of small antifriction 
 rollers, by which means the strain and pressure 
 upon the central pin is removed, and the small 
 wheel readily assumes the proper direction. It 
 is the invention of Mr. Harcourt, of Birming- 
 ham. Fig. 1 is a side view of the castor, the 
 upper or socket part only being in section ; a a 
 is a guide plate fixed round the central pin so 
 as to revolve with it : this plate has circular 
 holes made through it, in each of which is a 
 little spherical ball, which rolls as it is car- 
 ried round with the plate. Fig. 2 gives the plan 
 of the guide plate a, which has three or more 
 apertures for the antifriction rollers, and these 
 rollers may be either spherical or cylindrical ; 
 for which reason two of them are shown in this 
 diagram as spherical, and one as cylindrical. 
 
 CATARACT, in hydrography, is occasioned 
 by a precipice in the channel of a river, caused 
 by rocks or other obstacles stopping the course 
 of the stream, from whence the water falls with 
 great noise and rapidity. Such are the cataracts 
 of the Nile, the Danube, the Rhine, &c. In 
 that of Niagara, the perpendicular fall of the 
 water is 137 feet, and in that of Pistell Rhaiadr, 
 in North Wales, the fall of water is nearly 240 
 feet from the mountain to the lower pool. 
 
 CATECHU, or JAPAN EARTH. An extract prepared in India from the juice 
 of the mimosa catechu. In its present state it is a dry pulverable substance, 
 outwardly of a reddish colour, and internally of a shining dark brown, tinged 
 with a reddish hue. It contains a greater portion of tannin than any other 
 vegetable matter, and what is very remarkable, no gallic acid. 
 
 CATENARIA, or CATENARY. In the higher geometry, the curve line 
 formed by a line or cord hanging freely between two points of suspension, 
 whether those points be horizontal or not. The properties of this curve have 
 been practically applied in the construction of suspension bridges, for a descrip- 
 tion of which see BRIDGES. 
 
 CATOPTRICS, is that part of science which treats of the laws and properties 
 of light reflected from mirrors or specula. The whole doctrine of catoptrics 
 depends on this simple principle, namely, that the angle of incidence is equal 
 to the angle of reflection. 
 
 CATOPTRIC CISTULA. An arrangement of mirrors in a kind of box, by 
 which objects are represented as multiplied, magnified, or deformed. A variety 
 of pleasing phenomena are exhibited by machines of this kind. 
 
 CATOPTRIC, or REFLECTING DIAL, is a kind of dial which shows the hours 
 by means of a piece of looking-glass plate, adjusted to reflect the solar rays 
 upwards to the ceiling of a room, on which the hour lines are delineated. 
 
 CATOPTRIC TELESCOPE. Instead of lenses, this telescope is furnished chiefly 
 with mirrors, and exhibits remote objects by reflection instead of refraction.
 
 334 CEMENTS. 
 
 CAT'S EYE. A mineral of a beautiful appearance, brought from Ceylon. 
 Its colours are grey, green, brown, and red, of various shades; and from a 
 peculiar play of light proceeding from interposed white fibres, it has derived its 
 name. It is valued for setting as a precious stone. 
 
 CAULKING is a term applied in ship-building to the driving of a quantity 
 of oakum, saturated with tar, into the seams between the planks of ships, 
 which is effected by a blunt chisel and a mallet. After the oakum has been 
 driven very hard into the seams, it is covered with hot melted pitch or resin, to 
 preserve it against the effects of the water. The term caulking is, however, now 
 extensively applied to other operations of a similar nature ; thus engineers in 
 closing up the junctures between the flanges of pipes or plates of iron, caulk 
 them with iron cement. 
 
 CAUSTIC. A term in chemistry, applied to alkalies when deprived of 
 carbonic acid by means of quick lime. 
 
 CAUSTIC (Lunar). A preparation of silver dissolved in nitrous acid, and 
 afterwards fused and formed into small cylindrical pieces in a mould. 
 
 CAWK. A term given by miners to the opaque sulphate of barytes. 
 
 CEMENTATION. A chemical process, which consists in surrounding a 
 body in the solid state with the powder of some other bodies, and exposing the 
 whole for a time to a degree of heat not sufficient to fuse the contents. Thus 
 iron is converted into steel by powdered charcoal ; green bottle glass into 
 porcelain, by sand, &c. 
 
 CEMENTS, in general, are substances employed to unite bodies in close 
 adhesion, for which purpose they are applied in a semi-fluid or pasty state, 
 so as to be brought into intimate contact with the opposite surfaces, and becoming 
 solid as the moisture exhales, the whole form, as it were, one mass. Cements 
 are variously composed, according to the nature of the surfaces to which they 
 are applied, and their exposure to heat or moisture. We shall here annex the 
 processes of preparing and mode of employing those which are in the most 
 esteem. 
 
 Cement for Steam. The following methods are adopted by machinists to 
 join the flanges of iron cylinders, and other parts of hydraulic and steam 
 engines. Boiled linseed oil, litharge, red and white lead, mixed together to a 
 proper consistence, applied on each side of a piece of flannel, previously shaped 
 to fit the joint, and then interposed between the pieces before they are brought 
 home, as the workmen term it, to their place, by the screws or other fastenings 
 employed, make a close and durable joint. The quantities of the ingredients 
 may be varied without inconvenience, taking care not to make the mass too thin. 
 It is difficult in many cases instantly to make a good fitting of large pieces of 
 iron work ; this renders it necessary sometimes to join and separate the pieces 
 repeatedly before a proper adjustment is obtained. When this is required, the 
 white lead ought to predominate in the mixture, as it dries much slower than 
 the red. A workman knowing this fact, can be at little loss in exercising his 
 own discretion in regulating the quantities. It is safest to err on the side of 
 the white lead, as the durability of the cement is no ( t thereby affected ; a longer 
 time only is required for it to dry and harden. When the fittings will not 
 easily admit of so thick a substance as flannel being interposed, linen, paste- 
 board, or even paper, may be substituted. Stones that are broken, however 
 large, may be joined together very well with this cement, and cisterns put 
 together with it will never leak. In this case, the stones need not be entirely 
 bedded in it ; an inch, or even less, of the edges that are to be next the water, 
 need only be so treated; the rest of the joint may be filled up with good lime. 
 
 Iron Cement. Take two ounces of muriate of ammonia, one of flour of 
 sulphur, and sixteen of cast-iron filings or borings. Mix them well in a mor- 
 tar, and keep the powder dry. When the cement is wanted for use, take one 
 part of this mixture, twenty parts of clear iron borings or filings, grind them 
 together in a mortar, mix them with water to a proper consistence, and apply 
 them between the joints. This cement is in extensive use by iron founders, 
 and is found to be very excellent, as in time it unites with the iron as one mass. 
 
 Cement for Iron Boilers. Six parts of clay, one of iron filings, and linseed
 
 CEMENTS. 335 
 
 oil sufficient to form a thick paste, make a good cement for stopping cracks in 
 iron boilers. 
 
 Cement for Copper Boilers. Powdered quick lime mixed with bullock's blood 
 is often used by coppersmiths, to lay over the rivets and edges of the sheets of 
 copper in large boilers, as a security to the junctures, and also to prevent cocks 
 from leaking. 
 
 Cements for Jewellers, Lapidaries, fyc. It sometimes happens, that jewellers, 
 in setting precious stones, by accident break off pieces ; in this case they join 
 them, so that it cannot easily be seen, with gum mastic, the stone being pre- 
 viously made hot enough to melt it. By the same medium cameos of white 
 enamel, or coloured glass, are often joined to a real stone as a ground, to pro- 
 duce the appearance of an onyx. Mastic is likewise used to cement false backs 
 or doublets to stones, to alter their hue. The jewellers in Turkey, who are 
 generally Armenians, ornament watch-cases and other trinkets with gems, by 
 glueing them on. The stone is set in silver or gold, and the back of the setting 
 made flat to correspond with the part to which it is to be applied. It is then 
 fixed on with the following cement : isinglass, soaked in water till it swells up 
 and becomes soft, is dissolved in French brandy or in rum, so as to form a 
 strong glue. Two small bits of gum galbanum, or gum ammonicum, are dissolved 
 in two ounces of this by trituration, and five or six bits of mastic, as big as peas, 
 being dissolved in as much alcohol as will render them fluid, are to be mixed with 
 this by means of a gentle heat. This cement is to be kept in a phial closely 
 stopped ; and when used, it is to be liquefied by immersing the phial in hot 
 water. This cement will resist moisture. Temporary cements are wanted in 
 cutting, grinding, or polishing optical glasses, stones, and various small articles 
 of jewellery, which it is necessary to fix on blocks, or handles, for the purpose. 
 Four ounces of resin, a quarter of an ounce of wax, and four ounces of whiting, 
 made previously red hot, form a good cement of this kind, as any of the above 
 
 articles may be fastened to it by heating them, and removed at pleasure in the 
 same manner, though they adhere very firmly to it when cold. Pitch, resin, 
 and a small quantity of tallow, thickened with brick dust, is much used at Bir- 
 
 mingham for these purposes. Four parts of resin, one of bees'-wax, and one 
 of brick-dust, likewise make a good cement. This answers extremely well for 
 fixing knives and forks in their hafts ; but the manufacturers of cheap articles 
 of this kind too commonly use resin and brick-dust alone. On some occasions, 
 in which a very tough cement is requisite, that will not crack though exposed 
 to repeated blows, as in fastening to a block metallic articles that are to be cut 
 with a hammer and punch, workmen usually mix some tow with the cement, 
 the fibres of which hold its parts together. Seven or eight parts of resin, and 
 one of wax, melted together, and mixed with a small quantity of plaster of 
 Paris, is a very good cement to unite pieces of Derbyshire spar, or other stone. 
 The stone should be made hot enough to melt the cement, and the pieces should 
 be pressed together as closely as possible, so as to leave as little as may be of 
 the cement between them. This is a general rule in cementing, as the thinner 
 the stratum of cement interposed, the firmer it will hold. 
 
 Cement for Electrical Apparatus. One pound of bees'-wax added to five 
 pounds of resin, one pound of red ochre, and two table-spoonfuls of plaster of 
 Paris, all mixed together, make an excellent composition ; but a cheaper one, 
 for cementing voltaic plates into wooden troughs, is made with six pounds of 
 resin, one pound of red ochre, half a pound of plaster of Paris, and a quarter 
 of a pint of linseed oil. The ochre and plaster of Paris should be well dried, 
 and added to the other ingredients in a melted state. 
 
 Universal Cement, particularly adapted for joining glass, porcelain, and 
 metallic surfaces, is thus prepared. To an ounce of mastic add as much highly 
 rectified spirits of wine as will dissolve it. Soak an ounce of isinglass in water 
 until quite soft, then dissolve'it in pure rum or brandy, until it forms a strong 
 glue, to which add about a quarter of an ounce of gum ammoniac, well 
 rubbed and mixed. Put the two mixtures together in an earthen vessel, over a 
 gentle heat; when well united, the mixture may be put into a phial, and 
 kept well stopped. When wanted for use, the bottle must be set in warm
 
 336 CEMENTS 
 
 water, the china or glass articles must be also warmed, and the cement 
 applied. It will be proper that the broken surfaces, when carefully fitted, shall 
 be kept in close contact for twelve hours at least, until the cement is fully set; 
 after which, the fracture will be found as secure as any part of the vessel, and 
 scarcely perceptible. 
 
 Cement for Chemical Glasses. Mix equal quantities of wheat flour, finely 
 powdered Venice glass, pulverized chalk, with half the quantity of fine brick- 
 dust, and a little scraped lint, into some whites of eggs. This mixture must 
 then be spread upon a linen cloth, and applied to the crack of the glasses ; it 
 should be dried before they are put to the fire. 
 
 Cement for Stone Paper or Artificial Slates. Linseed oil rendered drying, 
 intimately mixed with white-lead and chalk : this should be used in a nearly 
 fluid state, as by doing so it will insinuate itself amongst the joints and interstices, 
 and cover the heads of the nails perfectly. 
 
 Water Cements, or Roman Cements, harden under water, and consolidate 
 almost immediately on being mixed. The ancient Romans, in making- their 
 water cements, employed a peculiar earth obtained at the town of Puteoli. 
 This they called Pulvis Puteolanis : it is the same that is now called Puzzolana. 
 There is a substance called tarras, terras or trass, mostly employed by the Dutch 
 in their great aquatic structures. It is very durable in water, but inferior to the 
 other kinds in the air. In an analysis of Parker's Roman cement, by Monsieur 
 Berthier, he finds that its constituents differ so little from the constituents of 
 chalk and common clay, that he proposes the manufacturing of a similar cement 
 by the mere mixture of them in certain proportions. One part of clay, and 
 two and a half parts of chalk, sets almost instantly, and may therefore be 
 regarded as Roman cement. If clay and oxide of iron be mixed with oil, 
 according to Mr. Gad, of Stockholm, they will form a cement that will harden 
 under water. It has been discovered that manganese is a valuable ingredient 
 in water cements : four parts of grey clay are mixed with six of the black 
 oxide of manganese, and ninety of good limestone, reduced to fine powder ; 
 then the whole is calcined to expel the carbonic acid. When this mixture has been 
 well calcined and cooled, it is to be worked into the consistence of a soft paste, 
 with sixty parts of washed sand. If a lump of this cement be thrown into 
 water, it will harden directly. 
 
 Turners' Cement. Melt together resin one pound, pitch four ounces; and 
 while boiling-hot, add brick dust, until, by dropping a little upon a stone, you 
 perceive it hard enough ; then pour it into water, and immediately make it up 
 in rolls, and it will be fit for use. A finer cement is made of pitch two ounces, 
 resin one ounce, and red ochre finely powdered. A small quantity of tallow is 
 used sometimes, according to the heat of the weather, more being necessary in 
 winter than summer. Either of these cements are of great use to turners. By 
 applying it to the side of a chuck, and -making it warm before the fire, you 
 may fasten any thin piece of wood, which will adhere while it is turned ; 
 when it is wanted offagain, it need only be struck on the top with a tool, and 
 it will immediately fall off. 
 
 Mice Cement. This useful and elegant cement, which is beautifully white, 
 and dries almost transparent, is made by mixing rice flour intimately with cold 
 water, and then gently boiling it. Papers pasted together with this cement 
 will sooner separate in their own substance than at the joining. It is, there- 
 fore, an excellent cement in the preparation of curious paper articles, as tea- 
 trays, ladies' dressing and work boxes, and other articles which require layers 
 of paper to be cemented together. In every respect it is preferable to common 
 paste made with wheat flour. It answers well for pasting into books the copies of 
 writing taken off by copying machines on unsized silver paper. With this com- 
 position, made with a small quantity of water, that it may have a consistence 
 similar to plastic clay, models, busts, statues, basso-relievos, and the like, may 
 be formed. When dry the articles made of it are susceptible of a high polish ; 
 they are also very durable. The Japanese make quadrille fish of this substance, 
 which so nearly resemble those made of mother-of-pearl, that the officers of 
 our East Indiamen are often imposed upon.
 
 CENTRAL FOUCES. 337 
 
 Parolic Cement. To prepare this cement, take the unsalted curd of skimmed 
 milk, after pressing the whey out of it, and break it into lumps ; distribute these 
 lamps upon linen sheets laid upon the floor of an airv room to dry ; and fre- 
 quently, from time to time, as the curd acquires greater consistency, stir and 
 break it into smaller masses, either with the hands, or with the assistance of 
 a flat board, and a bar or rubber of wood, until at length it becomes dry 
 enough to grind in a steel coffee-mill to a powder about as fine as the best 
 gunpowder, when it must be gently dried over a stove, and kept dry for use. 
 lOOlbs. of curd frcm the cheese-press will only afford about 30 Ibs. of the dry 
 curd. To 90 parts of this dried curd, 10 parts of caustic quick lime, made of 
 blue marble, finely rubbed to powder and searced, and 1 part of camphor, must 
 be added, and well mixed, by rubbing the whole together with a pallet-knife 
 upon a stone slab; and the whole must be then inclosed in bottles, holding 
 about an ounce each, and well corked immediately afterwards, in order to pre- 
 vent the access of air to the composition. In this state the cement will remain 
 good a long time ; and when wanted for use, a little of it must be poured out 
 upon any flat earthen plate, &c., and, by the aid of a pallet or case-knife, be 
 instantly mixed with a proper quantity of water, to render it of a fit consistency 
 for the purpose to which it is to be applied. The bottle must be again carefully 
 closed, after taking out the quantity of cement required, as, otherwise, the lime 
 would lose its causticity, upon which its solvent action, or the caseous part of 
 the cement, entirely depends. 
 
 The manufacture of that important and valuable cement, glue, is described 
 in its initial order in this work. 
 
 CENTRAL FORCES. The two antagonist forces by which bodies are 
 caused to revolve round a central point As all forces act in right lines, the 
 tendency of any body moving in a circle is to fly off in a right line forming 
 a tangent to the circle, and this tendency is called the centrifugal force ; and 
 the force by which it is restrained from so flying off, and which maintains it in 
 its curvilinear path, is termed the centripetal force ; and these two forces are 
 necessarily equal to each other. Dr. Brewster has summed up the whole 
 doctrine of the central forces in the following propositions. 1. The centrifugal 
 forces of two unequal bodies moving with the same velocity, and at the same 
 distance from the centre of motion, are to one another as the respective quantities 
 of matter in the two bodies. 2. The centrifugal forces of two equal bodies 
 which perform their revolutions round the central body in the same time, but at 
 different distances from it, are to one another as their respective distances from 
 the central body. 3. The centrifugal forces of two bodies which perform their 
 revolutions in the same time, and whose quantities of matter are inversely as 
 their distances from the centre, are equal to each other. 4. The centrifugal 
 force of two equal bodies moving at the same distance from the central body, 
 but with different velocities, are to one another as the squares of the velocities. 
 5. The centrifugal forces of two unequal bodies moving at equal distances from 
 the centre with different velocities, are to one another in the compound ratio of 
 their quantities of matter and the squares of their velocities. 6. The centrifugal 
 forces of two equal bodies moving with equal velocities at different distances 
 from the centre, are inversely as their distances from the centre. 7. The 
 centrifugal forces of two unequal bodies moving with equal velocities at different 
 distances from the centre, are to one another as their quantities of matter 
 multiplied oy their respective distances from the centre. 8. The centrifugal 
 forces of two unequal bodies moving with unequal velocities at different dis- 
 tances from the centre, are in the compound ratio of their quantities of matter, 
 the squares of their velocities, and their distances from the centre. 
 
 To find the centrifugal force of any body : Divide the velocity in feet per 
 second by 4.01, and the square of the quotient by the diameter of the circle; 
 the quotient is the centrifugal force when the weight of the body is 1. Hence 
 the quotient, multiplied by the weight of the body, is the centrifugal force 
 required. Ex. Required the centrifugal force of the rim of a fly-wheel 20 feet 
 in diameter, moving with a velocity of 32* feet per second : 
 
 32^-7-401=8.02 and 8.02 2 -*-20=3.216 times the weight of the rim.
 
 338 CENTRE OF PERCUSSION. 
 
 Rule 2. Multiply the square of the number of revolutions per minute, by the 
 diameter of the circle in feet, and divide the product by the constant number 5870, 
 and the quotient is the centrifugal force when the weight of the body is 1 ; 
 and this quotient, multiplied by the weight of the body, is its centrifugal force. 
 Ex. Required the centrifugal force of a stone weighing 2 Ibs., revolving in a 
 circle of 4 feet diameter, at the rate of 120 revolutions per minute : 
 
 120 2 X 4=57600 and '^J^-=9.81 
 5670 
 
 hence 9.81 X 2=19.62 centrifugal force. 
 
 CENTRE OF GRAVITY. A point in any body about which all the 
 parts are in equilibrio ; so that if the body be suspended or supported by this 
 point, it will remain in any position in which it may be placed. The centre of 
 gravity of any plane may be found mechanically as follows: suspend the plane 
 by a point in or near its perimeter, and when it is at rest, draw across it a 
 vertical line, passing through the point ; suspend it in like manner by another 
 point, and draw a vertical line as before ; the intersection of these lines is 
 the centre of gravity. 
 
 CENTRE OF GYRATION is that point in a body revolving about an axis, 
 into which, if the whole quantity of matter were collected, the same moving force 
 would generate the same angular velocity. To find the centre of gyration : mul- 
 tiply the weight of the several parts of the body by the squares of their distances 
 from the centre of motion, and divide the sum of the products by the weight 
 of the whole mass, and the square root of the quotient will be the distance of 
 the centre of gyration from the centre of motion. 
 
 CENTRE OF OSCILLATION is that point in a body suspended from a 
 point and made to vibrate, in which all its force is collected, and to which point, 
 if an obstacle were applied, all its motion would cease. To find the centre of 
 oscillation in a compound pendulum: Multiply all the parts or bodies of which 
 the pendulum is composed, each by the square of its distance from the point of 
 suspension, and divide the sum of the products by the product of the whole 
 weight of the pendulum, multiplied by the distance of the centre of gravity 
 from the point of suspension. 
 
 CENTRE OF PERCUSSION. That point in a body revolving about a fixed 
 axis into which the whole force or motion is collected ; it is, therefore, that point 
 of a revolving body which would strike an obstacle with the greatest effect, and 
 from this property it has received the name of the centre of percussion. The 
 centres of percussion and of osculation are generally treated separately, but 
 the two centres are in the same point, and therefore their properties are the 
 same. As in bodies at rest the whole weight may be considered as collected in 
 the centre of gravity, so in bodies in motion, the whole force may be considered 
 as concentrated in the centre of percussion ; therefore, the weight of the rod 
 multiplied by the distance of the centre of gravity from the point of suspension, 
 will be equal to the force of the rod divided by the distance of the centre of 
 percussion from the same point. For example : suppose a rod, 12 feet long, 
 and weighing 2 Ibs. per foot, with two balls of 3 Ibs. each, one fixed 6 feet 
 from the point of suspension, and the other at the end of the rod ; what is 
 the distance between the points of suspension and of percussion ? 
 
 12X2X6=1 44 momentum of rod. 
 3X6 =18 ditto of first ball. 
 3X12 =36 ditto of second balL 
 
 198 momentum of balls and rod : 
 
 and the weight of the rod multiplied by the square of its length, and divided 
 by 3=to the force of the rod; and the weight of the balls multiplied by the 
 square of their distance from the point of suspension=to the force of the ball. 
 Therefore
 
 CERUSE. 339 
 
 24 X 144 
 
 jj =1152 the force of the rod 
 
 3 X 36= 108 ditto of the first ball 
 3 X 144= 432 ditto of the second ball 
 
 1692=force of balls and rod, 
 
 and 1692-5-198=8.545 feet from the point of suspension. In a slender rod, of 
 small breadth as compared with its length, the distance of the centre of percussion 
 is nearly two-thirds of its length from the point of suspension. In an isoceles 
 triangle, suspended by its apex, and vibrating in a plane perpendicular to itself, 
 the distance of the centre of percussion is three-fourths of its altitude ; and the 
 same thing holds with regard to fly-wheels, or wheels in general. 
 
 CENTRE, or CENTERING. The framing of timber by which an arcb or 
 vault is supported during its erection. See BRIDGE. 
 
 CENTRIFUGAL MACHINE. A machine invented by Mr. Erskine for 
 raising water by means of a centrifugal force combined with the pressure of the 
 atmosphere. This machine consists of a vertical tube resting upon a pivot, and 
 having at top two horizontal hollow arms, near the extremity of each of which, 
 but on opposite sides, is a valve opening outwards ; whilst near the bottom of 
 the vertical tube, and below the surface of the water to be raised, is a valve 
 opening inwards. On the upper part of the arms are two holes, with screw- 
 caps, and through these holes water is poured previous to setting the machine 
 in motion ; by which means the air is forced out of the machine, and the water 
 supported in the tube by the foot-valve at the bottom. The holes in the arms 
 being secured by their screw-caps, and a rapid rotatory motion being commu- 
 nicated to the tube, the water in the arms acquires a centrifugal force, opens 
 the valves near the extremity of the arms, and flies out with a velocity nearly 
 equal to that of the arms, discharging itself into a circular trough. Although 
 extremely ingenious and simple, this machine is not equal in effect to a well- 
 made pump ; and as the fluid is forced up the vertical tube into the arms by 
 the pressure of the atmosphere, it is incapable of raising water to a height 
 exceeding 33 feet. 
 
 CERATE. A compound of hog's lard or oil with bees' wax, employed in 
 surgery. 
 
 CER.IN. That part of common wax which is dissolved by alcohol. 
 
 CKRIUM. A newly discovered metal found in the mineral cerite. It has 
 not yet been obtained in a useful metallic form. 
 
 CERUSE, or WHITE LEAD, is commonly made by coiling up very thin cast 
 sheets of lead into rolls, so as to leave a small space between each fold. The 
 rolls thus formed are lightly jammed into the mouths of a number of earthen- 
 ware pots, which are about half filled with vinegar. These pots are placed in 
 a situation where a very gentle heat will cause a slow evaporation of the 
 vinegar, in order that it may gradually operate upon the lead. A layer of 
 several hundreds of them are usually deposited either in a bed of tanner's spent 
 bark, or dung, contained in a wooden frame. Boards are then laid over the 
 tops of these pots, and on this temporary floor, which is supported by boards 
 placed edgeways, is laid another layer of pots similarly furnished. Seven such 
 layers of pots are placed in succession over each other, to form a stack. When 
 the vinegar is found to be completely evaporated in these stacks, which 
 generally occupies three months, they are taken down ; the corroded lead is 
 taken out of the mouths of the pots, but as the adhesion to the latter is very 
 strong, many of them are broken in getting out the lead, and the poisonous 
 dust which the workmen inspire by this operation, lamentably impairs their 
 health, and they are often in consequence afflicted with the disease called the 
 Devonshire, or painter's colic. To avoid this serious evil, and economize the 
 process, a different and more mechanical arrangement has been made. The base 
 of the stack is made of a layer of pots filled with vinegar only ; over these is 
 supported, by planks on edge, a floor of boards, pierced with numerous holes 
 to allow the passage of the acid vapour ; on thest perforated boards are then
 
 340 CHAIN. 
 
 laid the rolls of lead, then another perforated floor, and another layer of rolls, 
 until the stack is completed. By this arrangement it is said that the manufac- 
 turer obtains one-third more white lead, saves his pots from breakage, and 
 avoids the dust so pernicious to the workmen by first sprinkling the rolls with 
 water. Upon uncoiling the plates, the white substance that falls off is the purest 
 white lead, and is disposed of for the finest work under the name offtake white ; 
 a portion of the latter is ground up with water, formed into small lumps, and 
 sold under the name of ceruse. But all the white lead that is subsequently 
 taken off the plates is ground up either with water, and sold in large lumps, or 
 it is ground with oil, and is usually more or less adulterated with whiting, to 
 suit the various prices at which it is required in the market. As the processes 
 employed in France and Germany for the manufacture of ceruse appear to be 
 well worthy of attention, we shall here annex some account of them. In 
 France the first part of the process consists in dissolving 174lbs. of finely- 
 ground litharge in 65 Ibs. of pyroligneous acid, of such strength that 22 grains 
 of this acid will saturate 25 grains of sub-carbonate of soda ; fifteen to twenty 
 times as much water is usually added. The whole is left for a short time, and 
 the clear portion being decanted off, some fresh acid and water is poured on the 
 sediment, to take up any oxide that might have escaped the action of the first 
 parcel. The decanted solution is run into large shallow covered cisterns, into 
 which carbonic acid gas is passed through numerous pipes. When the settling 
 appears to be completed, the whole is passed into a deep cistern, and left there 
 for some hours, when the liquid part is to be poured off, in order to be combined 
 with more litharge, some fresh acid being also added. After the desired tint 
 has been given to the lead, it is well drained, put into glazed pots of the proper 
 shape to imitate the Dutch white lead leaves, then dried in stoves, and lastly, 
 packed in blue paper to heighten the effect of its beautiful colour. 
 
 In Germany the first part of the process consists in casting the pure lead of 
 Corinthia into very thin sheets, which is effected by pouring the liquid metal 
 upon inclined sheets of iron. The sheets of lead are trimmed to a proper size, 
 and suspended over an acid liquor contained in boxes, which are usually about 5 
 feet long, 1 foot broad, and 10 inches deep ; and they are pitched internally on 
 the bottom, and rising therefrom about 2 inches at the sides. Sticks are placed 
 across the boxes, and the sheets of lead are doubled so as to be suspended in the 
 middle by them, but so as not to touch each other, nor the acid liquor deposited 
 underneath them. The liquor in some manufactories is made of equal parts of 
 vinegar (obtained from crab apples) and wine lees, and about two gallons of this 
 mixture is apportioned to each box. Some manufacturers use 20 pints of vinegar, 
 8 pints of wine lees, and 1 Ib. of pearl ash. The usual mode is to dispose the 
 boxes in a large room heated up to 87 Fahrenheit ; a greater heat would 
 evaporate the acid too fast. In about a fortnight the corrosion is finished, 
 rendering the sheets about a quarter of an inch thick, and partially covered 
 with crystals of sugar of lead. Those crystals that are easily detached are 
 carefully washed ; during this operation a white scum appears, which is taken 
 off, and a little pearl ash being added to it, it is changed into ceruse of a beautiful 
 whiteness, and is sold for the choicest purposes; the remainder is mixed in 
 different proportions with the pure sulphate of barytes, brought from the Tyrol. 
 
 C ETINE. The name given by Chevreul to spermaceti, which is extensively 
 adopted. See FAT. 
 
 CHAFF-CUTTING MACHINE, as its name denotes, is a machine for 
 cutting chaff for cattle, which being an object of some consequence on large 
 farms, and in establishments employing many horses, a variety of machines 
 have been invented for the purpose of performing the operation with facility 
 and dispatch. For a highly-improved machine of this description, see the 
 article STRAW. 
 
 CHAIN. A series of links of metal engaged one within the other; also, 
 in surveying, a measure of length, made of a certain number of links of iron 
 wire. That which is most commonly used for this purpose, called Gunter's 
 chain, is composed of 100 links = 4 poles, or 66 feet; and 1 square charn= 
 10,000 links=16 poles; .10 square chains= 100,000 links=160 poles= 1 acre
 
 CHEESE. 341 
 
 CHAIN PUMP. See PUMPS. 
 
 CHALDRON. An English measure for coals, containing 12 sacks, or 36 
 bushels. The bushel measures are always heaped up, and on shipboard, 21 
 chaldrons are allowed to the score. 
 
 CHALK. A species of carbonate of lime. 
 
 CHALYBEATE. Mineral water impregnated with iron is so called. 
 
 CHARCOAL. The fixed residue of vegetables exposed to a strong heat 
 whilst protected from the access of the atmospheric air. In countries where 
 wood abounds, charcoal is prepared by forming it into a conical stack, covered 
 with clay and turf to the depth of several inches, leaving an aperture at the 
 top for the escape of the smoke, and several small apertures at bottom for the 
 admission of air at first lighting of the pile, but which are carefully closed as 
 soon as the ignition is supposed complete. Charcoal is also made on a great 
 scale by charring wood in iron cylinders, as described under the head of ACETIC 
 ACID. Charcoal has been prepared lately in France from turf or peat, and is 
 said to be superior to that prepared from wood. In a goldsmith's furnace it 
 fused 11 ounces of gold in 8 minutes; whilst wood charcoal required 16 minutes 
 to produce the same effect. The malleability of the gold, too, was preserved 
 in the former instance, but not in the latter. From the scarcity of wood in this 
 country, pitcoal charred is much used instead of charcoal, and is known by the 
 name of coke. 
 
 CHARGE, in gunnery, the quantity of powder and shot which is necessary 
 to load a piece of ordnance, in order that when fired it may produce the in- 
 tended effect. For proving guns the weight of the powder is always equal to 
 that of the ball ; but the charge of powder generally esteemed sufficient for 
 service is one-half or one-third the weight of the ball, or even less. Dr. 
 Hutton found, from many experiments, that the length of the charge producing 
 the greatest velocity, in guns of various lengths of bore, from 15 to 40 cali- 
 bres, is as follows : 
 
 Length of bore. Length of charge. 
 
 15 
 
 calibres. 
 
 the length of the bore. 
 
 CHAYA ROOT. The root of Oldenlandia umbcttata, which grows wild on 
 the coast of Coromandel, and is likewise there cultivated for the use of the 
 dyers and calico pi-inters. It is used for the same purposes as madder with us, 
 to which it is said to be far superior, giving the red so much admired in the 
 Madras cottons. 
 
 CHEESE. An article of food obtained by mixing an acid with milk, which 
 causes it to coagulate and form a curd ; the curd is then subjected to the action of 
 a powerful press to separate it from the whey, after which it is set upon racks 
 to dry. The quantity of curd is less when a mineral acid, than when a vege- 
 table acid is used ; but the substance which answers best for this purpose, and 
 indeed which is almost the only one employed in England, is rennet, which is 
 made by macerating in water the last stomach of a calf, salted and dried for 
 this purpose. Cheese is made in several parts of England, but that made in 
 Chester is generally esteemed superior to all others. An excellent account of 
 the mode of making it will be found in Vol. XI. of Tillock's Magazine, taken 
 from the agricultural report of the county. " If the milk," says the reporter, 
 " be set together very warm, che curd, as before observed, will be firm ; in this 
 case, the usual mode is to take a common case knife, and make incisions across 
 it to the full depth of the blade of the knife, at the distance of about 1 inch, 
 and again crossways in the same manner, the incisions intersecting at right 
 angles. The whey rising through these incisions is of a fine pale green colour. 
 The cheese-maker and two assistants proceed then to break the curd ; this is 
 performed by their repeatedly putting their hands down into the tub, the cheeso- 
 x x
 
 342 CHEMISTRY 
 
 maker with the skimming dish in one hand, breaking every part of it as they 
 catch it, raising the curd from the bottom, and still breaking it. This 
 part of the business is continued till the whole is broken uniformly 
 small; it generally takes up about 40 minutes, and the curd is then left 
 covered over with a cloth to subside." The cheese is subsequently broken 
 by hand, mixed with salt, and put into a vat, in which it is pressed with 
 loaded boards, and then is turned over upon a cloth into another vat, with a 
 tin hoop or binder over the upper part of the cheese, and within the sides of 
 the vat, and then pressed for about 8 hours, being twice turned in the vat 
 during that time. It is then set to dry, being turned twice a day for the first 
 week, and then cleared and turned once daily for three weeks longer, after 
 which it is removed to the common cheese-room, where it is laid upon straw 
 upon a boarded floor until it acquires the proper hardness. 
 
 CHEMISTRY is the science which teaches the composition, properties, and 
 uses, of all material bodies. It is the business of Mineralogy to investigate the 
 properties and uses of inorganic substances as they naturally occur, but it is 
 the office of chemistry to reduce, not only them, but all organic bodies, to their 
 primitive elements, and having discovered the component parts and their pro- 
 portions, to aim at their reproduction, when such reproduction would be beneficial 
 to man. Under this head we shall give but a short sketch of this extensive 
 science, as it will be necessary to explain the nature and mode of operation of 
 those potent agents, Light, Heat, and Electricity ; and as each substance which 
 is the object of chemical research will be described under the initial letter of its 
 name. For the history of this science we must refer our readers to Brande's 
 Manual, or some other systematic work on the science, as its details would be 
 fa.r too multifarious to be compatible with the limits of this work. The science 
 of chemistry will be found to depend chiefly on the operation of the different 
 degrees of attraction which the various elementary bodies have for each other. 
 Every mass of matter on the earth, or diffused through the universe, is found to 
 tend towards every other mass. This tendency is expressed by the term gravi- 
 tation, and it is found to increase in intensity as the masses are nearer in the 
 proportion of the squares of the distances between them. If, however, we 
 examine this power in individual masses, we shall find it act with much greater 
 intensity, and to vary its force in different bodies; it is then called affinity. 
 The former species of attraction, or that acting on masses at sensible distances, 
 forms the particular object of study in mechanical philosophy; while the action 
 of the particles on each other at insensible distances is the object of chemical 
 philosophy. When this affinity acts between particles of the same kind, it is 
 called cohesion ; but when it operates between particles of a different kind, it is 
 called chemical attraction, the attraction of composition, or sometimes simply 
 affinity. One particle of copper is attached to another particle of copper by 
 cohesion; also a particle of sulphate of copper to another particle of the same 
 substance ; but when a particle of copper unites with a particle of sulphuric or 
 nitric acid, it is an instance of chemical affinity. The attraction of cohesion, 
 as well as the power of repulsion, which is opposed to it, are both opposed to 
 chemical attraction. A lump of sugar or salt is much more readily dissolved 
 if previously broken into pieces or pulverized, than if left in the solid form 
 which cohesion imparts to it. Chemical attraction has been distinguished into 
 three degrees or states of energy : the result of the lowest kind is mixture ; of 
 the second, solution; and of the third and most energetic, composition. Chemical 
 mixture takes place when the particles of two bodies are in a like state, and 
 the power of cohesion, with regard to them, so far suspended, as to admit of 
 that freedom of motion between themselves upon which fluidity depends ; thus, 
 two liquids or two aeriform fluids may admit of mixture, but two solids can be 
 chemically mixed only by diminishing their cohesion by means of heat to such 
 a degree as to bring one or both to the state of liquids. Between some fluids 
 there appears to be no attraction, and hence they do not admit of mixture ; 
 thus, if water and oil, or water and mercury be agitated together, they wil/ 
 separate as soon as they are allowed to remain at rest, the denser body occupying 
 the lower place; but sulphuric acid and water, or alcohol and water, have <t
 
 CHEMISTRY. 343 
 
 strong attraction for each other, and when mixed, do not separate by repose, 
 although the density of the ingredients materially differs. The atmosphere in 
 which we live and breathe is an example of the mixture of aeriform bodies : 
 it is composed of two gases oxygen and nitrogen, which are mingled with 
 surprising uniformity. They may be separated from each other, and the pro- 
 perties of the latter exhibited, by burning a little sulphur under a bell glass 
 over water. By this process the oxygen is removed, combining with the sulphur, 
 and the nitrogen remains. The properties of these gases will he discussed 
 hereafter under their respective names. Unlike liquids, all aeriform bodies have 
 the property of mixing together. This difference is considered to arise from a 
 modification of attraction between their constituent particles. In the case of 
 liquids not mixing, the attraction of cohesion between similar particles is pro- 
 bably greater than the chemical attraction between the dissimilar particles. In 
 gaseous bodies the attraction of cohesion does not appear to exist, and chemical 
 mixture operates unopposed. The expansive power of heat is opposed to 
 cohesion, and hence this attraction may be so far counteracted, that solid bodies 
 shall assume the fluid state, and may then be mixed together ; thus, melted tin 
 may be mixed with melted lead or copper, and their particles remain combined 
 after they have resumed the solid state. Chemical mixture may take place 
 between two bodies in any proportion. Equal measures of sulphuric acid and 
 water may be commingled, or a single drop of the former may be mixed with 
 a pint or a gallon of the latter, and the mixture will be uniform and perfect. 
 Chemical mixture is often attended by condensation or diminution of volume. 
 If equal measures of sulphuric acid and water are mixed, the mixture will not 
 fill two measures: this contraction is usually accompanied with an increase of 
 temperature. If four parts of sulphuric acid be suddenly mixed with one of 
 water, both at ordinary temperatures, the heat of the mixture will be higher 
 than that of boiling water. The properties of bodies are not essentially changed 
 by moisture ; in general, however, those of the more active prevail. A few 
 drops of sulphuric acid will communicate a sour taste to a quart of water. 
 The separation of liquid mixtures may be effected either by the addition or 
 subtraction of heat, arising from the unequal effect produced by this agent on 
 different bodies. By carefully applying heat to a mixture of alcohol and water, 
 the spirit will rise in vapour, and leave the water pure ; this process is called 
 evaporation. If the more evaporable fluid is condensed and received into a 
 separate vessel, it is termed distillation. This process may easily be performed 
 in a small way by using a retort 
 and receiver. In the annexed cut 
 a is the retort, containing the mixed 
 liquid, which may be spirit and 
 water, or a little wine or ale ; b is 
 the receiver, into which the neck 
 of the retort must pass through a. 
 cork ; c is the spirit lamp, which 
 furnishes heat for the distillation. 
 As soon as the heat is applied, the 
 spirit being more easily vapourized, 
 rises to the top of the retort, where, 
 being condensed into the liquid 
 state, it slowly trickles down the 
 
 spirit in its liquid 
 
 gaseous fluids are not separable by heat or cold, for they all expand equally by 
 equal additions of heat ; but steam, and other vapours, may be separated from 
 
 Cases by reduction of temperature, which destroys the elasticity of the forme), 
 ut not of the latter. The second degree of chemical attraction is solution, 
 which operates between solids and liquids, or gases and liquids; the liquids, in 
 these cases, are called solvents. Between some liquids and solids attraction
 
 344 CHEMISTRY. 
 
 does not exist, or it is overbalanced by the cohesive power. Resin and sealing 
 wax are insoluble in water, but readily dissolve in alcohol. Chemical attraction 
 may be exerted in different degrees between one body and several others. 
 There is an affinity between alcoliol and water, whereby they are capable of 
 mixing ; there is also a mutual affinity between alcohol and resin, by which the 
 former dissolves the latter ; but there is no affinity between water and resin. 
 Now, if water be added to a solution of resin in alcohol, the resin will resume 
 the solid form ; the attraction between the particles of alcohol and those of 
 water is greater than that between the particles of resin and alcohol : the 
 consequence is, that the alcohol quits the resin and combines with the water, 
 and the resin falls to the bottom of the liquid. This is called elective attraction, 
 because the alcohol may be considered as exercising a choice between the 
 substances with which it is capable of combining. This resumption of the 
 solid form by a body previously dissolved in a liquid, is termed precipitation. 
 The power of solution is limited, as liquids cannot combine with more than a 
 certain definite quantity of any solid or aeriform body. The point at which 
 the action between the two bodies ceases is called the point of saturation. Up 
 to this point the two bodies may combine in any proportions. A solvent that 
 has been saturated with one substance, is often capable of combining at the 
 same time with ethers ; thus water that is saturated with saltpetre will dissolve 
 a considerable quantity of common salt. The influence of heat upon the power 
 of solution corresponds with the difference between cohesion and elasticity. 
 Upon solid bodies it generally increases the power of the solvent by diminishing 
 their cohesion. Upon aeriform bodies it diminishes the power by increasing 
 their elasticity. Solvents may be separated from the bodies with which they 
 are united by alterations of temperature. If a solution of alum or common 
 salt be boiled, the liquid will be dissipated in vapour, but the solid salt will 
 remain. If a solution of carbonic acid in water be frozen, the gas will escape 
 and the water remain in the solid state. The result of the highest degree of 
 chemical attraction is composition, which may take place between bodies under 
 every modification of cohesive attraction. Bodies that unite in this intimate 
 manner combine only in definite proportions, which are invariable in the same 
 compound. Combination usually produces a total change in the sensible pro- 
 
 C'es of the combining substances; and the process is generally accompanied 
 hange of temperature, to such an extent sometimes that light and heat 
 are emitted in abundance. If copper filings and sulphur be mixed togethei, 
 and heat applied as soon as the sulphur melts, a violent action will take place, 
 the copper will become red hot, and a black brittle body will be formed, with 
 properties totally different from those of its two ingredients. This compound, 
 which is the sulphuret of copper, is often found ready formed in mineral veins ; 
 but whether existing naturally, or formed by art, its composition is definite and 
 invariable. It is found to consist of 64 parts by weight of copper, and 16 of 
 sulphur. There is, however, another compound of copper and sulphur, in 
 which the proportions are 64 copper to 32 of sulphur. In this it will be seen 
 that the quantity of sulphur is exactly double of that which the first combi- 
 nation contains. This is a fact of common occurrence ; many bodies will unite 
 in two or three different proportions, but they are no less definite, each being a 
 multiple, or a submultiple, of the preceding; that is, it is double, triple, or 
 half, and so on. This is well illustrated in the compounds of mercury. If 
 this brilliant and fluid metal be agitated for a long time in contact with the 
 common air, it will unite with the oxygen of that mixture, and will be con- 
 verted into a black, insipid, insoluble powder, which consists of 200 parts of 
 mercury to 8 of oxygen. If instead of being agitated at common temperatures 
 with the air it be kept nearly boiling in it, it will be converted into a red 
 shining mass, endued with an acrid metallic taste, and which is soluble in 
 water, and poisonous. This consists of 200 parts of mercury, and 16 of 
 oxygen. Again, if mercury be rubbed in a mortar with sulphur, it unites 
 with a given proportion. If the mercury be poured into melted sulphur, 
 and strongly heated, a compound will be formed which rises in vapour, and 
 concretes on cooling into a brilliant red substance, known as cinnabar or
 
 CHEMISTRY. 315 
 
 vermilion. In this the quantity of sulphur is double of that in the preceding 
 compound. Another compound of mercury is the well-known medicine called, 
 calomel, which is formed by the union of the metal with a gas named chlorine. 
 The compound is heavy, white, tasteless, crystalline, and nearly insoluble in 
 water. It may be taken in doses of several grains without any effect but that 
 of a purgative. It is composed of 200 parts of mercury, and 36 of chlorine. 
 If, however, the mercury be made to combine with 72 parts of chlorine* it 
 produces corrosive sublimate, a semitransparent white mass, of an acrid, nau- 
 seous, metallic taste, soluble in water and alcohol, and highly poisonous. In 
 these examples, it will be seen that substances comparatively inert, may 
 produce by their union compounds of highly active properties ; and that a 
 compound of two bodies, which, in one proportion, if taken internally, will have 
 but a slight effect upon the animal frame, if united in a different proportion 
 will prove destructive to life. On the other hand, highly active bodies of 
 opposite properties will also produce, by their union, substances of a mild cha- 
 racter, and they are then said to neutralise each other. Sulphuric acid, or oil 
 of vitriol, is highly corrosive, and intensely sour. If brought into contact with 
 any substance stained with vegetable blue colours, as those of violets or litmus, 
 it instantly changes them to a bright red, a property which belongs to all the 
 acids. Barilla, or carbonate of soda, is a solid that is soluble in water, of a 
 hot, acrid, bitter taste. It changes the blue colour of vegetables to green, 
 which property is common to all alkalies. If into a solution of this substance 
 we carefully drop a portion of the former, a brisk effervescence will ensue, and 
 carbonic acid will be given off. If the experiment be performed with care, and 
 the affusion of the acid stopped the moment the effervescence ceases, the solu- 
 tion will be found to be warm, and possessed of properties totally different 
 from those of the acid or alkali from which they have been formed; "it will no 
 longer be sour, corrosive, acrid; or hot; it will have no action on vegetable 
 colours, and all the active properties of the original bodies are said to be neu- 
 tralised. The compound is slightly bitter, saline, and cooling. If part of the 
 water be evaporated by heat, a solid will be deposited in regular crystalline 
 forms, called sulphate of soda, or Glauber's salt. The operation of affinity, 
 which produces chemical composition, exists in a body in different degrees 
 towards other bodies ; and if to a compound of two bodies a third be pre- 
 sented which has a stronger attraction for either of the component parts than 
 they have for each other, a decomposition will take place, and a new compound 
 will result. Carbonate of soda is composed of carbonic acid and soda ; and in 
 the experiment above referred to, it is decomposed, the sulphuric acid uniting 
 with the soda, and the carbonic acid escaping in the gaseous state. In like 
 manner, if a solution of carbonate of soda be boiled with caustic lime, the car- 
 bonate of soda will be decomposed, the carbonic acid will quit the soda and 
 unite with the lime, forming carbonate of lime or chalk, and caustic soda will 
 remain in the solution. These affinities are conveniently represented in the 
 following diagrams : 
 
 I Carbonic acid. 
 
 Carbonate of soda \ 
 
 i boda. bulpuunc acid. 
 
 in i ___ 
 
 Sulphate of soda. 
 
 Carbonate of soda 
 
 Lime. 
 
 Carbonate of lime. 
 
 In these diagrams the substance at bottom is the new compound, which is pre- 
 cipitated, or thrown down, and that at the top either escapes or remains in 
 solution ; this action is called single elective affinity. If two compounds are
 
 346 CHEMISTRY. 
 
 brought together in solution, it not unfrequently happens that a process ot 
 double decomposition and composition occurs; that is, the two original bodies 
 are decomposed, and two new compounds produced, by a mutual interchange 
 of ingredients : this compound action has been named double elective affinity. 
 Decomposition, which cannot be effected by single, may by double elective 
 affinity. Sugar of lead, or acetate of lead, is a compound of acetic acid and 
 lead. White vitriol, or sulphate of zinc, is compounded of sulphuric acid and 
 zinc. If in a solution of acetate of lead we suspend a piece of metallic zinc, 
 
 we shall have an example of single elective affinity ; the acetic acid will act 
 upon the zinc, and the lead will resume its metallic state, and be precipitated 
 on the zinc in a beautiful arborescent form. But if a solution of acetate of 
 
 lead be mixed with a solution of sulphate of zinc, the acetic acid will unite 
 with the zinc, and, at the same instant, the sulphuric acid will combine with 
 the lead, forming an insoluble precipitate, which will fall to the bottom of the 
 vessel while the acetate of zinc remains in solution. The latter is an instance 
 of double elective affinity, and may be represented by the following diagram : 
 
 Acetate of zinc. 
 
 I" Acetic acid. Zinc. "j 
 
 Acetate of lead. < . I Sulphate of zinc. 
 
 (.Lead Sulphuric acid.) 
 
 Sulphate of lead. 
 
 Here the original substances are placed on the right and left of the diagram, 
 while the new compounds occupy the top and bottom. 
 
 Having given a general view of the nature of chemical attraction, we shall next 
 proceed to sketch the most important facts as connected with this subject relative 
 to light, heat, and electricity. The phenomena resulting from the motion of light 
 will be found in the article OPTICS; we shall, therefore, in the present sketch, 
 refer to the mechanical properties of light only so far as is necessary to render its 
 chemical effects intelligible. When a pencil of light is admitted through a hole in 
 a window shutter into a darkened room, and made to fall on a triangular glass 
 prism, it is turned out of its natural or straight-lined direction, and prevented 
 from falling on the floor, where it would produce a spot of white light, instead 
 of which it forms a spectrum of splendid colours on the wall, or on a screen 
 placed to receive it. From this circumstance it appears that light is compound 
 and separable by means of an inequality in the refrangibility. In the annexed 
 diagram a b represents a ray of light, 
 which falling on the prism e, is diverted 
 from its course, and dispersed into 
 colours occupying the space c d. The 
 colours, proceeding from the bottom, 
 are red, orange, yellow, green, blue, 
 indigo, and violet, according to Sir 
 Isaac Newton's observation ; but some 
 modern observers state that there are 
 only red, -green, blue, and violet, in 
 the spectrum, when it is formed as it 
 should be, with a very small pencil of * 
 light. The violet occupying the upper part of the spectrum, is most diverted 
 from its course, and is said, therefore, to be the most refrangible. The red is 
 the least refrangible. This effect is very similar to that of elective attraction, 
 for the same glass acts with different force on different rays ; and this analogy 
 is extended by the observation that different kinds of glass, as well as other 
 substances, disperse light in different proportions. If these differently coloured 
 rays of light thus separated by the prism be concentrated on one spot by means 
 of a lens, they will reproduce colourless light. If the spectrum produced, as 
 we have stated, be minutely examined, it will be found to have different pro- 
 perties in different parts. Thus the red end will most sensibly aTect the
 
 CHEMISTRY. 347 
 
 thermometer; the lightest green rays are most illuminative, and the violet end 
 produces the most decided chemical changes. If the white luna cornea, the 
 muriate of silver, be moistened and exposed to the different rays in the pris- 
 matic spectrum, it will be found that no effect is produced upon it in the least 
 refrangible rays, which occasion heat without light. A slight discolouration 
 will be occasioned by the red rays, but the blackening power will be greater in 
 the violet than in any other ray ; and beyond the violet, in a space perfectly 
 dark, the effect was still perceptible This observation shows that there are 
 rays more refrangible than those which produce heat and light. Sir H. Davy 
 found that a mixture of chlorine and hydrogen acted more rapidly upon each 
 other, combining without explosion, when exposed to the red, than when placed 
 in the violet rays ; but that solution of chlorine in water became solution of 
 muriatic acid most rapidly when placed in the most refrangible rays of the 
 spectrum. He also observed that the puce-coloured oxide of lead, when mois- 
 tened, gradually gained a tint of red in the least refrangible rays, and 
 at last became black, but was not affected in the most refrangible. The 
 same change was produced by exposing it to a current of hydrogen gas. 
 
 Dr. Wollaston found that guaiac, exposed to the violet rays, passed rapidly 
 from yellow to green. MM. Gay Lussac and Thenard applied the same 
 influence to a gaseous mixture of hydrogen and chlorine, when an explosion 
 immediately took place. By placing small bits of card, coated with moist horn 
 silver, or little phials of those mixed gases, in different parts of the spectrum, 
 M. Berard verified the former observations, of the chemical power acquiring its 
 maximum in the violet ray, and existing even beyond it ; but he also found by 
 leaving the tests a- sufficient time in the indigo and blue rays, a perceptible 
 effect was produced by them also. He concentrated by a lens all that portion 
 of the spectrum which extends from the green to the extreme boundary of the 
 violet, and by another lens he collected the other half of the specti'iim, com- 
 prehending the red. The latter formed a focus of white light so brilliant that 
 the eye could not endure it, yet in two hours it produced no sensible effect on 
 muriate of silver. On the contrary, the focus of the other half of the spectrum, 
 whose light and heat were far less intense, blackened the muriate in ten minutes. 
 The sun beams, in traversing a coloured glass, produce similar effects. Thus, 
 the chloride of silver acquires a black tint behind a blue or violet glass, but 
 does not blacken behind a red or orange glass. On the other hand, it becomes 
 red behind a red glass, and that much more quickly than even in the solar 
 spectrum. With respect to the light emitted by gases, even the bright light of 
 olefiant gas, when concentrated so as to produce a sensible degree of heat, 
 occasioned no change on the colour of muriate of silver, nor on a mixture of 
 chlorine and hydrogen ; while the light emitted by electrized charcoal speedily 
 affects the muriate, and causes these gases to unite rapidly, and sometimes with 
 explosion. Sii H. Davy has remarked, that the refraction and effects of the 
 solar beam offer an analogy to the agencies of electricity. In the voltaic 
 circuit, the maximum of heat seems to be at the positive pole, where the 
 
 Grer of combining with oxygen is given to bodies, and the agency of rendering 
 ies inflammable is exerted at the opposite surface ; and similar chemical 
 effects are produced by negative electricity, and by the most refrangible rays of 
 the solar beam In general, in nature, the effects of the solar rays are very 
 compounded. Healthy vegetation depends upon the presence of the solar 
 beams, or of light; and whilst the heat gives fluidity and mobility to the 
 vegetable juices, chemical effects likewise are occasioned oxygen is separated 
 from them, and inflammable compounds formed. Plants deprived of light 
 become white, and contain an excess of saccharine and aqueous particles, and 
 flowers owe the variety of their hues to the influence of the solar beams. Even 
 animals require the presence of the rays of the sun, and their colours seem 
 materially to depend upon the chemical influence of these rays ; a comparison 
 between the polar and tropical animals, and between the parts of their bodies 
 exposed, and those not exposed to light, shows the correctness of this opinion. 
 Light is produced in several natural operations, most of which may be con- 
 sidered in this place. If two pieces of quartz be rubbed together, light is
 
 348 CHEMISTRY. 
 
 produced even under water. Atmospheric air, or oxygen, quickly and violently 
 compressed in a glass syringe, or a glass ball rilled with the latter, and suddenly 
 broken in vacuo, produces light. Light accompanies intense heat. Air heated 
 up to 900 Fahr. and made to fall on pieces of metal, earth, &c. communicates 
 to them the power of radiating light. The flame exhibited in the burning of 
 charcoal and phosphorus is merely the ignition of the solid particles of these 
 bodies. At a certain elevation of temperature, about 800 of Fahr., all solid 
 bodies begin to give out light, and the same effect is produced in vacuo by 
 transmitting voltaic electricity through a metallic wire. The phosphorescence 
 of minerals is another source of light. If fluor spar be coarsely pounded and 
 placed upon a mass of iron heated below redness, it will give out a beautiful 
 green light; this property is possessed by quartz, topaz, phosphate of lime, and 
 a variety of other minerals. There is also a class of bodies called solar 
 phosphoric, which emit light upon exposure to any highly luminous body ; the 
 most powerful of these is a compound discovered by Canton. If three parts of 
 calcined oyster shells in powder are mixed with one of flour of sulphur, and 
 the mixture rammed into a crucible, and ignited for half an hour, we shall find 
 that the bright parts, on exposure to the sun-beam, or to the common daylight, 
 or to an electric explosion, will acquire the faculty of shining in the dark so as 
 to render visible the figures on the dial-plate of a watch. After a while they 
 will cease to shine ; but if the powder be kept in a well corked phial, a new 
 exposure to the sun-beam will restore the luminescence. When an electric 
 discharge is transmitted along the surfaces of certain bodies, a somewhat durable 
 phosphorescence is occasioned ; thus 
 
 Sulphate of barytes gives a bright green light. 
 
 Acetate of potash . . . brilliant green light. 
 
 Succinic acid ditto, more durable. 
 
 Loaf sugar ditto. 
 
 Selenite ditto, but transient. 
 
 Rock crystal red, and then white. 
 
 Quartz dull white light. 
 
 Borax faint green light. 
 
 Boracic acid bright green light. 
 
 Canton's pyrophorous produces more light by this treatment than any other 
 body, but nearly every native mineral, except metallic ores and metals, become 
 luminous by an electric explosion. Light is also emitted in certain chemical 
 changes, where no sensible heat is perceived. Marine animals, both living and 
 dead, emit light ; as the shell fish called pholas, the medusa phosphorea, and 
 other molluscse. When deprived of life, marine fishes in general seem to abound 
 in this kind of light ; among insects, also, several species offulgora, or lantern- 
 fly, and of lampyris, or glow-worm. Rotten wood and peat earth also emit light 
 copiously. This luminous matter may be separated from the bodies of animals 
 by immersing them for a short time in dilute saline solutions; one part of 
 sulphate of magnesia in eight of water is the most convenient menstruum for 
 this purpose. Fresh water, spirit of wine, and dilute acids, destroy the luminous 
 property altogether, while a gentle heat, and oxygen gas, increase the brightness 
 of the phosphorescence. 
 
 The next important agent in chemical investigations is heat. Many chemists 
 have considered heat or caloric as a material substance, capable of entering into 
 combination with all other kinds of matter ; but recent investigations seem to 
 put it and light upon the same ground, and show them to be but certain states 
 of matter, brought about by the undulations of an exceedingly subtile ether, 
 which is considered to fill all the space in the universe not occupied bv other 
 matter. Heat appears to be an antagonist principle to attraction ; while the 
 latter binds together, the former tends to separate, the parts of bodies, first 
 expanding them, then reducing them to the liquid state, and finally to that 
 of gas or vapour. Sometimes it decomposes a body, separating it into its 
 proximate or ultimate elements : so powerful, indeed, is heat as a repulsive
 
 CHEMISTRY. 349 
 
 agent, that there can be no doubt that, if the temperature of the globe were 
 sufficiently increased, every solid mass on its surface would become liquid, and 
 every liquid assume the state of vapour. We have an illustration of this con- 
 sequence in the different states of the same body on different parts of the earth's 
 surface. Thus some bodies, as butter, oil, water, &c. which exist only as solids 
 at the poles of the earth, are perfectly liquid at the equator. Ether, which is 
 a liquid in this latitude, can only exist as a vapour in the torrid regions of the 
 earth. Mercury also, which we see always in the liquid state, may, by 
 exposure to the intense cold of a northern sky, be converted into a solid 
 metal like lead. The most immediate and general effect of heat is expansion. 
 If a poker or an iron ball be placed in a fire, it becomes heated, and assumes that 
 state which is called ignition ; at which time its temperature is nearly equal to 
 that of the surrounding fuel. In like manner, if a cup of cold water be placed 
 within a vessel of hot water, the two speedily become of the same temperature, 
 the one giving out caloric, and tin; other receiving it. If now either of these 
 bodies that have changed their temperature be examined, it will be found to have 
 changed its bulk also. This expansion of bodies by heat, and their consequent 
 contraction by cold, are facts of the highest importance in the arts. The amount 
 of expansion in different substances by a known increase of temperature, has 
 therefore been carefully studied, and a variety of results, more or less accurate, 
 have been obtained by different experimentalists. The property of expansion 
 by heat, and contraction by cold, appears to belong to nearly all bodies upon 
 which experiments have been made; at least in that class of bodies which com- 
 pose the mineral kingdom, for among vegetables the effects of heat are so 
 mixed with other effects, that it is difficult to distinguish them. Some minerals, 
 too, as clay, and several metallic substances, have been considered as excep- 
 tions to the general law ; but a more minute investigation has shown that they 
 are only apparent. Clay contracts in consequence of the expulsion of mois- 
 ture, and the incipient fusion that occurs ; and some of the metals, as iron, 
 bismuth, antimony, in fusion, expand in the act of setting or solidifying, but 
 afterwards contract as they cool. The force with which bodies expand is so 
 great as to overcome every resistance that is opposed to it. The general fact 
 of the expansion of solid bodies by heat may be 
 seen by taking a metal cylinder a b that will just 
 fit into a gauge c d, and pass through a circular 
 hole e when cold. When made red hot, it will 
 be found so much enlarged as to be incapable of 
 passing through the hole, or fitting into the 
 gauge, thus proving that it has been enlarged in 
 all its dimensions. The cubic or solid expan- 
 
 sion is always three times greater than the 
 
 linear. For example, if the expansion of a rod 
 of steel be one-tenth of its length, the whole 
 expansion will be three-tenths of its bulk. The 
 expansion of liquids may be made evident by filling a Florence flask, or any 
 bottle with a narrow neck, with cold water, and then applying heat to it ; the 
 fluid will soon be observed to flow over the mouth of the bottle in consequence 
 of its increased bulk. This fact is also familiarly illustrated by means of an 
 ordinary tea-kettle, which, if it be quite filled with cold water, will be unable to 
 contain the increased bulk occasioned by heat, and will consequently discharge 
 a portion of its contents over the hearth long before the water reaches its 
 boiling point. The expansion of air may be shown by a similar apparatus. If 
 the flask full of air be inverted with its mouth under water, and the flame of 
 a lamp or candle be applied to it, the air will be expanded, and will be seen 
 escaping from the mouth of the flask in large bubbles. If the flame be 
 removed, the air will cool, gradually contract its dimensions, and the water 
 will rush up into the vessel to fill the space vacated by the air. The expansion 
 of solid bodies is ascertained by what is called a pyrometer, for the construction 
 of which see its name. The most general facts connected with expansion are 
 as follows: 1. Nearly all solids, liquids, and gases, are expanded by heat, anri 
 
 Y Y
 
 3.50 
 
 CHEMISTRY. 
 
 contracted by cold; and of these, the gases are most expansible, and solid 
 bodies least. 2. Different solids and liquids are differently expanded by the 
 same degree of heat, but gases and vapours are equally and equably expanded 
 by equal portions of heat. 3. In the same body, whether solid or liquid, the 
 expansion by a given quantity of heat, is greater at higher than at lower tem- 
 peratures ; but in gases and vapours, the expansions are equal, by equal addi- 
 tions of heat at all temperatures. 4. The expansion of atmospheric air, gases, 
 and vapours, not in contact with the liquids from which they have been gene- 
 rated, is equal to one four hundred and eightieth part of the bulk they occupy at 
 32 of Fahrenheit's thermometer. The absolute dilatation in length of several 
 of the most generally used substances, is shown in the following table 
 
 Glass tube 
 Platina . 
 Iron . . 
 Steel . . 
 Gold . . 
 Copper . 
 
 i 
 
 1148 
 
 rial 
 i 
 
 846 
 1 
 
 57 
 
 Brass 
 Silver 
 Tin 
 Lead 
 Zinc . 
 
 Glass from 32 to 212 of the thermometer 
 
 Ditto 212 to 392 
 Ditto 392 to 572 
 
 I 
 
 535 
 
 1 
 524 
 
 1 
 
 402 
 
 3JH 
 I 
 
 310 
 
 1089 
 987 
 
 Alcohol 
 
 Nitric acid (sp. gr. 1.4) . 
 Fixed oils . . . <*.;{ 
 Oil of turpentine . . . 
 Sulphuric ether . . . 
 Sulphuric acid (sp. gr. 1.85) 
 
 Expansion of liquids in bulk. 
 
 Muriatic acid (sp.gr. 1.137) 
 
 Water saturated with salt 
 
 Water 
 
 Mercury 
 
 Apparent expansion of 
 mercury in glass . 
 
 One of the most important applications of the expansibility of liquids, is in 
 the construction of the thermometer, which consists essentially of a closed tube, 
 containing a liquid, the expansion of which can be conveniently observed. To 
 construct a thermometer, a glass tube of very small bore is usually taken, and 
 a bulb, globular, cylindrical, or conical, is blown at one end, which bulb and 
 part of the tube are then filled with perfectly pure mercury. The tube must 
 then be hermetically sealed by melting the top by means of a blow-pipe flame. 
 Previous to closing the top, however, the mercury must be exposed to heat so 
 as to completely fill the tube ; and while the tube is full, the sealing must be 
 effected. When the mercury cools, the surface will subside, and a vacuum will 
 be left in the upper part of the tube. The thermometer is then complete, 
 except its graduation ; this is accomplished as follows : The bulb is to be plunged 
 into snow or ice that is just melting, and a mark made on the tube at the point 
 at which the mercury stands ; this is called the freezing point ; and in the thermo- 
 meters common in this country, called Fahrenheit's (from the inventor's name), 
 it is marked 32. The tube must next be placed in boiling water, or its steam, 
 in such a way that the whole of the mercury may be exposed to heat. When 
 the mercury has risen and is stationary, another mark must be made ; this 
 denotes the boiling point of water, and is marked 212. The space between 
 the boiling and freezing point? must next be divided into 180 equal parts, and 
 the graduation is complete. In the centigrade thermometer used in France, 
 the freezing point is marked 0, and the boiling point 100, the intervals being
 
 CHEMISTRY. 351 
 
 divided into 100 equal parts or degrees. One degree of Fahrenheit is there- 
 fore equal to four-ninths of the centigrade ; and one of the centigrade to nine- 
 fourths, or 2i Fahrenheit. This is but a brief and general view. For further 
 information, see THERMOMETER. 
 
 It has been already stated that fluidity is the result of heau Every solid 
 may be liquefied ; and many of them, as well as liquids, may be vaporized at 
 a certain elevation of temperature ; and there can be little doubt that every 
 known liquid may be solidified if we possessed the means of sufficiently 
 reducing the temperature. Several of the gases, by the united operation of 
 cold and pressure, have already been reduced to the fluid state, and nearly every 
 known liquid may be frozen. The temperature at which a solid body assumes the 
 liquid state is palled its fusing or melting point. If the substance be ordinarily 
 in the liquid state, this point will be its freezing, concreting, or congealing point. 
 The concreting or congealing temperatures of various substances will be found 
 in the following table : 
 
 Deg. Deg. 
 
 Sulphuric ether 46 
 
 Liquid ammonia .... 46 
 
 Nitric acid (sp. gr. 1.424) . 45.5 
 Ditto (sp.gr. 1.329) . 2.4 
 Sulphuric acid (sp.gr. 1.8376) 1 
 Common salt 25 -f- water 75 . 4 
 Ditto 22.2 + ditto 77.8. 7.2 
 
 Oil of turpentine .... 14 
 
 Strong wines 20 
 
 Blood 25 
 
 Commonsalt4.16-fwater9.584 27.5 
 
 Milk 30 
 
 Water 32 
 
 Olive oil 36 
 
 Sulph. and plus., equal parts 40 
 Sulphuric acid (sp. gr. 1.78) . 46 
 
 Tallow 92 
 
 Phosphorus 108 
 
 Spermaceti 112 
 
 Potassium 136.4 
 
 Yellow wax 142 
 
 White wax 155 
 
 Sodium 194 
 
 Sulphur 218 
 
 Tin 442 
 
 Bismuth 476 
 
 Lead 612 
 
 Zinc . .680 
 
 The temperature at which bodies melt is fixed, but the congealing point is 
 modified by circumstances. Many liquids may be cooled considerably below 
 their usual freezing points, before they assume the solid state. This is the case 
 with water, which may be cooled 10, or even 20 below its congealing point 
 without freezing ; but if a small spicula of ice be dropped into it, or the water 
 caused to vibrate, it will instantly solidify. The same phenomena occur with 
 saline solutions. A hot saturated solution of sulphate of soda may be cooled 
 to 50" under a film of oil, and it will remain liquid, and bear to be moved 
 about in the hand without any change ; but if the vessel containing it be placed 
 on a vibrating table, crystallization will instantly take place. One remarkable 
 fact attends the cooling of bodies below their usual freezing point ; viz. at the 
 instant solidification occurs, the temperature of the mass rises to the proper 
 freezing point. Thus, if a portion of water be placed in an atmosphere of 21, 
 tne liquid will cool and remain fluid at this temperature, till, by touching it 
 with a piece of ice, or causing it to vibrate, we make it freeze, when it instantly 
 rises to 32, or 11 above the surrounding medium. This curious fact was first 
 explained by Dr. Black, and gave rise to the knowledge of the latent heat or 
 caloric of fluidity of bodies. Dr. Black suspended two glass globes, of the same 
 size, near each other ; the one filled with ice at 32, the other with water at 
 33: in half an hour the water had risen to 40, but it took ten hours and a 
 half to liquefy the ice, and heat the resulting temperature to 40. In this 
 experiment we observe that 7 of heat entered the globe in 1 half-hour, but 
 21 half-hours were required to melt the ice and raise its temperature to 40. 
 If from the product 7 X 21=147, we subtract 7, which the water was above 
 33, we have 140 as the measure of a quantity of heat that has entered the sub- 
 stance without being appreciable by the thermometer. Another simple experi- 
 ment, showing the same result, is made by mixing a pound of pulverized ice 
 at 32, with a pound of water heated to 172 ; the ice is instantly melted, but 
 the temperature is only 32. Here, then, 140 of heat have disappeared with- 
 out raising the temperature. From this circumstance, the quantity of heat that
 
 352 
 
 CHEMISTRi. 
 
 always disappears when a body assumes a fluid state, is called latent heat, or 
 caloric of fluidity. The latent heat of different substances varies, as may be 
 seen in the following table by Dr. Irvine : 
 
 Sulphur 
 Spermaceti . 
 Lead . . 
 Bees' wax . 
 
 143.68 
 145 
 162 
 175 
 
 Zinc 493 
 
 Tin 500 
 
 Bismuth ... . 550 
 
 The quantity of heat that disappears in the liquefaction of solids, explains the 
 origin of that cold which always accompanies solution, and enables us to apply 
 the process of artificial cooling by what are termed freezing mixtures. Snow 
 and salt, when rapidly mixed, dissolve and produce a reduction of temperature 
 equal to 38. The more rapid the liquefaction the greater the cold ; hence, if 
 the snow and salt be placed in a pan over the fire, and a glass tube containing 
 water be immersed in it, the water in a few seconds will be found frozen. The 
 solution of all crystallized salts is attended with a depression of temperature, 
 which in general increases with the solubility of the salt ; the like occurs with 
 certain metals. If a solid amalgam of bismuth be mingled with a solid amalgam 
 of lead, they become fluid, and the thermometer sinks. A variety of experiments 
 have been made on the frigorific effects of different mixtures, some of which 
 are stated in the following table, abridged from Mr. Walker's Experiments on 
 Frigorific Mixtures. 
 
 1. Frigorific Mixtures without Ice. 
 
 Mixtures. 
 
 Parts. 
 
 Thermometer sinks. 
 
 Degree 
 of cold 
 produced 
 
 Muriate of ammonia . . 
 Nitrate of potash . . . 
 Water ; 
 
 5 
 
 5 
 16 
 
 From 50 to 10 . 
 
 40 
 
 
 Sulphate of soda . - ' 
 Diluted nitric acid . 
 
 3 
 2 
 
 From 50 to 3. 
 
 53 
 
 Nitrate of ammonia . . 
 Water 
 
 1 
 1 
 
 From 50 to 4. 
 
 46 
 
 
 Sulphate of soda .... 
 Diluted sulphuric acid . . 
 
 5 
 4 
 
 From 50 to 3. 
 
 47 
 
 2. Frigorific Mixtures with Ice. 
 
 Snow or pounded ice . . 
 Muriate of soda .... 
 
 2 
 1 
 
 From any temperature to 5. 
 
 
 Snow 
 Diluted nitric acid . . . 
 
 7 
 4 
 
 From 32 to 30. 
 
 62 
 72 
 
 Snow .... 
 
 4 
 5 
 
 From 32 to 40. 
 
 Muriate of lime .... 
 
 Snow 
 
 2 
 3 
 
 From 15 to 68. 
 
 53 
 
 Muriate of lime .... 
 
 
 8 
 10 
 
 From 68 to 91. 
 
 23 
 
 Diluted sulphuric acid . . 
 
 Similar phenomena to those that take place in liquefaction, occur in vapor- 
 izing any liquid. If a vessel of water be placed over the fire, a sound is pro-
 
 CHEMISTRY. 353 
 
 duced by the successive vaporization and condensation of the particles in 
 contact with the bottom of the vessel. As the liquid increases in heat, the 
 sound becomes louder till it terminates in ebullition. At this point the tem- 
 perature ceases to rise, and remains stationary till the whole of the liquid is 
 evaporated. To ascertain the quantity of heat consumed in vapourizing a 
 given quantity of water, Dr. Black set a tin cup full of water at 50 on a red 
 hot iron plate ; in 4 minutes it reached the boiling point, and in 20 minutes 
 more it was all boiled off. From 50 to 212 the rise is 162, which was gained 
 in 4 minutes ; but it took five times as long to be converted into vapour ; hence 
 162 X 5=810 is the quantity of heat that disappears, or is rendered latent in 
 the conversion of water into steam. By subsequent experiments, the latent 
 heat of steam is found to be 967, or 1 ,000. The point at which liquids emit 
 vapour of equal tension with the atmosphere, which is their true boiling point, 
 differs in different liquids, as may be seen in the following table : 
 
 Boiling points. 
 
 Ether (spec. grav. 0.7365, at 48) 100 
 
 Alcohol (spec. grav. 0.813) 173.5 
 
 Nitric acid (spec. grav. 1.500) 210 
 
 Water 212 
 
 Saturated solution of sea salt 224 
 
 Muriatic acid (spec. grav. 1.094) 232 
 
 Ditto (spec. grav. 1.16) 220 
 
 Oil of turpentine 316 
 
 Sulphuric acid (spec. grav. 1.3) 240 
 
 Ditto (spec. grav. 1.848) 600 
 
 Phosphorus 554 
 
 Sulphur 570 
 
 Linseed oil 640 
 
 Mercury 656 
 
 The boiling point of the same liquid varies with the atmospheric pressure, and 
 also with the vessel the liquid is boiled in. Thus, in silver, the boiling point 
 was found to be 21 1.775, in common earthenware, 213.8, at the mean pressure 
 of the atmosphere. If the whole of the pressure be removed, liquors will boil 
 and assume the vaporous state at 124 below their ordinary boiling points. 
 Thus water will boil in vacuo at 88, instead of 212 ; and alcohol, at 49. On 
 this principle Dr. Wollaston constructed his thermometric barometer, for mea- 
 suring heights. He found that a difference of 1 in the boiling point of water 
 is occasioned by a difference of pressure equal to 0.589 of an inch on the 
 barometer. If water be heated in a close vessel, or under extraordinary pres- 
 sure, its temperature may considerably exceed 212; and as the steam will be 
 always of the same temperature as the liquid, and will have its elasticity 
 increased by heat, the vapour produced will considerably exceed the atmo- 
 sphere in elasticity, giving rise to what is called high pressure steam. At the 
 freezing point of water, the vapour that rises will have sufficient elasticity to 
 balance two-tenths of an inch of mercury in the barometer; at 212 it equals 
 the atmospheric pressure (about 30 inches). Its elasticity at some other tem- 
 peratures is stated in the following table : 
 
 Temperature. Pressure. 
 
 40 0.25 inches. 
 
 80 1.01 
 
 100 1.86 
 
 135 5.07 
 
 170 . 12.05 
 
 205 25.00 
 
 212 30.00 =1 atmosphere. 
 
 248 ........ 60.00 =2 ditto. 
 
 273 90.00 =3 ditto. 
 
 290 ........ 120.00=4 ditto. 
 
 305 , J . , . 150.56=5 ditto.
 
 354 
 
 CHEMISTRY. 
 
 A pint of water at 40, on being converted into steam, forms l,69i pints ; or 
 in round numbers, 1 cubic inch of water will form 1,728 inches, or 1 cubic 
 foot of steam. We have already observed that the latent heat of steam is about 
 1,000. This may be ascertained by evaporating a given weight of water, and 
 condensing it in to a known weight 
 of cold water. This may be illus- 
 trated by an apparatus similar to 
 the annexed cut. A given weight 
 of water may be evaporated from 
 the vessel a, the vapour of which 
 will pass along the pipe c, and be 
 condensed in the water in b. It 
 will be found that the steam will 
 raise the temperature of the 
 water in b six or seven times 
 more than an equal weight of 
 boiling water would do. By ex- 
 perimenting in this manner, Dr. 
 Ure has ascertained the latent 
 heat of several vapours, as in the annexed table : 
 
 Latent heat. 
 
 1000 
 457 
 312.9 
 
 Vapour of water at its boiling point . . 
 
 ,, alcohol (spec. grav. 825) . 
 
 ether (boiling point 112) -- 
 
 petroleum /.>;,:, . 183.8 
 
 oil of turpentine . " 183.8 
 
 nitric acid (spec. grav. 1.494) . . 550 
 
 liquid ammonia (spec. grav. 0.978) . 865.9 
 
 vinegar (spec. grav. 1.007) . . . 903 
 
 From the above table it will be seen that different bodies require different 
 quantities of heat to enable them to assume the vaporous state. An analogous 
 fact is, that different bodies require very different quantities of heat to elevate 
 their temperatures a given number of degrees. If a pound of water at 60 be 
 mixed with a pound of oil at 90, the resulting temperature will be 70 instead 
 of the mean 75 . And conversely, if a pound of water at 90 be mixed with 
 a pound of oil at 60, the temperature of the mixture will be 80 . In the first 
 experiment we see that the oil lost 20, while the water only acquired 10 ; and 
 in the second the oil gained 20, while the water lost only 10. Hence the 
 specific heat of water is double that of oil ; or the same quantity of heat that 
 will raise the temperature of oil 20, will only raise that of water 10. The 
 same fact may be shown' by placing mercury, oil, and water, in an oven ; the 
 mercury will be first heated, next the oil, and lastly, the water. An important 
 practical illustration of the doctrine of specific heat is afforded by atmospheric 
 air. The specific heat of air diminishes more slowly than its specific gravity. 
 When air is expanded to a quadruple volume, its specific heat is 0.540 ; and 
 when expanded to eight times the volume, its specific heat is 0.368. The den- 
 sities 1, J, J, |, correspond nearly to the specific heats 5, 4, 3, 2. Hence may 
 be explained the intense cold that prevails at the tops of high mountains, and 
 also the great heat developed in the compression of gases. A compression 
 equal to four-fifths is sufficient to ignite tinder ; and if a syringe of glass be 
 used, a vivid flash of light is seen to accompany the compression. 
 
 We have now alluded to most cf the phenomena of heat that may be useful 
 in chemical investigations, except those which relate to the conduction and 
 radiation, which we shall briefly illustrate. 
 
 It is well known that if a bar of iron, as a poker, be placed in the fire, the 
 heat will in time be communicated to its remote end. It is also a matter of 
 common observation, that a hot mass of iron, or a vessel of hot liquid sus- 
 pended in a room, will gradually become cooler until it attains the temperature 
 of the surrounding medium. If we suppose a mass of iron, heated red hot, to
 
 CHEMISTRY. 355 
 
 be placed on a metallic pillar or support, in a still room, we shall find that it 
 will lose its heat in three distinct ways. 1. If the metallic support be felt, it 
 will be found to be hot, and we may consequently infer that a portion of the 
 heat has been conducted away by its means. 2. If the hand be held over the 
 hot body, considerably above it, a current of hot air will be perceived, which 
 must convey another portion of caloric from the hot body. 3. If the hand be 
 held at some distance from the side of the body, a distinct sensation of heat will 
 be experienced ; and as this occurs when the hot body is inclosed in a vessel 
 exhausted of its air, it is manifestly a different mode of cooling from the other 
 two : in fact, a variety of experiments render it evident that the heat is pro- 
 jected from the hot body in right lines on every side. In the first of these 
 modes of cooling, the heat is conducted slowly along the iron bar, which is 
 denominated a conductor ; and the process is called the conduction of heat. 
 In the second, the heat unites with the particles of air, and renders them speci- 
 fically lighter, in consequence of which they ascend, and another stratum of 
 cooler particles descend and occupy their place ; these in their turn become 
 expanded and rise, and thus a constant ascending current is maintained. 
 Caloric, therefore, is conducted from bodies in two ways ; it either imparts heat 
 to the adjacent particles, which impart it to the next, and so on, without change 
 of place, or it unites with the adjacent particles of the surrounding medium, 
 and is conveyed upwards by the increased levity which it occasions. The third 
 method of cooling in which the caloric is projected from the body in right 
 lines, is called the radiation of caloric. The communication of heat by con- 
 tact is manifest in solids and liquids, although in the latter it is chiefly propa- 
 gated by the ascent of heated particles. If different solids be taken, and have 
 one end exposed to a high temperature, one of them will become heated in a 
 shorter time than another. Thus, if a piece of copper or iron wire, 3 or 4 
 inches long, be held in the hand by one end, while a spirit lamp is applied to 
 the other, it will soon become so hot as to be intolerable ; while a glass tube, in 
 similar circumstances, may be held within an inch of the flame with little 
 inconvenience. The difference in the facility with which heat is transmitted 
 through bodies, will appear from the following table : 
 
 Conducting power. Conducting power. 
 
 Gold . . . . . 100 
 Platinum .... 98 
 
 Silver 97 
 
 Copper 89 
 
 Iron 37 
 
 Zinc 36 
 
 Tin 30 
 
 Lead 18 
 
 Marble 2.5 
 
 Porcelain . . . . 1.25 
 
 Brick earth ... 1 
 
 From this table it appears that the metals are the best conductors of heat, 
 though even among them there are striking differences. The different kinds 
 of wood have very little conducting power, and hence are well adapted for 
 handles to vessels that are exposed to heat. Bodies of a porous or spongy 
 nature, especially fibrous substances, as wool, silk, feathers, fir, &c. are the worst 
 conductors of heat ; and from this circumstance derive their value as articles of 
 clothing. It is, however, probable that the warmth of these substances is 
 attributable rather to the impediments they offer to the motion of the air than 
 from any inherent heat-retaining power. Confined air is a bad conductor of 
 beat ; and if a quantity of it be enclosed among the interstices of the fur, 
 wool, &c. it will furnish an effectual barrier to the egress of caloric. On this 
 account double windows and doors are found effectual in maintaining an equable 
 temperature in our apartments. The conducting power of liquids by contact is 
 so exceedingly small, that for a long time it was doubted whether they conducted 
 at all. Accurate experiments made in vessels of ice, have, however, established 
 the fact that liquids do conduct heat downwards, or by contact of their particles. 
 If it be desirable to heat a liquid, it is well known that the heat should be 
 applied at the bottom of the vessel, by which means the stratum of particles 
 nearest the fire becomes lighter, and ascends, being forced up by the descent of
 
 356 
 
 CHEMISTRY. 
 
 the colder, and therefore heavier parts. This process continues until the whole 
 has attained that degree of heat at which the liquid hoils ; the same occurs in 
 heating a confined portion of air. Any circumstance that tends to impede the 
 motion of the particles of liquids will diminish the facility with which they are 
 heated or cooled. Water-gruel, soups, and other thick drinks, retain their heat 
 for a considerable time; while more dilute liquids become cooled at the surface, 
 the cooler parts subside, and the hot ones rise and come into contact with the 
 atmosphere ; these become cooled and sink, and thus the process goes on till the 
 whole attains the same temperature as the surrounding medium. It has been 
 long known that the sun's rays proceed in right lines, and that they are capable 
 of being reflected and refracted by mirrors and lenses so as to produce an intense 
 heat. In like manner, if an iron ball be heated a little below redness, it will 
 be found to emit rays of heat that are capable of being reflected and re- 
 fracted in a similar way. If two concave and polished metallic mirrors 
 be placed opposite to each other, and at about eight or ten feet distant, 
 (as in the annexed engraving,) and the hot iron ball be placed in the 
 focus of one, as at a, while in that of the other we place a piece of phosphorus 
 b, resting on a lump of charcoal, or any bad conductor, in a few seconds the 
 
 phosphorus will inflame. Now to produce this effect, it is manifest that rays 
 of heat must have emanated from the iron ball, and falling on the nearer 
 mirror, must have been reflected to the second mirror, by which they have been 
 concentrated on the phosphorus. In this experiment we observe two important 
 facts, the radiation and reflection of heat. Radiation may be considerably 
 modified so as to be nearly destroyed by an alteration of the surface of the 
 radiating body. Instead of the hot ball, Sir John Leslie used a tin cubic 
 cannister filled with hot water ; and as a large body would stop the return of 
 the rays, he used only one mirror, in the focus of which he placed one of the 
 balls of his differential thermometer, as here represented. Previous to placing 
 the cubic canister a before the mirror b, its four vertical sides were coated with 
 different substances one with lamp-black, another with China ink, a third with 
 
 isinglass, while the fourth was left naked, presenting a surface of polished tin. 
 When this vessel, filled with hot water, was presented to the mirror, the ther- 
 mometer c immediately indicated an increase of temperature, varying according 
 to the surface presented ; the lamp-black surface depressed the liquid of the
 
 CHEMISTRY. 
 
 357 
 
 thermometer 100, the China ink 88, the isinglass 80, and the tin 12. By a 
 variety of similar experiments, Professor Leslie obtained the results in the fol- 
 lowing table : 
 
 Radiating power. Radiating powt.. 
 
 Lamp black . . 
 Water (by estimate) 
 Writing paper . . 
 Resin . . . 
 
 . 100 
 . 100 
 
 . 98 
 96 
 
 Isinglass . . .80 
 Plumbago . . .75 
 Tarnished lead . 45 
 Mercury . . 20 
 
 Sealing wax . . 
 Crown glass 
 China ink ... 
 Ice 
 
 . 95 
 . 90 
 
 . 88 
 
 . 85 
 
 Clean lead . . .19 
 Iron polished . .15 
 Tin plate . . .12 
 Gold, silver, copper . 12 
 
 The nature of the substance is not the only circumstance that influences 
 radiation. In general, the more smooth and polished the surface, the more 
 feeble in its radiating power. If the surface be roughened with a file, or other- 
 wise, its radiation is increased. It also appears that the radiation occurs not 
 only from the superficial particles, but also from those immediately beneath 
 them. With one coating of jelly it was found that the radiation was 38 ; 
 while a film of the same substance, four times thicker, produced a depression 
 of 54. When the thickness of the coating amounted to one-thousandth part 
 of an inch, the radiation became diminished. If the same radiating surface 
 be presented to different mirrors, we shall discover the differences in the 
 reflective powers. By various experiments of this kind, the reflective powers 
 of several substances were found to be as follows : 
 
 Reflective power. 
 
 Brass 100 
 
 Silver 90 
 
 Tinfoil 85 
 
 Black tin .... 80 
 
 Steel 70 
 
 Lead .... 60 
 
 Reflective power. 
 Tin foil softened with 
 
 mercury ... 10 
 
 Glass 10 
 
 Ditto coated with wax 
 
 or oil . ... 5 
 
 If we compare these tables, we shall find generally that the best radiators are 
 the worst reflectors, and vice versd. It may easily be inferred, that those bodies 
 that radiate most caloric, when heated above the temperature of the surround- 
 ing medium, will also absorb most rapidly when exposed to a temperature supe- 
 rior to their own. In the experiment with the lamp-black surface exposed to 
 the mirror, the thermometer indicated a temperature of 1 00 ; if, however, the 
 glass ball of the thermometer be covered with tin foil, the indication will be re- 
 duced to 20. In the same manner, if the bright side of the canister be pre- 
 sented, the temperature will be 12, but with the bulb covered, only 2. From 
 these experiments, as well as from reasoning, it is evident that the absorptive 
 power is equal to the radiating. Connected with this part of the subject is the 
 effect of screens. When a thin deal board was placed between the canister 
 and the focal ball, the thermometric effect was diminished, and this diminution 
 was proportional to the thickness of the screen. A pane of glass interposed 
 reduced the effect of radiation from 100 to 20. The reduction was greatest 
 when the screen was most distant from the canister : the thinnest gold leaf 
 stopped the whole of the heat ; in general, those bodies intercept heat most 
 effectually which are the worst radiators. From some more recent experiments 
 of M. de la Roche, it is found that caloric acquires a more penetrating power 
 as it proceeds from a source of higher temperature. A curious experiment was 
 made by the Florentine Academicians, in which, instead of the hot canister, 
 a large mass of snow was placed before the mirror : in this case the ther- 
 mometer indicated a rapid depression of temperature, and it was at first 
 inferred that rays of cold emanated from the snow and acted on the ther- 
 mometer ; this supposition is, however, unnecessary, for it may easily be shown 
 that all bodies radiate heat constantly. Even a mass of ice or snow may have its 
 temperature higher than the surrounding air, and will, therefore, produce signs
 
 358 
 
 CHEMISTRY. 
 
 of heat in the thermometer. In the experiment just cited, the snow radiates 
 caloric towards the mirror, and the thermometer, at the same time, radiates 
 towards it, which is reflected towards the snow. If the snow were not placed 
 in front of the mirror, the thermometer would receive as much caloric as it 
 emits, and hence its temperature would remain constant ; but as the temper- 
 ature of the snow is lower than that of the thermometer, the latter receives less 
 than it imparts, and its temperature falls. 
 
 Having stated the most important general facts connected with heat, we 
 must refer the reader to other articles in ihe work for more particular infor- 
 mation, under the words EXPANSION, THERMOMETER, PVROMETER, COMBUSTION, 
 &c. and proceed to another important agent in chemical research electricity. 
 
 If a glass tube, or a stick of sealing-wax, be briskly rubbed with a dry silk 
 handkerchief, and then presented towards small pieces of paper, feathers, or 
 gold leaf, it will first attract and then repel them. Or if a glass tube be taken 
 in one hand, and a stick of sealing-wax in the other, and each be rubbed, then 
 if the glass rod be brought near a piece of gold leaf floating in the air, it will 
 first attract, and afterwards repel it. While the gold leaf is repelled by the 
 excited tube, if the sealing wax be brought near, the leaf will be attracted, and 
 thus it will be seen that bodies electrified by glass will be attracted by the wax, 
 and vice vend. Bodies that are electrified by glass are said to be positively or 
 vitreously electrified ; and bodies submitted to excited wax are called negatively, 
 or resinously electrified. If either of the tubes are well excited, and a finger 
 be presented to it, a crackling noise will be heard, and in the dark, sparks of 
 light will be seen issuing from the tube ; these are termed electric sparks. If 
 to the further end of the excited tube a brass ball be attached by a wire, the 
 ball will possess all the qualities of the tube itself; but if it be connected by 
 means of silk, the electric virtues will not pass into it. From this circumstance 
 bodies have been divided into conductors and nonconductors. Some bodies 
 conduct or permit the passage of electricity more readily than others ; hence 
 arises the distinction of good and bad conductors. The following table contains a 
 list of conducting substances in the order of their conducting power. 
 
 Copper. 
 
 Silver. 
 
 Gold. 
 
 Iron. 
 
 Tin. 
 
 Lead. 
 
 Zinc. 
 
 Platinum. 
 
 Charcoal. 
 
 Plumbago. 
 
 Strong acid. 
 
 Soot, and lamp black. 
 
 Metallic ores. 
 
 Metallic oxides. 
 
 Dilute acid. 
 
 Saline solutions. 
 
 Animal fluid. 
 
 Water. 
 
 Ice and snow above 0*. 
 
 Living vegetables. 
 
 Living animals. 
 
 Flame. 
 
 Smoke. 
 
 Vapour, 
 
 Salts. 
 
 Rarefied air. 
 
 Dry earths. 
 
 Massive minerals. 
 
 The nonconductors or insulators are as follows : 
 
 Shell lac. 
 
 Amber. 
 
 Resins. 
 
 Sulphur. 
 
 Wax. 
 
 Asphaltum. 
 
 Glass, and all vitrified bodies. 
 
 Raw silk. 
 
 Bleached silk. 
 
 Dyed silk. 
 
 Wool, hair, and feathers. 
 
 Dry gases. 
 
 Dry paper and leather. 
 
 Dry woody fibre. 
 
 Porcelain. 
 
 Marble. 
 
 Massive earthy minerals. 
 
 Camphor. 
 
 Caoutchouc. 
 
 Dry chalk and lime. 
 
 Phosphorus. 
 
 Ice (below Fahr.) 
 
 Oils ; the densest are the best. 
 
 Dry metallic oxides.
 
 CHEMISTRY. 
 
 359 
 
 The worst insulators differ very little from the worst conductors, so that the 
 whole list, from copper to shellac, might be considered as one series, in which 
 different degrees of resistance are opposed to the passage of electric power. 
 The best conductors are sometimes called nonelectrics, and the best insulators 
 electrics, on the supposition that only the latter were capable of producing 
 electricity by friction. This appears to be erroneous, as even metallic bodies 
 may be excited if they are held by a nonconductor to prevent the electricity 
 being carried away as soon as produced. A similar mistake was originally 
 made with respect to the production of vitreous or resinous electricity. It was 
 thought that the same body always produced the same kind of electricity ; but 
 it is now known that this depends on the nature of the rubber. In all cases 
 where two bodies are rubbed together, if the one become vitreously electrified, 
 the other will be reslnously electrified. In the following table the several sub- 
 stances acquire vitreous electricity when rubbed with those which follow them, 
 and resinous when rubbed with those that precede them : 
 
 The skin of a cat. 
 
 Polished glass. 
 
 Woollen stuff, or worsted. 
 
 Feathers. 
 
 Dry wood. 
 
 Paper. 
 
 Silk. 
 Lac. 
 Roughened glass. 
 
 The early experimenters used only the glass tube for the excitation of elec- 
 tricity ; but the labour and insufficiency of this process soon gave rise to a 
 machine for the same purpose. 
 There are two kinds of elec- 
 trical machines now in use, 
 which are called the plate ma- 
 chine, and the cylinder machine. 
 The cylinder machine is shown 
 in the annexed figure, in which 
 a is a cylinder of glass, mounted 
 in a frame, so as to be turned on 
 its axis by means of the handle 
 /. At e is a cushion stuffed with 
 wool or horse-hair, and covered 
 with an amalgam of three parts 
 of mercury, two of zinc, and 
 one of tin, melted together. 
 Attached to the cushion is a 
 piece of silk c, which reaches 
 over the cylinder as far as the 
 prime conductor b. The prime 
 conductor b is a cylinder of 
 tin or brass, mounted on a glass leg d, and furnished with a row of points ex- 
 tended towards the cylinder, for the purpose of collecting the electricity gene- 
 rated by the friction of the cylinder against ~ 
 the rubber. The cushion is mounted on a glass 
 leg for the purpose of procuring resinous elec- 
 tricity ; but when only vitreous electricity is 
 required, a chain or piece of wire must be 
 attached to the cushion. The principle of the 
 plate machine is precisely similar to this ; but, 
 instead of a cylinder, a circular glass plate is 
 mounted, so as to turn on an axis passing 
 through its centre, while the rubbers are applied 
 near its circumference. When a greater quan- 
 tity of electricity is required than can be fur- 
 nished by sparks from the prime conductor, 
 an apparatus is used, which, from having been 
 discovered at Leyden, is called the Leyden Jar. In the engraving a represents 
 
 </
 
 36U 
 
 CHEMISTRY. 
 
 a glass jar coated within and without with tin foil, except near the top ; b is a 
 brass ball connected with the interior coating by means of a brass wire. When 
 the knob b is brought near the prime conductor of the electrical machine, sparks 
 pass into the jar, until it has become charged. A discharging rod c, furnished 
 with a glass handle d, is then applied, so that one ball touches the outer coating, 
 and the other the brass ball b ; the whole of the electricity then passes from the 
 inside to the outside of the jar, which is then said to be discharged. If, instead 
 of the discharging rod, a person applies his hands to the outer and inner sides 
 of the jar, the electricity passes through him, and he receives an electric shock. 
 If the electricity -be accumulated in a large jar, or if several jars are connected, 
 as in the accompanying sketch, they form an electric battery, and all the effects 
 
 produced by lightning may be imitated by means of it. If electricity be passed 
 through resin, phosphorus, ether, gunpowder, &c. it inflames them ; it will 
 penetrate a thick card or a quire of paper ; and if in sufficient quantity, will 
 destroy life in an eel, rabbit, dog, &c. Friction is not the only means of pro- 
 ducing electric indications, but it is the most energetic; and when we have 
 occasion to test the presence of electricity excited by other means, it is necessary 
 to use a delicate electrometer. One of these, called Bennet's electrometer, 
 shown in the accompanying sketch, consists of two small slips 
 of gold leaf suspended by a brass wire within a glass cylinder. 
 In the improved form of the instrument the wire which carries 
 the leaves a a passes through a plug of silk within a glass tube 
 b in the cap of the electrometer. By this instrument we are 
 enabled to perceive that electricity is excited in the fusion of 
 inflammable bodies, in evaporation, in the disengagement of 
 gas, by the sudden disruption of a solid body, by change of 
 temperature, by contact of dissimilar bodies. This latter has 
 been considered by Volta and others as the origin of voltaic 
 electricity, while some of our first chemists consider chemical 
 action to be the primary source of voltaic energy. Voltaic elec- 
 tricity is usually procured by an arrangement of copper and 
 zinc plates, called a voltaic battery. There are different forms of 
 this apparatus, but the battery of Cruikshank is, on the whole, the most convenient 
 This consists of a number 
 of zinc and copper plates, 
 soldered together at their 
 edges, and cemented into 
 grooves in the sides of a 
 mahogany trough. To 
 prepare the battery for ac- 
 tion, a liquid consisting of 
 about two parts of sul- 
 phuric acid one of nitric
 
 CHEMISTRY. 361 
 
 acid, and 100 of water, sfiouid be poured into the cells till they are nearly full; a 
 wire must then be inserted at each end touching the outer plates. The wire con- 
 nected with the zinc plate will give off positive electricity, and the wire attached 
 to the copper plate, negative electricity. The galvanic or voltaic battery is a 
 highly important agent in chemical research, both from its energetic decom- 
 posing power, and from the intense heat which it produces. If the two wires are 
 of platinum or gold, And are inserted into a glass of water, the water will be 
 decomposed into its elements, oxygen and hydrogen ; the oxygen will appear at 
 the positive wire, and the hydrogen at the negative If the ends of the wires dip 
 into two separate glasses of water, and a finger of each hand be immersed in 
 them, a slight electric shock will be felt, the intensity of which will increase witli 
 the number of plates. If the number of plates is very great, or if of large dimen- 
 sions, the phenomena are beautiful and striking. The battery of the Royal 
 Institution, used by Sir H. Davy, in his researches, contained 2,000 pairs of 
 plates, containing a surface of 1 28,000 square inches. When pieces of charcoal 
 about an inch long, and one-sixth of an inch in diameter, were brought within 
 one-thirtieth or one-fortieth of an inch of each other, a bright spark was pro- 
 duced, and more than half the volume of the charcoal became ignited to whiteness; 
 and by drawing back the points a little from each other, a constant discharge 
 took place through the heated air, in a space equal at least to four inches, pro- 
 ducing a most brilliant ascending arch of light, expanded and conical in the 
 middle. When any substance was introduced into this arch, it instantly became 
 ignited. Platinum melted in it like wax in the flame of a common candle. 
 Quartz, the sapphire, magnesia, lime, all entered into fusion. Fragments of 
 diamond, and points of charcoal and plumbago, rapidly disappeared and seemed 
 to evaporate in it, even when the connexion was made in a receiver exhausted 
 by the air pump ; but there was no evidence of their having previously under- 
 ne fusion. Copper and zinc are not the only metals proper for forming: a 
 
 gone fusion. Copper and zinc are not the only metals proper for forming i 
 galvanic battery, but they are the least expensive. The following tables by Sir 
 H. Davy will furnish a variety of combinations. The metal first named is 
 positive in reference to those that follow. 
 
 With Ordinary Acids. 
 
 Potassium and its amalgams ; barium and its amalgams ; amalgam of zinc ; 
 zinc ; amalgam of ammonium, cadmium, tin, iron, bismuth, antimony, lead, 
 copper, silver, palladium, tellurium, gold, charcoal, platinum, iridium, rhodium. 
 
 With Alkaline Solutions. 
 
 fhe metals of the alkali, and their amalgams, zinc, tin, lead, copper, iron, 
 silver, palladium, gold, platinum, &c. 
 
 With the Solutions of Hydro-Sulphurets. 
 Arrangements consisting of one Conductor and two Imperfect Conductors. 
 
 Solution of sulphur and potash 
 of potash . . ; . 
 
 Copper. 
 
 Silver. 
 Lead 
 
 Nitric acid. 
 Sulphuric acid. 
 
 
 Tin. 
 Zinc. 
 Other metals. 
 Charcoal. 
 
 ) Any solution contain- 
 ) ing acid. 
 
 The most splendid effects of the voltaic battery achieved by Sir H. Davy were 
 the decomposition of the alkalies and alkaline earths, as potash, soda, baryta, 
 strontia, lime, and magnesia. These were found to be composed of a brilliant
 
 362 
 
 CHEMISTRY. 
 
 substances for the convenience of study, and by its means they are divided into 
 two classes. The first consists of those elements which are attracted from their 
 compounds with substances of the other class, by the positive pole of the voltaic 
 pile; and as bodies in opposite states of electricity attract one another, they have 
 been called electro-negative bodies. The second comprises those elements that 
 are attracted by the negative pole, which are therefore termed electro-positive 
 bodies. Before giving a list of the simple substances, it will be necessary to 
 allude to the theory of equivalents. In an early part of this article we have 
 stated that different bodies combine in proportions that are fixed with regard to 
 each other in a given compound. We may now observe that these proportions 
 are definite with regard to every other substance with which they are capable 
 of entering into composition, so that there are certain determinate proportions 
 of all bodies which are equivalent to each other in their powers of combining 
 with all other bodies. Thus, acetate of lead is a compound of 50 parts of acetic 
 acid and 112 parts of lead, in the state of an oxide. White vitriol, or sulphate 
 of zinc, is composed of 40 parts of sulphuric acid and 41 parts of oxide of zinc. 
 Now these proportions are all equivalent to one another, and if the numbers are 
 written against the different substances as follows, we can at once perceive the 
 proportions in which they will unite in any new combination. 
 
 Sulphuric acid 40 
 
 Zinc (oxide) 41 
 
 Acetic acid 50 
 
 Lead (oxide) 112 
 
 The same equivalent numbers or their multiples are preserved in every possible 
 combination with other bodies ; and when any body is compounded of two 
 simple substances, the sum of the equivalents of the two elements will give the 
 number, denoting the proportion in which it will combine. Thus the prime 
 equivalent of hydrogen is 1, that of oxygen 8; these combine to form water, 
 the equivalent of which is 9. The following table contains the names of those 
 substances which being, in the present state of chemistry, undecomposable, are 
 considered as simple elementary bodies, classed in two divisions, and having 
 their equivalent or combining numbers attached. 
 
 Non-Metallic. 
 
 Electro-negative. 
 
 valenti. 
 
 Electro-positive. 
 
 Eqi- 
 valeots. 
 
 *{? : : : : 
 
 / Bromine .... 
 \ Iodine 
 Volatile. <[ 
 
 8 
 36 
 
 75 
 124 
 
 Hydrogen . . 
 Nitrogen . . 
 
 Sulphur . 
 
 1 
 
 14 
 
 16 
 
 
 
 Phosphorus . 
 
 12 
 
 I* :::'**: 
 
 
 Selenium . 
 
 40 
 
 c 
 
 
 Carbon . . . 
 
 6 
 
 Fixed. < 
 
 
 
 8 
 
 
 
 
 6 
 
 
 

 
 CHIMNEY. 
 
 363 
 
 Metallic Elements. 
 
 
 Electro-negative. 
 
 Eqni- 
 aleuts. 
 
 Electro- positive. 
 
 i; 
 
 
 
 
 Mercury . 
 
 200 
 
 
 
 
 Silver . . 
 
 110 
 
 
 
 
 Gold . 
 
 200 
 
 J -LI 1 
 
 
 
 Platinum . . 
 
 96 
 
 
 
 
 Palladium . . 
 
 56 
 
 
 
 
 
 44 
 
 
 
 
 Iridium 
 
 ? 
 
 
 
 
 
 f 
 
 
 
 
 Nickel . . . 
 
 30 
 
 
 
 
 Lead 
 
 104 
 
 
 ' 
 
 
 Tellurium 
 
 29 
 
 
 
 
 Conner 
 
 64 
 
 
 
 
 Bismuth 
 
 71 
 
 
 
 
 
 ? 
 
 Do not decompose 
 
 .... 
 
 
 Cobalt . . . 
 
 ? 
 ? 
 
 water at any tempera- 
 
 
 
 
 ? 
 
 ture. 
 
 
 
 
 44 
 
 
 
 
 
 144 
 
 
 
 
 Tungsten 
 
 96 
 
 
 
 
 
 28 
 
 
 
 
 
 48 
 
 
 
 
 
 38 
 
 
 r. 
 
 
 Tin .... 
 
 59 
 
 
 
 
 
 28 
 
 
 . 
 
 
 Zinc 
 
 34 
 
 
 ' 
 
 
 
 56 
 
 
 : : : : 
 
 
 
 28 
 
 
 
 
 
 40 
 
 Decompose water at 
 
 
 
 
 24 
 
 atmospheric temper- 
 
 
 
 
 10 
 
 atures. Oxides, caus- ^ 
 
 
 
 
 20 
 
 tic, (alkaline metals.) 
 
 
 
 
 70 
 
 
 
 
 
 44 
 
 
 !". 
 
 
 
 12 
 
 Decompose water below 
 
 
 
 
 20 
 
 a red heat, but oxides 
 
 ...... 
 
 
 Yttrium 
 
 34 
 
 insipid. (Earthy me- 
 
 : : : : : 
 
 
 
 10 
 
 tals). 
 
 
 
 Zirconium 
 
 ? 
 
 A particular description of the properties of these bodies, with the compounds 
 formed by their union with each other, will be found under the initial letter of 
 their respective names. 
 
 CHIMES. A piece of musical mechanism produced at equal intervals of 
 time by the strokes of a hammer against a series of bells. This is effected by 
 means of a chime-barrel, which is something of the nature of a barrel to an 
 organ. It is a cylinder of brass in small clocks, or of wood in church clocks, 
 which gives motion to the hammers that strike the bells, and produce a change 
 or tune by means of pegs inserted into certain points of its circumference at 
 measured intervals. 
 
 CHIMNEY. An aperture or passage for the escape of the smoke and 
 heated air from a furnace or fire-place, and for producing a more perfect com- 
 bustion by determining a rapid current of air through the fuel. The principle 
 upon which the action of a chimney depends, is, that the air in the chimney
 
 364 
 
 CHIMNEY. 
 
 becoming rarefied, its specific gravity is diminished, and the weight of tne 
 column of air within the chimney becoming less than the weight of a column 
 of the external air of the same altitude, the heated air in consequence escapes 
 at the top of the chimney, and is replaced by the colder and denser air, which 
 enters at the bottom. The greater, therefore, the height of the chimney, the 
 greater will be the effect; for the greater will be the difference in the weight of the 
 two columns of air. In Mr. Tredgold's work on warming and ventilating apart- 
 ments, the following rule is given for the orifices of chimneys according to the 
 height and magnitude of the fire-places. Multiply by 1 7 the length of the fire- 
 place in inches, and divide by the square root of the height of the chimney 
 (above the grate) in feet, and the quotient is the area in inches for the aperture 
 of the chimney. Mr. Hiort, of the Office of Works, Whitehall, has taken out 
 a patent for a new method of building chimney flues and tunnels, which has 
 been adopted in the new palace, Pimlico, and in several public buildings, and 
 has given great satisfaction. The plan consists in building within the usual 
 walls, and incorporated with the common brick-work, circular smoke flues or 
 tunnels, as seen in the annexed plan or horizontal 
 section at b. Each flue or tunnel is surrounded in 
 every direction, from top to bottom, by cavities or 
 hot-air chambers c c, commencing at the back of 
 each fire-place, and connected with each other. 
 The air confined within these chambers is said to 
 be rendered sufficiently warm by the heat of any 
 one fire, to prevent condensation in all the flues con- 
 tained in the same stack of chimneys. The figure 
 of each brick composing these circular flues a 
 wedge-like, or inclined, as respects its upper and 
 lower surfaces : the external face is composed of two planes, forming a very 
 obtuse angle with each other; and the internal, of the arc of a circle, to the 
 centre of which the two ends of the brick tend or radiate ; and the whole circle 
 is completed by placing four bricks together, end to end, as shown in the fore- 
 
 going plan. Their inclined figure is best shown in the engraving above, from 
 which it will likewise be seen that the flues or tunnels may be carried in nuv
 
 CPIIMNEYS. 
 
 365 
 
 direction without producing any internal angles, the bricks being read fly 
 adapted to any required curvature. To make the flue straight, it will be 
 pbserved that the thick ends of one 
 course of bricks are placed alternately 
 upon the thin ends of the next course; 
 and in order to make curves, the thick 
 ends are placed together on one side, 
 and the thin ends on the opposite side. 
 The circular flue commences at the 
 throat of the chimney below the usual 
 line of the chimney bar, and imme- 
 diately over the fire. From below the 
 chimney -bar the flue is continued 
 
 downward to the hearth in a half- 
 circle, forming the centre of the back 
 of the fire-place. From the construc- 
 tion of these chimneys, and the nature 
 of the materials of which they con- 
 sist, no danger need be apprehended 
 should the soot ignite (an accident not 
 likely to happen), for such an accu- 
 mulation of soot as common chimneys 
 are liable to cannot take place within 
 these flues, there being no angles 
 within which it can lodge, the 
 draught of air being much stronger 
 through them, and the necessity for 
 cleansing them may be rendered less 
 frequent by vitrifying the inside of the 
 bricks to prevent adhesion ; never- 
 theless, the operation of cleansing may 
 with facility oe performed without the 
 aid of climbing boys, all sharp angular 
 turns, and other impediments which 
 have hitherto opposed the use of ma- 
 chinery for this purpose being totally 
 avoided. 
 
 Whilst upon this subject, we have 
 great pleasure in calling the attention 
 of our readers to a very effective machine for sweeping chimneys, invented by 
 Mr Glass, which has been approved by the Society for Superseding the 
 
 3 A 
 
 Fig. 2.
 
 CHIMNEYS. 
 
 Necessity of Climbing Boys, and which seems applicable to almost every con- 
 struction of flues. The brush, Fig. 1, is made of a round stock a, commonly 
 alder, and pierced with small holes, into which bunches, formed of strips of the 
 best whalebone, are inserted and fastened by glue. These strips b are from 8 
 to 8J inches in length, which renders the brush, including the stock, about 20 
 inches in diameter ; it therefore completely fills, and effectually cleanses, the 
 largest flues, which are never more than 14 inches square, and nre seldom 
 more than 14 by 9 inches. At the end of the stock c is a very strong brass 
 ferrule, with a wormed socket, which receives the screw of the first joint. Fig. 2 
 is a representation of the ferrules of the real size ; the three first portions d d d, 
 2 feet in length, are made of good cane, the rest eeeof ground ash, and of the 
 same length, the number used of course depending upon the height of the 
 chimney ; these are made gradually stronger towards the bottom, and are 
 affixed to each other by means of the brass screws and sockets in Fig, 2, before 
 described. The superiority of this machine consists in extreme pliability, 
 lightness, and strength, which render it peculiarly applicable in high chimneys 
 having a diagonal portion at b, as shown in the annexed 
 Fig. 3. If Glass's machine be introduced through B, it 
 will proceed to the top of A with ease, whilst most fig. 3. 
 
 other machines generally stick at b. A common defect 
 in the construction of chimneys, although not so great 
 in houses of recent construction, is, that the aperture is 
 generally much larger than necessary for the passage 
 of the smoke, the consequence of which is, that the 
 fuel in the grate not being sufficient to rarefy the whole 
 portion of the air in the flue, the rising current of heated 
 air is met by a descending current of cold air, and the 
 smoke is borne back into the room. By Mr. Tredgold's 
 rule, before given, it appears, for a grate 18 inches wide, 
 a chimney 36 feet in height would require an aperture 
 of only 51 inches area, little more than 7 inches square, 
 whereas no chimneys are less than 14 inches by 9. It 
 is true that they could not be swept by climbing boys if 
 made of less dimensions ; but if carried up in nearly a straight direction, without 
 abrupt bends, they might be easily cleaned by machinery, by which means a 
 barbarous and inhuman practice would be abolished, and the proper dimensions 
 being assigned to the chimney, the annoyance of smoke in the apartments 
 would be got rid of. The most effectual remedy for smoky chimneys is to 
 
 Fig. 2. 
 
 contract the aperture, and lower the breast of the cliimney ; and when this ha 
 been carried as far as is practicable, some further benefit may be derived by
 
 CHIMNEYS. 
 
 3G7 
 
 placing on the summit a revolving cap, turned by a vane, so that the aperture 
 for the smoke shall always be to leeward. 
 A machine of this description, invented by 
 Capt. Halliday, is represented in the engraving 
 on the preceding page, a and b are two square 
 plates of iron, or other metal, the upper one 
 being supported by four vertical pillars ; c is 
 the aperture for the passage of the smoke from 
 the brick flue immediately beneath ; across 
 this aperture a bar is fixed horizontally, sup- 
 porting the upright spindle d, on the upper 
 end of which is fixed a double-tailed vane, 
 shown in plan at Fig. 2. Below the plate b 
 a square plate, forming a screen or guard, is 
 attached by braces to the spindle, and the 
 spindle being turned by the action of the 
 wind upon the vane, the screen is constantly 
 opposed directly to the wind. 
 
 The sketch below exhibits a smoke cowl 
 commonly used at Glasgow : Fig. 1 is an 
 elevation, and Fig. 2 & plan or horizontal 
 section of the contrivance, which consists of 
 a quadrangular box of sheet iron, surmounted 
 by a pyramidical cap, ind placed, as exhi- 
 bited, over the top of the brick flue. There 
 are four doors to it, ab cd; a is connected 
 by an intermediate rod / to the opposite door 
 c, and b, by the rod e to the door d, so that 
 when the wind closes the door opposed to it, 
 the opposite one is opened for the smoke to 
 escape uninfluenced by the wind. 
 
 The annexed engraving represents Mr. Fen- 
 ner's apparatus for curing smoky chimneys. It 
 consists of a spiral tube or flue to the upper 
 part of an ordinary chimney. These tubes 
 are made of thin copper, and furnished with 
 
 Fig 2.
 
 308 
 
 CHURN. 
 
 a flange at the lowest end upon which it rests on the top of the brick-work 
 of the ordinary flue. The chimney is then continued upwards with a reduced 
 thickness of brick-work, by which means the capacity is sufficiently enlarged 
 for the reception of the spiral tube. The expanded part of the chimney is 
 closed in at top so as to form a hot-air chamber round the tube, which being 
 of thin metal, the heat is readily transmitted to the chamber. 
 
 CHLORINE. The name given by Sir Humphrey Davy to a gas which long 
 went, and even still commonly goes, by the name of oxymuriatic acid gas, as 
 being imagined to be a compound of oxygen and muriatic acid, but which he 
 showed to be a simple substance, which, when combined with hydrogen, formed 
 muriatic acid. Chlorine is commonly, in the small way, obtained by distilling 
 in a glass retort, at a gentle heat, 3 parts of common salt, 1 part of black oxide 
 of manganese, and 2 parts of sulphuric acid. The gas which comes over is of 
 a greenish yellow colour, and its odour and taste are disagreeable, strong, and 
 so characteristic, that it is impossible to mistake it for any other gas. Like 
 oxygen, it is a supporter of combustion, the products of which are termed 
 chlorides. It has two remarkable properties : 1st, Its affinity for hydrogen is 
 superior to that of any other substance, whence it is extremely useful in 
 destroying contagious miasmata ; and 2dly, its destructive action upon vegetable 
 colours, with the aid of a little moisture. Scheele first remarked this property, 
 Berthollett applied it to the art of bleaching in France, and Mr. Watt intro- 
 duced its use into Great Britain. The alkaline metals, as well as copper, 
 tin, arsenic, zinc, antimony, in fine laminae or filings, spontaneously burn in 
 chlorine : metallic chlorides result. Phosphorus also takes fire at ordinary 
 temperatures, and is converted into a chloride. Sulphur may be melted in the 
 gas without taking fire. See BLEACHING. 
 
 CHOCOLATE. A kind of paste or cake pre- 
 pared from several ingredients, the chief and basis 
 of which is the cacao nut. The cacao, after being 
 roasted, is ground to a paste. The English manufac- 
 turers are said to mix the flour of horse-beans, or 
 other farinaceous vegetable matter, to soften the 
 strong taste of the cacao; some vanilla and sugar are 
 likewise added by them. The Spanish chocolate 
 contains cloves, cinnamon, besides musk, ambergris, 
 &c., which are not agreeable to the English palate. 
 
 CHURN. A vessel in which butter is obtained 
 from milk or cream by agitation. A great variety 
 of churns are in use ; a very common one consists 
 of a deep wooden tub, rather conical, resting on its 
 base, and having a wooden cover, through which 
 passes the churn staff, to the bottom of which is 
 fixed a broad kind of foot, having numerous perfo- 
 rations to occasion a more universal agitation of the 
 milk in churning, the staff being worked briskly up 
 and down. From the mode in which the power 
 is applied in this kind of churn, the operation is 
 very laborious; another kind, therefore, called the 
 barrel churn, is now very generally adopted in our 
 dairies, which consists of a kind of rolling barrel 
 with an apparatus within it, calculated to quicken 
 the formation of the butter by promoting the agita- 
 tion of the milk. The annexed engraving repre- 
 sents an elegant little table churn, constructed of 
 glass by Messrs. Pellat and Green, which shows the 
 manner in which butter is formed in a very inte- 
 resting manner, a represents an axis placed verti- 
 cally in a glass cylinder, and furnished with four 
 
 leaves b b, placed at right angles to each other, (as seen in Fig. 2,) and notched 
 on the edges, and also perforated (as shown in Fig. 1). To the interior of 
 
 Fig.2.
 
 CLARIFICATION. 3(jy 
 
 Ihe cylinder are fixed three leaves c c, at equal distances from each other, and 
 also notched on the edges so as to receive the projecting points of the leaves 
 attached to the axis, and nearly fit them, at the same time allowing the 
 movable leaves to pass freely when the axis is turned round. The agitation 
 is produced by a rapid rotation of the axis with its leaves or fans, which is 
 effected by means of the bevilled wheel d and e, put in motion by the handle/. 
 CINCHONA is the bark of several species of cinchona, which grow in South 
 America ; of this bark there are several varieties, the red, the yellow, and the 
 pale. The red is in large easily pulverized pieces, which furnish a reddish 
 brown powder, having a bitter" astringent taste. The yellow Peruvian bark 
 was first brought to this country about the year 1790, and it resembles 
 pretty closely in composition the red species. The pale cinchona is that 
 " employed in medical practice as a tonic and febrifuge 
 
 CINNABAR. A beautiful red pigment, composed of sulphur and mercury, 
 and hence in the chemical nomenclature called sulphuret of mercury. 
 
 CINNAMON. The inner bark of the laurus cinnamonum, a native of 
 Ceylon. It is a most grateful aromatic, of a very fragrant smell, and a mode- 
 rately pungent taste, and is an excellent restorative spice. 
 
 CIRCLE. A line continued till it ends where it began, having all its parts 
 equidistant from a common centre. 
 
 CIRCUMFERENCE. The periphery or line bounding or including any 
 
 CIRCUMFERENTOR. A mathematical instrument used by surveyors for 
 taking angles by the magnetic needle in cases where great accuracy is not 
 required, and where a permanent direction of the needle is of the most 
 material consequence in surveying. It consists of a compass box containing 
 a magnetic needle, supported on a pivot in the centre, and the circum- 
 ference of the box divided into 360 parts or degrees. The box is furnished 
 with two sights, placed on opposite ends of the meridian line, or 180 asunder; 
 it is also mounted on a pivot in the head of a tripod or stand. In taking 
 the angle between two objects with this instrument, the box is turned until one 
 object is seen through the sights, when the number of degree's to which the 
 south end of the needle points is noted ; the box is then turned until the 
 second object be observed through the sights, and the degrees pointed to by 
 the needle again noted, and the difference between the two numbers is the 
 quantity of the angle. 
 
 CITRIC ACID. An acid obtained from the juice of lemons, although it is 
 also contained in various other fruits and vegetables. The usual method of 
 preparing it consists in saturating a quantity of the juice of lemons by chalk, 
 which thus forms citrate of lime, and afterwards decomposing the citrate by 
 diluted sulphuric acid, by which means sulphate of lime is formed, and the 
 citric acid is set free, and in this state it is used by the calico printers ; but for 
 other purposes it is crystallized by evaporation. There is an interesting paper 
 on this suoject in Parkess Chemical Essays. 
 
 CIVET. A perfume which bears the name of the animal from whence it is 
 taken, called a civet cat (found in China and the East and West Indies), but 
 bearing a greater resemblance to a fox or marten than a cat Several of these 
 animals have been brought into Holland, and afford a considerable branch of 
 commerce, particularly at Amsterdam. The civet is collected near the anus of 
 this fierce carnivorous quadruped, and squeezed out in summer every other day, 
 in winter twice a week ; the quantity procured at once is from two scruples to 
 a drachm or more. The juice thus collected is much purer and finer than that 
 which the animal sheds against shrubs or stones in its native climates. Good 
 civet is of a clear yellowish or brownish colour, not fluid nor hard, but about 
 the consistence of butter or honey, and uniform throughout ; of a very strong 
 smell, quite offensive when undiluted, but agreeable when only a small portion 
 is mixed with other substances. 
 
 CLARIFICATION. The process of clearing or fining any fluid from 
 heterogeneous matter or feculence by chemical means, thus differing from 
 filtration, which is merely a mechanical operation. Clarification is performed
 
 370 
 
 CLOGS. 
 
 either by heat, ot by the addition of some substance which will unite with, and 
 either precipitate to the bottom, or carry to the surface, the matter which 
 renders the liquid turbid. 
 
 CLARINET. A wind instrument of the reed kind. 
 
 CLEPSYDRA, or WATER CLOCK. A contrivance of very great antiquity, to 
 measure the lapse of time, and indicate the hour by the 
 flowing of water into or out of a vessel properly graduated. In 
 the former case the vessel was divided by lines into a number 
 of equal parts, which would be filled with water in equal por- 
 tions of time provided the source from whence the water was 
 obtained was so abundant as to render the hydrostatic pressure 
 upon the discharging aperture nearly equal. Such clocks, how- 
 ever, could be employed in particular situations only, the latter 
 plan was therefore most commonly adopted, viz. to measure 
 by the discharge of water from the vessel ; but as in this plan 
 the velocity of the water would not be uniform, but would 
 decrease with the decrease of the water in the vessel, equal 
 quantities of water would not be discharged in equal times, 
 and some contrivance became necessary to compensate this 
 inequality. The most common was to employ a vessel of larger 
 diameter at the upper than at the lower end, and divide the 
 altitude into a number of equal parts, or else to use a vessel 
 of equal diameter throughout, and divide the height into a 
 number of unequal parts, gradually diminishing from the top ; 
 but each of these methods was difficult to execute accurately. 
 The cut in the margin represents a. contrivance of Mr. Par- 
 tington's, by which these difficulties are avoided, and equal 
 quantities of water are discharged in equal spaces of time, a 
 ia a cylindrical tube to hold the water, and b a cork float on its 
 surface, through which is passed the shortest leg of a narrow 
 syphon c, which is suspended by a silken cord over a wheel d, 
 and to the other end of the cord is attached a weight, which 
 nearly counterbalances the syphon ; near to the extremity of j 
 the syphon is fixed an index/, that points out upon a graduated \ 
 scale the hour, according to the degree of depression within i 
 the tube. It is obvious that as the float by which the syphon 
 is supported is always immersed to the same depth in the 
 water, the outer leg of the syphon will always remain in the 
 same relative position to the surface of the water in the tube, 
 and thus the hydrostatic pressure will be always the same, the 
 flow or discharge will be uniform, or equal portions will be 
 
 discharged in equal times, and the tube being cylindrical, or 
 of the same dimension throughout its length, th 
 
 scale cor- 
 
 responding to its altitude will be divided into equal parts ; 
 thus the instrument forms a very accurate measurer of time. 
 The water falls into a receiver g, which forms the base of the 
 instrument, and may be made to run back into the tube by 
 opening a passage between them, and inclining the instrument. 
 
 CLOCK. An instrument for measuring and indicating time. 
 See HOROLOGY. 
 
 CLOG. In the manege, a log of wood fastened to the c 
 fetlocks of a horse, to break him in to a peculiar kind of pace 
 or step. 
 
 CLOG. A sort of shoe with a thick sole of wood or leather, worn over the 
 ordinary boots and shoes in dirty weather. Although clogs are more easy to 
 walk in than pattens, as affording a firmer footing, they are not so cleanly, as they 
 splash and throw up a deal of dirt. The figures on the opposite page represent a 
 combination of the clog and the patten, affording the security and firmness of the 
 tread of the former, and the cleanliness of the latter. Fig. 1 shows the patten 
 clog in perspective, and Kg. 2 the same turned upside down, a is the patten
 
 CLOGS. 
 
 871 
 
 Iron, of the peculiar form represented, which is found not to splash in the least ; 
 it is rivetted to the bottom of the clog, as a support to the heel, and is upon a 
 level with the projecting or thickest parts b of the sole that supports the fore 
 part of the foot. The clog is hollowed out at c to render it lighter, and to cause 
 it to take up less dirt. One objection to clogs, as usually constructed, is the 
 
 fatigue they occasion in walking, from their want of flexibility. This defect has 
 of late years been remedied by forming the sole of two or more pieces, con- 
 nected by hinges ; and a further improvement has been introduced by Mr.Schaller, 
 who has obtained a patent for what he terms " expanding clogs or pattens," 
 which may be lengthened or contracted at pleasure, so as to fit lie foot of the 
 wearer with the greatest exactness. These expanding clogs are represented in 
 the engravings on page 372. Fig. 1 repres-snts a man s clog in perspective, with 
 the contrivance for expanding or contracting the same. Under the brass ferule 
 at a is a sliding rack and spring, or other contrivance, by which the clog can be 
 lengthened or shortened at pleasure ; at b is another rack and spring, which 
 allows the raised sides of the heel-piece to be expanded or contracted breadth- 
 wise. To the strap c is likewise attached an improved spring slide, by which 
 that also may be lengthened or shortened: these several contrivances are 
 exhibited in detail in Figs. 2, 3, 4, 5, 6. Fig. 3 represents a plan of the upper 
 side of the sole of the clogs, without the brass ferule or sheath a, and with 
 another flat plate, which encloses the work underneath, removed ; the rack d 
 and the spring e are thus brought into view, the former being screwed to the 
 waist of the sole, and the latter to the heel piece, in cavities or mortises made 
 to receive them ; they are likewise so fixed that the spring always keeps in 
 contact with the rack, as shown by the edge view of them in Fig. 4, where it 
 is seen that there is a stout pin / which goes through a slot mortise in the rack : 
 this pin slides backwards and forwards in the slot mortise. By this arrange- 
 ment it will be seen that the clog may be contracted by simply thrusting the 
 toe part towards the heel, as the spring catch, which is fastened to the former, 
 slides over the notches in the rack ; but to pull the toe from the heel, in order 
 to lengtlien the clog, it becomes necessary to press upon the brass pin /, which 
 in this clog protrudes a little way either on the upper or the under side. fig. 2
 
 372 
 
 CLOGS. 
 
 represents a plan of the upper sole of the superadded heel-piece, which consists 
 of a metal plate g. The sides h h are here shown as expanded for a large foot ; 
 to contract it to suit a smaller foot it is only necessary to press the sides h h 
 together, when a spring catch (nearly similar to that already described iu the 
 other part of the clog) slides over the notches of a rack, and fixes itself wherever 
 
 it is left. On the contrary, when it is wished to increase tne capacity of the 
 heel, the guide pin i which slides in the slot mortise k is to be pressed upon by 
 the thumb nail, which thrusts the spring catch out of contact with the rack, 
 and the sides h h spring out again in the position shown in the figure, owing to 
 their having a metallic lining (of thin plate iron), which possesses sufficient 
 elasticity for that purpose ; the four screw holes, shown in the heel-plate ff, are 
 for the purpose of fastening it down to the wood or leather heel-piece of the 
 dog. The slide for lengthening or shortening the tie of the clog across the 
 instep of the wearer is shown on an enlarged scale at Figs. 5 and 6, the same
 
 COAL MINE. 373 
 
 letters in each referring to the same parts. It consists of two plates // laid 
 flat-wise in contact with each other, with four long apertures or slots, in each of 
 which slides a brass pin ; two of these pins are rivetted to each plate, and confine 
 the opposite plate in contact by their heads projecting over it. To give an 
 increased friction to the sliding plates, and to stop their action, a spring n is fixed 
 to one of the plates, with a brass catch pin o at the other end, .so that when the 
 slide is shut up, as shown in Fig. 1, the pin o enters the hole p, where it is 
 retained, until pressed out again in order to lengthen the tie as may be required. 
 Fig. 7 represents a clog more especially adapted to ladies' wear, in which another 
 mode of lengthening or shortening the clog is adopted. In this instance a thin 
 iron bar or plate is perforated with holes and rivetted to the fore part of the 
 sole, and kept steady by two pins on either side ; the other end of the perforated 
 plate enters the heel of the clog, and is so formed at the extremity as to prevent 
 it being entirely drawn out. Now the brass sheath a has a hole at q, and 
 another directly opposite to it at the bottom ; the pin r being then passed through 
 both holes in the brass sheath, and through one of the holes in the intervening 
 perforated plate, fixes the clog firmly in the place required. 
 
 CLOTH. A general name for any fabric woven from any fibrous materials 
 (except silk), such as flax, cotton, &c., but it is mostly used to signify cloth 
 made from wool. See WEAVING and WOOLLEN MANUFACTURE. 
 
 CLOUTS. Thin plates of iron, which are nailed to the wooden axletrees of 
 carriages. 
 
 CLOVES. The produce of the caryophillus aromaticus of Linnaeus, which 
 grows in the Molucca Islands, particularly in Amboyna, where it is principally 
 cultivated. The clove tree resembles in its bark the olive, and is about the 
 height of the laurel, which it also resembles in its leaves. No verdure is ever 
 seen under it. It has a great number of branches, at the extremities of which 
 are produced vast quantities of flowers, that are first white, then green, and at 
 last red and hard. When they arrive at this degree of maturity, they are, 
 properly speaking, cloves. The season for gathering is from October to February, 
 when the boughs of the trees are shaken, or the cloves beaten down by reeds, 
 large cloths being spread to receive them. These are afterwards either dried 
 in the sun, or in the smoke of the bamboo cane. 
 
 CLUTCH. A mode of connecting shafts with each other or with wheels, so 
 as to be disengaged at pleasure ; numerous examples of which have been given 
 in the preceding part of this work. See also MILLWORK. 
 
 COAL. A carbonaceous substance lying in strata at various depths beneath 
 the surface of the earth, and extensively used for fuel. The varieties of coal 
 are scientifically described by Dr. Jamieson in his geological work, and classed 
 in several species and subspecies ; but, in a practical point of view, they may be 
 divided into three classes, according to their degree of inflammability. The 
 least inflammable kind is the anthracite, or stone coal, of which class is the Welsh 
 and Kilkenny coal. It requires a considerable degree of heat to ignite it, but 
 when once kindled it remains in distinct pieces in the fire without caking, pro- 
 ducing neither smoke nor flame, making no cinder, but leaving a stony slag 
 behind. It is chiefly used in malt kilns, dye-houses, &c. Open burning coal 
 kindles quickly, makes a hot pleasant fire, but is soon consumed, and produces 
 smoke and flame in abundance ; it lies open in the fire, and does not cake 
 together to form cinders, its surface being burnt to ashes before it is thoroughly 
 calcined in the middle. Of this kind is Cannel coal, jet, and most of the 
 Staffordshire and Scotch coals. Close burning coal kindles quickly, makes a very 
 hot fire, melts and runs together like bitumen ; it makes a more durable fire 
 than any other kind of coal, and burns finally to ashes of a brownish colour. 
 Of this kind are the Newcastle coals, and those of the surrounding districts. 
 The various kinds of coal are often found mixed with each other, and at times 
 some of the finer sorts run like veins between the coarser sorts. 
 
 COAL MINE. Strata of coal are to be met with in various parts of the 
 
 globe, as France, Germany, Sweden, America, Australia, and we believe likewise 
 
 in India ; but in no country in such profusion, or of so good a quality, as in 
 
 Great Britain; and to this circumstance we may mainlv attribute our commercial 
 
 9m
 
 574 COAL MINE. 
 
 greatness, ana our superiority in almost every branch of manufacture. In coat 
 mining, and the carrying trade, a vast portion of our population is employed, 
 besides many hundreds of thousands of tons of shipping constantly engaged in 
 transporting this valuable mineral not only to all parts of our own coasts, and 
 up our rivers, but to almost every part of the Netherlands, France, Spain, 
 Portugal, the West Indies, and America. The principal seat of the coal trade 
 is in the northern and eastern parts of England, and the most important coal 
 works are those of Newcastle and Whitehaven ; at the latter place some of the 
 mines extend more than a mile under the sea, and at a depth considerably 
 greater below its surface than has been reached in any part of the world, the 
 deep mines of South America being situated upon lofty mountains considerably 
 elevated above the surface of the earth. 
 
 We shall now proceed to give a brief description of the method of working 
 a coal mine. To ascertain whether coal is concealed beneath the surface at any 
 place, recourse is had to boring, by a process and implements similar to what 
 we have already described in our account of the method of boring for water ; 
 and an account is carefully kept of the different strata cut through, and of the 
 depths to which they extend before arriving at the principal bed of coal ; and 
 the thickness of the coal strata in different situations, as well as the dip or 
 inclination of the strata, (for they seldom lie horizontal,) are ascertained by the 
 same means. The working is usually commenced upon the dip, as it is termed, 
 or where the depression of the strata of coal is greatest. The first consideration is 
 the means of draining off the water from the feeders and springs with which the 
 coal is usually intersected. If the situation and other circumstances will admit of 
 it, an adit is driven through the side of the hill to the lowest part of the mine, 
 and the water runs off by it to a lower level ; but if this cannot be effected, the 
 water is raised by pumps worked by horses, water, or steam, according to 
 circumstances. For this purpose a pit or shaft, termed the " engine shaft," is 
 sunk (generally upon the dip of the coal), in order to allow the water to drain 
 from the workings and to keep them dry. In this shaft the pumps are placed, 
 divided into sets at the various depths of the mine, the lowest set delivering its 
 water into a cistern, from which it is raised by the next set of pumps above it, and 
 so on to the surface, the lift for each set seldom exceeding 25 to 30 fathoms. 
 When the required depth is attained, a portion of coal is worked dipward of the 
 engine-shaft, forming a cistern for the waters to collect in. A level is then cut, 
 from the bottom of the engine-shaft, called the gateway, or winning headway, 
 which, as the works proceed, is carried the whole length of the mine, and is 
 from 8 to 10 feet high, and 9 feet wide. When the gateway has proceeded 
 to the required distance from the engine shaft, another shaft is sunk to meet 
 it called the coal shaft, or pit, by which the coals are conveyed to the 
 surface in baskets by a gin. From the gateway, or winning headway, the coal 
 is worked from passages cut at right angles, called " rooms," which are about 
 12 feet wide; and other passages again are cut at right angles to the rooms, 
 which open from one room into the next, and are called "thoroughs," or thirt- 
 ings, the coal remaining thus forming pillars for the support of the roof. When 
 the coal is of a firm texture, from two-thirds to three-fourths may be got out 
 at the first working ; but in other cases little more than a half. Two large 
 blocks or pillars, 15 or 20 yards long by 10 or 15 yards wide, are left to 
 protect engine and coal-pit, in case of the falling in of the mine. The coals 
 are brought to the r pit or shaft in small cars, drawn by horses when the workings 
 are wide and moderately level ; but if too steep or narrow, are drawn by men 
 in baskets upon trucks ; or if too steep for this, are carried in baskets upon the 
 backs of women. A general idea of the operations and arrangements of a coal- 
 mine may be gathered from the accompanying section of Bradley Coal Mine, 
 near Bilston, in Staffordshire. A, the whimsey, or steam-engine for raising the 
 coal from the bottom of the shaft ; B, the banksman who lands the same ; C, 
 one of the shafts of the mine ; D, a passage from one shaft to another ; E, the 
 gateway, or head-winning way ; F, the bolt hole, made to cause a free circula- 
 tion of air though the mine ; (should any part take fire, the bolt hole is built up ;) 
 G, pillars left in working the ten-yard coal, to support the superjaoent strata ;
 
 COAL MINE. 
 
 375 
 
 TT, an excavation called a stall, or room, by the colliers, who, after the gateway 
 is cut, begin thus to work the coal, or hole-under ; I, the ribs through which 
 the air-way is cut ; J, lights ; K, a man who hangs on the skips, and rakes the 
 gateway; L M N, miners heading, holing, and shovelling out the slack or 
 small coal ; O, slack carrier ; P, miner working on a scaffold ; Q, the spern, 
 a small piece of coal left as a support to many tons above, which fall when this 
 is taken away ; R, a collier on a scaffold, taking out the spern as far as he can 
 reach with a pick ; S, a collier standing upon a heap of slack, called the gob, 
 with a prong used f-.>r that work, which cannot be safely done with a pick ; T, 
 
 a collier breaking or turning out coal ; U, a collier loading a skip ; V, a 
 collier breaking the large coal with a wedge ; W, a driver with an empty skip, 
 X, a driver with a loaded skip ; Y, a skip being drawn up the shaft by the 
 engine ; Z, a pillar, called the man of war, left to support the upper 
 strata until the lower are worked ; it is then taken away, and the upper 
 coal falls down. The different strata that are cut through to arrive at the 
 principal bed of the coal are exhibited on the left of the shaft, by variously 
 shaded portions of the solid earth, extending in the Bradley mine to the depth 
 of about 111 feet, the depth to the bottom of the shaft is 139 feet 4 inches. 
 In the extensive collieries in the vicinity of Newcastle a complicated and
 
 376 COAL MINE. 
 
 expensive system of ventilation has been adopted, in order to guard against the 
 disastrous consequences which result from an accumulation of fire-damp or 
 hydrogen gas ; but from the calamitous explosions, which are of such frequent 
 occurrence, it is but too clear that the system is deplorably inefficient, and calls 
 loudly for improvement. The accompanying sketch represents, on a small 
 
 scale, the plan which is pursued to counteract the effects of that fatal evil, and 
 to spread throughout the workings a sufficient quantity of fresh air. The dark 
 parts in the plan represent the pillars of coal left to support the roof, and the 
 light parts the workings. There are generally two descents or more to the 
 mine, as we have already stated, which are distinguished by the terms of the 
 downcast and upcast shaft. A is the downcast shaft by which the air descends ; 
 the current of the air is represented by the waved line, which is carried through 
 the main passages only, the subways which diverge from them being stopped 
 by the brattices ; and its motion is accelerated by the heat of a large fur- 
 nace, situated at the bottom of the upcast shaft B ; and thus the air, after 
 traversing the whole of the workings, ascends the shaft B. An exhausting 
 pump placed near the upper end of the upcast shaft B is sometimes substituted 
 for the dangerous expedient of the furnace at the bottom of the shaft. But 
 when particular parts of the mine are subject to rapid accumulations of fire- 
 damp, recourse is had to the firing process, which is usually performed by means 
 of an apparatus, consisting of a long pole, or a series of poles, fitting one into 
 another like a fishing-rod, so as to he elevated to the break, or pot-hole, where 
 the fire-damp has accumulated ; at the upper end of this pole is a small sheeve or 
 wheel, over which a copper wire passes, of sufficient length to reach to the horse 
 stable from any part of the mine ; this done, the pole is firmly fixed in the 
 place where the gas lodges. A candle, fixed to a piece of lead or other substance 
 to keep it upright when suspended, is carried by the fireman as far towards the 
 explosive region as safety will admit, when it is set upon the floor, and fastened 
 to one end of the copper wire, after which the firemen retire to the stable, 
 which is made strong and well secured, in order to barricade them: the other 
 end of the wire is brought through a crevice in the door, and by this means the 
 light is drawn up to its destination; and the gas which has accumulated, 
 coming in contact with the flame, ignites and explodes. In some instances the 
 firemen remain pent up a considerable time in the greatest suspense, owing to 
 some accidental circumstance having put the candle out before it reaches the 
 pot-hole, when they are fearful of venturing, from the uncertainty of what may 
 be the event. In many instances it has been found necessary to explode these 
 lodgments three times a day, at each time clearing the mines of all the work- 
 men except the firemen ; the necessity of which has been occasioned by the 
 miners cutting down strata or measures of coal, so a& to render the roof higher
 
 COAL MINE. 
 
 377 
 
 than the general run, of six or eight feet seams, and by these means making the 
 extra elevation too great to be effected by the diluting current. In fact, where 
 the roof of a coal mine (where the seam is thirty-six feet thick,) is cut down, no 
 means but the firing process could suspend for a single day the destructive 
 effects produced by an explosion of the whole mine. To obviate the dangers 
 and difficulties of the firing process, Mr. James Ryan, of Netherton colliery, 
 near Durham, who had been for many years engaged in working mines, invented, 
 in lieu of it, a simple, effectual, and economical system of ventilation, by which 
 the fire-damp, or inflammable gas, was carried off upwards from the mine, 
 whilst by another arrangement he caused the carbonic acid gas (or choke-damp) 
 to pass off into the water level. In attempting to get his plans of ventilation 
 tried at various mines, he met with the most stubborn opposition ; and although in 
 every instance in which he was allowed to introduce his system, he was eminently 
 successful, yet, from the misrepresentations of ignorance and jealousy, his 
 system of ventilation has been adopted in very few mines, and the firing pro- 
 cess is still very generally resorted to. Mr. Wood, of Summer Hill Grove, Nor- 
 thumberland, has however invented an apparatus by which the firing may be 
 effected without any personal danger. The annexed diagram represents the interior 
 
 of a coa' mine in perspective, with Mr. Wood's apparatus employed in igniting 
 the gas. It consists of a common Dutch striking clock, in which the descent of a 
 weight at a previously determined hour raises a lever having a counterbalance 
 weight. : this lever acting upon another lever, causes a match, charged with
 
 378 
 
 COAL MINK. 
 
 oxymuriate of potash, to be dipped into a bottle containing sulphuric acid ; the 
 counterbalance weight on the first lever immediately afterwards draws the 
 match out of the bottle, when the contact of the air causes the match to ignite, 
 and to set fire to a train of combustible matter connected with it, consisting of 
 cotton or tow saturated with spirits of turpentine, a represents the weight of 
 the clock, which is set to go off at the time denoted ; a projecting piece at the 
 bottom of the weight presses in its descent upon one extremity of a lever, which 
 turns upon a fulcrum at b : the other end of this lever is provided with a roller 
 c, which raises the loaded end d of another lever, supported upon a standard at 
 e ; at/ is a rod attached by a joint to the other extremity of the second lever, and 
 at the lower end it is jointed to a small block, to which is fixed the match. To 
 the match are attached some loose!* twisted filaments of cotton, which are 
 carried upward, and wound round a<i iron rod as loosely as possible, so as to 
 form a large bunch of easily ignitable matter, to further which the whole is 
 saturated with spirits of turpentine: the iron rod containing the bunch of 
 cotton slides up and down in a fixed standard i, as represented ; and from this 
 point a train is made to other parts of the mine, where the inflammable gas 
 may have collected in a detached volume, by means of strips of brown paper 
 dipped in oil of turpentine, which are strung together and suspended in festoons 
 on standards fixed in the ground. The clock being set to go off when all the 
 workmen are absent from the mine or at rest, the weight operates upon the 
 lever at the precise period determined upon, ignites the match and the train, 
 and thus destroys all the inflammable gas. 
 
 The following is a simple and useful contrivance for the prevention of 
 accidents in raising men or minerals out of mines, by the ropes " running wild," 
 as it is termed, and for which the inventor, Mr. E. Speers, was presented with 
 the silver Vulcan medal by the Society of Arts. A bar is fixed on the end of 
 an axis. Two hooks,, as A, 
 swing freely on the ends of 
 
 this bar; C is a short bar ^ --.^ 
 
 or stop, projecting from s'' X. 
 
 the frame of the machine, 
 for the hook to catch hold 
 of. When the bar re- 
 volves at a moderate rate, 
 the hooks constantly hang 
 down by their own weight, 
 and keep clear of the stop 
 C; but when it revolves with 
 a ; dangerous rapidity, the 
 centrifugal force causes the 
 hooks to diverge from tl\eir 
 pendant position, and one of 
 them catches hold of the 
 check-bar C, (as shown by {'...->" 
 dotted lines,) which stops *' 
 the machine instantly. 
 
 A correspondent in the Register of Arts proposes the following modification 
 
 e of 
 the 
 
 of this contrivance, by which the shock occasioned by the sudden stoppage of 
 the- machinery is avoided, and the further advantage gained, that when th 
 velocity of the machinery is so far reduced as to avoid danger, the machinery will 
 
 hot stop, but will recommence motion of itself. In the engraving in the next page, 
 a is a section of Mr. Speers' check-hooks ; the bar to which the hooks are sus- 
 pended turns with the axle be; e is & conical pulley, with grooves cut in 
 a spiral direction, as represented in the section ; this pulley turns on the axle, 
 and not with it, like the bar a; out of this pulley projects the check-pin/. 
 <j is a screw fixed to the frame h, which fits into the pulley e, so as to enter 
 it as soon as the pulley is made to revolve in the same direction as the bar a, 
 i is a cord fixed to the pulley e, so as to be wound round all the grooves when the 
 pulley is turned ; to the end of it is fixed a weight, the size of which must
 
 COCKS. 
 
 379 
 
 be regulated according to the velocity 
 
 with which the machine is required to 
 
 work. From inspection of the plan it 
 
 will be seen that when the check-hooks, 
 
 by the too rapid revolution of the check- 
 bar a, have diverged so far from their 
 
 pendant position as to lay hold of the 
 
 check-pin f, the pulley e will be drawn 
 
 round in the same direction as the bar 
 
 , and will wind the weight suspended 
 
 by the cord i until the cord reaches the 
 
 uppermost groove, as at I, when the 
 
 velocity of the machinery will be greatly 
 
 moderated, at which time the pulley e 
 
 will have advanced so far along the 
 
 screw G as to draw the check-pin out of 
 
 the check-hooks, when the machinery 
 
 will proceed in a regular way, and the 
 
 cord i, by the descent of the weight 
 
 attached to it, will reverse the motion 
 
 of the pulley, and return it to its original 
 
 position, as shown at i, where it will be 
 
 always ready to regulate the machinery 
 
 when the check-hooks, by their centrifugal force, come in contact with the 
 
 check-pin /. 
 
 COBALT. A metal of a whitish grey colour, similar to tin, but with little 
 
 brilliance. It is brittle and easy to pulverize, but difficult to fuse, requiring 
 a temperature equal to that which is necessary to melt cast iron. Like iron it is 
 attracted by the magnet. In its metallic state it is of little use, but its oxide is 
 employed to impart a blue colour to fusible and vitreous substances. See 
 ZAFFRE and SMALTS. 
 
 COCOA-NUT is a native of most of the tropical countries ; the tree is from 
 40 to 60 feet high, the leaves from 10 to 15 feet long, and 3 feet broad. The 
 fruit is about the size of a man's head ; it contains a white kernel, the hollow 
 of which is filled with a milky juice. The uses of the cocoa-nut tree are numerous 
 and important. Its trunk is made into boats and water-gutters ; and in house- 
 building, the leaves serve for thatch, and are wrought into mats and baskets ; 
 likewise as & substitute for paper in writing upon. The fibrous husk of the 
 shell, after being soaked in water, is beaten into oakum, spun into a variety of 
 yarns, woven into sail-cloth, and twisted into ropes and cables even for the 
 largest ships. The bard shell is polished and formed into cups, powder- 
 boxes, &c. 
 
 COG. The tooth of a wheel, by which it acts on another. 
 CLARION. A kind of trumpet, whose tube is narrower, and its tone acuter 
 and shriller, than that of the common trumpet. 
 
 COCHINEAL. An insect which feeds on the Oactus opuntia, or prickly pear 
 of Mexico and other parts of South America. In the dried state in which it is 
 brought to Europe it resembles grains about one-eighth of an inch long, with 
 one side round and transversely wrinkled, and the other rather flat. The colour 
 is of a purplish grey ; the grey is owing to a powder which covers it naturally; 
 the purple tinge proceeds from the colour extracted by the water in which it 
 has been killed. The rich crimson colouring matter which it yields does not 
 appear to be injured by long keeping in a dry place, some cochineal of 130 
 years' old having been found to produce the same effects as new. The colour- 
 ing matter may be extracted either by water or alcohol. Alum was formerly 
 the only substance used to fix the dye of cochineal. About the year 1650, 
 Drebdel, a German chemist, discovered the effect of tin in heightening the colour. 
 The solution of tin in different acids will produce crimson, purple, violet, and 
 scarlet of various kinds. See CARMINE. 
 
 COCK. An instrument for permitting or arresting the flow of a liquid at
 
 380 
 
 COCKS. 
 
 pleasure. They generally consist of a short tube communicating with the caslc 
 containing the liquid, and having a plug ground into it near the middle, and 
 standing at right angles to it. This plug has a hole through it, which being 
 brought to coincide with the bore of the pipe, the plug offers no obstruction to 
 the liquid, but by turning the plug one quarter round, the solid part of the plug 
 stands across the bore of the pipe, and stops the passage of the liquid. 
 Numerous peculiarities are to be found in the construction of cocks, to adapt 
 them to particular uses ; some of these we shall proceed to notice. 
 
 The annexed figure represents in section, an improved lock-cock for liquor- 
 casks, invented by Mr. W. Russel. Numerous patents have been taken out for 
 
 lock-cocks ; but few of these inventions, we think, are equal to Mr. Russel's for 
 simplicity and security. The engraving represents the cock shut- and locked. A 
 square hole being cut through the barrel and into the plug a, a movable steady 
 pin or bolt b, with a shoulder to limit its action, is fitted into it, passing through 
 the barrel into the plug ; the opposite end terminates in a screw, over which is 
 a spiral spring resting on the shoulder ; a turned brass socket c, having also 
 a shoulder about midway to press upon the spiral spring, is then put over all, 
 and secured to the barrel either by solder or screws ; if by the latter only, the 
 notches in the heads must be filed away for obvious reasons. To open the cock, 
 or rather to withdraw the bolt, the screwed socket key must be introduced, 
 when about two turns will sufficiently compress the spring and withdraw the 
 bolt, and the cock may then be opened and shut at discretion, while the screw- 
 key remains in the position described. When the key is withdrawn, the action 
 of the spring upon the plug forces the bolt into the aperture of the plug upon 
 shutting the cock. 
 
 The accompanying figures repre- 
 sent another contrivance of Mr, 
 Russel's, which he has named a 
 " hydro-pneumatic liquor-cock, and 
 air-vent attached,"the object of which 
 if *o admit the air to press upon the 
 surface of the liquor, so as to cause 
 it to flow upon opening the cock, 
 but to shut off all communication 
 between the atmosphere and the 
 interior of the vessel when the 
 cock is closed, by which the 
 strength of the liquor is preserved, 
 and it is prevented from speedily 
 turning sour. Fig. 1 is a view of 
 the cock with the air tube applied 
 externally. The plug, in addition 
 to the aperture for the passage of
 
 COCKS 
 
 381 
 
 the liquor, has a smaller one placed 
 above it for the transmission of the 
 iir : upon turning the cock to draw 
 off, the air enters the smaller pas- 
 sage, and passing along the bent 
 tube b enters the vat above the 
 surface of the liquor through the 
 metal plug or ferrule d. Fig. 2 is a 
 section of a barrel showing another 
 modification of the apparatus, by 
 which the air-tube is placed inter- 
 nally ; this method is considered 
 preferable in brewers' or distillers' 
 large vessels, and in situations where 
 the tube, if applied externally, would 
 be liable to injury. Letters abed 
 and e apply to the same parts as in 
 Fig. 1 ; but the aperture for the 
 admission of air in this cock is 
 situated at the side (at e), in order 
 to show the application of the inven- 
 tion to one of Mr. Rnssel's lock- 
 cocks, already described. 
 
 The following cut represents a cock of simple construction, in which there is 
 no plug requiring grinding into its seat, and which may be entirely formed of 
 cast iron, which is at once cheaper and not pernicious like brass, a is the 
 
 barrel ; b a small rod having a screw cut on che end g, which works in a 
 corresponding screw cut in trie nose of the cock ; the other end of the rod 
 passes through a guide-piece e (perforated with numerous holes, to allow an 
 easy passage to the liquor), and through a leather washer, at the back of which 
 is an iron washer, against which the rod is rivetted ; and according to the 
 direction in which the screw is turned, the leather washer is either pressed 
 against the end of the cock, thereby closing the aperture, or it recedes from it, 
 and opens the passage. // is a section of the cask into which the cock is screwed. 
 Another cock, in some respects resembling the preceding, but requiring 
 3 c
 
 382 
 
 COFFEE. 
 
 greater accuracy of workmanship, is shown in the following figure, a is the 
 barrel, bored out cylindrical, and t lie interior end faced or filed square ; b the 
 nozzle ; c a conical plug formed upon one end of a screw ; d a handle upon the 
 other end of the screw, by turning which the plug may be made to close the 
 
 cylindrical passage o, but when drawn back to the fullest extent, it leaves a 
 clear passage for the liquor. A great objection to metallic cocks is their liability 
 to corrosion in liquors containing any portion of acid, by which means the pW 
 becomes loose in its seat, and in many instances a poisonous solution of the metal 
 is formed in the liquor. These evils are avoided in Ridgway's porcelain cocks, 
 which are not liable to corrosion in the strongest acids, at the same time they are 
 very firm and substantial, being formed of the strongest porcelain or stone ware. 
 
 The forms of the cock are somewhat new, as well as the interior construction. 
 The annexed diagram gives a section (excepting the upper or handle part of the 
 plug,) of the form most approved by the patentees, a is the long tube, with a 
 screw thread cut upon its external surface for the purpose of being screwed into 
 the barrel ; b the plug accurately ground, and fitted into its place; in the plug 
 a vertical perforation is made by 
 boring, equal to the diameter of that 
 in the long tube, and another hole 
 at right angles to the former to com- 
 municate with the vertical perfo- 
 ration and with the long tube, when 
 the plug is turned in the direction 
 shown, for drawing off the liquor. 
 To secure the plug in its place, and 
 to produce a uniform action, it has 
 a groove made three-quarters round 
 it, for receiving the end of the bolt 
 c which is fastened by the screw d. 
 See VALVES. 
 
 COFFEE is the seed contained in a berry, the produce of a moderate sized 
 tree called the Coffea Arabicum, and., which has also been named Jasminum Ara- 
 licum. This tree grows erect, with a single stem, to the height of from eight 
 to twelve feet, and has long, undivided, slender branches, bending downwards , 
 these are furnished with evergreen leaves, not unlike those of the bay tree. 
 The blossoms are white, sitting on short footstalks, and resembling a cherry, 
 and having a pale, insipid, and somewhat glutinous pulp, inclosing two hard 
 oval seeds, each about the size of an ordinary pea. One side of the seed is 
 convex, while the other is flat, and has a little straight furrow inscribed through
 
 COFFEE. 383 
 
 its longest dimensions ; while growing, the flat sides of the seed are towards 
 each other. These seeds are immediately covered by a cartilaginous mem- 
 brane, which has received the name of the parchment. The trees begin bearing 
 when they are two years old ; in their third year they are in full bearing. 
 The aspect of a coffee plantation during the period of flowering, which does not 
 last longer than one or two days, is very interesting. In one night the blos- 
 soms expand themselves so profusely as to present the same appearance which 
 has sometimes been witnessed in England when a casual snow-storm at the close 
 of autumn has loaded the trees while still furnished with their full complement of 
 foliage. The seeds are known to be ripe when the berries assume a dark red 
 colour, and if then not gathered will drop from the trees. The planters in 
 Arabia do not pluck the fruit, but place cloths for its reception beneath the 
 trees, which they shake, and the ripened berries drop readily. These are after- 
 wards spread upon mats, and exposed to the sun's rays until perfectly dry, when 
 the husk is broken with large heavy rollers, made either of wood or stone. The 
 coffee thus cleared of its husk is again dried thoroughly in the sun, that it may 
 not be liable to heat when packed for shipment. The method employed in the 
 West Indies differs from this. Negroes are set to gather such of the berries as are 
 sufficiently ripe, and for this purpose are provided each with a canvass bag, having 
 an iron ring or hoop at its mouth to keep it always distended, and this bag is 
 slung round the neck so as to leave both hands at liberty. As often as this bag 
 is filled, the contents are transferred to a large basket placed conveniently for 
 the purpose. It is the usual calculation, that each bushel of ripe berries will 
 yield ten pounds' weight merchantable coffee. In curing coffee it is sometimes 
 usual to expose the berries to the sun's rays, in layers five or six inches deep, 
 on a platform. By this means the pulp ferments in a few days ; and having 
 thus thrown off a strong acidulous moisture, dries gradually during about three 
 weeks : the husks are afterwards separated from the seeds in a mill. Other 
 planters remove the pulp from the seeds as soon as the berries are gathered. 
 The pulping-mill used for this purpose consists of a horizontal fluted roller, 
 turned by a crank, and acting against a movable breast-board, so placed as to 
 prevent the passage of whole berries between itself and the roller. The pulp 
 is then separated from the seeds by washing them, and the latter are spread 
 out in the sun to dry. It is then necessary to remove the membranous 
 skin or parchment, which is effected by means of heavy rollers running in a 
 trough wherein the seeds are put. This mill is worked by cattle. The seeds 
 are afterwards winnowed to separate the chaff; and if any among them appear 
 to have escaped the action of the roller, they are again passed through the 
 mill. The roasting of coffee for use is a process that requires some nicety ; if 
 burned, much of the fine aromatic flavour will be destroyed, and a disagreeable 
 bitter taste substituted. The roasting is now usually performed in a cylindrical 
 vessel, which is continually turned upon its axis over the fire-place, in order to 
 prevent the too great heating of any one part, and to accomplish the continual 
 shifting of the contents. Coffee should never be kept for any length of time 
 after it has been roasted, and should never be ground until it is required for 
 infusion, or some portion of its fine flavour will be dissipated. Count Rumford, 
 who paid great attention to the management and preparation of coffee, used to 
 preserve the aromatic fragrance of that which had been ground, by placing 
 it into a cylindrical metallic box, which was covered by an accurately fitting 
 piston in the inside, being well closed by a nicely adjusted cover on the 
 outside. An improved apparatus for roasting coffee was patented by Mr. 
 Evans in 1 824, the operation of which, it is said, confers a flavour similar to 
 that from Mocha to West India coffee ; and, owing to the retention of the 
 essential oil, a greater weight of roasted coffee is obtained from a given weight 
 of the raw material. The art, according to Mr. Evans's practice, seems to con- 
 sist in the abstraction of the aqueous and acidulous matter, without volatilizing 
 the essential oil, upon which mainly depend the flavour and agreeable qualities 
 of coffee. The apparatus consists of an elliptical iron retort, set in brick-work, 
 over a furnace ; the retort is made to revolve upon hollow axes, one of them 
 ecrving as an exit passage for U vapour, which is delivered therefrom into a
 
 334 
 
 COFFEE. 
 
 convoluted pipe, immersed in cold water, and is thereby condensed ; the other 
 hollow axis is for the convenience of introducing the " examiner," which is a 
 perforated tube, used to draw out a sample of coffee under operation, while 
 it serves also as a safety valve in case of the vapour accumulating in too great 
 force. A series of the retorts are placed over their respective furnaces, and 
 they are caused to revolve by geering connected to their axes, to which motion 
 is given by a steam engine, or any other convenient power. When the roasting 
 has been found complete, the retorts are lifted out of their apertures over the fur- 
 nace, and turned over upon one of their axes, which is provided with an ingenious 
 swivel bearing for that purpose ; the coffee is then discharged, and the operation 
 renewed upon a fresh quantity. In the ordinary method of roasting coffee an 
 acetic acid is generated, which is diffused in the liquor if the infusion remains 
 long. To obviate this inconvenience, an apparatus was contrived called a 
 biggin, in which the coffee is put into a bag suspended to the rim of the vessel, 
 and boiling water having been poured through, it is separated and removed 
 from the water, which remains pretty free from acid, and combined with much 
 aromatic fragrance. In coffee roasted by Evans's distillatory process, before 
 mentioned, the acetic acid is mainly got rid of, and therefore the same pre- 
 cautions that are used in the biggin are not necessary, and a richer infusion 
 maybe made by allowing the coffee to soak longer in the water; but as the fragrant 
 principle is of a very volatile nature, Mr. Evans contrived the following apparatus, 
 which is found to answer the objects in- 
 tended extremely well, and will serve for 
 the foundation of a machine of a more ele- 
 gant exterior. The body a of the vessel is 
 of a cylindrical form ; it has a cover b at 
 top, and at c a bottom, under which is a 
 stand or furnace d containing a lamp e ; at 
 / is a floating piston with a hook under- 
 neath for suspending the ground coffee 
 in a bag g. The floating piston is made 
 of two thin metal plates soldered together, 
 with a hollow space between them capable 
 of holding a sufficient quantity of air to 
 render itself and the bag of coffee buoy- 
 ant. The piston is accurately fitted to 
 the cylinder, but so as to allow it to rise 
 and fall freely with the surface of the 
 liquid in which it floats, and thus pre- 
 serve the infusion from the contact of 
 air, and there is only an extremely fine 
 circular line of liquor at the edges ex- 
 posed ; the heat and the aroma of the 
 infusion is thus preserved until the last 
 cup is drawn off. When coffee is ground to a fine powder, and placed loosely 
 among the water, the particles are a long time subsiding, and are easily dis- 
 turbed after having settled. To clear the liquid it has been usual to add a few 
 shreds of isinglass or other animal gelatine. The inconvenience of this pro- 
 cess probably caused the introduction of the bag, which is however not without 
 some disadvantages ; among which may be mentioned the trouble of cleansing, 
 and the imperfect solution of a portion of the extractive matter when the 
 coffee lies in so dense a mass. It has accordingly been suggested to place the 
 coffee between two flat perforated plates, at nearly the bottom of the vessel ; 
 the water should be supplied by a tube extending from the top of the vessel to 
 the bottom, from whence it will ascend through the strainers, and the coffee 
 contained between them, which being unconfined, every particle will be kept in 
 agitation by the boiling water, and be thoroughly operated upon : to this 
 arrangement the floating piston, before described, may be advantageously 
 added. 
 
 Since the foregoing suggestions vrere made, Mr. Jones, of the Strand, has 
 
 V^SglSg^^
 
 COLCHICUM AUTUMNALE. 
 
 385 
 
 introduced a coffee-pot on the principle which is represented in the annexed 
 
 cut. a is a vessel placed over a lamp furnace, into which the requisite 
 
 quantity of water is put ; b is a double vessel, the 
 
 internal one consisting of a perforated metal cup to hold 
 
 the ground coffee ; c is another recipient fitting over 
 
 b, and having a valve at d. When the water in a boils, 
 
 the steam ascends amongst the coffee in b ; and when 
 
 the steam accumulates in sufficient force, its pressure 
 
 upon the surface of the water in a causes the boiling 
 
 fluid to ascend the pipe e e, and to be discharged into 
 
 the vessel c; the lamp may then be blown out, and 
 
 the liquid will percolate through the coffee in a, and 
 
 the perforated strainer in its descent to the vessel a, 
 
 which will thus become filled with a filtered and 
 
 aromatic infusion. 
 
 COFFER DAM. An enclosure constructed for the 
 purpose of laying the foundations of bridges, piers, &c. 
 formed by two or more rows of piles driven close 
 together, with clay thrown in between the rows, the 
 heads of the piles rising above high water mark, and 
 thus forming a barrier to exclude the water. 
 
 COHESION, or ATTRACTION OF COHESION, is that i 
 power by which the particles of bodies are held ( 
 together. The absolute cohesion of solids is mea- 
 sured by the force necessary to tear them asunder ; heat is excited at the same 
 time. At the chain cable manufactory of Capt. Brown, a cylindrical bar of 
 iron, of 1 J inches diameter, was drawn asunder by a force of 43 tons. Before 
 the rupture the bar lengthened about 5 inches, and was reduced nearly three- 
 eighths of an inch at the part where the fracture took place, which became 
 heated to a degree unpleasant, if not painful, to the hand. The cohesive force 
 of metal is considerably increased by hammering, rolling, or drawing. The 
 following table shows the cohesive strength of a square inch in Ibs. avoirdupois, 
 or the force necessary to pull asunder a square inch of the various substances 
 named therein. 
 
 U 
 
 Copper, cast 22,000 
 
 Ditto, wire 61,000 
 
 Gold wire 31,000 
 
 Iron, cast 30,000 to 50,000 
 
 Ditto (German) 68,000 
 
 Ditto, bar 60,000 to 80,000 
 
 Ditto (German) 60,000 to 90,000 
 
 Ditto, wire 113,000 
 
 Platinum wire 56,000 
 
 Silver ditto 40,000 
 
 Ash 17,000 
 
 Beech 17,000 
 
 Deal (Norway spmce) 18,000 
 
 Ditto (English) 7,000 
 
 Elm 13,000 
 
 Oak 11, 000 to 16,000 
 
 Hemp fibres glued together .... 92,000 
 
 COINAGE, or COINING, is the art of making metallic money. See MINT. 
 
 COLCHICUM AUTUMNALE. A medicinal plant, the vinous infusion of 
 whose root has been shown by Sir E. Home to possess specific powers of alle- 
 viating gout. The sediment of the infusion ought to be removed by filtration, 
 as it occasions gripes, sickness, and vomiting.
 
 386 
 
 COMB MAKING. 
 
 COLLAR. A part of a horse's harness which surrounds his neck, and to 
 which the traces are attached by which he draws. It ordinarily consists of a 
 stuffed leather pad, on which rest two curved bars called the homes, united at 
 the lower ends by a few links of chain, 
 and drawn together at top by a strap 
 and buckle ; but from the collapsing of 
 the names, the shoulders of the horses 
 frequently become rung, which induces 
 many to give the preference to breastings 
 rather than collars. In Mr. Lukin's 
 improved horse collars the name is made 
 in one piece, which, from its elasticity, 
 has a tendency to expand instead of 
 collapsing, and the pads upon it are not 
 fixed immovably, but turn round upon 
 the hames as an axis, by which means 
 the pressure adapts itself to the motion 
 of the horse, and materially reduces the 
 chafing against his shoulders. The 
 annexed cut represents one of these 
 collars, a a represent the pads, one 
 turned partly round upon the hames 
 b b b to show their action ; c c are clips 
 for the traces ; d a small pad which lies 
 over the horse's neck, and e the strap 
 by which the hames are contracted in 
 any required degree. 
 
 COLOUR is that property in bodies which, when acted upon by light, 
 impresses the mind, through the agency of our sight, with those sensations which 
 we denominate colour. The light of the sun, which seems perfectly homogeneal 
 and white, is universally acknowledged to be composed of no fewer than seven 
 different colours, viz. red, orange, yellow, green, blue, purple, and violet. A 
 body which appears to be of a red colour has the property of reflecting the red 
 rays more powerfully than any of the others, and so of the orange, yellow, 
 green, &c. A body which is of a black colour, instead of reflecting, absorbs 
 all or the greatest part of the rays that fall upon it ; and, on the contrary, 
 a body which appears to be white reflects the greatest part of the rays indis- 
 criminately, without separating the one from the other. See PAINTING and 
 PIGMENTS. 
 
 COMB MAKING. The process of comb making is usually conducted as 
 follows. The material of which the comb is formed is first reduced to thin 
 smooth plates of an even thickness. The workman who cuts the teeth then 
 fastens one of these plates in a clamp or vice, and proceeds to cut the teeth by 
 means of a double saw, of which each blade is somewhat like the small one 
 with which joiners and cabinet-makers cut their fine work. As this instrument 
 leaves the work square, and in rather a rough state, particularly in the inside 
 edge of each tooth, it is followed by another about the size and shape of a case- 
 knife, having teeth like a file on each flat side. After this, two others of the 
 same shape, but each finer cut than the former, follow. One stroke on each 
 side of the comb is then given with a rasping tool, to take off any roughness 
 that may remain on the sides of the teeth, after which they are polished by 
 rubbing them with rotten stone, and oil spread upon a piece of buff leather. 
 With the simple apparatus above described, delicate ivory combs, containing 
 from fifty to sixty teeth in the inch, are cut. Mr. Bunday's machine for cutting 
 the teeth of combs is constructed as follows : upon an arbor driven by a treadle, 
 is fixed ,a number of circular steel cutters, corresponding to the notches intended 
 to be cut in the comb. These cutters, which are about two inches diameter, 
 and all exactly equal in thickness, have brass washers between them, and are 
 also kept regularly asunder just above the place where the comb enters, by steel 
 guides fixed in a stationary frame. The comb is firmly secured to a horizontal
 
 COMB MAKING. 
 
 387 
 
 sliding block or carriage, which ia made to advance towards the centre of the 
 axis of the cutters, by means of a screw turned either by hand or by a band- 
 wheel fastened upon its axis. The combs are pointed by applying them to an 
 arbor, driven by a crank, and clothed with cutters with chamfered edges. 
 
 Some improvements have been introduced in the rotatory comb cutting 
 machines by Mr. Lyne, who has also invented a machine by which two combs 
 are cut at once out of any tough material, 
 as horn or iortoiseshell : the parts cut 
 out from between the teeth of one comb 
 funning the teeth of the other comb in the 
 manner shewn in the annexed diagram ; by 
 which means the waste of material occasioned 
 in cutting combs by the ordinary process is 
 avoided. This machine is represented in the 
 accompanying engraving, a a is the frame of 
 the machine, made of cast iron ; b, a lever, which, by a pinion upon its axis, gives 
 
 an alternating motion to the racks cc; e is the cutter in its carriage, which is 
 tttached to a strong helical spring, contained in the cylindrical box, and is
 
 38R COMBUSTION. 
 
 seen immediately over it. At each extremity of the cutter is a small chisel 
 dd, set upon sliding rods, so that their distance asunder may be always equal 
 to the length of the cutter e ; these chisels make the end cut, by which the teeth 
 of the one comb are separated from the back of the other comb. Beneath the 
 cutters is a traversing carriage, upon which the horn or tortoiseshell is firmly 
 secured by screws : it is made hollow to admit of a heated iron being 
 introduced within it, in order to soften slightly the horn or tortoiseshell, and 
 render it less brittle. This carriage is advanced along a chase mortise, fixed 
 upon the bed of the machine by means of a screw, upon one end of which is a 
 ratchet wheel, which is moved by the compound levers i i i. The fineness of 
 the teeth of the combs is regulated by the teeth in the ratchet wheel, which is 
 accordingly changed with the nature of the work, and a handle is placed on the 
 axis of the ratchet wheel for the purpose of bringing back the frame after a 
 comb has been cut. The operation of the machine is as follows : the alter- 
 nating motion of the lever b backwards and forwards alternately raises and 
 depresses the racks c c ; the horns or curved projections in the middle of these 
 racks bring down the cutter e, by which one side of a tooth is cut, whilst the 
 extremities of the racks depress one of the chisels d, which makes the cut at the 
 end of the tooth. The cutter e is returned during the rise of the rack, by the 
 spring contained within the cylindrical box, and the chisels d by the spring of 
 the rods upon which they are set In order to give the tapered form to each 
 tooth, and to reverse them successively upon the opposite side of each of the 
 racks to that shown in the engraving, is a small inclined plane or cam, which, 
 on the descent of the rack acting upon the vertical bars // attached one to each 
 end of the cutter frame, causes the cutter to change its position, and to make 
 angular instead of parallel incisions. 
 
 COMBUSTION. The disengagement of heat and light which accompanies 
 chemical combination. Combustion was for a long time held to be the dis- 
 engagement or development of a certain air supposed to be contained in all 
 combustible bodies, and to which the name of phlogiston was assigned ; and 
 bodies which had undergone combustion were said to be dephlogisticated, or to 
 have parted with their phlogiston. This hypothesis, notwithstanding the 
 numerous facts at variance with it, and particularly the familiar one that 
 metallic oxides formed by combustion increase in weight, which could not be 
 the case if combustion consisted in depriving them of any substance previously 
 contained in them, was zealously maintained by many philosophers long after 
 the brilliant discoveries of Scheele, Cavendish, and Priestley, as to the nature 
 of atmospheric air, and against the theory of Lavoisier, founded upon these 
 discoveries, and upon Dr. Black's theory of latent heat. . According to the 
 theory of Lavoisier, the light and heat emanate from the oxygenous portion of 
 the atmosphere at the moment of its fixation with inflammable bodies ; and 
 succeeding chemists of his school, enlarging upon this idea, have ranged all 
 substances under two classes, viz. combustibles, and supporters of combustion. 
 But this theory, although much more consistent with most of the phenomena 
 of combustion, is still insufficient to account for some of them, and the dis- 
 tinction between combustibles and supporters of combustion appears to be 
 altogether imaginary, for one substance is frequently in both capacities, being at 
 one time apparently a supporter, and* at another time a combustible. Thus, 
 sulphuretted hydrogen is a combustible with oxygen, and chlorine a supporter 
 with potassium ; and sulphur, with chlorine and oxygen, acts as a combustible, 
 but with the metals it becomes a supporter. Nor can we ascribe the appearances 
 to an extrusion of latent heat in consequence of condensation : the protoxide 
 of chlorine, a body destitute of any combustible constituent at the instant of 
 decomposition, evolves light and heat with explosive violence, and its volume 
 becomes one-fifth greater ; and the chlorates and nitrates in like manner treated 
 with charcoal, sulphur, or metals, detonate or deflagrate, while the volume of 
 the combining substances is greatly enlarged. Neither can the heat evolved 
 in combustion be attributed to a diminished capacity for heat in the resulting 
 substances, for in the greatest number of cases there is no diminution of capacity 
 of the compounds formed. For example, the combination of oxygen and
 
 COMPASS. 389 
 
 hydrogen, or of sulphur and lead, produces no greater alteration in the capacity 
 of water, or of the sulphuret of lead, than the combination of oxygen with 
 copper, lead, or silver, or of sulphur with carbon, produces in the capacities of 
 the oxides of these metals, or of carburet of sulphur. The preceding, and 
 numerous similar facts, prove that combustion is not necessarily dependent 
 upon the agency of oxygen ; that the evolution of the heat is not to be ascribed 
 simply to a gas parting with its latent store of that ethereal fluid on its fixation 
 or combustion ; and that no peculiar substance, or form of matter, is necessary 
 for producing the effect, but that it is a general result of the actions of any 
 substances, possessed of strong chemical attractions, or of different electrical 
 relations ; and that it takes place in all cases in which a violent motion can be 
 conceived to be communicated to the corpuscles of bodies. For this view of 
 the subject the world is indebted to the masterly mind and deep and successful 
 researches of Sir H. Davy. For a clear and comprehensive account of his 
 experiments connected with this subject, together with his inferences therefrom, 
 we refer the reader to Dr. Ure's Chemical Dictionary. 
 
 COMPASS. A nautical instrument, showing the direction in which a vessel 
 is sailing, or the part of the horizon to which her head is directed. It consists 
 of a flat bar of steel, which being repeatedly rubbed with a magnet or loadstone 
 acquires the property of constantly taking a direction nearly corresponding with 
 the meridian, when freely suspended from a thread, or upon a delicate pivot. 
 Although as important consequences have flowed from the invention of the 
 compass as from any other invention whatever, the name of the author of it, 
 and even the age and country in which it had its origin, are points involved 
 in the greatest obscurity. In Europe we are indebted for its use to 
 B. Givaia, of Naples, who, towards the close of the twelfth, or about the 
 commencement of the thirteenth century, observed that iron became polarized 
 by contact with the loadstone ; but most writers upon the subject agree that the 
 compass was known long before that period to the Indians and Chinese ; nay, 
 in Bowles's Spirit of Maritime Discovery, it is attempted to be proved, by much 
 "learned argument," that it was known to Noah, and formed part of the 
 equipment of the ark. The compass is extensively used in surveying and 
 mining, as well as in navigation ; but there is in general this difference between 
 them, that marine compasses have a circular card divided into thirty-two 
 parts or points, and attached to the needle ; but in those for other purposes 
 the card is fixed to the bottom of the box, which is turned till the needle coincides 
 with the north point of the card. Marine compasses are usually supported' 
 upon a pin of steel or brass, having a fine point, working in a socket of agate 
 let into the centre of the needle or magnetized bar ; the pin is fixed into the 
 bottom of a circular box or basin, which is suspended by two pins turning in 
 holes in a ring concentric with the circular box ; this ring again is suspended by 
 two pins at right angles to the former, the whole forming a universal joint. 
 Besides the steering compass, there is another one made use of at sea, for 
 the purpose of taking the sun's bearing, in order to ascertain the variation of 
 the compass, or the difference between the true and magnetic north points, as 
 also in taking the bearings of different objects in marine surveying ; this is 
 called the azimuth compass. The card, besides the thirty-two points, is accu- 
 rately divided at the circumference into 360 degrees, and on the opposite sides 
 of the compass-box are two sights, for taking accurately the bearing of an 
 object, and a stud for stopping the card at the instant the bearing is obtained, 
 so as to allow time for reading off the angle. The circular box is suspended 
 within a square box, which latter is supported upon a pivot (on the top of a 
 three-legged stand), so that the right vanes may be turned to any part of the 
 horizon. Captain Phillips, R.N. has taken out a patent for an improved moda 
 of mounting ship's compasses; the object of which is to prevent those derange 
 ments which sudden concussion occasions to these instruments, by which the 
 card is frequently thrown off its central pivot, as is sometimes the case in stormy 
 weather, or from firing guns, striking of steam-boat paddles, &c. The figuie 
 in the following page, Fig. 1, gives a vertical section of the improved compass, a 
 is the standard formed of a hollow tube which incloses a long spiral spring, resting 
 3 D
 
 390 
 
 COMPASS. 
 
 upon a bearing at b ; to this bearing are fixed two handles cc, by which it may n 
 elevated within the standard, (compressing the spring,) and the bearing may rest 
 
 at any 01 the notches or recesses Noa. 1 , 2, 3, 4, which are formed in opposite sides 
 of the tube, to receive the handles cc. d is a short solid cylindrical piece, so fitted 
 into the hollow standard as to slide freely within it, and resting upon the spiral 
 spring ; e is a cap fixed on to a by a bayonet joint, to prevent the spring from 
 forcing the sliding piece d out of the standard ; /is the compass-card, which 
 rests upon the pivot g ; this pivot passes through the cross bars / /, and the 
 lower end is formed into a spherical knob, (better seen at 7i, Fig. 2, which 
 exhibits the same parts upon a larger scale). This spherical knob rests upon a 
 flat surface of agate, cornelian, or other hard stone i, which lies in a recess 
 upon the top of the piece d, and is kept in its place by the cap k being screwed 
 down upon it ; the cap k is made concave in the upper part of it, to fit the 
 spherical knob, so that the latter, resting at bottom upon a hard plane, and 
 above in its hemispherical concavity, can turn freely in any direction. At mm 
 is shown (black) the section of a leaden ring, which surrounds the compass- 
 box, as is shown by the two parallel dotted lines. At n n are two handles 
 fixed to the leaden ring, by which it may be shifted higher or lower on the 
 case, and be fixed at any height at pleasure, by the palls o o dropping into the 
 racks p p, which are screwed to opposite sides of the case, q is the steering, 
 or "lubber's point," which is suspended upon a movable joint r as a centre of 
 motion, and oscillates as a pendulum. This centre being placed so as to slide 
 between two vertical guides, it may be raised or lowered at pleasure, ana is 
 retained in its place by the pressure of a spring in the centre. The lubber's 
 
 C'nt should be adjusted so as to be even with the upper edge of the compass, 
 , raising or lowering the centre r, and the bob * should be shifted along the 
 rod until it coincide with the centre of the leaden ring. If the motion of the 
 compass-box, in a vertical direction, should be too violent, it is to be checked 
 by raising the handles c c into one of the notches 1, 2, 3, 4, as may be required 
 bv circumstances. The oscillations of the compass-box are regulated by shifting
 
 COMPOSITION OF FORCES 301 
 
 the leaden ring, raising it in blowing weather, 
 and lowering it in fine weather. It frequently 
 happens at sea that the sun is visible, although 
 the horizon cannot be distinguished for fog and 
 haze, in which case it becomes impracticable 
 to take the sun's altitude, in order to determine 
 the ship's place. This circumstance, at all 
 times inconvenient, may, in some situations, 
 be attended with the most fatal consequences. 
 To obviate this difficulty, Lieut. G. Linde- 
 say, R.N. proposes to take two bearings of the 
 sun, as near noon as possible, noting the time 
 elapsed by a good watch, and from these data 
 to compute the sun's meridian altitude in the 
 usual way, which will give the latitude and 
 apparent time at the ship; and this latter, 
 compared with the Greenwich time, will give 
 the longitude. For taking the sun's bearing 
 he proposes to attach to a common compass, 
 mounted on a pivot at the summit of a tripod, 
 a telescope, turning upon a joint, and a mag- 
 nifying glass to read off the divisions, as 
 shown in the annexed diagram. It appears 
 to us that the common azimuth compass (with 
 which all ships are or ought to be provided,) 
 will be found much superior to the above 
 contrivance, by which we fear it would 
 be difficult to observe the bearing with 
 sufficient accuracy. 
 
 COMPASSES (MATHEMATICAL). Instru- 
 ments for describing circles, measuring lines, 
 
 &c. They are of various descriptions; the common consist of two sharp- 
 pointed branches or legs, turning upon a hinge at top. Triangular compasses 
 are constructed as the ordinary compasses, with the addition of a third leg 
 turning upon a universal joint ; they are used in laying down places on a chart, 
 or measuring angles. 
 
 Beam Compasses are for the purpose of describing circles of considerable 
 radius, and consist of a straight bar of wood or metal, of suitable length, 
 furnished with a fixed point as a centre, and a movable tracing point, which 
 may be set to any required radius. 
 
 Elliptical Compasses, likewise called a "trammel," for the purpose of describl-y 
 ellipses, consist of a bar with a fixed tracing point, and two cursors, which can 
 be set upon any part of the bar, and which have a sliding motion in two grooves 
 cut in a piece of brass, which grooves intersect each other at right angles. 
 
 Proportional Compasses are composed of two flat bars pointed at the end, 
 and having a groove down the middle, in any part of which can be set a steel 
 pivot, held fast by a tightening screw, by which means the compasses can be 
 divided into two parts, bearing any required proportion to each other, and 
 which, turning upon the pivot in the manner of a pair of scissors, the angles 
 at the opposite extremities will be proportional to the length of the respective 
 parts. 
 
 COMPOSITION OF FORCES is the finding a single force which shall he 
 equal to two or more given forces when acting in given directions, the principles 
 of which may be thus illustrated. If two forces, moving in the direction of the 
 two adjacent sides of a parallelogram with velocities proportional to the length 
 of the sides of the said parallelogram, impinge upon a body, it will cause that 
 body to move over the diagonal of the parallelogram in the same time that 
 either of the forces singly would have impelled it along its corresponding side. 
 This may be demonstrated experimentally by an ingenious apparatus, designed 
 and executed by Mr. C. Holtzapfell, of Charing-cross, and which is exhibited
 
 302 
 
 CONDENSER 
 
 in the annexed engraving. 
 The apparatus consists of a 
 rectangular board, with a 
 perpendicular brass pillar 
 fixed in one corner. Two 
 guide steel wires extend 
 from the flanch at the bot- 
 tom to the cap at the top, 
 and sufficiently distant from 
 the pillar to allow the two 
 ivory balls a and b to descend 
 upon them without touching 
 the pillar. The board is 
 made perfectly flat, var- 
 nished, and polished, and 
 when used, must be placed 
 perfectly level. At the point 
 where two straight lines from 
 the bottom of the guide wires would meet and make a right angle, a small 
 hollow is made to receive a ball c. The weights of the balls a and b are 
 adjusted to correspond with the length of the sides of the board ; so that when 
 the ball a is dropped, it will give an impulse to the ball c, and send it to the 
 end of the board in the direction of the line d in the same time that the ball b 
 would send it to the edge of the board in the direction e. If now both balls be 
 dropped at the same instant from the same height, they will propel the ball in 
 the diagonal c f of the parallelogram in the same time that one of them singly 
 would have impelled it along one of the sides. 
 
 COMPRESSIBILITY, in Philosophy, that quality of a body by which it 
 yields to the pressure of another body, so as to be reduced within a smaller 
 compass. The compressibility of liquids is still a matter of doubt with philo- 
 sophers, although some consider the fact proved by the experiments of Mr. 
 Canton, and, more lately, of Mr. Perkins. According to the former gentleman, 
 the compression of 
 
 parts. 
 
 1,000,000 
 3 
 
 Spirits of wine, spec. grav. 846 was 
 Rain water . . 1000 . . 
 Mercury . . . 13,595 . . 100000 o 
 
 CONDENSATION. The art by which a body is rendered more dense, 
 compact, and heavy. Condensation is by most writers distinguished from 
 compression, by considering the latter as effected by mechanical force or pres- 
 sure, and the former by cold, or the abstraction of heat. 
 
 CONDENSER. A vessel in which aqueous or spirituous vapours are 
 reduced to a liquid form, either by injection of a quantity of cold water, as in 
 the condenser of a steam-engine; or when this is inadmissible, as in the case of 
 alcoholic vapour, by placing the condenser in another vessel, through which is 
 maintained a constant current of water, the condenser being so constructed as 
 to expose the steam or vapour in thin strata over an extended surface to the 
 action of the cooling medium. The condensers employed by distillers are 
 usually composed of a long tube of pure tin, or of copper tinned, formed into a 
 series of concentric coils over one another, and from its shape denominated a 
 worm ; this is placed in a large vat, which is called the worm-tub. But when 
 the distillation is carried on upon a large scale, the worm is not of a cylindric 
 section, as it is not the form which is best adapted for the purpose of conden- 
 sation ; for on account of the large diameter of the tube, which then becomes 
 necessary, that portion of vapour which occupies the centre of the tube is not 
 brought into sufficiently intimate contact with the cooling surfaces, and there- 
 fore either escapes condensation, or requires a much larger quantity of water 
 than would be otherwise necessary. Various arrangements have, in conse-
 
 CONIC SECTIONS. 393 
 
 quence, been devised for presenting the vapour in extremely thin strata, so as 
 to obtain a ready condensation with the least quantity of water. One invented 
 by Mr. Wheeler, of High Wycomb, appears to us very judiciously arranged for 
 this purpose ; it is denominated by the inventor the Archimedes' Condenser, and 
 is represented in the accompanying en- 
 graving, a is the pipe leading from the 
 neck of the still, through which the 
 vapours nter into the flat chambers b b 
 (represented black). These chambers, 
 owing to the sectional view, appear to 
 be disconnected, but they are wound 
 spirally round a central tube, and termi- 
 nate at the cock c, where the condensed 
 products pass off; d is a pipe leading 
 from a reservoir of cold water to the 
 bottom of the central tube, where it 
 passes through holes represented at ee 
 underneath the vapour chambers, and 
 can only ascend in the vessel by passing 
 successively through every coil, as each 
 turn of the spiral is connected by the 
 edge of one of its plates to the side of 
 the containing vessel. The water thus 
 heated in its progress flows out at the 
 aperture / into a trough or pipe. By 
 this arrangement it will be noticed that 
 the hot vapour or fluid is constantly 
 descending spirally an inclined plane, 
 while the cold fluid is constantly ascend- 
 ing, almost in contact with the other, as 
 they are only separated by a very thin 
 plate, formed of the best conducting 
 substance (copper). It will likewise be 
 evident that two fluids, one cold and the 
 
 other hot, may thus be made to exchange their temperatures. Thus, if cold 
 water at 50 Fahr. be admitted at the bottom of the vessel, it will, when it 
 arrives at the top, be nearly of the same temperature as the vapour or liquid 
 (say 200), which entered at the top, by having gradually abstracted the heat 
 from the vapour or hot liquid in its progress. This being understood, it follows 
 that the latter, having gradually parted with its heat in its descent, will become 
 of the same, or nearly the same temperature at the termination of its course 
 as the water, namely 50, provided the liquids be admitted in their proper 
 volume, which is easily regulated by the cocks. 
 
 CO ^E. A geometrical figure generated by the revolution of a right angled 
 triangle upon one of its short sides, as an axis. 
 
 CONGELATION. The transition of a liquid to a solid state, in conse- 
 quence of the abstraction of heat : thus metals, oil, water, &c., are said to 
 congeal when they pass from a fluid to a solid state. With regard to fluids, 
 congelation is the same as FREEZING, which see. 
 
 CONIC SECTIONS are the figures formed by the cutting of a cone by a 
 plane ; they are five in number, corresponding to the different positions of the 
 cutting-plane. When the cutting-plane passes through the apex of the cone, 
 and coincides with the axis, the section is a triangle. When the plane cuts the 
 axis at right angles, the section is a circle. When the plane cutting the axis 
 obliquely, and passing through both sides of the cone, the section is an ellipsis. 
 When the plane cuts the axis in a line parallel to one side of the cone, the 
 section is a parabola : and lastly, when the plane either does not cut the axis, 
 or cutting it forms with it an angle less than that formed by the side with it, 
 the section is an hyperbola. The term conic section is applied more peculiarly 
 to the three last figures ; and the doctrines of their several properties constitute
 
 394 COOPER^ G. 
 
 one principal branch of geometry, of great importance in astronomy and many 
 other sciences. See GEOMETRY. 
 
 CONOID. A solid produced by the circumvolution of the section of a 
 cone about its axis, and consequently may be either an elliptical conoid (other- 
 wise called a spheroid), a hyperbolical conoid, or a parabolical conoid. 
 
 CONTRACTED VEIN, in Hydraulics, a term denoting the diminution 
 which takes place in the diameter of a stream of water issuing from a vessel at 
 a short distance from the discharging aperture, owing to the particles nearest 
 the periphery experiencing greater attrition than the rest, and being retarded ; 
 in consequence of which the least diameter of the stream is to the diameter of 
 the orifice, on an average as 1 to the square root of 2 ; and in computing 
 the discharge of fluids, this proportion should be substituted for the real 
 aperture. 
 
 CONTRATE WHEEL, or CROWN WHEEL. A wheel in which the teeth do 
 not radiate from the axis, but stand at right angles to the arms, or parallel to 
 the axis. It is chiefly used for clock-work. 
 
 COOLER, among brewers, distillers, &c. is a large shallow vessel in which 
 liquids are exposed to cool. 
 
 COOPERING is the art of manufacturing casks, barrels, vats, and all kinds 
 of circular or elliptic wooden vessels, that are bound together by hoops. There 
 are several classes of coopers, some of whom carry on their peculiar branches 
 distinctly, while others embrace the general manufacture in one establishment. 
 The workmen, however, generally confine themselves to the particular line they 
 have been brought up to, and in which they are consequently most expert. 
 Thus we hear of "butt coopers," "rundlet coopers," "dry coopers, 1 ' "white 
 coopers," and "wine coopers." The work of the butt coopers chiefly consists 
 in the manufacture and repair of casks for breweries, also puncheons and 
 hogsheads. Their principal tools are very few, but they use these with so much 
 dexterity and skill as to produce with surprising facility and dispatch the most 
 solid, accurate, and substantial work. With an axe, an adze, two or three 
 spoke shaves, and a bench, the cooper rapidly gives a new and perfect form to 
 the material he operates upon. The bench consists simply of a stout plank 4 or 
 5 feet long, and 1 foot wide ; it stands upon four feet, but considerably inclined, 
 one end of the bench being usually about 2 feet high, and the other 6 or 8 
 inches lower. On the bench are fixed "stops " and " keeps," for the purpose of 
 holding the staves or other work. This cooper has also a large plane, called a 
 iointer, which is usually fixed with its face upwards, and against which he forces 
 the staves to shoot their edges to a smooth surface, (whether those edges are 
 required straight or curved,) in order to make the "joints " or joinings of the 
 staves come into perfect and hardly-pressed contact, when they are brought 
 together to form the vessel. To describe ah 1 , or even the leading operations, of 
 the cooper, would be uninteresting, because it is so openly and universally prac- 
 tised. We shall therefore proceed to notice, and that briefly, the nature of the 
 occupations of the other classes of coopers mentioned ; and afterwards we shall 
 insert some patented improvements in the art, that appear to be deserving of 
 notice. The rundlet coopers make use of the same tools, or nearly so, as in 
 the branch of the trade last described, but of less dimensions. Their work 
 consists chiefly in the manufacture of bottles, and small casks, for holding the 
 products of the distilleries, besides numerous other purposes. The dry coopers 
 are employed in manufacturing sugar hogsheads, and casks of every size and 
 quality, for holding dry goods ; and as such vessels are seldom required air and 
 water-tight, the workmanship is comparatively coarse to that of the butt and 
 rundlet coopers, and the expense proportionally less. The white coopers manu- 
 facture all kinds of domestic utensils, such as are used for brewing on the small 
 scale; for washing tubs, churns, pails, and a great variety of other work. To 
 this branch of coopering is frequently added the coarser kinds of turnery for 
 domestic use. The wine cooper's business consists chiefly in the removal and 
 depositing of wines and spirits, which he is enabled to effect with greater security 
 and convenience than other persons, who are not so intimately acquainted with 
 the nature and strength of tlie vessels containing them. The bottling, storing,
 
 COOPERING. 395 
 
 and packing of wines, and other liquors, belong to this branch of trade, besides 
 the making of all repairs and alterations in the butts or casks which may be 
 found necessary. Although the manufacture of backs and vats appears of a 
 similar character to other coopering, yet it is usually made a distinct branch of 
 business, and is performed by persons who call themselves back and vat makers. 
 From the variety of forms, and the immense strength required for some of the 
 backs, as well as for the frame-work to support them, the knowledge and skill 
 of the carpenter is almost constantly required, and not unfrequently the aid of 
 the engineer. In America, and several parts of Europe, machinery has been 
 extensively introduced to facilitate the labours of the cooper. In 1811, a patent 
 was taken out by Messrs. Flasket and Brown for the following' mode of 
 operating ; and as the exclusive privilege granted to those gentlemen is expired, 
 those of our readers who may be so disposed are at liberty to adopt the mechanism 
 employed, which is thus described in Dr. Gregory's Mechanics. 
 
 " First, the machinery for cutting the stave consists of a stout bench, having 
 a board or platform annexed to it, capable of being moved endways, to which 
 another board is connected, so arranged as to be moved across steadily by 
 racks and pinions, or screws. The last board has a hollow part made in it, in 
 which the stave-board may be laid, so that one edge of it may project clear 
 oeyond the edge of the first-mentioned board ; a circular saw is placed either 
 above or below the bench, having its axis at right angles to the line of motion 
 of the first mentioned board, and opposed to the direction of the course of the 
 projecting part of the stave-board; this circular saw is made flat when the 
 straight-edged staves are to be cut, and is dished, or of a spherical shape, 
 when staves with curved edges are wanted. The board first mentioned is moved 
 either in a right line, or is made to assume a curved course, by being confined 
 in its motion by curved grooves, or by curved rods moving against pins ; and 
 by the proper management of these sliding-boards, the stave-board is cut by 
 the circular saw of the shape desired. The machinery next used consists of 
 a large lathe, in which the cask is turned in a vertical position when it is of a 
 large size (after it is formed in the usual manner from the staves prepared as 
 above described), being either fixed in a great chuck placed beneath it, or in a 
 cylindrical cage whicli surrounds it, fixed upon a strong upright arbor, and 
 revolving between collars, where it serves the office of a mandrill In this 
 lathe the chime and groove for receiving the head are turned in the cask by 
 the application of a proper tool. When the cask is small, the cage is made to 
 turn in a horizontal position instead of revolving vertically. The third opera- 
 tion is to form the head, which is pinioned together as usual, after having the 
 pin-holes made by piercers projecting from the mandrill of a lathe, the dis- 
 tances and depths of which holes are correctly regulated by gauges ; it is then 
 turned on a flat revolving table, from which points project to hold it fast, and 
 against which it is held by another revolving piece that is screwed towards the 
 first, where it is brought to the proper size of the cask by fit tools. The fourth 
 operation is to turn the whole cask at the outside, for which purpose it is placed 
 in a large lathe between two chucks, made to fit into the chines, and attached 
 to the head by points ; and then the surface of the cask is turned smooth by a 
 spokeshave, or other fit instrument, held against it by a rest properly placed for 
 the purpose. The patentees bend their wooden hoops for their casks in an 
 expeditious manner, by fastening one end of them to the circumference of a 
 wheel, and pressing them against the wheel as it is turned round ; they also 
 describe a method of forming the projecting part in the bung-staves of the 
 small casks called bottles, by flat or concave circular saws, which cut the face 
 of the stave on each side close up to the projection ; and lastly, in giving 
 motion to this machinery, the inventors use any of the usual first movers and 
 mill work as may be necessary." 
 
 It is due to Mr. George Smart, of Westminster Bridge, to state, that, for 
 some years previous to the date of the patent granted to Messrs. Flasket and 
 Brown, he had in actual operation, on a very extensive scale, a similar arrange- 
 ment of machinery for making small casks, particularly canteens for the army. 
 The saws and other apparatus were of course more diminutive, but the accu-
 
 39G COPPER. 
 
 racy of their work may be judged of when it is stated that there was no occa- 
 sion to plane the edges of the staves to render the bottles water-tight, although 
 submitted to a severe test. 
 
 COPAL. A hard, shining, transparent concrete juice, obtained from an 
 American tree ; but which, although it is commonly considered a gum, has 
 neither the solubility in water common to gums, nor the solubility in alcohol 
 common to resins, except in a very slight degree. It may be dissolved by 
 digestion in linseed oil, rendered drying by quick lime, with a heat very little 
 less than is sufficient to boil or decompose the oil. This solution, diluted with 
 oil of turpentine, forms a beautiful transparent varnish, which, when properly 
 applied, and slowly dried, is very hard and durable. It preserves and gives 
 lustre to paintings, and greatly restores the decayed colours of old pictures, by 
 filling up the cracks, and rendering the surfaces of reflected light more 
 uniform. It has been observed by Mr. Sheldrake, that if powdered copal be 
 triturated with a little camphor, it softens and becomes a coherent mass ; and 
 camphor, added either to alcohol or oil of turpentine, renders it a solvent of 
 copal. Half an ounce of camphor is sufficient for a quart of oil of turpentine, 
 which should be of good quality ; and the copal, about the size of a walnut, 
 should be broken into small pieces, but not to powder. The mixture should 
 be set on a fire, so brisk as to make it boil almost immediately. The 
 vessel should be of metal, strong, with a long neck, and capable of holding 
 about two quarts. The mouth should be stopped with a cork, having a 
 notch cut in it to prevent its bursting. Mr. Cornelius Varley (who has 
 bestowed much judicious attention to the preparation of artists' materials), states 
 that a good copal varnish may be prepared by pouring upon the purest lumps 
 of copal, reduced to a fine mass in a mortar, colourless spirits of turpentine, to 
 about one-third higher than the copal, and triturating the mixture occasionally 
 in the course of the day. Next morning it may be poured off into a bottle for 
 use. Successive portions of oil of turpentine may thus be worked with the 
 same. Oil of lavender is stated to be alone a solvent of copal, which is probably 
 owing to the camphor contained in the former. Camphorated oil of turpentine 
 will also dissolve copal, but a mixture of camphor and alcohol effects it more 
 readily. 
 
 COPPER is a metal of a reddish brown colour, hard, very malleable, ductile, 
 and sonorous ; of considerable tenacity, and of a specific gravity from 8.6 to 8.9, 
 The good quality of copper is shown by its capability of alloying silver, without 
 any diminution of its extensibility under the hammer or roller. For this reason 
 the Swedish copper has a decided preference in the preparation of the alloys 
 of gold and silver; and its superior purity has been found to render it far more 
 durable when employed in the sheathing of ships, as well as for many other 
 purposes. English copper is chiefly obtained from the mines of Cornwall and 
 Devonshire, whence it is usually transported across the Bristol Channel to be 
 smelted at the coal-works in South Wales. The ores consist chiefly of yellow 
 copper ore, or copper pyrites, and the grey sulphuret of copper. The average 
 produce in copper is said to be about 84 parts from 100 of the ore. The 
 ordinary processes of smelting consist of alternate calcinations and fusions in 
 reverbatory furnaces of the usual construction. The calcining furnaces are 
 furnished with four doors or openings, two on each side, for the convenience 
 of stirring the ore and drawing it out of the furnace. They are commonly 
 from 17 to 19 feet in length from the bridge to the flue, and from 14 to 16 
 feet in width, with a fire-place 5 feet by 3. The melting furnaces are usually 
 about one-third the area of the calciners, but their fire-places are nearly as 
 large, and they have only one door, and that in front. The charge of ore for 
 a calcining furnace usually consists of about 3 tons, which is uniformly dis- 
 tributed over the bottom. When charged, the heat is gradually increased 
 during twelve hours, until near the point of fusion, when the ore is discharged 
 through holes in the bottom, and is suffered to lie underneath until it is suffi- 
 ciently cool to be removed. With this calcined ore, which is in the form of a 
 black powder, the melting furnace is charged, by spreading it over the bottom 
 thereof. A few slags from the previous fusions are added, and the door
 
 COPPER. 397 
 
 is closed and luted. When brought into fusion, the liquid mass is well 
 stirred, and the oxides and earthy matters which float at the top are skimmed off 
 through the front door by the smelters. When this first mass of metal has been 
 freed from the last-mentioned impurities, the smelter lets down into the furnace 
 a second charge of calcined ore, and proceeds with it in the same manner as 
 with the first, repeating the charges until the furnace will hold no more, when 
 a tapping-hole made in the side of the furnace is opened, and the metal runs 
 through it into a pit filled with water, which causes the metal to become granu- 
 lated, in which state it contains about one-third part of copper. The slags 
 which have been cast in sand-moulds, are afterwards broken to ascertain if 
 they contain any metal ; the pieces that do are then remelted to separate it. 
 When the ores are difficult of fusion, some fluor spar is added to the charge. 
 The coarse metal obtained by the preceding process is then calcined by a similar 
 treatment to that which the ore received. To oxidize the iron with which the 
 copper is contaminated, the charge is allowed to remain twenty-four hours in the 
 furnace, where it is repeatedly stirred and turned. The metal thus calcined is 
 then to be melted again with some slags from the previous melting, to which 
 may be added some pieces of furnace bottoms, which are impregnated with the 
 metal. The slags from this operation are also skimmed off; they have a great 
 specific gravity, being composed chiefly of the oxide of iron ; they fuse readily, 
 and act as fluxes to reduce further portions of the ore. The metal obtained 
 from the second operation of the melting furnace, after the slag has been 
 separated, is tapped off either into sand-moulds or into water. In the former 
 plan the product is collected in a mass, and is called blue metal ; in the latter it 
 becomes granulated, and is denominated fine meted. The quantity of pure 
 copper these products contain is about 60 per cent. The subsequent calcination 
 and fusion of these last products is conducted by a repetition of the operations 
 described ; and the result of this third melting are pigs containing from 80 to 
 90 per cent, of pure metal. The fourth process is, for the most part, an 
 oxidizing, or, as it is called, a roasting of the pigs obtained in the third. For 
 this purpose the furnace is filled with the pigs to the extent of 25 or 30 cwt. 
 which are exposed to the action of the air, while the heat is gradually increased 
 to the melting point, which facilitates the expulsion of the volatile matters, and 
 oxidizes the iron or other metallic substances that may remain. This operation 
 is continued from 12 to 24 hours, according to the degree of purity of the 
 pigs when put into the furnace ; and when completed, the metal is brought to 
 a state of fusion,- and run out into sand beds. The ebullition of the metal 
 arising from the extrication of the expanded air from the sand under the 
 metal, caused the latter to assume in cooling a honey-comb texture internally, 
 with a blistered surface ; and, from this latter appearance, such copper is 
 denominated blistered copper. The copper in this stage being freed from its 
 more abundant contaminations is ready for the refining furnace, which is of a 
 similar construction to the melting furnace, only that the bottom, instead of 
 being of fire-brick, is a bed of sand, laid to incline to the furnace door, near 
 to which a pool is formed for the purpose of lading out the refined copper. 
 The furnace is charged with from three to five tons of the blistered pigs ; the 
 heat applied to them is at first moderate, and air is admitted so as to continue 
 the oxidation, should the metal not be quite fine. - When this charge is fused, 
 and the slags skimmed off, an assay is taken by the refiner with a small ladle, 
 and the metal broken in a vice. From the appearances of the metal both in and 
 out of the furnace, the refiner judges whether it is in a sufficiently forward state 
 to undergo the toughening process ; previous to which the copper is of a deep 
 red colour, inclining to purple, with an open crystalline structure. In the pro- 
 cess of toughening, the surface of the metal is first covered over with charcoal ; 
 a pole, commonly of birch, is then held in the liquid metal in the furnace, which 
 causes considerable ebullition, owing to the evolution of gaseous matter ; and this 
 operation of poling is continued with the occasional addition of fresh charcoal, 
 until the quality of the assays, which the refiner takes from time to time, attain 
 the required degree of purity indicated by the polished silky appearance of the 
 metal when cut half way through, the light red colour of it when broken, and 
 3 E
 
 398 COPPER. 
 
 *,he closeness of the grain. After this a trial of the malleability of the copper 
 is made by taking out a small quantity in a ladle, casting it in a metallic 
 mould, and then hammering it out upon an anvil ; if it does not crack at the 
 edges by this operation, it is deemed in a fit state to be withdrawn from the 
 furnace, which is done by lading it out and casting it into rectangular cakes, 12 
 inches wide by 18 inches long. In preparing copper for the manufacture of 
 brass, it is usual to granulate it by pouring the hot metal through a colander 
 placed over a cistern of cold water, which causes the drops of metal to assume 
 by contact with the cold fluid, a ragged appearance, and to which the name oi 
 feathered shot is given in the trade. For making brass that is to be drawn into 
 wire, the same process as the last is employed, except that the metsl is poured 
 into hot water ; the drops, in consequence, take an oblong form, and are hence 
 termed bean shot. In granulating copper, it should be poured into the water by 
 small quantities at a time to prevent explosions. A considerable quantity of 
 copper is exported by the East India Company under the denomination of 
 Japan copper. It is cast in small sticks about six inches long, and weighing 
 about half a pound each. It is of a rich red colour, caused by throwing the 
 cast sticks, as soon as they have become solid in their moulds, into water. 
 Copper unites readily with several of the metals. Its combination with tin is 
 effected at a less heat than is necessary to melt the copper ; on which circum- 
 stance is grounded the method of tinning copper vessels. For this purpose 
 they are first scraped or scoured, and afterwards rubbed with sal ammoniac. 
 They are then heated (usually over a charcoal fire), and sprinkled with pow- 
 dered resin, which defends the clean surface of the copper from acquiring the 
 slight film of oxide that would prevent the cohesion of the tin to its surface. 
 The melted tin is then poured into the vessels, and spread about. An extremely 
 small quantity adheres to the copper, which is supposed to be sufficient to 
 prevent the noxious effects of the copper. When tin is melted with copper, 
 it forms the ancient compound termed bronze, the specific gravity of which is 
 remarkable for being greater than would be deduced by computation from the 
 bulks and specific gravities of its component parts. The uses of this hard, 
 sonorous, and durable composition, in the fabrication of cannon, bells, statues, 
 and other articles, are well known. The ancients made cutting instruments of 
 this alloy. A dagger analysed by M. Hielm consisted of 83 copper, and 16| 
 tin. Copper unites with bismuth, and forms a reddish white alloy. Wi'h 
 arsenic it forms a white brittle compound called tombac ; with zinc it forn 
 the important compound called brass ; and it is distinguished by various othex 
 names, according to the proportions of the two ingredients. It is not easy to 
 unite these two metals in considerable quantities by fusion, because the zinc is 
 volatilized at a heat inferior to that which is required to melt the copper, but 
 they unite very well in the way of cementation. There are various ways of 
 uniting granulated or small pieces of copper with zinc, but the following is the 
 ordinary method adopted in this country. Calamine, which is an ore of zinc, 
 is calcined in a kiln, or made ret hot, then ground to powder, sifted fine, and 
 mixed with ground charcoal, as the calamine is apt to clod and prevent an 
 uniform admixture. About seven pounds of calamine are put into a melting 
 pot of about a gallon content, to which are added about five pounds of the 
 granulated copper ; the calamine must be mixed with as much charcoal as will 
 fill the pot, and the copper must lie uppermost. This is let down with tongs 
 into a wind furnace, 8 feet deep, where it remains 11 hours. One furnace 
 usually holds eight pots arranged in a circle round a grate. By the heat the 
 zinc becomes revived, rises in vapour, and combines with the copper, which it 
 converts into brass. Towards the end of the process the heat is suddenly 
 raised, which causes the brass to melt and occupy the lower part of the 
 crucible. After melting it is cast into plates or ingots for use, as it is required. 
 The following method of making brass, mentioned by Cramer, is recommended 
 by the scientific Dr. Ure. The powdered calamine being mixed with an equal 
 quantity of charcoal, and a portion of clay, is to be rammed into a melting 
 vessel^ and a quantity of copper, amounting to two-thirds of the weight of 
 calamine. must be placed on the top, and covered with charcoal. By this
 
 COPYING PRESS. 399 
 
 method ihe volatile zinc ascends and converts the copper into brass, which 
 flows into the rammed clay ; consequently, if the calamine contain lead, or 
 any other metal, it will not enter into brass, the zinc alone being raised by the 
 heat. Copper unites readily with antimony, a compound of a beautiful violet 
 colour. It does not readily unite with manganese. With tungsten it forms a 
 dark brown spongy alloy, which is somewhat ductile. See ALLOV. 
 
 COPPERAS. A name apparently given by persons ignorant of its true 
 nature, to the sulphate of iron, obtained by the decomposition of iron pyrites. 
 The English copperas, or green vitrjpl, as it is also called, is made from the 
 natural combination of iron with sulphur, known in the various places where 
 they are found, by the several names of copperas stones, horse gold, gold 
 stones, &c. These are collected in great quantities, and laid in heaps about two 
 feet thick, upon a clay floor, surrounded by boards, that direct the rain water 
 that falls upon them to flow into a cistern. The clay floors at some works are 
 1 00 feet long, 1 5 broad at top, but narrowing to 1 2 at bottom, as they shelve 
 gradually to allow the water to run off easier. The cistern usually contains 
 about 100 tons of water. The copperas stones lie 5 or 6 years before they 
 yield a strong liquor. The sun and rain are found to be the proper agents; and 
 that other water, although prepared by exposure to the sun, and sprinkled on 
 them, only retards the produce. After a time these stones change to a vitriolic 
 earth, which swells and ferments like leavened dough. When a new bed is 
 made, the work is hastened by mixing a good quantity of the old fermented 
 earth with the new stones; and when this has come to perfection, it is refreshed 
 every fourth year by a layer of fresh copperas stones on the top. The copperas 
 water is considered rich if it weigh fourteen-eightieths more than water. Thf 
 jopperas liquor is boiled in leaden vessels, containing about twelve tons. AbouV. 
 a cwt. of old iron is put into it at first, and more added as it dissolves, 
 amounting, in one boiling, to about 15 cwt. Fresh water from another boiler 
 is added to supply the loss from evaporation. When the boiling is finished, 
 (which is determined by the deposition of crystals in a little earthen vessel, 
 after a small quantity has been allowed to cool therein,) the liquor is drawn off 
 into a tarras cistern 20 feet long, 5 feet deep, 9 feet over at top, but tapering 
 towards the bottom, where, being left for a fortnight to cool and crystallize, the 
 remaining liquor is drawn off, and is reserved for boiling with new liquor. 
 At the bottom and sides of the cistern or coolers there is usually a crystalline 
 deposit 5 inches thick, that at the sides being of a bright colour, while that at 
 the bottom is foul and dirty. At some works, instead of putting all the iron 
 into the boiler, a portion of it is added to the liquor in the cistern before 
 boiling. When the pyrites is too abundant in sulphur, and does not alter by 
 exposure to the weather, it is usual to roast it in piles to drive off the super- 
 abundance ; and when the sulphur is required as a separate product, to distil 
 the pyrites in close vessels. Copperas is also formed by simply exposing some 
 kinds of bituminous earth to air and moisture, from which the crystals are 
 afterwards obtained by washing. The French also manufacture copperas by 
 dissolving old iron in weak sulphuric acid, and crystallizing the solution. 
 Copperas crystallizes in the form of rhcmboidal prisms, which are transparent 
 and of a beautiful green colour. Its taste is harsh and styptic ; it reddens 
 vegetable blues ; two-thirds of cold water, or three-fourths of boiling water, 
 dissolve it. A moderate heat calcines and whitens copperas, by driving off the 
 water of crystallization ; a greater heat expels the sulphuric acid. Its con- 
 stituents, according to Berzelius, are 28.9 acid, 28.3 protoxide, and 43 water; 
 according to Mr. Ferret, 1 prime acid, 2 oxide, and 7 water. The chief uses 
 of copperas are the making of ink and in dying, 
 
 COPYING PRESS. A machine for speedily producing a fac-simile copy 
 of any manuscript recently written. The method is to place over the letter a 
 sheet of thin damp paper, and subject them both to the action of the press, by 
 which means a portion of the ink is transferred from the manuscript to the damp 
 paper. When letters are intended to be copied by this means, it is usual either 
 to make use of a kind of ink expressly prepared for the purpose, or to add a 
 portion of sugar to the common writing ink. The presses are variously con-
 
 400 
 
 CORAL. 
 
 etnicted; but the screw prsss, new so common in merchants' counting-houses, 
 is the invention of the celebrated James Watt, who obtained a patent for it 
 about forty years ago. The annexed figure represents an improvement upon 
 this machine, invented by Mr. Ritchie, of Edinburgh, a the bed of the press ; 
 
 ..-i:-"" ' '" 
 
 6 the platten ; c c handles which revolve on the screw d, and are used to draw 
 down the platten on the paper, &c. placed underneath ; e is a square piece of 
 steel in which the screw works; the square piece slides in a hole of a similar 
 figure on the head of the press, (as shown by the dotted lines at/), and on the 
 top of it is a small cam ff, operated upon by the lever h. The ordinary pressure 
 is given, as usual, by the screw; and the cam being subsequently brought down, 
 increases the force almost to infinity through a very small space, and, con- 
 sequently, by such a press, a person exerting only the usual force can print 
 effectually a larger surface. The other arrangements will be evident upon an 
 inspection of the drawing. 
 
 A very simple, and, at the same time, effectual, copying machine may be 
 made as follows : Take a roller of beech, or any hard wood, about 1 8 inches 
 long, and 1 inch in diameter, and having cut a longitudinal slit therein nearly 
 the whole length, insert in it and fasten very neatly with glue a slip of strong 
 cloth, about 14 inches wide, and 18 inches long; the remaining part of the 
 roller will serve as a handle, and may be cut with several faces to obtain a 
 firmer hold. To use this copying press, lay the sheet of paper on which the 
 letter is written upon the strip of cloth ; on that place the thin copying paper, 
 and upon these lay a thick baize, or horse-hair pad ; then roll the whole round 
 the roller, and grasping that part where the cloth is with the left hand, turn the 
 roller round with the right, gradually increasing the grasp with the left ; the 
 pressure becomes very great, and quite sufficient to transfer the letter to the 
 copying paper. 
 
 CORAL, and CORAL FISHERY. The substance called coral was formerly 
 considered to be of vegetable origin, but it is now admitted to be of animal 
 origin, belonging to the order Zoophytes : by analysis it is found to consist 
 almost wholly of animal matter and carbonate of lime. The coral plants, (as
 
 CORK. 401 
 
 they are termed) sometimes shoot out like trees without leaves in winter ; they 
 often spread out a broad surface like a fan, and not uncommonly a large bundling 
 head like a faggot ; sometimes they are found to resemble a plant, with leaves 
 and flowers, and often the antlers of a stag, with great exactness and regularity. 
 If, in our researches after the nature of these plants, we should be induced to 
 break off a branch of the coraline substance, and observe it carefully, we shall 
 perceive its whole surface, which is very rugged and irregular, covered with a 
 mucous fluid, and almost in every part studded with little jelly-like drops, 
 which, when closely examined, will be found to be no other than insects of the 
 polypus kind. If a coraline plant be strictly examined whilst growing in the 
 sea, and the animals upon the surface be not disturbed, either by the agitation 
 of the waters or the touch of the observer, the little polypi will then be seen in 
 infinite numbers, each issuing from its cell, and, in some kinds, the head 
 covered with a little shell resembling an umbrella, the arms spread abroad in 
 order to seize its prey, while the hinder part still remains attached to its 
 habitation, whence it never wholly removes. By this time it is perceived that 
 the number of its inhabitants is infinitely greater than was at first suspected ; 
 that they are all assiduously employed in the same pursuits; and that they 
 issue from their respective cells, and retire into them at pleasure. The true, or 
 red coral, was considered by Linnaeus as an isis, and arranged as such in the 
 Syslema, though Linnaeus himself acknowledged to Mr. Ellis, the author of the 
 Natural History of Zoophytes, that the latter had more properly classed it with 
 the gorgonia, or sea-fan. The red coral grows in an exposed and somewhat 
 flattened form, with dichotomous branches, that lessen towards their extremities. 
 The flesh is of the colour of red kad, or inclining to vermilion, soft, slippery, 
 and full of minute vessels. The mouths are placed on the surface, and rise up 
 i/i a conical form, consisting of eight valves, just opening, whence proceed polypi 
 of a white colour, with eight claws, each of which has a double fibre at both 
 edges. The bone, or shell itself, divested of the flesh, is the true coral of the 
 shops, and which, in its natural state, is of a strong texture, and of a bright red 
 colour, with the outside marked with minute furrows, or irregular striations, 
 interspersed with a few slight depressions, corresponding with the situation of 
 the shells before the flesh was removed. The coral fishery is a very lucrative 
 employment. The time for fishing is from April to July ; the places are the 
 Persian Gulf, the Red Sea, the coasts of Africa, towards the bastion of France, 
 the isles of Majorca and Corsica, and the coasts of Provence and Catalonia. 
 Spallanzini, in his Travels in the Two Sicilies, has particularly described the 
 coral fishery in the Strait of Messina. The instrument by which they force the 
 branches of coral from the rocks, is formed with two poles of wood, crossing 
 each other at right angles, and having a piece of net fastened on the under side 
 to their extremities. A large stone is fixed where the poles are crossed, that the 
 instrument may more readily sink to the bottom. A cord is strongly tied round 
 the middle of it, one end of which the fisherman holds in his hand, guiding by 
 it the net to those places where the coral is supposed to grow, and which is 
 enclosed in the pieces of the net, broken off and drawn up. The rocks which 
 produce the coral are situated almost in the middle of the Strait, at different 
 depths, from 350 to 650 feet. The bottom and caverns of the rocks are the 
 places from which they endeavour to bring up the coral in their nets, and it is 
 a constant observation, that every branch is perpendicular to the plane on 
 which it grows, without ever turning on one side. The coral fishermen have 
 divided the whole track in which they fish into ten parts. Every year they 
 fish in only one of these parts, and do not fish in it again till ten years are 
 elapsed. This interval of ten years they think necessary for the coral to acquire 
 its full growth in height and consistence. When they transgress this law they 
 find the coral smaller and of less consistence ; and the intensity of the colour 
 is always in proportion to the number of years they have desisted from fishing. 
 CORK. The bark of a tree growing wild in the southern parts of Europe, 
 especially in Spain ,and Portugal. When the tree is about fifteen years of age, 
 it may be barked ; and the operation may be repeated for several years, the 
 bark growing again, and its quality improving as the age of the tree increases.
 
 402 CORN. 
 
 It is chiefly used for forming stoppers for bottles, and floats for fishermen's 
 nets. 
 
 CORN. A general name for the various kinds of grain which serve as food for 
 man or other animals ; thus wheat, rye, barley, maize, &c., are comprehended 
 under the term corn. In England, however, it is usually understood to signify 
 wheat ; in America, and most parts of the world, the term implies maize, or 
 Indian corn. Owing to adventitious or natural circumstances, corn is fre- 
 quently combined with a variety of impurities, denominated smut-ball, dust- 
 brand, pepper-brand, mildew, must, besides a portion that is decayed or 
 partially eaten by insects ; there is also frequently a mixture of gravel, earth, 
 and different foreign substances, to a greater or less extent. To free corn from 
 these impurities, numerous machines have been designed, but their effec- 
 tiveness has proved so limited or partial, as to cause them to be very little 
 employed; and damaged or impure corn, in consequence, possesses a value 
 in the market far below what its intrinsic worth would be considered were there 
 known some simple and cheap process for separating effectually the good from 
 the bad. An apparatus for this purpose was, however, very recently patented, 
 
 which, in our opinion, is calculated to supply the desideratum in that 
 important branch of art, the experiments already made with it having proved 
 highly satisfactory. We make the following abstract from the specification 
 
 (leaving out the references to the drawing), which embraces other mechanism 
 and processes immediately connected with the subject under consideration. 
 
 Jfebert's Patent Scouring, Washing, and Separating Machine, This apparatus 
 " is brought into use whenever the adventitious or impure matter cannot be 
 effectually removed by sifting or other dry operation. The grain to be washed 
 I deposit on a floor in the upper part of a building, and contiguous to a 
 hopper that is fixed to, and passes through a cavity in the floor. Near to this 
 hopper I also collect a heap of very coarse sharp sand (fragments of buhr 
 stones answer well), which has been previously well washed and sifted, 
 
 detain only those particles which measure from a sixteenth to a thirtieth part 
 of an inch in diameter, and to free it from those which are either coarser or 
 finer. Into the said hopper I then throw a charge for the scouring cylinder 
 (situated underneath it on the next floor) ; the charge consisting of a mixture 
 of the grain and coarse sand, in the proportion of about five shovelsfull of 
 the grain to one of the sand in its wet state. The length of the scouring 
 cylinder should be proportioned to the magnitude of the operations intended to 
 be conducted by it; but its diameter should not be less than 30 or 36 inches, 
 in order that the pressure of the superincumbent portion upon the lower may 
 cause the sharp angles of the interposed coarse sand to scour off the impurities 
 adhering to the surfaces of the grain. A slow rotation of the cylinder for a 
 few minutes will in general suffice to complete this part of the process ; the 
 state of which may at any time be ascertained by drawing out a sample of the 
 grain througli a try-hole, made in one of the flat ends of the cylinder, and 
 provided with a stopper. When completed, the door in the cylinder is to be 
 unfastened, and the mixed materials are to be discharged into a large, flat, 
 rectangular sieve, suspended underneath it, and lying submerged in a large 
 body of water contained in a bath. This being done, the cylinder is to be 
 turned half way round upon its axis, so as to bring the open doorway upper- 
 most, and opposite to the short of the hopper above, in order to its being re- 
 charged as before ; after which the door is to be refastened. From this time, 
 and at every subsequent charge until the work is completed, both the scouring 
 cylinder and the washing and separating bath operate together, the grain in 
 the sieve being agitated by the rotative action of the cylinder in the following 
 manner. On the revolving axis of the cylinder is fixed a pulley, which, by 
 means of an endless corder chain and two guide pulleys (employed to convert 
 the vertical into a horizontal motion), causes a fourth pulley to revolve in a 
 horizontal plane : on the upper side of the last mentioned pulley is a plate, having 
 an eccentric groove, in which a pin fixed to the centre of the bottom of the sieve 
 works ; this arrangement, so far, causes the sieve to perform a circular motion 
 in the water ; but the sieve is suspended from its four corners to two projecting
 
 COTTON. 
 
 403 
 
 arms or levers, fastened to two horizontal spindles (acting as their fulcra), and 
 is, in consequence, made to incline alternately from side to side, in a constantly 
 varying plane, during each revolution of the eccentric plate before mentioned. 
 This compound motion produces a great agitation amongst the particles of corn 
 and sand, causing them to be quickly and thoroughly separated from each 
 other, and the corn to be well washed by the collision. The sand passes 
 through the meshes of the sieve, and is deposited at the bottom of the bath ; 
 the bad corn, from its inferior specific gravity, rises to the surface of the water, 
 whence it is floated away by a gentle current over a partition or dam in the 
 bath, into a receptacle on the other side, whence it flows through a spout out 
 of the machine. The current is produced by the constant running into the 
 bath of a small stream of water from a pipe and cock at the opposite end of 
 the bath, and a constant level of water is preserved by its running over the 
 dam. The purified corn alone remaining in the sieve, is now to be dis- 
 charged thence; for this purpose, two levers fixed to the before-mentioned 
 spindles, and connected by a rod (to cause them to move parallel with each 
 other), are brought into operation ; so that upon one of them being pulled, the 
 sieve is lifted out of the water and placed in an inclined position, by which the 
 contents are easily projected into* a contiguous hopper, where the corn is 
 allowed to drain during the washing of the succeeding charge of grain, and 
 then it is conducted into the kiln to be dried. See KILN. 
 
 CORROSIVE SUBLIMATE. The chloride of mercury; also called the 
 oxymuriate of mercury. 
 
 COTTON. The down of the cotton tree or plant, of which naturalists 
 recognise ten varieties. Some of these are to be met with in the warmer 
 parts of Europe ; but its cultivation to any extent is chiefly confined to 
 climates within the tropics. The generality of the West India species, are 
 annuals, whilst those of Asia are perennial both in branch and root, and rise 
 in a straight line about eight feet high. The cotton down is contained within 
 pods, which, when arrived at maturity, open. The down envelopes a husk 
 called the gin, which contains the seeds of the plant; and the first operation 
 in rendering cotton fit for manufacturing purposes, consists in freeing the down 
 from these seeds. This is effected by first drying it in the sun until the seeds 
 become quite hard ; and then operating upon it by a machine called a gin, of 
 which there are two kinds, the one called a roller gin and the other a saw gin. 
 The roller gin is represented in Fig. 1. It consists of two small fluted rollers 
 a b, about 1 inch in diameter, and 9 inches long, and generally made of 
 hard wood ; they are put in motion by the treadle c acting vpon cranks or 
 
 Fig. I. Fig. 2. 
 
 pins in the face of the fly-wheel d. The labourer who drives the machine 
 places the cotton on a feeding board, and the cotton is drawn in between the 
 rollers, which being set too close to allow the seeds to pass between them, the 
 cotton falls down the inclined board e, and the seeds drop into the box /. 
 The saw gin is given in Fig. 2. a is a roller having a number of circular 
 saws b fixed upon it, with a washer of wood between each ; c is a grating
 
 404 COTTON SPINNING. 
 
 through which a portion of the teeth of the saws project ; d is a circular brush 
 driven by the wheel e on the axis of a, which works into a pinion on the axis 
 of d. The cotton being put into the hopper f, the teeth of the saws lay 
 hold of the wool and tear it through the grating, whilst the seeds are by that 
 means separated, and roll down the inclined plane of the grating, and finally 
 escape at the spout g ; the cylindrical brush serves to clear the cotton from the 
 teeth of the saws, and throw it clear of the cylinder, in which state it is ready 
 to be packed for the market. 
 
 COTTON SPINNING; the operation by which cotton-wool is formed into 
 yarn. The most ancient and simple method of forming filamentous substances 
 into a continuous thread was undoubtedly by the distaff and spindle, a method 
 still practised by the natives of India, and which appears to be known to every 
 nation removed one step from absolute barbarism. The first improvement upon 
 this simple contrivance was the spinning wheel, invented at a remote and un- 
 certain period; and by means of this machine, with some slight improve- 
 ments in its construction, the operation of spinning continued to be performed 
 in this country until the latter part of the last century, when an entirely new 
 system was introduced in the art, the process being no longer dependent upon 
 the skill and intelligence of the artisan, but every part of it being performed 
 by mechanical means, with a degree of accuracy and dispatch before unknown. 
 The new system spread with great rapidity, and quickly raised our cotton 
 manufactures, which were previously of small importance, to rank amongst the 
 principal ones of the country. From a paper in the Repertory of Arts, it 
 appears that so early as 1730 Mr. John Wyatt, of Birmingham, conceived the 
 idea of spinning by machinery, and that becoming associated with a foreigner 
 named Lewis Paul, a patent was taken out in the narne of the latter in 1738. 
 In 1742 a mill was erected at Birmingham, which was turned by two asses. A 
 more successful result attended the exertions of Richard Hargreaves, a weaver 
 in Lancashire, who, in 1767, invented what is called the spinning jenny. 
 In 1769 R. Arkwright invented the method known by the name of water 
 spinning; and in 1779 Crompton combined the principles of jenny spinning 
 and water spinning into a system called mule spinning, and by one or other of 
 these three methods the operation is now performed. 
 
 We shall proceed to describe, as briefly as is consistent with perspicuity, each 
 of these methods, taking them in the order in which the inventions stand in 
 point of time ; but first, we must note the method by which the cotton wool 
 (which arrives in this country very imperfectly cleaned from seeds, dust, &c.) 
 is freed from these impurities. This operation, which is called batting, is 
 performed by a machine called a batter, of which the annexed cut is a diagram. 
 
 The cotton is laid upon the endless web, or band, passing round the rollers a b, 
 and by this band, which is called the feeding cloth, it is carried to the rollers 
 c d, which deliver it upon the curved rack or grating e, whilst a scutch /, 
 revolving rapidly upon its axis, strikes the cotton with its two edges and divides 
 it, and the gins, sand, &c. fall through the circular grating e, and down the 
 inclined grating i, at the same time a draft of air, created by the revolution of 
 the fan k, blows the cotton forward along the passage I into a box, from which
 
 COTTON SPINNING. 
 
 405 
 
 it is from time to time removed, any remaining seeds falling from the cotton 
 through the grating m, (which forms the bottom of the passage I,) as the 
 cotton is blown along the passage. 
 
 We shall now proceed to give a verbal description of the process of jenny 
 spinning, unaccompanied by any representations of the machinery, which 
 being the same as that which, combined with some other machinery, is used 
 in mule spinning, will be described under that head. The process is as follows : 
 The cotton, after batting, is soaped, by being immersed in a strong solution of 
 soap; then pressed in a screw press, and afterwards stove-dried. It is then 
 carded by a carding machine, from which it passes in the form of rolls, about 
 the size of a candle, on to an endless band, from which it is lifted by children, 
 and carried to be roved. The roving is performed on a billy, usually containing 
 thirty-six spindles, driven by bands from a cylinder turned by hand. Upon 
 the side next the carding engine is a feeding cloth, upon which the rolls from 
 the carding engine are united so as to form a number of rolls equal to the 
 number of spindles in the billy. After a certain number of revolutions of the 
 rollers of the feeding cloth, the cloth is stopped, and the rolls being held fast 
 between two clasps of wood, the ends are attached to the spindles, that are 
 mounted on a movable carriage, which, as it recedes, stretches the rolls and reduces 
 them to the proper size of the roving. In returning the carriage, the rovings 
 are built upon the spindles in the form of cones, receiving at the same time 
 a slight twist; and when a sufficient quantity of roving is wound upon the 
 spindles, they are removed to the spinning jenny. The spinning jenny differs 
 from the roving billy in having the clasp boards attached to movable frames or 
 carriages, and the spindles stationary. The clasps, by the receding of the 
 carriage, reduce the rovings *o the size for yarn, and during the return of the 
 carriage the yarn is built upon the spindles. Jenny yarn is now little used, 
 except for the weft of calicoes. Water spinning is the name given to Arkwright'a 
 method of spinning, because in all the mills in which it was first adopted the 
 machinery was driven by water. The distinguishing feature of this method is 
 the means by which the rovings are gradually reduced in thickness to the size 
 of the intended yarn. In jenny spinning, we have already stated, this ia 
 effected by nipping the rovings at one part between wooden clasps, and causing 
 the spindles to which the end of the rovings are attached to recede very 
 gradually ; hut in water spinning this is effected by passing the rovings between 
 the drawing rollers faster than it is taken in by the feed rollers ; the fibres slide 
 one over the other, and the roving is reduced in thickness, or extended in 
 length, in proportion to the difference of the velocities of the feed rollers and 
 drawing rollers. The process of water spinning is conducted as follows : 
 After batting, the wool is carded by two machines, the first called the breaker, 
 and the second the finisher. The annexed diagram will give some idea of the 
 
 nature of the operation, and of the construction of the machine. The cotton 
 is carried by the feeding cloth a a to the feed rollers b b, which deliver it on to 
 the carding cylinder c. This cylinder is covered with slips of leather, stuck 
 full of bent wires, forming what are called cards, which are ranged parallel to
 
 406 
 
 COTTON SPINNING. 
 
 the axis of the cylinder ; the arched top d of the box in which the cylinder is 
 enclosed is likewise covered with similar cards, the teeth of which incline in an 
 opposite direction ; as the cylinder slowly revolves, the cotton is repeatedly torn 
 from it by the top cards, from which it is recovered by the cylinder, until the 
 cotton at length reaches the doffer e, which is a cylinder with the cards ranged 
 round it in one continued spiral fillet, that strips the cotton wool from the 
 cylinder in a thin film, which is removed by a steel comb/, worked by a crank 
 g; and by the comb it is thrown on to a smooth cylinder h, called the lapping 
 cylinder ; this is surmounted by a light roller i, by which the film of wool is 
 pressed flat upon the cylinder, forming what is termed a lap. After a certain 
 number of layers are wound upon the lapping cylinder, which is called plying, 
 or doubling, the machine is stopped, and the lap broken off and removed to 
 the finisher, which has a carding cylinder, doffer, and comb, similar to the 
 breaker; but instead of the wool, as it comes from the comb, passing round a 
 lapping cylinder, it is drawn through a conical vessel by a pair of rollers, which 
 compress it, and deliver it in thin slivers or bands into tin cans; these, when full, 
 are removed to the draw frame, which is represented in the following diagram. 
 
 The draw frame contains several heads of rollers, each head composed of a 
 pair of feeding rollers a a, and a pair of draw rollers b b; the upper roller in 
 each pair is covered with leather, or some other elastic substance, and the 
 lower pair is formed of metal, and fluted. The ends of the slivers con- 
 tained in the cans c c are passed through the leader d, and brought under the 
 rollers a a and b b. If, now, we suppose the rollers b b to travel four times as 
 fast as the feed rollers a a, or to have a draught of four, as it is termed, the 
 slivers will be drawn out to four times their original 
 length. The slivers are united by passing through 
 a conical ring, and conducted by a pair of rollers 
 //, (which do not draw or extend the cotton,) into 
 another can g ; and if we suppose four ends to be thus 
 united, the sliver will be of the same thickness as 
 the original sliver, but of four times the length. 
 This operation being repeated through several other 
 heads on the same frame, the fibres of the cotton 
 are laid nearly parallel, the sliver becomes more 
 uniform, and is then ready to be carried to the 
 roving frame, in which, besides being reduced, it 
 receives a slight degree of twist. Roving frames 
 have been variously constructed, but the form most 
 approved and in most general use at the present 
 day is what is termed the spindle and flyer roving 
 frame, represented by the annexed diagram, a a, bb, 
 are draw rollers, between which the sliver is con- 
 ducted from the cam c, and reduced according to 
 the draught of the rollers ; d d is the flyer fixed upon 
 the top of the spindle e, which is put in motion by a 
 band passing over the wheel/. The rollers deliver 
 the reduced sliver to the flyers on the top of the
 
 COTTON SPINNING. 
 
 407 
 
 spindles, where it passes through an eye g, and thence proceeds down one of 
 the legs of the flyer (which is made tubular for that purpose,) to the bobbin A, 
 placed loosely on the spindle c, and supported on the rai^ The tube of the 
 flyer running swiftly round the bobbin, lays the roving (which thus acquires a 
 twist) on the bobbin as fast as the rollers deliver it ; and in order to cover the 
 surface of the bobbin with regularity, the rail i is made to ascend and descend 
 alternately with a slow motion. The bobbin, it will be observed, is dragged 
 round by the flyers, and but for the friction of the surface on which it rests, 
 would move as fast as the flyers ; but in this case it would take up no roving, 
 for the quantity taken up will depend upon the difference between the speed 
 of the flyer and the bobbin. A slight degree of friction is then necessary to 
 give the bobbin a slow motion, but as the bobbin becomes full, the weight 
 increases the friction, and consequently would retard the motion still further 
 if it were only dragged round by the flyer ; and as it is requisite that 
 the bobbin should always take up the same quantity of roving, its motion 
 is regulated so as to take up the roving exactly as fast as it is delivered from 
 the rollers. The mechanism by which this is accomplished varies in different 
 mills ; the following is one of the most approved methods. Two conical barrels 
 are placed opposite each other, the large end of the one fronting the small end 
 of the other. One of these barrels moving uniformly turns the other barrel, 
 by means of an endless strap, which, by being shifted towards either extremity, 
 varies the speed of the other barrel. The belt or strap remains equally tight 
 in every part of the barrels, for the diameter of the one increases in exactly the 
 same proportion as that of the other diminishes. From the second barrel 
 motion is conveyed to pulleys k resting on the bearer or rail t, and having the 
 spindles passing through the centre of each ; the bobbins rest on those pulleys, 
 and are carried round with them. The rovings are next carried to the spinning 
 frame. The spinning frame is similar in its operation to the roving frame, 
 except that it has generally three sets of drawing rollers, and from the greater 
 strength which the thread has acquired, no machinery is requisite to regulate 
 its motion ; it is therefore dragged round by the flyers. The bobbins, when 
 taken off the spindles filled with water twist for warps, are carried to be reeled. 
 The reel is composed of six rails, in front of which the bobbins are ranged on 
 pins, in a board extending the whole length of the reel. The dimensions of 
 the reel are such as that it requires exactly 1 yard to go round it ; the thread 
 from the bobbins, after passing between several wires, to give a proper degree 
 of tension, is made fast to one of the rails, and the wheel set in motion. After 
 eighty revolutions (one lay) a bell or click strikes, the reel is stopped, and the 
 lays are tied with pieces of thread to keep them distinct. Seven lays form a 
 hank. When the hanks are completed they are taken off the reel, for which 
 purpose one of the rails is hinged, which permits it to be folded inward, and 
 the hank being slided to one end of the reel, the reel is lifted off its bearing, 
 and the hanks are taken off. 
 
 It now remains to describe the ope- 
 ration of mule spinning. The preparation 
 is similar to that of water spinning; but 
 previously to the rovings receiving their 
 last reduction on the spinning frame, 
 they undergo a process called stretching. 
 The stretching frame nearly resembling 
 the mule, except in being of larger 
 dimensions: we shall proceed to de- 
 scribe the latter, by means of the 
 annexed diagram, a represents a roving 
 placed in a frame behind the drawing 
 rollers c d e. After passing between 
 the rollers, the reduced roving goes on 
 to the spindle/, which are like those of 
 the common jenny, and have neither bobbins nor flyers. The spindles are 
 placed in a reclining position, and supported on a carriage g. The machine
 
 408 COTTON SPINNING. 
 
 being put in motion, the carriage recedes as fast as the rollers deliver the 
 rovings, the spindles at the same time revolving rapidly, giving sufficient twist 
 to the yard to bear stretching. After the rollers have delivered a certain 
 length (a yard, for example,) of yarn thus imperfectly twisted, they stop, but 
 the carriage continues to recede half a yard further, for example, and the 
 spindles continue to revolve. The yarn is thus stretched, and forms a fair and 
 even thread. In order to save time, the spindles move more rapidly during the 
 process of stretching. The mechanism by which this is effected is called 
 double speed. The yarn being sufficiently hard twisted, the machine disengages 
 itself from the other moving parts of the mule ; the attendant then returns the 
 carriage home to the rollers. By this arrangement, comprising the advantages 
 Doth of the rollers and the spindles, the thread is stretched more gently and 
 equally, and a much finer quality of yarn can therefore be produced. This 
 excellent machine, which has superseded the jenny, and, to a considerable 
 extent, the water frame, and which has carried the cotton manufacture to a 
 perfection it could not otherwise have attained, was invented by Samuel Crompton, 
 a young weaver of respectable character and moderate circumstances, living at 
 HalHn-the-Wood, near Bolton, and was completed by him in 1779. Being of 
 a retiring and unambitious disposition he took out no patent, and only regretted 
 that public curiosity would not allow him " to enjoy his little invention to 
 himself in his garret," and to earn by his own manual labour, undisturbed, the 
 fruits of his ingenuity and perseverance. The very superior quality of his 
 yarn, it is said, drew persons from all quarters, to ascertain the manner whereby 
 rie produced it. He stated to Mr. Bannatyne, that, on the invention of his 
 machine, he obtained 14s. per Ib. for the spinning and preparation of No. 40, 
 (z. e. yarn of forty hanks to the pound) ; that a short time after he got 25s. 
 per Ib. for the spinning and preparation of No. 60 ; and that he ther spun a 
 small quantity of No. 80, to show that it was not impossible, as was supposed, 
 to spin yarn of so fine a grist, and for the spinning and preparation of this he 
 got 42s. per Ib. ! These prices were obtained by the unrivalled excellence of 
 the yarn ; and it affords a criterion to estimate the value of the machine, when 
 it is found that the price of yarn, No. 100, is at the present day only from 
 2s. 3d. to 3*. per Ib., including the cost of the raw material, which is from Wd. 
 to Is. per Ib., this surprising reduction having been effected chiefly by the powers 
 of the mule; and notwithstanding it was before supposed to be impossible to 
 spin 80 hanks to the pound, as many as 350 hanks to the pound have since 
 been spun, each hank measuring 840 yards, and forming together a thread 167 
 miles in length ! Although the principle of Crompton's machine was excellent, 
 it was rudely constructed ; his rollers were of wood, and all the parts clumsy ; 
 for Crompton was unused- to tools, and knew but little of mechanics before he 
 attempted to put to practice the beautiful combinations he had conceived. His 
 first machine contained but 20 or 30 spindles. Subsequently, Stones, of Harwich, 
 a machinist, constructed a mule in a workmanlike manner, making the rollers 
 of metal, and applying clock-work to move them; the mule was thus adapted 
 for 100 to 130 spindles. Baker, of Bury, and Hargraves, of Toddington, 
 introduced some improvements. In 1790, Mr. Kelly, of Lanark mills, applied 
 water power to the mule, and shortly after Mr. Wright, of Manchester, con- 
 structed a double mule. By these successive additions the machine was made 
 capable of working with no less than 400 spindles. Since this period mules have 
 been so much increased in size and effectiveness, that there are many at work 
 in Manchester and elsewhere of 800 spindles each, and some of the prodigious 
 number of 1100 spindles each, or 2200 the pair, the pair being managed by 
 one spinner. Mr. Crompton having made no attempt to secure this important 
 invention, Parliament was memorialized on the subject, and a grant of 5000/. 
 was obtained free of all charges ; and it is worthy of remark, that at this time 
 (1812), there were at work, on the principle of his invention, between four and 
 five millions of spindles ! But the course of improvement has not yet stopped ; 
 mules are now constructed which do not require the aid of a spinner, the 
 mechanism being so contrived as to roll the spindle carriage out and in at the 
 proper speed, without a hand touching it; and the only manual labour employed
 
 COTTON SPINNING. 409 
 
 in these machines, (which are called self-acting mules,} is that of the children 
 who join the broken threads. The first machine of this nature was invented 
 by the ingenious Mr. W. Strutt, of Derby, son of Mr. Jedediah Strutt, the 
 partner of Arkwright. This appears to have been in the year 1790 ; and two 
 years afterwards, Mr. Kelly, of Lanark mills, invented another self-acting 
 mule, which is thus described by him in a letter to Mr. Kennedy, which we 
 annex, as it furnishes a very interesting detail of the progress of improvement. 
 ' I first applied water power to the common mules in the year 1790 ; that is, 
 we drove the mules by water, but put them up (that is, the carriage or spindle 
 frame) in the common way, by applying the hand to the fly-wheel, and by placing 
 the wheels (or mules) right and left ; the spinner was thereby enabled to spin 
 
 two mules in place of one The mules at that time were generally 
 
 driven with ropes, made with cotton mill-waste, from a lying shaft in the middle 
 of the room, and over gallows-pulleys above the fly-wheels, on each side of the 
 room. That mode of driving was succeeded by belts, which were in every 
 respect much better, and better adapted to self-acting mules, &c. From the 
 above date I constantly had in view the self-acting mule, and trying to bring it 
 into use ; and having got it to do very well for coarse numbers, I took out the 
 patent in the summer of 1792. The object then was to spin with young 
 people, like the water twist. For that purpose it was necessary that the carriage 
 should be put up without the necessity of applying the hand to the fly-wheel. 
 At first we used them completely self-acting in all the motions, the fly continuing 
 to revolve, and after receiving the full quantity of twist, the spindles stood, 
 the guide or faller was turned down on the inside of the spindles, and the points 
 were cleared of the thread at the same instant, by the rising of a guide, or 
 inside faller (if it might be so called). When the outside guide wire, or faller, 
 was moved round, or turned down to a certain point on the inside of the spindles, 
 it then disengaged, or rather allowed a pulley, driven from the back of the 
 belt-pulley, to come into geer, or action, and which gave motion to the spindles, 
 and took in the carriages at the same time (similar to the way you assist the 
 large mules in putting up). But in the above self-acting mule, which performed 
 every motion, after the spindles were stopped it required about three turns of 
 the fly-wheel to move round the faller, and put in action the above-mentioned 
 pulley that took in the carriage, which was a great loss of time. We therefore 
 set aside that part of the apparatus or machinery, and allowed the mule to 
 stop in the common way, on receiving the full complement of twist ; and the 
 instant it stopped, the boy or girl, without putting their hand to the fly-wheel, 
 just turned the guide or faller with the hand, which instantly set in motion the 
 spindles, and took in the carnage, the cop being shaped by an inclined plane, 
 or other contrivance It may naturally be asked, Why were not the self- 
 acting mules continued in use? At first, you know, the mules were about 144 
 spindles in size, and when power was applied, the spinner worked two of such ; 
 bat the size of mules rapidly increased to 300 spindles and upwards, and two 
 such wheels being considered a sufficient task for a man to manage, the idea of 
 saving, by spinning with boys and girls, was thus superseded." So numerous 
 and diversified have been the successive improvements in this important branch 
 of art, that a very large volume might readily be filled with merely a selection 
 of the more ingenious ; but our prescribed limits compel us to confine our 
 present notice to the most successful, and we believe the most perfect mechanism 
 for spinning hitherto brought into use, which is the self-acting mule, invented by 
 Mr. Roberts, of the firm of Sharp and Roberts, of Manchester. The following 
 description of the invention, extracted from the patentee's specification, we 
 copy from the London Journal of Arts and Sciences, Vol. VIII. Second Series. 
 
 " The nature of my said invention consists of an improvement or improve- 
 ments in the mechanism employed to render self-acting the 'machines com- 
 monly known by the names of mule, billy, jenny, jack-frame, stretching frame, 
 and all other machines of that class, whether used to rove, slub, or spin cotton, 
 or other fibrous substances, the particular object of which improvement or 
 improvements is to effect in a more complete manner than has hitherto been 
 done by self-acting machines of the kinds above mentioned, the regular winding
 
 410 
 
 COTTON SPINNING. 
 
 Fig. 1. 
 
 on of the yarn, or roving, upon the spindles, by regulating their rotatory 
 motions according to the gradually varying form and increasing diameter of 
 the cop. In Figs. 1 and 2, a a is a mule carriage in two parts, one on each 
 side of the headstock, the parts being firmly united by b b, a connecting bar of 
 iron, and c c, an iron frame ; to this is bolted in front a frame of iron d, which, 
 at its upper part, is supported by e, a spur piece, bolted to the bar b and to the 
 frame d. On studs in the spur piece are //two ratchet tension barrels; to one 
 of these is fastened g a cord, 
 which, after passing over a 
 notch in the spur piece e, is 
 wound round and fastened to 
 h a drum or barrel ; this has 
 also attached to and coiled 
 round it i another cord, which 
 after passing over j a guide 
 pulley, and a notch in the 
 spur piece, is attached ,to the 
 other ratchet barrel. A shaft 
 k, on which is keyed the drum 
 h, has a pinion I working into 
 m the toothed quadrant, which 
 receives an alternating motion 
 on its centre, through an arc 
 of about 90, whilst the car- 
 riage runs out and in, that ia 
 to say, at every stretch. In a 
 groove in the inner arm of the 
 quadrant is n a sliding nut 
 moved by o a double threaded leading screw, on the lower end of which is 
 keyed p a mitre wheel, gearing with q another mitre wheel, the central stud of 
 which is opposite to the centre of the quadrant. Attached to the back of mitre 
 wheel q is r, a pulley, which is turned at intervals by * an endless strap passing 
 round it, and t a sliding pulley. A weighted lever u, called the governor lever, 
 is movable on a stud in the back part of the carriage frame, and forms the 
 upper jaw of a pair of pincers, the lower jaw being v a stud in the carriage 
 end. The lever w, when not intended to press upon the stud v, is carried by 
 an adjustable nut on the lower end of w, a rod connected with the arm of the 
 counter faller, and having free play through a hole in a side projection from the 
 arm of the lever. When, in winding on, the tension of the yarn brings the 
 faller wires to nearly the same level, the dropping of the arm of the counter 
 faller allows the lever u to descend till it pinches the endless strap s against the 
 stud, and drags it along as the carriage runs in, until the rise of the counter 
 faller arm again raises the lever and liberates the strap. The spindles are 
 banded in the ordinary way, and the drums are driven by a band, which, after 
 taking both the grooves in x, the driving pulley, is spliced, instead of passing 
 from the carriage to the twist pulley, as in common mules. The pulley x is 
 keyed on y, an inclined shaft, the upper end of which turns in a swivel collar, 
 and the lower end or foot in an arm of a bell crank. During the process of 
 twisting and backing off, the shaft y receives motion through 1, a mitre wheel, 
 which is keyed near its lower extremity, and is driven by 2, another mitre wheel 
 fixed on 3, a shaft, on which is also keyed 4, a double grooved driving pulley, 
 receiving motion by an endless band from 5, the twist pulley above. This 
 pulley band passes under a carrier pulley, and over a double grooved carrier 
 pulley, under the driving pulley 4, again over pulley 7, and under pulley 4, 
 round 8, a sliding carrier pulley, under 9, a carrier pulley, and thence to the 
 twist pulley. The mitre wheel 1, comes occasionally into gear with 10, another 
 mitre wheel, keyed on 11, a shaft, upon which is also keyed 12, a spur wheel, 
 which gears into 13, another spur wheel, firmly connected to 14, a drum or 
 barrel, which is called the winding-on barrel. The diameters of wheels 12 and 
 13 should be made to give, as nearly as possible, the proper amount of lotation
 
 COTTON SPINNING. 
 
 to the spindles, according to their diameters and those of the warves, the final 
 adjustment being made in the diameter of the barrel 14, the whole being 
 adapted to give so much motion to the spindles as will cause them to wind on 
 the whole stretch at the first run in. There is a cord 15, one end of which is 
 
 Fig. 2. 
 
 tied to the sliding nut n in the arm of the quadrant m, and the other made fast to 
 the barrel 14, after having made several coils round it; and 16 is an opposing
 
 412 
 
 COTTON SPINNING. 
 
 cord, also coiled round and fastened to the barrel 14, and after passing under 
 17, a carrier pulley, and over 18, another carrier pulley, it sustains 19, a coun- 
 terpoise, which causes the barrel 14 to take up the cord 15 as the carriage 
 recedes from the rollers. A lever 20, inclined downwards at both ends, is 
 mounted at its middle upon 21, a tumbler shaft, carrying 22, a fixed vertical 
 arm, which is connecte- 1 by 23, a link with the side arm of the bell crank ; 24 is 
 a stopping bar, movable on a stud in the vertical arm of the tumbler shaft, its 
 lower end passing through and abutting by a shoulder against the upper side of i 
 mortise hole in 25, a stopping piece, which is bolted to the frame c; the stopping 
 bar is held against the upper side of the slot by 26, a spiral spring ; 27 is a 
 latch on a stud in a projection from the frame e, which is pressed by 28, a spring 
 in the direction of a catch on one side of the lever 20 ; 29 is a radial weight, 
 movable on a stud in the framing, and carrying on a stud near its centre, 30 a 
 friction roller, under which the inner inclined arm of the lever 20 passes, and 
 raises the weight a little just before the carriage completes its run inwards; 31 
 a stud in the framing, which, by stopping the latch 27 in its motion inwards, 
 disengages the lever 20 at the instant the carriage has completed its run, which 
 allows the weight 29 to depress the inner arm, and BO to throw into gear the 
 mitre wheels 1 and 2, preparatory to the recommencement of twisting ; 32 is 
 another radial weight, similar to the weight 29, having a friction roller, under 
 which the outer arm of lever 20 comes to raise it, as the carriage reaches its 
 outward limit. When the process of backing off is completed, the mechanism 
 for putting up, or running the carriage in, is put into gear, and simultaneously 
 with it ; and by the same, or any other convenient means, the stopping bar 24 
 is depressed, and the weight 32 depressing the lever 20, shifts the mitre wheel 
 1 from the wheel 2 into gear with the wheel 10. The diagram, Fig. 3, is 
 intended to show the arrange- 
 ment of the connecting wheels, /%77>^r~7? : %t-^ *'& 3 - 
 the winding on barrel, and the 
 crooked lever, when the spin- 
 dles are driven by bands from 
 a roller, instead of drums, 
 which, as far as the present 
 improvement or improvements 
 in the mule, billy, jenny, jack 
 frame, or stretching frame, are 
 concerned, is almost the only 
 difference in the several ma- 
 chines enumerated; they all 
 being machines of the same 
 
 class, that is, in which is performed at intervals the winding on of the stretches 
 of yarn or rovings, though used for different purposes, and distinguished by 
 different names. A spur wheel a is keyed on the coupling shaft which connects 
 the spindle band rollers on each side of the headstock ; b is a radial arm cen- 
 tred on the same coupling shaft, and connected by c, a link, with d, the crooked 
 lever, which is acted upon by the radial weights and catches, as described 
 before ; e a double grooved pulley, keyed on the same shaft with /, a spur 
 wheel ; g a double grooved carrier pulley, round which and the pulley e the 
 twist pulley band is passed twice, as before explained ; h the winding on drum, 
 keyed on the same shaft as i, a spur wheel ; j a spur wheel carried by the 
 radial arm b, and gearing into wheel / whilst the twist is being given, and into 
 wheel i during the winding on. In the adaptation of the present improve- 
 ments to the mule, billy, jenny, jack frame, or stretching frame, according to 
 the diameter of the cop to be formed, or the length of stretch made in the several 
 machines, it may be requisite to vary the length of the grooved arm of the 
 quadrant. Whilst the carriage is running in, it turns by the band g, Fiy 2, the 
 drum h, its shaft Jc, and the pinion I, which works into the quadrant m. When 
 the quadrant begins to move, its grooved arm stands about 12 beyond the ver- 
 tical position from the rollers, and during its action it turns on its centre 
 inwards, through an arc of about 90. At the commencement of a set of cons,
 
 COTTON SPINNING. -513 
 
 the stud in the nut n, to which the cord 15 is attached, is set opposite, or nearly 
 to, to the centre of the quadrant, in which position it suffers no change of place 
 by the motion of the quadrant. As the carriage recedes from the point of 
 attachment of cord 15, it causes the rotation of the winding on drum 14, round 
 which the cord is coiled, and the drum through the train of wheels 13, 12, 10, 
 and 1, that of the pulley x, which, by the spindle drums, gives motion to the 
 spindles (see Fig, 1.) The rotation of the spindles during the first run-in of 
 the carriage, just suffices to wind on the stretch of yarn upon the bare spindles. 
 As the diameter of the cop increases by each succeeding layer, fewer revolutions 
 will be requisite to effect the winding on of the constant length ; .and, therefore, 
 the whole quantity of motion imparted to the spindles during a run-in must 
 undergo progressive diminution so long as the diameter of the cop is increasing, 
 which goes on until the bottom is formed. This decrease of motion in the 
 spindles is obtained by lessening the quantity of cord to be uncoiled from the 
 winding-on barrel ; an effect which results from the advance of the nut n along 
 the arm of the quadrant, the amount of the effect being exactly commensurate 
 with this advance, as is apparent when the grooved arm of the quadrant, at the 
 end of the run-in, nearly coincides with the line of traction of the cord 15. 
 The motion which slides the nut along the quadrant arm is produced in this 
 way. During the process of backing off, the spiral coils of yarn are unwound 
 from the ends of the spindles, and the faller is depressed when the counter 
 faller by its weight rises, and takes up the uncoiled or slack yarn, and thus the 
 faller wires keep up the tension as the yarn is uncoiling. Whilst the carriage 
 is running in, the spindles, in winding on the stretch of yarn, take up by 
 degrees the coil yarn also ; and as this is effected, the faller wires are brought 
 to nearly the same level. At the first run-in, this approach of the faller wires 
 takes place only as the carriage comes up to the rollers. The power of winding 
 on increasing as the diameter of the cop enlarges in the subsequent stretches, 
 the coil yarn gets taken up before the carriage has run home ; and when this 
 occurs, the descent of the counter faller allows the governor lever u to fall, and 
 to pinch the endless strap s against the studu. With the motion of the carriage 
 the strap is dragged along, and turns the leading screw o, which slides the nut n 
 towards the circumference of the quadrant. The strap continues to be dragged 
 until the retardation of the taking up, from the diminished velocity of the spin- 
 dles thus produced, pennits the counter faller again to rise and relieve the trap 
 from the pinch of the lever. In this way the nut n is made to advance upon 
 the quadrant arm, in proportion as the expanding diameter of the cop accele- 
 rates the action of winding on, and a correspondent abatement in the whole 
 number of revolutions of the spindles is the result. As soon as the cop has 
 attained its full diameter, that is, when the bottom is formed, the winding on 
 power then remaining uniform, the governor lever is no longer made to act 
 
 upon the strap, and, consequently, the nut n travels no farther from the centre 
 of the quadrant during the completion of the cop. Besides the adjustment of 
 the whole amount of winding on motion, each stretch is adjusted to the growing 
 
 diameter of the cop, which is effected by causing the point of attachment of 
 the drag cord 15 to advance progressively upon the rim of the barrel 14. The 
 grooved arm of the quadrant, by carrying the point of attachment of the cord 15, 
 after the first stretch through an arc of about 90 at each run-in, causes the 
 cord to be uncoiled from the barrel 14, by a ratio increasing as the carriage 
 recedes from the quadrant ; and this variable rotation of the barrel is increased 
 by the successive shifts of the nut n from the centre of the quadrant, thus 
 adapting the rotation of the spindles to the winding-on powers of the cop, 
 through its various diameters from the base to the summit of the cone. Having 
 now described my improved mechanism for adapting the rotation of the spindles 
 to the regular taking up of the yarn or roving, as the form and diameter of the 
 cop changes throughout the operation of winding on, I do hereby declare, that 
 my invention consists in the method or means to be employed for that purpose 
 hereinbefore described. The mechanism thus employed by me affects the 
 rotation of the spindle in two ways ; first, rotatory motion is given to a drum 
 or barrel, which turns the spindles whilst the carriage is running in by uncoiling 
 3 G
 
 414 CRAMP. 
 
 from it a portion of a cord, strap, or chain, attached to the drum, and having 
 its other extremity fastened at some point in a radial arm which describes an 
 arc, whilst the winding-on drum is receding from the point of attachment of 
 the cord in a right line. This compound motion adjusts the rotation of the 
 spindles to the varying power of taking up by the conical cop as the yarn or 
 roving is being coiled on its different diameters, during the winding on of each 
 stretch. Secondly, during the progress of the formation of a cop, the situation 
 of the point of attachment of the uncoiled end of the cord, strap, or chain, on 
 the radial arm, is changed progressively, as the increasing bulk of the cop 
 demands fewer revolutions of the spindles to take up the stretch, and, conse- 
 quently, there is a shorter length of the cord to be uncoiled from the barrel." 
 We refer the reader to the articles SPINNING and WEAVING for further infor- 
 mation on this important branch of art, as cotton is not the only fibrous matter 
 to which such mechanism is applicable. It is a remarkable circumstance in the 
 cotton manufacture, and highly honourable to British skill, that all its numerous 
 and varied operations are performed by machinery. Mr. Baines, in his valuable 
 History of the Cotton Manufacture, justly observes, " It is by iron fingers, teeth, 
 and wheels, moving with exhaustless energy and devouring speed, that the 
 cotton is opened, cleaned, spread, carded, drawn, roved, spun, wound, warped, 
 dressed, and woven. The various machines are proportioned to each other in 
 regard to their capability of work x and they are so placed in the mill as to allow 
 the material to be carried from stage to stage with the least possible loss of 
 time. All are moving at once, the operations chasing each other ; and all 
 derive their motion from the mighty engine, which, firmly seated in the lower 
 part of the building, and constantly fed with water and fuel, toils through the 
 day with the strength of perhaps a hundred horses. Men, in the meanwhile, 
 have merely to attend on this wonderful series of mechanism, to supply it with 
 work, to oil its joints, and to check its slight and infrequent irregularities; each 
 workman performing, or rather superintending, as much work as could have 
 been done by two or three hundred men sixty years ago. At the approach of 
 darkness, the building is illuminated by jets of flame, whose brilliance mimics 
 the light of day, the produce of an invisible vapour generated on the spot. 
 When it is remembered that these inventions have been made within the last 
 seventy years, it must be acknowledged that the cotton mill presents the most 
 striking example of the dominion obtained by human science over the powers 
 of nature, of which modern times can boast." 
 
 COULTER. A stout iron knife or blade fixed to the beam of ploughs, which 
 serves to cut out the furrows. 
 
 COUNTERBALANCE. A weight applied to balance the vibrating parts of 
 machinery upon their axes, so as to cause them to turn freely, and to require 
 little power to put them in motion ; also a weight by which a lever acted upon 
 by an intermitting force is returned to its position, as in the case of the beam 
 of a single acting steam engine. 
 
 COUPLING BOX A mode of permanently connecting two shafts : they 
 are variously constructed, the most common being simply a tube embracing the 
 end of each shaft, with a pin or bolt passed through each. 
 
 CRAB. A kind of small capstan, consisting of an upright shaft, having 
 several holes at the top, through which long bars or levers are thrust. The 
 name of crab is likewise ^iven to a simple portable crane, on the wheel-and- 
 axle principle, and chiefly used for raising building materials to the tops of 
 houses, &c. There is a machine, likewise called a crab, that is used in launching 
 ships, or heaving them off or on to their ways or slips. 
 
 CRADLE is a name given to a supporting frame of timbers, which is placed 
 under the bottom of a ship, in order to conduct her steadily into the water 
 when she is to be launched, at which time it supports her weight while she 
 slides down the inclined plane or slip, which is for this purpose smeared with 
 soap. The bedsteads for wounded seamen are also called cradles ; these, as 
 well as those used for rocking children, require no particular description. 
 
 CRAMP. A portable kind of iron press, chiefly designed and employed for 
 closely compressing the joints of frame-work. See FLOORING CRAMP.
 
 CRANE. 
 
 415 
 
 CRANE. A machine employed at wharfs, warehouses, &c. for raising and 
 lowering goods ; it consists of a long projecting arm, called the jib, having a 
 pulley at the outer end, over which passes the rope or chain by which the good's 
 
 are raised, the other end of the rope being wound round a barrel either attached 
 to the foot of the jib, or placed at any convenient distance from it. Various 
 modes have been resorted to for turning the chain barrel ; on piers and jetties
 
 4Ifi CRANE. 
 
 it is frequently placed erect, and worked like a capstan : another method which 
 was formerly very common, but is now little used, was to place it horizontally, 
 and connect it with the axis of a large hollow drum, within which were placed 
 a number of men, who, by stepping upon battens nailed upon the interior 
 circumference parallel to the axis, caused the drum to revolve. But the most 
 effective and best mode of employing the strength of men in working cranes 
 (in situations which will admit of its application), is that invented and patented 
 by Mr. Hardy : as in the preceding plan, the chain barrel is connected with a 
 large drum fixed upon a horizontal axis, but the steps upon which the labourers 
 tread are ranged upon the outside (instead of the inside) of the drum, radiating 
 like the floats of an undershot water-wheel, and the labourers continually step 
 upon that arm or step which is horizontal, so as always to act upon the longest 
 lever. One or more of these cranes were erected at the East India Warehouses, 
 and the principle has been since rendered familiar to one very numerous 
 portion of the public by the invention ascribed to Mr. Cubitt, of IpswicH 
 called the treadmill. 
 
 The preceding figure represents a side elevation of Mr. L. Wright's paten! 
 crane, erected at the West India Docks, and which was the subject of much 
 acrimonious controversy amongst some of the scientific periodicals of the time. 
 a is the principal wheel, fixed to and revolving with the chain barrel b on the 
 axis c ; the periphery of the wheel c is made perfectly flat on both sides, for 
 the reception of the numerous small wheels d, alternately placed on the opposite 
 sides of the ring, with their axes fixed into it; these, which may be called 
 friction wheels, are solid, about an inch thick, and five inches in diameter 
 they are turned smooth, and made bright in all parts; e e are two (of four) 
 levers, worked by a four-throw crank ff turned by the winches gg ; the levers 
 pass between guides at o, and slide over rollers at p, which form the fulcrum of 
 the levers ; and by the revolutions of the cranks the levers are successively 
 projected against the under sides of the small wheels d, from whence they are, 
 by the continued revolution of the cranks, again withdrawn, and again projected 
 under the next little wheel below the former, each wheel being raised by the 
 angular motion of the lever over which it rolls. It should be observed that only 
 one side or half of the machine is seen, the other side being a duplicate of it, 
 having two similar levers, large wheel, and smaller wheels, &c. The machine 
 (as delineated) is in gear; to put it out of gear a locking bar t is lifted, and 
 thrown into the position shown by the dotted lines ; then the framing r which 
 carries the crank, inclined planes, and fly-wheel, and turns upon the centre *, 
 is thrown back, by which the axis of the crank moves in the arc of a circle 
 (shown by dots) to the position n. What mechanical advantage the inventor 
 expected to obtain by this singular construction, it is hard to say ; the machine 
 is cumbersome and unsightly, has a complication of parts, in which the friction 
 far exceeds that of a well-made crane of the common construction, to which it 
 is also decidedly inferior in the circumstance of affording no means of altering 
 the power or velocity according to the weight to be raised. The method adopted 
 by the inventor for putting the machine in and out of gear is also very defective ; 
 but if the crane offered any advantages in other respects, this latter defect 
 might be obviated. 
 
 In Mr. Revis's patent crane, which we are about to describe, the alternating 
 motion of a single lever is employed to produce rotatory motion by means of a well- 
 known mechanical arrangement, instead of producing such motion by turning a 
 winch. The engraving on the succeeding page represents an elevation of this 
 machine, cis the alternating lever (shown as broken into two parts for want of 
 space), and having a counterbalance at x ; it is on the opposite side of the machine 
 to that represented, and its fulcrum being the axis of the toothed wheel b, which 
 gears into another toothed wheel c, motion is given to both wheels in opposite 
 directions. These two wheels are shown merely by two dotted circles, to avoid 
 confusion in the drawing. On the axis of the wheels b and c are placed tne 
 wheels d and e, which are not fixed to the axles, but turn loosely upon 
 them ; each of these wheels cany four palls or clicks, which fall into the 
 notches of two ratchet wheels /and g that are fixed to the axis on which d and
 
 CRANE. 
 
 417 
 
 e turn loosely. The operation of the lever, therefore, which causes the two first 
 mentioned wheels b and c to revolve in opposite directions, produces precisely 
 the same effect upon the ratchet wheels / g. It will now be observed that 
 the ratchet teeth and palls of both wheels incline, in respect to each other, in 
 the same direction ; and as the ratchets are turned round in opposite directions, 
 the palls in one wheel slip over the ratchet teeth, while in the other wheel the 
 palls catch into the ratchet ; the latter is thereby locked to the toothed wheel, 
 which now operates upon the toothed wheel / on the working barrel, upon which 
 the rope or chain r is wound. During this process, the other wheel and ratchet 
 (which we will suppose to be df} has no effect, from their not being connected; 
 
 but upon reversing the motion of the lever, these become fastened together* 
 while the former are simultaneously loosened ; and as the wheel d revolves in 
 an opposite direction to e, the wheel / is turned round in the same direction as 
 previously, and the rope or chain on the barrel proceeds in an uniform course. 
 Having thus explained the manner in which the motion of the lever a is com- 
 municated to the other wheels b c, and thence to the rest of the machine, 
 it is obvious that the putting of the wheel b out of gear with the wheel c, will 
 stop the forward action of the crane ; this is effected by means of the lever h, 
 which turns horizontally upon a fulcrum pin at /, and slides the axis in its 
 bearings, so that the wheels w and c are placed out of contact with each other.
 
 418 
 
 CRANE. 
 
 This is done when it is intended to lower the rope or chain ; but if a weight 
 or goods be appended to it, the friction band m m is made to press against the 
 periphery of the fly-wheel k by raising the lever , which, having its fulcrum at 
 o, draws the friction band tightly over the fly-wheel, and the goods are thus 
 lowered with safety and expedition. But, for general purposes, the wheel and 
 pinion turned by a winch is superior to all other modes of working cranes, and 
 more particularly is it superior to any arrangement of reciprocating levers, as it 
 produces a smooth continuous circular motion, avoids the jerks and concussions 
 attending the latter, and saves a vast deal of friction, complexity, and 
 expense ; accordingly, we find the wheel and pinion now generally adopted 
 almost to the exclusion of every other method. We have already stated that 
 the barrel is sometimes attached to the jib so as to turn with it. The annexed 
 engraving represents an excellent construction of a crane of this description, 
 several of which are erected upon the wharfs of the Regent's Canal, a is an 
 upright pillar of cast iron firmly fixed in a foundation of masonry ; b a pin in 
 
 the head of a, which supports the jib c, and forms the pivot round which it 
 turns ; d d two struts, supporting the extremities of the jib, and the lower 
 ends resting on a collar e encircling the lower part of the pillar, which collar is 
 suspended from the jib by the iron rods//; g is one of the side frames sup- 
 porting the barrel h; k a toothed wheel on the axis of the barrel, and turned 
 by a pinion, on the axis of which is fixed the winch I. The crane is turned 
 round upon its pivot by means of the winch m, which, by means of an inter- 
 mediate wheel and pinion, turns the pinion , working in the wheel o, fixed to 
 the base of the pillar a. 
 
 The following figure represents a modification of the wheel and axle, known 
 by the name of the " Chinese Crane," which, for simplicity of construction 
 and immense power, far surpasses any other machine which is applied to pur- 
 poses for which this is adapted; and however its modest and unassuming appear- 
 ance may prevent its admission into the elegant companies of wheels and 
 pinions, which we see associated together in this age of mechanical combination, 
 there can be little doubt that it will eventually work its way into notice by its 
 own merits, to the displacement of some of those complicated arrangements of 
 wood, iron, and brass, which, in some cases, seem to be erected for no other 
 purpose than for employing a horse to do the work of a man. The construction
 
 CRANK. 
 
 419 
 
 of this machine will be readily under- 
 stood by reference to the figure, a b 
 is a windlass, which is worked by a 
 winch or handle c d. It will be seen that 
 the windlass a b partakes of two diame- 
 ters, that part from a to e being larger 
 than the remaining part e b ; the cord g 
 is wound round the part a e of the wind- 
 lass, and is passed under the movable 
 pulley h i, and carried over the part 
 e b of the windlass, on the opposite side 
 to that from which it descended at a e ; 
 the weight to be raised is suspended from 
 the pulley h i. Now if a power be applied 
 at d, and the windlass be caused to make 
 one revolution, a portion of the cord g 
 equal to the circumference of the part 
 a e of the windlass, will have been wound on to the windlass ; but the part e b 
 of the windlass has also made one revolution, consequently a portion of the 
 cord, equal to the circumference of e b, has descended, so that after one revo- 
 lution the cord will have been shortened a quantity equal to the difference 
 between the larger and smaller barrel of the windlass: but as this difference 
 has been divided between the two parts of the cord g and k, it follows that the 
 weight has been raised through a space equal to only half the difference of the 
 circumferences a e and e b. But as circles are to each other as their radii, the 
 following simple rule may be deduced for calculating the power of these 
 machines ; as c d, the radius of the winch, is to half the difference of the radii 
 of the parts of the windlass a e and e b, so is the weight w to the power which 
 is necessary to produce an equilibrium. For example, put c rf=18, the radius 
 a e=6, and the radius e 6=3; and suspend a weight of 108 Ibs. from h i; we 
 then have 6 3-j-2=l J, and as 18 : 1J : : 108 : 9 ; consequently a power of 9 
 applied at the point d would be equivalent to a weight of 108 Ibs. acting upon 
 the pulley h i. This subject may perhaps be better understood by referring to 
 the annexed diagram, where a e represents the 
 radius of the larger part of the windlass, and b 
 the smaller radius, e d being the radius of the 
 winch ; and we may suppose d a to represent a 
 lever, whose fulcrum is e ; and as each of the 
 ropes g k bear equal parts of the weight of 1 08 Ibs. 
 we represent the whole weight by two distinct 
 weights g and k acting upon the points b and a 
 of the lever d a ; and if we retain the propor- 
 tions de\8, ae=16, and b e=3, we have a 
 weight k on one side of the fulcrum, at the dis- 
 tance of b, whose quantity is 54 ; and we have a 
 
 power of 54 acting on the opposite side of the fulcrum, at the distance of 3. 
 Now it will easily be seen from the principles of the lever, that g will sustain a 
 quantity equal to J k, consequently there will remain a weight of 27 acting 
 at a, to be kept in equilibria by a force applied at d; but ed is 3 times e a, 
 therefore a power equal to 9 applied at d would balance a weight of 27 acting 
 at a; which is precisely the same result as was obtained by the rule before laid 
 down. 
 
 CRANK. A short arm or lever fixed to a shaft in any machine, and set in 
 motion by a connecting rod proceeding from some other part of the machine, 
 which has a reciprocating motion to and fro. To obtain a continuous rotatory 
 motion of the crank and shaft it is necessary to fix upon the shaft a fly-wheel 
 of considerably larger radius than the crank, for when the connecting rod lies 
 in the same direction or right line as the crank, and no longer forms any angle 
 with it, it can have no tendency to move the crank to either side ; but the heavy 
 fly-wheel, which, from its greater radius, has travelled much faster than the
 
 420 CRANK. 
 
 crank, has acquired n considerable momentum, which urges round the crank 
 when the connecting rod has ceased to impel it, or carries the crank past the 
 dead points, as it is called. Although this means of obtaining a rotatory 
 motion had long been in practice in various machines, as in the turning-lathe, 
 and knife-grinder's wheel, yet it is a singular fact that a considerable time 
 elapsed after the invention of the steam engine ere the same simple and effective 
 method was employed to obtain a rotatory movement from the reciprocating 
 action of the engine beam, whilst several schemes, exhibiting much contrivance 
 and ingenuity, but which were inadequate to the object in view, were from time 
 to time proposed. By the addition of the crank and fly-wheel to the steam 
 engine, the latter, which before was chiefly used for pumping water, has become 
 generally applicable as a prime mover of machinery, and its utility has, in con- 
 sequence, been augmented a thousand fold. But'the utility of the crank and 
 fly-wheel, as applicable to a steam engine, consists not merely in converting 
 rectilinear into circular motion, but also in gradually destroying the momentum 
 of the piston, and bringing it gently to a state of rest at the end of each stroke. 
 It is a law of nature that all bodies have a natural tendency to preserve their 
 state of motion or of rest, until opposed by some external force. This property 
 of matter occasions a great loss of power in the steam engine, where a massive 
 beam, with all its appendages, have to be reversed at each stroke of the engine; 
 and were it suddenly stopped and reversed when at its greatest velocity, the 
 shock would be so great as speedily to destroy the machinery. The loss of 
 power employed in overcoming the vis inertia of the beam cannot be avoided, 
 but the shock at the reversal of the motion is prevented by means of the crank, 
 in a manner which will be best explained by the diagram in the margin. Let 
 a b represent the crank of a steam engine, equal to half 
 the length of the stroke, or half df, and letdcacf re- 
 present the semicircle through which the crank travels 
 whilst the piston performs a stroke, or moves through 
 the space df. Now, when the crank is in its present 
 position, the piston is at its greatest speed, and travels 
 with nearly the same velocity as the crank, moving 
 through the space bg whilst the crank passes from a to c. 
 But when the crank moves through the next portion of 
 its revolution c d, equal to the former portion a c, the 
 piston only moves through a space equal to g d in the 
 same time as it before moved through the space b g, 
 which is nearly double g d : hence it is seen that the 
 crank, by diminishing the speed, is admirably adapted for 
 preventing the shock which would be experienced from 
 too sudden a reversal of the motion. A want of a 
 thorough comprehension of the mode in which the fly-wheel and crank operate, 
 has been the origin of many attempts to supersede them. Of these we shall 
 only notice the following, which is the invention of Mr. J. Apsey. 
 
 At Fig. 1, page 421, is an elevation of the apparatus ; a a is a strong elliptical 
 frame of cast iron, having fixed on each side a toothed rack b c. This frame is sup- 
 posed to be immediately connected to the piston rod of a steam engine or other 
 rectilineal moving force, the motion of which causes the toothed wheels d and 
 e (the wheel c is behind d, as is shown in the edge view of them at Fig. 2,) to 
 revolve on the axis i, which axis communicates its motion and force to whatever 
 machinery may be connected to it. / ' g are two guide bars, and hj are two 
 guide rings or annular plates, in front of the wheels d and e, which serve to 
 keep their respective parts in their proper places. It will be observed that the 
 frame a a is represented at the lowest point of its descent during such descent 
 it turns round the wheel d by means of the rack g, and at the same time causes 
 a revolution of the axis ; by the ascent of the frame the wheel d revolves the 
 contrary way, but it then runs freely upon the axis, so as to have no influence 
 upon it ; during the same time the opposite wheel e becomes locked to the axis, 
 and by means of the rack causes the axis to continue revolving in the direction 
 given to it by the previous operation of the wheel d, as; will be best understood
 
 CRANK. 
 
 421 
 
 by an explanation of Fig, 2, which exhibits the toothed wheels and axis distinct 
 from the frame and side racks. To each of the wheels d and e are fixed the 
 guide rings hj, and a clutch box k I, which turn with the wheels on a. smooth 
 part of the axis, as shown at i in the separate Fig. 3. These wheels are 
 alternately connected to the axis, to give it motion, by means of the clutches 
 op, which have merely a sliding motion along the axis, and are constantly 
 pressed against the boxes le 4 by means of helical springs g r wound upon the 
 axis, and confined in a case, as represented in the figure. The clutches op have 
 grooves made in them, as shown by the end views of them given in the separate 
 
 Fig. I. 
 
 Fig. 2. 
 
 Fig. 3. 
 
 figure o p, through which the stuts s t, Fig. 3, slide, and secure them to turn 
 round with the axis. As the action of the apparatus may not be quite clear to 
 some of our readers by the foregoing, we will just repeat that the raising of the 
 elliptical frame containing the side racks, causes the wheel e to operate upon 
 the axis by its becoming locked to it by the agency of the clutch p ; but on the 
 motion of the frame being reversed, by the reciprocating action of the piston rod, 
 or other rectilineal moving force, the wheel e is released from the axis, and the 
 other wheel d becomes locked to it by the agency of the clutch o, which carries 
 the axis round in the direction previously given to it, and by the repetition of the 
 alternations of the frame, the axis is caused to revolve continually in the same 
 direction. Motion is often required to be communicated to machinery at a 
 distance from the first mover, and this is usually effected by a metallic shaft, 
 which, if the distance between the machinery and the first mover be great, 
 must be made of considerable thickness, to prevent its being twisted to pieces 
 by the power applied, or else by chains, straps, or ropes, which, to prevent their 
 slipping on the drums or pulleys over which they pass, causes considerable 
 impediment to the motion by friction. These are inconveniences which cannot 
 3 11
 
 422 
 
 CRAYON. 
 
 in all cases be avoided ; but under some circumstances the following method of 
 transmitting motion through the medium of three rods and two triple cranks, 
 connecting the machinery with the first mover, might be introduced with 
 considerable advantage. The apparatus is represented with the axes of motion 
 placed horizontally by Fig. 1, and with the axes placed vertically by Fig. 2. 
 The same letters represent similar parts in both figures. It will be perceived 
 that the motion may be in the direction shown by the arrows, or the contrary ; 
 and hence it may be reversed at pleasure. The triple crank a b c, to be 
 put in rotation by any first mover, is connected by three rods to a similar 
 
 Fig. I. 
 
 crank d b' cf of equal dimensions ; and as the cranks project from the axes at 
 equal distances, there will always be one of them in a position to produce a 
 pulling action, and hence there will be no necessity for having the conducting 
 rods stronger than what may be sufficient to sustain, by tension, the resistance 
 of the machine to be put in motion, and thus the expense of transmitting 
 motion by this method to a considerable distance will be very small. The 
 motion, too, will be perfectly uniform ; for as the leverage of the crank a, for 
 instance, diminishes by its rotation, that of the corresponding crank a will be 
 equally diminished ; so that whatever motion is produced by the first mover 
 will be faithfully transferred to the machinery. 
 
 CRAPE. A light kind of stuff, somewhat like gauze, much used in mourn- 
 ing. It is made of raw silk, jammed and twisted in the mill, and woven without 
 crossing. Crapes are either crisped or smooth; the first double, expressing 
 a closer mourning ; the latter single, used for denoting a less portion of grief. 
 The silk destined for the first is more twisted than that for the second ; it being 
 the greater or less degree of twisting, especially of the warp, which produces 
 the crisping given to it : when taken out of the loom, it is steeped in clear 
 water, and rubbed with a piece of wax for that purpose. Crapes are all dyed 
 raw. 
 
 CRAYON is a general name given to various mineral and vegetable sub- 
 stances used in designing or painting in pastil, whether they have been beaten 
 and reduced to a paste, or are used in their primitive consistence, after sawing 
 or cutting them into long narrow slips. In this last manner red crayons are 
 made from red chalk ; white, from white chalk; black, from charcoal and black 
 lead. Crayons of all other colours are compositions of earths reduced to paste. 
 The tempering of crayons is found to be an operation of great nicety, to 
 avoid their being so hard as to impart an insufficient supply of colour ; or, on
 
 CRUCIBLE. 423 
 
 the contrary, so soft as to crumble away, and to be little better than a powder 
 upon the paper. A variety of slightly glutinous fluids have been proposed to 
 give them the due degree of coherence ; but the strength and the kind of fluid 
 used requires to be varied according to the nature of the colour to be employed. 
 The English manufacturers employ a variety of substances for this purpose ; 
 among which may be mentioned ale-wort, rendered glutinous by boiling, and 
 gum tragacanth. It is obvious that the marks made upon paper by such com- 
 positions as we have mentioned, can be but slightly attached to the paper, and 
 that they are extremely liable to be injured or defaced. Various means have 
 been resorted to for fixing them in such a manner, that, without having their 
 tints injured, they may be enabled to bear rubbing. When the picture is made 
 on unsized paper, Cathery recommends the back to be brushed over with a size 
 made of half an ounce of isinglass, and two drachms of powdered alum, boiled 
 for a quarter of an hour in a quart of water, and strained. This size, used 
 milk-warm, penetrates the paper, and effectually fixes the picture. He also 
 recommends another way, which is applicable to large drawings done on sized 
 paper ; it consists in sponging with the glutinous fluid a piece of unsized or 
 blotting paper, of the same size as the picture. This wetted paper being laid flat 
 upon a table, the face of the picture is pressed upon it in every part. The 
 chalk thus becoming wet with size adheres to the original surface, and, by 
 taking care wholly to avoid the smallest sidewise motion whilst the two surfaces 
 are in contact, the colours are not in the least daubed, nor is the minute quan- 
 tity of colour transferred to the blotting paper any injury to the piece. Sebas- 
 tian Grandi, an Italian artist, communicated to the Society of Arts a process 
 for preparing crayons, which are stated to be of a quality greatly superior to 
 those commonly or previously in use, being fixed so as to prevent their being 
 rubbed off the paper when used, and are applicable alike to water or oil 
 paintings. These crayons are made of bone-ash powder, mixed with sper- 
 maceti, adding thereto the colouring matters. The proper proportion is three 
 ounces of spermaceti to one pound of the powder. The spermaceti to be first 
 dissolved in a pint of boiling water, then the white bone-ash added, and the 
 whole to be ground well together with as much of the colouring matter as may 
 be necessary for the shade of colour wanted. They are then to be rolled up in 
 their proper form, and gradually dried upon a board. 
 
 CREAM. The oily part of milk which rises to the surface of that liquid, 
 mixed with a little curd and serum. When churned, butter is obtained. Heat 
 separates the oily part, but injures its flavour. 
 
 CROWN SAW. A species of circular saw formed by cutting the teeth 
 round the edge of a cylinder. 
 
 CRUCIBLE. A pot in common use for a variety of chemical purposes. It 
 is generally made of clay, and is designed to withstand a strong heat. The 
 best crucibles for this purpose are the Hessian crucibles, composed, according to 
 Pott, of a mixture of very refractoiy clay with sand. The vessels are not 
 turned upon a potter's wheel, but the earth is kneaded into a very stiff mass, 
 and the form given by ramming it in an iron mould. A composition con- 
 sisting of two parts of Stourbridge clay, and one part of the hardest coke, well 
 ground and tempered together, has been employed with excellent results by 
 Mr. Anstey, of Somers Town. The following description of his process is an 
 extract from his account published in the Transactions of the Society of 
 Arts : 
 
 " Take two parts of fine ground raw Stourbridge clay, and one part of the 
 hardest gas coke, previously pulverized, and sifted through a sieve of one- 
 eighth of an inch mesh. Mix the ingredients together with the proper quan- 
 tity of water, and tread the mass well (if the coke is ground fine the pots are 
 very apt to crack). The pot is moulded by hand on a wooden block, as shown 
 in the engraving in the next page, in which a is the bench ; b b two uprights 
 supporting a cross-board c ; d the wooden block on which the pots are moulded, 
 supported on a spindle e which turns in a hole in the bench ; f& gauge to regulate 
 the thickness of the melting pot, as shown in the dotted lines ; g a cap of linen 
 or cotton, placed wet on the core before the clay is put on its use is to prevent
 
 424 
 
 CUPEL. 
 
 the clay from sticking partially to the core while it is taking off; the cap adheres 
 to the pot only while wet, and may be renewed without trouble or hazard (to 
 (he pot) when dry ; h a wooden bat to assist in moulding the pot ; when 
 moulded, they are carefully dried at a gentle heat. A pot dried as above, when 
 wanted for use, is first warmed by the fire-side, and is then laid in the furnace 
 with the mouth downwards (the red cokes being previously damped with cold 
 ones in order to lessen the heat) ; more coke is then thrown in till the pot is 
 
 covered, and it is then brought up gradually to a red heat. The pot is then 
 turned and fixed in a proper position in the furnace, without being allowed to 
 cool, and is then charged with cold iron, so that the metal, when melted, shall 
 have its surface a little below the mouth of the pot. The iron is melted in 
 about an hour and a half, and no flux or addition of any kind is made use of. 
 A pot will last for fourteen or even eighteen successive meltings, provided it is 
 not allowed to coot in the intervals ; but if it cools, it probably cracks. These 
 pots will bear a greater heat than others without softening, and will, conse- 
 quently, deliver the metal in a more fluid state than the best Birmingham pots 
 will." Crucibles are also sometimes made of porcelain, plumbago, iron, silver, 
 and platina. 
 
 CRYSTALLIZATION. That process of nature by which the particles of 
 bodies are arranged systematically in passing from a liquid to a solid state. The 
 phenomena of crystallization have much engaged the attention of modern 
 chemists, with a view to determine exactly the different figures assumed by 
 salts in crystallizing; but it does not yet appear that any certain rule can be 
 laid down in these cases, as these figures may be varied by the slightest circum- 
 stances, so that the same salt frequently assumes various figures, and very 
 different substances sometimes present themselves under absolutely the same 
 form. The most diligent observer of the phenomena of crystallization, and 
 who has been most successful in deducing a plausible theory from these obser- 
 vations, is M. Haiiy ; to whose work, on the Theory and Structure of Crystals, 
 we would refer the reader who is desirous of obtaining the best information on 
 the subject. 
 
 CUCURBIT. A chemical vessel commonly called a body, made of earth or 
 glass, in the shape of a gourd, and therefore called a cucurbit. It is used in 
 place of a still for distillation. 
 
 CUPEL. A shallow earthen vessel used in that part of the process of assay- 
 ing termed cupellation. It is made of the phosphate of lime, or the residue of 
 burnt bones, rammed into a mould, which gives it its figure.
 
 CYDER. 425 
 
 CUPELLATION. A process in assaying for freeing gold, silver, and pla- 
 tina, from alloys of other metals. It is performed as follows : the precious 
 metal is put together with a due proportion of lead into a cupel, and the fusion 
 is effected by exposing them to a considerable heat in a muffle or small earthen 
 oven fixed in the midst of a furnace. The lead continually vitrifies or becomes 
 converted into a glassy calx, which dissolves all the imperfect metals. This 
 fluid glass, with all its contents, soaks into the cupel, and leaves the precious 
 metal in a state of purity. During the cupellation, the scoriae running down 
 on all sides of the metallic mass produce an appearance called circulation, by 
 which the operator judges whether the process is going on well. When the 
 metal is nearly pure, certain prismatic colours flash suddenly across the surface 
 of the globule, which soon afterwards appears very brilliant and clean ; this is 
 called brightening, and shows that the operation is ended. After gold has 
 passed the cupel, it may still contain either of the other perfect metals, platina 
 and silver. The former is seldom suspected ; the latter is separated by the 
 operation called quartation and parting. 
 
 CUPOLA, in Architecture, an hemispherical vault : this term is also applied 
 to the furnaces used for melting iron. See FOUNDRY. 
 
 CURRYING is the art of preparing leather after it has been tanned, with 
 oil, tallow, and other matters calculated to give it pliability or suppleness, and 
 durability. See LEATHER. 
 
 CUTLERY is a general term applied to table knives, forks, scissors, pocket 
 knifes, razors, lancets, swords, and to a great variety of the more delicate kinds 
 of cutting instruments ; it is distinguished from edge tools by the latter applying 
 to the coarser kinds of cutting instruments employed by artificers and 
 mechanics, such as axes, adzes, chisels, gouges, gravers, &c. ; nevertheless, in 
 some of these it is necessary to the skilful operator to have the utmost pre- 
 cision of form and finish given to their cutting edges. 
 
 CYCLOGRAPH. An instalment used for describing arcs of circles in cases 
 where compasses cannot be employed. The most simple cyclograph is that 
 commonly used by artificers in describing arches for the tops of doors and 
 windows, which consists of two rods connected together at such an angle that 
 the apex may touch the highest point of the curve, whilst the sides of the rods 
 are in contact with points fixed in the extremities of the curve, and by turning 
 the instrument round, keeping the two legs in contact with the points at the 
 extremities of the curve, a tracing point in the apex will describe the required 
 arc. An improved instalment on this principle, invented by Mr. Rotch, is 
 described in the Transactions of the Society of Arts. 
 
 CYCLOID. That curve which is described by a point in the" circumference 
 of a circle, during the revolution of the circle over a plane. 
 
 CYDER. A fermented beverage prepared from the juice of apples. Large 
 quantities of this liquor are made annually in England ; that made in Here- 
 fordshire and Devonshire is generally accounted superior to any other. The 
 best practical directions on the art of preparing this liquor that have been 
 given to the public, are those of Messrs. Marshall, Crocker, and Knight, from 
 which chiefly the following account is compiled. The .process may be divided 
 into three distinct parts. 1st. Preparing the fruit. 2d. Grinding and expressing 
 the juice. And 3d. Fermenting and bottling. 
 
 1st. In preparing the fruit care must be taken both as to its peculiar quality 
 and its stage of ripeness. Mr. Marshall is of opinion that the fruit should not be 
 gathered until fully ripe, which is when they begin to fall from the trees ; but 
 as apples ripen very unequally on the same tree, he recommends that the trees 
 should first be gone over with a hook when the fruit begins to fall naturally, 
 and that they should be finally cleared with poles when all is ripened, or the 
 winter likely to set in. When the fruit has been gathered, it is usual to lay 
 them in heaps to sweat, but this appears to be only useful for such fruit as is 
 not perfectly ripe. 
 
 2d. Grinding and Pressing. The grinding is usually performed in a mill 
 nearly resembling a tanner's mill for grinding bark, and consists of a millstone 
 from 2 i to 4J feet in diameter, from 9 to 10 inches in thickness, and 1 to 2 tons'
 
 426 DAIRY. 
 
 weight, and running on its edge in a circular stone trough. The bottom of the 
 trough in which the stone runs is somewhat wider than the stone itself; the 
 inner side of the groove rises perpendicularly, but the outer side is bevelled in 
 euch a manner as to make the trough 6 or 8 inches wider at top than at 
 bottom. The runner or millstone turns upon a long shaft or axle passing 
 through its centre ; the inner end of the shaft rests upon a pivot in the centre 
 of the mill bed, and the outer end extends beyond the circular trough, and is 
 there connected with a spring bar, to which ahorse is attached. After the fruit 
 is ground it generally remains some time before it is pressed, to allow the rind 
 and seeds to communicate their virtues to the liquor : from twelve to sixteen 
 hours is sufficient for this purpose. In order to press the fruit, or pommage, as 
 it is now called, it is folded up in pieces of hair cloth, or placed between layers 
 of clean sweet straw or reed. The bed of the press, which is about 5 feet 
 square, should be made entirely of wood or stone, the practice of covering it 
 with lead being extremely pernicious. It has a channel cut a few inches within 
 its outer edges to catch the liquor as it is expressed, having under it a stone 
 trough or wooden vessel to receive it. The press is worked by levers of different 
 lengths, first a short one, then a longer one, both worked by hand, and lastly a 
 bar 8 or 9 feet long, worked by a capstan or windlass. 
 
 3d. Fermentation. The common practice is to have the liquor tunned imme- 
 diately, and to fill them quite full, but it is more proper to leave a small space to 
 be filled up afterwards. No ferment is added, as in malt liquors, but Mr. Marshall 
 thinks it would be desirable to do so, as it would more speedily determine the 
 fermentation, which at present is very precarious as to the time of its com- 
 mencement and its duration. The process of fermentation is variously conducted 
 by different cyder growers, some endeavouring to promote it in a spacious open 
 vat, whilst others endeavour to repress it by enclosing the liquor in hogsheads, 
 and excluding the air. After remaining a certain time in the fermenting 
 vessel, it is racked off from the leys and put into a fresh cask. A fresh fer- 
 mentation usually commences after racking, and if it becomes violent a fresh 
 racking is necessary to check it ; but if only a small degree of fermentation 
 takes place, termed fretting, the liquor is suffered to remain in the same cask. 
 Mr. Crocker says, when the fermentation ceases, and the liquor appears toler- 
 ably clear to the eye, the pure part should be racked off into open vessels, 
 and placed in a cool situation for a day or two, after which it may be again 
 barrelled, and placed in some moderately cool situation for the winter. 
 
 D. 
 
 DAIRY is the art of manufacturing various kinds of food from milk ; the 
 term dairy is likewise applied to the building where those operations are per- 
 formed. The great variety of business in a well-conducted dairy requiring 
 the most minute and assiduous attention, may be conceived by just stating the 
 principal heads ; namely, the proper choice, food, and management of cows ; 
 the mode of milking, according to the variation of circumstances ; the manage- 
 ment of the milk and cream preparatory to the making of butter ; the processes 
 of making butter according to the mechanism used for that purpose ; the manner 
 of making the various kinds of cheese ; the vatting, pressing, and salting the 
 same, &c. These important subjects, which scarcely fall within the plan of this 
 work, are most ably treated, in all their interesting details, in the Oxford Ency- 
 clopaedia, from which valuable publication we extract the following observations 
 on the proper position, structure, and arrangement, of a dairy and its utensils. 
 As respects the dairy-house, the author observes, " It is a matter of consider- 
 able importance that buildings of this description should be placed in a proper 
 situation, with respect to the other parts of the farm ; this will save both 
 expense and labour, as well as promote convenience. Another principal object 
 in choosing a situation for the dairy is a proper degree of temperature for 
 carrying on the business which is to be conducted in it. To accomplish this, 
 the following are the chief objects to be aimed at. The dairy buildings should
 
 DAIRY. 427 
 
 be situate sufficiently near the sheds or cow standings, that the milk may be 
 readily conveyed to them, the form being such as to combine well with the 
 nature of the other erections. The door or entrance into the room destined for 
 the milk should be made through that of the scalding room, which should have 
 the copper for heating water and other purposes, placed in a shed without it, 
 that the heat may be kept at as great a distance as possible from the milk, a cock 
 being fixed in the bottom of it for conveying the heated water through a trough 
 or pipe across the scalding room, in which another cock should be fixed for the 
 convenience of washing smaller utensils, passing the wall into the milk-leads, 
 pans, trays, or coolers, that whenever they are required to be scalded the 
 boiling water may at once pass through the whole range of them, or be de- 
 tained at pleasure in any one of them, so as to effect the business in the most 
 complete and perfect manner, being afterwards taken off by a suitable drain 
 made for the purpose. The passage of the water through the wall of the dairy 
 should be in a trough of sufficient dimensions to admit the discharging of a pail 
 full of milk into it with perfect safety, having a hair sieve so placed in it as that 
 the whole of the milk of the cows may be made to pass through it into the 
 necebsary trays or coolers in which it is to stand, as by this simple contrivance 
 the necessity of dirty men or boys entering the dairy-house is wholly prevented. 
 There should be likewise a trough, pipe, or some other similar contrivance, for 
 the purpose of conveying the waste milk, whey, &c., from the dairy-house to 
 the cisterns for containing the wash for the pigs, &c. Several plans for regu- 
 lating the temperature of the dairy have been proposed by different persons. 
 It may be accomplished in various ways, as by having double walls and roofs, 
 or by hollow walls, or by the walls having a vacuity left of eight or ten inches 
 in width between the lath and plaster. A spring or fountain rising in the 
 centre of the principal apartment, when it can be procured, will be a most 
 valuable convenience. It is obvious that the nature and number of these 
 buildings on any farm must depend on the kind of dairy business proposed to 
 be carried on, whether milk, or butter, or cheese ; and the size is always regu- 
 lated by the number of cows. The dimensions usually adopted in Glouces- 
 tershire are 20 feet by 16 for forty cows; and 40 feet by 30 for one hundred 
 cows. It is well known that without a suitable place for preserving the milk 
 and performing the various operations, the dairy business cannot proceed with 
 any prospect of advantage. To preserve an equable temperature, a northern 
 aspect has been suggested as the most proper. These apartments should be dry, 
 and to render them clean and sweet at all periods without much trouble, their 
 situation should be in the immediate neighbourhood of a spring or clear 
 rivulet. The roof and walls should also be defended from the action of the 
 sun's rays by shady trees, buildings, &c. For the milk dairy two good rooms 
 are all that are necessary ; namely, one for scalding, cleaning, and airing the 
 utensils, and the other for the reception of the milk. For a butter dairy three 
 apartments will be required ; one for holding, washing, scalding, and airing the 
 utensils ; one for keeping the milk ; and one for churning the butter. Four 
 apartments are necessary to a well-constructed cheese dairy ; namely, one for 
 the reception of the milk : another for the scalding and pressing of the cheese ; 
 a third, where it is salted ; and a fourth, called the cheese-loft, in which the 
 cheeses are deposited." As respects the dairy utensils, our writer states, that 
 " the only proper materials for making the vessels and implements belonging to 
 a dairy are wood, porcelain, glass, and slate ; they are, however, made mostly 
 of wood, as glass and porcelain are too expensive ; slate has lately been em- 
 ployed in constructing milk coolers." Tinned iron is, however, often used for 
 skimming dishes and other purposes ; lead and glazed earthenware form many 
 of the utensils in some dairies, and cast iron has been recommended for the 
 same purpose: but it will be proper to observe that lead is poisonous, and so are 
 some of the metallic substances that enter into the composition which forms the 
 glazing of earthenware. Now, since milk contains acids capable of dissolving 
 these metallic compounds, it must follow that the use of them in a diary must 
 be very prejudicial. The human constitution must infallibly be injured by 
 imbibing these deleterious solutions ; but the progress of the mischief is slow ,
 
 42S .DECOMPOSITION. 
 
 and when at length the mischief is discovered, we seldom or never ascribe it 
 to the proper cause. Nor is the use of iron to be recommended, for though its 
 solution in the acid of milk may be harmless, yet the milk, butter, and cheese, 
 into which this solution enters, may be altered in their taste, and acquire new 
 properties from it. The best vessels and utensils for the dairy are, therefore, 
 those which are made of wood, and which are kept in a sweet and clean state 
 by daily scalding, scouring, &c. The utensils which are most generally wanted 
 in a dairy farm, are milk-pails, skeels, bowls, strainers and coolers, churns, 
 lading and skimming dishes, cheese tub, ladders, vats, cloths, and presses. The 
 fitting a dairy, where one churn is used, with these utensils, will cost from 
 twenty to twenty-four pounds, this is the estimated value in Gloucestershire ; 
 in a farm consisting of twenty-five or thirty cows the cost would probably be 
 double that sum, and so on, in proportion to the magnitude of the farm. 
 
 DAMAJAVAG. This singular name has been given to a preparation of 
 the chestnut tree, and is employed in tanning as a substitute for oak bark and 
 gall nuts : it is the subject of a patent granted to Charles Louis Giroud, of 
 Queen-street, Soho, London, in 1825. The mode of preparing damajavag is 
 as follows : The external shell of the chestnut, or the wood itself, is to be broken 
 into small pieces, and soaked in double its weight of water for twelve hours, 
 then boiled for three or four hours, when the liquid is to be drawn off, and 
 filtered through a cloth or sieve to separate the fibrous matter. The liquid 
 extract is now to be evaporated by returning it into the boiler, and the ebullition 
 is to be renewed and continued until the extract becomes of the consistency of 
 paste ; after this it is to be cut into cakes, and dried in an oven for sale, or at 
 once applied to the various purposes in the arts, in lieu of gall nuts. One 
 hundred pounds of chestnut shells will thus produce about eight pounds of 
 damajavag. The sap of the chestnut tree contains similar properties to the wood 
 and the nut shell, but combined with a greater portion of mucilage. The trunks 
 of the trees may be tapped, the sap collected, and an extract made from it by 
 simple evaporation. Iron vessels should not be used in the preparation of dama- 
 javag, as that metal would darken the colour of the extract, owing to the affinity 
 between iron and the gallic acid of the chestnut, their combination producing ink. 
 
 DAMASK. The name given to silk or linen fabrics with a raised pattern 
 on the right side. 
 
 DAMASKENING. The art of beautifying iron, steel, &c. by making 
 incisions in them, and filling them up with gold or silver wire ; it is chiefly 
 used for adorning swoi-d blades, locks of pistols, &c. Sac IRON. 
 
 DAVIT. A projecting piece of timber, used as a crane to hoist the flukes 
 of the anchor to the top of the bow of a ship. 
 
 DEAD LIGHTS. Strong wooden shutters for closing the stern windows of 
 a ship in bad weather. 
 
 DEAD RECKONING. An account of the progress of a vessel, showing 
 the courses steered by compass, with the distance in miles and fathoms run 
 upon each course. These courses, corrected by allowances for leeway and 
 variation, and the distances by allowances for heave of the sea and currents, 
 form what is termed the corrected dead reckoning, which is used for ascertaining 
 the vessel's place upon a chart, in default of observations of the celestial bodies 
 to determine the same. 
 
 DEAL. A stout kind of plank made from the fir-tree by sawing the trunk 
 longitudinally. 
 
 DECIMAL ARITHMETIC, in general sense, denotes the common arithmetic 
 in which we count by periods of tens ; it is otherwise and more properly called 
 denary arithmetic, to distinguish it from the binary, duodenary, and other scales 
 of arithmetic. 
 
 DECOCTION. A fluid which has been made to take up certain soluble 
 principles by boiling. 
 
 DECOMPOSITION, in Chemistry, the separation of the component parts 
 of bodies from each other. It is in general the effect of some new combination 
 amongst the constituent principles of bodies, the only exceptions being those 
 decompositions which are effected by heat or electricity.
 
 DENDROMETER. 429 
 
 DECREPITATION. The crackling noise which several salts make when 
 suddenly heated, accompanied by a violent exfoliation of their particles. It 
 has been attributed to the sudden conversion of the water they contain into 
 steam ; " but," observes Dr. Ure, " it is the salts which are anhydrous, or 
 contain no water, that decrepitate most violently ; those that contain water 
 generally enter into tranquil liquefaction on being heated." Salts decrepitate 
 for the same reason that glass, quartz, and cast iron crack with an explosive 
 force, on being suddenly heated, namely, from the unequal expansion of the 
 laminae which compose them, in consequence of their being imperfect con- 
 ductors of heat. 
 
 DEFLAGRATION. The act of burning two or more substances together, 
 as charcoal and nitre. 
 
 DEFLEXION, in Mechanics, the bending of any material exposed to a 
 transverse strain. **In all bodies so situated deflexion takes place; but whilst 
 the elastic force of the material exceeds the straining force, the deflexion will 
 be directly proportional to the pressure, and will not increase after the load has 
 been on for a second 01 two, and upon its removal the material will recover its 
 original form; but if the load exceed the elastic force of the material, the 
 extension or deflexion increases with time, a permanent alteration of form 
 ensues, and the deflexion increasing rapidly with slight addition to the load, 
 fracture ensues. The resistance of a material to flexure, as Mr. Tredgold 
 observes, is the only proper measure of its resistance, when it is to be applied 
 in the construction of buildings, and that of its resistance to permanent alteration 
 when it is used for machines. According to Mr. T.'s experiments, a bar of cast 
 iron, 4 feet long and 1.2 inches square, and supported at both ends, sustained a 
 load of 112 Ibs. in the middle of its length without permanent alteration. The 
 deflexion with this load was one-tenth of an inch. 
 
 DEGREE, in Geometry, the 360th part of the circumference of a circle, 
 into which number of parts all circles are considered to be divided ; it is 
 indicated by a small near the top of the figure ; thus, 45 is forty-five degrees. 
 Each degree is subdivided into sixty smaller parts, called minutes, and denoted 
 by the mark' ' ; and these again are each subdivided into sixty parts, called 
 seconds, and marked thus " ; thus, 45 12' 20" is forty-five degrees twelve 
 minutes and twenty seconds. 
 
 DELFT WARE. A kind of pottery, covered with an enamel or white 
 glazing, which gives it the appearance of porcelain. They are composed of a 
 fatty clay, with which is ground a portion of sand, that it may not crack or 
 shrink too much in baking. Vessels formed of this earth require to be dried 
 very gently, to avoid cracking ; they are then slightly baked in a furnace, to 
 give them a degree of hardness ; after which, the enamel, ground very fine and 
 diluted with water, is applied, and as the ware is very porous from being but 
 slightly baked, it readily absorbs the water, leaving a coating of enamel adhering 
 to the surface. The ware, when thoroughly dried, is then enclosed in cases of 
 baked earth, and subjected to a heat sufficient to fuse the enamel uniformly, 
 and at the same time to complete the baking. Delft ware was formerly made 
 chiefly at Delft, in Holland, from which town it takes its name. 
 
 DELIQUESCENT, in Chemistry, a property of various substances (chiefly 
 salts), to absorb moisture from the atmosphere, and dissolve. 
 
 DENDROMETER. An instrument for measuring trees, invented by 
 Messrs. Duncombe and Whittel. It consists of a semicircle, divided into two 
 quadrants, and graduated from the middle ; upon the diameter there 
 
 * plummet for fixing the instrument in a vertical position. The principal use 
 jf it is for measuring the length and diameter of any tree perpendicular or 
 oblique to an horizontal plane, or in any situation of the plane on which it 
 rests ; or of any figure, whether regular or irregular, and also the length and 
 diameter of the boughs, by mere inspection. The inventors of it have calcu- 
 lated tables, annexed to their account of the instrument itself, by the help of 
 which the quantity of timber in a tree is obtained without calculation, or 
 the use of the sliding rule. The dendrometer, fitted to a theodolite, may be 
 applied to measuring the heights and distances of objects accessible or inacces- 
 3 i
 
 40 DETONATING JAR. 
 
 fcible, whether situated in planes parallel or oblique to the plane on which the 
 instrument is placed. It may be also used for taking all angles, whether vertical, 
 horizontal, or oblique, in any position of the planes in which they are formed. 
 
 DENSITY is the proportionate quantity of matter in bodies of a given 
 magnitude ; thus, if a body contains more matter than another, both being of 
 the same bulk, the former is said to be more dense than the latter, and that in 
 proportion to the relative quantities of matter they contain ; or if the former 
 body contains the same quantity of matter as the latter, but under a less bulk, 
 its density is greater in proportion as its bulk is less than that of the other. 
 Hence the density is directly proportional to the quantity of matter, and in- 
 versely proportional to the bulk under which it is contained. The relative 
 quantities of matter in bodies are known by their gravity or weight; for, according 
 to Sir Isaac Newton, the original particles of matter being equal, and con- 
 sequently endowed with equal gravity, bodies, or assemblages of those particles, 
 will have a gravity proportionate to the number of particles contained in them. 
 Hence, when a body, mass, or quantity of matter is spoken of, its weight or 
 gravity is always understood, that being the proper measure of the quantity of 
 matter. The density of bodies is found by weighing equal bulks of each ; for 
 this purpose solids must be previously reduced to the same shape and size, but 
 each fluid should fill the same vessel, in which they must be weighed separately. 
 The density of fluids may also be determined by the following methods. First, 
 by making an equilibrium between them, in tubes that communicate ; for the 
 diameters of the tubes being equal, and the weights or quantities of matter also 
 equal, the densities will be inversely as the altitudes of the liquors in them ; 
 that is, inversely as their bulk. Secondly, by immersing a solid in the fluids, 
 their densities may be readily compared ; for if the solid be lighter than the 
 liquids, the part immersed by its own weight will be inversely as the density of 
 the fluid ; but if the body be heavier, so as to sink in the liquid, it must be 
 weighed in them separately, and the weight lost by the body in each will be 
 directly as the density of the fluid. Sir Isaac Newton, and most of the other 
 philosophers, are of opinion that there is no such thing as a space absolutely 
 full of matter, and that consequently there is no substance in nature, either 
 solid or fluid, that is perfectly dense : the densest bodies, according to Newton, 
 consist of much more porous space than solid matter. 
 
 DEPARTURE, in Navigation, the distance of a ship or place to the east or 
 west of any meridian, expressed in nautical miles, whilst the difference of 
 longitude is the same distance reckoned in degrees and minutes upon small 
 circles of the earth, termed parallels of latitude ; and as these small circles 
 continually decrease as they approach the poles, and as every circle, large or 
 small, contains 360, each containing 60', the length of the degrees and minutes 
 of longitude must vary with the latitude. 
 
 DEPHLEGMATION. The operation by which bodies are deprived of 
 water, which is principally effected by evaporation. 
 
 DEPHLOGISTICATION. The operation by which bodies are deprived of 
 phlogiston, or the inflammable principle, and nearly synonymous with what is 
 now expressed by oxygenation or oxidization. 
 
 DESCENDING CLOCK. A clock so constructed that by gradually rolling 
 down an inclined plane it shows the progress of time ; the motion is com- 
 municated to the wheels by a weight, which revolve about the axis as the 
 clock descends. A drawing and description of this machine is given in Emerson's 
 Mechanics. 
 
 DESIGNING is the art of delineating or drawing the appearance of objects 
 by lines on a plane ; but, the term is more generally understood to apply to the 
 first sketch of a work which it is intended afterwards to execute with greater 
 accuracy of detail or of finish, or upon a different scale of magnitude. A 
 design bears the same relation to drawing and painting as a model does to the 
 making of a machine or building. 
 
 DETENT, in Clock-making, a stop, which, being lifted up and let fall down, 
 locks and unlocks the striking parts of a clock. 
 
 DETONATING JAR. An apparatus for firing a mixture of gases by
 
 DETONATING POWDERS. 431 
 
 means of the electric spark. It consists of a thick glass tube, open at bottom, 
 but hermetically sealed at top, and having towards the upper part two small 
 wires cemented into it, which approach each other within the jar near enough to 
 communicate the electric spark from an adjoining machine, by which the gases 
 are fired. 
 
 DETONATING POWDERS, or FULMINATING POWDERS. Certain chemical 
 compounds, which, on being exposed to heat or friction, explode with a loud 
 report, owing to one or more of the constituent parts assuming the elastic state 
 with such rapidity as to strike the displaced air with great violence. The most 
 common detonating powders (except gunpowder), are fulminating gold, and 
 fulminating powder. This latter is made by triturating, in a warm mortar, 
 three parts by weight of nitre, two of carbonate of potash, and one of flowers 
 of sulphur. When fused in. a ladle and then set on the fire, the whole of the 
 melted fluid explodes with an intolerable noise, and the ladle is commonly 
 disfigured as if it had received a strong blow downwards. If a solution of 
 gold be precipitated by ammonia, the product will be fulminating gold. This 
 precipitate, separated by filtration, and washed, must be dried without heat, as 
 it is liable to explode with no great increase of temperature ; nor must it be 
 put into a bottle with a glass stopper, as the friction of this would expose the 
 operator to the same danger. Less than a grain held over the flame of a candle 
 explodes with a very sharp and loud noise. Fulminating silver may be prepared 
 as follows: powder one hundred grains of nitrate of silver, put the powder into 
 a glass vessel, and pour upon it first an ounce of alcohol, and then as much con- 
 centrated nitrous acid. The mixture grows hot, boils, and an ether is visibly 
 formed, that changes into gas. By degrees the liquor becomes milky and opaque, 
 and is filled with small white clouds. When all the grey powder has taken this 
 form, and the liquid has acquired consistency, distilled water must be imme- 
 diately added, to suspend ebullition and prevent the matter from being redissolved 
 and becoming a mere solution of silver. The white precipitate is then to be 
 collected on a filter, and dried. The force of this powder greatly exceeds that 
 of fulminating mercury : it detonates in a tremendous manner on being scarcely 
 touched with a glass tube, the extremity of which has been dipped in concen- 
 trated sulphuric acid. Fulminating mercury was discovered by Mr. Howard. 
 A hundred grains are to be dissolved with heat in an ounce and a half by 
 measure of nitric acid. The solution, when cold, is to be poured on two ounce 
 measures of alcohol, and heat applied till an effervescence is excited. As soon 
 as the precipitate is thrown down, it must be collected on a filter, that the acid 
 may not react on it, washed, and dried by a very gentle heat. It detonates 
 with very little heat or friction. Three parts of chlorate of potash, and one of 
 sulphur, triturated in a metal mortar, cause numerous successive detonations, 
 like the cracks of a whip, the reports of a pistol, or the fire of musketry, 
 according to the rapidity and force of the pressure employed. A few grains 
 struck with a hammer on an anvil explode with a noise like that of a musket, 
 and torrents of purple light appear around it. Six parts of the chlorate, one 
 of sulphur, and one of charcoal, detonate by the same means, but more strongly, 
 and with a redder flame. Sugar, gum, or charcoal, mixed with the chlorate, 
 and fixed or volatile oils, alcohol, or ether, and made into a paste, detonate very 
 strongly by the stroke, but not by trituration. Some of them take fire, but 
 slowly and by degrees, in sulphuric acid. Fulminations of the most violent 
 kind require the agency of azote or nitrogen, as we see not only in its compounds 
 with the oxides of gold, silver, and plalina, but also still more remarkably in 
 its chloride and iodide, which form the two most violent detonating compounds 
 known. The first of these, viz. the chloride of azote, was discovered in 1812, 
 by M. Dulong, but its nature was first investigated by Sir H. Davy, who was 
 twice seriously wounded by explosions of the substance whilst operating upon 
 it. It may be prepared as follows : put into an evaporating porcelain basin a 
 solution of one f part of nitrate or muriate of ammonia, in ten parts of water 
 heated to about 100, and invert into it a wide -mouthed bottle filled with 
 chlorine. As the liquid ascends by the condensation of the gas, oily looking 
 drops are seen floating on its surface, which collect together, and fall to the
 
 432 DIALLING. 
 
 bottom in large globules : this is chloride of azote. By putting a thin stratum 
 of common salt at the bottom of tlie basin, we prevent the decomposition of 
 the chloride of azote by the ammoniacal salt. It should be prepared only in 
 very small quantities. A small quantity of it thrown into a glass of olive oil, 
 produced a most violent explosion, and the glass, although a strong one, was 
 broken into fragments. It also detonates strongly when brought into contact 
 with phosphorus and many of its compounds, with various fixed oils, with oil 
 of turpentine, naphtha, fused potash, aqueous ammonia, nitrous gas, and various 
 other substances, but not with sulphur or resin. Iodide of azote may be most 
 readily prepared by putting pulverulent iodine into common water of ammonia. 
 It is pulverulent, and of a brownish black colour. It detonates from the 
 smallest shock, and from heat, with a feeble violet vapour. When properly 
 prepared, it frequently detonates spontaneously ; hence, after the black powder 
 is formed, and the liquid ammonia decanted off, the capsule should be left in 
 perfect repose. Dr. lire mentions, that in transferring a little of it from a 
 capsule of platina to a piece of paper, the whole exploded in his hands. It 
 should therefore be prepared with the greatest care, and in only very small 
 quantities, and should not be preserved. 
 
 DI ACOUSTICS. The consideration of the properties of sound refracted in 
 passing through different media. 
 
 DIAGONAL, in Geometry, a right line drawn across a figure from the 
 vertex of one angle to the vertex of another. 
 DIAGONAL SCALE. See SCALE. 
 
 DIAGRAM. A geometrical scheme for the explanation of the properties 
 of a figure, or for the illustration of machinery ; in which case it differs from a 
 drawing, by the parts being represented by single lines without any breadth. 
 
 DIAL, or SUN DIAL. An instrument for measuring time by means of a 
 shadow cast by the sun upon a surface properly placed for the purpose. Sun 
 dials are an invention of very great antiquity, and are frequently mentioned in 
 the Bible ; and Vitruvius speaks of one made by the ancient Chaldee historian, 
 Berosus, on a reclining plane, almost parallel to the plane of the equinoctial. 
 Before the invention of clocks and watches, dials afforded almost the only means 
 of marking the lapse of small portions of time; and dials were, therefore, gene- 
 rally to be seen in most places of public resort, as churches, crossways, mar- 
 kets, &c. ; but since that invention, and the immense improvements made in 
 it, dials have gone gradually into disuse, and are now rarely to be met with in 
 England, where, indeed, the variable nature of the climate materially limits 
 their utility. On the Continent they are still to be met with ; and one kind, 
 called the pillar dial, consisting of an elegant stone column, is frequently introduced 
 as an ornament in the squares and market places. Our ingenious neighbours, 
 the French, have likewise contrived a method of calling attention, at least once 
 in the day, to the silent progress of the shadow over the dial, by means of a 
 small mortar placed on the meridian line of a dial with a burning lens placed 
 over the touch-hole, at such a distance and angle, that as soon as the sun 
 arrives on the meridian, its rays, concentrated by the lens, set fire to the 
 powder, which discharges the gun, and thus announces the hour of noon. 
 " We take no note of time but from its loss; 
 To give it then a tongue is wise in man." 
 
 Dials of this description are placed in the gardens of the Palais Royal, and of 
 the Luxembourg. 
 
 DIALLING. The art of drawing dials on any surface, plane or curved. On 
 account of the limited utility of this art, from the causes before noticed, we shall 
 confine ourselves to explaining the general principles of dialling, which may be aptly 
 illustrated by the phenomena of a hollow or transparent sphere of glass. Then 
 suppose a PBp to represent the earth as transparent, and its equator as divided 
 into 24 equal parts, by so many meridian semicircles, a b c, &c., one of which 
 is the geographical meridian of any given place, as London, which is supposed 
 at the point a; and if the hour of 12 be marked upon that meridian, and 
 upon the opposite one, and all the rest of the hours in succession on the other 
 meridians, those meridians would be the hour circles of London; because, as the
 
 DIAMOND. 433 
 
 sun appears to move round the earth, which is in the centre of the visible 
 heavens, in twenty-four hours, he will pass 
 from one meridian to another in an hour. 
 Then, if the sphere had an opaque axis as 
 P e P, terminating in the poles P and P, the 
 shadow of the axis, which is in the same plane 
 with the sun and with each meridian, would 
 fall upon every particular meridian and hour 
 when the sun came to the plane of the oppo- 
 site meridian, and would, consequently, show 
 the time at London and at all other places on 
 the same meridian. If this sphere were cut 
 through the middle hy a solid plane A B C D 
 in the rational horizon of London, one-half of 
 the axis e P would be above the plane, and 
 the other below it; and if straight lines were drawn from the centre of the 
 plane to those points where its circumference is cut by the hour circles of the 
 sphere, those lines would be the hour lines of an horizontal dial for London ;- 
 for the shadow of the axis would fall upon each particular hour line of the 
 dial when it fell upon the like hour circle of the sphere. Those who are further 
 interested in the subject we would refer to Emerson's Dialliny, and Ferguson's 
 Lectures on Mechanics. Dr. Brewster, in the Appendix to his valuable edition 
 of this latter work, has described an analemmatic dial, which sets itself. Many 
 ingenious constructions of dials are also given in Dr. Mutton's Translation of 
 Montucla's Recreations. 
 
 DIAMETER, in Geometry, the line which, passing through the centre of a 
 circle, or other curvilinear figure, divides it or its ordinates into two equal 
 parts. 
 
 DIAMOND. The most brilliant and the most valued of all the minerals. 
 It is found of all colours white, grey, red, brown, yellow, green, blue, and 
 black ; the colourless varieties are the most esteemed. If very transparent and 
 pure, they are said to be of the first water ; and in proportion as they depart 
 from this transparency and purity, they are denominated of the second or third 
 water. The extraordinary lustre of the diamond is said to be derived from its 
 reflecting all the light which falls on its posterior surface at an angle of inci- 
 dence greater than 24 13' ; artificial gems reflect only half this light. The 
 weight, and, consequently, the value of diamonds, is estimated in carats, one of 
 which is equal to four grains ; and the piece of one diamond, compared to that 
 of another of equal colour, transparency, purity, form, &c., is as the squares 
 of the respective weights. The average price of rough diamonds that are worth 
 working is about two pounds for the first carat ; and the value of a cut diamond 
 being equal to that of a rough diamond of double weight, exclusive of the price 
 of workmanship, the cost of a wrought diamond of 
 
 1 carat is 8 
 
 2 ditto is 2 2 x 8 = 39 
 
 3 ditto is 3* x 8 = 72 
 
 4 ditto is i'xS = 128 
 
 5 ditto is 5 2 X 8 = 200 
 
 This rule is, however, not extended to diamonds of more than 20 carats 
 (value 3,200/.) ; the larger ones, in consequence of the scarcity of purchasers, 
 being disposed of at prices greatly inferior to their estimated worth. It does 
 not appear that a larger stun than 130,000^. was ever given for a diamond, 
 which was brought by a gentleman named Pit, from India, and was hence 
 called the Pit diamond. Diamonds can only be cut and polished by their own 
 substance. The operation is commenced by rubbing several against each other 
 while rough, after having first glued them to the ends of two wooden blocks, 
 thick enough to be held in the hand. The powder thus rubbed off the stones
 
 434 DILATATION 
 
 is received into a little box for the subsequent purposes of grinding and pohsfi- 
 ing them. These operations are effected by a mill, which turns a wheel of soft 
 iron, on which is sprinkled the diamond dust, mixed with oil of olives ; the 
 particles of diamond becoming imbedded in the soft iron by the rubbing action, 
 and presenting a multiplicity of opposing cutting angles to the stone under 
 operation, which is thereby shaped according to the design of the operator. 
 The same dust well ground and diluted with water and vinegar is used in the 
 sawing of diamonds, which is performed by an extremely fine iron or brass 
 wire ; the operation being similar in principle to the sawing of blocks of stone 
 for the use of the mason, by means of sharp sand and a blunt blade of iron. 
 Brilliants are those diamonds which are cut in faces at the top and bottom, 
 and whose table or principal face at top is flat. Rose diamonds are quite flat 
 underneath, with the upper part cut into many little facets, usually triangles, 
 the uppermost of which terminates in a point. The only chemical difference 
 between diamond and the purest charcoal is, that the latter contains an 
 extremely minute portion of hydrogen. It is said that diamonds have been 
 recently artificially produced from charcoal. 
 
 DIAPASON. An interval in music that expresses the octave of the Greeks. 
 This term is likewise applied to the rule or scale whereby musical instrument 
 makers adjust the pipes of organs, and cut the holes of hautboys, flutes, &c. 
 in due proportion, for performing the tones, semi-tones, and concords, with 
 precision. 
 
 DIAPER. A kind of cloth, on which is formed a variety of designs, chiefly 
 employed for table linen. See WEAVING. 
 
 DICE. Small cubical pieces of bone or ivory, marked with dots on each 
 face, from one to six. To give uniformity to their figure, or to make true dice, 
 is of course a very simple art ; but the ingenuity of the dice-maker is called 
 into action to construct false or untrue dice for the sharping gamester ; for him 
 they are so skilfully constructed or loaded, as to ensure a preponderance of 
 favourable chances, without incurring the probability of the cause being dis- 
 covered. Some of their nefarious processes are known to us, but it is not our 
 province to extend the knowledge of so vile an art. 
 
 DIFFERENCE is the remainder after taking the less of two quantities from 
 the greater. 
 
 DIFFERENTIAL, in the higher Geometry, is an infinitely small quantity, 
 or part of quantity, so small as to be less than any assignable one, and is thus 
 denominated because it is frequently considered as the difference of two 
 quantities, and as such, is the foundation of the differential calculus. The 
 term differential is also applied, in Mechanics, to various machines for imparting 
 to a body the difference of motion of two other bodies moving in contrary 
 directions ; an example of this is shown in the Chinese crane, under the 
 article CRANE. For further instances, see PULLEY DIFFERENTIAL, SCREW 
 DIFFERENTIAL, and WHEEL DIFFERENTIAL. 
 
 DIGESTER. A strong vessel formed of iron or copper, the lid of which 
 screws down, and is made tight by luting or grinding; and the steam not 
 being allowed to escape, the water acquires a very high temperature, by which 
 its solvent powers are greatly increased. To prevent accidents, a small safety 
 valve is inserted in the lid. The digester is the invention of the celebrated 
 Papin. 
 
 DIGIT, in Arithmetic, any one of the ten numerals 1, 2, 3, 4, 5, 6, 7, 8, 9, 
 also a measure equal to three-quarters of an inch. 
 
 DILATATION. The expansion of a body into a greater bulk by its ov_ 
 elastic power. It differs from rarefaction : for though the effects of both are 
 nearly, if not quite the same, yet the latter arises from the application of heat. 
 It has been observed by modern philosophers, that bodies which have been 
 compressed and are again set at liberty endeavour to dilate themselves with a 
 force equal to that by which they are compressed ; accordingly they are found 
 to sustain a force and raise a weight equivalent to the force of compression. 
 Bodies in the act of dilating by their own elasticity exert a greater force at the 
 beginning than towards the end, as being at first more compressed ; and the
 
 DISTILLATION. 435 
 
 greater the compression is the greater is the elastic power and endeavour to 
 dilate : hence the compressing power, the compression, and tho elastic force, 
 are necessarily equal, and may be taken the one for the other. The motion 
 by which compressed bodies restore themselves is usually accelerated, though 
 sometimes not. When compressed air begins to restore itself, and dilate into 
 a larger space, it is still compressed, consequently new impetus is continually 
 impressed upon it by the dilatative cause ; and the former remaining with this 
 continual addition, the effect, namely, the velocity, must likewise evidently be 
 increased. But it may also happen, that where the compression is only partial, 
 the motion of dilatation will not only not increase, but be even retarded, as 
 is the case when sponge, soft bread, gauze, and other similar bodies, are 
 compressed. 
 
 DIOPTRICS. The doctrine of refracted vision, which investigates and 
 explains the effects of light refracted by passing through different media, as 
 air, water, glass, &c. 
 
 DISTILLATION. The art of obtaining in a separate state, by the appli- 
 cation of heat, the more volatile parts of bodies ; but the term is generally 
 limited to signify the separation of volatile liquids, for when the volatile product 
 is obtained from a solid, and assumes a solid form, the operation is termed 
 sublimation. In the distillation of liquids the most volatile parts rising in 
 vapour first are conducted to variously disposed refrigerators, usually composed 
 of metal, and surrounded with cold water, which, abstracting a portion of heat 
 from the vapour, it becomes condensed, and assumes a liquid form. One of 
 the principal applications of the art of distillation is the preparation of spirituous 
 liquors, which is usually divided into two branches. The first, termed distillation, 
 consists in separating the spirituous parts of fermented liquors, mixed with a large 
 portion of water, from the fixed or nonvolatile parts ; and in the latter branch, 
 termed rectification, the spirit is concentrated and purified principally by means 
 of redistillation. Having already treated largely upon the various methods of 
 effecting this, under the head ALCOHOL, we shall in this place limit ourselves 
 principally to the description of the preparatory process of distillation, together 
 with some of the most approved apparatus employed therein. 
 
 In London and its neighbourhood the process of forming the wash for 
 distillation is the same as in brewing for beer, except that no hops are used, 
 and that instead of boiling the wort they pump it into coolers, and afterwards 
 draw it into backs, to be then fermented with yeast. During the fermentation, 
 considerable attention should be paid to the temperature of the liquid, which 
 should be steadily maintained at about 70 Fahr., and the fermentation is 
 continued until the liquor grows fine and pungent to the taste, but not so long 
 as to allow acetous fermentation to commence. In this state the wash is put 
 into the still (of which it should occupy about three-fourths), and distilled with 
 a gentle fire as long as any spirit comes over, which is generally until about 
 half the wash is consumed. The form of the common still is too well known to 
 need any particular description. It generally consists of a large boiler made 
 of copper, and fixed in masonry over a fire-place. The boiler has a head, or 
 capital, as it is called, which is of a globular form, to which is soldered a neck, 
 forming an arch curved downwards, and fits into what is called the worm : this 
 is a long tube, made generally of pewter, of a gradually increasing diameter ; 
 it is curled round in a spiral form, and enclosed in a tub, which is kept filled 
 with cold water during distillation. That celebrated philosopher and mechanic, 
 the late Mr. Watt, having ascertained that liquids boil in vacuo at a much 
 lower temperature than when under the pressure of the atmosphere, endeavoured 
 to turn this circumstance to advantage in distillation, under the idea that less 
 fuel and also less water for condensation would be required ; but found, by 
 experiment, little or no advantage in this respect, the latent heat of the vapour 
 being nearly the same, whether formed in vacuo or under the pressure of the 
 atmosphere. The idea of distillation in vacuo was subsequently taken up by 
 Mr. Tritton, as affording a means of preventing any empyreumatic flavour 
 being imparted to the spirit by the burning of any matter contained in the still, 
 as a heat considerably less than 212<> Fahr. is sufficient to cause the wash to
 
 435 
 
 DISTILLATION. 
 
 boil rapidly in vacuo. The annexed diagram exhibits a section of Mr. Tritton's 
 apparatus for distilling in vacuo. A is the body of the still ; B is a water 
 
 bath, into which the body of the still is immersed ; C is the head or capital , 
 D the neck of the same, which, curving downwards, is connected with a pipe 
 that enters the condensing vessel E ; F is a refrigeratory or close vessel, con- 
 taining cold water, for converting into liquid the spirituous vapours, which, 
 having been raised in the still, are contained in the vessel E. From the bottom 
 of the vessel E a pipe issues, for conveying the liquid 
 and the vapour not yet condensed into vessel G, 
 which being surrounded with cold water contained in 
 the vessel H, acts also as a refrigeratory, and reduces 
 the whole of the remaining vapour into a liquid state. 
 I is an air pump for effecting a vacuum in the vessels 
 AEG; K is a stop-cock for cutting off the commu- 
 nication between the vessels E and G, when the 
 contents of G are drawn off by the cock M, by which 
 means a vacuum is preserved during that operation in 
 the vessel E and the still A. L is an air cock, to 
 admit air into the vessel G, to allow the contents to 
 run out at M ; N is the discharge cock to the still A. 
 It will be seen that the greatest heat to which the 
 matter in the still can be subjected can never exceed 
 212 Fahr. ; but upon the pressure of the atmosphere 
 being removed by means of the air-pump, the dis- 
 tillation is effected at the low temperature of 132 Fahr., 
 by which means all injury to the flavour of the spirit, 
 by carbonization of the matters contained in the still, 
 is entirely avoided. 
 
 Dr. Arnott, in his work on the Elements of Physics, 
 proposes a mode of distilling or evaporating in vacuo, 
 without the aid of an air pump, by simply establishing 
 a communication between a close distilling or evapo- 
 rating vessel, and the top of a water barometer. The 
 principle of this method will be readily comprehended 
 by referring to the annexed diagram and its accom- 
 panying explanation, a is the evaporating vessel or 
 still, the neck of which communicates with a strong 
 vessel b, forming the top of the barometer ; from the 
 under side of b proceeds a tube, plunging in a small vessel d, situated 36 feet 
 below the bottom of b. The cocks at d and e being shut, the vessel b and the 
 descending pipe are to be filled with water through a cock c at the top ; then 
 
 d,
 
 DISTILLATION. 
 
 437 
 
 this cock being shut, and the cock at d opened, the water will sink down out of 
 the vessel b until the column in the tube be only 34 feet high, as at /, that 
 being the height which the atmosphere will support. On opening a commu- 
 nication between the vessel a and the vacuum in b, the operation goes on as 
 desired, and the steam arising from a may be constantly condensed by allowing 
 a small stream of water to run through b from above, in cases where it is sought 
 to concentrate any liquid in a in vacuo ; but for distillation, where the condensed 
 vapour is the product which is sought, the water must be applied externally to 
 b, by placing that vessel in another vessel g, kept constantly full of water. If 
 the vacuum becomes destroyed by the accumulation of the air extricated in 
 boiling, it may be easily restored by refilling 6 as at first. Dr. Arnott states 
 that he planned this arrangement as a simple apparatus for the preparation of 
 medicinal extracts, as many watery extracts from vegetables have their virtues 
 impaired or destroyed by a heat of 212; but when the water is driven off in 
 vacuo, the temperature need never be higher than blood heat. The doctor 
 further observes, that this plan appears " particularly well suited to the colonies, 
 where air-pumps and nicer machinery can with difficulty be either obtained or 
 managed." 
 
 The annexed engraving represents Sir Anthony Perrier's improved apparatus 
 for distillation. The object of this invention is to cause the liquid to flow 
 gradually over the heated surface of the body of the still, and during its 
 progress to give out its spirituous vapour, and to maintain a continuous and 
 
 uninterrupted distillation as long as the supply of liquid is furnished and the fire 
 kept up. Fig. 1 is a view, in profile, of the section of the still, and Fig. 2 is a 
 plan of the same. The bottom of this boiler is divided by concentric partitions, 
 which stand up, as in Fig. 1, sufficiently high to prevent the liquor from boiling 
 over. These partitions have openings from one to the other at opposite sides, 
 so as to make the course a sort of labyrinth, /is a reservoir of liquor prepared 
 for the operation ; g is a pipe or tube descending from the reservoir, and 
 3*
 
 4.38 
 
 DISTILLATION. 
 
 conducting the liquor to that part of the boiler marked //, which is the commence- 
 ment of the race. From hence the liquor flows through the channels, as shown 
 by the bent arrows, progressively traversing the whole surface of the bottom, 
 whereby the full effect of the fire is exerted upon small portions of the liquid, 
 which causes the evaporation U> proceed with great rapidity. The residue of 
 the liquid then passes off by the discharge pipe i, which is made to slide, for 
 the purpose of regulating the quantity and depth of fluid in the still ; and this 
 pipe should be in such proportion to the admission pipe, as to cause the perfect 
 distillation of the liquor in its passage to the regulating tube. In the still, as 
 shown at Fig. 1, a set of chains are seen suspended from a bar i /, supported 
 by a centre shaft, which may be put in motion by a toothed wheel and pinion, 
 actuated by a crank or winch. These chains hang in loops, and fall into the 
 spaces between the partitions, for the purpose of sweeping the bottom of the 
 still, and preventing the material operated upon from burning, when of a thick 
 or glutinous nature, as turpentine, syrups, &c. 
 
 In the still we are now about to describe, invented by Mr. Frazer, of 
 Houndsditch, the object is the economizing of fuel, and the production of a pure 
 spirit, by a peculiar arrangement of the vessels employed, that shall at the same 
 time be in perfect accordance with the existing excise laws. The wash still, 
 instead of being exposed to naked fire, is immersed in boiling water, the vapour 
 from the former enters the low wine still, where it is condensed ; the wine thus 
 abstracts the heat from the wash, becomes itself vapourized, and is conducted 
 into a refrigeratory ; the first and second distillations are in this manner con- 
 ducted together by a continuous process, which will be best understood by a 
 reference to the annexed diagram, a is a supposed steam engine boiler, or 
 
 other similar vessel, the heat from which boils the wash (or low wine) in the 
 still b. To prevent the liquid from boiling over into the condenser, the neck is 
 formed of the shape shown at i ; from hence the vapour passes through a steam- 
 tight case e, immersed in a reservoir c, containing either wash or the product 
 of the first distillation, where it becomes partly condensed ; the vapour and 
 condensed liquid then descend through the worm beneath, wherein the
 
 DISTILLATION. 439 
 
 condensation is completed and the liquid cooled, which then runs into the closed 
 recipient d underneath. This recipient d therefore contains the weak spirit of 
 the first distillation, called low wines, to re-distil which product it is raised by 
 the pump /, and discharged into the reservoir c, which is, in effect, the low 
 wine still. The liquid in this vessel, as before mentioned, is vapourized by the 
 heat of the vapour from the wash still passing through it; it is afterwards 
 condensed in the refrigeratory g, and finally received into the closed vessel 
 h, where the operation is completed. 
 
 The engraving on p. 440 represents the patent distilling apparatus of Mr. 
 Stein ; in appearance it greatly resembles those constructed in France upon the 
 plan of Woolf's apparatus ; but the principle of its operation is totally dif- 
 ferent, the object being rather to cause a great economy in the consumption of 
 fuel, than to obtain spirits of any required strength at a single operation. The 
 heat absorbed in the conversion of a given weight of water into steam, exceeds 
 greatly that which is required to raise its temperature to the boiling point ; a 
 pound of water converted into steam raising six pounds of water to the point of 
 ebullition. The heat thus developed varies in different liquids, but is in all 
 cases considerable ; and as distillation is ordinarily conducted, this heat : s not 
 merely lost, but occasions a considerable additional expense, from the great 
 quantity of water required to reduce the vapour to the liquid state. To obviate 
 these two sources of loss, the patentee has contrived his apparatus, so that one 
 portion of liquid formed into vapour shall be reduced to the liquid form by 
 another portion of liquid, which is evaporated by the heat given out in the 
 condensation. But to convert a fluid into steam, not only a certain quantity of 
 heat is required, but the heat must also be of a certain intensity; thus, although 
 a pound of steam at 212, would raise six pounds of water to the boiling point, 
 it would convert no portion of it into steam, as the moment the water had 
 acquired the heat of the steam, it would receive no further portion of heat from 
 it ; but if the steam is formed under a pressure exceeding that of the atmosphere, 
 its heat, as indicated by the thermometer, is increased, and consequently it will 
 continue to impart heat to a liquid which has attained the boiling point under a 
 less pressure than the steam employed to heat it. Upon the combination of these 
 two principles, Mr. Stem's apparatus is constructed. Nos. 1, 2, 5, and 4, are 
 four oblong elliptical vessels or stills, two of which are shown in section ; the 
 lowermost halves are enclosed in casings a a, forming thereby steam chambers 
 b b; each still has a vertical pipe c cc c, terminated by a double passage cock 
 d d, one passage opening into the pipe e, which leads to the worm tub, whilst 
 the other opens a communication from one still to the steam case of the next 
 still, by means of the curved pipes fffi that from the still 1 leading to the 
 steam case of still 2, and so on in succession. The stills are charged from the 
 pipe g, the quantity admitted being regulated by the floats h ; each steam case 
 communicates by the pipes II 1 1 (which are furnished with cocks) with the pipe 
 k proceeding from the boiler. From the lower part of the steam case proceed 
 pipes in m ; that from still 1 leads to the cistern, which furnishes the steam 
 boiler with hot water, whilst the others may either communicate with one 
 common main , leading to a refrigerator, or they may each communicate with 
 a separate refrigerator. From the upper part of each steam case proceeds a 
 pipe (shown at 3 and 4) which communicates with a gauge pipe pp, and ter- 
 minates in a syphon barometer q q. rrrr are the man holes to each still ; 
 ssss the discharge pipes to the stills, the steam cases being emptied by opening 
 cocks in the pipes m m leading to th? main n. The operation is as follows : 
 The stills being charged, and the cocks d being open to e, the steam is admitted 
 to each case by the pipes 1 1 leading from the steam pipe k, and is rapidly con- 
 densed in the steam case, the air escaping by a pipe not shown in our drawing. 
 When the liquor in the stills has nearly attained the boiling point, the steam is 
 shut off from all the cases except that of 1 , and the cocks d are opened to the 
 pipes/, and the main n, being cleared of the condensed water, the cocks on m 
 of 2, 3, and 4 are closed. The steam from the boilers (which is under consider- 
 able pressure) continues to flow into the case 1 , and by the heat given out to 
 the liquor in the still, causes it to boil ; the vapour passes into the steam case
 
 440 
 
 DISTILLATION. 
 
 of 2, and the liquor in 2 condenses the steam in 1, until a common temperature 
 is attained ; then the steam from 1 being no longer condensed, and continuing 
 still to receive heat from the boiler, its pressure, and consequently its temper- 
 ature, increases, and it again gives out heat to the liquid in 2, which causes it 
 
 to boil 
 
 il. The vapour from 2 then passes into the steam case of 3, where the 
 process ensues, and which is subsequently repeated under the still 4, the 
 steam from which passes by the pipe e to the condenser. As soon as the 
 liquids in 2, 3, and 4 begin to boil, tae cock on m must be partially opened to 
 allow the condensed spirit to pass by the pipe n to the refrigerator ; yet always
 
 DISTILLATION. 
 
 441 
 
 retaining a certain portion in the steam case, the height of which may be 
 ascertained by the gauge pipe p, whilst the barometer q q will indicate the 
 pressure of the steam in each steam case. The proper pressures will be best 
 obtained by observation, as it will vary in different liquors during the distilla- 
 tion. The person conducting the process must, therefore, pay great attention to 
 the barometer; and to enable him to do this with facility, the gauge pipes and 
 barometer are all ranged in a cluster at the centre of the apparatus. By this 
 mode of distillation, it will be seen that the latent heat of three-fourths of the 
 liquid evaporated is saved, which produces a corresponding saving in the article 
 of condensing water. 
 
 In Mr. Williams's apparatus for distillation, for which he obtained a patent 
 about the year 1821, the improvements projected are comprised under the 
 following heads ; viz. an enlarged capacity of the still head, to cause a separa- 
 tion of the aqueous vapour by condensation, previous to its passing over the 
 neck of the still into the spirit condenser ; in the employment of numerous 
 small vertical tubes, surrounded with cold water, to increase and accelerate the 
 condensation ; in the adaptation of a peculiarly constructed " cooling worm," 
 by which it is conceived the quantity of spirit will be increased, by preventing 
 evaporation in its progress to, and when in the receiver ; and in the employ- 
 ment of refrigerating saline mixtures, for the more effectual cooling of the spirit 
 
 in warm climates, or in warm weather. In the body of the still (that part 
 where the vapour is generated) there is no improvement proposed, but an 
 enlarged capacity of its globular head, to cause the watery particles to fall back 
 into the still ; this part of the apparatus we have omitted in our diagram, as 
 it requires no additional explanation ; the engraving, therefore, relates wholly 
 to the apparatus for condensation, a is the termination of the neck of the 
 still, which conveys the vapour into the " upper drum " b, whence it is divided 
 among a number of small vertical tubes c, which the patentee says, should not 
 exceed three-fourths of an inch in their interior diameter. As the tub inclosing 
 this apparatus is filled with cold water, the condensation immediately com- 
 mences in the upper drum, and is completed in its subsequent progress through 
 the vertical tubes, aud the "lower drum" d. From thence the fluid runs
 
 442 DISTILLATION. 
 
 down a central neck e into the trap /, from the upper part of which trap it 
 enters the cooling worm b. It is evident that the trap f is, in working, always 
 partly filled with liquid ; and the neck e being immersed therein, any vapour 
 which may have escaped condensation can pass no further. The trap / has a 
 funnel-shaped bottom, from which a pipe h passes through the coils of the 
 worm, and through the side of the tub, where it is furnished with a cock for 
 the purpose of drawing off any impure spirit which may be separated from 
 the wash in the first stage of the process, and to discharge what may remain 
 in the trap when the process is over. To the trap f is also attached another 
 jiipe i, called the safety pipe, for the purpose of allowing the egress and ingress 
 of atmospheric air from and to the condenser, to prevent both pressure and 
 vacuum therein. The coils of the cooling worm are made octangular : the 
 worm itself is made flat, and of considerable breadth ; a transverse section of 
 it is exhibited in the separate figure k, which shows it to be in the form of a 
 parallelogram, whose longest sides are four inches, and its shortest half an inch 
 wide. This octangular worm, after making six complete turns, assumes a cir- 
 cular shape, and diverges off to pass through the side of the tub ; at its end 
 outside the tub, which is made a little tapering, is fitted, and is to be occasion- 
 ally applied, a crane-necked pipe I, which pipe may be elevated or depressed at 
 pleasure, for the purpose of keeping three or more of the coils of the worm full 
 of liquid. This crane-necked pipe is intended to be applied in hot weather, or 
 hot climates, to cool the spirits more effectually, and prevent their evaporation, 
 by subjecting the same in a greater degree to the effect of the cold water in 
 the worm tub. An additional apparatus, to be used in hot climates, of un- 
 doubted utility, is likewise recommended by the patentee, and claimed by him 
 as his invention. It consists of another pipe m, into which the discharging 
 end of the crane-necked pipe is made to enter ; and which pipe, after passing 
 the end of the trough n, is made of a very bread, flat shape, and running the 
 whole length of the trough (which may be of any extent) ; it is then to return 
 by a very slight descent, so as to run back very gently into the funnel of the 
 pipe which conveys it into the receiver. The trough n is to be filled with 
 Glauber's salts and nitre, or any saline mixture capable of producing intense 
 cold, for the more effectual cooling of the spirit. The trough may be placed 
 upon wheels and axles, for the convenience of bringing it to and conveying it 
 from its required situation. 
 
 Distillation is very commonly practised in India ; and although the apparatus 
 is of the most simple (not to say rude) description, the products are generally 
 of such excellent quality as to render the process deserving of the consideration 
 
 of the British manufacturer to discover the cause. The still commonly used 
 by the natives of Ceylon is represented in the above cut. It is constructed
 
 DISTILLATION. 
 
 445 
 
 wholly of earthenware, excepting the tube of communication between the 
 alembic and the refrigeratory, which is of bamboo. 6 is the body (or boiler) 
 of the still ; a is the capital, luted with clay to b ; c is the bamboo tube, which 
 conducts the vapour into the receiver d, where it is condensed by being 
 immersed in the vessel of cold water e. It is with this rude apparatus, 
 (according to Dr. Davy,) that the Singalese distil in the open air that fine 
 spirit arrack, which is obtained from toddy, the fermented juice of the cocoa 
 nut. 
 
 The editor of the present work, having a few years back had his attention 
 called to the state of the arts and manufactures in Ceylon, and of the implements 
 connected therewith, with a view to the improvement of the same, published 
 a series of papers on the subject, in a periodical work which he at that time 
 conducted, suggesting such alterations as seemed to him practicable with the 
 simple means and resources at the disposal of the natives ; and the Ceylonese 
 still, just described, appearing to him to possess considerable merit, he proposed 
 the following modification of it, in which, whilst the best features of it are 
 retained, it is rendered in some respects more efficient, fuel and labour are 
 economized, and by a simple method of combining several small stills, an 
 apparatus is constructed adapted to operations on a more extended scale, aaaa 
 
 are the heads of a series of earthen boilers, of the kind described above, 
 but instead of being exposed to the air, they are set in a close furnace b l>, 
 built of clay, or of the same materials with which their pottery is formed. This 
 furnace is proposed to be built in a circular form, to any convenient extent, so 
 as to surround wholly or partially the other parts of the apparatus ; it is for 
 this reason shown in the drawing as broken away, after being extended suffi- 
 ciently to allow of five vessels being fixed therein. The curved figure of the 
 furnace is given to it chiefly with the view of affording a convenient means of 
 connecting the bamboo tubes which conduct all the vapours from the several
 
 444 
 
 DIVING APPARATUS. 
 
 stills into the cylinder d. This cylinder is' fixed firmly in a closed vessel e, 
 which serves both as a recipient for the condensed liquid, and as an enlarged 
 chamber for the vapours. On one side of the cylinder d there is an oblong 
 aperture, made longitudinally for the egression of 
 the vapours, which is covered by a liglit piston, so 
 that when the vapours have attained but a very little 
 more elastic force than is sufficient to overcome the 
 pressure of the atmosphere, this piston is lifted, which 
 uncovers the aperture to a certain extent, and per- 
 mits the vapours to pass through a large bamboo tube 
 of communication into a thin metal refrigerating 
 box I; this metal box is supported by a strong tube 
 o, fixed into the close recipient p, the tube being 
 open to both. On the top of the cylinder is fixed 
 a vertical standard, the upper end of which be- 
 comes the fulcrum to a lever crank t. To one end 
 of this crank is jointed a rod or stout wire, which 
 connects it to the handle of the water valve k ; the 
 other arm of the crank lever passes between anti- 
 friction rollers on the piston rod h. It will be mani- 
 fest by this arrangement, that in exact proportion to the volume of vapour 
 that escapes from the cylinder, will the precise quantity of water necessary to 
 condense it be showered down upon the refrigeratory ; and this is done 
 uniformly and according to circumstances, without any attention on the part 
 of the distiller. By the elevation and 
 depression of the piston rod k also, 
 the long arm r of the lever crank 
 may, by means of a cord s, be made 
 to open a sliding door or damper to 
 the furnace, by an arrangement for 
 this purpose omitted in the rough 
 sketch. As it is objectionable to leave 
 the still-heads exposed to the air, by 
 which a portion of the vapour be- 
 comes condensed and runs back into 
 the still, it is proposed to enclose them 
 with a cap of wood or pottery, like that 
 delineated in the margin above, which 
 will envelope them in a heated atmo- 
 sphere. To prevent the escape of the 
 heat through the clay walls of the 
 furnace, they are made double, with a 
 stratum of charcoal between, as repre- 
 sented in the annexed sectional view, 
 in which a a represents the strata of charcoal imbedded in the surrounding clay; 
 b the boiler ; c the head, luted to the boiler enclosed in the box d, through an 
 aperture in which the neck e passes, that conducts the vapour to the cylinder ; 
 the cavities round the boiler // are for the heated air, and g the hearth, on 
 which the wood is thrown at one end of the furnace. 
 
 DIVING APPARATUS. Contrivances for the purpose of enabling per- 
 sons to descend and to remain below the surface of the water for a great length 
 of time, to perform various operations, such as examining the foundations of 
 bridges, blasting rocks, recovering treasure from sunken vessels, &c. The appa- 
 ratus most commonly employed for this purpose is the diving bell, the invention 
 of which is generally attributed to Dr. Halley. These machines have been 
 variously modified, but are now ordinarily made in the form of an oblong 
 chest, open at the bottom. It is made of cast iron of considerable thickness, 
 and has several strong convex lenses set in the upper side or roof of the bell, 
 to admit light to the persons within. It is suspended by chains, hooked to 
 strong staples in the upper part of the bell, and which chains are passed round
 
 DIVING APPARATUS. 
 
 415 
 
 a windlass supported upon the sides of two lighters or barges, so that the bell 
 can be raised or lowered, upon signals to that effect from the persons within the 
 bell, who are supplied with fresh air by means of a flexible hose passing under 
 the lower edge of the bell, and connected with a set of forcing pumps placed 
 in the barges. The air which has been respired being heated, rises to the 
 upper part of the bell, whence it escapes bv a cock An apparatus has also 
 been devised to enable a person to quit the diving bell, and remove to a con- 
 siderable distance when requisite, and still to receive the necessary supply of 
 air. It consists of a copper helmet, fitting water-tight to the shoulders of the 
 wearer, and furnished with a mouth piece, to which is attached a flexible hose, 
 reaching under the bell ; but recently a patent has been obtained by Mr. W. H. 
 James for a somewhat similar apparatus, by which a diver can carry on the 
 necessary operations independently of a diving bell. The diver is attired with 
 a portable vessel (placed around and adapted to the figure of his body,) which 
 is filled with condensed atmospheric air ; and by means of a simple arrange- 
 ment of pipes, and judiciously constructed valves, he is enabled to supply him- 
 self with fresh air for respiration during the time he is under water. In the 
 
 two accompanying figures, the letters in each refer to the same part?,. Fig. 1 
 gives a front view of the diver fully equipped in the nppara'as, and supposed wJ
 
 416 
 
 DOCKS. 
 
 be engaged in recovering from the deep a variety of sunken property ; and 
 Fig.2 gives a section on a larger scale, for the better understanding of the 
 several parts. A is the vessel to contain the 
 condensed air, which is to be filled by means 
 of a condensing air-pump ; it consists of a 
 series of strong metallic tubes, or of one con- 
 tinuous tube, coiled elliptically round the body, 
 and connected together by bands, to which 
 straps are attached to secure it in its position. 
 At a is a valve opening inwards, through which 
 the air is to be forced by means of a condensing 
 pump, until it has acquired the required degree 
 of density, which will, of course, be determined 
 by the time it is proposed for the diver to remain 
 under water. B is a tube made of caoutchouc 
 (or Indian rubber), for conveying the air into 
 the water-tight helmet C, by means of a valve 
 so contrived as to be completely under the 
 control of the diver. This helmet may be 
 made of any water-tight material, but thin 
 copper is recommended ; it is provided with a 
 strong plate of glass in front, to enable the 
 diver to see surrounding objects Inside the 
 helmet is a flexible tube c, with a mouth-piece 
 at the end, which comes near to the mouth of 
 the diver; through this the air is discharged 
 from his lungs, and passes out through a valve 
 d in the top of the helmet. At the lower part 
 of the helmet, and round the breast, back, and 
 shoulders, a water-proof garment e is attached, 
 fitting closely round the body of the wearer, 
 and made fast by elastic bandages /. To 
 
 secure the diver from being inconvenienced by the pressure of the air within 
 the helmet becoming too great, a safety-valve is introduced. Notwithstanding 
 the weight of the apparatus (amounting perhaps to 50 Ibs.), the density of the 
 water at great depths would render the body of the diver too buoyant to keep 
 on his legs and execute his work ; in these cases it will become necessary to 
 attach weights to his person, capable of being easily removed, if desired ; 
 some are therefore shown in the figures as attached to the apparatus ; these, 
 however, it may be desirable to place lower down his person, about his legs and 
 feet. The same apparatus (divested of the weights) may be employed with 
 safety and advantage in mines and other places filled with deleterious 
 ga<es. 
 
 DOCKS. Enclosed excavations or basins, formed for the reception of 
 shipping. There are two descriptions of docks, viz. wet docks, and graving or 
 repairing docks. Wet docks are extensive basins formed adjacent to rivers and 
 harbours, with which they are connected by means of a lock, furnished with 
 gates at each end, so that vessels remain afloat at all times of the tide. They 
 are usually surrounded with warehouses, for the purpose of loading or dis- 
 charging vessels. The wet docks in this country are numerous and extensive, 
 and have proved highly beneficial to its commercial interests; as in these 
 ships lie in perfect security from storms and depredation, their cargoes are 
 taken in and delivered with the utmost dispatch, and the navigation of the 
 rivers is freer from obstruction. The town of Liverpool, which, from the 
 badness of its harbour, resorted to the construction of wet docks it 1708, has 
 at the present day a range of them in front of the town, and along the banks 
 of the river Mersey, extending more than two miles in length, and which, from 
 their concentration in one spot, form the most striking display of the kind that 
 can any where be met with. Hull, Bristol, and Leith, have successfully emu- 
 lated this example. Although London was without the conveniences of wet
 
 DOCKS. 4-17 
 
 docks until the commencement of the present century, it can now hoast of 
 several, some of which exceed in magnitude any in other parts of the kingdom. 
 The first of these undertakings was the West India Docks, for the accommodation 
 of the West India trade, erected under an Act of Parliament passed in July, 
 1799. The great basin is 420 yards in length, and~230 yards in width, covering 
 an area of twenty acres. A basin of nearly three acres connects it with the 
 river. The warehouses are most noble buildings ; the tobacco warehouse is 
 the most spacious erection of the kind in the world, being capable of containing 
 25,000 hogsheads of that article, and the vaults underneath, as many pipes of 
 wine. This single building under one roof is said to occupy upwards of four 
 acres of ground. These docks were opened in 1805. The London Docks were 
 begun in 1 800, and completed in 1 805. The principal basin is 420 yards in 
 length, ajid 276 in width, giving an area of 25 acres. The principal range of 
 warehouses occupies a superficies of 120,000 square yards. The first stone of the 
 East India Docks was laid in March 1825, and the first vessel entered them in 
 August 1826. The dimensions of the dock for unloading inwards are 1410 
 feet in length, and 560 in width ; the dock in which vessels load outwards is 
 780 feet long, and 520 feet wide ; and the entrance basin, which connects them 
 with the river by a lock, is 2J acres in extent. The lock is 210 feet in length, 
 the width at the gates 48 feet in the clear, and the depth of water at ordinary 
 spring tides 24 feet. The warehouses at these docks are of trifling extent, the 
 principal part of the cargo of vessels unloading here being conveyed in vans 
 direct from the ships to the East India Company's warehouses, situated in 
 various parts of the city of London. Besides these principal docks just enu- 
 merated, there are various others in the port of London, which our limits will 
 not allow us to notice. 
 
 Graving or Repairing Docks are excavations sufficiently large to admit one 
 or sometimes two vessels for the purpose of being repaired. At the entrance 
 is a pair of gates, forming an angle outwards or towards the river. When it 
 is required to dock a vessel, the water is admitted by means of sluices, and 
 when it has attained the same level within the dock as without, the gates are 
 opened, and the vessel hauled in over a range of blocks previously laid on the 
 floor of the dock ; the gates are then shut, and the vessel, being steadied by 
 shores or props placed against the side of the dock, as the tide recedes, settles 
 upon the blocks. At low water the sluices are shut, and the water (if any) 
 remaining in the dock is pumped out, so as to leave it perfectly dry, and 
 to allow any part of the vessel's bottom to be examined and repaired. When 
 the soil is of an unfavourable nature for excavations, as also with a view 
 to avoid the delay which often occurs from ships being able only to enter some 
 repairing docks or to leave the same at the height of the springs, a contrivance, 
 called a floating dock, has been proposed, in which vessels may receive the 
 necessary repairs. Various constructions have been offered for this purpose. The 
 engraving on the following page represents a design for a floating dock, by Mr. 
 Edward Clark, of New York, civil engineer. This dock is proposed to be con- 
 structed by forming a float of timber to constitute the bottom of the structure, 
 and which, by its buoyancy, shall support a vessel within the dock with its keel 
 above the surface of the water. To attain this end the float is made in the form 
 of a hollow box, composed of strong logs firmly jointed together and caulked, 
 so as to render it water-tight. The capacity of the hollow part must be such 
 that, when exhausted of water by means of pumps, it shall be sufficiently buoyant 
 to sustain itself with its load, a represents the float ; b b the piers, forming a 
 recess to steady and secure the float ; c c perpendicular supports and braces 
 appended firmly to the piers ; d d also supports appended firmly to the float, so 
 as to allow by means of the rollers e e of the easy and steady ascent and 
 descent of the float conformably to the motion of the tides and waves, and also 
 of sinking and raising the float in the same place ; / the stern of the vessel ; 
 g g bilge blockings ; h h braces, all for supporting and steadying the vessel in 
 an upright position ; i timbers framed into the piers, forming a bed for the 
 support of the float while sunk. The float a is supplied with valves and pumps 
 (not shown in tlw >ngraving) ; and if it be required to float the vessel/, nothing
 
 418 
 
 DRAG SHEETS. 
 
 more is necessary than to open the valves, when the float, being previously 
 ballasted, will fill with water and sink to its bed. The vessel / being now 
 removed, and another made to occupy its place by means of guides, the valves 
 are to be closed, and the pumps put in motion, and when a quantity of water 
 has been displaced from the float equivalent to the weight, she will be elevated 
 entirely above the water, and placed in a most favourable situation to undergo 
 
 repairs. A float of this description, for use in sea water, would require to be 
 coppered externally, and occasionally to be filled with some other saline fluid, 
 or with fresh water, to preserve it from worms. The Committee of the Franklin 
 Institution at Philadelphia, to whom this invention has been submitted by 
 Mr. Clark, state, in their report thereon, that the main objection to docks of 
 this description, made sufficiently capacious for vessels of large dimensions, and 
 for the operations to be carried on in repairing them, is the unequal pressure to 
 which their bottoms must be subjected by the weight of the vessel upon them, 
 and the upward pressure of the water. They are aware that, by judicious 
 shoring, much of the weight of a vessel may be distributed over the bottom ; 
 this, however, although it would lessen the objection, would not remove it. 
 Ships, although constructed in a shape and braced in a manner calculated to 
 render them stable, undergo in nearly every instance a change of form after 
 they are launched ; to this change of form the float in question would be much 
 more liable, inasmuch as its flat surfaces are less calculated to resist the effects 
 of the pressure to which they are subjected. 
 
 DODECAGON. A regular polygon of twelve sides. 
 
 DODECAHEDRON. A solid, having twelve equal and similar sides or 
 faces, each of which is a regular pentagon. 
 
 DOVETAIL is a term implying a mode of connecting two pieces of wood 
 or other substance together by means of cutting their extremities into the form 
 of a dove's tail, and interlocking them so that they cannot be separated in the 
 direction of the strain without breaking the materials asunder. Sometimes a 
 solid piece dovetailed at each extremity is employed to connect two other 
 pieces or parts together, by entering morticed cavities in the latter. 
 
 DOUGH. The paste formed by kneading flour and water together in the 
 preparation of BREAD, which see ; also KNEADING. 
 
 DRACHM, or DRAM. A weight consisting of the sixteenth part of an 
 ounce avoirdupois, and the eighth of an ounce in apothecaries' weight. 
 
 DRAG SHEETS. The name given to a contrivance for lessening the drift 
 of vessels in heavy gales of wind, for which Mr. Burnett obtained a patent 
 in 1826. The current caused by the action of the wind extends but a
 
 DRAG SHEETS 
 
 419 
 
 few feet below the surface, even in the heaviest gales ; and if a body be sunk 
 to a considerable depth it will remain nearly stationary. Dr. Franklin, aware 
 of this fact, recommended vessels encountering adverse gales in the open 
 ocean, instead of lying to, to form a kind of floating anchor by attaching a 
 stout hauser to four bridles from the four corners of a sail, the corners being 
 distended by spars, and then lowering the sail into the sea with sufficient 
 weight to sink it. The effect of it will be considerable in retarding the pro- 
 
 gress of the vessel astern. Another well-known fact is, that any substance 
 floating upon the water, prevents, in a very great degree, the waves from 
 breaking ; and fishermen and sailors who have taken to the boats upon a 
 vessel, frequently make them fast with some scope of rope to a spar, 
 which they throw overboard, which breaks the force of the waves, and allows 
 the boats to ride in comparatively smooth water. Mr. Burnett's invention is a 
 combination of these two plans, as will be perceived from the annexed repre- 
 sentation of it. The upper figure represents the drag sheet, viewed a little in
 
 450 DRAINING. 
 
 perspective ; a is a plank hollowed out underneath, so as to form a cavity or 
 sufficient dimensions to receive the remainder of the apparatus when rolled up. 
 When in use, this plank forms the float for the rest of the apparatus ; appended 
 to it, and sunk in the water 6, is a circular bar or rod of rnetal, firmly fixed at 
 the extremities to the float, within the cavity before mentioned ; round this 
 bar the upper side of a square piece of sail-cloth c is fastened ; the lowermost 
 side is in like manner secured to another metallic bar or roller d; the ex- 
 tremities of d are formed into rings or eyes, which are thereby hung upon 
 hooks attached to the uppermost bar b; a series of eye-hooks, like the one 
 shown in the margin (at i) sliding upon the 
 rods / are then employed to stretch the can- 
 vass c tightly out between them. The frame 
 thus completed, a rope or chain is attached to 
 each comer of it ; one from e to g on the one 
 side, and another chain in the same manner 
 on the opposite side; both these pass through a 
 ring h, as represented, which ring is attached 
 to a hauser or cable, that is made fast to the bow of the ship. By this 
 arrangement the heaving of the vessel, or of the drag, by the undulatory 
 motion of the waves, allows the ring to traverse up and down the chains, pre- 
 serving thereby the perpendicularity of the drag, and consequently producing 
 the utmost resistance to its passage through the water. 
 
 DRAGON BEAMS are two strong braces, supporting a breastsummer, and 
 meeting each other on the shoulder of the king-post. 
 
 DRAGON'S BLOOD. A red coloured resin, imported from the East Indies. 
 It is insoluble in water, partially so in alcohol, but dissolves readily in oils : the 
 solution imparts a beautiful red stain to hot marble. 
 
 DRAINING, in Agriculture, the process of drawing off the water from 
 bogs, marshes, and lands liable to be flooded by excessive rains, by means of 
 drains or trenches cut to some depth below the surface, which drains serve to 
 collect the waters and convey them off to some lower level. Until the middle 
 of the last century little attention was paid to the draining of lands. The first 
 person who treated the subject systematically appears to have been Dr. J. 
 Anderson, of Edinburgh, who showed that the origin of swamps and morasses 
 lay in the waters, attracted from the atmosphere by the summits of hills and 
 mountains, percolating through the various porous strata of which they are 
 composed, until they arrive at a stratum of clay, which, being impervious to 
 the waters, they stagnate and accumulate, until by their increasing upward 
 pressure they force their way through the soil of the valleys and lowlands at 
 the foot of the hills, and form bogs and marshes. The principle of his system 
 of drainage consists in intercepting the waters in their progress below the 
 surface from the hills to the low grounds, by a trench running along the base 
 of the hill, and extending to the substratum of clay, which impedes the progress 
 of the water; from this trench a drain is cut, to convey the waters to the 
 nearest channel that will carry them away. Mr. Elkington, about the same 
 period, appears to have paid great attention to the subject in England, and for 
 various improvements which he introduced in the practice, received from Par- 
 liament the sum of 1000/. In cases where the top soil is of considerable depth, 
 and no water therefore rises into the ditch, after cutting five or six feet down, 
 both Mr. Elkington and Dr. Anderson recommend to bore with a proper auger 
 until the clay be reached, when the water will rise through the holes into the 
 trench. These trenches should be made narrower as they descend, by spades 
 of a proportionate size, but the lowest part ought to be more contracied than 
 any other, so that the shoulders or edges of it may support stones or faggots, 
 in order to cover the whole at a small expense without obstructing the currents 
 of water. In many places hollow bricks or ridge tiles are substituted for stones 
 or faggots, as being cheaper. When the land to be drained consists of a long 
 level tract, without sufficient fall to carry off the water from the reservoirs or 
 pits into which it is conveyed by the drains, or when there is a rising ground or 
 an embankment between the drained land and the level which is to convey the
 
 DRAINING. 
 
 451 
 
 water off, it must be elevated mechanically ; for this purpose pumps, driven by 
 windmills, are very extensively employed in Lincolnshire. Where there is 
 sufficient outfall, water may also be conveyed over an intervening obstacle by 
 
 means of a syphon, provided that the height of the syphon do not much exceed 
 20 feet ; but one objection to this method consists in the interruption to which 
 the action of the syphon is liable, from the extrication of the air which all
 
 452 DRAWBRIDGE. 
 
 common water contains, and which begins to separate from that fluid as it risjs 
 under diminished pressure in the short leg of the syphon, till at length the 
 angle of the syphon is filled with air, and the current of water is interrupted. 
 To remove this defect, Mr. Cowen, of Carlisle, places a box at the upper angle 
 of the syphon, into which all the ai' separated from the water rises ; and the 
 application of a forcing pump for a few minutes once or twice a day drives the 
 air out of the box into the atmosphere. Fig. 1 represents Mr. Cowen's plan 
 applied to the draining of a quarry, a a represent a part of the quarry ; b a 
 'evel lower down than the bottom of the quarry, which, in this case, is 200 
 yards off where the water is to be discharged; c the highest ground over which 
 the water is to be conducted; d, e, and/, three distinct rises, over which the 
 pipes pass (they are further apart than here shown) ; g g h h the lead pipe, 
 composing the two legs of the syphon ; i a common forcing pump, fixed below 
 the surface of the water, having a hinge valve atj, Fig. 2, and an open working 
 box, with a similar valve Jc. These valves are opened by the force of the water 
 flowing through the pump in its passage to the syphon ; / the working handle 
 of the pump ; m is a close iron receiver, shown larger in Fig. 3, having inserted 
 at the end n the ascending leg of the syphon g, and at the other end o the 
 descending leg h ; at the upper side of both ends are inserted two small air 
 pipes p p, joining with the syphon pipe at t'ue highest bends, as shown at d, e, 
 and/, with a regular slope into the interior, to allow the air to ascend into it; 
 g is a small valve fixed at the highest point of the receiver, to allow the whole 
 of the air to escape through the valve when the water is forced up by the 
 pump ; for this purpose the pump i and the pipe g must be capable of supplying 
 the water quicker than the pipe h will carry it off. 
 
 Directions to be observed in laying the syphon to suit different situations. 
 First, in laying the pipes of the syphon, it is necessary to give them a regular 
 slope, to admit the air to pass forward into the receiver, or to the highest bends, 
 which must have either an air receiver to each bend, or a pipe inserted to 
 convey the air to a general receiver. Second, when sufficient descent can be 
 obtained on both sides from the air receiver, no air pipes will be required. 
 Third, in situations where it may be necessary to carry the pipes over more 
 (nan one elevation, and the second exceeds the height of the first, a separate 
 receiver will be required for each elevation. On this construction, viz. with 
 more than one receiver, it is necessary to adopt the following expedient for 
 closing the valves in succession as the air is expelled from each receiver. Fig. \ 
 is the lower valve in the receiver s, which is opened by the force produced by 
 pumping, and the air escapes ; t is an inverted valve, with a float v fixed upon 
 the valve spindle in the centre of the cup u. While the air only is expelled, 
 the inverted valve will remain open ; but when the water is forced out and fills 
 the cup, the float will rise and close the valve at the same time; thus the 
 water being stopped from flowing out, will be forced forward to any number of 
 receivers in succession, w is a very small outlet pipe, inserted into the bottom 
 of the cup u, through which the water escapes slowly ; as the cup is emptied 
 the float is lowered, and the inverted valve again opened a position necessary 
 to allow the air to escape at the next pumping. Another method for closing 
 the valve is shown at Fig. 5. q is a valve placed in a cup, as shown in Fig. 1 ; 
 on the cup is mounted a lever, with a counterweight x at the one end, and a 
 small pendant receiver y at the other end ; z is a conducting tube inserted into 
 the edge of this cup, to convey the overflowing water into the receiver, which, 
 as it fills, loads the valve and prevents the escape of the water, and thus forces 
 it forward, as before described, to any number of receivers. The preceding 
 account of this valuable improvement in the art of draining, by means of the 
 syphon, is extracted from the original description of it by Mr. Cowen, in the 
 Transactions of the Society of Arts, for the communication of which the Society 
 awarded him the gold Vulcan medal. In the 45th volume of the Transactions 
 ire some interesting details of his experiments. 
 
 DRAUGHT. The depth of water necessary to float a ship or other vessel. 
 For the draught of carriages, see RESISTANCE. 
 
 DRAWBRIDGE. A bridge thrown over a ditch or ravine, which may be
 
 DRILL. 
 
 453 
 
 drawn up or let down at pleasure, one of its ends serving as an axis or joint 
 for that purpose, while the other is connected by means of chains to two strong 
 levers, called plyers, which are framed together with other timbers in the form 
 of a cross, and are supported by two jambs, on which they swing. Bridges of 
 this kind are most common in fortresses, to cut off communication with the 
 surrounding country. In canal navigation, and in wet docks, swing bridges 
 that turn horizontally upon one end as an axis have almost wholly superseded 
 drawbridges. 
 
 DRIFT, in Mining, a passage dug under the earth, betwixt shaft and shaft, 
 or turn and turn. 
 
 DRIFT, in Navigation, the angle which the line of a ship's motion makes 
 with the nearest meridian, when she drives with her side to the winds and 
 waves, and is not governed by the power of the helm. It also implies the dis- 
 tance which the ship drives on that line. 
 
 DRILL. An instrument for boring holes in metals and other hard sub- 
 stances. It usually consists of a straight piece of steel, one end of which is 
 formed into an angular point, and the other into a blunted round point, for 
 inserting into a hole in a steel breast-plate, which is worn by the workman 
 whilst operating with the instrument, in order that he may ste'adily press the 
 point into the work, while he, at the same time, turns it backwards and for- 
 wards by means of a bow and cord, the latter being passed around a small 
 pulley fixed about the middle of the drill. Sometimes drills are fixed to braces 
 or stocks for the purpose of drilling. For boring large holes in metal, smiths 
 
 and engineers ' : " 
 
 pressure to the 
 
 joined cut. a b is a lever of the second 
 class, whose fulcrum is at a / the weight 
 being applied at b, its efficacy is trans- 
 mitted to the point c, in a ratio propor- 
 tioned to the relative distances between 
 b c and e a. As the pressure upon the drill 
 often requires relieving, a lever de is 
 added, whose fulcrum is at /. The ex- 
 tremity of the shorter arm is connected 
 to the lever a b by any convenient 
 method ; and when the workman wishes 
 to release the brace g, he applies lu's 
 power to the extremity of the longer arm 
 by pulling down at </, which raises the 
 shorter arm, and with it the lever ab, 
 consequently the brace g is at liberty to 
 be removed. In order that the work 
 may be firmly fixed, it is usual to screw 
 it fast between the chaps of a vice, as 
 shown at o I m n in the cut. 
 
 The annexed cut represents an ex- 
 tremely simple and ingenious contrivance for drilling holes, used by the smiths 
 in Ceylon. It is about two feet and a half 
 
 igineers employ a very convenient arrangement of levers for applying 
 re to the drill, which is called a press-drill, and is delineated in the sub- 
 
 the cord attached to the 
 
 cross sticks is made of slips 
 of hide twisted. The round 
 weight to give momentum is 
 of compact neiss, neatly cut. 
 Any kind of borer can be 
 fixed to the extremity of the 
 wooden rod. The instal- 
 ment is worked on the prin- 
 ciple of torsion. The hole 
 in the cross arms or handle, 
 through which the spindle 
 of the drill passes, is suffi- 
 
 3 M
 
 v,4 DRY ROT. 
 
 ciently large to admit of it being slided easily up and down the spindle. Upon 
 turning the cross a few times round the spindle, the cords become twisted in a 
 corresponding degree round its upper part, and upon pulling the cross down- 
 wards, the cords in untwisting impart a rotatory motion to the spindle, which, 
 by the impetus which the weight upon it acquires, is continued after the cords 
 have become straight ; and the cross being then slided up the spindle, the cords 
 become twisted round it in a contrary direction ; and by again depressing the 
 cross, the spindle revolves the reverse way. 
 
 DRILL, in Gardening and Agriculture, a small trench made in the ground, 
 for sowing in it the seeds of vegetables. 
 
 DRILL HARROW. A small harrow employed in drill husbandry, for 
 extirpating weeds, and pulverizing the earth between the rows of plants. 
 
 DRILL HUSBANDRY. A mode of cultivation in which the sowing of 
 seeds in drills is adopted, instead of the more common method of broad casting. 
 It is also called horse-hoeing husbandry, because the plants thus cultivated in 
 rows admit being cleansed from weeds and earthed up by a machine drawn by 
 one horse, and therefore called a horse-hoe. A great variety of machines are 
 employed in this branch of agriculture. See PLOUGH. 
 
 DRUG. A general name of commodities brought from abroad for the pur- 
 poses of medicine, dyeing, tanning, and various other arts. 
 
 DRUG MILLS are machines used for trturating drugs; but as they are for 
 the most part applicable to the grinding of other substances, they are described 
 under the general head of MILLS. 
 
 DRUM. A martial musical instrument in the form of a cylinder, hollow 
 within, and covered at the two ends with vellum, which is stretched or slack- 
 ened at pleasure, by means of cords with sliding knots. The cylinders are 
 usually made of wood, but sometimes of brass. Kettle-drums are large basons 
 or hemispheres of copper or brass, covired on their flat sides with vellum, 
 which is fastened to the peripheries by circular rims of metal, provided with 
 tightening screws for tuning them ; they are usually played upon in 
 pairs, and are chiefly used in the musical bands of cavalry regiments, or in 
 oratorios, operas, &c. 
 
 DRUM is a term in machinery, applied to cylinders or barrels, around which 
 endless straps, chains or cords, are passed, to communicate motion or power to 
 other mechanism. When cylinders so employed are narrow in the direction of 
 their axes, they are usually denominated pulleys or riggers. 
 
 DRY ROT. A term applied to that rapid decay of timber by which its 
 substance is converted into a dry powder, which issues from minute tubular 
 cavities resembling the borings of worms. On the causes of this decay numerous 
 volumes have been written, and nostrums for its prevention or " cure" have 
 been proposed without number, yet the dry rot continues to ravage our houses, 
 and to destroy our ships. It has been said that moist and warm situations, 
 where the circulation of the air is impeded, is the generating cause of this 
 disease, and that the effluvia from timber so diseased will carry its effects to 
 the circumjacent timber ; and that any sort of wood, dry as well as damp, so 
 exposed, will be soon destroyed. Timber once infected cannot be restored, 
 and the only remedy lies in cutting away the diseased parts, to prevent the 
 extension of the evil to the remainder ; and to effect even the latter a free 
 circulation of air must be admitted, and the parts be washed over with a strong 
 solution of iron, copper, or zinc. Patents have been granted for various 
 applications of the latter, as preventives of the dry rot, the distinguishing 
 features of the processes therein employed consisting in first preparing the 
 timber by a good steaming, or drying out of the sap, and afterwards injecting, 
 s/>akin.sr. or boiling the timber in a solution of copperas, or other metallic salt. 
 The following observations on this important subject were some time since 
 addressed to the editor by Mr. John Gregory, who is an experienced and 
 observant shipwright ; and as they appear to mark out clearly the true cause 
 of, and to suggest a very simple remedy for, the evil, it is right to give them a 
 place in this work. Mr. Gregory says, " Instead of squaring a piece of timber 
 according to the usual method, by leaving the heart of the tree in the centre.
 
 DRY ROT. 455 
 
 my plan is to saw it light down the middle, through the heart, into two equal 
 parts, immediately after the tree is felled ; and my reasons for this I will now 
 endeavour to explain to the best of my ability. It is, I believe, a well-known 
 fact, that a tree does not, literally speaking, die on receiving the final stroke of 
 the axe, but that it continues for a long period afterwards to vegetate, though 
 less vigorously. At length, however, the sap ceases to circulate, the pores 
 become closed, and the juices of the tree thus shut up undergo decomposition, 
 and lay the foundation of dry rot. It is well known that a man who dies in a 
 full habit of body soon decays ; the same effect takes place in a tree full of sap, 
 unless we adopt the same method with respect to it as the Egyptians practised 
 with the human body, viz. that of depriving it of all moisture, which process 
 would give to our timber a durability almost everlasting. My mind has been 
 long impressed with this idea, which has been confirmed by my having recently 
 noticed that several of the timbers in a very ancient public building, which had 
 been sawn originally in the manner I have proposed, were perfectly sound, 
 although they had withstood the dilapidating hand of time for seven hundred 
 years ; while other timbers in the same building, which had not been so cut, 
 but apparently squared out with the heart in the centre, were perfectly rotten 
 That the dry rot is certainly caused by the juices being enclosed in the heart of 
 the timber, I have had frequent opportunities of observing during my long 
 practical experience in the repairing of ships. In the frame of a ship in which 
 such large quantities of timber are employed, I have uniformly noticed, First, 
 that the decay commences in the run fore and aft, which is owing to the timbers 
 being fitted so close together at the heels or lower ends. The evil being thus 
 enclosed in the hearts of the timbers, and the air having no access to the 
 exterior of fliem to carry off the moisture by evaporation, internal decay is the 
 necessary consequence. I have sometimes witnessed these parts of the frame 
 of a ship in such a rotten state as to have been justly compared by the workmen 
 to a heap of manure. Secondly, those timbers in the midships that have been 
 bored off with the outside planks are not so affected, which I attribute to the 
 circumstance of the holes admitting a current of air through them, the destructive 
 juices being thereby carried off. Thirdly, it frequently happens that the floor ' 
 timbers of an old ship are found, on breaking up, to be nearly as sound as they 
 were when first put in. Their preservation seems to be owing to the effect of 
 the salt water which constantly laves over them, causing them to become in a 
 manner pickled ; or it may be, that the salt entering into the composition of the 
 wood, the destructive effects of its natural juices are thereby prevented. Fourthly, 
 the planks in the bottom, nearest to the timbers, take the infection first ; and 
 where the tree-nails are not close, the disease rapidly extends endways of the 
 grain. Fifthly, those parts of the deck planks that lie upon the beams are 
 those which are first infected with the rot, the cause of which is evident, as 
 those parts that are between the beams are generally quite sound. Sixthly, in 
 the beams of ships the decay usually commences in the internal parts, which is 
 decidedly owing, in my opinion, to the erroneous method of preparing the 
 timber, as before mentioned; but when timber, so prepared, is used, I would 
 recommend, as the best preventive of the rot, that a few holes be bored through 
 the beam fore and aft, and, what would still add to the benefit, to bore another 
 hole lengthways of the grain, to meet those which are bored crossways. But 
 the best preventive, I am confident, would be the adoption of my mode of 
 preparing the timber, namely, to saw it lengthways right through the heart, by 
 which not only much greater durability would be obtained, 
 but great economy in the consumption of the timber, as well 
 as a great increase of strength, which I will proceed to ex- 
 plain by reference to the annexed figure, which exhibits an 
 end view or section of a piece of timber. Having procured 
 a log of the shape required, first cut off the two slabs b b, 
 and then divide the remainder a a into two equal parts. 
 Being thus sawn through the heart, the air will rapidly 
 absorb the juices, and such a seasoning may be soon effected 
 as will, I have no doubt, completely prevent the dry rot. But my object in
 
 436 
 
 DRY RO1. 
 
 this place is to show the economy of the plan in a mechanical point of view. By 
 thus sawing a log through the middle, two timbers are immediately provided 
 instead of one, and both of one precise mould. Thus when the pieces a a in 
 the above figure are placed end to end, they will form two timbers exactly 
 similar, as appears by the annexed figure. The expedition gained by this 
 method of converting timber is 
 . obvious ; every ship-builder is 
 fully sensible of the difficulty 
 he is often put to, and of the 
 sad waste of time and labour 
 often incurred in preparing two 
 such timbers to match one another. It not unfrequently happens that the 
 framing of a ship stands still for several days owing to this circumstance. The 
 saving of time and labour is in consequence an important saving in the expense 
 of building. I have also proved by experiment that this mode of sawing the 
 timber down the middle confers great additional strength. From the same 
 bough I cut two pieces of the same length and thickness ; one of them I squared 
 according to the usual plan, which I condemn, the other, according to my prc- 
 posed method, leaving the circular sides, as shown at a a in the foregoing 
 figures. The proportional strength of only one of the pieces I found to be as 
 25 compared to 27, the strength of the whole square timber ; the strength of 
 the two pieces, therefore, makes the difference of 50 to 27, or nearly double ; 
 in addition to which advantage, far greater durability will be obtained by the 
 prevention of the dry rot. For the timbers of a 74-gun ship, logs of 22 inches 
 diameter are usually employed ; if these, instead of being squared, are divided 
 according to my method, their strength and width of bearings for the planks 
 will be fully adequate, and the little difference of strength may be easily com- 
 pensated by two or three more timbers, for which there will be plenty of room, 
 and the saving of expense will thereby be immense. By the most accurate 
 calculations that I have been enabled to make, I find the saving in timber only 
 to be full one-third. The annexed sketch represents a horizontal section of 
 a small portion of a ship's side, with 
 the arrangement of the timbers accor- 
 ding to my plan, a a a, three of the 
 ship's timbers ; b b b b, the fittings 
 made from the slabs before mentioned, 
 which are uniformly of a suitable 
 shape ; c c are air passages, which 
 serve effectually to carry off whatever 
 moisture may remain in the timber, 
 
 the hearts of the trees being exposed to the air. It will likewise be perceived 
 that the circular form of the grain being retained, the strength of the timber 
 is better preserved than if the logs were squared, as I have proved by the 
 before-mentioned experiment. From long observation and repeated investigation 
 I am indeed convinced that the outside, or younger part of a tree, is stronger, 
 more durable, and more seaworthy, than the heart, notwithstanding I have 
 daily witnessed the preference given to the latter, while the former has been 
 used for fuel. In the repairing and breaking up of ships, it will be almost 
 invariably found that the decayed planks have the heart of the tree, and the 
 sound ones, not ; it follows, therefore, that the present system of lining is very 
 defective. To lessen the charge of carriage, it is not unusual to side the logs 
 where the trees are felled. Now, if the trees were also sawn down the middle 
 in the forest, an increased facility of removal would be acquired, and the 
 timber would be seasoning, and probably be fit for use, ere it came into the 
 dock-yard. The longer a tree remains whole after it is felled, the more sap it 
 will contain, and the more rapid will be its decay. I have seen many treea 
 that were sound when felled, decay from the heart outwards, owing to their 
 lying a long time with their juices shut up in them. The dividing of the treea 
 would have preserved them." 
 
 DUCTILITY. That property or textvire of bodies which renders a prac-
 
 DYING. 457 
 
 ticable to draw them out in length, while their thickness is diminished, 
 without any actual fracture of their parts. 
 
 DULCIFICATION, or DULCERATION, in Chemistry, the combination of 
 mineral acids with alcohol, by which their caustic or corrosive qualities are 
 diminished : thus we have dulcified spirit of nitre, dulcified sphit of 
 vitriol, &c. 
 
 DULCIMER. A musical instrument, strung with about fifty wires, cast over 
 a bridge at each end. It is performed upon by striking the wires with little 
 iron rods. 
 
 DUODECIMALS, or CROSS MULTIPLICATION, is a rule used by workmen 
 and artificers in computing their work. Dimensions are usually taken in feet, 
 inches, and parts, omitting all those which are less than one quarter of an inch 
 as of no consequence. Rule : Set down the two dimensions to be multiplied 
 together one under the other, in such manner, that feet shall stand under feet, 
 inches under inches, and parts under parts ; then multiply each term in the 
 multiplicand, beginning with the lowest, by the feet in the multiplier, and set the 
 result of each directly under its respective term, observing to carry one for 
 every 12 from the parts to the inches, and from the inches to the feet. In like 
 manner multiply all the multiplicand by the inches and parts of the multiplier, 
 and set the result of each in one place, removed to the right hand of those in 
 the multiplicand, and the sum of these successive products will be the answer. 
 
 Example. Multiply 6 feet 4 inches 3 parts by 10 feet 3 inches 9 parts. 
 
 Answer . . 65 6 3 
 
 It should be observed, that the feet in the answer are square feet, but the 
 numbers standing in the place of inches are not square inches, as might at first 
 be supposed, but twelfth parts of square feet, each part being equal to twelve 
 square inches. In like manner the number standing in the place of parts, or 
 in the third place of figures, are so many parts of the preceding denomination ; 
 these, therefore, are square inches. 
 
 DYING. The art of tinging or imbuing various substances with different 
 colours at pleasure. The principal application of this art is to fabrics of wool, 
 silk, and cotton ; but it is also applied to tha colouring of leather, marble, 
 ivory, and various other substances. We shall limit our description to the process 
 of dying the first-mentioned substances. The simple colours employed in 
 dying are mostly either of animal or vegetable origin ; but although the 
 number of possible dyes which might be obtained from these sources is almost 
 infinite, the number employed in the regular manufactories of Europe is small, 
 the infinite diversity of tint which is obtained being the result of the combi- 
 nation of two or more simple colouring substances with one another, or with 
 certain chemical reagents. Of the great variety of known dyes, some (though 
 comparatively few) may be applied to animal or vegetable stuffs without any 
 other preparation than that of cleansing the stuff, and then immersing them in 
 a decoction or infusion of the dye, which then becomes so permanently com- 
 bined with the fibre as to resist the effect of washing and the bleaching power 
 of the sun and air. But the greater number of dyes have such feeble affinity 
 for fibre that no permanent combination can be effected between them in their 
 simple state ; to effect the combination, recourse is had to various substances 
 having a strong affinity both for the fibre and the colouring matter ; and the 
 cloth being previously steeped in a solution of some of these substances, and 
 afterwards immersed in the dye, an intimate union of the cloth and the colour-
 
 458 DYING. 
 
 ing mattter is effected. The substances which serve to fix the colouring 
 matter in the cloth are termed mordants ; and in the management and selection 
 of them is the chief art of the dyer, as their effects are not limited to the fixing 
 of the colour, but they, in most cases, produce some alteration in the natural 
 hue, a circumstance which the dyer avails himself of in numerous cases, to 
 vary and improve the colour obtained from simple dye stuffs : thus aluminous 
 mordant changes the dull red of madder to a bright crimson ; and the solutions 
 of tin not only fix cochineal in wool, but change it from crimson to bright 
 scarlet ; but if the oxide of iron be substituted for the tin as a mordant, the 
 colour becomes changed to a black. In dying, then, it is necessary not only 
 to procure a mordant for the colouring matter and the cloth, and a colouring 
 matter which passes the desired colour in perfection, but to procure a mordant 
 and colouring matter, which, when combined, shall produce the colour sought. 
 It is also evident that a great variety of colours may be produced from a single 
 dye stuff, provided the mordants can be sufficiently varied. Mordants are 
 generally composed of earths or metallic oxides, tannin, and oil. Of earthy 
 mordants, the most important and generally used is aluroine, either in the state 
 of common alum, in which it is combined with sulphuric acid, or in that of 
 acetate of alumina, which answers much better than alum, as the cloth is more 
 easily saturated with alumine, and takes, in consequence, a richer and more 
 permanent colour. Almost all the metallic oxides have an affinity for cloth, 
 but only two of them are extensively used as mordants, viz. the oxides of tin 
 and of iron. The oxide of tin was first introduced in dying by Kuster, a 
 German chemist, who brought the secret to London in 1543. It is generally 
 employed in the state of nitre-muriate, muriate, or acetate of tin. Iron is 
 generally employed in the state of the sulphate or the acetate ; the first being 
 chiefly used for wool, and the latter for cotton. Tannin has a very strong 
 affinity for cloth, and for several colouring matters. It is principally obtained 
 from nut galls, or sumach, which contain it in great quantities. Tannin is also 
 often employed along with other mordants to produce a compound mordant. 
 Oil is also used for the same purpose in dying cotton and linen. We now pro- 
 ceed to a consideration of the dyes, and commence by observing that innumer- 
 able as are the different colours and shades of colours communicated, they all 
 originate from four or five primary dyes, modified according to the colour 
 intended to be produced. These primary or simple dyes are as follow : blue, 
 yellow, red, black, and fawn, or brown colour. 
 
 Of Blue. The only two substances used for dying blue are woad and indigo- 
 Indigo has a very strong affinity for wool, silk, cotton, and linen, all of which may 
 therefore be dyed with it without the assistance of any mordant. But indigo 
 is soluble only in sulphuric acid ; it is therefore necessary either to employ the 
 sulphate of indigo, or to render it soluble in water, by depriving it of its 
 oxygen. The first process is frequently employed for dying wool or silk ; but for 
 linen or cotton, the latter is generally resorted to. When the sulphate is em- 
 ployed, one part of indigo is to be dissolved in four parts of concentrated sul- 
 phuric acid, and one part of dry carbonate of potash added to the solution, 
 which is then to be diluted with eight times its weight of water. The cloth 
 must be boiled for an hour in a solution of five parts of alum and three of 
 tartar, after which it must be removed to a bath containing a greater or smaller 
 proportion of the sulphate of indigo, according to the shade which the cloth is to 
 receive ; and in this bath it must be boiled until it acquire the desired colour. The 
 alum and tartar are not intended to act as mordants, but to facilitate the decom- 
 position of the sulphate of indigo. The alkali added to the sulphate answers 
 the same purpose. But the most common method of employing indigo is to 
 deprive it of the oxygen to which it owes its blue colour, and thus reduce it 
 to the state of green pollen, and then to dissolve it in water by means of 
 alkalies or alkaline earths, which act very readily upon it in that state. It is 
 deprived of oxygen either by admixture with other substances possessing a 
 greater affinity for oxygen, as the green oxide of iron, or various metallic 
 sulphurets; or it may be mixed in water with certain vegetable substances 
 which readily undergo fermentation : the ferments most commonly employed
 
 DYING. 459 
 
 are woad arid bran. During this fermentation, the indigo is deprived of 
 its oxygen, and is then dissolved by means of quicklime or alkali added to the 
 solution* The first of these methods is usually followed in dying cotton or 
 linen ; the second, in dying wool and silk. 
 
 Of Yellow. This colour is most commonly obtained from weld, fustic, or 
 quercitron bark. The cloth requires to be prepared before dying, by com- 
 bining it with some mordant ; that most commonly employed for this purpose 
 is alumina. 
 
 Of Red. The materials employed for this colour are lac or kermes, cochi- 
 neal, archil, madder, carthamus, and Brazil wood ; and the ordinary mordants 
 are alumina, and the oxides of tin ; various shades are produced by intermix- 
 ture of the dying materials above named, or by first dying the stuff with on 
 or more of them, and subsequently passing it through a yellow bath. 
 
 Of Black. The substances employed to give a black colour are red oxide of 
 iron and tannin. These two substances have a strong affinity to each other, 
 and, when combined, assume a deep black colour, not liable to be decomposed 
 by light Logwood is usually employed as an auxiliary, because it commu- 
 nicates lustre, and adds considerably to the fulness of the black. Cloth, before 
 it receives a black colour, is usually dyed blue, which renders the colour much 
 fuller than it would otherwise be ; for inferior cloth, a brown colour is some- 
 times given by means of walnut peel. 
 
 Of Brown, or Fawn Colour. Various plentiful and cheap substances are 
 employed to give a brown or fawn coloured ground, as birch, sumach, alder 
 bark, but more especially decoction of walnut peels, or walnut bark or rpot. 
 The shades produced by the bark or rind of the walnut tree are particularly 
 fine, the colours solid, and it renders the wool, when dyed in it, flexible and 
 soft. From the above colours variously combined are derived the endless 
 gradations of tint imparted to the various fabrics of silk, wool, cotton, and* 
 linen. Of these compound colours we shall notice a few of the principal. 
 
 Of Green. This is a mixture of blue and yellow, the shade varying accord- 
 ing to the prevalence of either ingredient. The cloth is generally first dyed 
 blue, and then immersed in a yellow bath ; but when sulphate of indigo is 
 employed, it is usual to mix the ingredients together, and dye the cloth at once. 
 
 Of Violet, Purple, and Lilac. These are all mixtures of blue and red, and 
 depend upon the different shade produced by the proportion of one colour to 
 the other. Wool, cotton, and linen, are firt dyed blue ; the two last are then 
 galled, and soaked in a decoction of logwood, or of green sulphate of iron , 
 they are then dyed scarlet in the usual manner : by means, however, of 
 cochineal, mixed with sulphate of indigo, the process may be performed at 
 once. Silk is first dyed crimson with cochineal, and then dipped in the indigo vat. 
 
 Of Orange. This is a mixture of yellow and red. A remarkable differ- 
 ence exists in the affinity of various substances for colouring matter, animal 
 substances generally taking the dye much more readily ttan those of vegetable 
 composition thus wool and silk are more easily dyed than cotton and linen ; 
 the latter article, indeed, has so slight an affinity for the dye that it is extremely 
 difficult to impart to it a bright and permanent colour. The processes and 
 manipulations in dying are few and simple, and require principally a good eye 
 to judge accurately of the gradations of the tints, and care and attention in pre- 
 paring the ingredients, and in maintaining the baths at a proper temperature. 
 
 Mr. J. Hall, of Ordsall, near Manchester, has recently obtained a patent for 
 nn apparatus, shown in the engraving on the following page, the object of 
 which is to cause the goods to be exposed to the action of the liquor in 
 the dye vat in a more equal manner than is done in the ordinary method. In 
 the dye vat a are placed six small rollers, 1 to 6, one at each corner, and two 
 near the middle, on the same line with 1 and 4. At about half the depth of 
 the vat are placed two large rollers b and c, about one foot asunder ; one end 
 of each of the axes of these rollers comes through a stuffing-box, and on the 
 axis of b is placed a cog-wheel, which is connected with the axis by a pin 
 passing through it that can be withdrawn at pleasure ; on the axis of c is a 
 similar wheel gearing into b, and may be thrown otit of gear when required by
 
 460 
 
 DYNAMICS. 
 
 the lever d. On the top of the vat is the roller ?, whose axis turns in bearings 
 fixed in each side of the vats ; and upon this roller another roller /rests, which 
 can only move in a vertical direction, its axis being square, and confined by 
 guides g. At one end of the vat is a roller h, supported in two upright forks, 
 and having a small wheel on its axis ; another wheel Ic on a short axis is placed 
 between the last mentioned wheel and the wheel and the axis of c, and gears 
 into each. The roller h may be lifted out of the forks by the lever I. To the 
 roller c is fastened a piece of cloth of the width of the goods to be dyed ; this 
 cloth passes over the rollers 6 and 1, under 2 and 3, and over 4 : a similar 
 
 piece of cloth is wound round the roller I, the end of which is brought up and 
 hung over the roller 5. The cloth or web to be dyed is attached by a long 
 skewer to the cloth of c, hanging over the roller 4 : the wheel b being now 
 -unpinned, and set in motion by a band wheel, or other means, the web is 
 wound upon c, passing under the roller, as before described, until the outer end 
 arrives at the roller 4, when it is attached to the cloth of b by a skewer, and 
 the wheel turned until the cloth on b is unwound. The wheel on c is next 
 thrown out of gear, and that on the axis of b is pinned to its axis, when the 
 wheel being again set in motion, the cloth is unwound from c and wound 
 upon b; and it is thus wound alternately upon each of the rollers b and c, until 
 it is deemed sufficiently dyed. It must then be wound upon the roller b, and 
 the cloth, being detached from the web c, is passed between the rollers e and 
 /, and made fast to the roller h. The wheel on b is then unpinned, and being 
 set in motion, turns h by means of the wheel on c, and the small wheel k ; the 
 piece is thus wound upon the roller h, and deprived of a great portion of mois- 
 ture by the pressure of the rollers e f. When the end appears above the roller 
 5, the" skewer attaching it to the cloth of b is withdrawn, and the roller h is 
 lifted out of the forks by the lever I, and replaced by a similar one. 
 
 DYNAMICS treats of the nature and laws of motion. In this sense it is 
 used in opposition to STATICS. A single force, always producing motion, must 
 6e considered under the head of Dynamics; but two or more forces, accf rdinglv
 
 DYNAMOMETER. 
 
 461 
 
 as they result in producing motion or not, constitute cases in STATICS or 
 DYNAMICS. These two terms are frequently used to designate the two great 
 divisions of mechanics Statics, including all cases where equilibrium is pro- 
 duced, and Dynamics, those in which motion results. The term dynamics is, 
 however, not confined exclusively to the motions of solid bodies. When applied 
 to describe the laws of motion in fluids, it is termed hydrodynamics, and electro- 
 dynamics when used to comprehend the phenomena of electricity in motion. 
 See FORCES, MOTION, &c. 
 
 DYNAMOMETER. An instrument employed to measure the comparative 
 
 Fig. 2. 
 
 strengths of men and cattle, and to ascertain the force required in drawing 
 3*
 
 462 EAR TRUMPET. 
 
 carriages upon land, and vessels upon canals. These effects are usually esti- 
 mated by the compression or distension of a strong spring, or by a steelyard 
 upon the principle of a bent lever balance ; but in both these constructions the 
 instrument is subject to great vibration, owing to inequalities in the resistance 
 and in the moving force, which render the indications very uncertain. This 
 o jection to spring dynamometers has been obviated by Mr. H. R. Palmer, as 
 follows : a piston, fitting loosely in a cylinder filled with oil, so as to allow the 
 oil to escape slowly past its sides as it moves up and down, is connected with 
 the springs by means of a fine steel wire passing through stuffing boxes at each 
 end of the cylinder ; the friction, therefore, is so extremely slight as not to be 
 worth taking into account in any experiments, whilst it prevents that vibratory 
 motion of the index, from jerks, and allows the resistance to be ascertained 
 with the greatest accuracy. The preceding engraving is a representation of the 
 instrument, a a represents the back of the dial plate of any ordinary spring 
 weighing machine, the front of which is shown separate in Fig. 2 (but without 
 the graduated scale, as being unnecessary) ; bb are two spiral springs enclosed 
 in cylindrical cases, (similar to the well-known domestic article called pocket 
 steelyards,) the upper ends of which are fixed to a sliding frame c c, and at 
 their lower ends they are hooked to a cross bary, which bar is made fast to a 
 piece of metal o at the back of a a; d is the cylinder of oil, which is firmly 
 fixed at the back of a a; to this cylinder is fixed four pieces of metal e e e e, 
 having angular grooves, in which the frame c c slides when the springs are acted 
 upon. The piston in the cylinder is shown by dots, the rod to which (a fine 
 steel wire) passes through stuffing boxes at each end of the cylinder, and each 
 end of the rod is then made fast to the frame c c. Now the bar g, which pro- 
 ceeds from the circular box a a, and acts upon the spring, is connected at the 
 swivel ring i with the upper end of the frame c c, as one solid piece ; therefore 
 when the ring k is made fast to a carriage, and power applied to the rope at i, 
 the bar g is drawn out of a, while the frame c c acts simultaneously upon the 
 steelyard springs c c, which move along with them the piston in the fixed 
 cylinder d ; the oil therein being incompressible, is compelled to pass from one 
 side of the piston to the other, through the extremely narrow interstice between 
 the periphery and the cylinder. 
 
 In the dynamometer invented by Mr. Milne, of Edinburgh, an iron plunger 
 is by the force exerted in traction caused to descend in an open vessel con- 
 taining mercury, by which means the latter rises to a height indicated by a 
 glass tube open at top, and connected to the mercurial vessel at bottom by a 
 neck, the bore of which is contracted to diminish the vibrations of the mercurial 
 column ; half the height in inches of the mercury in the tube multiplied by the 
 area of the base of the plunger in inches will be the amount of the force of 
 traction in pounds. 
 
 E. 
 
 EARTHS. A name commonly assigned to a class of solid substances com- 
 posing, in various states of combination, the crust of the globe ; the general 
 qualities of which are, that they are incombustible, not convertible into metals 
 by the ordinary methods of reduction, and their specific gravity not exceeding 
 five times that of water. The number of these substances is ten ; viz. barytes, 
 strontites, lime, magnesia, alumina, or clay, silica, glucina, zerconia, yttria, 
 and thorina. But although these substances are generally termed earths, the 
 experiments of Sir H. Davy have shown that a portion of them, viz., barytes, 
 strontites, and lime, as well as the alkalies, potash and soda, are, in reality, 
 combinations of metallic bases with oxygen and lead, and determine, by 
 most probable analogies, that the whole of them belong to the metallic class. 
 
 EARTHENWARE. Articles made of baked or vitrified earth: See 
 POTTERY. 
 
 EAR TRUMPET. A contrivance for the benefit of 'deaf persons; as 
 usually constructed, it resembles in shape a marine speaking trumpet, but 
 smaller, seldom exceeding six or eight inches in length. The party using the
 
 EBONY. 463 
 
 trumpet inserts the small end within his ear, and the speaker applies his mouth 
 to the wide end. Dr. Morrison, of Aberdeen, however, contends that this con- 
 struction is erroneous, and that the end which is applied to the ear should 
 be large enough to include the whole ear, instead of being inserted within 
 it The Doctor states, that having laboured under a deafness for a number 
 of 3'ears, he applied in ever}' quarter for the most improved ear trumpet; 
 but from none of them could he derive the most trivial benefit. He at length 
 ordered one to be made of the finest block tin, constructed as above recom- 
 mended, and found it to answer beyond his most sanguine hopes. The annexed 
 cut is a representation of a flexible ear trumpet, invented by Mr T. Hancock, 
 of Fulham. It is made of Indian rubber, covered with a net-work of gold or 
 
 silver wire, and, from its flexibility, is rendered more convenient for portability 
 and for ready application in any situation that may be required. Mr. Hancock 
 has successfully applied tubes of this description as speaking pipes, to commu- 
 nicate verbally with the various parts of an extensive manufactory. 
 
 EASEL. A frame used by painters for supporting their pictures while in 
 progress, and admitting of being adjusted to any convenient angle by means 
 of a movable prop at the back. 
 
 EAU-DE-LUCE. A volatile preparation, which is thus made : 12 grains 
 of white soap are dissolved in 4 ounces of spirit of wine ; this solution being 
 strained, a drachm of rectified oil of amber is added, and the whole filtered. 
 Afterwards, some strong volatile spirit of sal ammonia is to be mixed with the 
 solution. 
 
 EAU-DE-COLOGNE. A celebrated odoriferous liqueur: the following is 
 the true mode of preparing it. Take of the essence of bergamot, lemon peel, 
 lavender, and orange flower, of each 1 ounce ; essence of cinnamon, half an 
 ounce ; spirit of rosemary, and of the spirituous water of melisse, each 15 
 ounces ; strong alcohol, 7 pints. Mix the whole together, and let the mixture 
 stand for the space of a fortnight ; after which introduce it into a glass retort, 
 the body of which is immersed in boiling water, contained in a vessel placed 
 over a lamp, while the beak is introduced into a large glass reservoir well 
 luted. By keeping the water to the boiling point, the mixture in the retort 
 will distill over into the reservoir, which should be covered with wet cloths. 
 In this manner will be obtained pure eau-de-Cologne. 
 
 EAVES. The edge or margin of the roof of a nouse, which projects beyond 
 the walls to throw off the water therefrom. 
 
 EBONY. An exceedingly hard and heavy wood, susceptible of a fine polish. 
 There are many kinds of ebony ; the most usual are the black, red, and green, 
 all of them the product of the island of Madagascar. The black ebony is pre- 
 ferred to that of any other colour, but it is not so much in request as formerly, 
 since the discovery of so many ways of giving other hard woods a black colour. 
 This may be done by boiling smooth, clean box wood in oil till it becomes per- 
 fectly black ; or by washing pear wood with aquafortis, and drying it in a
 
 464 EFFECT 
 
 shady place in the open air ; after which common writing ink should be 
 repeatedly passed over it, and the wood dried in a similar manner till it acquire 
 a deep black colour. It may then be polished with wax and a woollen cloth, 
 which will give it a fine lustre. An excellent black is also produced by first 
 applying a solution of copper and aquafortis, and afterwards brushing the wood 
 over with a decoction of logwood. 
 
 ECCENTRIC, in Geometry, denotes two circles or spheres, one of which is 
 contained within the other, but the centres of the two do not coincide. In 
 mechanics, the name is given to a contrivance frequently substituted for a 
 crank, for obtaining a reciprocating motion from a circular. It consists of a 
 circular disc placed eccentrically upon a shaft, and revolving within a hoop 
 formed at one end of the connecting rod. The valves of most steam engines 
 which work with a fly-wheel are moved by an eccentric. 
 
 EDGE TOOLS is a general name applied to the coarser kinds of cutting 
 instruments, such as chisels, axes, adzes, gouges, augers, saws, &c. 
 
 EFFECT (USEFUL), in Mechanics ; the measure of the real power of any 
 machine, after deducting that portion which is lost or expended in overcoming 
 the inertia and friction of the moving parts, and in giving them the required 
 velocity, and every other source of loss. The greatest useful effect which a 
 horse can produce, was estimated by Bolton and Watt at 33,000 Ibs. raised one 
 foot high per minute ; and upon the introduction of the steam engine to per- 
 form the labour which was before performed by horses, their power was ex- 
 pressed by that of the number of horses which they were equal to ; and from 
 the convenience of this mode of expression, it has since been generally adopted 
 to express the power of all kinds of machinery. It is at all times desirable to 
 know the real effective power of any machine : when water is to be raised, the 
 effect is readily computed, but in most other species of work it is difficult to 
 estimate the resistance, and consequently whether the engine be really equal to 
 its nominal power ; in this case, Mr. Tredgold observes, the most convenient 
 and simple mode of measuring the effect is by friction. If the rim of a brake 
 wheel of known diameter upon an engine shaft be pressed with a force pro- 
 ducing a known degree of friction, which is exactly equal to the effect of the 
 engine at its working speed, then it is clear that if the friction this pressure 
 produces be ascertained, the power of the engine will be equal to the friction 
 multiplied by the velocity of the rubbing surface. To apply this, let A B be a 
 lever with a friction strap, that may be tightened upon the cylindrical surface 
 of the shaft or wheel C, and let it be tightened by the screw at B (the lever 
 being stopped by the stop at D), till the friction be equal to the power of the 
 engine when all other work is thrown off; then while the engine is still in 
 motion, add such a weight at E as retains the lever in a horizontal position. 
 
 To calculate the power, multiply together the length of the lever F C in feet, 
 me weight E in Ibs. the number of revolutions of C per minute, and the 
 number 6.2832 ; the result will be the number of pounds raised one foot per 
 -ninute, and divided by 33,000 it is the horses' power. Thus if a shaft make 
 20 revolutions per minute, and the length EC of the lever be 10 feet, and if it 
 be found that a weight of 240 Ibs. is sufficient to retain the lever in a hori- 
 zontal position, then 6.2832 X 10 X 240 X 25=376992 Ibs. raised one foot high, 
 or nearly eleven and a half horses' power
 
 ELECTRICITY. 465 
 
 EFFERVESCENCE. The commotion produced in fluids by some part of 
 the mass taking suddenly the elastic form, and escaping rapidly in numerous 
 bubbles. 
 
 EFFLORESCENCE. The effect which takes place when bodies spon- 
 taneously become converted into a dry powder. It is almost always occasioned 
 by the loss of the water of crystallization in saline bodies. 
 
 EGGS. The envelope which contains the foetus of various animals, and 
 which, being voided by the parent, is subsequently matured by. incubation. 
 This may also be effected by means of prolonged artificial heat ; and in Egypt 
 the art of hatching chickens by means of ovens has long been practised, but 
 it is there only known to the inhabitants of a single village, named Berme, 
 and to those that live at a small distance from it. Towards the beginning of 
 autumn they scatter themselves all over the country, where each person among 
 them is ready to undertake the management of an oven, each of which is of a 
 different size, but in general they are capable of containing from forty to four- 
 score thousand eggs. The number of these ovens placed up and down the 
 country is about 386, and they usually keep them working for about six months ; 
 as, therefore, each brood takes up in an oven, as under a hen, only twenty-one 
 days, it is easy in every one of them to hatch eight different broods of chickens. 
 Every Bermean is under the obligation of delivering to the person who entrusts 
 him with an oven, only two-thirds of as many chickens as there have been eggs 
 put under his care ; and he is a gainer by this bargain, as more than two-thirds 
 of the eggs usually produce chickens. In order to make a calculation of the 
 number of chickens yearly so hatched in Egypt, it has been supposed that only 
 two-thirds of the eggs are hatched, and that each brood consists of at least 
 30,000 chickens ; and thus it would appear that the ovens of Egypt give life 
 yearly to at least 92,640,000 of these animals. As it is of great importance 
 in a zoological, and, to a certain extent, even in an economical point of view, 
 to be able to transport eggs fresh from one country to another, it has been 
 proposed, as the best method of effecting this, to varnish them with gum 
 arabic, and then imbed them in pounded charcoal, which being a non-conductor 
 of heat, a uniform temperature will be preserved. 
 
 ELAINE. The oily principle of solid fats, the remaining or solid portion 
 being named stearine, names assigned to these substances by the discoverer, 
 Mr. Chevreul. If tallow be squeezed between the folds of porous paper, the 
 elaine soaks into it, whilst the stearine remains. The paper being then soaked 
 in water and pressed, yields up its oily impregnation. Elaine has very much 
 the appearance and properties of vegetable oil, and is liquid at the temperature of 
 60. Cocoa nut oil, which in England usually is concrete, or at most semi-fluid, 
 has of late years been resolved into the above-named constituents by mechanical 
 pressure, and the solid part manufactured into candles, whilst the liquid forms 
 a valuable oil for lamps. See FAT. 
 
 ELASTICITY. A property of bodies to resume their form upon the removal 
 of any force by which they may have been deflected from it. In this respect all 
 bodies which come within our knowledge are comprehended under one of these 
 three distinctions. If two bodies, when pressed together, suffer an alteration 
 in their form, and if afterwards, on removing that pressure, they recover their 
 original figures, they are called elastic; if, when pressed, their forms are not in 
 the least altered, they are called hard; and if, when pressed as above, they alter 
 their forms, and retain the same after the pressure is discontinued, they are 
 called soft ; and both these last kinds of bodies are termed non-elastics. It is 
 doubtful, however, whether any bodies are either perfectly hard, or soft, or elastic, 
 the air not being perfectly elastic, and water (which was for a long time held to 
 be perfectly incompressible and non-elastic,) being in the opinion of many 
 persons shown to be compressible, by the experiments of Canton and of Perkins. 
 
 ELECTRICITY. The name assigned to a certain mysterious natural 
 principle or element, with the nature of which we are totally unacquainted, 
 as it can only be inferred from its effects, in which respect it resembles 
 the principles of light, heat, and magnetism. For a brief outline of the science 
 of electricity, see CHEMISTRY.
 
 466 EMERY. 
 
 ELEMENTS. The name assigned by the ancients to those simple subjtances 
 of which, by combination, all bodies were supposed to be formed. These 
 principles were supposed to be four in number, viz. fire, water, earth, and 
 air; but the researches of modern chemistry have completely overturned this 
 classification, showing that each of these supposed elements is in reality 
 composed of two or more substances, and extending the number of simple sub- 
 stances to nearly fifty ; at the same time it is to be observed that these sub- 
 stances are not pronounced to be absolutely simple, but are merely so in respect 
 to the present state of the art of analyzing bodies. For a list of the simple 
 or undecompound substances, see CHEMISTRY. 
 
 ELEVATION, in the art of design, an orthographic projection of the vertical 
 figure of any building or piece of machinery, there being no vanishing points, 
 as in a perspective representation, but the eye being supposed to occupy the 
 whole space of the picture, or every part of the object bein^ deemed perpen- 
 dicular to the eye. 
 
 ELIQUATION. An operation by which one substance is separated from 
 another that is less fusible. It consists in the application of a degree of heat 
 sufficient to fuse the former, but not the latter. 
 
 - ELIXiR. A compound tincture extracted from many ingredients, whereas, 
 a simple tincture is extracted from only one ingredient. 
 
 ELLIPSIS, in Geometry, a curve line returning into itself, and produced 
 from the section of a cone by a plane cutting both its sides, but oblique to the 
 axis of the cone. 
 
 ' EMBOLUS. Any thing inserted and acting in another, as the sucker of a 
 pump, the piston of a steam engine, &c. 
 
 EMBOSSING. The forming of ornaments in relief upon any substances, 
 whether by sculpture, casting, stamping, or any other means. One pleasing 
 species of embossing is that by which the leather covers of books are now so 
 richly ornamented ; this is effected by means of a metal plate on which the 
 pattern is engraved, and which, being heated, gives the impression to the 
 leather by the action of a powerful fly-press. The following method of em- 
 bossing on wood, invented by Mr. Straker, is extracted from the Transactions 
 of the Society of Arts ; it may be used either by itself, or in aid of carving, and 
 depends on the fact, that, if a depression be made by a blunt instrument on the 
 surface of wood, such depressed part will again rise to its original level by 
 subsequent immersion in water. The wood to be ornamented having first been 
 worked out to its proper shape, is in a state to receive the drawing of the 
 pattern ; this being put in, a blunt steel tool, or burnisher, or die, is to be 
 applied successively to all those parts of the pattern intended to be in relief, 
 and at the same time is to be driven very cautiously without breaking the grains 
 of the wood, till the depth of the depression is equal to the subsequent pro- 
 minence of the figures. The ground is then to be reduced by planing or filing 
 to the level of the depressed part ; after which the piece of wood being placed 
 in water, either hot or cold, the parts previously depressed will rise to their 
 former height, and will thus form an embossed pattern, which may be finished 
 by the usual operation of carving. 
 
 EMBROIDERY. The enriching of cloth, stuff, or muslin, by figures worked 
 thereon with a needle, with thread of gold, silver, silk, or cotton. The em- 
 broidery of stuffs is performed in a kind of loom ; that of muslin by stretching 
 it on a pattern already designed, and the thinner the muslin the better it is 
 adapted to the purpose. 
 
 EMERALD. A well-known gem, of a pure green colour, somewhat hard r 
 than quartz, though softer than most of the precious stones. Owing to the 
 beauty of its colour, and the fine contrast it makes with brilliants, it is valued 
 next to the ruby. The oriental emerald is considered to be a variety of ruby of 
 a green colour. 
 
 EMERY. A very hard mineral, of a dark grey colour. The best is 
 obtained from the island of Naxos, whence it is imported into this country ; it 
 is found in irregular masses, mixed with other minerals. It is so hard as to 
 scratch topaz. Its constituents are 86 alumina, 3 silicia, 1 iron, and 7 loss. Its
 
 ENAMEL. 467 
 
 specific gravity is 4.0. Emery is also obtained from some of the iron mines in 
 this country. The extreme hardness of this substance has caused it to be 
 employed in various arts. Lapidaries employ it in cutting and polishing of 
 precious stones; opticians, in grinding glass preparatory to polishing. It is very 
 extensively used by the manufacturers of iron and steel wares ; is a common 
 household material for brightening iron ; and is applicable as a grinding, 
 scouring, and polishing powder, in a great variety of operations. For all these 
 purposes it is first pulverized in large iron mortars, and the powder, which is 
 very sharp, is frequently washed to free it from foreign matters ; it is then dried, 
 and afterwards sifted into six or more different degrees of fineness, for the 
 various purposes before mentioned. 
 
 EMPYREUMA. A term implying a peculiar odour derived from the over- 
 heating of matters under the process of distillation, or when vegetable or 
 animal matter becomes burned in other processes in close vessels. It is said 
 that tin's peculiar odour is produced from no substance that does not contain oil ; 
 hence, if no empyreuma is perceived in burning any substance in a close vessel, 
 we may be assured that it contains no oil. 
 
 ENAMEL. A shining vitrified substance, employed as an indestructible 
 coating to pictures, and various articles of taste and utility. The basis of all 
 kinds of enamel is a perfectly transparent and fusible glass, which is subsequently 
 rendered either semi-transparent or opaque by the admixture of metallic oxides. 
 White enamels are composed by melting oxide of tin with the glass, and adding 
 a small quantity of manganese to increase the brilliancy of the colour. The 
 addition of the oxide of lead or antimony produces a yellow enamel. Reds 
 are formed by an admixture of the oxides of gold and iron. Greens, violets, 
 and blues, are procured from the oxides of copper, cobalt, and iron ; and these, 
 when intermixed in different proportions, afford a variety of intermediate 
 colours. The proportion in which these ingredients are used, as well as the 
 degree and continuance of the heat necessary to their perfection, constitute the 
 secrets of the art. The best enamel was formerly imported from Venice ; but 
 during the restrictions on commerce imposed by the late war, the importation 
 had almost wholly ceased. The high price of the article, therefore, induced 
 British artisans to attempt its manufacture, and they succeeded in producing a 
 hard enamel, superior to the best Venetian in whiteness, and much more valuable 
 to the dial-plate makers. In 1817 Mr. Wynn communicated to the Society 
 of Arts a series of receipts for the preparation of enamel colours, and for 
 which a premium was awarded by the Society. The fluxes are those em 
 ployed by Mr. Wynn." 
 
 Parts. 
 
 (Red lead 8 
 
 KT , J Calcined borax ]J 
 
 Flint powder 2 
 
 Flint glass 6 
 
 [Flint glass 10 
 
 No. 2. 
 
 C Flint glass 
 3 White arsenic 
 (Nitre 
 
 < Red lead 1 
 
 ( Flint glass . . . 3 
 
 rRed lead 9 
 
 No. 4. ^Borax, not calcined 5J 
 
 (Flint glass 8 
 
 (Flint glass 6 
 
 No. 5 3 Flux, No. 2 4 
 
 (Red lead 8 
 
 After the fluxes have been melted they should be poured on a wetted flag-stone, 
 or into a large pan of clean water, then dried, and finely powdered in a biscuit- 
 ware mortar for use. 
 
 To make yellow enamel : take red lead 8 parts, oxide of antimony 1, and 
 white oxide of tin 1. Mix the ingredients well in a biscuit-ware mortar, and 
 having put them on a piece of Dutch tile in the muffle, make it gradually red
 
 468 ENAMELLING. 
 
 hot, and suffer it to cool. Take of this mixture 1 part, of flux, No. 4, 1J, and 
 grind them in water for use. By varying the proportions of red lead and anti- 
 mony, different shades of colour may be obtained. 
 
 To make orange enamel : take red lead 12 parts, red sulphate of iron 1, oxide 
 of antimony 4, and flint powder 3. After calcining these without melting, fuse 
 1 part of the compound with 2 of flux. 
 
 To make dark red enamel : take sulphate of iron, calcined dark, 1 part, flux, 
 No. 4, 6 parts, and of colcother 1 part ; of the two latter mixed, add 3 parts. 
 
 To make light red enamel: take red sulphate of iron 1 part, flux, No. 1, 3, 
 and white lead 1 . 
 
 To make broton enamel : take maganese 2J parts, red lead 8, flint powder 4. 
 
 ENAMELLING. The art of covering plates of metal with enamel is of 
 great antiquity ; it was practised by the Egyptians, and by them probably 
 transmitted to the Greeks and Romans. Several ancient specimens of curious 
 workmanship prove its existence in Britain at a very early period. It was for- 
 merly employed chiefly for ornamental purposes, but since the invention of 
 clocks and watches, its usefulness has been proportionably increased. For 
 clock and watch dials there is probably no substance that could be substituted 
 that can equal enamel in permanence and beauty. The art of dial-plate 
 enamelling is divided into two branches, namely, hard enamelling, and soft or 
 glass enamelling. In the first branch the Venetian enamels are chiefly em 
 ployed ; in the last the English or glass enamels. The practice of hard 
 enamelling requires more skill, time, and labour, than the others, and is con- 
 sequently the most esteemed. The metals to be enamelled on are usually gold, 
 silver, or copper; but the process being similar, one description will suffice. 
 The copper, which is the metal usually employed, being evenly flatted in long 
 slips, and to a proper thickness, pieces are cut off for use according to the size 
 wanted ; they are then annealed in a clear fire in order to make them suffi- 
 ciently pliable to take the required forms which are given U> thsm by means of 
 brass dies. A complete set of dies varies in size from about three-fourths of an 
 inch, to two inches and a half, the gradations being very small. The copper is 
 next placed on the die best adapted for the purpose, and the eye, or centre 
 hole, is made with a small round-headed punch, and smoothed with a grained 
 file ; it is then again placed on the die, and pressed gradually open, till it 
 nearly fills the hole with an oval burnisher ; it is afterwards pressed tighter into 
 the hole with a round broach, the burr being occasionally taken off by the file, 
 and care employed to prevent the eye from cracking. The punch, burnisher, 
 and round pin, are all of steel ; the two latter taper in regular gradation 
 towards the handles. When the eye is completed, the edge of the copper is 
 cut round, so as to leave a small part projecting beyond the die, which is then 
 turned up or burnished against the edgt of the die, the copper being first laid 
 smooth and flat by the burnisher, The copper is then gradually set up to the 
 convexity or height required by rubbing it gently, yet firmly, with a bent or 
 setting spatula, formed of a thin slip of steel about five inches long, properly 
 fixed, after which the feet are soldered on. The inconveniences that attended 
 the use of plain copper wire, soldered with spelter for the feet, are now entirely 
 obviated by employing copper wire plated with silver. The feet must be cut 
 by fixing an iron peg into the work-board ; to the pieces of plated wire being 
 held against it, it will be found to form a very good resistance against the 
 action of the file. It should be observed, that if coppers are to be made for 
 flat plates, the feet should be filed at right angles ; but if the plates are convex, 
 they should be filed at an angle as nearly as possible corresponding with the 
 curve formed in the hollow part of the copper, because when the foot is placed 
 on the copper it will be found to stand perpendicular to the base line or edge 
 of the copper. In order to make the feet remain in their places, and facilitate 
 the soldering, the end of each foot, before putting it on the copper, which is 
 done by means of a pair of corn tongs or tweezers, is dipped into a slight wash 
 of borax and water, through which it adheres with sufficient force to admit of 
 its being exposed to the power of the blow-pipe. The lamp in common use 
 contains from a pint to a quart of oil, and has a cylindrical spout projecting
 
 ENAMELLING. 4C9 
 
 tK at three inches, being an inch or more in diameter. This space is filled 
 with cotton, which being lighted, a strong flame is produced. The copper is care- 
 fully placed upon a piece of solid charcoal, long enough to be held in the hand ; 
 and the flame being then propelled by the blow-pipe against the solder or silvered 
 wire, as the case may be, the feet are firmly united to the copper. The whole 
 is then thrown into the pickling-pan, in order to free it from the scale or oxid- 
 able covering acquired from the heat. The coppers being thus prepared, the 
 next process is that of enamelling, properly so called. The operations of hard 
 enamelling, and glass enamelling, are, to a certain extent, the same. When 
 they are different, we shall describe the difference as we proceed. The enamel, 
 as it comes from the makers, is generally in small cakes from four to five 
 or six inches in diameter. It is first broken with a hammer, and then ground 
 in a mortar, and moistened with water ; after which, the coppers having been 
 first cleansed by the pickle, and carefully brushed out with water, are spread, 
 face downwards, over a soft cloth, or smooth napkin, and a thin layer of hard 
 enamel, called in its ground state the backing, is spread over the under sides 
 with the end of a quill, properly cut, or with a small bone spoon. The coppers 
 are then slightly pressed on by another soft cloth or napkin, which, by imbibing 
 some portion of the water, renders the enamel sufficiently dry to be smoothly 
 and evenly spread with the rounded side of a steel spatula. The next opera- 
 tion is to spread a layer of glass enamel over the upper sides of the coppers, 
 called the first coats. In doing this, the surface is first brushed slightly over 
 with a small camel-hair brush, or a hare's foot, to remove any dirt or extra- 
 neous particles of enamel, as the mixture of any hard enamel with the glass 
 would infallibly spoil the work. The glass is then spread upon the coppers in 
 a layer, the thickness of which is commonly the same as the height of the edge 
 and eye. The water is afterwards slightly absorbed with a clean napkin, 
 smoothly folded, and the enamel spread by a thin flat spatula, till all uneven- 
 ness is removed, and the surface lies regularly from edge to centre. The next 
 department is firing, as it is technically called, which consists in melting it till 
 it becomes one uniform mass on the surface of the copper. In doing this, the, 
 first coats are placed upon rings, which are generally made of a mixture of 
 pipe-maker's clay and Stourbridge clay, rolled up into the form of cylinders, 
 and turned in a lathe by means of a cylindrical piece of wood forced through 
 the centre of the mass when wet. They are next put into a shallow tin vessel 
 called a tin cover, which is either made square or round, according to the fancy 
 of the artificer, and is commonly about three quarters of an inch in depth. AH 
 the moisture is then slowly evaporated from the enamel, by placing the cover 
 upon a German stove, or in some other convenient situation near a fire, where 
 the evaporation can be properly regulated. The firing is executed beneath a 
 muffle, placed in a small furnace, ignited with coke and charcoal. The fur- 
 nace being drawn up to a sufficient heat by means of a register, the first coats 
 are taken separately from the tin covers and placed upon thin planches of clay, 
 or iron chalked over, and gradually introduced beneath the muffle, where, in a 
 very short time, the enamel melts or runs, and becoming properly consoli- 
 dated, the first coat is complete. A second layer of ground enamel is then 
 gently spread with a quill, and prepared for firing by the napkin and spatula as 
 before ; after which the second coats are placed upon the rings, and the mois- 
 ture being evaporated in thp tin cover, they are ready for a second fire. This 
 requires an equally cautious management as the former one. The plates must 
 not be over-fired, nor must the heat be suffered to melt the enamel too rapidly, 
 but a kind of rotatory motion, called coddling, must be given to the work, by 
 holding the loaded planch lightly with the tongs, and gently drawing the edge 
 of it towards the mouth of the muffle, and then returning it to its former place, 
 till the fusion be complete. The work is now in a fit state for polishing, tech- 
 nically called using off. This is performed by rubbing the surface of the plate 
 on a grit stone with fine sand and water, until all the glazed appearance is 
 completely obliterated, and one uniform and equally rough surface is produced. 
 The intention of this part of the process is to remove the mottled appearance 
 on the surface, and give a more equal convexity to the plate. 
 3u
 
 470 ENAMELLED CARDS. 
 
 The foregoing is an outline of the process for glass enamel plates. The firing 
 of the Venetian hai'd enamel is much the same ; but the heat applied to melt 
 it must not he so great, and the plate must be taken from the fire as soon as 
 the enamel is found to form one tolerably compact body, as any longer con- 
 tinuance would have a tendency to spoil the intended shape of the plate, 
 which is always considered a most essential quality in those of hard enamel. 
 The heat for finishing may be rather more than that used in the first fires, as in 
 that instance the intention was only to unite the particles of enamel into one 
 solid mass : but the principal object in finishing being to raise the flux to the 
 surface as much as possible, a greater heat may be used with advantage, but 
 the plate must be taken from the furnace the instant that the surface appears 
 bright and glossy. Where good Venetian enamel cannot be obtained, and 
 mixtures of various kinds are resorted to, it frequently happens that the glass 
 enamel plates crack when they are brought to the second fire. When this is 
 the case, as soon as the crack is observed the plate must be withdrawn from the 
 fire ; and if it extends only from the centre hole to the edge, it will, in most 
 cases, bear mending; but if it has happened in two or three places, it will 
 be useless to make the attempt, as it will rarely succeed. If the dial plate was 
 to continue in the fire after it is cracked a sufficient time, the enamel would 
 close, and the plate become sound again ; but as the copper on its surface is 
 in a state of oxidation, the oxide of copper uniting with the enamel would 
 rise to the upper surface of the plate, producing by its union a faint and some- 
 times a dark green line, which would evidently render the plate useless. The 
 operator, therefore, must observe the time when the crack has opened to its 
 greatest width, and before it unite or close at the bottom the plate must be 
 withdrawn from the furnace and allowed to cool. The opening must then be 
 filled with fine enamel, laid sufficiently high to allow for its running down in 
 the fire ; but to adjust the quantity so as to prevent the appearance of a seam 
 across the plate will require much judgment ; and, indeed, however well the 
 operation rnay succeed, it will still remain visible. 
 
 The method of painting in enamel is performed on plates of gold, silver, and 
 copper, enamelled with the white enamel ; whereon they paint with colours 
 which are melted in the fire, by which they acquire a brightness and lustre like 
 that of glass. This painting is the most prized of all for its peculiar brightness 
 and vivacity, which is very permanent, the force of its colours not being effaced 
 or sullied with time as in other painting, and continuing always as fresh as 
 when it came out of the workman's hands. 
 
 ENAMELLED CARDS is a name given to the cards on which a coating in 
 imitation of real enamel is produced. We believe there are' various processes 
 at present employed for fabricating these elegant and fashionable articles ; but 
 the following account of Mr. Christ's process, which we derive from the speci- 
 fication of his patent, enrolled in August 1 826, may be regarded as genuine and 
 practical. One pound of parchment cuttings, a quarter of a pound of isinglass, 
 and a quarter of a pound of gum arabic, are to be boiled in an open iron pot 
 or other vessel, in twenty-four quarts of pure water, until the solution is reduced 
 to twelve quarts, when it is to be taken off the fire and strained clear. The 
 solution of this consistence is then to be divided into three equal parts of four 
 quarts each ; to the first of these portions is to be added six pounds of pure 
 white lead, (previously ground fine in water,) which is called mixture No. 1 ; to 
 the second portion, eight pounds of pure white lead, forming mixture No. 2 ; 
 and to the third is to be added six pounds of pure white lead, making mixture 
 No. 3. The sheets of paper are then to be stretched out upon flat boards and 
 brushed over with a thin coat of No. 1 mixture, with a common painter's brush ; 
 the paper is then to be hung up to dry for twenty-four hours. After this, the 
 paper is in a similar manner to receive a coat of No. 2 mixture, and to be hung 
 up again to dry for twenty-four hours: the paper is then to be treated in the 
 like manner with No. 3 mixture; and then dried again for twenty-four hours. 
 It is next to be printed with the engraved plate, and the press-board used for 
 the purpose is to be of smooth cast iron instead of wood. The printing being 
 completed, the paper is to be hung up a fourth time for twenty-four hours to
 
 ENCAUSTIC PAINTING. 471 
 
 dry; after this it undergoes the final operation of receiving its high gloss, which 
 consists in laying the work with its face downwards on a highly-polished steel 
 plate, and then passing both with great pressure between a pair of cylindrical 
 rollers, and thus the beautifully polished surface of the steel is transferred to 
 the composition on the paper, which closely resembles in appearance the finest 
 white enamel. It is, however, to be regretted that this enamelled surface is 
 not very durable, as it comes off readily after wetting it with the finger. To 
 prevent this, a solution of some resinous substance should be added in the 
 last operation. 
 
 ENCAUSTIC PAINTING. A method of painting, much in use among 
 the ancients, in which wax was employed to give a gloss to the colours, and 
 permanence to the work. From the meagre account given to us by Pliny of 
 the method, it is evident he was not in the secret himself; all the information 
 he affords amounts to this that the colours made use of were fixed by fire, 
 and that wax was employed to give them a gloss, and preserve them from 
 being injured by the air. This ancient art, after having been long lost, was 
 restored by Count Caylus, a member of the Academy of Inscriptions at Paris ; 
 and the method of painting in wax was announced to the Academy of Painting 
 and Belles-Lettres in the year 1753, through M. Bacheleir, the author of & 
 treatise de I'Histoire et du Secret de la Peinture en Cire, who had actually 
 painted a picture in wax in 1 749, and he was the first who communicated to 
 the public the method of performing the operation of inustion, which is the 
 principal characteristic of the encausting painting. The cloth or wood designed 
 for the basis of the picture is waxed over, by only rubbing it simply with a 
 piece of bees' wax, the wood or cloth stretcbtd on a frame being held hori- 
 zontally over, or perpendicularly before, a fire, at such a distance that the wax 
 might gradually melt, whilst it is rubbed on, diffuse itself, penetrate the body, 
 and fill the interstices of the texture of the cloth, which, when cold, is fit to 
 paint upon. But as water colours, or those that are mixed up with common 
 water, will not adhere to the wax, the whole picture is first to be rubbed over 
 with Spanish chalk or white, and then the colours are applied to it ; when the 
 picture is dry it is put near the fire, whereby the wax melts, and absorbs all 
 the colours. Several improvements in the art of encausting painting were 
 proposed by Mr. J. H. Muntz, in a treatise by him on this subject. When the 
 painting is in cloth he directs it to be prepared by stretching it on a frame, and 
 rubbing one side several times over with a piece of bees' wax, or virgin wax, 
 till it is covered with a coat of considerable thickness. In fine linen this is 
 the only operation necessary previous to painting, but coarse cloth must be 
 gently rubbed on the unwaxed side with a pumice stone, to take off all those 
 knots which would prevent the free and accurate working of the pencil. Then 
 the subject is to be painted on the unwaxed side with colours prepared and 
 tempered with water; and when the picture is finished, it must be brought near 
 the fire, that the wax may melt and fix the colours. This method, however, 
 can only be applied to cloth, paper, or other substances through which the wax 
 can pass ; but in wood, stone, metals, or plaster, the method previously described 
 may be observed. In the year 1787, Miss Greenland, an amateur of painting, 
 communicated to the Society of Arts the knowledge of this art which she had 
 acquired during her residence at Florence, and at the same time made a present 
 to the Society of a picture executed by herself in this manner, and for which 
 the Society awarded her their honorary reward of a gold pallet. The following 
 are her instructions. " Take an ounce of white wax, and the same weight of 
 gum mastich, powdered. Put the wax in a glazed earthen vessel over a very 
 slow fire, and when it is quite dissolved throw in the mastich, a little at a time, 
 stirring the wax continually until the whole quantity of gum is perfectly melted 
 and incorporated ; then throw the paste into cold water, and when it is hard 
 take it out of the water, wipe it dry, and beat it in one of Mr. Wedgwood's 
 mortars, observing to pound it first in a linen cloth, to absorb some drops of 
 water that will remain in the paste, and prevent the possibility of reducing it to 
 a powder, which must be so fine as to pass through a thick gauze. It should 
 be pounded in a cold place, and but a little while at a time, as after long beating
 
 472 ENGRAVING. 
 
 the friction will in a degree soften the wax and te gum, an 
 becoming a powder, they will return to a paste. Make strong gum arabia 
 water, and when you paint, take a little of the powder, some colour, and mix 
 them together with the gum water. Light colours require but a small quantity of 
 the powder, but more of it must be put in proportion to the body and darkness 
 of the colours ; and to black there must be almost as much of the powder as 
 colour. Having mixed the colours, and no more than can be used before they 
 get dry, paint with fair water, as is practised in painting with water colours, a 
 ground on the wood being first painted of some proper colour, prepared in the 
 same manner as is described for the picture ; walnut-tree and oak are the sorts 
 of wood commonly made use of in Italy for this purpose. The painting should 
 be very highly finished, otherwise, when varnished, the tints will not appear 
 united. When the painting is quite dry, with rather a hard brush, passing it 
 one way, varnish it with white wax, which should be put into an earthen vesss} 
 and kept melted over a very slow fire till the picture is varnished, taking great 
 care that the wax does not boil. Afterwards hold the picture before the fire, 
 near enough to melt the wax, but not to make it run ; and when the varnish is 
 entirely cold and hard, rub it gently with a linen cloth. Should the varnish 
 blister, warm the picture again very slowly, and the bubbles will subside. 
 When the picture is dirty, it need only be washed with cold water." Almost 
 all the colours that are used in oil painting may be employed in the en- 
 caustic method, and many which cannot be admitted in oil painting, as red 
 lead, red or piment, crystals of verdigris, and red precipitate of mercury, may 
 be used here. The crayons used in encaustic painting are the same with those 
 used in the common way of crayon painting, excepting those that are in their 
 composition too tenacious, and the method of using them is the same in both 
 cases. The encaustic painting has many peculiar advantages ; though the 
 colours have not the natural varnish or shining they acquire with oil, they have 
 all the strength of painting in oil, and all the airiness of water colours, without 
 partaking of the apparent character or defects of either ; they may be looked 
 at in any light, and in any situation, without any false glare ; the colours are 
 firm, and will bear washing ; and a picture after having been smoked and then 
 exposed to the dew, becomes as clean as if it had just been painted. In 
 retouching the new colours unite with the old ones. 
 
 ENCHASING, or CHASING. The art of enriching and beautifying gold, 
 silver, and other metal work, by some design or figures represented thereon in 
 low relievo. It is practised only on hollow thin works, as watch cases, &c., 
 and is performed by punching or driving out the metal from the under side, 
 so as to stand out prominent from the plane or surface of the .metal. In order 
 to effect this, a number of steel blocks or puncheons are provided of different 
 sizes, and the design being drawn upon the surface of the metal, the workman 
 applies the inside upon the heads or tops of these blocks directly under the 
 lines or parts of the figures ; then with a fine hammer striking on the metal 
 sustained by the block, the metal yields and the block makes an indenture or 
 cavity on the inside, corresponding to which there is a prominence on the out- 
 side, which is to stand for that part of the figure, and by successive applications 
 of the hammer to the various parts of the design, the whole figure is brought out 
 with a precision and efiect which it seems almost impossible to produce by such 
 simple means. 
 
 ENGINE, among practical men, is a term used synonymously with machine ; 
 but some eminent writers on Mechanics affect to distinguish it as designating 
 more complicated structures than ordinary machines, notwithstanding which 
 discrimination, these same writers define a cannon, which consists essentially 
 of only one piece or part, as an engine ; and a jacquard loom, which essentially 
 consists of several hundred parts, as a machine ! 
 
 ENGRAVING. The art of producing figures or designs upon metals, 
 stone, wood, and various other substances, by means of lines cut upon the sur- 
 face. In this extensive sense of the term, the art is doubtless of very great 
 antiquity, repeated mention being made in Scripture of seals, signets, and other 
 works of the graver; but the word usually signifies the art of producing
 
 ENGRAVING. 473 
 
 designs as above for the purpose of being subsequently printed upon paper, 
 which copies are also called engravings ; and in this sense of the term the art 
 does not appear to have been known or practised in Europe until the middle of 
 
 the fifteenth century. In the present day it is held in very great esteem, and 
 is very extensively practised. It may be divided into two branches, according 
 to the substances upon which the design is engraved, which is generally either 
 metal or wood, although glass and other substances have been occasionally em- 
 ployed. Of the metals, copper has, until within these few years, been almost 
 exclusively chosen for engraving, on account of its ductility, evenness of tex- 
 ture, and the softness and delicacy of the tints which may be produced upon it ; 
 but latterly, steel plates have been very extensively employed for this purpose, 
 and although the engravings thus produced are perhaps somewhat inferior in 
 softness to those obtained from copper, a very high pitch of excellence has 
 been attained, and in point of durability the copper-plates will bear no com- 
 parison with steel-plates. Engraving on copper is performed in various styles, 
 the principal of which are, line engraving, mezzotinto, etching, and aquatinta. 
 Line Engraving is considered as the highest department of the art, and is 
 always employed in the illustration of historical subjects. In this style of 
 engraving the lines are all cut upon the copper by means of an instrument 
 called a graver, the roughness being removed by a triangular steel instrument 
 called a scraper. To trace the design upon the plate (which for every style of 
 engraving should be of the best copper well planished and burnished), it is 
 usual to heat the plate sufficiently to melt white wax, with which it must be 
 covered equally with a thin film, and then suffered to cool; the drawing is 
 copied in outline with a black lead pencil on paper, which is then laid with the 
 pencilled side upon the wax, and the back rubbed gently with a burnisher, 
 which will transfer the lead to the wax. The design is then traced with an 
 etching needle through the wax on the copper, when on wiping it clean it will 
 exhibit all the outlines ready for the engraver. 
 
 Mezzotinto Engraving differs entirely from the manner above described, and 
 is chiefly employed for portraits and imitations of Indian ink drawings. The 
 mode of proceeding is as follows : the plate is prepared by scratching it 
 equally in every direction with a tool called a grounding tool, so as to remove 
 entirely the polish from the surface, which is thus converted into a chaos of 
 intersections, which, if covered with ink and printed, would present a perfectly 
 black impression upon the paper. To transfer the design to be scraped, it is 
 usual to rub the rough side of the plate with a rag dipped into the scrapings of 
 black chalk, or to smoke it with a burning wax taper, as in the process of 
 etching. The back of the design is then covered with a mixture of powdered 
 red chalk and flake white, and laid on the plate, and the outline of the design 
 "being lightly traced with a blunt point, the red particles at the back are thus 
 transferred to the black ground of the plate in the form of a corresponding 
 outline ; the process must then be carried on with a scraper, by restoring the 
 plate in the perfectly light parts of the intended print to a smooth surface, from 
 which the gradations are preserved by scraping off more or less of the rough 
 ground, but the burnisher is necessary to polish the extreme edges of drapery, 
 &c., when the free touch of the brush in painting represents a brilliant spot of 
 light. The deepest shades are sometimes etched and corroded by aquafortis, 
 and so blended with the mezzotinto ground added afterwards, that there is 
 nothing offensive to the eye in the combination. Many proofs are required to 
 ascertain whether the scraping approaches the desired effect, which is done by 
 touching the deficient parts with white or black chalk on one of the proofs, and 
 then endeavouring to make the plate similar by further scraping, or by relay- 
 ing the ground with a small tool made for this particular purpose, where too 
 much of the roughness has been effaced. 
 
 A third method of engraving consists in corroding the various lines by 
 means of aquafortis, the remaining parts of the plate being defended from the 
 action of the acid by being covered with a thin stratum of a composition which 
 resists its effects. This method is termed etching, and is employed both for 
 preparing the outline in other styles of engraving, and also for filling in and
 
 174 ENGRAVING. 
 
 completing a picture ; and the prints so produced resemble pen and ink draw- 
 ings. This style is distinguished for the inimitable spirit and freedom of which 
 it admits. The first stage of the process is the preparation of the plate, by 
 covering it with a thin even film of the composition or ground, as it is termed, 
 which is to protect it from the acid. This ground is a combination of asphaltum, 
 gum mastich, and virgin wax, melted over a fire in an iron pot. A piece of 
 this ground is tied on a piece of lustring for use, and another piece of silk is 
 made into a dabber by tying a quantity of cotton wool in it. The copper-plate, 
 secured at one corner by a hand vice, is to be held over a charcoal fire, and the 
 silk containing the ground rubbed over until every part is covered by the melted 
 composition ; and before it cools, the silk dabber is applied in all directions, 
 until the surface of the plate is thinly and equally varnished. When this is 
 completed, several lengths of wax taper twisted together are to be lighted, and 
 the plate being held in the left hand by the vice, the right holding the wax 
 taper, is to be waved gently to and fro under the ground, carefully avoiding 
 touching it with the wick, yet causing the flame to spread smoothly over the 
 surface, which will render it perfectly black, smooth, and shining in a short 
 time. The next object is to transfer the design to the ground, which may be 
 done either by making a tracing with a black lead pencil, or with vermilion, 
 upon thin paper, and applying it carefully to the plate, pass the plate through a 
 rolling-press ; or the back of the design may be rubbed with red chalk and fas- 
 tened to the plate at the corners, and the outline then gone carefully over with 
 a blunt tracer. The outline thus prepared is then gone over with an etching 
 needle, which cuts through the ground ; but particular care must be taken that 
 the point of the needle, though taper, be rounded, so as to avoid the possibility 
 of its tearing the surface of the copper, which would prevent the progress of the 
 point, and ruin the plate when bitten. The different shades and tints are then 
 worked up by the needle, the arrangement of the lines of which they are com- 
 posed depending entirely upon the taste and judgment of the artist. When 
 the etching is completed, the edges of the plate are surrounded by a high 
 border of wax, so well secured that water will not penetrate between it and the 
 plate. The best spirits of nitre must then be diluted with water, in the pro- 
 portion of one part of the former to four of the latter, and poured upon the 
 plate. In a short time numerous small air bubbles collect over every line 
 traced by the needle through the ground ; these bubbles are caused by the 
 action of the acid upon the copper, and must be removed with a feather. When 
 it is judged that the lighter tints are sufficiently corroded, the acid is poured off 
 the plate, which is then washed, suffered to dry, and the light parts stopped 
 out, as it is termed, that is, covered with a composition of turpentine, varnish, 
 and lamp black, diluted so as to be used freely with a camel's-hair pencil ; this 
 prevents the aquafortis from touching these parts again. After this the acid is 
 again applied until the next depth of tint is obtained, which parts are in their turn 
 stopped out ; and thus the process continues, alternately biting in and stopping 
 out, until every gradation of tint is obtained. The ground is then removed by 
 covering the plate with olive oil, heating it, and then wiping it with a piece of 
 old linen dipped in spirit of turpentine, which effectually removes all remaining 
 dirt. If upon proving the plate, any part should be found not sufficiently cor- 
 roded, it must be rebitten, which is effected by applying the ground so care- 
 fully as not to fill in the lines, but merely to protect the surface of the plate ; 
 and then raising a border of wax round the parts to be rebitten, apply the acid 
 as before. When the operations of etching and rebiting are entirely finished, 
 nothing remains to be done but to examine the plate attentively, and improve 
 it with the graver and dry point. 
 
 The last style of copper-plate engraving which we shall notice is the aqua- 
 tinta. The prints from an aqua-tinted plate greatly resemble a neatly-tinted 
 Indian ink drawing. This effect is produced by covering the plate with a 
 thin coating of various substances finely granulated, which defend it from 
 the acid where they cover it, whilst the interstices amongst the particles or 
 grains are corroded. The first step is to lay an etching ground, and to bite in 
 lightly the outline, after which the plate is cleaned and polished with whi f ing,
 
 ENGRAVING. 475 
 
 previous to laying the grain. The best mode of laying the grain is as follows : 
 common resin, gum mastich, or Burgundy pitch, is dissolved in highly rectified 
 spirits of wine of the best quality ; each of these substances produce a different 
 description of grain, of which that from resin is the coarsest ; but they may be 
 mixed in such proportions as the artist prefers, who, to satisfy himself on this 
 point, should try the grain of each proportion on useless slips of copper. Having 
 obtained a solution to his mind, it must remain undisturbed until every impure 
 particle has subsided, when it is poured upon the plate, which is held slightly 
 slanting, until the most fluid parts run off, after which it is laid to dry, in the 
 progress of which the resin granulates, and adheres firmly to the surface. The 
 grain being thus laid, the various tints are obtained by biting in and stopping 
 out, as in etching. 
 
 Another style of engraving has been introduced within these few years, called 
 machine engraving or ruling, in which the lines are ruled with a diamond point 
 on an etching ground, by means of a machine invented for the purpose by the 
 celebrated Lowrie. This machine is capable of producing lines straight or 
 waved, and either parallel or converging to any given point, as also parabolas, 
 hyperbolas, and most other geometrical curves and circles varying from a point 
 to a five-feet radius. The lines thus ruled are afterwards bitten in, in the usual 
 manner, as in ordinary etching. This style is now universally employed for 
 architectural and mechanical subjects, as also for putting in the buildings and 
 skies in the works of line engravers. 
 
 Steel Engraving, as we have already said, is extensively employed in the 
 illustration of works of which very large editions are printed, on account of the 
 durability of the steel plates, which is so great, that artists' proofs have 
 sometimes been taken after 20,000 impressions have been thrown off, whereas 
 a copper-plate will generally require touching after 1500 or 2000 impressions. 
 But before steel can be cut by the graver it requires to be softened, by depriving 
 it of a portion of its carbon, which is effected by imbedding the steel to the 
 depth of half an inch on all sides in a bed of pure iron filings, contained in a 
 cast iron box with a well closed lid. In this box the steel is to be exposed 
 for four hours to a white heat, after which it is to be suffered to cool very 
 slowly, which is best effected by shutting off all access of air ,to the furnace, 
 and covering the box with a layer of fine cinders to the depth of six or seven 
 inches. After the steel plate has been engraved, (which engraving may be in 
 any of the styles practised on copper,) it requires to be hardened or reconverted 
 into steel, which is effected by the following process : a suitable quantity of 
 leather is reduced to charcoal, by exposing it to a red heat in an iron retort for 
 a sufficient length of time ; a cast iron box, whose cavity is about an inch 
 greater than the thickness of the steel plate, is then to be filled with this 
 charcoal reduced to a fine powder, and being covered with a well-fitted lid, it 
 is to be exposed to a heat somewhat above a red heat, until all the volatile or 
 evaporable parts are driven off from the charcoal. The lid is then removed, 
 and the plate immersed in the charcoal, as nearly as possible in the middle, so 
 as to surround it on all sides with a stratum of uniform thickness. The lid 
 being replaced, the box must remain in the degree of heat before described, 
 from three to five hours, according to the thickness of the plate. After 
 remaining in the fire the requisite time, the plate is taken from the box and 
 plunged immediately into cold water, from which it must be withdrawn before 
 the hissing noise has ceased ; but the precise point for this cannot be explained 
 in words, and can only be learned by actual observation. The plate is then to 
 be immediately laid over a fire, until its temperature is raised to that degree 
 that smoke would arise upon rubbing the surface with tallow, when it must be 
 again plunged into water, where it remains until the hissing sound becomes 
 somewhat weaker than before. The process of heating and cooling is then to 
 be twice repeated, after which, the surface of the plate is to be cleaned, and 
 the temper finally reduced by heating it over a fire, until it acquires such a 
 shade of colour as denotes that the steel is of the fit quality for the required 
 purpose. For the process above described for softening and then rehardening 
 teel plates, we are indebted to Mr. Perkins, it constituting an important branch
 
 476 ENGRAVING. 
 
 of an art invented by that gentleman, and to which lie has given the name of 
 Siderographia. By means of this truly wonderful invention, not only are en- 
 graved steel plates obtained, whose durability is unknown, (since Mr. Perkins 
 states that he has taken 500,000 impressions from one plate,) but a plate being 
 engraved, other plates may be produced from it, which shall be fac similes of 
 the original. The method by which this astonishing effect is obtained is as 
 follows : A steel plate is engraved or etched in the usual way ; it is then har- 
 dened. A cylinder of very soft steel, of from two to three inches diameter, is 
 then made to roll backwards and forwards on the surface of the steel plate, 
 until the whole of the impression from the engraving is seen on the cylinder in 
 relievo ; after this cylinder has been hardened, it is made to roll backwards and 
 forwards on a copper or soft steel plate, and a perfect fac simile of the original 
 is produced of equal sharpness. But not only is perfect identity thus obtained, 
 but the two styles of work, viz. copper-plate printing and letter-press may be 
 beautifully combined, by means of the process of transferring and retransferring. 
 This invention is admirably adapted to the prevention of forging bank notes, as 
 by this means several first rate artists may be employed at one time to produce 
 portions of a plate in detached parts, which may afterwards be combined and 
 arranged in any order to produce a single plate, and before the note could be 
 imitated by forgers it may be called in and a new note issued, consisting of the 
 same parts differently arranged; the principle, also, offers various other mode: 
 of defeating attempts at imitation. The invention has accordingly been ver> 
 extensively patronfzed by the banks in America from its outset ; and at the 
 present time the notes of most of the provincial banks in this country are pro- 
 duced by this process, some of them presenting the most beautiful specimens 
 of the art of engraving ever witnessed. The bank of England, however, for 
 reasons which are variously stated, has declined availing itself of the advantages 
 which the plan holds out, and after going to an expense of more than 30,0007. 
 in endeavouring to improve the quality of its notes, and to render them more 
 difficult of imitation, still continues to issue the same wretched description of notes 
 as have been so extensively and successfully counterfeited for many years past. 
 Wood Engraving is a process which is the reverse of copper-plate engraving, 
 for in the latter, the incisions made in the metal receive the ink and print the 
 design, while hi the former, the raised parts form the design, receive the ink, 
 and transfer the subject to the paper. Accordingly, in engraving a block of 
 wood, the subject of which is to be represented by black lines, all those parts of 
 the space occupied by the design, which are not drawn upon, are entirely cut 
 away, whilst aU the permanent lines of the drawing are left 
 untouched by the graver, as shown in the subjoined profile 
 sketch of a face. In work of this kind it is obvious that the 
 engraver can easily produce a perfect fac-simile of the artist's 
 drawing ; in fact, his manual skill only is exercised to leave 
 the lines of the design untouched, by carefully cutting away 
 all the wood, and so deep that no other part of the block 
 shall take the printer's ink from the dabber or roller, and 
 that the paper in printing shall not reach the sunken parts. 
 The process of clearing away the wood without damaging 
 the lines of the drawing, is, of course, a nice operation ; 
 nevertheless, a learner in the space of two or three months 
 acquires such dexterity with his little tools, that he cuts away nearly as fast as 
 he can move his hand or fingers. Before, however, the engraver commences 
 to "clear out" his work he "outlines it," which consists in carefully running a 
 very sharp narrow-pointed graver along both sides of the lines of the drawing ; 
 this insures more accuracy and clearness in the subsequent operation, and to 
 prevent the back of the graver from injuring the lines of the design, the engraver 
 occasionally in difficult parts defends the lines by covering them with a thin 
 piece of metal, which he holds down upon the work with the fingers of his left 
 
 A much easier, and therefore cheaper mode of engraving on wood, is to make 
 white lines on a black ground, as represented in the engraving on the next page.
 
 ENGRAVING. 
 
 477 
 
 In this case the block of wood is supposed, as in the former case, to have the 
 profile drawn upon it, but instead of leaving the artist's lines upon the wood, he 
 cuts them away alone, leaving the rest of the wood the same 
 true plane it was before. The latter, therefore, receives the 
 ink, and delivers it upon the paper, while the incisions, taking 
 up no ink, leave their traces like white lines upon the paper. 
 This mode of engraving on wood is, therefore, analogous to 
 that upon copper plates, but the inking is different; as in the 
 latter case the ink is rubbed into the lines or incisions, leaving 
 the surface clean, and therefore the lines only of the copper 
 plate are imprinted. The taste of a wood engraver is most 
 exercised in softening the shadows and graduating the lights 
 of his subject. A consideration of the following sketch will explain to the reader 
 the principle upon which the engraver works. In the upper figure the strong 
 light upon the top of it is produced by first cutting 
 down in mass the upper surface at that part, by shelving 
 sides to the cavity made, so that when 
 
 or inclining the si 
 
 the parallel straight lines or tint is cut, their extremities 
 become so extremely fine and tapering, that they can 
 scarcely receive or deliver any ink, by their being sunk 
 below the plane of the other parts. In the distance it 
 will be noticed that the lines are very near together, 
 to give the effect of distance, while those in front are 
 comparatively wide apart, to give the effect of nearness. These different spaces 
 are produced by gravers of different breadths of point. For this purpose the 
 engraver provides himself with six or eight tinting gravers, which he numbers 
 from 1 to 6 or 8, taking them up and changing them in his work as the subject 
 requires. In the figure underneath, it will be seen that a strong light and a very 
 deep shadow are brought very near together, but without offending the eye by 
 too great abruptness. This is effected by continuing the white lines of the 
 light part by lines of diminished thickness over the black or solid part, with a 
 fine graver. A very close imitation of copper engraving may be made upon 
 wood, so as to have great force and clearness in some kind of subjects, but can 
 only be afforded by the engraver when he is duly paid for the great extra labour 
 attending it. This consists in crossing the lines in the manner shown by a little 
 bit at a, in the bottom corner of the preceding figure. The diamond-shaped 
 pieces are every one picked out by the graver, and these, in some fine wood 
 engravings, are extremely minute; nevertheless, the lines, however fine, are 
 left clear and unbroken. To show the freedom, ease, rapidity, and consequent 
 cheapness with which white lines may be executed 
 upon a black ground, we have added the annexed 
 illustrated cut, which was executed by an expert I 
 engraver in the space of three or four minutes. The ! 
 wood made use of is mostly box, the best of which 
 comes from Turkey. The tree is cut into slices j 
 transversely to the grain, and then rendered to a true 
 plane and smoothed. On this fine compact surface 
 the subject is drawn, either with black lead pencil or 
 with Indian ink; but the latter is preferable (except for 
 works of high finish), as it is not so liable to be effaced 
 during the process of engraving. The art of engraving 
 on wood is coeval with the art of printing, in Europe, 
 the earliest books being printed from wooden blocks, each block comprising a 
 page, as is the method at the present day in China, in which country the art, 
 it is said, has been practised so far back as the Christian era. After flourishing 
 for a time in Europe, the art seems to have fallen into neglect, from which it 
 was first rescued in England by the celebrated Bewick, since whose time it has 
 risen gradually in repute and eminence, and now occupies a respectable station 
 amongst the fine arts. The superior utility of wood engraving consists in the 
 great durability of the blocks, but more especially in the peculiar advantage it 
 3 P
 
 478 EQUIVALENTS. 
 
 possesses of ranging with type, and being printed with it ; which renders it 
 particularly adapted for the illustration of mathematical and mechanical subjects, 
 us the necessary diagrams and figures can be introduced in the body of the 
 letter press, wherever it is most convenient for the elucidation of the subject. 
 The blocks may likewise be stereotyped along with the type, as is now very 
 generally practised with standard works. 
 
 ENTABLATURE, in Architecture, is that part of an order of a column 
 over the capital; and comprehends the architrave, frieze, and cornice. Mr. 
 Nicholson, author of The New Practical Builder, says, "In buildings upon 
 magnificent scales, projections, similar to the entablatures just mentioned, art 
 carried round the edifices, and, where the expenses are limited, along the front 
 only : these projections are also termed entablatures." In this sense the term 
 is applied by engineers to similar parts of the framing of machinery wherein 
 architectural designs are introduced. 
 
 EPICYCLOID, in Geometry, a curve generated by a point in one circle, 
 which revolves about the circumference of another circle. They are distin- 
 guished into exterior and interior epicycloids. An exterior epicycloid is formed 
 by revolution of a generating circle upon the convexity of the quiescent circle ; 
 and an interior epicycloid is formed by its revolution along the concavity of the 
 quiescent circle. A curious property of the latter description of epicycloid is, 
 that when the diameter of the generating ckcle is equal to the radius of the 
 quiescent circle, the epicycloid described is a right line equal and coincident 
 with the diameter of the latter. Mr. Murray, of Leeds, applied this property 
 to obtain a rotatory motion of the fly-wheel of a steam engine directly from 
 the piston rod, without the intervention of a connecting rod. Epicycloids have 
 been recommended by many eminent mathematicians as the best curve for the 
 teeth of wheels ; but in practice they are usually formed of circular arcs, as 
 these work very well, and are easier of construction. 
 
 EQUATION, in Algebra, is an expression in which two quantities, differently 
 represented, are put equal to each other by means of the sign = placed between 
 them, as 3 ab=d. 
 
 EQUILIBRIUM, in Mechanics, signifies an equality of forces in opposite 
 directions, whereby the body remains at rest, or in equilibrio ; in which state 
 the least additional force being applied on either side, motion will ensue. 
 
 EQUIVALENTS, CHEMICAL. A term happily introduced into chemistry 
 by Dr. Wollaston, to express the system of definite ratios in which the corpus- 
 cular objects of this science combine, referred to a common standard of unity. 
 The two grand laws of chemical combination are, 1st, The general reciprocity 
 of the saturating proportions ; and 2d, The definite proportions in which bodies 
 combine ; and if any substances are capable of combining in more than one 
 proportion, such combinations are always multiples, or submultiples of one of the 
 proportions. The first of these laws was discovered by Richter, in 1792, who 
 inferred it from the remarkable and well established fact that two neutral salts, 
 in mutually decomposing each other, give birth to two new saline compounds, 
 always perfectly neutral. Thus sulphate of soda being added to muriate of 
 lime, will produce perfectly neutral sulphate of lime and muriate of soda. 
 From this he concluded that the quantities of two alkaline bases adequate to 
 neutralize equal weights of any one acid, are proportional to the quantities of 
 the same bases requisite to neutralize every other acid. For example : 6 parts 
 of potash, or 4 of soda, neutralize 5 of sulphuric acid ; and 4.4 of potash neu- 
 tralize 5 of nitric acid. Therefore to find the quantity of soda equivalent 
 to the saturation of this quantity of nitric acid, we need not make any experi- 
 ment, but merely compute it by the proportional rule of Richter. Thus as 
 6 : 4.4 : : 2.93, the weight of soda required to saturate 5 parts of nitric acid ; 
 and this proportion of 6 to 4, or 3 to 2, will pervade all the possible saline 
 combination of these bases, so that it will require only two parts of soda to 
 saturate as great a quantity of any acid as could be saturated by three parts of 
 potash. The doctrine that bodies combine chemically in certain definite pro- 
 portions, was first promulgated by Dr. Higgins, in his Comparative View of the 
 Phlogistic and Antiphlogistic Theory, published in 1789. This doctrine wa
 
 ESSENTIAL OILS. 479 
 
 subsequently maintained by Mr. Dalton, in his New System of Chemical Philosophy, 
 first framed about the year 1803, and published in 1808. In this work Mr. 
 Dalton fully establishes the proposition that bodies do not combine in all pro- 
 portions, as Berthollet maintained, but that the different compounds of the same 
 principles proceed in successive proportions, each a multiple of the first. This 
 proposition has been further illustrated and confirmed by the researches and 
 reasonings of the most eminent chemical philosophers, and is now universally 
 admitted to be true. In the first part of the Philosophical Transactions, appeared 
 Dr. Wollaston's description of his scale of chemical equivalents ; an invention 
 which has contributed more to facilitate the general study and practice of 
 chemistry, than any other invention of man. This singularly useful con- 
 trivance consists of a flat ruler, about 2 inches wide and 1 8 inches long, on 
 which a list of substances are arranged on one or other side of a logarithmic 
 line of numbers, in the order of their relative weights, and at such distances 
 from each other that the series of numbers placed on a sliding scale can at 
 pleasure be moved, so that any number expressing the weight of a compound 
 may be brought to correspond with the place of that compound in the adjacent 
 column. The arrangement is then such, that the weight of any ingredient in 
 its composition, of any reagent to be employed, or precipitate that might be 
 obtained in its analysis, will be found opposite the point at which its respective 
 name is placed. For example: If the slider be drawn upwards till 100 cor- 
 responds with muriate of soda, the scale will then show how much of each 
 substance contained in the table is equivalent to 100 of common salt. It 
 shows with regard to the different views of this salt, that it contains 46.6 dry 
 muriatic acid, and 53.4 of soda, or 39.8 sodium, and 13.6 oxygen; or if viewed 
 as chloride of sodium, that it contains 60.2 of chlorine, and 39.8 sodium. 
 With respect to reagents, it may be seen that 283 nitrate of lead, containing 
 191 of litharge, employed to separate the muriatic acid, would yield a pre- 
 cipitate of 237 muriate of lead ; and that there would then remain in solution 
 nearly 146 nitrate of soda. These, and many more such answers, appear at 
 once by bare inspection, as soon as the weight of any substance intended for 
 examination is made by motion of the slider to correspond with its place in the 
 adjacent column. Dr. Wollaston took, as his standard or unity, oxygen, from 
 its almost universal relation to chemical matter, and determined the equivalents 
 of other substances by their relation to this standard. Sir H. Davy proposed 
 as unity, hydrogen, which is the lightest of all known substances, and which, 
 therefore, seems preferable as the basis of the scale, since the equivalents of 
 all other substances must necessarily be expressed in all numbers without frac- 
 tions ; and this scale has, accordingly, been extensively adopted. 
 
 ERMINE. A fine description of fur, obtained from the skin of an animal 
 of the same name. 
 
 ESSENCES. Several of the volatile or essential oils are called essences by 
 the perfumers. 
 
 ESSENTIAL OILS, (called also volatile and ethereal,) are distinguished 
 from fixed or fat oils, from the circumstance of their rising in distillation at 
 temperatures below that of 320 Fahr. by themselves. They are mostly 
 obtained from odoriferous vegetable substances, although some of the principles 
 are found in animal matter. In different vegetables these oils are found 
 variously lodged, sometimes in the bark, as in cinnamon ; sometimes in the 
 root, as in the plant that yields the true camphor ; sometimes in the wood, as 
 in the cedar; sometimes in the leaves, as in mint, balm, &c. ; sometimes in the 
 flowers, as in the carnation and rose ; sometimes in the rind, as in the orange 
 and lemon ; and, in a great variety of instances, in the seeds or fruit. The 
 plants should be collected at the time their scents are the most powerful, and 
 in most instances it is preferable to dry them previous to distillation, to get rid 
 of some of the acid juices of the sap of the plant, which, by enabling the water 
 with which they are distilled to dissolve more of the oil than it otherwise would, 
 would diminish the produce. The drying of the plants should, if possible, be 
 in the sunshine, but where this is not practicable, it should be effected as quickly 
 as possible on a kiln. Woods must be reduced to shavings ; barks, and similar
 
 \ SO ESSENTIAL OILS. 
 
 substances, to a gross powder; and these in general require to be soaked 
 for some days before they are distilled, in water sharpened with salt, or a 
 little muriatic acid. The still, if of copper, should be well tinned inside, and 
 have a low head, that the oil may not have to rise high. The old alembic 
 answers well, with the simple mode therein adopted of condensing at the capital 
 or head, either by a small reservoir of water fixed thereon, or by enveloping 
 the head with flannel, and allowing water to drip upon it. No more water 
 should be added than is necessary to bring over the oil, and prevent the matter 
 from burning in the still ; hence, the goods should be first floated with water, 
 and then more added by weight or measure, to determine the necessary quantity. 
 In goods that yield their oil easily, about six times their weight is sufficient ; 
 but in others which yield their oils with difficulty, as the woods, about ten times 
 their weight must be added. The distillation is conducted with a quick fire, 
 until the quantity of water that was added is come over ; and if the last portions 
 bring over any oil with them, the fire is slackened, and the distilled water 
 returned into the still, and brought over a second time ; sometimes it is found 
 necessary to distil it a third time. As some oils congeal at a low temperature, 
 it becomes necessary that the condenser be not kept so cold as to produce that 
 effect, but at that temperature by which the oils would preserve their liquid 
 form, in order that they may flow out into a receiver. And as it is difficult to 
 clean out the convoluted worms of ordinary condensers, those with straight or 
 zigzag tubes are preferable where more than one kind of oil is made, otherwise 
 the odour of one would be mixed with another. The quantity of oil which 
 comes over being extremely small in comparison with that of the water, it is 
 proper to have a receiver that will allow the water to run off into another 
 vessel, while it retains the oil. The water used in a previous distillation may 
 be advantageously used in a second, and sometimes a third distillation, to save 
 that portion of the oil which always combines with fresh water. It is, however, 
 to be observed, that by frequent cohobation, the water acquires acid properties, 
 and then takes up a larger quantity of oil, and diminishes the produce. 
 Roses should be distilled with their green flower cups, and be torn open with 
 the nails, as the liquid or scented oil is lodged in a cell at the claw of each 
 petal. By adding a little muriatic acid to the water, and digesting for a few 
 days, the produce is doubled. The essential oil of bitter almonds requires 
 particular treatment, and the distillation should be conducted in the open air, 
 to prevent the deleterious effects' of its vapours, which cause severe head-ache 
 and fainting to all persons within its influence. The usual process consists first 
 'oi pressing the almonds, to separate the fixed oil, and then grinding the resulting 
 oil cake to a coarse powder. Thirty pounds of this powder is then to be dis- 
 tilled with eight gallons of water, until the whole is come over, when there will 
 be found floating about three-quarters of an ounce of essential oil ; this is to be 
 taken off, and then as much salt as the water will dissolve is to be added to it, 
 and about a gallon of this being distilled, a further produce of four or five 
 ounces of the essential oil will result therefrom. The essential oil of tur- 
 pentine, called also spirit of turpentine, is prepared by distilling turpentine in 
 iron stills with a condensing apparatus, until the drops of oil begin to grow 
 coloured. One hundred-weight of turpentine yields from twelve to twenty 
 pounds of oil ; the product is found to be greater in proportion to the slowness 
 of the operation. For medical purposes the turpentine is either distilled with 
 water, or rectified with it, but as a portion of water thus combines with it, it is 
 not adapted to painters' use. The essential oils of aniseed, camomile, caraway, 
 cassia, cinnamon, cloves, dill, juniper berries, mint, nutmegs, penny-royal, 
 peppermint, rue, sassafras, savine, and wormwood, are used in medicine as 
 carminatives and stimulants. Those of aniseed, caraway, cassia, cinnamon, 
 cloves, juniper, and pepper, are used in compounding the cordial waters of 
 the spirit dealers. A tiiird class, as those of balm,. citron flowers, lavender, 
 orange flowers, roses, rosemary, sandal, thyme, are used to scent and flavour 
 spirits of wine, to make what are called toilet waters, as eau de Cologne, 
 Hungary water, &c. which are employed as cordials. The essential oils of 
 balm, calamus aromaticus. camomile flowers, caraway seeds, hyssop, lavender
 
 LUDIOMETRY. 481 
 
 flowers, marjoram, milfoil, parsley, rosemary, sage, sassafras, thyme, are used 
 to scent soaps. 
 
 ETHER. See ^ETHER. 
 
 EUDIOMETRY. The measurement of the quantity of oxygen contained 
 in atmospheric air," or, indeed, in any gas in which it is not intimately com- 
 bined, is named eudiometry, and the instrument by which it is performed is 
 named the eudiometer. There are two modes of effecting this ; either by pre- 
 senting to the oxygen any substance having a strong affinity for oxygen, or by 
 exploding it with hydrogen in a strong glass vessel by means of the electric 
 spark, and in either case estimating the quantity by the decrease in the bulk of 
 the gas. In the first method, the substances usually employed to absorb the 
 oxygen, are either phosphorus, sulphuret of potash, or nitrous gas, which 
 latter substance, when used according to the directions of M. Gay Lussac, 
 seems preferable to any other ; these directions are as follows : Take a very 
 wide tube or tumbler, for example, invert it in water, and having introduced 
 into it 100 parts of the air to be examined, pass into it 100 parts of nitrous 
 gas. There is instantly exhibited a red vapour, which is nitrous acid gas, and 
 which being very soluble in water, disappears speedily without agitation, and 
 after a minute at most the absorption is complete ; then transfer the residuum 
 into a graduated tube, and it will be found that the absorption is almost 
 uniformly 84 parts, provided atmospheric air was used ; and as nitrous acid 
 (the resulting compound) consists of three volumes of nitrous gas and one 
 volume of oxygen, one-fourth of the absorption, equal 21 parts, indicates the 
 quantity per cent of oxygen. M. Gay Lussac shows by numerous experi- 
 ments, the accuracy of the above process in varied circumstances. There is 
 this great advantage attending it ; that the proportion of oxygen gas being 
 estimated by an absorption four times greater than its own volume, the 
 errors of experiment are reduced to one-fourth. The analysis of combustible 
 gases, and the supporters of combustion, reciprocally by explosion with the 
 electric spark, furnishes, when it can be applied, one of the most elegant and 
 speedy methods of chemical research ; but is attended with some danger, from 
 the liability of the tube to burst, if a close tube is used, or with a risk of failure 
 from the ejection of the mercury when the tube is merely sealed by that fluid. 
 This has given rise to several modifications of the apparatus, most of which are 
 somewhat complex and costly ; but that invented by Dr. Ure, and communicated 
 by him to the Royal Society of Edinburgh, is at once simple, cheap, and 
 effective. It consists of a glass syphon, having an interior diameter of from 
 two-tenths to four-tenths of an inch. Its legs are nearly of an equal length, 
 each being from six to nine inches long. One end is open and slightly funnelled ; 
 the other end is hermetically sealed, and has .inserted near it by the blow-pipe 
 two platina wires. The outer end of one wire is incurvated across, so as nearly 
 to touch the open end of the tube ; the outer end of the other wire is formed 
 into a small hook, to allow a little spherical button to be attached to it when 
 the electric spark is to be transmitted. To use it, the whole syphon must be 
 filled with water or mercury, then plunge the open leg into a pneumatic trough, 
 and introduce into it any convenient quantity of the gases from a glass measure 
 tube, containing them previously mixed in determinate proportions. Then, 
 applying a finger to the orifice of the syphon, remove it from the trough, 
 and transfer the gases into the sealed leg, by holding the syphon Teg 
 uppermost. Then bring the mercury to a level in both tubes, by adding or 
 displacing a portion, and note carefully the volume of gas in the sealed leg, which 
 should be graduated to one hundredth parts of a cubic inch. Then applying 
 again the fore finger to the orifice, so as also to touch the end of the platina 
 wire, bring the pendant ball or button to the electric machine, and transmit the 
 spark. After the explosion, on gradually sliding the finger to one side, and 
 admitting the air, the mercury will rise in the sealed leg more or less above that 
 in the other ; then pour in mercury till the equilibrium be restored, and read 
 off, as before, the bulk of the remaining gas, and the difference of the two 
 
 volumes will denote the true quantity of oxygen, without requiring any 
 So perfectly is the shock of the explosion deadened 
 
 reduction or allowances.
 
 432 
 
 EVAPORATION. 
 
 by the elasticity of the air confined between the finger and the surface of the 
 mercury in the open end of the tube, that nothing but a slight push or pressure 
 at the tip of the finger is felt, even when the included gas is in considerable 
 quantity and of a highly explosive nature ; and the projection of the mercurv 
 or displacement of the gas is obviously impossible. 
 
 EVAPORATION. A term generally used to signify the dissipation of the 
 volatile parts of a compound body, whether caused by the action of the sun 
 and atmosphere, or by artificial means ; although some authors restrict the use 
 of the word to the former case, and employ the term vaporization in the latter. 
 A distinction is likewise drawn in the case where the volatile parts are the 
 objects of the process, which is then termed distillation ; but the fixed parts, or 
 the residuum, are the products sought by evaporation. The vessels are 
 accordingly different, evaporation being commonly carried on in open shallow 
 vessels, and distillation in vessels nearly closed from the external air. The 
 degree of heat must be duly regulated in evaporation. When the fixed and 
 more volatile matters do not differ greatly in their tendency to fly off, the heat 
 must be very carefully adjusted ; but in other cases this is less necessary. As 
 evaporation consists in the assumption of the elastic form, its rapidity will be 
 in proportion to the degree of heat and the diminution of the pressure of the 
 atmosphere ; a current of air is likewise of service in this process. Dr. Ure, in 
 his Chemical Dictionary, mentions the following method of evaporating liquors, 
 as being practised in some large alum manufactories. A water-tight stone 
 cistern, about three or four feet broad, two feet deep, and from twenty to forty 
 feet long, is covered over by a low brick arch. At one extremity of this tunnel 
 a grate is built, and at the other a lofty chimney. When the cistern is filled, 
 and a strong fire kindled in the reverberatory grate, the flame and hot air 
 sweep along the surface of the liquor, raise the temperature of the uppermost 
 stratum almost instantly to near the' boiling point, and draw it off in vapour. 
 The Doctor observes, that the great extent, rapidity, and economy of this 
 process recommend it to general adoption on a large scale. 
 
 More recently, Mr. Jacob Perkins has obtained a patent for a novel mode of 
 forming steam of very high pressure, by confining the water under mechanical 
 pressure, in a boiler properly constructed for the purpose and intensely heated ; 
 
 Fig. I. 
 
 Fig. 2: 
 
 and subsequently he obtained another patent for an adaptation of that appa- 
 ratus for the evaporating of water and other fluids. For this purpose the 
 high pressure steam is projected from the generator through pipes which 
 circulate through the evaporating pans or boilers; and such an arrangement is
 
 EVAPORATION. 18?, 
 
 made, that the water produced by the condensation of the steam is returned 
 into the generator by means of valves and a force pump, the steam or water 
 being always under mechanical pressure. The preceding engravings give 
 a sectional elevation and a plan, and the same letters of reference apply to 
 similar parts in each figure, a is the generator ; b the forcing pump ; c a pipe 
 opening into, and projecting from the upper part of the generator at d, and 
 opening to, and projected from the lower part of it, opposite to e ; f is a pipe 
 leading from the pipe c to the forcing pump ; g is a valve ; h a vessel, containing 
 the liquid to be boiled or evaporated ; andj a safety valve. At I, in the plan, 
 is a valve opening into the generator; it is not seen in Fig. 1, but is in a line 
 with the part marked e in that figure. When steam is admitted from the 
 generator into the pipe c c, it becomes condensed in heating the surrounding 
 fluid in the vessel h, and collects in the form of water at the valve g. Upon 
 raising the handle of the forcing pump, the valve g opens, and the water fills 
 that portion of the pipe marked /, between the pump and the valve g, the 
 pressure in the generator keeping the valve at the opening I shut. When the 
 handle of the force pump is depressed, the valve g shuts, and the water being 
 prevented, in consequence, from returning into the pipe c, necessarily forces 
 open the valve at /, and is returned into the generator ; and this operation is of 
 course successively repeated at every stroke of the piston rod of the pump. 
 
 Messrs. Beale and Porter's patent method of applying heat for the purposes 
 of evaporation, consists in the use of various fluids as media for the communi- 
 cation of heat, which rise in vapour or boil at different degrees of temperature; 
 so that one substance may be chosen as proper for one process, and another 
 substance or combination of substances may be employed as more suitable for 
 other processes, the nature of these substances being such that, under the ordinary 
 pressure of the atmosphere, each will indicate a known and unvarying degree 
 of heat at its boiling point, which may be communicated to any substance 
 exposed to its action. Amongst the numerous substances suitable for heating 
 media, are the following: Spirits of turpentine, which boils at 316 Fahr., and 
 naphtha, which boils at 400 Fahr. ; and by distilling coal tar, and collecting the 
 products at different periods, various other bodies are obtained, which will 
 furnish different degrees of heat ranging between 400 and 700 Fahr. By 
 this arrangement it was expected that the maximum degree of heat would be 
 always and altogether independent of accident or want of skill, so that no 
 injury from burning could possibly arise, except through the employment of an 
 improper medium, which, as fluids may be chosen whose boiling points vary 
 between the range of 200 and 700 Fahr., need never occur. The mode of 
 applying this principle to boiling or distilling, is, by using a double vessel, 
 having one part placed within the other, so as to leave a small intermediate 
 space. Into this space the substance intended to form the medium must be 
 introduced, in sufficient quantity to cover the flat bottom of the outer vessel, to 
 such a depth as to secure it from injury by means of the fire. When this 
 fluid is made to boil, it will give off vapour of the same temperature, which, as 
 it comes in contact with the surface of the inner vessel, will part with its heat 
 thereto, and, resuming the fluid form, will fall again to the bottom of the vessel, 
 to be again vaporized; and so on, in a constant alternation of evaporation and 
 condensation. To keep up a communication between the fluid medium and the 
 atmosphere, and avoid thereby all tendency to rupture or explosion, a tube, open 
 at both ends, is introduced into the intermediate space between the vessels. 
 Should there be gross mismanagement of the fire, some portion of the vapour 
 would be forced up this tube ; it is therefore made to pass through a condenser, 
 the action of which will return the fluid to the double vessel, so that little or no 
 waste of the fluid medium will be sustained. This mode of evaporating has, 
 we understand, been applied with great advantage in the refining of sugar, a 
 substance so liable to injury from an excess of heat, that the most complex and 
 expensive plans have been resorted to in order to avoid the danger of burning. 
 The plan has likewise been successfully adopted in several large medicinal 
 laboratories, and is equally valuable to distillers, dyers, and, in short, almost 
 every process in the arts where a steady uniform temperature is of importance
 
 484 
 
 EVAPORATION. 
 
 The diagram here given will show the great simplicity of the plan, and the little 
 chance there is of injury to the apparatus from the fire, as it comes in contact 
 only with a surface always protected 
 by a fluid which rapidly absorbs and 
 carries off the caloric. The engraving 
 represents the apparatus as adapted to 
 the purpose of sugar refining, a the 
 evaporating pan ; b b the outer pan, 
 containing c, the fluid medium, repre- 
 sented by dotted lines, and which, for 
 the purposes here described, is a 
 modified product, by distillation of 
 coal tar, which furnishes vapour at the 
 fixed degree of 350 Fahr. d the 
 breathing pipe, which, in the event of 
 injudicious firing, will serve as an out- 
 let and condenser for such portion of 
 the vapour as may not otherwise be 
 condensed by the comparatively cold 
 surface of the evaporating pan a ; e an ordinary furnace ; / the ash pit. 
 
 Air, it is well known, has a great affinity for vapour, and large quantities of 
 water are evaporated by the process of nature, even at the temperature of the 
 atmosphere, wherever a large surface is exposed to the action of the air. Taking 
 advantage of this fact, Mr.Cleland has contrived a new and singularly elegant 
 method of evaporating the aqueous parts of syrups and saline solutions. The 
 principle of the invention consists in continually exposing a thin film (if the 
 expression may be allowed) of the liquid to the joint action of heat and air, and 
 by that means effecting a rapid evaporation. The apparatus consists of a con- 
 voluted worm of great length, heated by steam in the interior, which is made 
 to revolve horizontally upon its axis, partly immersed in the liquid under 
 evaporation, which is thereby constantly taken up by it in the thinnest possible 
 
 stratum ; and being in contact with the hot surface of .the metal, the aqueous 
 portion of the matter is quickly formed into steam, and carried off by the sur- 
 rounding air. a is the boiler or vessel affording steam, which may therefore be 
 imagined as set over a furnace ; b is a shallow vessel, containing the syrup to 
 be concentrated, and cc. placed upon the boiler as to form the top or cover to it ; 
 c c is the worm, supported by stPi's upon an axis d d, which has a cavity at
 
 EXCAVATING MACHINES. 485 
 
 each end communicating with the worm. One end of d is supported in n 
 stuffing-box e upon a hollow arm /, which communicates with the boiler, and 13 
 pierced with numerous small holes in that part which turns in the stuffing-box ; 
 the other end of the axis d is supported by a solid arm g, and is open at the 
 extremity for the emission of the steam after it has passed through the numerous 
 coils of the worm. The axis may be turned by a winch h, or by a pulley k, or 
 receive its motion from any convenient prime mover. By this excellent 
 arrangement it will be seen that the steam in the boiler acts upon the bottom 
 of the evaporating pan, and raises the temperature of its contents; at the same 
 time it passes by the hollow arm / through the small apertures in the axis d 
 into the worm c ; herein it traverses through all the turns, and escapes finally 
 at the opposite end of the axis into the atmosphere. The lower part of the 
 worm reaches to but, a small depth in the syrup, and by turning the worm, 
 every portion of it becomes covered with the liquid, and lying in contact with 
 an extensive heated surface, vapour is given off, which is quickly absorbed by 
 the surrounding atmosphere. 
 
 EVOLUTE, in the higher Geometry, a curve, which, by being gradually 
 opened, describes another curve. It may be described mechanically by un 
 winding a string, to which is fastened a tracer, from off a cylinder or any other 
 curve. 
 
 EXCAVATING MACHINES, for digging and removing earth in extensive 
 excavations, have occupied the attention of many ingenious men, and various 
 machines for the purpose have been proposed and tried with different degrees 
 of success. The great difficulty appears to consist in adapting any peculiar 
 arrangement of mechanism which shall be capable of digging into the various 
 kinds of earth. Were it only to operate upon a uniform mass, like soft clay, 
 the task would be comparatively of easy accomplishment. Mr. G. V. Palmer, 
 of Worcester, appears to hcve devoted himself with great assiduity to the con- 
 struction of an efficient excavating engine, and to have expended considerable 
 sums in its attainment. In 1830 he took out his first patent " for a machine to 
 cut and excavate earth," which we have perused at the Inrolment Office. This 
 machine is designed, by the application of steam power, to loosen, dig up, and 
 remove into a cart, earth from a canal or other cavity, and to move itself 
 forwards as the excavation proceeds. In principle its leading arrangement 
 resembles the dredging machines employed in clearing the beds of rivers and 
 harbours ; but it has several appurtenances, such as picks, for loosening the 
 earth, cutters, for separating it, and scrapers, for filling it into the scoops or 
 elevators, which convey it into the cart by which it is moved away. The machine 
 is mounted upon four wheels, and gradually moves forward upon a temporary 
 railway as the excavation proceeds. The moving power is applied to the axis 
 of a fly-wheel, and to the same axis is fixed a drum or pulley, around which 
 passes an endless pitched chain, that gives motion to another drum or pulley, 
 which revolves in bearings fixed to the upper ends of two long cheeks or supports. 
 Around this second drum passes another endless chain, which gives motion to 
 a third drum or pulley, which is of a quadrangular figure, and turns on an axis 
 in the lower ends of the long cheeks ; to this last-mentioned chain are fastened 
 a series of earth scoops, which are successively brought into operation in taking 
 up the earth. So far the machine resembles the common ballast engine ; we 
 have therefore to describe how the several actions of picking, digging, ami 
 projecting the earth are effected. A third endless chain is actuated by the 
 drum on the main axis, and gives motion to a spur-wheel, which drives another 
 toothed wheel attached to the fore wheels of the carriage, which gradually 
 advances it. By an ingenious system of levers, connected to a crank on the 
 main axis, a row of pick-axes, a row of cutters, and a row of scraping shovels, 
 are alternately brought into action. When the pickers have descended and 
 loosened a portion of earth, the cutters succeed, and separate it from the mass, 
 and this separated portion is immediately afterwards drawn forwards by the 
 scraping shovels into the sccops, which, by the action of the machine, are 
 brought into the required position on one of the sides of the revolving quadran- 
 gular drum ; the filled scoops thence proceeding to the top of the machine by 
 S Q
 
 486 EXPANSION. 
 
 the revolution of the attached endless chains, discharge their contents into a 
 cart or waggon to be conveyed away. The same gentleman patented another 
 engine for this purpose in 1832. This consisted of an excavating cart and 
 plough united, to be worked by horses or other power. The cart wheels are 
 made considerably wider than those in common use, and the interior portion of 
 the ring of each wheel is made into a series of earth boxes; these earth boxes are 
 made to open inwards, and also towards the centres of the wheels. Underneath 
 the cart, immediately adjoining each wheel, is placed a plough, for raising and 
 turning the earth into the boxes, as the cart is moved forwards ; the wheels at 
 the same time turning round, bring up the earth and deliver it into the body 
 of the cart. When a sufficient load has been thus deposited in the cart, the 
 ploughs are raised from the ground by means of a lever, and then the cart can 
 be drawn in every respect as a common cart, to the place intended for the 
 deposition of the excavated earth, where it is to be unloaded by withdrawing a 
 pair of bolts, which allow the bottom of the cart to fold downwards sufficiently 
 to permit the earth to escape. There are many circumstances where the appli- 
 cation of excavating machinery of this kind might be employed to advantage. 
 Under the head BARROW will be found some useful information relating to this 
 subject, which we have repeatedly seen practised on the great scale. 
 
 EXHALATION is distinguished from evaporation by some writers, as not 
 applying to the raising of vapour in the ordinary sense of the word, but to 
 subtle, dry effluvia, loosened, by the action of the sun, from minerals and other 
 hard terrestrial bodies ; that these exhalations ascend until their specific gravity 
 equals that of the surrounding atmosphere, where, mixing with other vapours, 
 they help to form clouds, and return to the earth in mists, dews, rains, &c. 
 
 EXPANSION, in Natural Philosophy, the enlargement or increase of bulk 
 in bodies, chiefly by means of heat. This is one of the most general effects of 
 caloric, being common to all bodies whatever, whether solid, fluid, or in 
 the aeriform state. Metals expand in the following order, those that expand 
 most being placed first: zinc, lead, tin, copper, bismuth, iron, platina. 
 The degree of expansion produced in different liquids varies considerably. In 
 general, the denser the fluid, the less the expansion ; water expanding more 
 than mercury, and alcohol more than water. The various elastic fluids, or 
 gases, on the contrary, all expand equally, the expansion being about one four 
 hundred and fortieth part of their bulk at 32 Fahr. for every degree of heat. 
 But elastic fluids are capable of expanding indefinitely without the application 
 of heat, by the mere enlargement of the containing vessel ; since whatever be 
 its capacity, they must necessarily be equally diffused, and press with equal 
 force in every part of it, the pressure being inversely as the bulk of the gas. 
 This property of elastic fluids has been turned to great advantage in steam 
 
 engines, by admitting steam of high pressure info the cylinder during a portion 
 of the stroke, and then shutting off the communication with the boiler ; tho
 
 EXPERIMENTAL PHILOSOPHY. 
 
 487 
 
 expansion of the steam in the cylinder carries the piston with a constantly 
 decreasing force through the remaining portion of the stroke, by which mode 
 of working the whole effect produced during the expansion of the steam is 
 clear gain. Upon this subject Mr. J. Perkins, who has employed steam of 
 greater expansive force than perhaps any other person, observes, that there is 
 great economy in using very high steam expansively, and that the higher 
 the steam can practically be used, the sooner it may be cut off. The preceding 
 diagram shows (approximately) the gain in cutting off the steam at a quarter 
 stroke. Let the piston, which is represented by the line k 1 a descend to i b, 
 being one quarter of the stroke, with a constant force of 400 Ibs. per square 
 inch. At this point let the steam be cut off and expand to double its volume ; 
 when it arrives at h c it will be exerting a pressure of 200 Ibs. per square inch, 
 producing a mean pressure of 300 Ibs. per square inch through the quarter 
 stroke. Let the steam again expand to double its volume, and the piston will 
 finish its stroke at f e at 100 Ibs. per inch, giving a mean of 150 Ibs. through 
 the last two quarters; to which add 400=the 
 pressure during the first quarter, and 300=the 
 pressure during the second, and the sum will be 
 1,000, giving a mean pressure of 250 Ibs. on the 
 inch throughout the whole stroke. It will be 
 seen that when the stroke is completed, the cylin- 
 der will be filled with steam of 100 Ibs. pressure 
 per square inch, which will be the same in 
 quantity as though the steam Iiad begun at a 
 pressure of 1 00 Ibs. and continue at that pressure 
 throughout the strok-5 { but in this case the sum 
 of the pressure through the four quarters would 
 only be 400 Ibs. so that by using the same quantity 
 of steam expansively, thsre is a gain of 150 per 
 cent. By employing two cylinders, the pistons 
 of which act upon cranks at right angles to 
 each other, a compensation is obtained for the 
 varying pressure of the steam ; for whilst one 
 piston is at its greatest power, the other is 
 acting with diminished power, so as to render 
 the force exerted nearly the same throughout 
 the revolution, as will be seen by the diagram. 
 The annexed figure represents an instrument 
 for showing the expansive force of steam 
 at different temperatures. At the bottom 
 of a strong spherical vessel of brass is placed a 
 quantity of mercury sufficient to fill the long 
 vertical glass tube above ; over the mercury is 
 the water to be converted into steam, by a spirit 
 lamp placed beneath. The long tube is sub- 
 merged in the fluid, so as to nearly touch the 
 bottom ; on one side of this tube a thermometer 
 is fixed in an inclined position, its bulk projecting 
 towards the centre of the vessel. On the application of heat, the water is con- 
 verted into steam, which, by its expansive force, presses upon the surface of 
 the mercury, and impels it up the long tube, where its pressure is noted 
 upon a graduated scale ; at the same time, the height of the mercury in 
 the thermometer shows the temperature of the steam. 
 
 EXPERIMENTAL PHILOSOPHY. That philosophy which proceeds on 
 experiments, and deduces the laws of nature, and the properties and powers 
 of bodies, and their ajtion upon each other, from sensible experiments and 
 observations. The business of experimental philosophy is to inquire into and 
 investigate the reasons and causes of the various appearances and phenomena 
 of nature, and to maka the truth or probability thereof evident to the senses, by 
 plain, undeniable, and adequate experiments, representing the several parts of the
 
 488 FACE GUARD. 
 
 rnd machinery and agency of nature. Sir Isaac Newton, the greatest master 
 the science, lays down four rules by which to guide our inquiries into 
 nature. 1st, More causes of natural things are not to be admitted than 
 are both true and sufficient to explain the phenomena ; 2d, and therefore, of 
 natural effects of the same kind, the same causes are to be assigned, as far as it 
 can be done, as of respiration in man and beasts ; of light in a culinary five 
 and in the sun ; and of the reflection of light in the earth and in the planets. 
 3d, The qualities of natural bodies, which cannot be increased or diminished, 
 and agree to all bodies in which experiments can be made, are to be reckoned 
 as the qualities of all bodies whatever ; thus because extension, divisibility, 
 hardness, impenetrability, mobility, the vis inertiae, and gravity, are found in 
 all bodies which fall under our own cognizance or inspection, we may justly 
 conclude they belong to all bodies whatsoever, and are, therefore, to be 
 esteemed the universal and original properties of all natural bodies. 4th, In 
 natural philosophy, propositions collected from the phenomena by induction, are 
 to be deemed (notwithstanding contrary hypotheses) either exactly or very nearly 
 true, till other phenomena occur by which they may be rendered either more 
 accurate, or liable to exception. This ought to be done lest arguments of 
 induction should be destroyed by hypothesis. These four rules of philoso- 
 phizing are premised by Sir Isaac Newton to his third book of the Principia, 
 and more particularly explained by him in his Optics, where he exhibits the 
 mode of proceeding in philosophy. 
 
 EXPLOSION, in Natural Philosophy, a sudden and violent expansion of an 
 aerial or other elastic fluid, by which it instantly throws off any obstacle that 
 may be in the way. It differs from expansion in this, that the latter is a 
 gradual and continued power, whereas the former is always sudden and of only 
 momentary duration. 
 
 EXPONENT, in Algebra, is a number placed over any power or involved 
 quantity, to show to what height the root is raised ; thus 2 is the exponent of 
 x 3 , and 4 is the exponent of a; 4 , or xxxx. 
 
 EXTRACT. Mixtures of several of the principles of vegetables, reduced 
 by decoction either to a solid, or to the consistence of paste. The word is also 
 applied by modern chemists to denote a peculiar substance supposed to be one 
 of the immediate principles of vegetables, and the same in all when separated 
 from any foreign admixture, except as the proportions of its constituent prin- 
 ciples may vary. 
 
 F. 
 
 FACADE, or FACE, in Architecture, the side of a building in which is the 
 principal entrance ; also that exterior part of a building which is projected or 
 advanced beyond the main body. 
 
 FACE GUARD. A kind of mask to defend the face and eyes from acci- 
 dents in various chemical and mechanical processes. A guard intended to pre- 
 serve the face, and particularly the eyes of smiths, founders, and others, from 
 being injured either by the heat of the furnace or of red hot melted metal, or 
 of fragments of metals dispersed by the hammer, is described in the Trans- 
 actions of the Society of Arts. The guard is of two forms, either a veil of iron 
 wire-gauze of a curved form, and fastened by a hinge to the front part of the 
 hat ; or a mask, more or less complete, with the eye-holes covered with wire- 
 gauze. There is not much novelty in the invention itself, but there is in its 
 application to persons exposed to the radiant heat of furnaces, whose eyes, it is 
 well known, often become much injured thereby. The great utility of it for 
 these purposes, has been testified by a number of persons who have recently 
 adopted their use, and have expressed their surprise at the trifling heat which 
 they, in consequence, felt upon their faces. The author of this invention, Mr. 
 Callaghan, received a reward for it from the Society ; and we have no doubt 
 that its adoption by those classes of workmen for whose use it was designed, 
 would prove highly beneficial to them.
 
 FAT. $ : -.' % 489 
 
 FACETS, in Crystallography, the flat surfaces which bound the angles of 
 crystals. 
 
 FACIA, or FASCIA. A broad flat projecting part of a building, as the 
 bands of an architrave, larmier, &c. 
 
 FACTOR, in Arithmetic, a name given to the multiplier and multiplicand, 
 as their quantities multiplied together constitute the product or factum. 
 
 FAKE. One of the circles or windings of a cable or hawser, as it lies dis- 
 posed in a coil. 
 
 FAN. A machine used to agitate the air, and cause it to impinge upon 
 other bodies to reduce their temperature. Those used for cooling the person 
 are made of every variety of form and materials that fancy can invent ; but 
 they generally consist of a piece of paper, satin, or any other light fabric, cut 
 semicircularly, and mounted upon several little sticks of wood, ivory, tortoise- 
 shell, or the like. If the stuff be single, the sticks of the mounting are placed 
 on the least ornamented side ; if double, they are placed betwixt them. The 
 paper is plaited in such a manner that the sticks may be alternately inward 
 and outward. In the middle of each plait the sticks are cemented ; all of 
 which are cut exceedingly thin and delicate, and they are connected together at 
 the end by a single rivet, by which the fan, as it is held in the hand, may be 
 either folded up or expanded. The Chinese and East Indians excel in elabo- 
 rate carving upon the fan sticks ; but the elegance and taste displayed by our 
 own artists upon the other parts, are unrivalled. The term fan is applied to 
 those small vanes or sails that receive the impulse of the wind, and, by a 
 connexion with machinery, keep the large sails of a smock windmill always 
 in the direction of the wind ; see WINDMILL. Also a rotative blowing machine, 
 consisting of vanes turning upon an axis, used for winnowing corn. Similar 
 apparatus is used to decrease the speed of light machinery, by the resistance of 
 the air against the motion of the vanes. 
 
 FARINA implies generally vegetable flour. The flour of the Parisian 
 bakers (which it may be presumed is chiefly, if not wholly, wheaten,) was 
 ascertained by M. Vauquelin to consist of gluten 10.2, starch 72.8, sweet 
 matter 4.2, gummy glutinous matter 2.8, and moisture 10, in 100 parts. The 
 farina of many vegetables consists almost entirely of starch, as is the case with 
 rice, arrow root, and the potatoe. The method of separating the farina from 
 the latter root is described with figures under the word BREAD. A patent was 
 granted in 1829, to Mr. Benjamin Goulson, of Pendleton, near Manchester, for 
 " certain improvements in the manufacture of farina and sugar from vegetable 
 productions." The specification explains it to consist in a method of converting 
 dahlias, beets, carrots, mangel wurzel, and other roots, by the application of 
 acid. After the roots have been well cleaned by washing, and cleared from 
 their skins by nibbing or other process, they are to be sliced or grated, and 
 steeped in a mixture of pure water and acid (the preference being given to 
 sulphuric acid), in a ratio varying from two to ten pounds of acid (according to 
 the roots operated upon,) to a hundred weight of roots. Those which possess 
 the least natural sweetness will probably require the most acid. In this 
 mixture the roots are to be kept till they become quite soft or pulpy, when they 
 are to be washed with pure water till they cease to taste of the acid. They are 
 next to be dried in the sun or in an oven, and then be ground into flour, and 
 used for making bread, or other purposes for which wheaten flour is employed. 
 To extract the saccharine matter from roots, Mr. Goulson employs a second 
 dose of diluted acid, in the proportion of from two to ten pounds of the acid to a 
 hundred weight of the farina thus obtained, and by this means the fibrous parts 
 become macerated ; after which the acid is to be neutralized and separated from 
 the saccharine portion, which is then to be clarified by the usual processes ; or 
 the saccharine matter may, by continuing the first process, and using an addi- 
 tional quantity of acid, be obtained at once without first converting the roots 
 into flour. 
 
 FARRIERY is the art of shoeing horses and administering to their diseases. 
 See HORSE-SHOE. 
 
 FAT. Animal oil in a concrete state, deposited in minute cells in various
 
 490 FEATHERS. 
 
 parts of the bodies of animala, The colour is white or yellowish ; it is insipid, 
 inodorous, insoluble in water and in alcohol, but it combines with alkalies and 
 forms soap. It absorbs oxygen by exposure to the air, and becomes rancid, 
 forming a peculiar acid, called the sebacic. It is decomposed by heat, producing 
 the sebacic acid, an empyreumatic oil, and carbonated hydrogen, leaving a 
 residuum of charcoal. Fat is oxidated by the acids, and it oxidates several of 
 the metals, when they are combined with it in the form of an ointment. Some 
 interesting information on the nature and properties of fat, and the mode of 
 separating its constituent properties, will be found under the head CANDLE. See 
 also SOAP. 
 
 FAT is also a name given to a measure of capacity, differing in different 
 commodities. Thus, a fat of isinglass contains 3 to 4 cwt. ; a fat of unbound 
 books is four bales ; a fat of wire 20 to 25 cwt. ; a fat of yarn 220 bundles. 
 
 FATHOM. A measure of six feet, used to regulate the length of cables, 
 rigging, &c., and to divide the lead or sound lines. 
 
 FEATHERS. A general name for the natural covering of birds. Chemically 
 examined they are found to differ but little from hair or bristles. Mr. Hatchet 
 boiled some feathers for a long time in water, but discovered no traces of 
 gelatine ; the quill is chiefly albumen. Feathers form a considerable article of 
 commerce, particularly those of the ostrich, heron, swan, peacock, goose, &c. 
 for plumes, ornaments, beds, pens, &c. Geese are plucked in some parts of 
 England five times a year, and in cold seasons many of them die by this 
 barbarous custom. Those from Somersetshire are esteemed the best, while 
 those from Ireland the worst; but there are exceptions to this rule, for we have 
 seen some Irish feathers equal to those imported from Dantzic and Hamburg, 
 which attain the highest price in the market from their superior strength, that 
 is, durable elasticity in the making of beds. Goose feathers are usually sorted 
 into white and grey. The latter make equally good beds with the white, but 
 their colour diminishes their value for sale to the extent of sixpence the pound 
 in the best qualities. Those feathers denominated "poultry," which are from 
 turkeys, ducks, and fowls, are of very inferior value ; for although they are soft 
 to the touch, they are too deficient in elasticity to make light or good beds. 
 Wild duck feathers are soft and elastic, but the difficulty of curing them from 
 the odour of the oil they contain, renders them less suitable than those of the 
 goose. Irish feathers have obtained a bad character from the large quantity of 
 foreign matter, particularly lime, with which they are usually mixed. A small 
 portion of lime sprinkled amongst fresh feathers tends to their preservation, by 
 combining with the oil they contain, while it also prevents the putrefaction of 
 the small portions of animal fibre that occasionally adhere to them ; but the 
 Irish peasantry, or the small dealers in Ireland, with the view of impo- 
 sition, load them to an injurious extent, which renders the cleaning of such 
 feathers a work of time and difficulty. The following process of clearing 
 feathers from their oil, and preparing them for use in making beds, was com- 
 municated to the Society of Arts several years ago by Mrs. Jane Richardson, 
 whom the Society rewarded in consequence with the sum of twenty guineas. 
 " Take, for every gallon of clean water, one pound of quicklime ; mix them 
 well together, and when the undissolved lime is precipitated in fine powder, pour 
 off the clear lime water for use. Put the feathers to be cleaned into another 
 tub, and add to them a quantity of clear lime water, sufficient to cover them 
 about three inches, after they have been well immersed and stirred about therein. 
 The feathers when thoroughly moistened will sink down, and should remain in 
 the lime water three or lour aays, aaer which the foul liquor should be separated 
 from them by laying them on a sieve. The feathers should be afterwards well 
 washed in clean water, and dried upon nets, the meshes of which may be about 
 the fineness of cabbage nets. The feathers must be from time to time shaken 
 upon the nets, and as they dry will fall through the meshes, and are to be 
 collected for use. The admission of air will be serviceable in the drying. The 
 whole process will be completed in about three weeks. After being prepared 
 as above mentioned, they will only require beating, to get rid of the dust, 
 previous to use.
 
 FELLING TREES. 
 
 491 
 
 FEATHER. A term applied by engineers to nan-ow ribs, placed edgewise, to 
 strengthen framing and other parts of machines. 
 
 FEATHER-EDGED signifies any piece of work in which the edge of it is 
 materially reduced in its thickness. . 
 
 FELLING TREES. The cutting down of trees o/N^C^X ( 
 at the proper time, and in the best manner, requires ^\ ~ 
 both knowledge and skill. Its proper season is deter- Y 
 mined by various causes, as maturity of growth, defects 
 in the trees, and new arrangements. Every tree that 
 indicates decay, ought to be immediately felled, as its 
 value will rapidly decrease. In all trees, there are three 
 stages youth, manhood, and age. The beginning of 
 manhood is the fittest period for removing trees. All 
 plantations, when arrived at maturity, ought to be cut 
 down and replanted. Winter is the proper season for 
 felling trees that are not to be disbarked ; but summer 
 is preferable for those of the resinous tribes. In spring 
 and autumn, the wood is fullest of sap; in winter and 
 summer the least so, and therefore it is the fittest time, 
 generally speaking, for levelling them. But in felling 
 oaks, and such as have to be disbarked or peeled, the 
 early part of the spring, before the leaves appear, is 
 found to be the fittest period, as the bark will at that 
 time easily separate, or " run," as the workmen term 
 it. The preparatory operation to felling, is disbranching 
 the trees of such limbs as may endanger the tree in its 
 fall. In arms of timber that are very great, it is always 
 necessary to chop or sink in them close to the bole, and 
 then meeting it with downright strokes, it will be severed 
 from the tree without splitting. In felling the tree, 
 take care always to cut it as close to the ground as pos- 
 sible, unless it is intended to be grubbed up ; and 
 the doing that is of advantage both to the timber 
 and the wood ; for timber is never so much valued, if 
 it be known to grow out of old stocks. In the clearing 
 of woodland, the extirpation of the stumps and roots is 
 the most laborious part of the process. In British 
 America, the ordinary method is to allow the stumps 
 to remain for a number of years, according to their 
 size. During this period, the smaller fibres gradually 
 decay, and the root itself is each year removed a little 
 from its original position by the frost. When the far- 
 mer judges that time has so far produced decay, as to 
 render the removal of the stumps and roots practicable 
 by the usual means, he pitches upon the spring of the 
 year, when the soil has been loosened by the returning 
 heat ; and with the assistance of four or five men, and 
 a couple of pairs of oxen, he effects his purpose, by a 
 great deal of labour, and under a disadvantageous 
 application of power, owing to the softness of the 
 ground. 
 
 I iv 1821, J. Mack ay, Esq. of Pictou, Nova Scotia, 
 cut down the trees and removed the timber from a field 
 of ten acres. The following were the means adopted 
 by that gentleman for clearing the ground of the stumps 
 and roots, which proved so effectual, that with the 
 assistance of four men he cleared upon an average 
 80 stumps a day, and with them every root which could 
 impede the progress of the plough. A ship's winch, or movable crane, was the 
 machine used for accumulating a great mechanical power j this was brought into
 
 92 FERMENTATION. 
 
 the middle of about an acre of stumps, and fastened to the largest of them. From 
 the barrel of the winch a chain proceeded, which extended to the farthest stump 
 in the piece ; a number of shorter chains were also provided, each having a 
 ring at one end, and a hook at the other. By passing the hook through the 
 ring, they were fixed upon the stumps nearest to that to which the chain of the 
 winch was attached, and when it was raised, these chains were in succession 
 hooked to the leader, so that the winch was employed without interruption, till 
 the nearest stump was extracted. In clearing Mr. Mackay's field, five hands 
 were employed; two at the winch, two in fixing the chains, and one at the 
 stump to be raised. When the stump was large, those who attended the chains 
 occasionally assisted in turning the winch. 
 
 Reference to the Engraving on the preceding page. a a the two winch handles 
 of the crane b b, which is chained to the largest stump c ; d d the leading 
 chain, proceeding from the barrel to a distant stump h, to be hooked on to the 
 leading chain d d as soon as it has raised the stump e, and has been disengaged 
 from it, so that the different stumps are raised in succession, from the farthest 
 to the nearest. The winch is then removed to face the next portion, and the 
 chain extended to the farthest it can reach, while the shorter chains are 
 attached to the right and left stumps, and hooked on in succession to the leading 
 chain, and thus continued until a whole circle round the winch has been 
 cleared. Should the stump to which the winch is attached he liable to give 
 way, it will be requisite to lash it to one or two in the rear, to secure the 
 purchase. 
 
 FELLOES, the curved pieces of wood, usually six or eight in number, 
 which, when united end to end, form the circular rim, or periphery of carriage 
 wheels, and into which the spokes are inserted. See WHEELS. 
 
 FELTING. The process by which hair, wool, or silk, is worked into a fabric 
 of firm texture, called felt, without spinning or weaving ; it is chiefly employed 
 in the manufacture of hats, and under that head will be found details of the 
 process. 
 
 FERMENTATION. When vegetables and animals are deprived of life, 
 the elements of which they are composed exert an action on each other ; some 
 of them enter into new combinations, others become entirely undecompounded, 
 and the identity of the original substance is destroyed. Fermentation is of 
 three kinds : first, the vinous ; second, the acetous ; third, the putrid. The two 
 first kinds are peculiar to vegetable substances; the last is common both to 
 vegetable and animal substances, though the change it indicates is, in reference 
 to animal substances, more usually called putrefaction. Moisture, and gene- 
 rally access of air, are necessary to fermentation; and a warm temperature 
 materially promotes it, while by an excess either of heat or cold it is entirely 
 checked. 
 
 Vinous Fermentation. The vinous fermentation never takes place except in 
 substances containing sugar, and it is most remarkable in those which contain 
 the most of the saccharine principle. If a decoction of a vegetable holding 
 much sugar in solution, or saccharine vegetable juices, or simply a mixture of 
 sugar and water, be exposed to a heat of 70 in a vessel either uncovered, or 
 not entirely closed, in a short time the fluid becomes very turbid, bubbles 
 rise to the surface and break ; mucilage is at the same time disengaged, part of 
 which sinks to the bottom, and the remainder rises to the top, where, with the 
 bubbles entangled in it, a stratum is formed, called yeast. When the quantity 
 of the fermented fluid is considerable, the operation goes on briskly for several 
 days, afterwards it becomes gradually more languid, but it is a considerable time 
 before it completely ceases. A fluid which has undergone the vinous fermentation 
 is entirely changed in its properties ; its specific gravity is diminished ; its 
 sweet taste and viscidity is gone ; it becomes brisk and transparent, and has 
 acquired a pungent spirituous flavour. It forms beer, cyder, wine, &c. according 
 to the substance which has furnished the saccharine juice ; and from whatever 
 it has been prepared, it affords, by distillation, a light inflammable fluid, called 
 alcohol. From the experiments of Lavoisier, it appears that sugar is converted 
 into alcohol by the loss of a part of its oxygen The oxygen separated is
 
 FERMENTATION. 493 
 
 employe i to form carbonic acid gas, which produces the bubbles observed on 
 the fermenting liquor. A small quantity of yeast is always added to liquors 
 intended to be fermented, as it materially accelerates and renders uniform this 
 process through the whole mass of fluid. 
 
 Acetous Fermentation. When liquors are fermented for the use of the table, 
 they are put into casks while the fermentation is yet active ; at first the bung- 
 hole is left open, and as yeast is discharged, the barrel is filled up with a part 
 of the fluid or wort reserved for that purpose ; afterwards the vessel is closed. 
 But if the fluid be allowed to remain a sufficient time in open vessels, the 
 acetous fermentation comes on, which changes its taste and smell, and converts 
 the fluid into vinegar. This change takes place most rapidly at the temperature 
 of about 90, and is promoted by changing the surfaces of the liquor by stirring 
 it, or pouring it from one vessel to another. During the acetous fermentation 
 the alcohol imbibes oxygen to a degree that converts it into an acid ; and if the 
 liquor which has undergone this process be distilled, pure vinegar, instead of 
 ardent spirit, comes over. Simple mucilage will pass to the acetous fermentation, 
 without being preceded by the vinous, or at least the vinous fermentation is so 
 transient as not to be discernible. Wines deprived of mucilage cannot be con- 
 verted into vinegar. 
 
 Putrid Fermentation. When dead vegetables contain much saccharine 
 matter, and the other circumstances necessary to fermentation are combined, 
 the vinous, the acetous, and the putrid fermentation, succeed each other in 
 regular order. When mucilage is the predominant principle of the vegetable, 
 the acetous fermentation, above described, is the first change discoverable, the 
 putrid follows of course, as it is always the last, but the vinous does not appear. 
 When albumen and gluten are predominant in the vegetable matter, the putrid 
 fermentation only is apparent. We have observed the progress of a saccharine 
 fluid, from the vinous to the acetous fermentation ; let us now trace it to the 
 putrid. When vinegar has been completely formed, and the warmth and 
 exposure to the air in which it was formed are still continued, it gradually 
 becomes viscid and turbid, an offensive gas is emitted, ammonia flies off, an 
 earthy sediment is deposited, and the remaining fluid scarcely differs from water. 
 Such is the change produced by putrefactive fermentation in a saccharine fluid. 
 When moist vegetables are heaped together in considerable quantities, their 
 putrefaction is attended with the production of considerable heat, their whole 
 texture becomes less coherent, their colour dark, and nitrogen, hydrogen, car- 
 bonic acid, and ammoniacal gases, begin to be evolved. When the putrefactive 
 process has advanced to this stage, the vegetable matter affords excellent manure ; 
 for it is obvious that the principles of vegetables are liberated, and are ready to 
 nourish the seed or the root to which the manure is applied, while the warmth 
 with which the decomposition is attended enables the seed or root more readily 
 to receive the food thus offered. The putrefaction of animal substances goes on 
 under the same circumstances that promote the putrefaction of vegetables 
 humidity, a temperature neither hot nor cold, and the access of the atmosphere ; 
 but is distinguished by a far greater noisomeness. The presence of the air is 
 the least essential particular, for putrefaction goes on in vacuo, the air required 
 being supplied by the decomposition of water. A very small quantity of salt 
 hastens putrefaction, while a considerable quantity remarkably retards it, and 
 is therefore used in the preservation of animal food. The first indication of 
 putrefaction in animal substances is a cadaverous odour, their substance becomes 
 soft, pale, then green, blue, and lastly, a blackish brown ; the smell at the same 
 time becomes more nauseous and penetrating, ammoniacal gas is perceived, 
 other gases also escape, which are of an infectious and poisonous nature ; in 
 the end, the substance loses all traces of organization, becomes dry, soft, and 
 reduced to a state resembling that of an earth. The worms and insects 
 generally found among putrefying substances are not produced by putre- 
 faction, and therefore not a necessary consequence of it ; life never springs 
 but from life, and the maggots are there because the insects from which they 
 spring, directed by instinct, have deposited their eggs among matter suitable 
 for their food. 
 
 3a
 
 494 FID 
 
 FERRETTO. A substance used in colouring glass, obtained by the calci- 
 nation of copper and powdered brimstone, or of copper and white vitriol. 
 
 FESTOON, in Architecture, an ornament in the form of a garland of 
 flowers. The term is also applied to drapery, when suspended so as to form 
 elliptic curves, with the extremities of the cloth depending. 
 
 FIBRE (VEGETABLE). A substance of great use in the arts and manu- 
 factures, furnishing thread, cordage, &c. For these purposes the filamentous 
 parts of hemp and flax are employed amongst us ; in Sweden, a strong cloth 
 is said to have been prepared from the stalks of hops ; and in India, exceed- 
 ingly serviceable cordage and cables are manufactured from the husks of 
 cocoa nut. 
 
 FIBRIN. A peculiar organic compound, found both in animals and vege- 
 tables, but procured however, in its most characteristic state, from animal mat- 
 ter. To obtain it, we may beat blood as it issues from the veins with a bundle 
 of twigs. Fibrin soon attaches itself to each stem, under the form of long 
 reddish filaments, which become white by washing them. It is solid, white, 
 insipid, without smell, insoluble in water, softens in the air, becoming viscid, 
 brown, and semi-transparent. Fibrin does not putrefy speedily when kept 
 under water. It shrinks on exposure to a considerable heat, an<3 emits the 
 smell of burning horn. 
 
 FID. A short and thick bar of wood or iron, which, passing through a hole cut 
 in the lower part of the topmast or top-gallant mast, and resting upon the trestle 
 trees, serves to support those masts. A most important improvement upon this 
 part of a ship's apparatus, is the patent lever fids, invented by Mr. Rotch, by means 
 of which ships may strike their topmasts, or top-gallant masts, at any moment, in 
 less than one minute, and fid them again in less than five minutes. The lever 
 fids consist of two powerful levers of the first class, resting upon iron plates or 
 carriages, bolted upon the upper surface of the trestle-trees, and carrying the 
 gudgeons or trunnions which form the fulcrums of the levers ; these gudgeons 
 pass through circular notches cut in the upper side of the levers, and that part 
 of the levers which rests upon the plate being formed into the arc of a circle, 
 of which the gudgeons are the centre, the whole weight of the masts is sup- 
 ported upon the carriages, instead of upon the fulcrum, which merely serves as 
 a centre of motion. The operation of fidding a mast is as follows : The mast 
 being swayed high enough for the short arms of the levers to enter the fid-hole 
 (which is defended by a very stout iron plate), the longer arms are depressed by 
 tackles hooked to their extremities until they attain a horizontal position, when 
 they are secured by lashings. To strike a mast (the top rope being rove and 
 made fast below), all that is necessary is to slack the lashings until the strain is 
 brought upon the top rope, and then to lower away. These patent lever fids 
 may be applied to any ship without any alteration in her tops, mast, or fid- 
 holes; and from the rapidity and certainty of their operations, are calculated to 
 render most important service to navigators in the most trying situations, where 
 despatch in striking a mast may be of essential consequence, as in the case of 
 a sharp ship grounding upon a rapidly falling tide, in gales of wind at sea in a 
 dark night. In the case of springing a topmast just above the cap, when 
 in chase, the lever fids will be found invaluable, as the topmast may be 
 instantly lowered until the part which is sprung is below the cap, by just 
 shaking the vessel in the wind for' half a minute, when all will be safe, and 
 she may be kept on her course again. So sensible were the Lords of the Admi- 
 ralty of the utility of this invention, that they paid to Mr. Rotch a large sum 
 for the use of it in the Royal Navy. 
 
 Mr. Rotch has subsequently taken out a patent for a prop for supporting 
 masts, by which the strain is transferred from the trestle trees to the lower 
 mast, just beneath the top, and acts in a direction nearly vertical. The cut on 
 the following page represents an outline sketch of the apparatus, a is the top- 
 mast; b the lower mast; c the fish (which is a strong piece of timber fixed to 
 the lower mast to strengthen it) shown in dotted lines ; d the cheeks of the 
 lower mast, on which are fixed the trestle-trees e; f the fid of the top- 
 mast ; g a bolt stay to the top-mast ; h, the new patent prop, bolted to the heel
 
 FILE. 
 
 495 
 
 of the top-mast by means of an iron 
 plate, connected with the hinge joint 
 upon which it turns, the other end rest- 
 ing in an angular cavity made to receive 
 it in the fish of the lower mast ; t shows 
 the position which the prop takes when 
 the top-mast is being raised or lowered; 
 the curved dotted lines o o represent the 
 form into which the trestle- trees ordi- 
 narily become bent by the action of the 
 top-mast. This latter effect is owing to 
 the trestle-trees having to support the 
 whole weight of the top-mast, with its 
 
 ends resting upon the trestle-trees. To , , 
 
 the weight is to be added the force of ' s 
 
 the wind, which has a tendency to in- . 9. 
 
 crease that effect in a tenfold degree, 
 especially when the inclined position in 
 which the masts of most ships are placed 
 is taken into consideration. If instead 
 of the fid and the trestle-trees having 
 to withstand all this force, the little prop 
 h be put into the cavity of the fish, it 
 will be seen that nearly the whole of it 
 is thereby thrown diagonally upon the 
 lower mast, which is well able to sustain 
 
 'FILAMENT. Those extremely deli- 
 cate threads of animal or vegetable pro- 
 duction, such as are produced by the silk-worm, spiders, flax, nettles, &c. ; by 
 the combination and twisting of which, threads, cordage and cloth are made. 
 
 FILE. A steel instrument employed for shaping or giving a smooth surface 
 to articles made of metal, bone, wood, &c. The varieties of files are very 
 extensive, being expressly adapted to numerous different trades or branches of 
 manufacture. There is, however, an immense variety of files which are appli- 
 cable to general purposes ; these are distinguished by the terms of flat, half- 
 round, three-square, four-square, round, hand, pillar, cant, and other technical 
 names, which denote their transverse sectional shape ; then each of these shapes 
 may be single or double cut ; that is, the notches or incisions made upon them 
 may consist of only one series of parallel lines, technically called floats, or of 
 two series, in which the lines or incisions cross each other diagonally. Then 
 again, either of these latter may be of different degrees of coarseness or fine- 
 ness, denominated in the trade, rough, bastard, second-cut, and smooth ; the 
 latter term indicating teeth so fine and close as to produce upon metal a surface 
 nearly smooth, and requiring only the aid of the burnisher to polish it. It is 
 then to be understood, that each of these classes and varieties, or most of them, 
 are made of lengths differing from two or three inches, up to twenty inches 
 long. Even these are ,not all ; there are also a numerous class of rasps, which 
 have jagged teeth, and are chiefly used in working bone and hard woods ; also 
 rubbers, which are great, heavy square files, used by smiths and others ; and a 
 peculiar class of heavy files, chiefly used by millwrights and engineers, forming 
 a medium between rubbers and files of ordinary thickness ; besides a great 
 variety ef extremely delicate files of the best steel, used by watchmakers and 
 others. When, therefore, it is considered that the file manufacture thus 
 embraces several thousand distinctions, and that many thousands of families 
 are constantly employed in their fabrication in the neighbourhood of Sheffield, 
 Birmingham, and other places, an idea of the extent and importance of it may 
 be formed. The steel employed for files is required to be very hard, and, in con- 
 sequence, undergoes a longer process in the conversion, and is said to be double 
 converted. The very heavy files are made of the inferior marks of blistered
 
 49 FILE. 
 
 steel ; those for sharpening the teeth of saws, and the more delicate kinds, are 
 made of cast steel. The steel is previously drawn at the tilt hammer into rods 
 of a suitable size. The flat and the square files are made wholly with the 
 hammer and the plain anvil. Two workmen, one called the maker the other 
 the striker, are required in the forging of heavy files, the smaller being forged 
 by one person only. The anvil is provided with a groove for the reception of 
 bosses or dies, which are used for the purpose of forging the half-round and 
 three-angled files. The half-round boss contains a hollow, which is the segment 
 of a sphere, less than half a circle. That used for the three-angled files has a 
 hollow consisting of two sides, terminating in an angle at the bottom. In 
 forging the half-round file, the steel is drawn out, as if intended to make a flat 
 file, it is then laid in the die and hammered till the underside becomes round. 
 The steel for the triangular files are tilted into square rods. The part to form the 
 file is first drawn out with the hammer, as if intended to form a square file ; it 
 is then placed in the die with one of the angles downwards, and by striking 
 upon the opposite angle, two sides of the square are formed into one, and con- 
 sequently a three-sided figure produced, which is perfected by successively 
 presenting the three sides to the action of the hammer. In forming the tangs 
 of most files, it is necessary to make the shoulders perfectly square and sharp. 
 This is performed by cutting into the file a little on both sides with a chisel, 
 and afterwards drawing out the part so marked off to form the tang. After 
 forging, and previous to being ground and cut, the files require to be annealed. 
 This process is generally performed by piling up a great quantity together in a 
 furnace for the purpose, and heating them red hot, suffering them after- 
 wards to cool slowly. This method of annealing files, and indeed any other 
 articles in which great hardness is requisite, is very objectionable, since the 
 surface of steel, when heated red hot in the open air, is so liable to oxidation. 
 A superior method of annealing is practised by some file-makers; and since 
 hardness in a file is so essential a property, the process ought to be generally 
 adopted. This method consists in placing the files in an oven or trough, having 
 a close cover, and filling up the interstices with sand. The fire is made to play 
 on every side of the vessel, as gradually and as uniformly as possible, till the 
 whole mass becomes red hot. The fire is then discontinued, and the whole 
 suffered to cool before the cover is removed from the trough. Steel annealed 
 in this way is perfectly free from that scaly surface acquired in the open air ; 
 /tnd if each corticle be perfectly surrounded with the sand, and the cover not 
 removed before the steel is cold, the surface will appear of a silvery white 
 colour. If the steel be suspected to be too kind, from containing too little 
 carbon, powdered charcoal may be employed instead of sand, or sand mixed 
 with charcoal. In this case the files should be stratified alternately with the 
 charcoal, in order that the extra conversion may be uniform. The next thing 
 is to prepare the files for cutting, by making the surface to contain the teeth as 
 level as possible. This was formerly effected by files, and the process is called 
 striping. The same is still practised by the Lancashire file-makers (who excel 
 in the manufacture), and by others not having the convenience for grinding. 
 The greatest quantity of files are, however, ground, to prepare them for cutting. 
 The stones employed for this purpose at Sheffield are of a compact and sharp 
 texture, of great diameter, and about eight inches broad over the face. When 
 used, the surface is kept immersed in water ; the grinder sits in such a position 
 as to lean over the stone, whilst its motion is directed from him. The next 
 process is that of cuttirg the files, which is performed by means of a chisel 
 and hammer on an anvil. The chisel and hammer are of such a size as the 
 size and cut of the file require. The file-cutter is also provided with a leather 
 strap, which goes over each end of the file, and passes round his feet, which 
 are introduced into the strap on each side, in the same manner as stirrups are 
 used. He therefore sits as if he were on horseback, holding his chisel witli 
 one hand, and his hammer in the other, at the same time he secures the file 
 in its place by the pressure of his feet in the stirrups. While the point of the 
 file is cutting, the strap passes over one part of the file only, while the point 
 rests upon the anvil, and the tang upon a prop on the other side of the strap.
 
 FILE. 497 
 
 When one side of the file is single cut, a fine file is run slightly over the teeth 
 to take away the roughness, when they are to be double cut ; and another set 
 are then cut, crossing the former nearly at right angles. The file is now 
 finished on one side, and it is evident that the cut side cannot be laid upon the 
 bare anvil to cut the other. A flat piece of an alloy of lead and tin is there- 
 fore interposed between the serrated surface and the anvil, while the other side 
 is cut, which completely preserves the side previously cut. Rasps are cut in 
 precisely the same way, using a triangular punch instead of a flat chisel. The 
 art in cutting a rasp is^o place every new tooth opposite to a vacant space in 
 the adjoining row of teeth. The last and most important part of file-making 
 is the hardening them. In effecting this, three things are to be observed : 1st. 
 To prepare the file on the surface, so as to prevent it from being oxidated by the 
 atmosphere when the file is red hot, which effect would not only take off the 
 sharpness of the tooth, but render the whole surface so rough that the file 
 would, in a little time, become clogged with the substance it had to work upon. 
 This is accomplished by laying a substance on the surface consisting of salt dis- 
 solved in water, and stiffened with ale grounds or common flour. When it fuses, 
 this forms a kind of varnish, which defends the metal from the action of the 
 air. 2d. The heat ought to be very uniformly red throughout, and the water 
 in which it is quenched fresh and cold, for the purpose of giving it the patper 
 degree of hardness. And lastly, the manner of immersion is of great import- 
 ance to prevent the files from warping, which, in long thin files, is very diffi- 
 cult. After the file is properly heated for the purpose of hardening, it should 
 be cooled as soon as possible. The most common method of effecting this is 
 by quenching it in the coldest water. All files, except the half-round, should 
 be immersed perpendicularly, as slowly as" possible, so that the upper part shall 
 not cool. This management prevents the file from warping. The half-round 
 file must be quenched in the same steady manner, but at the same time that it is 
 kept perpendicular to the surface of the water, it must be moved a little hori- 
 zontally in the direction of the round side, otherwise it will become crooked 
 backwards. When the files are hardened, they are brushed with water and 
 coke dust, the surface becoming of a whitish grey colour, as perfectly free from 
 uxidation as before it was heated. They may like 
 
 oxidation as before it was heated. They may likewise be dipped in limewater, 
 and dried before the fire as rapidly as possible ; after which they should be 
 rubbed over with olive oil, in which is mixed a little turpentine, and then they 
 are finished. To preserve them for use, or pack them for sale, they are wrapped 
 in stout oiled brown paper in half-dozens, the paper interposed between each 
 preventing any injin-y to the opposed teeth. 
 
 The operation of simple file cutting seems to be of such easy performance, 
 that it has for almost two centuries been a sort of desideratum to construct a 
 machine to perform that which is not only done with great facility by the hand, 
 but with wonderful expedition. It is said, that a lad not very experienced in 
 the business, will produce with his hammer and chisel nearly three hundred 
 teeth in a minute. With respect to machinery, Mathurin Jousse, in a work 
 entitled, La Fidelle Ouverture de tArt de Serrurier, published at La Flesche, in 
 Anjou, in 1627, gives a drawing and description of one in which the file is 
 drawn along by shifts by means of wheel-work, and the blow is given by a 
 hammer. There are several machines for this purpose in the Machines 
 approuvees par I'Academie Rot/ale de Paris. There is also one published in 
 the second volume of the Transactions of the American Philosophical Society ; 
 and a patent was taken out by Mr. William Nicholson, in 1802, for the same 
 object. From the knowledge, talent, and assiduity, of the last-mentioned inventor, 
 we may be assured that it was a very elaborate and judiciously-constructed 
 machine ; nevertheless it was found wanting, and never got into practical 
 operation ; files, therefore, continue to be cut as they were a century ago. 
 File-cutting is an art that appears, at first thought, extremely simple, but a little 
 investigation of the subject will convince the reader, (as it did ourselves 
 many years ago, when we designed a machine for the purpose,) that it abounds 
 with difficulties, which, though probably not of an insuperable nature, are such 
 as call for unremitting study, the devotion of much time, and the incurring of
 
 FILTRATION. 
 
 a considerable expense to occomplish. No man, therefore, should undertake it 
 who is not possessed of abundant capital, leisure, and constructive skill. In 
 the operations of filing, the coarser cut files are always to be succeeded by the 
 finer, and the general rule is to lean heavy on the file in thrusting it forward, 
 because the teeth of the file are made to cut forwards ; but in drawing the file 
 back again to make a second stroke, it is to be lifted just above the work, to 
 prevent its cutting or rubbing as it comes back. The rough file, or a rubber, 
 serves to take off the most uneven part of the work ; then follows the bastard 
 file, to reduce the file cuts or scores of the rough file, and next usually a smooth 
 file, to remove the scores of the bastard, and prepare the work for the bur- 
 nisher, if it is to be polished. 
 
 FILLAGREE WORK. A kind of enrichment on gold or silver, wrought 
 delicately in manner of little threads or grains, or both intermixed. In Sumatra, 
 manufactures of this kind are carried on to very great perfection. But what 
 renders this a matter of great curiosity is, that the tools made use of are very 
 coarse and clumsy. The gold is melted in a crucible of their own forming, and 
 instead of bellows, they blow with their mouths through a piece of bamboo. 
 They draw and flatten the wire in a 
 manner similar to that of Europeans. It 
 is then twisted, and thus a flower, or the 
 shape of a flower, is formed. Patterns of 
 them or of foliage are first prepared on 
 paper, of the size of the gold plate on wliich 
 the filagree is to be laid. According to 
 this, they begin to dispose on the plate the 
 
 arger compartments of the foliage, for 
 
 1 
 
 which they use plain flat wire of a larger 
 size, and fill them up with their leaves. 
 A gelatinous substance is used to fix the 
 work, and after the leaves have been 
 placed in order, and stuck on bit by bit, 
 a solder is prepared of gold filings and 
 borax, moistened with water, which they 
 strew over the plate, and then putting it 
 on the fire a short time, the whole becomes 
 united. When the filagree is finished, it 
 is cleaned with a solution of salt and 
 alum in water. The Chinese make most of 
 their filagree of silver, which looks very 
 elegant, but is deficient in the extra- 
 ordinary delicacy of Malay work. 
 
 FILLET, in Architecture, is a narrow 
 rectangular moulding. In the metallic 
 framing of machinery, narrow moulded 
 slips or fillets are put in the angles, to 
 facilitate the casting and strengthen the 
 structure. 
 
 FILTRATION. A process for freeing 
 liquids from particles held in suspension 
 in them, by causing them to percolate 
 through various porous substances, which 
 intercept the insoluble matter, but allow 
 a passage to the liquids, which are thereby 
 rendered clear and transparent. The 
 purpose to which filtration is most ex- 
 tensively applied, is the purification of 
 water for domestic purposes ; and from 
 the importance of pure water as regards 
 the preservation of health, and from the 
 general complaints of the impurities
 
 FILTRATION. 499 
 
 abounding in the water supplied by the different companies, the subject has of 
 late excited much attention, and a variety of filtering apparatus have been offered 
 to the public, some few of which we propose to describe. 
 
 The first of these machines which we shall notice is Messrs. White and Aveline's 
 "artificial spring," in which the water is made to filtrate upwards by its pressure 
 against the under side of a stone, the quantity filtered depending upon the area 
 of the stone, and the height of the reservoir from which the water descends ; 
 but with a head of 35 feet, which can be obtained in most houses in London, a 
 stone of 10 inches square will filter nearly thirty gallons per hour. The en- 
 graving on the opposite page exhibits a vertical section of the apparatus. a 
 is the cistern which receives the water in its impure state ; it has a ball float 
 and lever to keep a constant head of water over the pipe b, and likewise to 
 prevent any air passing down it. The pipe b b is shown broken off, that the 
 space between may be considered as of any required length. To the lower end 
 of the pipe there is a nozle c through which the pipe passes, which causes the 
 water to shoot up against the under surface of the filtei-ing stone /. Through 
 this stone the water oozes with great rapidity, leaving the animalcule and other 
 impurities in the lower part or basin e of the machine, from whence they are 
 drawn off occasionally by the cock g, and carried away by the waste pipe h. 
 When the filtered water rises in the reservoir above k to a certain height, the 
 filtration is stopped by the rising of the float I, which by its lever or rod re, shuts 
 a cock o in the supply pipe. When the stone has become charged with a deposit 
 on its under surface, it is capable of being cleansed by the scraper s which is 
 turned round by means of a handle shown at the bottom of the reservoir k, 
 the axis passing through the stone ; provision is thus made for reviving the 
 filtering properties of the stone whenever required, and with very little trouble. 
 
 A very old contrivance for filtering water, but which has been the origin of 
 most of the more recent apparatus for the purpose, consists in nearly filling the 
 two legs of a pipe, formed either of metal as in Fig. 1, or of wood as in Fig. 2, 
 with washed sand, leaving merely a space at b and e to receive the turbid water, 
 and another at c or /for the filtered water to run off by. The chief objection 
 
 to these machines is, that they soon become foul, and consequently useless, 
 until restored by cleansing, and this task, as generally performed, is such a 
 laborious, tedious, and slopping one, that these filters are usually abandoned in 
 a short time. This objection seems to be obviated in the arrangement 
 shown in the cut on the following page, a is a barrel capable of being turned 
 round, but rendered stationary by pins passing through the extremities of their 
 bearings at b b ; c is a bed of sand occupying about one-third of the cask ; d
 
 600 
 
 FILTRATION. 
 
 is the supply pipe or hose, (any flexible tube,) which conducts the turbid water 
 from a reservoir above, into the cask ; at e is a union joint and nozle piece, 
 containing a sponge, which serves three purposes: it prevents the grossest 
 impurities of the water from 
 entering among the sand ; 
 
 it prevents the column of " 
 
 water from forcing up the 
 bed of sand ; and it pre- 
 vents the sand from falling 
 into the pipe. The filtered 
 water is drawn off at /. 
 When the sand requires 
 cleaning, the pins at the 
 bearings of the axis are 
 taken out, and the winch 
 turned so as to bring the 
 union joint to the top of the 
 cask, previous to which the 
 pipe should be detached by 
 unscrewing. The sponge being now removed, the water may be let on freely 
 at top, and the barrel turned by the winch g, by which means the sand is expe- 
 ditiously washed, the water being let on and run off as often as necessary, 
 which it is obvious may be effected with so much facility, that the filtering 
 powers may be at any time renewed in a few minutes. 
 
 The following engraving, Fig. 1, represents an apparatus of a convenient form, 
 by Mr. James, of Knightsbridge. It consists of two vessels (A and B,) of stone 
 ware, placed upon a strong stand c. The upper vessel, which is covered, 
 receives the impure water in a chamber d, at the lower part of which there is 
 a large aperture, stopped by a sponge e, which detains the grosser impurities : 
 hence the water passes through a finely perforated earthenware plate into a 
 layer of six inches of prepared charcoal, through which the water filters, and is 
 
 Fig. 2. 
 
 Fig. I. 
 
 thereby purified from any noxious smells, as well as any floating impurities ; it 
 then passes through another perforated plate g, and is received at h into the 
 separate vessel, which is a stone ware cask, from which it may be drawn off at 
 pleasure by the cock. 
 
 A very convenient filtering machine, from its portability, is Wiss's patent 
 filter, which is shown in the preceding cut, Fig. 2. a is a force pump ; b a
 
 FILTRATION. 501 
 
 raction pipe, to be inserted in a pail or other vessel of water ; c the pipe which 
 conducts the water out of the pump to the top of the vessel d; e is a receiver 
 for the purified water ; / a cock for drawing it off ; g g g, screws for separating 
 the receiver from the machine when required. The filtering substances used 
 in this apparatus are of the same description as in the foregoing ones. The 
 upper portion of the filter down to the letter d in the 
 engraving, is left vacant for the dirty water which 
 first passes through a thin bed of charcoal, and then 
 through a bed of sand occupying the remainder of 
 the vessel, and supported by a perforated metal plate, 
 covered with a few layers of flannel. 
 
 A very simple method of freeing water from its 
 impurities by means of the capillary attraction of 
 fibrous substances is represented in the annexed 
 engraving, a is the reservoir, b the lower com- 
 partment, c an open tube soldered into the bottom 
 of the reservoir, in which is put a wick of cotton 
 or wool, (the latter is best,) with one end immersed in 
 the bottom of the reservoir, whilst the other end 
 hangs down a little below it, forming a kind of 
 syphon. The water in rising by the capillary 
 attraction between the filaments deposits the gross 
 matter floating therein, and descends in a compara- 
 tively pure state into the vessel b, or into a jug 
 placed therein. 
 
 The figures represented in page 502, are a portion of Mr. Suwerkrop's appa- 
 ratus for filtering and heating water. Fig. 1 shows a side elevation of the vessels 
 in question ; and Fig. 2 is a vertical section of the same. The letters have refer- 
 ence to similar parts in each figure. The water is supposed to be conveyed by 
 the pipe a from a reservoir situated upon a higher level than the cask b, which 
 is divided by the partition c into two equal parts, forming thereby a double fil- 
 tering machine. In each of these divisions, the filtering substances and the 
 arrangement of them are the same. As the water flows from a higher level, 
 it will of course ascend through the filtering substances, and flow out at the 
 upper part. The first substance which it has to pass through is a circular mat 
 d, made by coiling up and sewing together a rope of platted horse-hair, which 
 detains the grossest of the impurities ; from this it passes through a floor or 
 false bottom of wood, e, pierced throughout with numerous small holes ; upon 
 the wooden bottom is laid first a stratum of coarse gravel or small pebbles, over 
 this is put a layer of finer, then a layer of finer still, and lastly, a bed of 
 sand/, about six or seven inches thick ; from this the water rises in a tolerably 
 pure state ; if not sufficiently purified, instead of drawing it off for use, it may 
 be allowed to pass through the curved pipe h into the upper division of the 
 cask. The water continuing to rise, then percolates successively through the 
 horse-hair mat j, the perforated floor k, and the various strata of the sand and 
 gravel I, finally flowing out of the cask, and through the pipe m, into the heating 
 vat n. The vat is constructed with a furnace o, and flue p p inside of it, all 
 made of copper, except the grating for the fuel, which is made of cast iron as 
 usual ; copper being preferred for the flue on account of its oxidating less rapidly 
 than iron or other cheap materials. The heated air or gases first rise up the 
 neck q into the hollow sphere r, which becomes soon occupied with intensely 
 heated air, from whence it has little disposition to descend and escape by means 
 of the spiral tubes, which finally become flues for the grosser products of the 
 combustion ; as these tubes, however, make a long circuitous course through the 
 tub of water, the heat is almost wholly absorbed by it. The furnace and flues 
 are supported and kept in their positions by stays fixed to the sides of the vat, as 
 Bhown. The three closed apertures in the cask b, Fig. 1, are for the several 
 purposes of washing the bottoms of the horse-hair mats, by passing water through 
 them downwards ; and for taking out and refreshing the layers of sand and 
 gravel when they have become foul by deposition from the water. 
 8 s
 
 502 
 
 FILTRATION. 
 
 The engraving on the next page represents an apparatus contrived by Messrs. 
 Williams and Doyle, for the purpose of separating the salt from sea-water, by 
 merely causing it to percolate through a body of sand under mechanical com- 
 pression, and thus to render it fresh. Could this object be obtained by such means, 
 the invention would doubtless be one of the utmost importance to navigation, as 
 it would render a store of fresh water unnecessary, thereby affording additional 
 stowage for provisions or cargo ; but we are not aware of any experiments 
 proving that substances dissolved, and chemically combined with a liquid, can 
 be separated by filtration ; we therefore apprehend that the apparatus would be 
 ineffectual for the object the inventors had in view, although it may prove very 
 efficient in freeing water from any impurities floating or suspended in it The 
 following description of the engraving (which represents one of the several 
 modes of construction proposed by the inventors), is derived from the specifi- 
 cation of their patent, a is a part of the cask supposed to contain sea water ; 
 b a tube descending therefrom, made fast by bands c c c to the filtering appa- 
 ratus d d, which is a strong square trunk of wood, lined internally with sheet 
 lead, which are cemented together to prevent the interposition of water. 
 This part of the apparatus is given in section, that the construction and arrange- 
 ment may be seen at one view ; e is the lower chamber, -where the water is
 
 FILTRATION. 
 
 503 
 
 first received; / is a strong stool of open frame work, supported on five stout 
 lees a. A plan of this stool is given in a separate figure F, the situation of 
 each of the five legs being marked with a g. Over this short frame is nailed a 
 plate of copper, pierced with numerous small holes ; this plate is also shown by 
 a separate figure H. Over the perforated plate are several layers of woollen 
 cloth, or woven horse-hair i, and above these a body of sand k, filling up the 
 
 entire trunk ; on the top is placed a sliding cover /, which is operated upon by 
 a strong screw m, working through a fixed nut n, which is supported by curved 
 iron arms, extending from opposite sides of the trunk. The sand having been 
 compressed, by the agency of the screw, intc i more dense and compact mass, 
 is prevented from rising by the pressure of the water, which percolating through 
 the minute interstices to regain its level, deposits its salt, and runs out by the pipe 
 o in a fresh state into a vessel p placed to receive it. When the sand has become 
 saturated with salt, it is to be removed by taking out the screw and the press- 
 ing board I ; the man holes r r may then be opened by unscrewing the plugs,
 
 504 
 
 FIRE ENGINE. 
 
 when the other materials may be easily sifted. These matters being completed, 
 a fresh quantity of sand may be taken from the ballast of the ship, and the 
 process of filtration continued as before. 
 
 We shall close this article with a description of a very convenient apparatus 
 for filtering liquids out of contact with the atmosphere, invented by Mr. Donovan. 
 By means of this arrangement, alkalies can be preserved in their caustic state, 
 the absorption of carbonic acid by the alkali being prevented, a is a bottle of 
 green glass, with a funnel-shaped end inserted into 
 another bottle b, the junction being luted or ground to 
 fit closely ; the neck d of the upper vessel has a cork 
 tightly fitted to it, perforated in the middle for the 
 reception of the glass tube c, which being bent down- 
 wards, enters the branched neck e of the lower vessel, 
 thus connecting them together, and opening an air 
 passage between them. The funnel-shaped end of the 
 upper vessel has a piece of linen, loosely rolled up, placed 
 in it, for the purpose of filtering, but for the corrosive 
 acids a stratum of pounded flints should be employed 
 instead of the cloth. To charge the upper vessel with 
 the alkaline solution, the tube c must of course be 
 removed, and the first droppings should be allowed to 
 run to waste previously to the apparatus being fitted 
 together, that no absorption of carbonic acid may take 
 place in the filtered liquor When the whole is properly 
 closed, the filtration will proceed without the possibility 
 of absorption. Now it is evident that no liquor can fall 
 from the upper vessel without an equal volume of air 
 entering it, and that none can enter the lower without an 
 equal bulk escaping from it. Both these conditions are 
 fulfilled by the connecting tube c, the air being driven 
 from the lower into the upper vessel at every dropping 
 of the filtered liquid. The whole process is therefore 
 conducted without the access of more air than the vessels 
 at first contained, and in the most cleanly and perfect 
 manner. The utility of this contrivance is very extensive. 
 The most volatile liquids, as ether, alcohol, ammoniacal 
 
 liquors, volatile oils, &c. may be filtered without loss, as the vapours cannot 
 escape during the operation ; and by the exclusion of the atmosphere in the 
 filtration of a variety of fluids, other injurious effects to which they are subject 
 by the common process, may "be entirely obviated. 
 
 FIRE, in Natural Philosophy, combustion, or the decomposition of combustible 
 bodies, accompanied with light and heat. The word, however, has been used 
 in such various senses by philosophers of different schools, that in works of 
 close reasoning it is now generally exchanged for that of combustion, as a term 
 affording a more definite meaning. Fire, under this view of the subject, is not 
 a substance, but a quality. It supposes two or more bodies entering into com- 
 bination, attended with an emission of light and heat. All these phenomena 
 may take place separately, but it is a compound operation, resulting from the 
 union of the whole, that alone produces fire. 
 
 FIRE ARMS are all sorts of arms charged with powder and ball ; as cannon, 
 mortars, muskets, pistols, &c. See CANNON, GUN, &c. 
 
 FIRE ENGINE. An engine for projecting water upon buildings on fire. 
 Buckets composed of wood, leather, or other suitable material, were the only 
 means employed in England and on the continent for extinguishing fires, up to 
 the middle or close of the sixteenth century. The earliest mention of any 
 description of fire engine with which we are at present acquainted, occurs in 
 the building accounts of the city of Augsburg, in Germany, in the year 1518. 
 They are there described as " instruments for fires," and " water syringes, 
 useful at fires." They are stated to have been made by Anthony Blatner, a 
 goldsmith of Friedburg, who, in the year above mentioned, became a citizen of
 
 FIRE ENGINE. 505 
 
 Augsburg. These syringes appear to have been of considerable magnitude, as 
 they were mounted on wheels, and worked by levers ; they are also represented 
 to have been expensively constructed. Caspar Schott, the well-known Jesuist, 
 Btates, that small engines of this description were used in his native city 
 (Konigshofen) in the year 1617. This writer has also furnished a short account 
 of a much larger one, which he saw tried at Nuremburg, in 1657. It was 
 constructed by John Hautsch, of that place, and was mounted on a sledge ten 
 feet long by four feet broad, which was drawn by two horses. It had two 
 working cylinders placed horizontally in the cistern, which was eight feet long, 
 four feet high, and two feet broad. It was worked by twenty-eight men, and 
 threw a jet of water one inch in diameter to the height of eighty feet. This 
 is the largest and most powerful squirting engine of which we have any record. 
 The English appear to have been unacquainted with the progress made by the 
 German engineers, or to have been very slow in availing themselves of their 
 discoveries; for at the close of the sixteenth century, hand-squirts were first 
 introduced in London for extinguishing fires. They were usually made of 
 brass, of various sizes, holding from two to four quarts of water each. Those 
 of the former capacity were about two feet and a half long, and one inch and 
 a half in diameter, that of the nozle being half an inch. They were furnished 
 with handles on each side, and every syringe required three men to work it. 
 One man on each side grasped the handle in one hand and the nozle in the 
 other, while a third man worked the piston or plunger, drawing it out while the 
 nosel was immersed in a supply of water, which filled the cylinder ; the bearers 
 then elevated the nozle, when the other pushed in the plunger, the skill of the 
 bearers being employed in directing the stream of water upon the fire. In the 
 vestry-room of St. Dionis Backchurch, in Fenchurch- street, London, there are 
 still preserved several of these syringes, the property of that parish. They are 
 said to have been used at the great fire in 1666, when one of the set (originally 
 six) was lost, and several others much damaged. These syringes present a 
 valuable and interesting relic ; for although the number of them formerly dis- 
 persed throughout the city was once very great, very few indeed of them are 
 now to be seen. Soon after the commencement of the seventeenth century 
 the Londoners perceived the convenience that would arise from fixing these 
 squirts in a portable cistern, and applying their power through the medium of 
 a lever: the fire engine thus obtained was considered a great mechanical 
 achievement. The advantages resulting from this arrangement were certainly 
 considerable, as they permitted a larger syringe to be used, which could be 
 worked easier, as well as much faster, than the hand squirt. This simple form 
 of engine, however, had many inconveniences ; they projected the water by 
 spurts only, a cessation of the stream taking place between each stroke of the 
 piston, in consequence of which a great deal of water was lost, and a difficulty 
 was experienced in accurately projecting the stream. To be useful, it was also 
 necessary to place these engines very close to the fire, which exposed the 
 persons working them to imminent danger from the falling of the burning 
 buildings. That these engines were but imperfectly constructed, and deficient 
 in strength, we learn from a recorded circumstance, that three of them which 
 were taken to extinguish a large conflagration on London bridge, in 1633, and 
 were then considered " such excellent things, that nothing that was ever devised 
 could do so much good, yet none of these did prosper, for they were all broken." 
 The following description of an engine of this kind has been handed down to 
 us by Mr. Clare, in his work on the Motion of Fluids, published in 1735. 
 " Engines for extinguishing fires," he observes, " are either forcing or lifting 
 pumps, and being intended to project water with great velocity, their effect in 
 great measure depends upon the length of their levers, and the force with 
 which they are wrought. A common squirting engine which was constructed 
 on the latter principle, consisted of a large circular cistern, like a great tub, 
 mounted upon four small solid wheels, running upon axletrees, which supported 
 the vessel. A cover or false bottom, perforated with numerous small holes, 
 was fixed inside the cistern, about a foot below the upper edge, and about three 
 feet from the bottom. In the centre of the perforated cover was fixed a lifting
 
 506 FIRE ENGINE. 
 
 pump, to the piston rod of which was attached a cross-tree carrying two vertical 
 connecting rods, which were simultaneously worked up and down by manual 
 labour, by means of two curved levers (similar to common pump handles,) on 
 opposite sides of the machine. During the downward motion of the piston, a 
 quantity of water passes through the valve on its upper surface, and gets above 
 the piston, and during the ascending stroke, this water is driven with great 
 velocity through a branch pipe provided with a flexible leather joint, or by a 
 Dall-and-socket motion, screwed on to the top of the pump barrel. Between 
 the strokes the stream is discontinued. This engine is supplied with water 
 poured into the cistern by buckets, &c., the perforated cover before mentioned 
 keeping back all such matters as would be likely to choke or injure the pump- 
 work." A year after the great fire of London, that is, in 1667, an act of 
 Common Council was passed " for preventing and suppressing fires for the 
 future," in which, among other salutary provisions, was enacted that the 
 several parishes, the aldermen, and different companies, should provide a 
 certain number of buckets, hand squirts, fire engines, &c.; which shows that 
 these were the only contrivances then known for the purpose. We may also 
 infer that the fire engines were not much to be relied upon at that time, from 
 the greater importance attached to hand squirts and buckets. With such 
 inefficient means it is not to be wondered at that fires spread as they used to 
 do, but rather, taking into account the buildings of that period, that they were 
 extinguished at all. Towards the close of the seventeenth century, M. Duperrier, 
 in France, Leupold, in Germany, and Newsham, in England, introduced, almost 
 contemporaneously, fire engines of a very improved description, which soon 
 came into general and extensive use. The most novel and important feature 
 of these engines consisted in the employment of an air chamber, which rendered 
 the stream of water continuous and uniform ; together with the equally im- 
 portant and valuable addition of the flexible leathern hose, of any requisite 
 length, invented by the brothers Jan Van der Heide, and first tried by them at 
 Amsterdam, in the year 1672. These contrivances enabled the stream of water 
 to be conveyed a considerable distance from the engine, and directed upon the 
 flames with the greatest precision and effect. In the engines of Leupold, 
 Duperrier, and some others, one working cylinder only was employed in con- 
 junction with an air vessel. These machines very much resembled the common 
 garden engines of the present day, which are too well known to require 
 describing in this place. Newsham used two cylinders; and the following 
 description of his fire engine will be read with much interest, when it is 
 considered that, so perfect was his machine, at the expiration of above a 
 century we still find it nearly as he left it. Various convenient alterations and 
 improvements have in the course of this period been made in the details of this 
 engine, but the general character and mode of construction adopted by Newsham 
 have not yet been surpassed. 
 
 The following engraving represents a perspective view of Newsham's engine, 
 ready for working. It consists of a strong oak cistern, about three times as long 
 as it is broad, mounted on four wheels, and drawn by the handle a. The under 
 part of the cistern is cut away in front, to allow the fore-wheels to lock in 
 turning round : the earliest engines were not furnished with this contrivance, 
 but none are now built without it. At b is an inverted pyramidical case, 
 enclosing the pumps and air vessel, forming a platform c, on which the fireman 
 formerly stood to direct the jet of water issuing from the spout or branch pipe 
 d. This branch pipe is attached to the air vessel by two brass elbows, the first 
 of which is screwed on the top of the air vessel, and the second elbow screws 
 upon the first by a fine screw of several threads, so truly turned as to be per- 
 fectly water-tight in every direction. The first elbow revolves on the top of the 
 air vessel horizontally, while the second elbow revolves on the first vertically ; 
 the combination of these two motions, therefore, permits the branch pipe to be 
 guided in every possible direction. This contrivance, however, is now obsolete, 
 except in small garden engines, where it is used in an improved form. The 
 flexible leather hose affords such a ready and convenient method of conducting 
 the stream of water to any required point, that all fire engines are furnished
 
 FIRE ENGINE. 
 
 507 
 
 with a proper quantity of it, to the extremity of which the branch pipe is 
 attached. At the hinder part of the engine is seen a strong leather suction 
 pipe (prevented from collapsing by a spiral piece of metal running throughout 
 its length), one end of which is screwed on, when required, to a brass nozle at 
 
 Fig. !. 
 
 Cie lower end of the cistern ; the other end is furnished with a rose or strainer, 
 and immersed in the water supplied by a pond, fire-plug, &c. To the hinder 
 part of the cistern is added a wooden trough e, with a copper grating (for 
 keeping out stones, sand, dirt, &c.) through which the cistern is supplied with 
 water, when the suction pipe cannot be used. An open space is left in the fore 
 part of the engine, also furnished with a copper grating, through which water 
 maybe poured into the cistern. In working this engine, the handles//, visible 
 on each side, are moved up and down, which gives alternate motion to the two 
 pumps. The working is also assisted by persons who stand on two suspended 
 treadles g g, throwing their weight on each alternately as they descend, and 
 keeping themselves steady by means of the two rails h h. The use of treadles, 
 however, has been discontinued for some time, and they only now remain in 
 a few of the oldest engines. Over the hind trough there is an iron handle or 
 key i, which turns the suction cock (a three-way cock) situated beneath it. 
 While the engine is working from water drawn through the suction pipe, the 
 handle i stands in the direction of the cistern, as drawn ; but when the engine 
 works from water contained in its own cistern, this handle is turned a quarter 
 round, into the position shown by the dotted lines. Between the pyramidal 
 case b and the fore end of the engine, there is a strong square iron shaft k, 
 lying in a horizontal position over the middle of the cistern, lengthwise, and 
 playing in brasses at each end, one of which is seen placed between the two 
 uprights 1 1 supporting the hand-rails. Upon this shaft are fitted two stout iron 
 bars or levers m m, one at each end, which carry the cylindrical wooden handles 
 // hy which the engine is worked. The treadles gg are suspended at the end 
 by pitched chains, and receive their motion jointly with the handles that are on 
 their respective sides, by means of iron double sectors fixed upon the shaft k
 
 08 
 
 FIRE ENGINE. 
 
 the foremost sectors are seen at n, the others are contained within the upright 
 box b. 
 
 Fig. 2, in the subjoined engravings, is a section of the working parts of this 
 engine through the cylinders, as seen on looking from the fore part of the cis- 
 tern towards the air vessel ; o o are the working cylinders or pump-barrels ; p p 
 the piston rods, with square holes to carry one end of the treadles ; q is the 
 double sector connected with the piston rods by the chains before mentioned. 
 It will be seen that there are two chains to each piston, one passing from the 
 top of the sector to the lower end of the piston rod ; the other from the top of 
 the piston rod to the bottom of the sector. The chains are riveted to the 
 sectors, and attached to the piston rods by screw nuts, which allow them to be 
 kept constantly tight. The pistons r r are formed of two round plates of brass, 
 smaller in diameter than the barrels, put into stout leather cups, and fastened 
 together by a nut, which screws on the piston-rod below the pistons ; m m is a 
 portion of one of the levers, by which the engine is worked ; the situation of the 
 two entrance-valves is seen at the bottom of each cylinder. Fig. 3 is another 
 section, taken vertically through the hinder part of the engine, showing one of 
 
 Fig. 2. 
 
 the cylinders o and the air vessel s. On the floor of the cistern is placed the 
 standing-piece, or sole, of cast-brass, which reaches from the nozle x through 
 the suction cock y, and afterwards divides itself into two branches, so as to open 
 under each of the barrels; one of these passages is seen in the figure, the 
 other is situated exactly behind it ; through these channels water is conveyed 
 to the pumps, either from the cistern itself, or from any place without, by means 
 of the suction pipes. The two cylinders are screwed down upon the standing, 
 or as it is frequently termed, the sucking piece, with plates of leather between 
 them, which makes the joints water-tight, and also forms the valves, one of 
 which appears at t. Each cylinder has a projecting piece cast on its lower 
 side, which forms a seat for the air vessel, and a communication into it, which 
 is closed by a valve opening upward at v. The leather valves are kept closed, 
 and also strengthened by a piece of metal having a tail, which passes through 
 the leather, and is cross-pinned under it. When the engine is at rest, all four 
 of the valves continue closed by their own weight ; but when the engine is 
 working, two are opened and shut alternately, g is the sector on the shaft A,
 
 FIRE ENGINE. 
 
 509 
 
 and g is one of the treddles in its bearing on the piston-rod; s shows the 
 internal construction of the air vessel. The action of this engine is exceed- 
 ingly simple ; on raising the piston r a partial vacuum is produced in the cylin- 
 der o, when the pressure of the atmosphere forces the water up the suction 
 pipe through the cock y, along the sole, and lifting the valve t into the cylinder. 
 Upon the piston reaching the top of its stroke, and beginning to descend, the 
 valve t closes, and prevents the water, which has entered the cylinder, from 
 returning by the way it came ; being urged by the forcible descent of the 
 piston, it is driven along the communication into the air vessel, raising the 
 valve v in its progress, which closes again the moment the water has all passed 
 through. While this process has been going on, the other cylinder has become 
 filled with water, which is now discharged in its turn into the air vessel, and so 
 on continuously. On the water first entering the air vessel, a quantity of air 
 is expelled ; but so soon as the water rises to the dotted line, the lower orifice 
 of the exit pipe becomes covered, and the escape of any farther portion of air 
 is prevented ; the air is therefore gradually driven by the continued influx of 
 water into a much smaller space than it originally occupied, and by its elastic 
 force reacting on the surface of the water, drives up the upright pipe z, along 
 the leather hose, and out at the branch-pipe, with so great velocity as to break 
 windows, &c., and throw up a jet to the height of sixty or seventy feet. New- 
 sham met with great encouragement, his patent being renewed for a second 
 term ; his engines were eagerly purchased by the government, nobility, and 
 gentry, the different parishes, and by the various fire insurance companies thai 
 were formed about this time ; viz. the Hand-in-Hand, in 1696 ; the Union, in 
 1714 ; and the London Assurance Corporation, in 1720. 
 
 In the year 1 792, Mr. Charles Simpkin took out a patent for an improve- 
 ment in fire-engines, which consisted in the employment of separate chambers 
 for containing the valves, instead of placing them within the cylinders and air 
 vessels, as was done previously. Mr. Simpkin, (afterwards of the firm of 
 Hadley, Simpkin, and Lott,) Long Acre, London, materially altered ti.a 
 internal arrangement of the working parts, and constructed an engine much 
 more compact and convenient than any of its predecessors. As a travelling 
 
 engine it was infinitely superior to any previously built ; the only method of 
 conveying Newsham's engine about, was by placing it in a cart or waggon made 
 purposely for it, and many of our metropolitan readers will recollect that the 
 London Assurance, Royal Exchange, and Phoanix Fire Offices, continued to run 
 Newsham's engines in this manner to the end of the year 1 832, when these and 
 other offices combined in forming a general fire-engine establishment, which 
 adopted Simpkin's form of engine. The above cut represents a side elevation of 
 one of Mr. Simpkin's engines, the principal working parts of which are shown 
 in section. The cistern a b is of oak, about seven feet long by two feet broad ; 
 tine pockets d and the upper part c are made of fir, for the sake of lightness, great 
 3 T
 
 510 FIRE ENGINE. 
 
 strength not being required in these parts. The cistern is supported by strong 
 springs on four substantial wheels. The hinder axle is bent like a crank, to give 
 due play to the springs, and permit large wheels to be used without raising the 
 body of the engine to an inconvenient height for working. The fore carnage 
 locks under the front of the cistern, which is cut away for that purpose ; it is fur- 
 nished with a pole and also shafts, to suit either cart or carriage horses. // are the 
 handles working the shaft e e by means of two levers. When not in use, the 
 handles are kept in their present position by the forked bar g. The suction- 
 pipe screws on to the nozle h, otherwise closed by a brass cap. There is a 
 screwed nozle i on each side, for attaching the delivery hose, which may be 
 fixed on to either side, or both sides, at pleasure. The pockets d carry two six- 
 foot lengths of suction pipe, and two branch pipes, one long, the other short. 
 The other equipments, generally about six forty-feet lengths of leather hose, 
 rope, crow-bar, shovel, pole-axe, saw, &c., are stowed away in convenient order 
 in the front and uppermost box of the engine. All being contained inside, and 
 nothing hung on externally, this engine is exceedingly compact, and very elegant 
 in appearance. The top of the engine forms an excellent seat for the firemen, 
 their feet resting on the pocket d, while the driver occupies the box seat in 
 front, guiding a pair of light horses, which will draw an engine of this kind at 
 great speed. At Jc in the sectional portion is seen the sole, or sucking-piece, 
 containing all the valves, and carrying the two working cylinders. At one 
 extremity of the cistern the three-way suction cock I is screwed to the sole k ; 
 to the other end a brass tube is also screwed, forming a communication with 
 the air vessel m and exit pipe i. n is the first or suction-valve chamber, divided 
 into two compartments, each containing a valve, closed on the top by a plate of 
 cast iron, fastened down with copper screws, a piece of leather being introduced 
 between to make the joint water-tight, o is the second, or delivery-valve chamber, 
 also in two compartments, closed in the same way as the former. The valves 
 are brass plates, ground to fit the circular brass seat on Avhich they rest ; being 
 accurately ground, no leather is required to make them tight. The whole valve 
 is put together, and then slipped into grooves, cast in the side and bottom of 
 the sole for its reception. If any of these valves should fail, it is only necessary 
 to unscrew and remove the covering plate, when they can be got at without 
 disturbing the other parts of the engine. In Newsham's engine, if one of the 
 suction valves became deranged, the engine had to be taken completely asunder, 
 before the defect could be remedied, p is one of the working barrels, six inches 
 in diameter, with a seven-inch stroke, made of cast brass, carefully bored and 
 screwed down upon the iron sole k, with copper screws, an intervening leather 
 making the joint perfect. The piston q is of two circular brass plates, placed 
 in strong leather caps, and bolted together. The top of the barrels is a little 
 above the level of the cistern, so that when the latter is filled with water it 
 may not run into the barrels, and wash away the oil with which the pistons are 
 kept constantly covered. Projecting arms on each side of the main shaft e, 
 work the pistons by means of slings within the piston rod, which is forked to 
 the height necessary for that purpose, but ends in a cylindrical rod, working in 
 a guide plate above r, which preserves the parallelism of the piston throughout 
 its stroke The main shaft works in brass journals at sss. The sole k is made 
 so as to form an inclined plane from h to i, which causes all the water to run 
 out of the engine after it has ceased working. The principle of action in this 
 engine is similar to that already explained while treating of Newsham's, and 
 therefore requires no further mention here. 
 
 In the year 1793 Mr. Joseph Bramah took out a patent for a new fire engine, 
 with sundry improvements and additions. This engine was essentially different 
 in its construction from those already described. It consisted of a large 
 horizontal metal cylinder, having a flanch at each end, to which two end caps 
 or covers were screwed. These caps enclose all the working parts of the engine, 
 and have brass bearings with stuffing-boxes in their centres, for carrying in an 
 air-tight manner the working axis of the engine. Within the cylinder is 
 placed a strong metal partition or radius, the lower edge being joined to the 
 cylinder, and the uppermost edge, which is grooved, made so as exactly to fit
 
 FIRE ENGINE. 
 
 511 
 
 the circle of the latter. The axis is armed with two wings or fans, on each of 
 which is placed a valve opening upwards, to allow the water to pass through 
 them. These fans are made to move water-tight against the sides and end 
 caps of the cylinder, by means of leather on their edges. When the axis 
 carrying the fans is fixed in its place, the groove in the metal partition described 
 above, is filled with hemp, or some other soft material, so as to press on the 
 under surface of the axis, and cause it to move in a water-tight manner. The 
 fans being a diameter of the cylinder, divide it into two parts, the lower of 
 which is again divided by the radius partition into two compartments, in each 
 of which an aperture is cut through the cylinder opening into the suction 
 passages ; these apertures, like those in the fan, are closed by valves opening 
 upwards. A vibratory motion being given to the fans by means of levers on 
 the axis, the capacity of the two lower compartments of the cylinder becomes 
 alternately enlarged and diminished ; the consequence of this is, that water 
 becomes drawn up into the cylinder, gets above the fans on either side, and is 
 then forced out through the exit pipe, the stream being rendered equable by 
 means of a spherical air vessel placed on the top of the cylinder. This was 3 
 novel and ingenious contrivance, and produced a very compact engine ; 
 
 great drawback, however, upon its advantages, was the difficulty of packing 
 and making it water-tight in the first instance, and the still greater difficulty of 
 keeping it so for any length of time, if much used. 
 
 Subsequently Mr. Rowntree introduced an engine, in which he attempted to 
 embody all the advantages of Bramah's engine, and to avoid its defects. 
 Mr. Rowntree's principal improvement consisted in the employment of one fan, 
 a radius of the cylinder, instead of two ; the vibration of the fan took place in 
 the lower half of the cylinder, the 
 partition being placed above. Mr. 
 Rowntree, however, succeeded but 
 imperfectly with his engine, which 
 has been greatly surpassed by a more 
 recent invention by Mr. John Barton, 
 which is decidedly the best engine 
 hitherto constructed on the vibratory 
 principle. 
 
 The accompanying drawing and 
 description will convey an accurate 
 idea of Mr. Barton's engine, and show 
 the principle of action in this, as well 
 as in the two former contrivances. 
 The figure affords an end view of 
 Barton's engine, mounted on a suitable 
 cistern upon wheels, a is the cylinder, 
 or working barrel, of brass or iron : 6 
 is the fan or piston, which, like 
 Rowntree's, is a radius, but his was 
 placed below the centre, while Bar- 
 ton's is situated above. The fan is 
 composed entirely of metal, on the 
 expanding principle, with springs and 
 segments, as in Barton's metallic 
 pistons, ccc c are four valves, all 
 opening upwards ; d is the air vessel, 
 with the exit orifice at its lower part ; 
 e is the cistern, which may be kept 
 full of water for immediate use on the 
 breaking out of a fire. This engine, 
 like all the former, is capable of working from a pond, &c. by means of a 
 suction hose, as well as from water poured into the cistern, the supply, as in 
 Mewsham s engine, being regulated by a three-way cock placed within the 
 cistern. The engine is worked by the elevation and depression of the handles 
 
 n
 
 512 FIRE ENGINE. 
 
 h h, connected with the axis of the fan b, which vibrates backward and forward 
 in the upper part of the cylinder, and delivers at each stroke nearly one-half of 
 its contents, and may be regulated so as to give more or less, as required. The 
 working of the fan or piston b, being perfectly air tight, tends to produce a 
 vacuum below, on that side of the cylinder a where the handle is elevated, and 
 the pressure of the atmosphere causes water to rush up into this space. During 
 this stroke the air that occupied the other side of the cylinder has been partly 
 expelled, and this space, on the second stroke being made, is filled with water, 
 while that already on the other side of the piston is forced up into the air 
 vessel, and thence through the exit pipes in a continuous jet. 
 
 A very compact and convenient fire engine has lately been invented by 
 Mr. Baddeley, consisting of only one cylinder placed horizontally, and working 
 on the principle of De la Hire's double-acting pump. The ordinary up and 
 down motion of the handles, by means of a simple contrivance, causes the 
 piston to traverse backward and forward within the cylinder, each side being 
 alternately filled with water which the returning stroke expels. There are two 
 entrance valves lying at the bottom of the cylinder, one at each end, and two 
 exit valves, situated immediately over the former. The water enters at the 
 bottom of the cylinder, and is discharged at the top, the stream being equalized 
 by a globular air vessel. The inventor considers the advantages of this engine 
 to consist in its compact form, great strength, and durability; that it has 
 fewer working parts, is lighter, and has less friction than any other engine of 
 equal power. 
 
 Of all the engines hitherto constructed and worked by manual labour, the 
 floating fire engine is the most powerful. Engines of this kind generally 
 consist of three cylinders, working into an air vessel of large dimensions, and 
 are built in appropriate barges. They are put in motion by the power of from 
 forty to fifty men, applied to four long revolving cranks, which, by suitable 
 machinery, work the three pistons. These engines will throw a column of water, 
 one inch in diameter, upwards of a hundred feet high. They are advantageously 
 employed on the river and in docks, where an abundant supply of water can 
 always be depended upon. 
 
 These engines, however, have been greatly surpassed by the fire engines 
 recently constructed by Mr. John Braithwaite, worked by steam power. The 
 last of this kind, the Comet, built for the Prussian goverment in 1 832, had two 
 working cylinders ten inches and a half in diameter, with a fourteen-inch 
 stroke, the steam cylinders being twelve inches in diameter. When working 
 with a steam pressure of seventy pounds upon the square inch, and making 
 eighteen strokes per minute, this engine threw a jet of water, an inch and a 
 quarter in diameter, nearly one hundred and twenty feet high. The same 
 power gave two jets of seven-eighths of an inch, and afterwards four of five- 
 eighths of an inch, an elevation of about eighty feet. The consumption of 
 coke was three bushels per hour, and the average working of the engine was 
 calculated to be equal to the discharge of between eighty and ninety tons of 
 water per hour. 
 
 Numerous attempts have been made to condense a powerful fire engine into 
 a small compass. In this respect Capt. Fisher, R.N. appears to have been 
 most successful ; his engine, on Newsham's principle, consisting of two five- 
 inch cylinders, with eight-inch strokes, and an air vessel situated between them, 
 was comprised within a box the size of an ordinary tea chest, exclusive of the 
 handles, which fixed on the outside, and served to carry the engine by. The 
 purposes for which this kind of engine is suitable are so few, that they have not 
 been very extensively used ; for the local purposes only of mansions, manu- 
 factories, or on ship board, can they be advantageously employed. 
 
 Much ingenuity has been exercised to construct a fire engine on the rotatory 
 principle, but without success. An ingenious one of this kind was the invention 
 of Mr. Rangeley, for which he took out a patent. It consisted of two fluted 
 rollers, working into each other, while their opposite sides worked in semi- 
 cylinders, with which they were in close contact, the ends of the rollers being 
 similarly circumstanced ; each space between the fititings came up filled with
 
 FIRE ESCAPE. 
 
 513 
 
 water, which was discharged by the flutings exactly fitting into each other on 
 the descending side. In this, however, as in all the other rotatory steam and 
 fire engines, it was found to be practically impossible to construct an engine 
 sufficiently water tight to stand the great pressure to which they are subject, 
 without incurring an excessive and destructive amount of friction. 
 
 FIRE ESCAPE. Perhaps few subjects have more extensively engaged the 
 public attention, or exercised so much ingenuity, as the best mode of rescuing 
 individuals from death by fire. Notwithstanding the varied talents that have 
 been directed to this object, it is a singular fact, that no invention has yet been 
 
 Fig. 3. 
 
 produced so universally efficient as to supersede all others, or to induce the 
 belief that the limits of perfection have been attained. Many excellent and 
 ingenious contrivances have been produced, most of which will be found 
 embodied in the following classified description. Fire escapes may generally 
 he divided into three classes, viz. ladders, portable escapes, and carriage escapes. 
 With the common fire ladders all must he well acquainted ; they are made of 
 different lengths to reach a first, second, third, or fourth story window. When 
 of the largest kinds they are generally furnished with iron guides or hand-rails
 
 514 FIRE ESCAPK 
 
 at the sides, and also with a contrivance for raising them. This contrivance 
 consists of a short conical iron tube, jointed to one of the upper rounds or steps 
 of the ladder ; a long pole fixes into this tube, and affords great facility in 
 raising the ladder. A well-made ladder of bamboo, from its extreme lightness, 
 combined with the requisite strength, has been considered by some persons 
 admirably adapted for the purposes of a fire escape. Another form of ladder, 
 and one that is at present very successfully employed, consists of short lengths, 
 from eight to nine feet long, which fit one on the other to any required extent, 
 by a strong, but simple joint, in the same way as scaling ladders. The advan- 
 tages of this kind of ladder are, great portability and convenience, with all the 
 practical utility of the longest and most unwieldy ladder. Mr. Gregory, whose 
 numerous fire escapes have attracted deserved attention, has constructed a great 
 variety of ladders ; among them is a very pretty ladder, in two parts or lengths, 
 one sliding upon the other, and sustained at any required elevation by a simple 
 contrivance. A cradle is attached to this ladder, for the rescue of timid or infirm 
 persons ; the whole is of a convenient size for carrying or stowage, and is very 
 easily managed. Mr. Gregory's patent ladders are exhibited in the engraving 
 on the preceding page. Fig. 1 is a side view of one of the ladders, nine feet in 
 length. Fig. 2 exhibits three of these ladders connected together, and applied 
 as a fire escape, with a light car or cradle, raised by ropes h h, working in pulleys 
 attached to the top of the ladder. Fig. 3 represents four of these ladders 
 raised, for the purpose of elevating the fireman, and enabling him to direct the 
 stream of water from the engine most effectually upon the fire. A set of these 
 ladders may be placed on a light hand carriage, or might accompany each 
 fire engine. On reaching a conflagration, the lower ladder is first raised, and 
 the feet secured in their place by a bolt passing through them and two blocks, 
 placed upon the engine for that purpose. The iron stays b b crossing each 
 other are hooked into staples fixed in the back of this ladder. The first ladder 
 being thus firmly fixed, a man mounts it and attaches another on the top of it; 
 a third, fourth, or a fifth, may in this way be added, until the required height is 
 obtained. When the height is considerable, two guy ropes d d are employed, 
 to preserve the ladders in the proper position. For this purpose the back of 
 the carriage is provided with two large square staples, through which the bar 
 e is thrust ; to the ends of this bar the ropes are made fast, as shown. The 
 ladders are each precisely alike, so that all fit one another ; they are connected 
 by the following simple and effective contrivance. Two long hooks or half- 
 staples a a are fixed on the hook of each ladder by means of an iron strap, 
 and riveted through ; each ladder is provided with two flat steps c c at its 
 lower end, which drop into the two hooks and make a firm and secure joint. 
 Rope ladders have sometimes been employed as fire escapes ; the most common 
 kind consist of strong rope sides, with wooden steps ; circular pieces of wood 
 are sometimes added to the ends of the steps, to keep the ladder from walls, &c. 
 In Edinburgh wire chain ladders are employed with great success, being used 
 by men duly trained for that purpose. The principal difficulty with all ladders 
 of this description, is in raising them to the windows where they are required ; 
 this difficulty has been surmounted in the rope ladder of Mr. A. Young, the 
 most ingenious and useful contrivance of this kind with which we are ac- 
 quainted. It consists of a number of rounds A, Fig. 2, (in the engraving on the 
 following page,) which form the steps of the ladder by being united with two 
 ropes B B ; these are suspended from an iron frame C, terminating in hooks 
 a a, which can very conveniently be lodged on the sill of a window, and thus 
 form a secure support for the ladder. The principal peculiarity of this con- 
 trivance consists in making the ladder, so that the rounds or steps can be put 
 together as shown at Fig. 1, forming a pole by which the frame c can be raised 
 up to a window from below. To effect this, the ends e of the rounds A have 
 ferules fitted fast upon them, and the other ends / are reduced so as to enter 
 the cavities of the ferules, which project beyond the end of the wood, thus 
 forming sockets for their reception. The iron frame c at the top has a projecting 
 pin d, which fits into the socket e of the upper round ; this supports it at the 
 top. The small end of this step is inserted into the ferule of the second, which
 
 FIRE ESCAPE. 
 
 A. 
 
 is again fixed to the top of the third, and so on to the bottom. In this way a 
 
 pole is formed, as in Fig. 1, of all the steps of the ladder joined together, by 
 
 which means the hooks at the top of the iron frame may be raised up to a 
 
 window sill, and then a single jerk or pull at /-;.. 
 
 the lower end disunites the staves from one 
 
 another, and they assume the form of Fig. 2, 
 
 ready for ascending or descending. The side 
 
 ropes of the ladders B B are composed of 
 
 three small lines plaited together, which 
 
 method gives the means of fastening the 
 
 staves very securely to them ; this is shown 
 
 by Fig. 3. A hole is bored through the stave 
 
 at the place where the rope is to be fixed, 
 
 large enough to receive one of the three lines, 
 
 and a groove is turned round outside of it at 
 
 the same place. One of the lines is passed 
 
 through this hole, the other two are taken 
 
 round in the groove so as to surround the 
 
 stave, then all three, being plaited together 
 
 make a firm connexion. The frame c at the 
 
 top has two iron rods b b fixed to its sides, 
 
 which are useful as hand-rails to any person 
 
 getting out of a window on to the ladder. The 
 
 whole rolls up into a compact bundle, and is 
 
 easily carried about. A ladder on the same 
 
 principle may also be constructed entirely of 
 
 metal, by using wire chains, and metal tubes 
 
 for the steps. Mr. Young received a silver 
 
 medal and fifteen guineas from the Society of 
 
 Arts for his invention. 
 
 Mr. Gregory constructed a very complete 
 rope-ladder escape, which was supported on 
 the window sill, parapet, &c. of a house, by a 
 hook of ingenious workmanship, composed of 
 two sides or arms, bent into a form very 
 closely resembling the external figure of the 
 human ear, from that circumstance called the 
 ear hook. The two sides of this hook were 
 held together by three horizontal iron rails or 
 bars. This simple, original, and effectual 
 mode of attachment admits of universal ap- 
 plication, without any previous provision for 
 that purpose ; it firmly embraces alike the 
 thickest and thinnest walls, and when once 
 fixed, no downward force can separate it from 
 its attachment, but by tearing the hook asunder. 
 To this hook was attached a neat, well made 
 rope ladder, to which a sliding cradle was 
 adapted, the rope by which the cradle was 
 worked passing over the central bar of the ear 
 hook. 
 
 The next class of fire escapes, comprising 
 those of a portable description, is a very 
 numerous one, and may be said to commence 
 with a simple rope made fast to something 
 within the room, by means of which a descent 
 might be effected ; it has been considered an 
 improvement to knot the rope pretty closely, and descend by alternately 
 changing the grasp, instead of letting the rope slip through the hand ; it is but 
 a limited number of persons, however, who could escape by these means. Jt 
 
 Fig.
 
 516 FIRE ESCAPE. 
 
 has therefore been suggested to attach a sack to the end of a rope of sufficient 
 length, into which females, children, &c. might be put and lowered in safety, 
 their descent being regulated by drawing the bed close to the window, and 
 passing the lope once or twice round the bed post, which would generate 
 friction enough to make the descent easy, without much exertion on the part of 
 any person. Several improvements have been made upon this rude and simple 
 apparatus, consistiug in general of a cradle in lieu of the sack, made of a con- 
 venient form and suitable material, and in running the rope through a pulley 
 hooked to a staple provided for that purpose ; a guide rope is also attached to 
 the bottom of the cradle, which enables it to be pulled aside from flames issuing 
 from the lower windows, and from railings, areas, &c. In some cases the 
 -pulley is supported by a grappling hook thrown into the window. Escapes 
 of this kind have been constructed by Messrs. Cobbin, Cook, Fox, Hesse, 
 Merryweather, Read, and some others, all similar in principle, but differing 
 slightly in detail. Mr. Gregory employed a stout rope, forty feet long, having 
 a hook at the top, and a pulley within a few inches of it ; a cradle slides upon 
 this rope by means of two rings, one at the top and the other at the bottom of 
 it. Another rope, twice the length of the former, passes over the pulley, 
 and is fastened to the upper part of the cradle ; by this rope the persons below 
 raise or lower it, until the whole of the inmates of the house are extricated. In 
 this escape the oscillations, as well as the rotatory motion, which occur in 
 some of the former contrivances, are both prevented. 
 
 Mr. B. Rider a short time since exhibited a simple rope fire escape, con- 
 sisting of a stout hempen rope sallied with worsted, having at one end a swivel 
 spring catch, by which it could be instantly attached to a bed post, chest of 
 drawers, bar of a grate, &c. Upon this rope was placed a stirrup or friction 
 seat, with three rings, through which the rope passed ; these rings were not 
 placed perpendicularly above each other, but stood in a curved direction, so as 
 to cause considerable friction, and check the too rapid descent of the parties ; 
 for one individual, with very little exertion, could, by means of the friction 
 seat, descend with another person in his lap. A contrivance was also appended, 
 for instantly fixing a secure noose under the arms, to be used when the friction 
 seat was not employed. 
 
 Mr. Davies invented a rope fire escape, possessing in an eminent degree the 
 essential qualities of simplicity, efficacy, and portability. It consists of a long 
 rope doubled, the two ends of which are secured to a strong iron hook, for the 
 purpose of attaching it to a ring bolt screwed to the sash frame, or a beam in 
 the ceiling. A number of loops, made of strong girth web, slide upon the 
 double rope, by means of short copper tubes or eyes ; these loops are also 
 equipped with cloth slides. This, with a jointed rod for raising it to a window, 
 comprises the whole of the apparatus. The mode of using this escape is as 
 follows : the end of the double ropes at which the sliding loops are all collected, 
 :s placed upon the forked extremity of the uppermost joint of the rope, a 
 second is added, and so on, till the necessary elevation is obtained. The persons 
 above having secured the hook to some suitable object, those below hold the 
 ropes asunder, thus forming a triangle, the apex being at the window, and the 
 base in the street. One of the persons above then takes one of the loops, and 
 passing it over hia head and shoulders, fixes it under his arms ; he then gets 
 out of the window and commits himself to the rope, down which he slides to 
 terra firma. As the ropes are in contact at the window, the descent Ls at first 
 rapid, but as the person gets lower, the greater divergence of the ropes gradually 
 arrests his progress. There should be at least six or eight persons holding the 
 ropes, and they should be kept as wide apart as circumstances will permit ; the 
 base should always be upwards of three yards. Females, children, &c. may be 
 lowered by this escape with perfect ease and safety ; for, by bringing the cloth 
 slide on the loop close to the body, the person descending cannot quit the loop 
 till released by withdrawing the slide. Mr. Barnard had- previously proposed 
 the employment of a wicker cradle sliding on divergent ropes, but this arrange- 
 ment is inferior to that of Mr. Davies in practical convenience and efficacy. 
 The principal difficulty attending the use of portable fire escapes, is in
 
 FIRE ESCAPE. 
 
 517 
 
 establishing a communication with the persons in danger; the most usual 
 method of effecting this object is by rods about six or eight feet long, connected 
 either by fishing-rod or bayonet joints, or by screws, as in the escapes of Messrs 
 Davies, Glass, Merryweather, and several others. The accompanying sketch 
 shows a series of rods connected in this manner, which 
 not only raise but also support a pulley upon which a cradle 
 is worked ; this arrangement, however, requires strong, 
 and, consequently, very heavy rods, and therefore cannot 
 be much recommended. Mr. Gregory effected a com- 
 munication by means of a walking stick with three 
 extending joints like a telescope, by which a line was 
 handed to the persons in danger from the window of an 
 adjoining house. Others have suggested the idea of 
 dropping a line from the tops of the houses on each 
 side of that on fire, which, attached to a rope, or escape 
 of any kind, would enable it to be raised to those 
 requiring its aid. Some persons have proposed to throw 
 a ball with a line attached, into the window from the 
 street, and thus form the desired connexion ; this, 
 however, is a difficult and random mode of proceeding, 
 and by no means to be relied on in the time of danger. 
 The Edinburgh firemen use a cross-bow, and a three- 
 ounce leaden bullet, attached to a fine cord of the very best materials and 
 workmanship, 130 feet long. The bullet and cord are thrown over the house by 
 the cross-bow ; to this cord a stronger one. is attached, and drawn over the 
 house by the former, and so on, until a chain ladder or escape is eventually 
 elevated. To act upon this plan, however, with any good chance of success, 
 requires the men to be regularly trained for the purpose, as they are in 
 Edinburgh, where they are exceedingly skilful in the management of all their 
 fire machinery. 
 
 Mr. Buston introduced a fire escape, consisting of a large strong canvass 
 sheet, with loops all round to hold on by ; this being held under the window at 
 which any person is situated, by eight or ten persons, the party above leaps out 
 of the window into the middle of the sheet, which catches him uninjured. 
 Although this is by no means the most pleasant mode of escape, nevertheless 
 numberless experiments have proved it to be a safe and effectual one. As this 
 escape takes up but little room, and is ready for use in a few seconds, it is well 
 adapted to be carried by the fire engines, and most of those in London are now 
 provided with one of this kind. 
 
 Having thus briefly noticed the most celebrated fire escapes of a portable 
 nature, we proceed to describe those of a larger kind; and first of carriage 
 ladders. In the year 1809 Mr. John Davies submitted to the Society of Arts a 
 fire escape, which consisted of three ladders connected to, and sliding upon, 
 each other, by means of ropes worked by a small windlass ; a second windlass 
 raised and lowered a cradle, supported by ropes passing over pulleys at the top 
 of the uppermost ladder. This machine was mounted upon a low four-wheeled 
 truck, drawn by a horse or by six men. Subsequently, Mr. Gregory greatly 
 improved upon this escape ; he employed three ladders sliding on each other, 
 which, when lowered, were balanced horizontally upon a convenient frame 
 mounted on a light four-wheeled carriage. When in this position they are 
 capable of being run under low gateways, &c. with great facility. The ladders 
 are brought into the perpendicular position, and then raised by a small windlass 
 in the front of the machine, to any required height between ten feet and forty ; 
 the ladders are then inclined towards the window, upon the sill of which the 
 top may be made to rest. To obtain a greater elevation than forty feet, one or 
 more joints can be carried up and affixed, in the manner already described under 
 the head of PORTABLE LADDERS. A cradle accompanies this machine, for the 
 assistance of those who cannot descend the ladders. Mr. Gregory's ladder escape 
 has been but partially employed for that purpose ; as a valuable and convenient 
 ladder, however, it has been very extensively used by architects and others. 
 3 c
 
 518 
 
 FIRE ESCAPE. 
 
 Mr, John Hudson, the founder of a short-lived society for preventing loss of 
 life by fire, in 1829, constructed an escape-ladder, differing in some respects 
 from that of Mr. Gregory, although upon a similar principle. The following is 
 a side view of Mr. Hudson's apparatus ; a is the carriage mounted on four 
 
 wheels, the front pair of which turn with their axis and handle b under the 
 carriage, for the facility of guiding, stowage, &c. ; // are three ladders sliding 
 in grooves one within another. The foot of the lowest ladder is hinged to a 
 revolving centre in the middle of the floor of the carriage ; d is an arched 
 frame forming the quadrant of a circle, with ratchet-teeth on its edges, in 
 which drops a pall or click g on a cross bar fixed to the back of the lowest 
 ladder. The ladders usually lie in a horizontal position, as shown by the dotted 
 line /; the palls and ratchet- teeth prevent the ladders from falling back while 
 being elevated. In order to place them in the oblique position for use, they 
 may be elevated by hand, or more easily by turning the windlass i round the 
 barrel of which the rope k is wound, and the other end of it fastened to the 
 ladders at about three feet above the floor. The ladders being thus brought 
 to the position represented in the engraving, the motion of the windlass is con- 
 tinued, which winds off the rope from the ladders, and elevates them succes- 
 sively one above the other, until they attain the greatest height. The rope k 
 passes through a pulley near the bottom of the lowest ladder, then over the top 
 of it to the bottom of the next, and then over the top of the same to the bottom 
 of the uppermost ladder. The pivot to which the ladders are hinged, is for 
 enabling them to be veered round when it would be inconvenient to turn the 
 carriage. The horizontal position is given to the ladders for enabling the 
 machine to be conveyed through low passages, &c. There is a roller n at the 
 top of the ladder, to prevent friction when moving up against a wall, and a 
 tackle fall at o for cradles, &c. 
 
 Mr. Joseph, who entertained a strong objection to the use of a connected
 
 FIRE ESCAPE. 
 
 519 
 
 series of ladders, submitted the following novel 
 tion : a is a carriage capable of being drawn by two men, on which is fixed an 
 elevated part b, sustaining a column of wood c ; within this there is a smaller 
 column of iron, capable of being raised by a rack and pinion, acted upon by the 
 winch d; on the top of this internal 
 column is an iron arm e on a swivel, 
 having a cleft at its extremity to re- 
 ceive the long bar or lever /fastened 
 to it by a bolt. The lower end of 
 this bar is secured to the carriage 
 by a pulley-tackle, which admits of 
 an easy and secure adjustment at 
 pleasure ; to the upper end of this 
 bar is suspended the cradle, &c. in 
 the usual manner, with guy ropes to 
 guide the cradle in its descent ; k is 
 the handle for drawing the carriage. 
 There is a small rope ladder at /, 
 and a bolt and chain at the top of 
 the column, for fixing the internal 
 pillar (which has a range of eight 
 feet) at the required elevation. The 
 pillar has a joint near its base, by 
 which it is turned down into the 
 horizontal position whenever it is 
 required to pass under gateways, &c. 
 In the year 1813, Mr. Thomas 
 Roberts received a reward from the 
 Society of Arts, for a " speedy ele- 
 vator and fire-escape," of a very 
 complex description, on the principle 
 of the lazy-tongs ; the same principle 
 has since been employed under 
 various modifications by numerous 
 persons, and most recently by Mr. 
 Doyle. The engraving on the fol- 
 lowing page represents Mr. Doyle's 
 machine ; a a exhibiting the com- 
 bination of levers on one side of the 
 machine ; b is the frame that holds the lower pair of levers, and wherein the 
 moving force is applied ; c the carriage on four wheels, drawn by a handle 
 not shown in the engraving ; d is a stage or platform at the top of the machine, 
 on which a fireman or other individual is raised to rescue the persons from the 
 house on fire ; at e there is a folding-bridge or gangway, to be projected into 
 the window of a room ; at /is a toothed pinion ; g is a toothed quadrant, welded 
 to the lowest lever-bar on one side, with its teeth taking into those on the upper 
 side of the pinion ; at k is another quadrant, the teeth of which take into the 
 lower side of the pinion ; motion being given to the pinion by the winch, the 
 two quadrants are moved in opposite directions, and the series of levers are 
 simultaneously operated upon in like manner, opening and shutting like so 
 many pairs of shears, thereby drawing them all up closely together, or expanding 
 to the extent of nearly their whole length. In the accompanying cut the 
 machine is represented as only expanded to half the height it is capable of being 
 extended. On the other side of the machine, there is, of course, a similar 
 set of levers ; they are connected to those already described, by cross horizontal 
 bars, the ends of which form the pivot joints on which the levers turn. The 
 opposite side of the lower part of the machine is also a counterpart of that 
 represented, and the power is connected by a common axis to the opposite 
 pinion. Although the principle of the movement is, perhaps, the best that 
 could be devised for the purpose, the practical difficulties of executing such a
 
 520 
 
 FIRE ESCAPE. 
 
 machine on a large scale, have, 
 we are informed, been found insur- 
 mountable, an attempt to construct 
 one having failed. 
 
 Mr. Gregory, some few years 
 since, patented a " portable derrick 
 fire-escape," which consisted of three 
 square wooden pillars, sliding one 
 within the other, mounted on a 
 convenient carriage ; the uppermost 
 carried a pulley for raising a cradle, 
 &c. The pulley was elevated by a 
 windlass and rope connected with 
 the pillars in the same manner as 
 employed for raising his ladders. 
 
 Mr. Rose, of Manchester, con- 
 structed a fire-escape composed of 
 an upright frame, fronted on a 
 four-wheeled carriage ; a second 
 frame sliding within the former, 
 carried at its top a small railed 
 platform or gallery, in which people 
 were received from the windows of 
 houses ; or it was occupied by a 
 fireman with the branch of an 
 engine, which enabled him more 
 effectually to throw the stream of 
 water upon the fire in lofty build- 
 ings. The sliding frame was raised 
 by two chains attached to its lowest 
 end, and carried over pulleys at the 
 top of the first frame, to a windlass 
 in the body of the machine ; a 
 ladder formed a communication 
 between the body of the machine 
 and the platform when it was in its 
 lowest position. 
 
 Besides the escapes already no- 
 ticed, there is yet another kind, 
 which may be very properly desig- 
 nated "domestic fire-escapes," as 
 they are intended solely for the use 
 of the family in whose house they 
 are placed. Some of the best of 
 this class are those in form of a 
 chair, sofa, or other convenient 
 article of furniture, and stand in 
 the recess of a window, outside of 
 which they are soon placed, and 
 constitute excellent fire-escapes, 
 with every convenience necessary 
 for a safe descent. Mr. Witty re- 
 ceived a reward from the Society 
 of Arts for an admirable escape of 
 
 this kind. These machines, however, do not generally obtain, for the mass of 
 the people are too indifferent to this subject to provide themselves with escapes, 
 but rather choose to trust to the chance of obtaining external aid. Various 
 expedients have been resorted to, and different plans may be adopted to effect 
 an escape from fire, according to circumstances. Egress can sometimes be 
 made at the top of a house, either by a door, or by an opening made in the
 
 FIRES. 
 
 521 
 
 roof with a poker for the purpose. Sheets and blankets tied together and 
 fastened to the bed-post, or the bed-cords, attached in the same way, afford the 
 means of descending ; the feather-bed, &c. thrown out, serve to break the fall 
 when jumping from the window as the last alternative. With a little contriv- 
 ance, women and children may be lowered by means of the bed-clothes. Upon 
 these occasions, all depends upon the persons in danger retaining so much 
 presence of mind as will enable them to avail themselves of the best means in 
 their power ; and it often happens that pressing danger develops a great deal 
 more ingenuity and intrepidity in individuals, than they have previously taken 
 credit for. 
 
 FIRES, EXTINGUISHING OF. The most suitable and convenient material for 
 extinguishing fire is water ; but when that cannot be speedily obtained in suf- 
 ficient abundance, it has been proposed to increase its extinguishing property 
 by the addition of various substances. M. Van Aken, a Swede, employed an 
 antiphlogistic composition of water holding in solution sulphate of iron, sul- 
 phate of alumine, red oxide of iron, and clay, with which he performed several 
 successful experiments. Some persons have recommended the employment of 
 simple solutions of either of the following substances alum, common salt, 
 pearl-ash, and several other salts and alkalies. Other experimentalists, on the 
 contrary, especially M. Van Marum, have contended, with much apparent 
 truth, that water alone, when properly and judiciously applied, is nearly as effi- 
 cacious in extinguishing fire as any of the above compounds. Carbonic acid 
 gas, sulphuric acid gas, and steam, have likewise been suggested as applicable 
 to the extinction of fire ; there is, however, much practical difficulty, and great 
 inconvenience in employing either of these 
 substances for such a purpose ; with respect 
 to the latter, some extensive and well-con- 
 ducted experiments, recently performed by 
 Mr. Waterhouse, at Preston, in Lancashire, 
 have shown that steam will speedily extin- 
 guish moderately small bodies of flame, but 
 does not possess the power of preventing a 
 low or charring combustion, and that steam 
 impelled against a large fire increases the 
 violence of the combustion in a remarkable 
 degree. Water, however, is so universally 
 diffused, that all other modes of extinguish- 
 ing fires have fallen into disuse. There are 
 many ways of applying this fluid to the 
 purpose now under review, the most useful 
 of which we proceed briefly to describe. 
 The simplest contrivance for extinguishing 
 fires, is by means of an elevated reservoir 
 or cistern, a pipe from which proceeds 
 through all the floors of the building, with 
 a cock and screwed nozle in each, to any of 
 which a flexible hose and director can be 
 affixed. On turning the cock, a jet of water 
 ..rushes out with a force proportionate to the 
 "height of the reservoir, which can be thrown 
 into that part of the premises where the 
 fire is situated. This arrangement is par- 
 ticularly useful in large manufactories or 
 warehouses. The principal advantage of 
 this plan, is the great facility with which 
 one person can apply this remedy, the 
 labour having been previously performed. 
 If the fire is so extensive as to require 
 more water for its extinction than is con- 
 tained in the reservoir, the supply must be
 
 522 FIRES 
 
 maintained by pumping. In lieu of the reservoir and system of pipes, some 
 persons prefer fixed pumps, drawing their supply of water from a well. The 
 engraving on the preceding page represents a stationary fire-pump of this 
 description, as erected in various places by the late Mr. Russell, of St. John 
 Street, London. It consists of a lifting-force pump, with an air-vessel to equalize 
 the stream between the strokes, placed in a deep^ well. The nozle of the pump 
 is screwed for attaching one or more lengths of leather hose, according to the 
 distance of the fire ; the handle is forked to allow several hands to work the 
 pump. The advantages of this and other kinds of stationary engines, consist in 
 the promptness with which they can be got into action, and the certainty of 
 obtaining a sufiicient supply of water : one disadvantage is, that their usefulness 
 is confined to a comparatively limited space. In some late experiments, one of 
 these pumps, erected at Aldgate, delivered a stream of water with considerable 
 force at the distance of sixteen hundred feet from the source of supply. 
 
 Of all the portable contrivances for extinguishing fires, perhaps that invented 
 by Capt. Manby is the most convenient, and is very ingenious. This apparatus 
 consisted of a copper vessel, two feet long, and eight inches in diameter, capable 
 of holding four gallons. A metal tube, a quarter of an inch in diameter, passed 
 internally from the top to within half an inch of the bottom of the vessel, fur- 
 nished at the top with a stop-cock and jet-pipe one-eighth of an inch in 
 diameter. Three gallons of a saturated solution of pearl-ash in water being 
 put into one of these vessels, the jet-pipe was removed, and a condensing 
 syringe afforded in its place ; as much air as possible was then pumped into the 
 space remaining above the fluid : the stop-cock was then turned, and the con- 
 densing syringe exchanged for the jet-pipe. In this state the apparatus formed the 
 well-known artificial fountain in pneumatics ; on turning the cock, the elasticity 
 of the condensed air reacting on the surface of the fluid, forces it out at the 
 nozle in the form of a violent jet. Six of these vessels were placed in a light 
 hand-cart, with which a man could run at a good speed. On reaching the fire 
 the man takes one of the charged vessels from the cart, and slings it in front 
 of him by a strap passing over his shoulders; he then enters the build- 
 ing, and placing himself as close as possible to the fire, turns the cock, and dis- 
 charges the contents of the vessel on the flames ; by tlae time the first vessel is 
 expended, others will have been conveyed to the man, who discharges them in 
 succession. All fires, even the greatest, have small beginnings, and when early 
 discovered, are easily kept under or suppressed. Capt. Manby's fire-cart appears 
 well adapted to check the progress of fires, if not by entirely suppressing them, 
 yet by keeping them within the range of easy extinction by more powerful 
 means, which cannot be so expeditiously applied. 
 
 Fire-engines are now common in every civilized country ; the several kinds of 
 these useful machines having been already fully described, it will only be neces- 
 sary in this place to offer a few practical remarks on their management. In 
 bringing up, placing, and setting a fire-engine to work, great judgment is requi- 
 site, and much will always depend upon the acquaintance of the parties employed 
 with the duty they have to perform. Great activity is required in combination 
 with skilfulness ; six good hands will, at any time, get a large fire-engine to 
 work through two or three forty-feet lengths of hose in about two minutes, 
 supposing water to be at hand. An engine being set to work, its efficient per- 
 formance will depend entirely upon the manner in which the stream of water 
 is directed. The old method was to throw the water into the windows at ran- 
 dom ; latterly, however, a more rational mode of operating has been adopted, 
 and one, the advantage and efficacy of which was strikingly exemplified by the 
 experiments of M. Van Marum, before alluded to. The only successful mode 
 of using a fire-engine, is to take the director or branch-pipe into the building, as 
 near as possible to the fire, and be sure that the stream of water strikes directly 
 upon the burning materials ; this cannot be too often or too anxiously inculcated 
 on every person using a fire-engine. Every other method not having this for 
 its fundamental principle, will, in nine cases out often, utterly fail. When the 
 water is thrown into the building hap-hazard from the street, it is impossible to 
 . y if any of it touches the parts on fire or not, unless the flames appear at the
 
 FIRES. 
 
 523 
 
 windows. On taking the hose and branch pipe inside the building, besides the 
 advantage of the water striking directly upon the fire, there is a great saving in 
 the article of water itself; the whole quantity thrown by the engine is usefully 
 and advantageously applied, and no more is thrown into the building than is 
 absolutely necessary to extinguish the fire. If, on entering an apartment, the 
 flames are found to cover a consider- 
 able space, the thumb should be 
 placed partly over the aperture of 
 the nozle, which will spread the 
 stream of water according to the 
 pressure applied, so as to wash a 
 large surface at once. In encoun- 
 tering fires at close quarters in this 
 manner, much inconvenience arises 
 from the smoke and heat ; to avoid 
 the former, by far the most annoy- 
 ing and dangerous of the two, it be- 
 comes necessary to kneel or lie 
 down, so that the fire may be clearly 
 seen and the water thrown upon it. 
 While in a recumbent posture, a per- 
 son will generally be able to respire 
 air comparatively pure, though stand- 
 ing upright, suffocation would be 
 inevitable : the purest air is always 
 the lowest. 
 
 Mr. Roberts, a miner, invented a 
 " hood and mouth-piece," which 
 enabled the wearer to enter premises 
 when on fire, through the most dense 
 smoke, and reacue human life and 
 property, or apply the most eligible 
 means for extinguishing the flames. 
 Mr. Roberts's apparatus is shown in 
 the accompanying engraving, which 
 is a side view, as it appears on the 
 wearer. It consists of a leather cap 
 or hood a, which entirely covers the 
 head and face, with strong glasses 
 before the eyes. The lower part of 
 the hood is padded with soft cotton, 
 covered with wash leather, which 
 being drawn tight round the neck 
 by a strap and buckle, excludes the 
 surrounding air. The upper part of 
 the proboscis b is of sufficient capa- 
 city to include the nose and mouth 
 of the wearer, and forms the channel 
 through which he respires. A trum- 
 pet-mouthed orifice is formed at c, 
 provided with a good cork stopper, 
 which is secured by a small brass 
 chain ; the use of this appendage is 
 to afford a ready relief to the lungs, 
 without taking off the hood when 
 the wearer goes to the door or win- 
 dow of a building on fire, for the 
 purpose of respiring a purer atmo- 
 sphere, or to consult with persons on the outside. Below this part is attacheu, 
 by means of an union joint, a flexible tube d, about two feet six inches long,
 
 524 
 
 FIRES. 
 
 and terminating in a funnel five inches in diameter, in which is contained a 
 sponge saturated with water. The flexible pipe is kept distended by a spiral 
 coil of wire, and the straps e e are for the purpose of buttoning it to the dress 
 of the wearer, so as not to encumber him, or impede his exertions. The opera- 
 tion of the apparatus is as follows : The gaseous and other noxious matters 
 
 which exist in the apartment, are, by the act of inspiration, obliged to pass 
 through the funnel of the tube, where they are absorbed and neutralized by the 
 liquid contained in the sponge, and the air is sent up to the lungs in a pure 
 sate. The efficacy of the apparatus 
 has been repeatedly proved, in the 
 
 presence of numerous scientific indi- /ffl^^" BHJ Ftg. 2 
 
 viduals, amidst the most dense smoke, 
 arising from the combustion of wool, 
 wet hay, wood shavings, &c., besides 
 large quantities of sulphur, in tem- 
 peratures varying from 90 to 240 of 
 Fahr. 
 
 To obviate, in some measure, the 
 necessity for entering the apartment 
 in which the fire is raging, Mr. 
 George Dodd invented and patented 
 an ingenious contrivance, consisting 
 of a peculiar arrangement of levers 
 and joints connected with the hose 
 of a fire-engine, by which the operator 
 may direct a jetof water to any unseen 
 part of the interior of a ship or house on 
 fire. This will at once be understood 
 on reference to the above engraving, 
 Fig. 1, wherein a person at a is point- 
 ing to the spot where the fire is situ- 
 ated; the operator b then directs 
 the lever c he holds, so as to point 
 to that part ; this movement causes 
 the nozle d to point to the same 
 place, and, consequently, the utmost 
 effect in extinguishing the fire is pro- 
 duced, which is, of course, greatly 
 accelerated by excluding the admis- 
 sion of fresh air. The annexed Fig. 2 
 exhibits a part of the above on a 
 larger scale, showing more exactly 
 the construction of the apparatus by 
 which these effects are produced ; c 
 is the branch pipe of a fire-engine, of a peculiar form, the hose being screwed 
 on at /. If there is no bull's eye in that part of the deck where it becomes
 
 FIRES. 525 
 
 necessary to insert the apparatus, the carpenter would be directed to strike out 
 a hole, as shown at g, through which the branch would be let down to the 
 required position, when it would be made fast by turning the screw h in the 
 ferule i, the aperture below being entirely covered by a large flanch at the 
 bottom of the ferule, as represented. The lever c moves upon a fulcrum, or 
 centre-pin, at the upper end of the branch pipe e, not affixed to the pipe itself, 
 but to another ferule fixed thereon. To this lever is attached, by another 
 centre-pin Jc, the long bar 1 1, which is connected by a pivot-joint to the nose 
 pipe d. It will now be seen, that as the distance between the two joints in the 
 nose pipe is the same as the distance between the two joints in the lever c, a 
 corresponding motion will be produced when operated upon in any direction, 
 upward, downward, horizontally, or obliquely ; and as the connecting rod I is 
 perforated with a number of holes, it may be attached in any part of its length 
 to the lever c, so that the jet may play close under the deck, or far from it. 
 There are several other modifications of the apparatus to suit different circum- 
 stances, but the above explains the principle of action of the whole, which 
 appears calculated to prove useful in stopping fires on ship-board. 
 
 FIRES, PREVENTION OF. Among the various modes which have from time 
 to time been proposed for this purpose, the most useful and important are those 
 relating to the manner in which buildings are constructed. The general prin- 
 ciples to be attended to are simple and briefly stated, viz. the use of incom- 
 bustible materials to the greatest possible extent, and the placing of those 
 necessarily inflammable in situations and under circumstances the most 
 unfavourable for combustion. The incombustible materials commonly employed 
 in building are stone, brick, and metal ; the combustible is timber, in all its 
 various forms. Many ingenious expedients have been resorted to for the 
 purpose of rendering wood fire-proof; solutions of muriate of ammonia, muriate 
 of soda, sal ammoniac, borax, alum, and several other salts and alkalies, have 
 this property to a certain extent. Professor Fuchs, member of the Academy 
 of Science at Munich, invented a composition for making wood fire-proof, 
 which consisted of ten parts potass or soda, fifteen parts fine silicious eai-th, 
 and one part charcoal, mixed together with water. This composition, applied 
 to the surface of wood, forms a vitreous coat, which effectually resists the action 
 of fire. After some decisive experiments had fully established the efficacy of 
 this plan, the Royal Theatre at Munich was protected by the application of 
 this composition ; the surface covered was upwards of four hundred thousand 
 square feet, and the expense, it is said, did not exceed five thousand francs. 
 The following is an English composition for the like purpose : one part, by 
 measure, of fine sand, two parts wood ashes, and three parts slacked lime, 
 fTound together in oil, and laid on with a painter's brush, the first coat thin, 
 the second thick. This forms a very strong and adhesive coating, which is 
 both fire and water-proof. There are, in general, however, many practical 
 objections to the use of these preventives ; and the more feasible method of 
 obtaining the desired security appears to be in the judicious selection and 
 skilful disposition of the materials most commonly employed. Bricks form the 
 staple material for building in most of the towns in this country, and with them 
 the external walls are usually constructed ; where due attention is paid to the 
 prevention of fire, the partitions will be of the same material. If circumstances 
 permit it, brick arches will also be used for supports. When it is desirable, for 
 the purposes of trade, &c. to support the walls on brestsummers, those of cast 
 iron are employed. Pillars of the same material are also frequently used with 
 advantage to support fronts of considerable length. In this way the skeleton 
 or frame-work of a building is easily completed in a fire-proof manner. The 
 next thing, then, to be attended to, is the floor; and here we find caution 
 extremely necessary, as the security of the building depends greatly upon the 
 manner in which the floors are constructed. In dwelling houses, floors of wood 
 are essential to an Englishman's notion of comfort; nor is there any real 
 difficulty in obtaining them of this material perfectly compatible with the end 
 now under consideration. There is a particular description of floor occasionally 
 used in Edinburgh, which, although not absolutely fire-proof, is certainly almost 
 3 x
 
 526 FIRES. 
 
 practically so. It is composed simply of plank, two and a half or three inches 
 thick, so closely joined and so nicely fitted to each other and to the walls, as to 
 be completely air tight. Its thickness, and its property of being air tight, will 
 readily be observed to be its only cause of safety. A floor of a somewhat 
 similar kind has been employed in the neighbourhood of Manchester with 
 success; the planks are about three inches thick, jointed and ploughed on the 
 edges for the purpose of receiving slips of iron called tongues, that enter some 
 distance into each board ; this makes a tight and substantial floor, which, as 
 well as the former, should be laid on iron joists. Great protection is capable of 
 being given to boarded floors, by using a strong fire-proof cement for the ceilings; 
 the plaster at present employed is so to a certain extent, but this may be greatly 
 improved. If a fire occurred in a room protected in this manner, the chance 
 is more than ten to one that it would burn itself out before it could ignite the 
 building. It would be very difficult to set fire to the floor, from the natural 
 tendency of flame and heat to ascend ; it would be still more difficult to ignite 
 the ceiling, from the resistance offered to the flames by cement, iron joists, 
 and, finally, by the closeness of the flooring. If the fire should not, however, 
 be entirely repulsed, still its progress would be so greatly retarded as to afford 
 plenty of time for the successful application of the usual modes of suppression. 
 Before quitting this subject, however, there are some kinds of floors veritably 
 fire-proof, which could not with propriety be omitted. At Manchester, fire-proof 
 floors have been constructed in the following manner : the columns and beams 
 are of cast iron, and are firmly secured in their places with wrought-iron bars 
 that traverse from beam to beam. Upon a margin underside the beam spring 
 arches of brick work ; these are filled to a level on their upper side with hard 
 rubbish, and then covered with flags or tiles. 
 
 Mr. Frost, builder, of Bankside, London, has succeeded in forming excellent 
 floors and roofs to houses, of hollow earthenware tubes and cement, so combined 
 as to form a floor as strong as one of timber, but perfectly fire-proof. The 
 hollow tubes are square in the section, and are made of brick earth, prepared 
 by machinery in a very superior manner ; they are placed in strata in opposite 
 directions, and cemented together. The floor or flat roof thus produced, is, in 
 effect, one solid flag stone of the size required, but not one-fifth the weight of 
 stone. The cement which Mr. Frost employs is thus formed : chalk is ground 
 fine in a mill, and, as it is ground, mixed with water, which carries its lighter 
 particles to a reservoir. Clay is ground at the same time, and, mixed with 
 water, is conveyed in the manner before mentioned. This combination 
 of chalk with about thirty per cent, of clay, is drained, and left to evaporate 
 to dryness. The mixture is then broken up, burnt in a kiln, and after being 
 ground to powder, it is closely packed in casks; in this state it will keep for 
 any period, and may be sent to any distance. Mr. Frost's floors have many 
 recommendations, and his cement affords a very convenient mode of protecting 
 various parts of buildings from the action of fire. 
 
 Mr. Farrow, of Great Tower-street, London, took out a patent a few years 
 since for a new method of constructing fire-proof buildings, a large model of 
 which was erected in Mark-lane, for public inspection. The walls are of coarse 
 brick or stone, built in the usual manner. The joists are of wrought iron ; they 
 are formed with a lateral projecting flange on each side, upon which are laid, 
 from joist to joist, a series of flat stones, and of sufficient thickness (from two 
 to two and a half inches,) to lie flush with the upper edge of the joist, forming 
 a level floor of stone interlined with iron : it may be used in this state, or 
 covered with planks, according to the purposes of the apartment. The eiyjs 
 of the joists are turned down and let into bond stone laid upon the walls, and 
 cemented or run in with lead, which, with the weight of the walls, continued 
 upward, takes off the elasticity of the iron, so as to enable the joists to carry 
 almost any weight, and at the same time ties the walls together in such a 
 manner as to render it impossible for them to separate. The boarded floors are 
 grooved into the edge of the joists about half an inch, and when dowelled, will 
 require very little fastening down. But where it is necessary, a stub is let 
 into the stone floor, and screwed to the edge of the board; there are, therefor^
 
 FIRE-PLACES. 527 
 
 no nails necessary, nor any other fastenings visible when the floors are finished. 
 The under part of the stone is stabbed or made. rough, so as to form a good key 
 for the ceiling, therefore no laths are necessary, and the whole floor occupies no 
 more than from four to five inches in depth. A roof is the same ; and, being 
 covered with mastic, is, according to the statement of the patentee, the cheapest 
 roof ever invented, with the important advantages of being fire, air, and water- 
 proof. These floors have been successfully employed in some sugar refineries, 
 and other premises liable to accident from fire, and are admirably adapted to 
 prevent this calamity. Having thus briefly described some of the most important 
 facts relative to floors, we proceed to state that the most material part of all 
 buildings, so far as prevention of fire is concerned, is the staircase, for this part, 
 above all others, acts as a conductor, and greatly assists the spreading of the 
 flames. When a fire is discovered before it has gained possession of the stairs, 
 its suppression is comparatively easy ; but the staircase once on fire, there is 
 but slight chance of saving the building. Effectually to prevent the spread of 
 fire, therefore, it is absolutely necessary that the stairs should be wholly com- 
 posed of some incombustible substance. In many places on the continent the 
 stairs are always of stone, which is quite sufficient to account for the speedy 
 manner in which conflagrations are extinguished by the fire associations of 
 those countries, where, although the number of fires are considerable, the 
 amount of damage is usually very small. Nothing gives a more elegant appear- 
 ance to a house than a clean well-proportioned stone staircase, and this material 
 is by far the most eligible for the purpose ; economy, however, may dictate the 
 employment of a cheaper material without prejudice to the effect. In ordinary 
 dwelling houses it is necessary that the roof should be as light as practicable, 
 nor is it very essential to bestow fire-proof qualities on this part ; but in manu- 
 factories and public edifices it becomes desirable to render the building fire-proof 
 throughout. This is done in some cases by using cast-iron framed roofs, with 
 metallic or other covering. At the New Palace, in St. James's-park, the builder, 
 Mr. John Richardson, of Spencer-street, introduced fire-proof floors and roofs, 
 composed of hollow earthen coombs or pots, invented some thirty years before, 
 and first used at Knight's Hill, near Dulwich, the seat of Lord Thurlow. The 
 coombs are arranged in arches, springing from stone abutments resting on the 
 flanges of the iron girders ; the spandrils of the arches are filled up with brick 
 work, forming a level roof, which is covered with hot cement. This cement is 
 composed of chalk, coal tar, and sand. The first coat being levelled with heated 
 irons, is suffered to harden ; a second coat is then applied, and the slates 
 embedded in the cement while it is hot Woeful experience has shown that 
 the defective construction of chimneys and setting of stoves have been a fruitful 
 source of fires ; a slight attention to these points would be sufficient to remedy 
 the evils arising from this cause. Lateral openings are sometimes imprudently 
 suffered to remain, communicating between the chimney and sides of the 
 room ; these places in time become filled with soot, which a falling spark 
 ignites, and sets fire to the apartment. No beam should on any account be 
 permitted to enter a chimney ; this was too common formerly, and has caused 
 the destruction of many buildings. An act of parliament, passed some years 
 back, for regulating buildings, and so preventing the spread of fires, has tended 
 in some degree to remedy the evils just referred to ; this act, however, contains 
 many incongruities, and it stands greatly in need of that revision which it is 
 expected very soon to undergo. It would doubtless be both useful and inte- 
 resting to follow out the subject of fire prevention, and detail the cautions 
 necessary to be observed in the application of fire-heat to manufacturing 
 processes, as well as the management of fire and light in the arrangements of 
 domestic economy. The limits of this work, however, will not permit us to 
 extend the present article ; but in many of those that follow we shall have 
 occasion to make some observations on the subject. 
 
 FIRE-PLACE is a general term given to the brick, stone, and iron-work, 
 which constitute the apparatus for heating the apartments of dwelling-houses, 
 and for performing culinary and other domestic operations, to which the various 
 names of stoves, stove-grate, grate, and range, are given ; but as it would be
 
 528 
 
 FIRE-PLACES. 
 
 uninteresting and useless to explain, in this place, the bath, pantheon, rumford, 
 and other common open stoves and ranges, with which every eye is fami- 
 liarized, we shall confine our notice to the leading features, (stripped of all 
 ornament), of those deviations from the ordinary apparatus, which are regarded 
 as improvements upon the before-mentioned. It has been remarked, that 
 Englishmen, who boast so much of their firesides, and who are the greatest and 
 most skilful manufacturers of iron work in the world, are generally the worst 
 provided with the means of comfortable warmth of any civilized nation. 
 The mode almost universally adopted for increasing the temperature of our 
 apartments by the common open stoves, supplied, as they are, with air drawn 
 from around the chilled persons of its occupants, is perhaps as wasteful and 
 inefficient as could be designed. Full nine-tenths of the heat generated in 
 the grate is rapidly conducted away up the chimney into the atmosphere, while 
 the remaining feeble tenth is radiated into the apartment. The introduction 
 of the register stoves, about thirty years ago, undoubtedly effected a considerable 
 mitigation of the evil just mentioned. These stoves, filling up the entire 
 opening of the fire place, and being provided with a flap door at the upper part 
 of the back, which can be opened and shut, more or less, according to the state 
 of the fire, and the emission of the smoke, check in some degree the current 
 of cold air which is constantly rushing to the fire-place to fill up the vacuum 
 in the chimney, and support the combustion of the fuel in the grate. When 
 there is only a little, or a very clear fire in the grate, the flap door may be 
 almost closed, in which state it prevents the falling of soot into the apartment. 
 There is, however, this objection to such stoves being made entirely of metal, 
 which, from its great conductibility, is not so economical with respect to the 
 fuel as the following, and some others of a very humble kind. 
 
 Irish Stove. Mr. Buchanan, in his Essay on the Economy of Fuel, relates, 
 that on landing in Ireland, he was much struck with the excellent construction 
 of the fire-grate in the room of the inn where he lodged. He at first thought 
 it was an invention of his landlord's, but on proceeding on his journey, he 
 found the same kind of grates common in that part of Ireland. Fig. 1 repre- 
 sents a front elevation, and Fig. 2 a transverse vertical section of one of these 
 fire-places, which appear well calculated to remedy the smoking of chimneys, 
 
 Fig. 1. 
 
 Fig. 2. 
 
 and, at the same time, to lessen the consumption of fuel. The fire room is 
 wide and shallow, presenting the greater surface of fire to the room, and 
 thereby radiating the greatest quantity of heat into it. The upper portion 
 of the chimney recess is partly closed by an upright slab of fire stone, in 
 which is cut an arch. The back wall is formed of fire stone, or fire brick, into 
 an oval niche, and the throat of the chimney is made very small to increase 
 the velocity of the air, and thus enable it the better to carry off the smoke. 
 
 Birmingham Stove. The stoves in common use in Staffordshire and War- 
 wickshire, although not so elegant as those made in London and Nottingham
 
 FIRE-PLACES. 
 
 529 
 
 for the same class of rooms, are far more judiciously disposed for diffusing 
 warmth. Instead of the usual recess in the brickwork for the reception of the 
 stove, the wall is built up in front from the ground to the mantel, and flush with 
 it, leaving only an aperture of eight or nine inches square for the passage of 
 smoke into the chimney ; this is situated just above the back of the stove, 
 which is placed against this wall, projecting its whole depth entirely into the 
 room. 
 
 Open Firts. There is, from long custom, so great a desire among all ranks 
 in England to see the ike that warms, their apartments, that the most con- 
 venient, cleanest, and cheapest methods of heating them, are sacrificed to 
 this single circumstance. Accordingly, persons who attempt the improvement 
 of stoves are compelled to endeavour to combine what appears to be irrecon- 
 cilable, namely, the appearance of a bright open fire, with an economy of fuel, 
 regularity of temperature, and without producing a draught through the apart- 
 ment. Of the various contrivances in which the attainment of these proper- 
 ties have been attempted, there are but few worthy of notice. 
 
 Sir George O. Paul's Stove. This stove may, at pleasure, be made either an 
 open fire-place, or a close stove, heating the room by the radiation of the heat 
 from its front wall ; and when thus acting as a close stove, it serves as a ven- 
 tilator of the apartments with which it is connected. The fire-place is of the 
 ordinary dimensions. Folding doors are made to close the fronts of the ash- 
 pit, and to fall back against the hobs ; other folding doors are made to close the 
 front of the grate, and to fall back against the sides. The top of the fire grate 
 was also provided with a floor, which formed a back when open, but when shut 
 down horizontally, left only a small cavity, and produced a strong draught. It 
 was supplied with air by tunnels underneath the hobs. Although the utility of 
 this stove was satisfactorily proved in Gloucester gaol, and other places, its 
 clumsy inelegant appearance prevented an extensive adoption. Mr. Marriott 
 has, however, so modified it as to remove the above-mentioned objection, and 
 has recently brought it before the public in the following form. The shadowed 
 compartments a and b are recesses 
 just of sufficient depth to admit of 
 the doors e e and //, when folded 
 back, to lie flush with the other 
 parts of the front of the stove, as 
 is the case with those marked e 
 and d. We have thus arranged 
 them in the drawing merely to 
 render the matter quite clear to 
 the eye, not that such positions of 
 the doors are peculiarly eligible, 
 (nevertheless cases may be ima- 
 gined wherein they would be so, 
 such as screening particular objects 
 from the influence of the fire, or 
 increasing the combustion of a 
 particular part of the fuel, by 
 altering the direction of the cur- 
 rent of air.) In lighting a fire, or 
 in replenishing one that is low, the combustion is greatly excited by shutting 
 the four upper doors, which act as a "blower." On the contrary, when a fire 
 burns too rapidly, or is not much wanted, the four lower doors may be shut, 
 which will damp it immediately, yet allow a great portion of the heat to radiate 
 into the room. On retiring to bed, or wishing to leave the room in perfect 
 security from fire, all the doors may be closed, when the fire will infallibly go 
 out for want of draught. To keep in the fire, and yet leave the room in safety, 
 or to prevent the radiation of much heat and light in a room (often desirable 
 in the chamber of the sick), the doors may be placed thus "V V". For such 
 chimneys as occasionally return their smoke, or in which the draught is feeble, 
 these stoves will, we doubt not, be also found very convenient and advantageous
 
 530 
 
 FIRE-PLACES. 
 
 Pycroffs Patent Fire Stove. Mr. Pycroft, of Rolleston, near Burton-upon- 
 Trent, took out a patent for improvements in fire-places, in 1831, the principle 
 of which consists in connecting with the fire stove a chamber for hot air, to he 
 admitted at pleasure either into the apartment where the fire is situated, or into 
 one adjoining thereto. The hot-air chamber extends from below, up behind, 
 and on each side, and over the top, under the mantel. The air passes into the 
 chamber by a series of registers situated below the fire, and when heated, 
 passes out into the chamber by a series of registers situated aver the fire. 
 When it is intended, for the sake of ventilation, to receive the air to be heated 
 from the external atmosphere, instead of from the room where the fire is situ- 
 ated, the registers below the fire must be closed, and a communication opened 
 between the external air and the lower part of the chamber ; and when it is 
 intended to throw heated air into an adjoining apartment above the fire, the 
 registers are to be closed, and a communication opened between the upper part 
 of the chamber and the apartment to be heated. For the purpose of exciting 
 a draught at pleasure, and of preventing any smoke issuing into the room, a 
 hood or blower is hinged to the upper part of the grate, which may be brought 
 out towards the front or top bar of the fire. Behind this is another hood or 
 blower, which is raised or lowered by a knob passing through the first ; this 
 inner hood is provided with angular side-flaps, which, when the blower is 
 brought down and projected forwards, inclose the side of the fire. This stove 
 has likewise a flap valve at the back, acted upon by a handle in front, by which 
 the flue or throat into the chimney may be regulated in its dimensions, and the 
 draught increased, diminished, or entirely stopped at pleasure. 
 
 Cutler's Patent Stoves. This invention, 
 when first brought before the public in 1815, 
 met with considerable patronage ; but it is now, 
 we believe, but little used, owing to some 
 difficulties of a slight description, for which 
 ho sufficient remedy has yet been provided. 
 The spirit of enterprise which originated the 
 invention received, we have been informed, 
 a severe check, by the numerous and com- 
 bined attempts of rival manufacturers to invade 
 and destroy the patent right, which is now 
 expired. The principle of the contrivance is, 
 however good, and will probably, under able 
 management, become a valuable apparatus. 
 The invention consists in the construction of 
 stoves and fire-places in such a manner as 
 that the fuel necessary for combustion shall 
 be raised and supplied from a close chamber 
 beneath, where the upper stratum of coal 
 shall be constantly undergoing the process of 
 coking, the gas from which becomes ignited 
 in passing through the open part of the grate 
 above, and by causing the said chamber to 
 descend at pleasure, so as to extinguish the 
 fire. The figure represents a vertical section 
 of a register stove, presenting an end or side 
 view ; a is one of the front pilasters ; 6 the en- 
 tablature ; c the back ; d the chimney, the 
 entrance to which is shown by the curved 
 arrow ; e the top plate, turning upon hinge 
 joints, to be raised up whenever required for 
 sweeping ; this top does not fill up the space 
 accurately, but leaves a narrow opening at /, 
 for the escape of the vapour and dust that may 
 arise prior to the current being established in 
 the direction of the arrow, by the effects of the combustion ; g are the front grate 
 
 d
 
 FIRE-PLACES. 
 
 531 
 
 bars ; h the receptacle of the coals, including i, the place (as usual) where they 
 are burned. As the air which finds its way into the close box A, is only sufficient 
 to coke the coals, their perfect combustion is not effected until they are raised 
 aoove the front plate k, at which place the air pours in on all four sides, between 
 the bars in front, through the side grates, one of which is shown at I, and from 
 an aperture at o, under the bottom edge of the back ; p is a vertical groove, in 
 which the bar q (seen endways) traverses up and down, supporting the movable 
 bottom plate of the coal box h. To each end of this bar, exteriorly, is attached 
 a chain r, which thereby suspends the coal chamber (or movable bottom), by 
 an horizontal roller s, extending across the stove. This roller is the shaft or 
 axis of a cog-wheel t, and is put in motion by a pinion u ; the axis of u is a 
 small square pin, fitting into the cavity of the winch v ; the turning round of 
 the latter winds the chain upon the roller, and elevates the movable bottom q, 
 which raises the coals, as they may be required for combustion, to supply the 
 place of those which have been consumed. On turning the winch the contrary 
 way, the bottom of the coal receptacle descends by its own gravity, and that of 
 the coals resting on it, as far as the plate x, when the fire dies away for want 
 of air. The patentee employs a pall and ratchet to stop the action of the 
 roller, which is operated upon by pressing upon a pin, placed externally. Two 
 objections have been urged against these stoves ; one, that the current of air 
 passing through it makes an unpleasant roaring noise, like that of an air 
 furnace ; the other, that the expansion of the coals in undergoing the process 
 of coking prior to being raised into the open part of the fire, causes them to 
 adhere so fast to the sides, as to render the friction excessive, and the labour 
 great, of raising up and getting down the coals. These objections are, how- 
 ever, we believe, not of an insuperable character, and may be overcome by 
 mechanical skill. 
 
 Mrs. Smith's Stove. A plan of a stove designed for burning its own smoke, 
 was communicated by Mrs. Rachel Smith to a periodical journal, which seems 
 susceptible, by its simplicity of construction and soundness of principle, to be 
 made effective for the object intended The stove is made exteriorly of the 
 usual form, excepting that the fire part / is of greater length or height than is 
 
 common, and the spaces under the hobs are made into reservoirs to receive the 
 coals, as shown at c c, for supplying the fire. The hobs are upon hinges, and 
 form lids, which shut down very closely, if air tight, the better. The cheeks 
 of the grate are open at the bottom, so that the coals lying upon the inclined 
 planes of the reservoirs descend by their own weight, and occupy the lower 
 part of the grate ; and as the fuel is consumed, or raised by the poker, a fresh 
 portion of coals enters from either or both of the reservoirs, and fills up the 
 space. In this manner the fuel is constantly supplied, occasioning little or no 
 smoke. The reservoirs should be of a capacity sufficient to hold enough coals 
 for the day's consumption.
 
 532 
 
 Fi RE- PLACES 
 
 Atkins's Patent Stove. Messrs. Atkins and Marriott had a joint patent for a 
 smoke-consuming stove on the principle of the last described, which they 
 manufactured in a style of great elegance, and adapted to the various situations 
 and applications of domestic stoves. The patentees state their objects to be, 
 first, to afford a remed^ for smoky chimneys ; and secondly, to economize fuel, 
 and regulate the heat evolved from stoves or grates for warming apartments, 
 and for the various operations of cooking. In order to effect the combustion 
 of the smoke, the coals are thrown into a coal chamber at the back of the 
 grate, which is closed by a door. At the lower part of this chamber there is 
 an opening through the back into the grate, the interior of the box being formed 
 so as to throw the coals forward to supply the grate when necessary. The other 
 improvement made by the patentees consists of an appendage, in lieu of a 
 fender, attached to the front and lower part of any kind of stove or grate, which 
 they denominate a basement. This basement they usually make of a convenient 
 inclination, to put the feet upon, but it may be made of any figure or dimensions 
 according to individual taste. It is provided with a drawer or box to receive 
 the ashes, beneath the fire, and with apertures in front to admit air beneath the 
 fire bars. The whole of the interior of this basement, except the ash box, is 
 filled with a mixture of pulverized charcoal and lime ; the stove has also a 
 canopy or cornice filled with similar slow conductors of heat ; also each side of 
 the grate, as well as a part of the back, are provided in like manner. The effect 
 of these appendages, in retaining that portion of heat which is nearly all lost 
 to the apartment in other stoves, is doubtless very great ; we are, indeed, credibly 
 informed that it will preserve nearly the same temperature in a room for several 
 hours after the fire is extinguished. These stoves have pipes or passages for 
 allowing a column of air to ascend through the basement and upper portion, 
 which becomes warmed in its passage, and flows out into the apartment above. 
 
 Jacomb's Patent Grates. The principle of this invention also consists in 
 placing the fresh fuel underneath the ignited portion ; but the mode of carrying 
 it into effect is peculiar. The stove is a kind of grated cage, cylindrical or 
 parallelopipedal, turning upon axes, which are mounted on side standards. 
 On two of the 
 serving alterm 
 are supplied a 
 
 grate turned half round, so as to bring the fresh fuel underneath, by which 
 means the gas emitted becomes inflamed in its ascent through the ignited fuel 
 above. The selection of the materials, and the diversification of designs and 
 proportions for the construction of stoves, will of course depend upon the uses 
 to which they are applied ; but we will select, as an example, the following one 
 adapted for a parlour. Fig. 1 is a front view, and Fig. 2 is a side view, a a 
 
 are the axes, which rest and slide in horizontal, grooves b. The two doors 
 before mentioned, represented in Fig. 5, are made fast by catches x x. The 
 stove is put into action by b'ghting a fire in the ordinary manner with coal or
 
 TIRE-PLACES. 533 
 
 other fuel, as near as possible at the top, preferring to place uppermost the 
 cinders, and green coal undermost ; the fire will then gradually find its way to 
 the bottom, burning with little or no smoke, which, together with the gas or 
 vapour, is consumed as emitted. When fresh fuel is required, it is to be placed 
 on the top of the ignited fuel, and the door shut down and secured by the catch 
 x ; the grate is then to be drawn forward in the groove b, and turned round 
 one half of a revolution on its axis, and then be returned back again to its 
 former position in the groove. 
 
 Lloyd's Patent Stove consists in the adaptation of a box in a recess at the 
 back of an ordinary register or other stove, for the reception of sufficient coals 
 for a day's consumption, which are to be drawn forward into the fire as they 
 may be wanted, and thus supersede the use of the coal scuttle, an utensil 
 which has certainly its inconveniences. That this operation may be performed 
 with facility, the box at the back of the stove is closed with a sliding door, the 
 weight of which is supported by a counterbalance suspended over a pulley ; it 
 is therefore drawn up or let down with ease, by means of a small handle placed 
 conveniently, when the coals may be raked on to the fire by means of the 
 poker. 
 
 Smolce-consuming Stove. The annexed cut is 
 illustrative of a design, by an anonymous inventor, 
 for a stove to consume its own smoke. We are not 
 aware of its having ever been constnicted, but as it 
 presents a novel and elegant arrangement of parts, 
 calculated to answer the intended purpose in judi- 
 cious hands, we give it insertion. The inventor 
 proposes that the smoke from the fresh fuel shall 
 be allowed to ascend up a short flue, and then 
 descend and rise again through a tube placed in 
 the middle of the fire, after which the tube conducts 
 the remaining incombustible gases into the chimney. 
 The intense heat of the tube which rises through 
 the fire must necessarily burn the smoke, economize 
 fuel, and increase the temperature of the room. 
 
 Silvester's Patent Sieve. The common methods . 
 
 of heating buildings by means of hot air stoves had 
 
 been much and justly complained of, from the salubrity of tlie air being fre- 
 quently injured by its coming in contact with the surface of a stove compara- 
 tively small, but intensely heated ; and to remedy this evil, the late Mr. Silvester 
 introduced cockle stoves, first in the Infirmary of Derby, and afterwards in 
 many other places, with large heating surfaces, that they might be sufficient to 
 heat moderately a large quantity of air, but not to be heated so high as to 
 injure any portion of it ; and thus was obtained an extensive ventilation by 
 air moderately warmed. (See AIR.) Still, however, stoves of this kind, 
 without considerable care and skill on the part of the firemen, were liable to 
 become over-heated, and at times to deteriorate the air; and to obviate the 
 possibility of this defect seems to be a principal object with the present 
 patentee. He proposes, hi the first place, to lower the fire grate, till the bottom 
 bars are on a level with the surface of the floor of the room in which it is 
 placed. The fire bars are prolonged and widened to touch each other in front 
 of the fire, so as to form a hearth. They require no fastening into their places, 
 but simply to be laid upon appropriate bearings at each end. There are grooves 
 made on the under sides of the fire bars, for the admission of fresh air for 
 supporting the combustion of the fuel within the grate, and for the escape of 
 hot air into the room. It is stated that the bars may be either made of equaj 
 lengths, to constitute a rectilineal hearth, or of different lengths, to constitute a 
 curvilineal one, at pleasure. When the ash pit, which is situated below the 
 fire in the usual manner, requires clearing out, a few of the fire bars are to be 
 removed, which can be effected with facility, as they are not made fast to any 
 thing. Mr. Silvester proposes, in the second place, to surround at least three 
 sides of his fire with a vessel containing water, and upon the exterior of this 
 3 Y
 
 534 
 
 FIRE- ['LACES. 
 
 water vessel he causes a large quantity of cold air to impinge, that its tem- 
 perature may be elevated sufficiently to communicate the required degree of 
 neat or ventilation to any adjacent apartments to which it may be conveyed. 
 For the purpose of conveying the cold air to, and the heated air from, the 
 water vessel, the patentee proposes to employ apparatus of the same description 
 as that employed with the hot air cockles invented by his father. 
 
 Gaunt and Ecksteins Grate. The stove designed by these gentlemen (for 
 which they had a patent in 1831 ,) has a grate of bars, of a semi-elliptical form, 
 attached to a straight back, which is brought much further forward than are 
 the backs of stoves of the usual construction, by which arrangement three 
 sides, or what is equivalent to three sides, of the fire, is in a situation to radiate 
 heat into the room. Immediately over the fire is placed a metallic hood, which 
 receives and radiates into the room a portion of the heat which would otherwise 
 pass up the chimney The distance between the fire and hood is diminished 
 and increased at pleasure, by elevating or depressing the grate containing the 
 fire, and thus is obtained the means of increasing or diminishing at pleasure 
 the draft of the fire, and of preventing *he escape of smoke into the room. 
 The change in the altitude of the grata is effected by means of projections 
 from the grate passing through vertical slits in the back, which projections are 
 joined together by a cross bar, attached to a lever by a connecting link ; this 
 lever has on its exterior end a toothed sector, which is actuated by a small 
 pinion, whose axis receives a regulating winch, passing through a small hole in 
 the back. This hole, with the pinion axis, is the only part connected with the 
 rising apparatus which is visible in front, which admits of their being manu- 
 factured in a style of great elegance and neatness. 
 
 Maw's Stove. This apparatus, for which Lieut. Maw obtained a patent in 
 1831, consists in the introduction of a fuel drawer, or receptacle for the fuel, 
 which is placed under a grate of the usual construction, in order that the most 
 volatile portion of the fuel may be liberated and be consumed in its ascent through 
 the fire ; and when the coal has thus, by parting with its gaseous matter, been 
 converted into coke, it is to be removed from the fuel receptacle, and placed 
 upon the fire, leaving the receptacle at liberty for the introduction of another 
 supply of fresh fuel. A front elevation of one of Lieut. Maw's fire grates is 
 
 Fig. 2. 
 
 exhibited in the above cut at Fig. 1, and a sectional side view, Fig. 2, wherein 
 a shows a grate of the usual construction, and b a fuel drawer or receptacle, 
 having a grating underneath, for the admission of atmospheric air to maintain 
 the combustion. The openings in the grating between the fire and the fuel 
 receptacle are made at some distance from th? front, that the volatile matter, 
 in its ascent, may not pass so near the front of the fire as to be cooled, lest it 
 escape without being consumed. The advantages which would result from 
 having the fuel supplied to a fire under the ignited portion, have been long 
 acknowledged ; and of the various plans that have been proposed, we do not 
 think there is one so well calculated to answer the purpose of burning the 
 smoke as that of Lieut. Maw. 
 
 Witty 1 & Fire Places. Mr. Witty, by a judicious attention to proportions,
 
 FIRE-PLACES. 535 
 
 and the conveniences required, has succeeded in adapting the original invention 
 of Watt (described under the word FURNACE,) to domestic stoves, particularly 
 those of the close kind. Mr. Witty has, however, unadvisedly taken out a 
 patent for these stoves, although we can discover nothing that is original in the 
 principle nor in the arrangement of the parts. Some elegant and very effective 
 stoves on this plan may be seen at the Museum of National Manufactures and 
 the Mechanic Arts, in Leicester-square. 
 
 Nott's Patent Furnaces. A very effective kind of close stove, particularly 
 adapted to large rooms, halls, and churches, and possessing considerable 
 novelty of appearance, has lately been introduced into this country by 
 Mr. J. B. Nott, from the United States. In the upper part of a low pedestal 
 is a large capacious chamber, capable of holding a sufficient supply of coals for 
 the day's consumption ; from this receptacle the coals gradually sink down, as 
 they are consumed, in front of the grate, and are deposited upon an arched 
 grating, supported upon a pivot, upon which it is made to oscillate, (by using 
 the poker as a lever for that purpose,) and thereby clear the bars of ashes ; and 
 when it may be necessary to clear or put out the fire entirely, the said vibrating 
 grating is moved through a greater angle, by which all the ignited fuel thereon 
 is thrown out at either end of the arch. To give the lively appearance of an 
 open fire, and the security of a close stove, the front of the stove is enclosed by 
 windows of talc, through which the glowing fuel is seen. The air is admitted 
 for lighting the fire by leaving the ash-pit drawer a little way open, and when 
 ignition is complete, the drawer may be entirely shut, as sufficient air finds its 
 way through the imperfect junctions or fittings of the metal, to preserve a vivid 
 combustion of the fuel. The fire chamber is encased in fire brick, or some 
 other suitable slow conductor, which prevents the surrounding cast iron from 
 obtaining that high temperature which is found to deteriorate the air of the 
 apartment, and the heat is in consequence more uniformly diffused over the 
 other parts of the structure, which presents altogether a very extensive surface 
 of metal for the radiation of heat, principally derived from a tall ornamented 
 chimney, of a flat pyramidal or pilaster-like form. In this chimney there is a 
 turn valve, to regulate the egress of air, the action of which, together with the 
 management of the ingress crevice at the ash-pit drawer, determines the 
 quantity of heat or the rate of combustion of the fuel. In fitting a stove of 
 this kind to a room having the ordinary cavity for the fire-place, Mr. Nott 
 converts the latter into a hot air chamber, and places his close stove upon the 
 hearth in front. A stove of this kind is employed for warming the extensive 
 range of rooms at the Museum of National Manufactures and the Mechanic 
 Arts, in Leicester-square, which it does most efficiently, with very great economy 
 of fuel. Anthracite, or stone coal, which is almost wholly free from bituminous 
 matter, and emits, in consequence, scarcely any smoke, may be very advan- 
 tageously burned in stoves of this kind. 
 
 German, Pyramidal, Pedestal, Sarcophagus, 8fc. Stoves. All grates of this 
 class are, strictly speaking, close stoves, the fire being entirely shut up within 
 them, the flue or chimney usually consisting of a metallic pipe, which is con- 
 ducted through the walls of the room to the external atmosphere. The German 
 stove is a vertical cylinder of sheet iron, mounted upon legs, having internally, 
 and about midway, a short cylinder of cast iron, with a grating at bottom, 
 which constitutes the fire room, and underneath is the ash pit. The tops, 
 which are variously formed to suit particular purposes, are made to take on and 
 off, so as to allow of baths, boilers, or retorts, to fill up the aperture, and thus 
 become the cover to the upper part of the furnace ; the application of heat is 
 thus very convenient and effective, and is much used for chemical processes, 
 and manufacturing operations on the small scale. The pyramidal, pedestal, and 
 sarcophagus stoves are of similar internal construction to the German or 
 cylinder stoves, but they are usually of cast iron, and designed with a view to 
 ornament as well as utility : their external forms are explained by their names. 
 
 Having now described the principal varieties of stove grates or fire-places in 
 their most improved forms, (including air stoves, which will be found under the 
 article AIR), we shall close this part of the subject by a few observations on the
 
 536 FIRfe-PL,ACES 
 
 proper construction of fire-places in general, in order that the reader may 
 understand the defects that may exist in his own, and know how to apply the 
 remedy. In open fires the bars should not be larger than is necessary for 
 strength, as they obstruct the radiation of heat, and prevent the egress of air, 
 which is requisite for making the fire burn clear. To attain a clear fire, 
 Mr. Tredgold justly says, that the sides of the burning fuel should be at least half 
 surrounded with slow conductors of heat, otherwise the heat developed will pass 
 off so quickly by conduction, that the fuel will burn dead, and that heat which 
 ought to be radiated will be expended in warming the walls, &c. behind the 
 fire. Iron is a very rapid conductor of heat, and therefore it should be used 
 as sparingly as possible. Fire brick, a slow conductor, is employed with much 
 advantage for the backs and ends of grates by a few manufacturers, but iron- 
 mongers in general seem to think it more desirable to use iron than to economize 
 fuel, or to work on sound principles. But when a fire-place, made of slow 
 conducting materials, is large and filled with fuel, as soon as the fire becomes 
 bright the heat is extremely intense and scorching ; when the fire is in this 
 state it is often too powerful for the room, though perhaps barely sufficient 
 when the combustion is less perfect. This may be remedied by any method 
 which enables us to expose a greater surface of hot matter with the same bulk 
 of fuel, and at a lower degree of heat. Some time ago " fire balls," (spheres 
 made of baked clay,) were used with this object ; but their inconvenience, when 
 not judiciously attended to, brought them into disrepute. An improved 
 substitute for them has been suggested by Mr. Tredgold, when the fire is 
 of greater length than 18 inches ; that of building a projection from the back 
 of the grate (and of the same depth) to within three inches of the front bars. 
 This projection should be of good fire brick, and built firmly in with the other 
 part of the back. Thus is left a space for a sufficient body of fire on each side, 
 and the surface is increased without adding to the mass of burning fuel. 
 The combustion of the fuel in an open grate should not be faster than is 
 necessary to produce a clear fire. To guard against the loss of heat by the 
 warm air of the room ascending the chimney, two partial remedies have been 
 adopted that of lowering the mantel, and contracting the throat of the 
 chimney ; but the first of these remedies impairs the ventilation of the room, 
 and the second, causing a rapid draught, increases the consumption of fuel. 
 For some rules in duly proportioning the flues, see the article CHIMNEY. A 
 grate should offer as little obstruction as possible to the radiation of heat, and 
 therefore the usual mass of metal below the front bars, called a fret, is objec- 
 tionable ; and the sectional form of bars should be that of a wedge, with the 
 sharp extremity rounded off, which part should be inside, or next to the fuel, 
 as it is advantageous to have as little metal as possible in contact with the fuel. 
 There is, however, no objection to the employment of metallic covings, as 
 reflectors of heat, when separated by a slow conductor from the metal of the 
 grate ; and instead of these being blackened, as they are usually in the common 
 Rumford stoves, they should be bright or polished surfaces, and preferably of 
 brass to the other common metals. The angle best suited for the covings is 
 45 with the front line of the grate. The height of the grate from the floor is an 
 object of some importance ; if it be placed too low, the heat is expended almost 
 wholly on the hearth, and the fire-place seems buried within the fender; if it 
 be placed too high, a person's face is scorched, while too small a portion of 
 heat is given to the floor to render a room comfortable ; but a high mantel has 
 the advantage of producing a more effectual ventilation. Mr. Tredgold con- 
 sidered that the top bar of stoves ought not to be less than 20 inches from the 
 floor, and never exceed 2 feet ; and when the lower part of the fire is not 
 buried in a mass of metal work, there will be an abundant supply of heat 
 thrown upon the floor from the greater height. The space between the top bar 
 and the mantel will require to be proportioned to the size of the room and the 
 height of the chimney, and in ordinary cases may be about 15 or 16 inches. 
 With respect to the proportion of grates to different sized rooms, Mr. Tredgold 
 has, from observation, deduced the following rule : Let the length of the front 
 of the grate be made one inch for each foot in length of the room, and the
 
 FIRE-PLACES. 537 
 
 depth of the front be half an inch for each foot in breadth of the room. If the 
 length of the room be such as requires the grate to be longer than 2$ feet, 
 two fire-places will be necessary ; and in that case the same proportions may 
 oe adopted, divided into two grates, unless the room be very wide, when a 
 greater length should be given, and less depth, so as to preserve an equivalent 
 area. For various information connected with this subject, see the articles 
 VENTILATION, COMBUSTION, AIR, FURNACES, &c. 
 
 Welles s Patent Peripurixt.This is a small portable cooking stove, and is 
 very ingeniously contrived. The patentee states in his prospectus of it, that 
 " it boils water, prepares coffee and chocolate in a very superior manner, boils 
 eggs, cooks a beef-steak or a slice of ham, all in less than ten minutes. For 
 dinner, it will prepare soup, steam vegetables, and cook fish, chops, or steaks, 
 at the same time ; and for these one farthing's worth of fuel is sufficient." 
 Fig. 1 is an external view, and Fig. 2 is a vertical section ; a is a small cone of 
 cast iron, having at the bottom a grating, on which is put the fuel (charcoal), 
 broken into small pieces ; below this is a small chamber b, perforated at its 
 sides for the admission of air, and containing a small pan to receive the ashes, 
 and also to light the charcoal by a piece of paper ; the vessel c contains water, 
 which entirely surrounds the cone ; the next vessel e above is intended to be 
 
 Fi v 
 
 used as a steamer ; it has in its centre a frustrum of a cone, the lower edges of 
 which descend below the bottom of the vessels, and fit upon the cone beneath, 
 so as to carry up the flue to the chamber above, which has open perforated 
 sides, whence the vapours produced by the combustion escape. On the top of 
 the cone there is a valve for enlarging or diminishing the aperture, having a 
 horizontal rod fixed to it, which passes to the outside of the vessel, as shown. 
 The vessel over this, /, is, we suppose, a stew-pan, or something of the kind ; 
 it is heated by the hot air and direct influence of the fire ; above this pan is 
 placed in a cavity of the cover a small pot for warming small quantities of 
 liquid. There are several appendages or vessels for peculiar purposes, such as 
 the boiling of eggs, &c. which fit one over another in a similar manner to 
 those described. The apparatus is proposed to be used on the breakfast or 
 dining-table, to be taken in a carriage, in a boat, or carried by pedestrians. 
 
 Tczer's Patent Calefacfor. This is another ingeniously contrived little 
 cooking stove, and is intended to meet many of the wants of a small family, 
 especially in the summer season, when the smallest quantity of artificial heat is 
 desirable. The diagram in the next page is explanatory of its construction 
 and arrangement when applied to roasting and steaming ; some of the parts 
 in the drawing are slightly varied from their real positions, for the purpose of 
 elucidation by a single figure, a is the steam boiler, which has a large ellip- 
 tical opening down the centre for depositing a variety of culinary vessels
 
 538 
 
 FIRE-PLACES. 
 
 therein ; 6 an aperture for charging the boiler with water ; c a stop-cock for 
 drawing off the water as may be required, but placed high in the boiler to 
 admit a draught of air to the grating e, on which the charcoal is burned ; the 
 grating is, strictly speaking, a strong iron plate, perforated all over for the free 
 
 admission of air through the holes ; / is termed the oven pan, which is a cast- 
 iron dish, suspended about half way down the elliptical opening ; g a sheet-iron 
 cover ; h a pipe conveying the steam from the boiler a to the steamers i andy, 
 which separate in the middle, and allow of one or both being used at a time ; 
 each of these steamers may be subdivided into distinct compartments ; k, a 
 sliding damper for enlarging or contracting the air passage d, so as to increase 
 or diminish the combustion of the fuel, as may best suit the peculiar culinary 
 process. When the apparatus is not required for roasting, but for boiling, or 
 making soup or broth, the oven pan is to be removed, and in its place the 
 required vessels (all of which are made to fit) are deposited. In some cases 
 the patentee adopts two half-kettles instead of one. A current of heated air 
 is constantly kept up, entering at the grating at bottom, and passing out at the 
 grating above, where the heat is reverberated against the top and sides of the 
 cover, prior to its escape through a small central aperture in the latter. 
 
 FIRE-SHIP. A small vessel filled with combustible matter, and employed 
 for the destruction of an enemy's shipping by being run into the midst of them, 
 and set on fire by the crew before they quit the vessel. 
 
 FIRE-STONE. A coarse kind of free-stone, obtained at Reigate and other 
 places, which is capable of bearing a considerable degree of heat, and is there- 
 fore used in the construction of furnaces, ovens, &c. Its colour is a pale grey, 
 tinged with green, which the fire changes to a light red. 
 
 FIRE-WORKS. As the leading object of this work is utility and not mere 
 amusement, we shall but very briefly notice the nature and composition of 
 artificial fire-works. Of these the most generally interesting, from the great 
 altitude of their flight, are rockets. They are made by ramming into strong 
 cylindrical paper cases (put into wooden moulds to support them) powdered 
 gunpowder, or the ingredients of which it is composed ; namely, saltpetre, sul- 
 phur, and charcoal, very dry. To represent a fiery rain falling from the rocket, 
 mix among your charge a composition of powdered glass, filings of iron, and 
 sawdust; this shower is called the peacock's tail, on account of the various 
 colours exhibited. Camphor mixed with the charge produces white or pale 
 fire ; resin, a reddish colour ; sulphur, a blue ; sal ammoniac, a green ; anti- 
 mony, a reddish yellow ; ivory shavings, a silvery white ; pitch, a deep or dark 
 coloured fire ; and steel filings, beautiful corruscations and sparks. Sticks are 
 fastened to the rockets for the convenience of discharging them, and causing 
 them to pass through the air like an arrow ; the resistance of the air to the 
 rush of fire at the end of the rocket causing it to ascend. Artificial fire-works 
 differ from each other very much in point of simplicity of construction. Some 
 require very little dexterity in the preparation, and are either employed a
 
 FLAX DRESSING. 5J9 
 
 appendages to works of greater importance, or, if used by themselves, are con- 
 fined to the sports of school-boys. Of this nature are squibs, crackers, ser- 
 pents, stars, sparks, maroons, saucissons, pin-wheels, leaders, Roman candles, 
 &c. Others are very complex in their structure, require considerable address 
 and ingenuity, and form the amusement of fashionable circles on occasions of 
 public rejoicing, or private festivity : such are wheels, suns, globes, pyramids, 
 &c., and rockets of various kinds. Those who wish for precise instructions in 
 the preparation of these resplendent trifles, we would recommend to consult 
 the article PYROTECHNY, in the Oxford Encyclopedia. 
 
 FLAGEOLET. A little flute, made of box or other hard wood, with an 
 ivory mouth-piece, and having six holes besides the one at bottom, and one 
 behind the neck. Great improvements were made in this pleasing instrument 
 by the late Mr. Bainbridge, who also invented the double flageolet, upon which 
 one person may play duets. 
 
 FLAIL. An instrument for threshing corn. It is composed of two staffs 
 united at one end of each by strong double leathers. 
 
 FLAME. The luminous phenomenon produced by the combustion of 
 gaseous substances, or under certain circumstances of a solid and a gaseous 
 body. 
 
 FLANNEL. A kind of loose woollen stuff, composed of a woof and warp, 
 woven in a loom with two treddles, in the manner of baize. 
 
 FLAX. A plant having a slender, round, hollow stalk, about two feet high ; 
 its bark is full of filaments, like hemp; the leaves are long, narrow, and 
 pointed ; it bears a blue flower, to which succeeds a roundish fruit, about the 
 size of a pea, containing ten little seeds, full of an oily substance, or meal. There 
 are twenty-five species, of which the most remarkable are the common annual 
 flax, and the perennial Siberian flax. 
 
 FLAX DRESSING. Before flax can be converted into cloth or other 
 articles, it undergoes certain preparatory processes, constituting what is called 
 " dressing;" the object of which is to separate the boon, or core, from the flax, 
 which is the cuticle, or bark of the plant, and to straighten out the fibres for 
 the spinner. These operations are sometimes performed by hand, but at the 
 present day more commonly by machinery, driven by steam or water power. 
 When the flax is dressed by hand, the bark is separated from the core by 
 means of an instrument called a "flax-brake," composed of three wooden teeth 
 or swords, fastened longitudinally on a horizontal bench, and of a lever, to the 
 under side of which are fixed similar, but rather smaller teeth, which fit in 
 between the interstices of the others. The flax being held hi the left hand 
 across the under swords of the brake, the upper teeth are then with the right 
 hand quickly and often forced down upon the flax, which is artfully shifted and 
 turned with the left hand, in order that it may be fully and completely broken 
 m its whole length. The fibres are then straightened by means of a kind of 
 comb called a " hackle," whence the operation is termed " hackling." The 
 hackle is composed of a number of long teeth or spikes, fixed firmly in a bench ; 
 and the workman striking the flax upc.?* the teeth, draws it quickly through 
 them. To persons unacquainted with this kind of work it may seem a very 
 simple kind of operation ; but, in fact, it requires as much practice to hackle 
 well as any other operation in the whole manufacture of linen. The workmen 
 use finer, or coarser, and wider-teethed hackles, according to the quality of the 
 flax ; generally putting the flax through two hackles, a coarser one at first, and 
 then a finer one in finishing it. But the hand methods of breaking and 
 scotching of flax are, however, too tedious in their operation to give satisfaction 
 to the manufacturers in the present advanced state of mechanical science, and 
 accordingly mills have been constructed by which these preparatory operations 
 are much facilitated. These mills differ greatly in their form, and the mode 
 of their operation. A very simple and efficient one is described in Gray's 
 Experienced Millwright, and is constructed as follows : Upon the main shaft, 
 or axis of a water-wheel, is fixed a large bevilled wheel, which turns three 
 horizontal fluted or toothed rollers, by means of a pinion on the axis of the 
 middle one, the upper and lower rollers being kept pressed against the lower
 
 5 to FLOATING CODIES. 
 
 one- by weighted levers, and being carried round by contact with it. The 
 driving-wheel likewise gives motion to an upright shaft, by means of a small 
 pinion fixed upon the foot of the shaft ; upon the upper part of this shaft are 
 fixed cross arms, to which are attached scotches, revolving within a cylindrical 
 casing. The rough flax is made up into small parcels, which being introduced 
 between the middle and upper rollers, pass round the middle one, and this, 
 either having rollers placed on its off side, or being enclosed by a curved board, 
 turns the flax out between the middle and under rollers, when the flax is again 
 put in between the middle and upper one, and passes round the same course until 
 it be sufficiently broken or softened, and prepared for the scotching machine. The 
 scotches, as before stated, are inclosed in a cylindrical casing ; in the periphery 
 of this casing are a number of apertures, and at these holes a handful of flax 
 being held, the revolving scotches clear off the refuse. 
 
 FLEAM. An instrument containing several lancets, jointed so as to shut 
 up into a handle in the manner of pocket clasp-knives. 
 
 FLINT. A mineral consisting of 98 silica, 0.50 lime, 0.25 alumina, 0.25 
 oxide of iron, 1 loss. The domestic use of this stone, for producing light by 
 collision against steel, is well known. It is also much used in gun-locks for firing 
 the powder. The manufacture of gun-flints employs numerous hands in this 
 country ; as independently of the large quantity required for home use, consi- 
 derable shipments of them are made to various parts of the world, where the 
 mineral is not supplied by nature. The manufacture of gun-flints was for a 
 long time kept secret ; and we are indebted to M. Dolimien for the first pub- 
 lished account of the method practised in France, which he has given in the 
 Memoire de V Institute National de Sciences. The masses of flint which are best 
 fitted for this purpose, are of a convex surface, approaching to globular. The 
 best flint nodules are generally from two to twenty pounds' weight ; the 
 colour should be uniform in the same nodule ; their transparency should be 
 sufficient to admit letters to be distinguished through a piece of the stone of a 
 quarter of a line thick, laid close upon the paper. Their fracture should be 
 perfectly smooth and equal throughout, and the fragments slightly conoidal. 
 The last of these properties is the most essential, since on it depends the facility 
 with which the nodule is divided into gun-flints. All flints that prove deficient 
 in any one of the above characters, either naturally or by a long exposure to 
 the air, are called intractible, and rejected by the workmen. There are several 
 hammers and a chisel employed in the operation of fashioning the flints, by 
 which means it is said that a clever workman is able to manufacture a thousand 
 flints in the space of three days. Gun-flints are also manufactured at Purfleet 
 in Kent, and in various other parts of England, in a very superior style. 
 
 FLOAT BOARDS. Those boards which are fixed to the rim or circum- 
 ference of undershot water-wheels, serving to receive the impulse of the stream, 
 by which the mill is put in motion. 
 
 FLOATING BODIES, are those bodies which swim on the surface of a fluid, 
 the stability, equilibrium and other circumstances of which form an interesting 
 subject of mechanical and hydrostatical investigation, particularly as applied to 
 the construction and management of ships and other vessels ; but as the sub- 
 ject is one involving the higher branches of calculation, and as it is difficult to 
 obtain practical results which shall accord with those obtained from theory, on 
 account of the difficulty of estimating the amount of the disturbing forces, our 
 remarks must be brief and general. 
 
 The equilibrium of floating bodies is of two kinds ; viz. stable or absolute, 
 and unstable or tottering. In the one case, if the equilibrium be deranged, 
 the body merely oscillates about its primitive position, to which it finally returns, 
 and this is called firm or stable equilibrium ; but in the other state of equili- 
 brium, if the system be ever so little deranged, all bodies deviate more and 
 more, and the system finally oversets and assumes a new position ; and this is 
 called unstable or tottering equilibrium. The stability of a floating body is 
 greater as its centre of gravity is lower than that of the displaced fluid ; it is 
 for this reason that the ballast is put in the lower part of vessels to prevent their 
 oversetting. The nature of the equilibrium as to stability, depends on the
 
 FLOORING CRAMP. 
 
 '541 
 
 position of a certain point, called the meta-centre, or centre of pressure. 
 When the meta-centre is lower than the centre of gravity, the equilibrium is 
 tottering ; when the meta-centre coincides with the centre of gravity, the body 
 will remain at rest in any position it is placed in ; when the meta-centre is 
 above the centre of gravity, the body will always have a tendency to recover 
 its original position, and the equilibrium will be stable. 
 
 FLOORING CRAMP. A machine invented by Mr. Andrew Smith, for 
 laying down floors, so as to make very tight and close joints with great facility. 
 The annexed engraving shows a perspective view of the machine as in opera- 
 tion, by which its construction and the mode of using it are both made 
 apparent, a is a lever of the second class, about 2 feet 6 inches long, with a 
 handle at the upper end, and forked at the lower so as to be attached to two of 
 the opposite sides of a block of cast iron b, by bolts at c. The block b is about 
 6 inches square, and 3 deep, with a large groove capable of being increased or 
 diminished in its depth for the reception of joists of different sizes. For this 
 purpose, it has on one side a shifting loose cleat or plate c, kept in its place by 
 stout pins ; and on the other end, on the other side of the joist, there is another 
 
 groove d, which contains two pieces of metal, with wedge-formed surfaces; 
 between these the long driving wedge / is forced by a slight blow with a ham- 
 mer, which compresses the joist between the metallic surfaces, which are jagged 
 or armed with short projecting teeth, that fix themselves into the wood, and 
 gripe it very fast ; g is a movable piece of cast iron, made to press against the 
 edge of the flooring board, with its broadest side ; the two other sides or parts 
 of this piece are stout square bars, at right angles with the other, which are 
 inserted a part of their breadth in shallow grooves, one on each side of the 
 3 2
 
 542 FLOORING MACHINE. 
 
 block b, and serve to guide the former in its action. It will be observed that the 
 two forks of the lever a pass through the side bars of g, which therefore gives it 
 motion. To use this machine, it is put upon the joist, and pushed up to the 
 board laid down ; a slight blow upon the wedge / fixes it firmly to its place ; 
 the handle of the lever is then pulled by the workman towards the boards, 
 causing the sliding piece g to press the edges of the boards together with a? 
 much force- as to render their junction imperceptible ; the stay h is jointed 
 loosely to the back of the lever a, and following the motion of the lever, the 
 jagged end of its lower extremity sticks into the joist, holds the lever in the 
 position it was drawn, and preserves the pressure against the board, while it is 
 nailed down by the workman. To remove the cramp, all that is necessary is 
 to strike the wedge on the opposite side, which loosens the whole, when it is 
 drawn back to take the next board, which is operated upon in a similar manner. 
 
 FLOORING MACHINE. A machine invented by Mr. Muir, of Glasgow, 
 the object of which is the preparation of complete flooring boards with extra- 
 ordinary dispatch, and in the most perfect manner ; the several operations of saw- 
 ing, planing, grooving and tongueing, being all carried on at the same instant, 
 by a series of saws, planes, and revolving chisels. 
 
 The figure in the next page represents a plan of the machine, slightly modified, 
 to render the construction more easily understood by the reader. The machinery 
 is adapted for the simple planing of boards, as well as the preparation of square 
 jointed or plain jointed flooring. We shall commence our description by an 
 account of those parts which constitute a simple planing machine, and then 
 proceed to describe the apparatus by which it is adapted to the preparation of 
 jointed flooring. The planing machine consists of a perfectly flat and straight 
 bench, d d d, which should be at least twice as long as any board intended to be 
 prepared upon it. This bench is made fast to a block of stone c c or other 
 solid matter, which, together with a suitable framing, serves to keep the whole 
 machinery as firm and steady as possible. Along one side of this bench is a 
 raised guide e e, which extends as far as the circular saws t 1, but only a part 
 of it is shown in the figure, in order to bring some of the other arrangements 
 more into view. About the middle of the bench a metallic plate a a is let in 
 flush with its surface, which forms a durable stock for the plane irons ; these 
 plane irons are of the usual form, but of greater breadth than the boards to be 
 planed. The projection of their cutting edge is effected and regulated by screws, 
 and the number of plane irons employed at a time is determined by the degree 
 of finish required for the surface of the boards; three plane irons are how ever 
 generally used, as shown at h h h, the dark spaces being the mouths of the 
 planes : from this it will be seen that it is the lower side of the board that is 
 planed, and the shavings are delivered under the machine. An endless pitched 
 chain, having catch hooks at convenient distances, takes hold of the boards as 
 they are put into the machine in succession, and drags them along the bench ; 
 the edge of one of the sides of each board passing under a rebate in the guide 
 or fence (as shown in the figure) prevents the board from bending upwards by 
 the action of the chain, while it is pressed down to the plane irons by springs 
 or weighted levers, as seen at b b, which are mounted upon antifriction r< Jers, 
 the axles of which are so inclined as to cause the boards to be uniformly 
 driven against the fence, and to pass in a straight line through the machine. 
 Motion is given by a band from a large revolving drum, placed above the 
 machine, (not shown in the figure,) which communicates with the drum u, upon 
 the shaft of which is a pinion, that drives the toothed wheel j ; the axis of 
 the latter carries the pitched rigger t, round which the endless chain is passed, 
 and stretched in a parallel direction with the bench, by passing over the pulley 
 z, at the opposite end of the machine ; at this place only a small piece of the 
 chain is brought into view, as the introduction of the whole of it would hide or 
 tend to confuse some of the other parts of the apparatus. The pulley z is 
 mounted upon a tightening frame, y, which moves upon a joint at the lower 
 end, the tension being increased or lessened by the wedges 1 1 , or by regulating 
 crews. The parts we have thus described constitute a separate machine for the 
 planing only of boards. For the preparation of plain or square-jointed flooring
 
 FLOORING MACHINE. 
 
 543 
 
 boards, the following additional apparatus is brought into operation. A part of 
 the fence e is slightly hollowed from the direct line of the bench, to admit of 
 projecting inequalities in the edges of the boards; these are removed by irons or 
 cutters fixed on a horizontal revolving plate /, the periphery of which enters 
 an aperture in the fence e; and it is on the edge of the board presented to thia 
 side of the machine that a tongue or feather is formed when required. Te 
 
 produce this effect two circular saws, g and h, are used, one of which, g, revolves 
 under the board, and cuts it upward ; the other, h, revolves above the board, and 
 cuts it downwards, to such a depth only on each side as to leave a tongue or 
 feather of the required thickness uncut. By the progressive motion of the 
 board it next passes under the operation of two circular saws i, one only of 
 which can be seen, as the other is directly underneath on the same spindle, and 
 separated only by a ring or washer, which is of the same thickness as the tongue. 
 'JTiese saws, acting horizontally, or at right angles to those at g and h, cut off the 
 superfluous wood, and leave the tongue projecting from the board completely
 
 514 FLUORIC ACID. 
 
 formed. The opposite edge of the board is cut parallel to the other by a chcular 
 saw k revolving vertically, which is called the " breadthing " saw ; a guide fixed to 
 the head of o, which supports the spindle of this saw (but which cannot be seen 
 in the figure), is so placed as to conduct the superfluous pieces, separated from 
 the boards by the saw k, underneath the circular saw /; the slips are thus 
 removed out of the way of the latter saw and preserved. The saw / revolves 
 horizontally, and is called the "grooving saw;" it is considerably thicker than 
 ordinary circular saws, and has long teeth to admit of their receiving a " set" 
 to cut out the whole of the required groove at one operation. The spindle 
 head which carries the grooving saw is adjusted and fixed by screws to a 
 bracket attached to the head o, the latter being placed in slides, which keep it 
 steady, and conduct it in a parallel direction when moved to or from the bench. 
 All the parts that operate on this edge of the board being thus connected, 
 advance or recede together. This movement is effected by means of a screw 
 fitted with collars to the fixed puppet 3, and working in a nut in the back part 
 of the head o; the screw is turned by the handle n, and an index on the head 
 o points out the relative position of the circular saw k with respect to the other 
 side of the machine, and consequently indicates the various breadths of the 
 finished boards by pointing to a divided scale of inches and parts fixed upon 
 the block c. All the saws are fixed on to the spindles in the ordinary way, by 
 screws, nuts, and washers ; but the spindles are considerably thicker than 
 usual, to admit of their being fitted with cutters or irons, which, by cutting 
 horizontally, rebate the superfluous thickness of the board to a sufficient extent, 
 from that part which is destined to form the under side of the floor in all floor- 
 ing boards. The heads, which carry the vertical saws g h, are placed on slides 
 fixed to the block c c c, their horizontal position being adjusted by regulating 
 screws, worked by the handles p and r, and their spindles elevated or depressed 
 by proper adjusting screws. Motion is communicated by endless bands from 
 a large drum wheel above the machine, such bands embracing all the vertical 
 saw pulleys, and also the rigger or pulley w of the intermediate shaft vw; and 
 this intermediate shaft, by means of half crossed or twisted bands 4 4, gives 
 motion to the horizontal saws i and /. The circular plate or plane /is also 
 impelled by another half twisted band 5, from a pulley 6, on the axis of the saw 
 g. The power which impels the whole machine is derived from a steam 
 engine or other prime mover applied to the shaft of the large drum wheel 
 before mentioned. Several of these machines have been for some time past 
 in constant use ; one of which, at Pimlico, we have often witnessed the suc- 
 cessful operation of. 
 
 FLOUR. The fine particles of grain, usually obtained by grinding in a mill. 
 See FARINA, CORN, and MILLS. 
 
 FLUID. A body whose parts yield to the slightest force when impressed, 
 and by yielding, are easily moved against each other. Fluids are divided into 
 elastic and non-elastic. Elastic fluids are those which may be compressed into 
 an exceeding small compass, but which, on removing the compressing force, 
 resume their former dimensions ; and these are distinguished as airs or gases. 
 Non-elastic fluids are those which occupy the same bulk under all pressures, 
 or if compressible, it is only in a very slight degree, as water, oil, &c., and these 
 are denominated liquids, except in the case of metals in fusion. The physical 
 nature, laws, and effects, of More-elastic fluids at rest, constitute the science of 
 Hydrostatics, and when in motion, of the science of Hydraulics, or Hydro- 
 dynamics ; those that relate to elastic fluids appertain to Pneumatics. 
 
 FLUOR SPAR. The native fluate of lime. 
 
 FLUORIC ACID. The name given to an undecomposed substance, which, 
 combined with lime, constitutes the fluor spar. Fluoric acid may be obtained 
 by putting a quantity of the spar in powder into a leaden retort, pouring over 
 it an equal quantity of sulphuric acid, and then applying a gentle heat; a gas 
 ensues, which may be received in the usual manner in jars, standing over mer- 
 cury. This gas is the fluoric acid, which may be obtained, dissolved in water, 
 by luting to the retort a receiver containing that fluid. The distillation is to 
 be conducted with a very moderate heat, to allow the gas to condense, and to
 
 FLUX. 545 
 
 prevent the fluor itself from subliming. The properties of this acid are, that, 
 as a gas, it is invisible and elastic like air ; but it will not maintain combustion, 
 nor can animals breathe it without death. In smell it is pungent, something 
 similar to muriatic acid. It is heavier than common air, and corrodes the skin. 
 When water is admitted in contact with this gas, it absorbs it rapidly ; and if 
 the gas be obtained by means of glass vessels, it deposits, at the same time, a 
 quantity of silica. Water absorbs a large portion of this gas ; and in that state 
 it is usually called fluoric acid by chemists. It is then heavier than water, has 
 an acid taste, reddens vegetable blues, and has the property of not congealing 
 till cooled down to 23. Thepure acid may be obtained again from the com- 
 pound by means of heat. Fluoric acid gas does not act upon any of the 
 metals ; but liquid fluoric acid is capable of oxyding iron, zinc, copper, and 
 arsenic. It does not act upon the precious metals, nor upon platina, mercury, 
 lead, tin, antimony, cobalt. It combines with alkalies, earths, and metallic 
 oxides, and, with them, forms salts denominated fluates, of which the true fluor, 
 Derbyshire spar, or fluate of lime, consists of 
 
 Lime 57 
 
 Fluoric acid 16 
 
 Water 27 
 
 100 
 
 The most remarkable property is that already alluded to, viz. the facility with 
 which it corrodes glass and siliceous bodies, especially when hot, and the care 
 with which it holds silica in solution, even when in a state of gas. This affinity 
 for silica is so great that the thickest glass vessels can withstand its action only 
 a short time. With respect to the nature of the substance usually termed 
 fluoric acid, it has not yet been determined experimentally whether it be really 
 a compound of some unknown base with either oxygen or hydrogen, or whether 
 it be a simple substance like chlorine. Dr. Thompson inclines to the opinion 
 that it is a compound of an unknown radical with hydrogen, and not with 
 oxygen ; but Sir H. Davy made several attempts to separate its hydrogen, but 
 without success, although he applied the power of the great voltaic batteries of 
 the Royal Institution to the liquid fluoric acid ; neither could he decompose it by 
 passing it with chlorine through a platina tube heated red hot, nor by distilling 
 it from salts containing abundance of chlorine or of oxygen. Dr. Ure there- 
 fore observes, that by the strict rules of chemical logic, fluoric acid ought to be 
 regarded as a simple body, for we have no evidence of its having ever been 
 decomposed ; and nothing but its analogy with the other acid bodies has given 
 rise to the assumption of its being a compound. 
 
 FLUORINE. The imaginary radical of the above acid. 
 
 FLUTE. One of the simplest musical instruments of the wind kind. It is 
 played with a mouth-piece at the end, and the notes are changed by opening 
 or stopping the holes ranged along the side. The German flute differs from 
 the former, the end not being put into the mouth, but closed by a plug, and 
 the lower lip being applied to a hole about three inches from that end. As 
 usually constructed, this instrument has six open holes, and a seventh hole 
 closed by a key, as in hautboys, bassoons, &c. ; but numerous improvements- 
 have been made in them, and they are now frequently made with eight or even 
 ten keys, by which the fingering of many musical passages is much facilitated. 
 
 FLUX. A general term used to denote any substance or mixture added to 
 assist the fusion of minerals. In the large way, limestone and fusible spar are 
 used as fluxes. The fluxes made use of in philosophical experiments consist 
 usually of alkalies, which render earthy mixtures fusible by converting them 
 dass, or else glass itself into powder. Alkaline fluxes are either the i 
 
 into glass, or else glass itself into powder. Alkaline fluxes are either the crude 
 flux, the white flux, or the black flux. Crude flux is a mixture of nitre and 
 tartar, which is put into the crucible along with the metal intended to be fused. 
 White flux is formed by projecting equal parts of a mixture of nitre and tartar, 
 by moderate proportions at a time, into a red hot crucible. In the detonation 
 which ensues, the nitric acid is decomposed and flies off with the tartaric acid.
 
 546 
 
 and the remainder consists of the potash in a state of considerable purity. 
 Black flux consists of two parts of tartar to one of nitre, on which account the 
 combustion is incomplete, and a considerable portion of the tartaric acid is 
 decomposed by mere heat, and leaves behind a quantity of charcoal, on which 
 the colour depends. It is used in the reduction of metallic ores, which it 
 effects by combining with the oxygen of the oxide. Mowean's reducing flux 
 is made of eight parts of pulverized glass, one of calcined borax, and half 
 a part of charcoal. Care must be taken to use a glass which contains no lead. 
 
 FLY, in Mechanics, a wheel with a heavy rim, placed on the shaft of any 
 machinery put in motion by any irregular or intermitting force, for the purpose 
 of rendering the motion equable and regular by means of its momentum. This 
 effect results from a law of nature, that all bodies have a tendency to continue 
 in their state either of motion or of rest, until acted upon by some extraneous 
 force. Thus the rim of a fly-wheel, after a few revolutions, acquires a 
 momentum sufficient to cause it to revolve with a velocity depending upon the 
 resistance of the machinery ; and the augmentations and diminutions of the 
 impelling power succeeding each other rapidly, neither cause acts sufficiently 
 long to either augment or diminish the velocity acquired in any considerable 
 degree, so that it remains equable, or nearly so. Thus in the case of a man 
 working at a winch, the power which he exerts in pulling upwards from the 
 lower part considerably exceeds his power in thrusting forwards in the upper 
 quarter ; but before the extra force thus exerted has acted sufficiently long to 
 change the velocity of the wheel, the winch arrives at the point where his force 
 is the least, by which time the excessive force previously exerted having taken 
 effect, the equable motion of the fly is maintained ; and the resistance of the work 
 being equalized, a man is enabled to raise throughout a whole day a weight of 
 forty pounds with more ease than he could raise thirty pounds without a fly. In 
 all cases where a rotatory motion is to be obtained from a reciprocating one, by 
 means of a crank, a fly-wheel is necessary to continue the motion at those two 
 points of the revolution in which the crank lies in the direction in which the 
 moving force acts ; for in this case the crank affords no leverage to the power 
 either on one or other side of the fulcrum, and consequently no motion could 
 be produced in either direction ; but the momentum acquired by the fly urges 
 the crank forward in the direction in which it was previously moving, and con- 
 tinues the rotation until the crank is brought into such a position as to offer 
 sufficient leverage to the power to maintain the impetus of the fly. 
 
 FOCUS, in Optics, a point wherein several rays concur or are collected, 
 after having undergone either reflection or refraction. The point is thus deno- 
 minated because the rays being here brought together and united, their joint 
 effect is sufficient to burn bodies exposed to their action ; and hence this point 
 is called the focus, or burning point. 
 
 FOIL, among jewellers, a thin leaf of metal placed under a precious stone, 
 in order to increase its brilliancy, or give it an agreeable and different colour. 
 These foils are made of either copper, gold, or gold and silver together ; the 
 copper foils are commonly known by the name of Nuremberg, or German foils. 
 They are prepared as follows : Procure the thinnest copper plates you can get; 
 beat these plates gently upon a well polished anvil with a polished hammer, as 
 thin as possible ; and placing them between two iron plates as thin as writing 
 paper, heat them in the fire ; then boil the foils in a pipkin, with equal quan- 
 tities of tartar and salt, constantly stirring them, till by boiling they become 
 white ; after which, taking them out and drying them, give them another 
 hammering, till they are made fit for your purpose; however, care must be 
 taken not to give the foils too much heat, for fear of melting, nor must they be 
 too long boiled, for fear of attracting too much salt. The manner of polishing 
 is as follows : Take a plate of the best copper, one foot long and about five or 
 six inches wide, polished to the greatest perfection ; bend this to a long convex, 
 fasten it upon a half roll, and fix it to a bench or table ; then take some chalk, 
 washed as clean as possible and filtered through a fine linen cloth, till it is as 
 fine as you can make it ; and having laid some on the roll, and wetted the 
 copper all over, lay your foils upon it, and with a polishing stone and the chalk.
 
 FORCE. 547 
 
 polish your foils till they are as bright as a looking glass : after which they 
 must be dried, and laid up secure from the dust. 
 
 FOOT. A measure of length, consisting of twelve inches, each inch being 
 three barley corns, or twelve lines. The square foot is a measure for surfaces, 
 being a square of which each side is 12 inches; consequently a square foot 
 contains 144 inches. The cubic foot is a measure for capacity, or solid 
 contents; it is a foot in length, in breadth, and in depth or thickness, and 
 contains 1728 cubic inches. 
 
 FORCE is the name applied in Mechanics to whatever produces motion or 
 pressure. Thus we have the forces of gravity and of elasticity, muscular 
 foice, and that of electricity and magnetism. These will be considered 
 under the head PRIME MOVERS at present we shall confine ourselves to the 
 general laws to which the application of force is subject When a force is 
 applied suddenly to a body, and immediately ceases to act upon it, it is called 
 an impulsive force ; but when its action is continued so as to produce a con- 
 stantly increasing motion or pressure, it is termed a constant or accelerating 
 force. Examples of the first kind are seen in the blow with a hammer, and in 
 the discharge of a gun ; and of the second, in the action of gravity and in 
 the motion of the wind. Impulsive forces produce uniform velocities. Thus, 
 if a billiard ball be struck, and move along a smooth table, so that the resistance 
 arising from friction may be small, it will be observed to pass over equal spaces 
 in equal successive portions of time ; or, in other words, if the ball pass over 
 1 foot in a second, it will pass over 2 feet in two seconds, 3 feet in three 
 seconds, and so on. Constant forces produce accelerated velocities. Thus, if a 
 certain force, as that of gravity, act upon a body so as to impel it through 16 
 feet in one second of time, in the next second it would pass through three times 
 sixteen, or 48 feet ; in the third second through five times sixteen, or 80 feet, 
 and so on, the constant addition being 32 feet, which is the velocity acquired 
 at the end of the first second of time. Now if a force produce an uniform 
 increase of velocity, as in this case, it is called an uniformly accelerating force ; 
 or if it produce a regular diminution of velocity, it is a uniformly retarding 
 force. If, however, the increase or decrease of velocity be not constantly the 
 same, it is caused by a variable accelerating or retarding force. In the appli- 
 cation of forces, the chief considerations are intensity and direction. If a 
 single force act upon a body, motion necessarily results in the direction in which 
 the force acts, and with a velocity proportional to its intensity. If two or more 
 forces are employed, motion may or may not result, according to the intensity 
 and direction of the force. If two equal forces applied to the same point act 
 in opposite directions, they mutually annihilate each other ; if, however, they 
 act in the same direction, they produce the same effect as a single one equal in 
 intensity to the sum of the two. Or, if they act in different directions, forming 
 an angle with each other, a third force may be assigned, which shall be equi- 
 valent to the other two. In this case the two forces are called the components, 
 and the third, the resultant. The process for finding the resultant of two or 
 more forces is called the composition of forces, and the finding of two or more 
 forces, which shall be equivalent to a single given force, is termed the resolution 
 of forces. The propositions connected with this subject form a highly inte- 
 resting and important branch of the science of mechanics. In the annexed cut 
 let the line A B represent the intensity and direction of 
 one force, and A C the intensity and direction of the 
 other force. Complete the parallelogram A B D C, and 
 the diagonal A D will represent the intensity and direc- 
 tion of the resultant ; i. e. a force equal to A D, and, in 
 the direction D A, would counterbalance the other two, 
 and keep the point A at rest. The same may perhaps 
 be more clearly apprehended by considering the point 
 A in motion ; let a force act upon A so as, if alone, to drive it to the point E in 
 one second, and at the same instant let a force act in the direction A C, that 
 would, if unopposed, carry it to C in the same time ; then if the two forces act 
 together, the resulting motion will be in the line A D, and the body will react.
 
 548 
 
 FORCE. 
 
 the point D in the same time that it would have taken to reach B or C by the actior 
 of either of the forces singly. In the composition of forces it will be seen that we 
 are limited to one resultant; but in the resolution of force we may have an infinite 
 number of components, any pair of which will be equivalent to the given force. 
 Thus let a force, represented by the line A B, be 
 resolved into two others by drawing two parallelo- 
 grams around it, it will be manifest that the com- 
 ponent forces may be either A C and A E, or A D c 
 and A F ; and as an infinite number of directions 
 may be given to the lines AC, A E, the number of 
 components is also unlimited. In general, however, 
 the required direction and intensity of one of the 
 forces is given, and this determines the other. 
 Suppose a man were required to raise a weight over 
 a pulley, and the ropes, instead of being parallel, are 
 in the directions A B A D, it will be evident that a 
 part of his strength is employed uselessly in pulling 
 horizontally. Let B D represent the force necessary 
 to sustain the weight B; resolve this into the two 
 B C, B D, the one perpendicular, and the other parallel 
 to the horizon, it will then be seen that the force 
 which is employed in raising the body, is equal to 
 B C, and as this is less than B D, the weight must fall, 
 or the power be increased in the ratio of B C to B D. 
 If three forces are employed, they may also be deter- 
 mined by drawing three lines parallel to their directions, so as to form a 
 triangle. The three cords A D, B D, C D, will Le kept at rest, when the three 
 weights at A B C are proportional to the 
 three lines D E, D F, and E F, either of 
 which may be considered as the resultant of 
 the other two. If a number of forces act 
 upon a body, and a single resultant be re- 
 quired, it may be found by finding the 
 resultant of one pair, and connecting this 
 with another ; then find the resultant of this 
 pair and connect it with the next, and so on, 
 till the last is obtained, which is the common 
 resultant of the whole. Numerous examples 
 are daily presented of the composition of 
 forces. When a boat is rowed across a -river 
 in which there is a rapid current, it will not 
 pass directly across, nor down the stream, 
 but will partake of both directions, proceeding in a direction intermediately 
 between the acting forces. A body falling from the topmast of a vessel in full 
 sail will not fall directly downward, for having a direction forward given by the 
 motion of the vessel, and a downward direction by gravity, it will take a 
 middle course, describing what is termed a parabolic curve. The tide and 
 wind acting together upon a vessel, the two oars of a boat in rowing, the 
 motion of a stone, an arrow, or a cannon ball through the air, are examples of 
 the same kind. Another instance of a resultant motion may be adduced, in 
 the reflection of elastic bodies from a smooth 
 surface. Let A B be a smooth flat surface, 
 and let an elastic ball strike it in the direc- 
 tion C D, then will it be reflected in the 
 direction D E, making the angle of reflection 
 E D F equal to the angle of incidence CDF. 
 If C D represent the force of the ball in the 
 direction C D, it may be resolved into two, 
 vhich are proportional to C F and C B. The 
 force C F being parallel to the plane A B, is not influenced by it, but C I) being
 
 FORGE. 549 
 
 perpendicular, is destroyed, and a motion impressed in the direction D F. The 
 body is still then under the influence of two forces, its retained velocity in the 
 direction D A, and, the impressed force produced by the reaction of the board 
 in the direction D F. Between these two the ball necessarily moves in the line 
 D E. An application of this problem will account for the motion of billiard 
 balls, and of ships sailing obliquely to the wind ; also of windmill sails, and 
 other daily occurrences in nature and art. 
 
 FORCEPS. A general term, (but principally used in surgery,) for a variety 
 of instruments of the nature of tongs or plyers. 
 
 FORGE properly signifies a little furnace, furnished with a pair of bellows to 
 render the combustion more vivid ; and employed by smiths and other artisans 
 in iron, steel, &c. to heat their metals, in order to soften and render them more 
 manageable upon the anvil. In laboratories there is generally a small furnace, 
 consisting of a cylindrical piece, open at top, which has at its lower end a hole 
 for receiving the nozle of a pair of double bellows. This kind of forge is very 
 convenient for fusions, as the operation is quickly performed, and with few 
 coals. The natives of Ceylon work with considerable skill and taste in gold 
 and silver ; and, with means that appear very inadequate, execute articles of 
 jewellery that would certainly be admired, but not very easily imitated in this 
 country. The best artists require only the following apparatus and tools, a 
 low earthen pot, full of chaff or saw dust, in which he makes a little charcoal 
 fire ; a small bamboo blow-pipe, with which he excites the fire ; a short earthen 
 tube or nozle, the extremity of which is placed at the bottom of the fire, and 
 through which the artist directs the blast of the blow-pipe ; two or three small 
 crucibles made of the fine clay of ant-hills, a pair of tongs, an anvil, two or three 
 small hammers, and a file ; and to conclude the list, a few small bars of iron or 
 brass, about two inches long, and differently pointed for different kinds of work. 
 
 It is astonishing what an intense little fire, more than sufficiently strong to melt 
 gold and silver, can be kindled in a few minutes. Such a simple forge deserves 
 to be better known ; it is, perhaps, even deserving the attention of the scien- 
 tific experimenter, and may be useful to him when he wishes to excite a small 
 fire larger than can be produced by the common blow-pipe, and he has not a 
 forge at command. The success of this little forge depends a good deal in the 
 bed of the fire being composed of a combustible material, and a very bad conductor 
 of heat. The blacksmiths of Ceylon are not behind their brethren, the jewellers, 
 in the simplicity of their apparatus, however inferior they may be in skill. 
 The cut in the next page represents two smiths at a forge. The bellows consist 
 of a couple of bags made of bullocks' hides, each furnished with a bamboo nozle, 
 and a long slit as a mouth, with wooden lips, that are opened and drawn up and 
 shut and pressed down alternately by the hands of the person sitting between 
 the pair, who keeps up a constant blast by the alternate action of the two. The 
 nozle of the bellows is introduced through a small hole in the foot of the 
 fcreen, which constitutes the back of the forge, and serves to allow the ascent
 
 650 FORGE 
 
 of the smoke. It is composed of a mat or hurdle, supported between two 
 sticks and plastered over with clay to protect it from the heat Mr. J. Sperne, 
 
 of Belper, near Derby, has invented a forge, principally designed for the manu- 
 facture of nails, which is highly deserving of notice. It is peculiarly adapted 
 for the burning of charcoal ; and the inventor proposes to adopt this fuel in 
 conjunction with coke, or coal purified from sulphur, generally in the proportion 
 of three parts of the latter to one of the former ; these proportions to be, how- 
 ever, varied according to the nature of the coal, and the quality of the metal 
 to be wrought. This forge is constructed as follows : the brickwork is first 
 carried up from the bottom of a cylindrical figure, to the height of twenty four 
 inches, leaving proper apertures for the delivery of the ashes, the reception of 
 the water troughs, and for the insertion of the nozle of the bellows; the 
 circular aperture in the centre is then covered with a fine cast-iron grating, 
 which forms the bottom of the furnace. The courses of brick-work are next 
 carried up a foot higher, and the whole is then surmounted by a cast-iron plate, 
 with a rim or border six inches high round the external periphery, forming a 
 convenient dish for holding the fuel to replenish the fire. In the centre of the 
 cast-iron top plate is an aperture corresponding with the fire-place, and to this 
 aperture is fitted a cast-iron ring, supporting, on three cast-iron pillars, another 
 ring which carries the brick-work of the chimney, which is cylindrical. The 
 bellows are suspended from a frame, and are worked by a lever which encircles 
 the chimney, affording every workman employed the convenience of acting 
 upon it with facility ; and as this construction of the forge will admit of six 
 workpeople being employed round it in making of nails, the fire is always 
 kept up bright and vivid by the continual blasts from the bellows. With 
 respect to the advantages of the forge the inventor observes "By the peculiar 
 construction of the fire-place, wood charcoal alone may be used, which cannot 
 be done in other forges ; but by a mixture of wood charcoal with coke for 
 fuel, the metals to be wrought will acquire a surprising degree of malleability, 
 and weld with great ease ; their tenacity and clearness will also be improved, 
 and they will have, when cold, a better face or skin than can be put upon them 
 by any other method. In addition to the great advantage of apportioning the
 
 FOUNDING. 551 
 
 fuel to the work required, the circular form will admit of a greater number of 
 workmen being employed at the same time at this forge than at any other, 
 thereby causing a saving of brickwork in the erection of forges, of bellows, 
 and shoproom for working them, and a permanent saving in the fuel for their 
 consumption. See IRON. 
 
 FORK. A well-known instrument, consisting of a handle, and two or more 
 prongs. Though considered now to be indispensable, it did not come into use 
 till the reign of James I. 
 
 FORM. In Printing, an assemblage of letters, words, and lines, arranged 
 in order, and disposed into pages by the compositor ; from which, by means of 
 ink and the press, sheets are printed. Every form is enclosed in an iron chase, 
 wherein it is firmly locked by a number of wedge-shaped pieces of wood of 
 various sizes. There are two forms required in every sheet, one for each side : 
 and each form consists of more or fewer pages, according to the size of the 
 book. See PRINTING. 
 
 FORMIATES. Compounds of the formic acid with earths, alkalies, and 
 metallic oxides. 
 
 FORMULA. A general rule or expression for resolving certain particular 
 cases of some problem. 
 
 FOTHERING. A method sometimes resorted to for stopping a leak in a 
 vessel at sea. It consists in stitching loosely a quantity of oakum upon a sail, 
 which is drawn under the vessel's bottom ; and by the flow of the water through 
 the leak, the oakum is drawn into the aperture. 
 
 FOUNDING is the art of casting or forming of melted metal an infinite 
 variety of articles to any given pattern or design ; and the place or building 
 where the art is carried on is called a foundry. Foundries are, however, dis- 
 tinguished either by the metals they work or the articles they fabricate, such 
 as brass foundries and iron foundries, bell and type foundries. As the 
 methods of casting in one kind of metallic substance are very similar to those 
 employed in others, we shall therefore describe at some length the art of 
 founding as it is practised by the brass founders, and more briefly whatever is 
 peculiar in the processes adopted in the other branches of the art 
 
 The operations of the brass founder are not limited to that peculiar yellow 
 compound of copper and zinc, strictly termed brass, but to every variety of the 
 alloys of copper, with tin and zinc in every proportion, according to the pur- 
 poses for which the article is required, or according to the motive of economy 
 or profit of the manufacturer. Founders in brass require an exact model in 
 wood, or otherwise, of the article to be founded ; and this is most frequently 
 made in two parts, exactly joined together, and fitted by small pins, and the 
 casting, in such a case, is performed by two operations, that is. one half at one 
 time, and one half at another, and in the manner following ; viz. the founder 
 provides himself with a yellowish sharp sand, which is required to be well washed, 
 to free it from all earthy and other particles. This sand is prepared for use 
 by a process called tewing, which consists in working up the sand in a moist 
 state, over a board about one foot square, which is placed over a box to receive 
 what may fall over in the tewing. A roller about two feet long and two inches 
 in diameter is employed in rolling the sand about until it is brought into that 
 state which is deemed proper for its business; a long-bladed knife is also 
 required to cut it in pieces. With the roller and the knife, the tewing is 
 finished for use by being alternately rolled and cut. When the sand is so far 
 prepared, the moulder provides himself with a table or board, which, in size, 
 must be regulated by the castings about to be performed on it. The edges of the 
 table or board are surrounded by a ledge, in order to support the tewed stuff"; 
 the table, so previously prepared, is filled up with the sand as high as the top of 
 the ledge, which is in a moderately moistened state, and which must be pressed 
 closely down upon the table in every part. When the operation has so far 
 advanced, the models must be all examined, to see that they are in a state to 
 come nicely out of the mould, and if not found so, they must be cleaned or 
 altered till the founder is satisfied with them. All models require the greatest 
 accuracy in their making, or it will be vain to suppose any thing good can be
 
 552 FOUNDING. 
 
 performed by the founder. When the models are in a proper state to ba 
 founded, one half, generally longitudinally, is taken first, and this is applied on the 
 mould, and pressed down into the tewed stuff or sand, so as completely to leave 
 its form indented on it, which must be very carefully looked to, and examined 
 minutely, to see that there are no small holes, as every part in the indented 
 sand must be a perfect cameo of the models submitted and pressed into it. If 
 it should not be found perfect, new sand must be added, and the model re- 
 indented and pressed into it, till it leaves its impression in a state proper to receive 
 the metal. In the same manner, other models intended to be founded on the 
 same table must be prepared and indented into the sand. When the table is 
 completely ready for the metal it is carried away to the melter, who himself 
 examines its state, and also the cameos, and who lays along the middle of the 
 mould the half of a small wire of brass, which he presses into the sand, so as 
 to form a small channel for the melted brass to flow in, and which he terms the 
 master jet or canal. It is so disposed as to meet the ledge on one side, and far 
 enough to reach the last pattern on the other ; from this is made several lesser 
 jets or branches, extending themselves to each pattern on the table, by 
 which means the fluid metal is conveyed to all the different indented impres- 
 sions required to be cast on the table. When the work is so far forwarded it 
 is deemed ready for the foundry ; but previously to this, the whole is sprinkled 
 over with mill dust, and when it is so sprinkled the table is placed in an oven 
 of moderate temperature till it gets dry, or in a state which is deemed proper 
 to receive the melted brass. The first table being thus far completed, it is either 
 turned upside down, and the moulds or patterns taken out, or the moulder 
 begins to prepare another table exactly similar to the one he has just com- 
 pleted, in which he indents and presses the other half of the mould ; or he turns 
 the table already finished, containing the first half of the patterns, upside 
 down ; previously, however, to doing this, it will be necessary for him to 
 loosen the pattern, which is fixed in the sand, a little all round, with any small 
 instrument that will open away the sand from its edges, in order to its coming 
 out of the table more easily. This economy in founding, of making one 
 half of each pattern to be cast answer the purpose of the whole pattern, is a 
 very common practice in brass founding, and enables the manufacturer to sell 
 his goods at a much cheaper rate than he would otherwise be enabled to do if 
 he was obliged to have a full pattern of all goods to be founded. When he has 
 loosened the sand from about the pattern, and taken it out of the first table, the 
 work is proceeded in of preparing the counterpart or other half of the mould 
 with the same pattern, or otherwise, and in a frame exactly corresponding with 
 the former, excepting only that it is prepared with small pins to enter holes 
 which are made in the first half of the model, to secure them together. 
 When this counterpart table has been finished, and all the patterns indented in 
 the sand, it is carried to the melter, who, after enlarging the principal jet of the 
 counterpart, and making the cross jets to the various patterns, and sprinkling 
 them as before with mill dust, it is set in the oven to be sufficiently dried to 
 receive the liquid metal. When both parts are sufficiently dry, they are joined 
 together by the pins, and to prevent these from being forced open by the pressure 
 of the liquid metal, the tables are further secured by screwed bolts or wedges. 
 The furnace for melting is somewhat similar to a smith's forge, with a chimney 
 over it, and a pair of large bellows ; the hearth is of masonry or brickwork, 
 secured by an outer rim of iron. The fire-place, which is in the centre, is a 
 cavity of 12 to 18 inches square, and reaching down to the floor of the foun- 
 dry. The lowest part of this cavity constitutes the ash-pit and air-chamber, and 
 is divided from the upper portion by an iron grating ; on this the fuel is deposited, 
 in the centre of which is placed a covered crucible, containing the metal 
 under fusion, which is accelerated by keeping the fuel in which it is completely 
 imbedded in vivid combustion by the continued action of the bellows. When the 
 fusion is perfect the crucible is withdrawn from the fire by the caster, with a pair 
 of long tongs adapted to gripe it firmly, and with which he pours into the master 
 jet of each mould until they are filled. As soon as this is done water is sprinkled 
 over the tables to cool and fix the metal ; after which the tables are unfastened.
 
 FOUNDING. 553 
 
 and the new castings taken out, to be finished by filing, scouring, burnishing, 
 turning, &c. as the work may require. The sand is now taken out of the frames, 
 to be worked up again for the next casting : by repeated use the sand becomes 
 black, by the charcoal collected from the foundry, which does not, however, 
 unfit it for further employment. To reduce the expense and weight of casting 
 large masses in solid metal, recourse is often had to forming them hollow, 
 which process is distinguished by the term core casting, as it is necessary to 
 have a* core or heart of nearly the shape of the external form of the pattern. 
 This core is usually made of clay, mixed and kneaded with crucible dust, and 
 is suspended by wires in its place, with a space around it to receive the 
 metal ; in small articles, however, it is usual to fill up the space by coating the 
 core to that extent with wax, which melts as the metal flows to supply its 
 place. When the pattern is of a complicated form, and a difficulty arises in 
 getting out the core, it is usually separated into several pieces, which are 
 joined together after being cost. In many of the Birmingham manufactures 
 the cores occupy so much of the pattern, that the metal left is not thicker than 
 a shilling. The business of a brass founder, contrary to that of an iron- 
 founder, extends to the finishing of the articles he casts ; and not only to this, 
 but to the manufacture of brass goods that are not cast or founded at all, being 
 made entirely from wrought or rolled metal. A large proportion of the Bir- 
 mingham manufacture of cabinet brass work is formed out of sheet metal, by 
 pressure between dies after the manner of coining : such goods are in con- 
 sequence cheaply made, and frequently are impressed with very tasteful and 
 elaborate designs. The castings, when taken out of the sand, have first to be 
 cleaned up and completed, as they are seldom free from defects ; the cores are 
 filed off, and the small cavities filled up with metal or solder ; they are after- 
 wards finished, according to the nature of the article, by filing, turning, bur- 
 nishing, and lackering. The superior kinds of brass work are gilded, 
 which preserves them better than lacker, and constitutes the article called 
 or molu. 
 
 In the founding of statues, busts, &c. three things in particular require atten- 
 tion ; namely, the mould, the wax, and shell or coat, the inner mould or core, 
 so called from being in the middle or heart of the statue. In preparing the 
 core, the moulder is required to give it the attitude and contour of the figure 
 intended to be founded. The use of the core is to support the wax and shell, 
 to lessen the weight, and save the metal. The core is made and raised on an 
 iron grate, sufficiently strong to sustain it ; and it is farther strengthened by 
 bars or ribs of iron. The core is made of strong potter's clay, tempered with 
 water, and mixed up with horse-dung and hair, all kneaded and incorporated 
 together ; with this it is modelled and fashioned previously to the sculptor's 
 laying over it the wax ; some moulders use plaster of Paris and sifted brick- 
 dust, mixed together with water, for their cores. The iron bars which support 
 the core are so adjusted that they can be taken from out of the figure after it 
 is founded, and the holes are restored by solder, &c. ; but it is necessary in full 
 sized figures to leave some of the iron bars affixed to the figure to steady its 
 projecting parts. After the core is finished, and got tolerably firm and dry, the 
 operation of laying on the waxen covering to represent the figure is performed, 
 which must be all done, wrought, and fashioned, by the sculptor himself, and by 
 him adjusted to the core. Some sculptors work the wax separately, and afterwards 
 dispose and arrange it on the ribs of iron, filling up the void spaces in the middle 
 
 <V i ;.i_ i: :j _i__i. ji_ _!_ j <. i_ .. i -i i ,1 j_ _. 
 
 tig 
 
 substance, in order to the metal being so in the work, of which the wax is its 
 previous representative. When the waxen model is finished to the core, or 
 adapted and filled afterwards, small tubes of wax are fixed perpendicularly to 
 it from top to bottom, to serve not only as jets to convey the melted metal to 
 all parts of the work, but as vent holes to allow a passage to the air generated 
 by the heated brass in flowing into the mould, and which, if not admitted 
 readily to escape, would occasion so much disorder in it as would much injure
 
 554 FOUNDING. 
 
 the beauty of the work. Sc?ilptors adjust the weight of the metal required in 
 this kind of founding by the wax taken up in the model. One pound of wax 
 so employed will require ten pounds of metal to occupy its space in the cast- 
 ing. The work having advanced in progress so far, will now require covering 
 with a shell. This consists of a kind of coat laid over the wax, which, being of 
 a soft nature, easily takes and preserves the impression, which it afterwards 
 communicates to the metal upon its occupying the place of the wax, which is 
 between the shell and core. The shell is composed of clay and white crucible 
 dust, well ground, screened, and mixed up with water to the consistence of paint, 
 like which it is used. The moulder applies it, by laying it over the wax with 
 a camel's hair or other soft pencil, which will require eight or nine times going 
 over, allowing it time to dry between each successive coat. After this coating 
 is firm upon the wax, and whifrbt is used only to protect it from those 
 which are to follow, the second part or coating is made up of common earth, 
 mixed with horse dung ; this is spread all over the model, and in such thick- 
 ness as to withstand, in some measure, the weight of the metal. To this 
 coating or impression is added a third, composed almost wholly of dung, with 
 a proportion of earth sufficient only to render it a little more tough and firm 
 when used. When this is tolerably dry, the shell is finished by laying on 
 several more coats or impressions of the same composition, made strong and 
 stiff by successive workings with the hand. When this is finished and is 
 deemed adequate to support the heated metal, it is further secured and 
 strengthened by several bands or hoops of iron, bound round it at about six 
 inches from each other, and fastened at bottom to the grate on which the statue 
 stands. Above the head of the statue is made an iron circle, for the purpose 
 also of confining the shell and statue ; to this circle the hoops are fastened at top. 
 It may be considered, when the moulding has arrived at this state, to be in a 
 condition to receive the melted metal ; but it is not so exactly, as will soon 
 appear. The mould, as has been before observed, is made upon an iron grate ; 
 under this grate is a furnace and flue, in which, at this period of the work, a 
 moderate fire is to be made, and the aperture of communication therewith 
 stopped up, so as to keep in the heat. As the heat increases and begins to 
 operate upon the mould, preparation must be made to allow of the wax running 
 freely from out of the shell ; for this purpose pipes are contrived at the base of 
 the mould so that it may run gently off and through these pipes. As soon as it 
 is all run off the pipes are nicely stopped up with earth to prevent the air 
 entering them, &c. When this is done the shell is surrounded by any matter 
 that has non-conducting properties for instance, pieces of brick put round 
 and piled up of good thickness, secured by earth, will answer the end ; and the 
 whole should be finally coated outside with loam as a further protection to 
 keep in the heat. After the shell is adequately surrounded with materials to 
 keep off the effect of the air, the fire in the furnace is augmented till such 
 time as both the matter surrounding the shell and it also becomes red hot, and 
 which, iu ordinary circumstances, will take place in twenty- four hours' time; 
 the fire is then extinguished, and the whole allowed to cool ; after which, the 
 matter which has been packed round the shell is taken away, and its place 
 occupied with earth moistened and closely pressed to the mould in order to 
 make it more firm and steady. It will, when having advanced so far, be in a 
 state to receive the melted metal, to prepare which for the casting, a furnace 
 is made a few feet above the one employed to heat the mould ; it is formed 
 like an oven, having three apertures, one of which is for a vent, the other to 
 admit the fuel, and the last to let the melted metal flow thi-ough and out of the 
 furnace. This last aperture should be kept very close whilst the metal is fusing, 
 when it has arrived at that state which is deemed proper for running it into 
 the shell, and which is known by the quick separation and escape of the zinc 
 of the brass. A little tube is laid to convey it into an earthenware basin, which 
 is fixed up over the top of the mould ; into this basin all the large branches from 
 the jets enter, and from which is conveyed the metal into all parts of the 
 mould. The jets are all stopped up with a kind of plugs, which are kept close 
 till the basin which is to supply the metal be full. When the furnace is first
 
 FOUNDING. 535 
 
 opened for this purpose the melted brass gushes forward like a torrent of fire, 
 and is prevented from entering any of the jets by the plugs, till the basin is 
 sufficiently full to be ready to begin with the mould, and which is esteemed so 
 when the brass it contains is adequate to the supply of all the jets at once, 
 upon which occasion the plugs from all of them are withdrawn. The plugs 
 consist of a long iron rod, with a head at one end, capable of filling the whole 
 diameter of each tube. The hole in the furnace in which the melted metal is con- 
 tained is opened with a long piece of iron fitted on the end of a pole, to allow 
 of the furnace man keeping at a distance from it, as many accidents occur by 
 the red hot metal coming in contact with the air, particularly if it be damp, in 
 which case the most violent explosions take place. The basin is filled almost 
 in an instant after the furnace plug is withdrawn, and the metal is then let into 
 the several jets communicating with the model, which, when they have emptied 
 themselves into the shell or mould, the founding is finished in so far as the 
 casting is concerned. The rest of the work is completed by the sculptor, who 
 takes the new brass figure from out of the mould and earth in which it was en- 
 compassed, saws off the jets, and repairs and restores the parts where required. 
 His tools for this purpose consist of chisels of various sizes, gravers, punches, 
 files, &c. 
 
 In casting colossal statues a somewhat different mode is pursued than the 
 one already described, and this arises wholly from the size, it being found diffi- 
 cult to remove the moulds of such colossal works ; to obviate this difficulty, it 
 is worked and prepared upon the spot where it is to be cast. There are tw 
 ways of performing this, and some founders prefer the one and some the other 
 By the first plan, a square hole is dug into the earth somewhat larger thaa 
 would be required for the mould, and its sides are hemmed up with brick- 
 work ; at its bottom is formed a hole, below the one already prepared, as a 
 furnace, which must be built up with brickwork, having an aperture made 
 outwards into another pit prepared near it, from which the fuel is put into the 
 furnace. The top of the furnace in the first hole is covered by a grating of 
 iron, and on this is moulded and placed the case of the statue to be cast, and 
 also its waxen coating ; in doing which the same process is observed by the 
 sculptor as that already described. Near the edge of the large pit in which 
 the model is placed is erected the furnace to melt the metal, and which is 
 similar to the one already described for common figure casting, except being of 
 larger dimensions ; it has, like that, three apertures one for putting in the wood, 
 another for a vent, and a third to run the metal out at. By the second plan of 
 founding colossal figures, it is thought sufficient to work the model above 
 ground, adopting the same mode with respect to a furnace and grate under- 
 neath it ; for whether under ground or above it, to keep in the heat when 
 drying the core and melting the wax, is the end more particularly sought; 
 to do which in the most effectual way four walls of brickwork are built 
 up round the model, in the middle of which is fixed the grate and furnace ; 
 and on one side above is formed the mass of building intended for the furnace, 
 which is to be appropriated to the melting of the metal. When the whole is 
 finished and ready, a fire is made in the fire-place under the core of the model, 
 and kept up so as to produce a moderate heat to dry the core, and also to melt 
 the wax from off it, which runs down by tubes, as has been before remarked, 
 and indeed no difference whatever takes place in such founding, except 
 every thing being upon a larger scale. When the wax is run off and the fire 
 extinguished in the furnace, bricks are filled in at random, either into the hole, 
 if founding under ground, or into the area between the walls, if above ground ; 
 after this is done, the fire in the furnace is again lighted, and blown up and 
 augmented till such time as both the core and bricks are of a red heat, when 
 the fire is again extinguished, and the whole is left to cool ; and when cooled, 
 the bricks are removed, and all is cleared away, and the space again occupied 
 by moistened earth to secure and steady the model. Nothing now remains but 
 running in the metal, which is performed, as has been before described for 
 smaller foundings of statues. 
 
 The casting of guns is performed in the manner already described for statues,
 
 556 FOUNDING 
 
 excepting that no core is required, it being cast solid, and the cavity entirely 
 bored out, during which operation the gun is turned and finished on the outside. 
 (See CANNON, and BORING MACHINE.) The composition of which cannon is 
 formed in this country is 10 Ibs. of tin to 100 Ibs. of copper, whereas, in the 
 brass of statues, zinc is employed instead of tin. 
 
 Founding in Bronze. The Egyptian bronze consisted, according to Bessari, 
 of two-thirds brass and one-third copper. Pliny says, that the Grecian bronze 
 -vas formed by adding one-tenth lead and one-twentieth silver to the two-thirds 
 of brass, and the one-third of copper of the Egyptian bronze ; and that this was 
 the proportion afterwards made use of by the Roman statuaries. The modern 
 bronze is commonly made of two-thirds copper, fused with one-third of brass ; 
 and recently, owing to the great demand for ornaments and decorative furniture 
 of this alloy, lead and zinc in small proportions have been added to the copper 
 and brass. These additions, it is said, increase the fusibility of the alloy, and 
 facilitate the process of casting. Bronze casting is employed in forming eques- 
 trian statues, colossal and other figures in alto relievo, to adorn public places, its 
 peculiar tint finely contrasting with the stone or marble of architecture, espe- 
 cially when the artist displays taste in his design and skill in his execution. 
 The casting in bronze is performed in the following manner : first, the figure or 
 pattern to be cast must have a mould, and this is prepared and laid on a plaster 
 cast, previously wrought and finished by the sculptor. The mould is made of 
 plaster of Paris, moistened with water, to which is added brick-dust in the 
 proportion of one-third of the former to two-thirds of the latter. This is 
 carefully laid on the mould, with strength in proportion to the weight of metal 
 intended to be used in the founding. In its joints should be cut small channels 
 tending upwards and from different parts of the internal hollow, to allow of 
 vent for the air to escape, as the heated metal runs in xipon the mould. 
 A thin layer of clay should be spread over the inside of it, and of the 
 thickness which it is intended the bronze should be. Withinside of the clay a 
 filling-up of plaster and brick-dust, in the proportions as before described, will 
 be required to compose the core ; but if the work to be cast be large, before 
 the plaster and brick-dust are poured into the mould to form the core, a skeleton, 
 composed of iron bars, as a support for the figure, should be prepared and fixed ; 
 after which the filling up of the core may be proceeded in. When this is done 
 the mould must be opened again, the layer of clay taken out of it, and the 
 core thoroughly dried, and even burned, with a charcoal fire, or with straw ; 
 for if the least damp remain the cast will be blown to pieces when the hot 
 metal comes in contact with it, in running it into the mould, and the workmen 
 employed about the work be maimed or killed by the dispersion of the heated 
 bronze. After the core, &c. has been properly dried and is deemed ready for 
 the work, it should be laid in the mould, and supported in its place by short 
 rods of bronze, which should run through the mould into the core. All being 
 so far advanced, the mould should be clad and bound round with iron, of 
 strength proportionate to the size of the work to be cast; after which the 
 mould should be laid in a situation for running in the metals, and must be 
 supported for that purpose by bricks, &c. Great care should be taken that 
 every part be perfectly dried before any metal be run into the mould, or, as has 
 been before observed, the most fatal consequences will arise to those who may 
 be about the work. A channel must be made from the furnace in which the 
 melted metal is, in order to its running to the principal jet of the mould, and 
 with a descent to promote its flowing rapidly. The jets, furnace, &c. &c. are 
 all contrived, as has been before described, for casting figures in brass. 
 
 Founding of Iron. Owing to the immense demand for cast iron in most ox 
 our great public works, such as bridges, rail-roads, columns, girders, fences, gas 
 and water pipes, house-building, framing of machinery, and innumerable objects 
 of less magnitude, iron founding has become one of the most interesting and 
 important of our national manufactures. Wherever a foundry is to be formed, 
 u dry situation should be selected for it, as dampness would totally prevent any 
 thing being cast with tolerable accuracy, besides rendering the founding, in such 
 places, dangerous to the workmen employed. The floor of a building for this
 
 FOUNDING. 557 
 
 ousinesa should be about ten feet deep, and composed of a kind of loamy sand ; 
 and if the place selected does not afford this convenience naturally, the ground 
 must be made hollow, and such sand brought to fill up the excavation. This 
 loamy sand is for the purpose of burying large moulds beneath its surface, so 
 that the metal may be conveyed to them by channels or soughs hollowed out of 
 the sand, and through which it runs from the furnace to the mould to be cast. 
 A foundry, or casting-house, is provided with as many air or reverberating 
 furnaces, in addition to the blast furnaces, as is required for the extent of the 
 works to be founded at it ; an air or reverberating furnace is only used occa- 
 sionally, either when the metal contained in the blast furnace is not sufficient, 
 or when the quality made in it is not proper for the work about to be cast. 
 The difference in the qualities of the metals arises from their containing too 
 much or too little carbon, and this is corrected by the founder, who mixes them 
 with better or worse metal till they are rendered fit for the purpose required. 
 Cupolas, as they are called, are also wanted in a foundry, and are similar to the 
 blast furnace, except being of somewhat smaller capacity; they are used to 
 melt small quantities of metal when it is wanted in haste, as the reverberatory 
 or blast furnaces will take more time in filling the charge of metal than the 
 cupola does, by reason of their being of larger capacity ; but the founding by 
 cupolas requires more machinery, from which circumstance it is not so well 
 adapted to answer the purpose of the founder as the employment of a reverbe- 
 ratory or blast furnace. A much greater stock of flasks and other implements ia 
 wanted to make the moulds with, than is required by the caster who performs 
 his work by means of either of the other furnaces ; these kinds of furnaces 
 are always in use at large foundries, as at such places can be employed the 
 whole charge of metal they are capable of containing. In a foundry worked 
 by a blast furnace, a pit is sunk at a convenient distance from it, and the 
 moulds for all large articles, such as pipes, &c. are placed vertically in it, 
 within reach of the crane, that they may be raised or lowered in the pit. The 
 metal is conveyed from the furnace by a gutter or trough made in the floor of 
 the foundry, and a small iron trough, filled with sand, conducts the fluid metal 
 into the moulds. This method of performing foundings at large works is an 
 improvement on the old one, (which consisted in burying the pattern in sand,) 
 and which has caused a great saving in labour and time. The flasks for this 
 method of casting are founded of iron. It is now a practice at most of our 
 large foundries to substitute sand for loam castings, in cases in which there are 
 a great number of articles of the same kind to be cast, so that the expense of 
 the flasks becomes an object of no great importance. When it happens that 
 the articles are intricate, the sand is wetted so much as to render it sufficiently 
 adhesive to make it mould, and receive the form of the pattern completely ; 
 after this is done, it is necessary to dry the mould, to prevent accidents by the 
 explosion of the hot metal when running the cast ; for this purpose stoves are 
 used in which an equal and moderate degree of temperature is produced, and of 
 a capacity adequate to contain a good number of the patterns. The moulds, 
 when ready to be dried, are placed upon a carriage adapted to the purpose, and 
 on which they are arranged and conveyed to the oven ; and when dry, which 
 generally happens in about half an hour, they are withdrawn, and a new set 
 placed upon the carriage. Every foundry should be provided with one or more 
 cranes, so placed as to be easily got at when it is required to raise, lower, or 
 remove, any large piece of casting. The moulding of large pieces of cast-iron, 
 when they are required to be hollow, is made in loam, and consists in laying 
 down an iron ring upon the ground, of the diameter of the proposed calibre of 
 the work to be cast, and which has a rod of iron in its centre ; after this is done, 
 bricks, clay, and wet loam are mixed together, and built up within the ring and 
 round the iron rod, of somewhat less diameter than the cylinder about to be 
 cast, and for which this is to form the core. The whole, when built, is bound 
 round with iron hoops to protect it, and a fire is made inside to dry it; and when 
 properly dried, a coating of loam is spread all over and smoothed ; this coat fills 
 up and makes it the proper size for the inside of the cylinder, and is called the 
 core of the mould. Another cylinder is built and plastered in the same manner 
 4 B
 
 558 FOUNDING. 
 
 but without hoops, whose diameter is the same as the outside of the cylinder to 
 be founded. When this is finished, it is covered over with charcoal dust, or 
 ground charcoal, which is mixed up with water-like paint, and laid on with a 
 brush ; and a thin coating of loam, mixed up with hair, is then laid over the 
 charcoal, previously spread upon the inner cylinder. When all these are quite 
 dry, a man gets into the cylinder, and with a picker pulls away from the core 
 the bricks, and then with a trowel cuts away also the loam, leaving the inside 
 of the external cylinder, which is called the mould, quite smooth ; this part 
 pf the work is effected by the coat of charcoal, which prevents the two coats of 
 loam from adhering together. While this is doing, a deep pit is dug, and into 
 this the core is let down by a crane ; when this is done, the mould is lowered over 
 the core ; as soon as the adjustment is perfected, sand is thrown in and rammed 
 jound about it, to about the half of its height ; after which a flat cover of dried 
 loam is put on the top of the mould and core, and pieces of rounded wood are 
 put into the holes, which had been before made for pouring in the metal. The 
 plugs which keep open these holes are carefully taken out, and small channels 
 prepared for the metal to run through from the furnace. Before the metal is 
 run into the mould, the latter should be carefully examined, to ascertain that it 
 is quite dry, and in other respects in a perfect condition to receive the metal. 
 Sand, or open casting, is used for such articles as will allow of cutting into two 
 pieces, or even more, the models of which are indented in the sand, and the 
 metal is run in between flasks. 
 
 A patent for an improved mode of casting metallic cylinders was taken out 
 in 1826 by Mr. William Church, of Birmingham, the object of which was to 
 produce perfectly sound castings of uniform solidity. The process consists in 
 exhausting the air from the moulds by means of an air-pump, and afterwards 
 in forcing the fluid metal, from an air-tight reservoir beneath, upwards into the 
 mould by the aid of a condensing pump. As the apparatus for this purpose 
 may be constructed in a variety of ways, and be adapted to the description of 
 articles to be cast, the patentee has described only one arrangement, which he 
 adopts and recommends for the purpose of casting large cylinders, rollers, 
 cannon, &c. The mould prepared for casting is enclosed in a cast-iron air- 
 tight casing, and suspended in a vertical position, by means of chains, to the 
 {'ib of an ordinary crane, over the vessel containing the fluid metal; to the 
 ower end of the mould, an earthen tube (the materials similar to the crucible 
 ware,) descends and forms the channel for conveying the metal upwards into 
 the mould at the proper period of time ; this earthen pipe is covered with a cap 
 at its lower extremity, which is luted to it so as to be air-tight, and the material 
 and thickness of the cap is such that it will melt a short time after being im- 
 mersed in the fluid metal. As soon as the metal has arrived at the proper 
 temperature the suspended mould, with its appendage, as before mentioned, is 
 lowered by means of the crane, so that the earthen tube is immersed into the 
 liquid metal in the chest beneath ; this metal chest is then closed air-tight with 
 a flange fixed on the upper part of the earthen tube, by proper contrivances 
 for that purpose, such as a conical rim, an elastic metal hoop and luting ; the 
 perfect closing of which is effected by the pressure of the mould in its descent 
 to its seat on the top of the metal chest. The apparatus so far prepared is 
 next connected by short pipes with union joints, to pipes leading from an air- 
 pump of large dimensions, which both exhausts and condenses. First, the air 
 is exhausted from the mould, and from above the surface of the melted metal 
 in the chest; by this time the cap of metal at the lower end of the earthen 
 tube becomes fused, the fluid metal ascends that tube, and is then forced by the 
 condensing operation of the air-pump into the mould above, which, being pre- 
 viously exhausted, the metal is uniformly pressed into every cavity. As the 
 vacuum in the mould is of course imperfect, from the previous exhausting ope- 
 ration, and the remaining portion of air becomes condensed by the rising of the 
 metal, to prevent any ill effects from its pressure, a stop cock, communicating 
 with the exhausting end of the air-pump, is opened, by which it is withdrawn. 
 For the purpose of rapidly cooling the mould after being filled with the liquid 
 metal, the cast-iron mould case is surrounded with an outer case or jacket, with
 
 FOUNDING. 
 
 559 
 
 a vacant space between, which is charged with cold water whenever desired, 
 as in some castings this application must be of great utility in hardening their 
 surfaces. 
 
 In 1825 a patent was taken out by Messrs. White and Sowerby for an air 
 furnace for melting iron, for the use of founders, in which the requisite degree 
 of heat is obtained without the necessity of resorting to mechanical aid, but 
 simply bv the production of natural currents of air through lateral openings or 
 passages," with the further advantage of causing a body of flame to be con- 
 ducted over that portion of the metal lying in a fluid state at the bottom of the 
 furnace, by which it is kept from solidifying prior to the whole contents being 
 discharged. On these principles the patentees state that the furnaces may be 
 made square, round, oval, octagonal, or any other convenient form, with pas- 
 sages for the admission of atmospheric air in various parts and in different 
 directions, according as they may be required to direct the heat. The annexed 
 figures are intended to illustrate one convenient mode of carrying it into effect 
 
 a represents the body of the furnace, in which the coke and metal is deposited ; 
 b and c are flues leading from the same into the vertical chimney d; the capacity 
 or depth of the flues is regulated by dampers e e ; ff show the situation of two 
 of the lateral air chambers, (of which there may be any number;) one of these is 
 shown as opening into the outside of the structure, and the other into an open 
 archway or passage between the chimney and the body of the furnace ; a man hole, 
 for clearing out the bottom or bed of the furnace whenever required, is situated 
 at g. To set the furnace to work, the cover h is removed, and coke or other 
 fuel thrown in, which may be lighted, if required, at either of the air passages//; 
 when the heat has been raised to the proper degree for the fusion of the iron, 
 the metal and coke are thrown in alternately, in such quantities and proportions 
 is may be required for the casting, when the furnace is again to be closed by 
 the cover A. When the whole of the metal is reduced to the fluid state, it is 
 run off from the bed by means of a tap hole in the lower part By the 
 arrangement of the furnace, it will be perceived that a body of flame is made 
 to operate upwards in melting the metal, and another takes a downward course, 
 passing over the bed of the furnace, preserving that portion of the metal which 
 has been already melted, and lying upon it, in a fluid state, until the whole 
 contents of the furnace are melted. 
 
 The founding of iron cannon is conducted in a similar manner to other cast- 
 ings ; the pattern is moulded in the sand, and the metal run into the moiud
 
 56 FOUNDING. 
 
 through a gutter. Small guns are moulded on tables, one half of the mould 
 being formed on one table, and its counterpart on another ; they are fitted 
 together by pins, and screwed up by nuts and bolts to keep them firm together 
 whilst the hot metal is run in. About fifty years ago cannons were cast with a 
 hollow cavity for the bore, which was afterwards enlarged and cleaned out by 
 a machine adapted to the purpose. Guns are now invariably cast solid, owing 
 to the difficulty of getting them perfectly sound by that mode of casting, being 
 more or less spongy in some parts, which the subsequent turning did not wholly 
 remove. For the method of boring and turning great guns, see the article 
 CANNON. 
 
 The manner of casting bells is similar to that of statues, except that bell-metal 
 contains about one-fifth of tin to four-fifths of copper, while the metal of statues 
 contains no tin. The dimensions of the core and wax in modelling a bell, il 
 it be one of a ring of several, must be formed on a kind of scale or diapason, 
 which will give the height, aperture, and thickness of the shell necessary to the 
 several tones required. Our proportions of bells consist in making the diameter 
 fifteen times as thick as the brim, and its length twelve times. See the article 
 BELL, under its initial letter. 
 
 We now come to the description of that department of the foundry art which 
 must be regarded as the most valuable and important when its effects in ame- 
 liorating our condition as intellectual beings is considered : we allude to the 
 art of founding type. This invention is supposed to have originated at Mentz, 
 in the early part of the fourteenth century, when types were carved out of wood. 
 Some time afterwards they were cut of metal, and one Laurentius was honoured 
 as the inventor of this improvement, which, however trifling it may appear as 
 an advance in any mechanic art, proved to be of vast importance in its result. 
 The art of founding or casting types quickly succeeded, which appears to have 
 had its origin also in Germany, as we find they were first introduced into Hol- 
 "land from Strasbourg. By the mercantile activity of the Dutch at this period 
 the new metal type was rapidly dispersed into all the capital cities of Europe. 
 The earliest use of them in this country was at Oxford, in 1468, when a book 
 was printed there by one Bouchier. In 1471 Caxton, who had studied the art 
 in Holland and the Low Countries, established several printing presses in this 
 country. The art of reading, which, but a short time before, was chiefly con- 
 fined to a portion of the clergy and nobles, was soon extended to the other 
 gradations of society; and the ability to read was no longer considered the 
 highest climax and finish of an education, but was made the first step to it, by 
 the introduction of printed books into every school and seminary. As the 
 rudiments of education became improved, books became rapidly multiplied, print- 
 ing encouraged, and ever since a progressive improvement has been gradually 
 developing itself. Until the seventeenth century types continued to be cast with 
 very few improvements, excepting such as arose from alterations in the form 
 of the letters. Caslon set up a foundry in 1720, and succeeded in making 
 several improvements, to which some valuable additions were added by Basker- 
 ville, of Birmingham. Messrs. Fry and Son's foundry was established in 1764 
 In 1770 Mr. Jackson cut some very extraordinary and beautiful types, by a 
 mould and matrix, which were previously cast in sand. Mr. V. Figgins, in 
 1792, produced some beautiful types for the Persian, Greek, and Hebrew 
 characters, never before attempted in this country. In 1800 Messrs. Caslon 
 and Catherwood set about recutting and improving the whole business ; and 
 the superior taste and elegance displayed in their manufacture occasioned a 
 spirit of rivalry in the other type founders, particularly Messrs. Fry, Figgins, and 
 Thorne, who exerted themselves individually so as not to be surpassed by their 
 competitors ; the effect of which has been the production of types of that high 
 degree of excellence, which marks the character of all our books printed since 
 that period. The preparation of the moulds and matrices for the purpose of 
 casting the letters requires the utmost precision of workmanship ; the matrix 
 itself is simply a piece of copper or brass, about an inch and a half long, and 
 of a thickness in proportion to the size of the letter to be cast. In this piece 
 of metal is sunk the face of the letter, by means of a steel letter-punch. These
 
 FOUNDING. 
 
 6C1 
 
 punches being made with every size and kind of letter, are, of course, very 
 numerous; and the making of them, requiring the utmost nicety of execution, 
 necessarily forms a branch of the type-founder's business of considerable im- 
 portance. There are about twenty different sizes of each kind of type in general 
 use, all of which are cast in moulds and matrices, besides several larger sorts, 
 which are cast from patterns in sand. The following table gives the designation 
 of the twenty sizes alluded to, and the spaces they occupy in printing. They 
 are sold to the printer by the pound, at prices varying from two to thirteen 
 shillings, according to their size : 
 
 Diamond type 
 Pearl 
 
 Lines to each foot. 
 
 ... 204 
 . 178 
 
 Lin 
 
 s to each foot. 
 51 
 
 Paragon 
 
 . 44 1 
 
 
 . 143 
 
 Double Pica . . . 
 
 . 41* 
 
 
 . . 128 
 
 Two-line Pica. . . . 
 
 . 35 3 - 
 
 
 . 112* 
 
 Two-line English . . . 
 Two-line Great Primer. 
 Two-line Double Pica . 
 
 . 32 
 
 . 25* 
 . 20J 
 . 18 
 . 17| 
 . 14J 
 
 
 ... 102 
 
 Long Primer 
 Small Pica 
 
 . . . . 89 
 
 83 
 
 Pica 
 
 71i 
 
 Four-line Pica. 
 Five-line Pica. 
 
 English . 
 
 64 
 
 When the moulds and the set of matrices are duly prepared, they are brought 
 to the furnace, and consigned to the hands of the caster. The furnace is built of 
 bricks upright, with four square sides ; the stove for the fuel is at the top, with 
 a round hole made through it, to receive the pan which holds the metal. In a 
 large foundry there are several of these kinds of furnaces. The caster begins 
 his work by taking the mould- in his left hand, and with his right puts back a 
 spring, which keeps the matrix close up to the face of the mould, and then 
 with a small ladle adapted to the size of the work, he dips out of the pan over 
 the furnace a sufficient quantity of fluid metal to fill the mould, and at the 
 same instant that he turns the metal from out of the ladle into the mouth of it, 
 he throws up his hand, in which is held the mould, with a sudden jerk or shake, 
 and by this movement forces the melted metal down into the face of the matrix. 
 In this operation great expertness is necessary. After the letter is thus cast, he 
 relieves the spring, and takes the face of the type from the matrix, which is 
 done by pressing the thumb of the right hand against the top of the matrix ; 
 he then picks out the type, and goes on with the casting. Thus, in the casting 
 of every single type, there are several distinct operations to be performed ; yet, 
 owing to the admirable adaptation of the apparatus to the purpose, an expert 
 caster can, on an average, cast from six to seven thousand letters a day. When 
 the workman has cast as many types- of the same letter as are required, he ex- 
 changes the matrix for one containing another letter, and proceeds as before. 
 The types, after being cast, are received by the " break-off boy," who takes oft 
 the break or rim of the letter ; this operation is performed with so much expe- 
 dition that some boys will break off from 5 to 6000 in an hour. From the 
 break-off boy the new types are put into the hands of a "rubber," to have their 
 rag or beard removed, which is effected by rubbing them over a stone. A great 
 number of boys are employed in a type foundry besides those mentioned in the 
 various processes of the manufacture, such as " kerners," " setters up," 
 " dressers," &c., their operations being directed to the perfecting of the form 
 and finishing of the type, a circumstantial account of which our limited space 
 will not admit of. The metal of the type-founder consists of lead and anti- 
 mony fused together, the proportions of which are regulated by the size of the 
 type to be cast. The smallest sized types require the hardest metal, the alloy 
 for which is 25 of the regulus of antimony to 75 of lead, in 100 parts ; in the 
 larger sizes the proportions are varied accordingly, down to 15 parts of 
 antimony to 85 of lead. The usual method of casting the larger kind of types, 
 is by cutting the letter through a plate of brass, and afterwards riveting to it a 
 back to form a matrix ; these moulds are hung up, and the liquid metal
 
 562 
 
 FOUNDING. 
 
 simply poured into them ; the very large letters are cast in open sand, in the 
 usual way of brass casting. The moulds and matrices of the type-founder are 
 extremely valuable, and are therefore secured every night in strong rooms of 
 iron or stone. 
 
 By the common method of type-founding, which we have now briefly described, 
 only a single letter is cast at a time, and the operation has been nearly the same 
 ior upwards of seventy years ; a scheme was, however, set on foot by a Mr. 
 White, about seventeen years ago, to enable the founder to cast a great number 
 of letters at one time thirty or more ; but it was not carried into practice by 
 any of the founders. About the same time a Monsieur Didot, assisted by 
 Mr. Donkin the engineer, constructed a machine for a similar purpose, which 
 was also intended to perform all the operations of the work by the assistance of 
 a boy only. 
 
 The invention which we have now to describe is an improvement by Monsieur 
 Didot upon his former highly ingenious machine, now rendered capable of 
 casting 200 types at once, and to repeat the operation two or three times in a 
 
 A patent for this country was taken out by Mr. John Louis Puchee, 
 .ew yelrs ago established a type-foundry in Little Queen-street Holborn 
 the machinery is at present in full and successful operation Jhe grea 
 r of drawings which accompany the specification of this patent obliges us 
 select such portions only as will best give a just idea of its ; nature and consnuc- 
 tion and we have for the same reason thrown the side views into perspective. 
 
 minute. 
 
 who a f< 
 
 where 
 
 number of dra 
 
 select such portion
 
 FRACTION. 563 
 
 which exhibits the machine entire, as at Fig. 1. Fig. 3 represents one side of 
 the mould separated into its component parts. Fig. 2 is a section of the several 
 bars composing both sides of the mould. Fig. 4 exhibits a plan of the same, 
 fitted into and encompassed by a frame of iron, a horizontal and perspective 
 view of which is given at Fig. 1. The same letters refer to the same parts in 
 each of the figures, a (Fig. 3) is a steel bar, with horizontal grooves, in which 
 are formed the bodies of the types ; b b is the bar which holds the matrices c c, 
 each of which is arranged opposite to its respective groove in the bar a, to which 
 it is sjrewed fast ; the bar d is then screwed down to the bar b, which holds the 
 matrices c c firmly in their places. The bar e is next laid upon the bar a, which 
 covers the grooves, and forms the upper sides of the square recesses, shown also 
 at e e, Fig. 4. / is the break-bar, and is placed in front of the bar a ; a series 
 of small nicks or openings are made in this bar, through which the fluid metal 
 passes into the grooves and matrices, where the body and letters of the type 
 are cast; the grooves are closed by the spaces between the nicks of the 
 break-bar coming against them, and forming the feet of the types. The bar 
 ff is laid upon the break-bar as a cover to it, and the whole six bars thus com- 
 bined form one side, or one half, of a pair of moulds, shown in section, Fig. 3. 
 This section likewise exhibits the form of the apertures through which the fluid 
 metal has to pass into the grooves and matrices ; h is a receptacle between the 
 moulds for the fluid metal, previous to its being forced into them, as we 
 shall presently describe. In preparing the moulds for casting, the several bars 
 composing them are connected together as before mentioned, and laid upon a 
 solid metallic bed upon the table k k, as shown at Fig. 4 : the sides of the iron 
 frame / /, which turn upon joints, are then brought to bear sideways against the 
 moulds ; the top piece m, which also turns upon a joint, is brought down 
 over the mould bars, which it firmly secures by bringing the looped part of the 
 swinging lever n, shown at Fig. 1, over the end of the top piece m, which is 
 effected by the aid of the hand lever p forcing the tongue o against the lower 
 end of the swinging lever, when the latch z falls and makes all fast. Thus 
 prepared, a sufficient quantity of the fluid metal is poured out of a ladle into 
 the receptacle between the moulds ; a trigger at r is then pulled, when a string 
 connected to it draws back a bolt or catch s, which supports the long lever t, 
 and allows it to fall with the rammer q into the receptacle, which " drives with 
 considerable force the fluid metal from thence into the moulds and matrices." 
 On each side of the rammer q is fixed " a guard or housing, to prevent the 
 liquid metal from being splashed over the operator." In order to withdraw" the 
 types from the moulds, the workman places his foot upon the step M, when the 
 compound lever v acts upon the pin ti>, under the leg z, and forces out the 
 rammer from between the moulds, which is then lifted up by the workman, 
 until it has passed the catch s, which supports it in the position shown in the 
 figure. The mould is now opened by throwing up the hasp x ; the swinging 
 lever n then releases the end of the top piece, and allows the frame to be 
 opened, and the moulds to be removed to a table, where the bars which compose 
 it are placed under cramps, and separated by means of wrenches : the types are 
 then removed, and undergo the operations of dressing, &c. as mentioned in the 
 early part of our subject. 
 
 FOUNT, or FONT, among Printers, a set of types, sorted for use, that includes 
 running letters, large and small capitals, single letters, double letters, 
 points, lines, numerals, &c. ; as a fount of english, pica, bourgeois, &c. A 
 common fount consists of 100,000 characters. See PRINTING and TYPE- 
 FOUNDING. 
 
 FRACTION, in Arithmetic and Algebra, is a part or parts of something 
 considered as a unit or integer. Fractions are distinguished into vulgar fractions 
 and decimal fractions. Vulgar fractions consist of two parts or quantities 
 written one over the other, thus f , f , &c. ; the quantity above the line is called 
 the numerator, and that below the line the denominator. Decimal fractions 
 are written with a dot to the left hand of the series, thus, -1, '02, -003, and may 
 be considered, and are read, as vulgar fractions, whose denominator is always 
 1, with as many cyphers annexed as there are figures in the decimal, and the
 
 561 FRICTlOy. 
 
 decimal will then be the numerator; thus, -1, '02. -003, are to be read ai 
 
 ;'> ^ ,* 
 
 FRANKINCENSE, or OLIBANUM, is a gum resin, the product of the Junipua 
 lycia of Linnaeus, brought from Turkey and the East Indies, usually in drop.3 
 or tears. The best sort is of a yellowish white colour, solid, hard, and brittle. 
 When chewed it impresses an unpleasant bitter taste ; laid on burning coals 
 it yields an agreeable odour, and is for this reason much used by the Catholics, 
 the Jews, and various idolatrous nations, in their religious ceremonies, the 
 powerful perfume having a tendency to prevent the communication of infection 
 amongst a dirty people, and of moderating the disgust created by the slaughter 
 of the victims of the sacrifices. 
 
 FREEZING. See CONGELATION, FROST, and CHEMISTRY. 
 
 FRICTION, in Mechanics, the rubbing of the parts of engines or machines 
 against each other, by which means a great part of their effect is destroyed. A 
 body upon a horizontal plane should be capable of being moved by the smallest 
 application of force ; but this is not the case, and the principal causes which 
 render a greater or less application of force necessary are, first, the roughness 
 of the contiguous surfaces ; secondly, the irregularity of figure, which arises 
 either from imperfect workmanship or the penetration of one body by another ; 
 thirdly, an adhesion or attraction, which is more or less powerful according to 
 the nature of the bodies in question ; and fourthly, the interposition of extra- 
 neous bodies, as dust, moisture, &c. Innumerable experiments have been made 
 to determine the amount of friction or obstruction which is produced in parti- 
 cular circumstances ; but the results of apparently similar experiments which 
 have been made by different experimenters do not agree, nor is it likely they 
 should, since the least difference of smoothness or polish, or of hardness, or, 
 in short, of any of the concurring circumstances, produces a different result : 
 hence no certain and determinate rules can be laid down on the subject of 
 friction. Mr. Vince, who has done much on this subject, infers, first, that 
 friction is a uniformly retarding force in hard bodies, not subject to alteration 
 by the velocity except when the body is covered with cloth, woollen, &c., and 
 in this case the friction increases slightly with the velocity ; secondly, friction 
 increases in a rather less ratio than the weight of bodies ; the rate of increase, 
 however, is various in different bodies, nor is it sufficiently determined for 
 any one body what proportion the increase of friction bears to the increase of 
 weight. The smallest surface, at least up to a certain point, has the least 
 friction, the weight being the same ; but the ratio of friction to the surface is 
 not yet accurately known. The friction of mechanical engines not only 
 diminishes the effect, or, which is the same thing, occasions a loss of power, 
 but is attended with the corrosion and wear of the principal parts of the 
 machine, besides producing a considerable degree of heat, and even actual fire ; 
 it is therefore of great importance in mechanics to contrive means capable of 
 diminishing, if not quite removing, the effect of friction. 
 
 The methods of obtaining the important object of diminishing friction are of 
 two sorts, viz. either by the interposition of unctuous or oily substances between 
 the contiguous moving parts, or by particular mechanical arrangements. 
 Olive oil is the best and perhaps the only substance that can be used in delicate 
 work, as clocks and watches, when metal works against metal ; but in large 
 works the oil is liable to drain off unless some method be adopted to confine it. 
 The best contrivance with which we are acquainted, for preventing the waste 
 of oil, and for keeping gudgeons or axes properly supplied with it, is Barton's 
 Patent Lubricator, a section of which is shown in the accompanying engraving, 
 with the manner of applying it to the shafts of mill work, a shows a section 
 of a metallic vessel filled with oil, and closed by a lid to prevent the admission 
 of dust or other adventitious matter ; b is a small tube rising to nearly the top 
 of the vessel, and with the lower part extending an inch or two below it, and 
 inserted into an aperture made through the plummer block, directlv over the 
 shaft c, shown also in section ; through this tube a few threads of woollen yarn 
 are drawn, which reach to the bottom of the vessel, and conduct the oil by 
 capillary attraction, as a syphon, in minute but regular quantities to the shaft
 
 FRICTION. 
 
 565 
 
 or gudgeon ; the whole of the oil in the vessel is thus carried over, entirely free 
 from dust or other impurities, and in the precise quantity required, which is easily 
 regulated by the number of threads. It must be obvious that the economy o* 
 
 this contrivance is very considerable ; that machinery, where it is applied, win 
 run with less friction, last longer, and require less power. Since the above 
 cut was executed, Mr. Barton has greatly improved these lubricators, and 
 materially extended their utility. From some experiments which have been 
 made, it appears that when the strain is very great the solid unguents appear 
 to be more effectual in diminishing friction than oils, and in this case tallow 
 or swine's grease is generally employed. The celebrated "Anti-Attrition Com- 
 position" is simply a mixture of hog's lard and plumbago, in the proportion 
 of four parts of the former to one of the latter. In launching ships the 
 " ways" are smeared with soft soap. The mechanical contrivances for the 
 diminution of friction consist either in avoiding the contact of such bodies as 
 produce much friction, or by substituting a rolling for a sliding motion, as far 
 as it may be practicable. As an instance of the first method we may notice 
 that in mill work, the wooden axes of large wheels terminate in iron gudgeons, 
 turning generally in brass bearings, which produces less friction than wood 
 upon wood ; and as the iron gudgeon can be made of smaller diameter than 
 wooden ones of the same strength, the friction is also diminished from thxxt 
 cause in nearly the same ratio. The conversion of a sliding motion into a 
 rolling motion is effected by interposing cylindrical bodies between the moving 
 parts of machines, which, according to their size and arrangement, are denomi- 
 nated rollers, wheels, and (although improperly) friction rollers. In order to 
 understand the nature of rollers, and the advantages attending their use, it 
 must be considered that when one body is dragged over the surface of another, 
 the inequalities of the surfaces of both bodies meet and oppose each other, 
 which is the principal cause of friction or obstruction ; but when one body, 
 such as a cask, a cylinder, or a ball, is rolled upon another body, the surface 
 of the roller does not rub upon the latter, but its parts are successively 
 applied to or laid upon it, and are afterwards lifted up from it ; therefore, 
 ill rolling, the principal cause of friction is avoided, and other advantages alsc 
 4 c
 
 566 1-TKL. 
 
 obtained: thus, in mounting a carriage upon wheels, instead of placing it 
 upon skids or a sledge, the only friction arising from the sliding of one part 
 over another is that which takes place between the axle and the box in which 
 it works. The diminution of friction from this cause will be in the proportion 
 of the diameter of the wheel to that of the axle, and it is further diminished 
 by the friction being that of metal sliding upon metal, which offers much less 
 resistance than the best made road could be brought to do, and also that the 
 friction may be further reduced by means of lubricating substances. When the 
 sliding motion in machinery is not in a rectilinear direction, but arises from the 
 revolution of axes in their bearings, a great part of it may be converted into a 
 rolling motion by supporting the axes upon the peripheries of four wheels instead 
 of the usual fixed bearings ; an instance of this is seen in the elegant machine 
 invented by Mr. Atwood for illustrating the laws by which the descent of falling 
 bodies is regulated. But although friction detracts from the effect of machines, 
 and it is therefore generally an object to reduce it to the utmost, yet the action 
 of some parts of machinery depends upon friction, as in the case of the brake 
 of a crane or the drag of a coach. For light machinery, also, wheels are some- 
 times made to turn by contact, by simply covering their periphery with buff 
 leather, the resistance of the work not being sufficient to overcome the friction 
 between the two surfaces. 
 
 FRIT. The matter or ingredients of which glass is made, after they have 
 been calcined in a furnace. These ingredients are chiefly soda and flint, or 
 silicious sand. 
 
 PRIZING OF CLOTH. A term applied to the forming the nap of 
 woollen cloth into a number of little hard burs or prominences covering almost 
 the whole of the ground. It is commonly performed by a machine or mill 
 worked by water or horses ; the structure is as follows : The principal parts 
 are the frizer, the frizing table, and the drawer or beam ; the two first are 
 two equal planks or boards, each about ten feet long and fifteen inches broad, 
 differing only in this, that the frizing table is covered with a coarse kind of 
 woollen stuff, with a rough sturdy nap, and the frizer is incrustated with a kind 
 of cement, composed of glue, gum arabic, and a yellow sand, with a little aqua 
 vitae, or urine. The beam or drawer, thus called because it draws the stuff 
 from between the frizing table and the frizer, is a wooden table, beset all over 
 with little, fine, short points or ends of wire, like those of cards used in carding 
 of wool. The cloth, being stretched along the frizing table with that side upper- 
 most which is to be frized, is drawn slowly over the table by the beam or drawer, 
 whilst the frizer, which is suspended at such a distance from the table as merely 
 to allow the cloth to pass between the two surfaces, and which has a very slow 
 semicircular motion, meeting the long hairs or naps of the cloth, twists or rolls 
 them into little nobs or burs ; the workman supplying and stretching the cloth 
 at one end of the table as fast as it is drawn forward by the drawer at the 
 other end. 
 
 FROST. Such a state of the atmosphere as causes the congelation or 
 freezing of water or other fluids into ice. In the more northern parts of the 
 world even solid bodies are affected by frost, though this is only or chiefly in 
 consequence of the moisture they contain, which being frozen into ice, and so 
 expanding, as water is known to do when frozen, it bursts and rends any thing 
 in which it is contained, as plants, trees, stones, and large rocks. Many fluids 
 expand by frost, as water, which expands about one tenth part, for which reason 
 ice floats in water ; but others again contract, as quicksilver, and thence frozen 
 quicksilver sinks in the fluid metal. 
 
 FRUSTRUM, in Geometry, is the part of a solid next the base left by 
 cutting off the top or segment by a plane parallel to the base, as the frustrum 
 of a cone, a pyramid, a conoid, or of a sphere, which is any part comprehended 
 between two parallel circular sections ; and the middle frustrum of a sphere is 
 that, whose ends are equal circles. 
 
 FUEL. Those substances which receive and retain fire until they are wholly 
 or partially consumed. Dr. Black divided fuel into five classes. The first com- 
 prenends the fluid inflammable bodies; the second, peat or turf; the third
 
 Fl'KL. 5C7 
 
 charcoal of wood ; the fourth, pit coal charred ; and the fifth, wood or pit coal 
 in a crude state, and capable of yielding a copious and bright flame. The fluid 
 inflammables are considered as distinct from the solid on this account that 
 they are capable of burning upon a wick, and become in this way the most 
 manageable sources of heat, though, on account of their price, they are never 
 employed for producing it in great quantities, and are only used when a gentle 
 or small degree of heat is sufficient. The species which belong to this class 
 are alcohol and the different oils. The first of these, alcohol, when pure and 
 free of water, is as convenient and manageable a fuel for producing moderate 
 heats as can be desired ; its flame is perfectly clean and free from any kind of 
 soot; it can easily be made to burn slower or faster, and to produce less or more 
 heat, by changing the size or number of wicks upon which it burns ; for 
 as long as these are fed with spirit in a proper manner, they continue to yield 
 flame of precisely the same strength. The cotton, or other materials of which 
 the wick is composed, is not scorched or consumed in the least, because the 
 spirit with which it is constantly soaked is incapable of becoming hotter than 
 1 74 Fahr. ; it is only the vapour which arises from it that is hotter, and thia, 
 too, in the parts most remote from the wick, and where only the combustion is 
 going on, in consequence of communication and contact with the air. At the 
 same time, as the alcohol is totally volatile it does not leave any fixed matter, 
 which, by being accumulated on the wick, might render it foul and fill up its 
 pores ; the wick, therefore, continues to imbibe the spirit as freely, after some 
 time, as it did at the first. These are the qualities of alcohol as a fuel: but 
 these qualities belong only to a spirit that is very pure. If it be weak, and 
 contain water, the water does not evaporate so fast from the wick as the more 
 spirituous part, and the wick becomes, after some time, so much soaked with 
 water that it does not imbibe the spirit properly : the flame becomes much 
 weaker, or is altogether extinguished. When alcohol is used as a fuel, there- 
 fore, it ought to be made as strong or as free from water as possible. Oils, 
 though capable of burning in a similar manner to alcohol, are not so conve- 
 nient in many respects ; the soot which they emit accumulates at the bottom of 
 the vessel exposed to it, and checks the transmission of heat. By employing 
 numerous very small wicks, or the argand burners, we may chiefly prevent the 
 formation and deposit of soot ; but the wicks become scorched or charred, and 
 are soon rendered incapable of absorbing the oil so fast as before. Attempts 
 have been made to obviate this difficulty by making wicks of incombustible 
 matter, as asbestos or wire ; nevertheless, as the oil does not totally evaporate, 
 a small quantity of gross carbonaceous matter fixes itself to the wicks which, 
 by degrees, absorb less and less of the fluid, until they become quite useless. 
 
 The second class of fuel mentioned, peat or turf, is so spongy, that, compared 
 with the more solid fuels, it is unfit to be employed for producing strong heats. 
 It is too bulky for this ; we cannot put into a furnace at a time a quantity 
 that corresponds with the quick consumption that must necessarily go on when 
 the heat is violent. There is, no doubt, a great difference in this respect among 
 different kinds of peat, but this is the general character of it ; however, when 
 we desire to produce and keep up by means of cheap fuel an extremely mild 
 uniform heat, we can hardly use any thing better than peat ; but it is best to have 
 it previously charred or burnt to a black coal. When prepared in this manner 
 it is capable of being made to burn more slowly and gently, or will bear, without 
 being extinguished altogether, a greater diminution of the quantity of air with 
 which it is supplied than any other of the solid fuels. According to Clement 
 and Desormes peat affords only about one-fifth of the heat that is given out by 
 an equal weight of charcoal. Mr. Tredgold states, that the weight of a -cubic 
 foot varies from 44 to 70 pounds, and that the dense varieties afford about 40 
 per cent, of charcoal ; the other varieties nearly in proportion to their density. 
 
 The third class mentioned, the charcoal of wood, is capable of affording an 
 intense heat. Mr. Dalton, by heating water, obtained a result equivalent to 
 melting 40 Ibs. of ice with 1 Ib. of charcoal. Dr. Crawford's experiments give 
 69 Ibs. of ice melted by 1 Ib. of charcoal. Lavoisier, Clement, and Desormes, 
 about 95 Ibs. ; and Hasscnfratz, 92 Ibs. Mr, Tredgold considers 47 Ibs. of ice
 
 568 FUEL: 
 
 melted to be the real average effect of 1 Ib. of charcoal : a cubic foot weighs 
 about 15 Ibs. 
 
 The fourth mentioned class of fuel, pit coal charred or coke, possesses 
 similar properties to wood charcoal, although it is a much stronger fuel, that 
 is, it contains the combustible matter in a more condensed form ; it is, there- 
 fore, consumed much more slowly, and is better adapted for long-continued 
 intense heats. It has, however, a defect, from which wood charcoal is free ; it 
 leaves dense ashes in the grate, which in time collect in such quantity as to 
 obstruct the passage of the air; and when the heat is intense, these ashes 
 vitrify into a tenacious substance, which clogs the furnace. It is preferable to 
 wood coal for melting metals, as affording a greater quantity of heat before it 
 is consumed, and at a less expense. 
 
 The fifth class of fuel, according to Dr. Black, is wood and crude coal ; these 
 differ from their charcoals in affording copious and bright flames when plenty 
 of air is admitted to them. If but little air be admitted sooty vapours are 
 given out without flame, and with greatly diminished heat. Wood and candle 
 coal do, however, differ from each other so much, as respects their useful pro- 
 perties in manufacturing operations, that we deem it necessary here to drop the 
 generalization of Dr. Black, and consider wood and coal, and the varieties of 
 each, separately. First, as respects 
 
 Wood : its effect in producing heat depends greatly on its state of dryness. 
 Several experiments made by Count Rumford show the effect of dry wood to 
 be much greater than that of unseasoned ; the latter containing about one-third 
 of its weight of water. The kind of wood is also a cause of some difference ; 
 lime-tree wood was found, by Count Rumford, to give out most heat in burn- 
 ing. With lib. of dry pine-wood, the Count caused 20.10 Ibs. of ice-cold 
 water to boil. The same weight of dry beech made only 14.33 Ibs. of ice-cold 
 water to boil. A cubic foot of dry beech weighs about 49 Ibs. By the experi- 
 ments of Fossombroni, wood was found capable, by its combustion, to evapo- 
 rate twice its weight of water, or to prepare two-thirds of its weight of salt. 
 Rumford made the effect about one-third more than Fossombroni, owing, pos- 
 sibly, to superior management in the former. By an experiment made at the 
 Opera House, in Paris, 160 Ibs. of wood were found to be equal in effect to 
 58 Ibs. of coke. 
 
 As respects coal, there is a considerable difference in the effects of the several 
 varieties. The caking or binding coal with which London is supplied from the 
 great coal fields in Northumberland and Durham, under the general name of 
 Newcastle coal, is much esteemed, from its affording a great heat, and burning 
 with a lively flame ; but those of Wall's End are regarded as superior to the 
 latter for domestic use, as they burn with a whiter and more brilliant flame, and 
 do not cake so hard in the grate. The Tanfield Moor coals are preferred for 
 forges and furnaces, as they burn slowly, and afford a strong and long continued 
 heat. From the experiments of Mr. Watt, it appears that a bushel of New- 
 castle coal, which weighs about 84 Ibs. is competent to convert from 8 to 1 2 
 cubic feet of water into steam, from the mean temperature of the atmosphere 
 and that a bushel of Swansea coal will produce the same effect. Dr. Black 
 states, 7.91 Ibs. of the best Newcastle coals will convert one cubic foot of water 
 into steam capable of supporting the mean pressure of the atmosphere ; and 
 this statement appears perfectly to accord with the more extended experiments 
 of Watt Smeaton makes it require 1 1.4 Ibs. of coal to produce the same 
 result in steam ; but Smeaton has omitted to state the kind of coal. If he 
 employed the Staffordshire coal, there is no discrepancy, as will appear from 
 the table of Mr. Tredgold's experiments and calculations, which we shall subse- 
 quently insert in this article. Mr. Tredgold found, that after the brickwork, &c. 
 of the boiler of a steam-engine was warmed, a little less than 1 Ib. of Wall's End 
 coals would make a cubic foot of water boil, from the mean temperature of 
 52. To produce the same effect with inferior coals a stronger draft and more 
 time and attention are necessary. Splint coal, or hard coal, called by Kirwan 
 slaty cannel coal, is regarded as equally valuable for many purposes as the 
 Newcastle caking coal. It does not nroduce so much flame nor so much
 
 FUEL. 
 
 5G9 
 
 smoke ; it does not kindle so quickly, nor does it agglutinate, like caking coaL 
 A large body of splint coal makes a strong and lasting fire. Cherry coal, or 
 soft coal, readily catches fire, and burns with a clear yellow flame, giving out 
 much heat, and the flame continues till nearly the whole coal is consumed. It 
 burns away more rapidly than either caking or splint coal, and leaves a white 
 ash ; it is easily distinguished from caking coal by its not melting or becoming 
 soft when heated ; It makes a more agreeable fire, and does not require to be 
 stirred. It requires care and management in an open grate, even to burn the 
 small fragments which are made in breaking up the pieces to a fit size for the 
 fire : hence the small coals are often mixed with clay, and made into balls. 
 When these balls are dry, Mr. Gray says, they make an excellent addition to 
 the fuel for an open fire, producing a very durable heat. Mr. Watt calculated 
 that 1121bs. of these coals produced the same effect in raising steam as 841bs. 
 of the Newcastle coal. 
 
 The following table, by Mr. Tredgold, shows the comparative and real effect 
 of the principal varieties of solid fuel in converting water into steam. 
 
 ! 
 1 
 
 Kind of fuel. 
 
 Fraction of a pound that 
 will heat one cubic foot 
 of water one degree of 
 Fahrenheit's scale. 
 
 Pounds of fuel that 
 will convert one 
 cubic foot of water 
 into steam. 
 
 j, '. ' 
 
 Newcastle, or caking coal 
 
 0.0075 
 
 0.0075 
 0.0100 
 0.0172 
 0.0242 
 0.0265 
 0.0475 
 0.0095 
 0.0069 
 0.0205 
 
 8.40 
 8.40 
 11.20 
 19.25 
 27.00 
 30.00 
 53.60 
 10.60 
 7.70 
 23.00 
 
 Staffordshire cherry coal . 
 Wood (dry pine) . . . 
 (dry beech) . . 
 (dry oak) .-.';>- 
 Peat of good quality . . 
 Charcoal- ..-...-.- 
 Coke . . . . . - 
 
 Charred peat .-.-.. 
 
 Mr. S. F. Gray- is of opinion that fire-balls, x>f the size of goose eggs, composed 
 of coal and charcoal in powder, mixed with. a due. proportion of wet clay, and 
 well dried, would 'make a much more cleanly and in all respects a pleasanter fire, 
 than can be made with crude coals, and not more expensive. He states, that in 
 Flanders and Germany the practice of making equal weights of clay and coals 
 together, and forming them into cakes, is common, and that the labour of the 
 preparation is amply repaid by the improvement of the fuel, the coals thus mixed 
 burning much longer, and giving more heat, than when they are burnt in their 
 crude state ; that although clay is an incombustible body, the fact is certain 
 that coals so mixed afford more heat. For the purpose of lighting a fire speedily, 
 Mr. Gray recommends the formation of " kindling balls," composed of equal 
 parts of coal, charcoal, and clay, the two former reduced to a fine powder, well 
 mixed and kneaded with clay moistened with water, and then formed into 
 balls of the size of hens' eggs, and thoroughly dried, which, he says, may be used 
 with great advantage, instead of wood. These kindling balls, he further observes, 
 may be made so inflammable as to take fire in an instant, and with the smallest 
 spark, by dipping them in a solution of nitre, and then drying them again ; if 
 made of pure charcoal mixed with a solution of nitre, they would be still more 
 inflammable. In situations where coals are scarce or dear we think that the 
 mixtures recommended by Mr. Gray might be found convenient and economical; 
 but when it is considered that the average price of coals in England is not more 
 than a shilling for a hundred weight, we can hardly conceive it possible that 
 the same weight of fire-balls, of the size of hens' eggs, could be manufacturea 
 for the sum mentioned. It would appear, from Mr. Gray's remarks, that he 
 was not aware that several patents had previously been taken out for the very 
 obj ects mentioned by that gentleman ; and although the advantages of them 
 may not be very apparent in most situations, there are doubtless many localities 
 where it may be otherwise ; for the latter reason we shall, therefore, insert a
 
 670 FUMIGATION. 
 
 brief notice of some of them. Mr. Sunderland's patent dated 1825, is for a 
 fuel, in which gas-tar, clay, and refuse woody matter, are combined in various 
 proportions, according to the degree of inflammability required. One part of 
 gas-tar, one of clay, and two parts of any convenient woody matter, such as 
 saw-dust, tanners' spent bark, dyers' refuse wood, or peat, burn extremely well. 
 If equal parts of the tar, clay, and saw-dust be employed, they make a com- 
 position which burns vividly and with a brilliant flame. The materials are, of 
 course, to be thoroughly mixed, made up into lumps, and dried either artificially 
 or in the open air, preparatory to their being used as fuel. Messrs. Christie 
 and Harper's patent, dated 1824, was for various mixtures of culm and stone 
 coal (or anthracite) with bituminous or caking coal, depending upon the nature 
 of the heat required ; for the boiler furnaces of steam engines, where the bars 
 are half an inch apart, the patentees state that one-fourth of the bituminous 
 coal answers well for invigorating the other three-fourths. In 1 800 Mr. Peter 
 Devey had a patent for an improved artificial fuel, and the same gentleman, in 
 1821, had another patent for fuel balls, the particulars of which will be found 
 in the specifications of their patents in the Inrolment offices in Chancery. 
 FULCRUM, in Mechanics, the prop or support upon which a lever turns. 
 FULLER'S EARTH. A soft, greyish brown, dense marl. When dry it is 
 of a greyish ash-coloured brown, in all degrees, from very pale to almost black, 
 and it has generally something of a greenish cast ; it is of a compact fexture, 
 smooth to the touch, and does not stain the fingers. Thrown into water it 
 makes no ebullition or hissing, but swells gradually in bulk, and falls into a fine 
 soft powder. Fuller's earth is of great use in scouring cloths, stuffs, &c., imbibing 
 all the grease and oil used in preparing and manufacturing the wool ; but owing 
 to the almost general use of soap for these purpose^ it is not now in such 
 request in this country as formerly. In England it is found chiefly in Hamp- 
 shire, Bedfordshire, and Surrey ; it consists of 
 
 Silex 51.8 
 
 Alumine 25.0 
 
 Lime 3.3 
 
 Magnesia 0.7 
 
 Oxide of Iron 3.7 
 
 Water 15.5 
 
 100. 
 
 FULLING. A process by which woollen cloths are divested of the oil they 
 imbibe by the operation of carding, and the texture at the same time rendered 
 much closer, firmer, and stronger. This process, also called milling, is per 
 formed by a mill, thence called a fulling mill, the machinery of which consists 
 of a number of wooden stampers or beetles, working in a large trough by 
 Cleans of cams or wipers on the shaft of a water wheel. The cloths are laid 
 in the trough, and a quantity of warm water, in which is put a portion of fuller's 
 earth or soap, being poured upon it, it is subjected to the action of the stampers, 
 the repeated blows of which cause the fibres to felt and combine more closely 
 together. After a time it is taken out, and the grease and filth wrung therefrom, 
 and again returned to the fulling mill, from which it is occasionally taken to be 
 stretched, and to undo the plaits it has acquired in the trough. When it is 
 sufficiently milled and brought to the quality and thickness desired, it is scoured 
 in the trough in clear water until perfectly clean, after which it is hung upon 
 tenter-hooks to dry. 
 
 FULMINATING POWDERS. A variety of chemical combinations, 
 which explode, by the application of certain degrees of heat, with instantaneous 
 combustion and prodigious noise. See DETONATING POWDERS. 
 
 FUMIGATION. A process for destroying contagious miasmata or effluvia, 
 by the fumes of various substances. The most efficacious substance for this 
 purpose is chlorine, which may be readily applied in the state of gas by placing 
 in the apartment to be fumigated an earthen pan, containing sea salt and black 
 yxide of manganese, and pouring dilute oil of vitriol upon the mixture ; but a
 
 FURNACES 571 
 
 solution of chloride of 1'r.ne is generally preferred. Next to chlorine in efficiency 
 is the vapour of nitric acid ; and, lastly, of muriatic acid ; but the fumes of 
 heated vinegar, burning sulphur, or exploded gunpowder, deserve little confidence* 
 FUNNEL. A conical or bell-mouthed instrument with a narrow tube, for 
 facilitating the transferring of liquids or small substances from one vessel to 
 another. Any pipe or passage is sometimes called by this name, in particular 
 the small shaft or tube of a flue. 
 
 FUR, in Commerce, signifies the skins of several species cf animals, dressed 
 in alum, with the hair on, and used for the purposes of dr^-ss. The kinds mostly 
 made use of are those of the ermine, sable, beaver, hare, rabbit, &c. The fur, 
 properly so called, of various amphibious animals, as the seal and beaver, is 
 protected by a coating of long coarse hair ; this hair requires to be removed 
 prior to the short fur being sheared off for the purpose of covering hats. This 
 is generally effected by hand, for which purpose women and children are enr 
 ployed ; but a patent has recently been obtained by Mr. A. Bell for a machine 
 for performing the operation, the mechanical arrangements of which appear 
 to be simple and effective. The skin passes round a projecting bed, and is 
 advanced by machinery arranged for that purpose, the tension of the skin being 
 duly maintained by weights. In front of the projecting bed are two cylinders 
 of greater length than the width of the skins, and four or five inches in diameter. 
 Over the circumference of each of these cylinders, hut in contrary directions, 
 is wound, in a spiral line, a projecting rib ; each of these ribs making only one 
 revolution of the cylinder in spirally traversing its entire length. These cylin- 
 ders are driven by means of a rigger on the axis of the lower one, and are 
 placed so near to each other as to occasion the ribs to come in contact and to 
 press whatever hair or fur comes between them. As the skin is drawn forward 
 pver the edge of the projecting bed the long hairs stand nearly at right angles 
 to the ribs on the cylinders, which, in their revolution, forcibly seize the hairs, 
 and extract the same. In order that the pressure of the ribs may be somewhat 
 elastic, and take better hold of the hairs, they are covered with leather. 
 
 FURLONG. A measure of length, equal to the eighth part of a mile, or forty 
 p^les. 
 
 FURNACE. A vessel or apparatus, wherein fuel is burnt in chemical, manu- 
 facturing, and culinary operations. Furnaces are as various, and even more so, 
 than the particular objects for which they are designed ; to accomplish these so 
 that they shall perform their offices in the most economical and convenient 
 manner, is the proper study of those who have to construct or employ them. 
 The proper choice of materials, adapted to the degree of heat and other circum- 
 stances, is also of the greatest importance ; indeed, the resulting products of 
 furnaces greatly, and often wholly, depend upon the combined application of 
 chemical knowledge, manufacturing experience, and inventive skilL The fol- 
 lowing appear to be the essential qualifications of a good furnace : first, to be 
 able to concentrate the heat, and direct it as much as possible to the sub- 
 stances to be acted upon ; second, to prevent the dissipation of the heat after 
 it is produced ; third, to obtain the greatest quantity of heat from a given 
 quantity of fuel; fourth, to be able to regulate at pleasure the necessary 
 degree of heat, and have it wholly at the operator's management Under the 
 articles BOILER, IRON, AIR, FOUNDRY, and various others that occur in this 
 work, numerous practical examples are given of the construction of furnaces ; 
 it will therefore be our business, under the present head, to supply the defi- 
 ciencies that are left on the subject, which we shall premise by some observations 
 on the nature and proper construction of furnaces in general. In the construc- 
 tion of furnaces for boilers every thing should be combined that has a tendency 
 to add to the effect of the fuel, and to avoid that which is calculated to diminish 
 its effect ; but without a knowledge of the nature of burning, we should be 
 like seamen traversing the ocean without a compass. When a portion of fuel is 
 gnited in a close fire-place it must be supplied with air to enable it to burn : 
 and the fuel itself in the process of burning is partly converted into gaseous 
 natter, which escapes up the chimney with a portion of the air supplied to the 
 fire ; but the greater part of the air so supplied ought (as Mr. Tredgold observes ^
 
 572 FURNACES. 
 
 to be changed in the process, by its oxygen uniting with the carbon, and otliei 
 combustible parts of the fuel, forming carbonic acid gas, vapour, &c. Now, in 
 order that perfect combustion, or burning of the fuel, may take place, the air 
 should have free access to every part of the fuel, which is heated sufficiently 
 to burn ; as fuel must be heated in a certain degree, otherwise its elements 
 will not combine with the oxygen of the air. And we see clearly the advan- 
 tages of a regular supply of fuel : this advantage is greater in proportion to the 
 quantity of hydrogen contained in the same ; for if a large body of such fuel be 
 at once put upon the fire, much of the hydrogen will escape in a gaseous state 
 unconsumed, carrying off with it a very considerable portion of heat; whereas 
 if the fuel be thinly scattered over the surface of the fore part of the fire the 
 hydrogen would most likely be consumed in passing over the red hot embers in 
 the after part of the fire, and the product go off in steam ; and that the latent 
 heat of such steam may not be lost, it will be desirable to have a horizontal flue 
 of metal for the smoke to pass along after it has left the boiler, when the steam 
 can be condensed, and the heat applied to warin water for the boiler or other 
 useful purposes. But to succeed in consuming the combustible gases, it is 
 necessary that they should mix with the air that has become hot bypassing (as 
 expressed by Mr. Watt, in the specification of his patent in 1785,) "through, 
 over, or among, fuel that has ceased to smoke," or by being drawn through small 
 flues or channels in the brickwork round the fire, in such a manner as to 
 be heated before it mixes with the gas to be consumed ; but unless hydrogen, 
 or some of its combinations, are constantly passing off, the introduction of a 
 stream of air into the fire-place will only take away the heat from the boiler ; 
 and therefore in a slow fire, consisting chiefly of carbon, it will do more harm 
 than good; while in a quick fire of cherry coal, or cannel coal, in which 
 hydrogen is abundant, it must be a great advantage, and particularly when 
 the fire is regularly supplied with fuel. The quality of the air to supply the 
 fire, Mr. Tredgold remarks, is worthy of being considered, although any 
 dirty wet hole is usually esteemed good enough for the fire place. Now 
 the air ought to be dry, for air charged with moisture is improper, and only 
 takes away heat ; but where there is a very low chimney, and consequently 
 an imperfect draft, some water in the ash-pit will increase the draft, by 
 being converted into steam by the heat of the ashes, the mixture of the steam 
 rendering the smoke much lighter than common air. The air should be cool 
 when it enters the ash-pit, that it may pass with greater velocity through 
 the fire, and the fire-place shed should be dry, in order that the apparatus 
 may be durable, and be kept in order with little attention. The opening to 
 admit air to the fire should be sufficiently large for producing the greatest 
 quantity of steam that can be required, but not larger, and it should be 
 constructed so as to increase in size as it approaches the fire. The area of 
 the spaces between the bars should clearly be much greater than the area of 
 the place that admits air to the fire. The fire should be made immediately 
 under the boiler or other vessel to be heated, that its full effect may be exerted 
 upon the bottom ; and after quitting the fire, the mixture of flame and smoke 
 should pass through a wide and shallow aperture, called the throat; wide, that 
 it may spread under the greatest surface of the boiler ; and shallow, that it may 
 pass through with considerable velocity, and consequently be impelled against 
 the bottom of the boiler. In making the flue circulate, according to the usual 
 mode, round the sides of a long boiler, the heat never extends far enough to 
 render it effectual throughout its length, and the action being oblique the 
 advantage gained is very trifling ; for the same reasons, the making of a flue 
 to return through the boiler offers no advantage that compensates for its com- 
 plexity of construction, since the heat may as well be confined to act upon the 
 bottom, and have less depth of water. The depth of fuel to be on fire at the 
 same time should be sufficient to ignite the fresh fuel, without impairing its 
 action on the boiler in a sensible degree. From the observations and experi- 
 ments made by Mr. Tredgold to determine this point, it appears that the depth 
 of burning fuel should be about three or four times the depth of what irf added 
 at & time ux feeding the furnace ; that is, four times when you feed frequently
 
 FUUNACES. 573 
 
 and three times when you feed seldom ; and according to the nature of the 
 fuel, there will be greater or less space wanted hetween the bars and the 
 boilers. In the construction of furnaces, the slowest conductors of heat should 
 be used ; some metal work is absolutely necessary that is, simply the bars and 
 a frame at the mouth, where the fuel is put in, with or without a door ; in the 
 latter case, the space is to be filled with fuel. The rest of the brickwork should 
 be built with hard well burnt bricks ; and in order to confine the heat to the 
 boiler, it will be proper to leave cavities in the brickwork ; and, with the excep- 
 tion of the necessary ties, to form a double wall, with a hollow space between, 
 keeping the maxim of Morveau always in view to insulate the fire-place from 
 all bodies that are rapid conductors of heat. Between the fire door and the bars 
 there should be a dead space ; on this the fresh coals are laid, previous to their 
 being pushed forward on the grate, which should not be done until they have 
 given out their gas over the brightly ignited fuel on the bars. This dead space 
 is usually covered with an iron plate, called a dead plate, but it is preferable to 
 floor it with fire tiles, as the latter are less liable to affect the fittings of the door 
 and frame. The bars are of course proportioned to the size of the furnace ; 
 they are usually from 1$ to 3 inches in depth, and the thickness varying from 
 f to li inch ; the length seldom exceeds three feet ; and where a more extended 
 grate is required, they are generally laid in separate lengths upon transverse 
 i earing bars, which receive both ends. The spaces between the bars are from 
 $ to an inch. The whole area of the grating should be about one-fourth the 
 area of the bottom surface of the vessel to be heated ; each foot of such grating is 
 adapted, according to Mr. Tredgold's calculations, to burn one-eighth of a bushel 
 of coal per hour. The same area will answer for either a slow or a quick fire, 
 but in a slow fire a greater depth of fuel is necessary ; and also for equal bulks 
 of any other kind of fuel, the same area will apply as for coals ; but it will be 
 obvious from this rule that the areas to produce equal quantities of steam 
 will be inversely as the power of the fuel. The damper is best situated at the 
 opening into the flue ; it should be supported in its slide by a counterbalance 
 weight, and its action be rendered easy and certain. The door should be made 
 to shut as close as possible ; but there is a difficulty in keeping it so, when 
 exposed much to the action of the fire ; they are best defended by making 
 them double, with a hollow space for air between them. Mr. Atkinson's mode 
 of constructing them is good ; he rivets on the inside a hollow cast-iron box, 
 which just fits the doorway ; the depth of the sides of the box so strengthens 
 the door as to prevent its warping, while the hollow space of confined air 
 prevents the escape of heat. A sliding door, balanced by a weight, in the 
 manner of a sash window, has many advantages ; it is more easily opened and 
 shut; is out of the way when open, and shuts close : when any thing 'is to be 
 done at the fire, a smaller opening suffices. 
 
 Delasmes Furnace. The invention of a mode of constructing furnaces cal- 
 culated to burn all the smoke given out by the fuel, is usually attributed to our 
 celebrated countryman, Mr. James Watt; but it appears from the volume of the 
 Academy of Sciences, at Paris, for 1699, that some successful experiments 
 were made by M. de la Hire, which had reference to an invention of many 
 years previous date, by Uelasme, a French engineer. The latter, we are told, 
 exhibited his furnace for consuming its own smoke at the fair of St. Germain, 
 in the year 1685. The fire-place of Delasme consisted of a long tube, 
 bent into the form of a syphon, and inverted, the longest leg of which formed a. 
 chimney, and the shortest the furnace. The fuel was deposited on a grating 
 near the top of the shortest leg, being supplied from above. Soon after the 
 ignition of the fuel the heat was communicated to the longest leg or chimney, 
 and by that means a current of air was caused to pass downward through the 
 fuel, and under the grate, where the smoke was consumed. 
 
 Watt's Patent. The earliest application in this country of apparatus for 
 consuming the dense smoke of furnaces, that we are acquainted with, is the 
 invention of Mr. Watt, in 1785, before alluded to. It is thus described by him in 
 his specification : " My newly improved methods of constructing furnaces or 
 fire-places, consist in causing the smoke or flame of the fresh fuel, in its way 
 4 n
 
 574 
 
 FURNACES. 
 
 to the flues or chimney, to pass, together with a current of fresh air, through, 
 over, or among fuel which has already ceased to smoke, or which is converted 
 into coke, charcoal, or cinders, and which is intensely hot; by which means 
 the smoke and grosser parts of the flame, by coming into close contact with, or 
 by being brought near unto, the said intensely hot fuel, and by being mixed 
 with the current of fresh or unburned air, are consumed or converted into heat, 
 or into pure flame, free from smoke. I put this in practice, first, by stopping 
 up every avenue or passage to the chimney or flues, except such as are left in 
 the interstices of the fuel, by placing the fresh fuel above or nearer to the 
 external air than that which is already converted into coke or charcoal ; and by 
 constructing the fire-places in such manner that the flame and the air which 
 animates the fire must pass downwards, or laterally, or horizontally, through 
 the burning fuel, and pass from the lower part or internal end or side of the 
 fire-place to the flues or chimney." Mr. Watt then gives an example and 
 a description of the application of this principle in his specification, which we 
 do not .here insert, as there have been some improved arrangements introduced 
 which we shall have occasion to notice elsewhere. The specification next 
 proceeds to state as follows : " In some cases, after the flame has passed through 
 the burning fuel, I cause it to pass through a very hot funnel, flue or oven, 
 before it comes to the bottom of the boiler, or to the part of the furnace where 
 it is proposed to melt metal, or perform any other office, by which means the 
 smoke is more effectually consumed. In other cases, I cause the flame to pass 
 immediately from the fire-place into the space under a boiler, or into the bed 
 of a melting or other furnace." We annex the inventor's example of this 
 arrangement of the furnace, as it is simpler than the former, and equally effec- 
 tive, a a represents a reverberatory furnace, for melting iron, of which b is the 
 
 flue ; e is the ash-pit, and/ a door thereto ; g is a hopper-like receptacle for 
 the fresh fuel, which gradually sinks down as it is consumed beneath ; about 
 the middle of this mass of fuel it is intensely hot, as it consists of coals and 
 coke that have ceased to smoke. At i is an opening or openings to admit fresh 
 air, and regulate the fire. At the opposite end of the furnace is another door, 
 to be used either for charging the furnace or stopping its operation, which is 
 effected by the counter current produced by the opening of the door. The fire 
 is first lighted upon the brick arcli /, and when well ignited, more fuel is 
 gradually added, until it is filled up to g, care being taken to leave proper 
 interstices for the air to pass, either among the fuel, or between the fuel and 
 the front wall; and as much air is admitted at the opening as can be done, 
 without causing the smoke to ascend perpendicularly from g, which it would 
 do if too much be so admitted. " Occasionally the opening at g is closed with
 
 FURNACES. 
 
 a cover, to cause the air to enter wholly or partially at t." By this addition, il 
 will be noticed, Mr. Watt first applied the closed hopper, now so much ueed 
 in the feeding of furnaces. 
 
 The following figure exhibits another admirable contrivance of Mr. Watt's, 
 which many succeeding inventors have claimed as their own, as well as that piar 
 
 already described. Mr. Watt observes, "In some cases I place the fresh fuel on 
 a grate, as usual, as at a, and beyond that grate, at or near the place where the 
 flame passes into the flues or chimneys, I place another smaller grate b, on 
 which I maintain a fire of charcoal, coke, or coals, which have been previously 
 burned, until they have ceased to smoke, which by giving intense heat, and 
 admitting some fresh air, consumes the smoke of the last fire." 
 
 Thompsons Patent. Mr. Thompson had a patent in 1796 for a furnace on 
 the same principle as Watt's, but it was a less deviation from the ordinary con- 
 struction. The fire-bars were made about jjne third longer than usual, and at 
 two-thirds of their length from the front a low arch was thrown across the 
 fire-place, under which the smoke rushed from the fore part of the fire, and 
 was thus impelled through some intensely heated coked fuel, lying under and 
 beyond the arch upon the bars, and was thereby consumed. By the manage- 
 ment of a good stoker, this fire-place appears to us calculated to answer welL 
 
 ftoberton's Patent. In 1801 Messrs. Roberton, of Glasgow, patented some 
 improvements upon Mr. Watt's plans, which rendered the apparatus more com- 
 plete and convenient. To these gentlemen, indeed, is usually attributed the 
 first successful application of the principle patented by Watt, of burning the 
 smoke owing, we are inclined to believe, to tha indifference of the public 
 in the early part of Mr. Watt's career to the nuisance of dense smoke ; as, 
 from the comparatively small number of engines at that time, the adoption of 
 means to burn the smoke was not so much sought after. Joined to this cir- 
 cumstance may be reckoned the unskilful manner in which bricklayers, pre- 
 tending to an adequate knowledge of the subject, executed the work ; which 
 caused the principle to get into disrepute, rather than the bungling attempts to 
 carry it into effect. It was, in consequence, given in evidence, by numerous 
 witnesses before a committee of the House of Commons, that more coals were 
 consumed by burning the smoke than allowing it to pass off unconsumed ! in other 
 words, that inflamed gas afforded less heat than cold smoke. The probability 
 is, that more air was admitted than was requisite to supply the necessary 
 quantity of oxygen to the carbonaceous mutter, and that in consequence of such
 
 576 FURNACES. 
 
 management, the temperature of the furnace or of the boiler was reduced, 
 requiring an additional quantity of fuel to get up the requisite heat. 
 
 Sheffield's Patent. In the year 1812, Mr. William Evetts, of Sheffield, took 
 out a patent for improved reverberatory furnaces for melting metals, in which 
 he introduced what he termed an air conductor, for the purpose of conveying a 
 stream of pure air upon the surfaces of the metallic substances under reduc- 
 tion. This air conductor consisted of a vertical passage or tube, made in the 
 bridge or wall of brickwork at the back of the furnace, the lower end of which 
 opened into the ash pit, where it was widened, and the size of the aperture 
 regulated by a valve, which valve was operated upon by a long rod passing 
 through the front enclosure of the ash pit ; the upper extremity of the air tube 
 or passage did not pass vertically through the bridge, but had a horizontal turn 
 given to it, by which the jet was thrown upon the substances under operation, 
 or against the current of heated vapours, before they passed over the bridge ; 
 and this minor stream of fresh air was found to impart sufficient oxygen to the 
 carbonaceous matter of the smoke, and burn it. 
 
 Legislative Enactment. The annoyance and pernicious effects experienced by 
 the public from a sooty atmosphere, drew the attention of the legislature to the 
 subject, and a Select Committee of the House of Commons was appointed, in 
 1819, "to inquire how far it might be practicable to compel persons using 
 steam engines and furnaces in their different works, to erect them in a manner 
 less prejudicial to public health and comfort ; and to report their observations 
 thereon to the House.'' The committee having ascertained and reported to the 
 House that the reduction of smoke from furnaces might be practically accom- 
 plished, a bill to embrace that object was brought into the House and passed ; 
 it was ,-ntitled " An Act for giving greater facility in the prosecution and 
 abatement of nuisances arising from furnaces used in the working of steam- 
 engines:"' to commence Sept. 1, 1821. Among its enactions are the follow- 
 ing; "That it shall and may be lawful for the court before whom any such 
 indictment shall be tried, in addition to the judgment pronounced by the said 
 court, in case of conviction, to award such costs as may be deemed proper and 
 reasonable to the prosecutor or prosecutors, to be paid by the party or parties 
 so convicted." It was also enacted " That if it shall appear to the court before 
 which any such indictment shall be tried, that the grievance may be remedied 
 by altering the construction of the furnace, or any other part of the premises 
 of the party or parties so indicted, it shall be lawful to the court, without the 
 consent of the prosecutor, to make such order touching the premises as shall 
 be, by the said court, thought expedient for preventing the nuisance in future, 
 before passing final sentence upon "the defendant, or defendants, so convicted." 
 Gregson s Patent. Mr. Joseph Gregson, who was one of the gentlemen 
 examined before the Committee of the House, gave it as his opinion, that the 
 principal causes of the nuisance were, the putting on the fire too much crude 
 fuel at a time, and the chimney being in general too low. Mr. Gregson had a 
 patent for a plan of a furnace for consuming the smoke, the principle of which, 
 he stated, consisted, " first, in causing all the smoke, after it has arisen from the 
 fire, to return into the heat of the fire before it enters the flue or chimney, and 
 so be consumed ; secondly, in putting on no more fuel at any one time, than 
 the smoke of which can be consumed, and that without opening the door for 
 the purpose ; thirdly, in supplying the fire with a current of air to coun- 
 teract the effect of those winds that operate against the draft. The engraving in 
 the next page represents a vertical section of the apparatus. The fire-place G and 
 the feeding-door F are made as usual ; the smoke passes over the bridge D, 
 under which is an aperture, where an intense heat is produced, which inflames 
 the smoke in the descending flue by means of a supply of air through the 
 aperture C ; it then passes into the flue and the chimney, A, formed in the 
 usual manner. Z Z is an air shaft and drain to supply the fire with air through 
 a valve situated under the fire-place. It may be deserving of remark, that 
 the objects aimed at by Mr. Gregson in this arrangement would be considerably 
 promoted, by making the partition between the ascending and descending flues, 
 A and Z, of iron or copper, instead of brick ; and that an economy of fuel
 
 FURNACES 
 
 577 
 
 would result from the partial exchange of temperatures between the opposite 
 currents. But in thus abstracting the waste heat through the medium of good 
 conducting substances, a sufficient temperature must be left in the ascending 
 column to maintain the draft. 
 
 Losh's Patent. The entire specification of this gentleman's improvements 
 is inserted in the Repertory of Arts, and is deserving of perusal by those who 
 are interested in the subject ; the leading arrangements may however be un- 
 derstood by the following extract. The plan arranges " the furnace- 
 bars as near as possible under the middle of the boiler, or other vessel's bottom, 
 and to have the aperture or apertures for the escape of the rarefied air and 
 smoke above the door through which the fuel is put in, so that the heated air 
 and gases, by their expansive force and diminished specific gravity, shall pre- 
 vent the cold air of the atmosphere from penetrating beneath the bottom of the 
 boiler, in order that the cold air admitted at the door where the fuel is intro- 
 duced, shall, in its passage to the chimney, have no tendency to mix with the 
 1 eated gases nnti 1 after they have ceased to act upon such parts of the boiler 
 as are required to be submitted to their action alone. A division of cast plates, 
 extending from the ends of the bars next to the door, separates the grate-room 
 from the ash-hole and air-duct, and prevents any air from passing into the 
 grate-room which does not pass through the ignited fuel." Another peculiarity 
 in Mr. Losh's arrangements, consists in the employment of two fires, which we 
 will call A and B, with a wall between them, which supports the middle of the 
 boiler across its width. Each of these fires has a common flue, which termi- 
 nates in the chimney, and they communicate with each other by means of an 
 open arch under the partition wall ; each fire is supplied alternately with fuel ; 
 and the arrangement of the dampers is such, that the gas from the fresh fuel 
 iu A shall be compelled to descend, pass under the arch of the division wall, 
 and through the grate bars of the fire B, along with the fresh air that supplies 
 it where the smoke is consumed ; the current of heated air from both, thus
 
 578 
 
 FURNACES. 
 
 United, takes its course around the flue into the chimney. By the time that 
 the fuel in A has burned bright, that in B requires replenishing ; the dampers 
 are then reversed, which removes the current to the chimney ; then the gas 
 from the fresh fuel in B descends under the beforeinentioned arch up through 
 the grate bars of A, along with the fresh air of supply, and being there ignited, 
 is conducted to the chimney. In this alternate manner the operation of feeding 
 is continually repeated. 
 
 Steel's Improvement. Mr. Steel's fire-place was of a circular form, and made 
 to revolve on an upright axis by a gear connected to its lowest extremity ; 
 motion was also given, at the same time, to a fluted roller, turning in bearings 
 underneath a hopper filled with coals ; this roller broke or crushed the coals to 
 a sufficiently small size, and projected them down an inclined shoot, which dis- 
 tributed them over the circular grate as it turned round, as represented in the 
 annexed section, o o o shows a high pressure tubular boiler, set in masonry ; 
 
 i i is the ring or rim which surrounds the circular grate, made somewhat deeper 
 than the bars, and turning round in an iron trough 3 3, filled with sand, which 
 prevents the air from passing by the rim ; N is a metallic plate to receive the 
 ashes which fall ; D a toothed wheel, turned by any convenient means in the 
 step at C, and in a cross bar at L above. At F is the receptacle for the furl ; 
 E the breaking and supplying roller, which projects them down the inclined 
 shoot G R, into the revolving grate, which, continually presenting fresh surfaces.
 
 FURNACES. 579 
 
 the fuel is pretty uniformly distributed thereon. The grate is made to turn in 
 such a direction that the fresh coals are, immediately after they are deposited, 
 presented to the fire door contiguously situated, where, by the due admission of 
 air, vivid combustion immediately takes place, and the fresh fuel is in bright 
 ignition before more is thrown on the same part, the revolution of the grate 
 being low. 
 
 Bruntoris Patents. Mr. Brunton had a patent in 1819 for a revolving fire- 
 grate of a similar kind ; but whether Mr. Steel's was antecedent to it (as would 
 appear from the dates given, together with the circumstances), we do not know. 
 Mr. Brunton has, however, the credit of carrying his apparatus into successful 
 use, and of having rendered it very complete. Among many judicious con- 
 trivances, may be noticed a revolving scraper, which gathered up the ashes as 
 they fell upon the ash plate. In the following year, 1820, Mr. Brunton took 
 out a second patent for improvements upon the former ; these chiefly con- 
 sisted in a mode of raising or lowering the furnace at pleasure, so as to diminish 
 or increase the heat of the boiler as required ; also in a new mode of feeding 
 the fire. The shaft of the circular fire-grate upon which it revolves, is made 
 to pass through a hole in a bearer of iron, built in the brickwork, and receives 
 its support at bottom upon another bearer of iron, which is capable of sliding 
 up and down in grooves, so as to elevate or depress the fire, by means of a rack 
 and pinion, acted upon by a lever or winch. Round the periphery of the cir- 
 cular grate is a double rim of sheet-iron, rising up three or four inches, the space 
 between being filled with sand, so that when the grate is raised, another ring of 
 iron, attached to the wall of the furnace, may fit into the groove and form a sand 
 valve, to prevent the passage of air, and check the transmission of heat. Two 
 or more passages, provided with sliding doors, are made through the brickwork, 
 for the purpose of admitting a current of air to the top of the fire, in order to 
 assist in igniting the smoke, if necessary. The fire feeder is shaped like a 
 hopper, placed over the feeding hole, and the delivery aperture at bottom is 
 capable of contraction or expansion, as may be required. Below this is a plate 
 of iron, placed in an inclined position, and suspended upon pivots for the pur- 
 pose of being agitated, in order to distribute the fuel equally upon the grate; 
 there is also a shovel upon rollers, moved by means of a rod and chain 
 actuated by the engine. By the very equal distribution of the coal upon the 
 grate, a thin fire and a sharp draft is maintained, owing to every piece of 
 coal upon the grate being successively exposed to a current of the fire 
 passing constantly in one direction across the grate; the continual dropping 
 of the coal in minute quantities, instead of opening the door to charge as 
 usual, produces a great advantage in convenience, besides a saving of fuel. 
 The introduction of the coal is likewise completely governed by the steam 
 generated, so as to admit no more for combustion than is actually needed for 
 the due performance of the work of the engine. The whole apparatus acted 
 independently of the skill or of the carelessness of the fireman. Small coal, 
 of greatly inferior cost to that generally used, answers well with a furnace 
 of this kind, and thereby effects an important saving. A thin fire with a sharp 
 draft produces the maximum effect, because the greater the quantity of 
 oxygen brought into contact with the coal in combustion, the greater heat is 
 obtained. 
 
 Murray's Improvement. It has doubtless been observed by most of our 
 readers, that the very dense black smoke which issues from the chimneys of 
 steam engines and other furnaces, is not constant ; that it commences at the 
 time of putting on fresh fuel, and continues for a few minutes afterwards. At 
 this time the air finds its way through the fuel with less opposition, and the 
 evolution of dense smoke ceases until the next charge of coals. To supply the 
 requisite quantity of air to burn this black smoke, the late Mr. Murray (the 
 celebrated steam-engine manufacturer of Leeds), devised a very ingenious 
 machine. It is described in a letter addressed to the Editor of the London 
 Journal of Arts, dated February 15, 1821, wherein he observes, "The most 
 effectual method yet known for consuming smoke, is by the admission of a large 
 quantity of air to the hottest part of the tire, at the time the smoke is bursting
 
 580 FURNACES. 
 
 from the recent charging of coal. The necessary quantity of air to be admitted 
 ought not to be less than may pass through an aperture of four square inches 
 for each horse power that the boiler or fire is equal to ; this will consume the 
 smoke in from three to five minutes, according to the quantity and quality of 
 coal put on at each time, the times of charging being not more than five 
 times in an hour, nor less than three. The air rushing into the flue is the 
 moving force for giving motion to my new regulating machine, which continues 
 in motion during the consumption of smoke, but no longer." The machine 
 may be thus described, without the drawings given in the work before alluded 
 to. It consists of a light fan-wheel, from which proceeds a capacious tube, 
 communicating with the fire-place, and containing a turning valve, which opens 
 or closes the passage. When the fire-door is opened to take in fresh fuel, it 
 discharges (by means of a slip catch connected to the door) a pall, which sets 
 at liberty a suspended weight ; the descent of this, turns a ratchet wheel, 
 which places the turn-valve edgeways against the current, and leaves a free 
 communication between the atmosphere and the upper side of the fire. In this 
 state of rest the machine remains until the fire-door is shut, when the current 
 of air enters the machine, turning rapidly the fan-wheel, which having a pinion 
 on its axis of only one tooth, gives a slight motion to a light spur-wheel of 
 many teeth ; this wheel, through the medium of a catch-rod, and other simple 
 mechanism, gradually closes the turn-valve. The smoke having been consumed, 
 the fire continues burning until a fresh supply of fuel is necessary, when the 
 fire-door is opened, which puts the machine in a state for measuring off the 
 required quantity of air to be admitted to consume the smoke of each charge ; 
 the operation is then repeated. 
 
 Pritchard's Patent. Mr. William Pritchard took out a patent in 1821 for 
 the same object. He fixed a small cylinder in some convenient place con- 
 tiguous to the furnace, with an air-tight piston to rise and fall within it. A t 
 the upper end of the piston-rod a chain is attached, which passes over pulleys, 
 and its reverse end is connected to the top of the fire door or air-flue doors, 
 by means of which connexion, when the fire door is raised, the piston descends 
 in the cylinder by its own gravity ; and when the fire door is shut down, the 
 piston rises. On the outside of the cylinder is placed a branch pipe or channel, 
 through which the air passes (as the piston ascends or descends) from the upper 
 to the lower part of the cylinder, and vice versa. In the middle of this branch 
 pipe is a valve or stop-cock, which may be so adjusted as to suffer the air to 
 pass slowly, or by a very small stream, through the channel; by this means 
 the ascent of the piston is retarded, and hence the entire descent, or closing of 
 the fire doors, or air-flues, does not take place, until the air is nearly all expelled 
 from the upper part of the cylinder, allowing time for the requisite quantity of 
 atmospheric air to pass into the air-flues over the fire, for the purpose of con- 
 suming the smoke ; the time of closing the doors is regulated, as above, by 
 the valve or stop-cock in the branch pipe. London Journal of Arts. 
 
 Stanley's Patent. This invention, which we have seen repeatedly and suc- 
 cessfully applied, forms a distinct appendage to the front of the furnace. At 
 the upper part of the apparatus is a hopper, containing a supply of small coals 
 adequate to an hour or two's consumption. Through an aperture at the lower 
 extremity of this vessel, the coals drop between two grooved rollers, which 
 revolve in opposite directions, and break those which are too large to pass 
 without reduction between them ; they then fall upon a flat plate of iron, whence 
 they are continually projected by the arms of a kind of revolving fanner, which 
 scatters them evenly over the burning fuel on the grate, where it lies in a thin 
 bed, in order that the air may pass upward through them the more easily. The 
 apparatus is, however, usually adjusted to throw a larger proportion of the fuel 
 near the fire bridge, so that it may lie there heaped up or in a thicker stratum. 
 in order that the small quantity f smoke arising from the fresh fuel in front 
 may be consumed in passing over the bridge. 
 
 Chapman's Furnace. In 1824 Mr. Chapman received a reward from the 
 Society of Arts for a different mode of introducing air into the furnace. He 
 casts the grate bars hollow from end to end, so that they form a series of
 
 FURNACES. 
 
 581 
 
 parallel tubes, which open into two boxes, one placed in front, and t!ie other 
 behind the grate. In the front box, directly underneath the fire door, there is 
 a register to open and shut to any extent, at pleasure ; the other end is con- 
 nected with the brickwork, directly under the fire bridge, which fire bridge is 
 made double, with a small interval between, about one inch, the interval to go 
 across the furnace from side to side, and rather to incline forward, or towards 
 the fire door, so as to meet and reverberate the smoke on to the ignited fuel in 
 the grate, which causes it to inflame and become a sheet of bright fire under 
 the bottom of the boiler. By this arrangement it will be perceived, that if the 
 front register is open, or partially so, there will be a great draft of air through 
 it, along the interior of the grate bars, thence into the flue of the fire bridge, 
 and out of the orifice at top, which air will be heated in its passage through the 
 bars before it comes in contact with the smoke, when it will juve out its oxygen, 
 and cause it to inflame. Mr. Chapman's mode of supplying the coals to the 
 furnace is also simple and excellent, which will be explained with reference to 
 the subjoined engraving. Fig. 1 is a section of the furnace, with a boiler 
 
 Fig. \ 
 
 fixed therein ; and Fig. 2 a view of the hollow bars as they open into the box '. 
 a is the boiler ; b the fire-place ; e the feeding hopper, with a cover d, and its 
 type or turning bottom, having a lever or counterpoise e, by means of which 
 the coals are delivered into the fire-place ; / is a rake, by means of which the 
 half-burnt coals are pushed forward previously to letting in a fresh charge; g a 
 slit below the funiace door, through which the state of the fire is seen ; i i is an 
 air-tight box, into the back of which the bars open, and in front of which is a 
 register for the admission of air ; k one of the hollow bars, the whole of which 
 are shown in Fig. 2 as they open into the box i above mentioned ; / a flue in 
 the fire bridge, through which the air having passed into the box i, and thence 
 4 E
 
 582 
 
 FURNACES. 
 
 through the hollow bars k, enters into the furnace, and consumes the smoke. 
 Hollow bars are said to be more durable than solid. 
 
 Gilbertson's Patent.This differs but little from the former. Mr. Gilbertson's 
 plan is to heat the air by causing it to pass through " hollow plates" fixed to 
 the sides of the furnace, and thence into a cavity at the back of the fire, where 
 it comes in contact with the smoke, and causes it to be ignited. 
 
 Chemical Furnaces. The forms of furnaces employed by experimental as 
 well as practical chemists are extremely diversified. Those which are employed 
 in manufactories ; in metallurgical, distillatory, and other operations on the great 
 scale, will be found under the denomination of the article produced, such as 
 IRON, GAS, ZINC, &c. In this place, therefore, we shall confine our notice to 
 those portable furnaces which are generally employed by British chemists. 
 
 Reverberatary Furnace. Annexed is the common reverberatory furnace. At 
 rt a is the ash pit and fire-place ; bb the body of the furnace ; c c the dome or 
 
 reverberating roof; d the chimney ; e door of the ash pit ; / door of the fire- 
 place ; a handles of the body ; h aperture to receive the head of the retort ; i 
 handles of .the dome ; k receiver ; I stand of the receiver ; m retort, represented 
 in the body in dotted lines. 
 
 dikin's Portable Blast Furnace is represented in the figure on the following 
 page , it is composed of three parts, all made out of the common thin black 
 lead melting pots, sold in London for the use of the goldsmith. The lower 
 piece c, Fig. 1, is the bottom of one of these pots, cut off so low as only to 
 leave a cavity of about an inch deep, and ground smooth above and below. 
 The outside diameter, over the top, is five inches and a half. The middle-piece, 
 or fire-place a, is a larger portion of a similar pot, with a cavity about six 
 inches deep, and measuring seven inches and a half over the top outside 
 diameter, and perforated with six blast holes at the bottom. These two pots 
 are all that are essentially necessary to the furnace for most operations ; but 
 when it is wished to heap up fuel above the top of a crucible contained, and 
 especially to protect the eyes from the intolerable glare of the fire when in full 
 height, an upper pot b is added, of the same dimensions as the middle one, and 
 with a large opening in the side, cut to allow the exit of the smoke and flame. 
 It has also an iron stem with a wooden handle (an old chisel answers the pur- 
 pose very well,) for removing it occasionally. The bellows, which are double 
 (d), are firmly fixed by a little contrivance, which will take off and on, to
 
 FUSEE. 
 
 583 
 
 a heavy stool, an represented ; the nozle is received into a hole in the pot c, 
 which conducts the blast into its cavity. No luting is necessary in using this 
 furnace, so that it may be set up and taken down immediately. Coke, or 
 
 common cinders, answer well for fuel ; and the heat which this little furnace 
 affords is so intense, that its power was first discovered by the fusion of a thick 
 piece of cast-iron. 
 
 Chevenix's Wind Furnace is represented in the following engraving. It is, in 
 some respects, Dr. Ure observes, to be preferred to the usual form. The 
 sides, instead of being perpendicular, are inclined, so that the hollow space is 
 pyramidical. At the bottom the opening 
 is thirteen inches square, and at the top 
 eight. The perpendicular height is seven- 
 teen inches ; the form appears to unite the 
 following advantages : 1st, A great surface 
 is exposed to the air, which, having an easy 
 entrance, rushes through the fuel with 
 great rapidity ; 2d, The inclined sides act 
 in some measure as reverberating surfaces ; 
 and 3d, The fuel falls of itself, and is 
 always in close contact with the crucible 
 placed near the grate. The late Dr. Ken- 
 nedy, of Edinburgh, whose opinion on this 
 subject claims the greatest weight, found 
 that the strongest heat in our common wind furnaces was within two or three 
 inches of the grate : this, therefore, is the most advantageous position for the 
 crucible, and still more so when we can keep it surrounded with fuel. It is 
 inconvenient and dangerous for the crucible to stir the fire often to make the 
 fuel fall ; and the pyramidal form renders this unnecessary. It is also more 
 easy to avoid a sudden bend in the chimney, by the upper part of the furnace 
 advancing in this construction. 
 
 Lamp Furnaces. The flame of an argand lamp is very often employed for 
 chemical purposes, and it is very convenient. To a vertical rod is fitted to slide 
 thereon a number of metallic rings projecting from it horizontally, which 
 become the supports to retorts, or other vessels suspended over the flame of 
 the lamp. 
 
 Domestic Furnaces, such as stoves, grates, ranges, &c. are described under 
 the article FIRE-PLACE. 
 
 FUSEE, in Clockwork, the conical barrel drawn by the spring, and about 
 which the chain or cord is wound ; for the use of which see HOROLOGY.
 
 5S4 GALLON. 
 
 FUSION, in Chemistry, the application of heat to produce the dense fluid 
 state of bodies. 
 
 FUSTIAN, in Commerce, a kind of cotton stuff, which seems as if it were 
 whaled on one side. Right fustians should be made entirely of cotton ; but they 
 are frequently made with a warp of flax. 
 
 FUSTIC, OK YELLOW WOOD. This wood, the Moras tincloria, is a 
 native of the West Indies, and affords much colouring matter, which is very 
 permanent. The yellow given by fustic without any mordant is dull and 
 brownish, but stands well. The mordants employed with weld act upon fustic 
 in a similar manner, and by their means the colours are rendered more bright 
 and fixed. The difference between them is, that the yellow of fustic inclines 
 more to orange than that of weld ; and as it abounds more in colouring matter, 
 a less quantity will suffice. 
 
 G. 
 
 GALBANUM. A resinous and gummy juice that exudes from the Bubon 
 galbanum. The commercial article is in the state of white, yellow, and brownish 
 tears, unctuous to the touch, and softening between the fingers, and generally 
 full of bits of stalks, leaves, &c. of the plant ; it has a bitter acrid taste, and 
 strong smell. One pound of galbanum yields to alcohol nine and a half ounces 
 of resin, and to water about three ounces of gum. The peculiar smell and 
 taste of galbanum reside in an essential oil, six drachms of which are obtained 
 by distillation from one pound of the substance. 
 
 GALENA. The native sulphate of lead. 
 
 GALLEY, in Printing, a frame into which the compositor empties the lines 
 of type out of his composing stick, and in which he arranges and ties up the 
 whole matter of the page when it is completed. The galley is an oblong square 
 board, with a ledge on one of its sides and one of its ends, to support the type 
 in drawing it up into a compact mass ; it has sometimes a groove to admit a 
 false bottom, called a galley- slice. 
 
 GALLEY. A kind of low, flat-built vessel, furnished with a deck, and navi-" 
 gated with sails and oars ; chiefly used in the Mediterranean. This term is also 
 given to a light species of open boats employed in the river Thames, which is 
 rowed with six or eight pair of oars. 
 
 GALLIC ACID is found most abundantly in the vegetable substance galls, 
 whence it derives its name ; but most astringent vegetable matter contains it. 
 The simplest mode of obtaining it is probably that recommended by Mr. 
 Fiedler. An ounce of powdered galls is to be boiled in sixteen ounces of 
 water until reduced to eight, and then strained. Dissolve two ounces of alum 
 in water, precipitate the alumina by carbonate of potash ; and after edulcorating 
 it completely by repeated ablutions, add to it the decoction, frequently stirring 
 the mixture with a glass rod ; the m xt day filter the mixture ; wash the pre- 
 cipitate with warm water till this will no longer blacken sulphate of iron ; mix 
 the washings with the filtered liquor, evaporate, and the gallic acid will be ob- 
 tained in fine needle crystals. The gallic acid, placed on a red-hot iron, burns 
 with flame, and emits an aromatic smell like that of benzoic acid. It is soluble 
 in twenty parts of cold water, and in three parts at a boiling heat. It is more 
 soluble in alcohol, which takes up an equal weight if heated, and one-fourth of 
 Ishi 
 
 its weight cold. The distinguishing characteristic of gallic acid is its great 
 affinity for metallic oxides, so as, when combined with tannin, to take them 
 from the powerful acids. The more readily the metallic oxides part with their 
 oxygen, the more they are alterable by the gallic acid. To a solution of gold 
 it imparts a green hue ; mercury it precipitates of an orange yellow ; copper, 
 brown ; bismuth, a pale yellow ; lead, white ; and in iron, a black ; whence its 
 use in making ink, and in the operations of the dyer in making various shades 
 of black, and in improving or fixing other colours. 
 
 GALLON. An English measure of capacity, which, until recently, varied 
 considerably with the kind of goods measured by it ; thus
 
 GAS. 585 
 
 Tlie gallon wine measure contained 231 cubical inches. 
 Ditto beer measure, 282 
 
 Ditto dry measure, 268* 
 
 But by an Act of Parliament passed in 1824, it was altered on the 1st of May, 
 1825, to an uniform measure called the imperial standard gallon. By that act 
 it was determined to be such measure as "shall contain ten pounds avoirdupois 
 of distilled water, weighed in air at the temperature of 62 Fahr., and the 
 barometer at 30 inches ; and such measure is declared to be the " Imperial 
 Standard Gallon," and shall be the unit and only standard measure of capacity to 
 be used, as well for wine, beer, ale, spirits, and all sorts of liquids, as for dry goods 
 not measured by heap measure ; and that all other measures shall be taken in 
 parts or multiples of the said imperial standard gallon, the quart being the 
 fourth part of such gallon, and the pint one-eighth part; two such gallons 
 making a peck, eight such gallons a bushel, and eight such bushels a quarter of 
 corn, or other dry goods not measured by heaped measure. 
 
 GALLS. The protuberances on various kinds of trees, supposed to originate 
 in the puncture of an insect. Some are hard, and are therefore called nut- 
 galls ; others soft, which are called berry, or apple-galls. The best are the nut- 
 galls of the oak; and the most esteemed of this species are brought from 
 Aleppo. They are not smooth on the surface, but tubercular, small and heavy, 
 and should have a bluish or blackish tinge. By infusing 500 grains of Aleppo 
 grains broken into small pieces in distilled water, Sir H. Davy obtained, by 
 evaporating the fluid, 185 grains of solid matter, which, on analysis, gave 130 of 
 tannin; 12 mucilage and insoluble matter; gallic acid, with a little extractive 
 matter, 31 ; remainder calcareous earth and saline matter, 12. The extensive 
 use of galls in dying, tanning, and in making ink, is well known, for which see 
 the separate articles under their initial letters. 
 
 GALL-STONES. The calculous concretions occasionally found in the 
 gall-bladders of animals. Those found in oxen, used by painters, are of this 
 nature. 
 
 GALVANISM. A species of electricity excited, not by friction, but by 
 establishing a communication between two different metals through the medium 
 of a liquid. See CHEMISTRY. 
 
 GAMBOGE. A substance obtained from the Stalagmites cambogioides, a 
 tree that grows wild in the East Indies, from which it is had by wounding the 
 shoots. It is brought here in large cakes, which are yellow, opaque, and 
 brittle. With water it forms a yellow, turbid liquid, used in painting. In alcohol 
 it is completely dissolved. If taken internally, it operates violently as a 
 cathartic. 
 
 GARLIC. The root of the Allium. This root has been found, by chemical 
 analysis, to consist of albumen, mucilage, fibrous matter, and water. 
 
 GARNET, in Mineralogy, a species of the flint genus, of which there are 
 two sub-species, viz. the precious and common. The precious, or oriental, is 
 red, but of various shades ; it occurs most commonly crystallized, either as a 
 dodecadron, or as a double eight-sided pyramid. Garnets are found in almost 
 every country where primitive rocks exist. Switzerland and Bohemia are the 
 two countries which furnish them in the most abundance. 
 
 GAS. The name given to all elastic aeriform fluids (except the atmospheric 
 air) which retain that state at all ordinary temperatures and pressures. For a 
 long time the gases were supposed to be permanently elastic ; but about the 
 year 1823 Sir Humphrey Davy, assisted by Mr. Faraday, succeeded in reducing 
 several of them to a liquid state by subjecting them to great pressure, and an 
 extreme degree of cold ; upon removing the pressure, and restoring the natural 
 temperature, the liquids became again converted into gases. This discovery 
 induced these gentlemen to institute a series of experiments with the view of 
 ascertaining whether the vapours arising from the gases thus liquefied might not 
 be rendered available as mechanical agents in lieu of steam, and be applicable 
 to the same purposes. These experiments were detailed in a paper read at the 
 Royal Institution, and from this paper we select the following results: 
 
 Sulphuretted Hydrogen, which condenses readily at 3 Fahr. under a pressure
 
 GAS LIGHTING. 
 
 equal to the elastic force of an atmosphere compressed to one-fourteenth, had 
 its elastic force increased to that of an atmosphere compressed to one-seven- 
 teenth by an addition of 47 of temperature. Liquid muriatic acid at 3 Fahr. 
 exerted an elastic force of 20 atmospheres ; by an increase of 22 of tempera- 
 ture, its force was increased to 25 atmospheres ; and by a farther addition of 
 26, its force became equal to 40 atmospheres. Carbonic acid at 12 Fahr. 
 exerted a force of 20 atmospheres ; and at 32 Fahr. its pressure was equal to 
 36 atmospheres, making an increase of pressure equal to 13 atmospheres by 
 an increase of 20 of temperature ; and this immense force of 36 atmospheres 
 being exerted at the freezing point of water. From the above experiments, it 
 will be seen that great accessions of force are obtained by very slight additions 
 of heat; and Sir Humphrey observes, in the Memoir, that "if future experi- 
 ments should realize the views here developed, the mere difference of tempera- 
 ture betwixt sunshine and shade, and air and water, will be sufficient to 
 produce results that have hitherto been obtained only by a great expenditure 
 of fuel." Upon this subject Mr. Tredgold, in his excellent Treatise on the 
 Steam Engine, observes, " I think it will be found that two other circumstances 
 should be considered in estimating the fitness of compressed gases as me- 
 chanical agents. First, the distance through which the force will act ; for if 
 this distance of its action be less in the same proportion as its force is increased 
 by compression, no advantage will be gained ; the power of a mechanical agent 
 being jointly as its force, and the space through which that force acts. 
 Secondly, the quantity of heat required to produce the change of temperature, 
 is also to be considered ; for if the mechanical power requires as great an 
 expenditure of heat as common steam, no advantage will be gained ; in fact, 
 the only prospect they afford of being useful, is through lessening the extent of 
 the surface to be heated." Mr. Tredgold then gives the following Table of the 
 gases liquefied by Mr. Faraday, with their densities as far as can be ascer- 
 tained, and with a column to show their mechanical power as compared with 
 steam, according to the spaces through which they act. from which it will be 
 seen that in effect they are all inferior to the latter. The quantity of fuel requi- 
 site for their vaporization is not known. 
 
 
 Spec. Grav. 
 Air 1. 
 
 Spec. Grav. 
 of Liquid, 
 Water 1. 
 
 Tempera- 
 ture. 
 
 Pressure in 
 
 Atmosphere 
 
 
 Carbonic acid gas . . 
 Sulphuric acid gas . . ' 
 Sulphur, hydrogen gas . 
 Euchlorine gas . . . 
 Nitrous oxide .... 
 
 1.527 
 2.777 
 1.192 
 2365 
 1.527 
 1.818 
 
 1.42 
 .9 
 
 .9 
 
 32 
 45 
 50 
 
 45 
 45 
 
 36 
 2 
 17 
 
 50 
 3,6 
 
 42fi 
 530 
 
 395 
 
 Ammonia 
 Muriatic acid gas . . . 
 Chlorine 
 Steam of water . ". . 
 
 .596 
 1.285 
 2.496 
 .48 
 
 .76 
 
 1.33 
 1.000 
 
 50 
 50 
 50 
 212 
 
 6.5 
 40 
 4 
 1. 
 
 1057 
 
 440 
 1711 
 
 GAS LIGHTING. The art of procuring and applying to the purpose of 
 illumination the inflammable gases evolved by animal and vegetable matter 
 when exposed in close vessels to a high temperature. This important and 
 highly beneficial invention originated in the researches of modern chemists; 
 but a long period elapsed between the scientific discovery of the facts upon 
 which the process is founded, and their successful application to practical pur- 
 poses. The fact that a permanently elastic and inflammable seriform fluid is 
 evolved from pit coal during its destructive distillation, appears to have been first 
 ascertained experimentally by the Rev. Dr. Clayton, whose account of his dis- 
 covery was published in the Transactions of the Royal Society, Vol. XLL, for 
 the year 1739. Dr. Hales subsequently made experiments on pit coal, and 
 found that, when distilled in close vessels, nearly one-third of the weight of coa!
 
 GAS LIGHTING. 587 
 
 passed off in inflammable vapour. Further experiments were made by Dr 
 Watson, Bishop of Llandaff, in 1767; but no practical application appears to 
 have been made of these discoveries for a long period. The merit of such 
 application appears to belong to Mr. Murdock, who, in 1792, commenced a 
 series of experiments at Redruth, in Cornwall, upon the quantity and quality 
 of the gases contained in different substances, as coal, peat, and wood ; in the 
 course of which experiments it occuried to him, that, by confining and con- 
 ducting the gas in tubes, it might be employed as an economical substitute for 
 lamps and candles. The distillation was performed in iron retorts, and the gas 
 conducted through tinned iron and copper tubes to the distance of seventy feet. 
 At this termination, as well as at the intermediate points, the gas was set fire 
 to as it issued through apertures of different diameters and forms, purposely 
 varied to ascertain which would answer best ; amongst these forms were the 
 argand burner and the cockspur burner, which are the two most generally 
 employed at the present day. Bags of leather and of varnished silk, and vessels 
 of tinned iron, were also filled with the gas, which was set fire to and carried 
 from room to room, in order to ascertain its applicability as a movable light. 
 Mr. Murdock's constant occupations prevented his pursuing the subject further 
 until 1797, when he renewed his experiments upon coal and peat, at Old Cum- 
 nock, in Ayrshire. In 1798 he constructed an apparatus for lighting the works 
 of Messrs. Bolton and Watt, at Soho ; and in 1802, on the occasion of the re- 
 joicings for the peace, the whole of the works were illuminated with gas. In 
 ] 803 and 1 804 Mr. Winsor made public exhibitions of the general nature of 
 gas lighting at the Lyceum Theatre, and proposed to light the public streets by 
 means of gas ; but the extravagance of his statements respecting the advan- 
 tages of the scheme were prejudicial to the plan ; and although an experiment 
 was made by lighting up a portion of Pall Mall, it was soon abandoned, and 
 the practice did not come into successful operation until the year 1813, when 
 the Chartered Gas Company erected their works at Peter-street, Westminster. 
 Since this period the practice of gas lighting has come into general use with 
 astonishing rapidity ; important improvements have been made in the various 
 processes connected with it, and gas is now extensively procured from numerous 
 substances beside pit coal, such as oil, tar, resin, &c. We shall now proceed 
 to give a general view of the subject, by describing the process of gas making 
 as usually conducted at the Coal Gas Works. 
 
 A number of cast-iron vessels, called retorts, generally of a cylindrical or of 
 an oval shape, and set in a brick furnace, are heated to redness, and then about 
 half filled with coal, and the mouths of the retorts closed and carefully luted. 
 In a short time the decomposition of the coal commences, and the volatile parts 
 separating from the fixed parts, are conducted by bent tubes called dip pipes, 
 into a large horizontal cast-iron tube called the hydraulic main, from its being 
 half full of water, into which the ends of the dip pipes are immersed, so that 
 the gas and vapours may be forced to pass through the water, which condenses 
 a portion of the tar and ammonia, whilst the gas ascends to the upper part of 
 the hydraulic main ; from this it passes by a pipe to the condenser, which 
 consists of a number of metallic pipes or compartments, surrounded by cold 
 water. In its passage through this vessel the gas becomes so much cooled as 
 to occasion the remaining portion of the tar and ammonia to be condensed, 
 which latter products pass into the tar cistern, whilst the gas passes into the 
 purifier, where it undergoes a process by which the carburetted hydrogen, which 
 is the gas employed for illumination, is freed from the sulphuretted hydrogen, 
 and carbonic acid evolved with it ; it then passes through the gas meter, in 
 order that the quantity may be registered on its way to the gas holder (or 
 gasometer, as it is improperly called), in which it is stirred up till wanted for 
 use, being conveyed in any required direction by pipes connected with the 
 gasometer. For the further elucidation of the subject, a general view of the 
 apparatus, with explanatory remarks, will be found on the following page, a 
 Fig 1. in the following engraving, represents a portion of a bench of retorts, in 
 which five elliptical retorts bb are exhibited, set in an oven, the mouth of which 
 'K covered by the cast-iron plate c, having apertures for the introduction of the
 
 588 
 
 GAS LIGHTING. 
 
 retorts, which are secured to the oven plate by flanges at their mouths, and the 
 other extremity is supported by a cast-iron stud projecting from it and resting 
 
 a cast-irou socket at the back of the oven. This plan of setting retort,
 
 GAS LIGHTING. 589 
 
 which affords great facilities in their removal when burnt-out, and in replacing 
 them with others, was first employed at the Westminster Gas Works, and is 
 the invention of Mr. Malam, of that establishment. The fires for heating the 
 retorts are not seen, being situated at the back of the oven, by which arrange- 
 ment the annoyance of the heat to the men who charge the retorts from the 
 elevated platform d, is considerably diminished ; the coke, as it is raked from 
 the retorts, falls through apertures e e in the platform, to which apertures are 
 fitted trap doors, or movable gratings ; // are the dip pipes, by which the gas 
 enters the hydraulic main g, a transverse section of which, upon a larger scale, 
 is shown in Fig. 2 ; h is the pipe by which the gas is conveyed from the 
 hydraulic main to the condenser, to be divested of the tar and ammoniacal 
 liquor. Various arrangements have been employed for this purpose ; that 
 shown in the engraving, and which we believe to be generally preferred, is the 
 invention of Mr. Perks, and consists of a close vessel Ic. divided into compart- 
 ments 1 1, each communicating with the adjacent one by parallel rows of bent 
 pipes m m, which are surrounded by water contained in the tank n, erected upon 
 the top of k. The gas entering the condenser by the pipe h passes succes- 
 sively through the several rows of bent pipes until it arrives at the exit pipe o, 
 which conveys it to the purifier ; by which prolonged contact with a great extent 
 of cooling surface, the tar and ammoniacal liquor become condensed, and fall to 
 the bottom of the compartments 1 1, and from them are conveyed to the tar 
 vessel p, in which the tar, from its greater specific gravity, occupies the lower 
 portion, and is drawn off by the lower cock, whilst the ammonia, which lies 
 above it, is drawn off by the upper cock ; q represents the most approved con- 
 struction for a purifier when cream of lime is the material by which the car- 
 buretted hydrogen is freed from the sulphuretted hydrogen and carbonic acid, 
 with which it is still contaminated after leaving the condenser. In this arrange- 
 ment of the purifying vessels, three cylindrical vessels r r r are placed one over 
 another, and from the top of each descends a smaller cylinder sss, which does 
 not reach the bottom of the larger cylinder, and which has attached to its lower 
 end a broad flange or shelf. The larger cylinders are filled with cream of lime 
 to about one-half their depth, which is kept in constant agitation by broad vanes 
 1 1 attached to the spindle u, passing through stuffing boxes in the several 
 cylinders. The gas entering the lower small cylinder by the pipe o depresses 
 the liquid therein below the shelf, and then rises up through the fluid into the 
 upper part of the outer cylinder ; from whence it is conveyed by the bent pipe v 
 to the second interior cylinder, and from it, in a similar manner, to the third, from 
 which it escapes, as before described, to the outer cylinder, and from thence 
 passes by the pipe w to the gasholder, or gasometer x, as it is commonly 
 termed. The gasholder consists of a large outer cylindrical cast-iron vessel or 
 trunk y, nearly filled with water, in which is inverted another cylinder z of 
 sheet iron, a few inches less in diameter, and open at the bottom ; the inner is 
 usually suspended by a chain passing over pulleys, and having counterbalance 
 weights attached to them, so as to allow the vessel to rise easily by the upward 
 pressure of the gas upon its entering. For the purpose of suspending the inner 
 vessel, a heavy frame, or bridge, was formerly erected over the whole ; but a 
 much superior method is now generally employed ; in the centre of the vessel 
 z is a tube of about three feet diameter, through which rises a cast-iron pillar 
 2 to a plate, on the top of which are fixed the balance wheels, the weights 3 3 
 rising and falling within the pillar. From the gasholder the gas is conveyed 
 by the eduction pipe to the street mains, and from there, or from the various 
 service pipes branching from them, it is conveyed, by small wrought pipes, to 
 the street or private lamps. In order to regulate the flow of gas into the main, 
 at the junction of it with the eduction pipe is placed a regulating valve, and 
 from the main is supplied a lamp kept constantly burning, whilst an attendant, 
 by partially opening or closing the valve, maintains the flame of the lamp at the 
 proper height. 
 
 The engraving on the following page represents an improved description of 
 regulating valve, which has been introduced at the Bath Gas Works by Mr. 
 Eastwick, the engineer of that establishment. The valve consists of a circular 
 4 F
 
 590 
 
 GAS LIGHTING. 
 
 plate of metal, nine inches in diameter, sliding over the mouth of the main pipe 
 in a chamber ; the face of the index is a representation of the valve itself, so made 
 in order that the superintendent may know the precise position of the valve 
 at any time. The disc A is a thin plate of metal attached to a rod coming up 
 from the valve behind the index frame, in which there is a slit for the pin, 
 which carries the index, to pass. The portion of the circle B, which is un- 
 covered by the disc, represents the aperture or gasway into the main pipe. G 
 is a pressure gauge connected with the main on the gasometer side of the valve, 
 and T another pressure gauge, also connected with the main on the town side ; 
 there is a burner supplied from the town side of the valve placed before th, 
 
 eye of the person who adjusts the valve. From repeated inspection of the town 
 lights at all hours of the night, as well as of the burner before the index, the 
 requisite pressure is kjiown and regulated; as the night advances, the valve is 
 lowered more and more, and in the morning (when the lamps ought to be all 
 out) it is depressed to one-tenth of an inch, that being sufficient to cause the 
 exit of the gas in the lowest situations. 
 
 The opposite engraving exhibits a new construction of a retort and of a puri- 
 fying vessel, for which Mr. Hobbins, of Walsal, in Staffordshire, obtained a 
 patent. The objects sought by these new arrangements are, first, an increased 
 facility of charging and discharging the retort without the necessity of luting 
 the joints ; and a more rapid decomposition of the coal, by spreading it in a thin 
 stratum equally over the bottom of the retort ; and the subsequent purification 
 of the gas, without employing mechanical labour to produce a constant agita- 
 tion with the lime or other purifying materials. Fig. 1 shows a longitudinal 
 section of a retort, supposed to be placed in a furnace occupying the space 
 between the dotted lines a a ; the two ends of the retort are flanged on to the 
 body, and, projecting beyond the brickwork, are removed from the influence of
 
 GAS LIGHTING. 
 
 591 
 
 the fire b and c are two scrapers, with long rods attached to them, which pass 
 through the flanged ends of the retorts, and have cross handles at their ex- 
 tremities. From each end of the retort a tube projects horizontally, which 
 serves to support and guide the scraper rods, which slide through them. The 
 form of the scraper b is shown by the separate figure 2, and the form of c by 
 Fig. 3 ; in each of them are two square notches, which, sliding upon square 
 bars of iron, placed longitudinally on the upper side of the interior of the 
 retorts, are thereby suspended to it, and kept uniformly in their proper 
 positions. The process of working the retort is as follows : previous to 
 charging it, the scraper c is drawn outwards from the body of the retort close 
 up to its end, and the scraper b is pushed inwards so as to come in contact with.' 
 e ; both scrapers being then beyond the opening d, the charge of coals is 
 admitted through the latter by opening the cover c ; the scraper b is then drawn 
 back from its position beyond d, and thus spreads the coals in an even layer 
 over the bottom of that part of the retort exposed to the fire. About a foot 
 from each scraper, the rods are connected by a solid and a hollow screw, so that 
 
 when the rods are drawn out, they may be renewed by unscrewing them at 
 these parts. As the distillation of the coal proceeds, the gas escapes by the 
 tube / and from thence passes through the condenser to the purifying vessels. 
 When all the gas has been separated from one charge of coals, the scraper c is 
 thrust forward, pushing before it, and clearing out all the coke, which falls into 
 the coke box g, from which it may be discharged by the mouth piece h into a bar- 
 row, and wheeled away. As it is necessary that the apertures at rfand h should 
 be closed air-tight during the extrication of the gas, the lids or doors are lined 
 with lead, which, being screened from the heat of the furnace, serves to close 
 the joints as effectually as the troublesome process of luting them at every 
 charge. Fig. 4 gives an external view of that end of the retort where the coke 
 is discharged, and Fig. 5 a similar view of that end at which the coals are put 
 in ; the letters have reference to the like parts in each figure. Fig. 6 gives a
 
 .592 GAS LIGHTING. 
 
 vertical section of a series of three vessels, ij fc, which constitute the purifying 
 vessels ; the lower parts of them are occupied with a stratum of lime as high 
 as the dotted line //; the impure gas passes from the retort into the tuhe m, and 
 by its pressure descending along the bent arm, it passes out at the bell-mouthed 
 end, and mixes with the lime contained in the vessel i, wherein it deposits 
 much of its impurity by condensation ; from this vessel the gas again rises and 
 enters the tube n, thence filtering through the second lime vessel j, it reascends 
 and enters the tube o into the third filtering vessel k ; thence it proceeds by the 
 tube r, to the gasholder, for subsequent distribution. The covered tubes ppp 
 above the filtering vessels are for the purpose of charging them witli lime ; the 
 dotted circles are perforations in the sides of the vessels (furnished with plugs) 
 for the purpose of ascertaining the depth of the stratum of lime, or other purify- 
 ing material ; and the three tubes q q q at the bottom of the vessels are for dis- 
 charging the lime when saturated with the various matters that have been 
 condensed during the purifying process. To aid the complete discharge or 
 clearing of these vessels of their contents, three bars of iron are employed as 
 scrapers, one in each vessel, and a rod, as a handle, is screwed into each, and 
 passes through a stuffing box in the side of each vessel. We are not aware 
 whether the preceding apparatus has been adopted in practice. Retorts of a 
 semicircular form in their transverse section have been tried, but although the 
 coal was very rapidly and effectually decomposed, they were so speedily 
 destroyed that we believe retorts of this figure are no longer employed. Upon 
 the subject of retorts generally, it may be observed, that they, together with 
 the hydraulic mains, and other necessary connexions, form one of the principal 
 items of charge in the erection of gas works on the ordinary plan ; and that in 
 conducting works on the same principle, an enormous expense is annually in- 
 curred by the oxidizing or burning away of the retorts. Indeed the oxidation 
 of these vessels is so rapid, that however the time of their duration may vary 
 from a difference of their form, the quality of the iron, or the mode of setting 
 them in the furnace, they cannot withstand, on an average, more than eight or 
 nine months' wear. To avoid these sources of expense, and with a view to 
 other advantages, Mr. S. Broadmeadow, of Abergavenny, devised the following 
 process, which he secured by patent. The plan was adopted at the Aber- 
 gavenny Gas Works, but has not come into use elsewhere ; and although it may 
 not realize all the advantages contemplated by the inventor, is deserving of notice 
 in this place. The plan consists, first, in substituting brick ovens for iron 
 retorts ; secondly, in exhausting the ovens of gas, as fast as it is generated, 
 by means of an exhausting cylinder, or any equivalent apparatus ; and thirdly, 
 in purifying the gas so generated, either wholly or partially, by admitting into 
 the gasometer a certain portion of atmospheric air. The engraving on 
 page 593, with the following description, will sufficiently explain the process ; 
 a is the oven in which the gas is generated ; b the oven door ; d door of 
 the fire grate ; e a pipe through which the gas is conveyed from the oven 
 to the condenser /, into which a small hand-pump g is inserted to draw off 
 the coal tar ; ha pipe through which the gas passes from the condenser into 
 the top of the exbausting cylinder i : the piston of this exhausting cylinder 
 receives its motion from a small steam engine, which is supplied with steam 
 from a boiler fixed in the flue, and heated-by the waste fire of the furnace, k k 
 two pipes, one leading from the top and the other from the bottom of the ex- 
 hausting cylinder to the purifier I ; m the outlet pipe to convey the gas from 
 the purifier into the gasometer ; and n is a pipe branching from the pipe A to 
 convey the gas, at the alternate vibration of the beam, into the lower part of 
 the same cylinder. Some ovens on this principle have, as we have already 
 mentioned, been erected at the Gas Works at Abergavenny, and it is stated, that, 
 after being kept constantly at work for two years, they were not apparently the 
 worse for wear, whilst the charges for repairs had not reached twenty shillings 
 each per annum. Another advantage is, that as these ovens contain a charge 
 equal to about six full sized iron retorts, and require to be charged but once 
 in twenty-four hours, there is not only a saving in the first cost of erection, and 
 in the annual wear and tear, but in all the daily labour consequent upon the old
 
 GAS LIGHTING. 
 
 593 
 
 process, in which much time, as well as labour, is usually expended in thn 
 drawing off the charge, and in recharging. 
 
 The next improvement, and which indeed constitutes a principal feature in 
 Mr. Broadmeadow's invention, is that of his patent application of an exhaust- 
 ing cylinder, or other apparatus, to exhaust the gas from the condenser, thereby 
 causing a partial vacuum, and enabling the gas to flow from the ovens as fast 
 as it is generated. By means of this exhausting apparatus a portion of atmo- 
 spheric air, equal to about one-eighth part of the entire quantity of gas, is 
 admitted into the gasometer, when the oxygen of the atmosphere mixing with 
 
 the SI ' ...... ^, , , '.. .,.- i:-^-:. 
 
 a greater 
 patentee, 1 
 purifying process is required. As the admission of too great a quantity of 
 
 mittea into tne gasometer, wnen the oxygen ot the atmospnere mixing wun 
 e suphuretted hydrogen precipitates the sulphur, and gives to the lighted gas 
 greater degree of brilliancy. This mode of purifying gas is said, by the 
 tentee, to be so efficient, that, when the coal used is of good quality, no other
 
 ,594 
 
 GAS LIGHTING. 
 
 atmospheric air would prove injurious, the requisite speed at which the exhauster 
 should be worked is shown by a water gauge. 
 
 We shall now proceed to describe Mr. Ibbetson's patent process of preparing 
 inflammable gas by decomposing water, in conjunction with coal, in a furnace 
 of a peculiar construction. The following engraving represents a vertical 
 section of the apparatus employed. In the central compartment at a is au 
 iron door and frame, opening above the fire-place for supplying the fuel thereto; 
 immediately under the arched top of the fire-place is a small aperture b, for the 
 admission of the air requisite for the combustion of the fuel ; there is another 
 small door, (shown by dots at c,) for the purpose of lighting the fire ; d is the 
 ash-pit, e e e is the flue which descends, and then takes the course pointed out 
 by the direction of the arrows to the chimney, thus enveloping the decomposing 
 chamber, which occupies the space between the flues and the central furnace. 
 The coals or other substances to be decomposed are introduced through an 
 
 iron door h ; this door, as well as the two other doors, 1 1 (shown by dotted lines), 
 for extracting the coke, are kept closed air tight, by luting, during the process 
 of distillation ; and for clearing out the ashes under the gratings, there are 
 apertures at it, fitted also with doors, and kept closed like the last mentioned, 
 whilst the decomposition is going forward within. The steam is introduced at 
 two places?in the decomposing chamber ; one at/ by a pipe of retort earth, from 
 whence it ascends among the ignited coke, passing round the chamber in the 
 direction shown by the arrows ; the other at k, where a tube of retort earth is 
 extended across the chambers horizontally, the steam escaping from it through 
 numerous small holes at the bottoms and sides. The gases and vapours pro- 
 duced by these combined circumstances make their exit by a pipe at o. By 
 this apparatus, the patentee also professes to decompose tar and oil along with
 
 GAS LIGHTING. 
 
 595 
 
 the coal ; in which case, these fluids would be introduced on the right hand 
 side, (opposite to k,) through tubes, regulating the quantity by means of 
 stop-cocks, which quantity should of course never be more than will become 
 decomposed, whilst circulating through the burning coal, without reaching the 
 bottom of that side where it enters. The patentee observes, that the coals 
 should be broken into pieces not exceeding the size of walnuts, before they are 
 put into the decomposing chamber ; and that the charges should be made from 
 time to time by fresh layers of an inch and a half in thickness, after the pre- 
 vious charge has become red hot. 
 
 We have already stated that Mr. Murdoch experimented upon wood and 
 peat, as well as pit coal, in order to ascertain the qualities and quantities of 
 illuminating gas furnished by each. Shortly after the introduction of gas light- 
 ing into public use, experiments were made upon various other substances, 
 with the same view; as coal tar, pitch, pine knots, and sawdust; and in 1815 
 Mr. John Taylor obtained a patent for an apparatus for the purpose of preparing 
 inflammable gas from any kind of animal, vegetable, or mineral oil, fat, 
 bitumen, or resin, which can be rendered fluid by heat. The process may be 
 briefly described as follows : the liquid material is allowed to flow in a very 
 minute stream into a retort heated to redness, and containing a quantity of coke, 
 hard broken bricks, or other porous and refractory substances ; here the oil is 
 speedily converted into a very fine and brilliant gas, which is conducted to a 
 close vessel surrounded by water, in order to condense any oil which may have 
 come over, not decomposed, or in the state of vapour, which oil is returned to 
 the retort by a very simple arrangement. From the condenser the gas enters 
 a vessel containing the liquid from which the gas is prepared, by which a 
 further condensation of any condensible vapour which the gas may contain is 
 effected, and the gas then passes into the gasometer. 
 
 Mr. Philip Taylor some time afterwards obtained a patent for an improved 
 apparatus for obtaining gas from various substances in a liquid state, a section 
 of which apparatus is exhibited in the following engraving. When the liquid 
 
 itter introduced into the retort is of easy decomposition, one distrllation of it
 
 596 GAS LIGHTING. 
 
 through a single retort will be in general sufficient to separate the gas in a 
 tolerably pure state ; when they are, however, such as to require a longer pro- 
 cess, the gaseous products of the first distillation are passed into a second retort. 
 to complete the separation of the contaminating matter. As many as ten 
 retorts similar to those shown in the engraving may be conveniently arranges 
 over one furnace. In the case of a single distillation it is therefore to be 
 understood that these are all supplied at once with the fluid matter, and the 
 product of each retort respectively is carried from them direct to the gas holder ; 
 but when a second distillation is necessary, the ten retorts before mentioned 
 would be employed as five pair, and the diagram is drawn so as to show the 
 operation either by a single or by a pair of retorts, which we shall now explain. 
 The figure gives a vertical section of two cast-iron retorts, a and b, fixed over a 
 furnace constructed with fire-bricks ; the retorts are about four feet long, of a 
 cylindrical form, with covers accurately fitting their necks so as to render the 
 vessels air-tight, when they are luted on and fastened down with keys or screws. 
 They are placed erect in the brickwork by resting on their projecting flanges, 
 leaving open spaces around them as at c c c, by which very extended surfaces 
 are exposed to the direct action of the fire. Within each of the retorts a casing 
 or shell of wrought iron is placed, exactly fitting the interior; these are filled 
 with fragments of brick or coke, &c. and as these materials require to be fre- 
 quently changed, each case is provided with ears or lugs, for the convenience of 
 drawing them out, or letting them down into the cast-iron retorts. Vertical 
 tubes, e g, are placed in the centre of each retort; they are connected at then- 
 upper ends by the horizontal tube/, and, passing through the covers, their other 
 ends descend to the bottom of the retorts, when they are perforated with holes, 
 as shown in the figure. The internal cases, previously, empty, are then filled 
 with broken bricks or other substances before mentioned, and the covers and 
 joints being all properly luted and secured, the retorts are exposed to the action 
 of the fire until the material contained in them acquire a red heat. Thus pre- 
 pared for operation, the fluid to be distilled is allowed to flow through the pipe 
 d in a small quantity into the retort a ; here, falling upon the red hot materials, 
 the process of decomposition commences, which is assisted by the filtration of 
 the liquid through these substances. Having arrived at the bottom, the gaseous 
 portion, passing through the perforations, rises up the tube e; thence, pro- 
 ceeding along the branch/, it descends into the second retort b, by the pipe ff, 
 and passing out again through the holes at the bottom of g, the gas reascencls 
 among the ignited materials, being purified in its progress, until it arrives at the 
 tube h, which conducts it to the gasholder. When the operation consists of 
 only a single distillation, the fluid is introduced by a pipe i, shown by the 
 dotted lines. In this case the tube g does not extend higher than the cap of 
 the retort, in the centre of which the pipe enters, and passes down the middle 
 of the tube g, within six inches of the bottom ; from thence the liquid, flowing 
 through the perforations among the red hot materials, becomes quickly decom- 
 posed, and the resulting gas, filtering as it ascends, reaches in nearly a pure 
 state, the tube h, which, as in the former case, conducts it to the gasholder. 
 
 Coal tar has already been noticed as one of the products resulting from the 
 distillation of coal, and at the first establishment of public gas works, great 
 profits were expected to be realized from the sale of this article ; but from the 
 large quantities produced, and from its inapplicability to most of the purposes 
 for which vegetable tar is employed, it was soon found difficult to find a market, 
 and it became an object to utilize the material by converting it into gas. For 
 this purpose various processes were resorted to, nearly resembling that just 
 described, for converting oil and other liquid matters into gas; but a serious 
 inconvenience was found to result from the deposition of asphaltum in the pipes, 
 (owing to the imperfect decomposition of the tar,) which quickly choked them 
 up, and rendered them unserviceable, whilst the gas afforded but a feeble light, 
 and emitted much smoke. Numerous plans have since been proposed for the 
 remedy of these evils, of which we shall only notice the invention of Messrs. Vere 
 and Crane ; the apparatus, it is stated in the specification, is also applicable to 
 the distillation of all animal or vegetable solid or liquid matters, from which
 
 GAS LIGHTING. 
 
 597 
 
 sarburetted hydrogen may be obtained. The process consists in introducing into 
 the retort a constant stream of water, or a current of steam into the exit pipe, 
 which, mixing with the volatile matters arising from the substance under 
 decomposition, causes them to fall down again into the retort without proceeding 
 further to choke up the pipe, while the more gaseous products pass on through 
 the steam in a purer state to their destination, to be afterwards treated in 
 the usual way. Fig. 1 is a front elevation of the improved retort set in the 
 brickwork of the furnace ; and Fig. 2 is a vertical section of the same ; the 
 
 Fig. 
 
 letters have a reference to the same parts in each figure. is the ash-pit, b 
 the furnace, c c the flue winding round the retort ; d the retort, with its lid 
 fastened in the usual way by a cross bar and screw ; e the exit pipe, through 
 
 pan or tray, tc 
 to /, leading 
 
 ter ppe, an a cistern of water. 
 4 o 
 
 asene n e usua way y a cross ar an screw ; e te ext 
 which the gas escapes as it is generated ; / is a wrought-iron p 
 hold tar or other liquid matter to be distilled ; g a supply pipe 
 from the cistern or reservoir h i is a water pipe, and k a cist
 
 .-598 GAS LIGHTING. 
 
 When tar, for instance, is to be operated upon, the retort, partly filled with coke 
 or broken bricks, is to be brought to a bright red heat, which maybe ascertained 
 by inspection through the holes o o, shown in Fig. I, which are provided with 
 stoppers ; the cock of the water pipe is then opened, to admit the water to flow 
 in a slender stream into the retort, the heat of which immediately converts it 
 into vapour. This done, tar is to be admitted from the reservoir h to flow 
 through the pipe g into the pan /, where it is quickly decomposed ; the gas, as 
 it ascends, enters the exit pipe, and necessarily passes through a large volume 
 of steam, which, the patentees state, causes an instant precipitation of the car- 
 bonaceous matters, which would otherwise lodge in the pipes, and ultimately 
 obstruct the passage of the gas through them. The gas thus relieved in the 
 earliest stage from the principal contaminating matters, has then to pass 
 through the ordinary purifications, by which it is ultimately delivered to the 
 burners, in a state of great purity, for consumption. When coal or other solid 
 matters are to be decomposed to obtain the gas, the pan /, the pipe g, and the 
 reservoir h, are to be removed, and the operation conducted without them 
 retaining however the use of a current of steam as before. 
 
 The subjoined engraving represents Mr. Gordon's portable gas lamp. The 
 idea of employing gas as a substitute for lamps and candles, occurred to 
 Mr. Murdoch, as v 3 have seen, so early as the year 1792, wh**n he made 
 
 some experiments with that view, but seems to have subsequently aban- 
 doned the idea ; but to Mr. Gordon is due the merit of realising it, and 
 thus at length rendering inflammable gas applicable to every purpose of arti- 
 ficial illumination. These lamps consist of strong wrought-iron vessels of 
 various dimensions and forms, in which the gas is compressed into one thirtieth 
 of its bulk at the ordh ary atmospheric pressure ; the flow of the gas being 
 regulated with the utmost exactness, according to the degree of light required, 
 by a valve, which we shall subsequently describe. 
 
 A company having been formed to carry Mr. Gordon's invention into effect 
 upon an extensive scale, works have been established in London, and at some 
 of the principal country towns, at which the gas is manufactured; and the lamps 
 being charged therewith, are furnished to the consumer as occasion requires. 
 The gas with which the lamps are charged is usually procured from oil, on 
 account of its greater p arity, and of its occupying less space than coal gas, one 
 foot of oil gas being equivalent in illuminating powers to nearly three feet of 
 coal gas. The gas is generated by the usual processes, and the following en- 
 graving represents the apparatus employed at the London Portable Gas Works 
 for ch;irging the lamp. . a is the main horizontal shaft of a steam engine, upon
 
 GAS LIGHTING. 
 
 599 
 
 which are fixed two spur wheels b b ; the teeth of these take into the teeth of 
 two similar wheels c c fixed on the axis of a three-throw crank, to which is 
 thereby communicated a rotatory motion. The crank imparts (in the usual 
 manner) an alternating motion to the rods eee, which work three force pumps : 
 for a description of the forcing pumps originally employed for this purpose, 
 (which were of a singularly ingenious construction, although we believe they 
 have since been replaced by others more nearly resembling the ordinary 
 
 force pump,) we refer the reader to the article AIR PUMP. As the plunger of 
 each pump is successively raised, a quantity of gas equal to the space pre- 
 viously occupied by the plunger flows from the gasholder into the chamber at 
 the opposite end, by means of a pipe of communication, part of which is 
 brought into view at /. The valve by which the gas enters, opens inward, so 
 that it cannot return the way it came ; but there is another valve which opens
 
 600 GAS LIGHTING. 
 
 outward, and this is kept closed by a spring of sufficient power to prevent the 
 escape of the gas in the uncompressed state ; upon the descent of the plunger 
 the strength of this spring is overcome, the gas is forced out, and the valve 
 closes again. From the pumps the gas proceeds along the tube g, and enters 
 by the jointed valve h, into a strong wrought iron recipient i ; in this vessel it 
 is evident the gas might be collected and condensed to any required number of 
 atmospheres ; but the valve j being opened (by the cross-handled key shown), 
 the gas is suffered to flow through the pipe k k, which is extended along the 
 upper side of the " filling table" m, and from thence into the reservoirs (" port- 
 able lamps") llll, by which arrangement the pressure of the gas becomes 
 equalized in all the vessels, however great their number. The degree of con- 
 densation at which the gas has arrived by the continued action of the pumps, is 
 shown throughout the process by a mercurial guage, applied in the following 
 manner. The pipe n, which proceeds from the recipient i, conveys the gas 
 under compression into the reservoir of mercury, at the bottom of the guage 
 o o ; the pressure of the gas upon the surface of the mercury causes the latter 
 to rise in a long glass tube, hermetically sealed at top, and inclosing a portion 
 of atmospheric air above the surface of the mercmy ; this air becomes com- 
 pressed into a smaller space by the rise of the mercury, as the condensation of 
 the gas advances, and the diminution of its volume indicates, upon a scale 
 attached to the tube, the degree of condensation or pressure in the lamps ; and 
 when the mercury arrives at the line denoting thirty atmospheres, the valve j is 
 shut by means of the cross handle. All the lamps attached to the pipe in con- 
 nexion with the closed valve being now filled, are taken away by unscrewing them 
 from the sockets in the tube. The external pressure being removed by turning 
 off the gas r the lower valves of the lamps close by the pressure of the gas 
 within them, and the contents are further secured from escaping by a workman 
 screwing a cap over the lower valve as he successively removes each of them 
 from the tube. To ascertain whether there is any leakage, the lamps are im- 
 mersed one by one in a contiguous trough of water, where, if any leakage 
 exists, it is immediately shown by the gas bubbling up. The perfect state of 
 each lamp being thus ascertained, they are arranged in extensive racks or 
 stands, ready to be taken out to the consumers by the Company's carts, which 
 are regularly dispatched to all parts of the town. 
 
 To complete the subject, we shall proceed to describe the construction of these 
 valves, of the uses of which we have only yet spoken : they are of three kinds, 
 and were the subject of a patent granted to Mr. Gordon. 
 
 The annexed engraving gives a sectional view of an improved stop-valve 
 (similar to those attached to the principal 
 recipient *), especially adapted for transfer- 
 ring the compressed gas from one vessel to 
 another, without occasioning loss during the 
 process. It is composed of two pieces of 
 metal, A and B, which are screwed together 
 with a soft metal collar between them at a 
 a ; e e represents the openings through 
 which the gas is allowed to pass. The piece 
 A has the regulating steel screw c tapped 
 through it, being formed at the lower part 
 with a double cone, one part of which cone is 
 adapted to fit correctly into the cavity in the 
 under side of the piece A. Now when the 
 lower cone of the regulating steel screw is 
 screwed or forced tight down into the conical 
 seat in the piece B, it prevents all escape of 
 the gas; and when it is desired to trans: er 
 compressed gas from one lamp or reservoir to 
 another, the regulating screw c is to be turned 
 until its upper cone fits and applies correctly into the conical cavity of the piece 
 A, and thereby prevents all escape of the gas up the threads of the regulating
 
 GAS LIGHTING. 
 
 601 
 
 screw during the process of transferring, allowing, at the same time, free pas 
 sage of the gas from one reservoir to another, through the openings e e. 
 
 The next valve to be described is the one 
 which is fixed at the bottom of each reservoir 
 or lamp, for the purpose of filling them in the 
 manner described in the preceding part of our 
 subject; the annexed cut represents a sec- 
 tion of one of those valves. This filling valve 
 consists of a small conical plug g, which is 
 fitted into a conical cavity or seat in the piece 
 of metal c, similar to the valves of an air-gun, 
 being closed by a slight steel spring h, and 
 guided in its way by a metal pin, which slides 
 through a hole in a small brass cap or per- 
 forated cover t, represented as screwed over 
 it ; d shows a brass plug, which is intended to 
 be screwed into the lower aperture of the 
 piece c, after the filling is completed. The 
 
 upper surface of this screw-plug is furnished 
 with a soft metal ring or collar, b b (as in the 
 
 before-mentioned valve), which being pressed, 
 by the force of the screw, into contact with the under side of the piece c, effec- 
 tually prevents any escape of the gas from that end of the reservoir, even if 
 the filling valve g should not be quite air-tight. 
 
 The following figure represents a section of the third and last of these valves, 
 and its use is to permit the flow of gas to the burner to be regulated with great 
 nicety and precision. The passages for the 
 gas, e e, are drilled out of one solid piece of 
 metal, and the regulating screw c is tapped 
 into the side of the same piece ; the lower part 
 of it is adapted to screw into an aperture at 
 one end of the reservoir of the lamp, when 
 the regulating steel screw c is screwed up so 
 that its conical end fits tightly into the conical 
 cavity, it closes it perfectly, and prevents all 
 escape of gas to the burner a ; but on turning 
 the regulating screw slightly round by its 
 square head, the gas escapes through the pas- 
 
 sages e e to the burner, in any degree that may be desired. Previously to in- 
 serting the regulating screw, it is dipped into a mixture of bees' wax and oil, 
 which fills up every minute cavity or space which may be left between the 
 threads of the two screws. 
 
 The engraving on page 602 represents a contrivance for delivering gas to the 
 consumers in its natural volume, under atmospheric pressure. It consists of a 
 collapsing gasholder, capable of containing upwards of 1000 cubic feet of gas; 
 it is mounted on wheels ; and being charged at the gas works, the gas is con- 
 veyed wherever required. The invention forms the subject of a patent to 
 Messrs. Coles and Nicholson, and is, we believe, made use of by the Portable Gas 
 Company at Manchester, in addition to the gas-condensing apparatus erected at 
 their works at that place. Fig. 1 represents a plan of the cart, with the top of it 
 removed ; Fig. 2 is a side elevation, and Fig. 3 a front elevation ; Fig. 4 is 
 merely an enlarged section of the box marked d in Fig. 2. The recipient is 
 composed of two distinct parts or halves, a and b ; the upper part a is made of 
 some flexible material, impervious to gas ; and the lower part b of some com- 
 paratively stiff and inflexible substance ; when the vessel is empty, the part a, 
 turning itself inside out, falls down inside of b; the vessel is filled by forcing 
 the gas from the works through a pipe, which is screwed into a nozle at/, pro- 
 vided with a stop-cock, which is turned off after the recipient is fully inflated, 
 and the supply pipe from the works removed. The machine then travels 
 through the streets, and stopping at a customer's door, one end of a flexible
 
 602 
 
 GAS LIGHTING. 
 
 pipe is screwed into the gasholder of the house, and the other end into a nozle 
 in the box d, which communicates with the interior of the recipient by means 
 of intermediate valves shown at Fig. 4. The gas-exhauster c is then put in 
 motion by the handle at the top, and at every exhausting stroke is filled with 
 
 Fig- I. 
 
 gas from the gas cart through the valve g, Fig. 4 ; and at each forcing stroke, 
 the gas is discharged through the valve h, and along the flexible pipe into the 
 gasholder of the house, until the required quantity is transferred. The gas cart 
 thus proceeds from house to house, until the whole load is discharged. Along 
 the bottom of the cart is a pipe e, connected at one end with the stop-cock/, 
 and at the other with the box d of the exhauster, and perforated with nume- 
 rous small holes, for the purpose of allowing the passage of the gas along the 
 bottom of the cart when the flexible top lies over it. Since the foregoing 
 account of the Portable Gas Machinery was prepared for the press, we have 
 been informed that it has been nearly superseded by subsequent improvements 
 in the manufacture and management of coal gas; nevertheless, the subject pos- 
 sesses sufficient intrinsic merit for our pages, as much of the mechanism is 
 applicable to other purposes. 
 
 The " Domestic Gas Apparatus," shown in the following engraving, is an
 
 GAS LIGHTING. 
 
 803 
 
 invention of Mr. Pinkus, for the manufacture of gas on so small a scale as to 
 he adapted to private houses. An apparatus of the kind was exhibited in use 
 
 for a considerable time in the Strand, and we believe the invention has been 
 adopted in various extensive private establishments and small manufactories. 
 Fig. 1 is a front elevation ; Fig. 2 a lateral section of the apparatus ; Fig. 3 a 
 section of the retort ; and Fig. 4 a section of a retort of a different construe-
 
 601 GAS LIGHTING 
 
 tion ; Pig. 5 is a section of the condenser. In each bottom figure the same 
 letters refer to the same parts, a, Figs. 1 and 2, shows its application to a 
 kitchen range, but it is equally adapted to any other common fire-place ; b b, 
 Fig. 2, is a recess or furnace built in brick at the back of the fire-place, covered 
 in front by an iron plate c, and having a flue d opening into the chimney ; e, 
 Figs. 1, 2, and 3, is a cylindrical retort, divided by two or more internal par- 
 titions, radiating from a conical pipe/, as shown in Fig. 3. The retort is turned 
 with a small rim or flange at the fore end, which fits into the plate c, and the 
 hinder end is supported by a stout pin projecting frcm the back of the retort, 
 and resting in an iron socket let into the brickwork. The hinder end of the 
 pipe / terminates in a cup or cavity g, pierced with several holes, and serving 
 as a chamber for the gas to collect in ; the pipe /is also pierced with numerous 
 small holes, to allow the tar, as it forms, to fall through them upon the burning 
 fuel, where it, as well as that portion which runs down the conical pipe /and 
 the cup g, is decomposed and converted into gas. In the fore end of the pipe 
 / is screwed a stuffing box, through which passes the pipe h, leading to the con- 
 denser. Each compartment of the retort has a door or mouth-piece m m, by 
 which the coal or other material for making gas is introduced, and the door is 
 secured by sci-ews, the joints being either ground true or luted ; n is an iron 
 plate, sliding in grooves, and, when lowered down, serving to defend the face of 
 the retort and the pipe h from the action of the fire. Fig. 5 is a vessel divided 
 into two parts, the lower part o, which is air tight, containing a quantity of tar, 
 into which the pipe h dips a few inches ; it is supplied with tar from another 
 vessel p, by means of a bent pipe g ; r is a pipe for drawing off the tar when 
 required, and s an opening by which the tar runs down the pipe k into h, and 
 thence into the retort. The upper division of Fig. 5 contains a range of bent 
 pipes t t surrounded by water, one end of which, v, opens into o, and the other 
 end, x, leads to the gasometer ; from the lower bends of these pipes short pieces 
 yy descends into the tar in o, by which means the tar condensed in the 
 pipes 1 1 descends into o, whilst the gas cannot escape through the short 
 pipes. The operation is as follows : the retort being charged, and the doors 
 secured, the retort is turned till the chambers are in the position shown in Figs. 
 1 and 3 ; the shutter re is then let down and the fire lighted, a portion of the 
 heat and flame from which passes through an aperture in the back of the 
 range (shown by the black space between the bars in Fig. 1,) into the furnace 
 b, causing, in a short time, the lower part of the retort to become red hot, and 
 the coals or other materials in the interior to give out gas, which, collecting in 
 the chamber g, passes through the pipes /and h to the condenser ; at the same 
 time the tar given out by the coals in the upper chambers of the retort, 
 descends through / and g on to the burning fuel in the lower chamber, and 
 becomes decomposed. When it is supposed that the materials in the lower 
 compartment have given out all the gas contained in them, the retort is turned 
 partly round, so as to bring another compartment immediately over the flame, 
 when the gas is again given out as before. The gas thus formed contains tar 
 and other impurities, from some of which it can be freed by a reduction of tem- 
 perature ; the pipe h is therefore made to dip a few inches into the tar vessel o. 
 and through this tar the gas has to rise to enter the condenser, by which means 
 it is divested of a portion of its impurities, and, upon entering the condenser, 
 it passes through a great length of pipe surrounded by cold water, when all the 
 condensable impurities are separated, and descend into the tar vessel by the 
 
 r'pes y y. The tar, as we have before stated, returns to the retort by the pipes 
 and h, and is decomposed by falling on the burning coke in the retort. From 
 the condenser the gas passes to the purifier, and thence to the gasholder ; but 
 the method of purifying the gas, either upon a large or a small scale, forms the 
 subject of a separate patent to Mr. Pinkus, which we shall now proceed to de- 
 scribe, observing only that Fig. 4, in the preceding engraving, merely repre- 
 sents an oblong retort, which may be substituted for the one before described, 
 when the length of the fire-place will admit of it ; it will then of course be 
 fixed, instead of turning upon a pivot, and the gas will pass off by the pipe h, 
 and the tar return by k, inserted in the top of the retort.
 
 GAS LIGHTING. 
 
 605 
 
 The purifying substances employed by Mr. Pinkus, are the chlorides of socla 
 or of lime. The following engraving represents two arrangements of the 
 purifying vessels ; the one adapted to the use of gas works on a large scale, 
 and the other for the use of private houses, to purify the gas as it passes from 
 the public main to the burners. The method is as follows: the gas, upon 
 leaving the condenser, passes through a solution of the chlorides of soda or of 
 lime, which may be contained in 'a vessel resembling that shown in section at 
 Fig. 1, through which the gas may be made to pass, acting under a pressure 
 
 Fig. 2. 
 
 of from ten to twenty inches of water, by which means it will be purified, and 
 its obnoxious odour and bad smell removed ; in addition, the patentee recom- 
 mends to pour a quantity of the same solution into the feeder A, Fig. 2, from 
 whence it flows into the tar vessel b b b, through the bent tube c. In this 
 vessel, (which communicates with the retort by the pipe d,) the solution will mix 
 4 H
 
 606 GAS LIGHTING 
 
 with the condensed matter that falls into it through the hranch pipes connect- 
 ing the refrigerator tubes ///, (which are immersed in a vessel of water.) g g 
 with the tar vessel. The compound thus formed, and kept agitated by the gas 
 issuing from the dip pipe h h, is made to flow in a small stream through the 
 pipe d, into the retort, while in action ; upon coming in contact with the ignited 
 materials within the retort, other vapours or gases will be generated, which, 
 combining or mixing with the carburetted hydrogen gas, a chemical action will 
 take place, whereby the gas, while in the retort and during its passage through 
 the refrigerator, will become partly purified, or will be so altered as to be more 
 easily acted upon in its passage through the solution of the chloride of lime, 
 when its purification will be finished. In preparing the solution, the patentee 
 directs to employ one part of chloride to about thirty-five parts of water, and 
 when the chloride is in its most concentrated state a diluted acid, sulphuric or 
 muriatic, may be added to the solution to assist the liberation of the chlorine 
 gas from the lime ; and the quantity of water may then be increased to forty or 
 fifty parts, with one of the chloride. Fig. 3 represents the apparatus for the 
 more perfect purification of the gas on its passage from the street mains to the 
 burners, i is a recipient, intended to contain and supply the purifying liquid; 
 this vessel is connected with another vessel k by a syphon or by a bent tube /, 
 inserted through the centre and top of the lower vessel k, and having a stop- 
 cock m. The lower vessel k is made gas tight, and formed of tin, copper, or 
 sheet iron, and is a receptacle for gas, which flows through it, and for the 
 purifying liquid that falls from the upper vesel i ; n is a common sponge placed 
 on a shelf of coarse wire gauze o ; p is a manhole made in the side of the vessel 
 k, sufficiently large to admit the hand and sponge ; q is a pipe leading the gas 
 from the main ; and r is another pipe to supply the gas in a purified state to the 
 burners ; * is a waste pipe to let off the liquid when it has become too much 
 impregnated with the impurities of the gas; and t is a washing pipe leading 
 from a cistern ; u and v are stop cocks for admitting and drawing off the liquid. 
 The operation of this apparatus is as follows : into the recipient i pour a mix- 
 ture of one measure of the concentrated liquor of the chloride of lime, diluted 
 with from twenty-five to thirty measures of water. When gas is required to 
 supply the burners, turn on at the same time the stop-cocks m, in the bent tube 
 /, and the leading pipe q ; the purifying liquid will then flow through the bent 
 tube I, on to the sponge n, which will absorb a portion sufficient to keep it 
 always wet, and will permit the liquid to filter through, and fall to the bottom 
 of the vessel k; at the same time the gas will continue rising through the 
 moistened sponge n, where it will be acted upon by the purifying liquor, and 
 its obnoxious odour will be removed before it arrives at the burners through the 
 supply pipe r. 
 
 One object of great convenience and utility to which gas lighting has 
 within these few years been applied, is the illumination of public clocks. This 
 we believe was first put m practice at Glasgow, where a clock with two faces, 
 supported at the extremity of a projecting bracket, was lighted by jets placed 
 above it, the light of which was reflected on each face from mirrors placed 
 within the wings of an elegant representation of a phoenix, which sur- 
 mounted the clock. In order to light the burner without sending up a per- 
 son for that purpose, in addition to the pipe which supplied it with gas, was 
 another extending from the main to the burner, having a stop-cock at its 
 junction with the main, and being perforated with numerous small holes 
 throughout its length. Upon opening the cocks, the gas flowed through both 
 pipes, and issued at the small holes in the flash pipe as it was called ; and a light 
 being applied below, quickly communicated along the whole length of the 
 flash-pipe, and upon reaching the jet, ignited the gas issuing from it ; after 
 which, the cock on the flash pipe was shut. Various methods have since been 
 proposed of lighting up clocks, one of which is as follows : a dial plate, out of 
 which the figures representing the hours are cut, in contrary succession iu the 
 usual representation of them, is made to revolve on the axis that would other- 
 wise receive the hour hand. Behind it is a solid field, out of which a sufficient 
 ipace is cut to show the hour, half hour, or quarter ; each half hour is rcpre-
 
 GAS LIGHTING. 
 
 607 
 
 seated by a star, and each quarter by a dot ; and the time is reckoned by the 
 hours and quarters which have passed the centre of the opening Behind the 
 revolving plate is placed a gas light, which is ignited by the jet of gas being 
 directed on to a piece of spongy platina. 
 
 A somewhat superior method to the preceding is exhibited in the following 
 engraving. A is the dial plate of a common clock, with the hours, &c. 
 marked upon it, as usual ; B is the proposed addition to it, for the purpose of 
 exhibiting the time distinctly during the night ; C is a light cog-wheel, placed 
 immediately behind the day dial ; having its centre fitted in the arbour of the 
 hour hand, and revolving with it. The 
 night dial B is designed to be made of 
 plate glass, with the hours painted upon 
 it in black, and to revolve on an axis in 
 its centre. The index represented by 
 an arrow is fixed. The periphery of 
 the glass plate is encompassed by a rim 
 of brass, having cogs in its outer edge, 
 which fits into the cogs of the wheel C ; 
 consequently they move together, and 
 being of equal diameters, they perform 
 their revolutions in equal time. The 
 time represented in our engraving, is a 
 
 Quarter past X; when the hour hand 
 as moved on to XI. (for instance), the 
 transparent dial B will have moved an 
 equal space past the fixed index, and 
 denote the same precise time. Both 
 dials must, by this simple contrivance, 
 invariably agree in their respective indi- 
 cations of the time. During the day, 
 the time is observed on the large dial as usual ; and at night a lighted lamp 
 placed behind the transparent dial will always exhibit the time as distinctly. 
 
 But the most perfect and ingenious mode of illuminating public clocks which 
 has come under our notice, is that by which several of the church clocks in 
 London are lighted. By the revolution of the hands, and the addition of only 
 one wheel and pinion to the clock, the gas is lighted and extinguished at regular 
 stated hours, which hours may be varied monthly to suit the increase or decrease 
 in the length of daylight, by simply adding or withdrawing a pin._ The 
 inventor is Mr. Paine, from whose account in the Transactions of the Society of 
 Arts we have taken the following abbreviated description. 
 
 Reference to the Engraving. Fig.1- represents a skeleton frame dial, cast all 
 in one piece ; the eight central divisions are very thin, and curved, so as not 
 to coincide or interfere with the hands while passing over them ; the spaces are 
 all filled up with transparent red glass, ground rough on the inside. This by day 
 is sufficiently dark to relieve and render distinctly visible the gilt hour numbers;
 
 608 
 
 GAS LIGHTING. 
 
 but at night, when the gas burners behind the dial plate are lighted up, the 
 hours, minutes, and hands appear black, and the rest of the dial glows with a 
 dusky red light. Fig. 2 is a horizontal section across the aperture a a in the 
 church tower at the back of the dial b b ; c the tube which carries the hour 
 hand, having a balance weight and the wheel 48 on its inner end ; through 
 this passes the shaft d d, holding at one end the minute hand, and at the other 
 end the pinion 14 and balance weight e ; //two gas burners; g g the tubes 
 supplying the gas ; the aperture a a, not being so large as the dial, is cham- 
 ferred off at i i, to give a clear passage from the lights all over the dial ; jj a 
 curved reflector, made of sheets of tin ; k k a bar crossing the aperture a a 
 within, to support the motion wheels, and the additional twenty-four-hour 
 wheel, 96; the long axis d d receives motion from the clock (as usual) by a 
 bevel wheel; 14, 42, 12, and 48, Fig. 3, are the usual motion wheels and 
 
 Fig- 1. 
 
 Fig. 2. 
 
 pinions ; an additional pinion of 12 is put on the wheel 42, to turn the wheel 
 96 ; this has thirteen pins, one hour's motion apart ; these pins raise up the 
 weighted lever /, in Fig. 3, and let it drop ; while this is up, (as shown by the 
 dotted lines,) its opposite end m, by means of the connecting rod n, keeps the 
 lever handle o of the gas cock p down, and thus nearly closes it, allowing the 
 passage of only just enough gas to keep the burners alight ; but at eight o'clock, 
 when the weight / drops, it raises the handle o and quite opens the cock p, 
 by which the dial is instantly illuminated. Thus, Fig. 3 represents the lever / 
 down, and the pins nearly beginning to raise it ; by removing two pins, one at 
 each end, the clock will open the gas-cock one hour sooner, and nearly close it 
 one hour later. By successively removing the pins as the days shorten, and 
 replacing them as the days lengthen, the clock is accommodated to all seasons. 
 The whole space is kept clear between the lights and the dial, except only the
 
 GAS LIGHTING. 609 
 
 axis e, Fig. 2 ; and the lights being placed on each side of this, and having a 
 large reflector, no shadow is perceived from it. 
 
 With respect to the quantity of gas obtainable from a given weight of coal, 
 it depends greatly upon the quality of the coal, and also upon the construction 
 of the retorts, and the method of working them. Mr. Peckston, in his valuable 
 treatise on gas lighting, whilst writing on this branch of the subject, observes that 
 pit coal may be divided into three classes, according to the proportions of its 
 component parts. Such coals as are chiefly composed of bitumen are to be 
 considered as belonging to the first class. These coals burn with a bright 
 yellowish blaze during the whole process of combustion ; they do not cake, 
 neither do they produce cinders, but are reduced to white ashes. At the head 
 of this class is to be placed Cannel coal ; and most of the varieties of Scotch 
 coal, as well as some of those found in Durham and Northumberland, belong to 
 it, likewise the coals from Lancashire and the north-western coasts of England. 
 When ellipsoidal retorts are used, (which is the form which Mr. Peckston 
 decidedly prefers,) and charged with 1J bushel, or about 126lbs of coal, the fol- 
 lowing quantities of gas may be obtained in the manufactory, or on the large 
 scale. From a ton of 
 
 Lancashire Cannel 11,600 cubic feet of gas. 
 
 Newcastle (Hartley's) 9,600 
 
 Staffordshire (best kind) 6,400 
 
 The coke obtained from coals of this class is in_ small quantity, and of very 
 inferior quality. The second class of coals comprehends those varieties which 
 cake in burning. These contain less bitumen and more charcoal than the first 
 class. They produce less ashes, but afford hard grey cinders, which when 
 burnt over again with fresh coals, produce a very strong heat. The gas obtained 
 from these coals is not of so rich a quality as that from the first class, but the coke 
 is extremely well adapted for domestic and culinary purposes. When ellipsoidal 
 retorts are used, charged as before, with about a bushel and a half, from a 
 ton of 
 
 Wallsend, may be obtained . . 10,300 cubic feet of gas. 
 
 Temple Main 8,100 
 
 Primrose Main 6,200 
 
 Pembry 4,200 
 
 The third class of coal consists of such as are chiefly composed of charcoal, 
 chemically combined with different earths, and containing little or no bitumen. 
 Amongst the varieties of this coal are the Kilkenny coal, the Welch coal, and 
 the stone coal. None of the coals comprised in this class can be profitably 
 used for making gas. 
 
 Mr. Peckston gives the following table, exhibiting the comparative quantity 
 of gas obtainable from the following different species of coals comprehended 
 in the first and second classes, the Scotch Cannel coal being considered the 
 standard, and estimated at 1000. 
 
 Scotch Cannel 1000 
 
 Lancashire ditto .... 986 
 
 Yorkshire ditto .... 949 
 Bewicke and Craister's 
 
 Wallsend 875 
 
 Russell's ditto 861 
 
 Tanfield Moor 850 
 
 Heaton Main 822 
 
 Hartley's 810 
 
 Temple Main .... 690 
 
 Manor Wallsend ... 650 
 Forest of Dean Middle 
 
 Delf 612 
 
 Eden Main 562 
 
 Staffordshire coal, 1st kind 546 
 
 Ditto ditto, 2d ditto 514 
 
 Ditto ditto, 3d ditto 492 
 
 Ditto ditto, 4th ditto 490 
 
 Pembry 354 
 
 Killingworth Main ... 792 
 
 Pontops 762 
 
 With respect to the best form of retorts, and the mode of working them, so 
 as to produce the largest quantity of gas, we give the following summary of 
 three sets of experiments detailed in Mr. Peckston's work ; the coals in each 
 instance were of the same quality. 103 chaldron 12 bushels, distilled in
 
 610 GAS ENGINE. 
 
 circular retorts, charged with 2 bushels of coals, and each charge worked off in 
 6 hours, afforded 8300 cubic feet of gas per chaldron, and required 43 chaldron 
 14 bushels of coals for heating the retorts, = 42 per cent, on the quantity 
 employed for making gas. By cylindrical retorts charged with 2 bushels at 
 each charge, and which was worked off in 8 hours, 85 chaldron, 27 bushels 
 of coals yielded 10,000 cubic feet of gas per chaldron, and required for car- 
 bonization or heating of the retorts 21 chaldrons 16 bushels of coals, or about 
 25 per cent, of the quantity carbonized. With ellipsoidal retorts, the two 
 diameters of which were 20 inches and 10 inches respectively, charged with 1J 
 bushel, and each charge worked off in hours, 61 chaldron 8 bushels of coals 
 yielded 14,000 cubic feet of gas per chaldron, and required for carbonization 19 
 chaldrons 27 bushels of coals, or 32 per cent, of the quantity carbonized. Mr. 
 Peckston likewise states that five elliptical retorts are capable of carbonizing 
 45 bushels, or 33 cwt of coals, in 24 hours, but their average work may be 
 taken at 1 chaldron, or 27 cwt. in that time. 
 
 Mr. Anderson, of Perth, made a great number of experiments, to determine 
 the comparative quantity of light afforded by candles and coal gas ; the size of 
 the candles which he employed, was short sixes. The following are some of 
 the results : 
 
 A 3-jet burner consumed per hour 2,074 cub. in. = 6 candles. 
 
 An Argand of 5 holes 2,592 ,, 8 ., 
 
 Ditto 10 3,798 12 ' 
 
 Ditto 14 5,940 19J 
 
 Ditto 18 6,840 21 
 
 The mean of these results is, that 324 cubic inches of coal gas yield light 
 equal to that of one candle for an hour ; but this is the coal gas of Perth, the 
 specific gravity of which, Mr. Anderson says, is 650. 
 
 GAS ENGINE. An engine in which the motive force is derived from the 
 alternate expansion and condensation of the liquefiable gases. For the discovery 
 that certain gases may be reduced to the liquid form, and for the suggestion of 
 such gases as prime movers of machinery, we are indebted, (as we have 
 already noticed under the word GAS,) to Sir Humphrey Davy and Mr. 
 Faraday. The important advantages which seemed likely to be realized by 
 this discovery, naturally attracted the attention of engineers and scientific 
 mechanists, and many of the most eminent occupied themselves in endeavour- 
 ing to devise such arrangements as would render it applicable in practice. 
 The person who pursued the subject with the greatest perseverance was Mr. 
 Brunei, who obtained a patent for an apparatus, in which the liquefiable gases 
 are employed to furnish the moving power, and more especially the carbonic 
 acid gas. This gas may be obtained by decomposing any of the carbonates 
 by the action of the common acids. The mode of obtaining the liquid from 
 the gas is by forming the gas under a gasometer, and condensing it afterwards 
 in another vessel by means of a condensing pump, and continuing the opera- 
 tion until it passes to the liquid state. 
 
 The engraving on the next page represents Mr. Brunei's apparatus. This 
 apparatus, as shown at Fig, 2, consists of five distinct cylindrical vessels ; the 
 two exterior vessels a and b contain the carbonic acid, reduced to the liquid form, 
 and are called the receivers; from these, it passes into the two adjoining vessels 
 c and d, termed expansion vessels ; these last having tubes of communication 
 with the working cylinder e, the piston therein (shown by dots) is operated upon 
 by the alternate expansion and condensation of the gas giving motion to the 
 rod/, and consequently to whatever machinery may be attached thereto. As 
 the working cylinder e is of the usual construction, no further description of 
 that part of the apparatus is necessary ; and as the two vessels on ore side of 
 the cylinder are precisely similar to those on the other, a description of the 
 receiver a and the expansion vessel c will apply to their counterparts b and 
 d; the two former (a and c) are therefore given in a separate Fig. 1 on a 
 larger scale, in section, that their construction may be seen, and their operation 
 better understood. The same letters of reference designate the like parts in 
 both figures. The communication of the condensing pump (before mentioned"!
 
 GAS ENGINE. 
 
 611 
 
 with the receiver a, is through the orifice g, which can be stopped at pleasure 
 by the plug or stop-cock h. When the receiver has been charged with the 
 
 Fig. I 
 
 liquid and closed, a pipe i is applied to, and connected with the expansion vessel 
 c at k; 1 1 is a lining of wood (mahogany) or other non-conductor of heat, to
 
 612 GAS VACUUM ENGINE. 
 
 prevent the absorption which would otherwise be occasioned by the thick sub- 
 stance of the metal. The expansion vessel is connected through a pipe m to 
 the working cylinder e ; these vessels contain oil, or any other suitable fluid 
 shown at n, as a medium between the gas and the piston. The receiver is 
 a strong gun metal vessel, of considerable thickness, in the interior of which 
 are placed several copper tubes, as represented at o o o ; the joints of these 
 tubes through the top and bottom of the receiver are made perfectly tight by 
 packing. The use of these tubes is to apply alternately heat and cold to 
 the liquid contained in the receiver, without altering very sensibly the tem- 
 perature of the cylinder. The operation of heating and cooling through 
 the thin tubes o o o may be effected with warm water, steam, or any other 
 heating medium; and cold water, or any other cooling medium. For this 
 purpose, the tubes o oo are united by a chamber and cock p p, by the opening 
 of which, with the pipes o o, hot and cold water may be alternately let in 
 and forced through by means of pumps, the cocks being worked in a similar 
 manner to those in steam engines. Now if hot water, say at 120, be let in 
 through the tubes of the receiver a, and cold water at the same time through 
 the receiver b, the liquid in the first receiver will operate with a force of about 
 90 atmospheres, while the liquid in the receiver b will only exert a force of 40 
 or 50 atmospheres. The difference between these two pressures will therefore 
 be the acting power, which through the medium of the oil will operate upon 
 the piston in the working cylinder. It is easy to comprehend that by letting 
 hot water through the receiver b, and cold water through the opposite one a, a 
 re-action will take place, which will produce in the working cylinder e an 
 alternate movement of the piston, applicable by the rod / to various mechani- 
 cal purposes, as may be required. It is to be observed, that the use of the 
 gasometer, and of the forcing pumps, is simply for obtaining the gas, and 
 for charging the receivers with the liquid. When the receiver is once 
 charged, and has been closed with the stop-cock h, the gasometer and forcing 
 pumps are to be disconnected from the receiver by unscrewing the pipe i at the 
 joint. The same pipe may however be used as the means of connecting the 
 receiver with the expansion vessel ; the adoption of two distinct pipes for these 
 purposes is intentionally avoided, as it would become necessary in consequence 
 to have two orifices as well as two stop-cocks. It is obvious that no difficulty 
 exists in connecting the forcing pump with both receivers, as the small pipes 
 used for that purpose may be made to reach either. 
 
 Several years have elapsed since the engine just described was patented, but 
 hitherto no machine upon the same principle has been brought into operation ; 
 and as the mechanical talents of Mr. Brunei are unquestionable, and as he is 
 known to have devoted much time to bring the invention to perfection, it is 
 probable that the cause of the want of success lies in the principle itself, and that 
 owing to one or both of the causes noticed in Mr. Tredgold's remarks upon the 
 subject, which we have quoted under the word GAS, the liquefiable gases are not 
 so applicable as mechanical agents as the vapour of water or steam. Another 
 difficulty attending such application arises from the very imperfect means we 
 are at present acquainted with of producing the degree of cold necessary for 
 the purpose of condensing the gases ; for the present, therefore, there seems 
 little hope of advantageously svibstituting these gases for steam as a prime 
 mover of machinery. 
 
 GAS VACUUM ENGINE. An engine working by the pressure of the 
 atmosphere, a partial vacuum being obtained by the combustion of hydrogeu 
 gas in a close vessel. The first person who proposed obtaining power b}' this 
 means we believe to have been the late Mr. Cecil, of Cambridge, who published 
 some account of his plan, the details of which we do not rightly recollect In 
 1 824 Mr. S. Brown took out a patent for an engine upon this principle, and at 
 that time the invention excited considerable interest, and was by many looked 
 wpon as likely to supersede the steam engine ; but although the inventor has since 
 been perseveringly employed, and at a great expense, to bring the machine to 
 perfection, we apprehend he has met with no great success, as the only instances 
 in which we have heard of it being brought into actual use was on one occasion
 
 GAS VACUUM ENGINE. 613 
 
 for raising water on the Surrey Canal, at Croydon, and at another time 
 for a similar purpose, upon a canal in Oxfordshire ; and very contradictory state! 
 
 ments prevailed respecting the performance of the engines upon these occa- 
 sions. The preceding engraving represents the engine as constructed for 
 4 i
 
 GH GATE. 
 
 raising water, which, by being led on to a water wheel, may also impart a rota- 
 tory motion to machinery; but this latter purpose may be effected by means 
 of pistons working in cylinders. The method of producing the vacuum is as 
 follows : inflammable gas is introduced along a pipe into an open cylinder or 
 vessel, whilst a flame placed on the outside, but near to the cylinder, is kept 
 constantly burning, and at times comes in contact with the gas therein, and 
 ignites it ; the cylinder is then closed air-tight, and the flame is prevented from 
 coming in contact with the gas in the cylinder. The gas continues to flow into 
 the cylinder for a period, and is then stopped off; during that time it acts 
 by Us combustion on the air within the cylinder, and, at the same time, a part 
 of the rarefied air escapes through one or more valves, and thus a vacuum is 
 effected ; the vessel, or cylinder, is kept cool by water. The two cylinders c. 
 and d are the vessels in which the vacuum is to be effected ; from these descen .1 
 the pipes gig and hjh, leading into the lower cylinders x x, from which the 
 water rises along those pipes to fill the vacuum cylinders alternately. The water 
 thus supplied is discharged through the pipes B into the tank or trough Z, 
 whence it falls upon the overshot water wheel, and by the rotatory motion thus 
 produced, gives power to any machinery which maybe connected with it. The 
 water runs from a wheel along a case surrounding the lower half into a reser- 
 voir v, from which the lower cylinders x x are alternately supplied. In order 
 to produce the vacuum, the gas is supplied to the cylinders by means of the 
 pipe k /c Jc attached to a gasometer. The gas also passes along the small pipe 
 II (communicating likewise with the gasometer), and being lighted at both ends 
 of that pipe is kept constantly burning for the purpose of igniting the ga.s 
 within the cylinders. The water in the reservoir v passing down one of the 
 pipes w into one of the lower cylinders x, causes the float y in that cylinder to 
 rise, and pushing up the rod o raises the end b of the beam, which of course 
 draws up with it the cap /, and forces down the cap e of the other cylinder c. 
 The gas being admitted along the pipe k, the flame from the pipe I is now 
 freely communicated to the gas in the cylinder, through the orifice, by the 
 opening of the sliding valve s, which is raised by the arm r, lifted by the rod 
 by means of the beam. To produce the intermitting action of each cylinder, 
 some intermediate machinery is put in operation by chains and rods attached to 
 a glass or iron vessel p, partly filled with mercury, and turning upon a pivot ; 
 each end receives its movements of elevation and depression from the rise and 
 fall of the projecting arms q, by the action of the beam above, the mercury 
 being employed for the purpose of regulating the supply of gas into" the cylin- 
 ders, and the movement of the slide in the trough v. By the action thus com- 
 municated the water from the reservoir flows down the pipe w into the vessel x, 
 and produces the elevation of the float y and of the rod n, and raises the cap c 
 by the ascent of the beam at a. The motion thus caused in this part of the 
 machinery acting upon its duplicate parts on the other side, of course produces 
 by its action a corresponding movement, and the slider in the trough v, moved 
 by the action of the mercurial tube p being moved from its position, allows the 
 water to fall into the pipe w, and as it ascends, suffers the float y to descend, 
 and rising into the main cylinder, thus lifts again the beam at b and its con- 
 nexions, and forces down the cap e on the top of the other cylinder. After the 
 vacuum is effected in the cylinders, the air must be admitted to allow the water 
 to be discharged, and the caps to be raised ; this is accomplished by means of a 
 sliding valve in the air-pipe m m, acted upon by chains 1 1 attached to floats in the 
 reservoir, and as motion is given to them, the valve is made to slide backwards 
 and forwards, so as to allow of the free admission of atmospheric air. Chains 
 M u with suspended weights open the cocks in the pipe k fc, and produce the 
 alternate flow of the gas, and regulate and modify its supply. In the pipes giy 
 and hj h, are docks to prevent the return of the water when the air is admitted 
 into the cylinders. 
 
 GATE, in Architecture, a large door leading or giving entrance into an open 
 area, as a field or court-yard, or into a considerable building, as a palace or 
 prison. An excellent method of hanging gates of large dimensions, has been 
 introduced by Mr. H. R. Palmer, which is a useful application of his suspen-
 
 GAUGES. 
 
 615 
 
 sion railway (see RAILWAY). The following cut represents some sliding or 
 rather rolling gates at each end of the northern avenue of the London Docks, 
 between the warehouses and the basin, forming not only a useful barrier to 
 prevent the intrusion of improper persons during the intervals of cessation* of 
 public business, but producing also an ornamental effect. During the hours of 
 business these gates are rolled back against the side walls of the end ware- 
 houses, to which they stand close and parallel, occupying no useful room. In 
 opening or shutting them nothing need be moved out of the way, and it is done 
 with great facility and dispatch. Being suspended entirely from above, and not 
 even touching the surface of the ground, it is not subjected to the adventitious 
 obstacles common to other gates, a a is intended to represent part of the wall 
 of the ranges of warehouses, and b the extremity of the range of sheds on 
 the opposite side of the avenue ; c c a double railway, extended entirely across 
 the avenue from a to b, and likewise to the width of a gate beyond on each 
 side ; it is supported by slightly curved arches of wrought iron, with ornamental 
 scroll-work between the arches and the double rail, the superstructure resting 
 upon lofty columns of cast-iron. One of three gates d (each of which fills up 
 
 the space between two columns) is shown in the act of being closed, by a man 
 pushing it along ; from its large dimensions and great weight (though chiefly 
 composed of wood) this could not be easily effected by the simple force of one 
 man, but being constructed on the principle of Mr. Palmer's patent railway, the 
 friction is reduced to very inconsiderable amount, the whole weight of each 
 gate being entirely suspended by iron rods to the axles of the little wheels 
 which run on the top of the railway, which are kept in their tracks by their 
 peripheries being flanged ; the gates do not rest upon or even touch the 
 ground, but are merely guided in their course by means of a projecting edge 
 fixed in their path : this will be easily explained by means of the annexed 
 diagram, which represents a transverse section 
 of these parts. // are two plates of iron, with 
 raised edges in the middle, which are screwed 
 down to open sleepers gg, and above these is 
 shown an edge view of the lower ends of the 
 gates, which run on either side of the column h. 
 
 Gates upon the same principle have been put up 
 
 at the court-yard at the Admiralty, and various I j ' 
 other public situations. U_J 
 
 GAUGE. An adjustable standard of measure 
 employed in various arts where a number of articles of the same kind are re- 
 quired to be as nearly as possible of the same dimensions. Gauges are various, 
 constructed according to the purposes to which they are to be applied. The 
 cut on the following page represents a gauge contrived by Mr. H. R. Palmer, 
 for the purpose of making a line along the centre of any parallel or tapering
 
 816 GAUGES. 
 
 solid. It answers all tie purposes of a common carpenter's gauge, whilst it is 
 peculiarly serviceable in other respects, for which the common gauge is wholly 
 inapplicable ; in making mortices, and enabling workmen to measure from a 
 centre line, and to work with greater accuracy and facility ; and in many other 
 cases it will be found a very convenient instrument, a is a square bar of hard 
 wood, having two sliding cheeks b d 
 fitted tightly to it; the cheek b is 
 fixed fast on one end of the bar, 
 whilst the other slides upon it, but it 
 may be made fast at any required 
 place by means of the thumb screw 
 c ; at the end b a common scribing 
 point is fixed in the bar, and with 
 this and the sliding piece d it forms 
 the common gauge used for drawing 
 parallel lines from the edge of any 
 piece of wood work. The addition 
 made by Mr. Palmer consists of the two brass arms f and g, of equal lengths, 
 and which are centered in the two sliding cheeks at aa; the other ends arc 
 jointed together by the screw h, which is formed into a sharp conical point 
 beneath to mark the work with. In using this gauge it is evident that the point 
 of the screw h will always keep in the centre between the two cheeks b d. If 
 the work is not parallel in its width, then the screw c must be loosened, and 
 the two cheeks b d must be kept pressed towards each other, so as to be in 
 contact with the sides of the work, when the point g will traverse along the 
 centre of the piece as correctly as if the sides were parallel, because in all 
 situations it preserves an equal distance from the two cheeks iandd; these 
 cheeks have grooves made in them to receive the brass arms/ and g when the 
 cheeks are brought into contact. 
 
 GAUGE, PRESSURE. An instrument to determine the pressure exerted in 
 hydrostatic or pneumatic machines, as the hydrostatic press, air pump, and 
 steam engine. When the pressure exerted is less than the pressure of the 
 atmosphere, as in the condenser of a steam engine, the gauge is usually termed 
 a barometer, and consists simply of a barometer tube, the lower end of which 
 plunges in a cup containing mercury open to the atmosphere, whilst the upper 
 end communicates with the condenser, and the degree of exhaustion or vacuum, 
 as it is usually termed, is measured by the altitude of the column of mercury in 
 the tube above the surface of the metal in the cup. When the pressure exerted 
 does not exceed two or three times the force of the atmosphere, it may be 
 measured by means of an inverted syphon or bent tube of wrought iron con- 
 taining a portion of mercury ; one leg of the tube communicates with the vessel 
 in which the pressure is exerted, and the other leg is open to the atmosphere, and 
 contains a float by which the rise of the mercury is indicated ; but when the 
 pressure is very great, a tube of sufficient length to support the corresponding 
 column of mercury would be extremely inconvenient, and it is usual then to 
 measure the pressure by the compression of a volume of air contained in a 
 glass tube, the upper end of which is sealed, whilst the communication of the 
 air in the tube with the chamber in which the pressure is exerted is intercepted 
 by a quantity of mercury in the lower part of the tube, and the pressure in the 
 chamber acting upon the surface of the mercury exposed to it causes the mer- 
 cury to rise in the tube, and to compress the air therein into a smaller space, 
 which space will be inversely, as the pressure exerted. The figure on page 617 
 represents a pressure gauge upon this principle, described in No. LXIII. of the 
 .Philosophical Magazine, by Mr. H. Russell. The gauge consists of a glass tube, 
 sealed at one end, with a ball blown very near the other, leaving only as much 
 beyond the ball as may be necessary for connecting it with the pipe leading 
 from the vessel containing the condensed steam or gas, or other elastic vapour. 
 This ball, when the tube is filled with air, and subject only to atmospheric 
 pressure, should be about three quarters full of mercury, and the whole capa- 
 city need not exceed that of the tube more than as two to one. That the
 
 GAUGES. 617 
 
 divisions in the scale may be in geometrical progression, the tube is placed in a 
 horizontal position ; this renders the instrument altogether so simple in appear- 
 ance, that persons totally unacquainted with instruments of this description, 
 may at once be brought to understand its nature, and be able to affirm with 
 confidence the degree of pressure to which it is subject. To determine 
 the degree of pressure at any point, ascertain the distance from the sealed end 
 of the tube, and by that measure divide the length contained between the 
 sealed end and the bulb, the quotient will be the number of atmospheres. Thus 
 in general terms, where T represents the whole tube, P the part into which the 
 column of air is compressed, and A the number of atmospheres, we have 
 
 p^zA. Thus, suppose the tube 8 feet long, and the column of air compressed 
 into half that length, then w have j=2 atmospheres. If this column be again 
 compressed into half its volume, it will be represented by ^=4 atmospheres ; if, 
 again, compressed into half its volume, we have j=8 atmospheres; if, again, 
 (8 feet=96 inches) g-= 16 atmospheres; and lastly, -3=32 atmospheres. In 
 the above figure the mercury chamber is blown in the tube itself, so that in this 
 
 Elan we have no joints whatever to make in the instrument ; and being placed 
 i a horizontal position at a convenient distance from the floor, all parts of the 
 scale may be examined with equal facility. For the internal diameter of the 
 tube, perhaps one-sixteenth of an inch will be found preferable. 
 
 GAUGE, RAIN. An instrument for showing the depth of rain or quantity 
 falling on a given surface at any place. These instruments are variously con- 
 structed ; the one shown in the engraving on the following page is the inven- 
 tion of Mr. Crossley, and is an elegant application of his patent liquid metre. 
 The principal parts of this machine, which are enclosed in a small box a a and b, 
 are, a small tin vessel or tumbler ef, which is divided into two equal parts by a 
 vertical partition, where it is supported by pivots on the upright stem I. The 
 pivots are placed below the centre of gravity of the tumbler, so that when it is 
 tilted (as represented in the engraving), it will remain in that position till the 
 upper half receives such a quantity of water as will overbalance it, when the 
 end c will be depressed by the weight of the water, and emptied ; the end / 
 will, in consequence, be elevated and brought under the spout to receive the 
 water until it becomes sufficiently loaded to preponderate, when it will again 
 take the position in the figure. Attached to this tumbler is a forked projection, 
 that at every change of position, acts on a lever at h, and thus communi- 
 cates motion to a train of wheels, which, by the index and the dial face i, is 
 made to register the number of times the divisions of the tumbler have been 
 filled. The rain is received and conveyed into the tumbler by the hopper- 
 shaped vessel c c, the mouth of which must be made of an area, having such a 
 relation to the other parts that the index will point out the number of inches 
 of rain falling on that extent of surface ; or, in other words, how deep the 
 water would have become had it remained on the surface of the earth during a 
 single shower, a day, a month, or even a year, if required, and this, too, without any 
 attention or care being bestowed upon it for the apparatus is so simple in con- 
 struction, that it is not subject to derangement of its parts; and as it registers 
 during the falling of the shower, it requires no estimation to be made of the
 
 618 
 
 GAUGING. 
 
 quantity of water evaporated between the falling of the rain and the time of 
 observation. 
 
 GAUGING. The art of measuring the capacities of all kinds of vessels 
 Gauging of course forms a part of mensuration, and is accordingly treated 
 of by most writers on that branch of science ; but as casks are seldom of any 
 exact mathematical forms, the rules laid down by such authors must be con- 
 sidered as merely theoretical ; and in practice, gauging is performed mechani- 
 cally, by means of the gauging or diagonal rod, or by the gauging sliding rule. 
 The diagonal or gauging rod is a rod or rule adapted for determining the con- 
 tents of the casks, by measuring the diagonal only ; viz. the diagonal from the 
 bung to the extremity of the opposite stave next the head. It is a square rule, 
 having four sides or faces, and is usually four feet long, and folds together by 
 means of joints. Upon one face of the rule is a scale of inches, for taking 
 the measure of the diagonal ; to these are adapted the areas, in gallons, of 
 circles to the corresponding diameters. Upon the opposite face is a scale, 
 expressing the contents of casks, having a corresponding diagonal ; and these 
 lines constitute the difference between the diagonal rods and the slide rules. 
 To use the diagonal rods, put the rod in at the bung hole of the cask, until its 
 end touch the opposite stave at the farthest possible distance from the bung- 
 hole, and note the inches and parts cut by the middle of the bung ; then draw 
 out the rod, and look for the same inches and parts on the opposite face of it, 
 and on them will be found the contents, in gallons. The sliding rule is similar 
 to the common sliding Gunters, (see GUNTER'S SCALE,) but having certain divi- 
 sors, or gauge points at different points of the scale, pointed out by small brass 
 pins, which divisors are the number of cubic inches in any particular measure, 
 as malt bushels, or imperial gallons, the casks are gauged approximately aa
 
 GAUGING. 619 
 
 cylinders, taking a mean diameter, for which purpose they are generally 
 reduced to what is called four varieties ; and if the difference between the head 
 and the bung diameters does not exceed six inches, their mean diameters may 
 be found by multiplying the difference of the first by -68 ; of the second, by 
 62 ; of the third, by -55 ; and of the fourth, by -5 ; the respective products of 
 these numbers, added to the head diameter, will make a mean diameter. 
 Having found a mean diameter, the contents are found by setting the length 
 of the cask upon the line marked B, on the brass slider, against the gauge- 
 point, for gallons, on the upper line A, upon the rule, and against the mean 
 diameter upon the lower line D ; upon the rule will be found the contents on 
 C upon the slider. On the back of the rule are four other lines, differently 
 marked. The first line is marked D, and is similar to the same line upon the 
 opposite side, and upon this line are set the circular gauge-point for wine, and 
 various other gauge-points ,- the second line is upon the slider it is marked C, 
 and is similar to the same line C upon the opposite face ; the third and fourth 
 lines on v his instrument are two lines of segments, for ullaging the casks, as it 
 is termed, that is, finding the contents of a cask, only partly full. One of these 
 lines is marked S S, for segment standing, and the other S L, for segment 
 lying ; these lines are set upon the rule, and are both numbered alike, from 1 
 to 10, and from 10 to 100. To find the ullage of a lying cask by the line of 
 segments, having the bung diameter, the depth of the liquid in inches, and the 
 contents of the cask, set the bung diameter on C to 100, on the line of seg- 
 ments marked S L, and opposite the depth of liquid on C wiil be a number on 
 the line of segment, which call the reserved number ; then set 100 on A to the 
 contents of the cask upon B, and against the reserve number before found upon 
 A is the contents of the cask upon B. To find the ullage of a cask standing, 
 substitute the length for the bung diameter, and the line S S, for the line S L, 
 and proceed as before. 
 
 To facilitate computations in gauging, Mr. W. Gutteridge has invented a 
 series of new units of measure, which has received the approbation of every 
 individual member of the Commission of Weights and Measures. These units 
 of measure are numbered 1, 2, 3, 4, 5, 6, 7, 8, No. 4 being the common 
 decimal foot, which is introduced to complete the series. These units are all 
 decimally subdivided into 100 equal parts, and are the roots of the cubic and 
 superficial measures in which the capacities of vessels, or solid contents of 
 bodies are reckoned, as gallons for liquids, and cubic feet for timber. By this 
 means, no division is necessary in computing contents or capacities, for the area 
 expressed in Mr. Gutteridge's system of notation multiplied by the depth gives 
 the contents ; whereas, when the dimensions are taken in inches, after multi- 
 plying the area by the depth, it is necessary to divide the product by the num- 
 ber of inches in a gallon or a foot to find the contents. Mr. Gutteridge's units 
 of measure, with their data, are as follows : 
 
 For imperial Gallons. 
 No. 1. ty 277-274. .....= 6-52083 Inches. = 1 Units. 
 
 2. ty 277-274 x \/ '-^ = 7-35784 = 1 
 
 3. ^ 277-|l = 7-0676 = 1 
 
 4. is the common foot. 
 
 For Feet. 
 
 No. 5. y -j.*. = 1-12836 Feet. = 1 Units. 
 
 6. iX'i- =1.08383 = 1 
 
 7 ' '4 =1-2732 =1 
 
 8. ^ 144 = 5-2415 Inches. = 1 ,,\ 
 
 In connexion with the subject of gauging, we may notice a singular circum- 
 stance related by Mr. Gutteridge. He had been called in to gauge a new vat 
 for Messrs. Booth & Co. distillers, and his own system was employed as affording
 
 620 
 
 GAUGING. 
 
 greater accuracy than the inch method in common use. After the dimen- 
 sions had been taken, a glass tube was fixed on the outside of the vat, for 
 reading off the quantities within, as a means of comparison with the interior 
 dip. That no difference might arise from the effect of capillary attraction, 
 the tube was made of more than an inch bore, and was fixed perpendicularly, 
 with a graduated scale placed closely, so that the zero of the scale coincided 
 with the top of the ungula, which exactly covered the bottom, without pro- 
 ducing any sensible depth of wet at the dipping place, from which it was 
 inferred that the interior dip, and the exterior indications of level would be 
 always the same ; and upon putting in several determined quantities, those 
 quantities were indicated by the tube exactly ; but a difference was afterwards 
 perceived between the interior dip and the exterior level, and the greater the 
 quantity, the greater the difference. The experiment was frequently repeated, 
 with every precaution to guard against error, one source of which was the 
 difference of temperature in the vat and in the tube, amounting in one 
 instance to 2J degrees, which would cause a difference of about -085 of an 
 inch, (the spirit being 41-6 per cent, over proof,) but to save computations 
 of this sort, the time chosen for the principal experiment was when the tem- 
 perature was alike. With 1400 gallons in the vat, the difference was about -f a of 
 an inch ; 2200 gallons more were then pumped in, and the difference increased 
 to | of an inch, and on adding 700 gallons more, the difference amounted to 
 1^ inch. It appearing highly improbable that the timbers could compress so 
 much more under the dipping place than under where the tube was 'fixed, a 
 level of the two.surfaces was taken, and, extraordinary as the fact may appear, 
 there was a difference found in the levels, of ~ of an inch, the liquid being 
 that much higher in the vat than the tube. This difference Mr. Gutteridge 
 imputes to a difference in the specific gravity of the spirit within the vat, and 
 that within the tube, and upon assaying them the former was found to be nearly 
 5 per cent, stronger than the latter. This variation must have been caused 
 by a greater evaporation on the tube, and it shows that with spirits of such 
 great strength, evaporation is very rapid, and cannot be too carefully guarded 
 against. The remaining difference between the dip and the level in the tube 
 Mr. Gutteridge supposes to have arisen from a compression of the timbers under 
 the dipping place. 
 
 The following diagrams of the vat, tube, and timbers, will render the subject 
 more intelligible. Fig. 1 represents a section of the vat, a b being the tube 
 fixed into a metal pipe b c, with a cock at c d, the level of the spirit in the 
 vat ; / the level in the tube, and h i the dipping place. Fig. 2. shows the sup- 
 
 ports of the^vat; B the back, and F the front, of which the seven similar parts 
 a a are the immediate rests, each four inches square ; b b b the three timbers 
 upon which the former rest, 10* inches deep, and 12$ broad; cc the two 
 sleepers upon which the beams are laid. The places ddddare supported upon 
 four upright -posts, and under k was placed another support; 2 the orifice for 
 the tube pipe, and o the dipping place.
 
 GEARING. 621 
 
 GAUZE. A thin, transparent kind of stuff, woven sometimes of silk, and 
 sometimes of thread. To warp the silk for the making of gauze, a peculiar 
 kind of mill is used, upon which the silk is wound : it is a wooden machine, 
 about six feet high, having an axis perpendicularly placed in the middle thereof, 
 with six large wings, on which the silk is wound from off the bobbins by the 
 axis turning round. When all the silk is on the mill, another instrument is 
 used to wind it off upon two beams ; this done, the silk is passed through as 
 many little beads as there are threads of silk ; and thus rolled on to another beam 
 to supply the loom. The gauze loom is much like that of the common weaver's, 
 though it has several appendages peculiar to itself. Some gauzes are wrought 
 into figures and flowers of gold and silver, upon a silk ground. 
 
 GEARING. A train of toothed wheels, for transmitting motions in 
 machinery. There are two sorts of gearing in common ; viz. spur gear and 
 beveled gear. In the former, the teeth are arranged round either the concave 
 or convex surface of a cylindrical wheel in the direction of radii from the 
 centre of the wheel, and are of equal depth throughout. In beveled gear, 
 the teeth are placed upon the exterior periphery of a conical wheel in a 
 direction converging to the apex of the cone, and the depth of the tooth 
 gradually diminishes from the base. For the rules for setting out these wheels, 
 and for the best form of teeth, we refer to the article MILL WORK, and shall, 
 in this place, only notice a new system of gearing, invented simultaneously 
 by Mr. Dyer, in America, and by Messrs. M'Dougall, of Ferry Bridge, 
 in Yorkshire, and communicated by the former gentleman to Mr. H. Burnett, 
 who took out a patent for the same. The object of this invention is to 
 obtain a great difference in the relative velocities of the wheel and pinion, by 
 a construction which in some respects resembles what is called a worm 
 wheel, or a wheel driven by an endless screw, but is at the same time free 
 from the objections attending the ordinary arrangement of the wheel and 
 endless screw. The common application of the wheel and endless screw is 
 in the direction of a tangent line, (or very nearly so) to the wheel to which 
 it is applied, and the force exerted upon it or by it, is constantly in a direc- 
 tion coincident with its longitudinal axis, and never in that of its radius, 
 whilst a rubbing action takes place between the threads of the screw and the 
 teeth of the wheel, thus producing excessive friction, not only at the point of 
 contact, but also against the pivot or resisting point of the screw. In the 
 patent gearing, the axis of the 'screw, or spiral pinion, is not a tangent tc the 
 wheel, but lies in the same plane as the axis of the wheel in ordinary gear, 
 whether it be spur gear or beveled gear. The consequence of this arrange- 
 ment is, that the power of the screw or spiral is exerted in the direction of its 
 radius ; consequently, it can be driven by the wheel with the same facility with 
 which the wheel drives it (difference of leverage, according to their respective 
 radii, excepted), which is not the case with the ordinary wheel and screw. 
 Another advantage is, that there being but one point of bearing in action at 
 once, and that uniformly on the line of centres, and that action passing uniformly 
 over equal spaces, m equal times, and in the same direction ; the action which 
 takes place between the wheel and the spiral pinion is not a sliding, but a perfect 
 rolling action, whereby nearly the whole of the friction which would otherwise 
 occur, is avoided. One valuable property of this invention is. that any required 
 strength may be given to the arbor, without affecting its power or velocity ; this 
 will be rendered evident by an inspection of Fig. 3 on the following page, in which 
 the external lines e e and //represent the sections of two arbors of very different 
 sizes, and consequently strengths, while their mechanical action is precisely similar, 
 for it will be seen that, notwithstanding the difference of magnitude in the two 
 sections, they have but one common pitch-line, marked i i in both figures, so 
 that both can work in the same wheel, and their power and velocity must be 
 equal. Fig. 4 represents the arbor or pinion engaged with the tooth of a wheel. 
 Another most important advantage belonging to this system of gearing, is the 
 simplicity which may be thereby introduced into machinery, and the consequent 
 diminution of friction ; for since each tooth of the wheel will be equivalent to 
 an entire revolution of the arbor, a great saving may be effected; thus, for 
 4 K
 
 622 
 
 GEARING. 
 
 instance, if a common wheel has 100 teeth, and works into a pinion of ten 
 leaves, the same power or velocity may be obtained by the new mode of gear- 
 .vheel of only ten teeth, working into one spiral groove upon 
 
 ing, by using a wl: 
 
 the arbor ; as an example of which Fig. 1 
 
 Fig. 2. 
 
 side, and Fig. 2 a front elevation 
 Fig. 1. 
 
 of a regulator clock, which is capable of showing hours, minutes, and seconds, 
 and will go for a whole year with once winding up, by a weight of only a few 
 pounds. The curve of the spiral groove on the arbor may be found by covering 
 the face of the wheel with a strip of thin paper, and marking the bevel of one 
 tooth upon it, when the extension of that tooth may be cut off and wrapped 
 round the arbor, which will give the form of the spiral, which may be marked 
 and cut ; but this is only a proximate method, and as the action of the improved 
 gearing, like that of all other gearings, depends mainly upon the perfect work- 
 ing of the teeth and grooves, it is better to cut the groove on the arbor, in a 
 regular and proper machine for cutting spirals and screws.
 
 GEOMETRY. 01>3 
 
 GFJ ATIN. An animal substance soluble in hot water, capable of assuming 
 a will known elastic or tremulous consistence by cooling, when the water is not 
 too al undant, and liquefiable again by increasing its temperature. This last 
 property distinguishes it from albumen, which becomes consistent by heat It 
 is precipitated in an insoluble form by tannin, and it is this action of tannin on 
 gelat'n which is the foundation of the art of tanning leather. 
 
 GEMS. This word is used to denote such stones as are considered by man- 
 kind as precious. These are, the dianiond, the ruby, sapphire, topaz, chrysolite, 
 beryl, emerald, hyacinth, amethyst, garnet, tourmalin, opal ; and to these may 
 be added, rock crystal, the finer flints of pebbles, cat's eye, hydrophanes, chal- 
 cedony, moon-stone, onyx, cornelian, sardonyx, agates, and Labrador stone, 
 for which, consult the several articles respectively. 
 
 GEOMETRY. One of the most important of the mathematical sciences ; 
 as it relates to the form, extension, and magnitude of bodies, and is conse- 
 quently the foundation of Mensuration. The most generally useful portion of 
 this science has been selected for our pages, which we here annex under the 
 usual distinctive appellation of Practical Geometry. 
 
 DEFINITIONS. A point is that which hath position, but not magnitude. 
 
 A line hath length, but not breadth or thickness, and may therefore be con- 
 ceived to be generated by the motion of a point. 
 
 A right line is what is commonly called a straight line, or that tends every 
 where the same way. 
 
 A curve is a line which continually changes its direction between its extreme 
 points. 
 
 Parallel lines are such as are equally distant from each other, and which, if pro- 
 longed ever so far, would never meet : such are the lines A B and C D, Fig. 1. 
 
 An angle is the space or corner between two lines meeting in a point, as 
 A B C, B denoting the vertex, or angular point 
 
 A right angle is represented when one line stands upon another, so as not to 
 lean more upon one side than upon the other, as in the angles A B C in Fig. 3 ; 
 all right angles are equal to each other, being all equal to 90 ; and the line 
 A B is said to be perpendicular to C D. 
 
 Fig. 3. 
 
 A X "*- 
 Fig. 1. 
 A -R 
 
 Beginners are very apt to confound the terms perpendicular, and plumb or 
 vertical line. A line is vertical when it is at right angles to the plane of the 
 horizon, or level surface of the earth, or to the surface of water, which is always 
 level. The sides of a house are vertical. But a line may be perpendicular to 
 another, whether it stand upright or incline to the ground, or even if it lie flat 
 upon it, provided only that it make the two angles formed by meeting with the 
 other line equal to each other ; as, for instance, if the angles ABC and A B D 
 be equal, the line A B is perpendicular to C D, whatever may be its position in 
 other respects. 
 
 When one line B E, Fig. 3, stands upon another, C D, so as to incline, the 
 angle E B C, which is greater than a right-angle, ia called an obtuse angle ; 
 and that which is less than a right angle, is called an acute angle, as the 
 angle E B D. 
 
 Two angles which have one leg in common, as the angles ABC and ABE, 
 are called contiguous angles, or adjoining angles ; those which are produced by 
 the crossing of two lines, as the angles E B D and C B F, formed by C D and 
 E F crossing each other, are called opposite or vertical angles.
 
 624 
 
 GEOMETKS. 
 
 A figure is. a bounded space, and is either a surface or a solid. 
 
 A superficies, or surface, has length and breadth only. The extremities of a 
 superficies are lines. 
 
 A surface may be bounded either by straight lines, curved lines, or both 
 these. Every surface, bounded by straight lines only, is called a polygon. If 
 the sides be all equal, it is called a regular polygon. If they be unequal, it is 
 called an irregular polygon. Every polygon, whether equal or unequal, has 
 the same number of sides as angles, and they are denominated sometimes 
 according to the number of aides, and sometimes from the number of angles 
 they contain. Thus, a figure of three sides is called a triangle, and a figure o r 
 four sides, a quadrangle. 
 
 A pentagon is a polygon of five sides. 
 
 A hexagon has six sides. 
 
 A heptagon has seven sides. 
 
 An octagon has eight sides. 
 
 A nonagon, nine sides. 
 
 A decagon, ten sides. 
 
 An undecagon, eleven sides. 
 
 A duodecagon, twelve sides. 
 
 When they have a greater number of sides, it is usual to call them polygons 
 of 13 sides, 14 sides, and so on. 
 
 Triangles are of different kinds, according to the length of their sides. 
 
 A right-angled triangle is that which has one right angle, as A B C, Fig. 1. 
 
 An acute-angled triangle, is a triangle which has all its sides acute, as Figs. 
 A and B. 
 
 An obtuse-angled triangle, is a triangle having one obtuse angle, as Fig. C. 
 
 An equilateral triangle, is a triangle having all its sides equal, as Fig. A. 
 
 An isoceles triangle, is a triangle having two equal sides, as Fig- B. 
 A scalene triangle, is a triangle having no two of its sides equal, as Fig. C. 
 Quadrangles or quadrilateral figures are of various denominations, as their 
 sides are equal or unequal, or as all their angles are right angles or not. 
 
 Every four-sided figure, whose opposite sides are parallel, is called a parallelo- 
 gram. Provided that the sides opposite to each other be parallel, it is 
 immaterial whether the angles be right or not. Figs. D E F and G, are all 
 parallelograms. 
 
 When the angles of a parallelogram are all right angles, it is called a 
 rectangular parallelogram, or a rectangle, as Figs. E and D. 
 
 A rectangle may have all its sides equal, or only the opposite sides equal. 
 When all its sides are equal, it is called a square, as Fig. D. 
 
 When the opposite sides are parallel, and all the sides equal to each other, but 
 the angles not right angles, the parallelogram is called a rhombus, as Fig. G.
 
 GEOMETRY. 625 
 
 A parallelogram, having all its angles oblique, and only its opposite equal, 
 is called a rhomboid, as Fig F. 
 
 When a quadrilateral, or four-sided figure, has none of its sides parallel, it is 
 called a trapezium, as Fig. H, consequently, every quadrangle or quadrilateral, 
 which is not a parallelogram, is a trapezium. 
 
 A trapeziod has only one pair of its sides parallel, as Fig. I. 
 
 A circle is a plane figure, bounded by a curve line returning into itself, called 
 its circumference, b de, Fig. O, every where equally distant from, a point within 
 the circle, which is called the centre, c. 
 
 The radius of a circle is a straight line drawn from the centre to the circum 
 ference, as c d, Fig. O. The radius is the opening of the compass when a circle 
 is described ; and consequently, all the radii of a circle must be equal to each 
 other. 
 
 A diameter of a circle is a straight line drawn from one side of the circum- 
 ference to the other through the centre, as a b, Fig. P. Every diameter divides 
 the circle into two equal parts. 
 
 A segment of a circle is a part of a circle cut off by a straight line drawn 
 across it. This straight line/ h, Fig. R, is called the chord. A segment may 
 be either equal to. greater, or less, than a semi-circle, which is a segment formed 
 by the diameter of the circle, and is equal to half the circle, as in Fig. P. 
 
 A tangent is a straight line, drawn so as just to touch a circle without cutting 
 it, as d e, Fig. T. The point where it touches the circle, is called the point of 
 contact ; and a tangent cannot touch a circle in more points than one. 
 
 A sector of a circle is a space comprehended between two radii and an arc, 
 as act, Fig. T. 
 
 The circumference of every circle, whether great or small, is supposed to be 
 divided into 360 equal parts, called degrees; and every degree into 60 parts, 
 called minutes ; and every minute into 60 seconds. To measure the inclina- 
 tion of lines to each other, or angles, a circle is described round the angulai 
 point, as a centre, as a b, Fig. T, and according to the number of degrees 
 minutes, and seconds, cut off by the sides of the angle, so many degrees, 
 seconds, and minutes, it is said to contain. Degrees are marked by , minutes 
 by ', and seconds by "; thus an angle of 48 degrees, 15 minutes, and 7 seconds 
 is written in this manner, 48 15' 7". 
 
 PROBLEM I. To divide a given line A B into two equal parts. 
 
 From the end of the line A and B, Fig. I, as centres, and with any opening 
 of the compasses greater than half A B, describe arches, cutting each other in 
 c and d. Draw the line c d; and the point E, where it cuts A B, will be the
 
 626 
 
 GEOMETRY. 
 
 middle required. This is often effected by practical men assuming a distance 
 as half, and setting off from each end of the line, and then bisecting the 
 space between the distances set off by the eye. 
 
 PROBLEM II. To raise a perpendicular to a given line A B, from a point 
 given at C. 
 
 Case 1. When the given point is near the middle of the line, on each side of 
 the point C, Fig. 2. Take any two equal distances, C dand C e; from d and e, 
 with any radius or opening of the compasses greater than C d or C e, describe 
 two arcs cutting each other in/. Lastly, through the points /, C, draw the 
 line fg, and it will be the perpendicular required. 
 
 Case 2. When the point is at, or near the end of the line, take any point d, 
 Fig. 3, on the side of the line on which the perpendicular is to be drawn, and 
 with the radius or distance d c, describe the arc e cf, cutting e B in e and c. 
 Through the centre d, and the point e, draw the line e df, cutting the arc 
 e cf in/. Through the points fc, draw the line fc, and it will be the per- 
 pendicular required. 
 
 PROBLEM III. From a given point/, to let fall a perpendicular upon a given 
 line A B. 
 
 Case 1. From the point/ Fig. 2, with any radius, describe the arc de, cutting 
 A B in e and d. From the points e d, with the same or any other radius, 
 describe two arcs, cutting each other in g. Through the points / and g draw 
 the line/*?, and/C will be the perpendicular required. 
 
 Case 2. If the point be nearly over the end of the line, from it as at/, Fig. 3, 
 draw a line e f obliquely to the other end; bisect ef, in d, and with the 
 radius d e draw the arc/c e, cutting the given line at c, to which the required 
 perpendicular from / is to be drawn. 
 
 Fig. 2. 
 
 Fig. 3. 
 
 PROBLEM IV. To make an angle equal to another angle which is given, as a B b. 
 
 From the point B, Fig. 4 with any radius, describe the arc a b, cutting the legs 
 B a, B b, in the points a and b. Draw the line D b, and from the point D, 
 with the same radius as before, describe the arc bf, cutting D b in b. Take the 
 distanced a, and apply it to the arc bf, from b to/. Lastly, through the points 
 D/ draw the line D/, and the angle b D/ will be equal to the angle b B , as 
 was required. 
 
 PROBLEM V. To divide a given angle, ABC, into two equal parts or angles. 
 
 From the point B, Fig. 5, with any radius, describe the arc A C. From A 
 and C, with the same, or any other radius, describe arcs cutting each other in d. 
 Drat? the line B d, and it will bisect the angle A B C as was required. 
 
 PROBLEM VI. To lay down an angle of any number of degrees. 
 
 There are various methods of doing this. One is by the use of an instrument 
 called a protractor, with a semicircle of brass, having its circumference divided
 
 GEOMETRY. 
 
 627 
 
 into degrees ; similar to Fig, 6. Let A B be a given line, and let it be required 
 to draw from the angular point A a line making, with A B, any number of 
 degrees, suppose 40. Lay the straight side of the protractor along the line A B, 
 and count 40 from the end B of the semicircle ; at C, which is 40 from B, 
 mark ; then, removing the protractor, draw the line A C, which makes, with 
 A B, the angle required. Or, it may be done by a divided line, usually drawn 
 upon scales, called a line of chords. Take 60 from the line of chords, in the 
 compasses, and setting one at the angular point B, PROB. IV., with that open- 
 ing as a radius, describe an arch, as a b : then take the number of degrees of 
 which you intend the angle to be, and set it from b to a, then is a B b the angle 
 required. 
 
 Fig. 4. 
 
 Fig. 5. 
 
 Fig. 6. 
 
 PROBLEM VII. T/irough a given point C, to draw a line parallel to a given 
 line A B. 
 
 Case 1. Take any point d, in A B, Fig. 7, upon d and Cftoith the distance 
 C d, describe two arcs, e C, and df, cutting the line A B, in e and d. Make 
 df equal to e C; through C and /draw C/, and it will be the line required. 
 
 Case 2. When the parallel is to be at a given distance from A B. From 
 any two points c and d, in the line A B, with a radius equal to the given dis- 
 tance, describe the arcs e and /.- draw the line C B to touch those arcs without 
 cutting them, and it will be parallel to A B, as was required. 
 
 Fig. 7. 
 
 PROBLEM VIII. To divide a given line A B, tnto any proposed number of 
 equal parts. 
 
 From A, Fig. 8. one end of the line, draw A C, making any angle with A B ; 
 and from B, the other end, draw B 9 parallel to A C, making the angle A B 9 
 equal to B A C. In each of these lines A C, B 9, beginning at A and B, set off 
 as many equal parts, of any length, as A B is to be divided into. Join the 
 points C 5 ; 4,6; 3,7; and A B will be divided as required. 
 
 PROBLEM IX. To find the centre yf a given circle. 
 
 Draw any chord A B, Fig. 9, and bisect it with the perpendicular C D. Bisect 
 C D with the diameter E F, and the intersection O will be the centre required. 
 Or the intersection of two lines drawn perpendicularly through two of its 
 chords, will be the centre of a circle.
 
 628 
 
 GEOMETRY. 
 
 PROBLEM X. To draw a tangent to a given circle that shall pass through a given 
 
 point, A. 
 
 From the centre O, Fig. 10, draw the radius O A. Through the point A, 
 draw D F perpendicular to O A, and it will be the tangent required. 
 
 Fig. 9. 
 
 Fig. 10. 
 
 Fig. 8. 
 
 PROBLEM XI. To draw a tangent to a circle, or any segment of a circle A B L> 
 through a given point B, without malting use of the centre of the circle. 
 
 Take any two equal divisions upon the circle, Fig. 11, from the given point B 
 towards d and e, and draw the chord e B. Upon B, as a centre, with the dis- 
 tance B d, describe the arc fdg, cutting the chord e B in /. Make dg equal 
 to df; through g draw g B, and it will be the tangent required. 
 
 PROBLEM XII. Given three points, A, B, C, not in a straight line, to describe c 
 circle that shall pass through them. 
 
 Bisect the lines A B, BC, Fig. 12, by the perpendiculars a b, la, meeting 
 at d. Upon d, with the distance d A, d B, or d C, describe ABC, and it will 
 be the required circle. 
 
 Fig. 12. 
 
 PROBLEM XIII. To describe the segment of a circle to any length A B, and 
 A __ _ height C D. 
 
 Bisect A B, Fig. 13, by the perpendicular D g, cutting A B in c. From c 
 make c D, on the perpendicular, equal to C D. Draw A D, and bisect it by 
 
 J* __!_ ^ ..' T-v - _ TT A 1_ i_- J !1_ _ A -\ T> -1 
 
 a perpen 
 it will be 
 
 dicular 
 
 ic perpenc 
 ef, cuttin 
 
 be the required segment. 
 Fig. 13. 
 
 g Dg in g. Upon g the centre, describe A D B, and 
 
 Fig. 14.
 
 GEOMETRY. 
 
 629 
 
 PROBLEM XIV. To describe the segment of a circle by means of two rules, to 
 any length A B, and perpendicular Jieight C D, in the middle of A B, witiioitt 
 making use of the centre. 
 
 Place the rules to the height at C, Fig. 14; bring the edges close to A and 
 B ; fix them together at C, and put another piece across them to keep them 
 fast. Put in pins at A and B, then move the rulers round these pins, holding a 
 pencil at the angular point C, which will describe the segment. 
 
 PROBLEM XV. In any given triangle to inscribe a circle. 
 Bisect any two angles A and C, Fig. 15. with the lines A D and D C. From 
 D, the point of intersection, let fall the perpendicular D E ; it will be the radius 
 of the circle required. 
 
 PROBLEM XVI In a given square, to describe a regular octagon. 
 Draw the diagonals A B and C D, Fig. 16, intersecting ate. Upon the points 
 A, B, C, D, as centres, with a radius e C, describe the arcs hel,ken,meg,fe i. 
 Join/n, mh, &i, Ig, and it will be the required octagon. 
 
 PROBLEM XVII. In a given circle, to describe any regular polygon. 
 Divide the circumference into as many parts as there are sides in the polygon 
 to be drawn, and join the points of division. Or divide 360 by the given 
 number of sides, and set off from the radius of the circle, an angle equal to the 
 quotient, and its chord will be one side of the polygon, Fig. 17. 
 
 Fig. 15. Fig. 16. Fig. 17 
 
 PROBLEM XVIII. Upon a given straight line, A B, to form a polygon of any 
 
 number of sides. 
 
 Produce the side A B to P, Fig. 18, and on A P from the centre B describe 
 a semicircle A C P ; divide the senucircumference A C P into as many equal 
 parts as the number of sides intended ; through the second division, from P, 
 draw the line B C ; bisect A B and P C by perpendiculars cutting each other 
 in S ; from S with the radius A S, B S, or C S, describe a circle A B C D E, 
 then carry the side A B or B C round the remaining part of the arc, which will 
 be found to contain the remaining sides of the number required. Fig. 18 is 
 an example of a pentagon ; we shall give in Fig. 19 an example of a hexagon, 
 as in this figure we need not proceed by the general method : we have only to 
 make a radius of the given side A B, and take the points A and B as centres; 
 form the arcs A G and B G, and strike a circle with the radius G A or G B, 
 which will contain the six sides. 
 
 Fig. 18. 
 
 Fig. 19. 
 
 f
 
 630 
 
 GEOMETRY. 
 
 PROBLEM XIX. Upon a given line A B, to construct an equilateral triangle. 
 
 Upon the points A and B, Fig. 20, with a radius equal to A B, describe arches 
 cutting each other at C. Draw A C and B C, and ABC will be the triangle 
 required. 
 
 PROBLEM XX. To make a triangle, whose sides shall be equal to three given 
 lines D E F, any two of them being greater than the third. 
 
 Draw A B, Fig. 21, equal to the line D. Upon A, with the radius F, describe 
 an arc C D. Upon B, with the radius E, describe another arc intersecting the 
 former at C. Draw A C and C B, and A B C will be the triangle required. 
 
 Fig. 20. 
 
 
 Fig. 21. 
 
 PROBLEM XXL To make afgure equal and similar to a given irregular figure, 
 A BCD. 
 
 Divide the given figure as A B C D, Fig. 22, into two or more triangles, by 
 the diagonal D B. Make E F equal to A B ; upon E F construct the triangle 
 E F H, whose sides shall be respectively equal to those of the triangle A B D, 
 by the last problem. Upon H F, which is equal to D B, construct the triangle 
 H F G, whose sides are respectively equal to D B C, then E F G H will be the 
 figure required. 
 
 A figure having more than four sides must necessarily be divided into more 
 than two triangles. 
 
 PROBLEM XXII. To make a square equal to two given squares. 
 Make the sides D E and D F, Fig 23, of the two given squares A and B, on 
 opposite sides of the same straight lines, they will form the sides of a right- 
 angled triangle F D E ; draw the hypothenuse F E ; on it describe the square 
 E F G H, and it will be the square required. 
 
 Fig. 23. 
 
 PROBLEM XXIII. Two right lines A B, CD, being given, to find a third 
 
 proportional. 
 
 Make an angle H E I. Fig. 24, at pleasure ; from E make E F equal to A B, 
 and E G equal to C D : join F G. Take E I equal to E F, and draw H I parallel 
 to F G; then E H will be the third proportional required ; that is, E F: EG:: 
 EH: El, or AB: CD:: CD: El
 
 GEOMETRY. 
 
 631 
 
 PROBLEM XXIV. Three lines being given, to find a fourth proportions. 
 Draw G H and G I, Fig. 25, making any angle H G I ; take G H equal to 
 A B, G I equal to C D, and draw H I. Make G K equal to E F ; draw K L, 
 through K, parallel to H I ; then G L will be the fourth proportional required, 
 that isGH:GI::GK:GL, orAB:CD::EF:GL. 
 
 PROBLEM XXV. To divide a given line A B, in the same proportion as another 
 
 CD, is divided. 
 
 Make any angle K H I, Fig. 26, and make H I equal to A B ; then apply the 
 several divisions of C D, from H to K, and join K I. Draw, parallel to I K, 
 the lines e,f, g, h, i, k, I, by which the line H 1 will be divided as was required. 
 
 Fig. 24. 
 
 Fig. 25. 
 
 Fig. 26. 
 
 PROBLEM XXVI. Between two given lines A B and C D, to find a mean 
 
 proportional. 
 
 Draw the right line E G, Fig. 27, in which make E F equal to A F, and F G 
 equal to C D. Bisect E G in H, and with H E or H G, as radius, describe 
 the semicircle E I G. From F draw F I perpendicular to E G, cutting the 
 circle in I ; and I F will be the mean proportional required. 
 
 PROBLEM XXVJI. To describe an ellipsis. 
 
 If two pins be fixed at the points E and F, Fig. 28, a string being put about 
 them, and the ends tied together at C ; the point C being moved round, keeping 
 the string stretched, will describe an ellipsis. 
 
 The points E and F, where the pins were fixed, are called the foci. 
 
 The line A B passing through the foci, is called the transverse axis. 
 
 The point G bisecting the transverse axis, is the centre of the ellipsis. 
 
 The line C D crossing this centre at right angles to the transverse axis, is 
 the conjugate axis. 
 
 The latus rectum is a right line passing through the focus at F, at right 
 angles to the transverse axis terminated by the curve : this is also called the 
 parameter. 
 
 A diameter is any line passing through the centre, and terminated by the 
 curve. 
 
 A conjugate diameter to another diameter, is a line drawn through the centre, 
 parallel to a tangent, at the extreme of the other diameter, and terminated by 
 the curve. 
 
 A doubk ordinate is a line drawn through any diameter parallel to a tangent, 
 at the extreme of that diameter terminated by the curve. 
 
 Fig. 27. Fig. 28.
 
 C32 
 
 GEOMETRY. 
 
 PROBLEM XXVIII. TJie transverse axis A B, and conjugate axis CD of any 
 ellipsis, being given, to find the two foci, and from thence to describe the ellipsis. 
 Take the semi-transverse, A E, or E B, Fig. 29, and from C as a centre, 
 describe an arc, cutting A B at F and G, which are the foci. Fix pins in these 
 points ; a string being stretched about the points, F, C, G, the ellipsis is described 
 as above. 
 
 PROBLEM XXIX. The same being given, to describe an ellipsis by a trammel. 
 
 The trammel, Fig. 30, is an instrument consisting of two rulers fixed at right 
 angles to each other, with a groove in each. A rod, with two movable nuts, 
 works in this groove, and, by means of a pencil fixed in the end of the rod, 
 describes the curve. The operation is as follows : Let the distance of the first 
 pin at B, from the pencil at A, be equal to half the shortest axis, and the dis- 
 tance of the second pin at C, from A, to half the longest axis ; the pins being 
 put in the grooves, move the pencil at A, which will describe the ellipsis. 
 
 Fig. 29. 
 
 Fig. 30. 
 
 PROBLEM XXX. To describe an ellipsis similar to a given one A D BC, to any 
 
 given length IK, or to a given width, M L. 
 
 Let AB and CD, Fig. 31, be the two axes of the given ellipsis. Through 
 the points of contact A, D, B, C, complete the rectangle G E H F ; draw the 
 diagonals E F and GH : they will pass through the centre at R. Through I 
 and K draw P N and O Q parallel to C D, cutting the diagonals E F and G H, 
 at P, N, Q, O. Join P O and N Q, cutting C D at L and M ; then I K is the 
 transverse, and M L the conjugate axis of an ellipsis, that will be similar to 
 the given ellipsis A D B C, which may be described by some of the foregoing 
 methods. 
 
 PROBLEM XXXI. To describe a parabola. 
 
 If a thread equal in length to B C be fixed at C, Fig. 32, the end of a square 
 ABC, and the other end be fixed at F ; and if the side A B of the square 
 be moved along the line A D, and if the point E be always kept close to the 
 edge B C of the square, keeping the string tight, the point or pin E will describe 
 a curve E G I H, called a parabola. 
 
 Fig. 32.
 
 GEOMETRY. 
 
 633 
 
 The focus of the parabola is the fixed point F, about which the string revolves. 
 
 The directrix is the line A D, which the side of the square moves along. 
 
 The axis is the line L K, drawn through the focus F, perpendicular to the 
 directrix. 
 
 The vertex is the point I, where the line L K cuts the curve. 
 
 The latus rectum or parameter, is the line G H passing through the focus F, 
 at right angles to the axis I K, and terminated by the curve. 
 
 The diameter is any line M N, drawn parallel to the axis I K. 
 
 A double ordinate is a right line R S, drawn parallel to a tangent at M, the 
 extreme of the diameter M N, terminated by the curve. 
 
 The abscissa is that part of a diameter contained between the curve and its 
 ordinate, as M N. 
 
 PROBLEM XXXII. To describe a parabola, by finding points in the curve; the 
 
 axis A B, or any diameter being given, and a double ordinate C D. 
 Through A draw E F. Fig. 33, parallel to C D ; through C and D draw D F 
 and C E parallel to A B, cutting E F at E and F. Divide B C and B D, each 
 into any number of equal parts, as four ; likewise divide C E and D F into the 
 same number of equal parts. Through the points 1, 2, 3, &c. in C D, draw the 
 lines 1 , 2 b, 3 c, &c. parallel to A B ; also through the points, 1, 2, 3, &c. in 
 C E and D F, draw the lines 1 A, 2 A, 3 A, cutting the parallel lines at the 
 points a, b, c ; then the points a, b, c, are in the curve of the parabola. 
 
 PROBLEM XXXIII. TV describe an hyperbola. 
 
 If B and C, Fig. 34, be two fixed points, and a ruler A B be made movable 
 about the point B, a string ADC being tied (to the other end of the rule, and 
 to the point C ; and if the point A be moved round the centre B, towards G, 
 the angle D of the string ADC, by keeping it always tight, and close to the 
 edge of the ruler A B, will describe a curve D H G, called an hyperbola. 
 
 Pip. 34. 
 
 Fig. 35. 
 
 If the end of the ruler at B were made movable about the point C, the string 
 being tied from the end of the rule A to B, and a curve being described after 
 the same manner, is called an opposite hyperbola. 
 
 The foci are the two points B and C, about which the ruler and string 
 revolve. 
 
 The transverse axis is the line I H terminated by the two curves passing 
 through the foci, if continued. 
 
 The centre is the point M, in the middle of the transverse axis I H. 
 
 The conjugate axis is the line N O, passing through the centre M, and termi- 
 nated by a circle from H, whose radius is M C, at N and O. 
 
 A diameter is any line VW, drawn through the centre M, and terminated by 
 the opposite curves.
 
 634 GILDING. 
 
 Conjugate diameter to another, is a line drawn through the centre, parallel to 
 a tangent with either of the curves, at the extremity of the other diameter 
 terminated by the curves. 
 
 Abscissa is when any diameter is continued within the curve, terminated by 
 a double ordinate and the curve ; then the part within is called the abscissa. 
 
 Double ordinate is a line drawn through any diameter parallel to its conjugate, 
 and terminated by the curve. 
 
 Parameter, or latus rectum, is a line drawn through the focus, perpendicular 
 to the transverse axis, and terminated by the curve. 
 
 PROBLEM XXXIV. To describe an hyperbola by finding points in the curve, 
 having the diameter or axis A B, its abscissa B Cr, and double ordinate D C. 
 Through G draw E F, Fig. 35, parallel to C D ; from C and D draw C E 
 and D F, parallel to B G, cutting E F in E and F. Divide C B and B D, each 
 into any number of equal parts, as four ; through the points of division, 1, 2, 3, 
 draw lines to A. Likewise divide E C and D F into the same number of 
 equal parts, viz. four ; from the divisions on C E and D F, draw lines to G ; a 
 curve being drawn through the intersections at G, a, b, &c. will be the hyper- 
 bola required. 
 
 GILDING. The art of applying to various substances an extremely thin 
 coating of gold. If the substances to be gilt be metallic, this is effected by 
 simple adhesion of the surfaces ; but if not, the gold is attached by means of 
 some adhesive medium. The simplest of all the kinds of gilding on metal is 
 that by which copper or silver wire is gilt. The bar, before it is given to the 
 wire drawer, is plated with gold by having several layers of gold leaf burnished 
 down upon them whilst hot ; and being then subjected to the stronger compres- 
 sion which takes place in wire drawing, the gold and the other metal become 
 so perfectly united as to form, in fact, one substance ; but the most usual way 
 of covering the face of metals with gold is by means of an amalgam, or, as it 
 is technically termed, water gilding. If the metal to be gilt be silver, it is first 
 soaked in warm muriatic acid, that the surface may be rendered perfectly clean, 
 and then washed in clean water, changed two or three times to get rid of the 
 whole of the acid ; being afterwards dried and made moderately warm, a little 
 gold amalgam, also warm, is to be carefully and evenly spread upon the silver, 
 to which it will immediately adhere. The plate is then placed upon a con- 
 venient support over a charcoal fire, and the mercury is driven off by heat, 
 when the plate will be found entirely covered with a thin coating of pale dull 
 gold. The small roughnesses are now to be removed with a scratching brush, 
 composed of extremely fine brass wire, which renders the surface perfectly 
 smooth and bright ; after which the colour is heightened by warming the piece 
 and smearing it over with gilder's-wax, which is a composition of bees'-wax, 
 red ochre, verdigris, and alum. The wax being burnt off over a charcoal fire, 
 and the piece quenched in urine, the colour of the gilding will be found to be 
 much heightened, after which it may be burnished or not, as may be desired. 
 The affinity of copper and its alloys not being so great as that of silver for 
 mercury, the adhesion of the amalgam is promoted by the action of nitric acid 
 in the following manner : the piece of copper, a button for instance, after 
 being cleaned and burnished, is dipped in a solution of nitrate of mercury, 
 which, owing to the superior affinity of the copper for the nitric acid, is quickly 
 decomposed, and the mercury becomes deposited in a metallic state over the 
 whole surface of the copper, to which it strongly adheres ; the gold amalgam 
 is now applied, and the rest of the process goes on as already described. Gild- 
 ing is rarely applied to other metals than silver, copper, and the alloys of 
 the latter metal. There are two methods of gilding wood, viz., oil gilding and 
 burnished gilding. Oil gilding is thus performed : the wood is first primed or 
 covered with two or three coatings of boiled linseed oil and white lead, to fill 
 up the pores of the wood, and to render the surface smooth and even. When 
 the priming is quite dry, a thin coat of gold si/e must be laid on ; this is pre- 
 pared by grinding together some strongly calcined red ochre with the thickest 
 drying oil that can be procured ; and previous to using it, it must be mixed with
 
 GLASS. 635 
 
 a little oil of turpentine, that it may work freely. When the gold size is suf- 
 ficiently dry. leaf gold, cut into strips, is taken up by the point of a fine brush 
 and applied to the parts to be gilded, and is then gently pressed down by a ball 
 of soft cotton ; the gold instantly adheres to the sticky surface, and, after a few 
 minutes, the dexterous application of a camel's-hair brush sweeps away the 
 loose particles of gold leaf without disturbing the rest. In a day or two the 
 size will be perfectly dry, and the operation is then finished. This method is 
 simple and durable, but will not admit of burnishing, and therefore wants the 
 high* lustre produced by the next process : it is chiefly used for out-door work. 
 Burnished gilding, or gilding in distemper, is thus performed : the surface to 
 be gilt must be first covered with a thick coating of strong parchment size ; 
 this coating being dried, eight or ten more must be applied, consisting of the 
 same size, mixed with fine plaster of Paris or washed chalk ; and when the whole 
 is perfectly dry, a moderately thick layer must be applied of size, mixed with bole 
 or yellow ochre. While this last is yet moist the gold leaf is to be put on in the 
 usual manner ; it will immediately adhere on being pressed by the cotton ball, 
 and before the size is perfectly dry, those parts which are intended to be most 
 brilliant are to be carefully burnished with an agate or dog's tooth. This kind of 
 gilding will not withstand rain or even damp, and is therefore only applied to 
 ia-door work, as picture frames, &c. ; it may be cleaned with a soft brush and 
 hot spirit of wine, or oil of turpentine. 
 
 GIMBALS, in Sea Affairs, the brass rings by which a sea compass is sus- 
 pended in its box, forming a universal joint upon the principle of Hooke's, so 
 as to counteract the effect of the ship's motion, and t , keep the card hori- 
 zontal. 
 
 GIN, in Mechanics, a machine for driving piles, fitted with a windlass and 
 winches at each end, at which eight or nine men heave the rope from the 
 barrel or windlass, passing over the wheel at the top. 
 
 GLAIR. The white of eggs used as a varnish for paintings ; for this pur- 
 pose it is beaten to an unctuous consistence, and commonly mixed with a little 
 spirit of wine to make it work freely, and a little lump of sugar, to give it body 
 and prevent it from cracking; it is then evenly spread over the picture with a 
 fine brush. 
 
 GLASS. A well-known transparent and brittle factitious substance, of which 
 the basis is silica, brought into complete fusion by the addition of one of the 
 fixed alkalies. There are several different kinds of glass, adapted to different 
 uses. The best and most beautiful, are the flint and the plate glass ; these, 
 when well made, are perfectly transparent and colourless, heavy and brilliant. 
 They are composed of fixed alkali, pure silicious sand, calcined flints, and 
 litharge, in different proportions. The flint glass contains, likewise, a large 
 quantity of oxide of lead, which, by certain processes, is easily separated. 
 
 Crown glass is that used for windows, and is made without lead, chiefly of 
 fixed alkali fused with silicious sand, to which is added some black oxide of 
 manganese, which is apt to give the glass a tinge of purple. 
 
 Bottle glass is the coarsest and cheapest kind; into this little or no fixed alkali 
 enters the composition : in this country it is composed of sand, and the refuse 
 of the soap boiler, which consists of the lime employed to render his alkali 
 caustic, and of the earthy matters with which the alkali was contaminated. The 
 most fusible is flint glass, and the least fusible is bottle glass ; flint glass melting 
 at the temperature of 10<> Wedgwood, crown glass at 30, and bottle glass at 
 47. Although glass when cold is exceedingly brittle, when heated to redness 
 it becomes one of the most ductile bodies known, and may be drawn into 
 threads so very delicate as to become almost invisible to the human eye : it is 
 extremely elastic, and one of the most sonorous of bodies. In making glass, 
 the materials undergo a preparatory process called fritting, which consists in 
 mixing them in the proper proportions, and submitting them to a moderate 
 heat for six hours, by which they are reduced to a pasty consistence, and form 
 what is called frit, which is cut into squares^ and stored up for use ; and as 
 the quality of the glass depends upon the age of the frit, the principal manu- 
 facturers endeavour always to keep a considerable stock of frit on hand. This
 
 636 GLASS. 
 
 frit is introduced into large pots made of prepared clay, and in these is exposed 
 to a heat sufficient to melt it completely. When the fusion has continued the 
 proper time, the furnace is allowed to cool a little ; in this state the glass is 
 exceedingly ductile, and will assume any shape, according to the fancy of the 
 workman. The vessels thus formed must not be permitted to cool very 
 quickly ; hence they are put into a furnace, that the heat may pass off very 
 gradually, and this is called " annealing." Having said thus much to give a 
 general idea of the process, we shall now proceed to describe, somewhat in 
 detail, the manual operations in the manufacture of glass; observing that, 
 owing to the excise laws, the different branches of the manufacture, viz. crown, 
 flint, plate, and bottle glass, are not carried on at the same works, but require 
 to be in separate establishments ; we shall, therefore, select for description the 
 manufacture of flint glass, by which the various utensils in glass are produced. 
 The other branches differ principally in the number and arrangement of thefur- 
 naces ; but in all of them, with the exception of plate glass, the glass is brought 
 into the desired form principally by means of a blowing pipe : the operation is 
 exceedingly simple : the workman has a tube of iron, the end of which he dips 
 into a pot of melted glass, and thus gathers a small quantity of it on the end 
 of the tube ; he then applies the other end of the tube to his mouth, and blows 
 air through it ; this air enters into the body of the fluid glass, and expands it 
 out into a hollow globe similar to the soap bladders blown from a tobacco pipe, 
 and by varied management of these globes while in a soft state, and with the 
 aid of a few simple tools, they are reduced into the forms of the different ves- 
 sels in common domestic use. The first thing to be described is the furnace : 
 it consists of two large domes set one over the other ; the lower one stands 
 over a long grating, which is on a level with the ground ; on this grating the 
 fuel is laid, and beneath it is a large arch, by which the air is admitted, and by 
 which the ashes may be removed. In the sides of the lower dome as many 
 holes or mouths are made as there are workmen to make use of the furnace, 
 and before each mouth a pot of melted glass is placed ; the pots are very large, 
 like crucibles, and will hold from three to four hundred-weight of liquid glass ; 
 they are supported upon three small piers of brickwork, resting on the floor of 
 the furnace. The form reverberates the flame from the roof down upon the 
 pots, and they are placed at some distance within the furnace, that the flame 
 may get between the wall and the pots. The upper dome is built upon the 
 other, and its floor made flat by filling up round the roof of the lower dome 
 with brickwork ; there is a small chimney opens from the top of the lower dome 
 into the middle of the floor of the upper one, which conveys the smoke away 
 from it, and a flue from the upper dome leads it completely from the furnace ; 
 the upper dome is used for annealing the glass, and is exactly similar to a large 
 oven ; it has three mouths, and in different parts a small flight of steps leads 
 up to each. The implements employed in the formation of glass vessels are 
 few and simple ; the following are the principal : a blowing-pipe, which is 
 simply a tube of wrought iron about three feet long, and covered with twine 
 towards the mouth-piece, pliers and calliper compasses, a pair of common 
 shears to cut the glass, a very coarse flat file, and several small iron rods ; 
 there is also a bench or stool with two arms, another stool or table with a 
 smooth cast-iron plate upon it, and upon the ground behind this stool is another 
 plate of iron. 
 
 We shall now proceed to describe, somewhat more minutely, the manufac- 
 ture of flint glass. The melting pots are charged with frit, thrown in by 
 shovelsful from time to time, allowing each portion to melt before a fresh 
 quantity is added. When the whole is converted into a clear transparent glass, 
 and is become perfectly pure and free from particles of sand or bubbles of air, 
 the gatherers and blowers commence operations, and continue working night 
 and day until the batch is exhausted. The process of blowing is varied accord' 
 ing to the form of the piece to be manufactured ; to illustrate it, it will be suf- 
 ficient to describe the method in which a wine glass is formed. When the 
 blower has received from the gatherer the blowing pipe charged with a sufficient 
 quantity of metal, he seats himself in a chair provided with two arms or elbows,
 
 GLASS. 637 
 
 one of which is plated with iron, and placing the blow pipe across the elbows, 
 so that the heated end may rest on the iron plate, having first formed the glass 
 into a hollow ball, he rolls the pipe backwards and forwards, and laying hold 
 of the glass on the farther side of the ball with a small pair of pliers, draws 
 it out to form the stalk of the glass, while :he part next the blow pipe is 
 fashioned into the bowl. In the mean time another blower, having formed a 
 smaller ball, opens it by a sharp cut, and presses it while red hot against the 
 end of the stalk held by the former workman, to which it immediately adheres; 
 the workman then with a piece of iron, which he wets with his mouth, touches 
 the globe intended for the bowl of the glass, which is still very hot, although so 
 much chilled as to retain its shape ; in a second or two it cracks all round, and 
 by giving it a gentle knock it is detached from the blowing pipe. The workman 
 then instantly heats it, and with a pair of shears cuts the mouth smooth 
 and even ; but as the shears have put the glass out of the circular form, he heats 
 it again, and by a dexterous twirl and swing round his head gives it the 
 desired shape almost without the use of any tools. The wine glass now finished, 
 the iron at the foot is detached by a smart blow, and the glass is carried by a 
 boy, upon a long forked iron, to the annealing oven. After the glass is annealed 
 it may be required to be cut before it is ready for sale : this, when the articles 
 are small, and can be easily held in the hand, is performed upon small grit 
 grindstones, or by circular plates of iron, revolving in troughs of sand and 
 water; and for beaded mouldings, as upon decanters, a corresponding groove is 
 formed upon the periphery of the plate. The operations are concluded by 
 polishing the cut parts by means of revolving straps covered with polishing 
 powder. 
 
 In the manufacture of bottle glass, after the metal is brought into fusion, 
 which requires an intense heat during eighteen hours, it is reduced to the work- 
 ing temperature, which is steadily maintained by a due supply of fuel, and 
 being scummed, is ready for blowing. For carboys and similar articles it is 
 merely blown into a globular form ; but for common wine bottles, or for square 
 or octagonal bottles or jars, it is blown within moulds. Each piece, as it is 
 blown, is handed over to the finisher, who forms the ring at the mouth of the 
 neck, and delivers it to a boy, to be placed in the annealing oven. 
 
 In making crown glass, as soon as the metal is ready for blowing, a workman 
 gathers on the blowing pipe a quantity of metal sufficient for forming a sheet 
 or table of glass, which he blows, and, by frequent rolling on a polished table, 
 brings it into a globular or cylindrical form ; he then inflates it gently into an 
 oblong ball called a parisienne, and immediately heats it again at the mouth of 
 the furnace, in order farther to expand it; in this stage a solid iron rod, charged 
 with melted glass, is made to adhere to the centre of the expanded part oppo- 
 site the extremity of the blow pipe, and this latter is detached from the glass by 
 a cold iron, leaving an orifice, which is gradually enlarged by heating the glass 
 at the small hole of the flashing furnace, and afterwards at the larger hole of 
 the same furnace, the workman all the while wheeling the rod which supports the 
 glass on a hook in a cross wall, built to defend him from the heat. By degrees, 
 in consequence of the heat and the centrifugal motion, the opening of the glass 
 is continually enlarged, until it expands suddenly with great violence into Ihe 
 form of a large circular plate, four or five feet in diameter, and of uniform 
 thickness, except at the centre, where it is attached to the supporting iron ; from 
 this iron it is separated by the application of cold, leaving in the centre a thick 
 nodule called the bull's eye ; and when the plate is sufficiently firm to prevent 
 warping, it is carried to the annealing oven and placed on its edge in a proper 
 frame, to keep it flat till all the tables are ready for removal into the crates in 
 which they are kept. 
 
 Plate glass is formed either by blowing or casting : by the former method is 
 made the glass for carriage windows ; and by the latter, the large plates for 
 looking glasses. Of late it is said that the art of blowing plate glass has been 
 so much improved, that plates measuring 60 inches in length 'by 21 in breadth 
 have been produced by this method ; but by casting, much larger plates are 
 produced, and the establishment at Ravenhead has exhibited at their warehouse 
 4 M
 
 638 GLASS. 
 
 near Blackfriars' Bridge plates of the extraordinary dimensions of 12 feet by 0, 
 The most perfect furnace for manufacturing plate glass appears to be that 
 which is employed in France. It consists of a central melting furnace of an 
 oblong form, with a double arched roof; it is capable of containing, upon a 
 raised bench on each side of the fire grate, two large melting pots and a cis- 
 tern ; in each angle of the furnace, and on each side, are two or three openings 
 for introducing the materials, transferring the melted metal from the pots to the 
 cistern, and withdrawing the latter when filled with metal : at each angle of 
 the principal furnace is another of an oblong form communicating with the 
 central one by flues, through which the flame reflecting from the arches of the 
 melting furnace reverberates on their contents. Each of these smaller fur- 
 naces has two openings, a smaller one for producing a current of air, and a 
 larger one for introducing and removing what is placed within them. Three of 
 them are usually employed for burning the melting pots and cisterns, which 
 are made of fire-clay ; and the fourth is used for preparing the frit. Around 
 the plate glass house are several annealing furnaces like baker's ovens, with 
 capacious mouths. For receiving the melted metal from the pots, square cis- 
 terns nf sufficient capacity to contain melted metal enough for one plate are 
 used, and when these are filled they are withdrawn from the furnace by means 
 of large iron tongs, supported upon an axle running upon two wheels ; another 
 pair of tongs made to encompass the cistern by entering a groove on its sides, 
 and furnished at each end with a handle for the more convenient management 
 of it, is attached by four chains to a sort of crane for suspending and raising the 
 cistern into a proper position with regard to the table. The casting table con- 
 sists of an oblong frame of wood, covered on its upper surface with a thick 
 sheet of smooth copper, having at its sides two iron rulers of the thickness of 
 the intended plate, their distance asunder being regulated by the proposed 
 breadth of the plate. An iron roller of considerable weight, furnished with a 
 handle at each end, resting on the iron rulers at one end of the table, is made to 
 pass over the melted metal when poured upon the table, in order to form it into 
 a plate of uniform thickness. The apparatus just described is used only for 
 casting plate glass, that for blowing being so simple as to need no particular 
 description. In preparing the materials for plate glass they are first reduced 
 to powder, well mixed together and calcined in the fritting furnace before 
 described ; they 'are then removed as quickly as possible into the melting pots 
 previously heated, and after being melted, which generally requires about ten 
 hours, the heat is continued at its utmost degree till the metal becomes perfectly 
 fine ; it is then ladled from the pots into the cisterns, which are then drawn out 
 on projecting ledges, and conveyed to the casting table, over which they are 
 suspended by the crane, and by means of the handles of the tongs they are 
 inclined so as to allow their contents to flow over the table : the iron roller is 
 then immediately passed steadily over the surface of the melted metal, sweeping 
 off the superfluous matter into troughs placed at the sides of the table ; and 
 when the roller reaches the further extremity of the table, it is expeditiously 
 lowered on a tressel, which prevents its interfering with the plate. The opera- 
 tion of casting is performed before the mouth of the annealing oven, in which 
 it remains exposed to a moderate heat for fourteen days, the heat being at last 
 suffered to die away as gradually as possible. When quite cool it is withdrawn, 
 carried to the magazine, examined, and cut square by a glazier's diamond, and 
 is then ready for the operations of grinding and polishing. The casting table 
 and tressel, as also the crane, are all mounted upon wheels, for the convenience 
 of removing them from one annealing furnace to another. When plate glass is 
 made by blowing instead of casting, after the materials have been fused as 
 before described, and become fine, the further admission of air is prevented by 
 closing all the openings of the furnace, and every thing is suffered to remain 
 stationary for nine or ten hours. This gradual cooling has been found necessary, 
 to enable the melted glass to adhere sufficiently to the blowing pipe. The mode 
 of blowing plate glass greatly resembles that used in the manufacture of 
 table glass, except in the quantity of metal gathered on the blowing pipe, 
 which is sometimes nearly lOOlbs. When plates of the largest size are to be
 
 GLASS, SOLUBLE. 639 
 
 formed, the metal is gradually blown and worked into the form of a cylinder, 
 which is cut open at one side with a pair of shears, and the soft glass is spread 
 on a heated floor, covered with a thick stratum of sand, and from thence is 
 speedily conveyed to the annealing furnace. In grinding plate glass, two plates 
 are always ground together, one being imbedded in plaster of Paris upon a 
 table, whilst the other, also imbedded in plaster, is placed upon the former, and 
 being loaded with great weights, is moved uniformly but pretty quickly over its 
 surface. Sand moistened plentifully with water is from time to time sprinkled 
 between the plates, and grinds away all the prominences of the glass until both 
 plates become smooth and even. As the grinding proceeds, sand of greater fine- 
 ness is employed ; and towards the conclusion, it is exchanged for emery, also of 
 varying fineness. As by grinding the surface is roughened and rendered in- 
 capable of transmitting the rays of light, it becomes necessary to restore its 
 lustre by polishing, which is performed by rubbing the surface with a block of 
 wood, covered on the lower side with a woollen cloth. The workman keeps it 
 supplied with fine polishing powders, as tripoli and putty, changing from coarse 
 to fine, as the polishing advances to a conclusion. To regulate the pressure a 
 springing pole is put on the back of the block, which, being bent to a curve, is 
 supported from the ceiling of the workshop. 
 
 GLASS, (SOLUBLE.) A simple silicate of potassa or soda, which unites perfect 
 solubility in boiling water to some of the general properties of common glass. 
 In the liquid state, it may be applied to cloth or wood, for the purpose of ren- 
 dering them incombustible. In fact, by the evaporation of the water in which 
 it is dissolved, a layer of a substance capable of fusing when heated, is depo- 
 sited on these bodies, that protects them from the contact of air necessary for 
 their combustion. The following account of its manufacture and uses is 
 derived from a translation by Professor Ren wick, of the Traite de Chimie 
 appliqu6 aux Arts, par M. Dumas. 
 
 Preparation. Soluble glass may be obtained by dissolving pure silica, obtained 
 by precipitation, in a boiling solution of caustic potassa ; but this process, being 
 both inconvenient and costly, cannot be practised upon a large scale. When 
 sand and carbonate of potassa are heated together, the carbonic acid is never 
 wholly driven off, except when the sand is in excess ; but the whole of the car- 
 bonic acid may be expelled by adding powdered charcoal to the mixture, in 
 such proportion that the carbonic acid of that part of the carbonate which is 
 not decomposed may meet with a sufficient quantity of carbon to convert it 
 into carbonic oxide. In this way the silica first forms a silicate in the propor- 
 tions contained in common glass, and drives off the appropriate equivalent of 
 carbonic acid ; then, at a high heat, the rest of the carbonate of potassa is 
 decomposed by the carbon, the carbonic oxide escapes, and the potassa thus 
 freed, either sublimes, or combines with the glass already formed. 
 
 The sand (freed from lime and alumina) and carbonate of potassa (pearl ash) 
 are taken in the proportion of 2 of the latter to 3 of the former, and to 10 
 parts of pearlash and 15 of sand, 4 parts of charcoal are added. A less 
 portion of charcoal must not be taken ; on the contrary, if the form of 
 potash employed be not sufficiently pure, a larger proportion of charcoal 
 may be advantageously employed. This substance' accelerates the fusion 
 of the glass, and separates from it all the carbonic acid, of which there 
 would otherwise remain a small quantity that would have an injurious 
 effect. In other respects, the same precautions that are employed in the 
 manufacture of common glass are to be observed. The materials must 
 be first well mixed, then fritted, and finally melted in a glass pot, until the 
 mass becomes liquid and homogeneous. The melted matter is taken out of 
 the pot with an iron ladle, and the pot is then filled with fresh frit. Thirty 
 pounds of pearlash, 45 of sand, and 121bs. of powdered charcoal may be 
 taken for a charge ; with this quantity the heat must be continued for five 
 or six hours. The crude glass thus obtained, is usually full of air bubbles ; 
 it is as hard as common glass, of a blackish gray colour, and transparent at the 
 edges ; sometimes it has a colour approaching to whiteness, and at others is 
 yellowish or reddish these are indications that the quantity of charcoal has
 
 040 GLASS, SOLUBLE. 
 
 not been sufficient. If it be exposed for some weeks to the air, it undergoes 
 slight changes, which rather tend to improve than injure its qualities. It 
 attracts a little moisture from the air, which slowly penetrates its mass, without 
 changing its aggregation or its appearance ; it merely cracks ; and a slight 
 efflorescence appears at its surface. If it be exposed to heat, after it have 
 undergone this change, it swells up, owing to the escape of the aqueous matter 
 it has absorbed. In order to prepare it for solution in boiling water, it must 
 be reduced to powder by stampers ; if this were not done, it would dissolve too 
 slowly. One part of glass requires from 4 to 5 of water for its solution. 
 The water is first heated to ebullition in an open boiler, the powdered glass is 
 then added by degrees, and must he continually stirred, to prevent it from 
 adhering to the bottom. The ebullition must be continued three or four hours, 
 until no more glass is dissolved : the liquor will then have acquired the proper 
 degree of concentration. If the ebullition be checked before this state is 
 attained, carbonic acid will be absorbed by the potassa from the air, which will 
 produce an injurious effect; for the same reason, too great a quantity of water 
 must not be employed, for during the long evaporation which will then Become 
 necessary, the carbonic acid of the water will readily combine with the potassa, 
 and cause a precipitation of the silica. When the liquor becomes too thick, 
 before the whole of the glass is dissolved, boiling water must be added. When 
 the solution has acquired the consistence of syrup, and a density of 1.24 to 
 1.25, it is sufficiently concentrated, and fit for use. It is then permitted to rest, 
 in order that the insoluble parts may be deposited ; while it is cooling, a pellicle 
 forms upon the surface, which after a time disappears of itself, or may be redis- 
 solved by depressing it in the liquor. This pellicle begins to appear during the 
 ebullition, and indicates its concentration. When the crude glass is of a proper 
 composition it contains but a few saline impurities, and no sulphuret of potas- 
 sium, it may be treated in the way we have described ; but if it contain any 
 notable proportion of these substances, they must be separated before it is dis- 
 solved; this separation may be effected in the following manner: The pow- 
 dered glass is exposed to the action of the air for three or four weeks, during 
 which time it must be frequently stirred ; and if it run into lumps, which will 
 happen in moist weather, they must be broken up. The glass, as we have 
 stated, attracts moistui'e from the air, and the foreign substances either separate 
 or effloresce. It then becomes easy to remove them from the glass. It is 
 sprinkled with water, and frequently stirred. At the end of three hours the 
 liquor is removed, it will then contain a part of all the saline impurities, and a 
 little of the silicate of potassa ; the powder is again to be washed with fresh 
 water. Soluble glass thus treated readily dissolves in boiling water, and the 
 solution leaves nothing to be desired. To preserve it in the liquid form no 
 particular care is necessary, as even after a long space of time it undergoes no 
 perceptible change, if the solution have been properly prepared. The only pre- 
 caution is not to allow air too free an access to it. A similar product may be 
 obtained by using a carbonate of soda instead of one of potassa. In this case, 
 two parts of the soda of the shops is required for one of silica. This glass has 
 the same properties as the other, but is more valuable in its uses. The solu- 
 tions of these two kinds of glass may be mixed in any proportion whatever, 
 and this mixture is more serviceable in some cases, than either of them 
 separately. 
 
 Properties. Soluble glass forms a viscid solution, which when concentrated 
 becomes turpid and opalescent : it has an alkaline taste and reaction. The 
 solution mixes in all proportions with water. When the density of the solu- 
 tion is 1.25, it contains nearly 28 per cent, of glass; if the concentration be 
 carried beyond this point, it becomes so viscid that it may be drawn out in 
 threads like molten glass. Finally, the liquor passes to the state of a vitreous 
 mass, whose fracture is conchoidal ; it then resembles common glass, except in 
 hardness. When the solution is applied to other bodies, it dries rapidly at 
 common temperatures, and forms a coat like a varnish. Soluble glass when 
 dried does not undergo any perceptible change when exposed to the air, nor 
 does it attract from it either moisture or carbonic acid ; neither has the carbonic
 
 GLASS, SOLUBLE. 041 
 
 acid of the atmosphere any well marked action on the concentrated solution ; 
 but when a current of carbonic acid is passed through the solution, the glass is 
 decomposed, and hydrate of silica deposited. But a weak solution becomes 
 turbid on exposure to the air, and is after a time decomposed wholly. When 
 the glass is impure, an efflorescence is formed after a while, which may be pro- 
 duced either by the carbonate and hyposulphate of potassa, or by chloride of 
 potassium. Soluble glass dissolves gradually without residuum in boiling water; 
 but in cold water the solution is so slow as to have led to a belief that it does 
 not dissolve at all. It however never becomes entirely insoluble, except when it 
 contains a much larger proportion of silica, or when it is mixed with other bodies, 
 such as the earths, metallic oxides, &c., with which double or triple salts are 
 formed, as is the case in the common glasses. Soluble glass which has been 
 exposed to the air, and is afterwards submitted to the action of heat, swells and 
 cracks at first, and melts with difficulty; it then loses about 12 per cent, of 
 its weight. It therefore contains, even when solid, a considerable quantity of 
 water, which it does not lose when simply dried by exposure to the air. Alcohol 
 precipitates it unaltered from its solution in water. When the solution is con- 
 centrated, but little alcohol is required for precipitation, and it need not be 
 highly rectified. Pure soluble glass may therefore be easily obtained from an 
 impure solution by the use of alcohol. The alcohol being added, the gelatinous 
 precipitate is permitted to settle ; the supernatant liquor is decanted, the 
 precipitate collected, rapidly stirred afier the addition of a little cold water, 
 and subjected to pressure. In truth, however, this process is attended "with 
 some loss, for even cold water will rapidly dissolve the precipatated glass in 
 consequence of its minute division. The acids decompose the solution of 
 glass. They also act upon it when solid, separating the silica in the form of 
 powder. 
 
 Uses. The properties of soluble glass fit it for numerous and varied applica- 
 tions. It has been used in the theatre of Munich as a means of safety from 
 fire. All sorts of vegetable matter, wood, cotton, hemp, linen, paper, &c. are, 
 as is well known, combustible ; but in order that they shall burn, two conditions 
 are requisite, an elevated temperature, and free contact of air, to furnish the 
 oxygen necessary for their transformation into water and carbonic acid. When 
 once set on fire, their own combustion develops the heat necessary to keep up 
 the chemical action, provided they be in contact with air. Jf deprived of such 
 contact, and made red hot, they will, it is true, yield inflammable volatile pro- 
 ducts, but the carbon which is left will not burn, as it is deprived of air, and 
 thus the combustion will stop of itself. Such is the part which all the fixed 
 fusible salts are capable of performing, if they be, in addition, composed of 
 substances incapable of yielding their oxygen at a low red heat, to either carbon 
 or hydrogen. These salts melt as the vegetable matter becomes heated ; they 
 form upon it a coat impenetrable to the air, and either prevent altogether, or 
 limit its combustion. The phosphate and borate of ammonia have such a cha- 
 racter, but they are so readily soluble in cold water, as to be liable to objections 
 which cannot be urged against soluble glass. Although soluble glass is of itself 
 a good preservative from fire, it fulfils the object better when it is mixed with 
 another incombustible body in powder. In this case the solution of glass acts 
 in the same manner as the oil of painters. The several coats have more body, 
 become more solid, and more durable ; and if the substance which is added be 
 of proper quality, coagulate by the action of fire into a strongly adhesive crust. 
 Clay, whiting, calcined bones, powdered glass, &c. may all be employed for 
 this purpose; but we cannot yet say with certainty which of them is to be 
 preferred. A mixture of clay and whiting appears to be better than either 
 used separately. Calcined bones form with soluble glass a very solid and 
 adhesive mass. Litharge, which, with the glass, makes an easily fusible mix- 
 ture, does not give a product fitted for coating wood, as the mixture contracts 
 in drying ; it therefore cracks, and is easily separated. Flint glass and crude 
 soluble glass are excellent additions. The latter ought to be exposed to the 
 air after it is pulverized, in order to attract moisture. If it be mixed with the 
 solution, and be then applied to any body whatever it in a short time forms a
 
 642 oLAsS, SOLUBLE. 
 
 coating as hard as stone, which, if the glass be of good quality, is unalterable 
 by exposure, and resists fire admirably. The scoriae of iron and lead, felspar, 
 fluor, may all be employed with soluble glass ; but experience alone can decide 
 which of these substances is best, and in what proportion they are to be 
 employed. We should advise that the first coat should always be a simple 
 solution of the glass ; and that a similar solution be applied over coats 
 composed of its mixture with other substances, particularly when such a 
 coat is uneven and rough. The last named substances form a solid and 
 durable coating, which suffers no change by exposm-e to the air, does not 
 involve any great expense, and is readily applied; but, in order that it 
 may not fail, particular care is to be taken both in preparing and employ- 
 ing it. In order to cover wood and other bodies with it, the solution must 
 be made of a pure glass, for otherwise it would effloresce and finally fall 
 off. However, a small degree of impurity is not injurious, although after 
 a few days a slight efflorescence will appear ; this may be washed off by water, 
 and will not show itself a second time. When a durable covering is to be 
 applied to wood, too strong a solution must not be employed at first ; for in 
 this case it will not be absorbed, will not displace the air from the pores, 
 and in consequence will not adhere strongly. It is a good plan to rub the 
 brush several times over the same place, and not to spread the coating too 
 lightly. For the last coats a more concentrated solution may be employed ; 
 still it must not be too thick, and must be spread as evenly as possible. Each coat 
 must be thoroughly dry before another is applied ; and this will take, in warm 
 and dry weather, at least twenty-four hours. After two hours the coat appears 
 to be dry, but is still in a state to be softened by laying on another. The same 
 inconvenience will then arise, which occurs when a thick coat of a concentrated 
 solution is applied ; the coat will crack, and does not adhere. This, however, 
 is only the case when potassa is the base of the glass, for that formed from 
 soda does not appear to crack. In applying soluble glass to the woodwork of 
 the theatre at Munich, 10 per cent, of yellow clay (ochre?) was added. After 
 six months, the coat had suffered but little change ; it was damaged only in a 
 few places where it had need of some repair. This arose from a short time only 
 having been allowed for the preparation and application of the glass, and they 
 were therefore done without proper attention. When this mode is employed 
 for preserving a theatre from fire, it is not enough to cover the woodwork, it is 
 also necessary to preserve the scenery, which is still more exposed to danger. 
 None of the methods yet proposed for this purpose appears as advantageous as 
 soluble glass, for it does not act upon vegetable matter, and completely fills up 
 the spaces between the thread; it fixes itself in the web in such a way that it 
 cannot be separated, and increases the durability of the fabric. The firmness 
 which it gives to stuffs does not injure them for use as curtains, because it 
 does not prevent them from being easily rolled. So far as the painting of 
 scenes is concerned, the glass forms a good ground for the colours. To pre- 
 vent the changes which some colours, Prussian blue and lake for instance, 
 might undergo from the alkaline matter, it will be necessary, before painting, 
 to apply a coat of alum, and then one of whiting. There is no great difficulty 
 in applying soluble glass to cloths ; still this operation is not so easy as might 
 at first be imagined. It is not sufficient to coat or dip them in the solution ; 
 they still require after this operation to be subjected to pressure. This object 
 might perhaps be best attained by passing them between rollers plunged in the 
 solution. When a cloth is only coated with soluble glass, and put into the fire, it 
 will remain incandescent after it is taken out. This is not the case when it has 
 been properly impregnated with this solution. A still better purpose is answered 
 in this case, when litharge has been added to the solution. The stuff in 
 drying yields to the shrinking of the mixture, and becomes inseparable from it, 
 which is the reverse of what happens when it is applied to wood. A single 
 part of litharge in fine powder is sufficient for fourteen parts of concentrated 
 liquor. Soluble glass is capable of many other applications, and particularly as 
 a cement; for this use it is superior to all those which have hitherto been 
 employed for uniting broken glass, porcelain, &c. It may be used in place of
 
 GLAZING. 643 
 
 glue or isinglass in applying colours, although when employed by itself it does 
 not make a varnish which will preserve its transparency when in contact 
 with air. 
 
 GLAUBER SALT. The sulphate of soda. 
 
 GLAZING, as it is nowpractised, embraces the cutting of all the varieties of 
 glass manufactured for windows, together with fixing it in sashes by means of 
 brads and a stopping of putty ; also the forming of casements, and securing the 
 glass by bands of lead fastened to outside frames of iron. The most ancient 
 species of glazing was in head-work, as our numerous cathedrals and religious 
 houses still extant demonstrate ; and fixing glass in leaden frames is still con- 
 tinued for the same description of buildings. The business of a glazier, if 
 considered in its most simple operations, consists in fitting aT me various kinds 
 of glass manufactured and sold into sashes previously prepared to receive 
 them. The sashes, as they are now made, have a groove or rebate formed on 
 the back of their cross, and vertical bars adapted to receive the glass ; into 
 these rebates the glazier exactly fits the squares, which he beds in a compo- 
 sition called putty. The putty consists of pounded whiting beaten up with 
 linseed oil, and so' kneaded and worked together as to make a tough and tena- 
 cious cement, and is of great durability ; this the glazier colours to suit the 
 sashes he may have in hand ; if they are common deal sashes, the putty is left 
 and used as first manufactured ; but if they are mahogany, it is coloured with 
 ochre till it approaches more nearly that of the sashes. In glazing windows the 
 colour of the glass is that on which the greatest beauty is given to the work ; 
 and to effect this successfully, many different manufactories have been esta- 
 blished. The most usual kind of window glass now employed by the glaziers is 
 called crown glass ; it is picked and divided at the manufactory into the several 
 different kinds, which are known as first, seconds, and thirds, and which par- 
 ticularly denote the qualities of the several kinds of glass, the first being known 
 as best crown, the next in quality second crown, and the last, thirds, or third 
 crown, the price of each varying according to the quality. The glass is in 
 pieces called tables, of about three feet in diameter each, and, when selected 
 and picked as above, they are packed in crates, twelve of such tables being put 
 in each crate of best glass, fifteen in the seconds, and eighteen in the thirds. 
 
 Green glass is another of these species, and which is greatly in demand for 
 all the purposes in which colour is not so particularly sought for. This sort of 
 glass is used in the glazing of the windows of cottages, also for green and hot- 
 houses, to which it is found to answer every purpose : it is not more than one- 
 half the cost of the crown glass. The green glass appears to have been the most 
 ancient kind made use of, as most of the vestiges remaining in the old win- 
 dows approach very nearly in their quality to what is now sold under that 
 designation. The glaziers also prepare the crown glass so as to produce an 
 opaque effect, to prevent the inconvenience of being overlooked ; it is technically 
 called ground glass, which is not improper, inasmuch as it is rendered opaque 
 by rubbing away the polish from off its surface, to do which the glazier takes 
 care to have the sheets or panes of glass brought to their proper size ; then they 
 are laid down smoothly as well as firm, either on sand or any other substance 
 which is adapted to admit of its lying securely ; he then rubs it with sand and 
 water, or emery, till the polish be completely removed ; it is then washed, 
 dried, and stopped into the window for which it was prepared. There was a 
 species of glass made at Venice originally, which was manufactured wholly for 
 this purpose, and is now to be seen in many counting-houses and old buildings ; 
 its general appearance presented an uneven surface, appearing as though indented 
 all over with wires, leaving the intervening shapes in the form of lozenges. This 
 glass was very thick and strong, and is of the description known as plate glass ; 
 it is now, however, generally substituted by the ground crown glass. A very 
 beautiful plate glass is manufactured by the British Plate -Glass Company, at 
 Ravenscroft, in Lancashire, and at their depot in Albion-place, London, plates 
 of every size, up- to those of very great dimensions, may be obtained, the 
 thickness varying from an eighth to a quarter of an inch. The cheapest kind 
 of glazing is the old fashioned mode, in small squares of the diamond or
 
 64 4 GLOBES. 
 
 ihombus shape, technically called quarries, which are fixed in rebated leaden 
 bars in outbuildings, cottages and in some kind of church windows. The 
 lead for this purpose is cast and drawn through an instrument called a glazier's 
 vice, which gives it the exact form required, and perfects the grooves for the 
 reception of the quarries. These leads being cut to the proper lengths, they 
 are soldered together at the intersections. This metal, which is used instead of 
 the cross bars of sashes, is so soft as to be easily bent where the groove is left 
 in it for the glass, and to be bent up again to inclose the glass after it is in- 
 serted. Window lights of this kind are further strengthened by vertical or 
 horizontal bars of iron or wood, secured to them by bands of lead twisted 
 around the bar. Glaziers now cut all their glass with a diamond ; whereas, 
 formerly, an instrument was made use of for the purpose, called a grozing-iron. 
 The diamond used by glaziers is left in its natural state, or with its outward 
 coat ; when polished, it is said to lose its property, making a perfect fracture of 
 the glass ; it is fixed in lead, and secured by a ferrule in a handle of hard wood, 
 and is used by drawing the diamond point over the glass, straight lines being 
 effected by the assistance of a straight edge, also of hard wood. The other 
 tools used by the glazier chiefly consist in " stopping-knives," for spreading 
 the putty over the edges of the glass and rebates of the frames ; in " hacking- 
 out tools," which are strong-backed knives, capable of bearing the blows of a 
 hammer, and used in clearing out the old putty, or making repairs ; also in a 
 pair of compasses, a three-foot rule, and a few other common tools, the uses of 
 which require no explanation. New sashes should always be primed, that is 
 painted once over before they are glazed, as the putty thereby holds much more 
 firmly to the work. 
 
 GLOBE, or SPHERE, in Geometry, a solid figure described by the revolution 
 of a semicircle round its diameter, which remains unmoved; or it may be 
 defined as a solid, bounded by a uniform convex surface, which is in every part 
 equally distant from a point called the centre. 
 
 GLOBE, in Practical Mathematics, an artificial sphere, on which are repre- 
 sented the countries and seas of our earth, or the face of the heavens, the circles 
 of the sphere, &c. That with the parts of the earth delineated upon it is 
 called the " Terrestrial Globe," and that with the constellations of the heavens, 
 the ".Celestial Globe." These globes are mounted on frames with other appur- 
 tenances. Their principal use, besides serving as maps to distinguish the out- 
 ward parts of the earth, and the situation of the fixed stars, is to illustrate the 
 various phenomena arising out of the diurnal motion of the earth. The globes 
 commonly used are constructed of plaster and paper in the following manner : 
 a wooden axis is provided somewhat less than the intended diameter of the 
 globe, and into the extremities iron wires are driven for poles ; on this axis are 
 applied two hemispherical caps, formed on a spherical wooden mould by pasting 
 several sheets of paper on the mould one over the other to about the thickness 
 of a crown piece, and cutting them through the middle when they are dried, 
 and slipping them off the mould. They are now applied to the poles of the 
 axis, and the two edges are sewed together with packthread. The rudiments 
 of the globe thus laid, they proceed to strengthen it and make it regular. In 
 order to do this the two poles are hasped in a metallic semicircle of the size 
 intended, and a plaster made of whiting, water, and glue, well incorporated 
 together, is daubed all over the surface ; in proportion as the plaster is applied, 
 the ball is turned round in the semicircle, the edge of which pares off whatever 
 is superfluous, and beyond the due dimensions, leaving the rest adhering in 
 places that are short of it ; the ball is then set to dry, after which it is again 
 set in the semicircle, and fresh plaster applied ; and thus they continue to 
 apply fresh composition, and to dry it, till the ball every where accurately 
 touches the semicircle, in which state it is perfectly smooth and regular. The 
 next thing is to paste the map on it : in order to this the map is projected in 
 several gores or gussets, all of which join accurately on the surface, and cover 
 the whole ball. To direct the application of these gores, lines are drawn by a 
 semicircle on the surface of the ball, dividing it into a number of equal parts, 
 corresponding to the number of gores, and subdividing those again answerably
 
 GLOBES. 
 
 45 
 
 to those of the gores. The paper thus pasted on, there remains nothing but 
 to colour and illuminate the globe, and to varnish it, the better to resist dirt 
 and moisture. The globe itself thus finished, is suspended in a brass meridian 
 with an hour circle and a quadrant of altitude, and then fitted into a wooden 
 horizon, which is supported by the legs of the frame. 
 
 Major Muller, G.L. has contrived a new arrangement of the globes, to which 
 he has given the name of the cosmophere, and which forms the subject of the 
 annexed engraving. The celestial globe consists of a hollow glass sphere, on 
 
 which are depicted the stars constituting the various constellations. This sphere 
 
 is furnished with brass circles, representing the equinoctial, the ecliptic, tha 
 
 4 N
 
 64C GLUE. 
 
 colures, and the polar circles. The glass sphere separates at the equinoctial inV> 
 two hemispheres, for the purpose of admitting within it a terrestrial globe, 
 which is manufactured in the usual way : this globe is also furnished with 
 brass circles, which are adjustable, to represent at pleasure the meridian and 
 the horizon of any assigned place. The axis of the globe passes through the 
 sphere, and supports both in a strong brass ring, which may be either attached 
 to a stand, and made to rest upon a table, or suspended from the ceiling of a 
 room, with a counterpoise w, as represented in the engraving, which will render 
 the construction clear when compared with the following references, a a 
 represents the equinoctials, where the two hemispherical glasses gg are united, 
 and from which the declination of the stars is to be measured ; c represents one 
 of the colures, and / one of the terrestrial meridians ; h one of the polar cir- 
 cles, and m m the large brass circle or general meridian, in which the apparatus 
 is suspended by the poles N and S. By the cosmosphere, as we have described 
 it, the position of the earth, with respect to the fixed stars, may be shown at 
 any given time ; and by placing on the celestial sphere patches to represent 
 portions of the sun, moon, and planets, the position of the earth with respect 
 to these bodies may also be represented with facility ; hence many of the 
 astronomical phenomena arising from the position of the earth, with regard to 
 the other bodies, can be familiarly illustrated, and numerous useful problems 
 readily solved. But to extend its usefulness, the patentee has made arrange- 
 ments for removing the globe from the interior of the system, and placing in its 
 stead the sun and planetary system ; and by this means the relative positions 
 of the planetary bodies may be interestingly represented. He has likewise pro- 
 vided brass graduated circles, by which, when they are attached to the celestial 
 sphere, the nature of the various astronomical and nautical pi-oblems depending 
 upon spherical trigonometry may be pleasingly explained. 
 
 GLUE. A tenacious viscid substance, used chiefly for binding or cementing 
 pieces of wood together : it is usually prepared from the cuttings and parings 
 of hides, and from the hoofs and horns of animals. For this purpose the 
 materials are first steeped in water for two or three days, then well washed, and 
 afterwards boiled to the consistence of a thick jelly, which is passed, while hot, 
 through ozier baskets, to separate the grosser particles of dirt, bones, &c. from it, 
 and then allowed to stand some time to purify it farther ; when the remaining 
 impurities have settled at the bottom, it is then melted and boiled a second 
 time. It is next poured into flat frames or moulds, from which it is taken out 
 pretty hard and solid, and cut into square pieces or cakes, and afterwards dried 
 in the wind in a coarse kind of net. This is the ordinary method of preparing 
 the common glue for carpenters' work ; but some few years back Mr. Yardley, 
 of Camberwell, obtained a patent for manufacturing glue from bones, which, 
 as chemists have long known, contain nearly one-half their weight of solid 
 gelatin, besides a considerable portion of fat. The glue thus obtained is said 
 to be of very superior quality. 
 
 In the engraving on the next page a represents a section of the principal vessel 
 of Mr. Yardley's apparatus, which is in the shape of a sphere or hollow globe of 
 great magnitude, and made of cast or wrought iron ; copper should not be 
 used, as gelatin has a powerful action upon that metal. The first part of the 
 process is to cleanse the bones by immersing them in a pit or cistern of water, 
 where they are to remain about twelve hours ; the water is then to be drawn 
 off, and fresh water added to them ; this operation may be repeated several 
 times, to get rid of the adhering dirt. The water being withdrawn from the 
 bones, a solution of lime, in the proportion of one bushel of the earth to five 
 hundred gallons of water, is to be poured into the cistern for the more perfect 
 cleansing of the bones, and the removal of superfluous matters. After three or 
 four days' saturation the limy solution should be drawn off, and fresh water 
 added, to get rid of the lime. Thus prepared, the bones are brought to the 
 globular vessel a called the extractor, which is filled with them by removing 
 the interior plate which covers the man-hole b ; this aperture is of an elliptical 
 fo.m, and allows the plate (which is of a similar figure) to be slipped round and 
 refixed in its place by turning the nut c, which draws it up tight against the
 
 GLUE. 
 
 C47 
 
 interior surface of the globular extractor; and the junctures are made air-tight 
 by luting. The extractor turns upon a horizontal cylindrical shaft in the bear- 
 ings e e ; one-half of this shaft is made hollow, or consists of a strong tube //, 
 which tube also proceeds downwards from the centre of the vessel, to conduct 
 the steam beneath the grating g, upon which the bones are laid. The steam, of 
 
 about 15 Ibs. pressure to the inch, is admitted from the boiler by turning the 
 cock h, and, passing along the pipe by the safety valve i and the stuffing box 
 k, it enters and proceeds first to the bottom of the extractor, then rises up 
 through the grating, and amongst the bones, until the vessel is completely 
 charged ; previous to this, however, the air contained in the vessel is got rid of 
 by opening the cock I for the steam to blow through, and afterwards closing it. 
 Whilst the steam is acting upon the bones the extractor is occasionally turned gently 
 round by hand at the winch m, the shaft of which carries a small pinion that takes 
 into the teeth of the wheel n, and the latter being on the same shaft as the 
 extractor, consequently gives it a rotatory motion. When at rest, as shown, a 
 quantity of fluid gelatin is collected in the bottom of the extractor at o, from 
 whence it is discharged by the cock p into a tub beneath, after opening the air- 
 cock / to allow it to run off. This done, steam is again admitted from the 
 boiler into the extractor to act upon the bones for another hour, when the 
 second portion of condensed liquor is to be drawn off. When the products thus 
 obtained have become cold, the fat which has formed upon the surface is to be 
 carefully removed by skimming, and the gelatinous portion only is to be returned 
 into the extractor, by means of a funnel at the cock I. The steam is then re- 
 admitted to the extractor for another hour, after which it is finally drawn off into 
 another vessel to undergo a simple evaporating process, until it arrives at a 
 proper consistency to solidify when cold, previous to which some alum is added 
 to clarify it. When the gelatin has become cold and solid, it is cut out into 
 square cakes, and dried as usual in the open air. 
 
 Mr. Bevan found that when two cylinders of dry ash, 1| inch in diameter, were 
 glued together, and, after twenty-four hours, torn asunder, it required a force of 
 1 2601bs. for that purpose, and consequently that the force of adhesion w*.
 
 f ,4S GOLD BEATERS' SKIN. 
 
 equal to 715 per square inch of surface. From a subsequent experiment on 
 solid glue, he found that the cohesion is equal to 40001hs. on the square inch, 
 and hence infers, that the application of this substance as a cement is suscep- 
 tible of improvement. Glue is frequently prepared for more delicate purposes 
 in the arts from parchment or vellum cuttings, or from isinglass. Parchment 
 glue is made by boiling gently shreds of parchment in water, in the proportion 
 of one pound of the former to six quarts of the latter, till it be reduced to one 
 quart. The fluid is then strained from the dregs, and afterwards boiled to the 
 consistence of glue. Isinglass glue is made in the same way ; but this is im- 
 proved by dissolving the isinglass in common spirit by a gentle heat : thus 
 prepared, it forms a cement much superior to paste for joining paper, or for 
 stretching it on wood. 
 
 GLUTEN. A substance found combined with the feculent and saccharine 
 matter, which constitute the principal part of nutritive grain. It is obtained in 
 the largest quantity from wheat (amounting to the twelfth part of the whole 
 grain) by kneading the flour into paste, which is to be washed very cautiously 
 by kneading it under a jet of cold water till the water carries off nothing more, 
 but remains colourless ; what remains is gluten : it is ductile and elastic, and 
 has some resemblance to animal tendon. 
 
 GOLD. A yellow metal of specific gravity 19.3, which is greater than any 
 other body in 'nature, except platina. It is soft, very tough, ductile, and 
 malleable, unalterable and fixed, whether in the atmosphere or in the heat of 
 the hottest furnaces ; but it has been volatili2ed by powerful burning mirrors, 
 as also by the oxy-hydrogen blow pipe. No acid acts readily upon gold, except 
 the nitro-muriatic acid, called aqua regia, in which it may be dissolved, occa- 
 sioning at the same time an effervescence ; but from the slight affinity of gold 
 for oxygen, it is precipitated from its solvent by the alkalies, earths, and most 
 of the" other metals. Its precipitate with ammonia forms a compound, which 
 detonates with great violence, as has been already mentioned under the article 
 FULMINATING POWDERS. Most metals combine with gold, increasing its hard- 
 ness, but considerably impairing its ductility. For the purposes of coin, 
 Mr. Hatchett considers an alloy of silver and copper in equal parts to be 
 preferred, and copper alone as preferable to silver only : but the gold coins of 
 Great Britain are composed of eleven parts of gold, and one of copper. Gold 
 is mostly found in the metallic state, although generally combined with silver, 
 copper, or iron, or all three. It is found either in separate lumps or visible 
 grains amongst the sands of rivers, in many parts of Europe, and elsewhere. 
 The quantity is for the most part insufficient to pay the expense of separating 
 it ; but it is thought to be more universally diffused in sands and earth than 
 any other metal, except iron. Some sands afford gold by simple washing, the 
 heavy metallic particles subsiding first; but when it is imbedded in earths and 
 stones, these substances are first pounded, and then boiled with one tenth of 
 their weight of mercury, together with water. The mercury after a certain 
 time forms an amalgam with the gold, from which it is separated by pressure 
 through leather bags, and subsequent distillation. Gold is seldom used for 
 any purpose in a state of perfect purity. In estimating its fineness, the whole 
 mass spoken of is supposed to weigh 24 carats, of 1 2 grains each, and the pure 
 gold is called fine: Thus, if gold is said to be 23 carats fine, it is understood 
 that the mass consists of 23 parts of fine gold, and one part of alloy. The 
 principal use of gold is to make coin, trinkets, gold leaf for gilding, and gold 
 wire and thread. 
 
 GOLD-BEATERS' SKIN. The gold-beaters use three kinds of membranes, 
 viz. for the outside cover common parchment, made of sheepskins, is used ; for 
 interlaying with the gold, first the smoothest and closest vellum, made of calves' 
 skin ; and afterwards the much finer skins of ox-gut, stript off from the large 
 straight gut slit open, curiously prepared for the express purpose, and hence 
 called gold-beaters' skin. According to Dr. Lewis, the preparation of these 
 last is a distinct business, practised only by two or three persons in the kingdom. 
 The general process is supposed to consist in applying them one upon another, 
 by the smooth sides, in a moist state, in which they readily cohere and unite
 
 GOLD WIRE. 549 
 
 inseparably, stretching them very carefully on a frame, scraping off the fat and 
 rough matter, so as to leave only the fine exterior membrane of the intestine, 
 at the same time beating them between double leaves of paper, to force out 
 what grease may remain in them, and then drying and pressing them. Not 
 withstanding the vast extent to which gold is beaten between these skins, and 
 the great tenacity of the skins themselves, they yet sustain continual repeti- 
 tions of the process for several months, without appearing to extend or grow 
 thinner. 
 
 GOLD-BEATING. The gold is prepared for leaves by melting it in a 
 blacklead crucible, with some borax, in a wind furnace ; and as soon as it is in 
 perfect fusion, it is poured out into an iron ingot mould, then forged and 
 passed between steel rollers, until they become long ribbons, as thin as 
 writing paper: each of these ribbons is then cut into 150 pieces, and each of 
 these pieces is next forged upon an anvil, till it is about an inch square. 
 These squares, which weigh 6^ grains each, and are about ^ part of an inch 
 thick, are now well annealed, preparatory to the next operation, which consists 
 in interlaying the plates of gold alternately with pieces of very fine vellum, 
 about four inches square, and about twenty vellum leaves are placed on the 
 outsides ; the whole is then put into a case of parchment, over which is drawn 
 another similar case, so that the packet is kept tight and close on all sides. 
 It is now laid on a smooth block of marble or metal, of great weight, and the 
 workman begins the beating with a roundfaced hammer, weighing sixteen 
 pounds ; the packet is turned occasionally upside down, and beaten (ill the 
 gold is extended nearly to an equality with the vellum leaves. The packet is 
 then taken to pieces, and each leaf of gold is divided into four, with a steel 
 knife, having a smooth but not very acute edge. The 600 pieces thus produced 
 are interlaid with pieces of animal membrane, (see GOLDBEATERS' SKIN,) from 
 the intestines cf the ox, of the same dimensions and in the same manner as the 
 vellum. The beating is continued, but with a hammer weighing only twelve 
 pounds, till the gold is brought to the same dimensions as the interposed mem- 
 brane. It is now again divided into four, by means of a piece of cane, cut to an 
 edge, the leaves being by this time so thin, that any accidental moisture conden- 
 sing on an iron blade, would cause them to adhere to it. The 2400 leaves hence 
 resulting are parted into three packets, with interposed membrane as before, and 
 beaten with the finishing hammer, weighing about ten pounds, till they acquire 
 an extent equal to the former. The packets are now taken to pieces, and the 
 gold leaves, by means of a cane instrument and the breath, are laid flat on a 
 cushion of leather, and cut one by one to an even square, by a little square 
 frame, made of cane ; they are lastly laid in books of twenty-five leaves each, 
 the paper of which is previously smoothed, and rubbed with red bole, to 
 keep the gold from adhering. By the weight and measure of the best 
 wrought leaf-gold, it is found that one grain is made to cover 56f square inches; 
 and from the specific gravity of the metal, together with this admeasurement, 
 it follows that the leaf itself is ^-^ part of an inch thick. This, however, is 
 not the limit of the extensibility of the metal ; for by computing the surface 
 covered in silver gilt wire, and the quantity of gold used, it is found to be only 
 one-twelfth that of the gold leaf, or 3 , 384 \ BM part of an inch thick ; nevertheless 
 it is so perfect as to exhibit no cracks when viewed by a microscope. 
 
 GOLD THREAD, as it is called, consists of a silk thread covered with gold 
 wire. It is formed by passing gold wire between two rollers of nicely polished 
 steel, set very close together, by which means it is rendered quite flat, but 
 without losing any thing of its polish or gilding, and becomes so exceedingly 
 thin and flexible that it is easily spun upon a silk thread, by means of a hand- 
 wheel, and so wound upon a spool or bobbin. 
 
 GOLD WIRE. That which is commonly called gold wire is in fact merely 
 silver wire gilt. The following is the process employed for this purpose. 
 First an ingot of silver of 24 pounds is forged into a cylinder of about an inch 
 in diameter, which is reduced by passing it through eight or ten holes of a 
 large coarse drawing iron, to about three fourths of its former diameter. It is 
 then filed very carefully all over, to remove any dirt from the forge, and after-
 
 650 GRAVITY. 
 
 wards cut through the middle into two ingots, each about 26 inches long, which 
 are drawn through several new holes to remove any inequalities left by the file, 
 and to render the surface as smooth and equable as possible. The ingot thus 
 far prepared, it is heated in a charcoal fire : then taking some gold leaves, 
 each about four inches square, and weighing 12 grains each, four, eight, 
 twelve, or sixteen of them are joined, as the wire is intended to be more or less 
 gilt, and when they are joined so as to form a single leaf, the ingots are rubbed 
 reeking hot with a burnisher, and the leaves applied over the whole surface of 
 the ingot to the number of six over each other, well burnished or rubbed 
 down. When gilt, the ingots are again laid in a charcoal fire, and raised to 
 a certain degree of heat, when they are gone over a second time with the bur- 
 nisher, botli to solder the gold more perfectly, and to finish the polishing. The 
 gilding finished, the ingot is passed through twenty holes of a moderate draw- 
 ing iron, by which it is reduced to the thickness of the tag of a lace ; from this 
 time the ingot loses its name, and commences gold wire.. Twenty holes more 
 of a lesser iron leaves it small enough for the least iron, the finest holes of which 
 last, scarcely exceeding the hair of the head, finish the work. Each time that 
 the wire is drawn through a fresh hole it is rubbed afresh with new wax, both 
 to facilitate its passage, and to prevent the silver appearing through it. 
 
 GONIOMETER. An instrument for measuring the angles formed by two 
 or more planes, and chiefly, in crystallography, to determine the angles of 
 crystalline substances. 
 
 GOUGE. A sort of round hollow chisel, for cutting holes, channels, grooves, 
 &c. in wood or stone. 
 
 GRANARY. A storehouse for grain. The construction of this class of 
 buildings has not, we believe, received that attention from the scientific which 
 the importance of it deserves. The best which we have met with in print con- 
 sists of a plain rectangular building, about twice the height of the distance 
 between the opposite walls, that is 20 feet high by 10 feet in width on each 
 side, and provided with numerous air-holes, declining outwards, to prevent the 
 entrance of rain or snow ; from each air-hole to a corresponding one on the 
 opposite side is fixed an inverted angular spout or gutter, which permits the 
 air to pass through unimpeded by the corn lying above it. As many of these 
 gutters are fixed, as there are holes to receive the ends after crossing the build- 
 ing ; and the extremities of the holes are covered with wire gauze, to defend 
 them from vermin. The first floor of the granary is divided into a series of hop- 
 pers, that empty themselves into one large hopper underneath, provided with a 
 sliding door to regulate the passage of the grain into a sack or other receptacle. 
 At the top of the building is a loft, to which the corn is first hoisted by a tackle 
 or crane, and is discharged over a cross bar into the body of the building, which 
 may be continued until it is filled to the top. Upon drawing off any corn at the 
 bottom, the whole of it is put into motion, and the airing of every part is pro- 
 moted ; the process of airing is however continually going forward through the 
 numerous passages under the inverted gutters, the angles of which, it is said, 
 do not fill up by the lateral pressure of the grain. 
 
 GRANULATION. The method of dividing metallic substances into grains 
 or small particles to facilitate their combination with other substances, and 
 sometimes for the purpose of readily subdividing them by weight. This is 
 done either by pouring the melted metal into water, or by agitating it in a box, 
 until the moment of congelation, at which instant it becomes converted into a 
 powder. Copper is granulated for making brass by pouring it through a per- 
 forated ladle into a covered vessel of water, with a movable false bottom. 
 The small shot made of an alloy of lead with arsenic is produced in like manner, 
 by pouring the liquid metal through a perforated colander, and allowing it to 
 fall from a considerable elevation through the air, which causes the drops to 
 assume a spherical shape. See SHOT, SOLDER, &c. 
 
 GRAVITY, in Physics, the natural tendency of bodies towards a centre. 
 Terrestrial or particular gravity is that by which bodies descend or tend towards 
 the centre of the earth; the phenomena of which are as follows:!. All 
 circumterrestrial bodies tend towards a point which is either accurately or nearly
 
 GRAVITY. 651 
 
 tne centre of magnitude of the terraqueous globe. 2. In all places equidistant 
 from the centre of the earth the force of gravity, cteteris paribus, is equal. The 
 force of gravity is not equal on all parts of the earth's surface for two reasons : 
 first, because, as the earth is not a sphere, but a spheroid, all parts of its surface 
 are not equidistant from its centre ; and secondly, the gravity is different in 
 different latitudes, by reason of variations in the centrifugal force, occasioned 
 by the earth's rotation, the increment of gravity on this account being as the 
 iquare of the cosine cf the latitude. 3. Gravity affects equally all bodies, 
 without regard either to their bulk, figure, or matter; so that in a perfectly 
 unresisting medium, the most compact and the loosest, the greatest and the 
 smallest bodies would descend through an equal space in the same time. The 
 space through which bodies do actually fall in vacuo is 16 J feet in the first 
 second of time in the laf'tude of London, and for other portions of time either 
 greater or less the spaces are as the squares of the times. 4. Gravity is greatest 
 at the earth's surface, from whence it decreases both upwards and downwards, 
 but not at the same ratio in each direction ; the diminution of the force upwards 
 being as the square of the distance from the earth's centre ; whilst downwards, 
 the decrease is in the direct ratio of the distance from the centre. 
 
 General, or Universal Gravity, is that in consequence of which all the planets 
 tend to one another; and indeed all the bodies and particles of matter in the 
 universe tend to one another. 
 
 Gravity, specific, is the relative gravity of any body or substance, considered 
 with regard to some other body which is assumed as a standard of comparison, 
 and this standai'd by universal consent and practice is rain water or distilled water, 
 and by a very fortunate coincidence, at least to English philosophers, it happens 
 that a cubic foot of water weighs 1 000 ounces avoirdupoise, and consequently 
 assuming this as the specific gravity of rain water, and comparing all other 
 bodies with this, the same numbers that express the specific gravity of bodies 
 will at the same time denote the weight of a cubic foot of such bodies in avoir- 
 dupoise ounces. From the preceding definition may be drawn the following 
 laws of the specific gravity of bodies. 1. In bodies of equal magnitudes, the 
 specific gravities are directly as the densities, or as their weights. 2. In bodies 
 of the same specific gravities, the weights will be as the magnitudes. 3. In 
 bodies of equal weights, the specific gravities are inversely as the magnitudes. 
 4. The weights of different bodies are to each other in a compound ratio of 
 their magnitudes and specific gravities. 5. When a body is specifically heavier 
 than a fluid it loses as much of its weight when immersed in it as is equal to 
 the weight of a quantity of the same fluid of equal bulk. 6. If the gravity 
 of the fluid be greater than that of the body, then the weight of the quantity 
 of fluid displaced by the part immerged, is equal to the weight of the whole 
 body. The specific gravity of solid bodies is usually determined experimentally 
 
 by means of the " Hydrostatic Balance," (See BALANCE;) but for f 
 
 ascertaining the specific gravity of liquids, an instrument termed 
 a " Hydrometer " is usually employed. A description of a variety 
 of these instruments will be found under the head HYDROMETER. 
 
 The late Professor Leslie invented a new and singularly simple 
 and ingenious method for ascertaining the specific gravity of 
 
 solids. All substances of this class are more or less porous; and 
 the pores being filled with air which is not expelled when the sub- 
 stance is immersed in water causes their specific gravity when ascer- 
 tained by the hydrostratic balance to appear less than it really is. 
 In Mr. Leslie's method this source of error is avoided, and some of 
 the results obtained in consequence are extremely curious. The 
 instrument employed consists of a glass tube ac, about three feet 
 long, and open at both ends ; the wide part a b is about four- 
 tenths of an inch in diameter ; the part b c about two-tenths. 
 The two parts communicate at b by an extremely fine slit, which 
 suffers air to pass, but retains sand or powder. The mouth at a 
 is ground smooth, and can be shut so as to be air-tight by a small 
 glass plate /. The substance vhose specific gravity we wish to find is first 
 
 |
 
 652 GRENADE. 
 
 reduced to powder, which is then put into the wide part of the tube a b, which 
 may either be filled or not. The tube being then held in a vertical position 
 has the narrow part immersed in mercury, contained in an open vessel x, 
 till the metal rises within to the gorge b. The lid is then fitted on air-tight 
 at a. In this state it is evident there is no air in the tube, except that 
 mixed with the powder in the cavity a b. Suppose the barometer at the 
 time to stand at 30 inches, and that the tube is lifted perpendicularly upwards, 
 till the mercury stands in the inside of b c, at a point e 15 inches, (or one half of 
 30,) above its surface, in the open vessel ; it is evident, then, that the air in 
 the inside of the tube is subjected to a pressure of exactly half an atmosphere : 
 and of course it dilates and fills precisely twice the space ft originally occupied. 
 It follows, too, that since the air is dilated to twice its bulk the cavity a b contains 
 just half what it did at first ; and the cavity b e now containing the other half, 
 the quantity of air in each of these parts of the tube is equal. In other words, 
 the quantity of air in b e is exactly equal to what is mixed with the powder in 
 a b, and occupies precisely the same space which the whole occupied before its 
 dilatation. Let us now suppose the powder to be taken out, and the same expe- 
 riment repeated, but with this difference, that the cavity a b is filled with air 
 only. It is obvious that the quantity being greater it will, when dilated to 
 double the bulk under a pressure of fifteen inches, occupy a larger space, and 
 the mercury will rise, let us suppose, only to d. But the attenuated air in the 
 narrow tube always occupies exactly the space which the whole occupied at 
 ordinary atmospheric pressure ; and this space is therefore, in the one case, the 
 cavity b c, and in the other b d. Hence it follows that the cavity e d, which is 
 the difference between these, is equal to the bulk of the solid matter in the 
 sand. Now by marking the number of grains of water held by the narrow 
 tube b e on a graduated scale attached to it, we can find at once what is the 
 weight of a quantity of water, equal in bulk to the solid matter in the sand ; 
 and by comparing this with the weight of the sand, we have its true specific 
 gravity. Aware that some solid bodies, such as charcoal, hold much condensed 
 air in their pores, and that probably they retain part of this even when reduced 
 to powder, Professor Leslie obviates the chances of error arising from this 
 source by comparing the dilatation which takes place under different degrees 
 of pressure, under 10 inches and 20 for instance, or 7 and 15. Charcoal, from 
 its porosity, is so light that its specific gravity, as assigned in books, is generally 
 under 0.5 less than half the weight of water, or one seventh the weight of 
 diamond ; taken in powder by the above instrument it exceeds that of diamond, 
 is one half greater than that of whinstone, and is, of course, more than seven 
 times heavier than has usually been supposed. Mahogany is generally estimated 
 at 1.36; but mahogany sawdust proves by the instrument to be 1.68; wheat 
 flour is 1.16"; pounded sugar 1.83 ; and common salt 2.15 ; the last agrees very 
 accurately with the common estimate. Writing paper rolled hard by the hand 
 had a specific gravity of 1,78, the solid matter present being less than one third 
 of the space it apparently filled. One of the most remarkable results was with 
 an apparently very light specimen of volcanic ashes, which was found to have 
 a specific gravity of 4.4. These results are, however, given as approximations 
 merely by the first instrument constructed. 
 
 GRENADE. A kind of small bomb or shell filled with an explosive com- 
 position, and fired by a fusee inserted in the touch-hole. Their principal use is 
 in a close assault, when they are thrown by hand from the tops of ships or 
 ramparts of fortresses, whence they are frequently styled hand grenades. They 
 are usually about three inches in diameter, and weigh about three pounds. 
 Their employment in war is not so general as formerly, 
 owing partly to the uncertain action of the fusee, which ren- 
 ders it difficult to ensure their explosion so as to produce the 
 greatest effect. To obviate this defect, grenades have been 
 invented which are fired by means of a cap containing a 
 priming of percussion powder instead of a lighted fusee. 
 The annexed engraving represents a section of a grenade 
 upon this principle, a the shell of cast-iron supposed to be
 
 GUM. 653 
 
 filled with combustible matter, and having a conical hole into which an iron 
 pin, surrounded by a piece of cork, fits easily ; the other extremity of the pin 
 is formed to receive a percussion cap, in which is put a small quantity of per- 
 cussion powder. The shell being thrown, it will naturally fall on the head ot 
 the pin projecting on the outside ; the detonating powder is kindled by the 
 blow, and the contents of the shell, as well as the shell itself, are scattered in 
 all directions. 
 
 The annexed engraving represents a percussion 
 hand grenade, invented by Capt. Norton of the 
 34th Regiment. Its construction is precisely the 
 same as that of the foregoing one, but there is in 
 addition a sheet of brown paper, or a piece of 
 common cloth tied to a button, on the outside of 
 the shell, forming a handle to throw it by, and 
 guiding its descent, so that the head of the bolt 
 will infallibly strike the ground, and thereby insure 
 the explosion. 
 
 GRINDING. A mechanical process, in which 
 certain effects are produced by the attrition of two 
 surfaces. The process of grinding is of extensive 
 use in various mechanical arts; and great diffe- 
 rences exist in the mode of conducting it according 
 to the purposes for which it is employed, which are very varied ; thus, in grinding 
 corn, the object is to reduce the grain to an impalpable powder; in grinding 
 lenses, it is to give them a certain figure and polish; cocks and valves are 
 ground into their seats to promote intimate contact; colours are ground to 
 promote the intimate mixture of the colouring matter with the oil ; and cutlery 
 and tools are ground, to impart to them a sharp edge. The latter operation, 
 as is well known, is performed by applying the articles to be ground to the 
 periphery of a cylindrical stont of a rough, gritty texture, revolving with great 
 rapidity ; and to reduce as much as possible the heat caused by the friction of 
 the two surfaces, the stone is mounted over a trough containing water. Some 
 curious experiments are detailed in Nicholson's Journal upon this point, from 
 which it appears that tallow is much more effective than water in keeping the 
 temperature low ; for in trying to grind down the teeth of a file with the grind- 
 stone immersed in water, the file soon became too hot to hold, and the teeth 
 were scarcely touched, but by applying a tallow candle to a dry grindstone as 
 it revolved, so as to give an even coating of tallow, he was enabled to grind 
 down the teeth rapidly, and the temperature of the file was scarcely raised until 
 the tallow became melted. This effect Mr. Nicholson attributes to the heat 
 absorbed or rendered latent in bringing a solid substance into a fluid state. 
 
 GRINDSTONE. A flat circular stone, mounted on a spindle, and turned 
 by a winch handle, used for the purpose of grinding edge tools. In districts 
 where cutlery and edge tools are manufactured, great numbers of these stones 
 are used in one building, called a blade mill or grind mill. The stone suited 
 to form grindstones is composed of a coarse species of sandstone. The finer 
 sorts of grindstones, and what are called whitening or polishing stones, by the 
 Sheffield cutlers, are from different rocks in the upper part of the great Derby- 
 shire Coal Series ; others are from Staffordshire, Warwickshire, &c. 
 
 GUITAR. A musical instrument with five double rows of strings, of which 
 those that are bass are in the middle. 
 
 GUM. A vegetable juice, or thick, transparent, tasteless fluid, which some- 
 times exudes from certain species of trees. It is very adhesive, and gradually 
 hardens without losing its transparency ; but easily softens again when mois- 
 tened with water. The gum most commonly used is that which is procured 
 from different species of the Acacia in Egypt, Arabia, &c. ; it is known by 
 the name of gum arabic. Gum likewise exudes abundantly from the common 
 wild cherry tree of this country : it exists also in various plants in the state of 
 mucilage, especially in the roots and leaves. It is most abundant in bulbous roots ; 
 and of these, the hyacinth affords the largest quantity. Gum readily dissolves 
 4 o
 
 *M GUN. 
 
 in water, and the solution, which is thick and adhesive, is known by the name 
 of mucilage. It is also soluble in the vegetable acids, but is decomposed by the 
 sulphuric, nitric, and muriatic acids. It is insoluble in alcohol and ether. 
 
 GUN. A fire-arm or weapon chiefly composed of a barrel or long tube, 
 from which shot and other missiles are discharged by means of inflamed gun- 
 powder ; ignition being effected by the percussion of flint and steel, or that of 
 detonating powder, through the instrumentality of a piece of mechanism called 
 the lock, which is fixed to the handle or stock, and in connexion with the lower 
 extremity of the barrel, where the charge is deposited. The word gun, how- 
 ever, is indiscriminately applied to almost every species of fire-arm, and is 
 usually divided into two classes, namely, great guns, and small arms. The 
 former include cannon, artillery, and various species of ordnance, that are 
 moved on wheels, pivots, trucks, and slides, which are described under their 
 separate heads ; the latter class, which embraces muskets, blunderbusses, car- 
 bines, fowling-pieces, and pistols, being such as are manufactured by gun-smiths, 
 we propose to describe in this place. 
 
 The principal parts of a gun are the barrel, the lock, and the stock. The 
 following are the requisite properties of the barrel : first, lightness, that it may 
 incommode the person who carries it as little as possible ; secondly, sufficient 
 strength, and other properties requisite to prevent its bursting by a discharge ; 
 thirdly, it should be constructed in such a manner as not to recoil with violence; 
 and fourthly, it should be of sufficient length to carry the shot to as great a 
 distance as the force of the powder employed is capable of doing. The best 
 barrels in this country are formed of stubs, as they are called, or old pieces of 
 horse-shoe nails. About twenty-eight pounds of these are requisite to form a 
 single musket barrel. The method of manufacturing them from this material 
 is as follows : a hoop of about an inch broad, and six or seven inches diameter, 
 is placed in a perpendicular position, and the stubs, previously well cleaned, 
 piled up in it with their heads outermost on each side, till the hoop is quite 
 filled and wedged tight with them. The whole then resembles a rough circular 
 cake of iron, which being heated to a white heat, and then strongly hammered, 
 unite into one solid lump. The hoop is now removed, and the heatings and 
 hammerings repeated till the iron is rendered very tough and close in the grain, 
 when it is drawn out into pieces of about twenty-four inches in length, half an 
 inch or more in breadth, and half an inch in thickness. Four of the pieces, pre- 
 pared as has been described, are required for one barrel ; but in the ordinary 
 way, a single bar of the best soft iron is employed. The workmen begin 
 with hammering out this into the form of a-flat ruler, having its length and 
 breadth proportioned to the dimensions of the intended barrel. By repeated 
 heating and hammering, this plate is turned round a tempered iron rod called 
 a mandril, the diameter of which is considerably smaller than the intended bore 
 of the barrel. One of the edges of the plate being laid over the other about 
 half an inch, the whole is heated and welded by two or three inches at a time, 
 hammering it briskly, but with moderate strokes, upon an anvil, which has a 
 number of semicircular furrows in it, adapted to the barrels of different sizes. 
 Every time the barrel is withdrawn from the fire the workman strikes it gently 
 against the anvil once or twice in a horizontal direction. By this operation the 
 particles of the metal are more perfectly consolidated, and every appearance of 
 a seam in the barrel is obliterated. The mandril being then again introduced 
 into the cavity of the barrel, the latter is very strongly hammered upon it hi 
 one of the semicircular hollows of the anvil by small portions at a time, the 
 heatings and hammerings being repeated until the whole barrel has undergone 
 the operation, and its parts rendered as perfectly continuous as if they had 
 been formed out of a solid piece. To effect this completely three welding heats 
 are necessary when the very best iron is made use of, and a greater number for 
 the coarser kinds. 
 
 The next operation in forming the barrels is the boring of them, which is 
 usually done in the following manner : Two beams of oak, each about six 
 inches in diameter, and six or seven feet long, are placed horizontally, and 
 parallel to one another, having each of their extremities mortised upon a strong
 
 GUN. 655 
 
 upright piece about three feet high, and firmly fixed ; a space of three or four 
 inches is left hetween the horizontal pieces, in which a piece of wood is made 
 to slide by having at either end a tenon let into a groove, which runs on the 
 inside of each beam throughout its whole length. Through this sliding piece 
 a strong pin or bolt of iron is driven or screwed in a perpendicular direction, 
 having at its upper end a round hole large enough to admit the breech of the 
 barrel, which is secured in it by means of a piece of iron that serves as a 
 wedge, and a vertical screw passing through the upper part of the hole. A 
 chain is fastened to a staple on one side of the sliding piece, which runs between 
 the two horizontal beams, and passing over a pulley at one end of the machine, 
 has a weight hooked on to it ; an upright piece of timber is fixed above this 
 pulley and between the ends of the beams, having its upper end perforated by 
 the axis of an iron crank furnished with a square socket, the other axis being 
 supported by the wall, or by a strong post, and loaded with a heavy wheel of 
 cast-iron to give it force. The axes of this crank are in a line with the hole in 
 the bolt already mentioned. The borer being then fixed into the socket of the 
 crank, has its other end, previously well oiled, introduced into the barrel, whose 
 breech part is made fast in the hole of the bolt ; the chain is then carried over 
 the pulley, and the weight hooked on ; the crank being then turned with the 
 hand, the barrel advances as the borer cuts its way till it has passed through 
 the whole length. The boring bit consists of an iron rod somewhat longer than 
 the barrel, one end of which fits the socket of the crank ; the other is adapted 
 to a cylindrical piece of tempered steel, about an inch and a half in length, 
 having its surface cut after the manner of a perpetual screw, with five or six 
 threads, the obliquity of which is very small ; the breadth of the furrows is the 
 same with that of the threads, and their depth sufficient to let the metal cut by 
 the threads pass through them easily ; thus the bit gets a strong hold of the 
 metal, and the threads being sharp at the edges, scoop out and remove all 
 the inequalities and roughness from the inside of the barrel, and render the 
 cavity smooth and equal throughout. A number of bits, each a little larger 
 than the former, are afterwards successively passed through the barrel in the 
 same way, until the bore has acquired the magnitude intended. By this opera- 
 tion the barrel is very much heated, especially the first time the borer is passed 
 through it, by which means it is apt to warp : to prevent this in some measure, 
 the barrel is covered with a cloth kept constantly wetted, which not only pre- 
 serves the barrel from an excess of heat, but likewise preserves the temper of 
 the bit from being destroyed. The equality of the bore is of the utmost con- 
 sequence to the perfection of a barrel, insomuch that the greatest possible accu- 
 racy in every other respect will not make amends for any deficiency in this. 
 The method us^d by gunsmiths to ascertain this is by a cylindrical plug of 
 tempered steel highly polished, about an inch in length, and fitting the bore 
 exactly ; this is screwed upon the end of an iron rod, and introduced into the 
 cavity of the barrel, where it is moved backwards and forwards ; and the places 
 where it passes with difficulty being marked, the boring bit is repeatedly passed 
 until it moves with equal ease through every part. In forming the breech, a 
 tap is introduced into the barrel, and worked from left to right, and back again, 
 until it has marked out the first four threads of the screw ; another less conical 
 tap is introduced ; and when this has carried the impression of the screw as far 
 as it is intended to go, a third one, nearly cylindrical, is made use of, scarcely 
 differing from the plug of the breech intended to fill the screw thus formed in 
 the barrel ; the plug itself has its screw formed by means of a screw plate of 
 tempered steel, with several female screws corresponding with the taps em- 
 ployed for forming that in the ban-el. Seven or eight threads make a sufficient 
 length for a plug ; they ought to be neat and sharp, so as completely to fill the 
 turns made in the barrel by the tap. The breech plug is then to be case-har- 
 dened, or to have its surface converted into steel by covering it with shavings 
 of horn, or the parings of the hoofs of horses, and keeping it for some time red 
 hot, after which it is plunged in cold water. 
 
 The above is the usual method of making the common barrels, especially for 
 fowling pieces ; but there are some other methods of manufacture by which
 
 656 GUN. 
 
 they are thought to be considerably improved. One kind of these are called 
 twisted barrels, and by the English workmen are formed out of the plates made 
 of stubs, as above described. Four of these, of the size already mentioned, 
 are requisite to make one barrel ; one of them heated red hot for five or six 
 inches, is turned like a cork-screw by means of the hammer and anvil, the 
 remaining parts being treated successively in the sam? manner until the whole 
 is turned into a spiral forming a tube, the diameter of which corresponds with 
 the bore of the intended barrel. Four are generally sufficient to form a barrel 
 of the ordinary length, that is from 32 to 38 inches ; and the two which form 
 the breech or strongest part, called the reinforced part, are considerably thicker 
 than those which form the muzzle or fore part of the barrel : one of these tubes 
 is then welded to a part of the old barrel to serve as a handle ; after which the 
 turns of the spiral are united by heating the tube two or three inches at a timo 
 to a bright white heat, and striking the end of it several times against the 
 anvil in a horizontal direction with considerable force, which is called jumping 
 the barrel ; and the heats given for this purpose are called jumping heats. The 
 next step is to introduce a mandril into the cavity, and to hammer the heated 
 portion lightly, in order to flatten the ridges or burrs raised by the jumping at 
 the place where the spirals are joined. As soon as one piece is jumped 
 throughout its whole length, another is welded to it and treated in the same 
 manner until the four pieces are united, when the part of the old barrel is cut 
 off as being no longer of any use. The welding is repeated three times at 
 least, and is performed exactly in the same manner as directed for plain 
 barrels ; and the piece may afterwards be finished according to the directions 
 already given. The advantages of twisted barrels are, after all, somewhat pro- 
 blematical, where there is so much of welding ; and that in a spiral form, the 
 welding is more likely to be done in a careless manner, or with some imper- 
 fection in some part, than when it is a plain, is an obvious business ; nor have 
 we observed that twisted barrels are leas liable to burst than plain ones, where 
 the latter have been well and carefully forged. The manufacture of rifle bar- 
 rels, in their first formation, is exactly similar to that of other barrels, except 
 that their external form is generally octagonal, instead of being smooth on the 
 inside, like the common pieces, they are formed with a number of spiral chan- 
 nels resembling those of a screw, except only that the threads or rifles are less 
 deflected, makrng only one turn, or a little more, in the whole length of the 
 
 Eiece. This construction of the barrel is employed for correcting the irregu- 
 irity in the flight of balls from smooth barrels. The rifle barrels which have 
 been made in England, where they are not very common, are contrived to be 
 charged at the breech, the piece being for this purpose made larger there than 
 in any other part ; the powder and bullet are put in through the side of the 
 barrel by an opening, which, when the piece is loaded, is filled up with a screw; 
 by this means, when the piece is fired, the bullet is forced through the rifles, 
 and is projected with greater truth. The principal imperfections to which gun 
 barrels are liable are the chink, crack, and flaw >, the first is a small rent in the 
 direction of the length of the barrel ; the second across it ; and the third is a 
 kind of scale or small plate adhering to the barrel by a narrow base, from 
 which it spreads out like the head of a nail from its slTank, and, when sepa- 
 rated, leaves a pit or hollow in the metal. The chink or flaw are of much 
 worse consequence than the crack in fire-arms, the force of the powder being 
 exerted more upon the circumference than the length of the barrel. The flaw 
 is much more frequent than the chink, the latter scarcely ever occurring but in 
 plain barrels formed out of a single plate of iron, and then only when the 
 metal is deficient in quality : when flaws happen on the outside they are of no 
 great consequence ; but in the inside they are apt to lodge moisture and foul- 
 ness, which corrode the iron, and thus the cavity enlarges continually till the 
 piece bursts. This accident, however, may arise from many other causes 
 besides the defect of the barrel itself; the best pieces will burst when the ball 
 is not sufficiently rammed home, so that a space is left behind it and the 
 powder ; a very small windage or passage for the inflamed powder between the 
 sides of the barrel and ball will be sufficient to prevent the accident ; but if
 
 GUN. 657 
 
 the ball has been forcibly driven down with an iron ramrod, so as to fill up the 
 cavity of the barrel very exactly, the piece will almost certainly burst, if only 
 a very small place is left between it and the powder ; and the greater the space 
 is, the more certainly does the event take place. A piece will undoubtedly burst 
 from having its mouth stopped up with earth or snow ; which accident some- 
 times happens to sportsmen in leaping a ditch, in which they have assisted 
 themselves with their fowling-piece, putting the mouth of it to the ground ; 
 and when this did not happen, it is only to be accounted for from the stoppage 
 being extremely slight. For the same reason, a musket will certainly burst if 
 it is fired with the muzzle immersed only a very little way in water ; it will 
 also burst from an overcharge ; but when such an accident happens in other 
 circumstances, it is most probably to be attributed to a defect in the workman- 
 ship, or in the iron itself. These defects are principally an imperfection in the 
 welding, a deep flaw having taken place, or an inequality in the bore ; which 
 last is the most common of any, especially in the low priced barrels. The 
 reason of a barrel's bursting from the inequality of the bore is, that the elastic 
 fluid set loose by the inflammation of the powder, and endeavouring to expand 
 itself in every direction, being repelled by the stronger parts, acts with addi- 
 tional force against the weaker ones, and frequently bursts through them, 
 'vhich it would not have done had the sides been equally thick and strong 
 throughout. With regard to defects arising from the bad quality of the iron, 
 it is impossible to say any thing certain, as the choice of the materials depends 
 entirely on the gunsmith. The only way to be assured of having a barrel made 
 of proper metal, is to purchase it of a manufacturer of known reputation, and 
 to give a liberal price for the piece. 
 
 The recoil of a gun becomes an object of importance only when it is very 
 great, for every piece recoils in some degree when it is discharged. The most 
 frequent cause of an excessive recoil is an inequality in the bore of the barrel ; 
 and by this it will be occasioned even when the inequality is too small to be 
 perceived by the eye. The explanation of this upon mechanical principles, 
 indeed, is not very obvious ; for as it is an invariable law that action and re- 
 action are equal to one another, we should be apt to suppose that eveiy time a 
 piece is discharged it should recoil with the whole difference between the velo- 
 city of the bullet and that of the inflamed powder. The cause to which too 
 great a recoil in muskets has been usually attributed, is the placing of the 
 touch-hole at some distance from the breech-plug, so that the powder is fired 
 about the middle, or towards its fore part, rather than at its base ; to avoid this, 
 a groove or channel is often made in the breech-plug as deep as the second or 
 third turn of the screw, the touch-hole opening into this channel, and thus 
 firing the powder at its very lowest part. It appears, however, from a number 
 of experiments made upon this subject by M. Le Clere, that it made very little 
 difference with regard to the recoil, whether the touch-hole was close to the 
 breech, or an inch distant fr6m it. The only circumstance to be attended to 
 with respect to its situation, therefore, is, that it be not quite close to the breech- 
 plug, as in such a case it is found to be more apt to be choked up than when 
 placed about a quarter of an inch from it. It was formerly supposed, that the 
 longer gun barrels were made the greater would be the distance to which they 
 carried the shot, and that without any limitation. This opinion continued to 
 prevail till near a century ago, when it was first proposed as a doubt whether 
 long barrels carried fuither than short ones. Mr. Robins informs us, that "if 
 a musket barrel of the common length and bore is fired with a leaden bullet 
 und half its weight of powder, and if the same barrel is afterwards shortened 
 one-half, and fired with the same charge, the velocity of the bullet in this 
 shortened barrel will be about one-sixth less than what it was when the barrel 
 was entire ; and if, instead of shortening the barrel, it is increased to twice its 
 usual length, when it will be near eight feet long, the velocity of the bullet will 
 not be augmented more than one-eighth part; and the greater the length of 
 the barrel is in proportion to the diameter of the bullet, and the smaller the 
 quantity of powder, the more inconsiderable will these alterations of velocity 
 be." From these considerations it appears that the advantages gained by long
 
 658 GUNPOWDER. 
 
 barrels are by no means equivalent to the disadvantages arising from the weight 
 and incumbrance of using them ; and from a multitude of experiments, it is 
 now apparent that any one may choose what length he pleases without any 
 sensible detriment to the range of the piece. The most approved lengths are 
 from 30 to 36 inches. An opinion has generally prevailed among sportsmen, 
 that by some unknown manoeuvre the gunsmith is able to make a piece loaded 
 with small shot, throw the contents so close together, that even at the distance 
 of 40 or 50 paces the whole will be confined within the breadth of a hat. From 
 such experiments as have been made on this subject, however, it appears that 
 the closeness or wideness with which a piece throws its shot, is liable to in- 
 numerable variations from causes which no skill in the gunsmith can possibly 
 reach. So variable are these causes, that there is no possibility of making the 
 same piece throw its shot equally close twice successively. In general, how- 
 ever, the closer the wadding is the better disposed the shot seems to be to fall 
 within a small compass. In firing with small shot a curious circumstance 
 sometimes occurs, viz. that the grains, instead of being equally distributed 
 over the space they strike, are thrown in clusters of 10, 12, 15, or more; 
 whilst several considerable spaces are left without a grain in them. Sometimes 
 one-third or one-half of the charge will be collected into a cluster of this kind ; 
 nay, sometimes, though much more rarely, the whole charge will be collected 
 into one mass, so as to pierce a board near an inch thick at the distance of 40 or 
 45 paces. Small barrels are said to be more liable to this clustering than large 
 ones ; and M. de Marolles informs us that this is especially the case when the 
 barrels are new, and likewise when they are fresh washed ; though he acknow- 
 ledges that it did not always happen with the barrels he employed, even after 
 they were washed. It is probable, therefore, that the closeness of the shot depends 
 on some circumstance relative to the wadding rather than to the mechanism of 
 the barrel. 
 
 The lock of the gun, which comes next to be considered, was originally only 
 a cleft piece of iron, moving on a pin fixed in a stock. To this succeeded the 
 wheel lock, so called from a small wheel of solid steel, which being let off by 
 a spring, by its rapid evolutions elicited fire from the flint, and ignited the 
 priming. This was superseded by the snaplance, in which a motion was given 
 to the cock which held the flint, and a movable plate of steel called the frizel, 
 or hammer, was placed vertically above the pan to receive it. A great many 
 improvements in gun locks have been made during the last twenty or thirty 
 years, which have contributed to render this part of the gun admirably efficient. 
 Our space will not permit us to enter into details ; we therefore refer the reader 
 to the periodical works descriptive of patent inventions. The important requi- 
 sites in a gun lock are, that the action of the cock be as rapid as possible, and 
 that it should be so placed, that on uncovering the pan the flint may point into 
 the centre of the priming, and as near to it as possible, without touching it ; 
 the main spring should have a smooth and active motion ; the hammer spring 
 should be light, and should give a slight resistance to the cock on its striking 
 the steel, which ought to move on a roller. 
 
 The stocks of guns have assumed a great variety of forms. Sportsmen's 
 guns, till within these thirty years, were made very crooked in the stock, and 
 no regard was then paid to the balance of the piece ; since that period straight 
 stocks have been universally adopted, and the length of the stock has been 
 accommodated to the stature of the person for whom it is made. 
 
 GUNNERY. The art of employing artillery and other fire-arms against an 
 enemy with the best effect, including every thing that is necessary to a com- 
 plete knowledge of the most approved methods of mounting, transporting, 
 charging, directing, discharging, &c. s the above. It includes also a knowledge 
 of pyrotechny, the theory, force, and effect of gunpowder, the proportions of 
 powder and ball required to produce a proposed effect ; and rules for computing 
 the range of the projectile, the elevation of the piece, &c. 
 
 GUNPOWDER. The origin of the invention of gunpowder is a question 
 upon which the learned are by no means agreed; some attributing it to 
 Schwartz, a German monk, in 1320, others to Roger Bacon, who lived nearly
 
 GUNPOWDER. 659 
 
 a hundred years prior to that date; whilst other writers again contend, and 
 with every appearance of probability, that the invention had its rise in the 
 East, and that it has been known to the Indians and Chinese for thousands of 
 years. The most improved proportions for the composition of gunpowder are 
 75 parts by weight of nitre, to 16 of charcoal, and 9 of sulphur, which being 
 separately reduced to a fine powder, are intimately blended together with a 
 small quantity of water. This operation was formerly performed in wooden 
 mortars, with wooden pestles ; in the large way by means of a mill, wherein 
 the mortars were disposed in rows, and in each of the mortars a pestle was 
 moved by the arbor of a water wheel. The heat, however, produced by the 
 blows of the pestle, occasioned such frequen* explosions, that an Act of Par- 
 liament was passed in the 12th of Geo. III. prohibiting their use, and limiting 
 the licenses to mills similar in principle to the one which we shall describe 
 towards the close of this article. The mixture is, from time to time, mois- 
 tened with water which serves to prevent its being dissipated in the pulverulent 
 form, and likewise obviates the danger of explosion. When tbt process of 
 blending the materials together in this manner is complete, (winch requires 
 several hours,) the gunpowder is in fact made, and only requires to be dried, to 
 render it fit for use. The granulation of gunpowder is effected by placing the 
 mass, while in the form of a stiff paste, in a wire sieve, covering it with a 
 board, and agitating the whole ; by the pressure of the board, it is thus cut 
 into small grains or parts. The powder is smoothed or glazed, as it is called, 
 for small arms, by the following operation : a hollow cylinder or cask is 
 mounted on an axis, and turned by means of a water-wheel or other power ; 
 this cask is half filled with powder, and turned for six hours, and thus by the 
 mutual friction of the grains of powder, it is smoothed or glazed. The fins 
 mealy part thus separated from the rest is again granulated. The granulation 
 causes it to take fire more readily, as the inflammation is more speedily propa- 
 gated through the interstices of the grains. The variations in the strength of 
 different samples of gunpowder are generally owing to the more or less minute 
 division and intimate mixture of the parts ; the reason of this may be easily 
 deduced from the consideration, that nitre does not detonate until in contact 
 with inflammable matter, consequently the whole detonation will be the more 
 speedy the more numerous the points of contact. For this reason also the 
 ingredients should be very pure, as the mixture of any foreign matter not only 
 diminishes the quantity of effective ingredients, but prevents their contact by 
 its interposition. The elastic product obtained by the detonation of gunpowder 
 was found by Berthollet to consist of two parts of nitrogen gas, and one part 
 of carbonic acid gas. The sudden extrication and expansion of these gases are 
 the cause of the effects of gunpowder. 
 
 We shall now proceed to describe an improved gunpowder mill invented by 
 Mr. James Monk, the manager at the gunpowder mills of Messrs. Burton, 
 Children, and Burton, near Tunbridge. Some few years ago a model and descrip- 
 tion of it was presented to the Society of Arts, who voted to Mr. Monk their 
 silver medal and twenty guineas, as a mark of their sense of its merits. aaFig. 1, 
 on the following page, is a compound lever, formed of two iron bars, the extre- 
 mities of which terminate above the bedstones of the pair of mills, A B ; these 
 levers are connected at their other extremities by a bolt at b, forming a joint, and 
 permitting the levers to move so as to form a very obtuse angle, when a powei 
 from below upwards is applied to either of the ends of the levers a a as shown by the 
 dotted lines, c c are two oblong holes in the lever bars, through which two screws 
 are put, which, being screwed into the two uprights, constitute the two fixed 
 fulcrums of the levers ; d d are two uprights, with an eye or loop in each to 
 receive and steady the ends of the lever, which are made long enough to allow 
 the bars to take the position indicated by the dotted lines ; e e are two blowers, 
 made of thin sheet iron, in the form of hollow three-sided pyramids, and are 
 suspended by two iron rods to the ends of the levers a a. These blowers are 
 placed as near as possible to the tops of the upright stone shafts, and as close 
 to the wheels as the timber will allow ; // are two copper chains attached by 
 one end to the lever bars, and by the other supporting two copper valves, which.
 
 CGO 
 
 GUNPOWDER. 
 
 are not seen in Fig. 1, being inside the tubs; but one of them is shown at g in 
 the section of a tub, Fig. 2. h h are two oval tubs capable of holding six 
 gallons of water, and having a circular hole at the bottom ; surrounding this 
 hole is a grooved block having a cylindrical channel all round it, into which the 
 bottom edges of the cylindrical valves fit, shown in section at Fig. 2. i i are 
 two small spring catches fastened to the two uprights. The lever bars are laid 
 on the top of these catches, so that when the ends of the levers rise, that part 
 
 of the lever which is on the catch moves downwards, as shown by the dotted 
 lines, till it slips over the end of the catch, and thus the lever is prevented from 
 resuming its horizontal position till released from the catch. In order to fit 
 that part of the apparatus above described for action, bring the lever to a hori- 
 zontal position, place the valve g in the circular channel at the bottom of the 
 tub so as to cover the hole ; fill the channel with mercury, and then fill the tub 
 with water ; hence it is evident that the water is prevented by the mercury 
 from escaping out of the tub so long as the valve remains in its place. Now, 
 if an explosion happen in either of the mills, the blower e hanging over the 
 bedstone will be thrown up, and the lever will, in consequence, be brought into 
 the position indicated by the dotted line, and will be retained there by the 
 spring catches i i ; at the same time the valves g will be drawn up out of the
 
 HAIR. 661 
 
 mercury, and the water in both tubs will pour do\rn on their respective bed- 
 stones, extinguishing in one the inflamed powder, and in the other preventing 
 it from taking fire. In a certain stage of the grinding the materials are apt to 
 ciot and adhere to the runners ; parts of the bedstones are thus left bare, and 
 the runner and bedstone coming in contact, an accidental spark may be 
 elicited, and an explosion ensue. To prevent this most usual cause of acci- 
 dents, Mr. Monk fixes to the axles of the wheel a scraper formed of a curved 
 piece of wood fc shod with copper, which, being placed behind and almost 
 touching each of the runners, scrapes off the powder as it collects, and thus 
 keeps each of the bedstones always covered. I is the greater water-wheel, 
 which gives motion to the rest ; m m are two vertical beveled wheels, fixed on 
 the axis of the great wheel ; n n two horizontal bevel wheels working in m m, 
 and turning the vertical shafts, upon the upper part of which are also fixed two 
 horizontal wheels oo, which drive the wheels pp. To the shafts of these latter 
 wheels are fixed the runners q q, which traverse on the bedstones u u ; v v are 
 the curbs surrounding the bedstone to keep the powder from falling off. The 
 mill A presents a view, and the mill B a section of the bedstone and curb. 
 Fig. 2 shows the position of the apparatus after an explosion has taken place ; 
 the valve being raised up out of the channel, and the water pouring down on 
 the bedstone. 
 
 GUNWALE, OR GUNNEL, is the piece of timber in a ship which reaches 
 on either side from the half-deck to the forecastle, being the uppermost bend, 
 which finishes the upper works of the hull in that part. 
 
 GYPSUM. A substance which is very abundant in nature, and is now de- 
 nominated, according to the new chemical arrangement, the sulphate of lime. 
 It forms immense strata, composing entire mountains ; it is found in almost 
 every soil, either in greater or less quantities ; it is contained in the waters of 
 the ocean, and in almost all river and spring water. In these its presence is 
 the cause of the quality termed hardness, which may be known by the water 
 being incapable of forming a solution of soap, the sulphuric acid seizing on the 
 alkali of the soap, and the oil forming a compound with the lime. Sulphate of 
 lime is insipid, white, and soft to the touch ; water will not hold a five-hun- 
 dredth part of it in solution. Exposed to heat it appears to effervesce, which 
 phenomenon is caused by the expulsion of water ; it becomes opaque, and falls 
 into powder. This powder, when its water has been driven off by the appli- 
 cation of a red heat, absorbs water rapidly, so that if it be formed into a paste 
 with water, it dries in a few minutes. In this state it is called plaster of Paris, 
 and is employed for forming casts, and for a variety of purposes in the art of 
 statuary. 
 
 H. 
 
 HACKLE. An instrument or tool used in hackling or straightening the fibres 
 of flax. It consists of several rows of long sharp iron teeth, fixed in a piece 
 of wood, and placed with their points upwards before the workman, who strikes 
 the flax, which he holds in his hand, upon the teeth of the hackle, drawing it 
 quickly through them. According to the quality of the flax, or the purpose 
 for which it is designed, the workmen use a hackle with finer, coarser, or wider 
 teeth ; but generally using a coarse one first and a finer afterwards. See FLAX. 
 
 HAEMATITES. An ore of iron. 
 
 HAIR. Slender filaments issuing out of the pores of the skins of animals, 
 and serving most of them as a covering. All hair appears round; but the 
 microscope shows them to be of various shapes, as square, triangular, hexai* 
 gular, &c. The human hair forms a considerable article of commerce, princi 
 pally for the manufacture of perukes. The hair of northern countries is 
 preferred on account of its greater strength and length. Hair is sometimes 
 bleached on the grass like linen, -after previous washing and steeping in a 
 bleaching liquid ; it may then be dyed of any colour. When it does not curl 
 naturally, it is made to do so by first boiling it and then baking it in an oven. 
 4 p
 
 662 HAND-MILLS. 
 
 M. Vanquelin, who investigated the chemical constituents of hair, found that 
 red hair differs from black only in containing a red oil instead of a blackish 
 green oil ; and that white hair differs from both these only in the oil being 
 nearly colourless, and in containing phosphate of magnesia, which is not found 
 in them. Hair is usually distinguished into various kinds ; the stiffest and 
 strongest, such as those on the back of swine, are called bristles. The soft and 
 
 enable, like that on sheep, is called wool ; and the finest of all is called down, 
 air is also woven into cloth (of which it forms only the weft) for covering the 
 peats of chairs and sofas, besides other purposes. 
 
 HAIR POWDER. The starch of wheat finely pulverized, and variously 
 scented. 
 
 H ALBERT, or HALBERD. A kind of spear having a staff about six feet 
 long, much in use formerly, but now chiefly confined to the Serjeants of 
 foot. 
 
 HAM. The leg or thigh of pork, dried, seasoned, and prepared to make it 
 keep, and give it an agreeable flavour. Westphalia hams, which are most 
 esteemed, are prepared by salting them with saltpetre, pressing them for eight 
 or ten days, then steeping them in juniper water, and drying them in the smoke 
 of juniper wood. The curing of hams in this country is, first, by common 
 salting, to extract the blood ; the hams are then wiped dry, and afterwards 
 salted in a mixture of common salt, saltpetre, and brown sugar ; in this pickle 
 they remain for about three weeks, and are afterwards dried in a chimney, or 
 on the great scale, in a stove constructed for the purpose. 
 
 HAMMER. A well-known instrument used by workmen, of which there 
 are numerous varieties, adapted to the peculiar work they are designed for. 
 The general form is that of an iron head, having a handle at right angles to it. 
 The class called rivetling hammers have the handle fixed to them. by passing it 
 through a hole in the head, where it is made to fit or be wedged firmly ; the face 
 is formed of steel, as well as the rivetting end (called the pans), which are welded 
 to the iron. These hammers are used by carpenters, smiths, engineers, and 
 numerous artisans, and vary in some peculiarities of form ; and as respects 
 weight, from an ounce to many pounds, or that of a sledge-hammer. Of the 
 last mentioned there are various sorts and sizes ; also of hand or up-hand 
 .hammers, which are a medium size between the two before mentioned, and 
 are so called from the capacity of the w rkman to use them with one hand. A 
 variety of hammers having two claws, called claw hammers and Kent hammers, 
 are extensively used by carpenters and other trades, as the claw, together with its 
 handle, forms a powerful lever for drawing nails and other purposes requiring 
 great force. The late Mr. Walby, of Islington (who is succeeded by his son), 
 distinguished himself by the construction of a very ingenious apparatus, by which 
 he worked a hammer at the rate of 800 blows per minute, in the manufacture of 
 a very superior quality of bricklayers' 'trowels. For the construction and mode 
 of working those prodigious hammers, called tilt-hammers, see the article IRON. 
 
 HAMMOCK. A suspended bed, usually consisting of a piece of sacking 
 about three feet wide and six feet long, gathered or drawn together at the two 
 ends, and suspended from only one point at each end. They are chiefly used 
 on ship-board, and between decks; in warm countries they are likewise 
 employed for persons to sleep in the open air, by suspending them to posts 
 or to trees. 
 
 HAND, A measure of four inches, or that of the clenched fist. 
 
 HANDCUFFS. Two circular pieces of iron, provided with hinge joints to 
 open and shut them by, and a lock to secure them when together; employed 
 to secure prisoners or malefactors. 
 
 HAND-MILLS. This term does not properly apply to any specific kind of 
 mill, but to all that are worked by hand, such as those employed in the domestic 
 .offices .of grinding coffee, pepper, &c. There are, however, mills of a larger 
 description, which are also worked by hand for grinding malt, wheat, and other 
 substances ; and in the houses for the reception and employment of the 
 poor, it is not uncommon to employ the united force of a great number of 
 persons in grinding corn and dressing the meal for the establishment; and the
 
 HAND-M1U.S. 
 
 663 
 
 mode of applying their power is almost uniformly that of turning a winch ot 
 crank, made of sufficient length for that purpose. The winch undoubtedly 
 possesses the advantages of great simplicity and convenience ; and it has pro- 
 bably, on those accounts, been generally adopted. It has, however, been the 
 opinion of many eminent mechanics, that the most effective mode of employing 
 human force, is the action of rowing u boat. On this point the ingenious 
 Dr. Desaguliers observed, that more muscles are employed at once for over- 
 coming the resistance, than in any other position ; and that the weight of his 
 body assists in the act of pulling backwards. The following mechanical 
 arrangement for carrying the principle into effect is given in Brockler's 
 Theatrum Machinarum. The ver- 
 tical shaft e carries a large 
 toothed wheel c ; the latter being 
 intended to operate partly as a 
 regulating fly. Upon the crank 
 a hangs one end of an iron b, the 
 other end of which hangs upon the 
 lever h /, the motion being per- 
 fectly free at both ends of the bar 
 I. One end of the lever h I hangs 
 upon the fixed hook /, about which, 
 as a centre of motion, it turns ; 
 then, while a man, by pulling at 
 the lever h I, moves the extremity 
 I from I to k, the bar b, acting upon 
 the crank a, gives to the wheel 
 c half a rotation ; and the momen- 
 tum it has acquired will carry them 
 on, the man at the lever suffering it to turn back from k to /, while the other 
 half of the rotation of the wheel is completed. In like manner another 
 sufficient pull at the lever h I gives another rotation to the wheel c, and so 
 on at pleasure. The wheel c turns by its teeth the trundle d, the spindle of 
 which carries the upper mill-stone. If the number of the teeth in the wheel 
 c be six times the number of the cogs in the trundle d, then the labourer, by 
 making ten pulls at the lever h I in a minute, will give sixty revolutions to the 
 upper mill-stone in the same space of time. 
 
 We have given insertion to this "rowing-mill," as it is termed, on account 
 of the great praise bestowed upon it by succeeding eminent writers ; but we 
 cannot regard it as a very judicious mode of carrying the principle into effect, 
 for two reasons"; First, the large wheel making but ten revolutions per minute, 
 will not become a very efficient regulator of power; if fixed upon the first 
 motion, it must be made inconveniently large or weighty to collect the requisite 
 force to be useful. If a fly-wheel be used at all, it should be put on the axis 
 of the trundle d, where the velocity is six times greater ; the increased 
 momentum it would here acquire, would far more than compensate for the 
 small loss of effect by its removal farther from the motive force. But we doubt 
 much the use of a fly-wheel at all in the present case, because a heavy mill- 
 stone is put into operation ; and that is, in effect, a far more efficacious fly- 
 wheel than the above described. Second, because we think the inventor has 
 imitated the defects as well as the advantages of the rowing action. In this 
 mill the workman is supposed to pull the lever h I through the arc of a circle 
 Ik; and this indirect action, it will be noticed, is performed in a horizontal 
 plane, by which a contortion of the man's body results that must be unfavour- 
 able to his health, and the most efficient exercise of his strength. To avoid 
 these defects in the rowing-mill, we propose the following simplified, and, we 
 trust, improved arrangement, a represents a seat for one or two men ; b a 
 board to press their feet against in pulling back by the cross handle c, which is 
 connected to a rod d that slides straight through brasses fixed in a standard e ; 
 at / is a hinge joint, which permits the connecting rod g to vibrate with the 
 Devolution of the crank h, whose axis actuates the wheel , the pinion or
 
 664 
 
 HARMONICA 
 
 trundle/ on the axis A of which, is fixed the runner-stona /, serving also tho 
 office of a fly-wheel. In applying the labour of more men to an apparatus of 
 this kind, there would be some advantage in placing them opposite to each 
 other so that a pull should be made each way. For this purpose the rod da 
 
 might be lengthened, another seat be placed on the other side of the standard e, 
 and another cross handle between d and/; the men sitting here on each side 
 of the rod d. 
 
 Having now explained what is deemed the most advantageous application of 
 manual labour to mills, and the undefined nature of the term which heads this 
 article, we refer the reader for more information on the subject, and that of mills 
 generally, to the article MILL. 
 
 HANDSPIKE. A name given to a simple lever consisting of a bar of wood 
 or iron, chiefly used on board ship for heaving round the windlass. 
 
 HARBOUR. A place where ships may lie at anchor, secure from storms. 
 The principal qualities of a good harbour are, sufficient depth of water to float 
 the largest ships, and sufficient breadth and depth for them to enter with facility, 
 and without danger of foundering. The ground should be firm, and free from 
 rocks. It is desirable that they be surrounded by lofty hills or mountains, to 
 screen them from high winds, and the better if so far inland as to derive there- 
 
 an enemy at sea. They 
 irect ships at night, and 
 
 from increased security against being bombarded by 
 
 should also be provided with a good light-house to di 
 
 with numerous buoys, posts, moorings, &c. Harbours are sometimes formed 
 
 artificially, either wholly or partially, by the building of moles, breakwaters, 
 
 piers, and sometimes by large floating masses of timber, which rise and fall 
 
 with the tide. See the articles BUOY, BREAKWATER, and CAISSON. 
 
 HARDNESS. Tre resistance opposed by a body to the separation of its par- 
 ticles. This property depends on the force of cohesion, or on that which 
 chemists call affinity, joined to the arrangement of the particles to their figure, 
 and other circumstances. The differences between hard bodies, such as are, 
 soft, and such as are elastic, have been thus defined. The soft body yields to 
 pressure without spontaneously returning to its previous form on taking off the 
 pressure ; the elastic body returns to its original form upon removing the force 
 applied ; while that which is strictly hard breaks asunder when overcome by the 
 force brought against it. It is, however, justly doubted whether there is any 
 body in nature that is perfectly hard, perfectly soft, or perfectly elastic ; for all 
 bodies seem to possess these three qualities, though in proportions indefinitely 
 various. 
 
 HARDENING and CASE-HARDENING. See IRON and STEEL. 
 
 HARMONICA. Th name given to a musical instrument invented by
 
 HARPOON. 665 
 
 Dr. Franklin, in which the tones are produced by friction against the edges of a 
 series of glasses. The glasses are blown as near as possible into the form of hemi- 
 spheres, having each an open neck or socket in the middle. The thickness of 
 the glass near the brim is about one-tenth of an inch, but thicker as it comes 
 nearer the neck, which, in the largest glasses, is about an inch deep, and an 
 inch and a half wide within ; these dimensions lessening as the glasses them- 
 selves diminish in size, except that the neck of the smallest ought not to be 
 shorter than half an inch. The largest glass is nine inches in diameter, and 
 the smallest three inches. Between these there are twenty-three different 
 sizes, differing from each other a quarter of an inch in diameter. The glasses 
 being chosen, and every one marked with a diamond the note for which it is 
 intended, they are to be tuned by diminishing the thickness of those that are 
 too sharp. This is done by grinding them round from the neck towards the 
 brim, the breadth of one or two inches, as may be required, often trying the 
 glass by a well-tuned piano-forte or harpsichord. The largest glass in the 
 instrument is C, a little below the reach of a common voice, and the highest G, 
 including three complete octaves ; and they are distinguished by painting the 
 apparent parts of the glasses within side, every semitone white, and the other 
 notes of the octave with the seven prismatic colours; so that glasses of the 
 same colour (the white excepted) are always octaves to each other. The glasses 
 being tuned, they are to be fixed on a round spindle of hard iron, an inch in 
 
 according to the dimensions of the spindle in that part of it where they are to be 
 fixed. The glasses are all placed one within another, the largest on the biggest 
 end of the spindle, with the neck outwards ; the next in size is put into the 
 other, leaving about an inch of its brim above the brim of the fipst ; and the 
 others are put on in the same order. From these exposed parts of each glass 
 the tone is drawn by laying a finger upon one of them as the spindle and glasses 
 turn round. The spindle thus prepared is fixed horizontally in the middle of a 
 box, and made to turn on brass gudgeons at each end. A square shank comes 
 from its thickest end through the box, on which shank a fly-wheel, to equalize 
 the motion, is fixed. This wheel is made of mahogany, eighteen inches in 
 diameter, and pretty thick, to conceal near its circumference about 25lbs. of 
 lead. An ivory pin is fixed to the face of this about four inches from the axis, 
 and over the neck of this pin is put the loop of a string from a treadle, by which 
 the machine is put in motion. The whole is put in a neat case, and stands on 
 a frame with four legs. The case is three feet long; eleven inches wide at the 
 largest end, and five at the smallest ; it is made with a lid, which opens at the 
 middle of its height, and turns up by back hinges : the instrument is played 
 upon by sitting before the middle of the set of glasses, turning them with the 
 foot, and wetting them now and then with a sponge and clean water. The fin- 
 gers should be first a little soaked in water, and quite free from greasiness ; a 
 little fine chalk is sometimes useful to make them catch the glass, and bring out 
 the tone more readily. Both hands are used, by which means different parts 
 are played together. " The advantages of this instrument are," says Dr. 
 Franklin, " that its tones are incomparably sweet beyond those of any other ; 
 that they may be swelled and softened at pleasure by stronger or weaker pres- 
 sures of the finger, and continued to any length, and that the instrument being 
 once well tuned, never again wants tuning." 
 
 HARNESS. The furniture and equipments of horses, to adapt them for 
 drawing carriages, and for being dri.-en, guided, and controlled. The con- 
 stituent parts of harness are noticed under their separate heads. See COLLAR, 
 SADDLE, CARRIAGE, &c. 
 
 HARP. A stringed instrument, consisting of a triangular frame, the chords of 
 which are distended in a parallel direction from the upper parts, to one of its sides. 
 
 HARPOON, or HARPING-IRON. A javelin used to pierce whales, in the 
 Greenland and South Sea fisheries. It has a broad, flat, triangular, barbed 
 head, well sharpened, to penetrate easily, and a shank about two feet long, to
 
 666 HARROW. 
 
 the extremity of which is fastened a long line, which lies carefully coiled in the 
 boat, in such a manner that it may run out easily, and without entangling. 
 As soon as the boat has come within a competent distance of the whale, the 
 harpooner launches his instrument, and the fish, immediately he is wounded, 
 descends with amazing rapidity, carrying the harpoon along with him, and a 
 considerable length of the line, which is purposely let down to give him room 
 to dive. Being soon exhausted with the fatigue and loss of blood, he re-ascends, 
 in order to breathe, where he presently expires, and floats upon the surface of 
 the water; when they approach the carcase by drawing in the whale line. 
 This line is from sixty to seventy fathoms long, and made of the finest and 
 softest hemp, that it may slip easily. To prevent the boat taking fire by the 
 friction of the line against it, it is constantly watered as it passes out. The 
 harpoon is also employed to catch sturgeons, and other large fish. About a 
 century ago, guns were tried for discharging harpoons, on the presumption that 
 they could strike the whales at greater distances than by hand. They were 
 tried for several seasons, but their employment has been ever since abandoned. 
 
 HARPSICHORD. A stringed instrument contained in a large case of 
 wood, having a double or treble row of distended strings, of brass and steel 
 wires, supported by bridges. It is played upon similarly to the piano-forte, but 
 instead of hammers covered with leather, the tone is produced by little upright 
 pieces of wood, called jacks, furnished with pieces of crow-quill, which strike 
 the wires. The piano-forte has now almost wholly superseded the harpsichord. 
 
 HARROW. An agricultural implement, used for raking and levelling the 
 earth. There are two principal distinctions ; namely, the common, and the 
 jointed chain harrow. The common harrow is usually made by framing toge- 
 ther a number of stout parallel bars, by means of the like number of similar 
 bars, equidistant, and crossing the others at right angles, thus leaving 
 uniform square spaces between them. To strengthen this frame, a bar is 
 fixed diagonally across them. The spikes or tangs, which are made from 
 four to twelve inches in length, (according to the nature of the soil, or work 
 to be performed,) are fixed to this frame either by nuts and screws, or by rivet- 
 ting them down upon iron washers, after passing them through the wood. The 
 frame of course lies flatways upon the ground, with the tangs to the ground, 
 and it is drawn across the field by cattle yoked to a chain fastened to one corner 
 of the harrow. The chain or screw harrow is made to divide diagonally into 
 two parts, thus forming, as it were, two triangular harrows, which are hooked 
 and chained together. This contrivance adapts itself better to the ridges and other 
 inequalities of the ground. Sometimes, in lieu of this, two common harrows 
 are chained together, and applied to effect the same object. 
 
 HARTSHORN SHAVINGS. These shavings, although originally taken from 
 the horns of stags, or harts, which are a species of bone, are now obtained 
 chiefly by shaving down with a plane the bones of calves. They afford a 
 nutritious and speedily formed jelly. 
 
 HARTSHORN, (SPIRIT OF,) is now usually obtained by the distillation of 
 bones, hoofs, horns, and in general the refuse of slaughter-houses. An iron 
 still or retort is generally used with a pipe leading from it into a worm con- 
 denser. The retort is filled with bones roughly broken, or other materials, and 
 a strong heat applied. Water, and a tar-like oil, accompanied with a foetid inflam- 
 mable gas, result ; carbonic acid also comes over, but this is mostly taken up 
 by the ammonia, which is formed at the same time, and received in the state of 
 carbonate of ammonia. When the different substances have been condensed in 
 the worm, they should pass into a receiver, which has no communication with 
 
 the open atmosphere, (on account of the overpowering nuisance of its odour,) 
 but which should have a pipe inserted into the upper part of it, and connected 
 with the ash-pit of the still. The inflammable gas and the smell are conveyed 
 to the fire, where the former ignites ; but care must be taken to avoid any 
 explosion, for when the evolution of the inflammable gas becomes slow, 
 or ceases .entirely, the common air passes along the pipe into the close 
 receiver, which is filled with the same inflammable gas ; and, under these cir- 
 cumstances, an explosion will take place, which will not only burst the receiver,
 
 HATMAKING, 667 
 
 nut do other injury. This evil, Mr. Gray observes, may be avoided by placing 
 a valve in the pipe opening outwards, to allow the passage of the gas; and 
 anothei valve into the receiver, opening inwards ; by this means the flaming gas 
 will be stopped in its passage to the receiver ; as the valve into the receiver open- 
 ing, will admit the common air to fill up the vacuum. Thus, by means of this 
 apparatus, if it be well constructed, and proper luting be employed, the distilla- 
 tion of hartshorn may be carried on almost without any smell, although the 
 odour of animal oil is so remarkably offensive. The first product consists of 
 water, animal tar, and volatile salt. A great part of the tarry oil may be sepa- 
 rated mechanically ; the rest, in a great measure, by a second distillation with 
 a gentle heat. The liquid which comes over consists of a solution of sesqui-car- 
 bonate of ammonia, with a fetid animal oil, which gives it a peculiar odour. 
 This liquid is still sold in the shops under the name of spirit of hartshorn, as 
 the alkaline liquor obtained from that substance was at one time thought to 
 possess certain medical virtues, not to be found in the alkaline liquor obtained 
 from other animal matters. 
 
 HATS. A well-known covering for the head, and distinguished from a cap 
 or bonnet by a brim. They are made by various methods, according to the 
 nature of the substance of which they are composed ; but by far the greatest 
 number are formed of the fur of different animals, by a process called felting : 
 this manufacture has of late years become of considerable commercial impor- 
 tance, and numerous improvements have been introduced into it. The materials 
 for making hats are chiefly rabbits' fur, cut off from the skin, together with 
 wool and beaver, to which may also be added mole fur, and kid hair. These 
 are mixed in various proportions, and of different qualities, according to the 
 value of the hats intended to be made ; but the beaver is now wholly used for 
 facing the finer hats, and not for the main body or stuff. The first process in 
 the manufacture of hats is termed bowing, which has for its object to separate 
 the fibres, and break up any clots, so as to form the whole into a kind of light 
 down : it is performed as follows the workman is provided with a pole of ash, 
 or white deal, about seven feet long, having a bridge at each end, over which is 
 stretched a catgut about ^ of an inch thick ; and a portion of the material being 
 laid upon a hurdle of wire, he holding the bow horizontally in his left hand, 
 nearly in contact with the material, gives the string a pluck with a wooden pin, 
 held in his right hand. The string, in its return, strikes the fur, and causes it to 
 spring up in the air, and fall in a light open form, at a little distance from the 
 mass. By repeated strokes, the whole is subjected to the bow ; and having thus 
 fallen together in all directions, it forms a thin mass or substance for the felt. 
 The quantity thus treated at once is called a batt, and never exceeds half the 
 quantity required to make one hat. 
 
 When the batt is sufficiently bowed, it is ready for hardening, which is the 
 term for the commencement of the felting. The prepared material being evenly 
 disposed on the hurdle, is covered with a linen cloth, and pressed backwards and 
 forwards in its various parts by the hands of the workman. The pressure is gentle, 
 and the hands are very slightly moved backwards and forwards, at the same 
 time, through a space of perhaps a quarter of an inch, to favour the hardening 
 entangling of the fibres. In a very short time, the stuff acquires sufficient 
 firmness to bear carefully handling. The cloth is then taken off, and a sheet 
 of paper, with its corners doubled in, so as to give it a triangular outline, is laid 
 upon the batt, which last is folded over the paper as it lies, and its edges, 
 meeting one over the other, form a conical cap. The joining is soon made good, 
 by pressure with the hands on the cloth. Another batt ready hardened is in 
 the next place laid on the hurdle, and the cap here mentioned placed upon it 
 with the joining downwards. This last batt being also folded up, will have its 
 place of junction diametrically opposite that of the inner felt, which it must 
 therefore greatly help to strengthen. The principal part of the intended hat is 
 thus put together, and now requires to be worked with the hands a considerable 
 time upon the hurdle, the cloth being also occasionally s-prinkled with clear water. 
 During the whole of this operation, which is called basoning, the felt becomes 
 firmer and firmer, and contracts in its dimensions. The use of the paper is to
 
 668 HAT-MAKING. 
 
 prevent the sides from felting together. The basoning is followed by a still 
 more effectual continuation of felting, called working, which consists in plunging 
 them into a cauldron containing water slightly acidulated with sulphuric acid, and 
 then working them upon some planks forming the frustrum of a cone, meeting 
 in the cauldron at the middle. The imperfections of the felting now appear ; 
 and the workman picks out the knots and other hard substances with a bodkin, 
 and adds more fur upon all such parts as require strengthening. This added 
 fur is patted down with a wet brush, and soon incorporates with the rest. 
 Towards the close of this working, the beaver for the nap is laid on. By these 
 means, the substance of the hat is formed into a felt of close texture, pliable, and 
 capable of extension (although with difficulty), in every direction, but the figure 
 is still conical ; the next thing to be done, therefore, is to give it the required shape. 
 For this purpose the workman turns up the edge or brim to the depth of about 
 an inch and a half, and then returns the point back again through the centre 
 or axis of the cap, so far as not to take out this fold, but to produce another 
 inner fold of the same depth. The point being returned again produces a 
 third fold, and thus the workman proceeds until the whole has acquired the 
 appearance of a flat circular piece, consisting of a number of concentric folds 
 or undulations with the point in the centre : this is laid upon the plank, where 
 the workman, keeping the piece wet with the liquor, pulls out the point with 
 his fingers, and presses it down with his hands, at the same time turning it 
 round on its centre in contact with the plank until he has by this means rubbed 
 out a flat portion equal to the intended crown of the hat In the next place he 
 takes a block, to the crown of which he applies the flat central portion of the 
 felt, and by forcing a string down the sides of the block, causes the next part 
 to assume the figure of the crown, which he continues to wet and work until it has 
 
 this part. Water only is used in this operation of blocking or fashioning; at the 
 conclusion of which it is pressed out by the blunt edge of a copper implement 
 called a stamper. Previous to the dying, the nap of the hat is raised or 
 loosened out with a wire-brush or carding instrument. The fibres are too rotten 
 after the dying to bear this operation. The dying materials are logwood, a 
 little oak bark, and a mixture of the sulphate of iron and of copper, known in 
 the mails by the common name of green copperas and blue vitriol. The hats 
 are boiled with the logwood, and afterwards immersed in the same solution. The 
 dyed hats are, in the next place, taken to the stiffening shop. One workman, 
 assisted by a boy, does this part of the business ; he has two vessels or boilers, 
 one containing the grounds of strong beer, and the other containing melted 
 glue, a little thinner than what is used by carpenters. The beer grounds are 
 applied in the inside of the crown to prevent the glue from coming through to 
 the face, and also to give the requisite firmness, at a less expense than could 
 be produced by glue alone. The glue stiffening Is therefore applied after the 
 beer grounds are dried, and then only upon the lower face of the brim and the 
 inside of the crown. The dry hat, after this operation, is always rigid, and its 
 figure irregular. The last dressing is given by application of moisture and 
 heat, and the use of the brush, and a hot iron, as before mentioned, somewhat 
 in the shape of that used by tailors, but shorter and broader on the face. The 
 hat being softened by exposure to steam, is drawn upon a block, to which it is 
 securely applied by the former method of forcing a string down from the 
 crown to the commencement of the brim. The judgment of the workman is 
 employed in moistening, brushing, and ironing the hat, in order to give and 
 preserve the proper figure. Before the hat is quite finished, the brims are cut 
 by a knife attached to a radius rod so as to describe a circle ; the cut is not 
 carried entirely through, so that one of the last operations consists in tearing off 
 the redundant part, which, by that means, leaves an edging of beaver round 
 the external face of the brim. When the hat is thus finished, the crown is tied 
 up in gauze paper, which is neatly ironed down, and it is then ready for the 
 subsequent operations of lining, &c. for sale.
 
 HAT-MAKING. 
 
 6G9 
 
 In that ably conducted work, Nicholson's Journal, Vol. IV. 4to, are several 
 suggestions for effecting many of the foregoing operations by machinery. 
 Amongst other subjects proposed for inquiry are the following : whether 
 carding, which is rapidly and mechanically done, be inferior to bowing; whether 
 a succession of batts or carding might be thrown on a fluted cone, which rapidly 
 revolving in contact with three or more cylinders, might perform the hardening 
 and even the working with much more precision and speed than they are now 
 done by hand ; and whether blocking or shaping be not a process extremely 
 well calculated for the operation of one or more machines. These ingenious 
 suggestions have recently been in some measure acted upon. 
 
 In 1826 Mr. G. Borradaile obtained a patent for an apparatus for the making 
 or setting up of hat bodies, as it is termed, in which several cones or frustrums 
 of cones are made to revolve upon their axes ; and the frames in which these 
 
 cones act being made to vibrate horizontally on a fixed pivot and swivel, the 
 filaments of wool are caused to traverse each other diagonally, as they are 
 wound upon a double cone, and by that means to produce a matted substance, 
 which is afterwards to be wetted, shrunk, and felted together in the usual 
 manner. The bodies of two hats, each of a conical figure, are thus made over 
 the surface of a double cone, which are separated by cutting them along their 
 middle or base line, and slipping them off at the end. a a in the diagram, 
 represents this double conical block, and b b two conical rollers, of which there 
 4 Q
 
 070 HATCHING OF FISH. 
 
 are two more on the opposite side of the machine, not seen in this view. Ine 
 axes of these four rollers are placed in such an inclined position as to admit the 
 double cone a a to bear equally upon them. The two front cones b b have 
 fixed upon their bases two bevelled toothed wheels, which gear into one another 
 as shown ; and rotary motion is given to both by the teeth of one of them 
 taking into a bevelled tooth and pinion that revolves upon a vertical spindle, to 
 which motion is communicated by a band and rigger. The large double cone 
 a a, therefore, is made to revolve slowly by the friction of its surface against the 
 four conical rollers underneath. The sliver of wool being conducted from the 
 doffer of a carding engine, placed behind the machine, to the upper side of 
 the double cone a a, and the cones b b being made to revolve as before 
 described, causes the sliver of wool to be wound round the periphery of a a in 
 an uniform layer. In order to give a diagonal crossing to the filaments, as 
 they are wound upon the double cone, the machine is made to turn partly 
 round horizontally upon the pivot k in front, and upon a swivel joint I at top, 
 to which the back part of the machine is attached by a bent rod m m, the form 
 of which bent rod is explained by the separate Fig. 2. The gearing, by which 
 the vibrating motion of the machine is effected, is not brought into view in the 
 figure, as it could not be distinctly exhibited ; but it may be easily compre- 
 hended that a rotary crank and lever will effect this movement. The plan 
 above described, it will be seen, very closely resembles that suggested by 
 Mr. Nicholson for preparing the bodies of hats ; that which we are about to 
 describe as nearly resembles his plan for finishing them. 
 
 Mr. Ollerenshaw, of Manchester, about the year 1824, took out a patent for 
 a machine for assisting in the dressing and finishing of beaver or felt hats, by 
 which the ordinary labour in those operations is materially reduced, and the 
 work is completed in much less time. It is constructed on the principle of the 
 lathe, and the apparatus consists of three principal parts or lathes, which are 
 all fixed in one strong frame, and motion is given to them by means of a band 
 passing from any first mover, (as a steam-engine, water-wheel, &c. &c.) The 
 first of these lathes is constructed the same as the common wood-turner's lathe, 
 and is used for the purpose of ironing or dressing the sides of the crown ; the 
 block upon which the hat is fixed is made to fit on the chuck of the lathe, and 
 as the hat revolves, the hot iron is applied to the surface by the workman, 
 which quickly smooths the hat, giving it the usual glossy appearance ; the 
 velvet cushion, and the various brushes hatters use, are likewise applied, as 
 may be required, while it is thus revolving, till that part of the hat is finished, 
 when it is removed and placed upon the block of the next lathe. This second 
 lathe is constructed with a vertical shaft, so as to produce a horizontal rotary 
 motion to the hat, which is better suited for operating upon the flat part of 
 the crown, and the upper side of the brim, than a vertical motion. The hat 
 having undergone the usual manipulations in the second lathe, is removed to 
 the third, where it is introduced, in an inverted position, into a frame made to 
 receive it, which turns round very slowly in a horizontal direction (the axis 
 being vertical) ; here the workmen smooth the under side of the brim, by 
 drawing the iron across it from the centre outwards. The hat next undergoes 
 the usual examinations, and pickings-out of the extraneous and coarse hairs ; 
 after this, it is again subjected to the former operations of ironing and brushing, 
 which finishes it. 
 
 HATCH, and HATCHWAY. Hatchway is the square or oblong opening 
 through a ship's deck ; and the cover to it is the hatch, which is sometimes pro- 
 vided with a grating, to admit light and air beneath. 
 
 HATCHET. A small axe used with only one hand. See AXE. 
 
 HATCHING. The production of chickens, or other animals, alive, from 
 eggs, whether by incubation of the parent, or by artificial heat. Under the 
 article EGQS, we have described the mode of hatching chickens by the huat of 
 ovens. In the next article we shall notice the important art of hatching fish, 
 which is practised with much success in China. 
 
 HATCHING OF FISH. The Chinese hatch the spawn offish, by collect- 
 ing it on the margin and surface of the water, and then rilling the shell of a
 
 HELIOMETER. 671 
 
 newly laid egg with the gelatinous matter that contains the spawn. The hole 
 in the egg is waxed over, and it is put under a sitting hen. At the expiration 
 of a certain number of days, they break the shell in water warmed by the sun 
 The young fry are presently hatched, and are kept in pure fresh water till they 
 are large enough to be thrown into the pond with the old fish. The sale of 
 spawn for this purpose forms an important article of trade in China. 
 
 HATCHMENT. The coat of arms of a dead person, usually placed in the 
 front of the house. 
 
 HAUTBOY. A musical instrument provided with keys like a flute, but 
 blown by a reed at one end, and spreading out conically towards the other end. 
 
 HAY. Grass dried in the sunshine. The risk of this operation being suc- 
 cessfully completed, owing to unfavourable changes in the weather, is well 
 known ; and the loss to the farmer in consequence of long continued rains and 
 floods, after the grass is cut, is sometimes very severe. It has occurred to us 
 that a remedy for so serious an evil might be found, in providing some 
 simple temporary erections in the hay field, the cost of which would be far less 
 than the value of the crop saved. Four posts, or hop poles, might be fixed in 
 the ground, so as to form a quadrangle, with one in the middle, of greater 
 height, as a central support, and to form the apex of a conical top or roof. At 
 about a foot from the ground, some very coarse netting might be stretched 
 horizontally from pole to pole, and thereto tied ; a quantity of the green hay 
 might be thrown lightly upon this. Then, above this layer, a second floor of 
 net work might be laid, with a sufficient space underneath for the free passage 
 of the air, and upon it a second stratum of the wet hay may be thrown ; proceeding 
 in this manner, tier above tier, as high as may be convenient ; which, by the 
 assistance of a waggon as a stage, might easily be raised to twelve feet, and be 
 covered either by a tarpaulin, or a conical top of hay. In erections of this 
 kind, the hay would thoroughly dry, and the materials of which they are formed 
 would last many years, might easily be stowed away, and be useful for other pur- 
 poses. The coarse netting in which woollen rags are packed, made of the tarred 
 strands of old cables, would be very cheap, strong, and durable. The Tyrolese 
 have a method of preserving their hay crops which seems to deserve imitation 
 in this country, as it may be perhaps more generally and easily practised. It 
 is thus described by Mr. Brockedon, in a letter to the Society of Arts, &c. 
 " I have observed, in the course of my journeys in the Alpine districts, that 
 the hay is preserved in the meadows and on slopes, in situations where the 
 cocks are exposed to the action of torrents, by being cocked upon stakes 
 having two or three transverse pieces of wood fixed in them. The stake is light, 
 about five or six inches in circumference, and about four or five feet long. 
 These are kept by the farmers in large quantities, and stowed away compactly 
 during winter, under the overhanging roofs of their dwellings. When used, 
 they are driven upright into the ground at convenient distances, and the grass 
 when cut is thrown upon them : it is supported upon the cross pieces or arms 
 of the hay-stake, on which a large cock may be formed ; the lower part is free 
 from the ground, while the outside, raked smooth, carries off the rain ; in this 
 manner it is often left for weeks, if necessary ; the air freely entering and 
 circulating, dries the hay, and frequently it is never spread, except during part 
 of the favourable day in which it is housed. 
 
 HEARTH. The pavement or surface on or over which fuel is burned in 
 apartments. But the term hearth, in naval affairs, implies, the grate and appa- 
 ratus employed on board ship for preparing the food or messes for the ship's 
 company. It is fixed upon deck, in a small covered building, fitted up with a 
 variety of conveniences for the cook and his operations. The modern apparatus 
 usually comprises a steam boiler, coppers, ovens, hot closets, in addition to a 
 large open fire. 
 
 HEAT. See CALORIC, also CHEMISTRY. 
 
 HELIOMETER, or ASTROMETER, is an instrument invented by Bougeur, 
 for measuring with exactness the diameter of the sun, moon, and planets. 
 This instrument is a telescope, having two object-glasses of equal focal distance, 
 placed side by side, so that the same glass serves for both. The tube of this
 
 672 
 
 HELM. 
 
 instrument is of a conical form, larger at the upper end (which receives the 
 two object-glasses) than at the lower, (which is furnished with an eye-glass and 
 micrometer.) Hence, two distinct images are formed in the focus of the eye- 
 glass, the distance of which depending upon that of the two object-glasses from 
 one another, may be measured with the greatest accuracy. 
 
 HELIOSCOPE. A telescope fitted for viewing the sun, without dazzling 
 the eyes, by being provided with object and eye-glasses, that are coloured red 
 or green. Huygens used only a plain glass blacked over the flame of a candle 
 which he placed between the eye and the eye-glass. 
 
 HELIOTROPE is a sub-species of rhomboidal quartz. It is regarded as a 
 precious stone ; the colour green, of various shades, and streaked with red 
 veins. The blood and scarlet-red, and the yellow dots and spots are owing to 
 disseminated jasper. 
 
 HELM. In naval architecture, the apparatus for steering or guiding the 
 motion of a ship. The helm is usually composed of three parts the rudder, 
 the tiller, and the wheel, except in small vessels, where the wheel is unneces 
 sary. The rudder is a long and flat piece of timber, or assemblage of timbers, 
 suspended along the hind part of a ship's stern-post, and turning upon hinges. 
 The tiller is a long beam or lever fitted into the head of the rudder within the 
 vessel, by means of which the rudder is turned to the right or left, as occasion 
 requires. In order that the steersman may remain stationary, so as to see the 
 compass placed in the binnacle, ropes, called tiller ropes, are attached to the 
 end of the tiller, and, passing through leading blocks in the vessel's side, are 
 pulled by the steersman ; where an increased power is required, small tackles 
 
 I I I ! I II I 1 L ; I I 
 
 are employed : but in large vessels, the tiller ropes are wound upon a ban-el or 
 cylinder, which is turned by means of a wheel set upon the same axis, and fur- 
 nished with six or eight projecting spokes. The effect of the rudder in changing 
 the direction of a snip's head, according as it is turned to either side, arises 
 from the current produced by the vessel's passage through the water striking
 
 HELLEBORE. 
 
 673 
 
 more forcibly upon the side which is turned against the current, than upon 
 the opposite side which is turned from it ; and, as the rudder placed at the 
 extreme end of a ship may be considered as appended to a lever, the fulcrum 
 of which is somewhere about the centre of the vessel, the pressure thus 
 exerted against it naturally causes the ship to turn upon the centre of gyra- 
 tion, the effect being proportioned to the velocity of the current, and to the 
 angle at which the rudder stands opposed to it. Ships which have what is 
 called a full buttock, that is, carry their breadth very far aft, are found not to 
 answer the helm readily, owing to the water not coming easily to the rudder. 
 To remedy this defect, a false stern-post is sometimes bolted on, and the breadth 
 of the rudder increased. Mr. E. Carey, surveyor of shipping at Bristol, pro- 
 poses, as a more effectual remedy for vessels having the above defect, to bolt on 
 to the keel a piece one foot six inches abaft, running its breadth two-thirds for- 
 wards, then tapered off to nothing as far as the gripe, and to bolt another piece 
 of equal breadth on to the bottom of the rudder (as shown in the drawings, 
 Fig. 1 and 2, on the preceding page,) which will make the ship hold a better 
 wind, and answer her helm quickly, and steer perfectly easy. By reference to 
 Fig. 3, it will be seen that the effect of the water upon the additional piece will 
 be fully equal to that upon the whole of the rudder before it was put on ; for 
 the water rushing along the flat bottom of the vessel, and along the side of the 
 keel, without obstruction, strikes upon the new piece with great force, and at an 
 advantageous angle, and necessarily makes the vessel answer her helm quickly. 
 Ships of war, and other large vessels, if they happen to strike the ground when 
 riding heavily at anchor, or by tailing on a sand bank, are very liable to injure 
 the rudder by tearing it away from its fas- 
 tenings. To prevent this, Mr. Hillman, 
 of Deptford, proposes that the lower part 
 of the rudder should be made capable of 
 sliding up into a cavity prepared to receive 
 it, and of descending by its gravity into 
 its original position, as soon as the vessel 
 gets clear again. The changes in the 
 construction of the rudder which Mr. Hill- 
 man's plan would occasion, are represented 
 in the subjoined figure, which is a broad- 
 side view of it. a the stern post ; b part 
 of the keel; c the rudder, the bottom of 
 which is cut away to the dotted lines d d; 
 // is a metal segment, turning upon the 
 pin g, and sliding within the case e e ; this 
 segment is made hollow from the top on 
 two compartments, as shown by the dotted 
 lines h h; it falls by its own weight into 
 the position shown in the figure, and is 
 prevented from coming further by a projection from its top, lodging on a step 
 at i, within the case e e. The cavity^', from the bottom of the case e e to the 
 dotted lines dd, is made large enough to receive the whole of the segment//. 
 If, therefore, the vessel should touch the ground, so as to endanger the rudder, 
 this segment would slide into the recess, and thereby avoid the blow, and would 
 fall out again to restore the length of the rudder when clear of the ground. 
 The Society of Arts presented to Mr. Hillman their large silver medal for this 
 invention. 
 
 HELIX, in Geometry, is a term generally used synonymously with spiral; 
 but some authors make a distinction between the heJix and the spiral. Daviler 
 says, that a staircase is a helix or helical when the steps wind round a cylin- 
 drical newel ; but that a spiral winds round a cone, and is continually approach- 
 ing nearer and nearer to its axis. 
 
 HELLEBORE. The root of a plant formerly used in medicine, but 
 now nearly discarded frc-o practice, on account of the violence of its 
 operation.
 
 <J74 HINGES. 
 
 HELMET. A defensive armour for the head, composed usually of the skins 
 of animals and of metals. 
 
 HEMATIN. The colouring principle of logwood, which is obtained by 
 digesting alcohol for a day on the aqueous extract of logwood ; then filtering 
 the solution, evaporating partially, and leaving the liquid to rest, hematin will be 
 deposited in small crystals, which, after washing with alcohol, are brilliant, and 
 of a whitish red colour, having a bitter, acrid and slightly astringent taste. 
 Hematin forms an orange-red solution with boiling water, becoming yellow as 
 it cools, but recovering with increase of heat its former hue. Excess of alkali 
 converts it first to a purple, then to violet, and lastly to brown. Metallic oxides 
 combine with hematin, forming blue-coloured compounds. Gelatin throws down 
 reddish floculi ; peroxide of tin and acid redden it. 
 
 HEMISPHERE. One-half of a globe or sphere, formed by a plane passing 
 through its centre. 
 
 HENBANE. A poisonous narcotic plant, common in our ditches and road- 
 side. It is sometimes used in medicine. See HYOSCIAMA. 
 
 HENNA. A plant growing in Africa and many parts of the East; the 
 colouring matter being much in request for dyeing the finger nails of the inha- 
 bitants of the East, and the mains, tails, and hoofs of their horses. The 
 colouring matter of the plant is very abundant, and might be advantageously 
 used for dyeing woollens yellow and brown, of various shades, by combining it 
 with alum and sulphate of iron. The leaves are dried, powdered, and made 
 into a paste for the above-mentioned purposes. The powdered leaves form a 
 large article of export to Persia and the Turkish possessions. 
 
 HEPATIC AIR. Sulphuretted hydrogen gas. 
 
 HERMETICAL SEALING, is used to denote the perfect closing of vessels 
 so as to prevent the ingress or egress of the most subtle fluids or bodies. In 
 stopping glass vessels, for chemical operations, it is usual to heat the neck until 
 it is quite soft, and then twisting it by a pair of pincers ; sometimes a plug 
 well luted serves the purpose effectually. 
 
 HIDES. The skins of beasts ; the word being, however, distinctively applied 
 to the skins of oxen, cows, horses, and other large thick-skinned animals. Raw 
 or green hides are those which have not undergone any preparation. Seasoned 
 hides are those which have been salted with alum and saltpetre, to preserve 
 them until they undergo the process of tanning and currying. See LEATHER. 
 
 HIGH-WATER. That state of the tides when they have flowed to the 
 greatest height, in which state they remain nearly stationary for about 
 fifteen or twenty minutes, when the water begins to ebb. The time of 
 high-water is always nearly the same in the same place at the full of the moon ; 
 and at all other times the time of high-water depends upon the age of the 
 moon ; the rule for finding which, the age of the moon being given, is as fol- 
 lows : viz. Add four-fifths of the moon's age, as so many hours, to the time of 
 high-water at the full of the moon, and the sum is the time of high water 
 answering to that day, nearly. 
 
 HINGES. The joints on which doors, lids, gates, shutters, and an infinite 
 number of articles are made to swing, fold, open, or shut up. Independently 
 of a great variety of kinds and sizes kept ready made by ironmongers, there is 
 a constant demand for others of novel forms or properties to adapt them to 
 particular objects. The chief varieties are the following: cross-garnets, made 
 in the form of the letter T, for gates and out-house doors, from 6 inches to 36 
 inches long ; and a nearly similar kind made witli long straps and hooks to fix 
 in the stiles, to enable the gates or doors to be lifted off their hinges at plea- 
 sure. Those used in common for the doors of apartments are termed butts, of 
 which there ara many varieties. Those used for shutters are called back-flaps : 
 similar hinges are used for the joints of bedsteads, and very nearly the same 
 kind for Pembroke and other tables ; another sort, called H and tL hinges, from 
 their resemblance to those letters, are extensively employed for common pur- 
 poses. There are also many other sorts, distinguished by appellations that 
 designate their uses, and are too numerous to mention. All the various sorts 
 re, or may be made in the different metals, and most of them are to be found
 
 HINGES. 675 
 
 ready manufactured in \vrought-iron, cast-iron, and brass, and differently 
 finished. The chief manufactories are at Birmingham, Wolverhampton, 
 Tipton, and several parts of Staffordshire. The best of the wrought-iron kind 
 are made in Lancashire, and the heavier sort at Newcastle. We have several 
 excellent hinge manufacturers in London ; amongst whom should be particu- 
 larly noticed Messrs. Collinge and Son, and Mr. Redmund, on account of their 
 admirable improvements, which have been the subject of patent rights. Instead 
 of the ordinary plan, of a cylindrical joint working round a fixed central pin, 
 Messrs. Collinge form the end, as it were, of the pin, into a sphere, over which 
 a hollow spherical cap fixed to the other limb of the hinge is made to fit accu- 
 rately ; this is provided with a cavity for the reception of oil, having a small 
 perforation to conduct it between the two spherical surfaces, which work with 
 great truth and freedom. The principle of the invention is unquestionably 
 good, and by paying great attention to the manufacture of the article, the 
 inventors have succeeded in obtaining for them a high reputation ; they are, in 
 consequence, extensively adopted, especially in turnpike-gates, where their 
 neatness, efficiency, and durability, have established them almost as an indis- 
 pensable appendage. 
 
 Mr. Redmund, of the City Road, has likewise, with great skill and assiduity, 
 bent his attention to the improvement of hinges, in giving them new features 
 and properties, and in finishing them in a style of unusual excellence. We 
 have been informed by an architect of great eminence, that Mr. Redmund pos- 
 sesses a rare degree of ingenuity in adapting hinges to apparently impracticable 
 situations, in giving them an oniamental or a symmetrical appearance where they 
 would in general be deemed a disfigurement, and in rendering them invisible 
 when the style of architecture does not admit of any variations or additions ; 
 and that it was on this account that he was employed in rehanging the doors in 
 Windsor Castle, in the recent splendid improvements made in that palace by 
 the late king. This excellent mechanic was educated a carpenter, and being 
 now an engineer and iron founder of some repute, he unites, as it were, within 
 himself, all the resources of his art. Our assigned limits will not permit us to 
 give a detailed description of the variously formed hinges made by this manu- 
 facturer, but we will just notice one of them, which is upon the door of the room 
 where we are writing. Those hinges termed rising-butts, whose rubbing sur- 
 faces move in a spiral, or rather a helical line upwards on opening the door, 
 causes the latter to descend below the level of the carpet, are probably familiar to 
 enabling it to pass above the carpet on the floor, and which, on shutting the door, 
 most persons ; in that case it will not have escaped their notice that doors so 
 hung possess this inconvenience, that they will not stand open of themselves, 
 but are disposed to shut-to, nearly. To obviate these disadvantages, Mr. Redmund 
 cuts from the helical curves two small horizontal planes, so that they come opposite 
 to each other when the door is opened so far as to be at right angles to the stile, 
 that is, having made a quadrant of its circle, at which place the door is conse- 
 quently at rest, and to shut it when in this position requires a slight pull, which 
 causes the horizontal plane to slide off its support, and the door then returns by 
 its descent on the helix. Persons seldom open a door more than 50 or 60 on 
 entering or leaving a room ; consequently, doors hung with these hinges, always 
 shut when left to their own action, and stand open only when they are turned 
 to the full quadrant. In some cases Mr. Redmund assists the door to shut-to 
 closely when opened only a very little way, by the introduction of a very small 
 spring. A variety of these patent hinges may be seen at the manufacturer's 
 warehouse in Frith-street, Soho, London. 
 
 Having noticed, a few years ago, the inconvenience (attended with per- 
 sonal danger in some situations) of outside shutters to windows, we contrived 
 a simple addition to the common outside shutter hinges, which completely 
 obviated it Outside shutters when open, are generally fastened back to the 
 wall by means of those common appendages driven into the wall called turn- 
 backles, which often become loose, broken, or lost ; the consequences of which, 
 in windy weather, are, not unfrequently broken windows and broken shutters, 
 besides other inconveniences, which need not be specified. Fig. 1 represents
 
 676 
 
 HINGES. 
 
 the ordinary hinge shut: and Fig. 2 shows it open. A square hole is cut out 
 at A. and into it is strongly rivetted a semicircular piece of iron A B, a portion 
 of it being split in the manner shown, to form it into a spring, and the extremity 
 
 being turned upwards to form a stop, as shown at C. Upon opening the hinge 
 the flap B passes over the arc, pressing on the spring, and when arrived at the 
 stop C, it has passed the spring, and is completely open with the shutter fas- 
 tened flat against the wall. When it is required to close the shutter, the spring 
 (which is close to the window) is to be pressed down to allow the flap B to come 
 back over it ; and when shut it presents the appearance shown in Fig. 1. These 
 hinges are manufactured at only sixpence per pair more than the common sort 
 (the arc being fixed to only the lower one of a pair), and as the troublesome 
 turnbuckle is thereby superseded, the improvement cannot be considered as 
 enhancing the expense. 
 
 By the ordinary method of 
 hanging doors to libraries, the 
 hanging-stiles are fixed to the ver- 
 tical partitions of the shelves, and 
 being necessarily of a greater 
 width than the latter, the books 
 behind them cannot be got out 
 without displacing those adjoin- 
 ing. To remedy this inconve- 
 nience, the following exceedingly 
 simple and effectual contrivance 
 has been lately adopted by Mr. 
 Nettlefold, of Holborn. a is a 
 brass plate, which is screwed to 
 an upright partition ; b b are two 
 projecting parts (cast in one piece 
 with a) with the extremities 
 rounded off, and perforated to 
 receive the centre pin, which 
 passes alike through them and 
 the joint of the common butt- 
 hinge c. To the flaps of the latter 
 are screwed the doors d and e, 
 portions of which are only brought 
 into view to save room. It will 
 be observed that the door e lays 
 back quite level with the (sup- 
 posed) shelves, and that the door
 
 HINGES. 677 
 
 d folds close against e, so as to lie parallel with it, and quite out of tlie 
 way. This being the case, as represented in the figure, it is equally obvious 
 that when the door d is turned back the contrary way, both doors are thereby 
 shut, and lie quite flush and close ; and that the door e may then in like manner 
 be folded over d. The greatest facilities are thus afforded by a single hinge 
 instead of two hinges, and without the necessity of any additional hanging 
 stile. 
 
 Whitcchurch's patent hinge, for enabling doors and windows to be opened 
 either on the right or left hand, from its utility and convenience, besides the 
 ingenuity of the contrivance, deserves particular notice. It is equally applicable 
 to window- sashes, book-cases, and the show-cases of shops ; but its advantages 
 will be most conspicuous in packets, steam-boats, and those situations in par- 
 ticular where the utmost convenience in a small compass is the object of study. 
 The engraving on the following page represents the application of the invention 
 to the sash windows of houses ; and its chief utility in these consists in the 
 facility afforded in cleaning that part of the window in perfect safety which has 
 heretofore been done at considerable personal peril, and in very many instances 
 has caused fatal accidents. Its application to a door is, in principle, the same 
 as to a sash thus made (which opens on either side like a door) ; and our descrip- 
 tion of the hinges and fastenings therefore will, in a great measure, apply to 
 both, a represents the lower sash, suspended over pulleys by lines and weights 
 in the usual manner. To open the upper sash b, a false or movable sill is taken 
 out from the lower part of the sash-frame, which enables the sash a to descend 
 lower in the frame, and the upper sash, which was previously behind it (or 
 deeper in the frame) to pass over it, and to swing on its hinges on either side. 
 At c c c is a pair of long double acting hinges, shown connected on one side of 
 the window, and separated on the side where the window is open. A pair of 
 these hinges is shown shut up and complete by the distinct figure d. At e e e 
 is shown a pair of small auxiliary hinges ; and a single hinge of the kind at the 
 separate figure/ shows their precise construction. A brass bolt g is fixed on the 
 lower stile of the sash, and extending its whole length ; about two inches from 
 the end of the bolt it is jointed, so that when either end is shot into its mortice, 
 it acts as a kind of support, and as a centre for the lower part of the sash to turn 
 upon, h h exhibit two small latches for securing or opening the sash on either 
 side. Now when the window is opened on that side which is at present closed, 
 exactly the same appearances will be presented, only on the opposite side. It 
 is therefore clear that the hinges must alternately separate and connect them- 
 selves at the joints. The manner in which this is done will be partly under- 
 stood by reference to the separate figure /, where each flap of the small 
 secondary hinges is shown apart, as also their connecting themselves by the 
 jointed parts of one flap hooking into another. The long hinges used in the 
 upper part are, however, of a more complex nature, and it is very difficult 
 to give an intelligible description of them without the aid of several more 
 figures, giving different views of their parts, which would occupy too much 
 of our space. Any person, however, who may be desirous of investigating 
 their principles and mode of action, will, we doubt not, have every facility 
 afforded them at the office of the patentees. In applying the invention 
 to a room-door, the arrangement is somewhat different ; the long hinges are 
 placed at top as in the case of the window-sash, and the small auxiliary hinges 
 are fixed near to the bottom. On the middle stile of the door, the bolt, or 
 locking bar, is situated, which is either Jet in flush with the door, or lies in a 
 mortice passing from one side to the other, and is consequently entirely out of 
 sight. A mortice lock is placed on each side of the door, for opening and shut- 
 ting it by means of the knobs, and the bolt springs to and fastens the door 
 itself, when shut in the ordinary way ; and when it is required to open the door 
 the contrary way to that which it was the last time, an extra half-turn of the 
 knob throws back the bolt, and leeks the opposite side ; it is thus opened on 
 either side instantaneously, and is hung on the opposite side at the same 
 moment with never-failing security. The door is, in fact, more securely hung, 
 is better supported, and, consequently, turns on its hinges with greater ease and 
 4 a
 
 C78 HOB. 
 
 smoothness. It cannot be taken off its hinges without the aid of a turn-screw, 
 as in other doots. 
 
 HIP ROOF. A roof, the ends of which rise immediately from the wail- 
 plate, with the same inclination to the horizon as its other two sides. The 
 backing of a hip is the angle made on its upper edge to range with the two 
 sides or planes of the roofs between which it is placed. 
 
 HIVE. A receptacle for bees. See BEE-HIVE and HONEY. 
 
 HOD. A portable receptacle in which bricks, mortar, &c. are carried by 
 labourers in house-building. 
 
 HOE. An instrument employed in agriculture in breaking-up earth, and 
 drawing it around plants. It consists of a broad blade of iron or steel, with an 
 eye or socket in the middle of its upper side, through which a handle is put. 
 Garden and field-hoes are generally about three inches deep in the blade, and 
 from one inch to ten inches in length ; but there is a much larger kind, made o,
 
 HOLLOW WALL. 
 
 079 
 
 Various forms, equal in dimensions to ordinary spades and shovels, which are 
 manufactured in this country for colonial use, chiefly for the cultivation of the 
 sugar-cane. The demand for these articles, not only for the British settlements 
 but for most other parts of the world, is so extensive as to constitute a con- 
 siderable manufacture at Bristol, Birmingham, Sheffield, Newcastle, and other 
 places. 
 
 HOGSHEAD. A measure of capacity, or a cask of a certain determinate 
 size, for holding liquids. The wine hogshead is three-fourths of a puncheon, 
 one-half of a pipe, and one-fourth of a tun ; it contains a tierce and a half, or 
 63 gallons, or 252 quarts, or 504 pints, or 14,553 cubic inches. The beer and 
 ale hogshead is half a butt, and contains a barrel and a half, or 3 kilderkins, or 
 6 firkins, or 54 gallons, or 216 quarts, or 432 pints, or 15,288 cubic inches; 
 consequently, the wine hogshead is to the beer or ale hogshead as 539 to 564. 
 There are also hogsheads for sugar, flour, peas, and other dry goods ; but of 
 these the capacities are not fixed. 
 
 HOLD. The whole interior cavity of a ship comprehended between the 
 floor and the lower deck throughout her entire length. 
 
 HOLDFAST, Carpenters', is the name of a very useful tool, employed not 
 only by carpenters, but by other mechanics, for holding fast their work upon 
 the bench whilst being operated upon. It usually consists of a round bar of 
 iron, thickening a little upwards, and bent at the upper end, almost into a right 
 angle, and flattened. An oblique hole is bored in the bench ; and if a piece of 
 wood, or any other article, is wanted to be secured, it is placed under the hold- 
 fast, and a few strokes of the hammer are sufficient to make it bite firmly. In 
 order to loosen it, nothing more is necessary than a blow of the hammer 
 applied at the lower end of the bar. 
 
 Mr. W. Dungey, of Compton- 
 street, Soho, has succeeded in 
 improving this instrument, for 
 which he received a reward 
 from the Society for the Encou- 
 ragement of the Arts, &c. It 
 is represented in the subjoined 
 cut. The jaw a, instead of being 
 one piece with the rest of the 
 bar, is movable on the screwed 
 axis I, and is prolonged back- 
 wards. In this latter part is a 
 hole for the reception of a 
 cranked screw, which bears 
 on a projection d of the main 
 bar ; e is the hole in the bench, 
 and /is a flat square piece fixed 
 by a loose joint to the jaw a, and therefore capable of bearing by its whole 
 surface on any piece of work placed under it. By turning the screw c in one 
 direction the work is held fast ; and by turning in the other direction it is 
 released. It is considered as likely to be of service to coachmakers, carvers, 
 and chair and cabinet manufacturers, as the pressure of it is under perfect 
 regulation, and it is not liable to bruise the work which it is employed to 
 
 HOLDFASTS. A general term applied to a variety of flat-sided iron spikes, 
 that are driven into the joints of brick-work, against which it is desired to 
 fasten any kind of wood-work ; for this purpose, the other ends of the holdfasts 
 are spread out so as to lie flat against the wood, whereto these are nailed or 
 screwed through holes made in the iron. The term holdfast is likewise applied 
 to those iron ties in the form of the letter S, which are commonly fixed to walls 
 to keep the mass from separating. 
 
 HOLLAND. A closely woven kind of linen cloth, of a peculiar fabric, so 
 called from its having been originally imported from Holland. 
 
 HOLLOW WALL. A wall built in two thicknesses, leaving a cavity
 
 CSO HONEY. 
 
 between, which maybe either for saving materials, or for preserving an uniform 
 temperature in apartments. 
 
 HOLOMETER. A mathematical instrument that serves universally for taking 
 all measures, both on the earth and in the heavens. 
 
 HOMBERG'S PHOSPHORUS. Ignited muriate of lime. 
 
 HONE. A fine grained kind of stone, used for sharpening razors, pen- 
 knives, and other cutting instruments. The exquisite edge given by cutlers to 
 razors, lancets, &c. can rarely be produced ; by those persons who are not in the 
 habit of using them. This arises partly from ignorance of the properties in 
 which consists the difference between a good and a had hone, and partly from 
 a want of that skill and slight of hand in the use of a hone, which long and 
 constant practice only can give in perfection. Mr. P'ayrer, of Pentonville, has, 
 however, constructed a novel kind of hone, by the use of which the unskilled 
 and inexperienced operator may, without difficulty, produce a good edge. This 
 
 hone consists of a plate of brass a about an inch wide, and of any convenient 
 {ength, ground to a perfectly smooth surface on hoth sides, one of which is 
 marked R and the other S ; part of each end is cut or filed away, leaving only 
 two pins or pivots, on which the hone turns or swings. In the frame c c are 
 two uprights d d, with notches to receive the pivots ; e e are two boxes, one to 
 hold a coarser and the other a finer powder, made of oil-stone ground down and 
 washed over: for the latter, finely pulverized water-of-Ayr stone may be sub- 
 stituted. To use this hone, first place the side marked R uppermost, and put 
 on it a few drops of oil and a little of the coarser powder, then draw along it 
 in the usual manner the edge of the instrument to be sharpened. As the hone 
 swings on two pivots, the surface necessarily applies itself quite evenly along 
 the edge of the blade, in whatever direction the pressure of the hand is made 
 that holds the tool ; and the particles of the powder, as the operation pro- 
 ceeds, are continually becoming smaller and smaller, and therefore giving 
 a finer and finer edge. To finish the setting, turn uppermost the surface 
 of the hone marked S, apply to it oil and the finer powder, and proceed as 
 before. 
 
 HONEY. A sweet and scarcely fluid substance, which is collected by 
 bees from the nectaria of flowers, and deposited in the cells of the combs for 
 the support of the bees and their offspring. Naturalists are not agreed whether 
 honey undergoes a particular elaboration in the bodies of bees, thence deriving 
 its flavour and consistence, or whether it is merely collected and deposited by 
 them in its pristine state. M. Cavezzali has proved that honey is composed 
 of sugar, mucilage, and an acid. The sugar may be separated by melting 
 the honey, adding carbonate of lime, in powder, as long as any effervescence 
 appears, and scumming the solution while hot. The liquid, thus treated, 
 gradually deposits crystals of sugar. There are three distinctions of honey, 
 according to its purity and the manner it has been obtained from the honey- 
 combs. The first and finest kind is virgin honey, or the first produce of a 
 swarm, obtained from the combs without pressing, these being only set to drain, 
 in order to its running out. The second kind is that known by the name of 
 white honey, being thicker than the former, and often, indeed, almost solid ; it 
 is procured by pressing the combs, but without the assistance of heat. The 
 third and worst kind is the common yellow honey, obtained from the combs 
 first heated over the fire, and then pressed. Honey was a domestic manufac- 
 ture of great importance before the introduction of cane sugar; and in those 
 countries where cane sugar is still scarce, the preparation of honey is verv
 
 HOPS. CS1 
 
 extensively conducted. It is not uncommon for a peasant of the Ukraine to 
 have 4 or 500 hives ; and for a parisli priest in Spain to have as many as 5000 
 hives. In the Hanoverisches Magazin, it is stated that the Jews in Moldavia 
 have a method of making honey into a hard and white sugar, which is 
 employed by the distillers of Dantzic, to make their liqueurs. The process 
 "consists in exposing the honey to the frost during three weeks, sheltered 
 from the sun and snow in a vase of some material which is a bad conductor 
 of heat. The honey does not freeze, but becomes transparent, and hard as 
 sugar. 
 
 HONEY-COMB. The cellular fabric made by bees in wax, in which they 
 deposit their honey. Hence, in the casting of iron or other metals, when the 
 work is not solid, but cellular or spongy, it is denominated honey-comb, 
 
 HOOD. A cowl or covering, placed on the top of any thing. 
 
 HOOD and MOUTH PIECE, invented by Roberts, the miner, for descend- 
 ing mines, or going into houses on fire, is described under FIRE ESCAPES. 
 
 HOOFS. The horny substance that covers the feet of various animals ; it 
 chiefly consists of coagulated albumen. See HORN. 
 
 HOOP. A pliant piece of wood or metal made into rings, or circular ban- 
 dages for casks, &c. 
 
 HOPPER. A trough or funnel employed to supply corn to a mill, fuel to 
 close furnaces, and to a great variety of other purposes. 
 
 HOPS. The dried flower buds of a British climbing plant, which grows 
 wild in many parts of England; but for the purposes of commerce and brewing, 
 they are usually cultivated in extensive plantations, where they require the 
 growth of some years before they attain perfection. To cultivate it with suc- 
 cess requires extreme care, considerable experience, and a large capital ; yet 
 perhaps of no plant is the harvest so precarious, from an unfavourable season, 
 and the depredations of insects. There are several varieties of it, as the red 
 bind, the green bind, and the white bind. It is propagated by nursery plants, 
 or by cuttings. These are planted in little hillocks, formed by digging a hole 
 12 inches deep and 18 inches in diameter, and filling it up with fine mould, mixed 
 with manure, and the original soil. In the centre of the hill is set a single 
 plant, and round it half a dozen others. The hills are about 9 feet asunder. 
 Cuttings are set in February and March, but sets, or nursery plants, in autumn. 
 In April, if the season be favourable, the binds require tying to poles, which 
 are stuck in the earth. About Midsummer they are pruned, and the produce 
 given to cattle. In September they are usually ready for pulling. Chestnut 
 is reckoned to make the best poles, and ash the next the poles are from 18 to 
 24 feet in length; three poles are sufficient for a single hill, or two poles where 
 the plants are vigorous. The large poles are not required till the first winter 
 after the plantation has been formed, and it is advisable not to take any produce 
 the first year. The picking is performed by men, women, and children. 
 Proper baskets and bins or cribs being in readiness, the plants are cut off" close 
 to the ground, and the poles drawn up ; these are placed upon the bins, with 
 the plants upon them, and three or four persons on each side pick off the hops. 
 After this, they are dried in a kiln ; and when dry they are carried into, and 
 kept for five or six days in a room called the stowage room, until the)' are in 
 a state to be put into bags. This is done through a round hole or trap, cut in 
 the floor of the stowage room, exactly equal to the dimensions of the mouth of 
 the bag, and immediately under which, to a frame of wood, this mouth is fastened. 
 In each of the lower corners of the bag a small handful of hops is tied ; and a 
 person called the packer places himself in it, and by a heavy leaden weight, 
 which he constantly moves round in the places where he is not treading, presses 
 and forces the hops down in a very close manner into the bag, so fast as they 
 are thrown to him by another labourer. The work thus proceeds until the bag 
 is quite full, when each of the upper corners has a few hops tied in it in the 
 same manner. 
 
 The usual way of extracting hop poles, by pushing them backwards and for- 
 wards till they are sufficiently loosened to be raised up out of the grjuiid by 
 hand, subjects the hops to injury, by shaking and bruising them, while :he poles
 
 682 
 
 HORN. 
 
 themselves are frequently broken. These inconveniences are avoided, and a 
 considerable time is saved, by the application of an apparatus invented by Mr. 
 John Knowles, of Farnham, who took out a patent for it in 1830. The nature 
 of the contrivance, and the intention of the inventor, are well expressed on the 
 title of the patent, which is for " a certain instrument or machine for drawing 
 up hop poles out of the ground previous to picking the hops, and which, by 
 drawing the poles perpendicularly, will greatly save them, as well as prevent 
 the hops from being bruised, called a hop-pole-drawer, by lever and fulcrum." 
 In the annexed engraving, Fig. 1, is shown a portion of a hop pole, and the appli- 
 cation of the lever and fulcrum in raising it out of the ground ; a a is the pole 
 
 b the lever, and c is its fulcrum, which has a broad base, with a short spike 
 to prevent its slipping when the pressure is applied to it. Fig. 2 shows a plan 
 of the lever with its iron jaws, which are made to approach each other, that 
 some part of the opening may fit all sizes of poles ; and they are serrated to 
 
 prevent their slipping upon the poles. 
 HORN. An animal substa 
 
 substance, composed of coagulated albumen, with a 
 little gelatine, and about a two-hundredth part of the phosphate of lime. But 
 the horns of the buck and hart are of a different nature, being intermediate 
 between bone and horn. The horns of oxen are prepared for lanthorn leaves 
 in the following manner. They are first softened by roasting over a fire made 
 of the stalks of furze, and then slit lengthwise, on one side, and kept expanded 
 flat between a pair of tongs, and afterwards placed in a press between iron 
 plates that are greased. Here the horns remain till they are cooled ; they are 
 next soaked in water till soft enough to be pared down to the required thinness, 
 with a large knife worked horizontally on a block. Their transparency is 
 thus acquired ; and after being immersed in ley, they are polished with 
 whitening, and the coal of burnt willow. Horn for making into snuff boxes, 
 combs, and other ornamental articles are stained to imitate TORTOISE SHELL, 
 which see. 
 
 HORN. A musical instrument of the wind kind : the earliest, from which 
 the instrument derived its name, were the horns of animals, and these are still 
 used extensively in remote or uncivilized districts. Considered as a modern 
 musical instrument, they are chiefly made of metals, and of various kinds or forms. 
 The French horn is a long tube, narrow at the top, and increasing in diameter 
 to the end, where its mouth is very wide. It is curled up in several rings, for 
 the convenience of carriage and performance. The trumpet and the bugle 
 horn are noticed under their respective heads.
 
 HOROLOGY. 683 
 
 HORN, ARTIFICIAL, or TANNED GELATINE. Considerable manufactories 
 have, it is said, been established in France, for the construction of a variety of 
 articles with this substance. The gelatine is usually obtained from bones, by 
 treating them with a weak solution of muriatic acid ; and it is afterwards tanned 
 by the common process, as in making leather. Upon becoming bard and 
 dry, it assumes the appearance of horn or tortoise shell, and is employed 
 for the same purposes as those substances. It is softened by being boiled 
 in water with potash, when it may be formed into any shape, and the figure 
 preserved by drying the articles between moulds. In the soft state, it may 
 also be inlaid with gold, silver, or other metals, and is streaked with various 
 coloured materials, so as to resemble the finest woods and other natural pro- 
 ductions. 
 
 HORNBLENDE. A species of the clay genus, of which there are three 
 varieties ; viz. the common, hornblende slate, and basaltic hornblende. 
 
 HORN-ORE. One of the species of silver ore. 
 
 HORNSTONE. A sub-species of rhomboidal quartz, according to 
 Jameson, who divides it into splintery hornstone, conchoidal hornstone. and 
 woodstone. 
 
 HOROGRAPHf. The art of DIALLING, which see. 
 
 HOROLOGY. The art of constructing machines for measuring time ; but 
 from the circumstance of clocks and watches having very generally superseded 
 all other contrivances for this purpose, the term is now usually understood as 
 referring to these latter instruments solely. In these machines a pendulum, or 
 a spiral spring, connected to a flat wheel turning freely on its axis, (called a 
 balance wheel,) is made to vibrate; and it being a property of these bodies, 
 that all the vibrations, whether through large or small arcs, (within certain 
 limits,) are made in equal times, all that is necessary to measure time by this 
 means, is to register the vibrations, and to prevent the vibrating body from 
 being brought to rest by the resistance of the atmosphere, or the friction of its 
 parts, about the centre of oscillation ; and these objects are effected by means of 
 a train of wheels put in motion by the descent of a weight, or by the action of 
 a coiled spring, the velocity of the wheels being regulated by the vibrations of 
 the vibrating body. The essential difference between clocks and watches con- 
 sists in the nature of the regulator employed ; which in clocks is the pendulum, 
 and in watches the balance wheel. The pendulum requires to be suspended from 
 steady points of support, that its vibrations may be constantly performed in a 
 vertical plane, hence clocks cannot be made portable ; but from the pendulum 
 being acted upon by the force of gravity, which is a constant force, its motion is 
 more equal than that of the balance spring, the force of which varies greatly, 
 from changes of temperature, and other causes ; clocks are therefore always 
 preferred in observatories ; but as the balance will perform lying in any position, 
 watches have the advantage of being portable. 
 
 We shall now proceed to describe the construction of an ordinary eight-day 
 clock, which we nope will be rendered sufficiently clear with the help of the 
 accompanying engraving, which exhibits a front view of the works, the dial 
 plate being removed to show the manner in which the hour and minute hand 
 are made to revolve with different velocities upon the same centre. A portion 
 of the front frame plate is likewise represented as broken away to exhibit more 
 clearly the escapement ; the striking parts, and the wheels and pinions com- 
 posing the train, being hidden by the frame plate, are represented simply by 
 dotted circles, and instead of letters of reference, they are indicated by figures, 
 which express the number of teeth contained in them. The striking parts, as 
 usually constructed, are so very complex as to render it extremely difficult to 
 convey a clear idea of their operation without a very lengthened description, and 
 several diagrams ; we have therefore preferred introducing in their stead an 
 extremely simple and ingenious arrangement for the purpose, invented by Mr. 
 Prior, of Nessfield, in Yorkshire, and for which he received a reward from the 
 Society of Arts. A clock of this kind contains two independent trains of 
 vrheelwork, each with its separate first mover ; one is constantly going to indi- 
 cate the time by the hands on the dial plate ; the other is put in motion every
 
 684 
 
 HOROLOG\ 
 
 hour, ai.d strikes a bell to tell the hour at a distance ; the dotted circle a is the 
 barrel of the going part ; it has a catgut b wound round it, suspending the 
 weight c which keeps the clock going ; 96 is a wheel (called the first or great 
 wheel,) of that number of teeth, upon the end of the barrel, turning a pinion 
 
 of eight leaves, on an arbor which carries the minute hand. 64 is a wheel of 
 64 teeth, on the same arbor, (called the centre wheel,) turning the wheel 60, by 
 a pinion of eight leaves on its arbor : this last wheel gives motion to the pinion 
 of eight, on the arbor of the swing wheel 30, of 30 teeth ; d h are the pallets of 
 the escapement, fixed on an arbor e, going through the back plate of the clock's 
 frame, and carrying a long lever, which has a small pin projecting from its
 
 HOROLOGY. 685 
 
 lower end, going into an oblong hole, made in the rod /of the pendulum. The 
 pendulum consists of an inflexible metallic rod, suspended by a very slender 
 piece of steel spring, from a brass bar, screwed to the frame of the clock, having 
 a weight or bob at its lower end, in the present case 39.125 inches from the 
 point of vertical suspension ; when this pendulum is moved from the line in 
 either direction, and suffered to fall back again, it swings nearly as much beyond 
 the vertical on the contrary side, and then returns ; this it will continue to do 
 for some time, and each of these vibrations will be performed in one second of 
 time, when the pendulum is of the above length. This is the measurer of the 
 time ; and the office of the clock is only to indicate the number of vibrations it has 
 made, and give it a small impulse each time to keep it going, as the resistance of 
 the air, and elasticity of the spring, would otherwise in a few hours cause it to 
 stop. By the action of the weight applied to the cord b, (which is called the 
 maintaining power,) the wheels are all turned round; and if the pallets dh were 
 removed, the swing wheel 30 would revolve with great velocity in the direction 
 from 30 to d, until the weight reached the ground ; the teeth of these pallets 
 are so made that one of them always engages the wheel, and prevents its turn- 
 ing more than half a tooth at a time. In the drawing, the pallet d has the 
 nearest tooth of the wheel resting on it, and the pendulum is on the side h of 
 the perpendicular ; when it returns it moves the pallet d so as to allow the 
 tooth of the wheel to slip off; but in the mean time the pallet h has interposed 
 its point in the way of the tooth next it, and stops the wheel till the next vibra- 
 tion or second ; the distance between the two pallets d h is so adjusted that only 
 half a tooth of the wheel escapes at each vibration ; and as the wheel has 30 
 teeth, it will revolve once in 60 vibrations of one second each, or one minute; 
 consequently a hand on the arbor of this wheel will indicate seconds on a circle 
 on the dial plate divided into 60 ; the pinion of eight on its arbor is turned by a 
 wheel of 60, which consequently will turn once in seven turns and a half of the 
 other, or in seven minutes, 30 seconds, or one-eighth of an hour ; its pinion of 
 eight is moved by a wheel of 64, or eight times itself, which will tuni in one- 
 eighth part of the time, this will be an hour ; the arbor of this wheel, therefore, 
 carries the minute hand of the clock. The great wheel of 96 being twelve times 
 the number of the pinion eight, will turn once in 12 hours, and the barrel a 
 with it. The catgut goes round 16 times, so that the clock will go eight days. 
 The hour-hand of the clock is turned by the wheel work shown upon the front 
 frameplate ; on the end of the arbor of the centre wheel 64 a tube is fitted, so 
 as to go round with it by friction ; this carries the minute hand, but if the clock 
 should require correction, the hand may be slipped round without moving the 
 wheels : this tube has a pinion of 40 teeth on its lower end, indicated by a 
 dotted circle ; this turns another wheel 40, of 40 teeth, which has a pinion of 6 
 teeth on its arbor, turning a wheel 72, of 72 teeth ; the two wheels 40 will both 
 turn in an hour, and 72 in 12 hours; the arbor of this wheel has the hour- 
 hand, and is a tube going over the minute-hand, so that the two hands are con- 
 centric. The barrel a is fitted to an arbor coming through the plate of the 
 clock, and is filed square to put on a key to wind up the weight ; the great 
 wheel 96 is not fixed fast to the arbor, but has a click on it, which takes the 
 teeth of a ratchet wheel cut upon the barrel ; so that the barrel may be turned 
 in the direction to wind up the weight without the wheel ; but by the descent 
 of the weight, the wheels will be turned by the click. 
 
 In commencing our description of the striking parts, we should observe, that 
 
 might be contrived for effecting this : the dotted circle k has a weight m sus- 
 pended from it by a catgut passing round it like that which passes round the 
 going barrel a ; n is a scape-wheel of 78 teeth, connected with the barrel by a 
 ratchet and click, and having 12 pins projecting from its face, a portion of 
 which are seen, marked 2, 3, 4, 5, 6, 7, 8 ; these pins are ranged in a circle at 
 unequal distances, corresponding to the number of strokes to be struck at each 
 4 s
 
 6fc6 HOROLOGY. 
 
 successive hour; o is the scapement similar to that previously described; on 
 its arbor is fixed a pendulum p, of about nine inches in length, and which will 
 therefore vibrate half seconds nearly; but in order to regulate the rate of 
 vibration at pleasure, the rod of the pendulum is prolonged beyond the point of 
 suspension, and carries a small ball q moving stiffly upon it, and by raising or 
 lowering this ball the vibrations become retarded or accelerated. To the lower 
 end of the pendulum rod is attached a hammer r, which strikes upon a bell * at 
 every second vibration ; this effect is obtained by placing the bell sufficiently 
 oblique to allow the hammer to swing past it at one vibration, and to impinge 
 upon it at the returning one. The barrel k and escape-wheel n are retained at 
 rest by the locking detent /, which engages each of the pins in succession on 
 the face of the escape-wheel ; this detent is fixed on to the arbor of the arm or 
 lever v, which is pressed by the spring w against a snail or cam a fixed upon the 
 hollow arbor which carries the minute-hand. The snail is consequently carried 
 round once in an hour, d-iring which time the lever v is gradually elevated, and 
 moves the detent in like manner until the lever arrives at the highest part ot 
 the snail, when the pin on the escape-wheel is released from the detent, and the 
 wheel immediately begins to revolve and imparts motion to the pendulum, which, 
 as before said, strikes upon the bell at each second vibration. The rotation of the 
 snail having carried its highest point past the end of the lever, the latter 
 (pressed by the spring w) falls past the straight side of the snail to the foot of 
 the same, and brings the detent into its locking position ; and when, by the 
 revolution of the escape-wheel, the next pin comes in contact with the detent, 
 the motion of the wheel is arrested. Clocks are sometimes impelled by springs 
 instead of weights, as in the one just described, and are very convenient for 
 placing in chambers on account of their occupying less room than weight- 
 moved clocks. The construction of these spring clocks resembles that of the 
 other, with the exception that for the oarrel and weight are substituted a fusee 
 and spring barrel, resembling the same pieces in a pocket-watch, to the descrip- 
 tion of which we shall now proceed. 
 
 The essential difference, as we have before observed, between a clock and a 
 watch, consists in the former being regulated by a pendulum, and the latter by 
 a balance ; for as to the maintaining power, it is sometimes the same in both, 
 since although watches are not impelled by weights, clocks (as just mentioned) 
 are sometimes kept in motion by springs like watches. The balance is a small 
 wheel fixed on an arbor or axis called the verge, and moving freely upon pivots 
 at the ends of the arbor. To the axis of the balance the inner end of a very 
 elastic helical spring called the pendulum is attached, and the outer end is made 
 fast to some fixture. In this state the balance will remain at rest when the 
 spring is in that position which it would assume if detached from the balance, 
 and at perfect liberty ; but if the balance be turned on its pivots in either 
 direction, so as either to wind up or unwind the spring, the latter will, upon 
 the external force being removed, tend to resume its natural position ; but the 
 momentum which is thus imparted to the balance will carry it past the position 
 of rest, which will again alter the spring, and the balance will again be returned 
 past the position of rest, and will thus continue to vibrate until the friction of 
 the pivots and the resistance of the air destroy the original impulse. The 
 vibrations of such a balance, which passes through equal spaces, will be per- 
 formed in equal times; these vibrations, therefore, form the real measure of 
 time, and the remaining apparatus in a watch is for the purpose of registering 
 the vibrations, and of maintaining the motion of the balance ; and this is 
 accomplished in watches by means of a train impelled by a spring and fusee. 
 The spring employed for this purpose consists of a long flat plate of steel, coiled 
 up in a helical form ; it is inclosed in a cylindrical box called the spring barrel, 
 to which its external extremity is attached, whilst its internal end is connected 
 to a fixed axis, round which the barrel revolves. As the strength of the spring 
 is greater the more it is coiled up fay turning the box, its action would be 
 unequal in impelling the work of th clock ; and to remedy this inconvenience, 
 . the fusee has been contrived. The tusee consists ot a conical barrel, round
 
 HOROLOGY. 
 
 687 
 
 which a spiral groove is cut, which receives a chain previously wound round 
 the barrel, by which, as it is turned round, it coils up the spring ; the groove 
 receives the chain first near the base of the cone, and as the barrel revolves, 
 gradually brings it nearer the axis ; by this means the stronger the spring is 
 coiled up, the shorter is the lever by which it acts upon the work; and as it 
 gradually uncoils and becomes weaker, on the contrary the lever of action 
 becomes longer. 
 
 Having thus explained the nature and operation of the regulator, and of the 
 maintaining power, we shall endeavour to describe the construction of an ordi- 
 nary watch, with the assistance of the annexed engravings. Fig. 1 represents 
 
 1. 
 
 the works, the upper plate being removed ; Fig. 2 is the upper plate, with the 
 cock removed to show the balance ; and Fig. 3 a general elevation, supposed to be 
 set out upon a straight line, in order to show the whole at one view. The same 
 letters of reference are used to denote the same parts in all the figures, a is 
 the spring barrel ; b the chain attached by one end to the barrel, and after 
 being wound several times round the barrel, hooked by the other end to the 
 fusee c, mounted on pivots turning in holes in the two plates ee; one of these 
 pivots/ projects a considerable distance, and is cut square to receive a key, by 
 turning which the fusee is turned round so as to wind the chain upon it, which 
 causes the spring barrel to revolve also, and coils up the spring into a closer 
 spiral than it was when at liberty ; and upon the key being removed, the spring 
 reacts upon the chain, and by that means turns the fusee. To prevent over- 
 winding, a guard is added, which consists of a small lever g, which, when the 
 fusee has received a certain number of turns of the chain, presses against a 
 stop h on the top of the fusee, k is the great wheel attached to the base of the 
 fusee by a ratchet and click, by which means the fusee can be wound up with- 
 out turning the great wheel ; this latter has 48 teeth, and turns a pinion of 12 
 teeth on an arbor in the centre of the watch, which carries the minute-hand 
 upon this arbor is fixed the centre wheel m, of 54 teeth, working in a pinion 
 fixed upon the arbor of the third wheel n, of 48 teeth, which turns the 
 pinion of the contrate wheel o, of 48 teeth ; tne contrate wheel gives motion
 
 688 HOROLOGY. 
 
 to a pinion of 6 teeth, which is fixed upon the arbor of the crown or balance- 
 wheel p, which has 15 large teeth, that stop against two pallets alternately 
 upon the verge or arbor of the balance q ; these pallets are two small teeth 
 projecting from the verge at nearly right angles to each other, and constitute 
 the escapement, the object of which, as in a clock, is to prevent the train run- 
 ning down rapidly by the action of the main spring, as would be the case if 
 there were no check to it; but at each vibration of the balance, one of the 
 pallets engages a tooth of the crown, thereby retarding the motion of the train, 
 and imparting fresh impetus to the balance ; and no sooner has the pallet 
 swung clear of the tooth, but the other pallet engages another tooth on the oppo- 
 site side of the wheel. One of the pivots of the balance works in a small 
 frame r called the potence ; the lower pivot of the verge works in it also, and 
 the upper pivot turns in a cock s screwed to the plate e. The minute-hand t is 
 fixed upon the outer end of a tube which fits tight upon the arbor of the cen- 
 tral wheel, and which carries upon its inner end a pinion of 12 teeth ; this 
 pinion turns a wheel v of 48 teeth, on whose arbor is a pinion of 16 teeth 
 turning another wheel of 48 teeth, the arbor of which is a tube fitting upon 
 the other tube on the central arbor, and carries the hour-hand x. The tension 
 of the main spring is adjusted in the first instance by the maker, who turns it* 
 arbor, on the head of which is fixed a ratchet y, in which a click takes and 
 thereby holds it fast when wound up to the proper pitch ; subsequently, when 
 a watch is perceived to gain or lose time, it is regulated by strengthening or 
 weakening the pendulum spring 1, Fig. 2, which will cause it to move quicker 
 or slower. This adjustment of the pendulum spring is effected thus : the spring 
 is fixed to a stud 2 upon the plate e by one end, and to the verge of the balance 
 by the other ; 3 is a lever lying betwixt the spring and the plate, and turning 
 in a collar in the plate concentric with the centre of the balance, the verge of 
 which passes through a hole in the lever ; upon the lever is fixed a small stud 
 I with a notch in it to receive the spring ; the acting' part of the spring is from 
 4 to the centre, therefore by turning the lever in either direction, the length of 
 the spring is altered, and in order to regulate this length with precision, the arc 
 through which the end of the lever can be made to traverse on the plate, is 
 divided into a number of equal parts or degrees. In Figs, I and 3 are shown 
 four pillars, by which the two plates of a watch are held together; and in 
 Fig. 2, the heads of the same pillars are represented coming through the 
 upper plate, with small pins put through them to keep the plate down. 
 
 Chronometers are portable time-keepers, in which, by the nature of the 
 escapement, and the compensations for heat and cold, mean time is kept with 
 sufficient accuracy to determine the longitude at sea. The relation between 
 time and longitude, will be found explained under the head LONGITUDE. As 
 the principal differences between chronometers and other watches consist in 
 the escapement and the balance, we shall not detain the reader with a descrip- 
 tion of the other parts of these machines, but shall proceed to describe more 
 fully the various modes of constructing those grand essentials in all time 
 keepers, the regulator and escapement, noticing particularly those employed in 
 chronometers. 
 
 Amongst the various steps by which horological machines were brought 
 to their present state of perfection, the most important is the addition of the 
 pendulum, which furnishes at once the most simple and accurate measure of time 
 that we are yet acquainted with. Various claims have been made for the honour 
 of this grand improvement, but the person to whom mankind is really indebted 
 for bringing it into universal notice, is the celebrated Christian Huygens, of 
 Zuylichem, who, in his excellent treatise De Horologio Oscillatoreo, has described 
 the construction of a pendulum clock, and proved'that he made one before the 
 year 1658. His method of supporting the pendulum in the figure on the 
 following page, in which a contrivance is resorted to for the purpose of insuring 
 its isochronous motion, is ingenious, although it is not quite correct, as 
 has been shown by Mr. Cummings, in his Treatise on Watch-Making. It 
 consists of two cycloidal cheeks of brass, forming a curve, in which the
 
 t>89 
 
 HOROLOGY. 
 
 silk line by which the pendulum is suspended moves. When 
 the art of clock-making had attained a high degree of perfec- 
 tion, and the application of this instrument to astronomical 
 observations rendered the utmost accuracy desirable, it was soon 
 perceived that the varying length of the pendulum rod, in con- 
 sequence of its expansion by heat and contraction by cold, 
 was a source of irregularity, which it was deemed difficult to 
 overcome. To diminish as much as possible these variations, 
 we are indebted to that eminent artist, George Graham, for 
 the first application of the principle, which, under various 
 modifications, has since been applied to preserve unchanged the 
 centre of oscillation in a pendulum, and thus to insure the 
 performance of all its vibrations in the same length of time. 
 Those substances which were found to be least alterable by 
 changes of temperature, such for example as wood, and par- 
 ticularly deal (pine), were employed in the best clocks. As 
 the different metals are affected by heat in different degrees, 
 Graham conceived the idea that the greater expansion of one might be 
 employed to counteract the less expansion in another. After a series of trials, 
 during a period of five or six years, he succeeded perfectly, by attaching to the 
 pendulum rod a vessel containing mercury, which liquid, when the rod was 
 expanded by heat, rose, from the same cause, in the vessel which contained it, 
 so as to compensate for the downward expansion of the rod. This improvement 
 was completed in the year 1721. Five years afterwards John Harrison, a car- 
 penter in Barton, in Lincolnshire, subsequently so celebrated f'6r his improve- 
 ments in chronometers, invented and applied to a clock of his own manufacture 
 the pendulum, which from its form is called the gridiron pendulum. In this 
 the expansion of the iron rod is corrected by the greater expansion of rods of 
 brass or of zinc, which tend, to raise the bob in the same degree in which the 
 expansion of the main rod tends to lower it, and it of course is retained in the 
 same place : in this form the compensation pendulum is, to the present day, 
 most commonly made. The principle upon which these pendulums were con- 
 structed has received various modifications in the hands of different artists ; 
 Harrison's rods, for example, instead of being arranged in the form of a 
 gridiron, have been inclosed in a tube, and greater elegance and compactness, 
 with a more easy mode of adjustment, have been attained ; these, however, we 
 believe, comprise the whole merit of the 
 
 modern improvements. 
 
 The annexed figure represents the mode 
 
 of compensation proposed by Dr. Fearn. a 
 
 is the pendulum rod suspended by a flexible 
 
 spring, in the usual manner, from the cock 
 
 bf c is a rod or bar of zinc attached to the 
 
 back plate of the clock, by a screw at its 
 
 lower end. The head d of this bar works 
 
 upon a pin, which forms a joint, as repre- 
 sented in the drawing. Through this head 
 
 there is a mortice, which allows one end of 
 
 the lever e e to pass through it, and within 
 
 which it may be fixed firmly by means of a 
 
 tightening screw. The lever ee is attached 
 
 to the clock-plate b"y a screw, which is also 
 
 its fulcrum. Through a slit in the inner 
 
 end of this lever the suspending spring 
 
 passes, and is closely embraced by it on its 
 
 lower side. The operation of this apparatus 
 
 will readily be conceived ; as the rod a 
 
 lengthens by heat, or contracts by cold, the 
 
 rod c will be similarly affected. The expan- 
 sion of c will cause the inner end of the 
 
 9^
 
 HOROLOGY. 
 
 lever to descend, and, consequently, to embrace the suspending spring at a 
 lower point, and thus to diminish the effective length of the pendulum. The 
 mode of adjustment is obvious, as a greater or lesser motion may be given to 
 the lever, the upper end of the rod c being made to approach or recede from 
 its fulcrum. To obtain the requisite accuracy, an adjusting screw may be ma de 
 to act upon the head d. 
 
 In the year 1818 a reward was given to Mr. Reid for a compensation pen- 
 dulum, in which the bob rested in a hollow cylinder of zinc, through which th^ 
 rounded end b c of the steel pendulum rod is passed, 
 the zinc itself being supported by the nut e at the 
 end of the rod. As, therefore, the rod lengthened 
 by heat, carrying the bob downward, so the upward 
 expansion of the zinc raised the bob ; and if the rela- 
 tive lengths of the steel and zinc were so propor- 
 tioned that the amount of their expansions was 
 equal, it is evident that the compensation above 
 described would be perfect ; but it is extremely 
 difficult to effect this accurate proportioning of the 
 lengths of the two metals. The length of the zinc 
 at first must be such that its rate of expansion shall 
 be in excess, and it must be cautiously reduced by 
 repeated trials till the requisite accuracy is attained ; 
 this, however, is not done, except at a considerable 
 expense of time and attention, to avoid which Mr. 
 Reid has introduced the following modification. 
 He forms a hollow screw in the cross bar / of the 
 bob g, and an external screw on the same rake on 
 the end of the zinc cylinder d ; this latter is pur- 
 posely made too long for due compensation, but its 
 effective length may be commodiously and accu- 
 tately reduced to what is required by screwing it 
 up as represented in the figure ; but after this has 
 been done, supposing the nut e to have remained 
 stationary, it is evident that the extent of gravity of 
 the pendulum itself will have been lowered by the 
 bob descending exactly as much as the upper end 
 of the cylinder has advanced through the hole in 
 the cross-bar/; an adjustment for time is therefore 
 required after that for compensation has been 
 effected, which is done in the usual way, by screw- 
 ing up the nut e. This latter compensation, how- 
 ever, will not be required, if the rakes of the screws /and c are proportionate 
 to each other, as the weight of the bob alone is the sum of the weights of the 
 bob, the zinc cylinder, and the nut. Thus, if the former weight be assumed as 
 ten, and the latter as eleven, the screw at / must have ten 
 threads, in the same length that the screw at c has eleven 
 threads. Care must be taken in screwing the cylinder of zinc 
 up or down, to place the finger and thumb at the same time 
 on the nut, so that the two may turn together ; or the nut 
 may be fastened to the cylinder. 
 
 In connexion with this branch of the subject, we may notice 
 the inverted spring pendulum, invented by Mr. W. Hardy, of 
 Wood-street, Clerkenwell. The object of this invention is lo 
 ascertain the stability of the support of clocks, for which pur- 
 pose the weight at its upper extremity is screwed down until 
 it will perform its vibrations in the same period of time as the 
 pendulum of the clock. The inventor states that when the 
 weight a is screwed up to the top of the steel rod b, it 
 vibrates only once or twice in eight or nine seconds, which 
 renaers it remarkably susceptible, and that its sensibility is
 
 HOROLOGY. 69! 
 
 60 great that the attraction of the sun and moon, or of mountains, may be 
 observed by it : it serves also for ascertaining the stability of buildings, a is 
 the weight screwed upon a steel rod b, which is supported at bottom by a small 
 piece of steel watch-spring c, and contained in a glass tube ; d is a cap or 
 stopper to the upper end of the tube, and carrying underneath a small gra- 
 duated scale, over which ranges the index at the top of the weight. For this 
 invention Mr. Hardy received a reward from the Society of Arts. His com- 
 munication to them was accompanied by testimonials to the value of the inven- 
 tion from several eminent scientific characters, amongst whom was Captain 
 Kater, who employed the instrument to assure himself of the stability and 
 freedom from tremor of the base upon which his clock rested during his 
 experiments. 
 
 Before the application of the pendulum as a regulator in clocks, balances had 
 been employed for that purpose, but were quickly superseded after the intro- 
 duction of the pendulum ; but as external motion is destructive of the regularity 
 of the pendulum's performance, the balance was still the only regulator which 
 could be applied in portable machines, and the great improvement made in 
 that regulator by the addition of a spring has caused it to approach the pen- 
 dulum in point of correctness. The first invention attaching a spring to give 
 to the balance, by its elasticity, a power which renders the action of this sort 
 of regulator similar to that of gravity in a pendulum, is undoubtedly due to 
 Dr. Hooke, but he appears to have applied it only in a straight form. Huygens, 
 improving upon this idea, substituted a spiral spring, which is much more 
 favourable to the vibrations of the balance. 
 
 The alterations to which the length of the pendulum is exposed by variations 
 of temperature, and which affect the going of clocks, have already been noticed; 
 but watches with a balance are still more exposed to irregularity from that 
 cause, as not only the balance expands or contracts according to the rise or fall 
 of the thermometer, but the regulating spring itself suffers the same changes. 
 As the balance contracts, and its diameter becomes less, it will be more easily 
 carried round by the vibrating forces, and will then vibrate more quickly ; and 
 as the spring attached to the balance becomes contracted at the same time, it 
 will likewise act with greater force when cold, and on this account the vibra- 
 tions will be farther quickened. There are two ways of correcting these irregu- 
 larities ; the first, which was invented by Harrison, consists in lengthening or 
 shortening the spring when heat or cold may have given it more or less force ; 
 the other method is to cause the balance to expand instead of contracting by 
 cold, by which means the spring, when in the state of great rigidity, has more 
 work to do; this method originated with Peter Leroy, and has since been 
 carried to great perfection by Arnold. Harrison (whose application of the dif- 
 ferent expansion of two metals to correct the variations in the length of the 
 pendulum, has been already noticed), applied the principle in a manner not 
 before thought of, and made it act on the spiral spring so as to produce the 
 desired compensation in the regulator. His method is described as follows, 
 (Principles of Mr. Harrison's Time-keeper, p. xii Notes.) " The thermometer 
 kirb is composed of two thin plates of brass and steel, rivetted together in 
 several places, which, by the greater expansion of brass than steel by heat and 
 contraction by cold, becomes convex on the brass side in hot weather, and con- 
 vex on the steel side in cold weather ; whence, one end being fixed, the other 
 end obtains a motion corresponding with the changes of heat and cold, and the 
 two pins at the end, between which the balance spring passes, and which it 
 alternately touches as the spring bends and unbends itself, will shorten or 
 lengthen the spring, as the change of heat or cold would otherwise require to 
 be done by hand in the manner used for regulating a common watch." This 
 method of effecting the compensation, although it evinces considerable inge- 
 nuity, is now seldom used, owing to the extreme difficulty of effecting an accu- 
 rate adjustment ; recourse is therefore had to the principle introduced by 
 P. Leroy, a modification of which is seen in the figure on the following page, 
 which represents the balance of a chronometer as commonly constructed. A 
 circular groove is turned in the flat face of a piece of steel, and into this groove
 
 692 HOROLOGY. 
 
 a piece of good brass is driven, and a little of the solution 
 of borax is applied to prevent oxydation. This compound 
 piece being then put into a crucible, is made sufficiently 
 hot to melt the brass, which in these circumstances ad- 
 heres firmly to the steel without requiring any solder. 
 The face of the steel is then cleaned, and by proper appli- 
 cation of the mechanical means of turning, boring, and 
 filing, the superfluous steel is taken away, and the balance 
 is left, consisting of two, or sometimes three, radii, and a 
 rim, the external part of which is of brass, and the internal part of steel, the former 
 metal being about twice the thickness of the latter. In this state the arms of 
 the rim are then cut through and diminished in their length, as in the figure ; 
 and near that extremity of each arc which is farthest from its radius, is put on 
 a piece or weight, which can be slided along the arm, so as to be adjusted at 
 that distance which shall be found, upon trial, to produce a good performance 
 under the different changes of temperature; the flexure of the arms by the change 
 of temperature carrying the weights nearer to the centre in hot than in cold 
 weather, and the more the greater the distance of the weights from the radius. 
 The small screws near the ends of the radii afford an adjustment for time, as 
 the balance will vibrate more quickly the further these are screwed in ; and the 
 contrary will be the case if they be unscrewed or drawn further out. 
 
 The accompanying cut shows a balance according to the constniction of 
 Arnold, and specified by him to the com- 
 missioners of longitude. The expansion 
 weights are cylindrical, and are adjusted 
 upon the arms by screwing ; and there is 
 an inner rim, upon which three weights are 
 adjusted by sliding, which serve to regulate 
 the going of the time-piece in different posi- 
 tions. The necessity of a different adjust- 
 ment of the balance, according as the balance 
 is to vibrate with its axis vertical to the 
 horizon, or parallel to it, will be obvious 
 when we consider that the pivots of the axis 
 bear very differently according to the position of the chronometer ; and it 
 requires some management to make the frictions the same, whether the axis be 
 turning upon one of its ends, or upon the two cylindrical faces of the pivots ; 
 and still more than this, since the balance itself has a permanent figure com- 
 pared with the spring, which, in every part of its vibration, alters its distance 
 from the axis, and in every part of its length has a different degree of rotatory 
 motion it cannot be expected, nor does it happen, that a balance, which is 
 found to be in poize along with its spring when out of the chronometer, will 
 make equal vibrations, as to time, in all positions when in its place ; and in 
 addition to these difficulties, there is one part of the vibration where the force 
 of the spring and the inertia of the balance are not simply in opposition to 
 each other, but are combined with the maintaining power, viz. during the action 
 of the escape. .. The remedy for all these difficulties, which is happily adopted 
 in chronometers for use at sea, is to place the axis in a vertical position, by 
 which means the balance itself is not affected by gravity ; but for pocket time- 
 pieces, the ingenuity of the artist is called upon for expedients of which it 
 would not be easy to exhibit a complete theory. The general principle com- 
 monly used, is to consider the balance, when out of adjustment for position, as 
 a pendulum when above and below the centre of suspension, acted upon by 
 gravity, and, at the same time, urged to a quiescent point by the force of elas- 
 ticity. In these circumstances the vibrations will be quickest when the point 
 of stable equilibrium is downward, and they will be slowest in the opposite 
 positions of the machine. This leads to the remedy of diminishing either the 
 radius or the weight on that side which is lowest when the rate is most quick. 
 Thus, if one of the two adjusting screws in the first of the preceding balances 
 were downwards in the position of quickest rate, that screw would require to
 
 HOROLOGY. 693 
 
 be screwed a very little quantity inwards, and the opposite screw to be screwed 
 a like quantity outwards, in order to remedy this imperfection without much 
 alteration of the other adjustments. And if a like imperfection were found in 
 the vibrations of the balance when tried in a vertical position, having the lowest 
 point at rest in a line at right angles to a line passing through the radii, a 
 similar alteration must be made in the expansion weights, either by a careful 
 flexure of the circular arcs, or by altering the quantities of those weights ; or 
 else by means of small circular screws tapped into the weights themselves, and 
 directed towards the centre like the weights at the extremities of the radii. By 
 these, and other correspondent means, the balance may be made to keep time 
 in all those positions wherein its plane shall be perpendicular to the horizon ; 
 but even in these trials Very great pains and labour may be required to produce 
 a high degree of accuracy ; and, after all, as the quantity of action in the 
 spring must alter the quantity of pendulous effect in this curious and delicate 
 time measurer, it may be doubted whether the adjustments for position in the 
 vertical balance can be effectual any longer than while the arcs of vibration 
 remain the same. This consideration points to the necessity of an adjustment 
 in the maintaining power, in order that the vibrations shall not fall off; the 
 means of effecting this will be shown in treating of the different sorts of escape- 
 ments, to the consideration of which we shall now proceed. 
 
 The escapement is a general term for the manner of communicating the 
 motion of the wheels to the pendulum of clocks or balance of watches. One 
 of the 'most ancient escapements is that which is now applied in almost all 
 common pocket watches: it is represented in Fig. 1, and is best suited to the 
 long vibrations of the balance, which was invented earlier than the pendulum. 
 a b denotes the rim of a contrate wheel, pig. \, 
 
 called the crown wheel, having its teeth 
 pointed and sloped on one side only, so that 
 the points advance before any other part of 
 the teeth during the motion, c and d are 
 two pallets or flaps, proceeding downwards 
 from the verge ef. The pallets are nearly 
 at right angles to each other ; and when 
 the balance f g, fixed on the verge, is at 
 rest, the pallets remain inclined to the plane 
 of the wheel, in an angle of about forty- 
 five degrees ; but when it is made to vibrate, 
 one of the pallets is brought nearer to the 
 perpendicular position, while the other becomes more nearly parallel. The wheel 
 must be supposed to have one of its teeth resting against a pallet by virtue 01 
 the maintaining power. This tooth will slip off or escape as the pallet rises 
 toward the horizontal position, at which instant a tooth on the opposite side or 
 the wheel will strike against the other pallet which is down. The returning 
 vibration, by raising this last pallet, will suffer that tooth to escape, and another 
 tooth will apply itself to the first-mentioned pallet. By this alternation, the 
 crown wheel will advance the quantity of half a tooth each vibration, and the 
 balance or pendulum will be prevented from coming to rest, because the impulse 
 of the teeth against the pallets will be equal to the resistances from friction, and 
 the reaction of the air. This escapement not being adapted to such vibrations 
 as are performed through arcs of a few degrees only, another construction has 
 been made, which has been in constant use in clocks for this century past, 
 with a long pendulum beating seconds. Fig. 2, on the next page, a b represents 
 a vertical wheel, called the swing wheel, having thirty teeth, c d represents 
 a* pair of pallets connected together, and movable, in conjunction with the 
 pendulum, on the centre of axis /. One tooth of the wheel in the present 
 position rests on the inclined surface of the inner part of the pallet c, upon 
 which its disposition to slide tends to throw the point of the pallet further 
 from the centre of the wheel, and consequently assists the vibration in that 
 direction. While the pallet c moves outwards, and the wheel advances, the 
 point of the pallet d, of course, approaches towards the centre, in the opening 
 4 T
 
 6!4 
 
 HOROLOGY. 
 
 between the two nearest teeth; and when the 
 
 acting tooth of the wheel slips off', or escapes 
 
 from the pallet c, another tooth on the opposite 
 
 side immediately falls on the exterior inclined face 
 
 of d, and by a similar operation tends to push that 
 
 pallet from the centre. The returning vibration is 
 
 thus assisted by the wheel, while the pallet moves 
 
 towards the centre, and receives the succeeding 
 
 tooth of the wheel after the escape from the point 
 
 of d. In this manner the alteration may be con- 
 ceived to go on without limit. The celebrated 
 
 George Graham improved this escapement very 
 
 much, by taking off part of the slope furthest from 
 
 the points of the pallets ; instead of which part 
 
 he formed a circular or cylindrical face, having its 
 
 axis in the centre of motion. Pallets of this kind 
 
 are seen on the opposite side of the wheel at e 
 
 and g, having h for their centre or axis. A tooth 
 
 of the wheel is seen resting upon the circular inner 
 surface of the pallet g, which is not therefore 
 affected by the wheel, excepting so far as its motion, 
 arising from any other cause, may be affected by the friction of the tooth. If the 
 vibration of the pendulum be supposed to carry g outwards, the sloped surface will 
 be brought to the point of the tooth, which will slide along it and urge the pallet 
 outwards during this sliding action. When the tooth has fallen from the point of 
 this pallet, an opposite tooth will be received on the circular surface of e, and will 
 not affect the vibration, excepting when the slope surface of e is carried out so 
 as to suffer the tooth to slide along it. In the two former escapements, there is 
 always a certain portion of vibration takes place after the drop which drives 
 the pallet back, and causes the index also to recede through a small arc : this 
 has been distinguished by the name of a recoil. The escapement of Graham, 
 and all such as have no recoil, have been called dead beat escapements, because 
 the index for seconds falls directly through its arc, and remains motionless on 
 the line of division till the next vibration. It may be observed, that the main- 
 taining power in Graham's escapement, may be applied during a small 
 portion only of the vibration ; and that an increase of the maintaining 
 power tends to enlarge the arc of vibration, but scarcely interferes with 
 its velocity. In the escapements just described, the escape wheel is in continual 
 contact with the pallets belonging to the axis of the balance, and the friction 
 arising from this circumstance may be considered as a principal cause of the 
 irregularity in the going of watches. If we suppose a regulator to be made so 
 perfect as to be perfectly isochronal, while vibrating in a free position, that 
 advantage would be diminished, or lost, as soon as it was placed in connexion 
 with a train of wheels ; and the errors would be more or less, according to the 
 nature and quantity of friction in the escapement. It would be, therefore, 
 extremely useful to secure to the regulator a perfect liberty of vibration, 
 except during the short intervals of time which may be necessary for the action 
 of the escape wheel, to give it a new impulse. This ingenious idea was first 
 started, and also carried into execution by P. Leroy, who in 1748 presented to 
 the Academy of Sciences in Paris a model of a detached escapement, the 
 effect or action of which may be briefly described as follows : an escape wheel 
 is kept in repose by a lever detent ; the balance unlocks the detent, and 
 receives an impulse or stroke on a pallet through a part of every second vibra- 
 tion, and during great part of its course it is free and detached. A great 
 variety of escapements have been contrived by various ingenious men ; those 
 in which springs are used in the locking pieces instead of pivots are at present 
 generally preferred; we shall, therefore, proceed to describe the escapement ot 
 Mr. Arnold, who we believe is the author of this improvement. The engraving 
 on the next page is a representation of this escapement. The teeth of the 
 escape wheel are of a cycloidal sl.ape, in the face Dart, which is intended for
 
 HOROLOGY. 
 
 695 
 
 action, the sections of which, with those of the two other sides, form a sort of 
 mixed triangle, b b d represents the detent, which is formed of a .flexible 
 piece or spring, bending between c and n; and in the part nbd, which is 
 stronger than the other, is fixed the locking pallet a, opposite an adjusting 
 screw/. The pallet projecting below the spring detent locks upon the interior 
 angle of the tooth, suspending the 
 motion of the escape wheel, and 
 leaving the balance to vibrate free, 
 as pointed out in the preceding 
 escapements. The action of the 
 spring detent (for the joint of the 
 detent is itself a spring) presses the 
 locking pallet against the screw /, 
 except at the time of unlocking the 
 wheel. A very delicate spring n e, 
 called the discharging, or unlocking 
 spring, (and also the tender spring,) 
 is attached by one end n to the 
 spring detent cb nb a ; and passing 
 under the adjusting screw/, extends 
 a little beyond the extremity d, by 
 the detent itself; hhh is a circular 
 piece attached to the axis of the 
 balance, and o the discharging pallet. 
 
 This pallet when the balance is in motion from e to d presses against the end 
 of the discharging spring n e ; and carrying it together with the locking spring 
 b b d disengages the locking piece a out of the internal angle of the tooth, 
 with which it was in contact ; and the escape wheel then communicates a new 
 power to the balance by its impulse on a pallet m, which is fixed or set in the 
 aperture of the circular piece. As soon as this is done, the spring detent, or 
 locking spring, falls back to its position against the adjusting screw// and the 
 pallet, by receiving or intercepting the next tooth, stops the motion of the 
 escape wheel. When the balance returns from d to e, the unlocking pallet acts 
 again on the extremity of the discharging spring, but this being very delicate, 
 gives way without disturbing the detent, or locking spring ; and the balance, 
 after suffering a trifling degree of resistance by that contact, continues its free 
 vibrations. At the next vibration the unlocking takes place, and the action of 
 the escapement proceeds successively, as explained before. The detached 
 escapement was applied first to chronometers or time-pieces, but is now also 
 used for astronomical clocks ; and various excellent constructions have been 
 invented by different artists, amongst which we may mention those of Hardy 
 and Reid. In 1812, Mr. Prior, jun. was rewarded by the Society of Arts for 
 the construction of a detached remontoire escapement for clocks, which pos- 
 sesses considerable merit. The advantages of this escapement consist in the 
 freedom of its parts from friction ; in the exact and equal impulse which it will 
 continue to give to the pendulum, unaffected by the clogging of oil and 
 increased friction of the train ; and in the small power required for restoring 
 the tension of the remontoire spring, which does not require to be wound up 
 quick, or to be pushed beyond any catch or spring to keep it in its proper 
 situation. The engravings on page 696, with the following description extracted 
 from the Transactions of the Society, will explain the construction. The 
 swing-wheel, Fiys. 1 and 3, has thirty teeth cut in its periphery, and is constantly 
 urged forwards by the maintaining power which is supplied by the small weight ; 
 two spring detents are used to catch the teeth of the wheel alternately ; these 
 are, at the proper intervals, unlocked by the parts marked 1 and 3 upon the 
 pendulum rod, intercepting two small pins projecting from the detents, as it 
 vibrates towards the one or the other ; the renovating or remontoire spring is 
 fixed to the same stud as the detents ; it is wound up by the highest tooth of 
 the wheel, as seen in Fig. 1, (its position when unwound being shown by the 
 dotted lines.) This being the case, suppose a tooth of the wheel is caught by
 
 696 
 
 HOROLOGY. 
 
 one of the detents, this prevents the wheel from moving any further, and keeps 
 the renovating spring from escaping off' the point of the tooth ; in this posi- 
 tion, the pendulum is quite detached from the wheel ; now, if the pendulum be 
 caused to vibrate to the right, the part of it marked 2 conies against the upper 
 pin, seen in Fig. 2, projecting from the renovating spring, and pushes this spring 
 from the point of the wheel's tooth ; on vibrating a little further, the pendulum 
 removes the detent which detained the wheel, by the part 3 striking the lower 
 pin, Fig. 2, which projects from the detent ; the maintaining power of the clock 
 causes the wheel, thus unlocked, to advance until detained by a tooth resting upon 
 
 the end of the other detent on the opposite side ; by this means the renovating 
 spring will be clear of the tooth of the wheel as it returns with the pendulum, and 
 gives it an impulse with its pin pressing against the part 2 of the pendulum, 
 until the spring comes to the position shown by the dotted line, in which position 
 it is unwound, and rests against a pin fixed against a cross bar of the plate ; 
 the pendulum continues vibrating to the left, nearly to the extent of its vibra- 
 tion, when the part 1 meets the pin in the same detent, and removes it from 
 the wheel, and unlocks it; the maintaining power now carries it forward, 
 pushing the renovating spring before it until another tooth is caught by the 
 first detent, which detains the wheel in the position first described, the renovating 
 spring being wound up ready to give another impulse to the pendulum. The 
 pin is not fixed to the renovating spring itself, but is part of a piece of brass, 
 which is screwed fast to the renovating spring, and is made very slender near 
 the screw which fastens it ; this permits the renovating spring to give way, if, 
 by the weight being taken off the clock, or any other accident, the escape 
 wheel should be wound backwards, so as to catch on the detents improperly. 
 The weight in the preceding figures merely represents the means by which 
 the escape wheel was put in motion in the model presented to the Society, which 
 consisted merely of the escapement ; but when attached to a clock, the remon- 
 toire spring is wound up by the maintaining power of the clock transmitted to 
 the escape wheel by means of the train. 
 
 Chronometers and clocks for astronomical purposes, in which extraordinary 
 nicety in the exact measurement of time is necessary, have, besides the com- 
 pensation pendulums or balances, and detached escapements, before described
 
 HOROLOGY. 6 J)7 
 
 jewtlled pallets, and all their pivot-holes jewelled : they are likewise provided 
 with a contrivance for continuing their motion during the time of windin* up, 
 when the action of the maintaining power is suspended. For this purpose a 
 second larger ratchet wheel is added on the same arbor which admits the clock 
 to be wound up, but with teeth pointing the contrary way ; a strong spring, usually 
 the greatest portion of a circle, connects this large ratchet wheel with "the great 
 wheel of the clock, which is on the same axis with it, one end of this spring 
 being attached to the great wheel, and the other to the large ratchet ; and a 
 catch proceeds from the inner face of this back plate to the teeth of this ratchet, 
 which prevents its moving back when the clock is winding up, and serves as a 
 support for the reaction of the maintaining spring. When the clock is left to 
 the action of the weight, the small ratchet turns round the larger one, and con- 
 tracts or coils up the spring till it has strength sufficient to impel the great 
 wheel and train ; and when the action of the weight is suspended, as in wind- 
 ing up, the spring, freed from the contracting power of the weight, expands 
 itself and forces round the great wheel, its action in the contrary direction on 
 the great ratchet being prevented by the catch before mentioned. Leroy is 
 considered to be the inventor of the spring impeller to prevent loss of time in 
 winding up, but the idea of continuing the motion of the train during this 
 time originated with Huygens, for he contrived a method by which the weight 
 of his clock should continue to act on his train whilst it was drawing up ; the 
 weight in his clock having been made to draw up in a similar manner to that 
 used in common wooden clocks, instead of being wound up as in our metallic 
 clocks. 
 
 What has been already advanced, will, we trust, be sufficient to convey a 
 clear idea of the nature and general construction of horological machines; but 
 great diversities in their form and a variety of curious movements have been 
 introduced by the taste and ingenuity of artists in this branch : some of these 
 excite admiration by the number and intricacy of the component parts, and the 
 admirable precision with which they act, whilst others evince equal ingenuity 
 by the simplicity of the means adopted to obtain the end proposed. Of this 
 last description of clocks, none have as yet exceeded that invented by the cele- 
 brated Dr. Franklin ; it shows the hours, minutes, and seconds, and yet con- 
 tains but three wheels and two pinions in the whole movement. The lowest 
 wheel contains 1 60 teeth, and goes round once in four hours ; it carries the 
 hand on its axle, which points out both the hours and the minutes, as will be 
 described, and it turns a pallet above it of 1 leaves, on the same axis with 
 which is a wheel of 120 teeth, that gives motion to a pallet of 8 leaves : the 
 second-hand is annexed to the same axis with this latter pallet, as also the 
 swing-wheel, which carries 30 teeth, that gives motion to the pallets of an 
 anchor escapement, and to its pendulum that vibrates seconds. The dial of this 
 clock is of singular formation ; the external circle on it contains 240 divisions, 
 numbered from 1 to 60, in four successive notations ; this circle shows the 
 minutes ; within it the hours are arranged in three concentric circles, or in a 
 volute of three revolutions along four radii, which form right angles with each 
 other. By this arrangement, while the point of the hand shows the minute, its 
 side exhibits the hour ; or, more strictly speaking, shows that the hour is one 
 of three ; but so that it will hardly ever happen that any doubt will remain of 
 which it may be, as there are four hours difference between the figures next to 
 each other on the same radial line. A small circle is placed above the great 
 one, and divided into 60 parts for the seconds. This clock was wound up by a 
 line going over a pulley and ratchet, on the axis of the great wheel, by which 
 the weight was drawn up in the same manner as in the common wooden clocks. 
 Many of these clocks have been made which are found to measure time exceed- 
 ingly well. The small imperfection in this clock, of its leaving the uncertainty 
 mentioned as to which of three hours it denotes, though so easily corrected by the 
 judgment, has given rise to some ingenious contrivances to obviate it. Of these 
 the most curious is that which forms the subject of the engraving on page 698. To 
 the great wheel of this clock two concentric plates are annexed, the external 
 one of which has a groove cut through it along the line of a volute of three
 
 HOROLOGY. 
 
 revolutions. This groove forms a trough, in which a metal hall is placed, part 
 of which is seen through the excavation beneath the hour 1 1 in the figure ; as 
 the plate and groove turn round, the ball rolls along the volute, still approaching 
 nearer the centre as it proceeds ; and when it at last arrives at the centre, it 
 falls into another trough, by which it is again conveyed to the external part of 
 the volute. The hours are engraved between the revolutions of the volute, 
 
 J ___ 
 
 and the minutes are marked in four divisions of 60 each, upon an external 
 fixed circle, to which an index annexed to the volute plate points. Several 
 of these clocks were to be seen in the watchmaker's shops in London some 
 years ago, but we believe the author of this ingenious contrivance is unknown. 
 
 In addition to the parts which measure and register time, and therefore 
 alone constitute a watch or clock, various appendages are at times connected 
 with them for pleasure or convenience, as chimes and puppets to clocks, 
 musical and repeating movements, &c. to watches ; but as these are not strictly 
 comprised under the head of horology, we shall merely notice one or two 
 inventions of this class, our limits not allowing us to do more. 
 
 One very useful addition which is frequently made to clocks and watches, is 
 the alarum, or contrivance for calling attention at any fixed period of time. An 
 excellent arrangement of this kind is the patent detached alarum watch, invented 
 by Mr. Berollas, of the City Road, which is an improvement upon a former 
 invention of the same gentleman called the warning watch. In the present 
 invention all the useful parts of the watch are retained, while those that were 
 inconvenient or had a tendency to disturb its regular movements are here in 
 a detached state. The advantages that result from this arrangement are, first,
 
 HOROLOGY. 
 
 G99 
 
 Fig. I 
 
 the applicability or adaptation of the invention to all kinds of watches, what- 
 ever may be the principles of their construction ; second, the alarum being 
 detached from the watch, it can be made to produce a noise sufficiently loud fc 
 a house alarum ; third, alarum watches as before constructed were inconvenient, 
 from their bulk, to wear by this contrivance they may be made as flat and 
 thin as may be desired ; and, lastly, the expense is much less than any watches 
 hitherto made of similar performance. Fig. 1 represents the mechanism 
 attached to the watch, by which 
 the alarum is locked and unlocked, 
 as it appears when the dial-plate is 
 removed. The index by which the 
 alarum is set to the proper time of 
 going off, is attached to a hollow 
 axle fitted upon the arbor of the 
 ordinary hour-wheel. This index 
 may be set by hand ; but a prefer- 
 able method is to attach a toothed 
 wheel 4, which works into an inter- 
 mediate wheel 7, which works into 
 the wheel 6, and this latter works 
 into a wheel 3, fixed at right an- 
 gles to it upon the square end of 
 the steel arbor 1, which runs through 
 the pendant, and has at its other 
 extremity a milled nut 2, by turning 
 which nut it is obvious that motion 
 will be conveyed to the ulaiuin 
 wheel and index to set it at any 
 particular hour. To prevent the 
 train being turned the wrong way, 
 and to retain the index in its place, a small ratchet wheel is fixed upon the 
 square part of the steel arbor 1, into which ratchet a spring-pall 5 falls. The 
 hollow axis of the alarum index is made of steel, and on its underside is formed 
 into a flat circular plate, as at 44, which represents the 
 reverse side of the wheel 4 ; and in this plate a notch is cut 
 straight down on one side, and sloping on the other, as 
 shown at 45, which is a section of the wheel and hollow 
 axle, the straight side of the notch lies in the direction of a 
 radius of the flat plate in 44. The hour-wheel, marked 
 A, Fig. 2, lies immediately underneath the alarum wheel, 
 and has on its under side an oblong steel plate, 1, 2, 3, 
 in the detached figure A of Fig. 2, which is called the 
 detent. The detent is spring-tempered, has a hole in its 
 centre for the free passage of the cannon arbor, and is 
 fixed flat upon the hour-wheel by a small screw and steady 
 pin at 2; into the opposite end of the detent plate at 1, 
 is rivetted a small pin of sufficient length to pass through 
 a hole in the hour-wheel, and to project beyond the upper 
 surface of the same in such manner, that when the hour- 
 wheel and the alarum-wheel are put together in their right 
 places, and this pin presses upon the flat surface of the steel 
 plate 44, the end 1 of the detent is depressed below the 
 under face of the hour-wheel, but when it comes over the 
 notch it falls into the same, and allows the end of the 
 detent to rise and lie flat in the recess in the hour-wheel. TL end 1 of the 
 detent acts upon the circular end 2 of a flat steel spring C, Fig. 1, and shown 
 detached in the following page ; it is called the elevator, and is fixed in its 
 place by the screw and steady-pin at Z, which end is thicker than the other 
 parts of the spring, so that the end 2 is raised above the plate on which it is 
 fixed ; the degree of elevation may be adjusted by turning the screw-top at y,
 
 700 
 
 HOROLOGY. 
 
 i/ 
 
 :/ 
 
 which works freely through a hole in the elevator. The 
 end 1 of the detent presses upon the elevator in such 
 manner, that whilst the detent is depressed it holds 
 down the end 2 of the elevator ; but so soon as the pin 
 in the detent enters the notch, and the detent rises, the 
 pressure is withdrawn from the elevator, and it likewise 
 rises to discharge the alarum, which it does through the 
 medium of another piece called the propeller, drawn in 
 its proper place and form at D, Fig. 1, and also shown 
 in the detached figure in the margin. It is a steel lever 
 without spring, and turning upon the screw x as a ful- 
 crum ; it has a projecting piece W, which is formed 
 into an inclined plane, and highly polished and har- 
 dened ; this inclined plane falls directly under the end 2 
 of the elevator C, also polished at this part; consequently, 
 whenever the elevator is depressed by the detent, its 
 end 2 will press upon the inclined plane W of the pro- 
 peller, and drive its end V outwards ; this end is formed 
 into a portion of a circle not concentric with x, and 
 presses against the locker E, Fig. 1, which is a cylin- 
 drical piece of steel, having -in its outer end a small pin s projecting through 
 the case of the watch ; the locker E moves between two pins, and is pressed 
 against the end of the propeller D by the spring F, and kept at all times in 
 contact with it. The combined effect of the several parts may be briefly 
 recapitulated as follows : whilst the detent is depressed, it presses down the 
 circular end of the elevator c, which acting upon the inclined plane W of the 
 propeller D, forces its circular end against the locker E, and causes its small 
 pin * to protrude beyond the case, in which state it will remain until, by the 
 revolution of the hour-hand, the pin in the detent falls into the notch on the 
 alarum arbor ; when the elevator rises, and the pressure being withdrawn from 
 the inclined plane of the propeller, the locker E is pushed in by the spring F, 
 and remains in that position until the sloping side of the notch 44 has been 
 moved round sufficiently to depress the detent spring again. The above is all 
 that is necessary to form the union between the going parts of any watch, and 
 a detached alarum, because it will be evident that such alarum may be dis- 
 engaged or set off by the sudden withdrawal of the locker ; we shall therefore 
 proceed to describe the manner in which the alarum movement is operated 
 upon, whether the alarum of the bell, rattle, or any other kind. 
 An alarum movement in 
 
 Fig- 2- 
 
 its separate state is repre- 
 sented at G H, in the an- 
 nexed figure, and consists of 
 a frame, the upper plate of 
 which is nearly half an inch 
 less than the pillar plate, in 
 order that the works may be 
 covered by, and contained 
 within the bell, as shown at 
 Fig. 2, which is a section or pro- 
 file of the alarum movement. 
 A going barrel, which contains 
 the mainspring, is placed in 
 the centre of the said frame, 
 and a steel wheel cut with 
 ratchet teeth to work the 
 
 hammer is fixed on the upper part of the said barrel, its other side carrying 
 the main wheel to drive the train, which generally consists of three wheels and 
 four pinions. The alarum hammer has a spring and a regulating spring on tae 
 opposite side of the plate as shown at K, Fig. 4. The fly pinion has an arm of 
 steel fixed on its arbor, and as this comes in contact with the projecting pin,
 
 HOROLOGY. 
 
 701 
 
 the works are locked, and the alarum prevented from running down ; but so 
 soon as the pin H is moved, the whole is at liberty, and free to move ; the 
 pin H passes through a hole in the plate, and rises from the locking lever H 
 on the other side of the plate, as shown in Fig. 4, where it may be seen that this 
 locking lever turns on a screw pivot at its inner end, and is constantly pressed 
 to one side by the force of the spring P, which operates in such a direction as to 
 throw the pin out of contact with the steel arm of the fly arbor, and consequently 
 always keeps the alarum work in a free state for motion ; but it may be locked 
 at any time by pushing the locking lever H, Fig. 4, back- 
 wards, or against the action of its spring P ; a wire tail, I, 
 rises perpendicularly out of the outer end of the locking 
 lever H, and it is this wire tail that is to be engaged with 
 the small end s of the locker E s, Fig. 1, whenever the 
 alarum is to be wound up and set. This locking lever 
 H, with its two pins, is here shown in a detached state. 
 
 Fig. 5 shows a watch having all the above described 
 parts appertaining thereto, and placed upon one of the 
 aforesaid detached alarum movements; I being the case 
 of the alarum, formed of open-work, chased or otherwise 
 
 ornamented, and having the appearance, when empty, of the ordinary receptacle 
 of an external watch case ; M being the usual rim that shuts down over the watch 
 with a spring catch, and thereby holds it steadily in its proper position ; the 
 alarum movement is fixed in this external case, with the pillar plate upwards, 
 and the works and bell downward; consequently, the wire tail I, Fig. 4, projects 
 upwards into the case, and in placing the watch within, it is necessary to observe 
 that the projecting end of the locker *, Fig. 1, comes behind, and engages 
 with this wire tail, as seen at H F, Fig. 5, in such manner, that it may push 
 back the locking lever, li, Fig. 4, and thereby lock the train of the alarum 
 when the rim M is to be shut down, and the alarum hand set as aforesaid 
 
 4 u
 
 702 
 
 HOROLOGY. 
 
 to the time upon the dial when it is to be discharged. The alarum may 
 then be wound up by the key, or milled head K, Fig. 2, which is screwed 
 upon the main spring arbor, 
 so that it can only turn it Fig. 4. 
 in one direction without un- 
 screwing, and the machine 
 will be reudy to operate ; be- 
 cause at the assigned hour 
 and minute, the ends of the 
 locker will be withdrawn into 
 the watch, thereby releas- 
 ing the wire tail I, and the 
 locking lever H, Fig. 4, by 
 which the alarum will be dis- 
 charged, and will instantly run 
 down. 
 
 What has been said of 
 the bell alarum movement, 
 equally applies to rattle move- 
 ments, because they consist 
 of the same parts, and are 
 constructed and used in the 
 same manner, except only that the bell, the hammer, and the steel ratchet 
 wheel for working the same, and the springs connected therewith, are dis- 
 pensed with, and in lieu thereof, the rattle movement, shown in Fig 6, is sub- 
 stituted. This consists of two strong steel wheels N N, so fixed or screwed 
 upon the outside of the upper 
 
 plate that they may both press ^^^BSWli^H^t. Fi<>. fi. 
 
 in the same direction against 
 the two strong pins or studs q q 
 to receive them, and the upper 
 plate may in this construction 
 be made of the same diameter 
 as the lower plate, because 
 there is no bell to go over it. 
 A coarse steel pinion M is fixed 
 on to a square upon the con- 
 tinued arbor of the first wheel 
 in the movement, and which 
 "wheel for this purpose is brought 
 nearer to the edge of the plate, 
 in such manner that the lever 
 of the said pinion may engage 
 with the ends of both the 
 springs N N, and by its revo- 
 lution may carry them some 
 distance towards r. and on their return they strike against the pins q q, and 
 produce a powerful rattling noise; more or less springs may of course be used 
 for a similar purpose, according to the extent of noise required. 
 
 Of late years, the ingenuity of watch-makers has been much exercised in 
 the winding up of watches, without the employment of detached keys ; but 
 from the difficulty of applying such an improvement to watches having fusees, 
 their efforts have been solely directed to the winding up of those having going- 
 barrels ; and various contrivances have been proposed and adapted to the latter 
 for that purpose. Mr. Berollas, whose patent detached alarum watch we have 
 just been describing, has, however, overcome all the obstacles which the sub- 
 ject opposed to him, and has contrived the means of winding up watches of both 
 construction without keys, by a contrivance exhibiting great simplicity as well 
 as ingenuity. For this invention he has taken out a patent, and from the 
 specification of it we make the ollowing extracts; which, together with the
 
 HOROLOGY. 
 
 703 
 
 annexed engraved figures, will give the reader a full insight into the arrange- 
 ment and the mode of constructing this useful improvement. " The first 
 mover, or power, in most horological works, is obtained either by the action of 
 a weight or spring. In pocket watches, the power is obtained by a spring 
 called the main spring, which is enclosed in a box called the barrel. Now there 
 are two distinct ways of applying the power of this main spring to the first 
 wheel of a watch ; one of them consists in the intervention or agency of a fusee, 
 which is put upon the first wheel ; in the other, the first wheel is put upon the 
 barrel itself that contains the spring, which arrangement is distinguished from 
 that having a fusee by the term 'going-barrel.' Watches having going-barrels 
 are wound up by turning round the barrel arbors ; and watches having fusees, 
 by the fusee arbors. My invention consists in a new mechanical arrange- 
 ment, applicable to the winding up of horological works. First, as respects 
 what is termed a going-barrel, the following are the contrivances that I have 
 invented as applicable thereto : Fig. I represents a watch with a going- 
 barrel, to which my invention is applied ; in which figure a part of the dial- 
 plate is represented as broken away, for showing the novel parts, the operation 
 
 of which will be understood by first describing the separate figures, 2, 3, 4, 5, 
 6, 7, 8, all the same letters of reference in which refer to similar parts. Fig. 2 
 is the barrel ratchet with its click and spring, which keeps the maintaining 
 power up ; this ratchet is put on the barrel arbor, which is squared, and the 
 plate is sunk in which it Jays it is on the side of that part of the plate under 
 the dial ; this barrel ratchet is sunk or turned out as far as the teeth to receive 
 another ratchet with its click and spring, shown at a, Fig. 3, which I call the 
 
 a groove to receive a chain d, shown at Figs. 1 and 8, which is hooked on a
 
 704 HOROLOGY. 
 
 pm in the said groove. Fig. 7 gives a perspective view of the stud which 
 keeps the barrel pulley steady and close to the barrel ratchet ; the centre of this 
 stud is round, and the centre of the recoiling spring is hooked on to it ; the 
 other end of the recoiling spring is hooked on the barrel pulley. Figs. I and 8 
 show the impendent, made of the same metal as the case ; it turns freely 
 on a piece of steel g, Fig. 8 ; this steel arbor has a small knob on one side, h, 
 shown at Figs. 1 and 8, to prevent the impendent from slipping off; on the 
 other end it is split to receive the end of the chain which is pinned on ; the 
 pendent of the case is perforated, through which the chain passes. I shall 
 next describe the manner it is to operate, and how it is to be put on the wind- 
 ing up arbor. When the barrel ratchet before mentioned is put on the square 
 arbor, the recoiling spring is put on the barrel pulley, and placed over the 
 barrel ratchet, so as to act on its click ; the chain, which is no longer than to 
 produce one revolution of the pulley, is put through the pendent, and hooked 
 on to the pulley : the stud is then hooked on to the recoiling spring ; by this 
 stud the recoiling spring is set up one turn, more or less, and the stud is screwed 
 on the plate. To wind up the watch, the impendent is drawn from the pendent 
 as far as the chain will permit it ; the recoiling spring will bring the impendent 
 back again to the pendent ; and this operation is repeated till the impendent 
 remains on the pendent, and cannot be more drawn from it, which indicates 
 that the main spring is wound up. When the works are to be wound up by a 
 fusee arbor, the ratchet, which keeps the maintaining power, is on the fusee 
 itself; the fusee arbor, squared, is on the same side of the plate as the going- 
 barrel under the dial. The recoiling ratchet, Fig. 4, is put on the fusee arbor ; 
 its click and spring are on the barrel pulley, Fig 6. Here it is to be observed, 
 that when any works are to be wound up by a fusee, the fusee with the first 
 wheel and its arbor returns back again, which is not the case with a going 
 barrel, h is the relieving click, which has a double action ; first, it acts as the 
 recoiling click, by its action in the ratchet ; secondly, it acts as a reliever of the 
 said click ; it is planted on the under side of the barrel pulley, Fig. 6, with its 
 spring, and must be made in the form shown in the drawing. That part which 
 is near the edge of the barrel pulley has a small pin, which pin goes through 
 an aperture of the barrel pulley into the groove where the chain lies. When 
 the works are wound up, the impendent rests upon the pendent, and the chain 
 lays round the pulley, which is the same as with the going-barrel. The pin of the 
 relieving click, which goes into the groove of the barrel pulley, receives a pres- 
 sure from the chain ; it brings the click part out of the ratchet, and gives free 
 action to the ratchet on the fusee arbor to return back again without any drag 
 or incumbrance of the click. /, Fig. 1, is the finger touch : it is made of gold, 
 or some metal which will not rust. By referring to the drawing, it will be seen 
 that it is a kind of cup with a milled edge, and the minute-hand is fastened to 
 it : when the hands are to be set, a slight pressure with the end of the fore- 
 finger is required to turn the hands. In case it is desired to have a watch or 
 clock wound up in one pull, the multiplying of the turns of the chain round 
 the barrel pulley will have that effect. 
 
 The engraving on the next page exhibits a simple but very ingenious contri- 
 vance, termed by the inventor, (Mr. Knight, of Birmingham,) the " Patent Duty 
 Register," which is designed to operate as a check upon public watchmen, and 
 to ensure vigilance upon their part, by causing them to register the time at 
 which they go their rounds, in a manner that will admit of no deception. 
 Its uses, however, are not limited to this purpose, as it is equally serviceable as 
 a check upon servants in general, and as a conviction of the correct informa- 
 tion which it will infallibly afford to employers, it has a tendency to ensure 
 punctuality on the part of those from whom it may be required. The train of 
 wheel-work in Mr. Knight's machine being similar to those in ordinary clocks, 
 the invention must be regarded as an addition or appendage, which is capable 
 of being applied to clocks already made, as well as to those which are manu- 
 factured purposely to receive the new combination. The only essential variation 
 consists in causing the circular dial-plate, which is usually fixed, to revolve, and 
 the hand or index, which usually revolves, to be fixed. This stationary index
 
 HOROLOGY. 705 
 
 is placed at the top of the circle, and the hours, as they successively come 
 under it, denote present time. This index forms part of a bended lever, the 
 fulcrum of which is in the interior or back of the clock, and the other extre'mity 
 of it is attached to a bell wire, with suitable cranks to carry the line of com- 
 munication to the required place, where a handle is connected to it, for the 
 individual who is upon duty or guard, to pull at stated times ; this operation. 
 
 raises the power end of the lever, and depresses the index, which makes a 
 mark upon a temporary scale of hours fixed "to the dial-plate, and indicates the 
 precise time at which each mark was made. As the lever has only one centre 
 of motion, it follows that the index, which forms a part of it, moves in the 
 arc of a circle, and consequently would only strike upon a point ; but to 
 enable it to make a line, there is a spring joint where the lever is bent to a 
 right angle, which allows the extremity of the index to move in a right line
 
 700 HORSE POWER. 
 
 over the plate. The clock face has two concentric circles of ho.irs, the outer 
 permament and of a full size, the inner temporary, and of small dimensions. 
 The latter is an engraved print, the divisions upon which correspond radially 
 with those on the outer circle, and it is intended that a fresh card should be put 
 on the dial-plate every day ; it is contrived so as to enable them to be put on 
 with accuracy and expedition ; the card taken off forming a register of the 
 duty performed, a is the revolving metal dial-plate ; 6 the revolving card ; c 
 an ornamental metal shield, to confine the card down to the plate, which is 
 fixed to it by means of a thumb screw d ; I is the marker, formed of a little 
 sharp-edged wheel, revolving in a cleft at the extremity of the index, like a spur 
 rowel, only without teeth ; at/ is the spring joint of the lever, before mentioned, 
 forming the upper extremity of the lever. On depressing the lever, the end/ 
 takes the position of e, while c descends on the card dial and makes the mark. 
 In our drawing, .the time expressed is two o'clock ; and if the handle be pulled, 
 the index will descend from the position represented, and make the line drawn 
 between the II, marked s; there are two other lines made upon the drawing, also 
 marked s, which are intended merely as examples to show that such marks were 
 made at the time expressed by the person on duty. The projection of the 
 index in front of the dial is exhibited by the projection of its shadow thereon. 
 HORSE POWER. The force with which a horse acts is compounded of 
 his weight and muscular strength. If, then, the weight of one horse exceed 
 that of another to which it is inferior in muscular strength, the weaker and 
 heavier horse will overcome a resistance which the stronger and lighter horse 
 cannot, provided the excess of his weight in the smallest degree exceeds his 
 deficiency in strength. When a liors^ draws in a mill or machine of any kind, 
 care should be taken that the horse-walk, or circle in which he moves, be large 
 enough in diameter, otherwise he can only exert a part of his strength ; for, in 
 a small circle, the tangent in which he draws deviates more from the circle in 
 which he is obliged to go than in a larger circle. The diameter of the walk for 
 full-sized horses ought not to be less than forty feet ; but if such a space cannot 
 be obtained, and the circle be reduced, it is advisable to procure horses of 
 similarly reduced proportions ; for it has been found that the same horse loses 
 two-thirds of his effective strength in being removed from a walk of 40 feet in 
 diameter to one of only 19 feet. In drawing a carriage, a horse works to the 
 best advantage when the line of draught inclines a little upwards to his breast, 
 making a small angle with the horizontal plane. With respect to the quantity 
 of power a horse of average strength can thus exert, experimentalists have 
 materially differed, owing probably to the limited extent of their trials, with 
 horses of different degrees of strength, and under different circumstances; for 
 much will depend upon the nature of the ground, the proper shoeing, the angle 
 of draught, the fitting of the collar, &c. As a variation in these points will 
 fatigue or cramp the fun* exertion of a horse, a great difference in the amount 
 of a whole day's work must result ; but if we take the average of the data thus 
 furnished to us by the different authors and experimentalists on the subject, we 
 shall find it to amount to 160 pounds' weight, raised at the velocity of 2| miles 
 per hour, the correctness of which has been most satisfactorily shown by some 
 experiments on a very extensive scale by Mr. Bevan, that were recently commu- 
 nicated to the editors of the Philosophical Magazine. Mr. Bevan states, " In 
 the period from 1803 to 1809 I had the opportunity of ascertaining correctly 
 the mean force exerted by good horses in drawing a plough, having had the 
 superintendance of the experiments on that head at the various ploughing 
 matches, both at Woburn and Ashridge, under the patronage of the Duke of 
 Bedford and the Earl of Bridgewater. I find among my memoranda the result 
 of eight ploughing matches, at which there were seldom fewer than seven teams 
 as competitors for the various prizes. 
 
 Ibs. 
 
 The first result is from the mean force of each horse in six 
 teams of two horses each team, upon light sandy soil . . 156 
 
 The second result is from seven teams of two horses each team, 
 upon loamy ground, near Berkhempstead 15
 
 HORSE POWER. 
 
 707 
 
 The third result is from six teams, of four horses each team, 
 with old Hertfordshire ploughs . ........ 
 
 The fourth result is from seven teams, of four horses each team, 
 upon strong stony land (improved ploughs) ...... 
 
 The fifth result is from seven teams, of four horses each team, 
 
 127 
 
 167 
 
 193 
 
 upon strong stony land (old Hertfordshire ploughs) 
 The sixth result is from seven teams, of two horses each team, 
 upon light loam ............... 177 
 
 The seventh result is from five teams, of two horses each team, 
 upon light sand land ............. 170 
 
 The eighth result is from seven teams, of two horses each team, 
 
 upon sandy land .............. 160 
 
 The mean force exerted by each horse, from 52 teams or 144 horses, is equal to 
 163 Ibs. each horse; and although the speed was not particularly entered, it 
 could not be less than at a rate of 2J miles per hour. As these experiments 
 were fairly made, and by horses of the common breed used by farmers, and 
 upon ploughs from various counties, the numbers may be considered as a 
 pretty accurate measure of the force actually exerted by horses at the plough, 
 and which they are enabled to do without injury for many weeks ; but it 
 should be remembered, that if these horses had been put out of their usual 
 pace, the result would have been very different. The meat) power of the 
 draught horse, deduced from the above-mentioned formula, exceeds the calcu- 
 lated power from the highest formula of Mr. Lesslie, and, we may add, that of 
 Mr. Tredgold. The latter gentleman has, however, furnished us with a most 
 valuable table, showing the maximum quantity of labour that a horse of average 
 strength is capable of performing, at different velocities, in drawing boats on 
 canals, and carriages on railways and turnpike roads. 
 
 
 
 
 Useful effect of one horse working one day, 
 
 
 Duration of the 
 
 
 in tuns, drawn one mile. 
 
 Velocity in 
 milts per hour. 
 
 day's work at 
 the preceding 
 velocity. 
 
 ?orce of trac- 
 tion in pounds. 
 
 On a canal. 
 
 On a level, 
 railway. 
 
 On a good level 
 turnpike road 
 
 Mil. 8. 
 
 Hours; 
 
 Lbs. 
 
 Tons. 
 
 Tons. 
 
 Tons. 
 
 2| 
 
 11 J 
 
 834 
 
 520 
 
 115 
 
 14 
 
 3 
 
 8 
 
 83 
 
 
 243 
 
 92 
 
 12 
 
 Z\ 
 
 H 
 
 83! 
 
 
 153 
 
 82 
 
 10 
 
 4 
 
 4}. 
 
 83; 
 
 
 102 
 
 72 
 
 9 
 
 5 
 
 si 
 
 Q'*' 
 
 
 52 
 
 57 
 
 72 
 
 6 
 
 2 
 
 8S 
 
 
 30 
 
 48 
 
 6.0 
 
 7 
 
 M 
 
 83 
 
 
 19 
 
 41 
 
 5.1 
 
 8 
 
 u 
 
 8:4' 
 
 128 
 
 36 
 
 4.5 
 
 9 
 
 o-o 
 
 83* 
 
 9.0 
 
 32 
 
 4.0 
 
 10 
 
 of 
 
 83 
 
 6.6 
 
 288 
 
 3.6 
 
 It will be seen by the foregoing, that the loss of effect is very considerable 
 upon increasing the velocity of a horse beyond that of 2J miles per hour ; this 
 speed has, indeed, been considered by all writers on the subject, as the fittest 
 for obtaining the greatest quantity of power from horses, as they can exert it 
 without being overstrained, throughout a whole day's work. At the highest 
 speed of 10 miles per hour, which is that of many of our stage-coach horses, 
 it will be observed that they cannot keep up this pace for more than thr e 
 quarters of an hour ; that is, 7J miles per day is as much as they can perform 
 without being soon exhausted. The amount of useful effect assigned by Mr. 
 Tredgold for this day's work of only three quarters of an hour, is 3.6 tons 
 drawn one mile, which is equivalent to nearly half a ton drawn 7$ miles. Now 
 the weight of an ordinary stage-coach and its load is about four times the li-st
 
 708 HORSE-SHOES. 
 
 mentioned quantity, or two tons ; consequently we perceive the necessity of 
 four horses being employed, as is customary, to do the work at that high 
 velocity which one horse would easily perform at the velocity of 2| miles per 
 hour. In stating the power of steam engines, it is usual to say the number of 
 horses' power it exerts, each horse power being estimated as equivalent to 
 raising 33,000 Ibs. one foot high per minute. See the article STEAM. 
 
 HORSE-SHOES. Curved pieces of iron, made to fit accurately the horny 
 hoofs of horses, to which they are nailed in a peculiar manner ; the use of the 
 shoes being to preserve the hoofs from the destructive effect that would take 
 place by their collision and friction against the hard substances of which our 
 common roads are formed. It is a common rule to make the shoes three times 
 as thick at the toes as at the heels, so that by this means the frog (which is a 
 central projection in the foot) may come down to the ground. The nails are 
 all placed forward, four on each side, but not approaching too near the heels, 
 and are countersunk in conical or wedge-shaped holes. For horses which go 
 in shafts, or are used in hunting, it is usual to make shoes with only one heel, 
 which should be outward. The horse's heel is rather lowered on that side, and 
 the inner heel of the shoe somewhat thickened, so as to balance and bear 
 equally. The best breadth for the shoe of a medium-sized horse is said to be 
 one inch at the toe, and three quarters at the heel; the weight, about eighteen or 
 twenty ounces. In order to fit the shoe without causing the horse to stand too 
 much on his heels, the under part of the crust, or wall of the hoof, is pared 
 away to receive the excess of thickness in front; for the bottom of the shoe, it is 
 generally conceived, ought to be perfectly flat, without any stubbings or calk- 
 ings in front. Paring away the heels is a most destructive practice, except in 
 case of absolute excrescence in those parts ; nor should the bars (or diagonal 
 ridges) that extend from the heels to the frog, or central projection, ever be cut 
 more than is absolutely necessary for the purpose of keeping them in a clean 
 and healthy state. A good open heel is the indication of a powerful foot ; 
 hence the sides of shoes ought not to be much contracted ; when the heels are 
 tender, what is called a bar-shoe ought to be applied. On the frog the horse 
 chiefly depends for a spring or resistance at the bottom of the foot : if this part 
 does not touch the ground, the whole motion will be derived from the upper 
 parts of the limb, and a very uneasy gait will inevitably follow : this points 
 out the propriety of leaving it fully at liberty to come in contact with the 
 ground. Mr. Colman, the distinguished professor of the Veterinary College, 
 says, that " no animal, nor any part of the animal, can be preserved in health, 
 where the natural functions are perverted ; and he strongly urges the necessity 
 of some great alterations being made in the practice of shoeing horses, so that a 
 portion of the weight of the animal may be sustained by the frog, which, from 
 its central projection in the foot, and the tough elastic nature of its substance, 
 was evidently designed for that purpose. In a recent paper on the same subject, 
 from the pen of Mr. Cherry, that gentleman entirely coincides with the author 
 just quoted, and considers that not only the frog, but the sole also, (which is that 
 horny portion of the foot between the frog and the exterior wall or crust of the 
 hoof,) should be made to sustain its proportion of the superincumbent weight; 
 and, he adds, that any treatment which deprives these parts of pressure, must, 
 according to true physiological principles, induce disease. It is evident that a 
 horse in a state of nature presses with the whole surface of his foot upon the 
 ground, the rim of the hoof, by its angular projection, preventing slipping, and 
 the frog serving as a cushion to prevent any ill effects from violent concussion. 
 By the ordinary mode of shoeing, however, the whole weight of the horse is 
 thrown upon this angular rim, or wall of the hoof, contrary to the designs of 
 Providence, and the plainest dictates of common sense ; for, being shod with a 
 thick bar of iron on this part, the foot is thereby lifted up, forming a hollow 
 cavity within the shoe, which, as Mr. Cherry says, " deprives the foot of that 
 support which it would otherwise receive from the earth, and greatly deranges 
 the mechanisin of the whole foot." The same author p oceeds to observe, that 
 the feet of faim horses, though usually in tl.at condition termed a state of 
 neglect, will, upon examination, be found generally " moist, cool, and healthy j
 
 HORSE-SHOEING. 709 
 
 while a foot kept clean, is dry, brittle, and full of cracks;" which is evidently 
 owing to the shoes of the former being usually clogged with earth, by which the 
 whole surface of the foot is made to sustain the pressure, instead of the mere 
 rim ; the earth likewise contributes to the healthful condition of the feet by a 
 supply of moisture for absorption. " Perhaps," Mr. Cherry continues, " it may 
 be possible to prepare some compressible and adhesive substance to fill up the 
 cavity after the shoe is on, which shall give support to the whole foot, yet 
 without impeding the full action of its elastic properties." 
 
 The late Mr. Robert Uickenson entertaining the same views of the subject 
 as the above-mentioned eminent authorities, took out a patent for some 
 improvements in horse-shoes, of which the following is a description. In the 
 annexed engraving, Fig. 1 exhibits a plan, and Fir/. 2 a side view of the im- 
 proved shoe as fitted on to the foot. Fig. 3 represents the ordinary English 
 
 Fig. 1. Fig. 2. 
 
 mode of shoeing, which has been here introduced merely by way of contrast. 
 By Mr. Dickenson's plan, a piece of stout leather is cut to cover the whole 
 under surface of the hoof; and on this is rivetted a plate of iron of a shape 
 and magnitude to cover the frog, which it is designed to protect against injury 
 in travelling upon hard stony roads ; under the leather covering is stuffed into 
 the hollow of the hoof a quantity of sponge, and the shoe being nailed on 
 through the leather, the whole is thus simply and permanently secured until the 
 iron shoe is worn out, the leather lasting out several iron shoes, owing to its 
 compressible elastic nature. The absorbent nature of the sponge keeps the foot 
 always moist, and the whole surface of it is brought to sustain the pressure. It 
 will be observed that the iron rim of Mr. Dickenson's shoe is curved after the 
 French manner, as shown in Fig. 2. From the rapid action of a horse's foot 
 it is not easy to discover the precise kind of motion which he makes in 
 stepping out and relieving his foot for the next step ; but it is ascertained to be 
 a rolling from heel to toe. Now the flat shoe represented in Fig. 3, which is 
 the common English form, evidently presents an obstruction to this particular 
 action ; frequent stumbling from an unnatural effort to overcome the difficulty, 
 and a straining of the muscles and tendons, to which nature has assigned due 
 limits, seem to be the unavoidable consequences. On the contrary, the French 
 shoe is so curved as to conform to the natural figure of the hoof, and consequently 
 presents no impediment to the natural action of the foot; to this circum- 
 stance may therefore probably be attributed the welt- known superior sure- 
 footedness of French horses. The impropriety of a perfectly flat shoe is 
 manifested by the toe part being generally worn down as thin as a sixpence, 
 while the sides are frequently half an inch thick. 
 
 With the view of obviating the presumed necessity of fastening the iron 
 shoes to horses by nailing them to the hoofs, Mr. William Percival, of 
 Knightsbridge, took out a patent in 1828 for a mode of securing them to 
 horses' feet by means of straps or sandals. In the engraving on the following 
 page, Fig. 1 represents a plan of the shoe, which is of the kind called the frog- 
 bar shoe ; in the front is a tongue a, turning upon a hinge, and having two slits 
 in it to receive the band or strap, and keep it in its place ; at the extremities of 
 the frog-bar are two double loops or rings, bb, turning upon hinges or holes in 
 the ends of the bar. Fig. 2 shows the shoe attached to the foot of a horse, 
 the strap c, of elastic web, is passed through the lowermost of the two rings ; 
 through the lowermost slit in the tongue ; through the lowermost ring on the 
 opposite side ; then through the uppermost slit in the tongue ; and afterwards 
 4 x
 
 710 
 
 HORSE-SUOEING. 
 
 through the buckle on the other end of the strap, and itrawn tight. The strap d 
 >i passed through the uppermost of the two rings on one side, and over a pad e, 
 
 Fig. 2. 
 
 placed under the heel of the animal, then through the uppermost rings on the 
 opposite side, over a pad f, and secured by a buckle on the other end of the strap. 
 Mr. Benjamin Rotch, the barrister, has distinguished himself by his atten- 
 tion to this subject, which so intimately concerns not only the welfare, but the 
 utility of the most interesting and valuable animal in the creation. In 1810 he 
 had a patent for a flexible elastic horse-shoe; and in 1830 a second patent, 
 entitled " improved guards or protectors for horses' legs and feet under certain 
 circumstances ;" and as this patent may be regarded as an improvement upon 
 the former, we shall notice the latest only. These " improved guards" are to 
 be made of caoutchouc, or Indian rubber ; when one is to be applied to a horse's 
 foot, the neck is to be cut from a caoutchouc bottle, which is then to be softened 
 by immersion in hot water, and drawn over a block made of the shape and size of 
 the foot for which it is intended. On this block it is permitted to cool, when it will 
 retain its shape ; and by its elasticity it will adhere to the horse's foot when drawn 
 on to it. On the exterior of this shoe is to be applied a sole of sheet-iron, made 
 of sufficient size to allow of its edges being cut and turned up round the hoof, to 
 keep it on the foot ; but it is also fastened to the Indian rubber by means of rivets 
 with very broad and thin heads; and to the sheet-iron sole is to be fastened, if re- 
 quired, horse-shoes of the usual forms. In the preparation of the guards for the 
 legs of horses, botli the top and the bottom of an Indian rubber bottle are to be 
 cut off, and after being soaked, 
 softened, stretched on a block, 
 formed, and cooled, is to be ap- 
 plied to such of the legs or knet-s 
 of the animal as require protection. 
 For the purpose of ensuring a 
 perfect fit to a horse's foot at a 
 small expense, Mr. Dudley, of 
 King-street, Soho, took out a 
 patent in 1823 for a horse-shoe 
 of t'ow^-iron, an under side, or 
 ground view of which is repre- 
 sented in the annexed cvit. After 
 being cast to the precise model 
 of the foot taken from a plaster 
 cast, it undergoes that process of 
 annealing (now so well under- 
 stood and nractised) by which it 
 is rendered so soft and malleable 
 as not to be liable to break by 
 concussion in travelling over the 
 loughest pavement. At A A is
 
 HOT-PRESSING. 711 
 
 a raised border, or cord, the use of which is to strengthen the inner vein or 
 webj also to prevent pieces of flint or gravel, &c. from being forced on the sole 
 of the foot, which frequently happens with the common shoe, as that affords no 
 such protection. This form is also considered by the patentee to give great 
 security to the tread of the horse, either over pavement, road, or field. At the 
 ends B of the shoe, concavities are formed, which become stops, equal in effect 
 to the rough shoeing, or turning up at the heel, without altering the even 
 bearing of the horse's feet upon the ground, so essential to his true motions, 
 and the security of both horse and rider. If proper attention be paid to the 
 manufacture of these shoes, especially the annealing process, they would prove 
 of great utility, as they can be quickly made of any size, figure, or pattern, 
 exactly suited to the feet of any particular horse, and supplied in any quantity, 
 all precisely alike. 
 
 HOSE. A term given to a flexible tube attached to hydraulic engines, for 
 conveying water or other fluid to any required point. Fire-engine hose was 
 originally made of leather sewed up, which being very liable to get out of 
 order, many attempts have been made to discover some cheaper and more 
 durable material. Flax, or hempen hose, woven without a seam, have long 
 been employed on the continent ; and the Society of Arts, in London, have for 
 years past been in the habit of offering a reward for its production in this 
 countiy. According to Beckmann, however, a manufactory for this article 
 existed in the neighbourhood of Bethnal-green, towards the end of the eigh- 
 teenth century, but the speculation did not succeed. One of the London 
 Insurance Offices a few years since imported a length of the best hempen hose 
 from the continent, but it did not answer, being found not near so convenient 
 in use, nor so durable as leather. Mr. Hancock has manufactured some hose 
 of canvas, with layers of caoutchouc between them, which has been found 
 useful in many cases where leather would have been ineligible. Leather hose 
 was formerly made by sewing with strong twine, and subsequently with copper 
 wire ; neither of these methods, however, was found sufficient to keep the hose 
 constantly water-tight, and all the best hose now made is not sewn at all, but 
 rivetted. The fire-engine establishments of London and Edinburgh make their 
 own hose ; the method adopted by them is as follows : the leather, levelled to a 
 proper thickness, and in lengths of about four feet, is gauged to the breadth 
 required ; holes are punched, four at a time, all down the sides, by means of a 
 small press. The ends of each piece of leather are cut crosswise, at an angle of 
 about 37 ; the different pieces of leather necessary to form a length of hose 
 (forty feet) are then rivetted together at the ends. The length of leather thus 
 formed is then placed on a bench, and a long flat iron bar laid upon it ; the 
 rivets are next put into the holes on one side of the leather, and the holes on 
 the other side brought over them ; washers are then placed on the rivets, and 
 struck down with a hollow punch. The points of the rivets are then hammered 
 down over the washers ; this done, the bar of iron is shifted along, and the 
 operation continued until the whole length is completed. A piece of rivetted 
 hose made in this manner has been found capable of resisting a column of 
 water nearly 500 feet high. The following composition has been found most 
 efficacious for the preservation of leather hose, viz. one gallon of neat's-foot oil, 
 two pounds of tallow, and a quarter of a pound of bees'-wax, melted together, 
 and applied warm, the hose being in a moist state. 
 
 HOT-BEDS, in Gardening, are beds made with fresh horse dung, or tanner's 
 bark, and covered with glasses to defend them from inclement weather. 
 
 HOT-HOUSE. A garden erection, similar to a green-house, employed either 
 for forcing plants, or for the training of exotics, provided with a stove or flue 
 for the diffusion of artificial heat, and the means of duly regulating it. 
 
 HOT-PRESSING is, strictly speaking, the art of applying heat in conjunction 
 with mechanical pressure ; but it is generally understood to mean the employ- 
 ment of that process to paper, linen, and similar fabrics, by which they acquire 
 a smooth and glossy surface; and the mode of operating is as follows. A number 
 of stout cast-iron plates are heated in an oven constructed for the purpose ; 
 when they have acquired the proper temperature, they are taken out ai>4 put
 
 712 
 
 HOT-PRESSING. 
 
 into a screw-press, in alternate layers, with the goods to be pressed, in the 
 manner shown in the subjoined engraving; and when paper is the material to 
 be hot-pressed, in addition to the heated iron plates, a highly-glazed pasteboard 
 is put alternately between every sheet of paper ; the hard polished surfaces of 
 the pasteboards, in consequence, produce upon the soft and spongy sheets of 
 paper that smooth and elegant appearance by which hot-pressed paper is 
 distinguished. The great inconvenience and labour attending the drawing of 
 the heavy hot iron plates from the oven, then carrying them to, and lifting 
 them into the proper situations in the press, struck the editor of this work as 
 susceptible of amendment. With this view of the subject he devised a press 
 from which the plates never required removal, and wherein they are constantly 
 kept at the required temperature by hot air from a small furnace beneath. By 
 this arrangement, fuel, time, labour, and space, may be saved. The press itself, 
 as shown in the subjoined elevation, does not materially differ from those in 
 
 I 
 
 general use. The bed b, and the head-piece c, must be of the most solid and 
 tenacious materials; these parts are braced and held together by four stout cast- 
 iron hollow columns or cylinders dd, having a longitudinal slot montice througnout 
 their length for the reception of the corner pieces of the plates as shown by the
 
 HYDRATES. 713 
 
 annexed diagram, which exhibits a plan of 
 a plate, with its four corner pieces inserted 
 in the slots of the cylindrical columns, the 
 dark central parts of each being the space 
 where the hot air acts upon the corners of 
 the plates ; the heat from which, by the 
 conducting power of the metal, is quickly 
 communicated throughout. A series of 
 these plates is shown in the elevation, 
 attached to each other by means of short pieces of chain, which allow the 
 plates to be pressed nearly close together, or the drawing of them further apart 
 by the action of the screw e. The ends or corner pieces of the plates are 
 shown by dotted lines, as inserted in the hollow columns. The furnace or 
 fire-place is placed underneath at /; at g is the ash-pit, and at h is the hot-air 
 chamber. The bars of the furnace are made hollow, which, being heated by 
 the burning fuel, the cold air rushes through them, abstracting caloric in its 
 passage, and is received at the back into the hot-air chamber, which lines the 
 'sides, top, and part of the back of the fire. The air in this chamber derives a 
 great increase of heat by radiation through the iron partition which separates 
 it from the fire. The hot-air chamber is of course kept closed, the front plate 
 being merely removed in the drawing to show its form ; a sliding plate should 
 be made to fit the front ends of the hollow bars, by which the quantity of un- 
 admitted may be lessened or augmented; and by a due attention to the 
 management of the fire, the heat may easily be regulated with sufficient 
 exactness for the nature of the operation. The hot-air is conducted from the 
 chamber h, by means of four iron pipes, and to each of the cylindrical pillars ; 
 two of these are shown by the dotted lines ii. As the hot-air issues from these 
 pipes it ascends the columns, impinging in its progress upon the ends of the 
 plates, and heating them to the degree required for hot-pressing. For fire-proof 
 houses, see the article FIRE. 
 
 HOUSE. A building constructed for the purpose of habitation. The recent 
 improvements made in the construction of the constituent parts of houses, 
 such as windows, shutters, roofs, chimneys, &c. we have given under their 
 respective heads; and as it would be trespassing far beyond the assigned limits 
 of this work to introduce into it a regular treatise on the subject of house- 
 building, it is with satisfaction that we can recommend to the attention of the 
 inquiring reader, Nichokms Practical Builder, in which the modern practice 
 of this most important art is clearly developed in all its details. 
 
 HOWITZER. A kind of artillery between a cannon and a mortar ; being 
 longer than a mortar and shorter than a cannon, and from that circumstance 
 adapted to throw either shot or shells ; it is usually mounted as a cannon upon 
 a travelling carriage. 
 
 HULK. A large vessel moored and fitted up for the purpose of taking out 
 or putting in the masts of other ships, and for various other purposes that may be 
 required in nautical affairs. They are sometimes employed to contain stores, 
 and sometimes for the secure detention of prisoners. 
 
 HUNGARY WATER is made by distilling, in a water bath, two pounds of 
 fresh-gathered flowers of rosemary, with two quarts of the rectified spirit of wine. 
 
 HURDLES. A light fence of open rails, made in convenient detached 
 pieces, for fixing separately in the ground by stakes or prongs ; the hurdles 
 being afterwards tied together, end to end, constitute a continued fence. Until 
 recently they were almost wholly made of split oak or other tough wood ; but 
 now, from the low price of iron and the facilities of manufacturing, iron hurdles 
 are extensively used. 
 
 HYACINTH. A sub-species of pyramidal zircon. Colours red, brown, 
 green, and grey, and more rarely yellow. The darker varieties are deprived of 
 their colour by heat, a fact of which artists avail themselves to make zircon 
 resemble diamond. It is esteemed by lapidaries as one of the gems. 
 
 HYDRATES. Compounds, in definite proportions, of metallic oxide* 
 with water.
 
 711 HYDRAULICS. 
 
 HYDRAULICS is the term applied to that collection of facts which 
 describe the phenomena of fluids in motion. In treating of hydrostatics, we 
 have shown that fluids press in all directions, and that the pressure is as the 
 depth : hence if a small hole be made in the bottom or side of a vessel, the 
 velocity with which the water will issue will depend on the pressure above it, 
 that is on the depth of the hole. If a vessel be kept quite full of water, so 
 that the height may remain fixed, and holes be made at various depths beneath 
 the surface, it will be found that the velocity of the issuing fluid will be as 
 the square root of the depth of the hole. Hence to produce the velocities 
 1, 2, 3, 4, the corresponding depths must be 1,4, 9, 16, which are the squares 
 of the velocities. To produce a double velocity we see a fourfold pressure is 
 required. To explain this, we must bear in mind that when the velocity is 
 doubled, a double quantity of fluid must issue, and as this issues with a double 
 velocity, the power requisite to produce this effect must be four times greater. 
 In like manner three times the quantity of fluid issuing with three times the 
 velocity, will require a power nine times greater, and so on. This law, it will 
 be seen, is coincident with that of bodies falling in free space by the power of 
 gravity. To produce a double velocity, a fourfold height is required ; to 
 produce a threefold velocity, a ninefold height is required. Thus it appears if 
 a particle of water were to fall unresisted from the surface of the fluid to the 
 orifice, it would acquire the same velocity as the issuing water actually exhibits. 
 If a small tube were attached to the orifice and turned upwards, the water 
 would ascend to a height equal to its source, were it not for the resistance of 
 the air, and the friction against the sides of the tube. The absolute velocity of 
 the fluid cannot be ascertained by calculation alone, and must therefore depend 
 partly upon experiment. In the annexed cut it will be seen 
 that the particles of water, on account of the equality of pres- 
 sure on all sides, will so far interfere with each other's motion, 
 that the stream will be contracted a little below the orifice. 
 This contracted part was called by Sir I. Newton, who first 
 observed it, the vena contracta, or contracted vein ; and it 
 magnitude compared with that of the orifice, was found to be 
 as one to the square root of two nearly, or as 1000 to 1414. 
 Now the velocity found by the rule we have before stated is 
 the velocity at the vena contracta. But as the velocity of fluids in a channel varying 
 in diameter is inversely as its sectional area, the velocity at the orifice isless than at 
 the vena contracta in the proportion of 1 to 2, or as before stated, as 1000 to 1414. 
 Hence it follows, that the velocity at the orifice is that which a body would 
 acquire in falling through half the altitude of the fluid above the orifice. From 
 this theorem we may easily calculate the quantity of water that would escape 
 through a given orifice in any time. Let a cistern or other vessel be six feet 
 high, and kept full of water, and it be required to ascertain what quantity of 
 water would run out through a hole a quarter of an inch area, near the bottom, 
 in ten minutes. By the laws of mechanics we find that the velocity acquired 
 by a body falling through half the height, viz. three feet, is fourteen feet in a 
 second ; if, then, we multiply the area of the orifice, namely a quarter of an 
 inch by 14, and then by 600, the number of seconds in ten minutes, we shall 
 obtain 2100 cubic inches, or seven gallons and a half as the issuing quantity. 
 The quantity of water that issues through a hole in the bottom of a vessel 
 may be varied by inserting small tubes in the holes. Thus it was found by 
 Venturi that when a small tube was applied whose length was equal to twice 
 the diameter of the hole, it discharged eighty-two quarts of water in one hun- 
 dred seconds, while the hole without the pipe discharged but sixty-two quarts 
 in the same time. If the pipe, instead of being level at its top with the bottom 
 of the vessel, projects some distance within it, it diminishes the discharge to 
 less than would occur with the simple hole. In the preceding view of the 
 velocity of discharge we have considered the surface of the water as maintaining 
 the same level; but in ascertaining the time in which a vessel would empty 
 itself through a given hole, it must be evident that attention must be given to 
 the varying depth of the fluid. If the fluid flow with a velocity of sixteen feet
 
 HYDRAULICS. 
 
 715 
 
 per second, when the vessel is full, it will flow with a velocity of eight only 
 when the vessel has discharged three-fourths of its contents, that is, when the 
 height is reduced to a quarter of its original altitude. If it be considered that 
 the pressure is continually diminishing with the flow of water, it will easily be 
 conceived that the quantity of water that will flow out will be only one half of 
 that which would be discharged if the vessel were kept full. In this case the 
 surface would sink with a gradually retarded motion ; and if the sides of the 
 vessel were marked with a series of numbers representing the hours of the day, 
 it would form the clepsydra, or water-clock of the ancients, the surface of the 
 water being the index. The same law applies to the conveyance of water 
 through valleys in pipes, as we have shown to exist in the issue of water from 
 holes in the bottoms of vessels. If it were required to convey water across a 
 valley of considerable depth, the pipe employed must have great strength to 
 withstand the pressure arising from the height of its source. If a small hole 
 were made in the pipe the height to which the water would B 
 
 ascend, would indicate the great pressure existing. In 
 this way various fountains may be constructed. In 
 conveying water from a higher to a lower level, when 
 it is inconvenient to form a channel, the syphon may be 
 employed. This consists of a bent tube, A, B, C, having a 
 shorter and a longer leg. The shorter leg is placed in the 
 water to be removed, and the air being then drawn out 
 through a tube communicating with the longer leg, or by 
 means of a stop-cock, the water will rise in the shorter leg 
 by the pressure of the external air, and going over the bend 
 of the tube, will run in a continuous stream as long as the level 
 of the water at A is lower than that at C. In the flowing of water through 
 holes in the sides of vessels, the same proportions obtain as in the discharge 
 through holes in the bottom. If A B repre- 
 sent a vessel kept full of water, and holes 
 be made in the sides at a b c, the water 
 will be found to spout to different distances, 
 and yield different quantities according to 
 the depth of the orifice. Thus the quantities 
 of water that would flow from a and c would 
 be as 1 to 2, because their depth are as 1 to 
 4 ; and from any other hole the quantity 
 would still be as the square root of its depth. 
 If a semicircle be imagined to stand with 
 its diameter on one side of the vessel, y 
 and lines be drawn perpendicular to the 
 diameter, as a d, b e, and cf, these lines will show the proportionate distances 
 to which the fluid will spout. The vena contracta, in this case, being very near 
 the vessel, the velocity of projection at this point must be considered as the true 
 velocity ; and this is equal to that acquired by a body falling through the whole 
 height of the fluid above the hole. The curve c C described by the water, is a 
 parabola, whose vertex is at c : and by a property of the parabola, B C, the 
 distance to which the fluid spouts from B is equal to twice the square root of 
 (Be multiplied by c A) which is equal to twice c f. In a vacuum, therefore, 
 double the lines a d, eb, ef, represent the distances to which the fluid would 
 spout. If the water, instead of flowing through a very small hole, had to flow 
 through a long slit, the velocity would differ at the top and bottom, and in this 
 case, the point which may be taken as that of the mean velocity, is two-thirds 
 of that at the lowest point. In the action of liquids, as in solids, a considerable 
 quantity of power is constantly consumed in friction ; hence the velocity of 
 water through pipes, or jets is considerably diminished, as is also the motion of 
 rivers, a circumstance which is essentially beneficial to navigation ; for otherwise, 
 the velocity of the water, continually increasing in its fall, would become so 
 great as to be unmanageable. For further information in this science, con- 
 sult the articles, PUMPS, WATER-WHEELS, and the various hydraulic machines
 
 716 
 
 HYDRAULIC ENGINES. 
 
 HYDRAULIC ENGINES, are all kinds of machines which either 
 receive motion from the weight or impulse of water, or are employed in raising 
 it ; but the term is sometimes used to denote a machine which in its general con- 
 struction resembles a steam engine, but the piston of which is impelled by the 
 pressure of a column or head of water. The annexed figure is a representation 
 of a statical hydraulic engine erected by Mr. Man waring, at Messrs. Cook & 
 
 Co.'s Alum Works, near Whitby. A is the pipe by which the supply of water 
 is brought from a head 170 feet above the engine ; B is a vessel containing air, 
 the continual elastic pressure of which prevents the blow that would otherwise 
 be occasioned by the descent of the water ; c is a throttle valve ; d d is a 
 hollow open cylinder, working within an exterior one, and closely applied to 
 that cylinder, at the parts e e e e, but elsewhere leaving a vacant space between 
 the two cylinders for the reception of the water h h are packings, in order f ()
 
 HYDRAULIC ENGINES. 717 
 
 prevent tae escape of the water between the two cylinders ; and * > are adjust- 
 ing screws, to tighten the packing in proportion as it is worn away ; //are two 
 passages that lead into the upper and lower ends of the pipe g, in which the 
 piston w works. When the cylinder d d is in the position represented in the 
 cut, the communication is open by means of the upper pipe /, for the water to 
 flow into the pipe^p above the piston w ; at the same time the passage is open for 
 the water in the cylinder </, below the piston, to flow out through the lower pipe/ 
 and through the lower part of the open cylinder d, into the pipe x, which is some- 
 what more than 30 feet long, and terminates in a cistern of water. There is there- 
 fore, above the piston tv, a hydrostatic pressure equal to 1 70 feet of water, and below 
 it a partial vacuum ; the piston consequently descends to the bottom of the pipe 
 ff. By the time that it has arrived in this position the cylinder d will also 
 have descended so far as to have opened the communication between the 
 entering water and the lower pipe /, and to have shut off its communication 
 with the upper pipe /; the hydrostatic pressure is therefore transferred to the 
 under part of the piston, which consequently rises, while the water above the 
 piston pours into the top of the cylinder d, and escapes through the pipe x. 
 The alternate motion of the slide or cylinder d is thus effected. The rod of 
 the piston pp is attached at its top to one end of the beam ; at the other end of 
 the beam is a rod, terminating below in the crank m ; the oscillating motion of 
 this crank is transferred, by means of the connecting bar /, to the axis k, on 
 which is placed the curved tooth or cam n; the latter is enclosed within the 
 rectangular frame (or cam box) j, and, being movable in a horizontal position, 
 is consequently made to perform a backward and forward motion, by the cam 
 passing first on one and then on the other side of the box. To the outside 
 of the box are fixed two guide bars, supported on thin bearings o o, the con- 
 necting rod p at one end to the guide bar, and at the other end to the arm q of 
 a bent lever, having for its fulcrum the pivot r ; the other end of the lever is 
 forked, and embraces the pipe x ; one of these forks s is connected with the 
 lower end of the upright rod t, and the other fork is connected with a similar 
 rod. These rods are fastened at top to the two ends of a cross bar, to the middle 
 of which is fixed the rod u, which works in the stuffing box v, and gives motion 
 to the slide d. The slide remains stationary nearly half a stroke of the piston, 
 in order to allow the water to act with its full force ; and this is effected by its 
 being necessary for the cam, after it has moved the box in one direction, to per- 
 form about a quarter of a revolution before it can act on the opposite side of 
 the box. The reason for making the passages //as large as represented, is to 
 diminish as much as possible the friction of the water, which otherwise would 
 retard the motion of the piston. Engines upon the principle of the above 
 have been long known, and some were erected in Cornwall more than sixty years 
 ago. Some of the earlier attempts to construct hydraulic engines upon the 
 principle of the steam engine failed, because water, not being elastic, could not 
 be made to carry the piston onwards a little, so as to close one set of valves, 
 and open the other. In an engine erected by Mr. Trevethick, about thirty years 
 
 ra tumbler connected with the valve gear performs the office instead of 
 expansive force of the steam at the end of the stroke. This is now, how- 
 ever, much better effected by the introduction of an air vessel similar to that 
 shown in Mr. Manwaring's engine, which has besides, the effect of preventing a 
 concussion at the end of each stroke. 
 
 Mr. Seidler has taken out a patent for an engine, which he calls a hydraulic 
 engine, but which we think should rather be styled a pneumatic engine, as raising 
 water is merely one of the objects to which he proposes to apply the principle, 
 which is that of employing compressed air as a medium for transmitting the power 
 of any prime mover to machinery at a distance, or in situations where the ordi- 
 nary modes of connexion would be inconvenient or impracticable. The principle 
 itself is very old, having been employed by Papin as noticed under the word 
 AIR. The engraving on the next page represents the application of the prin- 
 ciple to the purpose of raising water from any depth, and through straight or 
 circuitous passages, a a represents a cylinder, in which a piston, p, works by 
 means of a steam engine .or other power, hg are copper pipes, forming a 
 4 y
 
 718 
 
 HYDRAULIC MACHINES. 
 
 communication between the cylin- 
 der a a and the cast iron tank or 
 vessel k I ; o o is a large delivery 
 pipe, of copper or other material, 
 through which the water is conveyed 
 from the tank, and discharged; at 
 r is an air-tight partition, dividing 
 the tank into two parts, k and I; 
 and s s are two air-tight partitions, 
 proceeding from the top nearly to 
 the bottom of the tank ; e is a two- 
 way cock, for effecting an alternate 
 communication between a and k, 
 and between a and /. The other 
 parts of the machine will be ex- 
 plained in the following description 
 of its action. Suppose the piston p 
 to be raised from its present posi- 
 tion in the cylinder, the air above 
 it will be conveyed through the 
 valve c, and the pipe h into the 
 vessel k, and force the water con- 
 tained therein through the valve t, 
 up the pipe oo, while air will be 
 supplied to the cylinder below the 
 piston through the valve b. When 
 the piston descends, the air will 
 pass from the lower to the upper 
 side of it by the valve d; this 
 operation is to be continued till 
 all the water is forced out of k, 
 when the two-way cock e must be 
 turned to change the communication 
 through the valve c to the pipes r;, 
 and the part of the tank I at the 
 ^ame time; the air which was 
 forced into k will be permitted to 
 re-enter the cylinder through the 
 pipe w, as shown by the dotted lines 
 iu the cock e, so that no air will be 
 required to enter at the valve 6 
 except at the commencement of 
 the operation, or when any of the 
 air is discharged with the water, or 
 otherwise dissipated. When the 
 air is liberated from the receptacle 
 4 of the tank, it will be again filled 
 with water through the valve m, the 
 valve i being shut by the pressure of 
 the water in the pipe o o. During 
 this time, the water in / will be 
 forced through the valve u ; in the 
 same manner from /r, through the 
 valve i. The cock e to be turned by the hand or by the machinery, after 
 such a number of strokes of the piston in the cylinder as is sufficient to displace 
 the water in one division of the tank. For machines for raising water, see 
 PUMPS and WATER WOHKS. 
 
 HYDRAULIC MACHINES. Under this head we propose to notice 
 various machines which are at times employed in lieu of pumps for raising 
 water, or which have been p-oposed for that purpose. The most simple, as
 
 HYDRAULIC MACHINES. 719 
 
 well, perhaps, as the most ancient (next to the bucket and windlass), istheCoclilion 
 Water Screw of Archimedes. It consists of a cylinder of wood, of about a foot 
 in diameter, and of any length at pleasure, and on this a leaden pipe of any 
 bore is wound from the bottom to the top. When the bottom of the cylinder 
 revolves in the water (by means of a common winch handle at top, and of a pintle 
 in the centre of its base, which rests in a bore or step for that purpose below,) 
 the reclined portion, as shown in the following figure, occasions the water to 
 enter the mouth of the pipe, and as by its gravity it naturally occupies the 
 lowest part of the pipe, whilst by the revolution of the cylinder the orifice of 
 the pij>e is gradually elevated, and a different portion of the pipe occupies the 
 lowest position, the water advances progressively along the pipe, always occupy- 
 ing the lowest portion of the bends or turns of the pipe, until it at length reaches 
 
 he top of the cylinder, and is discharged into a vessel. This, however, raises 
 but a small quantity, although the height may be indefinite ; therefore, when this 
 machine is used, it will be found eligible to cover the whole surface of the 
 cylinder with a number of pipes laid close together, or, what is a better method, 
 and is that which is usually adopted, is to wind a number of spiral feathers 
 round the cylinder, standing out from it at right angles like the square threads 
 of a screw, and covering these feathers with an exterior case closely fitting 
 in every part. These machines were formerly in great repute ; but, owing 
 to their liability to become choked with weeds and mud, they are not oftea 
 employed at present. 
 
 the figure on page 720 represents what is called the horn-drum ; it is formed 
 of a number of segments passing from the circumference of a large flat cylinder 
 to its centre. This affords an easy mode of raising water. The mouths or 
 scoops by turns dip into the water, and as they rise cause it to pass up the horn 
 or segment, until it is discharged into a trough placed under the end of the 
 axis, which is hollow, and is formed into a number of separate compartments, 
 each communicating with one of the horns or segments. One disadvantage 
 of this machine is that it raises water no higher than the axle, and is therefore 
 only applicable in situations where the water is required to be raised to an 
 inconsiderable height. This circumstance renders it necessary to construct it of 
 double the diameter of wheels that discharge their water at their tops. This 
 machine, however, might be altered to do so likewise, by confining the scoops 
 to near the periphery of the wheel, and discharging them by means of lateral 
 valves, to be opened by coming against a contrivance fixed at the top of the
 
 rso 
 
 HYDRAULIC MACHINES. 
 
 wheel for that purpose. The Persian wheel, represented in the following engrav- 
 ing, is free from the defect of the last described. In this machine a number 
 of rectangular buckets aaaa are hung upon strong pins bbbb, fixed in 
 the side of the rim, the diameter of which must somewhat exceed the 
 height to which the water is required to be raised. As the wheel turns, the 
 buckets on the right hand descend into the water, where they are filled, 
 and return up full on the left hand, until they arrive at the top at k, where 
 they strike against the end n of the fixed trough m by which they are 
 overset, and thus discharge the water into the trough, from which it may be 
 conducted by pipes to wherever it is required ; and as each bucket gets over 
 
 the trough, it falls again into a perpendicular position, and so goes down empty 
 until it comes to the water at o, where it is filled as before. On each bucket is a 
 spring r which, as it passes over the edge of the trough, elevates the end of the 
 
 bucket above the level of its mouth so as to discharge the whole of the water 
 into the trough. These springs are likewise useful in preventing the concussion 
 of the buckets against the trough. This machine, as well as the horn-drum, is 
 frequently driven by means of floats attached to the opposite side of the rim. 
 
 The Hungarian machine, so called from its having been employed in drain- 
 ing a mine in Chemnitz, in Hungary, produces its action by the condensation
 
 HYDRAULIC MACHINES. 
 
 721 
 
 shaft, at which the disci 
 
 of a confined portion of air, produced by the descent of a high column of water 
 contained in a pipe, and therefore acts with a force proportionate to the weight 
 of such column. Its general form is shown in the annexed cut, by which it will 
 appear that it is an exceedingly simple and useful machine, admitting of many 
 modifications and applications ; but it can be used only in hilly countries, or situa- 
 tions where the source of water by which it is to be worked is as much above the 
 top of the well as the water to be raised is underneath it. In this figure a is 
 supposed to he a well, or the shaft of a mine, from the bottom of which it is 
 necessary to raise the water standing at the level b b. c c is the surface of 
 the ground at the top of the well or 
 
 ed water 
 
 escaping, 
 
 either by running to waste, or being con- 
 verted to some useful purpose; and d is 
 the spring or other elevated source from 
 whence the supply of water for working 
 the machine may be obtained. The 
 machine itself consists of three cisterns > 
 chests, or reservoirs, two of which at 
 e and/ must be made very strong, and 
 perfectly air-tight, while the third at d 
 may be weaker, and open at the top, as 
 it is merely for collecting and retaining 
 the spring, rain, or other water for 
 working the machine. The lowest close 
 chest or reservoir e must be sunk be- 
 low the surface b b of the water in the 
 shaft or well a, but must not come into 
 contact with its bottom, otherwise the 
 water would be prevented entering the 
 chest by the valve g, which opens in- 
 wards for its admission. An open pipe 
 h h passes from very near the bottom 
 of this chest, through its top, in an air- 
 tight manner, and proceeds upwards in 
 the shaft as far as the surface of the 
 ground, where it bends over to deliver 
 its water, as at h c. Another open pipe 
 i , which may be of rather smaller 
 dimensions than the last, proceeds from 
 the top of the lower chest e to very 
 near the top of the second chest/; and 
 a third pipe, k I, of the same capacity 
 as the first, proceeds from very near the 
 bottom of the second close chest, up to 
 the bottom of the high reservoir d, but 
 has a cock or valve at /, by which it can occasionally be shut or opened. A 
 cock or valve, of large dimensions, is also fixed at m, by which the second 
 chest/ can be emptied of its water, and a smaller cock is fixed higher up, as at 
 t, for discharging its air. To set the machine in action nothing more is neces- 
 sary than to shut the cocks I and OT, and open the cock , from which the 
 air previously contained in the lower chest will escape, and its place will be 
 filled up by the water b b, which will pass through the valve g, until the chest 
 e is completely filled. That done, the air cock n is to be shut, and the water 
 cock I opened, when a column of water, equal to the full height and pres- 
 sure of the cistern d, will rush down the pipe k I, and by filling the chest . 
 will expel its air, which has no other opportunity of escaping but by the open 
 pipe i i, down which it will pass, and produce a pressure on the surface of the 
 water in the lower chest equal to the entire height of the column k I; and the 
 air thus thrown into the chest e, being in a condensed state, will form the
 
 7 22 HYDRAULIC MACHINES. 
 
 water previously in that chest up the pipe h h, from whence it will be dis- 
 charged at c. The lower chest e will now be filled with air, while the upper 
 shest/will be occupied by water: therefore the cock / must be shut, and 
 that at m opened, when the whole of the water from / will be discharged at 
 c, and will give the air in e an opportunity of returning again into / through 
 the pipe i i ; and as the air from e escapes, its place will be occupied by 
 a new charge of water, which will rise through the valve g, and again fill 
 the lower chest e, and prepare it for a second discharge. All, therefore, 
 that is necessary to keep the machine in action is to open the cocks I and m 
 alternately, that is to say, to keep the cock I open as long as any water flows 
 from the discharging pipe at h c, and as soon as the efflux ceases, to shut the 
 cock I, and open m to discharge the water from/, and permit the lower chest e 
 to fill, which will be effected whenever water ceases to flow from m. The cock 
 m must then be shut, and I opened, and so on alternately, which may easily be 
 done mechanically, and without superintendence, by using a part of the impelling 
 water from d, or that which has been 'discharged from h c, and which may be 
 employed to turn a small water-wheel, or to fill two small cisterns in which 
 floats are made to act. Mr. John W. Boswell devised a contrivance for answering 
 this same purpose, which will be found fully detailed in the second volume of 
 Dr. Gregory's excellent Treatise on Mechanics, where this simple machine is 
 described under several forms and modifications. It must not be supposed that 
 filling the middle vessel / with water will discharge the whole of the water out of 
 e, otherwise disappointment in its effects will ensue ; because, although water is 
 nearly incompressible, air is highly elastic, and the air in e will be compressed into 
 less than its natural bulk, or will be condensed with a force equivalent to the 
 pressure of the perpendicular column of water h h, which it has to overcome ; 
 and as atmospheric pressure was shown, when speaking of the pumps under 
 the second head or division, to be only equal to the support of a column of 
 water about 33 feet in height, so if we imagine this to be the height of the pipe 
 h h, that column of water would require one of double atmospheric elasticity 
 to support it, and hence the air in e will be condensed to half its former volume, 
 and, therefore, discharge but half the volume of water, although / should be 
 completely filled. Dr. Gregory further describes a curious phenomenon which 
 takes place in the working of this machine, and which never fails to create 
 surprise in the strangers who visit it, and to whom it is usually shown. That 
 is, when the efflux at h c has stopped, if the cock n be opened, the water and 
 air rush out together with prodigious violence, and the drops of water are 
 changed into hail or lumps of ice, issuing with such force as frequently to pierce 
 a hat if held against them, like pistol bullets. This rapid congelation is a le- 
 markable instance of the general fact, that air, by suddenly expanding, generates 
 cold, its capacity for heat being increased. 
 
 The Water Ram, or Better Hydraulique, as it was called by its inventor, 
 M. Montgolfier, of Paris, is a highly useful and simple machine, for the purpose 
 of raising water without the expenditure of any other force than that which is 
 produced by the momentum or moving force of a part of the water that is to 
 be raised. The effect of this machine depends entirely upon momentum, cr 
 the new quantity of force that is generated whenever a body is put into motion ; 
 and the effect of this is so great as to give the apparatus the appearance of 
 acting in defiance of the established laws of hydrostatic equilibrium ; for a 
 moving column of small height is made to overcome and move another column 
 much higher than itself. The form and construction of the hydraulic ram is shown 
 m the figure on the next page. Suppose o to represent a reservoir, or the source 
 of a spring, which is continually overflowing and running to waste by means 
 of a channel a few feet lower than itself, as at the level line p p. Instead of 
 permitting the water to flow over the sides of o, let it be conducted to the level 
 of pp by means of pipes q q connected with the side of the reservoir, and 
 terminating by an orifice r, in which a conical or other valve s is placed, so as to 
 be capable of effectually closing the pipe when such valve is drawn upwards, t is 
 an adjustable weight, fixed on the spindle of the valve s, by means of which the 
 valve is kept down and open ; any water, therefore, that is in the cistern o will
 
 HYDRAULIC MACHINES. 
 
 723 
 
 How down the pipe q q, and escape at the orifice r, so long as the valve remains 
 down ; but the instant it is raised and shut, all motion of the water is suspended. 
 Thus situated the adjustment of ^the weight t must take place, and by adding 
 to, or subtracting from it, it must be made just so heavy as to be capable of 
 sinking or forcing its way downwards against the upward pressure of the water, 
 the force of which will depend upon the perpendicular distance from the surface 
 of the water in o, to its point of discharge at r (represented by the dotted line 
 o v) ; consequently, if the valve s be raised by the hand or otherwise, all motion 
 
 of the water in the pipe q q will cease, but the instant the valve is released, it 
 will fall down and permit the water to escape. The water by its motion acquires 
 momentum and new force, and consequently is no longer equal to the column 
 o v, to which the valve has been adjusted, but is superior to it, by which it is 
 enabled to overpower the resistance of the weight t, a"nd it carries the valve up 
 with it, and closes the orifice r. This is no sooner done than the water is 
 constrained to become again stationary, by which the momentum is lost, and 
 the valwe and weight again become superior, and fall, thus reopening the orifice, 
 and permitting the water to flow again ; and as the pressure of the water and 
 t!ie weight of the valve each alternately preponderate, the valve is kept in a 
 constant state of vibration, or of opening and shutting, without any external aid 
 whatever. Such is the principle upon which the motion of the water in the 
 pipe q q is produced; but the motion generated cannot be instantly annihilated ; 
 and it is not only of sufficient power to raise the valve s, but likewise to burst 
 open the lower end of the pipe q q, unless a sufficient vent be provided, by 
 \\hich this accumulated force can escape. Accordingly a second valve is 
 placed near the lower end of these pipes, and is made to open upwards into an 
 air vessel w, with a discharging pipe x, and, consequently, whenever the valve 
 A- is closed, the water which would otheiwise have flowed from the orifice r 
 now opens the valve u and enters the air vessel, until the spring of the con- 
 tained air overcomes the gradually decreasing force of the momentum, when 
 the valve u closes, and that at s opens to permit the water to make a second 
 blow or pulsation, and in this way the action of the machine continues un- 
 ceasingly, without any external aid, so long as it is supplied with water and 
 remains in repair. A small running stream is necessary for this machine, as 
 the water at o should be kept at one constant elevation to ensure the perfection 
 of its action. A much greater quantity of water likewise escapes at the orifice r 
 between the pulsations than can be raised in the delivery pipe #, particularly 
 
 if it extend to any considerable height, for the comparative quantity of water 
 discharged through a?, and permitted to run to waste at r, must always depend 
 .ipon the respective perpendicular heights of the pressing column o v and the 
 delivered or resisting column w x, and the rapidity of the pulsations will like- 
 wise depend upon the same circumstances. Mr. Millington, from whose Epitome 
 of Natural Philosophy the above description is taken, and who has erected 
 several of these machines in different parts of England, which gave great satis-
 
 724 HYDRAULIC MACHINES. 
 
 faction, in order to show their efficacy gives the following particulars of one, 
 which, at the time when he wrote, had been in constant use for about two years. 
 The reservoir o is a basin of about 10 feet square and 2 feet deep, formed 
 partly in limestone rock, and partly in brickwork, the supply of water being 
 from a natural spring. The pipe qq is of cast iron, 14 yards long, and 2 inches 
 in diameter. The piece at the end, containing the air vessel and the valves, is 
 about fifteen inches long; the valves 1J inch each in diameter, and made of brass ; 
 contents of the air vessel, about 1 gallon. The height from the surface of the water 
 at o to its point of discharge at r, is 6 feet 4 inches, measured perpendicularly. 
 The delivery pipe x is of lead, 1 inch in diameter, and proceeds horizontally under 
 the ground 104 feet, and then rises perpendicularly to the height of 54 feet 
 3 inches above the discharge valve at r, where it delivers the water into a large 
 cistern. The water is thus raised 47.11 inches above the surface of the spring 
 which supplies it, and this by a fall of only 6 feet 4 inches. So circumstanced, 
 the valve * makes about 50 vibrations, or opens 50 times in a minute, when it 
 loses about two quarts of water, and injects nearly a quarter of a pint into the 
 elevated cistern at each pulsation ; the water lost being to that which is raised 
 nearly as 17 to 1. This may appear a small quantity of water, but when it is 
 recollected that the machine is at work night and day (unless purposely stopped), 
 and furnishes six quarts of water every minute, this will be found to be a supply 
 adequate to a very large household establishment. The construction above 
 described is, however, incomplete, as, owing to the mutual incorporation which 
 takes place between air and water, the successive quantities of water that are 
 impelled into the air vessel would soon absorb the whole of the air contained 
 in it, and it would cease to afford that elasticity which is indispensable to the 
 working of the machine. This was discovered in France by M. Montgolfier, 
 who added an improvement to the machine by introducing a very small shifting 
 valve, opening inwards into the lower part of the air vessel, but kept shut by a 
 small spring. This is shown in the separate shaded figure above the last 
 described, and represents an improved form of the air vessel. This valve is 
 self-acting, and effectually prevents the escape of any air or water from the air 
 vessel ; but when the water is thrown back by the shutting of the valve s, it 
 produces an instantaneous vacuum at the end of the pipe q, upon which the 
 shifting valve opens, and admits a sufficient quantity of the external air into 
 the air vessel to keep it constantly replenished, and by this simple addition the 
 water ram is J jndered continuous in its action. 
 
 The cut on page 725 represents a machine for raising water, the invention of 
 Mr. Rudolph Cabanal, engineer, of Melina-place, Westminster-road. It con- 
 sists of a series of troughs fixed one above another in a frame-work, and sj 
 inclined in contrary directions that each trough is united at one of its ends with 
 the trough next below it, and at the other end with the trough next above it. 
 The lower part of this frame-work forms the segment of a circle, and rests 
 upon a horizontal plane ; so that with a very slight impulse the whole 
 machine is put into a rocking motion ; the lowest trough is thereby made to dip 
 at each oscillation into a reservoir of water, which enters the trough through 
 valves at the bottom ; these opening only upwards, the water cannot return. As 
 the next oscillation raises the end that was before depressed, the water runs 
 along the trough to the opposite side of the machine, where it is discharged 
 into the depressed end of the trough above it ; from this second trough it is at 
 the next oscillation thrown into the third trough ; then from the third to the 
 fourth at the following oscillation : in like manner it ascends each trough suc- 
 cessively by the alternate rocking of the machine, until the water is raised ana 
 discharged at the required height. As the number of troughs, and the height 
 of the machine, will depend upon the altitude to which it is required to raise 
 the water, and as three troughs will show the arrangement and the action of 
 the machine, as well as a greater number, we have, accordingly, reduced ouv 
 diagrams to the exhibition of only three; these are shown at a be, Fia. 1, 
 attached to the framing e e e e e, with its curved segment d resting upon its 
 horizontal plane p. It is necessary here to notice that the frame-work is 
 double, that is, there are the same parts on this side the trough as are shown
 
 HYDRAULIC MACHINES. 
 
 725 
 
 in Fig. 1 on the opposite side, which will be better understood on reference to 
 the plan Fig. 2, where one side of the parallelogram marked e (as in Fig. 1), 
 corresponds with the opposite side marked/. Now it will be evident that when 
 the lowest end marked I of the trough a is depressed, it will dip into the reser- 
 voir g, and, by the opening of the valves, receive the water as shown; the 
 reverse motion of the machine, by which the end m is depressed, then causes 
 
 the water to run along a into b, and, at the next oscillation, from b to c, and so 
 on into any number of troughs in succession. In the plan, Fig. 2, but two 
 troughs could be shown ; these are the lowest, all the others being of the same 
 shape : / / is the depressed end of a, showing its long flap-valves, and that the 
 water runs from one to the other under the partition that seems to divide them. 
 The end m being depressed, the water flows in like manner into the double 
 chamber of b, and from b it is discharged into c, which, being above b, cannot 
 be shown in this plan. To the ends of each trough an inclined plane or board is 
 fixed to prevent the water from splashing over it ; these are shown at /* h under 
 the troughs a b. Contrivances of this kind are described in most of the old 
 writers upon hydraulics ; and in France, where they are known as the " water- 
 balance," several curious constructions have been invented. 
 
 A patent was taken by Mr. A. Bernhard for a novel mode of raising water 
 by the joint action of exhaustion, atmospheric pressure, heat, and condensation, 
 to a height exceeding fifty feet, with the view of applying the fall from that 
 4 z
 
 726 HYDRAULIC MACHINES. 
 
 height as a motive power for impelling machinery. The water to be raised runs 
 from its level into a cistern contiguous to the foundation of a large boiler; and 
 from the latter proceeds downwards a curved pipe dipping into the cistern. At 
 the top of the boiler there is another pipe, which leads shortly into a vertical 
 pipe, upward of eighty feet in height, which the patentee terms the hot water 
 atcend'mg pipe. To pieserve the temperature of the fluid in this pipe, the lower- 
 most portion of it, to the extent of 30 feet, is inclosed in the brick flue of the 
 furnace chimney ; hence it is inclosed in an iron funnel pipe, which forms the 
 remainder of the flue to the top of the building, which is a pyramidal tower 
 100 feet high. Near the top of the tower is a refrigeratory, formed by a judi- 
 cious arrangement of two tiers of pipes placed horizontally in a wooden case ; 
 into these pipes the hot water in the ascending pipe (which here terminates by 
 branching oif from the flue) is discharged. Throughout the refrigeratory box, 
 and surrounding the pipes, a current of cold air is continually passing ; this is 
 brought from the lowest part of the building through a large tube, and is dis- 
 charged through another proceeding from the top of the refrigeratory, and 
 extending to 25 feet above the altitude of the tower, to cause a strong draught. 
 The effect of this current of air is to cool the hot water distributed in its pipes, 
 from the lower tier of which it runs out and descends a vertical pipe 36 feet in 
 length, whose lower extremity is turned up and immersed in a cistern of water 
 to seal it from the air ; this pipe the patentee calls the cold water descending 
 pipe ; the upper end of it communicates with the exhausting pipe of an air 
 pump, which is used in the first place to obtain a partial vacuum in the pipes 
 described, and afterwards to abstract the air disengaged from the hot water 
 during the progress of the operation. The reader will now perceive, that when 
 the exhausting process is nearly completed by the working of the air-pump, the 
 pressure of the atmosphere will force the water out of the cistern on the lowest 
 level up the curved pipes mentioned, into the boiler, and filling the same, the 
 water will rise up the vertical (hot water ascending) pipe, proceeding from the 
 top of the boiler to the height of about 30 feet. This being effected, the 
 patentee says that if heat be now applied to the boiler, the water will thereby 
 be made to rise 50 feet higher into the refrigeratory. Here, being distributed 
 in the small pipes, it is cooled, and descends to the cold water pipe, wherein the 
 pressure of the column of water being greater than that of the atmosphere, the 
 water will run out over the cistern, and will continue to do so until the equi- 
 librium is restored, which it is the object of the patentee to prevent, and thus 
 obtain a constant power by the fall of the water from the cistern. Having so 
 far explained the object of the patentee, and the principle upon which he 
 intends to operate, we shall now describe the apparatus more particularly with 
 reference to the engraving on the next page, which is merely a diagram of the 
 apparatus, as complete drawings of it would require several figures, a a represent 
 the walls of the building bed e four floors in the same ; / the refrigeratory, 
 which communicates with the hot water ascending-pipe g ; h h is the air-tube, 
 which receives its supply at j, and after blowing through the refrigeratory, 
 escapes by the tubej, which extends 25 feet above the tower (but is shown, for 
 want of room, as broken off) ; the water in the refrigeratory is prevented from 
 returning by the intervention of a valve, and after being cooled in passing 
 through the series of pipes, runs down the pipe k; at I is the air-pump with the 
 pipe n, which connects it with the top of the pipe k, through the medium of 
 which the other pipes are exhausted ; q is the reservoir which receives the water 
 upon the natural level by a channel as at r ; the operation of the air-pump 
 causes the water to rise up the pipe s into the boiler t, thence up the pipe g as 
 high as the dotted line u, after which, heat being applied to the boiler by the 
 furnace v, the hot water rises to the refrigerator}'. About midway of the pipe 
 g there is a stuffing-box at one of the junctures to allow of the expansion and 
 contraction of the metal by changes of temperature. The pipe g is shown as 
 extending vertically through the brick chimney up to w, thence through the 
 
 flue x to the box y; hence it proceeds to the refrigeratory, and the flue-pip 
 takes a bend as at r, and proceeds to the top of the building. To prove th 
 truth of the principle, the patentee erected an apparatus on a considerable scale
 
 1IYDRAULICON. 
 
 727 
 
 in the Kent Road, near Peckham, but the result was a complete failure ; and 
 even had it been practicable, we doubt much whether it would have been au 
 
 economical mode of raising water to that height, when we consider the fuel that 
 must be expended to raise the temperature of the water, and the power required 
 to work the air-pump. 
 
 HYDRAULICON, OR WATER ORGAN. A musical instrument acted upon 
 by water ; the invention of which is said to be of higher antiquity than that of 
 the wind organ.
 
 726 HYDROMETER. 
 
 HYDRIODA1ES. Salts consisting of hydriodic acid, combined in definite 
 propoitions with oxides. 
 
 HYDROCHLORIC ACID. A compound of chlorine and hydrogen. 
 
 HYDROCYANIC ACID. Prussic acid; which see. 
 
 HYDRODYNAMICS treats of the mechanical properties of fluids in general. 
 It is usually divided into hydrostatics, which explains the pressure and equi- 
 librium of liquids, such as oil, water, &c. ; Hydraulics, which points out the 
 laws and effects resulting from the motions of liquids ; and Pneumatics, or the 
 doctrine of elastic fluids or gases, as steam, air, &c. 
 
 HYDROGEN GAS. See CHEMISTRY. 
 
 HYDROMETER. An instrument for ascertaining the specific gravities of 
 different liquids. The most common description of these instruments consists 
 of a hollow ball, of either metal or glass, capable of floating in any known 
 liquid, and having two stems, the lower one terminating in a weight, in order 
 that the instrument may float with the stems upright, and the upper stem 
 (which is of the same diameter throughout), being graduated, to show the den- 
 sity of the fluid by the depth to which it sinks ; as the heavier fluids will buoy 
 up the instrument more than such as are lighter. In this way, however, it is 
 clear that the stem must be of considerable thickness, in order that the instru- 
 ment may have an extensive range, in which case the smaller differences of den- 
 sity will not be perceptible. To obviate this imperfection various contrivances 
 have been resorted to ; one of the most common of which is, to construct tlio 
 instrument as above described, but with a very slender stem, which is divided 
 into 100 equal parts; and to provide a number of movable rings, all of equal 
 weight, any one of which being slipped over the stem, when the instrument 
 floats in distilled water with zero on the stem at the surface of the water, will 
 cause it to descend until the top of the scale be at the surface ; and the density 
 is estimated by the number of weights required to bring the lower part of the 
 scale below the surface, minus the number of divisions of the scale which remain 
 above the surface. But the method of Fahrenheit is both simpler and more 
 accurate. The hydrometer of Fahrenheit consists of a hollow ball with a 
 counterpoise below, and a very slender stem above, terminating in a small dish. 
 The middle or half length (the stem,) is distinguished by a fine line across, and 
 the instrument is always immersed up to this line by placing weights in the 
 little dish above. Then as the part immersed is constantly of the same magni- 
 tude, and the whole weight of the hydrometer is known, this last weight added 
 to the weights in the dish will be equal to the weight of fluid displaced; and if 
 the gravity of water be represented by 1000, and the weight be divided into 
 thousandth parts of the weight of the instrument when it sinks to the middle 
 of the stem in distilled water, the number of weights required to sink the 
 instrument to the mark on the stem when floating in any fluid, added to the 
 weight of the instrument, or 1000, will represent the specific gravity of the 
 fluid. 
 
 The engraving on the following page represents an instrument for ascertain- 
 ing specific gravities, invented by Dr. Hare, Professor of Chemistry in the 
 University of Pennsylvania. This instrument, to which the inventor has given 
 the name of Litrameter, owes its efficiency to the principle, that when columns 
 of different liquids are elevated by the same pressure, their heights must be 
 inversely as their gravities. Two glass tubes, of the size and bore usually 
 employed in barometers, are made to communicate internally with each other, 
 and with a gum elastic bag G, by means of a brass tube, and two sockets of 
 the same metal, into which they are severally inserted. The brass tube termi- 
 nates in a cock, in which the neck of the bag is tied. Between the cock and 
 the glass tubes there is a tube at right angles to an opening into that which 
 connects them. At the lower end of this tube, a small copper rod R enters 
 through a collar of leather. The tubes are placed vertically in grooves, against 
 an upright strip of wood, tenonned into a pedestal of the same material. 
 Parallel to one of the grooves, in which the tubes are situated, a strip of brass 
 is fastened, and graduated, so that each degree may be equal to ^ of the 
 whole height of the tubes. The brass plate is long enough to admit of about
 
 HYDROMETER. 
 
 729 
 
 140. Close to this scale a vernier v is made to slide, so that the divisions of 
 the scale are susceptible of sub-division into tenths, and the whole height of the 
 tubes into about 2200 parts or degrees. 
 On the left side of the tube there ia 
 another strip of brass, with another 
 set of numbers, so situated as to 
 comprise two degrees of the scale 
 above mentioned, in one. Agreeably 
 to this enumeration the height of 
 the tubes is, by the aid of a corre- 
 spondent graduation on the vernier, 
 divided into 1100 parts or degrees. 
 A small strip of sheet-tin k is let 
 into a kerf in the wood, supporting 
 the tubes, in order to indicate the 
 commencement of the scale ; and 
 the depth to which the orifices of the 
 tubes must extend. At distances 
 from this of 1000 parts and 2000 
 parts, (commensurate with those of 
 the scale,) there are two other indices, 
 T T, to the right hand tube. Let a 
 small vessel containing water be made 
 to receive the lower end of the tube, by 
 the side of which the scale is situated ; 
 and a similar vessel of any other 
 fluid, whose gravity is sought, be 
 made to receive the lower end of the 
 other tube ; so that the end of the 
 one tube may be covered by the 
 liquid in question, and the end of 
 the other tube by the water. The 
 bag being compressed, a great part 
 of the contained air is expelled 
 through the tubes, and rises through 
 the liquid in the tumblers. When 
 the bag is allowed to resume its shape, 
 the consequent rarefaction allows 
 the liquids to rise into the tubes, 
 in obedience to the greater pressure 
 of the atmosphere without. If the 
 liquid to be assayed be heavier than 
 water (as, for instance, let it be con- 
 centrated sulphuric acid,) it should 
 he raised a little above the first 
 index, at the distance of 1000 degrees 
 from the common level of the orifices 
 of the tubes. The vessels holding 
 the liquids being then removed, so 
 that the result maybe uninfluenced by 
 any inequality in the height of the 
 liquids, the column of acid must be 
 lowered, until its upper surface co- 
 incide exactly with the index 1000. Opposite the upper surface of the 
 column of water the two first numbers of specific gravity of the acid will 
 then be found ; and, by duly adjusting and inspecting the vernier, the third 
 figure will be ascertained. The liquids should be at the temperature of 
 60. If the liquid under examination be lighter than water, as in the case of 
 pure alcohol, it must be raised to the upper index. The column of water, 
 measured by the scale of 1000, will then be found at 800 nearly; which shows 
 that 1000 parts of alcohol are, in weight, equivalent to 800 parts of water; or, in
 
 730 
 
 HYDROSTATICS. 
 
 other words, 800 is ascertained to be the specific gravity of the alcohol. The 
 sliding rod and tube at r, between the cock and the glass tubes, facilitates the 
 adjustment to the index of the column of liquid in the right hand glass tube. 
 When the rod is pushed in as far as possible, it causes a small leak, by which 
 the ah- enters ; and the columns of the liquids, previously raised too high by the 
 bag, may be allowed to fall, till the liquid which is to be assayed is near the 
 index; then, by pushing the rod in, they may be gradually lowered, and 
 adjusted to the proper height, with great accuracy. A rod of this kind, 
 graduated, might answer the purpose of a vernier. 
 
 Meikles' Syphon Hydrometer, represented in the annexed engraving, it will 
 be seen, is upon this same principle, but of a much simpler 
 construction. This instrument consists of a g'lass tube, open " 
 at both ends, and bent into a kind of double syphon, having 
 four parallel legs ; so that the open ends are pointed in the 
 same direction, or upwards, as in the annexed engraving. The 
 manner of usingitis very simple : let one of the ends be stopped 
 with a finger or cock, and water be poured into the other. The 
 fluid will only rise a small way into the second leg, because of 
 the included air : next, stop the other orifice, and open the 
 one first closed ; and having poured into the latter the liquid 
 whose specific gravity is to be tried, open the top of the water H / \ 
 tube ; then the instrument being held upright, the two liquids *" 
 
 will arrange themselves so as to press equally on the included 
 air. This pressure will be measured by the difference in 
 the heights of the two columns of either liquids multiplied 
 by its specific gravity, so that by dividing the difference of 
 the two columns of water by the difference of those of the 
 other liquid, we obtain the specific gravity of the latter ; that 
 of water being unity. The difference between the columns 
 may be measured by applying any scale of small equal parts, 
 or the glass may be attached to a graduated plate furnished 
 with verniers, &c. The longer the columns of liquid employed, the more 
 accurate the process. The expansion of the glass or its capillary action cannot 
 affect the result, nor is it influenced by the expansion of the scale ; the only 
 correction required will be to reduce the observations to one temperature. 
 
 HYDROPHANE. A variety of opal, which has the property of becoming 
 transparent on immersion in water. It is also called oculus mundi. We must be 
 careful to immerse them only in pure water, and to withdraw them whenever 
 they have acquired their full transparency. If we neglect these precautions, 
 the pores will soon become filled with earthy particles, deposited from the water, 
 and the hydrophane will cease to exhibit this curious property, and will remain 
 always more or less opaque. 
 
 HYDROSTATICS explains the pressure and equilibrium of liquids, or of 
 what have been generally termed inelastic fluids. A fluid is a body whose 
 parts are put into motion among one another by the slightest force, and which 
 return to their former state as soon as the impressed force is removed. Fluids 
 have been divided into elastic and inelastic; but recent experiments have 
 proved that there is no fluid that may not be compressed by a suificient force, 
 and that will not return to its former state when the compressing force is with- 
 drawn. The terms may, however, without much inconvenience, be retained, 
 as the difference in compressibility is so great, that a sufficient distinction 
 obtains. Thus the same power that would reduce air to one half of its former 
 dimensions would effect a compression not exceeding one twenty-thousandth of 
 Us bulk in water. Hydrostatics, then, is concerned with those fluids, the com- 
 pressibility of which may, for most practical purposes, be considered as inap- 
 preciable. The laws of this science are generally proved by experiments on 
 water, as a fluid that is most plentiful, and most easily adapted to the purpose. 
 1 he principal and most important propositions with respect to pressure are, 
 1. I hat fluids press equally in all directions. 2. That in fluids of equal density 
 the pressure is proportional to the perpendicular distance from the surface, 
 inat fluids press equally in all directions is seen in a variety of cases, and may
 
 HYDROSTATICS. 
 
 731 
 
 therefore be easily made evident. If a cylindrical tin vessel have two holes of 
 equal size, one in the bottom and the other in the side as near the bottom as 
 may be, it will be found that each of these holes will permit the contents of 
 the vessel to run out in equal times. Now as the velocity of the running water 
 is dependent upon the pressure, it is manifest that the pressure upon the side, 
 or lateral pressure, is equal to that on the bottom, or downward pressure. That 
 the upward pressure is also equal is inferred from the fact, that water poured 
 into one of the legs of a bent tube will rise to an equal height in the other leg. 
 This upward pressure is a feature that distinguishes fluids from solids, and is 
 due to the extreme mobility of its particles, owing to the repulsive energy 
 which is exerted when the least compressing force is applied. We have next 
 to show that the pressure upon any particle in a fluid is proportional to its 
 perpendicular depth. In the annexed diagram, if a; be 
 a particle of water, the pressure exercised upon it will " 
 be proportional to the depth B x ; for if a hole were 
 made at x, the fluid (making allowance for the resist- 
 ance of the air) would spout up to A e. In like manner 
 the pressure at C is equal to the perpendicular depth 
 B C ; and as every particle on the bottom is at an equal 
 depth, the whole pressure will be equal to that pro- 
 duced by a column filling the whole space BCDe. 
 From this it appears that the pressure on the bottom 
 of a vessel is equal to the area of the base multiplied by 
 its perpendicular height. In vessels having equal bases the pressure will be 
 proportional to the height, and in vessels of equal depths the pressure will be 
 as the area of their bases, and this without any regard to the quantity of fluid 
 employed. This has given rise to the hydrostatic paradox " that any given 
 quantity of water, however small, may be made to balance any other quantity, 
 however large." Also the hydrostatic bellows depend on the same principle. 
 In the cut, A and B are two circular boards connected by leather after the 
 manner of a pair of bellows, so as to be water-tight. A tube, C D, is made to 
 communicate with the interior. If a small quantity 
 of water be now poured in so as to separate the 
 boards, and a number of heavy weights be placed upon 
 the upper board, the water in the tube C D will be c 
 seen to rise till it balance the weights placed upon A. 
 If the quantity of water in the tube, above the level 
 A.g, be noticed, it will be found to be so much less 
 than the weights upon A, as the area of the bore of 
 the tube falls short of the area of the board A. To 
 make the subject more evident, let us suppose the 
 sectional area of the tube C D to be half a square 
 inch, and that of the lower board of the bellows to be 
 one square foot, or 288 times greater ; it will then 
 be found that one pound of water in the tube C D 
 
 ill support a weight of 288 pounds on the board 
 g. In a similar way, a long narrow tube may b 
 
 Ag. _, j 
 
 inserted perpendicularly into a cask or other vessel; 
 after the vessel has been filled, a few ounces of water 
 poured into the tube will burst it. If a fissure in a rock should communicate 
 with an internal cavity of considerable magnitude, situated at some depth 
 below the top of the fissure, and filled with water, the pressure may be so 
 enormous as to burst the rock. The same effect may be produced by rain 
 falling into, and filling a long slender chink that may have been left in the 
 walls of a building ; whether the chink is of equal diameter throughout, or 
 vary in its size, and whether it be straight or crooked, provided it be water- 
 tight, so as to get full of rain, the effect will be the same, the pressure being 
 always proportionate to the perpendicular height. This principle has been inge- 
 niously applied by the late Mr. Bramah, in what is termed the Hydrostatic 
 Press, a machine by which an almost incredible force may be obtained in a
 
 732 HYDROSTATICS. 
 
 very small compass. (See Bramah's Press). From the equal pressure in all 
 directions arises the tendency in fluids to find their own level, so that the surface 
 of every fluid at rest is horizontal ; and for a similar reason, if two fluids be in 
 the same vessel, and do not mix, their common surface will be parallel to the 
 horizon. From what has been stated on the nature of fluid pressure, it will be 
 easy to calculate the pressure on any horizontal surface. Thus, if a cubical 
 vessel be filled with water, the pressure on the base will be equal to the weight 
 of the fluid. The same pressure will obtain if the vessel be of a conical form, 
 provided the area of the base ajid the height be the same. The pressure upon 
 a perpendicular surface will of course vary with the depth. If a board one 
 foot square be placed perpendicularly in a vessel of water, and be divided into 
 horizontal sections, each one inch deep, then calling the pressure at the depth 
 of one inch 1, the pressure at two inches will be 2, at three inches 3, and so on ; 
 hence the whole pressure will be equal to the sum of the series 0, 1, 2, 3, 4, 5, 6, 
 7, 8, 9, 10, 11, 12: this will amount to half the pressure which would have 
 occurred if the board had been situated horizontally 12 inches below the 
 surface. Now, as the centre of gravity of this surface is situated in the 
 middle of the board, it follows that the area of the board, multiplied by 
 the distance of its centre of gravity beneath the surface, will be equal to 
 the pressure. From a more extended investigation it is found that this rule 
 is general, that the pressure of a fluid against any surface, in a direction per- 
 pendicular to it, varies as the area of the surface multiplied into the depth 
 of its centre of gravity. From this we see that the pressure against the four 
 sides and bottom of a cubical vessel is equal to three times the weight of 
 the contained fluid. From this also may be calculated the pressure on dock 
 gates, on the lower parts of ships, and large cisterns, coolers, &c. In all 
 cases of pressure the amount, as determined above, must be multiplied by the 
 specific gravity of the fluid employed, as it will be evident, that if two vessels 
 of equal sizes and similar shapes be filled, one with water, and the other with 
 mercury, that the pressure on the base of the latter will be so much greater 
 than that on the former, as the weight of the mercury exceeds that of the water. 
 The equal pressure in all directions causes the surface of all large bodies of 
 water to be horizontal, and also the surfaces of any two bodies of water com- 
 municating by a tube or otherwise ; hence the construction of water levels. In 
 the annexed cut A B is a tube turned up at each end, 
 
 and filled with mercury or water. Upon the surface /+ 
 
 of the fluid at c and d are small floats, carrying an nf e T 
 
 upright sight, with a horizontal wire or hair across it. m 03 
 
 When the instrument is held in the hand, on looking H^ _Jj 
 
 through c its cross wire will cover that of d, because \^ / 
 
 the fluid stands equally high in both legs. If it be A B 
 
 required to know whether any distant object be horizontal, it is only necessary 
 to point the instrument toward it; and if the two cross wires and the object 
 coincide, the object is in the same horizontal line. The common spirit level 
 consists of a small tube filled with spirits of wine, except a small space, which 
 contains a bubble of air. The tube is hermeticalb' sealed ; and when placed 
 on a horizontal surface, the bubble will be seen in the middle of the tube. 
 A little reflection on the nature of hydrostatic pressure will show its appli- 
 cability to the purpose of ascertaining the comparative weights of bodies, or, 
 what is commonly termed their specific gravities. If a body of any shape, 
 either as heavy as water, or heavier than it, be plunged into a vessel filled with 
 that liquid, it will of course displace a quantity of fluid equal to its own bulk, 
 and if the quantity be measured, we have a ready measurement of the mag- 
 nitude of the solid body that was immersed ; for as the water displaced is 
 equal in bulk to the size of the irregular solid, a measurement of the one will 
 serve to ascertain the other. Again, if the quantity displaced be weighed, 
 and the immersed solid weighed also, we shall have the relative weights of the 
 two substances, or their specific gravities. If the whole of the water displaced 
 could be accurately collected and weighed, this method would furnish a ready 
 mode of ascertaining the relative weights of any two bodies. Thus, if two
 
 HYGROMETER. 733 
 
 bodies of equal weight, successively plunged into water, were to displace one 
 and two ounces of water respectively, the relative weights of the bodies would 
 be as 2 to I. As, however, considerable difficulty would arise in the use of 
 this method, the following process is used with bodies heavier than water. 
 Weigh the body in air, and also in water, observe how much of its weight it 
 loses by immersion in the water, and then divide the weight of the body in 
 air by the loss in water. Suppose a piece of gold to weigh 58 grains, by 
 weighing it immersed in water it would lose 3 grains of its weight ; divide the 
 58 grains by 3, and it will give 19 as the specific gravity of gold; that is, 
 the gold would be 19 times heavier than an equal bulk of water. The weights 
 of solid and liquid bodies are usually compared with that of water, one cubic 
 foot of which contains just 1 000 ounces avoirdupoise. Hence, by referring to tables 
 of specific gravities, we obtain the real as well as the relative weights of bodies. 
 Thus, in the example we have given, a cubic foot of gold would weigh 1000 X 19 j 
 = 19,333 ounces. If the solid consist of a substance that is soluble in water, it 
 must be covered with a coating of wax or varnish, and an allowance made for 
 the difference produced by the coating. When the solid consists of several small 
 pieces, a cup must be previously immersed, in the water, and accurately coun- 
 terpoised ; the fragments may then be placed in it, and the loss of weight ascer- 
 tained. If the body whose specific gravity is required be lighter than water, 
 anotherheavier body must be attached to it, and the loss of weight in the compound 
 being noticed, the loss in the heavier body must be subtracted from it, and it 
 will give the loss of weight in the body under investigation. The specific 
 gravity of liquids is found by filling a small bottle (which holds a definite 
 quantity, say 1000 grains of water,) with the liquid under examination, and 
 then weighing the quantity contained, the proportion which this bears to 1000 
 is the specific gravity of the liquid. Thus, if the bottle be successively filled 
 with water, real alcohol, and nitric ether, the weight of the equal measures 
 would be 1000, 797, and 908, which represent the specific gravities of these 
 fluids. This experiment shows clearly the nature of specific gravity, which it 
 will be seen is simply obtaining the real weights of equal measures of different 
 substances. If we could obtain a cylinder or cube of copper, and another of 
 gold, of exactly the same dimensions, and compare their true weights with the 
 weight of a portion of water of the same magnitude, we should at once obtain 
 their relative or specific gravities ; but as it is inconvenient to alter the shapes 
 of bodies, and, in many cases, would be next to impossible to obtain them of 
 precisely the same dimensions, the usual mode of weighing in water, by which 
 we obtain the weight of a quantity of water of equal bulk with the solid, is 
 infinitely preferable. For further information on the subject of this article see 
 BKAMAH'S PRESS, HYDROMETER, SPECIFIC GRAVITY, &c. 
 
 HYDROSULPHURETS. Compounds of sulphuretted hydrogen with the 
 salilhblf linses. 
 
 HYDRURETS, compounds of hydrogen with metals. 
 
 HYGROMETER. An instrument for ascertaining the degrees of dryness 
 ar moisture of the atmosphere ; therefore whatever substance expands by mois- 
 Lure or contracts by dryness, may be employed for the purpose, in connexion 
 with a suitable index and scale, showing the changes it undergoes. The 
 hygrometer invented by Saussure consisted of a hair, divested of its oil by 
 boiling it in water containing one per cent, of sulphate of soda. One of the 
 ends of the hair was attached to a fixed point, and the other to the circum- 
 ference of a movable cylinder, that carries a light index ; the hair being kept 
 straight by a counterweight of three grains, suspended by a fine silk thread to 
 the cylinder, and wound thereon the contrary way of the hair. As the hair 
 lengthens or shortens by changes in the humidity of the air, the cylinder 
 is put in motion, and the index fixed thereto points out on a graduated circle 
 the degree. This pretty little contrivance of Saussure'a was regarded as a 
 faithful indicator of the true condition of the atmosphere until M. de Luc 
 proved that hair was incapable of becoming a correct measurer of humidity, 
 and that this was owing to its organic reticular structure. The last-men- 
 tioned philosopher made an hygrometer, in which ivory was employed as the 
 5 A
 
 734 ICE. 
 
 medium of exhibiting the change of humidity. As ivory expands by moisture 
 and contracts by dryness, he formed a very thin hollow cylinder of this sub- 
 stance, open only at the upper end, into which he fitted the open end of a 
 very fine long glass tube, like that of a thermometer. Into these he introduced 
 a quantity of quicksilver, filling the ivory cylinder, and a part of the glass tube. 
 The consequence is this ; when moisture swells the ivory cylinder, its capacity 
 increases, and the mercury sinks in the glass tube ; and vice versa, when the air 
 is drier, the ivory contracts, and forces the mercury higher up the glass tube. As 
 this instrument is susceptible of being influenced by heat and cold, like the ther- 
 mometer, as well as by that of humidity, its indications are not to be depended 
 upon. Hygrometers are constructed, in a great variety of ways, by means of 
 sponge, and a rod suspended like a scale-beam. The rod is to have one of its 
 ends pointed, to serve as an index, and at the other end a hook to which the 
 sponge is fastened. The sponge is prepared by first washing it thoroughly in 
 clean water, and when it is dry washing it again in either water or vinegar, in 
 which a quantity of salt of tartar or sal-ammoniac has been dissolved ; after 
 which, the sponge being well dried, is fit for use. Then having fixed against 
 that part of a wall over which the point of the index will traverse, a graduated 
 circular arc, the index will show on this scale the state of the atmosphere; for 
 when the air is humid, the sponge will imbibe moisture from it, become heavier, 
 and consequently pull that arm to which it is suspended downwards; while the 
 other arm or index will move upwards, along the graduated arc on the wall. On 
 the contrary, when the air becomes drier, it imbibes the moisture from the sponge, 
 which consequently becoming lighter, the index preponderates, and moves 
 down the graduated arc, thus showing the moisture or dryness of the atmo- 
 sphere. Instead of the sponge, Mr. Gould recommends oil of vitriol, which 
 grows sensibly heavier or lighter, as the moisture of the air increases or 
 decreases ; so that being saturated in the dampest weather, it retains, loses, or 
 resumes its acquired weight, with the continuation, decrease, or increase of the 
 moisture in the air. So great is the alteration in the weight of this liquor from 
 the above cause, that in the space of fifty-seven days, it has been known to 
 change its weight from three to nine drams, and has shifted the tongue of a 
 balance thirty degrees. The curious on the subject of hygrometers may meet 
 with a great multiplicity of them in the Philosophical Transactions, and the 
 various scientific journals. 
 
 HYOSCIAMA. A new vegetable alkali, extracted by Dr. Brande from the 
 hyoscyamus nigra, or henbane. It is a strong poison. The vapour is extremely 
 prejudicial to the eyes ; the smallest morsel of the alkali upon the tongue is 
 dangerous. Nevertheless preparations of it are very advantageous, given in 
 medicine, by eminent practitioners. 
 
 HYPERBOLA, is one of the conic sections, formed by the intersection of a 
 plane and cone, when the plane makes a greater angle with the base of the 
 cone than that formed by the base and side of the cone. 
 
 HYPOTHENUSE, the longest side of a right-angled triangle. 
 
 I. 
 
 ICE. Water in a solid, crystallized state, owing to the abstraction of its com- 
 bined heat. Its specific gravity, according to Dr. Thomson, is .92. The force 
 of expansion exerted by water in the act of freezing has been found irresistible 
 in all mechanical experiments to prevent it. Advantage of this wonderful 
 phenomenon is taken to burst bomb shells, and other massive vessels, by filling 
 them with water, plugging them up, and then exposing them to the frost. The 
 effects of this expansive force are often observable by the bursting of trees, and 
 the rending of rocks, attended with a noise resembling the explosion of confined 
 gunpowder. Water after being long kept boiling, affords an ice more solid, 
 and with fewer air bubbles, than that which is formed from unboiled water ; also 
 pure water, kept for a long time in vacuo, and afterwards frozen there, freezes 
 much sooner than common water exposed to the same degree of cold in the 
 open atmosphere ; and the ice formed of water thus divested of its air, is much
 
 ICE-HOUSE. 735 
 
 more hard, solid, heavy, and transparent, than common ice. Ice after it is 
 formed, continues to expand by decrease of temperature ; to which fact is pro- 
 bably attributable the occasional splitting and breaking up of the ice of ponds 
 during the time of freezing, and sometimes, independent of other causes, the 
 separation of icebergs from the great frozen continent at the poles. According 
 to Dr. Black, ice requires 147 degrees of heat to reduce it to a fluid. 
 
 ICE-BOATS. There are two descriptions of boats which come under this 
 denomination ; namely, those that are designed to sail upon the surface of the 
 ice, and those that are employed to open the navigation of frozen rivers or canals, 
 by breaking up the ice. The first-mentioned kind of boats is much used in 
 Holland, on the river Maeze and the lake Y. These ice-boats are propelled, it 
 is said, with incredible swiftness, sometimes so quick as to render respiration 
 difficult; they are found very useful in conveying goods and passengers over 
 lakes and great rivers in that country. For this purpose a boat is fixed trans- 
 versely over a thick plank, or three-inch deal, under which, at the extremities, 
 are fixed irons, turned up forwards, resembling and operating as skates ; upon 
 this board the boat rests, with its keel at right angles to it ; and the extremities 
 of the boards serve as out-riggers to prevent the boat from upsetting, whence, 
 therefore, ropes are fastened that lead to the head of the masts, in the nature of 
 shrouds, and others passed through a block across the bowsprit. The rudder is 
 made somewhat like a hatchet, with the edge placed downwards, which, being 
 pressed down, cuts the ice, and serves all the purposes of a rudder in the water, 
 by enabling the helmsman to steer, tack, &c. 
 
 The other kind of ice-boat alluded to, is a strong and heavy-laden canal- 
 boat, fitted up for the purpose of breaking the ice, by arming the fore-part of 
 the keel and the bows with iron, which penetrate and break down the ice as the 
 boat is drawn forcibly along by an adequate number of horses towing it on the 
 path. This measure of opening the navigation of a canal is seldom adopted, 
 except when the ice is only a few inches in thickness, or when a thaw has ren- 
 dered thicker ice of little tenacity. "* 
 
 ICE-CREAM. A species of confectionary made by immersing cream, 
 variously flavoured, in a mass of ice, contained in a pail constructed for the 
 purpose, wherein the cream is congealed. 
 
 ICE-HOUSE. A repository for ice during the summer season. In London and 
 other places, ice is kept by the confectioners in deep cellars, from which the ex- 
 ternal air is excluded as much as possible, and provided with drains to keep them 
 dry. When the surrounding soil is moist, a frame-work, or case of carpentry is 
 constructed, having a grating at bottom, and is so placed in the cellar as to be two 
 or more feet distant from the floor, sides, and roof of the cellar. In this the ice 
 is said to be as perfectly preserved as in a dry cellar. Some market-gardeners 
 preserve ice in great heaps, by merely building it upon an elevated base in the 
 open garden, and covering it over and around by a very thick stratum of straw 
 or reeds. This plan of preserving ice is in accordance with Mr. Cobbett's 
 recommendation in his Cottage Economy, wherein he observes that " an ice- 
 house should not be underground, nor shaded by trees, but be exposed to the 
 sun and air ;" that its bed should be three feet above the level of the ground, 
 and composed of something that will admit of the drippings flowing instantly 
 off; and he adds, that " with some poles and straw, a Virginian will construct 
 an ice-house for ten dollars, worth a dozen of those which cost the man of taste 
 in England as many scores of pounds." The ice-houses built by the Virginians 
 consist of an inner shed, surrounded by an outer one, and having a sufficient 
 vacant space between the two to enable a person to walk round ; the walls and 
 roofs of both the sheds are made of thatch, laid on about a foot thick; and the 
 ice is deposited in the inner shed on a bed of straw. In England and France, 
 the common form of ice-houses is that of an inverted cone, or rather of an 
 hen's egg, with the broad end uppermost. The situation of an ice-house should 
 be dry, as moisture has a tendency to dissolve the ice ; it should also be so 
 elevated that water may freely run off. It should be exposed to the sun and 
 air (as observed by Mr. Cobbett), not under the drip, or in the shade of trees, 
 in order that the external deposit of moisture may be readily evaporated. The
 
 736 
 
 ICE-HOUSE. 
 
 j 
 
 form of the building may be varied according to circumstances; but in the well 
 or receptacle for the ice, it is desirable to have sufficient room for the deposit of 
 two or three years' consumption, as a provision against mild winters, \\here 
 the situation is of a dry, chalky, gravelly, or sandy kind the pit may be entirely 
 below the surface of the ground ; in which case, an ice-house on the plan recom- 
 mended by the late Mr. David Gordon (which was considered by that gentleman 
 as an improvement upon the American and Italian methods) may be advan- 
 tageously introduced, of which the annexed sketch represents an elevation. 
 
 'big a pit of about 12 feet deep, 
 and wide enough to permit the erec- 
 tion therein of a frame of rough wood 
 posts. This frame is to be 14 feet 
 wide each way at the bottom, and 16 
 feet each way at the top, conformably 
 to the sketch. The posts may be 
 about 9 inches in diameter, placed 
 near enough to each other for thin 
 laths to be nailed upon them, and the 
 inside be dressed to an acute angle, 
 so that as little wood as possible may 
 touch the ice. On the inside let thin 
 laths be nailed at about two feet 
 apart. On the outside, at moderate 
 distances, nail rough boards, and fill 
 the place within with wheat, or rye 
 straw set on end. The inside of the 
 roof to be made in the same way, 
 and also the gables. Straw is to be 
 sewed on the inside, and heath or 
 straw on the outside of the door.* 
 The outside of the roof is to be 
 thickly thatched with straw or heath ; 
 and heath, brushwood, or fir tops, to be filled in between the outside boarding 
 and the surrounding ground, and then neatly thatched or turfed over. The 
 bottom of the house, for two feet deep, should be laid with large logs or stones, 
 next with heath, fir-tops, or brushwood, and then with straw. The ice-house 
 thus completed, will look like a square bee-hive inverted, and is then ready to 
 receive the ice or snow. But unless the house be in a very shady place, Mr. 
 Gordon observes, it may be necessary to extend the roof, where the door is 
 placed, five or six feet, making a second gable and door, finished in the same 
 way as the first, and fill up the intervening space, except a passage, with heath 
 or straw. 
 
 Mode of filling the house. When the ice (or snow, if ice cannot be procured,) 
 is put into the house, it must be well beaten down with a pavior's rammer, or 
 mallet, and the surface always kept concave, as by this means any snow or ice 
 that may melt will run to the middle, or interstices, and freeze. For the same 
 reason, the ice ought always to be kept concave when it is taken out for use. 
 Should the frost be very intense when the ice-house is getting filled, it may 
 be very beneficial at the close of each day's filling to throw in thirty or forty 
 pails of water, which will fill the interstices and freeze. When the house is 
 full, spread upon the concave surface a carpet, or sail split up the middle, and 
 upon the top thereof a foot thick of water. When ice is required for the use 
 of the family, or when it is necessary to put in fresh meat to lie on the face of 
 the ice for preservation, or to take out for use, the straw and carpet, or sail, is 
 to be opened in the middle. Should rats infest the place, an iron-wire frame or 
 case may be required to put the meat or fkh, &c. into when lying on the ice. 
 A small open surface-drain ought to be dug round the house, to prevent any 
 water running into it. Opening the door of the house does little harm. 
 Damp or dense substances touching the ice is much more prejudicial than 
 <iry rir. 
 
 10 
 
 u
 
 ICE-SAWS. 
 
 737 
 
 ICE-SAWS. Large saws used for cutting through the ice for relieving shins 
 when frozen up. The vessels employed in the Greenland fisheries, and others 
 that navigate the polar seas, are regularly furnished with these machines, as 
 the lives of the crew not unfrequently depend on the expedition with which a 
 passage can be cut, so as to disengage the vessel before the further accumu- 
 lation of ice renders it an impossible undertaking. The saw, with a weight 
 suspended to it, is introduced by means of a hole broken through the ice, and 
 is suspended by a rope passed over a pulley fixed to a triangle. A party of a 
 dozen or more men, run out and back again with a rope, and thus move the 
 saw up and down till it has cut its Avay so far as to hang perpendicularly from 
 the pulley. The triangle is then moved a foot or two farther, and the sawing 
 recommences, the services of the whole crew being required in this laborious 
 undertaking. 
 
 Lieut. W. J. Hood, of the Hyperion, R.N. has recently greatly improved 
 this apparatus ; for the communication of which and the presentation of an 
 illustrative model to the Society of Arts, that gentleman was awarded the 
 Society's honorary medal. In Mr. Hood's machine, the saw is suspended by 
 a slight sledge, and is worked by the power of only two or three men at the 
 end of a lever ; a bar, called a propeller, is fixed on the lever between the ful- 
 crum and the saw, the other end resting on the surface of the ice, and so 
 adjusted that each motion of the lever shall produce a cut of a given length, 
 and at the same time, by means of the propeller, push the sledge on, so that the 
 teeth of the saw shall always be in contact with the ice. The annexed figure 
 
 gives a side elevation of the machine, a a a is a sledge, of open frame-work, rest- 
 ing on the surface of the ice ; b a transverse bar passing through the lever c c, 
 and forming the fulcrum on which it moves ; this lever has a cross handle, as
 
 738 IMPULSE. 
 
 represented in perspective in dotted lines ; e a clamp or brace consisting of two 
 cheeks, one on each side of the lever, loosely pinned at top to the lever, and 
 at bottom to the saw/; g a clamp similar to e, by which the weight d (which is 
 of the shape of a double convex lens) is hung to the lower end of the saw ; a 
 the propeller, an iron bar, terminating below in two claws, and at top in a fork, 
 and suspended on the lever by means of a transverse pin k; I a weight hung to 
 the propeller at m ; n a transverse bar, limiting the motion of the handle end 
 of the lever in an upward direction. It should be understood that there is a 
 duplicate frame similar to that brought into view, on the other side of the 
 machine, about 18 inches apart, and connected by transverse bars. To prevent 
 the lever from swerving laterally, there are at the handle ends two upright bars, 
 between which the lever moves. The saw, after having once entered the ice. 
 will only require from two to four men to work it ; and it should not be taken 
 out of the ice till after the distance required to be cut through is accom- 
 plished. The saw can be guided by the lever in any direction, so as to cut 
 the ice into pieces most convenient for removal, either by pushing them under 
 the adjacent floor of ice, or by dragging them out of the ship's track into clear 
 water. 
 
 ICHNOGRAPHY, in Drawing, is synonymous with the term flan, such as 
 is exhibited in an horizontal section of a building, or of any other object, 
 which shows the true dimensions to a scale of every part in the line or plane 
 through which the section is made. 
 
 IGNITION, in its general sense, properly signifies the setting fire to any 
 substance. But the sense is more usually limited to the kind of burning which 
 is not accompanied with flame, such as that of metals, stones, and other 
 substances, which become red hot without melting. 
 
 ILLUMINATING. A kind of miniature painting, anciently much prac- 
 tised for illustrating and adorning books, but now, comparatively to the other 
 modes of illustration, but little practised, being chiefly confined to very expensive 
 publications, of which a very few copies are intended to be taken, or to the 
 adornment of manuscripts. Formerly, besides the writers of books, there were 
 artists whose profession was to ornament and paint manuscripts, who were 
 called illuminators. The writers of books first finished their part, and the 
 illuminators embellished them with ornamented letters and paintings. In old 
 manuscripts blanks are frequently found, which were left for the illuminators, 
 who never filled them up. Some of the ancient manuscripts are gilt and 
 burnished in a style superior to later times, and the colours are so excellent, 
 as to indicate the exercise of great skill in preparing them. 
 
 IMPACT, in Mechanics, the simple or single action of one body upon 
 another, to put the latter, if at rest, in motion ; or, if it be moving, to increase, 
 retard, or alter the direction of its motion. The point against which the im- 
 pelling body acts is called the point of impact. 
 
 IMPALPABLE POWDERS. Powders so finely levigated, that the particles 
 of which they are formed cannot be distinguished by the senses, more especially 
 that of feeling. Fine pigments, prepared by a flat stone and muller, are 
 reduced to this state. 
 
 IMPENETRABILITY is commonly understood to imply that quality of a 
 body by which it cannot be pierced; but in Physics the term has a different, 
 or more refined signification. It is therein defined to be that property of a 
 body by which it prevents any other body from occupying the space in which 
 the former is. Two particles of matter cannot exist at the same time in the 
 same place, for as long as one retains its place, it must necessarily exclude the 
 other. Indeed, were the case otherwise, each body might be successively 
 absorbed into the substance of another, till the whole frame of the universe, 
 collapsing to a point, were lost in the vortex of annihilation. The fact of the 
 impenetrability of even water is easily demonstrated. If a solid body be 
 plunged into a vessel filled with water, a portion of the water will overflow 
 exactly equal to the bulk of the solid body immersed, which shows that it is 
 >nly a change of places of the substances. 
 
 IMPULSE, in Mechanics, the single or momentary action or force by which
 
 INDELIBLE. 739 
 
 a body is impelled by another body striking it, and is distinguished from 
 continued force, such as pulling, pushing, or pressure. Mr. Adams, in his 
 Lectures on Natural and Experimental Philosophy, justly observes, " We are 
 forced, by the evidence of every phenomenon in nature, by every experiment 
 in philosophy, to conclude that impulse is the only material cause of motion. 
 All the properties of matter are such as fit them to act, and to be acted upon, 
 in a mechanical way. They are all such as can be adapted to the known 
 principles of mechanism among artists. We are therefore bound by every 
 rule of sound reasoning, to consider it as the cause of all the motion, and 
 continuance of motion, in the material universe. It is the one certain .and 
 only universally known cause ; for neither the properties of matter, nor expe- 
 riment, nor observation, afford any other." 
 
 INCENSE. See FRANKINCENSE. 
 
 INCH. The twelfth part of a foot; it contains three barley-corns, or 
 twelve lines. 
 
 INCIDENCE, or LINE of INCIDENCE, in Mechanics, is the direction in 
 which one body presses or strikes upon another. 
 
 INCINERATION. The combustion of vegetable or animal substances, for 
 the purpose of obtaining their ashes or fixed residue. 
 
 INCLINATION, in Geometry and Mechanics, the mutual tendency of two 
 lines, planes, or bodies, to each other, making, at the point where they meet, 
 an angle, called the angle of inclination. Thus, the inclination of one line to 
 another, is the acute angle which those lines make where they meet. 
 
 INCLINED PLANE. One of the mechanic powers or simple machines by 
 which weights may be elevated with great facility. If a heavy body be sus- 
 pended freely in space, or against a vertical plane, it is manifest that a weight 
 equal to itself must be employed to sustain it. If, on the other hand, it rest on 
 a horizontal plane, the whole weight is sustained by the plane. But if the body 
 rest on a plane at all inclined to the horizon, a part only of the weight is 
 sustained by the plane. Let A B be a plane 
 inclined to the horizon ; D, a body supported 
 on the plane by means of the weight or power 
 E ; if the experiment be made by carrying a 
 cord over a fixed pulley, as in the diagram, it 
 will be seen that while the cord continues 
 parallel to the plane, the power E will bear to 
 the weight D the same proportion as B C to 
 B A ; that is, as the height of the plane to its 
 length. If the length of A B be six feet, and 
 the height one foot, a power of one pound will balance six pounds on the plane ; 
 if the height be two feet, one pound will balance three, and so on. To ascertain 
 the power obtained by this contrivance we must therefore divide the length of 
 the plane by the height. If the power act parallel to the base, the power is to 
 the weight as the height is to the length of the base. When the power acts 
 parallel to the plane, the power, weight, and pressure on the plane will be 
 proportional to the three lines B C, B A, and A C. For if the weight be 
 represented by a b, by the resolution of forces this may be decomposed into a c, 
 c b, one perpendicular and the other parallel to the plane. Now it is clear that 
 the one which acts perpendicularly on the plane will exert an equivalent 
 pressure, while the part that is parallel to the plane must be sustained by the 
 power. Hence the power, weight, and pressure, are proportional to the sides 
 of the small triangle a b c, which is similar to the large one ABC. If the 
 end of the cord be raised above the parallel direction, the pressure on the plane 
 will be diminished, but if it be depressed below the parallel direction, the 
 pressure will be increased, but in both cases a greater power will be required 
 to move the body up the plane. It is, we apprehend, needless to state examples 
 of the application of this method of increasing our power, as its use in assisting 
 to raise bodies to small elevations must be abundantly obvious. 
 
 INDELIBLE. Something that cannot be cancelled or effaced, as indelible 
 ink. See ANACARDIUM and INK.
 
 740 INKS. 
 
 INDEX, in Mechanism, is a light rod, similar to the hand of a clock 
 employed to point out the degrees marked upon a divided scale. 
 
 INDIGO. A blue colouring matter, extracted from the leaves and stalks of 
 the indigofera tincteria, or anil plant. The ancients were acquainted with this 
 dye under the name of Indicum. It is found both in the East and West 
 Indies, is spontaneous in China and Cochin China, and is cultivated all over 
 those vast empires. The seed is sown in little furrows two or three inches 
 deep, and about twelve inches distance from each other. Though it may be 
 sown at all seasons, the moisture of the spring causes the plant to shoot up in 
 three or four days, and it is at maturity at the end of two months. When 
 gathered it is thrown into a large cistern, called the steeping vat, containing 
 sufficient water just to cover the vegetable. The matter begins to ferment, 
 sooner or later, according to the warmth of the weather, and the maturity of 
 the plant, generally occupying from six to twenty hours. When the liquor is 
 in a proper state of fermentation (which is known by its heat, its thickening, an 
 abundant froth that it throws up, and its blue colour, inclining to violet), it is 
 let out by cocks in the bottom, into another vat placed for that purpose. In 
 this second vat, called the beating vat, the liquor ^is strongly and incessantly 
 beaten with a kind of buckets full of holes, fastened to poles. This part of the 
 process requires the greatest precaution. If the beating is ceased too soon, a 
 part of the colouring matter remains dissolved in the liquor ; if continued a 
 little too long, a part of that which is separated is dissolved afresh. The exact 
 time for discontinuing the process is determined by taking up some of the liquor 
 occasionally in a little cup, and observing whether the blue fecula is disposed to 
 separate and subside. The whole being now suffered to rest till the blue matter 
 has settled, the clear water is let off by cocks in the sides, at different heights, 
 and the blue matter at the bottom is discharged by another cock into a third 
 vat, where it is suffered to settle for some time longer, then conveyed, in a half 
 fluid state, into bags of cloth, to strain off more of its moisture ; and, lastly, 
 exposed to the air in the shade, in shallow wooden boxes, till it is thoroughly 
 
 INERTIA OF MATTER. The name given to a passive principle, by which 
 bodies persist in a state of motion, or rest, receive motion in proportion to the 
 force impressing them, and resist as much as they are resisted. See MECHANICS. 
 
 INFLAMMABILITY. That property in certain bodies which disposes 
 them to kindle or take fire readily. 
 
 INFUSION, is the operation of macerating or steeping any substance in 
 water or other fluid, hot or cold (but without boiling), so as to extract its soluble 
 parts. The liquid thus impregnated is called an infusion. 
 
 INGOT, is a term applied to small bars of gold, silver, copper, and other 
 metals, of a wedge-like shape in their transverse section. The metals are run 
 into this form for portability, the convenience of trade, and their easy application 
 in the arts. 
 
 INHALER. The name given to an apparatus having a breathing-pipe, by 
 which a patient inhales steam or other vapours, and sometimes particular gases 
 or airs, presumed to be beneficial in catarrhs, affections of the lungs, &c. 
 
 INJECTION. The operation of forcibly throwing any liquid or aeriform 
 fluid by means of a pump, syringe, or other suitable mechanism, into a vessel. 
 Thus, cold water is injected into the condenser of a steam-engine to effect a 
 vacuum. 
 
 INKS, are fluid compositions designed for writing, drawing, and printing 
 As there are a great variety of sorts, we shall treat them consecutively, 
 according to the following arrangement of the subject. 
 
 For Writing. 1. On black writing inks generally 2. On common black 
 writing ink. 3. On best, or Japan ink. . Copying ink. 5. Indelible, or 
 indestructible ink. 6. Red ink. 7. Indestructible red ink. 8. Blue ink. 
 9. Yellow ink. 10. Green, and other coloured inks. 11. Cloth-marking ink. 
 12. Sympathetic, invisible, or secret inks. 13. Lithographic ink. 
 
 For Drawing. 14. Indian, and imitation Indinn ink. 15. Lithographic ink. 
 for drawing on stone or paper.
 
 INKS. 741 
 
 For Printing. 16. Letter-press printing ink. 17. Red, and other coloured 
 ditto. 18. Copper-plate printing ink. 19. Lithographic printing ink. 
 For removing stains of ink, 20. 
 
 1. Black Writing Inks generally. When any vegetable matter, containing the 
 gallic acid, is infused with a solution of iron in water, the gallic acid unites 
 with the iron, and a black liquor results, from which the colour, in the form of 
 an impalpable powder, is gradually precipitated. To prevent the latter effect, 
 it becomes necessary to render the liquor viscid, or of greater specific gravity ; 
 and this is best effected by the addition of a gum which is perfectly soluble in 
 water, as this gum, besides keeping the black feculse suspended in the liquor, 
 serves also to prevent the ink from sinking or spreading on the paper, and 
 likewise to defend it, in the manner of a varnish, from the action of the air. 
 Ink may therefore be regarded as merely a gallate of iron, combined with a 
 little mucilage. It follows, from this view of the matter, that the same, or very 
 nearly the same, kind of black liquid may be produced from a great variety of 
 substances, and, therefore, to make ' ' *' 
 
 2. Common Slack Writing Ink. It becomes the business of the manufacturer to 
 select such materials as will produce the required quality at the least cost to 
 himself. It is commonly supposed that nut-galls are employed on a large 
 scale for this purpose, but the low price at which common ink is sometimes sold 
 per gallon, renders this improbable ; and that such an expensive material 
 (however good) is not necessary, the reader has only to consider that the dyer 
 makes a variety of good blacks without it. Of all known vegetable matters, 
 sumach approaches nearest to galls, and forms a very cheap substitute ; com- 
 bined with the sulphate of iron (green copperas) it makes a very rich black ink, 
 but it requires some peculiar management to prevent its becoming thick. 
 Logwood, from the great affinity of its colouring matter to the oxide of iron, 
 renders it a most desirable substitute for galls. It is well known to be partially 
 
 used with galls in making ink ; but very good common ink may be made from 
 it without any other astringent matter. Valonia, the barks of the oak, chestnut, 
 and many other trees, may be very advantageously applied as useful substitutes 
 
 for galls in making common ink, and are well deserving of the attention of the 
 manufacturer who may not be acquainted with their properties. A good common 
 ink is made in the following manner: Take 8 ounces of Aleppo galls, in coarse 
 powder, and 8 ounces of logwood, in thin chips ; boil these in six quarts of soft 
 water for an hour, and supply the waste from evaporation by the addition of 
 fresh water ; strain the decoction through a hair sieve, and then add 5 ounces 
 of sulphate of iron, and 3 ounces of gum Senegal, of ordinary quality. Stir the 
 mixture until the latter is dissolved, then let it subside for twenty-four hours, 
 after which, decant the ink, and preserve it in bottles of glass or stone ware for 
 use. This recipe, it is evident from the preceding remarks, may be considerably 
 varied ivithout material prejudice to the quality of the article ; but it should be 
 borne in mind that galls possess more intrinsic value (without reference to their 
 prime cost) than their substitutes, as a given weight of them yields a greater 
 quantity of black precipitate than any of the others ; the current price, as well 
 as the quality of the galls, will therefore have to be duly estimated, and in 
 apportioning the substitute a greater quantity must be used. 
 
 3. Best, or Japan Ink. M. Ribaucourt, who has paid particular attention to 
 the process of making black ink, "has drawn the following inferences from his 
 experiments. That logwood, from its disposition to unite with the solutions of 
 iron, is a valuable ingredient in the making of ink, rendering it not only of a 
 very dark colour, but less capable of change from the action of acids or of the 
 ah-. That sulphate of copper, in a certain proportion, gives depth and firmness 
 to the colour of the ink. That gum has all the advantages we have before 
 named. That sugar (although it has some bad qualities) is of use in giving a 
 degree of fluidity to the ink, which permits the dose of gum to be enlarged 
 beyond what the ink would bear without it. That water is the best solvent. 
 From these considerations M. Ribaucourt has given the following directions for 
 the composition of good ink, namely, 8 ounces Aleppo galls, 4 ounces logwood, 
 4 ounces sulphate of iron, 3 ounces gum arabic, 1 ounce sulphate of copper, 
 6 B
 
 742 INKS. 
 
 and 1 ounce of sugar candy The galls and logwood to be boiled in 12 Ibs 
 of water, till reduced to 6 Ibs. and after straining, the other ingredients are to 
 be added. This ink flows from the pen of a jet black, and from the gum being 
 in greater proportion to the liquid than in the previous recipe, the writing dries 
 with a gloss upon it ; hence it has been called Japan ink. If it is desired to 
 give it more gloss, the gum may be increased, to which some more sugar must 
 be added to give it equal fluidity ; but an excess in the latter ingredient renders 
 papers written upon with it liable to stick together, upon contracting the least 
 dampness. 
 
 M. Desormeaux, jun. an ink manufacturer of Spitalfields, gave an excellent 
 recipe for making ink some time since in the Philosophical Magazine ; but as 
 his process does not differ essentially from those we have given, and as his 
 observations are confirmatory, as far as they extend, of our own, we shall only 
 notice the points of difference in his communication. He directs the sulphate 
 of iron to be calcined to a whiteness, and employs coarse brown sugar instead 
 of sugar-candy, the acetate of copper instead of the sulphate, and only in one- 
 fourth the quantity ; and recommends the ink to be agitated twice a day for a 
 fortnight before it is poured from the dregs and corked up for use. These 
 variations appear to be judicious and deserving of imitation. 
 
 Dr. Lewis and others have recommended vinegar as the menstruum in pre- 
 ference to water ; on which, as well as the sulphate of copper of Mr. Ribaucourt, 
 Dr. Ure acutely observes, " I have found an inconvenience in the use of either, 
 which, though it does not relate to the goodness of the ink, is sufficiently great, 
 in their practical exhibition, to forbid their use. The acid of the vinegar acts 
 so strongly upon the pen, that it very frequently requires mending ; and the 
 sulphate of copper has a still more unpleasant effect upon the pen-knife. It 
 seldom happens that when a pen requires mending, that the ink is wiped very 
 perfectly from it; and often, when the nib is only to be taken off, it is done 
 without wiping at all. Whenever this is the case, the ink immediately deposits 
 a film of copper upon the knife, and by superior electric attraction of the 
 sulphuric acid, a correspondent portion of the edge of the knife is dissolved, 
 and is by this means rendered incapable of cutting until it has been again set 
 upon the hone. 
 
 4. Copying Ink, for transferring writings to thin unsized paper is prepared 
 by the simple addition of a little sugar to common writing ink. The powerful 
 affinity of water to sugar, causes the damp paper to immediately absord the 
 ink by the powerful aid of the copying-machine. See COPYING PRESS. 
 
 5. Indelible Ink. It is well known that common writing ink may be easily 
 obliterated by the application of oxymuriatic acid, or aqueous chlorine ; it 
 therefore becomes an important object" to employ those substances which shall 
 be indestructible by the application of any process that will not at the same 
 time destroy the material upon which it shall be used. For this purpose 
 Mr. Close has recommended twenty-five grains of copal in powder, dissolved in 
 two hundred grains of oil of lavender, by the assistance of a gentle heat, and 
 then mixed with two and a half grains of lamp-black, and half a grain of 
 indigo. A little oil of lavender, or of turpentine, may be added if the ink be 
 too thick. Mr. Sheldrake suggests that a mixture of genuine asphaltum, dis- 
 solved in oil of turpentine, amber varnish, and lamp-black, would be superior to 
 the foregoing. For many common purposes the introduction of a little lamp- 
 black into the composition of common ink will answer sufficiently. In the 
 Journal of the Royal Institution the following process of making an indelible 
 ink has been recommended : Let a saturated solution of indigo and madder in 
 boiling water be made in such proportion as to give a purple tint ; add to it 
 from one-sixth to one-eighth of its weight of sulphuric acid, according to the 
 thickness and strength of the paper to be used. This makes an ink which 
 flows pretty freely from the pen ; and when writing which has been executed 
 with it is exposed to a considerable but gradual heat from the fire, it becomes 
 completely black, the letters being thoroughly burnt in, and charred by the 
 action of the sulphuric acid. If the acid has not been used in sufficient quantity 
 to destroy the texture of the paper, and reduce it to tho state of tinder, the
 
 INKS. 748 
 
 colour may be discharged by the oxymuriatic and oxalic acids, and their rani- 
 pounds, though not without great difficulty. When the full proportion of acid 
 has been employed, a little crumpling and rubbing of the paper reduces the 
 carbonaceous matter to powder; but by putting a black ground behind them 
 they may be preserved ; and thus a species of indelible writing ink is procured, 
 (for the letters are in a manner stamped out of the paper) which might be 
 useful for some purposes, perhaps for the signature of bank notes. (See the 
 inks for marking linen.) When writing with common ink has been effaced by 
 means of aqueous chlorine, the vapour of sulphuret of ammonia, or immersion 
 in water impregnated with this sulphuret, will render it again legible. Or if 
 the paper that contained the writing be put into a weak solution of prussiate of 
 potash, and when it is thoroughly wet, a little suphuric acid be added to 
 the liquor, so as to render it slightly acidulous, the same purpose will be 
 answered. 
 
 6. Red Inks. Steep one pound of powdered Brazil wood, and one ounce of 
 powdered cochineal, in two gallons of vinegar. Let them macerate for twelve 
 hours. Then put the whole on to a slow fire, with four ounces of alum, and 
 one ounce of lump-sugar, in a pewter vessel, until a good red colour is 
 obtained. When the ink is settled it may be decanted, pouring it through a 
 piece of cloth into bottles, and preserved for use. Cochineal is a very expen- 
 sive article, and although it is usual to recommend its introduction into red ink, 
 on account of the richness of its colouring matter, we know from experience 
 that it is by no means a necessary ingredient, and that a beautiful and very 
 permanent red may be obtained without it. We have before us a recipe, 
 written fifteen years ago in the identical red ink it is descriptive of the process 
 of making ; the colour is extremely beautiful, nor in the least deteriorated by 
 the lapse of time. The process differs only from the above recipe in using no 
 cochineal, but it contained as much alum as the liquid would dissolve in its cold 
 state ; the Brazil wood was macerated during a night, and was very gently 
 boiled in an unglazed earthen pot on the next day, for half an hour ; afterwards 
 one pound of Senegal gum, and a quarter of a pound of lump-sugar, were 
 added. With so large a proportion of mucilage as just mentioned, and so much 
 alum, it is probable that vinegar may be dispensed with, and that water alone, 
 which is a good menstruum for the colouring matter of Brazil wood, will answer 
 very well, and materially cheapen the ink. Care should be taken to discontinue 
 the boiling after the full bright red is obtained, as by continuing it the colour 
 darkens ; also, that copper or iron vessels should not be used, unless they are 
 perfectly coated with tin in every part. A solution of tin heightens the red 
 colour, and tends to restore it, if it has acquired a purple tint 
 
 7. Indestructible Red Ink may be made by dissolving one ounce of copal in 
 seven ounces of oil of lavender, and adding thereto three ounces and a half of 
 pure vermilion. If found too thick for the pen, add a little more oil of 
 lavender. 
 
 8. Blue Ink. Take sulphate of indigo (indigo dissolved in sulphuric acid, it 
 may be had of the dyers), and dilute it with water till the desired tint is 
 obtained. It is with this sulphate, very largely diluted, that the faint blue lines 
 of ledgers and other books are ruled. If the ink were used strong, it would be 
 necessary to add chalk to it, to neutralize the acid. 
 
 9. Yellow Ink. Half a pound of French berries, boiled with a little alum in 
 a quart of water, or vinegar and water. 
 
 10. Green and other coloured Inks. A mixture of the above blue and yellow 
 inks will make a green ; a mixture of the red and yellow will make an orange ; 
 of the blue and red, a purple ; of the black and yellow, a brown. Inks of all 
 colours may, however, be very readily obtained by rubbing down with water 
 any of the water-colours prepared in cakes, for artists ; or by using a strong 
 decoction of any of the ingredients used in dyeing, with a little alum and gum. 
 
 11. Marking Linen. Mr. Haussman has given some compositions for marking 
 pieces of cotton and linen, previous to their being bleached, which are capable 
 of resisting every operation in the processes both of bleaching and dyeing, and 
 consequently might be employed in marking linen for domestic purposes. One
 
 ,4 INKS. 
 
 of these consists of asphaltum, dissoh'ed in about four parts of oil of turpentine, 
 and with this is to be mixed lamp-black or black-lead in fine powder, so as to 
 make an ink of a proper consistence for printing with types. Another, the 
 blackish sulphate left after expelling oxygen gas from oxide of manganese with 
 a moderate heat ; being dissolved and filtered, the dark grey pasty oxide left 
 on the filter is to be mixed with a very little of a solution of gum tragacanth, 
 and the cloth marked with this is to be dipped in a solution of potash or soda, 
 mild or caustic, in about ten parts of water. The anacardium, or cashew nut, 
 it is well known, yields an inflammable caustic liquor, which alone forms a 
 very useful marking ink, as any thing written on linen or cotton with it is of a 
 brown colour, which gradually grows blacker, and is very durable. The ordi- 
 nary marking ink sold in our shops is made in the following manner : Take 
 lunar caustic (nitrate of silver), 5 scruples ; gum arabic, 5 scruples ; sap-green, 
 1 scruple ; water, 1 ounce ; put these together in a small bottle, and the ink 
 is formed. In using it, the linen is first wetted with the following mordant ; 
 1 ounce of soda to 2 ounces of water. The marking ink should not be used 
 until the mordant has dried upon the linen. 
 
 12. Sympathetic, Invisible, or Secret Inks, are such as do not appear after they 
 are written with, but which may be made visible at pleasure, by certain means 
 used for that purpose. They are of considerable antiquity ; for it appears that 
 Ovid recommends the maidens of his days, who wished to correspond secretly 
 with their lovers, to write with fresh milk, which when ^dried might be made 
 visible by rubbing over it ashes or rust. J*liny, who was better informed than 
 Ovid in such arts, though probably less inclined to practise them, recom- 
 mended the milky juice of certain plants for the purpose ; but the use of such 
 things is superseded by the discoveries of modern chemists, who have intro- 
 duced to our notice a great variety of secret inks, the best of which we find 
 selected in the Oxford Cyclopedia , they are as follow : Dissolve some sugar 
 of lead in water, and write with the solution. When dry, no writing will be 
 visible. When you want to make it appear, wet the paper with a solution of 
 alkaline sulphuret (liver of sulphur,) and the letters will immediately appear of 
 a brown colour. Even exposing the writing to the vapours of these solutions 
 will render it .apparent. Write with a solution of gold in aqua-regia, and let 
 the paper dry gently in the shade : nothing will appear ; but draw a sponge 
 over it, wetted with a solution of tin in aqua-regia, the writing will immediately 
 appear of a purple colour. Write with an infusion of galls, and when you wish 
 the writing to appear, dip it into a solution of green vitriol ; the letters will 
 appear black. Write with diluted sulphuric acid, and nothing will be visible. 
 To render it so, hold it to the fire, and the letters will instantly appear black. 
 Juice of lemons or onions, a solution of sal ammoniac, green vitriol, &c. will 
 answer the same purpose, though not so easily, nor with so, little heat. 
 
 Green Sympathetic Ink. Dissolve cobalt in nitro-muriatic acid, and 
 write with the solution. The letters will be invisible till held to the fire, when 
 they will appear green, and will disappear completely again when removed 
 into the cold. In this manner they may be made to appear and disappear at 
 pleasure. A very pleasant experiment of this kind is to make a drawing 
 representing a winter scene, in which the trees appear void of leaves, and to 
 put the leaves on with this sympathetic ink ; then upon holding the drawing 
 near to the fire, the leaves will begin to appear in all the verdure of spring, and 
 will very much surprise those who are not in the secret. 
 
 Blue Sympathetic Ink. Dissolve cobalt in nitric acid ; precipitate the 
 cobalt by potass ; dissolve this precipitated oxide of cobalt in acetic acid, 
 and add to the solution one-eighth of common salt. This will form a 
 sympathetic ink, that, when cold, will be invisible, but will appear blue 
 by heat. 
 
 13. Lithographic /&. As the art of lithography is treated of generally 
 
 its initial letter in this work, we shall in this place simply notice the 
 
 autographic ink, suitable for transferring to stone the writings or drawings which 
 
 have been executed on paper prepared for th'e purpose. This ink ought to be 
 
 mellow, and somewhat thicker than that used for drawing or writing imme-
 
 INKS. 744 
 
 diately on stone ; so that when it is dry on the paper, it may be still sufficiently 
 viscous to cause it to adhere to the stone by simple pressure. The follow- 
 ing is the mode of preparing it : dry soap, i 00 drachms ; white wax, pure, 
 100 ditto; mutton suet, 30 ; shellac, 50; mastic 50 ; and lamp-black, (fine, from 
 the combustion of resin,) 30 to 35 drachms. These are to be melted over 
 a brisk fire in a metal pot over a chafing dish ; first melt the soap and the 
 suet, then add the shellac very gradually ; next the soda, a little at a time, and 
 after this the mastic, taking care to stir it from time to time with a wooden 
 spatula; lastly the lamp-black, stirring it all the time. When these materials 
 are well incorporated, they are poured on a plate of cast iron, made warm, and 
 oiled, in order that the composition may be easily detached from it. Ledges of 
 wood are put on the plate to keep the thickness of the composition uniform, 
 which when congealed, but still warm, is cut into sticks, like Indian ink. 
 
 14. Indian Ink. The genuine article, which is used by the Chinese for 
 writing with a brush, as well as for painting upon their soft, flexible paper, is 
 ascertained by experiment and information to consist of lamp-black and size, 
 animal glue, with the addition of perfumes or of other substances not essential 
 to its quality as an ink. The fine soot from the flame of a lamp or candle, 
 received by holding a plate over it, mixed with clean size from shreds of parch- 
 ment of sheep and goat skins, will make an ink equal to that imported. We 
 have been in the habit of using, during many years, both the genuine and 
 the imitation Indian ink indifferently, without being able to discover that either 
 merits a preference. 
 
 15. Lithographic Drawing Ink. This composition is the same as the ink 
 used for writing upon stone and lithographic transfer paper, already described ; 
 the artist rubbing it down usually upon a slab, as Indian ink, for his use. 
 
 16. Letter-press Printing Ink is a very smooth and jet black oil paint. 
 The consistence and tenacity of the oil in this composition are greatly increased, 
 and its greasiness diminished, by means of fire. Linseed oil, or nut oil, is 
 made choice of for this use. The nut oil is supposed to be the best, and is 
 accordingly preferred for the black ink, though the darker colour it acquires 
 from the fire renders it less fit for the red. It is said, that the other expressed 
 oils cannot be sufficiently freed from their unctuous quality. Ten or twelve 
 gallons are set over the fire in an iron pot, capable of holding at least half as 
 much more ; for the oil swells up greatly, and its boiling over into the fire 
 would be very dangerous. When it boils, it is kept stirring with an iron ladle ; 
 and if it do not of itself take fire, it is kindled with a piece of flaming paper 
 or wood. It is found that mere boiling, without setting it on fire, does not 
 give it a sufficiency of the drying quality. The oil is suffered to burn for half 
 an hour or more, and is then extinguished by covering the vessel close, and 
 excluding the air. The boiling is continued with a gentle heat, till the oil has 
 attained the proper consistency, in which state it is called varnish. It is neces- 
 sary to have two kinds of this varnish, a thicker and a thinner, (from the 
 greater or less boiling it has received,) which are occasionally mixed together, 
 to suit different purposes ; for that which answers well in hot weather, becomes 
 too thick in cold, and large characters or type do not require such stiff ink as 
 the small. The thickest varnish, when cold, may be drawn into threads, like 
 glue ; and the workmen taking out small quantities, from time to time, judge 
 of the proper degree of boiHng required, by testing its tenacity in that manner. 
 The oil loses by the boiling about one-eighth of its weight. The varnish readily 
 mingles with fresh oil, and it will unite with mucilages, into a mass that is after- 
 wards diffusible in water. About one-seventh part, by weight, of lamp-black 
 is added to the varnish, to give it the depth of colour. Boiled with caustic 
 alkali, a soapy compound is formed, and printers availing themselves of this 
 fact, are in the habit of cleaning their types by soap-makers' lees and a brush. 
 It is said that when very new oil is used in making ink, it does not readily 
 dry without the addition of litharge, or the oil of turpentine, and these addi- 
 tions (which are not necessary in old oil) cause it to stick very hard to, and 
 ciog up the types. 
 
 17. Red and other coloured Printing Inks, are made from linseed oil, boiled
 
 746 
 
 INKSTANDS. 
 
 into a varnish, as described in the black ink, with the addition of some dry 
 pigment of the required colour, which is ground up with the varnish, with a 
 stone and muller in the manner of oil paint. Thus, for preparing the bright 
 red printing ink, vermilion is ground up with the varnish, in such quantity as 
 will give the required depth of tint. In like manner for blues, yellows, oranges, 
 greens, &c. the Prussian blue, indigo, orpiment, chrome, red and orange lead, 
 verdigris, and in general the pigments used by house painters, are similarly 
 combined with the varnish. 
 
 18. Copperplate Printing Ink is of a somewhat similar kind to that used for 
 type printing, but the oil is less boiled, and the varnish is in consequence much 
 more fluid ; and instead of lamp-black, they either use the black imported 
 from Frankfort, (which is said to be the charcoal of vine twigs, prepared in a 
 peculiar manner,) or when this cannot be procured, or is too costly, the finest 
 ivory black they can obtain. 
 
 1 9. Lithographic Printing Ink differs from that used in typography, only in 
 being a much thicker varnish ; and the lamp-black which is used as the colour- 
 ing matter is not mixed with it in the mass, but small portions of the varnish 
 are taken from time to time, as it is required, and the lamp-black then only 
 ground up with it for immediate or very early use. See LITHOGRAPH y. 
 
 20. Removing Stains of Ink. The stains of ink on cloth, paper, or wood, may 
 be removed by almost all acids ; but those acids are to be preferred which are 
 least likely to injure the texture of the stained substance. The muriatic acid, 
 diluted with five or six times its weight of water, may be applied to the spot, 
 and after a minute or two may be washed off, repeating the application as often 
 as may be found necessary. But the vegetable acids are attended with less 
 risk, and are equally effectual. A solution of the oxalic, citric (acid of lemons), 
 or tartaric acids in water, may be applied to the most delicate fabrics, without 
 any danger of injuring them ; and the same solutions will discharge writing, 
 but not printing ink. Hence they may be employed in cleaning books that 
 have been defaced by writing on the margin, without impairing the text. 
 Lemon-juice, and the juice of sorrel, will also remove ink stains, but not so 
 easily as the concrete acid of lemons, or citric acid. 
 
 INKSTANDS. Utensils for holding ink for the convenience of dipping a 
 pen into them. They were formerly chiefly made of horn, but now generally 
 of glass or metal. It is not our intention to describe the ordinary kinds, that 
 are familiar to every eye, but only the recent elegant improvements which have 
 been made upon, them. 
 
 Edwards s Patent Inkstand is one 
 of great convenience and stability, 
 and not very liable to get out of order. 
 It is represented in the subjoined en- 
 graving, which affords a sectional view 
 of the interior, a a shows the top and 
 bottom of an external cylindrical 
 casing of bronze, b is the ink imbibed 
 by a quantity of loose hair or wool, 
 contained in a cylindrical glass cup 
 c c, of considerable thickness, the upper 
 part of which is closed by a glass pis- 
 ton d, accurately ground to fit the 
 cylinder, and so as to permit it to move 
 easily up and down. On the upper 
 surface of the glass piston, a hollow 
 screw e with a disc of metal at the 
 end, is made to operate by pressure 
 downwards, when the top piece / is 
 turned by the finger and thumb ; the 
 latter turns the solid screw, and causes 
 the hollow screw to advance or recede 
 with a sliding motion, so as to press
 
 INKSTANDS. 
 
 7*7 
 
 uniformly upon the piston without the friction of turning against its surface. 
 At the lower part of the reservoir, an aperture is made, into which a tube 
 is fixed that conducts the ink to a little pen-supplying cup g, when the wool is 
 compressed by a turn of the screw, forcing down the piston. The little cup, 
 previously empty, is thus instantly supplied with fresh ink, with no more trouble 
 than taking up a pen ; and should a little more ink be forced into the cup than 
 is necessary, by carelessly turning the screw too far, it runs over, and is caught 
 in the little saucer shown below. When the inkstand is not in requisition, a 
 half turn of the screw the reverse way causes the ink to flow back again, as 
 the wool being thereby relieved of the pressure, re-absorbs the fluid. The ink 
 being thus returned into the reservoir, none can be spilled, even if upset ; it is 
 preserved from the contact of the air, consequently from drying up, as well as 
 from dust, and it may be instantly brought into use whenever required. These 
 are decided advantages, which peculiarly recommend it for the use of persons 
 travelling. 
 
 Patent Caoutchouc Inkstand. Mr. Doughty, the ingenious manufacturer of 
 pens with ruby and rhodium nibs, having discovered the injury that those pens 
 received from being incautiously struck against the glass of common inkstands, 
 contrived to manufacture an interior bottle of Indian rubber, of nearly the form 
 of the external ornamental case, as shown in the annexed section of one of his 
 
 elegant inkstands. The stopper is of a conical form, and is so fixed in the 
 screwed head or cap as to have a little lateral play therein, which admits of 
 its adapting itself exactly to the conical neck of the inkstand, and when 
 screwed down, prevents the possibility of leaking ; and that the ink may not 
 corrode the metal stopper, the latter is coated with gold or platinum. 
 
 Horsley and Coopers Patent Inkstand. The peculiarity in this invention 
 consists in the forming of convenient and perfectly air-tight stoppers, in a 
 substance not liable to corrode. It is effected by bringing into contact two 
 circular discs of glass, the flat surfaces of which being ground to true planes, 
 are opposed to each other and united by a central pivot, rivetted to a bar of 
 metal fixed above them, across the mouth of the vessel. Each plate has an 
 nperture of proper dimensions for dipping the pen, and the upper plate is
 
 7 '18 
 
 IODINE AND IODIC ACID. 
 
 provided with two projecting studs, at equal distances from the central pivots. 
 The thumb and fore finger being applied to these two studs, the upper disc is 
 easily turned either to the right or left ; one way brings the apertures opposite 
 to each other, which opens the inkstand, and being moved the other way, the 
 unperforated part of the upper disc is slided over the stationary aperture of the 
 lower, and perfectly closes it. The p- t g j_ 
 
 rubbing surfaces are slightly oiled, 
 which renders the motion smooth 
 and easy, and the sealing perfect. 
 Fig. 1. affords a perspective view 
 of an inkstand of this kind, made 
 of very thick cut glass; the discs 
 or stoppers of which are sur- 
 rounded by a metallic ring, and 
 kept down in their places by an 
 horizontal metallic bar, into which 
 the pivot of the discs is fitted. In 
 this figure it will be perceived that 
 the inkstand is shut, the aperture 
 in the upper plate being over the 
 unperforated part of the lower. On 
 turning the studs a quarter round, 
 they are stopped by striking against 
 the cross bar, when the two holes 
 coincide, (as shown in the annexed 
 sections), by which the inkstand is 
 opened. Underneath the bar (which 
 is shown by a transverse section) a 
 steel spring is fixed, which keeps the 
 discs in close yet easy contact. The 
 advantage of this contrivance con- 
 sists in the facility and expedition , 
 with which the inkstand may be opened and closed air tight, the simplicity of 
 the construction, and the incorruptibility of the materials. 
 
 INSOLATION. A method of preparing certain fruits, drugs, c. by expos- 
 ing them to the heat of the sun's rays, either to dry, to maturate, or to render 
 them acid ; as is done in figs, raisins, vinegar, and many other products. 
 
 INTAGLIOS. Precious stones, on which are engraved the heads of eminent 
 men, such as are usually set in seals, rings, &c. 
 
 INTEGER, in Arithmetic, signifies a whole number, in contradistinction to 
 a fraction. 
 
 INTEGRAL, in Philosophy, is an appellation given to parts of bodies which 
 are of a similar nature to the whole. 
 
 INTEGRAL CALCULUS is the reverse of the differential calculus, and is 
 the finding of the integral from a given differential, and corresponds with the 
 inverse method of fluxions. 
 
 INTERMEDIATES. A term made use of in Chemistry in relation to affi- 
 nity ; thus, oil has no affinity to water unless it be previously combined with an 
 alkali; it then becomes soap, and the alkali is said to be the intermedium which 
 causes the union. 
 
 INTRADOS. The internal curve of the arch of a bridge. 
 
 INVERSE PROPORTION, OR INVERSE RATIO, in Philosophy, is that in 
 which more requires less, or less requires more. Thus in the case of light and 
 heat flowing from a luminous body, the light and heat are less at a greater dis- 
 ance and greater at a less distance. 
 
 IODINE AND IODIC ACID. Iodine is a peculiar and compounded prin- 
 ciple ; it was discovered in Paris in 1811 by M. Courtois, a saltpetre manufac- 
 turer, who observed a rapid corrosion of his vessels in his processes for obtaining 
 soda from the ashes of sea weeds ; and in searching for the cause of the corro- 
 sion, he made the discovery of this important substance. It is from sea weeds
 
 IRIS METAL ORNAMENTS. 7J9 
 
 alone that iodine can be obtained ; it has not yet been decomposed ; it is of a 
 greyish-black colour, and metallic lustre ; soft and friable to the touch ; taste 
 acrid, and a deadly poison. It gives a brown stain to the skin, which speedily 
 vanishes by evaporation. The specific gravity of iodine at 62, is 4.948 : it 
 dissolves in 7,000 parts of water, and the solution is of an orange yellow colour, 
 and in small quantities tinges raw starch of a purple hue. Iodine is incom- 
 bustible ; but with azote it forms a detonating compound, and in combining 
 with several bodies it produces the phenomenon of combustion. The oxide of 
 sodium, and the subcarbonate of soda are completely decomposed by it. It forms 
 with sulphur a compound of greyish black, radiated like sulphuret of antimony. 
 Iodine and phosphorus combine with great rapidity at common temperatures, 
 and produce heat without light. Hydrogen, whether dry or moist, does not 
 seem to have any action on iodine at the ordinary temperature ; but if we 
 expose a mixture of hydrogen and iodine to a red heat in a tube, they unite 
 together, and hydriodic acid is produced, which gives a reddish brown colour 
 to water. Charcoal has no action upon iodine. Several of the metals, as zinc, 
 iron, tin, mercury, attack it readily, even at a low temperature, provided they 
 be in a divided state. Iron is acted upon by iodine in the same way as zinc, and 
 a brown iodine results. Antimony presents with iodine the same phenomena 
 as tin. The iodines of lead, copper, bismuth, silver, and mercury, are insoluble 
 in water ; this is at least the case with the above-mentioned metals. There are 
 two iodines of mercury ; the one yellow, the other red ; both are fusible and 
 volatile. When iodine and oxides act upon each other in contact with water, 
 its hydrogen unites with iodine to form hydriodic acid ; while its oxygen, on 
 the other hand, produces with iodine iodic acid. Iodine of mercury has been 
 proposed for a pigment. Iodine has been most successfully applied medicinally 
 for reducing the goitre and glandular swellings. See Ure's Dictionary. 
 
 IRIDIUM. A new metal, to which that name was given by its discoverer, 
 Mr. Tennant, from the striking variety of colours it affords whilst dissolving in 
 muriatic acid. On examining the black powder left after dissolving platina, 
 Mr. Tennant found it to coi.tain two distinct metals never before noticed, which 
 he named iridium and osmium. Lead unites with indium easily, but separates 
 by cupellation, leaving the iridium in the cupel as a coarse black powder. 
 Copper forms with it a very malleable alloy, which, after cupellation, with the 
 addition of lead, leaves a small proportion of the iridium, but much less than 
 in the preceding instance. Silver forms with it a perfectly malleable compound, 
 the surface of which is tarnished merely by cupellation : yet the indium appears 
 to be diffused through it in fine powder only. Gold remains malleable and 
 little altered in colour, though alloyed with a considerable proportion ; nor is it 
 separable either by cupellation or quartation. If the gold or silver be dis- 
 solved, the iridium is left as a black powder. 
 
 IRIS METAL ORNAMENTS. A patent was taken out a few years ago 
 by Mr. Barton, of the Mint, for a very ingenious method of ornamenting 
 steel and other metals with the prismatic colours. It is effected by engraving 
 with an engine lines on the surface of the metals of extreme minuteness, so as 
 to divide a lineal inch into from 2000 to 10,000 equal parts. Mr. Barton has 
 sometimes proved the correctness and stability of his engine, when drawing 
 lines 2000 in an inch, by leaving out one line intentionally, then taking the 
 machine to pieces ; afterwards, on putting it together again, he has introduced 
 the omitted line in its place, without causing it to be distinguishable from the 
 rest. 
 
 In applying the principle of striated colours to ornament steel, the effect or 
 pattern is produced upon the polished surface by the point of a diamond ; so 
 that either the whole, or a part of the surface, is covered with lines or grooves, 
 whose distance may vary from the one-thousandth to the ten-thousandth of an 
 inch. When these lines are most distant, the prismatic images of any luminous 
 body, seen by reflection from the polished surface, are nearest one another, and 
 the common colourless image ; and when the lines are least distant, the coloured 
 images are farthest from one another, and the colours are most vivid. In day- 
 light the colours produced by these minute grooves are scarcely distinguished, 
 5 c
 
 750 
 
 IRON. 
 
 unless at the boundary between a dark and a luminous object. In sharp 
 lights, however, and particularly in that of the sun, the colours shine with ex- 
 traordinary brilliancy, and the play of tints which accompany every luminous 
 image can only be equalled by their matchless exhibition in the reflections of 
 the diamond. Steel dyes are engraved in this manner, from which impressions 
 are afterwards taken for the fabrication of various articles, in which the design 
 of the original is very faithfully transferred. 
 
 IRON. A metal of a bluisb-white colour, of great hardness and elasticity; 
 very malleable, and exceedingly tenacious and ductile. It is the most abundant, 
 the most important, and the most valuable of all the metals. Although a simple 
 undecompounded substance, it is not naturally found in this state, except in 
 comparatively minute quantities, but is the product of art. Some specimens 
 of native iron, nearly pure, have been found in Siberia and South America ; 
 also many iron stones, rich in the metal, supposed to be of volcanic or 
 meteoric origin, have been found in numerous parts of the earth ; but all the 
 iron of commerce is obtained by chemical means. Iron is so universally dif- 
 fused as to form a constituent part of almost all animal, vegetable, and mineral 
 substances. Unlike metals of inferior utility, its ores are not distributed in 
 thin veins, or scattered in minute particles, but are thickly stratified over 
 many thousands of square miles, chiefly in the northern regions of the earth, 
 where nature has been less profuse of her other benefits. The use of this metal 
 is of very great antiquity, though, on account of the difficulty of separating it 
 from its ores, and of working it, probably not so remote as the employment of 
 gold, silver, copper, and other comparatively soft me als, which are in many 
 places found in a pure metallic state. It is stated by some writers, that iron is 
 mentioned by Moses as the material of which knives and swords were fabri 
 cated ; and that Herodotus mentions the presentation of a saucer, or vase of 
 iron, very curiously inlaid, by Alyattes, king of Lydia, to the Delphic oracle. 
 Later and more erudite writers have, however, maintained that the words of 
 those ancient authors have been most incorrectly translated into our language ; 
 and that the working and use of iron was unknown at those periods. At what 
 time the manufacture of iron was first attempted in Britain, cannot be precisely 
 ascertained. Some suppose (for it is in reality only a probable conjecture) that 
 the Phoenicians who wrought the tin mines of Cornwall, introduced into the 
 country men who were skilled in metallic ores, and capable of estimating their 
 value, by applying the minerals to such purposes as their own necessities or 
 the wants of the inhabitants might require. There is, however, much evidence 
 to favour the belief that iron was worked in this country during the time it was 
 in occupation by the Romans ; and that during the establishment of the Danes 
 in England, the arts of mining and manufacturing the ores of iron were much 
 improved. It appears that the manufacture was at that period chiefly directed 
 to the fabrication of malleable iron, in what were called foot-ilasts, of a similar 
 nature to those still used in remote uncivilized countries, of which Dr. Davy 
 has furnished us with an example in a Singalese smelting house of the present 
 day. The simplicity and cheapness of construction of this furnace is extremely 
 interesting, as showing what may be effected by very limited means, and that 
 the large capitals and immense laboratories employed by our present iron 
 manufacturers, however necessary they may be to the production of a large 
 quantity of the metal, are by no means essential to the production of a good 
 quality; for it has been generally remarked, that the ruder the method employed 
 in any country for the reduction of iron, the better the quality of the metal is. 
 The observation holds good in Ceylon, and there is obvious reason why it should 
 e correct. Where the art is little advanced, the most tractable ores are selected, 
 and charcoal is the fuel always used, circumstances which are alone sufficient 
 to account for the iron obtained being excellent. Each furnace was, at its 
 mouth, about 1 foot and 4 inches, by 8 inches in diameter; about 3 
 feet deep, and terminated in the form of a funnel, over a shallow pit inclining 
 outwards. They were made in a bed of clay about 3 feet high, and 3 feet 
 wide, against which a light wall, about 10 feet high, was raised to protect the 
 bellows and operator, who was situated immediately behind. Each hollows
 
 JL10N. 761 
 
 consisted of a circular rim of wood, about 6 inches in diameter, and scarcely 2 
 inches high, fixed on a clay floor, and covered with moist cow-hide ; in the 
 centre of which was a hole to admit air, and to receive a cross stick, to which 
 a cord was attached that was fastened above to an elastic stick. Each pair oi 
 bellows was worked by a boy, who rested his back against a rope for the pur- 
 pose of support, and stepped alternately from the orifice of one bellows on to 
 that of the other, at each step forcing a blast of air into the furnace through a 
 
 
 tube of bamboo. The furnaces were charged with a mixture of iron ore, 
 broken into small pieces, and charcoal. The fires were kept up as strong as 
 possible till the ore was reduced, and the fused metal collected in a cake in the 
 ash-pit. 
 
 At the time when foot-blasts were used for separating the metal, the art of casting 
 iron was either altogether unknown, or in a state that it could not be prosecuted 
 with advantage. In the reign of Elizabeth, blast furnaces were of a sufficient 
 size to produce, with ores and the charcoal of wood, from two to three tons of 
 pig-iron per day, or from fifteen to twenty tons per week. It was only, how- 
 ever, in the most favourable situations for procuring water-power that such 
 great products were obtained, and the greatest proportion of it was converted 
 into bar-iron by means of the refinery fire ; but in many of the small works 
 the iron was " matured," that is, made malleable, before it was drawn from the 
 furnace. Wood, however, becoming scarce, or being engrossed by the great 
 manufacturers, induced several enterprising individuals to attempt the substi- 
 tution of pit coal for making pig-iron. Mr Simon Sturtevant, 1612, had a 
 patent granted to him, for thirty-one years, for that purpose. By the terms of 
 his patent he was bound to publish the nature and process of his invention, 
 which he did, in a quarto book, entitled Metallica; this book, Mr. Gray says, 
 does not contain a particle of useful knowledge, but that it is an extremely 
 curious specimen of the pedantry usual in James's reign. Sturtevant failed in 
 executing his proposed plans, and was obliged, the following year, to render up 
 his letters patent, or monopoly. John Ravenson, Esq. succeeded Sturtevant it 
 1613, had a patent granted to him, wrote his book, entitled "A Treatise of 
 Metallica, but not that which was published by Mr. Simon Sturtevant." Raverison 
 states, that at that time an iron work usually required from 10001. to 1500/. to 
 set it a-going, but that on his plan a capital of 100/. was fully adequate to 
 \rommence a work. The furnace itself was to cost but 10/. except the stones, 
 such furnace being capable of producing a ton of sow iron from each ton of pit 
 coal. This man, however, failed in his attempts to prove the correctness of his 
 statements, and resigned his patent. Several other unfortunate adventurers 
 followed Ravenson in succession, who also obtained patents, failed in their 
 
 undertakings, and resigned their privileges. It is a singular fact, that although 
 pit coal was known long before this period, and 
 
 great quantities of it wers
 
 752 IRON. 
 
 exported to Holland and the Low Countries, where it was used in the smith s 
 forge, and in other manufactories that require a strong continued heat ; yet in 
 England the prejudice against its use in the manufacture of cast iron was so 
 inveterate, that when it was first proposed and attempted, every obstacle that 
 could be devised was thrown in its way, and none of the adventurers succeeded, 
 until the year 1619, when Dudley had a patent, and manufactured pig-iron in 
 a Mast furnace, but produced only three tons in a week. He became, however, 
 the object of jealousy to the other manufacturers, who contrived to get his 
 patent limited from thirty-one to fourteen years, and his devoted works were 
 destroyed by a lawless mob, urged, it is supposed, by his rivals in business. 
 Soon after this, Captain Buck, Major Wildman, and some others, constructed 
 air furnaces in the forest of Dean, in which they placed large clay pots (similar 
 to those used in glass-houses) for containing the requisite preparations of ore 
 and charcoal, the flame of pit coal being employed for heating the furnaces ; 
 and it was expected, that by tapping the pots below, the separated material 
 would flow out. But the heat was not sufficiently intense to produce an entire 
 separation of the metal, the pots cracked, and the scheme was abandoned. At 
 this time iron was advancing, in consequence of many of the iron works having 
 stopped for want of fuel. To those manufacturers, therefore, who could still 
 be furnished with a supply of wood, the manufacture was highly profitable, 
 and they obstinately opposed any new attempt by which the price of iron 
 might be diminished. It was not till impelled by necessity, arising from the 
 rapid decline of the annual growth of timber, that pit coal became an object 
 of universal estimation. In this feeling the Hon. Robert Boyle seems to have 
 participated, for in his Usefulness of Natural Philosophy, published in 1663, he 
 expresses a desire that some method could be found to make coke without the 
 use of pots employed for that purpose, in order that it might be applied to the 
 smelting of iron ores. Two years after this, Dudley (according to Mr. Gray) 
 wrote his Metallum Martis, in which he states, that his father and himself had 
 smelted iron with coke in large quantity, but that Oliver Cromwell, and some 
 favourites of his, wishing, on renewal of the patent, to become partners, and 
 from other political circumstances, the establishment was ruined, and it seems 
 never to have been revived; for even so late as the year 1747, Mi. Mason 
 says, in the Philosophical Transactions, that several attempts have been made 
 to melt iron ore with pit coal, but he thinks it had not then succeeded any 
 where, as no account of its being practised had been published, but that 
 Mr. Ford did, however, then make pig iron, brittle or tough, as he pleased, 
 from iron and coal, both of which were procured on the same spot. 
 The brittle or inferior quality of English bar iron, made from coke at this 
 period, and the great expense of that which was made from charcoal, owing to 
 the increasing scarcity of wood, was most likely the cause of the great decline 
 in the home manufacture of iron which then took place ; recourse having been 
 had to Sweden and Russia for a supply, the importation of which on a great scale 
 at this time commenced. The home manufacture was, however, again renewed 
 by the general introduction of the steam engine ; and this afforded the manufacturer 
 the command of a power he had before no conception of. The small furnaces 
 supplied with air from bellows worked by oxen, horses, or men, were given up ; 
 larger furnaces were introduced, and blowing machines, with an increase of 
 the volume of air, for exciting a more vivid combustion. The steam engine 
 was found particularly beneficial in those situations where there was an abun- 
 dance of minerals for making iron, but a deficiency of water to supply the 
 power. Experience also soon taught the manufacturer, that the produce of his 
 furnace could be increased by enlarging the diameter of his steam cylinder 
 and rendering the vacuum therein more perfect. It was soon found, that by 
 increasing these effects, a quantity of pig-iron could be produced from the coke 
 of pit coal, which would be attended with an adequate profit. Owing to the 
 small quantity of air necessary to ignite, and preserve the required heat in a 
 charcoal furnace, the manufacturers very cautiously enlarged the dimensions of 
 their blowing apparatus in applying it to coke ; consequently much of the 
 advantage resulting from a great blast (which is now extended to about 4000
 
 IRON. 753 
 
 cubic feet of air JM.T minute) was lost. These difficulties were, however, 
 gradually surmounted, and it appears, that before the year 1760, the coke of 
 pit coal was in general use for blast furnaces. The iron trade assumed new 
 vigour, and made most rapid progress, as will appear from the following state- 
 ment of the total quantity of iron made in Great Pritain between the years 
 1740 and 1827. Since the latter period, the manufacture and trade has been 
 on the increase, notwithstanding the price has advanced. 
 
 In the year 1740, 17,000 tons were made from 59 furnaces. 
 
 1788, 68,000 tons 121 
 
 1796, 125,000 tons 
 
 1806, 250,000 tons 
 
 1820, 400,000 tons 
 
 1827, 690,000 tons 284 
 
 Of which latter quantity there were produced 
 
 By Staffordshire .... 216,000 tons from 95 furnaces. 
 
 By Shropshire .... 78,000 31 
 
 By South Wales . . . 272,000 90 
 
 By North Wales . . . 24,000 12 
 
 By Yorkshire .... 43,000 24 
 
 By Derbyshire .... 20,500 14 
 
 By Scotland 36,500 18 
 
 Total .... 690,000 284 
 
 In the foregoing statement, several furnaces in Gloucestershire, Cheshire, and 
 other places are omitted, which will render the produce in round numbers 
 700,000 tons. About three-tenths of this quantity are of a quality suitable to 
 the foundry, which is all used in Great Britain and Ireland, with the exception 
 of a small quantity exported to France and America. The other seven-tenths 
 are made into bars, rods, sheets, wire, &c., of which a large quantity is exported 
 to all parts of the world. Having thus given a brief historical sketch of the 
 rise and progress of this interesting and useful manufacture, we proceed to lay 
 before our readers a concise account of the process by which iron is obtained 
 from its ores, and brought into a crude or pure state, adapted to the wants of 
 mechanics, or to the various uses to which it is applied. 
 
 Making of Coke. The first operation is the preparation of the coal, to reduce 
 it to the state of coke, which is accomplished either in kilns, or in the open air. 
 The latter plan has been, and is still, the most extensively adopted ; we shall 
 therefore describe it the first. An oblong square hearth is prepared, by heating 
 the earth to a firm" flat surface, and paddling it over with clay. On this the 
 pieces of coal are piled up, inclining toward one another ; and those of the 
 lower strata are set upon their acutest angle, so as to touch the ground with 
 tbe least surface possible. The piles are usually from 30 to 50 inches high, 
 from 9 to 16 feet broad, and contain from 40 to 100 tons of coal. A number 
 of vents are left, reaching from top to bottom, into which the burning fuel is 
 thrown ; and they are then immediately closed with small pieces of coal beaten 
 hard in. Thus the kindled fire is forced to creep along the bottom, and when 
 that of all the vents is united, it rises gradually, and bursts out on every side at 
 once. If the coal contain pyrites, the combustion is allowed to continue a con- 
 siderable time after the disappearance of the smoke, to extricate the sulphur, 
 part of which will be found in flowers on the surface. If it contain none, 
 the fire is covered up soon after the smoke disappears, beginning at the 
 bottom and proceeding gradually to the top. In 50, 60, or 70 hours, the 
 fire is in general completely covered with ashes of char, formerly made, and 
 in twelve or fourteen days the coke may be removed for use. In this way a 
 ton of ordinary bituminous coal commonly produces from 700 to 1,100 Ibs of 
 coke. 
 
 Coke and Tar Works. The annoyance attending this process by the evolution 
 of the immense quantities of smoke from the ignited matter, besides the entire
 
 7*4 IRON. 
 
 waste of the volatile products, induced the late Earl Dundonald, many years 
 since, to introduce a plan for preventing the former, and saving the latter. One 
 of these tar works, as they were called, was erected at Mr. Wilkinson's great 
 works at Bradley, another at Tipton, and a third at the Level Colliery and 
 iion works upon Dudley-wood. Being erected in the vicinity of large iron 
 and coal works, the iron masters furnished the tar works with raw coal, and 
 received in return the cokes produced by such coal, the proprietors being com- 
 pensated by the volatile products, viz. tar, pitch, varnish, and ammonia. 
 
 Coke Kilns. The last described process of making cokes, is now being 
 superseded in many places, particularly in the neighbourhood of Sheffield, by 
 the employment of kilns made of bricks, of a hemispherical form, about ten 
 feet diameter at the base, and about two feet at the top, where a circular opening 
 is left for the introduction of the coal. The manner of working those ovens is 
 thus described by Mr. Parker : " When these ovens are once heated, the work 
 goes on night and day without interruption, and without any further expense 
 of fuel. It is conducted thus : small refuse coal is thrown in at the circular 
 opening at the top, sufficient to fill the oven up to the springing of the arch ; 
 it is then levelled with an iron rake, and the doorway on the side built up with 
 loose bricks. The heat acquired by the oven in the former operation is always 
 sufficient of itself to light up the new charge, the combustion of which is 
 accelerated by the atmospheric air that rushes in through the joints of the 
 loose bricks in the doorway. In two or three hours the combustion gets to such 
 a height, that they find it necessary to check the influx of the air; the door- 
 way is therefore now plastered up with a mixture of wet soil and sand, except 
 the top row of bricks, which is left unplastered all night. Next morning, when 
 the charge has been in twenty-four hours, this is completely closed also, but 
 the chimney remains open till the flame is gone, which is generally quite off in 
 twelve hours more. A few loose stones are then laid over the aperture, and 
 closely covered up with a thick bed of sand or earth. All connexion with the 
 atmosphere is now cut off, and in this situation the whole remains for twelve 
 hours to complete the operation. The doorway is then opened, and the cokes 
 are raked into iron wheel barrows, to be carted away. The whole operation 
 
 takes up forty-eight hours, and as soon as the cokes are removed, the ovens are 
 filled with coal for another burning. About two tons of coals are put in 
 for each charge, and the cokes produced are ponderous, extremely hard, of a 
 
 light grey colour, and shine with metallic lustre ; they acquire in the furnaces 
 an intense heat, and will sustain a great burthen of iron-stone and other 
 materials." When coke is required to be more of the nature of charcoal, the 
 process is conducted in a different manner. The small coal is thrown into a 
 large receptacle, similar to a baker's oven, previously brought to a red heat. 
 Here the door is constantly open, and the heat of the oven is sufficient to 
 dissipate all the bitumen of the coals, the disengagement of which is promoted 
 by frequently stirring it with a long rake. The coke from the ovens, though 
 made from the same kind of coal, is very different from that produced by the 
 former operation, this being intensely black, very porous, and as light as pumice 
 stone. Under the article LIME-BURNING, a drawing and description of a patent 
 oven for making coke is given, in which the latter operation is made subservient 
 to the first. The mechanical arrangement and process therein exhibited, maybe 
 advantageously applied to the roasting of ores instead of lime, and the coke 
 required for the smelting furnace might be made at the same time. As we 
 have extended our observations on the making of coke from pit coal to a 
 length which some of our readers may probably consider to be unsuited to its 
 real importance, we would observe, in the language of Dr. Colquhoun, that this 
 substance " has been the means of advancing the manufacture itself in this 
 country, to an extent which is unparalleled in the history of any other country or 
 nation. It has now been ascertained, by long experience, that there is no other 
 liel which is so well fitted at once to supply the heat of the furnace, and, at the 
 same time, to endure the powerful blast which is incessantly forced upon it. 
 It may now be said to be essential to our iron manufacture, which would 
 indeed, be almost annihilated were^he supplj of it withdrawn." Without it
 
 IRON. 
 
 75* 
 
 fig 
 
 we should be compelled to lay under wood immense tracts of what are now 
 fertile corn fields, in order to supply, at an enormous expense, a much more 
 imperfect fuel for the furnace. But the treasure of it seems to be inexhaustible, 
 and not less so the metal for which it is required, as will be seen upon reference 
 to the article COAL, wherein we have given a section of Bradley mine, and the 
 arrangement of the numerous distinct strata cut through to arrive at the coa- 
 amongst which there occurs from thirty to forty feet thickness of iron-stone 
 before the principal bed of coal is arrived at. 
 
 Roasting Iron-stone. The ores of iron require different treatment in the 
 smelting process, according to the nature and extent of the heterogeneous 
 matter with which the metal is combined. In all ores the iron is in the state 
 of an oxide, and would require a strong heat in contact with combustible 
 matter for their reduction. In most species, the oxide of iron is combined 
 with a considerable proportion of earthy or stony matter, and they are thence 
 denominated iron-stones. But besides the earthy matter and oxygen, many of 
 these contain sulphur, arsenic, and manganese; and it is necessary that these 
 should be extricated previously to melting, which is effected by calcination, called 
 roasting. This is usually done by stratifying the ore, broken into small pieces, 
 with small or refuse pit coal, and burning it in great heaps, either in the open 
 air, or in a kiln ; which dissipates the sulphureous, arsenical, and other volatile 
 matters, leaving behind the earth and oxide of iron, which are then easily 
 oroken into convenient fragments for melting. 
 Teague's Patent Roasting Furnaces. Mr. 
 Teague, of the Park End Iron Works, near 
 Calford, in Gloucestershire, took out a patent 
 in 1832, for improvements in smelting, in 
 which he proposes to economise the process of 
 roasting the ore, both as respects the labour 
 and the fuel. Instead of making the calcina- 
 tion a distinct process, conducted in another 
 part of the works, he combines the operations 
 of roasting and smelting, which go on simul- 
 taneously in the same furnace. For this pur- 
 pose lie constructs around the chimney shaft, 
 near to the top or tunnel-head of an ordinary 
 smelting furnace, a series of four or more 
 small reverberatory furnaces or ovens, each 
 provided with a chimney, a damper at top, and a 
 lateral door, which opens externally. Through 
 these doors the ores to be roasted are in- 
 trodi'ced, and deposited upon iron plates, 
 which form the bottoms, and incline down- 
 wards towards the shaft of the smelting fur- 
 nace. The ascending body of flame from the 
 latter, when at work, is prevented from passing 
 out vertically, as usual, by means of a valve 
 or trap door, which closes the orifice, and the 
 small chimneys to the surrounding reverbera- 
 tory roasting furnaces being opened, causes 
 the flame and heated matters to pass through 
 these, and in their progress to impinge upon 
 the ore, and deprive it of its volatile com- 
 binations. When the ores have been thus 
 sufficiently operated upon, they are thrust 
 forward by a proper tool into the body of the 
 smelting "furnace ; and whilst the roasting 
 furnaces are being recharged, the valve or 
 trap to the smelting shaft is opened, that the 
 flames may take that course instead. Thus 
 it would appear that a considerable saving
 
 756 IRON. 
 
 of labour is effected, and that all the fuel employed in roasting by the ordinary 
 process is likewise saved, as the flame which usually passes out of the tunnel- 
 Bead to waste in the air, is made to calcine the ore, and this being dis- 
 charged into the blast furnace at the high temperature it had acquired in the 
 oven, the subsequent fusion of it is greatly accelerated. In Fig. 1, on the 
 preceding page, is given a vertical section of one of these roasting ovens, in 
 connexion with the tunnel-head, a a represents a portion of the tunnel-head, 
 or upper end of the blast furnace, provided with a door or valve b, resting on 
 a ledge at c ; d is one of the four ovens ; e the iron plate that contains the ore 
 or "mine," supplied through a doorway at /; g the oven chimney, with its 
 damper h. Fig. 2 exhibits, on a smaller scale, a plan of the whole building, 
 taken just above the oven plates, as designated by the four letters e ; the fifth 
 compartment i of the pentagon being for supplying the fuel and fluxes into 
 the tunnel a, into which all of the compartments directly lead ; each of these 
 are closed externally by massive iron doors, suspended to stout iron lever beams 
 to the opposite ends of which are hung counterbalancing weights, that enable 
 the workmen to move them with facility. The dotted rectangle upon the plan 
 is designed to explain the precise nature of the sectional view given in Fig 1. 
 Jefferies' Coke and Iran Ore Furnace. A patent for economizing the process 
 of roasting ores was>, however, taken out prior to the last-mentioned, by Mr. W. 
 Jefferies, of Ratcliff, which was specified in August 1827. By this plan the 
 roasting of the ore and the forming of the coke are performed together in one 
 furnace ; the process is thus described in the Journal of Patent Inventions, 
 Vol. II. p. 66 : " The ore is first broken by stampers, or crushed by rollers, 
 until it is reduced to such fragments as will pass through a sieve of eight or ten 
 holes to the square inch. After which, instead of introducing the pulverized 
 ore into a roasting oven or furnace, it is incorporated with a sufficient quantity 
 of small coal, and the mixture put into a coke oven, previously heated in the 
 usual way. Herein the ore is calcined bv the heat of the coal, the latter being 
 thereby converted into coke ; for this purpose the door of the oven is left open 
 until all the. flame has passed off, in the ordinary manner, when the door is to 
 be closed, and all access of air prevented. After this the charge is to be with- 
 drawn, as if it were coke merely, and, when cooled, broken down into masses 
 of a proper size for the smelting furnace, into which it is thrown ; the metal is 
 here ' smelted out ' fi-om the coke with which it was combined ; the coke serving 
 as the fuel to fuse and extract it." 
 
 Fluxes. The coke and iron-stone having been duly prepared, the next consider- 
 ation is the nature and extent of the flux required to separate the metal by fusion 
 from those of its combinations which the previous process was inadequate to 
 perform. These differ in every degree and form, according to the nature of the 
 ore, and as their consideration at length would occupy a greater space than the 
 assigned limits of this work will afford, we purpose availing ourselves of a few 
 extracts from the valuable papers by Mr. David Mushet, inserted in Tillock's 
 Philosophical Magazine ; and must refer those of our readers who may desire' 
 more information to the original source for it. " To deprive an ore of its iron" 
 (says Mr. Mushet) " so that no portion of it shall escape in the scoriae 
 unrevived, two things are indispensable. First, the metal contained in the ore 
 must be presented to a portion of fuel sufficient to take up the oxygen of the 
 metal. Second, as this revivification goes on in the manner of a metallic per- 
 spiration upon the softened surface of the orp, another agent ought to be present 
 to facilitate the separation by uniting with the earthy parts of the ore, forming 
 a thinly divided lava, no longer capable of retaining the globules of metal, or 
 of preventing the congenial affinity of the carbonic principle from taking full 
 effect for the improvement of the quality of the iron."" Experience has 
 shown that an excess of any particular earth may be corrected by applying one 
 opposite in its effects ; and that the addition of lime, in various proportions, if 
 found in most cases to answer the desired end." " If the various classes so 
 iron ore are fused in contact with charcoal, without the addition of a flux or 
 solvent, the result is, from calcareous iron-stone, a larger portion of iron propor- 
 tioned to the intrinsic richness of the ore, than from argillaceous iron-stoue :
 
 IRON. 757 
 
 and from the latter a larger produce of iron, than from an ore whose chief 
 mixture was silex ; the scoriae produced from the respective operations always 
 demonstrate, from the colour and opacity, the probable quantity of iron which 
 still remains to be taken up." There are some calcareous iron-stones which 
 contain lime almost sufficient to form the necessary scoriae, the colour of which, 
 when freed from the metal, possesses a considerable degree of transparency. 
 When a number of these stones are used in the blast furnace, a much less 
 quantity of calcareous earths are necessary. It sometimes happens at iron 
 works, whose chief supply is derived from a calcareous field of iron-stone, that 
 by using a great proportion of an individual ore, surcharged with lime, the 
 operations of the furnace are obstructed, and consequences entailed fatal to the 
 interest of the manufacturer. From an excess of pure calcareous earth being 
 present in the furnace, the scoriae, thick and curdled, becomes attached to the 
 sides and bottom of the furnace; the quantity hourly increases, till it has 
 accumulated to such a degree as to intercept the ascent of the blast, and the 
 descent of the materials. The remedy suggested by Mr. Mushet for these 
 inconveniences, is, reducing the quantity of lime direct, or by an admixture 
 of clay or sand, whether combined with iron or not. An excess of clay in the 
 argillaceous ores has the same prejudicial effects which have led to their rejection, 
 though it has been owing to improper application. The fusibility of lime and 
 clay individually is much facilitated by the addition of sand. In all cases 
 where these earths exist in excess in the ores, they ought either to be combined 
 in the blast furnace with siliceous iron-stone, or treated with a lime-stone con- 
 taining a considerable portion of sand. When a scarcity of lime exists in the 
 blast furnace, and a superior quantity of clay and silex is combined with the 
 iron-stones, the lava will flow from the furnace comparatively cold, tenaceous, 
 and of a brown or pale dirty green colour, containing iron ; when the mixture 
 is just, the colour of the scoriae is pure white, enamelled with a variety of blue 
 shades, waving, circular, or formed in straight delicate lines, arising from a 
 peculiar existing modification of a minute portion of the metal. Where nature 
 has bestowed mixtures productive of every quality of crude iron, the proper 
 management of ores would become simple and easy : just combinations super- 
 sede the necessity of changing the quality of the lime-stone added for a flux, 
 or of having recourse to various qualities of it, in order to assist or correct the 
 deficiency of the native mixture. Wherever the ores are of a structure thus 
 deficient, it then becomes the province of the manufacturer to ascertain the 
 mixture of the individual ores which compose his supply, and to restore that 
 equilibrium of parts by the proper application of superadded earths which 
 experiment and observation have proved to determine a certain quality of iron. 
 Many years ago, Messrs. Hill and Co. of the Plymouth works near Merthyr, 
 took out a patent for the use of the "cinder" produced in the refining and 
 puddling operations, as a substitute for a portion of mine in the smelting pro- 
 cess. This cinder or scoriae is an oxide of iron combined with but little foreign 
 matter, and usually contains from 50 to 70 per cent, of metal. All previous 
 attempts to smelt it economically had failed. Messrs. Hill and Co. mixed with 
 it such a portion of argillaceous matter as to assimilate it to the natural ore of 
 their district, and by this combination succeeded in its perfect reduction. The 
 patent was soon after invaded ; and, upon an action being brought for infringe- 
 ment of right, the defendants proved a prior application of the process. The 
 patent was thereby quashed, and the iron masters, in consequence, generally 
 adopted the process ; but, from injudicious management, much bad iron was 
 made, which got it into disrepute. With proper care, and in small proportion, 
 the cinder is now used advantageously at most of the iron works, in the making 
 of forge-pigs, under the subsequent process of puddling. It i? usual, in most 
 furnaces, to make the coke always a fixed quantity, and to proportion the iron- 
 stone and the lime or other flux, to the quantity of iron to be made, and the 
 working order of the furnace ; and in proportion to the latter additions, the 
 furnace is said to carry a greater or less burthen. Some furnaces carry so 
 little burthen as to produce only about 13 tons per week, while there are others 
 which yield as much as 70 tons per week. In these latter, the ore is in much 
 5 D
 
 768 IRON. 
 
 greater proportion to tne coke than the former, but the product is inferior. 
 The burthen is varied according as the iron is required to possess more or less 
 carbon ; thus in making No. 1, or best iron, (which contains the greatest pro- 
 portion of carbon, the burthen must be considerably less than that required to 
 make less carburetted iron, or what is called white-iron, or forge-pig. A 
 general idea of the proportions of the materials from an argillaceous ore, con- 
 taining about 27 per cent, of iron, with a strong carbonaceous coal, and a good 
 limestone, consisting of shells, is afforded by the operation of a furnace under 
 Mr. Mushet's direction. The furnace works with a bright tuyere, and receives 
 from the blast about 2500 cubic feet of air per minute, through a circular 
 aperture 2f inches in diameter. The quantity of calcined ore for the manu- 
 facture of good melting iron is upon a par with the coke ; and forge-pig, or the 
 least carburetted variety, six of coke to seven of ore. The lime-stone, unburnt, 
 under the same circumstances, is to coke as 4 to 1 1 ; and for melting metal, 
 retains a similar ratio. 
 
 Smelting Furnace. The external figure of a blast furnace is that of a trun- 
 cated pyramid, while its interior form has been very aptly compared to that of 
 a decanter, supported upon a funnel. In the subordinate details of their con- 
 struction, there is mucn variation by different iron masters, which, however, 
 probably does not essentially affect the results. In the annexed sectional 
 representation of one of these great laboratories, we have not selected one of 
 
 Fig. 1. 
 
 the latest mould, but one that was described and found to be very efficient by that 
 peat master in metallurgic operations, Mr. David Mushet ; since which, we 
 bebeve there have been no improvements of essential importance, except in the 
 blowing machinery, which we shall duly notice, a is the regulating cylinder, 8
 
 IRON. 
 
 759 
 
 feet in diameter, and 8 feet high ; b the floating piston, loaded with weights pro- 
 portionate to the power of the machine ; c the valve by which the air is passed 
 from the pumping cylinder into the regulator ; d the aperture by which the blast 
 is forced into the furnace; diameter of the pipes, 18 inches; e the blowing or 
 pumping cylinder, six feet diameter, 9 feet high, 7 feet stroke ; / its piston, 
 with a view of one of its several valves ; g solid masonry, on which the regu- 
 lating cylinder rests, and to which the flanch and tilts of the blowing cylinder 
 are attached, h the safety-valve or cock, by the simple turning of which, the 
 blast may be admitted to, or shut off from the furnace, and passed off to a 
 collateral tube in the opposite side, i the tuyere, by which the blast enters the 
 furnace. The end of the tapered pipe, which approaches the tuyere, receives 
 small pipes of various diameters, from 2 to 3 inches, called nose pipes, which 
 are applied at pleasure, according to the strength of the blast required, k is 
 the bottom of the hearth, 2 feet square; / the top of the hearth, 2 feet 6 inches 
 square; kl the height of the hearth, 6 feet 6 inches ; / is also the bottom of 
 the boshes, which here terminate, of the same size as the top of the hearth, 
 only the former are round and the latter are square, m the top of the boshes, 
 
 12 feet in diameter, and 8 feet high; the top of the furnace, 3 feet diameter, 
 at which the materials are charged ; m n the internal cavity of the furnace of 
 the top of the boshes upwards, 30 feet high, n k, total height of the internal 
 parts of the furnace, 44$ feet ; o o the lining, which is built with fire bricks, 
 
 13 inches long by 3 thick, in the nicest manner ; pp a vacancy left all round the 
 outside of the first lining, 3 inches wide, which is rammed full of coke dust, this 
 space being left for the expansion of the materials by heat ; q q a second lining, 
 similar to the first ; r a cast iron lintel, in which the bottom of the arch r s is 
 supported this arch is 14 feet high on the outside, and 18 feet wide; vv the 
 extremes of the hearth, 10 feet square. Fig. 2 represents a plan of the foun- 
 dation of the furnace ; a a are the bottom stones of the hearth ; b stratum of 
 bedding sand ; c c passages for the escape of vapour ; d d pillars of brick ; these 
 parts, in the dotted elevation, are indicated by similar letters of reference. 
 The subjoined, Fig. 3, affords an horizontal section of 
 
 the diameter of the boshes, the linings and vacancy 
 being indicated by similar letters of reference to those 
 in the elevation. Fig. 4 exhibits a vertical side section 
 of the hearth and boshes, showing the tymp and dam- 
 stones, and the tymp and dam-plates, a the tymp- 
 stone ; b the tymp-plate, wedged firmly to the stone, to 
 hold it in case of splitting by the heat ; c, dam-stone, 
 which occupies the whole breadth of the bottom of the 
 hearth, excepting about six inches, which, -when the 
 furnace is at work, is filled every cast with strong sand. 
 This stone is surmounted by an iron plate of great 
 thickness, called the dam-plate, the top of which is 
 about 3 inches below the tuyere hole. The space be- 
 tween the bottom of the tymp and the dotted line is 
 rammed full of strong sand or fine clay, called the tymp 
 stopping, which prevents any part of the blast being 
 wasted. The square of the base of this blast fur- 
 nace is 38 feet; the height from the false bottom to the top of the crater, 
 55 feet 
 
 Mode of working furnace. When the furnace is finished, the bottom and 
 sides of it for 2 feet up the square funnel, receive a lining of common bricks 
 upon edge, to prevent the stone from shivering or mouldering when the fire 
 comes in contact with it. On the front of the furnace is erected a temporary 
 fire-place, about 4 feet long, into the bottom of which are laid corresponding 
 bars. The side walls are made so high as to reach the under surface of the 
 tymp-stone. A fire being kindled upon the bars, the whole cavity of the fur- 
 nace serves as a chimney ; the draught and heat is therefore considerable. la 
 the course of three weeks, the furnace is freed from damp, and ready to 
 receive the materials; the fire-place is then removed, but the interior brick 
 
 Fig. 3.
 
 700 IRON. 
 
 lining remains till the operation of blowing commences. Some loose ruel is 
 iben thrown upon the bottom of the furnace, and a few baskets of coke, which 
 are allowed to become thoroughly ignited before more are added, and the fur- 
 nace is then gradually filled. The furnace represented is capable of holding 
 99,000 Ibs. of coke, equivalent to 198,000lbs. of coal. This quantity of mate- 
 rials is continually burning for several years together, without intermission ! A 
 renewal of the total quantity occurs about every third day. There are, neverthe- 
 less, still larger furnaces in Wales. The first charges which a furnace receives 
 contain but a small proportion of iron-stone compared to the weight of the 
 coke, which is afterwards increased to a full burden. The descent of the bur- 
 den is facilitated by opening the furnace below, two or three times a day, throwing 
 out the cold cinders, and admitting, for an hour at a time, a fresh body of air. 
 This operation is repeated till the approach of the iron-stone and cinder, which is 
 always announced by a partial fusion, and the dropping of lava through the 
 iron bars, introduced to support the incumbent materials while those in the 
 bottom are carried away. The filling above is regularly continued ; and when 
 the furnace at the top has acquired a considerable degree of heat, it is then 
 judged time to introduce the blast ; the preparations of which are the follow- 
 ing: The dam-stone is laid in its place firmly imbedded on fire-clay; the 
 dam-plate is again imbedded in this with the same cement, and is subject to the 
 same inclination. On the top of this plate is a slight depression, of a curved 
 form, towards that side farthest from the blast, for the purpose of concentrating 
 the scoriae, and allowing it to flow off in a continued stream, as it tends to sur- 
 mount the level of the dam. From this notch to the level of the floor a decli- 
 vity of brick-work is erected, down which the scoriae of the furnace flows in 
 large quantities. The opening betwixt the dam and side walls of the furnace, 
 called the fauld, is then built up with sand, the loose bricks are removed, and 
 the furnace bottom is covered with powdered lime or charcoal dust. The 
 ignited cokes are now allowed to fall down, and are brought forward with 
 iron bars, nearly to a level with the dam. The space between the surface of 
 the cokes and the bottom of the tymp-plate is next rammed hard with strong 
 binding sands ; and those cokes, which are exposed on the outside, are covered 
 with coke dust. These precautions being taken, the tuyere hole is then 
 opened and lined with a soft mixture of clay and loam ; the blast is commonly in- 
 troduced into the furnace, at first with a small discharging pipe, which is afterwards 
 increased as occasion may require. In two hours after blowing, a considerable 
 quantity of lava is accumulated ; iron bars are then introduced, and perforations 
 made in the compressed matter at the bottom of the furnace ; the lava is ad- 
 mitted to all parts of the hearth, and soon thoroughly heats and glazes the sur- 
 faces of the fire-stone. Shortly after this it rises to a level with the notch in the 
 dam-plate, and by its own accumulation, together with the forcible action of the 
 blast, it flows over. Its colour is at first black ; its fracture dense, and very 
 ponderous ; the form it assumes in running off is flat and branched, sometimes 
 in long streams, and at other times less extensive. If the preparation has been 
 well conducted, the colour of the cinder soon changes to white; and the metal, 
 which is in the state of an oxide formerly coloured, will be left in a disengaged 
 state in the furnace. When the metal has risen to nearly a level with the 
 dam, it is then let out by cutting away the hardened loom of the fauld, and 
 conveyed by a channel made in sand to its proper destination ; the principal 
 channel, or runner, is called the sow, the lateral moulds are called the pigs ; 
 hence the name of the raw commercial article, " pig-iron," of which many 
 hundred thousands of tons are annually made. 
 
 Phenomena attending the production of the different qualities of Pig-metal. 
 When fine (No. 1,) or super-carbonated crude iron is run from the furnace, the 
 stream of metal, as it issues from the fauld, throws off an infinite number of 
 brilliant sparkles of carbon. The surface is covered with a fluid pellicle of 
 carburet of iron, which, as it flows, rears itself up in the most delicate folds ; 
 at first the fluid metal appears like a dense ponderous stream, but as the colla- 
 teral moulds become filled, it exhibits a general rapid motion, from the surface 
 of the pigs to the centre of many points. Millions of the finest undulations
 
 IRON. 761 
 
 move upon each mould, displaying the greatest nicety and rapidity of movement, 
 conjoined with an uncommonly beautiful variegation of colour, which language 
 is inadequate justly to describe. Such metal, in quantity, will remain fluid for 
 twenty minutes after it has run from the furnace, and, when cold, will have its 
 surface covered with beautiful carburet of iron, already mentioned, of an 
 uncommonly rich and beautiful appearance. When the surface of the metal 
 is not carburetted, it is smooth, like forged iron, and always convex. In this 
 state iron is too rich for melting without the addition of coarse metal, and is 
 unfit to be used in a cupola furnace for making fine castings, where thinness 
 and a good skin are requisite. 
 
 No. 4, or oxygenated crude iron, when issuing from the blast furnace, throws 
 oft' from all parts of the fluid surface a vast number of metallic sparks, and, 
 while running, it is covered with waving flakes of an obscure smoky flame, 
 accompanied with a hissing noise. This is a slight sketch of the appearances 
 of the two extreme qualities of crude iron, when in a state of fusion. There 
 still remain two intermediate stages of quality to be described ; these are, 
 carbonated, and carbo-oxygenated iron, that is, No. 2 and No. 3 of the 
 manufacturers. 
 
 No. 2, or carbonated iron, exhibits, like No. 1, a beautiful appearance in the 
 runner and pig. The breakings of the fluid, in general, are less fine, the 
 agitation less delicate, though the division of the fluid is equal, if not beyond, 
 tli at of the other. 
 
 No. 3, or carbo-oxygenated iron, runs smoothly, without any great degree of 
 ebullition, or disengagement of metallic sparks. The partings upon its surface 
 are longer, and at greater distances from each other than in the former varieties ; 
 the shape they assume is either elliptical, circular, or curved. In cooling, this 
 metal acquires a considerable portion of oxide. An infallible criterion of the 
 quality of the iron in the furnace is afforded by the colour of the scoriae upon 
 the working bars, which are from time to time inserted to keep the furnace free 
 from lumps, and to bring forward the scoriae. When No. 1, or super-carbonated 
 iron, is on the hearth, the vitriol crust upon the bars will be of a black colour 
 and smooth surface, fully covered with large and brilliant plates of plumbago. 
 As the quality of the metal approaches to No. 2, (carbonated,) the carburet 
 upon the scoriae decreases both in point of quantity and size. When carbo- 
 oxygenated (No. 3) is in the furnace, the working bars are always coated with 
 a lighter coloured scoriae than when the former varieties exist; a speck of 
 plumbago is now only found here and there; and when the quality of the metal 
 is oxygenated (No 4), not only have the plates of carburet disappeared, but also 
 the crally colour on the external surface of the scoriae. It may perhaps be 
 proper here to mention, that although for convenience the manufacturer has, 
 from a just estimation of the value of the metal in a subsequent manufacture, 
 affixed certain numbers for determinate qualities of iron, yet it is difficult to 
 say at what degree of saturation of carbon each respective term commences ; 
 suffice it then to say, that the two alterative principles, oxygen and carbon, form 
 two distinct classes that in which oxygen predominates, and that in which 
 carbon predominates. 
 
 Mechanical arrangements for supplying the tunnel-head with the materials for 
 fusion. The mode of supplying the lime, coke, iron-stone, &c. to the crater, or 
 tunnel-head of the furnace, was formerly by men carrying them in baskets up 
 an inclined plane or bridge. Subsequently small waggons or corves were em- 
 ployed to take the materials up an inclined railway to the crater, by means 
 of chains connected to the waggons, and passing round a drum or rigger, 
 actuated by the steam engine, or other prime mover. In some instances the 
 weight, of a bucket of water descending into a pit was employed as the moving 
 force to draw the loaded corve up to the top of the furnace, or hopper leading 
 into it ; where the corve, by being provided with a sliding bottom, to which was 
 fixed a projecting bar, discharged its contents, by the bar coming against an 
 obstruction, which pushed the bottom away, when over the discharging hole. 
 The bucket also, on reaching the bottom of the pit, was discharged of its water, 
 through a valve in its bottom being opened by coming in contact with a
 
 762 IRON. 
 
 projecting pin at the bottom of the pit. The motion was then reversed by the 
 superior weight of the empty waggon, causing it to descend the inclined plane, 
 and raise up the empty bucket for a renewal of the operation, by refilling the 
 vessels, one with the mineral, and the other with the water. In some situations 
 the mode of raising the materials is by an endless chain passing round two 
 riggers, one at each extremity of the inclined plane, the chain carrying two 
 corves or buckets, one of which is being filled below whilst the other is being 
 discharged above, in continuous succession ; in a similar way to the scoops in 
 dredging and excavating machines, described under their initial letters. 
 
 Welsh Smelting Furnaces. In South Wales and other mountainous districts 
 it is the practice to build the blast furnaces beside cliffs or steep preci- 
 pices, which are sometimes walled up artificially to render them perpendicular, 
 so that the tunnel-heads of the furnaces shall be upon a level or somewhat 
 lower plane than the contiguous high ground, from which a bridge is thrown on 
 to the top of the solid masonry, after the manner expressed in the subjoined 
 cut. This cut also gives the external form of the fur- 
 nace described at page 758, with this difference merely, 
 that instead of the open crater or tunnel-head, this has 
 a vertical cylindrical chimney of the same internal area 
 as the upper orifice built over it ; on one side of which 
 there is a doorway for charging the furnace with the 
 mine and other materials. A parapet wall or iron 
 fence surrounds the upper edge of the square towrr. 
 The dotted lines in the figure indicate the form of the 
 interior of the furnace. The coke-hearths and the 
 mine-kilns, and all other supplies to the furnace, are 
 situated on the high ground, so that they can at once be shot across the bridge 
 into the tunnel-head. Various buildings, including the " cast-house," where the 
 metal is run into pigs (or other forms to patterns as may be required) are situated 
 on the lower level, and are covered with roofs. 
 
 Anthracite used in Smelting. Before closing our account of the smelting 
 department of the iron manufacture, we think it right to call the attention of 
 those who are interested in the iron trade to the consideration of the practica- 
 bility of employing anthracite, or stone coal, in the process of smelting. In 
 several parts of Great Britain and Ireland, but particularly in Scuth Wales, 
 there are many thousands of acres of iron-stone near the surface, with a vast 
 abundance of anthracite coal, lying in contiguous strata. This coal, notwith- 
 standing it consists almost entirely of carbon, has been alleged, and is 
 generally believed, to be incapable of smelting iron ; and as there are in some 
 districts (that of Llanelly, for instance,) no bituminous coal sufficiently near to 
 these valuable beds of iron-stone, they remain un worked, under the presumption 
 that they cannot be worked with profit, owing to those circumstances. Whether 
 this prejudice is well or ill-founded, is a question that we cannot take upon 
 ourselves to solve ; but we will place before the reader a few facts that appear 
 to bear directly upon the question, and leave the solution to those who are 
 more practically conversant with the subject. 
 
 In several parts of the United States of America, where (as in South Wales) 
 iron-stones and anthracite are plentiful, but bituminous coal wanting, recent 
 attempts have been made to smelt the iron with anthracite alone ; and all the 
 reports that have reached us on that subject, agree in stating, that success has 
 attended those attempts. 
 
 Malm's Furnace for Smelting Iron with Anthracite Coal. Mr. Joshua Malin, 
 of Lebanon, in Pennsylvania, has described his furnace for this purpose in the 
 Franklin Journal. It is very similar to our common blast furnaces, the cru- 
 cibles and hearth alone differing materially. Mr. Malin's crucible, instead of 
 being square is round ; anthracite coal being so much more dense than coke or 
 charcoal, its weight causes it to descend in the corners or angles of a square 
 hearth, where, being screened from the intense blast which is required, and 
 carrying with it a portion of the unmelted ore, it mixes with, and chills a 
 quantity of the fused ore and metal, which stops the operation of the furnace.
 
 IRON. rjg 
 
 For the smelting by means of anthracite; ""Mr. Malin states, that the Wast 
 must be introduced under a pressure of at least two and a half pounds to the 
 circular inch ; and the quantity required for a common sized furnace will not be 
 less than 28,000 cubic feet per minute, or 7 cubic feet per minute lor every 
 circular inch in the area of the hearth at the tuyere. The hearth of the furnace 
 in which Mr. Malin made his experiments, was only 11 inches in diameter at 
 the tuyeres, the blast being introduced as represented in the subjoined plan. 
 Mr. Malin had the diameter increased to 14 inches, and found that the blast 
 which he had at his command would not enable him to go beyond that point, 
 as, when he attempted it, the scoriae and metal chilled, and formed a tube from 
 the tuyere a part of the way across the hearth. Fig. 1 exhibits a vertical sec- 
 tion, and Fig. 2 an horizontal section drawn to a scale of an eighth of an inch 
 to the foot; the letters of reference in each figure that are the same indicate 
 
 Fig. I. 
 
 Fig. 2. 
 
 corresponding parts, a is the crucible, being a part of what is commonly called 
 the hearth of the furnace ; b are the boshes, or that part where the metal passes 
 from the solid to the fluid state as it descends ; c is the bottom stone of the hearth, 
 bedded in sand, and supporting the crucible and boshes ; d is the dam-stone ; 
 e e the blast pipes ; // inner walls of the furnace of fire-brick, around which 
 is a space from 4 to 6 inches wide, filled with soft sand-stone ; h tymp-plate ; 
 i t lintels of cast-iron to support the inner walls over the tuyere and tymp- 
 arches ; k k tuyere arches ; / part where the metal flows out ; m tymp arch ; n 
 the tymp-stone, forming a part of the crucible, and supporting a part of the 
 boshes. 
 
 The prejudices in America against the use of anthracite were as strong as 
 they are here ; but there, they are now being rapidly dissipated by an irre- 
 pressible spirit of enterprise, guided by scientific intelligence ; whilst we, out of 
 reverence to the ignorance of our forefathers, adhere to and cherish them. In 
 America anthracite was at first introduced into the parlour grates, where, having 
 gained a triumph, it descended into the kitchens, in spite of the vehement pro- 
 testations of the ministers of the victualling department ; having, however, 
 here demonstrated its superiority over all other kinds of fuel, it next presents itself 
 to the notice of steam -furnace men and the iron masters; these, however asserted 
 that there was something in its very nature which, in their occupations, forbade 
 its use ; and they were so obdurate, Dr. Jones informs us, that " you might 
 as well have attempted to convince them that it was fit to be made into candles,
 
 |84 IRON. 
 
 as that it might be employed for their purposes if their furnaces were suitably 
 constructed, and the fuel properly managed." " It appears likely, however," our 
 scientific historian continues, " that it will soon assert its claims to superior 
 excellence in these applications also, and triumph over the prejudices of the 
 managers of furnaces, as it has over those of the householder, the cook, and the 
 blacksmith." 
 
 Improved Blowing Machinery. In continuing our account of the process of 
 obtaining iron in the smelting furnace, we omitted to notice that the blowing 
 apparatus delineated in connexion therewith, has, in a great measure, been 
 superseded by improved mechanism of that kind. The pumping cylinder, by 
 an arrangement of valves well understood, is made to draw air on both sides of 
 the piston, so that whilst the air enters on one side it is forced out on the other 
 into the regulating vessel, from whence it is usually conducted into the fur- 
 nace by two or three distinct pipes and tuyeres. But a most ingenious arrange- 
 ment of blowing cylinders was invented by Mr. Paterson, of Lanark, which is 
 described and figured in the article BLOWING MACHINES, wherein several others 
 are given. Water bellows have been extensively employed, but the objection 
 to these has been the humidity which the air acquired by the spray ; to remedy 
 this defect, the air is forced into a dry regulator, which is simply a large air- 
 tight metal box, about 10 feet square and 40 feet long. At Bradley iron works 
 they have a regulating cylinder of still greater dimensions. The uniform elas- 
 ticity which the air acquires in these great chambers causes it to issue in a 
 constant equalized blast. 
 
 The blowing of heated air has recently been introduced at several foundries, 
 and likewise at the Clyde iron works. It is the invention of Mr. J. B. Neilson, 
 of Glasgow, whose patent was enrolled in March, 1829, and is designated an 
 improved application of air to produce heat in fires, forges, and furnaces, where 
 bellows or other blowing apparatus is required. He proposes that the air sup- 
 plied by any kind of machine shall, before it enters the furnace or cupola, be 
 made to pass through an air-vessel heated to very high temperature, a red heat 
 if possible, by which means a current of hot air will be thrown on the fire 
 instead of the cold current usually employed. It is recommended that the air 
 vessel be surrounded with some non-conducting substance, and imbedded in 
 masonry. The capacity of this vessel for a smith's forge he recommends to be 
 about 1,200 cubic inches, and for a cupola or blast furnace, about 10,000 cubic 
 inches. It was much doubted whether the increased temperature of the fire 
 thus blown would produce advantages equivalent to the expense of constructing 
 the air vessel and keeping it at the requisite heat ; and as respects the smelting 
 of iron in particular, the theory seemed opposed to the well-known fact that a 
 much larger quantity of iron is yielded by the blast furnaces in the winter 
 season, or when the air is cold, than during the summer season, when the air is 
 warm. The experiments at the Clyde iron works, have however been reported 
 most favourably of, and the saving of coal attending it is so great, that it was 
 stated, in the Glasgow Chronicle, to be calculated to accomplish a saving in the 
 consumption of this island to the amount of 200,0007. annually. At the 
 Clyde iron works the air was heated to 220 Fahr. before it was discharged 
 into the furnace ; an efiect which was produced by the expenditure of only one- 
 eleventh part of the cost of fuel it takes to heat it to the same temperature in 
 the blast furnace, which may be accounted for by the circumstance that Mr. 
 Neilson 's air vessel is heated by coals, while the blast furnace is heated by coke. 
 Should further experience in this invention confirm the views of the patentee, 
 it may be regarded as a valuable improvement in metallurgic operations. 
 
 Refining Furnace. The refining of pig-metal is a modern intermediate 
 process of conversion, which the experience of our iron masters has led them 
 to believe is the best economy in the preparation of the metal for subsequently 
 rendering it malleable in the puddling furnace ; although it is well under- 
 stood not to be indispensable to the production of wrought iron. The furnaces 
 employed for this purpose are small buildings, termed refineries ; a vertical 
 section of one of them is given in the cut on the next page, a is a thick cast-iron 
 trough, having three of its sides made double, with a hollow space between,
 
 IRON. 
 
 765 
 
 around which water is caused to flow 
 from an external cistern b, the cool- 
 ing effect of the fluid serving to 
 prevent the fusion or other injury 
 of the metal sides of the furnace by 
 the intense heat; at c (in a line) are 
 two pipes, through which air is 
 forced from a blowing machine upon 
 the materials in the trough ; these 
 pipes are kept cool by a constant 
 stream of water always" flowing over 
 them, brought on by small pipes d, 
 regulated by cocks. The bottom of 
 the furnace is of brick, on which 
 the fuel is laid, and over it the pigs 
 to be refined. The building is sur- 
 mounted by a wide chimney about 
 12 feet high, and the front, which is left open, has a projecting roof to cover 
 the workmen who attend to it. In Wales it is usual to make these furnaces 
 what is termed double; that is, the fire is somewhat larger though single, but 
 the blast is double, there being usually three pipes and tuyeres on each of two. 
 opposite sides of the furnace ; each of the pipes are generally about an inch in 
 diameter, and supplied with a blast equal to about 2 or 2J Ibs. pressure upon 
 the square inch. The pigs are kept in a state of fusion for some time, exposed 
 to an intense heat from the powerful blast just mentioned, which drives off a 
 portion off the carbon united to the rnetal. When the operation, which usually 
 occupies two hours, is deemed to be complete, a hole in front of the hearth is 
 tapped, through which the liquid metal flows into a very thick oblong flat mould 
 of cast-iron, placed over a cistern of water ; this causes the metal to be rapidly 
 chilled, which is thus brought into a cake about 2 feet broad and 20 feet long. 
 This plate of metal is extremely brittle, and presents on its fracture a silvery 
 whiteness : it weighs about a ton. In some refineries the furnace is lined with 
 firebricks or stones, without water running round it, and^ the refined metal is 
 cast upon sand in shallow moulds or depressions, and water is then thrown upon 
 the metal to cool it quickly. As inattention or neglect on the part of the refiner 
 would be productive of serious loss to the iron master, he is always paid 
 according to the metal produced. Great experience and practical skill are requi- 
 site qualities in a refiner; his occupation is one of great personal exertion, and he 
 is exposed to an intense fire, that no one unaccustomed to it could even approach. 
 He puts the charge of pigs upon the fire, attends to the progress of the melting, 
 supplies the fire from time to time with coke, frequently stirring it up to equalize 
 the heat ; sees that the tuyeres are in good order, and that the water circulates 
 uninterruptedly ; runs out the metal when it is ready ; he removes the plate 
 from its mould when it has a little cooled, by means of a lever, on to a truck, 
 and wheels it out of his shed ; he then prepares his mould for the next plate, 
 removes his cinders, and repeats the operation. The quantity of refined metal 
 thus produced by a " double" furnace in Wales, is from 60 to 70 tons per week, 
 of 6 days of 24 iiours each, the men working in turns of 12 hours at a time, 
 and 12 hours rest. The refiner selects his materials according to the quality of 
 iron wanted. The best quality is from the dark grey pig, or No. 3, and the infe- 
 rior sorts from bright, mottled, and white in their order. The very " worst " 
 white iron cannot be used by itself in the refinery ; being almost infusible from 
 its deficiency of carbon, it is disposed to clog and settle on the hearth. To 
 Avork up such iron in the refinery, it is mixed with pigs of a "better quality," 
 or those containing more carbon, the union conferring fusibility. When 
 No. 3 pigs are used, it requires about 22^ cwt. of them to produce one ton of 
 refined metal ; the " yield " however varies, from causes before adverted to, 
 according to the degree of carbonation of the pig metal employed, the quality 
 of the coke, the management of the blast, and various other circumstances. 
 This reduction of weight is however not an entire loss, as a quantity of
 
 766 
 
 IRON. 
 
 " cinder" is produced which floats on the top of the metal, and detaches itself as 
 it cools ; this cinder contains usually about 50 per cent, of its weight of iron, 
 which is recoverable on the blast furnace. 
 
 The Puddling Furnace. The next process consists in depriving the iron of 
 its remaining carbon and oxygen (or as far as that may be practicable), by 
 which it is rendered malleable and is constituted wrought-iron. For this pur- 
 pose the brittle plate of white refined iron is broken up into small pieces, and 
 brought to the puddling furnace, sometimes called the balling furnace, from 
 the circumstance of the iron being therein made up into balls, about the size 
 and shape of quartern loaves of bread. The fiwnace differs but little from an 
 ordinary reverberatory furnace, as will be seen upon reference to the subjoined 
 engravings, in which Fig. 1 exhibits a vertical and longitudinal section, and 
 Fig. 2 an horizontal section or plan. As a strong flaming fuel is required in 
 this operation, coal is employed in preference to coke, the gaseous portion of 
 the former being rendered available as fuel. At a is the ash-pit ; b a series of 
 
 fig. 
 
 Fig. 2. 
 
 loose grate-bars, on which is deposited the coals introduced through an aperture 
 c kept closed, except during the charging or stoking, by heaping up the small 
 coal against it externally, where it is formed into a cast-iron receptacle for the 
 purpose, resembling a coal scuttle ; at d is the fire-bridge, frequently made 
 hollow by an iron casting, as shown in the drawing, and encased with fire- 
 bricks ; this hollow casting is connected externally with a vertical pipe to 
 convey off" the air, which is caused to pass through the fire-bridge ; and by the 
 heat it thus abstracts, the fire-bridge is prevented from becoming fused by the 
 intense action of the flame. At e is the basin of a bed of sea sand spread into 
 a concave shape ; it is supported upon a stratum of fire-bricks, which lie on 
 solid masonry /beneath. On this bed the refined metal is placed and exposed 
 to the heat of the flames, which are made to impinge downward upon the 
 metal in a constant stream, owing to the curved form of the roof, against
 
 IRON. 767 
 
 which the current of air that passes through the grate-bars strikes ; from the 
 metal the flames again ascend, passing over a dam g, through the throat h, into 
 the chimney i, which is carried up from 30 to 40 feet high, and is provided with 
 a damper at the top, by which the puddler regulates the degree of draft, and 
 consequently the heat of his 
 
 furnace ; for during some parts of his operations, 
 
 he requires "a more intense heat than at others. The draft through these fur- 
 naces is frequently so great as to cause the flames to ascend above the chimney 
 top, and to make the damper, situated there, red hot. At .;' is a sliding door, 
 suspended by a chain, and raised or lowered by a lever k ; at the bottom of the 
 door is a small aperture (as shown in Fig. 1) employed as a spy-hole, and for 
 the introduction occasionally of the puddler's tools without opening the door. 
 There is also usually another small aperture at /, lined with a cast-iron box or 
 case, and divided by a partition into two cavities, through which the "shingler" 
 puts his iron bars to be heated, as will be hereafter explained. The dam g 
 before mentioned is deeply grooved or furrowed (as seen in Fig. 2) to allow the 
 cinder or slag to run off into a pit n, whence it is discharged through an open- 
 ing o out of the furnace. The chimney is bound together at different points 
 with iron, and the external sides of the body of the furnace is encased in iron 
 plates, bolted through the brick-work. All these precautions are, how- 
 ever, insufficient to prevent the early distortion of the fabric, and which would 
 without them soon fall into ruins by the destructive effects of the fire. The 
 employment of a sand bottom to the furnace, it is proper to mention, is now 
 getting into disuse in many parts, where, in lieu of the sand, a thick cast-iron 
 plate forms the bottom, on which is strewed a coat of the oxide or cinder made 
 in the puddling process. The puddler is assisted in all his operations by an 
 inferior workman, termed his " under-hand," who is not recognised by the 
 master, but paid by the puddler. The metal being put into the furnace, the 
 door is shut down and carefully closed to prevent the admission of air, as any 
 admission of air otherwise than through the grate-bars, tends to derange or 
 moderate the proper current. In about half an hour the metal begins to fuse, 
 at which time the severe labours of the puddler begin. His first business is so 
 to dispose the pieces of melting metal, that those which are the least exposed 
 to the action of the flame may be drawn more -immediately under its influence, 
 and that the whole quantity may be brought to the same fluid state, as nearly 
 as possible at the same time. If it is not so managed, that which is first melted 
 begins to burn and waste before the other is ready, and the yield is therefore 
 inferior than when all goes on well together. When the whole is melted, the pud- 
 dler, sometimes with a tool turned at the end like a hoe, and sometimes with a 
 flat one, stirs it about diligently in all directions, exposing every part of it in 
 turn to the action of the flame. In doing this he is obliged to be constantly 
 changing his tools, which soon become red hot, and are plunged, as they are 
 withdrawn, into a vessel of water to cool them. The liquid mass heaves and 
 boils as it is being stirred, showing the escape of elastic fluid. By degrees the 
 metal loses its fluid property, and assumes the appearance of a loose granulated 
 mass, the external particles of which appear in vivid combustion, whilst the 
 main portion of it is less brilliant ; these appearances indicate that the metal 
 is "coming round to nature," as the puddler terms it; and to accelerate this 
 process, he frequently throws some water from a scoop on to the metal, and 
 occasionally adds a portion of the black oxide of iron formed in the subsequent 
 processes of the forge, by which the weight of his product of metal is increased. 
 He continues to move the mass about vigorously till it becomes so thick and 
 tenacious as to stick together and form into lumps. At this time the puddler 
 with great dexterity, exposed to a severely scorching heat, and a light of the 
 most dazzling brilliancy (which no ordinary person can even look at but for an 
 instant), separates the metal into masses resembling in size and figure quartern 
 loaves of bread, but weighing from 50 to 80 Ibs. each, called " puddled balls," 
 and having arranged his batch of metal upon their vitrified bed, they are left 
 there exposed to the continuation of the heat, until they can be successively 
 extracted and delivered by the under-hand to the shingler. By this mode of 
 puddling, a lose of time is incurred, by the heating of the fresh metal for the
 
 768 IRON. 
 
 next batch, amounting to nearly half an hour, besides the waste of fuel during 
 that period. To obviate these losses, various contrivances have been resorted to 
 for heating the fresh charge of metal, whilst the previous batch of puddled 
 balls are being shingled or rolled. The simplest and most improved plan deserves 
 mentioning. It is merely to make the body of the furnace longer than usual, 
 and to have a second door between that where the puddler works and the 
 chimney. This affords sufficient room for the succeeding charge of metal, which 
 is at the same time so near the workman that when he has completed the heat 
 and sent the balls to the shingler, the newly-prepared charge is just in the 
 right state for him to bring forward and recommence his operations upon. By 
 the puddling furnaces first described, but seven heats could be completed in the 
 turn of twelve hours ; but with the improved furnace, nine heats are effected in 
 the same time by one puddler, the results being two-ninths more of iron, 
 without any additional quantity of coals. 
 
 Malleable iron produced direct from the ore with stone coal. A short time ago, 
 a patent was taken out in America, by Mr. B. Howell, of Philadelphia, for an 
 improvement in a " bloomery furnace," " by means of which, and the use of 
 anthracite coal exclusively for fuel, iron ore is directly converted into malleable 
 iron." As this invention would be of immense importance to the country, 
 if it could be brought successfully into operation, (and we can discover no 
 reason why it should not,) we deem it right not to omit giving a description of 
 it in this work. 
 
 The specification, after adverting to the drawings, states, " By these, and the 
 notes and references appended thereto, it will be seen that this furnace combines 
 within itself the advantages of a close furnace and an open fire ; in this respect 
 differing essentially from any other now in use for similar objects. In the 
 upper or close portion, being all that above the hearth, with anthracite coal 
 excited by a proper blast, a degree of heat is obtained much greater than can 
 possibly be generated in the ordinary fire with charcoal ; while the lower por- 
 tion opening into the hearth, and permitting the free action of blast upon the 
 burthen, performs all the offices of the open fire, or forge. The size of the 
 furnace and the proportions may be varied, if the principle .of the close and 
 open fire be retained. The furnace being first heated up in the manner 
 of a common cupola, the process is thus conducted : the coal having settled 
 sufficiently for that purpose, it is charged with the proper burthen of ore, 
 which will vary according to the quality and kind. The charges are then con- 
 tinued alternately of coal and ore. The ore soon arrives at the tuyeres in a 
 state of partial fusion, and is then, by the intense heat of that part of the fur- 
 nace, quickly separated from its earths, and then rapidly descending into and 
 below the direct action of the blast, a large part of which is driven out at the 
 open front, first passing over that portion of the ore which has reached the 
 hearth, it is thereby brought, in the language of the workmen, " to nature," 
 or, in other words, into malleable iron. As it sinks into the region of the blast, 
 the small masses may be drken into one, and a loup shaped by giving a proper 
 direction to the pipes at the different tuyeres, and the loup can be removed 
 with a proper instrument ; another instrument, or strong iron bars, being intro- 
 duced at B, to hold up the burthen while this is doing. The loup may be drawn 
 into a bloom under a forge hammer, or passed through rollers. In either 
 operation, it will, of course, be necessary to renew the heats, which may be 
 done in a common chaffery, or in a heating furnace. This process is continued 
 at the pleasure of the workmen, and as soon as a quantity sufficient foi a loup 
 accumulates, it is withdrawn, as above described. In the early stage of the 
 operation, it will be necessary to charge the furnace, nearly, or quite to the 
 top ; but as the heat increases, the height of the coal may be gradually 
 diminished ; and at a very high temperature, from two to three feet of coal will 
 be found sufficient. The cinder produced in this way will bear working a 
 second time; an appropriate flue facilitates the operation, and as it is first 
 fused, and sinks, and is thus interposed between the iron at the bottom of the 
 hearth, and the coal, it contributes to prevent a mixture of the two. Holes 
 may or may not be left in the sides of the furnace for the introduction of bars
 
 IRON. 
 
 769 
 
 to aid in detaching the iron from the bottom and sides ; but this will often be 
 necessary, if the back of the furnace be thrown sufficiently forward, and a 
 proper direction be given to the blast ; for which purpose, tuyeres are placed 
 in different positions on three sides of the furnace, and at different elevations. 
 One or two pipes may be used at pleasure. From the foregoing, it must be 
 obvious that by the rapidity of the process, the saving thereby of time and labour 
 the substitution of a cheaper, more powerful, and abundant fuel for that now 
 in use, and which is so made applicable to this object by the peculiar construc- 
 tion of this furnace, a great and important improvement has been effected 
 in the conversion of iron ore into malleable iron. The following drawings, 
 Figs. 1, 2, 3, represent an elevation,- and vertical and horizontal sections, all 
 drawn to a scale of one inch to three feet, the same letters referring to corre- 
 sponding parts of each. A is the tunnel head, where the furnace is charged ; 
 
 Fig. I. 
 
 Fig. 2. 
 
 to be provided with a cover, which is placed on in the intervals of charging, 
 when the coal is low. B a projecting, open, hollow hearth, for the reception- of 
 cinder and iron, with a cinder hole at C, to be opened when it is wished to 
 draw off the cinder. D D are tuyeres 
 for the introduction of the blast, placed 
 in different positions on three sides of 
 the furnace, and at different elevations, 
 to vary the direction of the blast at 
 different stages of the process. The 
 back and front walls may both or either 
 be thrown or inclined somewhat more 
 inward than is represented in the draw- 
 ing, and as indicated by the dotted 
 line on the vertical section ; and with 
 advantage when the ore is not very 
 pure, and makes much cinder. The 
 furnace is to have over it a brick 
 canopy or chimney, to aid in carrying 
 off the gas given out by the coal. The 
 furnace is lined with fire brick, and is 
 cased with cast-iron plates, secured by 
 strong bolts, keys, and screws, and 
 between the casing and the lining,
 
 770 
 
 IRON. 
 
 Fig. 3. 
 
 common brick, with a thin packing 
 of sand ; the latter, to prevent injury 
 from expansion. In a letter to Dr. 
 Jones, (the editor of the Journal of 
 tlie Franklin Institute) Mr. Howell, 
 the patentee of the furnace just 
 described, states that he had com- 
 pletely succeeded in making bar iron, 
 and even nails with it, without suf- 
 fering the iron to cool; and that 
 practical forgemen, who performed 
 the manual labour, were astonished 
 beyond measure at the result ; the 
 iron being as good as that made at 
 the neighbouring forges in the old way. 
 
 Refining with Mineral Coal- A patent recently granted in America, to Mr. C. 
 Lewis, (of Pine Creek, Alleghany County, Pennsylvania,) for refining pig iron, 
 seems also to be well deserving of the attention of the English manufacturer. 
 The process is chiefly effected by mineral coal, uncoked, but in such a manner, 
 that the metal while in a state of fusion is not brought into contact with the 
 mineral coal. A reverberatory furnace is employed ; the mineral coals are put on 
 the grate-bars, and when the furnace has acquired a melting heat, a door at the 
 side of the furnace is opened, through which a bushel of charcoal is introduced 
 into a basin ten inches deep, previously covered with a stratum of silicious sand ; 
 jver the charcoal is distributed, so as to cover it, a bushel of hammer or forge 
 cinder, and then about a ton of pig metal, so laid around the basin as to leave 
 a space between each pig ; thereby a greater surface of the metal is exposed to 
 the action of the flame. The fire in the grate is now to be well supplied, and 
 maintained; and all access of air prevented, except through the grate. In 
 about half an hour, the metal will be nearly melted, which, when the workman 
 perceives to be the case, he drags, by means of an iron rabble passed through a 
 hole in the door, the whole of the metal from the sides, into the basin. He 
 then introduces from three quarters to one bushel of charcoal upon the surface 
 of the metal in fusion. The fire being kept up, and the metal frequently 
 stirred, it will, in half an hour after the whole is melted down, be sufficiently 
 decarbonized to let it run out of the furnace. The consumption of mineral 
 coal in this operation is from 15 to 18 bushels, and two of charcoal of wood, to 
 each ton of metal ; and the ton of metal is obtained from only 22 cwts. of pigs. 
 Owing to the intense heat of the furnace, the volatile parts of the coal are 
 consumed, or pass along the roof of the furnace into the flue, while the surface 
 of the metal is protected by the charcoal and the scoriae, which in all cases keep 
 uppermost without incorporating with the metal. Refining after the above 
 way will be of great advantage to forges that make their blooms by means of 
 charcoal, as it will greatly facilitate the procedure, and lessen the quantity of 
 charcoal used. The iron made in the manner described is said to be quite malle- 
 able, close in texture, and fibrous. It is worthy of observation, that this furnace 
 requires no machinery attached to it, and the process appears calculated to effect 
 some important savings to the manufacturer. 
 
 Salts employed in making Iron. A patent was taken out a few years ago, by 
 Mr. Luckcock, an iron master of Edgebaston, near Birmingham, for the appli- 
 cation of the muriate of soda, (common salt,) to the iron in the puddling fur- 
 nace just as the metal is breaking down into fusion; the action of which was 
 said to be productive of that toughness and malleability which had previously 
 >ecn only effected by laborious and expensive mechanical agency. The pro- 
 portion of salt to the iron was about two per cent, by weight. How far expe- 
 rience has proved the advantage of this mode of seasoning the puddlers' balls, 
 we are not informed; but it might be presumed to have been successful, from 
 its having excited the rivalry of others, who have since taken out patents for 
 salting iron ; amongst these we may particularly notice Mr. Josias Lambert, of 
 Liverpool Street, London, who appears to have availed himself of some hints
 
 IRON. 771 
 
 out of an old fashioned receipt book. This gentleman adds (in his first 
 patent, 1829,) potash to Mr. Luckcock's soda, in the proportion of one part of 
 the former to two of the latter ; and of this mixture he administers 15 pounds 
 to the ton of ore in the blast furnace ; in the refining furnace 12J Ibs., and in 
 the puddling furnace, 1 1 Ibs. to the ton. Mr. Lambert, in the succeeding year, 
 1830, took out another patent, entitled "an improvement in the process of 
 manufacturing iron," &c. This improvement consisted in the addition to the 
 former mixture of two parts of lime! thus making it two parts of "salt," one 
 part potash, and two parts lime. But notwithstanding this powerful and novel 
 auxiliary, he does not diminish the quantity of the mixture, but nearly doubles 
 it. After this explanation of the nature of these presumed discoveries, it will 
 be unnecessary to enter more into detail, as respects the quantities of the 
 fluxes to be used in the several successive processes of the iron manufacture. 
 We should not indeed have noticed these two last patents at all, were it not 
 from the circumstances that this species of iron cookery has been, and is pro- 
 bably, still conducted upon an extensive scale. Of the novelty of the 
 scheme, every chemist must be aware, that all the substances mentioned 
 have been unscrupulously used as convenient fluxes in the assay furnace 
 for a century or more; and as respects the eligibility of their employment in 
 the great laboratories of the present day, we have the scientific and practical 
 authority of Mr. David Mushet, for observing that they are considered 
 useless. 
 
 The Forge, flotts, fyc. For the purpose of introducing some recent improve- 
 ments connected with the previously described departments of the manufacture, 
 we broke off our narration of the usual train of proceeding of an iron work at 
 page 768, where we left the puddlers' balls in the furnace ready for subsequent 
 operations. Hitherto, we may observe, imagination has had to picture to itself 
 the intense action and changes that have been going forward, unseen, and 
 unheard ; but henceforward, to the completion of the wrought-iron bar, the 
 rod, and the sheet, all is activity and motion. The departments where those 
 articles are produced are contiguous and open to each other ; they are termed 
 the forge and the mill, and are more or less extensive, according with the mag- 
 nitude of the iron work. The impression upon a spectator, to whom the scene 
 is novel, is one of extreme interest, and one that he never forgets ; he finds 
 himself in the midst of machinery of a peculiar character, and of extraordi- 
 nary magnitude, remarkable for its massiveness and its weight, and in its 
 effects astonishing. In the mill, at regular intervals of about a minute, he sees 
 elled by the rising of a furnace door, which opens to his 
 
 view a chamber full of dazzling light before which stands an invulnerable 
 workman, who pulls from the midst of it a lump of iron, blazing like a meteor, 
 and dashes it upon the ground. Almost as quick as thought, and before the 
 furnace door can be closed again, the ignited mass of metal is eagerly snatched 
 up by another workman, with a pair of tongs, who instantly applies it to the 
 largest grooves of a pair of solid cylindrical " rolls," which are revolving with 
 great velocity, and with such immense force, that the mass of iron is, as it were, 
 shot through the rolls, and is so far altered in its figure, by the compression, 
 as to be doubled in its length. Notwithstanding the rapidity with which the 
 iron moves by the revolution of the rolls, it is uniformly seized as it comes out 
 by another workman, who, with his assistant, tosses it back over the top roll, 
 where it is again taken by the first workman, and passed through the next pair 
 of grooves, smaller than the former ; it is again seized by the workman on the 
 opposite side, and treated as before ; and thus it travels backward and for- 
 ward, spontaneously illuminating its path by bright scintillations, through half 
 a dozen or more successive grooves ; all the while lengthening itself, perfecting 
 its shape, and improving its quality, till it arrives at the end of its journey in 
 about a minute after starting from its fiery chamber. The spectator, who may 
 have taken his stand at a convenient distance, and has scarcely been able to 
 comprehend more than the possibility of what he has seen done, from the celerity 
 of its execution, is probably obliged to move farther off by the scorching heat 
 of the still bright red, long, finished bar which has reached him. This bar has,
 
 772 
 
 IRON. 
 
 however, not passed its last channel before the effulgent furnace again opens its 
 mouth, and another bright mass of metal is ready to follow the first ; and thus, 
 bar after bar is made till the contents of that particular furnace are discharged. 
 During this splendid operation, the spectator has perhaps scarcely looked around 
 him ; to see a fly wheel, of twenty feet in diameter, and of ten tons weight, cutting 
 through the air at the rate of ninety revolutions per minute ; (more than 60 miles 
 per hour,) driving by means of a massive cog-wheel on its axis, numerous other 
 wheels at different velocities, to communicate the requisite power and motion 
 to various other mechanism contiguous and remote ; to observe that through the 
 medium of other gear of due proportions, the ponderous rolls are made to turn on 
 their thick axes or " necks " twice as many times per minute as the great fly ; to 
 trace the cause of motion of the latter, through a stout pinion on its axis, driven 
 by a great toothed wheel, which is turned by a crank attached to the lower 
 extremity of the heavy vibratory connecting rod of a magnificent steam engine, 
 which, in its own separate apartment or house, is quaffing its potent vapour in 
 silence, and distributing its constantly renewed energies around to all that 
 require it; not excepting the ponderous machine which we shall next describe, 
 the effects of which are the reverse of those which are complained of in the 
 trunkmaker's hammer. 
 
 Shingling or Blooming. The " underhand " having drawn a ball out of 
 the furnace, his superior, the " shingler," takes it up by a pair of tongs and 
 heaves it on to tbe depressed part a of an anvil b, which with its block (sunk in 
 
 the ground, and resting upon solid masonry) weighs several tons, at the same 
 time another shingler, whose turn it is, (there being two shinglers to each 
 hammer,) draws out of the furnace a stout flat bar, one of the two before men- 
 tioned, the end of which has been brought to a welding heat, and holding the 
 cooled end wrapped round with a piece of nail bagging, he lays the heated 
 end upon the ball under the hammer c, the first blow of the latter forces the 
 bar into the ball flush with its surface, and they are thus instantly welded 
 together, and form as it were, one piece ; the bar thus becoming a long handle, 
 by which the shingler can move and turn the ball about upon the anvil 
 between every blow of the hammer. This hammer with its helve d weighs 
 between four and five tons, and makes upon an average about 150 blows per 
 minute; it is actuated by the revolution of a cylinder e, in tbe circumference 
 of which are fixed, at equal distances, four or more wipers or coggs // which 
 successively come into contact with the underneath side of the extremity of the 
 hammer helve, and thereby lift it up after each blow about 18 or 20* inches, 
 whence it falls simply by its own weight ; which operates so effectively as to 
 reduce by a very few blows, the shapeless ball into a bloom. This bloom is a 
 rough square bar, usually about 20 inches long, and 4 cr 5 inches thick. 
 By reference to the foregoing figure, it will be observed that the hammer head
 
 IRON. 
 
 773 
 
 has not an uniform flat face, but is of a varied form, and has several projections 
 which answer to the rounded ends of common sledge and hand hammers, 
 termed panes; by placing the bloom under these projections crossways, the 
 bloom is extended lengthways ; and by placing the bloom so that a pane shall 
 strike it lengthways, its breadth is increased, and the grooves or dents which are 
 thus made are worked out by bringing the bloom under the flat parts of the 
 hammer. The effect of the hammering is not confined to giving it a new form, 
 out a large quantity of dross is thereby worked out, and the sparks and scales 
 fly off with great force, so that the workmen are obliged to be protected with 
 thick leather aprons, leggings, &c. It sometimes happens, through mismanage- 
 ment on the part of the puddler, that a ball has not sufficiently " come round to 
 nature," and it shows its indisposition to submit to the gentle correction of the 
 hammer by hissing and bubbling. This species of bloom is called a shadrach, 
 and it is thrdwn back to the puddler, who has to pay a fine for having drawn 
 it out of the furnace before it was sufficiently purged of its impurities. 
 
 Shingling Rolls. In this early state of the manufacture of malleable iron, the 
 office of the hammer just described is generally confined to giving the bloom only 
 about fifteen or twenty blows, by which it is brought into a shape that will permit 
 of its being, while still of a bright red heat, passed through the shingling rolls. 
 The precise form of the grooves in these rolls is not material, and they differ 
 in most works ; the intention is to reduce the bloom as quickly as possible into 
 a broad, flat bar, for a purpose that will presently be explained. In the annexed 
 sketch, which we have made to illustrate the subject, two different kinds of grooves 
 
 JHL 
 
 I 
 
 are introduced, both of which are employed. In the above figure, u u represent 
 the upper roll ; / / the lower ; s s are the standards through which the necks of 
 the rolls pass, and are therein made to revolve in opposite directions by the 
 action of the pinions pp in gear with each other, to the shaft of one of which 
 the power is applied ; and by a continuance of such shafting, connected by 
 clutch boxes, motion is sometimes imparted to a series of pairs of rolls, arranged 
 in one line. In the preceding figure, the dark spaces between the rolls, 
 respectively marked abcdefg, show the form given to the bars as they pass 
 through those grooves. The bloom is supposed to be first put through a, and 
 then through the others successively, until it is brought out at g in the form of 
 a flat bar four or five inches broad, and half, or five-eighths of an inch thick. 
 By the severe squeezing which the bar undergoes in passing through these 
 rolls, an additional quantity of cinder or foreign matter is forced out of it; and 
 it is worthy of remark that the grooves abc powerfully contribute to this effects 
 The form of them is not designed to be an equilateral hexagon, but that of a 
 square with the top and bottom corners taken off. In the horizontal line 
 the angles are right angles, the bar will therefore in that direction be made 
 wider than in its vertical breadth, where the angles are obtuse. Besides, there 
 are usually between the rolls, where they are intended just to touch each other, 
 little vacancies, into which the iron is compressed in its passage, and a burr is 
 thus formed upon its angles ; now, by turning the bar so as to present the 
 right angles and burrs to the flat top and the flat bottom of the same, or the 
 5 F
 
 774 
 
 IRON. 
 
 next pair of grooves, they are thereby crushed down, and the dross is thus more 
 efficiently worked out of the metal, and by the time it arrives at g, in the form 
 of a flat bar, it is considerably improved in its toughness and malleability. 
 Nevertheless, the iron is of an unmerchantable quality ; it is still impure ; is 
 too easily broken ; has a rough scaly surface, and its edges are imperfect. 
 
 Shearing the Bars. This rough bar is therefore, immediately it has passed 
 through the rolls, and while it is still red hot, put between the jaws of a pair 
 of shears, worked by the engine, and cut into lengths of about a foot each. A 
 pair of shears for this purpose is represented in the engraving of the great 
 hammer at page 772, by reference to which the reader will readily comprehend 
 our explanation of them. That portion of the shears marked gg g, is one mas- 
 sive casting, and is fixed to the ground in the most solid and substantial 
 manner. The cutting edge of the lower chap at h is formed out of a stout 
 steel bar; it lies in a rebate, and is therein fastened by screw bolts. The chap 
 of the upper shear i i is similarly provided ; this shear is the movable one, and has 
 its joint or centre of motion in the upright at g. By the revolution of the drum 
 e, it carries round with it an eccentric or solid crank k, to which is jointed a 
 stout iron bar /, which bar being jointed at its other end to the upper shear, 
 communicates its own vibratory motion to the shear, and makes it cut at 
 each alternation of the stroke or revolution of the drum. To prevent the steel 
 edges of the shears from being softened by the contact of the hot bars, a small 
 stream of water is made to flow over them constantly, brought on by a small 
 pipe, or other suitable channel, and regulated by a cock. The bars as they are 
 cut, fall into an iron barrow or truck, in which they are wheeled away to the 
 piler. 
 
 Piling. The piler piles the pieces of the rough bar together in the manner 
 shown in the annexed cut, putting as many upon 
 one another as will form a bloom or a finished bar of 
 the size and weight required. The piles are then 
 taken or deposited in a convenient situation for 
 being put into 
 
 The balling or reheating Furnace. This furnace is in no essential respect dif- 
 ferent from the puddling furnace already described ; but the men who work 
 them are usually called " bailers." 
 
 Sailing. With an iron instrument of the shape of a baker's peel, the bailer 
 places each pile on the bed of sand prepared to receive them, taking care not 
 to disturb them, so as to cause any of the pieces to project beyond the rest, as 
 these projecting pieces would, in consequence, be sooner heated, and sustain a 
 severer action of the fire than the others, causing those exposed parts to burn 
 or waste, and the whole mass to be deteriorated in tenacity. The number of 
 piles put into the furnace is regulated by their size, in order that when they are 
 sufficiently heated they may be quickly discharged ; and as large heavy bars 
 take longer to roll than small light ones, a less number of large piles are put 
 into a furnace in making large bars, than of small piles in making small bars. 
 Notwithstanding the bailer arranges his batch so that the piles may be com- 
 pletely heated in succession, he exercises his judgment upon them with his 
 eagle-like eyes, as to which bloom is in the most forward state. The bailers' 
 proceedings are likewise regulated by the state of the other balling furnaces of 
 the work, whose products are successively worked off. If a bailer keeps his iron 
 too long in the furnace, it is thereby rapidly wasted and deteriorated ; on the other 
 hand, he must be ready to a minute, that the rolls may be constantly at work, 
 and that the power of the engine may not be wasted. The blooms that are now 
 taken out of these reheating furnaces, are presumed to be of a quality adapted 
 to the manufacture of common bar-iron, of which there is a very extensive 
 variety of forms ; but the great bulk consists of three kinds, namely, flat, square, 
 and round, the latter being usually termed bolts. Of the three last-mentioned 
 classes, there are very numerous sizes, as will be seen on reference to the tables 
 subjoined to this article. 
 
 Variety of RoUing Apparatus. For the manufacture of so extensive a variety, 
 t, great number of rolls is required in an iron work. The stock of thebe
 
 IRON. 
 
 775 
 
 ponderous tools, in some works, consists of upwards of a hundred pairs; and there 
 are commonly from ten to twenty pair of standards (fixed in the most firm and 
 solid manner that art is capable of) ready for their reception. A sufficient 
 example of this kind of mechanism for making flat bars has already been 
 given &idefg, in the cut at page 773 : in the illustration which follows, the rollers 
 for making round and square bars are shown. These rolls are called finishing 
 rolls, for the bar, previously to being brought to them, is passed through several 
 grooves of a pair of roughing rolls, which are of greater diameter than the 
 
 finishing rolls, and furnished with larger grooves. In these last-mentioned, the 
 bars are reduced to nearly the intended size, and they are then run through 
 two or three grooves of the finishing rolls; each time that a bar is passed 
 through, whether round or square, it is turned a quarter round to take off the 
 burr or fin, formed at the junction of the rollers, and through the last hole it is 
 usually passed twice, by which its figure is perfected. The effect of the piling 
 and reworking the iron, as just described, has been to weld the several layers of 
 the pile together, which thus become one solid mass, possessing a fibrous tex- 
 ture and an increased toughness ; and during the operation, many of the 
 impurities that the iron had retained are expelled. In rolling flat bars, the 
 treatment is different from that of square and round ; the pile is never presented 
 to the rolls with the edges of its layers upwards, but always with their flat 
 sides horizontal ; for were the bar rolled upon the edges of the layers, the 
 welding would probably be very imperfect, and the bar comparatively weak. 
 Each bar after it is completed in the rolls, is taken by two boys with tongs, 
 who first put the marks on with steel punches ; they then present its extremities, 
 which are usually ragged and uneven, to be cut off by a pair of shears that 
 are constantly opening and shutting by the action of the engine ; the boys then 
 take the bar, and lay it along a solid cast-iron bench, perfectly flat, and having 
 a straight edge on one side; and as the bar is still hot, they easily make it per- 
 fectly straight by a few blows with wooden mallets. 
 
 Process of Rolling Defects and Improvements. To give the reader a clear 
 insight into the mode of working a bar through the rolls, it appears to be 
 necessary partly to repeat what has been before but imperfectly noticed. A bar 
 of iron, as it passes through each successive groove of a pair of rolls, is received 
 on the opposite side by two men, one of whom draws it out by the end with a 
 pair of tongs, and the other supports it by a lever to prevent its making too 
 sudden a bend ; and when the bar is through, these men pitch it back again 
 over the top roll for it to pass through the next groove ; and this operation is 
 repeated until the bar is reduced to the required size. Now it must be evident 
 upon reflection, that this returning of the bar over the rolls occupies about as 
 much time as the actual rolling ; consequently that the iron becomes cooled in 
 proportion, harder, and requires more power to roll it ; that the workmen have 
 a very severe labour to perform, and are all the while exposed to a scorching heat. 
 These defects in the ordinary process of rolling forcibly struck the writer
 
 776 
 
 IRON. 
 
 several years ago, when he proposed two methods of continuous rolling, 
 by which it was estimated that the manual labour would be greatly reduced, 
 the personal inconvenience diminished, the cost of the machinery lessened, and 
 one-half of the power of the engine saved. The first of these plans was to 
 place a series of pairs of small rollers (that is, short in their axes) one before 
 the other, so that the bar might pass in one continued straight line, from groove 
 to groove, until finished of its intended dimensions. This plan is explained 
 by the annexed diagram; a a, bb, and cc, represent the transverse sections of 
 
 Fig. 2. 
 
 three pair of rollers, with grooves of different depths ; the bar is supposed to 
 enter at d, and by passing through the rollers a a to be reduced to the size e, 
 where the bar slides upon a form h, guided thereon in a straight line by a fur- 
 row of the shape of the bar, direct into the grooves of the rollers bb; the bar of 
 the size of e is here reduced to that of/, lying on another form A, which con- 
 ducts it through the rollers e e, and is thereby further reduced to the size of g, 
 or any other that may be required by a suitable extension of the apparatus. 
 By this method it was considered that a bar would be rolled in about one-third 
 the usual time ; that the manual labour would be reduced to a trifling amount ; 
 and that not one-half the usual power required of the engine would be 
 absorbed. The latter advantage results from the celerity of the operation ; for 
 as the iron is much hotter, it is much softer, and requires a less amount of force, 
 even during the diminished time taken up by the process ; but the most im- 
 portant advantage is, that a better bar is thereby made ; when the maxim to 
 " strike the iron while it is hot," has thus been duly attended to, the bar, 
 instead of being cracked at its edges or otherwise unsound from being rolled 
 when too cold, will be uniformly solid and of a more perfect form. 
 
 The second plan devised was to put 
 a series of small rollers one above 
 another, with the usual spur gear on 
 their axes, which would give every suc- 
 ceeding roller an opposite rotation, so 
 that the bar might enter between the 
 first and second roller, go back through 
 the second and third roller, then 
 through the third and fourth, the 
 fourth and fifth, and so on to comple- 
 tion. In the annexed, Fig. 2 affords a 
 side elevation, and Fig. 3, on the follow- 
 ing page, a vertical section of six small 
 rolls, abcdef, which, by their arrange- 
 ment, are in effect five pairs. In Fig. 3 
 the letters ghikl, show the situation of 
 five shelves, (the proportionate length 
 of which cannot be shown,) on which the 
 iron slides ; and the arrows in the same 
 figure indicate the course taken by the 
 bar through all the rolls. The shelf g is 
 supposed to be upon a level or some- 
 what lower than the mouth of the fur- 
 nace, the bloom from which is to ba 
 slided down upon g, and pushed between 
 the rollers a and b, and as it passes 
 out of these, it gradually bends down,
 
 IRON. 
 
 777 
 
 the end falling in the position of the 
 arrow at h, ready to enter between the 
 rollers b and c; then upon i between c 
 and d, upon k between d and e, upon / 
 between e and/, and so on to any num- 
 ber of rolls underneath, or be conducted 
 forward to another series of rollers 
 placed before it. Both the plans now 
 described may be employed separately 
 or jointly ; but for various reasons the 
 vertical series would be preferable for 
 roughing the work, while the hori- 
 zontal arrangement would probably be 
 best suited for finishing the work. It 
 is to be understood that the foregoing 
 diagrams are only designed as explana- 
 tory of the principle of construction, all 
 the subordinate details being omitted as 
 unnecessary in this place. Previous to 
 the year 1828, the writer had never 
 seen nor heard of iron being rolled on 
 either of the plans described ; he had 
 seen several iron works, one newly 
 built, in none of which, however, was 
 the principle adopted ; he could find no 
 published account of any thing of the 
 kind ; his mechanical friends said the 
 plans were new and valuable, and a patent was determined upon if the opinions 
 of two or three respectable iron masters, whom he consulted, should be 
 favourable ; when, singular to relate, two of these persons, who had very exten- 
 sive concerns, condemned the plans as useless and impracticable, while the 
 third said they were not only practicable, but highly advantageous ; and he 
 proved the truth of his assertions by showing the writer his works, wherein 
 iron was at that time being rolled on the very principle of both plans, where 
 he was informed it had been practised for several years ; and that similar rolls 
 were used in several of the works of Staffordshire ! This fact has been men- 
 tioned with the view of inculcating circumspection in inventors before they 
 incur the expense of patents, and a disregard of dogmatical opinions when 
 unsupported by reason. It is worthy of remark in this place, that in none of 
 the recent treatises on the iron manufacture has any notice been taken of this 
 important improvement in rolling iron. The plan at the iron works where the 
 writer saw the principle in operation, is a modification of that which has been 
 described; it consists of only three rolls one above another, but of the same 
 kind as those delineated at page 775, so that a bar which has passed through 
 a groove between the top and middle roll is sent back through another 
 groove between the middle and lowest roll; and there being many grooves in 
 each of the three rolls, they are thus passed alternately through the upper and 
 lower range of grooves until completed ; but in making vat hoops, the bar, 
 after being passed through several grooves, to roll it to a thin, yet rough 
 flat bar, proceeded onward horizontally (in the same manner as shown in the 
 diagram, page 776), and entered between a pair of plain polished rolls, where 
 it was reduced to the required thinness, and a smooth face was given to it. 
 
 Hortoris mode of rotting large Bars. For bars of still greater dimensions 
 Mr. Horton adopted the following process, for which he took out a patent a few 
 years back. Instead of rolling the single blooms, and then welding the bars toge- 
 ther, to get bars of the sizes required, he takes the blooms (" billets," he calls 
 them,) from the puddling furnace, welds several of them together under the 
 great hammer, then submits the united mass to the operation of the rolls. Great 
 bars, thus prepared are said to possess a more laminated and fibrous texture lon- 
 gitudinally, than those which are united by welding together ready formed bars.
 
 ?78 IRON. 
 
 The various Forms of rolled Iron. Having seen that round iron is produced 
 by the junction of two semicircular grooves in the opposite rollers, the reader 
 will readily perceive, without the aid of a figure, that "half-round iron," (that 
 is, semicircular in its transverse section,) will be produced by having only one 
 roller with a semicircular groove, and the opposite roller with no groove at all ; 
 and that, by making the groove of less depth, that is, of an elliptical curve, a 
 semi-elliptical, or " half-oval " iron bar will be formed ; also that by the junction 
 of two semi-elliptical grooves, " oval iron " will be the result. The two last- 
 mentioned sorts are extensively used by coach smiths; also for the tops of 
 fenders, wire-guards, and such like. It will likewise be evident to the reader, 
 that as square iron is made by two angular grooves, one of such grooves opposed 
 to a plain roller will produce triangular, or " three-square iron ;" that as flat 
 bars are made by grooves of this form , it will be only necessary to make the 
 opposite groove deep and narrow, thus I , and let the latter groove come next to 
 one end of the former, to produce L or " angle-iron." This angle-iron, though 
 of recent introduction, is, on account of its very great utility in making framing, 
 cases, boilers, and a thousand other things, a great favourite with all kinds of 
 smiths, as it enables them to execute superior work with much less labour. 
 Seeing how the angle-iron is made, it will be readily understood that, by placing 
 this i groove so as to come in the middle of this groove in the opposite roll, 
 that " T iron " will thereby be rolled ; and this brings us to a clear understanding 
 how "railway-iron" is made, as the form is usually but a slight modification of 
 the T, by a little rounding of some of the parts ; and by obvious combinations 
 of the foregoing, it will be seen how " iron mouldings," of an infinite variety, 
 may be produced by a pair of rolls, and with far more facility and dispatch than 
 a joiner can make them of wood with his moulding planes. 
 
 Slit Rods. The manufacture of this article is interesting from the wonderful 
 rapidity of its execution ; and that it is of great importance in its results, it 
 need only be stated that in the neighbourhood of Birmingham alone, it furnishes 
 the highly-convenient raw material to upwards of sixty thousand people, men, 
 women, and children, who are employed in nail-making, besides being applied 
 to an infinite variety of other purposes. The slitting is performed by what we 
 would define to be a series of circular shears, formed by the continued contact 
 of a pair of deeply-grooved steeled rollers, which cut by the intersection of 
 their angular edges, as will be clearly understood by reference to the subjoined 
 engraving, which exhibits a pair of slitting 
 rolls, adapted to slit a flat bar or slab, of 
 about seven inches wide, into thirteen 
 equal parts. An end view of this slab is 
 intended to be represented at o, and by 
 presenting it between the two rolls at b b 
 it is obvious that the edges, as they inter- 
 sect each other in their revolution, will 
 divide the slab in the manner shown at a, 
 and force them into the cavities between 
 them, in which manner they will pass out 
 of the rolls in a finished state, requiring 
 only to be tied up into bundles afterwards, 
 of the usual weight of 56 Ibs. To faci- 
 litate the operation of slitting, the bar 
 passes from the rolls where it has been 
 formed of the required dimensions, in its red-hot state, directly between the 
 slitters. In this manner upwards of thirty rods, of a small size, are made at 
 once by a single revolution of a pair of rolls. As the sizes and forms of the 
 rods required are extremely various, it is necessary in a slitting mill to have, at 
 the least, two pair of rolls for each size, that a freshly-turned pair may be in 
 readiness to supply the place of those which become worn or damaged. Slit 
 rods are always more or less ragged at their edges, but this is of trifling import 
 compared to the advantage of their great cheapness, especially in the making 
 ot nails, where they have to be drawn out under the hammer. To prevent any
 
 IRON. 779 
 
 considerable burr, or ruggedness of edge in the rods, the slitting rolls are turned 
 with great care and truth, so as accurately to fit each other 
 
 Rolling of Plate or Sheet Iron is performed between perfectly plain rolls, as 
 before mentioned, for hoops; but the rolls are necessarily of greater dimensions, 
 frequently as wide as five feet ; and of course a very great power is required 
 to compress at once so extensive a line of surface. For ordinary sheet iron, 
 such as is called " double and single plate," only one pair of rolls is employed 
 at a time, the rolls being set nearer together oy regulating screws, each suc- 
 ceeding time that a sheet is passed through. In rolling boiler plates, which are 
 often more than half an inch in thickness/and weigh more than 2 cwt. each, 
 the manual labour is very severe. The iron for these plates is prepared by 
 making a pile of rough bars, which is heated in an air furnace, and then 
 subjected to the action of the great forge hammer, already described, which 
 reduces the pile to a thick slab, the forgers moving it under the hammer, so as/ 
 to give it somewhat of the figure, as to length and breadth, required for the 
 finished boiler plate. It is then heated again in the furnace, and rolled to the 
 required thickness by repeatedly passing the plate between the rolls, the rollers 
 adjusting the rolls nearer together each succeeding time, and taking due care to 
 present the plate in such positions as will extend it to the required shape and 
 dimensions, sometimes making it enter the rolls corner ways, sometimes length- 
 ways, and sometimes breadth ways ; the skill and efforts of the workman being 
 directed to bringing the plate to the required form and dimensions at one heat, 
 and so as to require but very little superfluous edging to be subsequently taken 
 off by the shears. 
 
 Rolling Rods. Round rods, and those of a square or flat shape, that are 
 required more perfect in their figure, and with a smoother surface than those 
 which are split by the process described, are made by rolling with small rolls 
 that are case-hardened, and have their grooves very nicely formed. They are 
 usually from six to seven inches in diameter, and make from 230 to 260 revo- 
 lutions per minute, and the rods, whilst between the rolls, are drawn through 
 them at the same velocity. They are rolled of great lengths, sometimes upwards 
 of forty feet, and are afterwards cut to the required lengths, and tied into 
 bundles of 56 Ibs. each. Round rods are thus rolled so small (about three- 
 sixteenths of an inch), as to form a very useful and cheap substitute for wire. 
 It is extensively used by wire-workers, and in making " invisible fences ;" also 
 by tinmen, coppersmiths, and other trades ; but especially in those cases where 
 it is covered over, and employed to stiffen flexible substances. 
 
 Red-Short, is a term given to bar iron that has the defect of cracking or 
 breaking, when punched or bent, while at a red heat. It is generally very 
 strong when cold, and therefore useful in that state ; and when it is worked, 
 care should be taken by the smith not to subject it to severe strains at that 
 peculiar heat in which it is disposed to give way. 
 
 Cold-Short, is that kind of iron that readily breaks when cold, but is easily 
 wrought under the hammer when heated. 
 
 Testing the Quality of Iron is usually performed by cutting a nick on one side 
 of it with a cold chisel, then bending it down, or giving it a blow with a sledge 
 hammer. If the iron be bad, or cold-short, it will break, and exhibit a re- 
 splendent, crystallized fracture ; if, on the contrary, the uncut part bends back, 
 and exhibits the appearance of a bundle of silky-looking fibres, such iron will 
 probably stand the heated test of bending it double whilst at a cherry-red heat, 
 first in the direction of the pile, and afterwards at right angles to it If the 
 iron does not crack by these tests, it is neither cold-short nor red-short, but of 
 a tough good quality. We have now given a pretty general outline of the 
 process of making common malleable iron, but there remains to be explained in 
 what respect the processes differ in the preparation of the superior kinds. 
 
 Best Malleable Iron. The correct meaning of the term " best " is very 
 different to the signification of it in the iron trade, in which it now implies the 
 next better quality than common ; and it is usually said to be made by a 
 repetition of the process at the balling furnace, the forge, and the rough rolls; 
 that is to say, the rough bar of the common iron already described, is cut, piled,
 
 780 IRON. 
 
 and made into a bloom onco more, which confers upon the metal a more fibrous 
 texture, and considerably increases its toughness and elasticity. We believe, 
 however, that much of the iron that is sold under this denomination undergoes 
 a different process, which does not improve the quality to the same extent.. We 
 are informed that best iron is more commonly prepared from pig metal of a 
 better quality, namely, the dark grey, whose fracture is brilliant, and of a 
 silvery white colour. These are carefully refined and puddled, without any 
 admixture of inferior materials ; the bloom is well hammered, and when rolled 
 out into rough bar, it is made thinner than for common iron; this is afterwards 
 cut into short lengths, piled, reheated, and rolled out to the required size, as in 
 common iron. 
 
 Scrap Iron. There is another kind of best iron, distinguished by the name 
 of "scrap-iron," being made up of all the scraps, short lengths, ends cut oft 1 
 the finished bars, as before explained, and all the little bits of wrought iron 
 that can be collected together. Of these there is always a considerable quantity 
 accumulating in an iron work ; the larger pieces are made up into piles, and 
 the smaller into balls. The piles may be heated to a welding heat, and rolled 
 at once into finished bars, but the balls, consisting of smaller pieces, are shingled 
 under the great hammer, to consolidate them and bring them into the form of 
 a bloom. This bloom is reheated, and when rolled, produces excellent tough 
 iron, superior to the piled scraps that have not been shingled. Scrap-iron, thus 
 reworked, often produces so excellent a quality, as to fail under the denomination 
 of the next described quality of iron, namely, 
 
 Best-best Iron, No. 3, Chain-cable Iron. These names, and various others 
 intended to denote the superlative degree, are given by manufacturers to that 
 kind of iron which is deemed to be, in reality, of the best quality, prepared 
 with mineral coal. This metal is chiefly manufactured for the purpose of 
 enabling it to resist most effectually a longitudinal strain or tension ; and the 
 property is best acquired by the careful selection of the best materials, and 
 repeatedly cutting, piling, shingling, and rolling, as before explained. In the 
 preparation of this superlative quality of iron, the utmost attention to the process 
 is necessary ; and any bloom or bar that may be incidentally injured in its 
 tenacity should be rejected by the manufacturer, whose reputation might be 
 injured by such iron receiving the mark that properly belongs only to the 
 primest quality. It is this kind of iron which is chiefly employed in the making 
 of chain-cables, in tie-rods and bolts, that are subjected to a powerful strain. 
 
 Charcoal Iron. This term is originally applied to such iron only as had been 
 prepared solely with wood charcoal, from the ore to the malleable and finished 
 state ; but now the name of charcoal iron is given to malleable iron, the ore of 
 which may have been smelted with coke, in the ordinary blast furnace ; and it 
 acquires its distinguishing name from the circumstance of its being refined with 
 wood charcoal. The process of refining, and also that of puddling, are per- 
 formed as one in a puddling furnace, wherein it "comes round to nature," 
 combined with less impurities than by the common mode described. The bloom, 
 when taken out of the furnace, is put under the heavy hammer, and brought 
 to the form of a flat cake, when intended for sheet iron, in which state it is 
 denominated stamped iron. The stamped iron is next broken into pieces, piled, 
 heated, and again put under the hammer, which reduces it to a slab of about 
 one hundred-weight. These slabs are used for a variety of purposes; but their 
 chief application is by the manufacturers of tinned plates, who reduce the 
 "charcoal slabs " to the required thinness preparatory to the tinning operation. 
 (bee TINNING,) When the charcoal iron is required for bars, it is treated in all 
 respects in the same manner as in making of the very best chain-cable iron. 
 Owing to the large quantity and expensive nature of the fuel employed, 
 
 , , 
 
 machinery that are liable to severe tension. 
 
 ^ Re-manufactured Iron. Worn-out and broken articles of iron, termed old 
 iron, are collected throughout th > country, and purchased by a class of tradesmen
 
 IRON. 781 
 
 called dealers in marine stores, who sort them into three kinds for sale. The 
 * first is called " coach-tire," and consists of the old wheel tire of carriages, and 
 other large pieces; the second is called "nut, or scrap iron," and consists of 
 nuts, nails, screws, holdfasts, hinges, and an infinite variety of little solid 
 pieces; the third is called "bushel iron," and consists chiefly of very thin 
 articles of iron, such as those which have been of rolled sheets or hoops. The 
 last-mentioned is of the least value, on account of the great waste by oxidation, 
 and the trouble attending it. The iron so collected and separated by the dealers 
 is so considerable in and near London, that although a large portion of it is 
 sent by the Grand Junction Canal to the works in Staffordshire, and another 
 large portion of it is shipped on board the coal ships, in lieu of ballast, for the 
 Newcastle works, still there is a sufficient supply for three iron works near 
 the metropolis ; namely, one at Wandsworth, another at Chelsea, and a third 
 at Rotherhithe. The last- mentioned, called the King and Queen iron works, is a 
 very old establishment, and the most considerable of the metropolitan works, 
 the quantity of hoops and bars made there being from fifty to a hundred tons 
 weekly: the quality, also, of the iron manufactured at this work (well known in 
 the trade as King and Queen iron) is justly celebrated, which may be accounted for 
 by these circumstances nothing but old iron being used, the machinery being 
 of the most improved kind, and a vigilant attention to the essential parts of the 
 process. By the liberality of the proprietor, Mr. Howard, we have had an 
 opportunity of inspecting this work, of which we shall give such a brief notice 
 as will enable us thereby to complete our account of the manufacture of English 
 malleable iron. 
 
 A number of poor women are employed in piling up the scrap-iron into balls, 
 as they are called ; but the form is that of a short cylinder, resembling in size and 
 -figure the crown of a man's hat, somewhat narrower at the top than at the 
 bottom. A flat circular piece of sheet iron forms the foundation, and on that 
 is raised the fabric, the larger pieces on the outside, the smaller in the inside, to 
 fill up the interstices, and the whole as solid and compact as can readily be 
 done. Care is especially taken not to put any little bits of brass or copper that 
 may be accidentally mixed with the iron into the piles, which would prevent 
 the consolidation cr welding of the mass ; and, to encourage the vigilance of 
 the pilers, they are allowed the copper and brass they may thus find as perqui- 
 sites. The balls are put into a reverberatory furnace, similar to the puddling 
 furnace we have described : when brought to the proper welding heat, they are 
 subjected to compression by a "squeezer;" this is necessarily a very strong 
 machine ; it is composed of a fixed lower jaw, of great massiveness and breadth 
 (about a foot of superficies) en which the ball is laid, and is operated upon by 
 the motion and force of the upper jaw, which, being actuated by the engine, is 
 continually opening and shutting during the process, and thus it chews, as it 
 were, by half a dozen or a dozen bites, the great ball of iron into a suitable 
 shape to be passed between the shingling rolls, whereby it is, in a few seconds 
 reduced to a short, very thick bar or bloom. This bloom is re-heated in an air 
 furnace, and then it is reduced between the rollers to a bar, a plate, or a hoop, 
 equal in quality to the " best iron " from pigs ; but it is, nevertheless, the com- 
 monest iron made in this re-manufacturing pi'ocess. 
 
 We have now to explain the mode of preparing the larger pieces of old iron 
 before-mentioned for re-manufacture. A number of men and boys are employed 
 in clipping, with large fixed hand shears, the old hoops into convenient lengths, 
 and other old articles into suitable sizes, to be afterwards made up into bundles, 
 called faggots. The wheel tire, which requires great force to cut through, is 
 effected with a pair of shears worked by the steam-engine : the materials, as they 
 are cut, fall into barrows, in which they are conveyed to the faggotting depart- 
 ment, where several men are employed in preparing the faggots at a stout bench, 
 on which are fixed convenient little machines, for facilitating the operation. 
 One of these is represented at page 782. a a is a stout bridge-piece, in the centre 
 of which works the screw b, by turning the handles c c ; d d are two forked 
 bearers, in which are laid two soft iron bands e e, bended to fit the square to the 
 bottom of the Bearers. On these bands is first laid a piece of wheel-tire /; on 
 5 a
 
 782 
 
 IRON. 
 
 this tire, pieces of hcop and other thin stuff are then evenly laid, which last are 
 covered with another piece of tire g. Their crooked or curved forms prevent 
 their laying so close together as is desirahle; the turning of the screw, however, 
 forces them together very compactly, as shown in the sketch. Thus held down 
 
 by the screw, the bands e e are brought together and twisted, which holds them 
 fast, and the faggot is completed. The screw is turned back, the faggot taken 
 out, and others are made in like manner. The sizes of the faggots vary much, 
 being proportioned to the size of the bar, or other article to be made of it. If 
 not more than twenty or thirty pounds each, as required for making puncheon, 
 butt, or vat hoops, or small bars, they are, after being duly heated in the 
 furnace, at once rolled out into their intended dimensions. If the faggots are 
 large, they are heated and shingled into blooms, which are again heated when 
 required to be rolled out. It is the practice at these works, as well as others, 
 to prepare large quantities of blooms, to be kept as stock ; but there is a great 
 economy in finishing the work by the first heat of the faggot, and this is 
 facilitated by the quickness at which the rolls travel in making the lighter 
 articles above-mentioned ; and when, as at these works, the rolling is effected 
 by three rollers, one above another, by which the iron is rolled both backwards 
 and forwards (as before explained), a very long bar or hoop is completed in 
 little more than half a minute, and, consequently, while the iron retains a good 
 heat. 
 
 The first quality, or best king and queen iron, is thus prepared : a ball or 
 faggot, being duly heated, is first compressed a little by the squeezer, then rolled 
 to a flat bar in the shingling rolls; the bar is next cut into pieces, piled, 
 re-heated, and made into a best bloom under the shingling hammer. This best 
 bloom is next re-heated, passed through the roughing rolls, and then through 
 the finishing rolls, whereby it is brought to the form required. It is an important 
 consideration, that much of the old iron used in the re-manufacturing process 
 was originally the " best " iron of the first manufacturer ; and that as the 
 greater part of the old iron has been improved at the blacksmith's forge, it may 
 safely be said, that where the processes of refinement of the first manufacture"- 
 leave off, those of the re-manufacturer begin : and as it is universally admitted 
 that the more iron is worked, the better it becomes, (which is indeed proved by 
 the extreme tenacity of fine iron wire,) it seems to follow, that the re-manufac- 
 tured iron we have been describing must be greatly superior to that which is 
 newly made from pigs, however carefully the process may have been conducted, 
 or however often it may have been repeated. 
 
 Russian and Swedish Irons, which were formerly usually employed in our iron 
 manufactures, are still applied extensively at Sheffield and some other places, in 
 the fabrication of the superior kinds of steel and fine cutting instruments ; but 
 their application to other purposes is extremely limited, on account of their much
 
 IRON. 783 
 
 greater cost than our own best charcoal iron, which is scarcely inferior for most 
 purposes to which bar iron is applied. The Russian and Swedish irons are 
 entirely converted and refined with charcoal by processes so similar to our own 
 as not to need description. These valuable foreign irons are more particularly 
 noticed under the sub-head Steel in this article. 
 
 Malleable Cast-iron. A very extensive manufacture of iron articles is now 
 carried on at Birmingham, Sheffield, and other places, which although they are 
 cast from fluid metal, are nevertheless malleable. This property is derived 
 from two causes ; first, the pigs are prepared from the rich and pure iron ores 
 of Cumberland ; and the metal thus obtained is combined with but a small 
 quantity of carbon, so as nearly to resemble steel in colour, hardness, and the 
 brilliancy of its fracture ; and it has in consequence been designated by some 
 manufacturers, run steel. An infinite variety of articles, including nails, 
 saddlers' ironmongery, (and particularly such goods as afterwards receive 
 another metallic coat, as those which are plated upon steel,) are cast from 
 this metal. The castings thus produced are exceedingly brittle ; but this 
 property is entirely destroyed by a process termed annealing, in which the 
 metal is deprived of the carbon to which its previous fusibility was owing, 
 and is in consequence brought to that state of wrought iron requiring only the 
 operations of the shingling forge and rollers to give it a laminated and fibrous 
 texture. , Nails made by this process may be drawn out longer, and bent 
 backwards and forwards, without breaking. The metal is however not so 
 strong or tough as hammered and rolled iron ; the discovery of the process is 
 nevertheless of great value, as many excellent articles are produced in conse- 
 quence, which would not without it be made at double the cost. The discoverer 
 of this mode of converting cast-iron goods into malleable, was Mr. Samuel 
 Lucas, of Sheffield, who took out a patent for it in 1804; the specification of 
 which we shall annex, as there are some manufacturers who, while they avail 
 themselves of Lucas's process, assume it to be their own discovery, in conse- 
 quence of making some unimportant variations. " I declare that my said 
 invention of separating the impurities from crude or cast-iron without fusing 
 or melting it, and of rendering the same malleable and proper for the several 
 purposes for which forged or rolled iron was used, and also, by the same 
 method, of improving articles manufactured of cast-iron, and thereby rendering 
 cast or crude iron applicable to a variety of new and useful purposes, is thus 
 to be performed: the pig, or cast-iron, being first made or cast into such form 
 as may be most convenient for the purpose intended, it is to be put into a steel- 
 converting, or other proper furnace, together with a suitable quantity of iron 
 .stone, iron ore, some of the metallic oxides, lime, or any combination of these, 
 {previously reduced to powder, or into small pieces,) or with any other substance 
 capable of combining with, or absorbing the carbon of crude iron. A degree 
 of heat is then to be applied, so intense as to effect an union of the carbon of the 
 cast-iron with the substance made use of, and continued so long a time as shall be 
 found necessary to make the cast-iron either partially or perfectly malleable, accor- 
 ding to the purposes for which it may be wanted. If it be intended to make the 
 iron perfectly malleable, from one half to two-thirds of its weight of iron stone, 
 iron ore, or other substance, will be found necessary ; if only partially so, a 
 much less quantity will be sufficient. Five or six days and nights will in 
 general be found sufficient, during which to continue the heat, which towards the 
 close of the process cannot be too great. Care should be taken that the pieces 
 of cast-iron be not of too great thickness, as it would have the effect of length- 
 ening the process. But the proportion of the several substances made use of, 
 and the degree and duration of the heat to be applied, must greatly depend, not 
 only on the nature of those substances, but also on the nature and quality of 
 the pig or cast iron employed, a knowkdge of which can be obtained only by 
 experience. The cast-iron to be rendered malleable, and the substances to be made 
 use of for that purpose, may be placed in the furnace in alternate layers ; and in 
 order to prevent the iron stone, or iron ore from adhering to the iron, a thin layer 
 of sand may be placed between them. For the improvement of articles manufac- 
 tured of cast-iron, the same directions may be observed ; except that when tlie
 
 784 
 
 IRON. 
 
 articles are small, a less proportion of the substances for producing malleability 
 will be required, and ako a less degree and continuation of the heat." 
 
 Steel. We place this well known invaluable substance under the head of iron, 
 in preference to its own initial letter, considering that we may, with far more 
 propriety, class it under that denomination than cast-iron; for the latter, which 
 every body maintains to be iron, contains more foreign matter than steel, and 
 of the very same kind ; cast-iron containing about 7 per cent, of carbon or 
 other matter, and steel considerably less than one per cent. ; even so little in 
 some specimens, as a four-hundredth part. Steel is besides so much like malle- 
 able iron, in density and hardness, that few persons, comparatively speaking, 
 know how to distinguish one from the other. The difference between common 
 steel and common cast-iron we understand to be this ; that steel is a very com- 
 pact and nearlv pure iron, rendered more dense and hard by an intimate com- 
 bination with *a minute portion of carbon, with which in some specimens is 
 found manganese and silex ; and that cast-iron is a less dense and very impure 
 iron, combined in an almost granulated state with a large proportion of carbon 
 and other matters. We are supported in this view of the subject by the fact 
 that in the manufacture of steel with bar iron and charcoal, by the process 
 called cementation, the iron is increased in its specific gravity ; but if the pro- 
 cess of cementation be continued beyond the proper limits, the iron will absorb 
 more and more carbon, until it becomes disintegrated, and runs down into cast- 
 iron, the loose texture of which is indicated by its greatly reduced specific 
 gravity. 
 
 The specific gravity of steel is 7.827 
 
 malleable iron is . 7-788 
 
 cast-iron is ... 7.207 
 
 Now white cast-iron contains much less carbon than black cast-iron, and in 
 consequence approximates more to the nature of steel. But white pig metal, 
 obtained from the generality of British ores, and smelted with coke, contains so 
 much impurity, that our manufacturers, rather than make steel direct, by 
 abstracting the principal portion of the carbon from the pig, prefer purging the 
 latter entirely of its carbon and other matters, by the expulsion .of which it is 
 converted into malleable iron, (as already fully explained in the iron manufac- 
 tures;) and then giving the malleable iron that small dose of carbon by which 
 it is made into steel. 
 
 Natural Steel. In those countries where iron ores are found extremely rich 
 and pure, and their reduction is effected by charcoal, excellent steel is produced 
 from cast-iron, without an intermediate process ; and this kind of steel has in 
 consequence received the distinguishing name of Natural Steel. Formerly, this 
 kind of steel was fabricated and chiefly used in this country, and it is still made 
 in Styria and Catalonia, with great success. The French some time ago 
 attempted the imitation, but notwithstanding some of their most scientific men 
 were engaged in the undertaking, they failed in obtaining a natural steel equal 
 to that which they imported from Germany. It had been previously asserted 
 by Bergmann, that the natural steel of the Styrian and Nassau Liegen foun- 
 dries, derived its excellence from containing a portion of manganese ; and this 
 opinion was subsequently corroborated by a writer in the Annalcs de Chimie, who 
 had made some comparative analyses of the ores used in France and Germany. 
 In support of his opinion, he mentions the fact that in the territories of Nassau 
 Liegen, there are mines of manganese, and that the black oxide of that metal is 
 employed as a flux in smelting iron intended for steel when their ores are found 
 to be naturally deficient of that substance. This writer states, that steel in 
 general, but particularly natural steel, is essentially an alloy of iron and manga- 
 nese, combined with carbon, and that this alloy is the natural steel of Germany, 
 generally in these proportions: 
 
 Iron 96.84 
 
 Manganese 2.16 
 
 Carbon 1.00
 
 IRON. 785 
 
 Hence he concludes that good natural steel ought to contain twice as much 
 manganese as iron. Several years ago, the writer of this article (having a dif- 
 ferent object in view) mixed some black oxide of manganese with melted cast- 
 iron, and the result was an exceedingly hard alloy, resembling steel. For 
 obtaining natural steel, the ore is smelted, as for iron in blast furnaces ; but the 
 blast given is weaker, and is directed not upon the metal, but in a horizontal 
 direction above it. The metal is kept covered with slag, and is not disturbed 
 by stirring. When the iron is judged to be sufficiently refined, and has 
 become nearly solid, it is taken out of the furnace and forged ; after this, 
 natural steel is withdrawn, there remains at the bottom of the furnace one or 
 more pigs of cast-iron, rather hard, which are generally employed in fabricating 
 implements of husbandry. The natural steel of Germany is extensively em- 
 ployed on the continent in the making of files, and various sorts of tools. The 
 celebrated steel from Damascus, called damask steel, and that from Bombay, 
 called Wootz, are both natural steels, being converted directly from the ore in 
 crucibles. These " fancy steels," however, we shall take some further notice of, 
 after having explained the more important operations of our manufacturers. 
 
 Blistered Steel. The first process employed by our manufacturers in the pre- 
 paration of steel is to stratify malleable bar iron with pounded charcoal in alter- 
 nate layers, in a close furnace, to cause a gradual absorption of the carbon by 
 the metal. In the engraving on p. 786, Fig. 1 represents a vertical section of 
 the kind of furnace employed for this purpose ; and Fig. 2 represents a plan of 
 the interior structure, without the external conical walls which surround it. a 
 and b are the troughs, called cementing pots, in which the bars of iron are laid to 
 be converted into steel ; the pots are made of a peculiar kind of fire-stone, not 
 liable to crack or fuse; their dimensions are usually from 10 to 15 feet long, 
 and from 24 to 30 inches in width and depth. The bars of iron, and the pow- 
 dered charcoal are laid in the pots in alternate strata ; the upper stratum of 
 bars being covered with a thicker layer of charcoal than those underneath ; above 
 which is also laid a mixture of sand and clay, to prevent the charcoal from entering 
 into combustion by access of the outward air. c is the external cone, of strong 
 masonry or brickwork, of from 40 to 50 feet high. Inside this superstructure is 
 a smaller conical dome d, called the vault, which is built substantially of fire-brick, 
 or other material, capable of withstanding an intense heat. The vault rests upon 
 external walls e e, at a distance from those which support the external cone, and 
 the space between them is filled up with rubbish, sand, &c. The cementing pots 
 and b are supported upon a series of detached courses of fire-brick, leaving 
 spaces or flues between them to conduct the flame under the pots. In the same 
 manner the sides of the pots are supported from the vertical walls of the vault, 
 and from each other by a few detached stones, so as to intercept the heat The 
 vault has a series of short chimneys to conduct the smoke into the great cone 
 c, as shown at//. In the front of the furnace, an aperture is made through 
 the external building, and another corresponding in the walls of the vault; 
 these openings form the door, at which a man enters the vault to put in or take 
 out the iron ; but when the furnace is lighted, these doors are closed by fire- 
 bricks, luted with fire-clay. Each pot has also small openings at each end, 
 through which the ends of two or three bars are left projecting in such a manner 
 that, by only removing one loose brick from the external building, the bars can 
 be drawn out without disturbing the process, to examine the progress of the 
 conversion from time to time ; these are called tap-holes, and should be placed 
 in the centre of the pots to obtain a fair specimen of their product. The fire- 
 grate is shown in Fig. 1 at g, consisting of bars laid over the ash-pit h, which 
 must have a free communication with the open air. The attendant examines 
 the state of the fire from the ash-pit h, which has steps leading down to it, and 
 when he perceives any part of the fire not very bright or fierce, he thrusts a 
 long hooked bar through the grating, and opens a passage for the air. The 
 fire-place has no door, being built open at each end ; but a quantity of coals is 
 piled up before each aperture, so as to close the openings, and answer effectually 
 the purposes of doors ; from this heap of coals the workman shoves in, with a 
 kind of long hoe, such quantity as may be required to replenish the furnace
 
 786 
 
 IRON. 
 
 from time to time, and the renewal of the coals to the heap prevents any air 
 entering the furnace, but such as has passed upwards through the ignited fuel, 
 and contributed to the combustion. The heat and flames from the fuel are 
 reverberated by the dome d, and have passages underneath and around the 
 pots The degree of heat at which the carbon begins to be absorbed, is found 
 to be about 70 of Wedgwood's pyrometer ; this heat is kept up for about 
 7 or 8 days, according to the thickness of the bars, and the degree of carboni- 
 zation required. When the process is completed, the furnace is suffered to 
 
 Fig. I- 
 
 Fig. 2. 
 
 cool, which takes 6 or 7 days more ; the contents of the pots are removed, and 
 the fresh charges put in, the charcoal serving again, as it is scarcely altered 
 from not having entered into combustion. The bars of iron are now found to 
 be covered with blisters and projections, to have acquired a brittle quality, and 
 to exhibit in the fracture a crystalline structure, which is uniform throughout 
 the bar if the carbonization has been complete. The degree of carbonization 
 is varied according to the purposes for which the steel is intended ; and so
 
 IRON. 787 
 
 likewise is the nature and quality of the iron employed for the purpose. For 
 the finest and most important purposes, the Russian and Swedish irons are 
 always employed for conversion, by reputable manufacturers ; and there are 
 certain kinds, of long-established celebrity, to which a very general preference 
 is given ; these are distinguished by well-known marks stamped upon them, 
 which the governments of the countries whence they are imported warrant the 
 authenticity of. Amongst the chief of these marks may be particularly men- 
 tioned L inside a circle (called hoop L) ; G, with an L connected to the bottom 
 of the G (called G L) ; two small circles (called double bullet) ; a G, and an F 
 underneath, connected to it (called GF); an ellipsis, with some lines across its 
 shortest diameter (called gridiron) ; J B, the J being made out of the upright 
 line of the B (called J B) ; a stag's head and antlers (called stein-buck) ; a 
 crown, with a C close underneath (called C and crown). Of course there are 
 as many marks as there are manufactories or mines, many of which may furnish 
 as good iron, but they are not yet so well established. There is, however, pro- 
 bably some exceptions to this remark, and undoubtedly the Russian iron, branded 
 C CIV) D, is an exception. The hoop L, which is the produce of the Dannimora 
 mines, in Sweden, is considered the most valuable ; forty pounds sterling per 
 ton being readily paid for it, which is about four times the price of the best 
 English bar iron. However immense this difference of cost to the steel 
 manufacture!-, it is of trifling importance compared to that of maintaining his 
 reputation for the production of an unexceptionable article. The paying of 
 threepence per pound more for the raw material, will make no perceptible dif- 
 ference in the cost of the artist's graver, the surgeon's lancet, or even the 
 writer's pen-knife not to mention watch springs, and a thousand other appli- 
 cations of fine steel, in which, were it necessary to insure perfection of quality, 
 a hundred times the cost of the raw material added to the manufactured article 
 would be gladly paid. 
 
 Mackintosh's Patent. A few years ago Mr. Mackintosh, of Crossbaskets, in 
 Lanarkshire, took out a patent for converting malleable iron into steel, by sub- 
 jecting it to a stream of carburetted hydrogen gas, evolved from coal under dis- 
 tillation. The iron is inclosed in a pot or crucible in the furnace, and when 
 arrived at a proper heat, a stream of gas is directed by a pipe into the crucible, 
 which has another aperture to allow that part of the gas to escape which has not 
 been taken up by the metal. The apparatus for conducting this process will 
 of course admit of various modifications. This invention appears to have 
 reason for its basis ; for it must be evident that hi the process of cementation 
 before described, the carbon must have entered into combination in a gaseous 
 state with the iron : the steel made by it was reported to be excellent. 
 Whether experience has proved it to be an economical process, is a point upon 
 which we are not informed. 
 
 Mushafs Patent Steel. The preceding articles are descriptive of three dis- 
 tinct modes of preparing steel. First, by the careful refinement of cast-iron ; 
 second, by the stratification of malleable iron with charcoal ; and third, by the 
 application of gaseous carbon to the metal. A fourth process, materially dif- 
 fering from those, but producing very similar results, and attended with some 
 peculiar advantages, was patented in the year 1 800 by Mr. Mushat, the gen- 
 tleman whose metallurgical labours we have before noticed. The specification 
 of the patent directs that malleable iron (in scraps or bars) is to be put into a 
 crucible, together with a due proportion of powdered charcoal, or pit coal, 
 plumbago, or any other substance containing the carbonaceous principle, and 
 subjected to an intense heat in an air or blast furnace until the metal is reduced 
 to a fluid state, when it is to be poured out into moulds to form ingots, or any 
 other article that may be required ; which castings will be of a similar nature 
 to the steel produced by cementation. But in those cases when iron ore can 
 be obtained sufficiently rich and free from foreign admixtures, the patentee pro- 
 poses to save all the time and expense attending the tedious operations neces- 
 sary for the conversion of such ore, first into cast-iron, and afterwards into bar 
 iron ; for such ore, he observes, being previously roasted or torrified, may be 
 substituted for the malleable iron, and the result will be cast-steel, provided
 
 788 
 
 the proper quantity of carbonaceous matter be used, as for the common 
 and ordinary qualities of cast steel. The quantity of carbonaceous matter 
 required, is much less than had been previously supposed to be necessary. In 
 employing wood charcoal, from a seventieth to a ninetieth of the weight of the 
 iron being sufficient ; and when the quantity is increased beyond a seventieth 
 to a sixtieth, or a fortieth of the weight of the iron, the steel becomes so fusible 
 that it may be run into moulds of any shape, and afterwards be capable of 
 being filed and polished. Hence, by casting, may be constructed stoves, grates, 
 kitchen utensils, wheels, mill-work, and a great variety of things which could 
 not be so made by the processes previously in use. By varying the proportions of 
 the carbonaceous matter, he can make as great a variety in the qualities of the 
 steel, as the various kinds of pig-metal differ from each other. Cast-steel, made 
 in the ordinary way, Mr. Mushat observes, is so volatile when in fusion as not 
 to admit of being run into any shape except straight moulds of considerable 
 diameter ; but that steel of such density as to admit of being cast into any form 
 may be produced by his process, by increasing the quantity of charcoal, and 
 fusing the matter as before directed. To produce qualities of steel softer than 
 is usually manufactured by the common processes, he uses a very small propor- 
 tion of charcoal, sometimes so little as a two-hundredth part of the weight of 
 the iron ; and he states that steel produced with any proportion of charcoal not 
 exceeding the one-hundredth part, will generally be found to possess every 
 property requisite to its being cast into those shapes which require great elas- 
 ticity, strength, and solidity ; and will also be generally found capable of sus- 
 taining a white heat, and of being welded together like malleable iron. 
 
 Tilted Steel. As blistered steel in its crude state is applicable to but few 
 purposes, it is moderately heated in a furnace, and subjected to the action of a 
 tilt hammer, which strikes about 700 blows per minute : this operation increases 
 its tenacity and solidity, and adapts it to numerous uses. 
 
 Shear Steel. This name was given to a steel that was first made by Crowley, 
 of Newcastle, about sixty years ago, in imitation of a peculiar kind of bar 
 steel that we formerly imported from Germany. Crowley, however, stamped 
 his production with the figure of a pair of shears, to indicate its suitable 
 application. The process of making it at Sheffield, where the manufacture 
 of this and all other kinds of British steel is conducted on an immense scale, is 
 as follows : The bars of blistered steel are broken into pieces of from one to 
 two feet in length, which are then piled up into bundles or faggots of a size 
 and weight adapted to their subsequent applications, The faggots are then taken 
 up by means of a long bar having a ring at the end, into which one extremity 
 of the faggot is inserted ; and by means of the bar as a handle, a workman puts 
 it into a reverberatory furnace, whence, after it is brought to a welding heat, it 
 is taken out and placed under a heavy hammer, by which it is drawn out into 
 a bar ; this bar is then divided, the pieces laid together, brought again to a 
 welding in the furnace, and then under the hammer, or by rolling, reduced to 
 the size required. By this process the steel has lost much of its previous brit- 
 tleness, and has acquired a uniform texture, which adapts it to the manufacture 
 of a great variety of edge tools and other purposes to which it was before 
 unsuited. Various qualities of shear steel are made, distinguished by the terms 
 half-shear, single-shear, and double-shear, according to the number of times it 
 has been cut, piled, welded, and drawn out. 
 
 Sandersons Patent. In September, 1828, a patent was taken out by Mr. 
 Charles Sanderson, of the Park Gate Iron Works, entitled " A new process or 
 method of making shear steel," which, the specification informs us, consists 
 in forming shear steel out of very small pieces of bar steel, instead of 
 pieces from one to two feet in length, as heretofore, whereby he is enabled to 
 form shear steel with fewer heats, and consequently with less waste, and 
 without the use of silicious sand, as heretofore practispd. The patentee describes 
 his mode of operation in the following words : " I take bar steel in the state 
 in which it comes from the converting furnace, and break it into very small 
 pieces of one inch to two inches long ; a quantity of these small pieces being 
 ready, I procure a round stone of any quality which is capable of withstanding
 
 IRON. 789 
 
 the strong heat of a reverberatory furnace without cracking or breaking ; and 
 upon this stone the small pieces are piled as closely and compactly as possible ; 
 the whole is then inclosed in a fire-clay crucible, and placed in a reverberatorv 
 furnace, where it is allowed to remain until the whole mass becomes of a hign 
 welding heat. It is then taken from the crucible and placed under a heavy 
 cast-iron hammer, usually called a metal helve, and exactly the same as those 
 used in the manufacture of bar iron : this hammer is driven by machinery, and 
 from the circumstance of the whole mass being in a semi-fluid state, it is almost 
 instantaneously hammered or manufactured into one solid mass or bloom of 
 steel, of from three to four inches square ; this bloom is placed in a furnace, or 
 as it is more generally termed, a hollow fire, of two or three feet square, heated 
 with coke, and the heat increased by the application of a blast of air ; and the 
 whole mass or body of steel so hammered or manufactured as aforesaid, is 
 raised to a high welding heat ; it is then taken from the furnace, and placed 
 under the same metal helve or hammer before mentioned, and drawn into a bar 
 of shear steel, ready to be tilted or rolled into the various sizes or shapes which 
 may be required. For shear steel, to be used for inferior purposes, it might be 
 too expensive to place the piled steel in a crucible, but it might merely be placed 
 in a reverberatory furnace, and drawn thence, when it is of a complete welding 
 heat." 
 
 Cast Steel. The finest and very best steel for most purposes, is that which 
 has undergone the process of fusion and a subsequent hammering, called cast 
 steel. It is about ninety years since this steel was introduced by one Hunts- 
 man, of Attercliffe, near Sheffield, whose name it continued to bear for a long 
 time; but his rivals at Rotherham and Sheffield, who subsequently undertook 
 the manufacture, gave it the more significant name which it now bears. The 
 process of preparing it on the large scale, is as follows : Blistered steel is 
 broken into small pieces, and put without any admixture into crucibles that 
 hold about 40 Ibs. each, and are covered with a lid. The crucibles are sepa- 
 rately deposited in a row of small melting furnaces, which are usually square 
 pots, about 15 inches wide and 3 feet deep, with a grating at bottom ; the tops 
 of these furnaces are open, and level with the floor of the foundry ; and just 
 below their tops are lateral apertures or flues, leading into the common chimney 
 of all the furnaces ; access to the fire-places and ash-pits is had in a vault under- 
 neath. The fuel employed is hard coke, in which the crucibles are entirely 
 imbedded and covered over ; then each of the furnace mouths is stopped with 
 a trap-door of fire-bricks, inclosed in an iron frame. This being done, a very 
 sharp draught of air is produced from the ash-pits, through the fuel, into the 
 lateral flues, and a very intense heat is produced, which, being kept up for four 
 or five hours, the steel is thereby brought into perfect fusion, when it becomes 
 necessary to remove the crucibles, and pour out their contents into cast-iron 
 ingot moulds, prepared for their reception, which are either in the form of a 
 short thick bar, for being tilted, or a thick flat cake, to be lamellated between 
 the rolls. The melter has likewise to prepare himself against the terrible ordeal 
 of the operation just mentioned : to protect himself from the fierce fire of the 
 furnaces, as he bends over their mouths, which would otherwise set his clothes 
 on fire, he puts on an armour of coarse sacking ; and then, with a pair of long 
 iron tongs, he gripes the blazing crucible, and, quickly lifting it out of its 
 chamber, pours the contents into the moulds. The subsequent processes upon the 
 ingots, bars, or plates of steel, cast in the moulds to bring them to the required 
 shapes, are in every respect the same as we have described for preparing iron 
 into similar forms ; but on account of the greater value of steel, and the delicate 
 manner in which it is often wrought, the rolling and hammering processes 
 become more essential in perfecting the quality, and therefore they are more 
 carefully performed. For the best purposes, steel is always preferred that has 
 been drawn to its required sizes under a tilt hammer, which gives three or four 
 hundred blows per minute. It is however deserving of remark, that when 
 steel rods and bars have been repeatedly rolled at a low heat, they acquire the 
 same density, and more uniformity, than tilted steel. 
 
 Ncedham's Patent. A patent for a new process of casting steel was taken 
 5 H
 
 790 IRON. 
 
 out in 1824, by Mr. Needham, of Davis -street, Fitzroy-square. His plan is to 
 employ large fixed or stationary crucibles (made of lire-stone, or Stourbridge 
 clay), and allowing the steel, when melted, to flow from them, through suitable 
 apertures :nade in the sides, into the moulds, instead of moving the melting- 
 pots already described. The size and shape of these stationary crucibles, it is 
 stated in the specification, may be varied according to circumstances, but a 
 preference is given to an oblong form, with movable covers, fixed upon bearers 
 of fire-brick or stone, on a plane a little inclined from the horizontal line ; at 
 the bottom of each crucible a perforation is made, to which is fixed a tube, that 
 passes through the furnace to the moulds, with a plu^r at the external end; this 
 being withdrawn, the fluid metal readily discharges itself into the moulds. In 
 this manner several melting-pots may be fixed in one furnace, so that a quan- 
 tity may be fused sufficient for articles of great magnitude; and as the different 
 descriptions of steel require different degrees of heat for their fusion, the 
 patentee recommends that those which require the least be placed in crucibles 
 above those which require the most ; by which arrangement, in casting large 
 shafts or cylinders of steel, those parts that require it may be formed with the 
 best steel, while those parts wherein an inferior steel answers the purpose, may, 
 in like manner, be supplied with it. If it be required to cast a large cylindrical 
 steel roller, the exterior may be made of a superior quality of steel, and the 
 interior of a common quality, by placing a cylinder of wrought iron within 
 the hollow cylindrical mould ; and then directing jets of fluid steel, of distinct 
 qualities, to flow into the opposite sides of this circular wrought-iron partition ; 
 the steel will then adhere to the iron, and form one solid roller, of inferior cost, 
 but equal in quality to one made entirely of superior steel. 
 
 Thompson's Patent. A short time after the granting of Mr. Needham 's 
 patent, Mr. Thompson, of the Chelsea-street Works, took out another, having 
 a very similar object in view. He proposes, in the first place, to melt the steel 
 in a reverberating or puddling furnace, by which pit-coal may be used instead 
 of coke ; secondly, instead of the movable crucibles in general use, he employs 
 stationary vessels, marie of the usual materials, but of a semi-cylindrical shape, 
 having spherical ends, and a rebate or groove in the upper edges, to fit a cover 
 to it. These are to be fixed on a slightly-inclined plane, fcr the convenience 
 of the fluid discharging itself through a hole in the bottom, in which is inserted 
 a tube of platina ; this tube is connected to another tube of fire-clay, passing 
 through the brick-work to the outside of the furnace, through which the metal 
 flows into moulds, through apertures previously stopped with clay, which are 
 tapped by means of a long rod tipped with platina. 
 
 Alloys of Steel. Messrs. Farraday and Stodart, a few years since, made a 
 series of experiments on the combinations of some other metals with steel, an 
 account of which was published by them in the Philosophical Transactions for 
 1822 ; amongst the results of these experiments the following appear to be most 
 worthy of notice. Silver can be alloyed with steel only to the extent of a five- 
 hundredth part; when more was used, it either evaporated, or separated as the 
 button cooled, or was forced out in forging. The alloy was said to be excellent ; 
 and the addition of price was no obstacle to its use for fine instruments. 
 Steel, alloyed with one-hundredth part of platinum, though not so hard as the 
 silver alloy, has more toughness; where tenacity as well as hardness is required, 
 the extra cost was considered to be more than counterbalanced by its excellence. 
 As far as the experimenters could judge, neither gold, tin, nor copper, improved 
 steel. Messrs. Stodart and Farraday's memoir on this subject having been 
 noticed in the public journals, some of our Sheffield manufacturers wisely con- 
 sidered that it afforded them a favourable opportunity to advertise themselves to 
 the public, along with their wares made of " silver-steel ; " and, for a while, 
 knives and scissars, exquisitely finished, made of that " invaluable" alloy, were 
 alone the fashion. Rival manufacturers sought in turn to amuse the public 
 with Wootz, and Damascus, and Peruvian steel ; and each of these were, for a 
 time, necessary to the novelty-loving part of the public. Time had, however, 
 swept nearly all the notices of these wonders of the day from our shop windows, 
 and old-fashioned steel was quietly resuming its sway, when suddenly meteor
 
 IKON. 791 
 
 tteei made its appearance, not from the clouds, nor the moon, nor from a 
 volcano, but from the patent office, as will appear from the subjoined account 
 of the enrolled specification. 
 
 Meteor Steel. The patentees of this manufacture (Messrs. J. Martineau, jun. 
 and W. H. Smith,) specify their object to be the preparation of an alloy of steel, 
 having that peculiar wavy appearance exhibited in the Damascus sword blades, 
 and likewise for producing their toughness and elasticity of temper. The process 
 of preparing the alloy is thus described: zinc 80 parts, purified nickel 16 parts, 
 silver 4 parts = 100 parts. These are put into a black lead crucible, and 
 covered with charcoal ; the lid is then luted down to prevent evaporation, and 
 exposed to the heat of an ordinary steel furnace, until the metals are fused, 
 when the alloy is poured out into cold water, to suddenly cool it, which renders 
 it so brittle, that it is easily reduced afterwards, by a pestle and mortar, to 
 powder, which the patentees call meteor powder, and is incorporated with the 
 steel, together with other mixtures, in the manner following: 281bs. of common 
 blistered steel, 10 oz. of meteor powder, 7 oz. of powdered chromate of iron, 
 1 oz. of charcoal, 2 oz. of quick-lime, and 3 oz. of porcelain clay, are put 
 together in a crucible, and fused in a cast-steel furnace. After casting, this 
 alloy is to be drawn out, under a hammer, into bars, when it will be found to 
 exhibit the damask wavy appearance on its surface. To bring out the damask 
 more fully upon any article made of this alloy, the surface is to be polished, and 
 then washed over with nitric acid, diluted with nineteen times its weight of 
 water. It could hardly have been supposed by the patentees that such a 
 variety of substances was necessary to producing the damask pattern upon 
 steel ; the nickel and the chromium were probably introduced by them with the 
 view of imitating those natural phenomona called meteoric stones, in which it is 
 said one or both of these metals are constantly found : and as two or three of the 
 other ingredients of this patent steel mixture may he regarded as fluxes, it is not 
 quite so whimsical a compound as it might at first appear, especially as it was 
 introduced at a time when the public taste for steel-extraordinary was so much 
 excited. 
 
 Wooiz. This celebrated steel is made in India, at little furnaces supplied 
 with air by several pairs of small bellows, worked assiduously by men and 
 boys; and thus is produced the raw material of the famed Damascus sword 
 blades, the various patterns upon which have been imitated in our linen manu- 
 facture, and hence called damask. To ascertain the cause of this beautiful 
 appearance has given rise to a good deal of investigation, and several of our 
 chemists, as well as others on the continent, have entered upon the inquiry. 
 The wootz imported from Bombay is in form of a round cake about21bs. weight 
 Dr. Pearson, in an essay published many years ago in the Philosophical 
 Transactions, Vol. XVII., gave it as his opinion that it is made direct from the 
 ore, and, consequently, that it has never been in the state of wrought iron. 
 " For the cake," he says, " is evidently a mass which has been fused ; and the 
 grain of the fracture is what I have never seen in cement steel before it is 
 hammered or melted." This opinion consists with the composition of wootz; 
 for it is obvious that a small portion of oxide of iron might escape metal- 
 lization, and be melted with the rest of the matter. The cakes appear to have 
 been cut almost through, while white hot, at the place where wootz is manu- 
 factured ; and as it is not probable that it is then plunged in cold water, the 
 great hardness of the pieces imported above that of our steel must be imputed 
 to its containing oxide, and, consequently, oxygen. The particular uses to 
 which wootz may be applied may be inferred from the preceding account of its 
 properties and composition. A very general opinion is, that the waved appear- 
 ance is produced by an intermixture of steel and iron forged together, an 
 opinion that is in some degree founded upon experiment, as very close resem- 
 blances have been made by that process. Many sword blades, in no respect 
 inferior to the Eastern originals, have been fabricated in the dominions of 
 Austria and Prussia, by a process invented by Professor Crevilli, who had 
 given detailed instructions for their manufacture in a small treatise published 
 at Milan, and entitled, Memoria suW Arte di fablricare le Sciabole di Damasco.
 
 792 IRON. 
 
 An epitome of Crevilli's treatise was published in the Allgemaine Militar 
 Zeitung, the following translation of which was given in a recent number of the 
 United Service Journal. "A long flat piece of malleable steel, of about one 
 inch and a half in breadth, and one- eighth in thickness, is to be first bound 
 with iron wire, at intervals of one-third of an inch. The iron and steel are 
 to be then incorporated by welding, and repeated additions (10 or 20) of iron 
 wire made to the first portion, with which they must be firmly amalgamated. 
 This compound material is then to be stretched and divided into shorter lengths, 
 to which, by the usual process of welding, grinding, and tempering, any wished- 
 for form may be given. By filing semicircular grooves into both sides of the 
 blade, and again subjecting it to the hammer, a beautiful roset-shaped Damascus 
 is obtained: the material can he made to assume any other form. The solution 
 by which the figures are made visible, is the usual one of aquafortis and vinegar. 
 The success of this method, and the excellence of the blades which have been 
 constructed according to these directions, have, by various trials, been placed 
 beyond all doubt. Professor Crevilli has had several sabre blades prepared 
 under his own instruction at Milan ; similar experiments have, by the Emperor's 
 commands, been made at the Polytechnical Institution at Vienna: and finally, 
 the War Office has empowered Daniel Fischar, a manufacturer of small arms in 
 that capital, to proceed with the manufacture on a largo scale. These blades, 
 which, when made in large quantities, are but little dearer than those in common 
 use, have been submitted to the severest tests. . . .An idea of their extra- 
 ordinary tenacity may be formed from the fact, that out of 210 blades that 
 were examined by a military commission, and each of which was required to 
 bear three cuts against iron, and two against a flat wooden table, not a single 
 one snapped, or had its edge indented. In Prussia this method of preparing 
 sword blades is stated to have been in practice several years, and to have been 
 attended with equal success." M.Breant, examiner-general of assays at the 
 Royal Mint of Paris, investigated the nature and composition of wootz very 
 philosophically. In an interesting memoir which he published on this subject, 
 he observes, that if in the preparation of ordinary steel sufficient carbon has 
 not entered, the steel formed will only be in proportion to the quantity of 
 combined carbon ; the rest will be iron, only mixed. The cooling then takes 
 place slowly, the more fusible particles of steel will tend to unite together and 
 separate themselves from the portion of iron. This alloy will therefore be 
 capable of developing a damask, but this damask will be white, and slightly 
 marked, and the metal will not be susceptible of great hardness, because it will 
 be mixed with iron. If the proportion of charcoal be exactly such as it ought 
 to be in order to convert the whole of the iron into steel, there will be only 
 one sort of combination; but if the carbon is a little in excess, the whole of the 
 iron will in the first place be converted into steel, afterwards the carbon remaining 
 in the crucible will combine in a new proportion with the part of the steel already 
 formed. There will in this case be two distinct compounds, namely pure steel, 
 and carburetted steel, or cast iron. These two compounds, at first mixed con- 
 fusedly, will tend to separate when the liquid matter remains at rest. A 
 crystallization will then form, in which the particles of the two compounds 
 will arrange themselves according to their respective affinity or specific gravity. 
 If a blade made of this steel be put into acidulated water, a very apparent 
 damask will be developed, in which the pure steel parts will be black, and those 
 of carburetted steel will remain white. The carbon irregularly dispersed in the 
 metal, and forming two distinct combinations, is, then, that which occasions the 
 damask ; and it is obvious that the slower the cooling, the larger the veins of 
 the damask should be. 
 
 " Plumbago," says M. Breant, " has appeared to me in some circumstances to 
 soften the steel, which an excess of carbon would render too harsh ; at least I 
 have obtained excellent results with a hundred parts of steel, one of smoke- 
 black, and one of plumbago. But a very remarkable experiment in regard to 
 the advantage which may be derived from it, in working on a large scale, is 
 that a hundred parts of soft iron, and two of smoke-black, melt as easily as com- 
 mon steel." From this announcement by M. Breant, it appears, that he was
 
 IRON. 7!>a 
 
 unacquainted with Mr. Mushat's patent process of converting malleable iron into 
 steel by fusion with charcoal, described at page 787. M. Breant continues, ' It 
 must be supposed that the whole of the carbon does not enter into combination. 
 Some of our best blades are the product of this combination. It is evident from 
 this experiment that it is not necessary, in order to obtain very good steel, to 
 begin the operation by cementation with iron. The iron may be treated 
 immediately with the smoke-black, and this would greatly diminish the 
 expense of the manufacture. A hundred parts of the filings of very grey 
 cast-iron, and a hundred parts of similar filings previously oxidized, have pro- 
 duced a steel of a fine damask, and fit for the manufacture of bright arms ; 
 it is remarkable for its elasticity, a quality not possessed by the Indian steel. 
 The more carbon the steel contains, the more difficult it is to forge. Most 
 of the specimens that I have prepared have not been drawn out, but at a 
 temperature the limits of which are extremely confined." " I am convinced 
 from experience, that the orbicular veins called ronces by the workman, which 
 are seen on fine oriental blades, are the result of the manner of forging. If 
 we content ourselves with drawing the steel out lengthwise, the veins will be 
 longitudinal ; if we extend it equally in all directions, the damask has a crys- 
 talline appearance. If we render it wavy in the two directions, there will be 
 shades and gradations as in the oriental damask. It will not require long trials 
 to produce any variegated design we desire." Repertory of Arts. 
 
 Having explained the most approved modes of preparing the celebrated 
 damasked steel, as well as the various steels of our now no less celebrated British 
 manufacturers, we proceed to the consideration of another department of the 
 subject. 
 
 Case-hardening. This is a process for converting the surface only of articles 
 made of malleable iron into steel, in order that they may afterwards receive a 
 Aigh polish. The process is extensively applied to the pokers, tongs, and 
 shovels of our domestic fire-grates, and to an infinite variety of our iron manu- 
 factures. The following mode, recommended by Mr. Gill, editor of the Techno- 
 logical Repository, deserves confidence, from the extensive practical knowledge 
 of that gentleman in the treatment of iron and steel. This is effected, he says, 
 by inclosing the articles in carbonaceous compounds, either animal or vegetable, 
 and exposing them to heat in close vessels, until the change is completed, and 
 until the surface at least of the articles is converted into steel. For this pur- 
 pose, bones, from which the ammonia has been extracted by distillation at a high 
 temperature, and which are afterwards ground to a coarse black powder, are 
 chiefly used. The articles being surrounded with this powder, contained in cast- 
 iron vessels, are exposed to a high red heat, in an open fire-place, for several hours, 
 until the surfaces of the iron articles are sufficiently changed to steel ; when, if 
 large enough, they may be taken out, whilst hot, and quenched in water, or if 
 too small and numerous, the whole contents of the vessel, bone-dust and all, 
 may be poured into the water. Any parts of the articles which are required to 
 remain iron after this operation, may be guarded from the action of the carbon, 
 by coating them with clay or loam. Sometimes the water is covered with a 
 layer of oil, two or three inches in depth, to prevent the small steel articles 
 from being cracked hi quenching ; and it is very convenient in this case to 
 have a wire sieve suspended in the water, at a proper depth beneath its surface, 
 to suffer the bone ashes to fall through, but to detain the small articles. Other 
 substances are employed in case-hardening; leather, burnt till it can be pulve- 
 rised, is considered a good agent ; also the hoofs and horns of animals, heated 
 in an oven until they can be beaten to a coarse powder : the latter are preferred 
 by gunsmiths for their work. 
 
 Hardening and Tempering. In giving the requisite degree of hardness to cut- 
 ting instruments of steel, two distinct processes are employed ; first, hardening, 
 and afterwards tempering. The hardening is effected by heating the steel to a 
 cherry-red, and immediately plunging it into cold water ; by this process, the 
 steel becomes so hard as to resist, or turn the edge of the hardest file ; likewise 
 so brittle as to be useless for most purposes, but particularly for cutting instru- 
 ments. To adapt the steel to the latter, the second process, called tempering,
 
 is resorted to, which is a species of annealing, or softening, or as the workmen 
 term it, letting down, to the degree of hardness which is necessary for the peculiar 
 purpose for which it is designed; for in proportion as the edge is harder 
 than is required, is its liability to break in use. It is a remarkable fact, that 
 the greatest part of our ordinary cutlery is hardened by a process which, 
 although well known to be a very defective one, is persisted in from the force of 
 habit, or from an indisposition in the workman to make any changes in the cus- 
 tomary routine of executing work, in which the remunerating prices are very 
 low. We allude in particular to the practice (which, we are informed, is genera] 
 at Sheffield,) of hardening direct from the anvil ; that is, the articles are hard- 
 ened with the scale on the surface, which is produced by the act of forging. 
 The scale varies in thickness, according to the degree of heat the steel received 
 in forging; it is also a very bad conductor of heat, consequently the transition 
 from heat to cold (by which the effect of hardening is produced) is not so 
 sudden in one piece of steel as in another; and some are scarcely hardened at 
 all, owing to the temperature of the water having scarcely penetrated through 
 the scale. Hence, when such articles are afterwards tempered or " lowered," 
 there are not two alike in temper out of a great number ; a fact which can 
 hardly have escaped the observation of any man who has shaved for several 
 years. Instead, therefore, of the customary mode of hardening the blade 
 direct from the anvil, it has been recommended by an experienced manufac- 
 turer, that the blades be passed from the anvil to the grindstone. " A slight 
 application of the stone," he observes, " will remove the whole of the scale or 
 coating, and the razor will then be properly prepared to undergo the operation 
 of hardening with advantage. It will be easily ascertained that steel in this 
 state heats in the fire with great regularity, and that when immersed, the 
 obstacles being removed to the immediate action of the water on the body of the 
 steel, the latter becomes equally haid from one extremity to the other. To 
 this may be added, that as the lowest possible heat at which steel becomes hard 
 is indubitably the best, the mode here recommended will be found the only 
 one by which the process of hardening can be effected with a less portion than 
 is or can be required in any other way." 
 
 Considerable difficulty has been experienced in giving to articles about to be 
 hardened a perfectly uniform degree of heat in an ordinary fire ; and one of 
 the best means of obviating it is probably that which has been published by 
 Mr. Nicholson, of his adoption, and which he had for some time previous, for 
 justifiable reasons, kept secret : this was to employ a bath of melted lead, 
 heated to moderate redness, and well stirred ; into this the piece was plunged 
 for a few seconds, until, when brought near to the surface, that part did not 
 appear less luminous than the rest. The piece was then speedily stirred in the 
 bath, suddenly dra\yn out, and plunged into a large body of water. Instead of 
 employing simple water as the cooling medium, a variety of salts added to it 
 have been at different times recommended and boasted of. Not long ago, 
 mercury was cried up, and just now it is the fashion to extol a current of air, 
 grounded, we believe, on the report of travellers, that the sabres of Damascus 
 are hardened by cleaving the north wind with them. Although it is probable 
 that improvements in the present mode of hardening may be discovered, we 
 think it is improbable that they will be found in that fluid which is an inferior 
 conductor of heat, and that cannot be applied with equal uniformity to water. 
 
 A mode of tempering instruments of hardened steel was invented by 
 Mr. Hartley, in 1789, for which he obtained a patent ; and we have never yet 
 heard of a better. Mr. Hartley's plan was to immerse the articles in a bath of 
 oil, heated to a regulated temperature, and measured by a thermometer. This 
 was certainly a very great improvement, both in point of precision and dispatch, 
 on the common method of heating the instrument over a flame till a certain 
 colour, produced by a film of oxide, appears on its surface. These colours are 
 
 At 430 Fan. a very faint yellow, for lancets. 
 
 450 a pale straw colour, for razors, and surgeons' instruments, 
 470 a full yellow, for penknives.
 
 IRON. 
 
 795 
 
 At 490* Fahr. a brown colour, for scissors and chisels for catting old iron. 
 
 510 
 530 
 550 
 
 n, with purple 
 
 le, for table-knives and large shears. 
 
 spots, for axes and plane irons. 
 
 560 
 600 
 
 a brown, wit 
 
 a purple, f 
 
 a bright blue, for swords, watch springs, truss springs, and 
 bell springs. 
 
 a full blue, for small fine saws, daggers, &c. 
 
 a dark blue, verging on black, is the softest of all the gra- 
 dations, when the metal becomes fit only for hand and 
 pit-saws, which must be soft, that their teeth may bear 
 sharpening by the file, and bending or " setting." 
 
 If the steel be heated still further, it becomes perfectly soft. When tools having 
 a thick back and thin edge, like penknives, are to be tempered, they are some- 
 times placed with their backs in a plate of hot iron, or on hot sand ; otherwise 
 they would become too soft at their cutting edges before their backs would be 
 sufficiently heated. It is evident that baths of any of the soft metals, whose 
 fusible points are above those required for tempering, may be used instead of 
 oil ; and alloys of those metals might be so proportioned as to obtain points of 
 fusion at the exact degree of heat required. In these cases, however, to prevent 
 oxidation, it would be necessary to keep the fluid metal covered with grease, and 
 it would be advisable not to omit the use of a thermometer. Mr. Gill, in the 
 Technological Repository, has recommended several compositions for hardening 
 and tempering steel, to which work we must refer the reader for the formulae 
 and processes. We do not insert them here, because they are, for the most 
 part, apparently unsuited to operations on the great scale, although they are 
 certainly, in many respects, well deserving the attentipn of engineers. We shall, 
 however, avail ourselves of his instructions in the following article. 
 
 On restoring the Elasticity of hardened and tempered Steel Articles, " Saws, 
 sword-blades, clock and watch springs, &c., which, after being hardened and tem- 
 pered, require to be ground and polished,or otherwise brightened, lose their elas- 
 ticity or springiness by these operations, so as to appear soft on bending them, 
 although they are as hard as ever ; these qualities are again restored to them, 
 either by heating over a clear fire, made of cinders urged by bellows, or over 
 the flame of burning alcohol, or by inclosing them in a smouldering fire, made 
 of wood-ashes and embers, to a blue colour, which colour may either remain, 
 or be removed by the application of diluted muriatic acid wiped over them." 
 
 The partial Conversion of Iron into Steel t which is often the case in the blistered 
 bars, owing to the carbon not having penetrated to the middle, is usually 
 regarded as a great defect ; but an important advantage may be gained from 
 it in the steeling of edge-tools, which, Mr. Gill says, is adopted by Mr. Maudsley. 
 The bar is split down its middle into two parts, and these parts are sometimes 
 subdivided ; the internal parts which remain unconverted are then welded to 
 the iron of the tool, leaving the steel outside, to form the cutting edges of the 
 tool. 
 
 TABLE, Showing the Weight of Cast-iron Plates, twelve inches wide, and from 
 one-eighth of an inch to one inch thick. 
 
 FARTS OF AN INCH IN THICKNESS. 
 
 Width 
 in 
 Inches. 
 
 i 
 
 4 
 
 1 
 
 i 
 
 
 
 i 
 
 i 
 
 One Inch. 
 
 
 Ibs. oz. 
 
 Ibs. oz. 
 
 Ibs. oz. 
 
 Ibs. oz. 
 
 Ibs. oz. 
 
 Ibs. oz. 
 
 Ibs. oz. 
 
 Ibs. oz. 
 
 12 
 
 4 13f 
 
 9 lOg 
 
 14 8 
 
 19 5g 
 
 24 2| 
 
 29 
 
 33 13| 
 
 38 lOf
 
 796 IRON. 
 
 TABLE, Showing the Weight of one Foot Length of Malleable Ir&iu 
 
 SQUARE IRON. 
 
 ROUND IRON. 
 
 Sea tling. 
 Inches. 
 
 Weight. 
 
 Diameter. 
 
 Circ 
 
 umference. 1 
 
 Weight in 
 Pounds. 
 
 Pounds. 
 
 Inches. 
 
 Weight in 
 Pounds. 
 
 i 
 
 0.21 
 
 i 
 
 0.16 
 
 1 
 
 0.26 
 
 1 
 
 0.47 
 
 I 
 
 0.37 
 
 H 
 
 0.41 
 
 i 
 
 0.84 
 
 
 0.66 
 
 
 - 0.59 
 
 
 
 1.34 
 
 g 
 
 1.03 
 
 H 
 
 0.82 
 
 f 
 
 1.89 
 
 f 
 
 1.48 
 
 2 
 
 1.05 
 
 
 2.57 
 
 i 
 
 2.02 
 
 2i 
 
 1.34 
 
 1 
 
 3.36 
 
 1 
 
 2.63 
 
 2* 
 
 1.65 
 
 H 
 
 H 
 
 4.25 
 5.25 
 
 i! 
 
 3.33 
 4.12 
 
 91 
 
 3 
 
 2.01 
 2.37 
 
 f 
 
 6.35 
 
 
 4.98 
 
 3J 
 
 2.79 
 
 I 
 
 7.56 
 
 ji 
 
 5.93 
 
 3 
 
 3.24 
 
 I 
 
 8.87 
 
 ii 
 
 6.96 
 
 3| 
 
 3.69 
 
 t 
 
 10.29 
 
 if 
 
 8.08 
 
 4 
 
 4.23 
 
 
 11.81 
 
 if 
 
 9.27 
 
 4^ 
 
 5.35 
 
 2 
 
 13.44 
 
 2 
 
 10.55 
 
 5 
 
 6.61 
 
 2J 
 
 17.01 
 
 2j 
 
 13.35 
 
 5J 
 
 7.99 
 
 
 21.00 
 
 2J 
 
 16.48 
 
 6 
 
 9.51 
 
 2| 
 
 25 .41 
 
 2$ 
 
 19.95 
 
 6i | 11.18 
 
 3 
 
 30.24 
 
 3 
 
 23.73 
 
 7 
 
 12.96 
 
 i 31 
 
 41.16 
 
 Si 
 
 27.85 
 
 7i 
 
 14.78 
 
 4 
 
 53.76 
 
 3J 
 
 32.32 
 
 8 
 
 16.92 
 
 4 
 
 68.04 
 
 3 t 
 
 37.09 
 
 8| 
 
 19.21 
 
 5 
 
 84.00 
 
 4 
 
 42.21 
 
 9* 
 
 21.53 
 
 6 
 
 120.96 
 
 M 
 
 53.41 
 
 10 
 
 26.43 | 
 
 7 
 
 164.64 
 
 5 
 
 65.93 
 
 * U 
 
 
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