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 LIBRARY 
 
 UNIVERSITY OF CALIFOENTT 
 

 PREFACE 
 
 The nature and extent of this Work will be better understood by refe- 
 rence to its pages, than by any remarks which can be made in a Preface. 
 The following previously-circulated Address will, however, show the 
 object of the author in its preparation : — 
 
 " Those who are accustomed to attend philosophical lectures, or to 
 read scientific books, must be aware how much valuable information is 
 lost if they do not properly understand the scientific language, and know 
 somewhat of the construction of the instruments used in illustration. 
 The lecturer cannot stop at all times to explain these matters, and 
 there is no book sufficiently cheap, modem, condensed, and illustrated, 
 to communicate the information wanted ; thus the student necessarily 
 remains ignorant, though with the strongest tliirst for knowledge. The 
 general reader too, who may not desire to know the laws of natural 
 philosophy, yet may admire those of art ; machinery, architecture, or 
 painting, may employ his attention, and if he should be without a 
 director to explain the different parts, and the technical terms, here, as 
 in the former instance, much valuable time will he lost, and dissatis- 
 faction, often disgust, succeed. Even supposing a person care for none 
 of these things, yet his daily intercourse with the world will often 
 thrust upon his attention some portion of the scientific improvements 
 or discoveries which are yearly occurring, which the usual Dictionaries 
 take no cognizance of, and which the voluminous Encyclopaedias discuss 
 at a greater length than he desires, even should he possess one of 
 them — which, unless a rich man, probably he will not 
 
 " The attention of the author of this ' Dictionary of Arts and Sciences ' 
 has been directed to three objects. — The first, to explain briefly, but 
 plainly, all the terms used in architecture, civil engineering, practical 
 mechanics, manufacturing processes, the mathematics, the fine arts, and 
 the experimental sciences. The second, to give the origin, properties, and 
 application of all chemical substances ; and the third, to record and 
 describe all the apparatus and machines employed in natural philo- 
 sophy ; and also those numerous inventions and contrivances of a 
 mechanical nature, which our periodicals and galleries of art abound 
 with, but which are known comparatively to a very few persons, though 
 often of the most essential value to the community ; " illustrating each 
 article with wood-cuts, wherever such could in any way whatever lead 
 to the better understanding of the subject. 
 
 It will be readily believed, that the above has been a most difficult 
 task, involving care, patience, and assiduity, especially as the author 
 was his own draughtsman ; he trusts, however, that his readers will 
 give him the credit of carrying out, to the utmost of his power, the 
 original, and it is to be hoped, useful design. 
 
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 The first letter in all alpha- 
 bets, except that of the Abys- 
 sinian language. In English 
 it has four sounds, exempli- 
 fied in water, father, paper, 
 and fancy. Among the an- 
 cients it was a numeral ; in Greek 
 signifying 1 ; in Latin 500. With us 
 it often inlicates priority, as we say 
 ^ tchedule A. In algebra it is put for 
 ? some know i quantity. In numerous 
 compound scientific words, particularly 
 those derived from the Greek, it is used 
 s a negative, thus achromatic, without 
 color. A, in inscriptions and on coins, 
 is a contraction of Augustus, absolve, 
 argentum, annos, &c. In modem com- 
 merce it implies accepted and acre. 
 A in music is the sixth note of the 
 gamut ; in singing representing the 
 monosyllable la. It is the open note 
 of the second string of the violin, by 
 which its other strings are tuned and 
 i-egulated. A with a figure annexed, pre- 
 ceding a piece of music, indicates the number 
 of voices it is intended for, as A 2, for two 
 voices, &c. 
 
 Abaciscus. In ancient architecture one 
 of the tUes or compartments of an orna- 
 mental pavement. Not to be confounded 
 with the tesserce or cubical blocks used by 
 the ancients in tessellated pavements ; but. 
 
 more resembling the quarries of modem use, 
 and of which the following may convey an 
 idea. (See Quarry, Tessera, and Pavement,) 
 
 • 
 
 i 
 
 ••- -^--^^ 
 
 s 
 
 ® 
 
 
 • 
 
 >-^>-> 
 
 • 
 
 Abacus. The tablet or cap which covers 
 the top of a column. 
 
 The term, though of Greek origin, is equally 
 applied to the blocks, «rhether plain or 
 sculptured, which crown the capitals of an- 
 cient Indian and Egyptian buildings, although 
 often so different in shape from the Greek. 
 
AB 
 
 AB 
 
 In the Greek Doric order the abacus is square 
 and unornamented. In the Greek Ionic it 
 is thin, sqxiare, or rectangular, with an ovolo 
 moulding around it. In the Corinthian it 
 has hollowed sides, truncated angles, and 
 a rosette or other ornament in the centre of 
 each side. 
 
 m^^ 
 
 In the Roman Doric, the Tuscan, and Com- 
 posite, the abacus is shaped as follows, v£u-y- 
 ing in a very slight degree from the Greek 
 examples. 
 
 In Gothic architecture it is extremely varied. 
 In the Norman and Saxon styles the abacus 
 was mostly square, with the lower angle 
 chamfered off. In the early English build- 
 ings round abaci were common. In the 
 later and more ornamented styles, a variety 
 of angular forms were introduced. 
 
 Abacus. Among the Romans a counting 
 table. At first merely a tray sprinkled with 
 sand, upon which calculations were made. 
 Afterwards a frame with transvei-se wires, 
 upon which beads were strung, and which 
 from their position had a certain value as- 
 signed to them ; one wire denoting units, the 
 next tens, and so on. 1836 would be indi- 
 cated as follows : — 
 
 Abamurus. a buttress, or second wall 
 built to strengthen another. 
 
 Abartamen. An old name for lead. 
 lBatis, or Abbatis. Trees felled and laid 
 side by side, with their boughs outwards, ta 
 impede the progress of an enemy. 
 
 Abbrkviate Fractions. Compound 
 fractions, when reduced to simple ones^ are 
 thus called. 
 
 Abbreviation. The shortening of a word, 
 either for the sake of saving time and space, 
 as hhd. hogshead, or for secrecy. (See Con- 
 traction, Hieroglyphic, and Symbol. 
 
 Abbrevoir, (mt Abbreuvoir. The joint 
 between two of the stones of an arch, and 
 usually filled up with fine mortar. 
 
 Abb Wool. Among clothiers signifies the 
 warn or longitudinal fibres of a woven fabric. 
 
 AnEaRATiON is the wandering of any body 
 from the path in which it is expected to 
 move. In astronomy it is applied to light, 
 in its passage from one of the heavenly 
 bodies to another. For example, the appa- 
 rent place of a star differs from the true, 
 because light not being instantaneous in its 
 progress, the earth will have moved so far in 
 its orbit, while the particles of light which 
 renders the star visible is passing to the eye ; 
 and hence the telescope through which we 
 view the luminary must be directed forwards, 
 on a similar principle as the fowler points 
 his gun before the bird which he would shoot 
 in its flight. 
 
 Aberration, Spherical. Tlie intention 
 of spherical lenses, or of concave mirrors, is 
 that the rays of light should in the former 
 case be refracted, and in the latter reflected, 
 so as to converge, and meet in a single point, 
 or focus. In practice, the rays are generally 
 found to deviate from that point, and this 
 deviation is called the spherical aberration 
 of the lens or mirror. These aberrations 
 arise from two causes — from the form of 
 curvature of the lens or of the reflector, and 
 from the different refrangibility of the rays 
 of light. 
 
 Ablactation. That kind of grafting trees 
 in which the scion or graft is not separated 
 from the old stock till fully incorporated with 
 the new. 
 
 Abrasion. Wearing away by friction ; 
 also the crumbling of earth by frost. 
 
 Abraxas Stones. A name applied to a 
 variety of gems that exhibit enigmatical com- 
 positions, strange words in foreign characters, 
 &c. They were so called, because the more 
 ancient of them, and which often represented 
 the human body, with the head of a cock and 
 the feet of a reptile, have the Greek word, 
 abraxas, engraved upon them. Such stones 
 are supposed to have been amulets or talis- 
 mahs. 
 
 Abridging. In algebra the reducing a 
 compound equation or quantity to a more 
 simple form of expression. 
 
 Abscissa. (See Hyperbola.) 
 
 Absolute. Independent of any thing else j 
 unconditional. 
 
 Absolute Equation. (See Equation.) 
 
 Absolute Number. In algebra that term 
 in an equation which is completely known, 
 and which is equal to all the other terms taken 
 together. In the equation a; + 4 y + 2 = 30. 
 The 30 is the absolute number. 
 
 Absorbed. In painting is when the oil is 
 so soaked in, that the colors appear dead 
 or flattened. Synonymous with chilled or 
 sucked in. 
 
 Absorbent. Sucking up, or imbibing. 
 Thus alumine is an absorbent earth ; flint is 
 not so ; sulphuric acid is a liquid rapidly 
 absorbent of water ; potassium absorbent of 
 
AB 
 
 AC 
 
 oxygen, &c. In painting, picture grounds 
 are thus called when they have the power of 
 absorbing the oil, &c., so much that the co- 
 lors shall dry quickly ; such as distemper 
 grounds. 
 
 Absorbing Cascade. An instrument 
 invented by Mr. Clement, for the more per- 
 fect absorption of aeriform fluids by water. 
 
 A is a cylindrical vessel, filled with glass 
 beads, and water trickles into it from the re- 
 servoir E, through the cock G. In descending 
 between the glass it meets with the gas 
 coming from C, through B, becomes thereby 
 charged with gas, and nms away for use 
 through D into any vessel put to receive it. 
 F is a safety valve. Mr. Clement calculates 
 the absorbent power of this apparatus to be 
 more than 300 times greater than the usual 
 machines : it has been used chiefly for the ab- 
 sorption of chlorine. A similar apparatus, 
 called the productive cascade, has also been 
 contrived by Mr. Clement, in which gases 
 may be formed : for example, fill A with 
 oxyde of manganese, in large pieces. C 
 partly with sulphuric acid and salt. Let 
 water trickle through A, and apply heat to C, 
 when the manganese and salt will be decom- 
 posed, and chlorine pass off" through a pipe 
 near the top of A. 
 
 Absorption. The act of sucking up. Dry 
 earth absorbs moisture, so do the spongioles 
 of roots, and various membranes of the ani- 
 mal body ; water absorbs certain gasts, iScc. 
 Absorptions of the Earth. A term used 
 by Kircher and others, for the sinking in of 
 large tracts of land by subterraneous com- 
 motion, and many other circumstances. 
 
 Abstract Sciences, Ideas, Numbers, 
 &c. Those which are independent of others, 
 and are not to be altered by time or cir- 
 cums :«iice ; — thus algebra, geometry, arith- 
 metic, riuzions, &c., are abstract or cure 
 
 mathematics, considered in themselves ; but 
 when applied to the explanation of natural 
 laws, or physical facts, they cease to be 
 abstract and become mixed. The number 3 
 is abstract when not connected with a noun, 
 but in union with an object, as 3 books, 3 
 pages, it is no longer abstract. 
 
 Absurd. A method of mathematically 
 proving a proposition, by showing that it 
 cannot be otherwise than stated ; so that 
 even to suppose it different would be absurd. 
 Abundant Number, is that the aliquot 
 parts of which, when added together, are 
 more than the number itself; thus 12 is an 
 abundant number, because 1, 2, 3, 4, 6, its 
 aliquot parts make 16. 
 
 Abutment, or Butment. The solid sup- 
 ports at the end of a bridge or arch, also 
 synonymous with buttress. In carpentry, 
 the joint when timbers are framed at right 
 angles one with the other. In engineering, it 
 is any part from which a moving power 
 arises, or against which it stops ; thus the ends 
 of the cyUnder of a steam-engine, where the 
 motion of the piston rod begins and stops, 
 are its abutments. 
 
 Abutment Arches. The two end arches 
 of a bridge. 
 
 Acacia. Something resembling a bag or 
 roll, often found on the medals of the Greek 
 and Roman emperors. 
 
 Acacia Gum. The same as gum arable, 
 which is produced from different species oi 
 the acacia tree. 
 
 Academy Figure. A drawing in light 
 and shade, made after a living model, regu- 
 lated by the rules and orders of an academy. 
 Acanthus. In architecture, an ornament 
 which resembles the leaves of a plant so 
 called. It is used in the capitals of the 
 Corinthian and Composite orders, and is 
 said to have been introduced into the former 
 by Callimachus, an Athenian architect, who 
 was struck with the beauty of the leaves 
 surrounding a basket, which, covered with a 
 tile, had been left so near the plant that the 
 leaves had grown over it. 
 
AC 
 
 AC 
 
 The preceding cut shows the plant in its 
 growing state ; the following represents the 
 front and side views of the leaf as an archi 
 tectural ornament. 
 
 Acceleration. An increase in the ra- 
 pidity of a moving body. 
 
 Acceleration, of a Star. Owing to the 
 motion of the earth in its orbit, the stars 
 come to the meridian 3' 56'' of time earlier 
 each succeeding day, which is their accelera- 
 tion. 
 
 Acceleration, of a Planet, is when its 
 real diurnal motion exceeds its mean diurnal 
 motion ; this arises from the greater rapidity 
 of the planet's motion in one part of its 
 orbit to that in the other. 
 
 Acceleration, of the Moon. An in- 
 creased mean motion of the moon, as 
 compared with the diurnal motion of the 
 earth, now and at former distant times ; the 
 cause of this is unknown, and the extent of 
 it about 9" in a century. 
 
 Accelerated Motion. A rapidity of 
 motion constantly increasing, like that of a 
 stone falling from an eminence. The velocity 
 of a falling body increases each second in the 
 arithmetical ratio of 1,3, 5, 7, &c., and the 
 whole space passed over in the geometrical 
 ratio of squares, 1, 4, 9, 16, &c. Thus a 
 stone falling passes over 16 feet in the first 
 second ; 3 times 16 in the second; 5 times 16 
 in the third ; while the distance it has fallen 
 altogether is 16 feet the first second ; 4 times 
 this altogether at the end of the second ; 
 9 times 16 at the end of the third ; and so on. 
 Accelerated Force. The increased 
 force which a body exerts in consequence of 
 its increased motion ; better to say, accu- 
 mulated force. 
 
 Accesses. External passages or corridors. 
 
 Accessory. Something added to the 
 
 principal design, as the subordinate parts and 
 
 objects in a picture, the embellishments of 
 
 sculptured architecture, &c. 
 
 Accidental. Such parts of a picture or 
 sculpture as are not necessarily present or 
 non-essential. 
 
 Accidental Colors. If we look intently 
 with one eye upon any colored spot, as, for 
 example, a wafer placed upon a sheet of white 
 paper, and immediately afterwards turn the 
 same eye to another part of the paper, we 
 
 shall see a similar spot, but of a different 
 color. Thus if the wafer be red, the seeming 
 spot will be green ; if purple, the spot will 
 be orange ; and so on for other colors. The 
 corresponding spots are accidental colors or 
 ocular spectra. 
 
 Accidental Lights, in a Picture^ are 
 such as arise from casual circumstances. 
 
 Accidental Point. In perspective is 
 the point in wrhich a right line drawn from 
 the eye, parallel to another right line, cuts 
 the picture, as in the following : F is the 
 accidental point. E F being parallel to A B. 
 
 Acclimatise. To accustom animals and 
 plants to a climate new to them. 
 
 Accordion. A musical instrument ; tlie 
 sound of which is produced by the vibration 
 of metallic springs, occasioned by a current 
 of air rushing from a bellows, where it is 
 accumulated, through valves attached to the 
 notes, and which are opened by the fingers of 
 the musician. 
 
 Accompaniment. Any music played or 
 sung for the purpose of increasing the effect 
 of the principal melody. 
 
 Ace RATE. A salt formed with aceric acid 
 and an alkaline or other base. 
 
 Acerbity. A sour roughness of taste, 
 such as that of unripe fruit. 
 
 Aceric Acid. Discovered by Scheren in 
 the juice of the maple, in the state of acerate 
 of lime. 
 
 Acescent. Substances are so called which 
 spontaneously enter into the acetous fermen- 
 tation, as beer, wine, over-ripe fruit, &c. 
 
 Acetates. Neutral salts, composed of 
 acetic acid, and an alkali or metal. The 
 acetates are, with the exception of two or 
 three, soluble in water, decomposed by heat, 
 and by sulphuric acid ; and often, when in 
 solution, by exposure to the air. The chief 
 acetates used in the arts are those of man- 
 ganese, iron, copper, lead, and alumine. 
 
 Acetate of Manganese is prepared for the 
 use of calico printers by mixing sulphate of 
 manganese with acetate of lime. It forms 
 transparent, pale red rhomboidal tiibles, so- 
 luble in water and alcohol. 
 
AC 
 
 AC 
 
 Acetate ofPeroaeyde of Iron, may be ob- 
 tained by digesting turnings and clippings of 
 iron in acetic acid, or by mixing acetate of 
 lead with sulphate of iron. It forms a deep 
 reddish brown solution, not capable of crystal- 
 lization. It is used by dyers and calico printers. 
 
 Acetate of Copper^ or Crystallized Ver- 
 digris. Dissolve common verdigris in acetic 
 acid, and evaporate till a pellicle forms on 
 the surface of the solution ; and set aside to 
 crystallize. 
 
 Di-acetate of Copper^ or Common Ver- 
 digris^ is prepared by exposing sheets of 
 copper to the action of acetic acid, or its 
 fumes. In France it is made by the acid 
 produced by the fermentation of grape stalks, 
 husks, &c. 
 
 Acetate of Lead, Sugar of Lead, is 
 much used as a drier by the painter, and in 
 various operations connected with dyeing and 
 calico printing. It is made by exposing 
 plates of lead to the fumes of vinegar, or 
 pyroligneous acid. The white powder thus 
 produced is dissolved in excess of acid, and 
 crystallized. It may also be made from li- 
 tharge, or from the carbonate of lead^ (the 
 common white lead,) by dissolving either of 
 them in acetic acid. 
 
 Acetate of Alumine. So extensively used 
 by dyers and calico printers as a mordant 
 for a great variety of colors. About 3 lbs. 
 of alum are dissolved in 8 gallons of water, 
 and li ft. of sugar of lead stirred in it. A 
 copious formation of sulphate of lead sub- 
 sides, and the clear liquid is a solution of 
 the acetate of alumina. 
 
 Acetic Acid. The acid which exists in 
 vinegar. It is the result of the acetous fer- 
 mentation, and may be procured from most 
 animal and vegetable products, as fruit, su- 
 gar, milk, &c., whether such materials may 
 have been subjected to the vinous fermen- 
 tation or not ; thus we say, sour wine, sour 
 beer, sour milk, &c., the acidity of which 
 arises from the presence of this acid. It 
 may also be procured by the distillation of 
 green wood, called then Wood Vinegar, or 
 Pyroligneous Acid, (which see.) 
 
 Acetometer. An instrument for ascer- 
 taining the strength or specific gravity of 
 acids. It consists of a globe of about 3 inches 
 diameter, having a little ball beneath, and a 
 graduated stem above ; the upper part of 
 the stem being furnished with a cup to hold 
 the requisite weights. It differs in no respects 
 from the hydrometer, except in the material 
 of which it is made, and in the method of 
 graduation. 
 
 Acetone. A new name for pyro-acetic 
 spirit. A combustible, colorless, strong 
 smelling, acrid liquid, procured by the dou- 
 ble distillation of the acetates. It is used as 
 a cheap solvent for the gums and resins re- 
 quired in hat-making. 
 
 Acetous. Like, or belonging to vinegar. 
 
 Achard's Pyrometer consists of a ball 
 and tube of semi-transparent porcelain, highly 
 baked, containing a fusible alloy of 2 parts 
 bismuth, 1 of lead, and 1 of tin. In the tem- 
 perature of the air this remains solid in the 
 tube ; but becomes fluid about the boiling 
 point of water ; then as a fluid expands by 
 increase of temperature ; and its expansion 
 being seen through the translucent tube, 
 which is divided into equal parts or degrees, 
 it becomes an indication of the temperature 
 applied to the ball. 
 
 Achelar or Ashlar. Hewn stone used 
 for the facings of walls. 
 
 Achromatic. Without color. Those op- 
 tical instruments and lenses which suffer the 
 rays of light to pass through them, without 
 decomposition, are called achromatic. White 
 light consists of rays of various colors, red, 
 blue, and yellow ; these rays are of dif- 
 ferent degrees of refrangibility, and when 
 light passes through common glasses, thick 
 and imperfect single lenses, and all such 
 media as do not make proper allowance for 
 these differences, it becomes decomposed, 
 and instead of remaining white is seen in its 
 different colors, if to be viewed at a distance, 
 as in a camera obscura, solar microscope, 
 &c. ; or if seen through, or at the axis, it is 
 ill defined and nebulous. It may be under- 
 stood by the following diagram : — Suppose 
 A A to represent rays of light coming from 
 
 a distant object. Striking the lens B, each 
 ray becomes divided into its three colors. 
 The red will reach the axis at R ; the violet 
 at V ; and the yellow at Y, instead of at the 
 same point. The ray of light C, being 
 nearer the centre of the lens, will be re- 
 fracted differently — the red ray reaching to r, 
 and the violet to v. At this part of the 
 axis, therefore, there will be a confusion of 
 tints, and if the red and blue rays be con- 
 tinued beyond the axis, as on to a screen, 
 they will appear upon it in their proper 
 colors. 
 
 Achromatic Eye Piece. An arrange- 
 ment of lenses made so as to correct the 
 chromatic and spherical aberration ; that is, 
 to cause the rays of light to be so refracted as 
 to meet in one exact point. This is pro- 
 duced by a combination of lenses, such as 
 the following. It may be understood by the 
 next diagram, that the red part of the ray of 
 light, A B, will meet the axis in R, and the 
 violet in V, provided there were no other lens ; 
 
AC 
 
 AC 
 
 but this interposing, the red ray is refracted 
 to C, and so is the violet ray, mxd thus the 
 
 effect of the one lens is to counteract the 
 chromatism of the other. 
 
 AcHUOMATiSM OF THE Eye. The powcr 
 which the eye has of viewing objects with 
 distinctness, and therefore without decom- 
 posing light into its component rays — an 
 effect which in artificial optical instruments 
 is produced by a series of lenses. 
 
 AcicuLAR. Needle-shaped. Many leaves, 
 and also the crystals of some of the salts and 
 minerals are of this form. 
 
 Acids. An extensive class of chemical 
 substances ; the properties of which are to 
 combine in certain proportions with the al- 
 kalies in solution, and with most of the me- 
 tallic oxydes, forming by such union neutral 
 salts. They redden vegetable blue colors, 
 and have mostly a sour taste. Some are de- 
 rived from minerals, others from vegetables, 
 and others from animals. Acids arise in 
 nearly all instances from the union of their 
 base with oxygen ; the greater or less relative 
 proportion of which regulates the pecuhar 
 properties of the acid. Such as are of the 
 least degree of oxidation ; that is, such as 
 have but a small proportion of oxygen, end 
 in ous. Those containing a large quantity 
 end in ic — as sulphurous and sulphuric, both 
 consist of sulphur and oxygen ; but the 
 sulphurous acid, with the same quantity of 
 sulphur, contains 2 proportions of oxygen, 
 sulphuric 3 proportions. A diminution 
 of oxygen in either case forms a hypo-acid, 
 as hypo-sulphurous acid consists of 2 parts 
 sulphur and 2 oxygen ; hypo-sulphuric acid 
 of 2 parts sulphur and 5 oxygen. A few 
 acids derive their acid properties from chlo- 
 rine, and not from oxygen ; as muriatic, or as 
 it is now called, hydro-cliloricacid. There are 
 not above 20 acids used in the arts, though 
 more than 220 are described in " Brande's 
 Chemistry." The whole will be found under 
 their respective names. 
 
 Acids, Artificial. Acids are so called 
 when, formed by the mixture of other acids. 
 Tims, nitro-chloric acid is formed by mixing 
 together the nitric and chloric acids. They 
 are mostly a union of nitric acid with some 
 vegetable principle, and formed by boiling 
 that principle or ingredient in strong nitric 
 acid. (See Carbazoiic Acid, which is of 
 this kind.) 
 
 Acids, Fatty. Such acids as are formed 
 by reducing an oleaginous or fatty body to 
 soap, by means of alkali ; then adding alcohol 
 
 a neutral salt is separated, composed of the 
 alkali used, and the fatty acid. Of this na- 
 ture, and thus formed, are the stearic, mar- 
 garic, oleic, phocenic, buturic acids, &c. 
 
 AciDiFi ABLE. Capable of being converted 
 into an acid. Such substances are called 
 radicals, or bases. 
 
 AciDULE. A name given by the French 
 chemists to such salts as have an excess of 
 acid ; such as supertartrate of potass. 
 
 AciDUM ^REUM. An old name for car- 
 bonic acid ga^. 
 
 AcoNiTA. A poisonous alkaloid, extracted 
 from the aconitum napellus, or monk's-hood. 
 Acoustics. That branch of natural phi- 
 losophy which treats of the nature of sound, 
 and the laws of its production and propa- 
 gation. It, therefore, explains the cause of 
 echoes, the reverberations of thunder, and 
 of artillery, the tone and mode of action of 
 musical instruments, the theory of har- 
 monics, &c. 
 
 Acre. A measure of land^ containing 4 
 square roods, or 160 perches. The English 
 acre of land contains 4,840 square yards; 
 the Scotch acre is nearly a quarter more; 
 the Irish acre more than half more; the 
 Welch nearly twice the English ; the number 
 of acres of land in England are 46,080,000. 
 
 AcROGRAPHY. The art of producing j 
 blocks in relief for the purpose of printing I 
 from along with type, and thus to supersede f 
 wood engraving. The method is at present \ 
 kept a secret by the inventor, Mr. Schonberg, \ 
 of Hatton Garden. 
 
 AcRONic AL. Said of a star or planet when 
 opposite the sun ; that is, which rises when 
 the sun sets, and sets when the sun rises. 
 
 Acrostic A poem of which the first, and 
 sometimes the last, letters form a word or 
 sentence. 
 
 Acroterions. The small pedestals upon 
 the ends or summit of a pediment, as well 
 as the statues which they sometimes support. 
 
 Also, the pinnacles, buttresses, or other di- 
 visions between the compartments of bal- 
 lustrading, along the attics of a building, &c. 
 
 Acropolis. The fortress or citadel of 
 Athens, which derived its name from standing 
 on an eminence. 
 
 AcROSPiRE. The plumule ; that is, the 
 first root that a seed makes when germi- 
 nating. In the process of malting an acro- 
 spire is seen on every grain of barley after 
 steeping in the cistern. 
 
AD 
 
 AD 
 
 Acting Point. That part of a machine 
 to which the power is first applied ; as the 
 acting point of a hand-mill is the winch by 
 which it is turned ; of a wind-mill, the sails 
 are the acting points ; of a steam-engine, 
 the piston of the steam cylinder. 
 
 Action and Reaction. Action is the 
 motion which one body produces or endea- 
 vours to produce in another ; and reaction 
 the resistance offered by the second body. 
 Action is therefore synonymous with force, 
 tmd reaction with resistance. 
 
 Action, Chemical, The effect produced 
 by one body on another, so that one or both 
 of them are altered in their properties by 
 the union or disunion. Thus an acid and an 
 alkali have a chemical action upon each other, 
 because they unite and form a salt, which is 
 neither acid nor alkaline. 
 
 Action, Electrical, Galvanic, and Mag- 
 netic. The power exerted by the electrical or 
 magnetic fluid of any body when put in cir- 
 culation, over the electrical or magnetic fluid 
 of any other body, near or in contact with it. 
 
 Action, Mechanical. The effect of bodies 
 over each other's motion, such bodies re- 
 maining unaltered by their respective ap- 
 proach or union. Tlius one ball striking 
 another is a mechanical action ; so is also a 
 horse drawing a cart, &c. A cannon acquires 
 its propelling power by the chemical action 
 of fire and gunpowder producing suddenly a 
 quantity of gas. The mechanical action or 
 force of this drives out the ball, and the me- 
 chanical action of the air stops its flight, 
 while the power of gravitation, which is also 
 a mechanical action, brings it to the ground. 
 
 Action, Mutual. "VMien two or more bo- 
 dies conduce to occasion the same effect. 
 
 Active Force. (See Force.) 
 
 Acuminate. Lengthened out so as to end 
 in a point, as a pinnacle, a leaf, a spindle, &c. 
 
 Acute Angle. (See Angle.) 
 
 Adagio, in Music. A slow time, gene- 
 rally applied to music which is to be played 
 with grace and embellishment. 
 
 Adapter. A glass tube open at both ends, 
 used to connect a retort with its receiver 
 when the neck of the former is not long 
 enough. 
 
 Addition. The adding or blending one 
 thing to another. A rule in arithmetic, 
 whereby the sum of two or more numbers 
 is found. 
 
 Additional Keys. Those keys of a 
 piano -forte which lie either above or below 
 the former compass of the instrument. These 
 are generally four or six notes above F m alt, 
 and three notes below double F. 
 
 Adhesion is the union of the surfaces of 
 
 bodies together, and is measured by the force 
 which is requisite to separate them again. 
 Adhesion may be either natural or artificial. 
 It is not to be confounded with cohesion, or 
 the power by which the particles of bodies 
 unite with each other, forming a solid mass ; 
 nor yet with gravitation, which is merely the 
 weight of one body upon another ; nor yet 
 the pressure of the atmosphere upon an ex- 
 ternal surface, when the air is removed from 
 beneath it, as is seen in the Magdeburg 
 hemispheres, and in the school-boy's leathern 
 sucker, but is rather an attraction or adhe- 
 sion between different bodies. Thus mc 
 speak of the adhesion of clay to our feet, 
 the adhesion of wax, oil, or paint, to our 
 clothes, the adhesion of pieces of wood, glued 
 or nailed together, &c. &c. The power or 
 degree of strength with which bodies unite 
 is called their force of adhesion. Mr. Bevan 
 found that if a nail driven into Christiana 
 deal reqtured 170 lbs. to extract it, in green 
 sycamore it required 312 lbs., in dry oak 
 507 lbs., in dry beech 667 li)s. A screw 
 holds three times as strongly as a nail of 
 similar length ; and in most light timbers a 
 nail driven across the grain holds with twice 
 the force of one driven with the grain. In 
 oak and elm there is not so much difference. 
 Well-glued surfaces of dry ash holds with a 
 force of 715 lbs. <^ square inch, if the glue 
 be new. Scotch fir 562 lbs. on the inch. 
 
 Adhesive Slate. A soft, massive, yel- 
 lowish grey slate, which splits easily, and 
 adheres to the tongue, whence its name. It 
 is found near Paris in the gypsum beds. 
 
 Adipocere. a fatty, or rather soap-like 
 substance, generated by dead bodies whai 
 buried in stagnant or in running water. In 
 1786-7, 1500 bodies, which were com- 
 pletely changed into this substance, were dug 
 out of the cemeteiy of the Innocents, when 
 it was found that adipocere was well adapted 
 for the use of the candle tnaker and the soap 
 boiler. It is white, hard, without scent, 
 somewhat resembles wax, and burns with a 
 clear bright flame. 
 
 Adit. The entrance to a mine, if horizon- 
 tal, and leading direct from the neighbouring 
 county; vertical entrances to mines are shafts. 
 Aditum. The whole interior of the an- 
 cient temples were so called, now it is applied 
 only to the more sacred parts. 
 
 Adjective Colors. Such as in dyeing 
 will unite with the material to be dyed without 
 a mordant. 
 
 Adjutage. The butting or resting of one 
 thing against another. (See Ajutage.) 
 Adopter. (See Adapter.) 
 Adulteration. The debasement of any 
 article of produce or manufacture, by the 
 introduction of inferior materials. 
 
 Adze. A cutting tool, used by different 
 artizans. 
 
MO 
 
 M. Many words, formerly beginning with 
 this diphthong, bemg now spelt with E only, 
 will be found under that letter. 
 
 ^GiNETiAN Marbles. A collection of 
 seventeen statues, obtained from the temple 
 of Jupiter Ponhellenicus, at ^gina, one of 
 the most beautiful remains of Doric archi- 
 tecture. They were purchased by the kmg 
 of Bavaria, in 1812, and the deficient parts 
 afterwards restored by Thorwaldson. They 
 are now exhibited in Munich, and are re- 
 markable for their exact imitation of nature. 
 This, indeed, is as strong a characteristic of 
 the ^ginetan style, as ideal grace is to the 
 Attic of the time of Phidias. 
 
 ^LLOPODES. The name given by its m- 
 ventor to a pedomotic carriage, which was 
 for some time exhibited in London, in 1839. 
 
 iEoLEAN Harp. A stringed instrument, 
 played by a current of wind issumg through 
 a crevice or hole. It consists of a thin 
 wooden box, with a hole at the top, and 10, 
 12,« or 14 cat-gut strings across it ; the 2 
 outer ones of which are like the fourth 
 string of the violin— all the rest like the first 
 string. It is usually adapted in length to 
 fit a window, the lower sash of which is to 
 be lifted up sufficient only for its insertion. 
 It may be 6 inches wide, and 2^ deep ; the 
 strings must be tuned so as to be in unison 
 with each other ; they are supported at each 
 end by a bridge. 
 
 iEoLEAN Harp, Meteorologicah An in- 
 strument invented by JVI. Ventail, of Basle, 
 which emits sounds during changes of weu- 
 ther. It consists of 15 iron wires, of dif- 
 ferent sizes, and 320 feet long each, stretched 
 across a garden. It is said by the discoverer, 
 that the sounds emitted are so loud that a 
 concert could not be heard in the house, and 
 that they resemble sometimes the hissing of 
 water when about to boil ; at other times 
 the sound of an harmonicon, a chime, or an 
 organ. The wires were inclined 20 or 30^^ 
 with the horizon, and due north and south — 
 not sounding in any other direction. 
 
 -^OLiPiLB. A hall or vessel in which water 
 can be converted into steam, and which al- 
 lowing the steam to escape by two opposite 
 orifices, by pipes connected with it, commu- 
 nicates motion to the ball. It was invented 
 by Hero, and is the origin of that mighty 
 instrument, the steam engine. 
 
 A is a cauldron in which water is heated. 
 The steam ascends through B and C into the 
 ball D, escaping by the orifices E E ; of 
 course the ball must be supported in such a 
 manner upon the pipes C D as to have 
 
 MO 
 
 freedom of motion around them, as an axis, 
 yet that this part shall be steam tight. 
 
 A philosophical toy is made under this 
 name : it consists of a small ball of metal, with 
 an exceedingly narrow tube and orifice — this 
 ball is filled with spirits of wine. It is made 
 to boil rapidly by a spirit lamp held beneath 
 it. The steam of tlie spirit will of course 
 rush out, sometimes to the distance of 2 or 
 3 feet, and this being set fire to produces a- 
 long and beautiful jet of fire. (See Fire 
 Cloud.) 
 
 A ball of this description is sometimes 
 mounted on four wheels, which bear also the 
 spirit lamp. If the ball be filled with water, 
 and this made to boil, the steam will, if di- 
 rected into the air at the back of the car- 
 riage, by its counter -action, impel the whole 
 along the table, forming the first and sim- 
 plest steam loco-motive carriage. 
 
 An instrument similar to the above, but on 
 a large scale, is used occasionally as a bel- 
 lows, to increase the draught of a steam- 
 engine furnace ; also the alcoholic blow-pipe 
 is upon a similar construction. 
 
 iEoLOPHON. A musical instrument, re- 
 sembling a piano-fprte in appearance, the 
 
iER 
 
 AE 
 
 sound of vrhicli arises from the vibration of 
 metallic springs, as in the seraphine. 
 
 JEpinus's Method of making Magnets 
 will be understood by the following diagram. 
 
 A B are two bars of steel which are to be 
 magnetized. They are joined together at the 
 ends by two hard steel already-made mag- 
 nets C and D. Then two strong magnets 
 E F are to be held one in each hand, at an 
 obtuse angle with each other, and their lower 
 ends placed on one of the steel bars — such 
 ends being separated by a small piece of 
 wood G. Then without separating E and F 
 they are to be drawn backwards and forwards 
 along the steel bars several times, when it 
 wUl become magnetic. When the bar on 
 one side is done, the other bar is to be mag- 
 netized in the same manner. It is said, that 
 this method is best adapted to magnetise 
 long and large bars, such as those used for 
 batteries. 
 
 ^IDoLus. A small portable machine, in- 
 vented by Mr. Field, for refreshing and 
 changing the air of rooms, commonly called 
 a ventilator, and fixed into a window instead 
 of a pane of glass — its turning round pro- 
 ducing the current of air required. 
 
 iEuATED Waters. Water impregnated 
 with carbonic or some other gas. Water of 
 this kind is commonly sold as soda water, 
 though improperly so called. Many mineral 
 springs are impregnated by different gases, 
 that at Harrogate contains sulphuretted hy- 
 drogen. Water may be made to absorb 
 numerous gases by the following, which from 
 its inventor is called Nooth's apparatus. 
 
 A D E are three glass vessels fitting into 
 each other. The ingredients to make the 
 gas are put by B into A. The gas passes 
 the finely-perforated tube C into water pre- 
 viously placed in D. After a time it may be 
 drawn off by the cock F. 
 
 The following apparatus is better adapted 
 to aerate water, when large quantities are to 
 be operated upon at once. A is a vessel 
 from which chlorine, carbonic acid, or other 
 gas is issuing. It passes to B, which is a 
 bag loaded with a weight. C a cock, com- 
 municating from B to the cask D, which is 
 half filled with water. The cock is so 
 
 connected with C, as to allow the former 
 to turn on its axis, without the joint be- 
 coming leaky ; in order that it may be turned 
 round by the handle occasionally throughout 
 the process, to occasion the water to absorb 
 a greater portion of gas ; finally, the con- 
 tents are drawn off at F, and a fresh supply 
 poured in at the hole at the top of the bar- 
 rel, which has a band and staple to keep it 
 properly fixed. The absorbing cascade is 
 also an excellent apparatus for the same pur- 
 pose. (This see, as well as Soda Water 
 Fountain.) 
 
 Aeration. Exposmg soil to the air. 
 
 Aerial Acid. An old name for carbonic 
 acid gas. 
 
 Aerial Electrometer. De Luc when 
 he had discovered the electrical instrument 
 which bears his name, {De LucPh Dry Pile, 
 which see,) observed, that its effects were 
 much influenced by the state of the atmos- 
 phere ; and therefore proposed it as an in- 
 strument to indicate aerial electrical changes, 
 under the name of the aerial electrometer. 
 The instrument has, however, never been 
 thus applied. 
 
 Aerial Perspective is that which re- 
 presents in pictures the weakening of tint in 
 objects distant from the eye, whether rela- 
 tive to distance alone, or to the interposition 
 of mist, clouds, &c. 
 
 Aeriform BoDiESor Aeriform Fluids. 
 Gaseous or resembling air. 
 
 Aerodynamics. A branch of mathema- 
 tical philosophy, which treats of the powers 
 and motions of elastic fluids, particularly the 
 air. (See Pneumatics.) 
 
 Aerography, Aerology, or Aero- 
 METRY. Synonymous with pneumatics. 
 o 
 
AE 
 
 AF 
 
 Aerolites. Stones which fall from the 
 atmosphere, called also meteorites or me- 
 teoric stones. They consist of iron with a 
 small admixture of nickel. Their origin is 
 not known ; some persons suppose that they 
 are cast from volcanoes in the moon, and 
 coming within the influence of our attrac- 
 tion descend to the earth's surface. 
 
 Aerometer. An instrument to ascertain 
 the bulk of gases. A graduated tube fur- 
 nished with a ball has a certain number of 
 inches of gas passed into it. This is in- 
 verted in another tube, containing water or 
 mercury of a certain degree of heat, and 
 which raising the inclosed gas to the same 
 degree, shows by its contraction or expan- 
 sion the positive quantity of gas operated 
 upon. 
 
 Aeronautics. Aerostation. The art 
 of sailing through the air, as in a vessel at 
 sea. The ancients speak of several aero- 
 nautic machines and automata, such as a 
 flying pigeon made by Archytas, Medea's 
 dragons, Juno's peacocks. &c ; and also have 
 some accounts of persons flying by means 
 of wings attached to their shoulders. These 
 are probably all fabulous ; at any rate we 
 are now enabled to navigate the air only by 
 the aid of balloons, and even by these only 
 to be driven where the wind may impel the 
 machine. To the formation and manage- 
 ment of balloons therefore the term is solely 
 applied. (See Balloon.) 
 
 -^RUGO. Oxyde of copper ; also, ver- 
 digris. 
 
 ^scuLiNE. An alkaloid, lately discovered 
 by M. Curzoneri in the bark of the horse 
 chesnut. It is of no known use. 
 
 -(Esthetics. The science of sensations, 
 or that which explains the cause of mental 
 pain or pleasure, as derived from a contem- 
 plation of the works of nature and art. 
 
 JEther. a thin, subtle fluid, supposed 
 to fill all space beyond the limit of our at- 
 mosphere. Its existence is purely hypo- 
 thetical, yet was maintained by most of the 
 ancient philosophers, and by many of the 
 moderns, among whom was Sir Isaac Newton. 
 Some imagine it to be identical with the 
 electric fluid. (See Ether.) 
 
 ^THRioscoPE is an instrument invented 
 by Professor Leslie, on the principle of the 
 differential thermometer, to indicate cold 
 pulsations of the air, and which Dr. Brewster 
 says is so delicate, that the liquor in the stem 
 rises and falls with every passing cloud. 
 The annexed cut. (No. 1,) is a represen- 
 tation of the original instrument. The cut, 
 (No. 2,) is a simplification of it as proposed 
 by Dr. Brewster. No. I consists of a metallic 
 cup, of the shape given, and made of thin 
 brass or sUver, polished on the inside, and 
 from 2 to 4 inches diameter. In the focus of 
 this is placed one of the balls of a differen- 
 
 tial thermometer, the diameter of which hall 
 is equal to one-third that of the cup. The 
 other ball is bent so as to be as much as pos- 
 sible out of the way, that it may not be sub- 
 ject to a like influence, a lid of metal is put 
 over the cup, and only removed when an 
 experiment is to be made. The scale may 
 extend 60 or 70° above zero, and about 15° 
 blow it. 
 
 Fig. 2 is the same, as to the cup, cover, 
 and sentient ball, but the tube is straight, 
 and the second ball is inclosed in the foot of 
 it. When used, the instrument is to be 
 placed a few feet above the earth, that it 
 may not be effected by terrestrial radiation. 
 It may also be remarked, that this instrument 
 would be of much more general application, 
 if it were fixed upon an axis, or had a joint 
 near the foot, that it might be directed to 
 any particular part of the heavens, and not 
 confined to a perpendicular impulse, as at 
 present. 
 
 ^TiTES. Eagle stones. A name given to 
 certain round nodules of oxyde, or sulphuret 
 of iron, which, being hollow and containing 
 some concretions or detached particles, rat- 
 tle upon being shaken. 
 
 ^THiops Mineral. Mercury triturated 
 with sulphur till it assumes a black color. 
 
 ^TNA Salt. An impure sal ammoniac, 
 found in the interstices of Mount iEtna and 
 other volcanoes. 
 
 Affected EauATioN. In algebra one in 
 which the unknown quantities rise to two or 
 more powers, as A'^ + a?y + 3/2. Also, some- 
 times used to signify those quantities which 
 have co-efficients, as 2a or 3.a?. 
 
 Affinity. A tendency of two bodies to 
 unite chemically with each other, as an acid 
 and an alkali unite and form a neutral salt, 
 because they have an affinity for each other. 
 Oil and water do not unite because they have 
 no affinity. 
 
AI 
 
 AI 
 
 Affinity, Elective, is where one body is 
 formed by the decomposition of another. 
 For example, dissolve some camphor in spi- 
 rits of wine, they will unite ; but add water 
 the spirits of wine will let fall the camphor 
 in a white powder, because it has a stronger 
 or an elective affinity for the water. 
 
 Affinity, Compound, or Double Elective, 
 is when two compounds are decomposed to 
 form two others of a different nature. Thus, 
 mix together a solution of bi- carbonate of 
 potass, (pearl-ash,) and sulphate of iron, 
 (green vitriol,) double decomposition will 
 take place. Carbonate of iron will fall down, 
 and the sulphate of potass be held in solution. 
 Affirmative, or Positive Sign. The 
 sign of addition + . 
 
 After. In imitation of, as a person paints 
 a picture in imitition of, or after Raphael, 
 Corregio, &c. 
 
 After Grass. After Math. A second 
 crop or mowing of grass. 
 
 Agaric Mineral, or Mountain Meal. 
 A light porous carbonate of lime, which 
 lately has been found to consist wholly of the 
 exttvise of fossil animalcules. It is abundant 
 in Tuscany, and often there made into bricks, 
 with the admixture of a certain portion of 
 clay, which are, when baked, so light as to 
 float in water. 
 
 Agate. A silicious stone, of various co- 
 lors, used for brooches, seals, snuff boxes, 
 knife handles, &c. The following are vari- 
 ties : — Ribbon agate, brecciated agate, for- 
 tification agate, mocha stone, moss agate, 
 and oriental agate. Some specimens are of 
 exquisite beauty and of a large size. 
 Age, in Chronology, 100 years* 
 Age, of the Moon, Tue time elapsed since 
 the last new moon. 
 
 Agedoite. The same as asparagin. 
 Agent. Any active cause, or power ; as 
 steam is said to be a powerful agent of motion. 
 Aggregated. When the parts of a mi- 
 neral, or other body, are collected together 
 in such a manner that they may be separated 
 from each other by mechanical means. Gra- 
 liite is an aggregated rocJc, so is sandstone, 
 pudding stone, &c. 
 
 Agriculture. The art and science of 
 cultivating the earth, so as to preserve and 
 increase the natural fertility of the soil, either 
 as applicable to the growth of food, timber, 
 materials for manufactures, or the rearing 
 and feeding of cattle. 
 
 Agricultural Implements. {Siee Har- 
 row, Plough, and others, according to their 
 names.) 
 
 AiGREMORE. A name given to charcoal 
 when in a state fit to be mixed with the other 
 materials in the making of gunpowder. 
 
 Aiguille. An auger, adapted for boring 
 through stone, used in blasting rocks with 
 gunpowder 
 
 Aileron. Synonymous with starling. 
 
 Air. The general term of the atmosphere, 
 which see. 
 
 Air, Inflammable. (See Hydrogen.) 
 
 Air, Dephlogisiicated. (See Oxygen.) 
 
 Air, Vital. (See Oxygen.) 
 
 Air, Fixed. Carbonic acid gas. 
 
 Air, Phlogisticated. Nitrogen. 
 
 Air, Mephitie. Nitrogen. 
 
 Air Balloon. A balloon, the buoyancy 
 of which is produced by being filled with 
 hydrogen gas, as those of common use, in 
 distinction to a fire balloon. (See Balloon.) 
 
 Air Beds, Cushions, &c. Bags of re- 
 quisite size, formed of air-tight cloth, and 
 inflated, when required for use, either by the 
 lungs, or by a pair of bellows. They are 
 light, soft or hard, according as they are 
 more or less inflated, are without the ener- 
 vating effect of a feather bed, and require no 
 making. 
 
 Air Chamber. Any vacuity in machi- 
 nery, stoves, &c., where air is contained. 
 
 Air Drain. An aperture through which 
 cold air is descending. 
 
 Air Escape. A simple and ingenious 
 contrivance for letting off the air from water 
 pipes. When these are laid upon rising 
 ground, the air will often collect in the 
 higher part, and obstruct the progress of the 
 water. To remedy this inconvenience, the 
 air escape is used. A hollow ball is attached 
 to the upper part of the pipe, in which a ball 
 cock is placed, adjusted in such a way, that 
 when any air collects in the pipes, it will 
 ascend in the vessel, and by displacing the 
 water, cause the ball to descend, and thus 
 open the cock and allow the air to escape. 
 No water, however, can follow it, for when 
 that fluid rises to a certain height, the ball 
 rises and shuts the cock. 
 
 A is the pipe through which the wate:i 
 enters. B the cock, whence the pent sir 
 issues. C the ball cock, when the air is i.; 
 abundance in the ball. D the ball cock^ 
 when the air has been let off". E the pipe W 
 carry off the water. 
 
 Air Flue. A tube in which heated air fi 
 made to pass rapidly from a stove, in ordek 
 to warm distant apartments, &?. 
 
 Air Gun. An instrument from which the 
 bullet is projected by condensed air, instead 
 
AI 
 
 of gunpowder. A resembles a common fowl- 
 ing piece, with stock, barrel, ram-rod, lock, 
 and trigger. B is a valve, opening upwards 
 when the hammer of the lock falls, and com- 
 municating to the end of the barrel. C is a 
 copper ball, in which the air is to be com- 
 pressed by a condensing syringe, (which see.) 
 To use it, charge the barrel with a ball, fasten 
 on the ball C, and pull the trigger, when a 
 quantity of the air escaping from C, and 
 expanding instantaneously in the barrel, 
 drives forward the ball to a distance of 80 
 or 100 yards, and almost without noise. 
 
 Air Pipes. Pipes used to ventilate a ship's 
 hold. A pipe extends from below to the 
 ship's stove ; here becoming heated the air 
 within it is rarefied, and passes upwards, and 
 thus it continually draws away the con- 
 taminated air round the lower end of it. 
 
 AiB PistoIm or Cannon, Electrical. 
 Consists of a tube of brass, in the end or 
 side of which a glass or ivory tube is inserted, 
 with a bent wire passing through the tube, 
 so that when a spark is taken on the wire 
 from an electrical machine, the fluid may 
 pass in a spark from the point of the wire 
 which is within the tube, if, therefore, it be 
 filled with hydrogen, and corked up, a spark 
 will inflame the hydrogen, and an explosion 
 ensue. 
 
 A shows the brass tube, or cliamber. At 
 the end a glass tube is situated, and now 
 supposed to be covered with a cap B, which 
 screws on at C. The cap being removed, 
 the structure is seen in the figure below. C 
 is the screw, one end of which screws to the 
 brass chamber, the other holds the cap. D 
 is the glass tube. E the bent wire. F the 
 ball to receive the spark from the machine. 
 At G the place of its passage from the point of 
 the wire to the outside case, and when it 
 
 AI 
 
 inflames the gas. The figure below is A 
 simple form of the instrument. The elec- 
 trical cannon is of the same nature ; but of 
 a different shape, as its name indicates. 
 
 Am Pump. An instrument to exhaust the 
 air from, or condense it in, close vessels. It 
 is the principal machine employed to illustrate 
 the science of pneumatics. The following, 
 which is the single-barrelled air pump, is the 
 simplest form of the instrument. Fig. 1, 
 shows its outward appearance — fig. 2, the 
 same in section. 
 
 It consists of a syringe, connected with a 
 tube, upon the other end of which is screwed 
 a well-ground brass plate, upon which rests 
 the receiver. Drawing up the handle A of 
 the syringe, the valve at B, which opens 
 upwards, is closed, and a vacuum being pro- 
 duced under it, the valve C is opened, and 
 the air from the receiver D passes into the 
 syringe ; by pressing down the handle of the 
 syringe, the lower valve is closed and the 
 upper one opens ; thus air equal to the size 
 of the piston is got rid of. Thus by the 
 alternate action, the air from the receiver is 
 gradually exhausted. 
 
 The following cut shows the usual form of 
 the double-barrelled air pump. The valves 
 are as in the former instance, and the handle 
 being worked to and fro moves a wheel, 
 and with that the two racks up and down 
 alternately. 
 
 Fastening the receiver down by a strap 
 across it, and reversing the valves, will 
 cause the air to be condensed. (See Air 
 Gun.) The air pump is not merely a philo- 
 sophical insti'ument, but has lately been 
 employed in many mechanical processes. 
 One is attached to the low pressure stear* 
 engine to draw off the air extricated from the 
 boiling water. Mr. Howard, by drawing the 
 air from the sugar pans, allowed the liquid 
 sugar to boil at a much less heat than is 
 usually applied to it i and upon the same pria- 
 
AI 
 
 AI 
 
 dple very superior medicinal extracts are now 
 made ; it ixas also been applied to distilla- 
 tion with success. Tanning is found to 
 succeed more rapidly and surely in exhausted 
 vessels. Filtering is also materially assisted ; 
 stereotype and other metal casting is, by 
 exhausting the air from the moulds, con- 
 ducted with much greater certainty, and as if 
 to complete the catalogue of uses of the air 
 pump, a pneumatic railway and other vacuum 
 engines have been lately constructed. (See 
 Hi c hie.) 
 
 Air Pyrometer. A somewhat clumsy 
 and expensive instrument, proposed by M. 
 Schmidt, of Jasy, in Moldavia. Its con- 
 struction is as follows : — A is a bottle of 
 platinum. B a tube of the same metal. A is 
 immersed in the heated substance to be ex- 
 amined. B conveys the expanded air from 
 A into an air-tight cistern C, which iS filled 
 with water. D is a thermometer to ascertain 
 the temperature of the water before the ex- 
 periment. E an open tube, dipping in the 
 water. The heat of the substance around A 
 is indicated by the great or less expansion 
 of the water, and its ascent into E. 
 
 Air Stove. An inclosed fire-place, so 
 constructed as to admit a stream of air to 
 pass round it, or through it ; and this im- 
 pinging upon heated surfaces is rarefied, 
 carried upwards, and warms the apartment. 
 There are numberless modifications of this 
 principle, but they all may be reduced to 
 two. First, such as admit the air to play 
 against metal^ wbicb is heated by a direct 
 
 fire. The second pass the stream of air 
 through a cylinder of steam. The following 
 cut represents one of the first kind, seen 
 both in elevation and in detail. 
 
 A is a square cast-iron box, closed at top, 
 and open only at the bars at bottom, to let 
 out the ashes, and let in the stream of air that 
 keeps up the combustion. Opening also in 
 front with a door to supply fuel, and having 
 a pipe C as a chimney. B is a cast-iron 
 case, entirely surrounding A. There is a 
 drawer below to catch the ashes. The air 
 enters at bottom between the two cases ; it 
 passes upwards, touching the outside of A, 
 and thereby becoming heated, escapes through 
 the top E, where is a register to regulate the 
 draught of air required to heat the apart- 
 ment, as there is also In the front of D 
 to regulate that appertaining to the fire. 
 If it be required to warm an apartment dis - 
 tant from that in which the stove is placed, 
 a pipe is affixed to the top of the stove, in- 
 stead of the register, and this pipe carried 
 to the required situation. 
 
 Air Shafts. In mines holes left for the 
 foul air to escape, and fresh air to enter. 
 
 Air Thermometer. A thermometer 
 which indicates changes of temperature by 
 air contained in a bulb and tube. The fol- 
 lowing, called the differential air thermome- 
 ter, is its most useful form. A A are two 
 bulbs, connected by a glass tube, and sup- 
 ported by a foot. The tube contains a small 
 quantity of colored sulphuric acid ; when one 
 of the balls is heated, it drives the liquid 
 towards the other, and the degree of this 
 repulsion is indicated on a scale, and the 
 different temperature of the two bulbs in- 
 stantly seen. 
 
AI 
 
 AL 
 
 Air Thermometer, Electrical. (See 
 Kinnersley.) 
 
 Air Tight. That degree of closeness in 
 any vessel or tube, which prevents the pas- 
 sage of air at its usual pressure. 
 
 Air Trap. A contrivance for excluding 
 the effluvia from drains, &c. — a water joint is 
 best .adapted for this purpose. 
 
 A is a pipe connected with the drain below, 
 and soldered by the cup B (which has a metal 
 cup attached to it,) with the sink hole above. 
 Over the top of A is inverted a cup E, the 
 edge of which extends to nearly the bottom 
 of B. The holes down which the water runs 
 are all outside of the sides of the cup. 
 When water runs down, it fills the space 
 between A and B, until it passes over the 
 top of the inner pipe, and runs away, while 
 the water joint prevents the return of any 
 smell from beneath. 
 
 Air Valve. A valve belonging to steam 
 boilers, the intention of which is to supply 
 air to the boiler, if, by a sudden cooling of 
 the water, letting off the steam, or other 
 cause, the boiler should have a vacuum 
 formed within it, in which case the atmos- 
 pheric pressure from without, might, and 
 occasionally does, press together the sides of 
 the boiler. This contrivance is very simple, 
 and resembles in appearance and mode of 
 action the common lever safety valve, except 
 
 that it is the air which opens it by pressure 
 from without, and not steam by pressure 
 from within. A A A is part of the top of 
 the boiler. F a plug valve, opening down- 
 wards. C a counterpoise weight, to keep it 
 in its place under ordinary circumstances. 
 The lever D is supported upon the fulcrum 
 E, and the weight C is capable of being 
 removed to any required distance from that 
 fulcrum. The valve, therefore, may be made 
 so as to adapt itseK to any degree of pres- 
 sure from without that may be deemed safe, 
 not exceeding 15 lbs. per square inch, the 
 amovmt of atmospheric weight. 
 
 Air Vessel. A vessel forming part of a 
 forcmg pump, fire engine, or other similar 
 hydrauhc machine, intended by the elasticity 
 of the compressed air within it, to keep up 
 
 stream of water while the action of the 
 
 pump is making the return stroke. (See 
 Force Pump.) 
 
 Airy. Paintings, or other works of art, 
 which are light and lively. 
 
 Aisle, or Aile. The lateral divisions of a 
 church. 
 
 Ajutage. The tube or mouth from which 
 water is discharged to or from water wheels, 
 and other hydraulic engines. 
 
 Ala. The wing of a building, side pas- 
 sage, &c. 
 
 Alabaster is of two kinds — one a sul- 
 phate of lime, or gypsum. The other a carbo- 
 nate of lime, analogous to marble, but softer 
 in texture. The oriental alabaster, which 
 is of this kind, is the most valuable, and of 
 extremely varied and beautiful colors. It is 
 used chiefly for the manufacture of bell han- 
 dles, time-piece cases, &c. The Italian ala- 
 baster is also of various colors, but that 
 which is pure white, and of silky marble- 
 like appearance, is preferred. It is cut into 
 innumerable ornaments, and small pieces of 
 statuary, for the decoration of houses, &c. 
 
 A-la-Grec. a particular kind of fret or-* 
 nament, called often the Grecian border. 
 
 Alarm, or Alarum. Any self-acting in- 
 strument adapted to give notice to a person 
 of some occurence happening, such as fire, 
 thieves, time of night, &c. ; thus the striking 
 part of a clock is an alarum, so is the rail- 
 road whistle ; but a bell, or other musical 
 instrument, is not, because sounded by 
 direct human agency. Alarums are endless 
 in form and materials. The following is one 
 invented by Mr. Russell, as a preservative 
 against fire. 
 
 A Bis a pulse glass, partly filled with a 
 liquid, suspended upon its centre, and in- 
 closed by wood, except the ball A. If a 
 fire occurs, the air in the top of A expands, 
 drives the liquid into the bulb B, this 
 becoming heavier, overbalances the other 
 bulb, and brings down the lever C, which 
 is hollow, and has in it some buUets, these 
 running down the tube, give the fall of the 
 lever sufficient impetus to ring a bell or fire 
 a pistol. 
 
 Albumen. A peculiar chemical substance, 
 found pure in the white of eggs, which are 
 wholly composed of it ; mixed with water it 
 
AL 
 
 AL 
 
 is called glaire, and used as a varnish for 
 the leather cover of books, kid shoes, &c. , 
 being merely put on with a small piece of 
 sponge. Glaire and quick lime form a 
 cement for joining china, glass, &c. 
 
 Album Gr^cum. The white dung of 
 dogs, sometimes used to soften leather in 
 dressing. It consists of digested animal 
 natter, and phosphate of lime. 
 
 Alburnous. Composed of alburnum. 
 
 Alburnum. Sapwood, that is, the outer 
 rim or growth of wood in a tree, which 
 has not yet attained its strength, or solidity. 
 It is often of a lighter color than the heart- 
 wood, as is seen very conspicuously in the 
 lignum vitce, where the real wood is nearly 
 black, and the alburnum white. 
 
 Alchemy. The science of chemistry, as it 
 was applied in former times to the attempted 
 transmutation of the bas3r metals into gold ; 
 the discovery of an elixir vitse, or universal 
 medicine ; a universal solvent ; and other 
 visionary substances. The first of these ob- 
 jects, was the principal one aimed at, and this I 
 by a powder, called the powder of projec- 
 tion, or philosopher's stone, which, mixed 
 with any metal, and assisted by fire, was to 
 change that metal into gold. The endeavour 
 to discover tliis powder occupied the atten- 
 tion, exhausted the fortunes, and destroyed 
 the health of hundreds of enthusiasts, during 
 the middle ages, especially from the period of 
 our King Edward I. to that of Charles II., 
 and even after this period. 
 
 Alcohol. The purely spirituous part of 
 liquors which have passed through the vinous 
 fermentation, such as wine, beer, &c. These 
 being distilled, an impure spirit passes from 
 them, called low wines. This, again dis- 
 tilled, becomes purer and stronger, called 
 then raw spirit, or whiskey. Deprived of its 
 flavor, by a third distillation, it is rectified 
 spirit. A fourth operation makes it spirit 
 of wine. To separate from this the pure 
 alcohol, it is saturated with hot pearl-ash, 
 which seizes upon the remaining water, and 
 leaves the spirit pure, or very nearly so. 
 Also, a bladder being partly filled with spirits 
 of wine, and put in a dry warm place, loses 
 in quantity, but gains in strength, until the 
 spirit parts with almost all its water by eva- 
 poration, and becomes nearly pure alcohol. 
 (See Distillation.) 
 
 Alcoholates. Alchoates. Compounds 
 produced by dissolving by heat various sa- 
 line bodies in pure alcohol, when cold crys- 
 tals are deposited, which appear distinct, 
 definite substances. Distilled tinctures are 
 also often so called. 
 
 Alcolized Sulphuric Acid, or Eau 
 DE Rabel. The same as sulphuric ether. 
 
 Alcohol of Sulphur. The bi-sul- 
 phuret of carbon. 
 A1.COHOLIC, or Spirit Blow-fipe. A 
 
 blow-pipe which acts by the inflammation 
 of a stream of the vapor of spirits of wine, 
 as will be seen by the following cut : — 
 
 A is a vessel in which alcohol is kept 
 boiling by the lamp beneath. The vapor 
 issues from the point of the tube, and passing 
 through the burning wick is inflamed, and 
 forms a powerful jet of fire. 
 
 Alcoholic Thermometers. Such as 
 are filled with alcohol. 
 
 Alcohometer. (See Hydrometei\) 
 
 Alcoranes. High slender turrets ad- 
 joining to mosques. The same as minaret. 
 
 Alcove. A recess or place adapted for 
 repose, usually separated from the rest of a 
 room by pilasters, and a screen, or a curtain. 
 Summer houses in gardens are often so called, 
 particularly if imbedded in trees. 
 
 Aldeide. a name given by M. Liebeg to 
 pure alcohol, obtained by distilling alco- 
 hol over anhydrous sulphuric acid. He 
 imagines it to be a new substance. 
 
 Alembic Synonymous with still. 
 
 Alembroth, Salt of. A compound of bi- 
 chloride of mercury and sal ammoniac, used 
 by the alchemists to make a white precipitate, 
 which Ure says consists of ammonia, mu- 
 riatic acid, and mercury. 
 
 Algaroth, Powder of. A compound of 
 oxyde and chloride of antimony. 
 
 Algebra. The science of calculating by 
 means of symbols and letters, instead of by 
 figures. By this science we are enabled to 
 calculate the most difficult mathematical 
 problems, which arithmetic cannot reach ; 
 and also of expressing by a very few marks, 
 what would otherwise require a lengthened 
 explanation, and even that would be far less 
 clear than an algebraic formula. This science 
 is of very ancient date, havmg been known 
 1500 years ago, and probably long before. 
 
 Algorithm. An old word for algebra. 
 
 Alhambra. The royal palace of the kings 
 of Grenada. 
 
 ALiauANT Part. A number that will no^ 
 divide another number exactly, or without 
 remainder ; thus 7 is an aliquant part of 20 
 because 20 divided by 7 leaves the re- 
 mainder 6. 
 
AI 
 
 AL 
 
 AtiauoT Part. Such a part of a num- 
 ber as will divide exactly, without any re- 
 mainder: thus 7 is an aliquot part of 21, 
 because it is contained in it exactly 3 times. 
 
 Alizarine. A vegetable principle, ex- 
 tracted from the red coloring matter of the 
 madder plant, by subliming the precipitate 
 which water throws down from its alcoholic 
 solution. It sublimes in extremely beautiful 
 needle-shaped crystals, varying from a crim- 
 son red to a reddish yellow, or even a dirty 
 white color. 
 
 Alkahest. The pretended universal sol- 
 vent of the alchemists. 
 
 Alkalescent. Becoming spontaneously 
 of alkaline properties, particularly vegetables 
 of the cruciform or cabbage tribes ; the evo- 
 lution of ammonia occasions the peculiar 
 scent when these are decomposing. 
 
 Alkali. Chemical substances, acrid and 
 caustic, which form soap with fat and oil, 
 dissolve animal matter, combine with acids in 
 definite proportions, forming neutral salts. 
 They combine with water in any quantity, 
 precipitate most metals from their acid solu- 
 tions, and change most vegetable blue colors 
 into green, and the yellow to brown. The 
 chief alkalies are potass, soda, and ammonia. 
 The two former are called fixed alkalies, the 
 last the volatile alkali. Some of the earths 
 are also alkaline, and also numerous vegetable 
 principles. (See Alkaloid and Earth.) 
 
 Alkali, PhlogistiCated or Prussian. An 
 old name by which the prussiates of the al- 
 kalies were once known. 
 
 Alkalimeteu. An instrument to ascer- 
 tain the strength of an alkali. It consists of 
 a graduated tube, into which a certain quan- 
 tity of dilute sulphuric acid, of a known 
 strength, is poured. The quantity of the 
 alkali under examination found necessary to 
 neutralize the acid will indicate its relative 
 strength. 
 
 Alkalixe Earths. Such earths as unite 
 and form neutral salts with the acids. They 
 are lime, magnesia, alumina, lithia, baryta, 
 and strontia. 
 
 Alkaloid. Any vegetable principle which 
 has alkaline properties. The alkaloids are 
 much used in medicine, but not in the arts. 
 The chief are morphia, quinine, strychine, 
 brucine, veratrine, conine, atropine, del- 
 phine, emetine, and numerous others. The 
 general method of procuring them is to 
 make a solution of the vegetable, concen- 
 trate this a little by boil ing, add ammonia till 
 it is a little in excess— a precipitate will fall 
 down ; digest this in proof spirit to take 
 away the coloring matter. Then the pre- 
 cipitate left is dissolved in boiling alcohol as 
 Btrong as possible to be procured, and set 
 aside to crystallize. The alkaloids are chiefly 
 made in France, because of the expense of 
 alcohol in this country. 
 
 Alkanet. The name of a plant, the root 
 of which is used in staining wax, lip and 
 other salves, perfumed oils, mahogany and 
 marble. Its color is contained chiefly in the 
 bark, is of a reddish brovm, and is easily 
 extracted by spirits of wine, and by oils, wax, 
 and other unctuous substances. The roots 
 are chiefly imported from France, where the 
 best is produced. 
 
 Allegation. An arithmetical formula for 
 ascertaining the proper proportion- of ingre- 
 dients in a mechanical mixture, in proportion 
 to its value. 
 
 Alliaceous. Having the smell of garlic, 
 as the arsenical minerals submitted to a cer- 
 tain degree of heat. 
 
 Allodial. Independent of any superior. 
 
 Alloy. A combination of two or more 
 metals ; also used to indicate any inferior 
 metal, which may be mixed with gold and 
 silver. If mercuiy be one of the com- 
 bining metals, the mixture is an amalgam, 
 not an alloy. The chief alloys are bras 
 tombec, pinchbeck, prince's metal, bell 
 metal, type metal, gun metal, solders, fusi- 
 ble alloys, &c. &c., which see under their 
 respective names. 
 
 Algetic Acid. A name given by M. 
 Liebeg to the bitter principle of aloes, pro-* 
 cured by means of nitric acid — spec. grav. 
 1.25. It precipitates the salts of baryta, 
 lead, and protoxide of iron, of a purple 
 color, and forms a purple salt with potass. 
 It is the same as carbazotic acid. 
 
 Alluvion, or Alluvian Lands, or 
 Alluvial Formation. That which is 
 washed to the shore by inundations, or de- 
 posited in valleys by mountain torrents, &c. 
 Gravel, loam, clay, sand, brown coal, bog 
 iron ore, wood, coal, &c., are of this kind. 
 
 Almacantar's Staff. An ancient in- 
 strument for finding the amplitude of the 
 sun, &c. 
 
 Almery. a niche or cupboard let into 
 the substance of a wall, synonymous with 
 locker. In Gothic buildings it was usually 
 situated on the side of the altar, and used to 
 preserve the vessels and instruments used in 
 the communion service. 
 
 Almond. The kernel of the fruit of the 
 amygdalus communis and amygdalus amara, 
 or sweet and bitter almond tree. In medi- 
 cine, triturated with water, almonds form an 
 emulsion. The bland oil extracted from 
 them by pressure is valuable in the arts, 
 particularly for the use of the perfumer, 
 while the chemist extracts by boiling and 
 distillation the prussic or hydrocyanic acid. 
 
 Altar. An elevated place in which sacri- 
 fices are offered up to the Deity. Among 
 rude nations it is a pile of hewn wood ; in 
 the earlier ages of Christianity was a wooden 
 table. After the year 509 altars were chiefly 
 of stone. Sometimes but one altar was iu 
 
AL 
 
 AM 
 
 the edifice or place ; but in the Catholic 
 churches, besides this, many more to diffe- 
 rent saints are erected. In England, the 
 stone altars were ordered to be removed 
 soon after the accession of Elizabeth. 
 
 Ali'Ar Screen. The partition behind the 
 high or chief altar. They are often most 
 magnificently sculptured and fretted. 
 
 Alth^in. The same as asparagin. 
 
 Altimetry. The art of measuring heights. 
 
 Altitude. Height. The altitude of the 
 celestial bodies is reckoned in degrees, from 
 the horizon upwards towards the zenith. 
 It may be the apparent or the true altitude, 
 according as we reckon it from the sensible 
 horizon, or that which bounds our sight ; or 
 from the rational horizon, that which passes 
 through the centre of the earth. Terrestrial 
 altitudes may be calculated by trigonometry, 
 the observation of shadows, and by the ba- 
 rometer. Celestial altitudes by the sextant, 
 quadrant, &c. The altitude of a solid is 
 the perpendicular height of its apex, above 
 the base; of a tree, house, &c., its height 
 above the ground ; of a mountain, its height 
 above the level of the sea. Altitude in per- 
 spective is the height of the eye above the 
 horizontal ground line of the picture. 
 
 Altitude, Quadrant of. A thin, flexible 
 strip of brass, moveable at one end, around 
 a joint in the lower part of a square head, 
 which is furnished with a tangent screw. Its 
 use is, that when fastened on to the brazen 
 meridian of an artificial globe, it shall indi- 
 cate the relative position of places, and 
 other purposes, connected with that part of 
 geography, commonly called the use of the 
 globes. The strip of brass is graduated from 
 zero to 90°, and the size of the instrument 
 must be accordant to the size of the globe 
 with which it is to be used. 
 
 Alto Fagotta, or Octave Fagotta. 
 A musical instrument, combining the strength 
 of the horn with the sweetness of the cla- 
 rionet. It is made of brass, like the former, 
 and played with a reed, like the latter in- 
 strument. The compass is 3 octaves, com- 
 mencing with C in the second space, bass clef. 
 
 ^'ote — There are 3 holes and keys in the side 
 opjiosito to that delineated, marked by 3 black dots. 
 
 Alto Relief. Sculptured works, stand- 
 ing out from the sreneral flat surface. 
 
 Aludel. a receiver for the products of 
 sublimation. They may be of any shape, 
 or formed of any material ; generally, how- 
 ever, they are of earthenware. The word 
 is now seldom used. 
 
 Alum. A triple salt, consisting of alumina, 
 potass, and sulphuric acid ; chiefly an arti^ 
 ficial product, made from the alum slate 
 found in Yorkshire, and other places. One 
 hundred and thirty tons of the slate pro- 
 duce about one ton of the salt. Alum is 
 extensively used in dyeing, as a mordant ; 
 also, to imbue the paper in which gunpowder 
 is wrapped to prevent accidental combustion, 
 and resist better the moisture of the at- 
 mosphere. It is used also in tanning, fining 
 liquids, bread making, and other processes. 
 
 Alumina. An earth which forms the chief 
 constituent in clayey or argillaceous soil. It 
 is white, tasteless, insoluble in water, solu- 
 ble in acids, and caustic alkalies ; has a 
 powerful affinity for grease, and contracts 
 equably by heat. (See Pyrometer.) The 
 abundance of alumina in pipe clay, common 
 clay, and fuller's earth, render these earths 
 so valuable in the arts. The sapphire and 
 ruby are pure alumina. 
 
 Aluminates. Many of the earthy com- 
 binations of alumina are thus called. 
 
 Aluminum. The metallic base of alum. 
 
 Amadou. German tinder, is made from 
 the spongy fungus, called boletus igniarius,by 
 boiling it, beating afterwards with a mallet, 
 and soaking in a solution of saltpetre. When 
 now dried it forms an excellent tinder. The 
 black amadou is the above rubbed over with 
 meal-powder while wet. 
 
 Amalgam. A combination of mercury 
 with any other metal, usually made by the aid 
 of heat. The following are the most useful 
 amalgams : — 
 
 Amalgam, Electrical. Melt 1^ drams of 
 zinc, and add 4 drams of mercury — after- 
 wards pound up with a little tallow. 
 
 Amalgam for Silvering Glass Globes. 
 Melt 1 part of tin, 1 of lead, 1 of bismuth, 
 and 2 of mercury. When nearly cold, pour 
 into the globe, and turn it about. 
 
 Amalgam for a Metallic Varnish. Melt 
 
 1 part of tin, 1 of bismuth, and 1 of mer- 
 cury. When cold, mix with the white of an 
 
 egg. 
 
 Amalgam of Gold. Heat until it fumes, 
 
 2 ounces of mercury, then add one ounce of 
 gold, (or silver.) Used for water gilding. 
 
 Amalgamation. The art of combining 
 mercury with other metal ; a process exten- 
 sively employed in the purification of gold 
 and silver. 
 
 Amanitine. The poisonous principle of 
 some fungi. 
 
 Amber. A hard, brittle, semi-transparent 
 
 substance ; found plentifully in some parts 
 
 I of Poland, Italy, and on the shores of th« 
 
AM 
 
 AM 
 
 Baltic. It is combustible, and becomes 
 electrical by friction. Is used chiefly by the 
 varnish maker. 
 
 Ambergrease. Ambergris. A solid, 
 opaque, fatty substance, found on the sea 
 shores, and supposed to be produced by the 
 sperm whale. It is used in perfumery. 
 
 Ambitus. An inclosure, applied to the 
 space inclosed by the railings around a tomb, 
 or to a burying place generally. 
 
 Ambo. Any raised platform, particularly 
 applied to the raised part of a church which 
 surrounds the altar. The reading desk was 
 formerly called ambo. 
 
 Ambreic Acid is procured by digesting 
 ambreine in nitric acid. 
 
 Ambreine. The base of ambergris. 
 
 Ambulatory. A place to walk in, such 
 as the cloisters of a monasteiy. An avenue 
 of trees. 
 
 Amethyst. A gem of a violet, yellow, or 
 deep purple color^ X^^^ latter is the most 
 valuable,) of great brilliancy and hardness; 
 brought, the commoner sorts, from Ger- 
 many ; the best from Asia. 
 
 Amianthus. A fine kind of asbestos, 
 (which see.) 
 
 Amianthus Cloth, or Incombustible 
 Cloth, is made as follows : — Expose amian- 
 thtis to steam, separate the fibres with the 
 hand, spin and weave it along with one-third 
 the quantity of flax, or cotton ; and after- 
 wards throw it into the fire to bum the cotton 
 away. The cloth will be found well formed, 
 and uninjured by the fire. It has been used 
 as an enveloping dress for those who have to 
 enter burning houses, or to inclose substances 
 which are to be burnt, and yet the ashes of 
 them to be retained. 
 
 Amicable Numbers. Pairs of numbers 
 of which each of them is equal to the sum 
 of all the aliquot parts of the other ; thus, 
 220 and 284 are amicable. Of 220, the 
 aliquots are 1, 2, 4, 5, 10, 11, 20, 22, 44, 
 55, 110 = 284. Of 284, the aliquots are, 
 1, 2, 4, 71, 142 = 220. The other pairs of 
 amicable numbers are 6232 and 6368 — 
 17296 and 18416—9363584 and 9437056. 
 Amician Microscope, or Engiscope. 
 This instrument is constructed upon the re- 
 flecting principle, varying but little from that 
 of the reflecting telescope of Sir I. Newton. 
 The eye glasses, mode of illuminating ob- 
 jects, stage, stand, &c., differ in no respect 
 from those in common use. It is the re- 
 flection of the rays of light from the object 
 that constitutes the perfection of the instru- 
 ment. The construction will be understood 
 by the following diagram, observing that the 
 body of the instrument is horizontal, and 
 object glasses vertical. 
 
 A is the object, supposed to be lighted by 
 a candle and reflector or by any other method. 
 Tlie rays of light from it pass upwards, 
 
 through the object glass or glasses, to the 
 plane mirror B. Thence they are reflected 
 to the concave mirror C, and from this 
 along the tube to a focus D, and afterwards 
 pass onwards to the eye glasses. It is de- 
 cidedly a microscope of excellent construc- 
 tion, especially as improved by Mr. TuUey 
 and Dr. Goring. (See Tulley and Goring') 
 
 Amici's Camera Lucida. This instru- 
 ment is, in general form, like that of Dr. 
 Wollaston's. (See Camera Lucida.) The 
 structure of the glasses is as follows :— 
 
 Suppose A to be a triangular prism of 
 glass, or else a metallic speculum, having its 
 upper side reflective, and connected by one 
 of its other sides to a piece of plate glass 
 DEC. The angle which the reflecting 
 surface makes with the side of the plate 
 glass being 130". The rays from the ob- 
 ject O impinge upon A, are reflected to B, 
 and again to the eye, which looking down- 
 wards sees the object at F, through the piece 
 of plate glass DEC. The pencil is also 
 seen through the plate glass, at or near the 
 same point ; and as both are seen throxigh 
 the same medium, much less fatigue to the 
 eye, and facility of management is acquired, 
 than by Dr. Wollaston's instniraent, where 
 the sight is to be carried through media of 
 such different density as glass and the air. 
 
 Another construction, which is also due to 
 Amici, is as follows : — 
 
 Let A represent the mirror upon which 
 the light from the object O is reflected. (It 
 is to be observed, that in this instrument, as 
 well as some of the others, the light traverses 
 through the piece of plate glass, yet as tli^ 
 
AM 
 
 AM 
 
 Bides of it are exactly parallel, it is not di- 
 verted from its course ;) and DEC the 
 glass as before. The light passes to the in- 
 ner side of A, thence to B, and from B to 
 the eye above, which beholds the object at F, 
 «ien through the glass as before. 
 
 Amidine. a substance procured by boil- 
 ing starch in a large quantity of water. Pass 
 the liquid through a double filter, the solu- 
 ble part will pass through ; the membranes 
 of the grains of fecula or starch will remain 
 on the filter. Boil these again, and filter a 
 second time ; what is now left on the filter 
 is amidine. It is whitish, very friable, in 
 irregular fragments, destitute of taste or 
 smell. It does not form a jelly with boiling 
 water, is colored blue by iodine, and its 
 solution is not viscid when mixed with potass. 
 
 Ammonia. This volatile alkali, when pure, 
 is gaseous, transparent and colorless, of a 
 pungent smell, and caustic taste ; is rapidly 
 absorbed by water, then called liquid ammo- 
 nia, or spirits of hartshorn. Ammonia is 
 exttnsively used in chemistry, medicine, and 
 the arts. It consists of 3 parts hydrogen, 
 and 1 azote. 
 
 Ammoniac. A gum resin, extracted from 
 the dorema armeniacum, a Persian plant. 
 Besides its use in medicine, it is employed in 
 cemtnts, mending china, glass, &c. 
 
 Ammoniacal LiauoR. A liquid which 
 passes off from the retort when co ils are 
 submitted to distillation, as in the process of 
 the gas manufacture. One ton of coals will 
 produce from 17 to 20 gallons. It consists 
 chiefly of the carbonate and the sulphate of 
 ammonia, of uncertain degrees of purity. 
 
 Ammoniurets. Substances composed of 
 ammonia united with a metallic base. 
 
 Ammonium. The supposed base of am- 
 monia, never yet obtained. 
 
 Amniotic Acid. A crystallized acid, 
 formed by evaporating the liciuor amnios of 
 the cow. It is soluble in both hot and cold 
 water, is decomposed by heat, unites with 
 the alkalies, and is precipitated from ther< 
 by the other acids. 
 
 Amonton's Fire Wheel. A complicated 
 machine, which was to rotate by the power 
 of rarefied air. A description is in " Stuart 
 on the Steam Engine." The machine is 
 extremely complicated ; and, if useful at all, 
 was only so in the infancy of knowledge 
 of steam, at which time, (1699,) it was 
 suggested. 
 
 Amonton's THERMOMETEii,con- 
 sisted of a tube, 4 feet long, ending 
 in a ball below, bent upwards as in 
 the figure, and open at the other ex- 
 tremity. The measure of the tem- 
 perature was the elasticity of a given 
 portion of air included in the ball, 
 and subjected to the pressure of an 
 extra atmosphere, by pouring into 
 the tube mercury — it formed a co- 
 lumn of 28 inches in height ; thus, 
 using a tube only half as long as 
 would have otherwise have been requisite. 
 The instrument seems never to have been 
 used, except by the inventor, because the 
 varying state of the atmosphere rendered it 
 uncertain in exact result. 
 
 Amorphous. Not possessing any specific 
 form. 
 
 Ampere's Electrodynamic Cylinder, 
 An apparatus contrived of copper wire, 
 wound spirally into a cylinder. The ends of 
 the wire being connected with the poles of a 
 galvanic battery, and the machine so sus- 
 pended as to be free to move on its centre, 
 the cylinder will arrange itself in the mag- 
 netic meridian. 
 
 ■i 
 
 Two forms are given to this little appara- 
 tus, as above represented. In one the cy- 
 linder of wire is poised upon a point, the 
 two ends of it dipping into two channels, 
 cut in a wooden cup, and containing mer- 
 cury. The small cups leading to the diffe- 
 rent sides of the battery being connected one 
 with each channel of mercury. Thus, in 
 fig. 1, the galvanic fluid enters at P, passes 
 along the arm A, the coil B, the other arm C, 
 and finally out at Z. The other figure shows 
 the coil suspended from its ends in two cupg 
 filled with mercury, and leading to the diffe- 
 rent sides of a galvanic battery. 
 
 Ampere's Rotative Battery, or 
 Bucket. An instrument which, owing to its 
 galvanic disturbance, rotates upon one <d 
 
AM 
 
 AN 
 
 the poles of a magnet, forming one of the 
 most beautiful experiments in electro-mag- 
 netism. 
 
 It consists of a double cylinder, made of 
 copper, as represented in C. These are sol- 
 dered together by a bottom cut in the form 
 of a ring — the outer part fitting the larger 
 cylinder, and the inner part the smaller ditto. 
 When made, the cylinders may be half an 
 inch apart, and the outer one 2 or 3 inches 
 in diameter. The centre part of the bottom 
 is cut away, so as to admit a magnet, D, up 
 the inner cylinder, until it bears upon its 
 pole the point E — this point being connected 
 with the inner cylinder by a wire. The se- 
 cond part of the apparatus is at B ; it con- 
 sists of a hoop of zinc, a wire to hold it, 
 and with a point at top. When in use, the 
 cylindrical cup C is to be put on the pole of 
 a magnet ; the hoop and wire B is to rest 
 upon it, and dilute acid to be poured in, 
 when the copper will turn round one way, 
 and the zinc hoop the contrary way. A good 
 connection between the two being kept up 
 by a drop of mercury being poured into the 
 cup at the top of E. 
 
 Amphiprostyle. a bxiilding having a 
 portico at each end. 
 
 Amphitheatre. A spacious building, 
 either oval or round, having the arena or pit 
 encompassed with a vast number of seats, 
 disposed in rows, and rising gradually one 
 over another. Its use among the ancients 
 was to exhibit shows to the people, as the 
 combats of gladiators and wild beasts. The 
 amphitheatre of Vespatian or Titus, called 
 the Coliseum, was one of, if not the very 
 largest. It held from 80 to 100,000 spec- 
 tators, and at its opening a combat took place 
 of nearly 9,000 wild beasts. It is built of 
 stone, has four rows of columns externally. 
 The walls are 160 feet high, the interior 
 is 620 feet long, and 513 feet wide. 
 
 Amphiscii. All people living on the torrid 
 zone have their shadows directed in one 
 time of the year towards the south, and in 
 
 the other towards the north, in consequence 
 of the difference in the sun's declination. 
 
 Amphora. A vase having two handles, 
 and containing from 7 to 10 gallons. 
 
 Amplitude. The position of any of the 
 heavenly bodies when on the horizon. Thus 
 we speak of the sun's rising amplitude, and 
 his setting amplitude, meaning thereby the 
 exact point of the compass he is visible in at 
 the time of rising or setting, or when just 
 visible above the horizon. It is reckoned in 
 degrees from the east and west points, and 
 is the complement of the azimuth. 
 
 Amplitude, in Gunnery. The range of a 
 projectile. 
 
 Ampulla. An oblong vessel, bellying out 
 like a jug, chiefly of earth or glass ; used 
 among the ancients to contain oil for the 
 anointing their bodies. 
 
 Amylic Acid. Procured by distilling 
 starch, mixed with equal parts of black oxyde 
 of manganese, and moistened with water. 
 It turns sour, reddens vegetable blues, and 
 with bases forms neutral salts, very soluble, 
 and deliquescent. 
 
 Anacamptics. The science of the reflec- 
 tion of sound, particularly echoes. It is 
 now called catoptics. 
 
 Anaclastics. An old name for dioptics. 
 
 Anaclastic Curves. Apparent curv-es 
 seen at the bottom of a vessel of water, caused 
 by the refraction of light. 
 
 Anaclastic Glasses. A kind of sono- 
 rous, funnel-shaped phials, made with ex- 
 tremely large, slightly concave bottoms, as 
 thin as possible. On applying the mouth to 
 the orifice, and gently sucking out the air, 
 the bottom gives way with a tremendous 
 noise, and the convex becomes concave. 
 Upon breathing gently into the glass, the 
 bottom, with no less noise, bends back to 
 its former place, and becomes again convex. 
 
 Anaglyphic Art. The art of chasing, 
 carving, and embossing plate ; in opposition 
 to diaglyphic, which see. 
 
 Analemma. a tabular mark, usually in 
 the shape of the figure 8, depicted across 
 the torrid zone, on a terrestial artificial globe, 
 to notify the sun's declination on any day in 
 the year. 
 
 Analysis. The art of separating a com- 
 pound into its constituent parts. In che- 
 mistry this art is of the greatest importance. 
 The opposite of analysis is synthesis. 
 
 Analysis, in Mathematics, is of two 
 kinds ; finite analysis, or algebra ; and the 
 analysis of infinites, called also the neio 
 analysis, Auctions, or differential calculus. 
 
 Analysis of Powers. The resolving 
 them into their roots. 
 
 Analysis of Curved Lines, shows 
 their constitution, nature, and properties. 
 
 Analytics. The science of mathematical 
 analysis. 
 
AN 
 
 AN 
 
 Analytical Formula, or Expression. 
 A combination of symbols, or signs, ex- 
 pressing or representing a series of calcu- 
 lation, and including every particular case 
 that can arise from a general law. 
 
 Analyzing Plate. A plate of glass, 
 or a slice of a crystal ; used for examining 
 the properties of polarized light. 
 
 Anamorphosis. A distorted represen- 
 tation of any object, so contrived as to ap- 
 pear symmetrical from a certain point of 
 view; or when reflected from a certain- 
 shaped mirror, such as one which is cylin- 
 drical, conical, &c. Thus the following will 
 appear in true form when viewed from the 
 point C, and at the height D, as is easily 
 managed by cutting a piece of paper, as 
 is represented in E. 
 
 work, and the clamp 
 wedged to the anchor. 
 
 rivetted, or rather 
 
 Anatron. The scum which floats upon 
 molten glass in the furnace, sometimes called 
 sal vitrei, which, when taken off", melts in 
 the air, and becomes common salt. Also, a 
 compoimd salt, formed of quicklime, alum, 
 vitriol, common salt, and nitre ; used as a 
 flux for certain metals — this is also called 
 terra saracenica. 
 
 Anbury. Club root, as found on the cab- 
 bage, occasioned by the puncture of an insect. 
 
 Anchor. A heavy curved hold-fast, to 
 retain ships in a required position. They 
 are either mooring anchors, such as are sunk 
 in docks, or anchorages, for the general use 
 of tying up the vessels around ; or ship's 
 anchors, for the use of one ship only, and 
 that when and wherever it may be requisite. 
 
 Anchor and Collar. Collar and Clamp. 
 Strong hinges used for flood, lock, and other 
 strong gates. They are of the following 
 form ; the anckor being let into the stone- 
 
 Anchor. In architecture, part of the 
 echinus, or egg and anchor ornament. (See 
 
 Effff') 
 
 Ancones. The ornaments depending from 
 
 the cornice of Ionic doorways and windows. 
 
 (See Consoles and Trusses.) 
 
 Andirons. Handirons. The logs or 
 iron bars used formerly to support the burn- 
 ing logs in the hearth, now mostly superseded 
 by stoves. 
 
 Androides. a term sometimes given to 
 those automata which imitate human kind. 
 
 Andron. a passage between two houses. 
 
 Anelectrode. The positive pole of a 
 galvanic battery. 
 
 Anemometer. An instrument for mea- 
 suring the strength, or velocity of the wind. 
 The following is one of the most simple :— 
 
 The frame A turns round upon the spin- 
 dle B, by the action of the wind upon C. 
 D is a vane fixed on the axis E, whicli is, in 
 its middle, conical, upon one end of which is 
 fastened a string. The wind acting upon the 
 sails winds up the string, while a racket wheel 
 and catch prevents any retrogade motion. 
 
 Anemoscope. Any instrument to ascer- 
 tain the direction of the wind ; a weather 
 vane ; chiefly applied to those contrivances, 
 which, connected with a weather cock above, 
 bring down its indications to a dial placed at 
 a distance. 
 
 The following shows one of the most usual 
 
 arrangements. The spindle which supports 
 
 the letters is hollow. The vane A is fixed to 
 
 1 a long iron rod, passing downwards to tlxe 
 
AN 
 
 AN 
 
 wheel B. C is a similarly-sized and shaped 
 wheel working in it, and connected by its 
 Bpindle witl che index or hand D belonging 
 to the dial plate. The wind turns the vane, 
 that turns the wheel B, which works C, and 
 that turns D, exactly as much as the vane at 
 top is affected by the wind. In the same cut 
 is seen the front view of the dial plate. 
 
 Anfractous. Turning or winding in and 
 out irregularly, as a metallic vein. 
 
 Angle. A corner formed by two or more 
 Jines, or surfaces, from different directions, 
 meeting each other. If the angle be formed 
 of lines only, it is called a linear a.r\g\e, such 
 as that made by the junction of two hedges 
 in a field ; if consisting of the union of two 
 surfaces it is a superficial angle, as the cor- 
 ner of a house, wall, &c. When more than 
 two surfaces meet in a point a solid angle is 
 formed ; this is the case with crystals, spires 
 of churches, &c. A solid angle may also 
 be made by a circular body, as the angle at 
 the apex of & cone. In a pyramid all these 
 different angles are seen ; each face being a 
 triangle, it contains three linear angles — the 
 union of one face with another forms a su- 
 perficial angle, while at the apex, and also at 
 the corners of the base, are solid angles. 
 
 
 Angles, whether linear, superficial, or so- 
 lid, are further distinguished from each other 
 by the form of the lines which bound them. 
 If these be straight they form a rectilinear 
 angle, such as A ; if of curved lines, a cur- 
 vilinear angle ; if of circular curves, a sphe- 
 rical angle, as B ; if one line be curved, the 
 other straight, a mixed angle is formed, as C. 
 
 Angles are measured in degrees. The cir 
 cumference of every circle is divided into 
 360°. Cut the circle in half by a diameter 
 D B, each half will be 180°. Now as the 
 diameter is but one straight line, no angle 
 will be formed at the centre ; thus no angle 
 can be so much as 180°, but it may be any 
 thing less than this. Erect a perpendicular 
 C O at the centre of the last line, and two 
 equal angles will be seen at the centre, each 
 measuring 90° it will be a right angle. If the 
 second line C O be not perpendicular to A B, 
 the angle on one side would be an acute angle, 
 or less than a right angle ; the angle on the 
 other side obtuse, or greater than a right 
 angle, as is seen by the angles on each side 
 of A O. Obhque angle is a name common 
 to all that are not right angles. 
 
 An angle, when standing alone, is indi- 
 cated by a single letter, when united with 
 other angles, three letters are necessary to 
 distinguish it. Thus in fg. 1, (below,) A 
 alone marks the angle suflciently. In fig. 2, 
 the corresponding angle would be called 
 B A C, to distinguish it from the angle D AC, 
 E AD, E A C, or D A B. The letter A 
 being common to alk 
 
 Angle, Adjacent or Contiguous, Exte. 
 rior and Interior, are such as have one side 
 common to both, they being on opposite 
 sides of it. 
 
 Angle, Vertical or Opposite. When an 
 angle is formed by continuing the legs of 
 another beyond the angular point, three other 
 angles are formed. Those which are of the 
 same size are called vertical, or opposite, as 
 B A C is vertical to E A D, and E A C to 
 BAD; also B A C is an exterior angle, or 
 without the original figure, and E A D an 
 interior angle. 
 
 C A 
 
 Angle, Alternate. When a line is drawn 
 across two parallel lines, the two angles on 
 
AN 
 
 AN 
 
 the same sides of it are alternate, as A B C 
 and D C B ire alternate. 
 
 Angle, Salient, Sortant, or External, 
 and Re-entering or Internal. One angle pro- 
 jecting beyond another, or beyond a surface. 
 The outer part is called a saltient angle, the 
 inner a re-entering. Thus in the following 
 figure the dots are salient angles, the crosses 
 are re-entering angles. 
 
 Angle of a Segment, or a Semi-circle. 
 Any angle formed by two lines drawn from 
 the opposite ends of a segment, and meeting 
 in the arc. 
 
 Angle, Truncated, Chamfered, Splayed, 
 or Bevilled. It often happens that the 
 extreme point of a solid or superficial angle 
 is cut off, either naturally or by design. If 
 the latter, as, for example, in the corner of a 
 wall to prevent an abrupt turn, it is said to be 
 splayed or chamfered ; if naturally occurring, 
 as is extremely common in crystals, it \s 
 called a truncated angle ; or, as it is better 
 expressed, truncated at the angles, as in the 
 following cut : — 
 
 Although in this case the angles are re- 
 moved, yet what the figure would have been 
 with them is as easily ascertained by the in- 
 clination of the sides, as if the angles had 
 remained perfect. 
 
 Angle, Visual. The apparent size of an 
 object depends upon the size of the angle, 
 which its opposite extremities make with the 
 eye of the observer. The greater the an- 
 gle, of -course the larger the object will ap- 
 pear io be. This is totally distinct from its 
 real magnitude, which at all distances is the 
 same, though the object is apparently so 
 much larger when near than when remote. 
 
 Angle of Aperture. An ang*ilar mea- 
 fcurement of the rays of light, admitted into 
 
 the aperture of a telescope or microscope. 
 (See Aperture.) 
 
 Angle of Contingence, or Contact. Also 
 called tangential angle. The angle made by 
 the contact of a tangent, and the curve upon 
 which it impinges. 
 
 Angle of Draught. When a power is 
 applied to drag or roll a body over a surface, 
 it has to overcome certain obstacles, parti- 
 cidarly those arising from the inequality of 
 the ground, which are greater or less accord- 
 ing to their own nature, and the friction or 
 weight of the moving body. There is in 
 every case a certain direction of the drawing 
 power better adapted than any other to 
 overcome these obstacles ; this is called the 
 angle of draught. So, also, when the mo- 
 tive power be animal strength, it is always 
 to be considered at what angle with the 
 ground the muscular powers of the animal 
 are best called into action. 
 
 Angles of Elevation, is that angle with 
 the natural level of the ground, at which a 
 cannon or other similar instrument is pointed, 
 in order that the ball, or other projectile, may 
 reach a certain point, after being fired from 
 it. This angle, as illustrated by the following 
 example, will, of course, vary according 
 to the strength and quantity of gunpowder, 
 state of the wind, weight of ball, &c. In 
 all cases, an angle of 45° with the horizon is 
 that elevation at which the projectile is 
 thrown the farthest. 
 
 It also signifies the angle at which an 
 elevated object is seen by an observer on the 
 level ground, as, for example, a balloon, 
 and this without reference to its actual 
 height ; for it will be seen from the following 
 diagram that the angle of elevation has re- 
 ference to the distance from the observer, as 
 well as its positive height. 
 
AN 
 
 AN 
 
 The angle of elevation of the balloon when 
 at B is B A E, but when the balloon is at C 
 its angle of elevation is CAD, although 
 the height of it from the ground is the same 
 in both instances, B E and C D being equal. 
 When below the plane of the observer it is 
 called the angle of depression. 
 
 Angle, Horary. The angle formed with 
 the meridian of any place, by a great circle 
 which passes throiigh a star and the pole. 
 
 Angle of Inoidence and Reflection. The 
 angle of incidence is the angle at which a 
 moving body strikes a flat body at rest ; and 
 the angle of reflection is that at which the 
 same moving body flies off" again ; and, sup- 
 posing no disturbance from roughness of 
 surface, or irregular friction, one of these 
 angles will be always equal to the other, or 
 as it is common to say, " the angle of inci- 
 dence is equal to the angle of reflection." 
 This great law of physics is of the first ne- 
 cessity to be considered in treating of light, 
 heat, and sound. It is also the fundamental 
 principle upon which billiards and similar 
 games are played. These angles may be 
 exemplified as follows : — 
 
 Let A B be a flat and smooth surface. If 
 a ball be bowled against it from C, so as to 
 strike it perpendicularly at O, it will fly back 
 again to the hand, because, as it is bowled 
 to the flat surface at the angle of 90°, it flies 
 back again at 90° ; that is, comes back in the 
 same direction. If the ball be thrown from 
 the point D to the point O, it will fly off" 
 towards E^ making the angle of reflection 
 B O E equal to the angle of incidence A O D. 
 
 Angle of Inclination. The angle which 
 one line or plane makes with another, the 
 exact direction of which is understood, or 
 known to be either perpendicular or hori- 
 zontal. Thus we say, the side of a hill makes 
 a certain inclination with the natural level. 
 The roof of a house makes an inclination of 
 so many degrees with the flat of the building. 
 An arch may have a certain inclination with 
 its abutments. This general application has 
 occasioned the word inclination to be used 
 as synonymous with angle generally. 
 
 Angle of Polarization. One source of 
 the polarization of light is reflection from 
 polished surfaces, when it strikes those sur- 
 faces at particular angles only. This is called 
 the angle of polarization of the substance 
 v.'hich reflects it. Thus glass polarizes light 
 at an angle of 50° • air at 45° ; water at 
 
 53° 14' ; rock crystal at 57° 22'. (See 
 Polarization.) 
 
 Angle of Position. Usually the curvi- 
 linear angle, formed by two great circles 
 drawn through a star to the poles of the 
 ecliptic and equator. Or it may be used to 
 signify any angle made by lines drawn from 
 any point under consideration to any two 
 points, the relative position of which is re- 
 quired. Thus, suppose a person is situated 
 on a bank, and desires to know the position 
 of a windmill and a church, the lines which 
 connect these two points to him forms the 
 angle of position between them. 
 
 Angle of Refraction. When light passes 
 in an oblique direction from one medium to 
 another of a different density, it becomes 
 bent out of its former direction, in propor- 
 tion to the respective density of the two 
 media. Thus, dip a straight stick in clean 
 water, perpendicularly, and it will still ap- 
 pear straight, there being no refraction. 
 Then incline it towards either side, and in- 
 stead of its continuing as before, it will 
 appear bent at the place it touches the water. 
 
 The quantity and degree of this bending 
 A B C is the angle of refraction. 
 
 Angle of Repose. Angle of Friction. 
 The greatest slope at which a carriage will 
 stand at rest on an inclined plane. On a 
 rail-road it is about 1 foot in height, in 
 150 in length ; and on a hard turnpike 
 road 1 in 40 feet. Also the angle at which 
 newly-carted earth will rest without slipping 
 down. In perfectly dry sand this is about 
 30° ; in clay and other tenacious soils about 
 45°. 
 
 Angle Bar. The upright bar of wood 
 which stands at the extremity of each angle 
 
 ^^ 
 
AN 
 
 AN 
 
 of a polygonal window, or canopy, and 
 reaching from the bottom to the top of the 
 window. Also the angular timbers of a 
 spire, or any thing built of a pyramidal 
 or prismatic form. 
 
 Angle Braces, or Angle Ties. Pieces 
 of wood fastened across the angles of square 
 and other angular frames, in order to 
 strengthen the joints at those parts, and to 
 keep the frames of a proper shape. 
 
 Angle Irons. Knee Irons. Elbow Irons. 
 Bars of iron forged of an angular shape, to 
 strengthen the various joints of iron work, 
 particularly those of steam boilers. 
 
 Angle Rafter. The rafter at the junc- 
 tion of any two sides of a hipped roof, and 
 upon which the short rafters are fastened at 
 the upper end. 
 
 Angle Rib. A curved piece of timber 
 placed at the angles of groined ceilings. 
 
 Angle Staffs, or Staff Beads. Beads 
 of wood placed vertically at external angles 
 of windows, doors, &c., where two surfaces 
 of plaster meet, in order to render this part 
 stronger, and avoid the liability of the plas- 
 ter in such situations being broken, or 
 damaged. 
 
 Anglo-Greek, Anglo-Italian, An- 
 glo-Norman, Anglo-Roman, &c. Diffe- 
 rent styles of architecture, so called because 
 founded upon the principles of art adopted 
 by these foreign nations, and yet of edifices 
 built in this country, and so modified as to 
 be adapted to our climate and maimers. Of 
 the Anglo-Roman and Anglo-Saxon very few 
 remains exist. Of the former, the Pharos 
 of Dover Castle ; St. Martin's Church, Can- 
 terbury ; Richboro' Castle ; and Newport 
 Gateway at Lincoln ; with a few walls and 
 tessellated pavements, are the only relics. 
 Of the Anglo-Saxon buildings still fewer 
 records exist. The Tower of Earl's Barton, 
 Northamptonshire, and Barton, Lincoln- 
 shire, are supposed to be of this sera. Anglo- 
 Norman remains are frequent ; example, 
 Rochester Cathedral, St. Bartholomew's 
 Church, and the Temple Church, London, 
 St. Alban's Abbey Church, &c., were built 
 in this sera, which extended from William I. 
 to Henry I ; gradually passing into the 
 pointed Gothic in succeeding reigns. The 
 Italian or Venetian, blended with the Gothic, 
 formed the Elizabethan structure ; while the 
 beautiful proportions of the Greek styles 
 were introduced into England by Inigo Jones, 
 in the reign of Charles I., of which the first 
 and one of the finest examples is the Ban- 
 queting Room of Whitehall. Anglo-Grecian 
 buildings are now of constant erection. 
 
 Angular Capital. The term is applied 
 chiefly to the Ionic capital, when all its sides, 
 or wiiere two of its adjacent sides are made 
 to correspond, in order that it may be adapted 
 to the corner of an edifice wliich has co- 
 
 lumns in front and flank, that it may range, 
 with both. 
 
 Angular Modillions. Modillions which 
 are placed at the corner of a building, and 
 so as to project from the exact angle formed 
 by the two sides, equally deviating from both, 
 (See Modillion.) Angular capitals and mo- 
 dillions are not found in the classical remains 
 of Greece, nor yet in the more ancient 
 Roman edifices 
 
 Angular Motion. When a body moves 
 in an arc of a circle, its motion is not mea- 
 sured by the direct distance passed over, but 
 the number of degrees ; so that two bodies 
 may have the same angular motion, whose real 
 velocities are very different, as is seen in the 
 following diagram : — 
 
 The angle is 90°, thus the two balls in 
 going across the angle would each have 90° 
 of angular motion, though, as will be evident 
 from their respective paths, one will travel 
 nearly twice the distance of the other. 
 
 Angular Motion, or Velocity of the 
 Earth, is its diurnal rotation, measui-ed in 
 degrees ; thus, as its rotation is once in 24 
 hours, its angular motion is 360'' in this 
 time ; but as no angle can be more than 180°, 
 the angular motion is not mentioned as more 
 than this. The term is applied when cal- 
 culating the tides, and the angular position 
 and velocity of both moon and earth must 
 be observed. 
 
 Angular Velocity. The swiftness with 
 which a body revolves around a given point, 
 as a sling around the hand, or the earth 
 around its axis. 
 
 Angulometer. An instrument adapted 
 to measure external angles. The following, 
 by Mr. Hall, will show its principle and 
 usual construction : — 
 
 Anhydrous. Such substances as are 
 without water in their composition. 
 
 Animal Charcoal. Charcoal produced 
 by burning the bones and other parts of 
 animals. 
 
 Animal Electricity. A certain de- 
 velopment of the electrical fluid in the 
 muscles of particular animals, whereby they 
 
AN 
 
 AN 
 
 are enabled to give sKocks, either for their 
 own defence, or for catching their prey. 
 /-U the electrical animals known are of the 
 fish kind, either different species of the ray- 
 kind, or of eels. The most powerful is the 
 gymnotus electricus, an eel 4 or 6 feet long, 
 found abundantly in the marshy rivers of 
 Guiana. 
 
 Animal Magnetism. A name given by 
 Mesmer, in the latter part of the last cen- 
 tury, to certain effects produced by one 
 person upon another, and which were as- 
 sumed to be of a magnetic nature. The 
 means employed are touching with the 
 hands, waving them in certain directions, 
 along or in front of the face, while the mag- 
 netizer remains opposite the person mag- 
 netized, and fixes his eyes steadfastly upon 
 him. After some time, the person operated 
 upon, (who, it may be remarked, ought to 
 be of weak nerves and constitution, and of 
 the opposite sex,) becomes languid, and falls 
 asleep, from which he cannot be awakened 
 until the magnetizer dissolves the enchant- 
 ment by some counter-spell. The whole is 
 most probably the effect of imagination. 
 
 Animal Power. The capability of an 
 animal to sustain weights, and to move with 
 more or less rapidity. An animal can sup- 
 port the greatest load when standing still. 
 The load he can bear when moving diminishes 
 as his velocity increases, till at length his 
 whole strength is expended in moving along 
 his own weight. The greatest effective power 
 of an animal, as, for instance, a horse, is 
 when he moves with one-third his greatest 
 velocity, when unloaded, and bears 4-9ths of 
 the load he can just move. Animal strength 
 depends somewhat therefore upon the weight 
 of the animal itself, but still more so upon 
 the manner of using its strength. A horse's 
 power is best directed when he draws a loaded 
 carriage, and also when, by the adjustment 
 of the load, a part is thrown upon his back. 
 A man's power is most called out in rowing. 
 If in working a pump he can exert a force 
 of 100 lbs. ; in turning a winch the same 
 exertion will be equivalent to 167 lbs. ; in 
 ringing a bell 227 lbs. ; and in rowing a boat 
 248 lbs. A horse's strength is, according 
 to Smeaton, equal to that of five men. 
 
 Anime. a resin of a pleasant scent, used 
 in perfumery and medicine. 
 
 Animin. An oily fluid, odorous like harts- 
 horn, extracted from animal oils by distil- 
 lation. 
 
 Anion. That part of a body decomposable 
 by galvanism, which is attracted to the anode 
 or positive pole ; thus, in the decomposition 
 of water, as oxygen is attracted to the posi- 
 tive pole, it is an anion, while the part, (hy- 
 drogen,) which is taken to the negative pole 
 is a cathion, and both together are called 
 
 Anker. A cask holding 10 gallons ; ap^ 
 plied only to the casks of brandy brought by 
 smugglers, called by them tubs. A 5 -gallon 
 cask is called a half -anker , a. pin, or a keg. 
 
 Annatta. (See Amotta.) 
 
 Annealing. A process by which glas5, 
 and also various metallic bodies, are changed 
 from a state of brittleness to one of tough- 
 ness. This is accomplished by keeping them 
 for a length of time at a very low heat, and 
 afterwards cooling them very slowly. 
 
 Annual EauAxioN. (See Equation.) 
 
 Annular Vault. A vaulted roof, sup- 
 ported on circular walls, as was the west 
 end of the Temple Church, London, and 
 the Temple of Bacchus at Rome. 
 
 Annulate D Columns, are those that 
 are clustered together, or joined by bands, 
 as in Salisbury Cathedral, Westminster Ab- 
 bey, &c. 
 
 Annulet. The fillets which surround the 
 base of a Grecian Doric capital ; usually 
 3 in number, each of the 2 lower of less 
 diameter than that fillet above it. The rings, 
 or bands that sometimes surround the stafts 
 of other columns are also often called 
 annulets. 
 
 Anode. The positive pole of a galvanic 
 battery, as opposed to cathode the negative. 
 The anode is called also zincode. 
 
 Anomalistic Year. The time that the 
 earth takes to pafs through her orbit, until 
 she arrives at the exact spot again, which, on 
 account of a slight movement in the line of 
 the apsides, is rather more than a common 
 year. 
 
 Anomalous. Nameless, that is, so irre- 
 gular in shape, color, &c. that it cannot be 
 properly designated 
 
 Anomaly, in astronomy signifies the de- 
 viation of the planets from their true peri- 
 helion, which arises from their inequality of 
 motion. It is either mean or true. Tlie 
 mean anomaly is the angular distance from 
 the perihelion, supposing it to move in a 
 circle. The true anomaly is its angular dis- 
 tance from the perihelion in its elliptical 
 orbit. 
 
 Ans^, in Astronomy. The ring of Saturn 
 is so called, when it appears like a handle 
 on each side of the planet, as is the case 
 whenever the planet is in such a position 
 that we see the exact edge of the ring. 
 
 Ant^. Pilasters which terminate the side 
 walls of a temple, when they are brought 
 beyond the inclosed part of the building. 
 (See Antis.) 
 
 Antefixa. Terra cotta, or sculptured 
 marble blocks placed above the eaves of a 
 building to hide the ends of the rafters ; 
 
AN 
 
 AM 
 
 when these latter are raised like ridges above 
 the tiles, they have the honey-suckle, or 
 other device, engraved upon them. 
 
 Such ornaments are often placed on the 
 upper ends of the ridges also, as in the 
 above example. The lion's head, or mask, 
 placed along a cornice, and at the ends of 
 a pediment, are likewise called antefixa ; the 
 following is such an one from the Greek. 
 
 Antemurale. Any outwork. 
 
 Anteportico. An outer porch or vesti- 
 bule, called the propyloeum, in classic 
 architecture. 
 
 Antepagments. The jambs of a door, 
 when ornamented with mouldings similar to 
 those of the architrave. The lintel, when 
 thus ornamented, is called the supercilium. 
 
 Anterides. Synonymous with buttresses. 
 
 Anticum. a porch ; also that part of a 
 temple between the body of it and the 
 portico. 
 
 Anthracite. A species of coal which 
 burns without flame or smoke; it is very 
 difficult to ignite, but once ignited, burns 
 with an intense heat, therefore, of the 
 utmost value in the smelting of iron. It is 
 called also stone coal, blind coal, glance 
 coal, and Kilkenny coal. 
 
 Anti-attrition. A mixture of 4 parts 
 of hog's-lard and 1 of black lead ; used to 
 lubricate the axles of carriages, and the 
 rubbing parts of other machinery. 
 
 Anti-dryrot. a name given to a solu- 
 tion of corrosive sublimate, when applied for 
 the saturation of timber, as it prevents the 
 growth of that fungus called the dry-rot. 
 
 Anti-inflammable Substances. Such 
 bodies as prevent others, to which they may 
 be applied, from catching fire ; such are 
 alum, the carbonate of soda, potass, &c. 
 
 Antick. a fanciful composition of men, 
 birds, beasts, foliage, &c., formed out of 
 
 each other, as is often seen on cameos anA 
 engraved gems ; also all trophies and extra- 
 neous ornaments to buildings. 
 
 Antiguggler. a small tube, which is 
 inserted into the mouth of bottles or carboys, 
 to admit air while the fluid is running out ; 
 necessary because of the corrosive nature cf 
 the liquids contained, and the guggling and 
 consequent splashing of which would be 
 unpleasant. 
 
 Antimony. A white brittle metal, of a 
 striated texture, spe. gra. 6'712, melts at 
 810° Fahr., and volatilizes at a great heat ; 
 is soluble in most acids ; unites with sulphur, 
 chlorine, iodine, and phosphorus. It is 
 used in medicine in different states, the 
 making of printer's types, mv.sic plates, 
 specula for telescopes, &c. Its medicinal 
 properties were discovered by Basil Valentine, 
 who administered it as an emetic to his 
 brother monks ; they, however, taking too 
 much were killed ; hence it is called anti- 
 moine, or anti-monk. His future applica- 
 tions of it were more successful. 
 
 Antimonic Acid, is a peroxide of anti- 
 mony, in form of a white hydrate, procured 
 by treating antimony with strong nitric 
 acid, or nitro-hydrochloric acid, concen- 
 trating by heat, and pouring the solution 
 mto water. With alkalies it forms antimo- 
 niates. 
 
 Anti-peculator. A name given by its 
 inventor, Mr. Lawton, to a lock which can- 
 not be picked. 
 
 Antipodes. That part of the world which 
 is exactly contrary to another, both in lati- 
 tude and longitude ; or, in other woi'ds, if a 
 hole be supposed to be bored from any given 
 place through the centre of the earth to the 
 opposite side, that part would be the anti- 
 podes to the former place. The antipodes 
 to England is a point in the Southern Ocean, 
 in latitude 51^° S, and longitude 180° W. 
 At this place it is night during our day, and 
 summer during our winter. 
 
 Antique. This term U used to signify a 
 a building, statue, gem, &c., made at a time 
 when the arts were in their greatest purity 
 and perfection among the Greeks and Ro- 
 mans. 
 
 Antique, Modem. Any thing made in 
 modern times to imitate what is antique. 
 Gothic architecture is sometimes so called. 
 
 Antique Ornaments. Synonymous 
 with arabesque, except that it contains the 
 grotesque figures of animals, which true 
 arabesque properly does not ; it is more 
 properly called grotesque. The initial letter 
 B is of this kind. 
 
 Antiscii. The people living on different 
 sides of the equator are antiscii to each other, 
 because at noon their shadows are cast in 
 contrary directions. For example, when the 
 sun is on the eouator, the shadows of tliose 
 
AP 
 
 AP 
 
 who dwell in the northern hemisphere will 
 be directed towards the north ; and those 
 in the southern hemisphere will have them 
 projected towards the south. 
 
 Antis. a temple is in antis when it has 
 ant(B, or pilasters, connected with, and im- 
 bedded in the walls, usually with two columns 
 between them. 
 
 Antiseptics. Substances which coun- 
 teract the spontaneous decomposition of 
 animal and vegetable matter. The principal 
 antiseptics are common salt, sulphate of iron, 
 nitre, sugar, vinegar, spices, corrosive sub- 
 limate, creosote, and charcoal. 
 
 Antoeci. Those people who live under 
 the same meridian, but on opposite sides of 
 the equator, and equally distant from it, 
 they have, therefore, day and. night at cor- 
 responding times, but the seasons are con- 
 trary. 
 
 Anvil. A solid mass of iron ; made for 
 the purpose of forging and hammering metal 
 work upon. 
 
 Aperture. Generally a hole, or opening. 
 In optics, it signifies the hole next the object 
 glass of a telescope, or microscope. Accor- 
 ding to the size of this aperture, so will be 
 the conical pencil of light admitted to the 
 instrument ; and, in a great degree, its 
 discerning power will be accordant. 
 
 Apex. The summit of any pointed body, 
 as the apex of a pyramid, an obelisk, cone, 
 &c. 
 
 Aphelion. That point in the orbit of a 
 planet, or comet, in which it is farthest from 
 the sun ; in opposition to perihelion, the 
 nearest point. (See Apsis.) 
 
 Apiaries. A place where bees are kept; 
 ipplied to a collection of, rather than a 
 single bee -hive. 
 
 Aplanatic. Signifies free from error ; 
 applied to those optical instruments in which 
 spherical aberration is completely corrected. 
 
 Apogee. That point of the moon's orbit 
 in which she is at the greatest distance from 
 us. The term is, therefore, of the same 
 meaning, when applied to the moon, as 
 aphelion when applied to the earth, or other 
 planets. The opposite to apogee is perigee. 
 (See Apsis.) 
 
 Apograph. A copy of any writing, in 
 opposition to autograph, which is the 
 original. 
 
 Apollonicon. a name given by its 
 inventors, Messrs. Flight and Robson, to a 
 Stupendous organ, long exhibited in London. 
 
 and capable of being played by mechanism 
 alone, by the hands and feet alone, or by 
 all these united. It has foot pedals, 1900 
 pipes, 45 draw stops, and 2 kettle drums ; 
 3 barrels, each 2 feet in diameter, pricked 
 with tunes, 3 wind-chests, 3 key frames, 
 and 3 sets of keys, (250 keys in all.) Each 
 barrel, wind-chest, set of keys, &c., belonging 
 to a particular part of the instrument, and 
 working either independent, or in unison with 
 the others. The main cylinder is 8 ft. long, 
 and has 5 octaves, with the following stops : 
 open diapason, stop ditto, principal, twelfth, 
 fifteenth, flute, sesqui altera, comet, and 
 trumpet. The second cylinder is 3 ft. 9 long 
 for the bass notes from gamut G, 2 octaves 
 downwards, these are called double diapason 
 pedal pipes ; the largest is 24 ft. long, and 
 23 inches square. Tlie third cylinder is 
 8 ft. long, with the following stops : diapason, 
 or comi stop, stop diapason, violoncello, 
 German flute, wood fifteenth, trumpet, cre- 
 monas, flutes, vox humana, octave flute, 
 hautboys, piccolais, trumpets, diapason, prin- 
 cipal, &c. &c. The whole is inclosed in a 
 case 20 ft. broad, 18 deep, and 24 high. 
 
 Apomecometry. The art of measuring 
 things at a distance. 
 
 Apophyge. Apothesis. Apophysis. A 
 small curvature given to the top or bottom 
 of the shaft of a column, to make it to fit 
 the parts adjoining. It is also called the 
 scape of a column. 
 
 Aposepedine. a substance produced by 
 the spontaneous fermentation and decay of va- 
 rious animal substances, particularly cheese. 
 Called also caseous oxide. The scent and 
 pungent flavor of old cheese are derived 
 from it. 
 
 Apotheosis. Deification, or placing 
 among the gods ; an honor conferred by the 
 ancients upon many of their heroes, empe- 
 rors, &c. 
 
 Apotome. In mathematics, the difference 
 between two powers, which can only be mea- 
 sured by power as 1 and a/2. 
 
 Apparatus. This general term includes 
 the instruments, machines, vessels, and me- 
 chanical contrivances, used to illustrate the 
 particular facts and laws of science, and with 
 which to conduct its experiments. Also, in 
 numerous of the arts, the same term is em- 
 ployed to designate articles, machines, and 
 tools, used for certain specific purposes. 
 Tims we speak of the whole of the imple- 
 ments used in chemistry, as chemical appa- 
 ratus ; or, if it be adapted for a particular 
 object only, we designate it by an appro- 
 priate name ; thus we say, a steam apparatus, 
 a soda-water apparatus, an electrical ma- 
 chine, and so on. Occasionally articles are 
 best distinguished by the names of their in- 
 ventors, or by the place where discovered. 
 For example. Woolf's bottle, Barlow's wheel, 
 
AP 
 
 AP 
 
 Newton's telescope, Davy's miner's lamp, 
 the Leyden jar, the Magdeburg hemispheres, 
 &c. Inventors have frequently given a new 
 name to their contrivances, by which they 
 are desirous such contrivances should be 
 distinguished, and if no other instrument 
 for the like purpose be invented, such term 
 remains an individual name ; or, if others 
 arise it becomes the name of a class of ap- 
 paratus, such as electrometer, receiver, air 
 pump, telescope, microscope, gasometer, &c. 
 (All the apparatus, attendant upon experi- 
 mental science and art will be found under 
 the name by which such is generally known.) 
 Apparent. In astronomy and mathe- 
 matics, denotes things as they appear to the 
 eye, in contradistinction to their real place ; 
 thus we say, apparentplace, apparent motion, 
 apparent size, &c. The sun apparently 
 moves from east to west daily, but in reaUty 
 it is the earth which moves contrariwise. So 
 also apparent time, indicated by a clock, 
 often differs some minutes from true time, 
 as indicated by the sun. The true position 
 of a heavenly body differs from the apparent 
 one, because the light from it takes some 
 time to pass thence to us, and this. must be 
 allowed for. 
 
 Apparition. In astronomy, denotes stars 
 or other luminaries becoming visible, after 
 having been hid, as in a transit. 
 
 Appendage. Any thing attendant upon 
 another, as the minor details of a machine 
 are appendages to the main body of it. 
 Applicate. (See Ordinate.) 
 Approach, the Curve of. A curve of 
 such a nature, that a body rolling down it 
 approaches the bottom, by passing over equal 
 spaces in equal times. 
 
 Approximation. In mathematics, a term 
 ■used to signify a continual approach to a 
 quantity required, when no process is known 
 o*' arriving at it exactly. Thus, the square 
 root of 2 cannot be found exactly, yet so 
 nearly that its approximate value may be 
 used even in the nicest calculations. This 
 process is the bsisis of many calculations in 
 mathematics, and of great importance in 
 numerous practical operations. 
 
 Apron. In gunnery, a piece of lead used 
 to cover the touch -hole of a cannon. 
 Apron. In plumbing. (See Flashing.) 
 Apron. In engineering, is a platform, or 
 flooring of plank raised at the entrance of a 
 ,ock, or beneath flood and lock gates. 
 
 Apron Piece, or Pitching Piece, a 
 horizontal piece of timber in a wooden dou- 
 ble-flighted stair, for supporting the carriage 
 pieces, or rough strings and joistings, in the 
 landings. 
 
 Apron. In ship-building, a piece of curved 
 timber fixed behind the lower part of the 
 stem, immediately above the foremost end 
 uf the keel. 
 
 Appulse. So near an approach of two 
 heavenly bodies to each other, as to be seen 
 by the same telescope at the same time. 
 
 Apse. Apsis. A semi-circular or angular 
 termination to the choir, aisles, or other part 
 of a church. Also, all recesses of these 
 forms, if used for religious purposes, such 
 as for monuments, altars, shrines, &c. 
 
 Apsides. Apsis. The orbits of aU the 
 planets are elliptical around the sun, the 
 sun not being quite in the centre of the ellipse. 
 The two points at each end of the ellipse are 
 called the planet's apsides ; that in which the 
 planet is nearest the sun is called its peri- 
 helion ; the more distant point its aphelion. 
 The line which connects these is cjdled the 
 line of the apsides. The same occurs in the 
 moon's passage around the earth, except 
 that the two apsides are called the perigee 
 and apogee. 
 
 Apsides, Motion of the. The last figure 
 will exemplify this, supposing the oval, which 
 represents the earth's orbit, to turn round 
 the centre of the sun slowly, the luxe of the 
 apsides would of course take a different di- 
 rection each succeeding moment, until a 
 complete revolution had been made, and the 
 line of the apsides stood as at first. There 
 is such a motion in the apsides of all the 
 planets, arising from the disturbance which 
 they occasion to each other's motions, owing 
 to the relative positions of their respective 
 orbits. The motion of the apsides is so 
 slow, that it requires more than 109,830 
 years for the apsides of the earth to make a 
 single sidereal revolution, or to recover its 
 place again among the stars. 
 
 Apteral Temple. One without columns 
 on either side. 
 
 Apyrous. Refractory in the fire, applied 
 to those bodies which remain long in a state 
 of incandescence without change. 
 
AQ 
 
 AR 
 
 AauA-roRTis. The old and still popular 
 name for nitric acid. There are two kinds 
 in ordinary use, one called simply aqua-fortis, 
 which is about a quarter the strength of 
 nitric acid, and double aqua-fortis, which is, 
 as its name implies, double the strength of 
 the common kind. It is used in numerous 
 metallurgical processes, particularly by work- 
 ers in brass and copper, by whom it is known 
 by the name of pickle. Engravers employ it 
 wherewith to etch their copper and steel 
 plates, after the lines have been traced through 
 the etching ground. (See Biting-In.) 
 
 Aqua-marina. Synonymous with beryl. 
 The name of a precious stone of a bluish 
 green color. 
 
 Aqua-regia. a mixture of 2 parts nitric, 
 and 1 of hydrochloric acid ; used for the so- 
 lution of gold, platinum, and other stubborn 
 metals. It is now called nitro -muriatic or 
 nitro-chloric acid. 
 
 AauA-TiNTA. A species of engraving on 
 copper or steel, imitating Indian ink draw- 
 ings. The outlines of the figure are first 
 etched, in the usual manner, upon a sheet of 
 copper or steel ; then a solution of mastic or 
 rosin in spirits of wine is thrown over it ; the 
 spirits of wine evaporating, leaves the mastic 
 or rosin in minute specks ; acid being poured 
 on the plate, bites in the interstices between 
 the particles of rosin. The lighter parts, 
 when bitten enough, are stopped up with a 
 varnish, and the process continued only of 
 the rest, until by frequently stopping out 
 one part after another, the requisite effect is 
 produced. According to the strength of the 
 solution of rosin, so the specks deposited by 
 the evaporation of the spirit will be larger or 
 smaller, and thus such a coarseness or fine- 
 ness of grain may be given to the work as 
 may be desired. 
 
 AauA-TOFANA. A poisonous liquid, which 
 excited extraordinary attention in Naples, in 
 the 17th and 18th centuries. Tofana, a 
 Sicilian woman, seems to have invented it ; 
 it is said that she poisoned some hundreds 
 of individuals. It is described as a trans- 
 parent and tasteless water, of which 5 or 6 
 drops were fatal, producing death slowly, 
 without pain, inflammation, convulsions, or 
 fever. It seems to have been a solution of 
 crystallized arsenic, with probably something 
 added. 
 
 Aqua Vit^. Any strong ardent spirit, 
 particularly applied to brandy. 
 
 Aquarius. The eleventh sign of the zo- 
 diac, into which the sun enters on the 19th 
 day of January, and leaves on the 18th day of 
 February. It is emblematic of the winter 
 season, or rather the rainy season, such in 
 the hotter countries being equivalent to the 
 winter of the north. 
 
 Aqueduct. An artificial conduit or canal 
 for the conveyance of water from one place 
 
 to another. Tlie Roman aqueducts are still 
 celebrated. They were built in the same 
 manner as such of our railways as are upon 
 arches. 
 
 Aqueous. Any thing composed of, or 
 similar to water ; in painting any nearly 
 colorless transparent tint is so called. 
 
 Arabesque. Moresque. Any fanciful 
 enrichment used upon flat surfaces, con- 
 sisting of interlacing foliage, scrolls, net- 
 work, &c., extremely common in the Moorish 
 buildings, and used by us in endless varieties 
 in paper-hangings, carved work, paintings of 
 borders, interiors, &c. Tlie iron gates of 
 the triumphal arch at the comer of the Green 
 Park, London, is a fine specimen of the 
 arabesque ornament. No figures of animals 
 are seen in true arabesque work. (See Scroll, 
 Antique, and Grotesque Ornament.) Tlie 
 heading of this book, as well as many of the 
 initial letters, show different styles of ara- 
 besque grotesque, and fret ornament. Letter 
 A is from an illuminated manuscript of 1546. 
 Arabic Gum. A gum which flows natu- 
 rally from different species of the acacia, the 
 plum-tree tribe, &c. It is of considerable 
 value for stiffening various fabrics, such as 
 bonnets, lace, linens, &c., and for numerous 
 other purposes in the arts. 
 
 Arabin. The chemical principle which 
 forms the basis of all gums. It is composed of 
 
 Carbon 43-81"] 
 
 Oxygen 49-85 L^q 
 
 Hydrogen 6-2 j 
 
 Azote '14 J 
 
 Arable Lands. Such as are cultivated 
 by the plough, in distinction to pasture lands. 
 Arabo-tedesco. a style of architecture 
 exhibiting a mixture of the Moorish or low 
 Grecian, with the German Gothic. Of this 
 style is the Baptista at Pisa, erected in 1152. 
 The lower story is a Corinthian arcade, the 
 upper Gothic, with pinnacles and sharp 
 pediments adorned with trefoil ornaments. 
 
 Ar^ostyle. a term employed by Vitru- 
 vius to signify an inter-columniation, equal 
 to four diameters of the column, which is the 
 greatest space possible consistent with se- 
 curity. It is only applicable at all to Tuscan 
 buildings. 
 
 (ill 
 
 wi 
 
 Ar^osystylos. That style of building in 
 which four columns are used in the space of 
 8 diameter and a half, the centre inter-colum- 
 niation being 3|, and the others only a half, 
 as is seen in the front of the Louvre at Paris, 
 in which the columns appear in pairs. 
 
AR 
 
 AR 
 
 Arago's Oscillatory Plate. This is 
 the converse of the following instrument. 
 The plate A is made of any metal, such as 
 copper or zinc. It is balanced on its centre, 
 but loaded with a small ball on the circum- 
 ference to enable it to oscillate like a pen- 
 dulum. It was found, that when this plate 
 ■was put between the poles of a horse-shoe 
 magnet, the number of oscillations which it 
 made before being stopped by gravity, was 
 many less than when the magnet was not 
 present. 
 
 Arago's Revolving Plate. A circular 
 plate of copper, made to revolve above or 
 below a magnet, which is so suspended as to 
 be capable of a similar motion. Its object 
 is to show, that metals not usually magneftic, 
 yet become so when put into rapid rotation, 
 as is seen by their influence on a magnet 
 placed near them. 
 
 is useful in turning and polishing rings, hol- 
 low cylinders, and other objects that may be 
 driven over it. 
 
 The above is a view of the apparatus. A 
 is the plate of copper, about a foot in dia- 
 meter. B a freely-suspended magnet. C, D, 
 and E, a pulley, cord, and multiplying wheel, 
 to communicate motion to the copper-plate. 
 When the handle F is turned, and the 
 copper-plate is made to revolve, the magnet 
 revolves also ; and not because of the im- 
 pulse of the air, for it works in the same 
 manner when a sheet of glass intervenes 
 between them. The plate need not be copper, 
 M. Arago says, that all metals, solids, fluids, 
 and even gases, will produce some effect, 
 though the intensity is in proportion to the 
 nature of the substance. 
 
 Arbor. The axle or spindle on which a 
 wheel turns. 
 
 Arbor Chuck. A chuck, consisting of 
 merely a spindle or arbor, generally of metal, 
 projecting from the mandril of the lathe. It 
 
 Arborescent. Growing like the branches 
 of a tree ; as an arborescent plant, an arbo- 
 rescent mineral ; sometimes synonymous 
 with dendritic. 
 
 Arbor Dian^, or Silver Tree. An 
 arborescent deposition of silver ; it may be 
 formed thus — Pour upon mercury in a saUcer 
 a little of the solution of nitrate of silver. 
 After some hours the silver will separate, and 
 lay upon the surface of the mercury in a 
 beautiful series of crystals, resembling the 
 ramified divisions of a tree. 
 
 Arc. Any portion of the circumference 
 of a circle measured in degrees. 
 
 Arc of the Meridian. Any part of 
 the earth's surface, considered in reference 
 to a meridian, or a line running from north 
 to south. The measurement of an arc of 
 one degree, in different parts, enables the 
 astronomer to ascertain the precise form of 
 the earth. Were it exactly globular a section 
 of it would be a circle, and every one of its 
 360° exactly equal to the rest, because all 
 lines drawn perpendicular to the earth's sur- 
 face would meet in the centre ; but lines 
 drawn perpendicular to the surface of an 
 ellipse, or spheroid, do not meet in the cen- 
 tre, but each adjacent pair in a point diflie- 
 rent from the next pair. The angle which 
 any two of them makes, being measured, 
 gives the length of the arc at that particular 
 part of the surface. 
 
 Arcade. A series of arches, supported 
 upon piers or columns, either open, or closed 
 with masonry ; frequently used to decorate 
 the walls of Norman churches, both exter- 
 nally and internally. 
 
 Lately thei-e have been erected in some of 
 our cities ranges of shops, so inclosed as to 
 
AR 
 
 AR 
 
 form a covered line, and to which this name 
 has been given. 
 
 Arcanum. A secret, particularly a secret 
 recipe, or remedy. 
 
 Arch. A construction of stone, brick, 
 iron, &c,, so contrived as to throw any weight 
 above it upon the lateral abutments. The 
 component parts of an arch are its supports, 
 which may be abutments, piers, or columns, 
 A A. The square stone, or stones, capping 
 these, ic called the impost, or platband, B B, 
 immediately above which are the springers, 
 C C. All the stones in the curvature are 
 named arch stones, D D, while the centre 
 of all, and which knits them together at the 
 top, is the key stone, E. The under surface 
 is the intrados, or soffit, and the upper line 
 the extrados. The walls between the crown 
 of the arch, and a line perpendicular to the 
 springing, are the haunches, flanks, or sjjan- 
 drils, F F. The width from the inside of one 
 springer to the inside of the other is the 
 span or chord of the arch, G. 
 
 It is supposed that the principle of the 
 arch was quite unknown till near the time of 
 the Christian sera, no remains existing to 
 show that either the Greeks, Indians, or 
 Egyptians, were acquainted with it. In the 
 very ancient buildings, such as Stonehenge, 
 
 
 a flat stone laid across two uprights was used 
 over openings in walls. Among the Saxons 
 two stones were sometimes used, forming a 
 triangular straight-sided arch. After which 
 time it gradually, and in different countries, 
 assumed various forms, according to the 
 style of architecture of the buildings in which 
 it appeared. The preceding cut represents 
 some of these varieties. 
 
 Arch, Recessed or Compound. Consists 
 of a number of concentric archways, placed 
 within and behind each other, as is common 
 in the Norman and Saxon buildings. 
 
 Arch, Triumphal. A building of which 
 an arcfi is the principal feature, and designed 
 to commemorate the achievements of eminent 
 or illustrious persons. There are two or 
 three celebrated triumphal arches at Rome ; 
 one dedicated to Titus, and another to Con- 
 stantine. Hadrian's at Athens is another 
 beautiful example. 
 
 Arch Buttress. Arch Butment. Sy- 
 nonymous with flying buttress ; but the teem 
 is only used when several flying buttresses 
 unite to sm)port a vault, spire, &c., as in the 
 church of St. Dunstan's in the East, London. 
 
 Archetype. An original design from 
 which a piece of art is to be executed. 
 
 Archil. A whitish branched lichen, grow- 
 ing upon rocks in Portland Island, and more 
 plentifully in the Canary and Cape Verde 
 Islands, whence we receive it as gathered. 
 When bruised and mixed with urine, it 
 acquires after some time a purplish red color, 
 called then orchil ; after a few days it be- 
 comes blue, in which state it is called htmus, 
 a beautiful color, but fleeting, both when 
 exposed to the air, and excluded from it. 
 Hence the dyers use it only to give a bloom 
 to pink and similar colors. It affords, how- 
 ever, a durable scarlet color, by the addition 
 of a solution of a salt of tin. The spirt in 
 thermometer tubes is stained with archil, 
 so are various articles of furniture ; and lit- 
 mus affords to the chemist the most valuable 
 test for acids. 
 
 Archimedes' Screw. A machine for 
 raising water ; it is represented and described 
 as foUows : — 
 
 A is a hollow pipe, coiled around a cylin- 
 drical axis ; which axis is inclined at an angle 
 
AR 
 
 AR 
 
 vrith the ground, and supported at each end 
 upon pivots, the upper pivot being furnished 
 with a handle. When this is turned round, 
 the lower end of the pipe dips into the water 
 in the well below, and turning upwards 
 directly scoops up some of the water. When 
 the end points up, the part B will become 
 lower than it, therefore the water will fall to 
 B. Another half turn of the handle brmgs 
 C to the lowest point, and the first water 
 will occupy tliat part of the tube ; at the 
 same time more water will be scooped up at 
 the end. In a number of turns of the han- 
 dle, equal to that of the coils of the tube, 
 the first water will I'each, and flow out at the 
 top ; and from that time a flow will take 
 place at every revolution of the machine. 
 
 Architecture. The art of designing and 
 constructing edifices of magnitude, whether 
 civil or mihtary. The former of which clas- 
 ses maybe either sacred, municipal, domes- 
 tic, monumental, or relative to bridges and 
 other similar structures. The essentials of 
 architecture are utility, strength, and beauty. 
 Of the most ancient edifices tho^ alone re- 
 main, the strength and solidity or which are 
 enormous. Some of them, as the numerous 
 druidical ruins, show massiveness alone ; 
 others, as the buildings of Thebes, and the 
 caves of EUora, are carefully, though rudely 
 sculptured. The classical remains of Greece 
 first show the quality of strength combined 
 with grandeur of outline and delicacy of 
 enrichment. The different necessities of the 
 religion and habits of nations, their state and 
 degree of civilization, and the variations of 
 climate, have occasioned numerous styles of 
 architecture, and some of these styles have, 
 by the progress of knowledge and refine- 
 ment, been divided into several orders, each 
 of which, no less than the style itself, is dis- 
 tinguished by its appropriate proportions 
 and decorations. (See Doric, Tuscan, Ionic, 
 Corinthian, Composite, Gothic, Elizabethan, 
 8,'c. 8,-c.) 
 
 Architrave. That part of a building, 
 im.mediately above and resting upon the co- 
 lumns ; likewise called epistyle. It also 
 signifies the exterior mouldings to the outer 
 curve of an arch. 
 
 Architrave Cornice. An entablature, 
 consisting of an architrave, crowned with a 
 cornice, without the intervention of a frieze. 
 Archive. A chamber or apartment in 
 which records are kept, and also the docu- 
 ments themselves. 
 
 Archivolt. The inner curve of an arch 
 from impost to impost. The under-surface, 
 if quite flat, is called soffit. 
 
 Arcograph. Any instrument adapted to 
 draw a circular arc, without the use of a cen- 
 tral point. The following simple instrument 
 is very convenient in drawing upon paper 
 ths large curves for bridges, elhptical arches, 
 
 the circular lines upon maps, &c. It con- 
 sists of a piece of wood, shaped like A. It 
 may be I or 2 feet long, and half an inch 
 thick. In the centre of this is a long thumb 
 screw C, the head of wliich does not exceed 
 in diameter the thickness of the wood through 
 which it passes. At or near the ends of A 
 are two square staples, projecting half an inch 
 above the upper face. B is a thin flexible 
 strip of wood or metal, working in the two 
 staples, and curved to any required degree 
 by the screw C, which presses against it. In 
 order that the flexure may be equable and 
 regular, the strip of wood B should be slightly 
 thicker towards the middle of it than at the 
 sides. The manner of using the instrument 
 will be obvious. 
 
 The following method is often practised by 
 masons in striking a curve on a wall : — Drive 
 two nails into the wall, at the ends or spring- 
 ing of the curve. Then nail two rods or laths 
 together at such an angle, that when the 
 sides of the rods touch the nails, the top of 
 them shall touch the crown of the arc. Then 
 hold a pencil, or piece of chalk, at this point, 
 and by moving the rods backwards and for- 
 wards, still keeping the sides of them in 
 contact with the nails, the required curve 
 will be described. 
 
 Arctic. That part of the world towards 
 the northern or arctic pole, as the arctic 
 ocean, &c. 
 
 Arctic Circle. An imaginary circle on 
 the globe, parallel to the equator, and at the 
 distance of 23° 28' from the north pole ; 
 it is also called the north polar circle, and 
 separates the north frigid from the north 
 temperate zone. 
 
 Ardent Spirit. Any strong intoxicating 
 liquid, whether spirits of wine, brandy 
 whiskey, or any other. 
 
 Area. The space contained within the 
 boundaries of any thing, without regard to 
 thickness. The area of a plane figure is 
 estimated by the number of little square 
 spaces that may be contained in it ; each of 
 these spaces being of a certain size, as a yard, 
 a foot, an inch, measured on the side. In 
 building it is an inclosed space exposed to 
 the air. 
 
 Arena. The ground floor or area of an 
 amphitheatre, within the seats for spectators. 
 
 Areometry. The science of measuring 
 the gravity of fluids. 
 
 Afgal. Crude tartar, as it is taken fioin 
 the wine casks. 
 
AR 
 
 AR 
 
 Areometer. An instrument for 
 taking the specific gravity of liquids. 
 The following cheap and very sensi- 
 tive areometer is the invention of a 
 M. deParcieux, of Paris. It consists 
 of a glass phial, corked tight, into the 
 cork of which is fixed a perfectly- t 
 straight wire, or thin rod of wood, E 
 about 2 feet long. The phial is loaded 
 with shot, so as to make it sink in 
 the heaviest liquor to be examined, 
 so much as just to immerse the phial 
 itself to a certain mark made near 
 the lower part of the wire. In addi- 
 tion to this, there is a cylindrical glass 
 tube in which the liquor to be tested 
 is to be placed, which must have a 
 scale of equal parts marked on the 
 side, and which indicate the depth at 
 which the point of the wire falls, ac- 
 cording to the specific gravity of the 
 fluid in the glass tube. This instni- 
 ment is said to be so very sensitive, 
 that, if adjusted to cold water, and then ex- 
 posed to the rays of the sun for a few minutes, 
 the small degree of heat imbibed, and con- 
 sequently the small difference of specific 
 gravity will occasion a sinking of the phial 
 some inches. A pinch of salt, or sugar, 
 thrown in makes it rise some inches, and a 
 little spirits poured in makes it sink. With 
 one of the instruments, weighing somewhat 
 less than 24 ounces, and plunged in water, 
 there is a rise or fall of above half an inch 
 for every 1-1 7424th part of the water dis- 
 placed, so that a difference of a hundred 
 thousandth part is easily perceived. 
 
 Argand Burner. A lamp burner through 
 the centre of which the air is enabled to pass, 
 as in the common table lamps, gas burners, 
 &c. 
 
 Argentate of Ammonia. Ammoniuret 
 of silver. 
 
 Argento-cyanate of Potass. The ful- 
 minate of potass. 
 
 Argento-cyanic Acid. This supposed 
 acid is the bi-fulminate of silver. 
 
 Argentum. The Latin word for silver. 
 Aries. The Ram. One of the twelve signs 
 of the zodiac, in which the sun enters on 
 March 21st, and leaves on the 20th of April, 
 the former of which times is that of the ver- 
 nal equinox. In thfe ancient military art it 
 signified a battering ram, with which the 
 walls of cities, &c., were assailed. 
 
 Arithmetic teaches to compute or cal- 
 culate by means of numbers. It is both a 
 science and an art ; a science inasmuch as 
 its various operations are dependent upon 
 fixed mathematical principles, and an art 
 because these principles are only applicable 
 to the purposes of life by the aid of manual 
 dexterity. It is divided into vulgar, decimal, 
 wr.d fractional. The first treats of whole or 
 
 complete numbers, in their various combi- 
 nations, relations, and proportions. The 
 second supposes the complete number to be 
 attended by parts or portions of a number, 
 and these portions being the relation of 
 tenths, hundredths, &c., to a unit or one. 
 (See Decimal.) The third also supposes 
 parts of a number to be attached to the 
 principal, but these parts are in the form of 
 a vulgar fraction, (which see.) All ope- 
 rations in arithmetic may be said to consist 
 entirely of the rules of addition, subtraction, 
 multiplication, and division. The only cha- 
 racters absolutely necessary are the ten digits, 
 1, 2, 3, 4, 5, 6, 7, 8, 9, 0. 
 
 Arithmetical Progression, {^ee Pro- 
 gression.) 
 
 Arm. The length of a sail of a windmill 
 measured from the axis. 
 
 Arms of an Axle. The two ends of an 
 axle-tree. Projecting supports in machinery. 
 
 Armillary Sphere, An artificial globe, 
 composed of circles and rims of brass or wood, 
 to represent the imaginary circles on the 
 earth and in the heavens, such as the hori- 
 zon, the zodiac, the meridians, &c. It has 
 the same motions on its axis and at its sup- 
 ports as the usual artificial globes. 
 
 Armenian Cement, or Turkish Glue, 
 used for mending glass, jewellery, &c., is 
 made by dissolving isinglass in brandy, or 
 spirits of wine, and adding to it an equal 
 bulk of thick mastic spirit varnish. When 
 made it should be as thick as common glue. 
 
 Arnatta, Arnotto. a coloring mate- 
 rial, formed from the red pulp which sur- 
 rounds the seeds of the bixa orellana, a 
 West Indian plant. It was once much used 
 
AR 
 
 AR 
 
 by the dyers, but is not now much esteemed, 
 Gloucester cheese is colored with it, and in 
 Holland butter also. 
 
 Armature. The piece or pieces of soft 
 iron that are used to connect together the 
 poles of a magnet, in order that the magnetic 
 fluid may circulate from one pole to the other; 
 and that thus the magnets may remain un- 
 impaired by time or keeping, (No. 1.) In a 
 magneto-electric engine the armature is of a 
 more complicated form, consisting of iron 
 reels, wound round with covered wire, (No.2.) 
 
 Arnold's Compensation Balance. A 
 balance wheel of a watch or chronometer, so 
 contrived as to expand or contract, according 
 to the temperature to which it may be ex- 
 posed, and thus enabling the chronometer to 
 keep exactly the same rate of going in all 
 climate. 
 
 The rim of this balance, instead of being 
 composed of a solid ring of steel, as in the 
 common balance wheel, consists of three 
 arcs, each composed of two strips of dif- 
 ferent metals, one of them steel, the other 
 an alloy of zmc and silver, or of brass. The 
 adjustment of these metals is such, that the 
 expansibility of one shall counteract the 
 expansibility of the other, and a perfect uni- 
 formity of size in the balance; and, conse- 
 quently m the rate of going of the instru- 
 ment, be preserved in all degrees of heat 
 and cold. The use of the weights is that 
 the momentum shall reside in the rim of the 
 wheel. 
 
 Arnott's Stove. An inclosed fire place, 
 which communicates heat to the surrounding 
 air by radiation, it being filled with heated ai? 
 and heated smoke, passing from or through 
 tie fire, and filling an air jacket or chamber, 
 
 the outer case of which becomes hot by this 
 means. Its structure is as follows : — 
 
 A is the outer case of sheet or cast iron, 
 divided into two chambers by the partition 
 B C, which is open at top and bottom. D 
 is the door of thfe ash-pit, containing a re- 
 gister for the admission of air to support the 
 combustion. E the fire-box, which, that it 
 may retain its heat the better, is lined with 
 fire brick. F the hole to admit the fuel. 
 G the chimney. When a fire is lighted, and 
 the doors closed, the chamber H becomes 
 hot by the air direct from the fire. The back 
 chamber is not so heated, and never becom.es 
 so, being separated from the direct action of 
 the fire ; therefore a strong current or circu- 
 lation of hot air is kept up in the direction 
 indicated by the arrows, and this in its pas- 
 sage imparts to the surrounding case nearly 
 all its caloric, before it passes out by the 
 chimney. 
 
 Aroma. A general term for all powerful 
 and pleasant odours, such as the aroma of 
 the rose, the cinnamon, &c. 
 
 Aromatic Vinegar. Acetic acid, scented 
 with camphor, oils of cloves, lavender, and 
 rosemary. 
 
 Arrack. A spirituous liquor, distilled 
 from rice, and also from the juice of the 
 palm tree. 
 
 Arris. The edge or external angle at 
 which two sides or surfaces meet. 
 
 Arris Fillet. A slight piece of timber 
 used in raising the slates around chimneys, 
 sky-lights, &c., that the water may be better 
 thrown off ; when placed at the eaves it is 
 called the eaves-board. 
 
 Arrow. A missile to be discharged from 
 a bow. In land surveying an arrow is one 
 of the wires used to indicate the number of 
 chains in length measured ; also the mark 
 
 '^ 
 
 put upon military and government stores ia 
 called a broad arrow, or broad ar. 
 
ATI 
 
 AR 
 
 Arrow-Heabed Character. A written 
 language, used by the Babylonians and Per- 
 sepolitans, and of which we have many 
 specimens remaining in the bricks and stones 
 brought from Babylon and the neighbouring 
 parts of the East. One of the most perfect 
 of these is in the museum of the East- India 
 Company, and of which inscription the fol- 
 lowing is a part, the characters being en- 
 graved of the same size as in the original. 
 The meaning of them is totally unknown. 
 
 viWXHf I 
 
 mr-H- KUE5 
 
 N3 m 
 
 Arrow Root. The fecula or starch which 
 composes the root of different species of the 
 maranta. It grows both in the East and 
 West Indies, Brazil, &c. The better sam- 
 ples are used as food, the commoner in many 
 of the textile arts, as a dressing, Potatoe 
 starch has the same properties. 
 
 Arseniates. Salts of arsenic acid, with 
 the alkalies and metallic oxydes. 
 
 Arsenic. A brittle, whitish metal, very 
 fusible, and volatiHzed at 356° Fah., with a 
 smell like that of garlic. It is obtained from 
 numberless minerals, and is used for the 
 preparation of Scheele's green, realgar, and 
 orpiment ; to promote the ready fusion of 
 numerous metals ; and in the manufacture of 
 shot, in order to assist its better granulation. 
 Arsenic unites with oxygen, chlorine, hydro- 
 gen, sulphur, phosphorus, &c. 
 
 Arsenic Acid. A white powder, with 
 acid properties, consisting of 1 part metallic 
 arsenic, and 2^ oxygen. Soluble in 6 parts 
 of cold, and 2 of boiling water. Its solu- 
 tion tastes sour and metallic. It may be 
 procured by distilling nitric acid off metallic 
 arsenic. 
 
 Arsenical Soap. A preparation used to 
 anoint the skins of animals during the pro- 
 cess of preparing and stuffing them for the 
 museum. The composition of that of the 
 inventor, M. Becoeur, is as follows : — 
 Arsenic in powder .... 2 ounces. 
 
 Camphor 5 drams. 
 
 White Soap 2 ounces. 
 
 Salt of Tartar 12 drams. 
 
 Powdered Lime 4 drams. 
 
 Arsenious Acid. White arsenic. White 
 oxyde of arsenic is composed of arsenic 
 1 part, oxygen 1 1 ; is barely soluble in water, 
 tasteless, and violently poisonous. It may 
 be procured by sublimation from the metal. 
 
 Arsenio-sulphurets. Compounds Oi 
 the arsenical sulphurets with the alkaline 
 sulphurets, divided into arsenic proto-sul- 
 phurets, or such as have the proto-sulphuret 
 of arsenic, (realgar,) in their composition. 
 Arsenic sesqui-sulphurets, containing orpi- 
 ment or sesqui-sulphuret of arsenic, and ar- 
 senio-persulphate, containing the per-sul- 
 phuret of arsenic. 
 
 Arsenites. Compounds of arsenious acid 
 and various bases. The chief arsenite used 
 in the arts is Scheele's green, which is an 
 arsenite of copper, procured by precipitation 
 from the sulphate of copper. 
 
 Arseniurets. Combinations of arsenic 
 with metallic and other bases. 
 
 Arseniuretted Hydrogen Gas. A 
 fetid gas, sparingly absorbed by water, and not 
 capable of supporting combustion, therefore 
 poisonous. It is decomposed by most of 
 the metallic oxydes and salts, by nitric acid, 
 and by phosphorus, sulphur, &c., at a high 
 temperature. It may be procured by boiling 
 muriatic acid on an alloy of equal weights 
 of arsenic and zinc ; or one of 3 parts tin, 
 and 1 arsenic. 
 
 Art. a process dependent either upon 
 genius, taste, or manual dexterity. Accord- 
 ing as one or other of these is most requi- 
 site, so the process belongs to one of the 
 three principal division of art, the fine, the 
 ornamental, and the mechanical. These 
 two last sections are often combined under 
 the general denomination of the useful arts. 
 Logic, rhetoric, oratory, geometry, &c., 
 have been styled the liberal arts. The pro- 
 cesses used in the preparation of food, and 
 for the comfort of a household are called 
 the domestic arts. The manufactures de- 
 pendent upon chemistry are cailled the 
 chemical arts, while numerous others cannot 
 conveniently be classed with either of the 
 above, except the useful, nor yet with each 
 other, as the art of gardening, &c. 
 
 Artesian Wells. A name given by the 
 French, and extensively adopted here, to 
 such artificial fountains as are made by 
 boring the earth, and allowing the water to 
 rise. 
 
 Arthanatine. a crystalline matter, ob- 
 tained by alcohol from cyclamen roots. 
 
 Artificial. Any thing made by art. The 
 term is generally applied to such objects as 
 are intended to represent others which are 
 natural. Thus we speak of artificial flowers, 
 fruit, crystals, &c. ; or it may signify a spu- 
 rious imitation of a superior-manufactured 
 article, or a weak attempt at superior ex- 
 cellence in mind, style, &c. as is exemplified 
 in such expi'essions as artificial gold, artificial 
 manners, &c. 
 
 Artificial Globe. (See Globe.) 
 
 Artificial Magnets. (See Magnets.') 
 
 Artificial Couwebs. Exceedingly fine 
 
AS 
 
 AS 
 
 threads, made of Indian rubber by drawing 
 out its solution, (obtained by turpentine,) as 
 line as possible. The reason of the name is, 
 because these threads are used instead of 
 spider's webs for micrometers. 
 
 Arundelian Marbles. Ancient mar- 
 bles, illustrative of the mythology and his- 
 tory of the ancients, so called from the Earl 
 of Arundel, by whom they were obtained 
 from the Isle of Pharos. In 1667 they were 
 presented to the University of Oxford by 
 his grandson. They contain a chronicle of 
 the city of Athens, supposed to have been 
 inscribed thereon 264 years before Christ. 
 
 A SARIN. A principle extracted from the 
 asarum europoeum, or assarabacea. 
 
 Asbestos. A fibrous flexible mineral, in- 
 destructible in the fire, of which there are 
 five varieties. Amianthus, which occurs in 
 soft, white, long, and silky filaments, from 
 which the ancients made cloths, in which 
 bodies for the funeral pile were wrapped ; 
 also, dresses have lately been made of it, for 
 the use of firemen in entering burning 
 houses, &c. Common asbestos is inferior to, 
 but resembles the above, except in being less 
 flexible, and twice as heavy. Mountain 
 leather, consists of fibres so intermixed as 
 to resemble leather ; when in very thin pieces 
 it is called mountain paper. Mountain cork, 
 or elastic asbestos, is like the last, but less 
 compact : it swims on water. Mountain 
 wood, ligniform asbestos, differs in no 
 degree from the preceding, except in being 
 harder, of a bronze color, and having the 
 aspect of wood. 
 
 Ascending. In astronomy, is said of such 
 stars as are rising above the horizon in any 
 parallel of the equator. 
 
 Ascending Latitude. The latitude of 
 
 a planet when going towards the north pole. 
 
 Ascending Node. That point of a 
 
 planet's orbit wherein it passes the ecliptic 
 
 to proceed northwards. 
 
 Ascension. In astronomy, is either n'^A^ 
 or oblique. Right ascension, as of a star, is 
 that degree of the equator, reckoning from 
 the beginning of Aries, which comes to the 
 meridian with the star. The oblique ascen- 
 sion is that degree of the equator, reckoning 
 as before, which rises with the star. By the 
 right ascension and declination we are enabled 
 to find the position of stars in the heavens ; 
 in the same manner as places on the earth 
 are found, by noticing their latitude and 
 longitude. 
 
 Ascensional Difference. The diffe- 
 rence between the oblique and right ascension 
 in any point of the heavens. 
 
 Ash. The wood of the fraxinus excelsior, 
 or ash tree, valuable for its toughness, 
 strength, elasticity, and straight grain, while 
 kept dry for its durability, therefore much 
 used for wheel-work, carriages, agricultural | 
 
 implements, and the handles of tools. The 
 young wood is equally valuable with the old. 
 Ashes. The incombustible whitish pow- 
 dery material remaining after the burning oi 
 organic matter, and also certain mineral sub- 
 stances. The ashes of vegetable substances 
 are mostly impregnated with alkali ; that 
 produced by the burning of sea plants being 
 impregnated with soda ; that from terrestrial 
 vegetables with potass, in both instances 
 combined with carbonic acid and much 
 earthy matter. Coals, bitumen, &c. are 
 void of these alkalies, but yield ammonia 
 and other products, during their distillation, 
 and leave an earthy slag, which still more 
 burnt changes into an inert grey ash. The 
 ashes of animal remains, particularly those 
 from bones, are totally different in their 
 nature, composed chiefly of phosphoric acid 
 and lime, in the combined state of phosphate 
 of lime. 
 
 Ashlar. Hewn stone, used for the facings 
 of walls ; when smoothed, it is called plane 
 ashlar ; when wrought into regular flutes, it 
 is tooled ashlar; when cut without regularity, 
 it is s£iid to be random tooled; when wrought 
 with a narrow tool, it is called chiselled or 
 boasted: and when with a tool still narrower, 
 it is said to be pointed ; when the grooves 
 are sunk by cutting the arrises off the stones, 
 the work is said to be rusticated; and when 
 pitted into deep holes, it is called prison 
 rustic. 
 
 Ash-Hole. The receptacle for the ashes 
 of a furnace. 
 
 Ashlering. Setting an ashlar facing; 
 or by carpenters, it is the fixing of upright 
 quarterings between the rafters and floors of 
 garrets, in order to make more convenient 
 rooms, by cutting off the acute angles at the 
 bottom. 
 
 AsPARAGiN. A vegetable principle, dis- 
 covered in the juice of asparagus, the mallow, 
 and other plants. When the juice of these 
 is concentrated by evaporation, crystals 
 spontaneously separate. This substance ap- 
 pears to consist of hydrogen, oxygen, carbon, 
 and nitrogen, but contains neither earth nor 
 alkali. It is white, transparent, slightly 
 nauseous and cool to the taste, and soluble 
 in water. 
 
 AsPARTic Acid. An acid procured from 
 asparagin. 
 
 Asphalte. A bituminous stone, found 
 in many parts of the continent, particularly 
 Germany and Prussia ; much used by the 
 ancients as a cement in building, and lately 
 employed by us instead of paving, and for 
 covering roofs, &c. It is prepared for use 
 thus : — 94 parts by weight of the asphaltic 
 stone pulverized, are mixed with 6 parts of 
 bitumen or tar, and melted down ; when 
 melted it is merely poured upon the part 
 prepared to receive it, and scraped and 
 
AS 
 
 AS 
 
 beaten smooth while in a hot state ; for 
 pavements fine river sand is mixed with it. 
 
 AsPHALTic Mastic. The same as 
 asphalte. 
 
 AsPHALTUM, called also mineral pitch, 
 Jew's pitch, and bitumen. A hard, shining, 
 pitch-like substance, found in Judea, 
 America, China, &c. Anciently employed 
 in embalming dead bodies, and instead of 
 mortar in building ; now used in numerous 
 black varnishes, and engravers' etching 
 ground, &c. &c. 
 
 Asphyxiating Gases. Such gases as 
 are hurtful when inhaled, not because they 
 themselves contain a poisonous principle, 
 but because they are not oxygen. They are 
 nitrogen, hydrogen, carbonic oxyde, prot- 
 oxyde of nitrogen, &c. 
 
 AssA FcETiDA. The inspissated juice of 
 an umbelliferous plant, found in several 
 parts of Asia. It is of a most powerful and 
 foetid scent, and is used in medicine. 
 
 Assay, or Assaying. A chemical analy- 
 sis to ascertain the quantity of gold and sil- 
 ver in a metallic mass. In its more extended 
 meaning it is used for the determination of 
 the quantity of any metal whatever, in com- 
 position with any other metal, or mineral. 
 
 Assay Balance. An extremely delicate 
 oalance, employed for determining with great 
 precision the weight of minute bodies. It 
 differs in external form in no respect from 
 the common scales ; but in order to ensure 
 the greatest possible delicacy, the beam is 
 made very light, and supported at the centre 
 upon a sharp edge of steel, with a piece of 
 agate let into the beam for it to rest upon. 
 The scales are also supported upon two steel 
 edges, one crossing the other at right angles, 
 so that there is the least possible friction. 
 Some balances have been constructed of such 
 delicacy, as to turn with a millionth part of 
 the weight they were leaded with. 
 
 AsSER. An old word for a thin rafter, 
 board, or lath of wood, used for the roof of 
 a building. 
 
 Astatic. Without polarity. The term is 
 applied to a magnetic needle, when so con- 
 structed as not to turn to the pole of the 
 earth. It consists of two magnets united to 
 each other, so that the north pole of one 
 shall be opposite or near to the south pole 
 of the other, while the natural polarity of 
 one is counteracted by that of the other, and 
 the compound needle therefore is void of 
 spontaneous direction — a circumstance of 
 the utmost consequence in electro-magnetic 
 experiments. 
 
 Asteroids. The last discovered and small 
 planets, Ceres, Juno, Pallas, and Vesta. 
 
 Astragal. A small round fillet or mould- 
 ing, encircling a column. In the more or- 
 namented orders it forms the hypertrache- 
 lium ; that is, the upper part of all, between 
 the shaft and the capital. The same name 
 applies to the semi-circular moulding, some- 
 times cut into beads and berries, that sepa- 
 rates the different faces of an architrave. 
 
 Astringent. Any substance possessed 
 of a peculiar, rough, austere taste, such as 
 oak bark, willow bark, nut galls, new port 
 wine, many unripe fruits, &c. The com- 
 moner astringents are used in the art of 
 tanning, and therefore their active principle 
 is called tannin. 
 
 Astringent Principle. Another name 
 for tannin. 
 
 Astro GNOSY. The science which teaches 
 the constellations, ranks, .&c., of the stars. 
 
 AsTROLARB. Au ancicnt astronomical in 
 strument, used for taking the angle of alti- 
 tude, and position of the stars, and equally 
 applicable to take angles generally. The 
 following was its form : 
 
 -»■ 
 
 Astrology. An art which pretends to 
 foretell future events, especially the fate of 
 man, from the aspect of the stars at the 
 period of his birth. 
 
 Astronomy. The science which explains 
 the form, size, position, and motions of the 
 heavenly bodies, and their mutual influences 
 and disturbances. It is a science essentially 
 of observation and rigid mathematical cal- 
 culation. (See Heavenly Bodies, Solar Sys- 
 tem, Planet, Star, Comet, 8fc.) 
 
 Astronomical Horizon. (SeeHorizon.) 
 
 Astronomical Telescope. Forms a 
 part of most astronomical observatory instru- 
 ments ; to obtain one of the highest degree 
 
AS 
 
 AS 
 
 of perfection is of the greatest importance. 
 Astronomical telescopes are made upon dif- 
 ferent principles, as is explained under the 
 words Telescope, Amici, Newton, &^c. 8fc. 
 In the usual instruments the lenses are ac- 
 cording to the following arrangement : — 
 
 A B represents the object glass, which is 
 a double convex lens, placed at the larger 
 end of the telescope tube or case ; D E the 
 eye-glass, which is also a double-convex 
 lens, placed at the smaller end of the tube ; 
 (in the best instruments, instead of each of 
 these glasses are two lenses, that the chromatic 
 aberration may be corrected.) The rays of 
 light from the distant star or planet strikes 
 the object glass. The rays, before parallel, 
 are refracted to a focus in C. From this point 
 they again diverge till they strike the lens 
 D E, when they agam become parallel, and 
 in this state enter the eye. Owing to there 
 being but two glasses, every object will ap- 
 pear to the eye inverted, for the ray of light 
 from the top of the object strikes the object 
 lens at A, and proceeding onwards arrives 
 at the eye-piece at E — the lower portion of 
 it. This is of no consequence in viewing 
 the celestial bodies. Common astronomical 
 telescopes usually magnify from 70 to 100 
 times ; the better instruments sometimes as 
 much as 3 or 400 times. There is always a 
 very great difference in size between the object 
 and eye glasses of an astronomical telescope, in 
 order that the former may take in as large a 
 field of view as possible, and with it absorb 
 a proportionate quantity of light, which 
 being gradually condensed, comes to the eye 
 in a very concentrated state, so as to show 
 the object with considerable brilliancy. 
 Astronomical Symbols are as follows : 
 Siffns of the Zodiac. 
 
 T Aries. £2= Libra. 
 
 b Taurus. rn. Scorpio. 
 
 n Gemini. f Sagittarius. 
 
 25 Cancer. Vf Capricornus. 
 
 Q, Leo. ^ Aquarius. 
 
 m Virgo. 
 
 ^ Pisces. 
 
 The Heavenly Bodies, 8fc. 
 
 The Sun. 
 
 ^ Mars. 
 
 O Moon. 
 
 If. Jupiter. 
 
 O New Moon 
 
 Tl Saturn. 
 
 }) First Quarter. 
 
 y Herschel. 
 
 # Full Moon. 
 
 ^ Ceres. 
 
 ( Last QuartePw 
 
 ^ P^^^s. 
 
 5 Mercury. 
 
 "1" Juno. 
 
 $ Venus. 
 
 g Vesta. 
 
 ® The Earth. 
 
 ^ A Star. 
 
 Si The Dragon's Head, or Ascending Node. 
 a The Dragon's Tail, or Descending Node. 
 d Conjunction. ^ Opposition. 
 A Trine. Q Quadril. -Jf Sextil. 
 
 Astronomical Day, begins at twelve 
 o'clock at noon, and counts twenty-four 
 hours round. It is twelve hours later than 
 the civil day. Thus the first twelve hours o» 
 the astronomical 1st of January, would 
 agree with the hours from noon to midnight 
 of the same common day; while twelve 
 o'clock in the morning of our January 2nd 
 would make up the rest of the astronomical 
 day, and would be called 13 o'clock, or 13 
 hours, 14 hours, and so on to noon again. 
 
 Astroscope. An ancient astronomical in- 
 strument, consisting of two cones, upon 
 which the constellations were depicted, in the 
 same manner as they are now upon the ce- 
 lestial globe. 
 
 Asymptotes. (See Hyperbola.) 
 
 Athanor. An ancient alchemical furnace, 
 adapted to supply itself with the requisite 
 quantity of fuel for a long period. It 
 differed from modern contrivances only, in 
 having a pipe above the fire filled with 
 charcoal, which fell down as the fire made 
 room for it. The top of the tube being 
 closed, the fuel did not ignite till wanted. 
 
 Atlantes, or Persians. Male figures 
 used in the place of columns, to support 
 entablatures, &c. The female figures are 
 called caryatides. 
 
 Atmometer. An instrument invented by 
 Professor Leslie, to ascertain the exhalation 
 of a given vaporable substance in a given 
 time. It consists of a hollow ball of porous 
 earthenware, 2 or 3 inches in circumference, 
 with a small neck, into which is cemented a 
 graduated glass tube, closed at the top with 
 a brass screw ; this instrument is filled with 
 water or other liquid, the cap screwed on 
 tight, and then the whole hung in the sun 
 or air; according to the shiking of the 
 water in the graduated tube, so is the 
 evaporation to be allowed for. 
 
 Atmosphere. The sphere of air which 
 surrounds the earth. Its height, taken as 
 that where light ceases to be reflected, is 
 understood to be between 40 and 50 miles. 
 Its weight and pressure are dependent upon 
 its altitude above the surface ; decreasing 
 upwards, on the surface of the earth it is, at 
 an average, 15 pounds to the square inch, 
 and as fluids press equally in all directions, 
 according to their heights, the same pressure 
 is exerted on every inch of the surface of 
 every body on the globe to which the atmo- 
 sphere has access. As it is supposed that 
 the sun, moon, &c. are equally surrounded, 
 we speak of the sun's atmosphere, the 
 moon's atmosphere, and so on. 
 
 Atmospheres, One, Two, S(c. The elas- 
 ticity of air increases with its condensation, 
 
AT 
 
 AT 
 
 and the ordinary pressure being 15 pounds 
 on the square inch. A condensation which 
 produces a pressure of 30 pounds on the 
 inch is termed two atmospheres ; that which 
 gives a pressure of 45 pounds, three at- 
 mospheres, and so on. Pressures arising 
 from other causes, such as the weight of 
 liquids and the force of steam are counted by 
 atmospheres. 
 
 Atmosphere, Electrical. The air 
 around any body which is electrified, and 
 which, therefore, becomes itself electrical, 
 and capable of electrizing all bodies which 
 come within its sphere. 
 
 Atmospheric Electricity. That part of 
 science which ti-eats of the electrical appear- 
 ances visible in the atmosphere, such as 
 lightning, the aurora borealis, &c. ; and also 
 which teaches the means of guarding against 
 accidents arising from such phenomena. 
 
 Atmospheric Engine. Any engine may 
 be so called whose motive power is derived 
 from the pressure of the atmosphere ; but 
 the term is chiefly applied to the steam 
 engine invented by Newcomen in 1/05. The 
 construction of which will be understood by 
 the following engraving and description : — 
 
 A is a boiler ; B, a clack valve, as a safety 
 valve ; C, the cylinder, which has an open 
 top, and three holes at bottom D E F; 
 F admits the steam from the boiler through 
 the cock K ; D admits the cold v/ater to 
 condense with, and which passes from the 
 cistern G, through the pipe and cock N. 
 The hole E is connected with a long pipe, 
 which conveys away the waste water and 
 condensed steam ; H is a piston fitting 
 tightly into the cylinder ; I the beam, con- 
 nected at one side with the piston rod, and 
 at the other with the pump rod, which bears 
 
 upon it a weight L,to counterpoise the weight 
 of the piston on the other side, and to assist 
 in raising it at each stroke to the top of the 
 cylinder. 
 
 The action is this : — a boy was employed 
 to pull and push alternately at the handle O ; 
 this works the two cocks N and K, shutting 
 one at the same time that it opens the other ; 
 suppose then K to be open, the steam would 
 rush through and fill the cylinder, and drive 
 up the piston, when this is full, the boy 
 pushed the handle forwards, shutting off the 
 steam and admitting a jet of cold water, 
 which condensed the steam before admitted, 
 allowing the pressure of the atmosphere to 
 drive down the piston which worked the 
 pump-rod at the other end of the beam. 
 This engine is still employed in many of the 
 mining districts for pumping water, a rod 
 from the beam working the cocks. The 
 waste of steam, and consequently the expen- 
 diture of fuel is, however, very great. 
 
 Atmospheric Tides. Certain periodic 
 changes in the air, such as trade winds, 
 monsoons, &c. &c. 
 
 Atoms. The ultimate, or least conceivable 
 principles into which a body may be divided, 
 or of which it may consist. 
 
 Atomic Theory, The, depends upon 
 the supposirton, that ail bodies are composed 
 of ultimate atoms, the weight of which is 
 different in different kinds of matter, 
 according to which view every compound is 
 formed by a combination of the atoms of its 
 constituents. If water, for example, is 
 composed of an atom of hydrogen and an 
 atom of oxygen, it follows, that eveiy other 
 combination of hydrogen with oxygen must 
 contain 2, 3, 4, or more atoms of oxygen ; 
 because as an atom is the least possible 
 portion of matter, it is impossible that there 
 can be any division of this portion. 
 
 Atomic Weights. Numbers intended to 
 represent the relative weights of atoms, so 
 as to show the exact constituents and relative 
 proportions of them in every substance, 
 whether simple or compound. As atoms are 
 too minute for the real weight of them to be 
 appreciated by balances, it is necessary to 
 take one substance, and assign a certain 
 value to it, and from this to calculate the 
 atomic weights of other bodies, judging 
 from their known effects of combination. 
 By one class of philosophers hydrogen fonns 
 the standard or unit, by others, oxygen is so 
 considered. (See Scale of Chemical Equi- 
 valents.) 
 
 Atrium. A hall or antichamber, usually 
 of a large size, being used as a place of 
 meeting, feasting, &c. ; also the principal 
 porch of a church was so called by the 
 writers of the middle ages. 
 
 Atropine. The basis of the atropa bella- 
 donna, or deadly night-shade. 
 
AT 
 
 AT 
 
 Attar of Roses. A concrete oil of as- 
 tonishing and delightful fragrance, made from 
 roses in India and Turkey. To produce 
 one rupee's weight, (not half an ounce,) of 
 attar, requires 200,000 full-blown roses. It 
 is, therefore, extravagantly dear, being sold 
 at the English warehouse in India at ^10 
 for the above weight. That fragrant mate- 
 rial sold here as attar is spermaceti scented 
 with about a thousandth part of attar. 
 
 Attenuation. A making thin, applied in 
 distillation and brewing. The specific gravity 
 of spirit is diminished at every distillation, 
 because of its impurities being removed ; it 
 is therefore said to be attenuated. Wort 
 also becomes lighter during fermentation, 
 because of the formation of a vinous spirit, 
 and the separation of carbonic acid gas. In 
 proportion to the perfect fermentation, thei-e- 
 fore, the whole mass will become attenuated, 
 
 Attic Base. A peculiar kind of base, 
 used by architects in the Ionic, and some- 
 times in the Roman Doric order. It consists 
 of an upper and lower torus or round mould- 
 ing ; a Scotia or hollow moulding ; and two 
 fillets or square mouldings between them. 
 The whole of them together being in height 
 one -third of the thickness of the column, and 
 projecting on each side one-quarter the thick- 
 ness of the column. This description of base 
 is so great a favorite, that the columns of most 
 modem .edifices are built upon it. 
 
 Attic. The upper story of a building, 
 whatever be its shape, is in ordinary lan- 
 guage an attic. In architecture, it implies 
 that the story is of the same height all along, 
 and with windows. If this part be decorated 
 with pilasters, it is said to be of the attic order. 
 
 Attitude. In painting and sculpture is the 
 posture in which a figure should be placed to 
 indicate the action intended to be represented. 
 
 Attraction. A tendency which certain 
 bodies have to approach and adhere to each 
 other without apparent cause. There are 
 several kinds of attraction, as of gravitation, 
 cohesion, capillary, chemical, electrical, and 
 magnetic. 
 
 Attraction of Cohesion, is that power 
 which causes the particles of bodies to unite 
 into a soUd mass. As small masses of lead 
 melted together become a uniform single 
 mass by this attraction. 
 
 Attrxctioh of Gravitation. The power 
 which communicates weight ; it tends to draw 
 all bodies to the earth, and the earth itself to 
 
 the sun. Also is the probable cause of the 
 roundness of the heavenly bodies, as it is of 
 drops of water, globules of mercury, &c. 
 
 Attraction, Chemical. The tendency of 
 certain bodies to become so intimately blended 
 with each other, as to lose their individual 
 character ; the nature of both bodies being 
 changed, and a compound formed from them, 
 different in its properties from either. Thus 
 potass and oil, chemically united, form soap, 
 which is a body without the greasiness of oil, 
 or the causticity of the potass. 
 
 Attraction, Capillary. The power that 
 fluids have of rising above their level in fine 
 tubes or pipes. It is by this attraction that , 
 water is sucked up in sugar, sponge, &c. 
 
 Attraction, Electrical. The tendency 
 which two bodies, when in different electrical 
 states, have of coalescing, until by union or 
 approach they have become in the same elec- 
 trical condition. 
 
 Attraction, Magnetic, is that seen when 
 a loadstone or an artificial magnet takes up 
 any particle of iron in its vicinity. 
 
 Attwood's Machine. An instrument for 
 ascertaining experimentally the laws relative 
 to falling bodies. 
 
 A B are two wheels, moving freely on their 
 centres ; these are called friction wheels, 
 because they bear upon>them one end of the 
 
AU 
 
 AU 
 
 axis of the third wheel C. The other end of 
 the axis of which is home by two other 
 wheels, similar in size and position to A and 
 B. The wheel C has a groove on its end, in 
 which the cord D passes. The cord D has 
 an equal weight at each end E and F. From 
 the upper stage of the machine proceeds to 
 its foot a scale of equal parts G, for the pur- 
 pose of measuring the velocity of descent. 
 Upon the scale are two sliding stages H and I. 
 H is solid ; I is a ring. L is a small bar of 
 metal, (weighing a quarter of an ounce,) and 
 K a clock, the pendulum of which beats 
 seconds. O is a weight, (weighing a quarter 
 of an ounce,) and of the same diameter as 
 the weight P, though here drawn larger for 
 the greater clearness. The weights E and F 
 should be equal, so that they may stand at 
 any point, without a tendency in either to 
 descend ; and so adjusted, that a quarter of 
 an ounce weight added to either, makes that 
 «ide descend through one space of the scale 
 in the first second of time. The following 
 experiments will show the nature of the 
 machine. Screw the stage H at No. 25 of 
 the scale ; draw the weight F up to the top 
 of the scale, and load it with the quarter of 
 an ounce weight. Then let it fall exactJy at 
 the moment the pendulum is at one extremity 
 of its beat. Mark the beats of the pendu- 
 lum, and it will be found that at the end of 
 the first second, the weight A will have passed 
 over the first space ; at the end of the second 
 beat, it will have arrived at No. 4 of the 
 scale ; at the third second at No. 9 ; at the 
 fourth second at No. 16 ; and at the termi- 
 nation of the fifth beat the weight will strike 
 the stage H, or have passed through twenty- 
 five spaces in five seconds, the space passed 
 over being the square of the times. If in- 
 stead of the weight O, the bar of metal J 
 were used, it would be left on the ring at 
 any part of the course previously determined 
 upon, and the weight F proceed only in con- 
 sequence of the velocity it had acquired; 
 this velocity or momentum may, in like 
 manner, be measured. 
 
 Attributes. Such symbols given to 
 statues as indicate their character ; as a club 
 is given to Hercules ; a trident to Neptune ; 
 a thunder-bolt to Jupiter, &c. 
 
 Auger. An instrument for boring large 
 and deep holes, used by shipwrights, carpen- 
 ters, &c. There are three varieties of augers. 
 First, the old English auger, which has a 
 cutting part at the end, and straight cutting 
 sides. Second, the gimlet auger, which 
 having a screw point, like a gimlet, forces 
 itself into the wood, and suffers the sides to 
 cut away the wood. Third, the American 
 or screw auger, which has a point like a cen- 
 tre bit, and with a shank screw form, which 
 allows the chips to escape, and assists in 
 penetrating the wood to be bored. 
 
 AuRATES. Combinations of auric acid 
 and alkalies. 
 
 Auric Acid. A term proposed by M. 
 Pelletier for peroxyde of gold, because it 
 combines vnth alkaline bases. 
 
 Auro-Chlorides. These are haloid salts, 
 formed by the terchloride of gold, with me 
 tallic and other bases. Such are the auro- 
 chlorides of hydrogen, potassium, sodium, &c. 
 
 Aurora Australis. The same pheno- 
 menon as the aurora borealis, but seen 
 towards the south pole. 
 
 Aurora Borealis, or Northern 
 Lights. Flashes of electrical light, which 
 appear at certain seasons and places, passing 
 across the atmosphere, particularly from a 
 point near the zenith towards the horizon. 
 In hot countries they are rarely or never 
 visible, and even in this country the aurora 
 is seldom seen, but in the Shetland islands, 
 where such lights are of frequent occurrence ; 
 and where they are called * 'the merry dancers, ' ' 
 and in places still more northward, as in Lap- 
 land, Norway, Labrador, and Spitzbergen, 
 they occur so constantly, and so brilliantly, 
 that they much enlighten and enliven the long 
 nights of the polar winter. 
 
 Aurora Flask. An electrical apparatus, 
 contrived to show experimentally that the 
 aurora borealis is anelectrical phenomenon. 
 There are two shapes given to the instrument, 
 as represented below : 
 
 No. 1 is called the aurora tube ; it con- 
 sists of a large cylindrical tube of glass, 
 2 feet or more long, with a brass cap, 
 soldered on air-tightly at top, over the tube, 
 the brass cap having a tapering pointed 
 wire projecting about 2 inches into the glass ; 
 on the foot is also a brass cap, which has 
 a ball inside, and on the outside a screw 
 which fits a condensing syringe, or air-pump, 
 that the air may be partly exhausted from it, 
 the syringe being afterwards removed, the 
 screw unites the fabe to a small wooden foot. 
 
AV 
 
 AX 
 
 to enable the whole to stand upon a table. 
 When the upper cap is held so as to take a 
 spark from the conductor of an electrical 
 machine, the spark will pass through the 
 partly exhausted tube in quivering and 
 uncertain flashes, resembling, in miniature, 
 the aurora borealis. The other instrument, 
 marked No. 2, is commonly called the small 
 aurora flask. It is a glass vessel with a brass 
 cap, exactly similar to the last, with a point 
 inside, the glass being without a foot, but 
 with a small perforation below, and is to 
 be held in the hand when used. The use of 
 the perforation is, that the fluid may pass 
 away, otherwise it would become accumu- 
 lated v^ithin, and a shock be, probably, the 
 consequence. That it may pass away more 
 readily, the lower part, where it is taken 
 hold of, is covered with tin foil. As the 
 perforation prevents a direct exhaustion of 
 the air within, the flask should be put quite 
 close to the fire for some minutes before use, 
 the rarefaction of the air which will take 
 place will be sufficient. 
 
 AuRUM MusivuM, or Mosaicum. Sul- 
 phuret of tin. This is said to be the sub- 
 stance made by the alchemists and imposed 
 upon the credulous as gold, which it much 
 resembles. It is a powder, used chiefly by 
 the japanners of common tea boards, and by 
 the ItaHans to give the appearance of bronze 
 to their plaster images, after painting them. 
 
 Autograph. An original piece of writing, 
 whether it be a continued manuscript, or 
 merely a signature. 
 
 Automatic. A word used by Dr. Ure to 
 designate those processes which are carried 
 on by machinery alone. 
 
 Automaton. Any self-acting piece of 
 machinery, but chiefly applied to such as are 
 made to imitate living motions and sounds. 
 Automatic spiders, mice, and singing birds, 
 of Swiss manufacture, are not uncommon. 
 
 Autumnal Signs of the Zodiac. The 
 signs libra, Scorpio, and Sagittarius, through 
 which the sun passes during the autumn. 
 
 Avenaine. a chemical principle, dis- 
 covered by Hermbstradt in oats. 
 
 Averruncator. A pru- 
 ning instrument, consisting 
 of two blades, acting like 
 scissars ; one blade is fixed 
 to a rod, and the instrument 
 is worked by means of a 
 string fixed to the other 
 blade, and to be pulled by 
 the operator. 
 
 Aviary. A building appropriated to the 
 keeping of birds, sufficiently large to allow 
 them scope for flight 
 
 Avoirdupois. A series of weights, used 
 for weighing coarse and heavy goods, such as 
 the common metals ; the necessaries of life ; 
 and numerous articles, used in manufactures, 
 
 such as cotton, silk, pitch, ivory, &c. &c. 
 In this weight 16 drams, (dr.,) make an 
 ounce, 16 ounces, (oz.,) a pound, 112 pounds, 
 (lbs.,) 1 hundredweight, 20 hundred weights, 
 (cwts.,) 1 ton. Besides numerous weights, 
 used for particular goods, such as the clove, 
 stone, wey, fother, &c., which are combiw 
 nations of the regular proportions above 
 indicated. 
 
 Axe. a heavy steeled instrument, em- 
 ployed in chopping, having its cutting edge 
 parallel with the handle. 
 
 Axiom. A self-evident truth, or one which 
 neither admits of, nor requires a proof ; for 
 example, the whole of any thing is greater 
 than a part of it. 
 
 Axis in Peritrochio. One of the me- 
 chanical powers, commonly called the wheel 
 and axle. It is a modification of the lever, 
 and its power is calculated in the same 
 manner. 
 
 In the cut it is supposed to be turned 
 round by the spokes upon its circumference, 
 but sometimes, as in the instance of the 
 crane and drawwell, a winch or handle is 
 substituted. The power of such an appara- 
 tus is in proportion to the difference in 
 diameter between the wheel which bears the 
 smaller weight, and the axle which supports 
 the other weight. 
 
 Axis. In geometry, a straight line drawn 
 from the apex of the figure to the centre of 
 its base, as of a cone, a triangle, &c. In a 
 cylinder it is the line which connects the 
 centres of the ends. In a globe or circle it 
 is any diameter. In an ellipse and hyper- 
 bola are two axes — the transverse axis is. 
 the diameter passing through the two foci ; 
 in the hyperbola it is, therefore, the short- 
 est diann ter, in the ellipse the longest; a 
 diameter perpendicular to the centre of this 
 is the conjugate axis. In astronomy an axis 
 is an imaginary line, about which any of the 
 heavenly bodies revolve. In mecha ics it 
 also indicates the line of motion, sometimes 
 
AZ 
 
 AZ 
 
 iinagjinary and changeable ; at others, fixed 
 and certain. Axis is applied particularly to 
 bars, round which wheels rotate. In mag- 
 netism it is the line which connects the poles 
 of a magnet, without passing out of it. 
 
 Axis of Oscillation. The shaft upon 
 which any body vibrates. 
 
 Axis of Refraction. (See Refraction.) 
 
 AxLETREE. The centre upon which a car- 
 riage wheel turns. Axletrees are of two 
 kinds ; one in which the wheels and axle are 
 fixed to each other, so as to turn together, 
 the axle revolving in bearings attached to the 
 carriage, by which the nave is less weakened, 
 and the wheels have less play ; for which 
 reason such axles are now much used for 
 railway carriages, though as both wheels 
 move with equal speed, they are inconvenient 
 for turning sharp angles. The second method 
 is, that the axle is fixed to the carriage, and 
 the wheels turn round upon it, independently 
 of each other, by which means, in turning 
 short, the inner wheel can remain stationary, 
 and serve as a centre of motion to the 
 carriage. 
 
 Azote. (See Nitrogen.) 
 
 AzoTizED. Bodies containing mueh azote. 
 
 Azimuth. In astronomy, the position of 
 either of the heavenly bodies, when above 
 the horizon, with respect to an observer, 
 reckoned in the points of the compass ; 
 thus, if a ate be seen so many degrees east 
 or west of toc meridian of an observer, it 
 would be said to have so many degrees of 
 azimuth. If on the horizon it is called 
 amplitude. 
 
 Azimuth, Magnetic. That position of a 
 star, &c., indicated by the compass. It dif- 
 fers from the true azimuth, according to the 
 variation of the compass at the place where 
 the obsei-vation is made. 
 
 Azimuth Circle. On a globe, a circle 
 of degrees and minutes depicted on the 
 wooden horizon of an artificial globe, whereby 
 to ascertain the azimuth of any celestial 
 body. A circle of the same description, 
 name, and uses, is often attached to a quad- 
 rant and sextant. 
 
 Azimuth and Amplitude Circle. Dr. 
 Brewster observes, " that this instrument is 
 in itself, with the assistance of a good clock, 
 a complete astronomical apparatus, as by it 
 the astronomer is enabled to make all kinds 
 of observations. He can ascertain right 
 ascensions, transits, azimuths, and ampU- 
 tudes ; the latitude of his observatory ; and 
 the position of a star in any part of the 
 heavens ; it is also, w^hen made portable, an 
 excellent surveying instrument." 
 
 It consists of a strong, upright stem, F, 
 which fits into, and moves freely, yet accu- 
 rately, in a socket at the foot, bearing round 
 with it, on the lower part, a brass horizontal 
 circle G G, graduated into degrees, mhiutes, 
 
 and seconds. By this the telescope of the 
 instrument is directed to any point of the 
 heavens, and the point being ascertained, the 
 degree marked off is read by the eye-glass at 
 
 H. The upper part of the instrument con- 
 sists of an astronomical telescope, marked A, 
 which is fixed to a vertical circle B, graduated 
 like the former in degrees, minutes, and se- 
 conds-. This circle has a counterpart on the 
 other side of the telescope, (though this last 
 need not be graduated ;) and there are six 
 or more spokes, connecting each circle with 
 a central axis, which is supported upon the 
 upright stand. This being cut away in the 
 middle, to allow the telescope freedom of 
 motion in a vertical position. C C are two 
 sights or reading glasses, to read ofi" the de- 
 grees, which when the telescope is fixed is 
 visible beneath them, or one of them. The 
 reading glasses are connected with the arm 
 D, which is fixed to F. E is a spirit level, 
 to ensure accuracy of level, or horizontal 
 position of the whole instrument, which it 
 is evident must at all times be carefully 
 attended to. 
 
 Azimuth Compass. Differs from the 
 common magnetic compass, in having two 
 sights attached to the upper rim, and in the 
 whole instrument being so suspended as to 
 be capable of being moved in every manner, 
 both vertically round an axis, as well as ho- 
 rizontally ; vertically, in order that the sights 
 may be directed to any part of the horizon i 
 
BA 
 
 BA 
 
 and horizontally, that it may accommodate 
 itself to the motion of the ship in which it 
 may be used ; and also that the upper sur- 
 face may remain parallel at alL times with 
 the horizon. 
 
 A is a brass semi-circular arm, which turns 
 round on a pin below. B is a gimbal or 
 ring of metal, supported upon the two pivots 
 G G. At right angles to these pivots are 
 two others, tearing the compass box, one of 
 
 which is seen at H. E and F are the two 
 sights, through which the distant object, 
 whose azimuth is to be taken, is viewed, 
 A line from the slit of one of the sights E, 
 continues down to the compass card, and which 
 is graduated around the edge, indicating the 
 number of degrees required. It is to be 
 observed, that the compass card, from its 
 being attached to the magnetic needle, keeps 
 one certain position, N and S, (allowing 
 for the variation,) while the box itself is 
 moved round according to circumstances. 
 
 Azure. The blue color of the sky ; also, 
 the peculiar blue pigment used by the ancient 
 Egyptians, and which has preserved its bril- 
 liancy of tint for nearly 2000 years. Sir H. 
 Davy says it may be imitated by keeping at 
 a red heat for two hours, 15 parts of carbo- 
 nate of soda, 20 of calcined powdered flints, 
 and 3 of copper filings. Smalt is also called 
 azure. (See Smalt.) 
 
 Azure Stone. (See Lapis Lazuli.) 
 AzuLMic Acid. A new acid, found in 
 the black matter deposited during the de- 
 composition of hydrocyanic acid. 
 
 The second letter and first 
 consonant in all languages, 
 except the Ethiopic, where 
 it is the ninth. It is a mute 
 and a labial letter, that is, 
 one pronounced by the aid 
 . of the lips. Its sound varies 
 between the sounds of F, V, 
 and P,with which letters it is 
 occasionally interchanged in translating from 
 one language to another, and even sometimes 
 in the same language ; as, for example, in 
 the Spanish. The form given to it now 
 varies but little from that of long distant 
 ages, as may be seen in the ancient Greek 
 inscriptions. ' In music B is the name of the 
 seventh note of the diatonic or ordinary 
 scale ; it has no sharp semitone. In con- 
 tractions it stands for bachelor, Brutus, 
 beatus, &c. 
 
 Babbage's Revolving Plate. This 
 magnetic apparatus is the reverse of that in- 
 vented by Arago ; its object being to show 
 that plates of sundry metals, besides iron, 
 are affected by a magnet, when that magnet 
 is put into a rapid rotation. 
 
 A is a powerful horse -shoe magnet, which 
 is capable of motion around its centre, the 
 poles being upwards as represented. B is a 
 plate of copper, zinc, or other metal, about 
 14 inches over, balanced by a central spindle 
 between the two arms of the upright sup- 
 port. "WTien the magnet is made to rotate 
 rapidly by means of the multiplying wheel C, 
 it so affects the metallic plate above as to 
 
 render it magnetic also, as is seen by the 
 rotation of the plate in the same direction as 
 that of the magnet ; the same being the case, 
 
 if either the magnet or the plate be shut up 
 in a box, or a sheet of glass made to interpose 
 between them. The effect, therefore, not 
 being attributable to any impulse of the air. 
 
 Babington's Galvanic Battery. An 
 instrument originally invented by Dr. Ba- 
 bington, to supersede the couronne des tasses, 
 and to which it is greatly superior, both in 
 convenience, in power, and in economy. 
 
 It consists of a many-celled trough of 
 earthenware, or as it was first made, of a 
 wooden trough, with glass divisions across it, 
 so as to form as many cells as there are 
 pairs of plates of metal. The plates repre- 
 sented over the trough are of two metale, 
 
BA 
 
 BA 
 
 zinc and copper, one placed alternately with 
 the other ; each pair soldered together at the 
 lop, and so arranged, as to distance, that 
 when placed in the trough, each cell shall 
 have within it the zinc plate belonging to 
 one pair, and the copper plate belonging to 
 the next pair, and so on threughout the 
 
 series. From the trough below arise two 
 arms to support the plates when not wanted 
 to be in action ; the plates being screwed on 
 to a long slip of baked wood, that they may 
 be all lifted and put down together, and that 
 quickly. 
 
 Bacchus. A pneumatic instrument, in- 
 tended to show the effect of the elasticity of 
 the air. 
 
 A figure is represented sitting across a 
 cask A, in which there are two separate 
 compartments, a portion of colored liquid 
 being placed in one B. When the apparatus 
 is under the exhausted receiver, the elastic 
 force of the confined air causes the liquid to 
 ascend a transparent glass tube, fitted into 
 the mouth of the bacchanalian figure, and 
 flowing still along the pipe, which is within- 
 side the figure, fills the other part of the 
 cask. When air is admitted into the re- 
 ceiver again, the liquid returns to the first 
 compartment, as at first. To render the 
 experiment still more striking, and indeed 
 more illustrative, a bladder, with a small 
 quantity of air in it, is fastened to the 
 figure, ai)d covered with the silk dress. The 
 air in the bladder expands, and produces an 
 
 apparent increase of bulk in the figure, as 
 occasioned by the excess of liquor drank. 
 
 Bachhoffner's Electro -Magnetic 
 Machine. This instrument is intended to 
 show, in a convenient manner, the effects of 
 galvanism when passing along an extended 
 conductor ; also, the effects of galvanic in- 
 duction on a second extended conductor, in 
 connection with the first. It unites in itself 
 the effects of Callan's coil, (which see ;) 
 and an apparatus for rapidly breaking and 
 restoring contact, with other additions, as 
 will be understood by the following figure 
 and description : — 
 
 A is a double coil of wire. One coil of 
 about 600 feet of No. 16 copper wire, co- 
 vered with silk or cotton. This is inside, 
 and is called the primary ; upon this is 
 wound in the same direction, but quite un- 
 connected with the first, a second coil of 
 2000 feet, (more or less,) of thinner copper 
 wire, (No. 22,) also covered with silk or 
 cotton. This is called the secondary coil. 
 There is a hole in the middle of all, holding 
 a bundle of iron wires tied together. The 
 ends of the inner coil are soldered to the 
 cups H, F, and I, The ends of the second 
 coil to J. and K. The battery, which need 
 not be more than a single jar, is to be con- 
 nected with H and I. D is a toothed wheel, 
 turned round by a small pulley at the back, 
 connected with the multiplying wheel C. 
 To use the machine, if a shock is required, 
 G and H must be connected together ; if 
 electro -chemical effects be wanted, connect 
 together J and K, and place the substance to 
 be decomposed between these cups. The 
 fluid enters I, passes along the primary coil, 
 and arrives at F, goes thence to E, (E F 
 being a brass pillar ;) along the spring at E 
 to the spurred wheel D. This being metal 
 
BA 
 
 BA 
 
 conveys it to G. Whatever is placed between 
 G and H receives the current. The wheel 
 D only touches E when its teetli come 
 against it ; therefore in one rotation of the 
 wheel there will be as many fresh contacts ; 
 also as many breaking of contacts as the 
 wheel has teeth, consequently there will be 
 felt as many shocks. 
 
 Bachhoffner's Voltameter is thus 
 constructed : — A is a glass globe or bottle,- 
 
 3 inches in diameter, having a perforated 
 foot, into which two wires pass, and which are 
 terminated by platina points, C, within the 
 ball, and at the cups on the stand without. 
 A has a cork to fit it, and a graduated glass 
 tube passing through the cork upwards into 
 the air, and downward into the globe. To 
 use the instrument, fill B completely with 
 water acidulated with acid, and partly fill A 
 also with water, and put B in its place, as 
 represented in the figure. Connect the bat- 
 tery with the cups, when the water will be 
 decomposed, and the gases arising from the 
 decomposition pass upwards into the gra- 
 duated tube, and displacing the water, indi- 
 cate the quantity produced by the battery, 
 which is the object of a voltameter to ascer- 
 tain. (See Voltameter.) 
 
 Back Boxes. The boxes on the top of 
 the upper case used for printer's types, 
 which are appropriated to small capitals in 
 Roman letter; but wnich in imperfect founts, 
 such as Italic, Old English, &o., are appro- 
 priated to irregular sorts. 
 
 Back of a Composing Stick. The part 
 on which the bottom of the type rests. 
 
 Back. In a form of book-work those 
 pieces of furniture are called backs, which 
 are placed between the sides of a page, and 
 the cross of the chase. 
 
 Backs. The principal rafters of a roof. 
 
 Backing. Preparing the back of a book 
 by glueing, and otherwise strengthening it, 
 so as to be ready to receive the cover. 
 
 Bachhoffner's Galvanometer. A. 
 very sensitive instrument, of easy construc- 
 tion. A represents a coil of thin wire, co- 
 vered with silk ; its two ends being connected 
 with the cups N and P. B is a double or 
 astatic magnet, suspended on a single fibre 
 of silk, hanging from a brass arm, C \ the 
 whole being covered with a glass receiver, 
 and standing on a wooden foot. The sus- 
 pended magnet indicates by its disturbance 
 the intensity of the current passed along 
 the coil. 
 
 Back Staff. An instrument formerly 
 used for taking the sun's altitude at sea, 
 being so called because the back of the ob- 
 server was turned towards the sun. This 
 instrument is also called Davis's quadrant, 
 from the inventor. It is now totally dis- 
 carded from use. 
 
 Backwater, or Scouring Power. The 
 stream of water employed to carry the filth 
 from the mouth of a harbour, where a great 
 quantity of water can be obtained at high 
 tides, large reservoirs being filled at those 
 times, the water is afterwards discharged on 
 the bar at low water, when it carries every 
 thing before it. 
 
 Badigeon. a preparation for coloring 
 houses. It is prepared with saw-dust, slaked 
 lime, the powder of the stone with which 
 the house is built, and a pound of alum, 
 dissolved in a bucket of water. A little 
 yellow ochre is sometimes added to it. 
 
 Badigeon. A mixture of plaster and free 
 stone, well sifted and ground together ; used 
 by statuaries to fill up the little holes, and 
 repair the defects in stones oS which their 
 work is made. The same term is also used 
 by joiners for a composition of saw dust and 
 strong glue, with which holes and chasms ia 
 wood-work may be filled. 
 
 Bailey. Bail. Bale. The open space 
 between one wall or line of fortification and 
 another. 
 
 Baking. The exposing any body to such 
 a degree of heat as will dry and consolidate 
 its parts without wasting them. Thus wood, 
 pottery, and porcelain, are baked, as v^ell us 
 bread. 
 
V 
 
 BA 
 
 BA 
 
 Balance. A lever, turning on a fulcrum 
 or pivot, constructed for the weighing of 
 bodies. The lever, or rod, is called the 
 beam , each end of it from the pivot out- 
 wards is called an arm. When these arms 
 are equal, it is the common balance or scales, 
 which are two dishes, hung on what are 
 called the points of suspension. 
 
 Balances are for various purposes, and are 
 made upon different constructions. (See 
 Brady^s, Bent Lever, Danish, Letter, Roman, 
 Steelyard, Hydrostatic, and oihex Balances.) 
 
 Balance Discharger. An electrical 
 instrument to regulate the discharging of 
 Leyden jars and electrical batteries, according 
 to the intensity of charge required. 
 
 A is a foot-board, supporting two glass 
 pillars, B and G. C is a brass ball and 
 socket, fitting upon B, and by a hook at- 
 tached to it holding the chain H. The ball 
 C bears at top a brass arm and ball F, which 
 are fixed immoveably to it. Upon an axis, 
 running through C, is supported the balance 
 D E, also of metal : in order that this balance 
 may play up and down, so that E shall be 
 able to reach and fall upon G, a slip or long 
 aperture is made on two opposite sides of C, 
 wide enough for the wire to pass readily. 
 There is also a chain attached to the socket 
 of G, marked I; and a small moving weight, 
 between C and E, to be slipped backwards 
 or forwards, as required. 
 
 To understand the manner of action of 
 this valuable discharger, it is to be remem- 
 bered, that bodies when electrified similarly 
 repel each other, in proportion to the degree 
 of their electrization. Now connect H with 
 the inner part of a battery, and I with the 
 
 outer, and see that the balance is loadei? a 
 little. The brass part of the balance con- 
 nected with H will become charged, and 
 when charged sufficiently to overcome the 
 balance weight, the ball E will be repelled 
 downwards, and fall to G ; as this is con- 
 nected with the outside of the battery, it will 
 be discharged by the contact of G and E. 
 In the above it is to be remarked, that while 
 repulsion goes on between F and E, attrac- 
 tion will arise between E and G, therefore 
 there is a double force to draw down E. 
 
 Balance Electrometer, is of many 
 forms and degrees of delicacy. The fol- 
 lowing is of easy construction, and adapted 
 to show, in a lecture or otherwise, the gene- 
 ral effects of electrical attraction and repul- 
 sion. It consists of a fine beam of metal or 
 wood, suspended on a pivot affixed to a glass 
 rod in the centre. It should be accurately 
 balanced, and have at each end a pith ball, 
 or piece of gilt paper. The glass rod must 
 be very dry when the instrument is to be 
 uSed; an excited stick of sealing wax or 
 glass held towards one end will occasion it 
 to move round its centre, and thus indicate 
 plainly the excitement of the wax, or glass. 
 
 For a much more delicate balance elec- 
 trometer, see Coulomb and Tortion. 
 
 Balance Gates. Flood gates, balanced 
 upon a central pin, or axis, to each, as re- 
 presented below ; the inner side of each 
 being rather larger than the outer side, the 
 pressure of the water keeps them close, 
 while a very small power is sufficient to turn 
 them when required for the passage of the 
 water. 
 
 Balance Thermometr, of Mr. Ke. ley, 
 is a contrivance for keeping up in a;)!irt- 
 ments, green-houses, &c., an exact nnd 
 even tempei'ature ; the instrument not 
 
BA 
 
 BA 
 
 merely indicating the temperature, but also 
 by the preponderance of one side over the 
 other, closing or else opening a window of 
 the apartment, or a damper of the fire-place. 
 It may be described as follows : — 
 
 A is a tube or glass, filled with spirits of 
 wine. It is closed at the end B, and opens 
 into a ball at the end C. This ball has 
 another tube connected with it, and opening 
 into it underneath. The second tube D E 
 runs parallel with the former, and terminates 
 at E with a second ball, open to the air by 
 a small orifice at top ; the tube itself con- 
 tains mercury. The whole arrangement of 
 tubes is balanced on a knife-edge between 
 the two upright supports. When a room in 
 which it is placed becomes warmer, the 
 spirit expands, and fills the ball C, driving 
 the mercury forward to E ; thereby making 
 the end E heavier, until it sinks, and either 
 pulls a string, or touches a lever, or an 
 alarum. To regulate the degree of tempe- 
 rature at which it shall turn over, a scale is 
 fixed on the side of the tubes, this being 
 ])ushed backwards or forwards alters the 
 first equilibrium, making either a greater or 
 less force capable of affecting it. 
 
 Balance Wheel of a Watch. That 
 which answers the purpose of the pendulum 
 to a clock, or which regulates the velocity of 
 the motion. It is seen vibrating backwards 
 and forwards when the watch is opened. The 
 better kinds of watches and chronometers 
 are furnished with a compensation balance. 
 (See Arnold.) 
 
 Balaon, or Balloon. A large ball placed 
 upon the top of a pier, pillar, or pediment, 
 as a terminating ornament. 
 
 Balcony. A projecting gallery m front 
 of a window, supported by brackets, con- 
 soles, pillars, &c. 
 
 Baldwin's Phosphorus. Ignited ni- 
 trate of lime. It may be made by melting 
 
 some nitrate of lime in a crucible, and keep- 
 ing it in this state ten minutes. When cold 
 and hard break the mass into small pieces, 
 and inclose them in a phial well corked. 
 They will, after exposure to the rays of the 
 sun, emit a beautiful white light in the dark. 
 Balistraria. a cruciform aperture in 
 the wall of a fortress, through which cross - 
 bowmen discharged their arrows ; also a 
 turret projecting from the wall of a building. 
 In the latter sense better Bartizan, (which 
 see.) 
 
 Balk. Any large piece of timber. 
 Ball. Any globular body, whether 
 natural or artificial. 
 
 Ball and Socket. A particular kind 
 of joint, of which the one part is shaped 
 like a ball, the other, or that in which the 
 former works, is a hollow socket, of the 
 same diameter. This fitting and pressing 
 upon the surface of the ball allows it, toge- 
 ther with whatever may be attached to it, 
 freedom of motion in every direction, yet 
 steady in all. 
 
 Ball Cock. A water cock, the plug of 
 which has attached to it a lever, bearing a 
 buoyant hollow copper ball at the lower ex- 
 tremity. Such an apparatus is self-acting, 
 and is often attached to water butts, tanks, 
 &c. It is represented as follows : — 
 
 When the water in the tank is drawn off, 
 the ball sinks, and opens the cock, which 
 admits the water. When this rises, the ball 
 rises with it ; in its new position closing the 
 cock, and consequently stopping the stream 
 of water ; therefore the tank is always full, 
 yet never runs over. 
 
 Ball Flower. An ornament common in 
 the Gothic buildings of the decorated style 
 of the fourteenth century. It consists of a 
 ball, surrounded by three leaves. 
 
BA 
 
 BA 
 
 Ball Rack. Two wooden pins, fastened 
 into a feather-edged piece of wood, and at- 
 tached either to a separate stand, or nailed 
 against the wall of a printing office, intended 
 to hold the balls used for inking the type. 
 
 Balls, Printer's. A circular piece of 
 pelt, leather, or canvas, covered with compo- 
 sition, stuffed with wool, and fastened to a 
 handle. Its use is to cover with ink the 
 type which is arranged ready for printing. 
 
 Ball Stocks. Pieces of wood of the 
 shape shown in the cut of Ball Rack ; and 
 turned out of maple, alder, or elm, intended 
 to form the handle, and part of the body of a 
 printer's ball. 
 
 Ball Valve is represented 
 in the margin. It is supposed 
 to be seen withinside a cylinder. 
 The ball is surrounded by four 
 arms, fitted on the edge of a semi- 
 circular cup, a hole being through 
 the bottom of the cup. If this 
 simple instrument be made the 
 piston of a lift pump, at every 
 down stroke the ball will be 
 forced up by the water beneath, 
 which will consequently xise 
 round the edges, and fill the space above the 
 ball. Upon the ascent of the pump rod, 
 the ball will sink into the semi-circular 
 opening of the sucker, which being made of 
 a proper size to fit it, will consequently 
 shut off the communication. A valve of 
 this kind, being very easy to make, and not 
 liable to clog, is very convenient for models 
 and small pieces of machinery. 
 
 Ballast Waggon. The waggon em- 
 ployed in removing earth in excavations, &c. 
 Each waggon holds fiom 2 to 3 cubic yards, 
 when it is piled up. 
 
 Ballast Lighter. A large open barge 
 employed m removing silt, sand, rubbish, &c., 
 whether emptied into it from the shore, or 
 Slung up from the bottom of the stream, in 
 
 which latter case the lighter is attended by a 
 ballast heaver. 
 
 Ballast Heaver. A large iron hoop, 
 with a leathern bag sewed to it, to heave up 
 dirt, sand, &c., from the bottom of a river, 
 It is attached to a long handle, which in the 
 operation of heaving is partly fastened to a 
 rope, keeping thereby the bag to the ground, 
 while a chain fastened to the iron hoop, and 
 worked by a windlass, drags the machine 
 along, and lifts it up for its contents to be 
 discharged into the ballast lighter. 
 
 Ballasting. Furnishing a ship with some 
 heavy material to keep it upright and steady 
 when unladen. In road-making it signifies 
 the covering of roads generally ; also the 
 filling in of all holes and interstices between 
 the rails of rail-roads, &c. In some parts 
 of the country, the broken bricks, stones, 
 and other rough material, spread over the 
 foundation of buildings, for the brick or 
 stone-work to rest upon, is called ballast or 
 ballasting. This is, at other places, called 
 bottoming. 
 
 Ballistic Pendulum. An instrument 
 for ascertaining the velocity of mihtary pro- 
 jectiles. It consists of a heavy piece of wood, 
 suspended from above, and with a needle and 
 small arc attached to it, to indicate the 
 result. 
 
 The above is a representation of it. When 
 a cannon ball strikes the board, it occasions 
 it to oscillate, and the utmost extent or angle 
 of oscillation is indicated by the scale. 
 
 Balloon. Any receiver of a globular 
 form, more usually applied to an immense 
 bag of silk, or canvas, made for the purpose 
 of holding hydrogen gas, and of a sufficient 
 size to be buoyant in the atmosphere, when 
 filled with that light gas. Balloons for the 
 purpose of navigating the air, at first con- 
 sisted of such bags, expanded by smoke, 
 and rarefied air, (see Montgolfier,) rising 
 into it, in consequence of a fire being lighted 
 beneath, therefore called fire balloons. At 
 the present day gas balloons are the only 
 kind employed, and it may be said, the 
 English are the only people who venture to 
 ascend in them. A balloon consists of the 
 requisite pear-shaped or globular bag at top ; 
 a net-work of ropes over this ; and a car of 
 
BA 
 
 BA 
 
 wicker-work hanging from the ropes. It has 
 also two clack valves on the upper part, one 
 within the other. The small valve for the 
 purpose of enabling the aeronaut to descend, 
 and to let off superabundance of gas ; and 
 the other valve is with the object of emptying 
 che balloon as early as possible after the car 
 touches the ground, that it may not be 
 dragged along after it has fallen. 
 
 Balneum Mari^. A water bath. (See 
 Bath.) 
 
 Balsams. Vegetable juices, either liquid 
 or concrete, consisting of a substance of a 
 resinous nature, combined often with benzoic 
 acid. They are insoluble in water, but readily 
 dissolve in alcohol and ether. The liquid 
 balsams are copaiva, opobalsam, Peru, sty- 
 rax, and tolu. The concrete are benzoin, 
 dragon's blood, and storax. 
 
 Balsam of Sulphur. A solution of 
 sulphur in oil. 
 
 Balteum. a word used by Vitruvius to 
 denote the bolsters or moulding on the sides 
 of an Ionic capital. 
 
 Balustrade. A range of ballusters, 
 serving either for an elbow rest, as in porches ; 
 as a guard against accidents, as in balconies, 
 staircases, &c. , or to keep off persons from 
 without, as around tombs, &c. It also often 
 supports a coping, thereby forming a parapet. 
 Baluster. A httle column, pilaster, or 
 post, forming part of a balustrade. Balusters 
 are of various forms, accordant with the 
 style of architecture of the buildings to which 
 they are appended. They are made of wood, 
 metal, or stone. 
 
 Bamboo. A cane-colored porcelain biscuit, 
 invented by Mr. Wedgwood, and used for the 
 manufacture of numerous utensils of domestic 
 use. 
 
 Band. In architecture, any flat member 
 or moulding, that is broad and not very deep. 
 Also the set of mouldings which encircle the 
 centre of the pillar in early English buildings. 
 A tablet or string course around a tower, 
 &c. ; as we say, a band of trefoils, or other 
 ornaments. 
 
 Bandanna. India handkerchiefs dyed in 
 such a manner as to have round or square 
 light colored spots upon a darker ground. 
 All articles which are dyed in this maimer 
 are said to be bandanna dyed. 
 
 Band LET. Synonymous with annulet. 
 
 Bank. A deal table, on which printers 
 keep the damp paper that they are about to 
 print upon. 
 
 Banker. A stone bench on which 
 masons cut and square their work. 
 
 Baptistery. That part of a church in 
 which the baptismal font is situated. 
 
 Bar, in Architecture. A gate house, or 
 barrier ; thus Temple Bar, Holbom Bar, &c. 
 
 Bar. a piece of metal, or timber, placed 
 horizontally, and running across from one 
 part of any frame work to another. It also 
 signifies an accumulation of sand or gravel 
 at the mouth of a river, harbour, &c., 
 formed by the tides. 
 
 Bar Magnet. (See Magnet.") 
 
 Barbican. A watch tower ; also a field 
 work, a little beyond the walls of a town or 
 castle. 
 
 Bares. Those parts of an image or statue 
 which represents the bare flesh. 
 
 Barge Board. Berge Board. Pargb 
 Board, or Verge Board. A board fixed 
 to the ends of the gables of timber houses, 
 to hide the projecting timbers, and throw off 
 the wet. They are often made highly orna- 
 mental. 
 
 Barilla. A name given in commerce 
 to the impure soda imported from Spain 
 and the Levant. It is made by burning to 
 ashes different sea plants, and is brought to 
 us in hard porous masses, of a speckled 
 brown color. 
 
 Barium. The metallic base of barytes. 
 It is of a dark grey color, fusible at a red 
 heat, turns to barytes when left exposed to 
 the air, and when heated bums with a deep 
 red light, is rapidly dissolved in water. It 
 combines with oxygen in two proportions, 
 forming 1st, barytes, or the protoxide of 
 barium, and 2nd, the deutoxyde of barium. 
 It unites also with sxdphur, phosphonis. 
 chlorine, cyanogen, &c. Its salts are all 
 white, and, except the sulphate, poisonous. 
 
 Bark. The covering of trees. The barks 
 are in the arts a valuable class of bodies. 
 The barks of the oak, willow, and other trees, 
 contain much tannin, and are, therefore, 
 useful in the art of tanning leather. Nu- 
 merous barks have medicinal properties of 
 no mean degree ; others are employed by the 
 dyers ; or for various other purposes. 
 
 Barker's Centrifrugal Mill. This 
 valuable instrument derives its power from 
 the force acquired from a stream of water 
 rushing from two holes, so placed, near the 
 ends of the arms of a moveable spindle as 
 to throw the water on each side, and thereby 
 
BA 
 
 BA 
 
 to occaision a counter action against the 
 arms, propelling them, and whatever may- 
 be attached to them in a contrary direction. 
 
 Suppose A in the above cut to represent a 
 funnel connected with the hollow spindle G, 
 this rests at the bottom on a pivot C, and 
 bears a shaft above, which is connected 
 with one of the mill-stones E. The hollow 
 part of G is terminated by the two hollow 
 arms B B, which arms have holes, as repre- 
 sented. A stream of water flowing into A 
 will fall down into G, and fill the arms B B ; 
 at length rushing out of the holes. The air 
 will olfer such a resistance to the issuing of 
 the water, that the arms, together with the 
 other moveable parts, will revolve rapidly. 
 Under the article Centrifugal, is the descrip- 
 tion of a mill, the contrary in effect to the 
 above. 
 
 Barlow's Compensation Plate. An 
 apparatus for counteracting the effects of the 
 local attraction of the iron in a ship for the 
 needle of the ship's compass, thereby ena- 
 bling it to obey the terrestrial magnetic 
 influence only. It consists merely of an iron 
 wheel, placed in a certain position relative 
 to a compass needle ; and which position is 
 found by actual experiment, by comparing 
 the directive position of the ship's compass 
 needle, with one at a little distance on shore ; 
 and holding, in the first instance, the com- 
 pensation plate to the former, in such a 
 manner as to bring it to the same point as 
 the other. This being done by trial, the 
 plate is then fixed in any convenient manner 
 ftt that place. In the cut it is seen attached 
 
 to one of the legs of a tripod stand, the 
 compass being on the top. Mr. Barlow re- 
 commends that the plate should be made of 
 two very thin pieces of iron, with a card or 
 thick paper between them. The plates are 
 from 12 to 14 inches in diameter. 
 
 Barlow's Electro-Magnetic Globe, 
 is a globe of wood or pasteboard, 9 or 10 inches 
 in diameter, supported upon two wooden 
 uprights. The globe has a wire covered 
 with silk or cotton, coiled completely over it 
 from one pole round and round to the op- 
 posite pole. One end dips into the cup P, 
 the other into the cup N. When the two 
 poles or 'ions of a galvanic battery are con- 
 nected with the wires in P and N, the fluid 
 circulates around the globe, in consequence 
 of which the globe becomes magnetic, though 
 there is no iron attached to it ; and a small, 
 delicately-balanced magnet placed upon any 
 part of it will indicate the polarity and dip, 
 in exactly the same manner as the usual 
 magnet does upon the earth itself. 
 
 Barlowt's Spur Wheel, is represented 
 below. It is formed of a plate of very thin 
 brass, cut with 8, 10, or 12 rays, amalga- 
 mated at their points, and supported upon 
 two points of the cross arm, which is of such 
 a height that the points of the teeth dip into 
 a shallow trough, cut in the foot board. 
 The cross arm as well as the trough at 
 bottom are accompanied with mercury cups. 
 
BA 
 
 BA 
 
 To use the wheel, put a little mercury in 
 the trough, so that the points of the wheel 
 just dip into it, and connect the two cups 
 with the two poles of a galvanic battery, and 
 place a powerful horse-shoe magnet with one 
 pole on each side of the spur wheel, in the 
 same manner as was represehted in Arago's 
 oscillatory plate. Immediately the wheel 
 will begin a rapid rotation upon its axis. 
 Two spur wheels are sometimes supported 
 upon the same frame. It must be noted 
 ^that one point must leave the surface of the 
 mercury, before the next touches it, or the 
 wheel will not rotate. For a modification of 
 tlus experiment see Sturgeon. 
 
 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 fer- 
 mentation, such as beer, wine, mead, cider, 
 &c. 
 
 Bar Posts, are those whicn are fastened 
 into the ground, forming the sides of a 
 field gate, and are morticed so as to admit 
 of bars or horizontal pieces, which may be 
 inserted easily, or taken out at pleasure. 
 
 Barometer. An instrument for ascer- 
 taining the weight of the atmosphere, and 
 as this fluctuates according to the dryness 
 of it, so the instrument fluctuates also, and 
 this becomes indicative of corresponding 
 changes in the weather. Also, as the weight 
 of the atmosphere decreases from the level 
 of the sea upwards, the barometer becomes 
 a valuable instrument to measure heights. 
 The construction of all barometers depends 
 upon the principle, that the atmosphere 
 presses with a weight of 15 lbs. on each 
 square inch, and that in every direction ; so 
 that provided a tube be exhausted of air 
 to prevent any counter pressure, and the 
 end dipped in water, the weight of the 
 atmosphere upon the water would press it 
 into the tube, until it had attained such a 
 height as to weigh 15 lbs. per inch surface ; 
 this column if of water would be 32 ft. long . 
 As an instrument or weather glass, 32 ft. 
 long is inconvenient, mercury is substituted ; 
 this by the same pressure stands at a height 
 of from 28 to 32 inches, according to the 
 state of the air. The barometer is, therefore. 
 
 an instrument formed of a tube of glass 
 more than 32 inches long, closed at the 
 upper end and open at the lower ; then filled 
 with mercury ; and then inverted into a cup 
 of mercury, which is exposed to the influence 
 of the external air ; the mercury wUl then 
 stand at a certain height at the upper end 
 of the tube, where a scale being placed, the 
 pressure, and consequently the dryness or 
 moisture of the atmosphere may be seen by 
 inspection. 
 
 Such is the common barometer, figured A. 
 The wheel barometer agrees in principle, but 
 differs in arrangement; the glass tube is 
 turned round at the end, so that the mercury 
 occupies both legs ; as it descends in one, it 
 rises in the other, and vice versa, so that a 
 little glass weight, with a string to it, passing 
 over a pulley, and that pulley moving a hand, 
 indicates with great precision the least change. 
 E. The tube of a barometer should be at 
 least a quarter of an inch bore. 
 
 The diagonal barometer has the upper 
 part inclined at an angle of about 45° with 
 the vertical portion, that the divisions may 
 be more readily seen. B. 
 
 The pendant barometer is an instrument 
 pretty rather than useful ; it is now usually 
 made of a smaU mouthed phial, nearly filled 
 with water, and suspended from a ceiling, 
 with the open mouth downwards ; when the 
 convex or concave lower sift-face is thought 
 to prognosticate changes of the weather. C. 
 The original instrument, which was invented 
 by Amontons, was a slightly conical glass 
 tube, 4 or 5 ft. long, closed at the top, and 
 containing about 30 inches of mercury ; 
 according to the position in the tube which 
 this occupied, so was the weight of the air 
 ascertained. D. (See Marine Barometer, 
 Manometer, Boyle's Statical Balance, Por- 
 table Barometer, Sympesometer, and Moun- 
 tain Barometer.) 
 
 Barometric Scale. The scale attached 
 to a barometer. It extends from 28 inches 
 to 31 inches, each inch beiag divided into 
 
BA 
 
 BA 
 
 tenths and hundredths, by means of a 
 n^oveable hand or slide. 
 
 Barometrical Thermometer. An in- 
 strument invented by the Rev. F. WoUaston, 
 to ascertain heights, by the degree at which 
 water boils at those places, such degree 
 being accordant to atmospheric pressure, 
 and consequently, the altitude above the 
 level of the sea. 
 
 ^.^^ 
 
 E D C is the instrument ready for use ; it 
 has a scale 4^ inches long, divided into 100 
 parts. The scale and thermometer tube are 
 fastened to a double screw of metal C. D 
 is the index which is moved up and down 
 by the tangent screw E. A is an enlarged 
 view of the thermometer tube. It has a 
 large bulb, (1 inch) at bottom ; its tube is 
 bent and widened out near the bulb, and at 
 the top, instead of being closed in the usual 
 manner, is sealed with a glass cap B. H 
 is a cap to screw on to C, and defend the 
 bulb when the instrument is not in use ; at 
 which time the tube F also is put over the 
 instrument, and fastened to the other screw 
 belonging to C. Under F is seen a lamp 
 which also fits into the case when not wanted. 
 When the height of a place is to be ascer- 
 tained, fill F with water and make it boil ; 
 when boiling, immerse the bulb of tlie 
 thermometer into it, from the degree of 
 boiling may be ascertained the altitude of 
 the place. 
 
 Barometer, Syphon. (See Mercurial 
 Guage.) 
 
 Baroscope. (See Barometer.) 
 
 Barrel. A cask holding from 32 to 36 
 gallons; generally any middle-sized cask, 
 whether for liquid or dry goods. 
 
 Barrel Drain. One constructed in the 
 form of a hollow cylinder. 
 
 Barrel of a Drum Wheel. The cy- 
 lindrical part round which the rope is rolled. 
 
 Barrel of a Pump. Tlie cylinder or 
 hollow part in which the piston works. 
 
 Bartizan. A small projecting turret, ca- 
 pable of holding only one or two archers. 
 
 Barton's Iris Ornaments. Steel but- 
 tons, buckles, and other similar articles are 
 so called when they have exceedingly fine an(# 
 numerous lines or channels cut upon them, 
 because such lines as these occasion what is 
 called a play of light ; or, in more scientific 
 language, they polarize the light which falls 
 upon them, so that it is reflected in the most 
 vivid and varying colors, exactly as we see in 
 the reflection of light from the diamond ; 
 and in an inferior degree from the surface of 
 mother of pearl ; buttons thus prepared ap- 
 pear by candle-light of the most vivid and 
 ever-changing brilliancy. Such ornaments 
 were first made by Mr. Barton, of the Mint. 
 Barya. Synonymous with barytes. 
 Barytes. An alkaline earthy substance, 
 composed of barium and oxygen : it readily 
 combines with most of the acids. Its sulphate 
 and carbonate are very abundant as minerals 
 in many parts of England, and known on 
 account of their weight by the name of 
 " ponderous spar," though this term applies 
 properly to the former only. It is scarcely 
 used in the arts, is insoluble in water, and 
 in alcohol. 
 
 Basalt. A ponderous, massive, black 
 mineral, occurring mostly in immense co- 
 lumnar concretions, of which the celebrated 
 Giant's Causeway, in Ireland, and Fingal's 
 Cave, in the Isle of Staffa, are remarkable 
 examples. 
 
 Basaltes. a black kind of earthenware, 
 formed of basalt ground, mixed with a 
 little borax, or soda, moulded and baked. 
 Its use is well known in black tea pots, 
 milk jugs, &c. It is very hard and durable 
 resists acids ; is capable of taking a high 
 polish ; and will bear, without injury, a 
 great degree of heat. 
 
 Base. A rest or support ; particularly 
 applied to the bottom of columns and 
 pedestals. In geometry, the lowest part of a 
 figure ; or that upon which it is supposed to 
 stand. 
 
 Base Court. The back court yard of a 
 castle, in which the out-houses were situated. 
 Basement. The lower story of a building. 
 In ordinaiy houses it is not called so, unless 
 partly below the surface of the ground. In 
 pnblic buildings it supports the main order 
 of architecture. 
 
 Base Line. In perspective, the common 
 section of a picture, and the geometrical plane. 
 
BA 
 
 BA 
 
 Base Lines. The mainlines of a survey 
 upon which the correctness of the whole 
 
 depends, 
 base line. 
 
 In the following cut A B is the 
 
 Base Mouldings. Mouldings around 
 the base of a building. The classical Greek 
 buildings were without base mouldings, ex- 
 cept as to the bases of the columns, and 
 even these are only found in the more decora- 
 tive orders. (See Attic Base.) The Romans 
 adopted the column base of the Greeks, 
 adding the following very simple base for the 
 Tuscan order. 
 
 Gothic buildings are usually enriched with 
 many ornaments around the basement story. 
 Of the style of these the annexed cut will 
 convey a correct idea. 
 
 pro- 
 
 Bases. In chemistry, a term applied to 
 all the metals, alkalies, earths, and other 
 bodies, which unite with acids, or with gases. 
 Thus in sulphate of copper, the copper is 
 said to be the base of the salt, from the 
 supposition that the non-acid principle is 
 that which gives diversity or distinctness of 
 character to compounds. The term is now 
 retained from its convenience, rather than 
 the truth of the above opinion. 
 
 Basil. The angle at which a tool is ground, 
 in order that it may cut readily. 
 
 Basil Leather. Tanned sheep skin. 
 
 Basilica. A public hall among the 
 Romans. 
 
 Basso Relief. Sculptured work, pro- 
 jecting less than half its proportions beyond 
 the surface. (See Alto Relief and Messo 
 Relief.) 
 
 Bassorine. a constituent part of a 
 species of gum which comes from Bassora. 
 It is obtained by soaking gum Bassora in a 
 great quantity of cold water, and in removing 
 by a filter all the soluble parts. It is semi- 
 transparent, swells in cold and boiling 
 water, is difficult to pulverize, but very 
 soluble in water slightly acidulated with 
 nitric or muriatic acid. 
 
 Bastion. A rampart or bulwark 
 jecting beyond the walls of a town. 
 
 Bat. Part of a brick. 
 
 Bat's Wing Burner. A gas burner 
 with a slit at top, instead of a round hole ; 
 the gas issuing from this bums in a flame, 
 which is spread out like a fan, or a bird's 
 wing. 
 
 Bath Metal. An alloy of 4^- ounces of 
 zinc and 1 lb. of brass. 
 
 Bath, in Chemistry, is a vessel filled 
 either with hot sand, or with water, inclosing 
 another vessel which contains a substance to 
 be dried or heated; of a water bath the 
 common glue pot is an example ; a sand 
 bath is of the same formation ; it may be 
 considered an iron pan full of sand : put on a 
 fire it will become gradually and equally 
 heated, and acting like a fire, heats whatever 
 is put upon it, and that without danger to 
 the glass vessels, or burning their contents 
 unless the fire is very strongly urged. 
 Baths have often been made of oil, melted 
 lead, tin, &c., and steam has been advan- 
 tageously employed to heat various bodies 
 in the same way. 
 
 Battens. Boards from 2 to 7 inches 
 wide, used for flooring, doors, &c. A door 
 is called a battened door when made of a 
 board of such a size as to fit the aperture, 
 and this having styles, mullions, rails, &c. 
 fixed on the exterior surface. Gates are 
 often battened, being made of one range 
 of battens placed diagonally, and another 
 range of battens crossing them. Battens 
 are also those narrow slips of board nailed 
 upright to the bond timbers of a wall, in 
 
BA 
 
 BA 
 
 order to nail the laths upon when the walls 
 are plastered. Batten is also tlie moveable 
 lath or bar of a loom, which serves to strike 
 in or close, more or less, the threads of a woof. 
 Batter. A term applied to walls built so 
 as to lean inwards. In the dwarf walls of em- 
 bankments, fortifications, &c., the walls ge- 
 nerally batter. 
 
 Batter Rule. A plumb line, so contrived 
 that while the plummet hangs perpendicu- 
 larly, the building to which it is applied may 
 be constiucted sloping or battered. The 
 difference between this, and the common 
 jilumb line is, that the edge of that instru- 
 ment is parallel with the depending string ; 
 but of this the edge is made to differ from 
 the parallelism, in proportion as the building 
 is to taper. 
 
 Battery, Electrical. A collection of 
 Leyden jars, so arranged that they may be 
 all charged and discharged at once. ''See 
 Leaden Jar.) 
 
 Battery, Voltaic or Galvanic. An ar- 
 rangement of simple galvanic elements, so 
 contrived as that they shall all contribute to 
 produce a more powerful effect than they 
 could separately. Galvanic batteries are of 
 several kinds, and of different construction. 
 In all of them the two metals of which 
 they are formed, (see Galvanic Circle,) are 
 opposed to each other in each combination. 
 (See Babington, Cruikshanks, Wollaston, 
 Mullens, Daniel, DeLuc, CoronnedeTasses, 
 Volta, Grove, Smee, Faraday, Calorimoter, 
 
 Battery, Electro-magnetic, differs in 
 no degree from the galvanic battery, except 
 in being composed of few elements, scarcely 
 more than one of each kind, when in action 
 is made very energetic by stronger solutions 
 than are necessary for ordinary galvanic 
 purposes. (See Sturgeon, Ampere, Marsh, 
 Sfc.) 
 
 Battlement. An open, or interrupted 
 parapet, terminating the walls of a building. 
 Any wall with embrasures on the top, 
 whether used for defence or not, is said to 
 be embattled. 
 
 Bay. One of the compartments between 
 the ribs of a groined roof ; the main timbers 
 of a common roof ; the space between two 
 buttresses of a wall ; or between the mullions 
 of a window. This last is also often called a 
 dai/ or light. 
 
 Bayeux Tapestry. A celebrated piece 
 of tapestry, representing the conquest of 
 England by William the Conqueror, and long 
 preserved in the Cathedral of Bayeux, in 
 Normandy. It is supposed to have been 
 worked by Matilda, the wife of William ; or 
 by the Empress Matilda, daughter of Henry I. 
 
 Bayonet. A piece of wood or metal, with 
 two legs, to disengage and re-engage ma- 
 chinery. (See Sliding Pulley.) 
 
 Bay Window. Bow Window. A pro- 
 jecting window rising from the base upwards. 
 A bay window is always straight -sided ; a bow 
 window part of a circle. An oriel window is 
 a window of similar shape, but unconnected 
 with the ground, being supported by brackets. 
 
 Beacon. A tower or pole erected, or fire 
 lighted, as a signal of impending or present 
 danger, such as the approach of an enemy. 
 
 Bead. A small round moulding, some- 
 times plain, at others cut into divisions, like 
 a necklace ; in the latter case it is called 
 berried, and when these ornaments do not 
 correspond in size they are said to be blocked 
 and berried. When made flush with the 
 general surface it is a qnirk bead ; when 
 projecting a cock bead. A number of beads 
 imited is called a reedina:. 
 
 IlItTT^TTTTytrTTTTYlfTTnTTI 
 
 Bead and Butt Work. Framing in 
 which the styles and panels are flush or even 
 with each other ; the panels having a bead 
 on each side of them. 
 
BE 
 
 BE 
 
 Bead and Flush Work. In joinery, 
 a piece of framed work, having a bead mn 
 upon every edge of the framing which ad- 
 joins to each edge of the inclosed panel. 
 
 Beak Head. An architectural ornament, 
 peculiar to the early Gothic style, resembling 
 the head of a beast united to the beak of a 
 bird. 
 
 Beale Light. This is to the common 
 light of a lamp what a blast furnace is to an 
 ordinary one. A common Argand burner 
 is lighted, and through the centre of the 
 flame is urged a powerful stream of air. The 
 lamp is fed with any coarse material, such as 
 tallow, tar, rosin, &c., and however impure 
 either of these may be, yet the draught of 
 air occasions it to burn with the most intense 
 brilliancy, far more intense than the best 
 materials will do under ordinary circum- 
 stances. It is the suggestion of Mr, Beale, 
 engineer, of Greenwich. 
 
 Beam. A strong piece of timber, used to 
 support a floor, roof, &c. It has various 
 especial names, according to its use. The 
 lowest cross beam of a trussed roof is a tie 
 beam; one extending between a pair of 
 opposite rafters is a straining beam or colla?- 
 beam ; when it terminates the upper part of 
 a truss it is a camber beam. (See Roof and 
 Breslsummer.) 
 
 Beam of a Balance. The horizontal 
 piece of iron from the ends of which the 
 scales are suspended. 
 
 Beam Compass. An instrument adapted 
 for drawing very large circles. A long rod 
 of wood, with a nail at each end, or at a re- 
 quisite distance from each other, or a cord 
 fastened at the required centre, is a common 
 substitute by gardeners, carpenters, and 
 other workmen. The better instrument is 
 represented as follows : — 
 
 uHuiMMiUKUWUilllllll m 
 
 It is of a rod of wood, 2, 3, or more feet 
 long, with two square ferrules slipped over 
 it, each with a point below. One of these 
 ferrules is fixed at the end of the beam ; the 
 other is shifted backwards or forwards, ac- 
 cording to the size of the circle required. 
 
 Beam Filling. The masonry or brick- 
 work which fills the interstices between joists 
 or beams ; also, the brick-work in the gable 
 of a house has sometimes the same term 
 applied to it 
 
 Bean Shot. Granulated copper. 
 
 Beard of a Comet. The light which it 
 emits in the direction in which it moves, as 
 distinguished from the tail or rays left behind 
 it in its path. 
 
 Bearing. The position of one place from 
 another, reckoned in points of the compass. 
 Thus a place is said to bear NE. NW., &c., 
 meaning that it lies from your present situa- 
 tion in those directions. 
 
 Beater. An implement used by plasterers 
 to mix together the mortar and hair required 
 in their business. 
 
 Beats. The strokes made by the pallets 
 or fangs of a spindle in clock or watch 
 movements. 
 
 Bed. The upper and under surface of a 
 stone or brick as it lies in a wall. 
 
 Bed Mould. That part of a cornice 
 which is below the corona, between that and 
 the frieze. 
 
 Bed, of a Lathe. That part upon which 
 the mandril of the lathe is fastened, tnd 
 upon which the back poppit head and rest 
 sUde. It is in some lathes a triangular bar ; 
 in others, consists of two cheeks of wood or 
 iron. 
 
 Beetle. A large wooden mallet, used for 
 driving small piles; also the monkey or 
 heavy weight which descends from a pile 
 engine. (See Pile Engine.) 
 
 Beighton's Hand Gear. An invention 
 of Mr. Henry Beighton, in 1718, of certain 
 contrivances to work the cocks and valves of 
 the steam engine, and thus supersede the use 
 of the boys or men previously employed for 
 this purpose. It is therefore called hand 
 gear, and with slight modifications is used to 
 some engines at the present day. 
 
 Between two perpendicular pieces of wood, 
 (not to confuse the figure only one, B, is 
 shown,) is a square iron axle A, which bears 
 upon it the two hooks S S. The Y piece, as 
 it is called, G, bearing the moveable weight F. 
 Also the arms or spanners H and P. These 
 two last, as well as the Y piece, being fixed. 
 
BE 
 
 BE 
 
 N M is a forked frame, drawn backwards 
 and forwards by the arms of the Y piece, 
 and drawing with it the lever L. This rests 
 at one end on K, and at the other is fastened 
 to R, by a pin X. J is a lever and rack 
 which moves I, and this moves the cold water 
 injection pipe, while L regulates the admit- 
 tance of steam to the cylinder. Q, is the 
 plug frame, which is attached to the working 
 beam. In action Q rises and falls alternately ; 
 in rising it draws up P, and turning the axle 
 jA, brings D against the cross bar or stirrup 
 N. This drags forward L, and shuts off the 
 steam, and at the same time opens the in- 
 jection pipe E. The descent of the plug 
 frame reverses the effect, admitting steam, 
 and closing the water pipe. 
 
 Beighton's Steam Engine. This is a 
 modification of the Newcomen engine, (see 
 Atmospheric,) differing from it principally in 
 having attached to it an appendage to work 
 the various valves, besides other minor im- 
 provements noticed below. 
 
 A B is the wall of the building or other 
 support for the working beam, of which only 
 one half is shown at O. C is the steam cy- 
 linder. H is a small pipe from the cistern 
 above, to admit a little water above the pis- 
 ton to keep it tight. D is a pipe to admit 
 a part of this water to supply the boiler by 
 the pipe K. P is a pipe, leading to a dis- 
 tance, to convey away any surplus water there 
 may be in C, and thus prevent its flowing 
 over on the boiler. J is a small pipe, with 
 a cup and valve at the end of it, to allow of 
 the escape of any air there may be liberated 
 in the cylinder. This air escapes with a slight 
 noise at every descent of the piston, on ac- 
 count of which noise it is called the snifting 
 valve. 1 is the pipe to admit the steam. 
 I admits the injection water. E is the plug 
 frame to move the valve. F the JiunA gear. 
 
 G the lever of the cold water cock. N the 
 steel -yard safety valve, now for the first time 
 introduced. M the boiler, cased in brick- 
 work, upon which are two guage pipes, as in 
 Savory's engine. Another pipe, (acciden- 
 tally omitted in the figure,) conveys away 
 the injection water after it has been used. 
 
 Bell. A musical instrument, formed of 
 one piece of metal. The parts of a bell are 
 the body or carell, the clapper within, and 
 the ear or cannon whereby it may be hung 
 up. The edge of a church bell is generally 
 in thickness one-fifteenth of the diameter of 
 the bottom, and its height twelve times its 
 thickness. 
 
 Bell. The body of a Corinthian or com- 
 posite capital, supposing the foliage stripped 
 off; called also the tambour or drum, and 
 the corbel or basket. 
 
 Bell Crank. A bent lever or arc, used 
 chiefly in the hanging of bells, to allow the 
 wire to accommodate itself to the alteration 
 of motion requisite in turning comers, and 
 otherwise changing its position. 
 
 Bell Ckank Engine. A suggestion 
 made by Mr. Watt to do away with the beam 
 of the steam engine, substituting for it a 
 triangular frame or bell crank. The following 
 shows this part of the engine ; the cylinder, 
 condenser, valves, &c., are as in other cir- 
 cumstances. The cut shows one side of the 
 apparatus ; the opposite side is exactly si- 
 milar. 
 
 The point C is fixed. C A B is the bell 
 crank. H is fastened to the working crank. 
 The rod A D is attached to the piston rod. E 
 works the air pump. G the hot- water pump, 
 and it may be the cold water pump also. As 
 A moves up and down, it carries B back- 
 wards and forwards, and this works the crank 
 at H. Engines of this construction occupy 
 but little room ; the friction is, however, 
 greater than in the beam engine. 
 Bell, Diving. (See Diving Bell.) 
 Bells, Electrical. A small apparatus to 
 show electrical attraction. The following is 
 a view of one arrangement : — The hook and 
 beam at top are of metal ; two metallic chains 
 support the two outer bells — the centre one 
 and the clappers are suspended by silk strings. 
 A chain connects the centre bell with the 
 ground. When the whole is hung upon the 
 charged prime conductor of an electrical 
 
BE 
 
 BE 
 
 machine, the clappers will be attracted to 
 the outer bells, and here receiving a charge 
 will fly to the centre bell to deposit it, 
 and thus flying backwards and forwards ring 
 the bells. There are other forms of the in- 
 strument. (See Chime.^ 
 
 Bell Gable. A small turret, placed oc- 
 casionally at the west end of a church ; in- 
 tended to bear a small tinkling bell to be 
 rung at the elevation of the host ; not to be 
 confounded with the bell tower, where the 
 great bells were rung for assembly. Instead 
 of a turret, a niche cut in the gable itself is 
 sometimes used for the same purpose. 
 
 Bell Metal, is an alloy of 6 parts of 
 copper and 2 parts tin. 
 
 Bell, Pneumatic. An apparatus to show 
 that sound is not to be propagated in vacuo, 
 and thereby to prove that sound is but the 
 air in vibration. A small bell, according to 
 one of the following forms, is placed under 
 the receiver of an air pump, and the air being 
 exhausted from the receiver, the bell although 
 struck will yield no sound. The bells may 
 be struck by a rod passing through the col- 
 lar of the receiver, or by a small alarum at- 
 tached to it. The first figure shows an 
 alarum of this kind, where the string is sup- 
 posed to go through the collar of the receiver 
 at top. 
 
 Bkll Roof. A roof, the cross section of 
 which resembles a bell cut lengthwise ; it is 
 also called the cima recta roof, anU is chiefly 
 found in Elizabethan buildings. 
 
 Bellows. An instrument for producing a 
 current of air, by a reciprocating, that is, an 
 alternate up and down motion of one part or 
 
 flap of the machine, and used chiefly for 
 urging a fire. If the stream of air is re- 
 quired to be intermittent, the single-valved 
 bellows is sufficient ; if continued, one with 
 a double cavity, and an extra valve is re- 
 quisite. They are both figured below. 
 
 The single-valved or common bellows is 
 formed of an upper and under board, with 
 a skin of leather, naUed loosely between 
 them. The upper board is entire ; the lower 
 furnished with a clack valve. The action is 
 well understood. The double valve or forge 
 bellows has, in addition to these parts, a 
 board in the centre, also with a clack valve. 
 So that in fact it is what the other would be, 
 if an extra leather board and valve were 
 fastened beneath it. The centre board should 
 be a fixture — the nozzle connected with the 
 upper cavity — the lower part to be moved 
 when in use, and the upper board to be 
 loaded or made of heavy materials. The 
 action is this ; bearing in mind that the cen- 
 tral board is fixed, forcing down the lower 
 board, its valve is opened, and its cavity 
 filled with air ; drawing it up again, closes 
 its valve, and opens that in the centre. The 
 upper cavity is now full of air, and being 
 heavy the air rushes out of the nozzle in a 
 continued stream. The form of either in- 
 strument is of no moment. (See Blowing 
 Machine.^ 
 
 Bellows, Hydrostatic. A philosophical 
 instrument, of the following shape and ap- 
 pearance. It is intended to illustrate the 
 hydrostatic paradox, and show that a small 
 quantity of fluid force may be made to coun- 
 teract a great mechanical resistance. The 
 lower part consists of two round boards, a 
 foot or more over, the larger the better, with 
 loose leathers, fastened air-tight between 
 them. This may be loaded with a con- 
 siderable weight, and yet a person blowing 
 down the tube, may, by that slight force, 
 raise the weight, though the weight of the 
 air be not more than an ounce, and the load 
 upon the upper board a hundred weight ; a 
 person may thus lift himself up without 
 danger. It may be used with still greater 
 force by pouring water into the tube, when 
 it will be seen that a pint of water, weighing 
 one pound, may be made to Overcome half 
 a ton, if the leathers and boards be strong 
 enough. The actual power is calculated by 
 dividing the area of the bellows by the area 
 of the pipe, and multiplying by the weight 
 of fluid in the pipe, allowing in the first 
 
BE 
 
 BE 
 
 place the water to displace any air there may 
 be in the cavity of the bellows. (See Bra- 
 maVs Hydraulic Press.) 
 
 Belt. A line of stones or bricks pro- 
 jecting from a wall ; also called a stone string ; 
 a string course and blocking course ; though 
 the latter term, (see Blocking Course,) has 
 a somewhat more confined meaning. 
 
 Belts. Zones or girdles surrounding the 
 planet Jupiter, less lucid than the other 
 parts of his body, and varying from time to 
 time in width and relative distance from each 
 other, but always parallel, and around the 
 equatorial parts of the planet. Their nature 
 and use has never been ascertained ; some 
 astronomers supposing them seas ; others 
 considering them to arise from certain altera- 
 tions in the planet's atmosphere ; something 
 of a similar kind has been seen upon both 
 Saturn and Mars. 
 
 Belted Bottle. A Leyden jar, the 
 coatings of which are interrupted, or belted. 
 
 It has usually a medical electrometer, or 
 something similar attached; in order to 
 connect the belts when required, two wires 
 should pass into the bottle, one touching the 
 bottom to be drawn out occasionally ; the 
 other touching the inner belt.. Drawing out 
 the longer wire, the belt alone is charged ; 
 leaving it in, the whole bottle is affected ; 
 the requisite connection between the outer 
 belts being made at the same time. 
 
 Belvedere. An observatory built above 
 the roof, for the purpose of overlooking the 
 surrounding country ; also any small orna- 
 mented building on high ground in a garden, 
 intended for the same purpose. One of 
 the galleries, or open corridors, in the palace 
 of the Vatican ; is called the ** belvidere," 
 on account of the fine view it commands. 
 From this gallery the celebrated statue of 
 Apollo took its distinctive name. 
 
 Ben, Oil or. Obtained from the ben nut 
 by simple pressure. It is remarkable for its 
 not growing rancid in keeping, or at least 
 not for a number of years, and on this ac- 
 count it is used in extracting the aromatic 
 principle of such odoriferous flowers as yield 
 little or no essential oil in distillation ; such 
 as the hyacinth, jonquil, jasmine, mignionette, 
 &c. 
 
 Bench, or Berm. A ledge, or narrow 
 platform left on an embankment, in order to 
 strengthen it. 
 
 Bench Hook. A moveable pin, or plug, 
 passing through the top of a bench, for the 
 purpose of holding the wood worked upon. 
 
 Bench Marks. In surveymg, fixed points 
 left on a line of survey for reference at a 
 future time, consisting of cuts in trees, pegs 
 driven into the ground, &c. 
 
 Bench Table. The low stone bench, or 
 seat, around the walls and pillars in many 
 churches. 
 
 Bengal Stripes. Gingham, a sort of 
 cotton cloth, woven with colored stripes. 
 
 Bengal Lights. A species of fire-work, 
 producing a steady and very vivid blue-co- 
 lored fire. Their composition is 28 oz. of 
 sulphur, 12 oz. saltpetre, and2| oz. realgar. 
 Let these be well pounded and mixed toge- 
 ther, then sifted, and a portion put into a 
 small paint pot. Cover this over with com- 
 mon paper, and apply a common lighted 
 match to fire it. These are often called blue 
 lights, and are much used as night signals by 
 shipping. 
 
 Bennett's Gold-leaf Electrometer. 
 A most valuable instrument, for detecting 
 minute electrical impulses. No. 1 shows 
 the original form of the apparatus, as made 
 by Mr. Bennett : it consists of a glass tube, 
 such as a wide lamp glass, with a brass cap 
 and foot. Within the glass, and attached to 
 the brass cap, are hung two slips of gold leaf. 
 As soon as any tiling slightly electrified ap- 
 
BE 
 
 BE 
 
 proaches the instrument, the gold leaves 
 diverge, and if the impulse be strong enough, 
 strike against two slips of tin-foil, which are 
 pasted on the glass case. No. 2 is an im- 
 provement upon the above, suggested by 
 Mr. Sausseur. The cap at the top is fitted 
 with a glass tube in the centre of it, and the 
 gold leaves are fastened on to the end of a 
 wire, which passes through the glass tube, 
 and which is terminated at top by a small 
 table. In this form the insulation is more 
 complete, and consequently the instrument 
 more sensitive and certaia. 
 
 Bent Lever. A lever cf a bent or 
 crooked form, of which the clawed hammer 
 and the instrument for drawing teeth are 
 examples. The laws by vt^hich the power is 
 ascertained are precisely those of the common 
 lever, (which see.) 
 
 Bent Lever Balance. A weighing ma- 
 chine, represented as under : — 
 
 A B is a bent lever, turning on the pivot C, 
 loaded at the end B, and having a scale sus- 
 pended from A. When unloaded, the heavy 
 
 end of the lever hangs perpendicular, and in 
 proportion to the weight placed within the 
 scale, so wiU the end B rise towards the hori- 
 zontal position, and indicate by the graduated 
 arc what is the real weight of the body placed 
 in A. The power is dependant upon the 
 relative length of the levers, in reference 
 also to their respective weights. Thus sup- 
 posing each arm of the balance, that is, from 
 A to C, and from C to the extremity at B, 
 be of equal weight, the lever would remain 
 in the position represented, because A C is 
 equal to C E. The distance and the centre 
 of gravity of each is in a horizontal direction 
 from C, but in proportion as A is loaded, 
 so will the ball B remove to a greater hori- 
 zontal distance, while A will be scarcely 
 removed at all farther from C. 
 
 Benzamide. (See Benzule.) 
 
 Benzine. A principle obtained by heating 
 benzoic acid with hydrate of lime. 
 
 Benzoates. Salts composed of benzoic 
 acid and metalline or alkaline bases. Most 
 of them are soluble in water. 
 
 Benzoine. a crystalline substance, with- 
 out taste or color, deposited from the oil of 
 bitter almonds. 
 
 Benzoic Acid, formerly called flowers 
 of Benjamin, is made by subliming gum 
 benzoin from a hot plate. It may also be 
 obtained from many of the balsams, from 
 amygdaline, and other matters. It is in the 
 form of fine, white, circular crystals ; soft 
 like silk to the touch ; very inflammable, 
 with a sweetish, penetrating odour, for which 
 reason it is much used m the making of pas- 
 tiles and religious incense. It is soluble in 
 oil, alcohol, and more sparingly in water : it 
 unites and forms neutral salts with the alka- 
 lis. The alkaline earths and numerous of 
 the metals forming benzoates. 
 
 Benzoin Gum, or Gum Benjamin. A 
 substance of a resinous nature, imported from 
 the East Indies. It is of a speckled brown 
 color, fragrant when burnt, somewhat brittle, 
 and sweetish to the taste : it is soluble in al- 
 cohol, ether, sulphuric, acetic and nitric 
 acids^and partially in ammonia. 
 
 Bn^zoNE. A compound of carbon, hy- 
 drogen, and oxygen, procured by heating 
 benzoic acid with lime. 
 
 Benzule. A newly-discovered compound 
 inflammable body, of which benzoic acid is 
 an oxyde, and oil of bitter almonds, purified 
 from hydrocyanic acid, is a hydruret. Ben- 
 zule besides unites with chlorine, bromine, 
 iodine, sulphur, and cyanogen. Chloride 
 of benzule, with dry ammoniacal gas, treated 
 with cold water, forms benzamide. 
 
 Berberin. a newly-discovered bitter 
 principle, contained in the root of the 
 barberry. 
 
 Berillium. Synonymous with glucinum, 
 (which see.) 
 
BE 
 
 BI 
 
 Berlin Blue. Synonymous with Prus- 
 sian blue. 
 
 Bernouille's Dipping Needle, is a 
 contrivance for regulating with greater pre- 
 cision than ordinary the degree of dip in a 
 magnetized needle. 
 
 It consists of an ordinary bar of steel, 
 with a circle of brass, ivory, or card, fixed 
 concentric with its points of suspension. 
 Upon one of these points is a small moveable 
 arm, which, according as it is moved round, 
 alters the centre of gravity. To make it, 
 proceed thus : — Prepare the needle and cir- 
 cle, and balance them as accurately as pos- 
 sible. Then magnetize the needle, suspend 
 it, and mark its dip ; then take away its 
 magnetism, and turn the moveable arm until 
 it again dips to the same degree, as it did 
 when magnetized. Afterwards magnetize it 
 again, when being suspended a second time, 
 it wiU show the real dip much more accu- 
 rately than a common needle, or than it did 
 at first. 
 
 Berries op Avignon. The fruit of 
 rhamnus infectorius, a plant cultivated in 
 France for the sake of its berries, which are 
 plucked before they are ripe. They are used 
 to dye various shades of yellow, green, and 
 olive. 
 
 Bevelled Wheels or Bevelled Gear. 
 Two wheels with bevelled edges, so that they 
 work at certain angles to each other, and 
 not in the same straight line. 
 
 Bevil. a portion of a flat surface, 
 smoothly cut off, so as to form a regular 
 
 an-^le, either more or less than t^0°. When 
 tlie angle is exactly 45°, it is called a mitre. 
 Also an instrument like a square, but having 
 its sides moveable on a pin or joint, that it 
 may be opened to any required width. 
 
 Bezoar. This name, which is derival 
 from a Persian word, implying an antidote to 
 poison, was given to a concretion found in 
 the stomach of an animal of the goat kind, 
 which was once very highly valued for this 
 imaginary character, and has thence been 
 extended to the concretions found in all 
 animals. 
 
 Bi. Bin. Bis. Twice. In chemistry sig- 
 nifies an extra proportion of that substa-nce 
 to which the bi is annexed, most commonly 
 a double proportion ; as, for example, the 
 carbonate of ammonia contains one atom of 
 ammonia to one atom of carbon. The bi- 
 carbonate contains two atoms of carbon to 
 one of ammonia, and so on for other com- 
 pounds. 
 
 Bice. A pale blue color, formed from 
 smalt. When well ground, it forms one of 
 the best of artist's colors. A green color, 
 formed by mixing the blue with orpiment, 
 also bears the same name ; as also the blue 
 carbonate of copper, as well as certain com- 
 positions of indigo and verditer, with chalk. 
 
 BiHYDROGURET OF Carbon. (See CaV' 
 buretted Hydrogen.) 
 
 BiHYDROGURET OF PHOSPHORUS. (See 
 
 Phosphuretted Hydrogen.") 
 
 Bile. A bitter liquid of a greenish or yel- 
 low color, common to most animals ; the 
 peculiar secretion of the liver. (See Ox Gall.) 
 
 BiLECTioN Mouldings. Those which 
 surround the panels, and project before the 
 face of a door or gate. 
 
 Bill, with letter founders, the same as 
 fount with printers ; that is, a certain quan- 
 tity of type, proportioned in the number of 
 each letter, stop, space, &c., as nearly as 
 possible to the number in which each will be 
 required in ordinary printing. (See Fount.) 
 
 Billet, or Billet Moulding. An or- 
 nament common in Norman buildings, con- 
 sisting of an imitation of wooden billets, 
 alternately with vacant spaces. 
 
 N*^i»^-r 
 
 Billion. A million of millions according 
 to English mathematicians, but according 
 to the French only thousands of millions ; 
 in one case represented by 1,000000,000000; 
 in the other by 1,000000. 
 
 Binary Number. A number consisting 
 of two units, as 15, 73, &c. 
 
 Binocular. An optical instrument is so 
 called when made to be used with both eyes 
 at once. Thus a pair of spectacles is a bin- 
 ocular instrument ; a spy-glass is mouacu- 
 
M 
 
 B! 
 
 lar, or to be used with one eye only. Opera 
 glasses are now often made binocular, and so 
 were formerly some microscopes and teles- 
 copes ; but as they possessed but little ad- 
 vantage over the common instrument were 
 doubly difficult to adjust, and besides doubly 
 expensive, the use of them was never carried 
 to any extent. In structure, instruments of 
 this kind differ in no respect from the com- 
 moner sorts, except in being double. 
 
 Binding Screw. A term ap- 
 plied by opticians to denote the 
 screws by which the wires of gal- 
 vanic batteries, electro-magnetic 
 apparatus, and other similar things 
 are bound together, during the 
 time of their action. As good me- 
 tallic contact is necessary in elec- 
 tro-magnetic experiments, the ex- 
 treme point of the upper screw, as well as 
 the end of the wire to be inserted, should be 
 made bright, when wanted for use in deli- 
 cate experiments. 
 
 Binomial. Any thing known by two 
 names. In algebra a binomical quantity 
 consists of two terms, connected by the 
 signs, + plus, — minus, or = equal ; thus, 
 a + Uff a—b, a = b, are all binomial. A bi- 
 nomial curve is one whose ordinate is ex- 
 pressed by a binomial quantity. A binomial 
 equation is any equation of two terms, but 
 more commonly applied to the higher order 
 of equations. A binomial surd is used to 
 denote a binomial, of which one or both of the 
 branches are surd numbers ; thus a + V b 
 is a binomial surd. The binomial theorem 
 is a general algebraic formula, by which any 
 power or root of any quantity is expanded 
 into a series. 
 
 BiNOXYDE. A combination of oxygen and 
 a metal, in which the oxygen is in a double 
 proportion, to what it is in the oxyde. If 
 the oxygen be three-fold, it would form a 
 tritoxide. 
 
 Biot's Condensing Ribbon. A is a 
 glass cylinder or rod, an inch or more in 
 
 diameter, and 6 inches long ; capable of being 
 turned by the handle B ; and when in use to 
 be made perfectly dry. C is a coil of tin 
 foil, cut so as to resemble a ribbon, 2 inches 
 wide and 2 feet long, fastened to the cylin- 
 der at the inner end ; attached to the outer 
 edge or end is a silk string D. The ribbon 
 has a wire above, connected with the pith 
 balls at E, which are insulated from the 
 stand by the glass rod F. 
 
 To use it, give the ribbon three or four 
 sparks from the electrical machine, which 
 will make the pith balls diverge. Then pull 
 the string D, so as to unwind the ribbon. 
 This extension of surface will make the balls 
 collapse ; winding up the ribbon again by 
 the handle, the effect is again concentrated, 
 and the balls diverge, as at first, making 
 allowance for the casual dispersion of the 
 fluid into the surrounding air. 
 
 Biot's Spheroid. An experiment of M. 
 Biot to show that the visible disturbance of 
 the electric fluid resides only on the surface 
 of bodies charged or excited. The apparatus 
 necessary to prove this is a large metallic ball 
 suspended on a silk cord, and furnished with 
 two semi-circular cups, which fit over, and 
 enclose it ; the cups having glass handles. 
 To use the instrument proceed thus : — Hang 
 up the ball, cover it with the cups, electrify 
 it thus covered up, by a few sparks from 
 the machine ; then take off the caps by the 
 glass handles, hold either of them to a gold- 
 leaf electrometer, when its leaves will show 
 that the cups are charged. Holding the 
 ball in like manner to the electrometer, it 
 will undergo no change ; that is, will show 
 no signs of being affected, because it was 
 beneath the surface of the cups at the elec- 
 trizing of the whole. 
 
 BiPARTiENT is a number that divides 
 another into two equal parts ; thus 2 is the 
 bipartient of 4 ; 13 is the bipartient of 2G, 
 &c. 
 
 BiauADRATE. A fourth power, or the 
 square squared ; thus 16 is the fourth power 
 of 2. Twice 2 being 4, or the square ; and 
 4 times that being 16, or the biquadrate. 
 
 BiauADRATic Equation, is an equation 
 of the fourth degrep, or in which the unknowu 
 
BI 
 
 BI 
 
 quantity rises to the fourth power : thus, 
 
 x^ + aa^ + bot^ + cx-i- d= 10. 
 is a biquadratic equation ; x rising to the 
 biquadrate. It is the highest order of equa- 
 tion which admits of a general solution ; 
 all beyond this being resolvable only in par- 
 ticular cases. 
 
 BiauADRATic Root, is the fourth root 
 of any quantity ; thus 2 is the biquadratic 
 root of 16. It is the square root of the 
 Square root. 
 
 BiauiNTiLE Aspect of the Planets, 
 is when they are distant from each other 144°, 
 or twice the fifth part of 360°. 
 
 Bird's, (Dr.,) Contact Breaker, A 
 is a bar of iron, 5 or 6 inches long, sup- 
 ported on an upright, near the centre of the 
 foot-board, and capable of oscillating up and 
 
 down about 2 inches : the iron bar has two 
 covered copper wires coiled round it, one at 
 each end ; the two ends of the wires being 
 twisted together, and terminatinng in a fork 
 over the cups E and F. The two cups at 
 E are connected with the two at F, by two 
 wires beneath the stand. Behind the vibratory 
 electro-magnet, or iron bar, are two horse- 
 shoe magnets B C, placed with their north 
 poles uppermost, and at such a height that 
 one end of the bar shall be at the north pole 
 of one magnet, when the other end of it is at 
 the south pole of the other magnet. D shows 
 the situation of the binding screws to con- 
 nect with the battery ; one of the screws 
 being united by a wire beneath to one of the 
 cups at E, and the other screw to the re- 
 maining cup at E. The connection with the 
 battery being made, A becomes a tempo- 
 rary magnet when either end dips in the 
 mercury cups, and if the coils of wire be 
 wound in a proper mode, the acquired poles 
 of the temporary magnet will be repelled by 
 the contrary poles of the permanent magnets, 
 and the magnet itself will vibrate ; the fork 
 being lifted out of the cups, connection will 
 be broken at that end, but formed at the op- 
 posite end. The poles of the temporary 
 magnet are at the same time changed, and 
 
 repulsion again ensues ; thus a vibratory 
 motion, and with it breaking of the con- 
 tinuity of the circuit is established. 
 
 Bird's, (Dr.) Electro-Magnetic Ma- 
 chine, consists of two upright bars of iron, 
 with a primary and secondary coil of wire to 
 each. (See Bachhoffner's Machine.) Over 
 one magnet, or in any other way that is con- 
 venient, is fixed a brass beam F, having an 
 iron ball at one end, and at the other end a 
 stout copper wire F, forked below to dip 
 into the cups at D. The binding screws A A 
 are connected with the two ends of the pri- 
 mary coils, a break in the circuit being 
 between the cups at D. The cups at D are 
 connected with the binding screws at B B, 
 which are connected with the ends of the se- 
 condary coils. The poles of a small galvanic 
 battery being connected with A A, the fluid 
 in the primary coils is disturbed, and 
 makes the iron ball magnetic ; the ball of 
 the beam is attracted therefore to that coil 
 which it hangs over, and consequently lifts 
 the forked wire from out the cups at D, 
 contact being thus broken with the battery, 
 the bars of iron are no longer magnets. 
 The ball of iron on the beam therefore rises 
 again, and a second time the forked wire dips 
 in the cups, and renews the first effect. In 
 this manner, the rapid vibration of the beam 
 produces a correspondent breaking and re- 
 newal of contact. 
 
 Bird's, (Dr.,; Inversor. An instru- 
 ment to reverse quickly the current from the 
 galvanic battery. Its action is very simple, 
 complete, and convenient. 
 
 A B is an arc of solid brass, formed of 
 three separate pieces, either distinct from 
 each other, with a cavity between them ; or 
 else two pieces of ivory are inserted, that 
 the surface at the top may be quite even. 
 The two outer pieces of brass forming this 
 
m 
 
 BL 
 
 arc are connected together by a wire under- 
 neath the stand, but the centre pillar has no 
 connection with the others. A and the cen- 
 tre piece have binding screws attached. C 
 and D are two bars of brass, fixed to each 
 other, so that when one is moved the other 
 follows it, yet there is no metallic commu- 
 nication between them. There are binding 
 screws at one end of each, while the other 
 ends fit tightly upon the arc. The whole 
 cross moves stiffly round the centre pin. The 
 battery connection being made with E and F, 
 the object to be galvanized placed between 
 the binding screws of the arc, and the bars 
 or cross, as represented in the cut, the 
 positive pole being at E, the current would 
 traverse D to B, thence underneath by the 
 connecting wire to A, from A through the 
 object to the middle piece, and from this 
 by C to F. Slipping the cross aside so that C 
 is moved to A, (other things as before,) the 
 current would pass along D to the centre 
 piece, thence through the object to A, and 
 back by C to F, or to the opposite end of 
 the battery. This is a most valuable instru- 
 ment to the electrician. 
 
 Bird Lime. A glutinous substance, made 
 hy boiling, fermenting, and well pounding 
 the inner bark of the holly tree, or misseltoe 
 berries. It is used chiefly for catching small 
 birds. 
 
 Bird's Beak. A peculiar Gothic archi- 
 tectural ornament, represented as follows. 
 It occurs excrusively in buildings of the 
 Norman or early English style. 
 
 Biscuit. Unglazed porcelain. 
 
 Bisection. The division of a quantity 
 into two equal parts. 
 
 Bismuth. A metal of a reddish white 
 color, somewhat harder than lead, not mal- 
 leable. It melts at 480° Fahr. ; when partly 
 cooled again in the crucible, if the still fluid 
 portion of the metal be poured out, and the 
 inner part of the crust left around the sides 
 examined, the metal will be seen to have 
 arranged itself in the most beautiful crystals. 
 Bismuth is rapidly soluble in nitric acid, but 
 not in muriatic nor sulphuric acids. United 
 with other metals, bismuth mostly renders 
 them more fusible. It is used in printers' 
 types, in the composition of pewter, solders, 
 &c. 
 
 BissEXi'iLE. Leap year; a year consisting 
 of 366 days, which occurs once every four 
 years, except when that fourth year exactly 
 completes the century. Such years are leap 
 
 years as will exactly divide by 4 without a 
 remainder, except as before stated the cen- 
 tenary year ; thus, 1792 and 1796 are leap 
 years, but 1800 is not a leap year. It is 
 called bissextile, because the sixth day of the 
 calends of March was made double in such 
 years among the Romans. This day answers 
 to our 24th of February. We now add an 
 extra day to February to signify the bissextile 
 or leap year. 
 
 Bistre or Bister. A color made from 
 the soot of" dry wood, (of which beech is the 
 best,) boiled half an hour in water, in the 
 proportion of a gallon to 2 lbs. of soot. 
 After it has settled, the water is poured from 
 it, and when evaporated to dryness, and 
 made into cakes with gum water, it makes 
 good bistre. This color is much used by 
 artists in water colors. 
 
 Bite. If the frisketof a printer's press iff 
 not sufficiently cut away, but covers some 
 part of the form, so that it becomes printed 
 upon, it is called a bite. 
 
 BiTiNG-iN. The process of corroding cop- 
 per and steel plates, which have been pre- 
 pared by a ground laid over them, and the 
 design traced through the groimd with an 
 etching needle. For biting-in copper plates, 
 nitric acid diluted is employed ; for steel 
 plates many substances have been recom- 
 mended. The following is to be preferred : 
 3 parts strong nitric acid, and 1 part of 
 acetic acid ; when this liquid is poured upon 
 steel, faint tints will be produced in one 
 minute, and the strongest required in four or 
 five minutes. For the process, see EtcJiing.. 
 
 BiTTS. Small tools used in boring wood 
 or metal. 
 
 BiTTERiNG, or^ corruptly. Bittern. A 
 preparation sold to brewers and others for 
 adulterating beer, and composed of cocculus 
 indicus, liquorice, tobacco, quassia, and 
 sulphate of iron. 
 
 Bittern Wath-r. The water that remains 
 after the crystallization of common salt in 
 sea water, or the water of salt springs. It 
 abounds in sulphate and muriate of magne- 
 sia, to which its bitter taste is owing. 
 
 Bitumen. A fat unctuous matter» dug 
 from the earth or skimmed off lakes ; used by 
 artists sometimes as a color, under the name 
 of Jew's pitch. It is also valuable as a ce- 
 ment, forming a part of the asphalte cement. 
 
 Black Chalk. A mineral of a blueish 
 black color, a slaty texture, and which soils 
 the fingers. It occurs in Caernai-vonshire. 
 
 Black Chalk, for artists, is made in 
 two ways : One is to saw into proper shape 
 slips of charcoal, and afterwards boil them 
 in hot wax. Second. Mix ivory black with 
 soft fine clay, till of the color desired ; mould 
 it up vrith water of a proper shape, and set 
 it aside to harden. This kind is much softer 
 than the former. 
 
BL 
 
 BL 
 
 Black's, (Dr.) FuHnace. A very ser- 
 viceable portable furnace ; used for chemical 
 operations, and which may be applied to nu- 
 merous other purposes. 
 
 A is a vessel of sheet iron, lined around 
 the part where the fire is with fire brick, 
 that the heat may be the better retained. B 
 is the chimney, which may be lengthened at 
 pleasure. C is an aperture at the top, for 
 the reception of an iron sand bath or water 
 bath. D D are two sockets, for iron rods, 
 which have a cross bar at top, to suspend 
 various boilers by, that they may be over the 
 fire. E is a porcelain tube or gun barrel, 
 passing through the fire, for the production 
 of certain gases. This may be removed when 
 not wanted ; when one hole being stopped up, 
 the other will hold the nozzle of a pair of 
 bellows. F is an aperture, with a sliding 
 door for the reception of a muffle. G is a 
 door, by which a crucible may be put in the 
 fire ; and H is the ash-pit. The fuel may 
 be kept in the cavity under the chimney. 
 
 Black's, (Dr.) Blowpipe. (See Blow- 
 pipe.) 
 
 Black Flux. A material used to assist 
 in the melting of various metallic sub'stances : 
 it is made by mixing together equal parts of 
 nitre and tartar, and deflagrating them toge- 
 ther. The black substance which remains 
 is a compound of charcoal and the carbonate 
 of potass. 
 
 Blacking. A compound either in the 
 state of a liquid or a paste ; used for putting 
 a black gloss upon leather. The following is 
 an approved receipt for a liquid blacking. 
 Take of 
 
 Ivory black and treacle, each 12 oz. 
 
 Spermaceti oil 4 oz. 
 
 White wine vinegar 4 pints. 
 
 In the common blackings the oil of vitriol 
 is used, but this acid is very injurious to the 
 leather. 
 
 Black Jack. Miners give this name to 
 klende, which is an oxyde of zinc. 
 
 Black Lead. A mineral ; used for ma- 
 king pencils for artists, crucibles for foun- 
 ders and chemists, as a powder to diminish 
 friction, to put a polish upon stoves, and 
 other iron work, &c. The best is brought 
 from the mines of Cumberland ; it occurs in 
 large roundish masses, embedded in different 
 kinds of rock. For its chemical properties, 
 see Plumlaffo, by \yhich name it is chemically 
 known. 
 
 Black Wadd. One of the ores of man- 
 ganese. 
 
 Bladder Glass. In pneumatics, an in- 
 strument to show the pressure of the at- 
 mosphere. It is merely a glass vessel, open 
 at both ends ; upon the upper end is tied a 
 piece of thin bladder. Upon putting this 
 on the table of an air pump, and ex- 
 hausting the air from beneath it, the bladder 
 is pressed upon by the whole superincum- 
 bent weight of the atmosphere, and conse- 
 quently the bladder is forced inwards, and if 
 not too strong will burst with a loud report. 
 
 Bladdek and Weights. A pneumatic in- 
 strument, to show the elasticity of atmospheric 
 air. It is formed of a foot-board A, which 
 has three stout wires for sup- 
 porting a similar board at top. 
 B is another round piece of 
 wood, with a cup -shaped cavity 
 at top ; and over this is C, 
 which is a small bladder with 
 a small quantity of air in it, so 
 small a quantity that the blad- 
 der lies unseen in the cup B, 
 when E, which is a similar cup, 
 but with the hollow part down- 
 wards, is put over it. D repre- 
 sents three heavy leaden weights. 
 The weights and cup E slide 
 easily up and down between the 
 wires. When this instrument 
 is put under the receiver of an air pump, 
 and the air exhausted from around it, the 
 elasticity of the air within the bladder C will 
 expand it so much, as to raise up the heavy 
 weights above it. and thus show its rare- 
 faction. 
 
 Blair's, (Dr.) Achromatic Lens. An 
 improvement suggested by Dr. Blair, of 
 Edinburgh, to correct the sUglit tinge of 
 color apparent on the objects seen by even 
 the best achromatic telescopes, called the se- 
 condary spectrum. His first idea was to 
 have a concave achromatic lens, to refract 
 
BL 
 
 BI. 
 
 the green rays towards the axis ; and a con- 
 vex lens to refract them from the axis, thus 
 to neutralize each other's effects, and propel 
 the green rays of light along with the red 
 and yellow, which on account of the greater 
 refrangibility of the green rays were, under 
 ordinary circumstances, separated, occa- 
 sioning the secondary colors complained of. 
 
 The above being a difficult and complex 
 combination of lenses. Dr. Blair afterwards 
 suggested the interposition of a fluid between 
 two glass lenses, as follows, making the 
 fluid a concave lens. The fluid he employed 
 was muriatic acid, mixed with a metallic 
 solution. In the spectrum formed by this 
 fluid, the green were amongst the most re- 
 frangible rays, and when their dispersion was 
 corrected by that of glass, there was pro- 
 duced an inverted secondary spectrum ; that 
 is, one in which the green was above, when 
 it would have been below with a common 
 medium. He therefore placed a concave 
 lens of the above fluid between two glass 
 lenses, as shown in the figure, and with such 
 success that no trace of color is visible. 
 
 Blakey's Engine. A slight modification 
 of Savory's steam engine, for in Savory's 
 engine the steam comes into immediate con- 
 tact with the water to be driven out, conse- 
 quently is much condensed. Blakey took 
 out a patent in 1756 to prevent this, by in- 
 terposing a stratum of oil or air between tlic 
 water and the steam. The method of accom- 
 plishing this wa.s by the following engine : — 
 The fire-place, chimney, &c., was as in 
 ordinary engines. E is the boiler, D a pipe 
 proceeding from it into the receiver, or air 
 vessel I. This receiver is placed over another 
 vessel V, of equal capacity, and joined to it 
 by the pipe F. The receiver V is connected 
 by the pipe Q with the well suction pipe, 
 and the eduction pipe X. C is a funnel to 
 supply the boiler with cold water. T the 
 injection pipe, and cock L. Pa cock to 
 supply air to the receiver, or to permit its 
 escape when its accumulation renders it ne- 
 cessary ; this is also employed as a guage 
 cock, H is to let off superfluity of water 
 from the receiver. G is a guage cock on 
 the boiler. 
 
 The operation of the engine is very sim- 
 ple. Steam is generated in E, which flowing 
 through D disperses the air in I, driving it 
 before it like a piston, through F into V, 
 which pressing upon the water in V, forces it 
 
 through the pipe Q, the valve A, and up the 
 eduction pipe. When all the water at V is 
 expelled, the cock L is opened, and the water 
 falling through the cullender, placed in the 
 end of the pipe, condenses the steam in I, 
 and falling through a second cullender S,also 
 condenses the steam in V. A vacuum being 
 produced in I, and part of V, the atmospheric 
 pressure upon the water in the well at M, 
 drives it up the pipe Q into V ; when this is 
 full, turning off the cock L, and turning on 
 the steam D, the contrary action is produced, 
 as in the first instance. 
 
 Blanched Copper. An alloy of 8 ozs. 
 of copper and i an oz. of neutral arsenical 
 salt, fused together under a flux, composed 
 of calcined borax, charcoal dust, and fine 
 powdered glass. 
 
 Blast Pipe. A pipe employed in loco- 
 motive engines to convey the waste steam 
 up the chimney, and to urge the fire by 
 creating a quicker draught. 
 
 Blasting. An operation resorted to in. 
 mines and quarries, for the purpose of de- 
 taching large masses of earth, stone, or 
 metals. The operation is as follows : — A 
 hole is bored in the stone, 1,2, or 3 feet deep, 
 according to circumstances, and 1^ inches 
 in diameter ; a charge of gunpowder, made 
 like a cartridge, and with a slow match to it, 
 is then put in, and sand or clay put at the 
 top of it, so as to fill the hole. The fusee 
 or slow match is made to burn a certain 
 time before igniting the powder, to allow the 
 workmen to get out of danger. 
 
 Blast Furnace. An inclosed fire-place, 
 the heat of which is augmented beyond that 
 of an ordinary furnace, by a strong current 
 of air driven into the fire by means of a forge 
 bellows, or some other blowing machine. 
 
BL 
 
 The following 's a blast furnace of a §imple 
 and approved construction. 
 
 The outside is of common brick -work, 
 lined with fire brick A A ; it is fed through 
 the hole B. The fire at the bottom is urged 
 by the blast from the pipe D. An opening 
 is left at bottom for the escape of the melted 
 metal into the receiver C, whence it may be 
 made to run into moulds prepared for it. 
 Blast furnaces are chiefly used for the smelt- 
 ing of iron and other refractory metals. A 
 furnace of tlais kind is never allowed to cool, 
 but fresh ore and fuel is continually poured 
 in at the top, as may be found necessary. 
 
 Bleaching. The chemical art by which 
 the various articles, used for clothing and 
 other purposes, are deprived of a dark color, 
 and made to assume a whiteness not natural 
 to them. 
 
 Blende. An ore of zinc. 
 
 Blind Tooling. A term used by book- 
 binders to signify marks made on the leather 
 of bound books, by means of a tool made 
 hot ; used in distinction to those books 
 which are gilt on the edges, back, &c. 
 
 Blinds. Screens, formed of various ma- 
 terials and fixed in window frames, either to 
 exclude a too-strong light, or to screen the 
 interior of an apartment from the obser- 
 vation of persons on the outside, without 
 obstructing the view of those within. 
 
 Block House. A building erected by 
 besiegers for the investment of a castle. 
 
 Blocking Course. A course of plain 
 stone work, placed above the cornice in the 
 Grecian and Roman style of building ; also 
 a course of stone or brick, with mouldings 
 projecting beyond the wall, and forming a 
 base to the whole. 
 
 Block. A piece of wood, containing one 
 or more sheaves, upon which a rope is run 
 for lifting heavy weights. (See Pulley.) 
 
 BL 
 
 Block, as applied to railways, a founda- 
 tion or support for the rails upon which the 
 chairs are secured. Blocks are generally 
 about 2 feet square, and placed in the fol- 
 lowing manner : — 
 
 UJiri rn m nn 
 L-JL^LJL^L^ 
 
 Blockings. Bough square pieces of wood 
 glued on the joints at the under-side of 
 stairs ; at the back of fascias ; show boards, 
 &c., to strengthen the joints. The joints of 
 wooden columns are always blocked. 
 
 Bloom or Bloomary. A mass of iron 
 after having undergone the first hammering. 
 It requires several hammerings to render it 
 malleable enough for smith's use. 
 
 Blowing Machine. Any instrument for 
 producing a blast of air, the common bel- 
 lows for example ; though the term is mostly 
 applied to those implements applied for the 
 same purpose to blast furnaces, and similar 
 extensive operations. The following cut is a 
 very simple and effective machine applicable 
 to domestic use : — 
 
 A is a flat drum of tin, with a holt at tire 
 back, and a tube C at the edge ; withitfside 
 is a wheel of tin, formed only of several 
 arms B. This wheel fits with a pivot into a 
 hole at the back, and has a projecting pivot 
 in front. D is a moveable wooden wheel, 
 bearing so tightly upon the front pivot of B, 
 that when the wheel D is turned round, as 
 it may be by a handle at E, the wheel B 
 turns with it, and produces a constant draught 
 of air, which issuing from the mouth of C 
 may be urged against a fire, or as otherwise 
 wanted. 
 
 The following instrument, while it occupies 
 less room than the common forge bellows, 
 is upon the same construction, and equally 
 powerful. A is a handle to be moved up and 
 down. B B two arcs, upon which are two 
 chains which proceed downwards to the lower 
 part of C. Pulling down the handle then 
 lifts up C, and empties the air within it into 
 D, through a valve which belongs to the 
 centre board, as explained under the word 
 Bellows. D has a weight upon it, which is 
 always forcing the air through E to the fire. 
 
BL 
 
 BO 
 
 The handle being let go, the weight F brings 
 C down again, ready for a fresh supply, so 
 that a Constant stream of air is kept up. 
 
 Bx-ow-PiPE. An instrument to produce a 
 small and constant stream of wind, chiefly 
 required to increase the heat of a small flame, 
 as that of a lamp or candle. The simplest 
 blow -pipes are used by blowing into them by 
 the mouth, as the following : — 
 
 A is a tapering tube, used by jewellers and 
 others in soldering and melting small por- 
 tions of metal. B is for the same purpose ; 
 its particular form is that which was suggested 
 and approved by Dr.Wollaston : it is made 
 in two or three joints for the greater conve- 
 nience of carriage. C has a bulb on the 
 stem, for the purpose of retaining the mois- 
 ture of the breath. It is called, from its 
 inventor, Bergman's blow-pipe. D is an 
 improvement upon this : it consumes the 
 breath at the end, and has a moveable jet : 
 it is called Pepys's blow-pipe. E is the form 
 used by Dr. Black. 
 
 For the compound blow-pipes, (see Glass- 
 Blower's Tahley Gumey, Tulley, 8fc. 8fc.) 
 
 Blowing Valve. A small hole and valve, 
 placed near the bottom of the condenser ot 
 Watts'^ engine, to liberate the air which may 
 occupy this vessel before the engine is put to 
 work ; it is driven out as soon as the steam 
 from the cylinder tushes in. 
 
 Blubber. The fat which invests the bodies 
 of all large cetaceous fishes, serving to fur- 
 nish train oil, which it does by boiling. A 
 large whale will yield from 3 to 4 tons weight, 
 or about 1000 gallons. 
 
 Blue Powder. (See Powder Blue and 
 Stone Blue.) 
 
 Blue. One of the three primary colors ; 
 mixed with red it makes a purple, with yel- 
 low a green. It is a cool color, and harmo- 
 nizes well with most others. Its contrast or 
 accidental color is orange. The principal 
 blues used by the painter are ultra-marine, 
 bice, Prussian blue, and indigo. 
 
 Blunging. The art of mixing or kneading 
 clay for the potter's use. 
 
 Blue Dye. (See Indigo, Prussian Blue, 
 Logwood, 8fc.) 
 
 Blue Vitriol. Sulphate of copper. 
 
 Board. A piece of timber of an oblong 
 form, of any length, generally more than 
 4 inches broad and less than 2 inches thick. 
 When one edge is cut thicker than the other, 
 such boards are called feather-edged ; when 
 broader than 9 inches they are called ^/cnyt*,- 
 if narrow they are liattens^ As imported, 
 that is, 2^ or 3 inches thick, they are called 
 deals. 
 
 Boasting. In sculpture or carving is the 
 rough cutting of a stone to form the outline 
 of a statue, or an ornament. 
 
 BoAz's Steam Engine. An application 
 of the steam engines of Savory and Papiu, 
 by which water can be raised without coa- 
 densing the steam. 
 
 A is the steam cylinder, supplied by the 
 pipe C. B is the floating piston, attached to 
 a piston rod in A. Da waste steam cock. 
 F a pipe, which generally contains hot water. 
 
BO 
 
 E a valve, opening from the well upwards. 
 G the eduction pipe, conveying the water 
 upwards to the reservoir J, through a valve 
 at top. The air which accumulates in the 
 receiver escapes through I. H is the ex- 
 hausting vessel. The whole being filled with 
 mercury and water, (as shown in the shading 
 of the cut ;) shut the cock D, and open C. 
 The steam will press upon the piston, and 
 drive the mercury into H, and this will drive 
 before if the water above, and that through- 
 out the whole length of F and G into the 
 cistern J. When the piston is depressed to 
 the bottom of A, a tappit or arm attached to 
 it opens D, shuts C, and the mercury there- 
 fore, from its gravity, recovers its first posi- 
 tion, and raises B, leaving a vacuum in G, 
 which is filled up by the valve E opening, 
 and admitting the water of the well, which 
 is pressed into it by the external atmosphere. 
 
 Bob. a round ball ; the lower termination 
 of a pendulum is thus called, as is the ball 
 at the end of a string, used in levels, &c. 
 by workmen ; called in that case a plumb- 
 line bob. 
 
 Body, or Solid, is any thing which has 
 three dimensions ; length, breadth, and thick- 
 ness. Bodies are either soft, hard, or elas- 
 tic ; and either solid, fluid, or gaseous. 
 
 Regular Bodies, or Platonic Bodies. 
 In geometry are such as have all their sides, 
 angles, and planes, similar and equal ; of 
 which there are only the five following : — 
 
 1. Tetrahedon, contained under 4 equi- 
 lateral triangles. 
 
 2. Hexaedron, or cube, contained under 
 6 squares. 
 
 3. Octaedron, contained under 8 triangles. 
 
 4. Dodecaedron, contained under 12 pen- 
 tagons. 
 
 5. Icosaedron, contained under 20 trian- 
 gles. 
 
 Boiler. Any vessel in which a liquid is 
 boiled, more especially if of a large size. 
 The common household boilers are kettles, 
 saucepans, 8fc. ; that employed by the dyer, 
 brewer, &c., is called a copper; that made 
 use of by the sugar refiner is styled a pan ; 
 and that which distillers use is a still ; while 
 many articles used in the arts and in science, 
 for analogous purposes, are known by the 
 names of retort, alembic, boiler, digester, 
 &c. 
 
 Boiler, Steam Engine. Tliat part of the 
 steam engine in which the steam is generated- 
 Boilers are almost as varied in form as the 
 mechanical part of the ergines themselves. 
 The following, which from its shape is called 
 the waggon boiler, explains its general struc- 
 ture, and the various appendages usually 
 attached to it. 
 
 A is the boiler itself, formed of plates 
 of wrought iron, well secured together by 
 bolts. (Tlie side of that in the cut is 
 
 ]^o 
 
 taken away to show the internal structure.) 
 B is the pipe to convey the steam to the 
 
 engine. C is a pipe to supply the boiler 
 with water. When the supply of steam is 
 too rapid, it forces the water up the bottom 
 of the pipe C ; this raises the weight within 
 it, and lets fall the damper J, thereby 
 decreasing the fire. D is the float, connected 
 by a wire with a ball above, and that by a 
 rod to the lever K. Wlien the water in 
 the boiler is too low, the float pulls the wire 
 or rod, and turns the cock at K, letting 
 more water in from the pipe L, which leads 
 to C, and thence to the boiler. When there 
 is enough admitted, the float rises, and turns 
 oif the cock K. E is a safety valve ; when 
 the steam is too high it raises the weight 
 within the pipe, and escapes into the chim- 
 ney. F and G are guage pipes. H is the 
 air valve, fixed to a large flat iron plate called 
 the man-hole. I is the mercurial guage. 
 For the full description of these various parts, 
 see their respective names, AirVahe, Floaty 
 Guage Pipes, 8fc. For other boilers, see 
 Steam Engine, 8fe. 
 
 Boiling Point. That degree of heat at 
 whicfh a liquid boils. The boiling pomts of 
 some common liquids are as follows, sup- 
 posing them to be in the usual state of the 
 air, and not in a condensed or rarefied at- 
 mosphere. 
 
 Ether ..100°Fahr. 
 Milk.... „ 
 
 Sulphur.. 570 „ 
 Mercury 656 ,, 
 Alcohol ..173-5 „ 
 Boletates. Salts 
 
 Water ..212°Fahr. 
 
 Oil of Tur- 
 pentine 316 „ 
 
 Linseed 
 
 Oil. ... 640 „ 
 
 formed of the boletic 
 
 acid, and various bases. 
 
 Boletic Acid. An acid discovered by 
 M. Braconnot in the juice of the boletus 
 pseudo-ignearius. 
 
 Bologna Phials, or Proofs, are small 
 round bottles of unannealed glass, which fly 
 to pieces directly anything angular is dropped 
 into them. 
 
BO 
 
 BO 
 
 BoLOGNiAN Phosphorus. (See Bolog- 
 nian Stone.) 
 
 BoLOGNiAN Stone. The ponderous spar 
 or sulphate of barytes ; remarkable for its 
 making the Bolognian phosphorus, which is 
 thus prepared : — Let the stone be first made 
 red hot, then finely powdered, and made into 
 a paste with gum water. Cut this into small 
 pieces, and expose them to the heat of a wind 
 furnace, by placing them loose among some 
 powdered charcoal ; when afterwards exposed 
 for a few minutes to the sun's light, the 
 pieces will become extremely luminous — 
 giving light enough in the dark to read by. 
 
 Bolster. That part of a knife blade 
 which joins and abuts upon the end of the 
 handle. In architecture, the rolls forming 
 the ends or sides of the Ionic capital ai'e 
 called bolsters. 
 
 Bolting Machine. That part of the 
 machinery of a flour mill by which the flour 
 is separated from the chaflf. 
 
 Bolton's Engine. (See Watt.) 
 
 BoMBic. An acid discovered by M.Chaus- 
 sier in the silk -worm. It is of no known use. 
 
 Bond. A method of laying bricks or stones, 
 so that the joints shall be as far distant from 
 each other as possible, that the whole may 
 be firmly knit together. No. 1 is called 
 English bond. No. 2, Flemish bond. 
 
 Bonders. Bond Stones, Binding Stones, 
 Through Stones, Perpent Stones, are used 
 where rough stone walls are bo\md with cut 
 stone, and are inserted at intervals, for the 
 purpose of binding the facing to the backing, 
 or rough stone wall behind it. 
 
 Bond Timber. Beams of timber put 
 lengthways in a wall to bind the brick-work 
 together, and distribute the pressure of the 
 superincumbent weight more equally. 
 
 Bone Phosphate. Sub-phosphate of 
 lime. 
 
 BoNE„ to. An expression used by artizans 
 to signify looking down a flat surface, in 
 order to see if it is straight. 
 
 Bonnet. A hole formed in iron pipes, 
 and furnished with a sliding lid for the pur- 
 pose of clearing out the inside when requisite. 
 
 Bookbinding. The art of sewing the 
 sheets of a book together, and furnishing 
 them with a cover. (See Cutting Press, 
 Sewing Board, Plough, Sfc.) 
 
 Booms. Pieces of timber left to float in 
 front of coffer dams, to keep off the shoCkg 
 of vessels. They are usually secured to the 
 piles by chains, and rise and fall with the tide. 
 Such beams or booms are sometimes thrown 
 across the mouth of harbours for temporary 
 purposes of defence or protection. 
 
 BoRACic Acid. Sedative Salt. The only 
 known combination of borax and oxygen. 
 It is obtained bv dissolving borax in hot 
 water, and afterwards adding half its weight 
 of sulphuric acid. As the solution cools, 
 white scaly crystals of boracic acid appear, 
 which to be rendered pure must be melted, 
 and made red hot. The acid will then be 
 found fused into a white transparent glass. 
 Boracic acid unites with the alkalis, earths, 
 and many of th.e metals.. It communicates 
 a green color to the flame of spirits of wine, 
 or when ignited with gimpowder, for which 
 purpose it is used in the theatrical blue fires, 
 and in fire-works. 
 
 Borates. Combinations of boracic acid 
 with alkaline, earthy and metallic bases. 
 The borate of soda, or borax, is the only 
 one extensively used in the arts. 
 
 Borax. Borate of Soda, is imported 
 from India in an impure state, under the 
 name of tincal, pounxa, or chrysocolla. 
 It crystallizes in irregular hexagonal prisms, 
 slightly efflorescent. Its taste is alkaline 
 and styptic; soluble in 12 parts of cold 
 and 2 parts of boiling water. When heated 
 it loses its water of crystallization, and 
 becomes a porous powdery mass, called 
 Calcined Borax. It is decomposed by most 
 of the acids ; is valuable as a blow-pipe flux, 
 and instead of ipsin in soldering. Clothing 
 dipped in its solution is rendered to a certain 
 extent incombustible : it is the principal 
 source whence boracic acid is obtained. 
 
 BoRAXATED Tartar. If 2 parts by 
 weight of borax be added to 5 of crystals of 
 tartar, (bitartrate of potass,) the tartar be- 
 comes much more soluble than before. The 
 solution evaporated to the consistence of 
 honey, concretes on cooling into La Fevre's 
 soluble cream of tartar, or sal-gummosum, 
 which is the tartarus boraxatus of old 
 authors. 
 
 Boreal Signs. In astronomy, those 
 signs of the zodiac north of the equator. 
 They are Aries, Taurus, Gemini, Cancer, 
 Leo, and Virgo. The sun passes successively 
 through these during our summer months, 
 from March to September. 
 
 Boring. A vertical section, made in the 
 earth for the purpose of obtaining water. 
 Also the operation of drilling holes by a cir* 
 cular motion of a cutting tool. 
 
BO 
 
 BO 
 
 BoKiNG Collar. An appendage to the 
 lathe, used instead of the back poppit to 
 hold one end of a piece of 
 wood which is to be bored. 
 It fits on to the bed of the 
 lathe, and is fastened there 
 by a screw or wedge beneath ; 
 its upper part is a round iron 
 plate,with a circle of various- 
 sized tapering holes in it. 
 The plate is moveable around 
 a central pin or bolt, so that 
 any reqviired hole may be 
 uppermost ; and when so 
 placed uppermost it is tight- 
 ened in that position by a 
 screw behind. The piece of 
 wood to be drilled is fixed to, 
 and turned by the mandril at one end, and 
 works in or against that hole of the collar 
 which has been placed at top, and which 
 from the proper arrangement of the holes is 
 exactly even with it. A drill or boring bit is 
 held to the centre of the wood, as it appears 
 thro\igh the hole, and being forced forwards 
 cuts a hole exactly up the centre of the wood 
 which tfie mandrU has put in motion. 
 
 BoROFLUORiDES. Compounds formed by 
 the union of the fluoride of boron, or fluo- 
 boric gas, with either potassium, sodium, or 
 barium. 
 
 BoROHYDROFLUORic AciD. A Combi- 
 nation of the boracic and fluoric acids with 
 water. It does not corrode glass, as the 
 fluoric acid alone does, but is rapidly de- 
 structive to all organic substances, making 
 them to appear as if scorched. 
 
 Boron. The metallic base of boracic acid, 
 discovered in 1807 by Sir H. Davy. It is 
 obtained by heating in a copper tube 2 parts 
 of potassium, with 1 of boracic acid, pre-' 
 viously fused and pounded. The fused mat- 
 ters are washed out of the tube with water, 
 and the whole put upon a filter. The boron 
 remains in the form of a brown, insipid, in- 
 soluble powder ; a non-conductor of elec- 
 tricity ; not acted upon by water, air, alco- 
 hol, ether, or oils, but when heated nearly to 
 redness, it burns with difficulty into boracic 
 acid, which is its only known combination 
 with oxygen. It unites with chlorine and 
 fluorine. 
 
 BoRtJRETS. Compounds of boron with 
 the metals. 
 
 Boss. Any round projecting mass of en- 
 graved stone-work, particularly applied to 
 the knotted ornaments whiqh are placed upon 
 the intersection of the ribs of a groined roof. 
 BossAGE. A projection of stones laid 
 rough in a building, to be afterwards sculp- 
 tured or cut into mouldings. 
 
 Boss's Floating Coil. A simple gaU 
 vanic apparatus, which when placed in aci- 
 dulated water turns spontaneously, so as to 
 
 place itself north or south, or accordant to 
 the magnetic meridian. It consists of a coil 
 of wire, the ends of which are brought 
 through the coil, and are terminated by two 
 plates of metal, about an inch square each ; 
 one plate being of zinc, the other of copper. 
 Now when this instrument is in use, it is 
 necessary to suspend it by a thread, or sup- 
 port it by a cork at each end, lest it should 
 sink. (See Ampere, De la Rive, and Marsh.) 
 
 Bottle Director. An electrical instru- 
 ment, made out of a long narrow hollow 
 flask, furnished with a brass cap, wire, and 
 ball, the wire going down to the end on the 
 inside ; the inside is lined for a certain dis- 
 tance up with brass filings, by pouring into 
 the flask a little gum water, and turning the 
 flask about till the gum water touches every 
 part of the glass where the filings are to 
 reach, but no other part ; then pouring in 
 the filings they adhere. The outside to the 
 same height is covered with tin-foil, pasted 
 on. The instrument is charged in the same 
 manner as the Ley den jar, (which see ;) and 
 will give a shock according to its capacity. 
 It is scarcely used but for amusement. 
 
 Bottle, Electric. (See Leyden Jar.) 
 Bottle, Hydrogen Gas. An apparatus 
 for making hydrogen gas. It is formed as 
 follows, and is furnished with a bent tube, 
 in order that it may be passed under the 
 shelf of the pneumatic trough, and the gas 
 thereby purified. 
 
 BoVEY Coal, Fossil wood, impregnated 
 with petroleum or bitumen, and frequently 
 containing pyrites, alum, and vitriol. 
 
 It is 
 
BO 
 
 BR 
 
 of a blackish brovai color and lamellar struc- 
 ture, generally flexible when first dug up. 
 
 Boulders. Round pebbles, or small de- 
 tached rocks. 
 
 Boulder Paving, is formed of unhewn 
 round pebbles. 
 
 Boulder Walls. Those made of round 
 flints, laid in strong mortar. 
 
 Bow Compass. A small pair of com- 
 passes for drawing small circles with ink. 
 
 Bow Drill. A drill which is worked by 
 a bow and string. (See Drill Bow.) 
 
 Bow Pen. A steel ruling pen ; the part 
 holding the ink being foi-med of two cheeks, 
 bowed out towards the middle, and regulated 
 by a screw. 
 
 Bow Saw, or Frame Saw. (See Sav).) 
 Bow String Bridge, or Tension 
 Bridge. A kind of suspension bridge, the 
 roadway being suspended ft-om iron rods, 
 and these depending from an iron arch, as 
 represented below. 
 
 Bowtells. The shafts of a clustered pillar. 
 
 Boyle's Fuming Liquor. Hydrogu- 
 retted sulphuret of ammonia. 
 
 Boyle's Thermometer. One of the 
 earlier, and consequently more imperfect 
 thermometers. It is, however, 
 superior to any previously in use. 
 It is simply a glass tube, open at 
 both ends ; one end cemented 
 into a bottle half full of some 
 liquid. The cement preventing 
 any escape of the air which is 
 above the liquid, amy increase of 
 t;^mperature rarefies the air, and 
 drives the liquid further up the 
 tube ; on the contrary, a decrease 
 of temperature occasions it to 
 subside. There was no scale at- 
 tached to this thermometer. 
 
 Boylean Vacuum. Such a vacuum as is 
 produced by an air pump. 
 
 Box Camera. (See Camera ObscuraJ) 
 
 Boxings of a Window. Two recesses 
 into which inside shutters .are folded, so as 
 not to project into the room. 
 
 Brace. A curved instrument, of iron or 
 wood, to eceive and move small boring 
 tools, called bitts. 
 
 Braces,^ or Struts. The name given to 
 the timbers of a roof which serve to support 
 the principal rafters ; the lower ends of them 
 rest upon the king post or queen post. 
 
 Bracket. A projection from a wall, for 
 the purpose of supporting a statue, clock, 
 or any other object. In architecture it is 
 often synonymous with corbel. 
 
 Brady's Balance. An instrument for 
 weighing common goods, upon the principle 
 of the bent lever. 
 
 B C D is an iron frame, being much thicker 
 and heavier towards B than in the other parts. 
 It is supported upon a fulcrum G, and F is 
 a moveable suspender, to which a scale or 
 hook is attached, to receive the substance to 
 be weighed. There are different positions, 
 H F and I, in which this suspender may be 
 placed, and for which there are distinct 
 graduated scales, two of them following each 
 other on the lower arc of the frame at D. 
 W'hen a weight is placed in the dish, the 
 machine is turned round the fulcrum G, and 
 the side C descends, until equilibrium is 
 established, and the weight is read off* from 
 that scale which corresponds to the position 
 of the suspender. 
 
 Brake's System. (See ITyc^oean/Sy^/em.) 
 
 Braided. Any thing platted or twisted in 
 
 an ornamental manner, such as hair, &c. 
 
 The following ornament, used in architecture, 
 
 is called bi-aided. 
 
 Brake. A machine for separating the 
 cuticle or outer skin from the flax plant. 
 
 L 
 
BR 
 
 BU 
 
 Bhamah's Hydraulic 
 most valuable instrument 
 below : — 
 
 Press. This 
 is represented 
 
 A is an ornamental boiler, in the shape of 
 a bust. B is a float wheel, turned round by 
 the steam issuing from a pipe inserted into 
 the mouth of the figure. The wheel B com- 
 
 Its action depends upon the principle that 
 fluids transmit pressure equally in all di- 
 rections. A solid piston E is constructed so 
 as to move Water-tight in a cylinder. The 
 space beneath the piston is filled v/ith water, 
 and communicates by a small pipe with a 
 forcing pump, worked by the piston B, by 
 means of the lever A, and by which the 
 water, which is contained in the cistern G, 
 is forced through the valve D into the large 
 cylinder. The large piston being thereby 
 driven up, carries with it the bed H, and 
 presses closely together whatever may be 
 above it. Whatever pressure is exerted upon 
 B is transferred to E, and is increased ac- 
 cording to the relative size of the two pis- 
 tons. Suppose, for example, the piston at B 
 to have a superficial area of 1 inch, and the 
 large cylinder of 100 inches, then every 
 10 pounds pressure put upon B will be in- 
 creased by E 100-fold, and become 1000 
 pounds ; and as a person may exert a force 
 of 500 on the lever, his weight alone will 
 give a pressure 1000 x 500 pounds, or more 
 than 22 tons, and that with a pump, the 
 large cylinder of which is not more than 
 12 inches diameter ; and by decreasing the 
 smaller tube, from 1 inch diameter to half an 
 inch, the power will be increased four-fold, 
 or to nearly 90 tons. 
 
 Branca's Engine. One of the earlier 
 steam engines, invented by Giovanni Branca 
 in the beginning of the seventeenth century. 
 The following is a picturesque view of the 
 engine as applicable to pumping. 
 
 municates motion to the trundle C, that to 
 the wheel D, and also to the pump rod E. 
 It was employed by Branca in grinding, or 
 rather in giving motion to the pounders of a 
 mill for pounding drugs. 
 
 Branch Chuck. A chuck formed of 
 four branches, turned up at the ends, and 
 these ends furnished with a screw to each. 
 The use of this chuck is almost superseded by 
 the surface chuck, which is not only appli- 
 cable to the same purposes, but many others. 
 
 Branch of a Curve. Such parts of it 
 as when produced do not return into the 
 curve again, such as the legs of the parabola 
 and hyperbola. 
 
 Brandrith. a fence round the mouth of 
 a well. 
 
 Brandy. A well-known liquor, distilled 
 from spoiled wines, husks of grapes, &c., 
 chiefly in the wine countries. Its peculiar 
 flavor arises from the empyreumatic oil of 
 the fruit. It is like all distilled liquors per- 
 fectly colorless, until rendered dark with 
 burnt sugar. 
 
 Brass. An alloy, consisting of different 
 proportions of copper and zinc ; the zinc 
 being about one-third the weight of the 
 copper. 
 
 Brazil Wood. The wood of one species 
 of the Csesalpina. It gives out its color to 
 water, producing a fine, though fleeting red : 
 it is that from which red ink is manufactured. 
 
BR 
 
 BR 
 
 Brasses. Monumental slabs of brass, 
 much used in the middle ages ; and which 
 from the accuracy of the engraving of cos- 
 tume and inscriptions are valuable in ascer- 
 taining dates, &c. They were general to- 
 wards the close of the fourteenth century. 
 
 Brazing. The soldering together of me- 
 tals by means of an alloy, of which brass 
 forms the principal ingredient. On account 
 of the great heat requisite to melt brass, it 
 is not used as a solder, except for the metals 
 which are fused with difficulty, such as iron, 
 copper, &c. Articles of jewellery, though 
 the parts are joined together with brass, are 
 said to be soldered, and not brazed. 
 
 Branched Work. A name given to the 
 carved and sculptured leaves and branches 
 in monuments arid friezes. 
 
 Breaking SauARE. Asmall square phial, 
 holding about 3 ounces, and made of ex- 
 ceedingly thin glass. The use of the breaking 
 square is to show the elasticity and pressure 
 of the atmospherd ; thus, fasten to the 
 mouth of one of them a stop cock, fitting 
 the hole on the plate of the air pump, to 
 which attach it ; then extracting the air 
 from within, the external pressure will crush 
 the breaking square ; or else stop up the 
 mouth of another, and put it within the 
 receiver of the pump, exhaust the air from 
 around it, when the pressure of the air 
 within the bottle will burst it. 
 
 Break, or Convoy. A drag applied to 
 uxe~Wheels of railway carriages, the fly wheel 
 of cranes, &c., to check their velocity in 
 passing down hills, &c. ; also to stop the 
 motion of machinery. It is simply a block 
 of wood, made to press upon one of the 
 wheels in motion, by means of a lever held 
 in the conductor's hand. In wheel carriages 
 it is an iron shoe, in which one of the wheels 
 is placed, suffering that to slide along the 
 road rather than the wheel to turn. 
 
 Break. A projection from, or recess, in 
 the wall of a building. 
 
 Break Joint. (See Bond.) 
 Breakwater. An artificial embankment, 
 made to break the force of the waves, to 
 protect the entrances of harbours, &c. 
 
 Breakwater Glacis, or Storm Pave- 
 ment. A stone paving next the sea. In the 
 erection of piers they are mostly much 
 sloped, and built of large stones, that they 
 may resist better the force of the waves. 
 
 Breasts. The name given to the bushes 
 connected with small shafts or spindles. 
 
 Breasting. The circular sweep of ma- 
 sonry which surrounds the shuttle side of a 
 breast wheel. 
 
 Breast Plate. A small piece of steel, 
 with holes to receive the end of a drill. 
 When in use it is named breast plate, because 
 of being held against the breast. 
 
 Break Wheel. A wheel with breaks or 
 
 wipers upon the circumference. The use of 
 such a contrivance will be seen by the cut , 
 in which the breaks are employed to raise 
 and let fall alternately the handle of a sledge 
 hammer. 
 
 Breast Wheel. A water wheel,"^ which 
 receives its motion from a stream of water 
 flowing on to the breast or side of it, and 
 then descending, bears by its weight upon 
 the lower part of the wheel, as represented 
 below. 
 
 The quantity of water is regulated by a 
 sluice at the end of the stream. The chan- 
 nel of brick-work in which the wheel turns, 
 and which is called the breasting, is semi- 
 circular, and so close to the wheel, that the 
 water has no passage but by the wheel itself. 
 The wheel is made of float boards, which 
 have backs to them, to prevent the escape 
 of the water towards the inside of the wheel. 
 
 Breccia, or Breccia Marble. A con- 
 glomerated stone, seemingly made up of 
 broken fragments of various stones united 
 together by a hardened cement. 
 
 BREauET's Pyrometer, or Metallic 
 Thermometek, consists of a helix formed 
 of three strips of three metals, of different 
 degrees of expansibility. The exterior strip 
 is of silver, the interior of platina, and 
 between them is one of gold. Two only are 
 necessary to the perfect action of the in- 
 strument, but from the difference of the 
 expansibility between silver and platina, they 
 would be liable to separate by sudden changes 
 of temperature ; and a thin plate of gold, 
 which is of intermediate expansibility, is 
 interposed. The whole forms a wire of about 
 one hundredth of an inch in thickness. The 
 upper extremity of the helix is fastened to 
 the extremity of the brass arm B, which by 
 its form insulates the helLx, and permits its 
 
BR 
 
 BR 
 
 coiling and uncoiling freely. To its lower 
 extremity is attached a gold needle, which 
 moves round a graduated scale of degrees, 
 and thereby indicates the degree of tempe- 
 rature ; it being proved by experiment that 
 equal increase of temperature produces 
 equality of metallic expansion. The sen- 
 sibility of the instrument is said to be very 
 great, and it is the more valuable because of 
 not being affected by changes in the density 
 of the atmosphere, as the common thermo- 
 meter is. 
 
 Breech, or Breeching. That part of a 
 gun barrel or cannon, which closes it at that 
 end nearest the touch-hole. 
 
 Brestsummer. Bressummer. a beam 
 placed horizontally to support an upper wall 
 or partition. The lower beam of a church 
 gallery, and that over a shop window, are 
 brestsummers. 
 
 Brewster's Circular Pearl Micro- 
 meter, consists of a ring of mother of pearl, 
 fixed on its outer edge to a diaphragm D D, 
 at the end of a piece of brass tube, which is 
 capable of being adjusted to the anterior 
 
 focus of the object glass of a microscope or 
 telescope. The inner circumference of the 
 pearl is divided into 360" degrees, or equal 
 
 parts. The greatest angle that this micro- 
 meter will measure must first be ascertained 
 by experiment, which will be according to 
 the length of the focus, compared with the 
 internal diameter of the pearl ring. This 
 being known, a table is easily constructed to 
 show, by inspection, the angle subtended by 
 any two points or degrees of the circumfe- 
 rence the object to be measured will reach, 
 as is seen at E. The whole diameter or A B 
 being known. 
 
 Brewster's Compound Lenses. Con- 
 trivances to prevent the achromatism of the 
 ordinary lenses of microscopes, at the same 
 time that light should not be lost. They 
 are of two forms ; in one a channel is cut 
 round the sides of a solid lens, as represented 
 in Fig. 2. In the other form, two double' 
 convex lenses are made i^e of, so placed as 
 to form a double concrfW^ens in the centre, 
 which centre is filled with a fluid differing 
 from glass in its refractive and dispersive 
 power, so as to correct both the spherical 
 and achromatic aberration. This combi- 
 nation is shown in Fig. 1. 
 
 Brewster's Fluid Lenses. Dr.Brews- 
 ter describes the following as the best method 
 of constructing fluid microscopes or lenses. 
 " Take Canada balsam, balsam of copaiva, or 
 pure turpentine varnish, and drop either of 
 them on a parallel piece of glass, when a 
 plano-convex lens will be formed. The 
 power may be varied by the quantity of fluid 
 employed, or by allowing the plate of glass 
 to be horizontal with the drop above or be- 
 low it ; thus, if the plate be uppermost, the 
 gravity of the fluid will make it more con- 
 vex ; if the drop be above the plate the lens 
 will be flattened. When the first of these 
 substances is used it soon hardens, and the 
 lens is very durable." Dr. Brewster further 
 informs us, that he has made both the ob- 
 ject and eye glasses of compound micro- 
 scopes in this manner, which performed ex- 
 tremely well, and lasted a considerable time. 
 
 Brewster's Teinoscope, Kaleidoscope, 
 and Object Glass. See these names. 
 
 Brick. A kind of artificial stone, formed 
 of a mixture of clay, sand, and ashes, hard- 
 ened by long continued burning. 
 
 Brick-nogging. a wall in which bricks 
 are built up between quarterings, so as to 
 fill up the interstices ; this work is usually 
 the thickness of a brick. 
 
 Brick, Oil of. The liquor which comes 
 over in the destructive distillation of various 
 of the fixed oils ; these are decomposed at a 
 little above their boiling point, or at about 
 
BR 
 
 BR 
 
 600° ; the vapour that now passes over is 
 acrid, sour, and empyreumatic. It is called 
 oil of brick because a brick was often soaked 
 in the oil, and then submitted to distillation, 
 it being thought that it derived some part of 
 its peciQiar properties from that circumstance. 
 It is much used by seal engravers and gem 
 cutters as an oil. 
 
 Bridge. A pathway erected over a river, 
 
 a road, canal, &c., in order that a passage 
 
 may be made from the one side to the other. 
 
 Bridges may be made of timber, iron, brick, 
 
 or stone. The English excel all nations in 
 
 their bridges ; Waterloo bridge and London 
 
 bridge, the suspension bridge across the 
 
 Menai Straits, and numerous others, are 
 
 ^ the admiration of the world. The extreme 
 
 r ■ supports of a bridge, whether consisting of 
 
 f one or of many arches, are called abutments, 
 
 y or hutments. The parts upright between 
 
 these, if any, are called piers or pillars. Tlie 
 
 foundations upon which these rest, if widened 
 
 out so as to throw off the force of the stream, 
 
 are called starlings, and the fences on the 
 
 sides of the roadway are called parapets. 
 
 Bridge Stone. A stone laid from the 
 pavement to the entrance door of a house 
 over a simk area, not supported by an arch.. 
 Bridle-Rein Packing. A term applied 
 by engineers to signify the placing of a strip 
 of leather, or a loose rope of tow, around a 
 piston, to make it fit tightly to the cylinder 
 in which it works. It was used in Beighton's 
 steam engine. 
 
 Bright. Lucid ; glittering. A picture 
 is said to be bright when the lights so much 
 prevail as to overcome the shadows, and are 
 kept so clear and distinct as to produce a 
 brilliant appearance. 
 
 Brimstone. (See Sulphur.) 
 Brionin. a crystallizable principle, found 
 in white briony ; procured by treating the 
 expressed juice with ammonia. — Vanquelin. 
 British Gum. The trivial name given to 
 starch, altered by calcination in an oven, 
 whereby it assumes the appearance and ac- 
 quires the properties of gum. It is used as 
 a dressing to numerous woven fabrics, as 
 well as to thicken the colors used by the calico 
 printer. 
 
 Britannia Metal, or Tutania. Melt 
 together 4 ounces of plate brass, and 4 
 ounces of tin ; when melted add 4 ounces 
 of bismuth, and 4 ounces of regulus of 
 antimony. 
 
 Broach. An old English term for a spire ; 
 also used by some writers for the small tur- 
 rets or spires which surround a larger one. 
 Broken Number. The same as fraction. 
 Bronze consists of from 6 to 12 parts 
 of tin to 100 parts of copper. This alloy is 
 heavier than copper, and possesses more 
 tenacity : it is more fusible, and less liable 
 to be altered by exposure to the air. It is 
 
 used for medals, different articles of orna- 
 ment and domestic use, cannon, &c. 
 
 Bronze, also denotes any piece of sculp- 
 ture made of bronze metal, as statues, busts, 
 &c., whether in imitation of the antique, or 
 representing a modern prototype. 
 
 Bronze, to. To give to wood, plaster, 
 metal, &c., such a surface as to mal^e them 
 appear as if made of bronze. This .jls done 
 by means of a bronze powder ; th^ article 
 being first painted and varnished, and the 
 powder then sifted over such parts of it aa 
 are to appear metallic. It is usually done 
 on metallic articles, such as lamp stands, &c., 
 by slightly warming them, and then washing 
 them over with a liquid which slightly cor- 
 rodes the surface, (See Brotvning, 8fc.) 
 
 Bronze Liquid. Melt in 14 ounces of 
 vinegar 2 drams of sal-ammoniac, and half 
 a dram of salt of sorrel, (binoxalate of 
 potass ;) rub this over the object to be 
 bronzed with a soft brush, till the required 
 tint is obtained. Liquid to imitate antique 
 bronzes is made by dissolving 1 part of sal- 
 ammoniac, 3 parts of cream of tartar, and 
 6 parts of common salt, in 12 parts of hot 
 water ; mixing with the solution 8 parts of 
 a strong solution of sulphate of copper. 
 
 Bronze Bowlders are metallic powders 
 capable of communicating a bronze-like 
 color to those objects over which they 
 are spread. Aurum musivum, or the bi- 
 sulphuret of tin, is the most common, and is 
 used for plaster figures, &c. Dutch leaf 
 ground to a paste with honey, and afterwards 
 washed away from the honey, makes a fine 
 bronze powder. Copper powder, as pre- 
 cipitated from a solution of the nitrate of 
 copper by clean sheets of iron, is another. 
 
 Bronzing Salt. Chloride" of antimony ; 
 so called from its general use in browning 
 or bronzing gun barrels, &c. 
 
 Brooch. A term used by painters to sig- 
 nify a painting all of one color, as a sepia 
 painting, an Indian ink painting, &c. 
 
 Brown. A color between red and black, 
 or yellow and black. (See Umber, Spanish 
 Brown, Bistre, Cologne Earth, Sfc.) 
 
 Browning, or Bronzing, gun carrels, 
 or other iron articles, may be done by washing 
 them over with dilute, or muriatic, acid. 
 When somewhat corroded, they are to be 
 rubbed smooth and varnished : — or the fol- 
 lowing method may be recommended ; 
 Grind up the butter (chloride,) of antimony, 
 with olive oil, rub it upon the iron slightly 
 heated ; and afterwards expose it to the air, 
 till the desired color is obtained. It is 
 afterwards to be varnished. 
 
 Brucia. An alkaline substance, found in 
 the spurious angostura bax-k. It may be 
 made as follows : — boil the bark in acidulated 
 water, treat with quick-lime in excess, to 
 decompose the fluid ; treat the deposit with 
 
BU 
 
 BU 
 
 alcohol and distil ; the brucia will remain. 
 {Magendie,) 
 
 BauNswiCK Greex. Chloride, or sub- 
 muriate of copper ; it may be made by adding 
 oxyde of copper to a solution of chlorine, 
 or by exposing to the atmosphere slips of 
 copper partially immersed in muriatic acid. 
 It is a color extensively used by the house 
 painter. 
 
 Brush, Electrical, signifies the brush- 
 shaped emanation of electric light, which 
 issues from all sharp or pointed bodies 
 which are strongly electrified positively. 
 
 Brush Wheels. Such wheels as move 
 each other without cogs or teeth. Often 
 the rubbing surfaces are covered with stiff 
 hairs as a brush is formed, hence the name ; 
 but sometimes they are covered with woollen 
 cloth or buff leather. For light pieces of 
 machinery, where noise would be disagree- 
 able, such wheels are valuable ; for example, 
 in those machines used by astronomical 
 lecturers to illustrate the subject of planetary 
 motion, &c. Brush wheels may communicate 
 motion either in the same direction as the 
 wheel from which the impulse arises, as is 
 seen in F, or the motion may be continued 
 at a different angle, as is seen at A and E. 
 In the cut it will be seen that the wheel C, 
 moving upon the spindle D, turns at the 
 same time the wheels A, E, and F. 
 
 Bucket, Electrical. A small metal 
 bucket, having at the bottom a tube, per- 
 forated with a fine hole. Water put into 
 this bucket will under ordinary circumstances 
 fall in single drops from the hole, but when 
 the bucket is suspended from the prime 
 conductor of an electrical machine, and 
 
 over-shot water wheel, and far superior 
 where the fall of water is considerable, and 
 the supply limited. 
 
 strongly electrified, the water issues in 
 numerous streams, which are luminous in 
 the dark. 
 
 Bucket Engine. A substitute for an 
 
 An endless chain, carrying a series of 
 buckets, is made to revolve on two wheels, 
 A B, called rag-wheels. The water flows 
 into the highest bucket, and when it 
 descends the next bucket takes its place 
 and is likewise filled, and thus every bucket 
 on one side is filled, while those on the 
 opposite side, being inverted, are empty ; 
 the chain of buckets is therefore constantly 
 carried round by the weight of the water. 
 
 BuDE Light. A lamp in which the flame 
 is urged to an intense brilliancy, by a sti-eam 
 of oxygen gas being made to permeate the 
 centre of the flame. The flame thus urged 
 gives the most vivid light, so much so that 
 one of a quarter of an inch diameter, and 
 which receives the oxygen through an 
 extremely minute orifice in the centre of 
 the flame, jdeld an infinitely greater light 
 than many candles. This light is the 
 invention of Mr. Gurney, and is called the 
 Bude light from his place of residence. 
 
 Buff. A small wheel, covered with buff 
 leather, used to polish cutlery upon, after 
 having been ground. 
 
 Buff Stick. A piece of wood, covered 
 with buff leather, used for polishing. 
 
 Buffing Apparatus. A contrivance for 
 receiving the shock of a coalition between 
 
 railway carriages, consisting of powerful 
 springs, inclosed in a case ; the springs 
 being compressed at the time of a coalition 
 
BU 
 
 3iU 
 
 by a rod attached to them, and which pro- 
 ceeding outwards, is terminated by cushions, 
 called buffs, to receive the first impact. 
 
 Buffon's BuiLT-ui Lenses. The difl&- 
 culty of procuring lenses of glass of a very 
 large size, such as is necessary for burning 
 glasses, induced Count Buffon to recommend 
 them to be made of separate pieces of glass, 
 as represented in the cut below, which shows 
 the front and the side view of one of the 
 built-up lenses ; or, as Dr. Brewster calls 
 them, polyzonal lenses. 
 
 The advantages of these lenses are, the 
 greater facility of getting pieces of glass to 
 make the various zones, than to make a 
 solid lens ; the less expense to repair it if a 
 part should be imperfect or broken ; the 
 less aberration there is in a lens of this 
 description than there would be in one made 
 of a solid piece of glass ; also the less 
 expense of grinding such a lens, because of 
 the large size of the tools requisite for a 
 solid lens : Count Buffon merely recom- 
 mended such lenses ; Dr. Brewster first 
 made them. 
 
 Buffon's Burning Mirror was a 
 concave mirror, 6 feet in diameter, com- 
 posed of 168 small mirrors, or flat pieces 
 of looking glass, 6 inches square. This 
 instrument was adapted to burn an object 
 either below or above it, each mu-ror being 
 moveable, so that by the means of three 
 screws it might be set to a proper inclination 
 for directing the rays of the sun towards 
 any given point. Wood by this burning 
 mirror was burnt even by the weak sun of 
 March, at a distance of 150 feet, and silver 
 melted at 50 feet. The burning mirrors 
 once used by the celebrated Archimedes, 
 were of a similar description, though in all 
 probability made of polished metal. 
 
 Buhl Work. The cutting out and in- 
 laying of fine strips of brass, silver, ivory, 
 &c., on the surface of cabinet and similar 
 work. 
 
 Building Beams. A term used by car- 
 penters to signify the making up of a very 
 large beam, by pinning and bolting together 
 several smaller ones. 
 
 Bullet. To alter the wards of a lock in 
 such a manner that they may be passable by 
 more than one key. 
 
 Bull's Eye. A small circular, or ellip- 
 tical window ; chiefly applied to those in the 
 gable or pediment of a building ; also any 
 similar shaped recess in such places, even 
 when filled by a clock. 
 
 Bull's Eye, or Dead Eye. A small 
 oval block of hard wood, without sheaves, 
 having a groove round the outer side, and 
 one or more holes in the middle. The isuU's 
 eye spindle, or under spindle of the air pump 
 rod, in the common parallel motion of a 
 steam engine ; so called because the air pump 
 rod must pass through a hole in it, which is 
 the bull's eye. 
 
 Bundle Pillar. A term sometimes ap- 
 plied to a pillar, or pier, with others of 
 smaller dimensions arranged round, and at- 
 tached to it. 
 
 Buoy. A floating mark to point out the 
 position of objects beneath the water ; also 
 any light body used to support in the water 
 another body, which would otherwise sink. 
 
 Burning Glass. A convex lens, because 
 it, from its nature, refracts the parallel rays 
 from the sun, and collects them into a 
 focus, thereby so concentrating their power 
 as to scorch, or melt, the object upon which 
 they are thrown. 
 
 Burning Mirror. A bright concave 
 surface of metal, or other material, which 
 collects into a focus any rays of heat 
 thrown upon it, and burns, or melts the 
 substance placed within the focus ; so also 
 such mirrors collect heat from a certain 
 focus, and transmit it from their surface in 
 parallel lines. If two such mirrors be oppo- 
 site each other, and a heated ball placed in 
 the focus of one, it will heat any object placed 
 in the focus of the other ; as is represented 
 in the following cut, where A is a red hot 
 iron ball, and B a cup of spirits of wine, 
 which it has inflamed. 
 
 
 j»i ^ 
 
 ^1 
 
 
 
 'b a| 
 
 Hi 
 
 
 
 
 \f 
 
 
 
 
 
 
 
 
 As burning mirrors may be made of any 
 focus, they may be made to inflame com- 
 bustible materials at any required distance, 
 even miles away. The most refractory 
 bodies have been melted in the focus of a 
 burning mirror exposed to the sun, when 
 subjected to its influence for only a few 
 seconds. (See Buffon.) 
 
 Burning Mountain. (See Volcano.') 
 Burning Zone. The torrid zone. 
 
BU 
 
 BU 
 
 Burnish. To polish any thing by rubbing 
 it with some smooth material harder than 
 itself. 
 
 Burton's, or Spanish Burton's. A 
 series of pulleys, in which every pulley 
 contains but a single sheave, and in which 
 there are as many ropes as moveable pulleys. 
 Much power is gained by a construction of 
 this kind ; but the peculiar form, and less 
 compactness of Spanish Burton's than of the 
 ordinary block, makes them unavailable on 
 ship-board, or for general purposes ; besides 
 which, they are much more expensive. 
 
 Burnisher. A tool for burnishing. 
 Burnishers are of various shapes and ma- 
 tei'iuls, according to the purpose to which 
 they are to be applied. The engraver's 
 burnisher is of steel, with a smooth tapering 
 point ; it is used by him to take out false 
 scratches, to soften what has been too 
 deeply engraven, &c. The burnisher used 
 by the gilder is made of agate, porphyry, 
 or other hard stone ; those used in the 
 general polishing of iron goods, is of 
 hardened steel. 
 
 Bush. A hole in the nave of a wheel ; or 
 more properly the steel, bell-metal, or brass 
 tube, or hollow box, which fits into the 
 centre of the wheel ; to bear better than the 
 wheel otherwise would do, the friction of 
 the axletree. 
 
 Bust. In sculpture, that portion of the 
 human figure which comprehends the head, 
 neck, and breast, with or without the 
 shoulders. 
 
 Butment. A contraction of abutment. 
 
 BuTMENT Cheeks. The solid parts on 
 each side of a mortice. 
 
 Butter of Antimont. Sesquichloride 
 of antimony. 
 
 Butter of Arsenic. Chloride of arsenic. 
 
 Butter of Bismuth. Chloride of bis- 
 muth. 
 
 Butter of Cacao. An oily concrete 
 matter, obtained from the chocolate nut. In 
 appearance it much resembles mutton suet, 
 
 and is made by bruising the nuts, and boiling 
 the pulp in water, when the oil will float to 
 the top of the water, and may be taken off 
 when cold. It is used in pomatums. 
 
 Butter of Tin. Perchloride of tin. 
 
 Butter of Zinc. Chloride of zinc. 
 
 Butterfly Valve. A double clack 
 valve, as follows :— The two sides are fixed to 
 a hinge in the centre, and open in opposite 
 directions, either over a round hole, or over 
 two holes ; it is a useful valve, where there 
 is not height for the play of a flat valve 
 covering the whole orifice 
 
 Buttery Hatch. A half door between 
 the buttery, or kitchen, in old mansions, 
 and the hall. 
 
 Buttress. A projection from a wall to 
 create additional support and strength. But- 
 tresses partake of the particular style of 
 architecture of the building. In the Norman 
 style they projected but little. In the early 
 English the projection was increased. In 
 the pointed arch style the buttress became 
 heavy ; it was therefore soon afterwards per- 
 forated. Flying Buttresses next succeeded ; 
 
 in the decorated Tudor architecture the ut- 
 most elegance was given by panels, fret- 
 work, pinnacles, niches, &c. 
 
 BuTURATES. Combinations of buturic 
 acid with various bases. They are inodorous 
 when dry, but when moist smell strongly of 
 butter. 
 
 Buturic Acid. A limpid, colorless acid, 
 resembling oil, obtained from butter : it 
 unites with water, and with alkaline, earthy 
 and a few metalline bases, forming buturates. 
 
 BuTYRiNE. A peculiar oleaginous matter, 
 procured by M. Chevreul from butter, which 
 serves to distinguish it from animal fats. It 
 congeals at 32° Fahr. ; dissolves in all pro- 
 portions in boiling alcohol, its solution 
 gradually becoming sour. When buturine- is 
 saponified, it yields three distinct acids, 
 termed the buturic, the caproic, and the 
 capric acid. 
 
CA 
 
 CA 
 
 Thethird letter of the alpha- 
 bet in most European lan- 
 guages ; it has two distinct 
 sounds— a soft sound, like *, 
 before e, i, y, as in cell, city, 
 cylinder ; and a hard sound, 
 like k, before a, o, u, 1, and r, 
 as in cat, cot, cut, claim, cramj;. 
 Combined with the letter h it has many 
 sounds, as is exemplified by chord, 
 china, chivalry, choir, &c. ; and it is 
 silent before tandz, as in Czar. Used as 
 a numeral it signifies 100. In music, 
 the note thus called is placed between 
 the second and third clef line, and is 
 represented by the sound of the word 
 ut or do. Prefixed to printed or written 
 music it signifies common time. In 
 contractions, and on monuments and 
 coins it is put for Caesar, Caius, consul, 
 canto, condemn©, &c. ; besides being 
 often interchanged for q and 
 g, as cotidie for quotidie, 
 >leciones forlegiones, &c. 
 
 Cable. A rope, or chain, of large size, 
 by which ships are held to their anchors, or 
 moorings. Cables are always made of the 
 length of 120 fathoms, or 240 yards. Their 
 diametet varies according to the purposes 
 for which they are intended — this is mea- 
 sured in inches ; thus we say, an 18 -inch 
 cable, a 12-inch cable, and so on. 
 
 Cable Moulding. A round moulding 
 cut in imitation of the twisting of a rope ; 
 much used in the Norman architecture. 
 
 Cabling. The shafts of columns are 
 cabled when the flutes are partly filled by 
 cylinders ; these seldom extend about one- 
 third of the shaft in height. 
 
 Cable Stopper. An instrument, patented 
 by Mr. S. Burnett, to prevent sudden strains 
 upon cable fastenings, whereby they are so 
 often torn away. It consists of a spiral 
 spring, inclosed in a box. The box is fas- 
 tened to the ship, and the cable to an arbor 
 passing through the spring, and compressing 
 it when any unusual strain occurs. 
 
 Cacao, Butter of. (See Butter.) 
 Cadel's Fuming Liquid. An oil-like 
 liquid, impregnated with metallic arsenic, 
 water, and pyro-acetic spirit ; obtained by 
 
 distilling a mixture of acetate of potassa and 
 arsenious acid. 
 
 Cadmium. A metal discoveredabout 1818. 
 It occurs chiefly in Silesia, in several ores of 
 zinc : it has the color and lustre of tin, and 
 is susceptible of a fine polish. Its fracture is 
 fibrous; it is in texture soft, easily bent and 
 cut, malleable and ductile, and fuses at a 
 heat much less than redness ; its vapours 
 have no smell. In the strong acids it dissolves 
 with disengagement of hydrogen, forming 
 colorless solutions. The only oxyde is of a 
 brown color ; its sulphuret is of a fine orange. 
 Caduceus Rocket. (See Rocket.) 
 CoFFEic Acid. An acid precipitated along 
 with tannic acid, by treating decoction of 
 coff'ee with acetate of lead. 
 ^ Cafeine. a principle similar to narootine, 
 discovered by Robiquet in coff'ee. It is white, 
 crystallizes in long silky filaments, is volatile, 
 and soluble in alcohol and boiling water. 
 
 Cage. In carpentry, an outer work of tim- 
 ber, inclosing other w^orks within it, as the 
 case of a stair is the wooden wall which 
 surrounds it. 
 
 Cahinic, orCAHiNcic Acid. The bitter " 
 principle of caina bark, procured from the 
 alcoholic extract. 
 
 Cairngorm, or Cairngorum. A species 
 of quartz, usually of a slightly brown color. 
 Caisson. A large flat-bottomed box, 
 built of strong timber, made water tight, 
 and sunk to the bottom of a river ; intended 
 as a frame -work in which the workmen may 
 construct the foundation of a bridge. When 
 this is built above high- water mark, the sides 
 of the caisson are detached, the bottom of it 
 remaining, and forming part of the foun- 
 dation itself. Westminster Bridge is built 
 upon caissons. 
 
 Caissons. The sunk panels in flat or 
 vaulted ceilings, soffits, &c. 
 
 Caking. The adhesion of one thing to 
 another ; occasioned, by compression, subsi- 
 dence, evaporation of watery particles, swel- 
 ling by fire, &c. 
 
 Cai amanco. a sort of woollen stuff of 
 
 a shining appearance, checkered in the warp, 
 
 so that the checks are seen only on one side. 
 
 Calamine. An ore of zinc, chiefly used 
 
 in making brass. 
 
 Calc-sinter. The incrustations of car- 
 bonate of lime upon the ground, and sta- 
 lactites, as attached to the roofs of caverns, 
 &c. In all cases arising from the deposition 
 of the lime held in solution in the water. 
 
 Calcar, or Fritting Furnace, is a 
 furnace in which the ingredients used in glass 
 making are submitted to a roasting heat, 
 previous to their being placed in the glass 
 pots, where they are to be fused together. 
 This is necessary in order to drive off" the 
 impurities, particularly the carbonic acu) 
 which the ingredients may contain. 
 
CA 
 
 CA 
 
 Calcareous Earth. Any friable kind 
 of limestone, chalk, &c. In chemistry it 
 signifies pure lime. 
 
 Calcareous Spar. Crystallized carbo- 
 nate of lime. One of the purest varieties 
 has the name of Iceland spar, though it is 
 not peculiar to that island. It is remarkable 
 for having the power of double refraction, 
 as is represented iu the following crystal : — 
 
 Calcedony. a hard flinty stone, often 
 cut into seals. Cornelian is one of the spe- 
 cies of calcedony, so is the onyx stone. 
 
 Calchantum. The ancient name of sul- 
 phate of iron. 
 
 Calcination. The process by which some 
 bodies are rendered capable of being pul- 
 verized ; it consists of exposing the sub- 
 stances to a strong heat, so as to dissipate 
 the water of crystallization, and other vola- 
 tile portions, and thus destroying the cohe- 
 sion of the solider parts. 
 
 Calcium. The metallic base of lime, first 
 separated from the earth by Sir H. Davy. 
 Lime is an oxyde of calcium. The salts of 
 lime are now more properly called the salts 
 of calcium, as we speak chemically of the 
 chloride of calcium, &c. (See Lime.) 
 
 Calcography. The art of engraving. 
 
 Calculus. Among mathematicians is a 
 certain method of performing mathematical 
 calculations, investigations, &c. Thus we 
 say, literal calculus, which is the same as 
 algebra ; numeral calculus, the same as arith- 
 metic ; and so on for others. 
 
 Calefactor. a small cooking stove, in- 
 vented and patented by Mr. Tozer, for the 
 use of small families in the summer season. 
 It consists of a double cylinder of tin, holding 
 water between them ; the centre being then 
 dry, cooks any thing put within it, just as 
 is seen in a common glue pot. 
 
 Calendering. The operation by which 
 all accidental wrinkles are removed from 
 various kinds of cloth, and their surfaces 
 rendered smooth and free from wrinkles. 
 The common calendering machine resembles 
 a mangle, but is greatly larger and heavier. 
 
 Calendulin. a matter somewhat analo- 
 gous to gum tragacanth, obtained by Geiger 
 from the petaU of the marigolds 
 
 Calking. A term used by artists to de- 
 note drawings traced from a print or design, 
 by rubbing the back of the print vnth red 
 or black chalk, and laying it on a sheet of 
 clean paper, with its chalked surface next to 
 the paper ; then tracing all the lines of the 
 drawing, or print, with a point, leaves the 
 impression of the point. Instead of thus 
 spoiling the print, it is better to put a sheet 
 of chalked paper between the print and 
 white paper. 
 
 Caliber, Calibre, or Caliper. The 
 diameter, whether external, or internal, of 
 any round body ; thus we speak of the ca- 
 libre of a rocket, cannon, shaft, &c. 
 
 Calibers, Caliper Compasses, or 
 simply Calipers. A sort of compass, made 
 vnth bowed, or arch legs, for the purpose of 
 taking the diameter of any round object. 
 
 Calico Printing. The art of producing 
 upon calico and other similar cotton fabrics, 
 designs or patterns, combining a variety of 
 colors, so as to produce a pleasing effect. 
 
 Calippic Period. A period of 76 years, 
 continually recurring ; after which it was sup- 
 posed by Calippus, that the lunations, &c., 
 of the moon would return again in the same 
 order, which, however, is not exact, as it 
 brings them too late by a day in 225 years. 
 
 Callan's Coil. An electro-magnetic 
 apparatus, consisting of a wooden bobbin, 
 upon which is wound about 600 feet of 
 copper wire, about as thick as bell wire, and 
 covered with silk ; the inner and outer end 
 projecting through the sides of the bobbin. 
 This is called the primary coil ; over it is 
 wound 1600 feet of much thinner wire, also 
 covered with silk, and quite unconnected with 
 the inner coil, and with its ends also project- 
 ing ; this is called the secondary coil. This 
 compound coil of wire forms a part of all coil 
 machines, such as Bachhoffner's, Bird's, 
 Clarke's, Wright's, Sturgeon's, &c., (which 
 see,) or it may be used without them. The 
 galvanic battery being connected with the two 
 ends of the primary coil, and a person made 
 to take hold of the two ends of the secondary 
 coil, he will feel an intense shock at the 
 moment contact with the battery is made, 
 and if a fine wire be made part of the battery 
 circuit, it will be rendered red hot, much 
 more readily than without the coil. It is to 
 be added, that a bar of iron, or still better, 
 a bundle of iron wires, should be placed 
 within the inner coil, as represented in the 
 
CA 
 
 CA 
 
 figure, where A is the bundle of wires ; B C 
 binding screws at the ends of the primary 
 coil ; D E the wires from the battery ; F G 
 binding screws at the ends of the wires of 
 the secondary coil. 
 
 %!S-TF^ 
 
 Callan's Electro-Magnetic Re- 
 peater, is represented below. A is a scape- 
 wheel, moving the bar B, and with it the 
 arbor C, and the wire which is fastened to it 
 D E ; the arbor has a wire reaching some 
 mercury in the cup F ; while the ends of 
 D E are bent at right angles, so as to dip 
 alternately into G H ; G and H are connected 
 together by a wire beneath the stand. To use 
 the instrument, connect one pole of a galvanic 
 battery with the cup F, and the other pole 
 with either the cup G or H, it is immaterial 
 which ; upon turning the handle, very rapid 
 connection between the poles of the battery 
 will be made and broken. 
 
 ™I|!]M^^ 
 
 Callipers, see Calibers. 
 
 Calomel. Proto-chloride of mercury, 
 frequently called sub -muriate of mercury, or 
 mild muriate of mercury. 
 
 Caloric. An imaginary fluid substance, 
 supposed to be diffused through all bodies; 
 and the sensible effect of which is termed 
 heat ; with chemists, caloric is properly 
 the matter producing the sensation, and heat 
 the sensation itself. The terms, however, 
 are often confounded ; the word heat being 
 used both for the cause and the effect. 
 
 Conductors of Caloric (See Con- 
 ductor.) 
 
 Caloric, Free or Sensible, and Latent. 
 That portion of the fluid matter of heat which 
 exists in any body, without producing any 
 effect, is caUed latent .• that which produces 
 an effect being termed free or sensible caloric. 
 
 Caloric, Specific. Although all substances 
 possess some quantity of caloric which is 
 latent, yet the quantity in each varies with 
 the nature of the body. The relative pro- 
 portion that any body retains without the 
 effects being sensible, is termed the specific 
 caloric of that body, and its power of reten- 
 tion is called its capacity for caloric. 
 
 Calorific Rays, are those rays or emis- 
 sions from the sun, or any burning body, 
 which impart the sensation and other effects 
 of heat. 
 
 Calorific Repulsion. Heat. 
 
 Calorimeter. An instrument for mea- 
 suring the quantity of heat contained in any 
 body, the temperature of which is above 32°. 
 It consists of two metaUic vessels, placed 
 one within the other, with a space between 
 them ; each vessel being furnished with a 
 stop cock at bottom. The vessels have each 
 a closely- fitting cover, which covers have 
 also a space between them. If the space 
 between the vessels be filled with melting ice, 
 or snow, this will gradually melt away, and 
 the water formed run out by the cock A ; 
 by this arrangement the temperature of the 
 inner vessel will always be that of the freezing 
 point, or the thawing point, which is the same 
 thing. A third vessel B is now placed 
 within the second, and the space between the 
 two inner vessels also filled with melting ice. 
 It is evident that the ice contained in the 
 second vessel, cannot be affected by the ex- 
 ternal air ; therefore, when a heated substance 
 is placed within B, it will melt a certain pro- 
 portion of the imier stratum of ice, the 
 quantity of which melted, and consequently 
 the quantity of heat parted with, to lower it 
 to 32°, is ascertained by the quantity of 
 water which flows out of C. 
 
 C alorimotor. a galvanic battery formed 
 of a single pair of extremely large plates of 
 metal, such plates consisting of smaller plates 
 soldered together so as to act in union, or as 
 one plate ; (this was the structure of the first 
 battery of this description, made by the in- 
 ventor, Dr. Hare, of Philadelphia ;) or else 
 consisting of two long plates, one of zitic, the 
 other of copper, coiled round each other, as 
 suggested by Mr. Pepys, and as represented 
 below. This compound coil is suspended 
 over a tub of acidulated water, into which 
 it can be lowered at pleasure. The name 
 
CA 
 
 CA 
 
 calorimotor, or the mover of heat, is derived 
 from the extraordinary power the instrument 
 possesses in deflagrating the metals, and 
 otherwise producing heat and combustion. 
 
 Calotte. A concavity in form of a cap 
 or niche, to diminish the height of a cabinet, 
 alcove, &c., when it would be too high for 
 the width of it. 
 
 Calx. An old word to signify any earthy 
 substance left after burning ; as the oxyde 
 formed upon melted metals, such as lead ; 
 the dross left in the glass furnace, the iron 
 furnace, &c. In later times, calx is applied 
 chiefly to signify lime. 
 
 Cam, or Cam Wheel. A wheel, or part 
 of a wheel, formed so as to move eccentri- 
 cally, or else made with either projections, or 
 depressions on its circumference, of such a 
 nature as to produce a reciprocating and 
 mostly interrupted motion in some other 
 part of machinery attached to or working 
 against it ; for example, letter A represents 
 a wheel furnished with four cams on its cir- 
 cumference, and therefore, during every re- 
 volution it would lift up the rod B four 
 
 lift the rod gently up and down, without any 
 sudden recoil ; the cam D would lift it sud- 
 denly up, then let it rest for half a revolution, 
 then let it down, and then let it rest again. 
 The cam wheels, E, F, G, H, and I, will 
 each give a different motion to whatever is 
 pressed against it. It is by means of cams 
 that most irregular motions are given to 
 machinery, particularly in those curious 
 automata, where writing, drawing, &c., is 
 imitated by a mechanical figure. Cams are 
 also the principles upon which the rose and 
 similar engines are constructed. 
 
 Camber. A slight degree of arching which 
 is usually given to the cross beams of a roof, 
 as an allowance for their settling, wliich they 
 do in a slight degree when the weight of 
 rafters and tiling comes upon them ; also an 
 arch at the top of an aperture, or on the top 
 of a beam ; hence camber windows. 
 
 Camber Beam. (See Beam.) 
 
 Cambric. A kind of very fine and rather 
 thin linen fabric, first made at Cambray, 
 whence its name. It is in England sometimes 
 made from cotton, and at other times linen 
 thread. 
 
 Camera Lucida. An instrument in very 
 general use by artists, and others, in drawing 
 landscapes, machinery, &c., as well as for 
 copying and reducing complicated drawings. 
 It was the invention of Dr. Wollaston in 
 1807. It is thus figured and described. 
 
 times, the rod falling by its own weight, or 
 in consequence of a spring attached to it, as 
 soon as each cam has passed it. The eccentric 
 wiieel, or cam, C, iu each revolution would 
 
 A is a clamp, fastening the upper part to 
 the table, or to a drawing board ; B a stem of 
 two or three joints, sliding into each other, 
 after the manner of a telescope. C is a prism 
 shaped as seen more clearly in D. The front 
 side of the prism is directed to the object at 
 a distance ; the stem is drawn out according 
 to the size of the intended drawing. The eye 
 looking now down upon the top of the prism 
 will see the distant object represented below 
 
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 through the prism. This is, however, not 
 sufficient ; it is necessary that a pencil held 
 in the hand should be also visible ; to see this 
 at the same time as the picture, the eye is 
 directed half over the edge of the prism, and 
 half on the side of it, and in order that the 
 eye may be obliged to maintain the just 
 position, and not be diverted by extraneous 
 light, there is placed on the upper side of the 
 prism, a thin plate of brass, with a hole cut 
 in it, through which the vision is directed. 
 This instrument requires considerable prac- 
 tice, that the artist may see the object and 
 the pencil both at the same time clearly. 
 
 Camera Obscura, or Dark Chamber. 
 An amusing optical instrument, invented by 
 the celebrated Baptista Porta. In its original 
 state it is nothing more than a darkened 
 room, with an opening in the window shutter, 
 in which is placed a convex lens, of one or 
 more feet focal distance. If a sheet of white 
 paper be held perpendicularly behind the 
 lens, there will be painted on it a represen- 
 tation of all the objects to be seen from the 
 window, whether at rest, or in motion. To 
 exhibit this picture to several persons at 
 once, or to enable a person to copy it, it is 
 desirable that the image should be formed 
 upon a horizontal table. This is done by a 
 mirror, placed at an angle of 45° with the 
 objects, which in the first form of the instru- 
 ment represented below reflects the objects 
 downwards, and in the second form, called 
 the boa; camera, reflects them upwards. 
 
 A convenient form of the instrument is 
 seen below, where the objects are reflected 
 from the mirror A, downwards through the 
 meniscus glass B, on the table C. The lower 
 part of the instrument consists of a square 
 box, one side of which is cut to admit 
 the head and arms of the person who desires 
 to trace with a pencil the objects delineated. 
 It is best to fix the upper part which contains 
 the lens, and to which the mirror is attached, 
 on to a tube, that by turning it round the 
 mirror may be directed to any part of the 
 horizon. 
 
 tached to the top of a circular building, which 
 is capable of holding several persons at once. 
 The box camera is constructed as follows : 
 procure a box, about 14 inches long E, 
 having smother box sliding in it F ; the inner 
 box having but one end, and in the centre of 
 that end a double convex lens of 10 inches 
 focus A. The outer box contains a piece of 
 looking glass B, fixed at an angle of 45° ; 
 one part of the top also Ufts up D, and its 
 place is occupied by a piece of ground glass, 
 with its ground side uppermost C. The rays 
 of light passing the mirror, strike against the 
 looking glass, and are by it reflected upwards, 
 where they are intercepted by the ground 
 glass, consequently upon this are seen the 
 objects presented before A. 
 
 An apparatus like this is sometimes at- 
 
 Cameleon Mineral. A name given to 
 the manganesiate of potass, because of its 
 often-changing colors. When pure potass and 
 black oxyde of manganese are fused together 
 in a crucible, a compound is formed ; whose 
 solution in water, at first green, passes spon- 
 taneous through the whole series of colored 
 rays to the red. From this latter tint, the 
 solution may be made to retrograde to the 
 original green, by the addition of potass, or 
 may be rendered altogether colorless, by the 
 addition of chlorine, or sulphuric acid. 
 
 Cameo. A name given to stones, shells, 
 &c., when engraved, so as to show a bas-re- 
 lief of busts, statues, &c., particularly if 
 copies from antiques. 
 
 Camerated. The same as arched. 
 
 Cames. In glazing, small slender rods of 
 cast lead, about 12 or 14 inches long, to be 
 drawn through a vice, in order to make turned 
 lead; each such bar being called a came. 
 
 Camlet, or Camblet. A light stuff, 
 much used for female attire. It is made of 
 long wool hard spun, sometimes mixed with 
 cotton w linen yam. 
 
 Camp Ceiling. A ceiling, formed of one 
 or more planes, rismg at an obtuse angle 
 with the walls of the apartment, sometimes 
 meeting in a point at the top, but more fre- 
 quently inclosing a level ceilmg in ths middle 
 between them. 
 
 Campeachy Wood. Logwood. 
 
 Camphogen, or Campkene. Oil of tur^ 
 pentine. 
 
 Camphor. A volatile, concrete, strong- 
 smelling oil, obtained from fery many herbs 
 and trees by distillation, particularly from the 
 roots of different species of the Uurel. It 
 
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 swims on water, evaporates in a warm air, is 
 soluble in alcohol, and in a very small degree 
 in water. It bums with a very white light ; 
 and set fire to, when floating on water, it has 
 the singular property of rotating during its 
 inflammation, leaving no residuum. Its 
 effluvia are very noxious to insects, for which 
 reason camphor is mostly placed in cabinets 
 of stuffed animals, furs, &c., to prevent the 
 moths and other insects from attacking them. 
 
 Camphorates. Salts formed of camphoric 
 acid and numerous bases. They have a bit- 
 terish aromatic flavor, and are decomposed 
 by the stronger acids. The alkaline and earthy 
 camphorates are soluble. The metallic cam- 
 phorates, except that of manganese, are 
 insoluble. 
 
 Camphoric Acid. When camphor is re- 
 peatedly distilled with nitric acid, it is con- 
 verted into camphoric acid, and is in the form 
 of plumose crystals, which are, like camphor 
 itself, soluble very readily in alcohol, but 
 with difficulty in water. It combines with 
 the usual salifiable bases. 
 
 Cam Wood. A wood employed in dyeing. 
 It is brought from the Brazils. 
 
 Camus's Sieve. A contrivance, invented 
 by Mr. Camus, for the moving of sieves. 
 
 A is a sieve, which is capable of motion 
 on the pivots B B ; suspended to an arm C, 
 attached to one of the ends of the sieve, or 
 to one of the pivots, is a pendulum D. It is 
 evident, that whatever motion is given to the 
 pendulum, that motion will be communicated 
 to the arm C, and by it to the sieve A. E is 
 a box to receive the particles passing through 
 the bottom of the sieve. 
 
 Canal. An artificial channel for water, cut 
 either for the purpose of transporting goods 
 by boats, or sometimes to convey water to 
 towns. 
 
 Canals of a Column. The flutes of it. 
 
 Canal of the Ionic Volute. The spi- 
 ral channel, or sinking on the face ; which 
 begins at the eye in a point, and expands in 
 width till the whole circumvolutions are 
 completed. 
 
 Canal of the Larmier. A channel cut 
 underneath a soffit, coping stone, sill, &c,, 
 to prevent the rain which drips on it from 
 passing to the walls of the building. 
 
 Cancelli. Latticed windows, or those 
 made with cross bars of wood or metal ; they 
 are mostly without glass. 
 
 Cancer. The crab : one of the twelve 
 
 signs of the zodiac, in which the sun enters 
 on the 24th day of June, or our longest day. 
 Cancer, Tropic of. A small circle of the 
 sphere, parallel to the equator, and at the 
 distance of 23° 28' northward of it, bounding 
 therefore the torrid zone to the north. It is 
 so called because passing through the be- 
 ginning of the constellation Aries, the point 
 of the sun's greatest northern declination. 
 Candelabrum. A stand for a lamp. 
 Candle Lamp, is represe.ited in the figure 
 annexed. The tube A, which is called the 
 candle, and which is formed 
 and painted to resemble one, 
 moves tightly up and down in 
 the socket, or candlestick. 
 This socket has at the upper 
 end a pad, or piston of leather, 
 fixed by a wire to the foot of 
 the whole. The top of the 
 candle is unscrewed, the can- 
 dle drawn up to its full height ; 
 then filled with oil, the top 
 furnished with a wick and 
 lighted. As the candle may be 
 pushed down within the soc- 
 ket whenever the lamp bums 
 dimly, the oil may be con- 
 stantly kept even with the top, 
 so as to supply the wick. Tiie 
 overflow of oil is the great 
 inconvenience by which this 
 lamp is accompanied. 
 
 Canister Shot. Tin canisters filled with 
 small balls, which fired from cannon disperse, 
 themselves around, and are therefore most 
 destructive in their effects. 
 
 Cannel Coal. A species of coal, which 
 contsiins a large proportion of bitumen ; it 
 bums with a bright flame, has a smooth 
 surface when broken, and is much less fiiable 
 than coal in general, on which account it is 
 often turned into ornaments, snuff"-boxes, &c. 
 Cannon, Electrical. (See Air Pistol. ) 
 Canon. An old mathematical word for 
 formula. 
 
 Canopy. A magnificent covering for 
 thrones, tribunals, altars, pulpits, &c. It 
 also denotes the label, or projecting moulding, 
 which surrotmds the arch and heads of gotliic 
 niches, windows, and arches. 
 
 Canted. WTien the angles are cut off a 
 post, pier, beam, &c., it is called canted; 
 when a turret is built of a polygonal form, it 
 is said to be canted. Cant is also a term 
 used by carpenters to designate those beams, 
 timbers, &c., which are given to them the 
 wrong way, so that they require to be turned 
 end for end before they can be used. Among 
 coopers, it signifies the two side pieces of 
 wood which form the head of a cask. 
 
 Cantklivers. Trusses placed under the 
 modillions in a frieze ; also any projecting 
 piece of iron, wood, &c., to support eaves, 
 canopies, or cornices. 
 
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 Canthakidin. The active principle of 
 cantharis. It was procured by Robiquet, in 
 small brilliant micaceous plates. 
 
 Canton's Phosphorus. Calcined phos- 
 phate of lime. To make it : — Calcine some 
 common oyster-shells, let the purest part be 
 pulverized and sifted, and then mix with it 
 one-third in weight of flowers of sulphur ; 
 ram this mixture into a crucible ; put it in 
 the fire, and keep it red hot for an hour ; 
 afterwards let it cool, and keep for use the 
 whitest parts. It becomes luminous when 
 exposed to a succession of electric sparks, or 
 any other strong Ught. It must be kept in a 
 dry, stoppered phial. 
 
 Canton's Method of Making Mag- 
 nets. Take a poker and tongs, (or two bars 
 of iron,) the larger and the older the better ; 
 and fixing the poker upright, hold to it with 
 the left hand, near the top, by a silk thread, 
 the bar of soft steel, of which the magnet 
 is to be made, having its marked end down- 
 wards. Then grasping the tongs with the 
 right hand, a little below their middle, and 
 keeping them nearly in a vertical line, let 
 the bar be rubbed with the lower end of the 
 tongs, from the marked end of the bar to 
 its upper end, about ten times on each side of 
 it. By this means the bar will receive as 
 much magnetism as will enable it to lift a 
 small key at the marked end ; and being sus- 
 pended by its middle, or made to rest on a 
 point, this end will turn to the north, and is 
 called its north pole ; the unmarked end 
 being the south pole. 
 
 Cantoned Building. A building whose 
 angles are adorned with columns, pilasters, 
 rustic quoins, or any thing that projects 
 beyond the general surface of the walls. 
 
 Cantoned Columns. Such as are placed 
 at the angles of a square pier, &c., for sup- 
 porting the sp ringings of arches, or groins. 
 
 Canvas. A hempen cloth, unbleached, 
 and of various degrees of fineness ; used 
 principally to form the sails of a ship, and 
 also by painters, and for other purposes. 
 
 Caoutchouc, Gum Elastic, or Indian 
 Rubber. A milky juice which exudes from 
 numerous trees, particularly those of the fig 
 tribe. This concretes by exposure to the 
 air, or to the heat of a fire. It is insoluble 
 in water and in alcohol, but is soluble in pure 
 ether, in hot naphtha, and the fixed oils. It 
 is but little acted upon by the acids, or 
 strongest alkalies, and not at all by any of 
 the gases. It is used extensively in the ma- 
 nufacture of water-proof cloth, as a varnish 
 for balloons, and by artists as a means of 
 removing marks made by a black-lead pencil. 
 Caoutchouc is almost the only concrete vege- 
 table product which contains no oxygen ; 
 consisting, according to Dr. Ure, of 9 parts 
 carbon to 1 hydrogen, being 3 atoms of the 
 former to 2 of the latter. 
 
 Caoutchouc, Solution of, may be made 
 by cutting caoutchouc into small pieces, then 
 soaking it in hot naphtha, made by the distil- 
 lation of coal tar for some hours, when it 
 swells to 30 times its original bulk ; it is now 
 to be pounded, and more naphtha added, and 
 the heat being afterwards increased to boiling, 
 the caoutchouc dissolves, forming a thick, 
 clammy, transparent solution. A solution 
 may also be made by treating it with spirits 
 of turpentine in the same manner. Both 
 solutions are tedious in drying, particularly 
 the latter, though this is not so disagreeable 
 in odour as that made by the coal naphtha. 
 
 Caoutchouc Varnish. To either of the 
 above solutions add one-third its quantity 
 of drying oil. This is said to be the varnish 
 used for balloons ; its elasticity renders such 
 an appUcation valuable to aeronautic ma- 
 chines, but the tediousness of its drying, 
 and its long continued clamminess, make all 
 caoutchouc varnishes unavailable for ordinary 
 purposes. 
 
 Caoutchoucine. An inflammable liquor, 
 procured from caoutchouc by distillation. It 
 is one of the most remarkable substances; 
 inasmuch as although the liquid itself is the 
 lightest known, yet its vapour is heavier than 
 that of any other substance. It is, when 
 mixed with alcohol, a ready solvent for all 
 the resins, even copal, and that without heat ; 
 it also mixes with oils, and is valuable when 
 used along with painting oils, as it dries them 
 quickly without doing injury to the most 
 deUcate colors. 
 
 Capacity of a Body. Its solidity, or 
 content ; but more commonly it denotes the 
 hollow, or vacuity of bodies ; thus we say, 
 the capacity of a vessel, meaning the quantity- 
 it will contain. 
 
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 Capacity for Heat. (See Caloric.) 
 
 Capillary Attraction. (See Attrac- 
 tion.) 
 
 Capillary Tube. A hair is a tube, and 
 hence tubes which are very small, or like 
 hairs, ai-e called capillary. 
 
 Capillary Tubes andPLATES. Two phi- 
 losophical instruments, so called, to show the 
 effect of capillary attraction. The first consists 
 uf several small tubes of glass, open at both 
 ends, and attached to a foot board, each of 
 them having a bore, or cavity, of a size 
 different from the rest ; the largest being 
 nearly half an inch diameter, the smaller, 
 scarcely larger than a hair ; when the lower 
 ends are immersed in a basin of water, the 
 water will rise in the various tubes, in pro- 
 portion to their minuteness of cavity. 
 
 In the second instrument, two pieces of 
 plate glass are fastened to a stand, in such a 
 manner that they shall touch each other at 
 one edge, and be separated at the other to 
 ihe distance of a quarter of an inch, or more ; 
 vvhen immersed in water, the fluid will rise 
 between the plates, assuming the form of 
 an hyperbolic curve as represented. 
 
 Cap, or Capping Piece, The upper 
 terminating portion of any thing, as the cap 
 of a cupola ; the cap of a printer's wooden 
 press ; the cap of a cannon is the piece of 
 lead which shields the touch-hole from wet,^ 
 &c. 
 
 Capital. The projecting and ornamented 
 part which rests upon the shaft of a column. 
 The capital varies extremely in its details, 
 according to the style of the building of which 
 it forms a part. The classical styles have each 
 
 their appropriate capital. In the Doric and 
 Tuscan it consists of mouldings only, as is 
 seen under these words. In the Corinthian 
 and Composite, the capital is enriched with 
 sculptured leaves and tendrils, scrolls, &c. 
 (See Corinthian and Composite.) In the 
 Ionic, its enrichments consist of two scrolls, 
 or volutes, as follows, more or less accom- 
 panied with mouldings, or headings, around 
 the neck of it. 
 
 In the Egyptian architecture, the capitals 
 are much diversified, being some in es 
 loaded with hieroglyphics ; at others, formed 
 of palm leaves folding over each other, or 
 else of the lotus flower, and in numerous 
 instances are sculptured into the representa- 
 tion of a female face. The following are 
 examples of Egyptian capitals, from the 
 Temple of Carnac. 
 
 The capital of the most ancient Indian 
 remains, as exemplified in the Caves of EUora 
 and Elephanta, is scarcely to be defined; 
 often it consists of a huge elephant, supporting 
 a short and thick pier ; at others, of a block 
 of stone, rudely sculptured into some gro- 
 tesque form ; while it sometimes appears as 
 an object of considerable beauty. The fol- 
 io wmg is from the Caves of Ellora : — 
 
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 The Moorish capital is highly ornamental, 
 not only in its general form, but in its elaborate 
 omamentg, consisting of elegantly arranged 
 cavities, of foliage, and of intertwining fret- 
 work. The following is one of the capitals 
 of that perfection of Moorish skill, the 
 Alhambra of Grenada : — 
 
 I 
 
 The capitals of Gothic architecture are 
 endlessly diversified ; in the earliest style, 
 and still, in ordinary edifices, it consists oi 
 plain mouldings running round the ends of 
 the pillars. 
 
 beautiful capital is taken from YorH Cathe- 
 dral :— 
 
 In the Anglo-Norman style rude attempts 
 at ornaments were made, foliage began to 
 show itself, and what is called the cushion 
 capital became prevalent. Capitals of this 
 name and period are represented below. 
 
 As Gothic architecture progressed through 
 the more ornamental styles of the lancet 
 arched, the decorated, and the perpendicular, 
 the capital was variously enriched with leaves, 
 tendrils, grotesque heads, and other ela- 
 borately-carved ornaments. The following 
 
 Cavjtaij, Angular. (See Angular Capital.) 
 
 Capital of a Lantern. The covering 
 by which it is terminated, either in a bell- 
 shape, a spire, or other form. 
 
 Capital of aTriglyph. The projecting 
 band which surmounts the face of a triglyph. 
 In the Grecian Doric, its projection is very 
 trifling, and it is confined to the front face. 
 In the Roman Doric, it is more prominent, 
 and is returned around the flanks of the 
 triglyph, while a moulding, similar to it, 
 extends along the top of the mutules, from 
 one triglyph to another. 
 
 Capnomor. a colorless transparent liquid, 
 of a pimgent and rather agreeable odour, 
 which occurs in the oil of tar. It is insoluble 
 in water and the alkalies ; but soluble in 
 alcohol, and in ether. 
 
 Capric Acid. An acid produced along 
 with caproic acid and buturic acid from 
 butter. Neither acid has yet been applied to 
 any purpose in the arts or in medicine. 
 
 Gaproic Acid. (See Capric.) 
 
 Capricorn. The goat. A southern con- 
 stellation, and the tenth sign of the zodiac.. 
 It is denoted by the character vp, being 
 intended for the representation of the goat's 
 horns. When the sun enters this sign it is 
 the winter solstice, or the shortest day. 
 
 Capricorn, Tropic of. An imaginary 
 line, bounding the torrid zone to the south, 
 and passing through the first point of Capri- 
 corn, which is the point also of the sun's 
 greatest southern declination, being 23^" 
 nearly. 
 
 Capsicin. An alkaline principle, lately 
 discovered in cayenne pepper. Its properties 
 have not yet been ascertained. 
 
 Capstan. A machine upon the principle 
 of the lever, employed principally in large ves- 
 sels, 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, called capstan bai's. The capstan is 
 superior to the windlass in point of expedi- 
 tion, owing to the circumstance of the latter 
 requiring the levers to be shifted into fresb, 
 
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 holes, four times in each revolution ; though 
 ia the windlass man's power is exerted with 
 much greater effect. 
 
 Caput Mortuum. The burnt residue left 
 in a still, when a substance has been subjected 
 to destructive distillation. 
 
 Carat. An imaginary weight to indicate 
 the proportion of a precious metal in any mass. 
 The mass being supposed to be divided into 
 24 equal parts, a carat is one of these parts ; 
 and the metal is said to be so many carats 
 fine, or to have so many carats of gold, &c., 
 in it. Pure gold is therefore 24 carats fine, 
 if alloyed with half copper it will bel2 carats 
 fine, and so on. 
 
 Carbon. One of those chemical substances 
 supposed to be simple or uncompoimded. In 
 its crystalline and perfectly pure state it is 
 known as the diamond. In its \mcrystalline 
 form it constitutes charcoal, which may be 
 called wood carbon, and which is the residue 
 of wood which has been burnt without con- 
 tact with the air. Animal charcoal, or ivory 
 black, is carbon produced by burning bones, 
 and other parts of animals, in a similar man- 
 ner. Lamp black is the carbon given off" by 
 lamps, which but imperfectly decompose the 
 fatty material with which they are fed. Soot 
 is the carbon which escapes from smoky 
 fires ; and coke the carbon procured by 
 the partial burning of coals. Each of these 
 kinds has its own peculiarity, and except com- 
 mon charcoal, is impregnated with either 
 earthy or oily particles. Charcoal is infu- 
 sible, incombustible without air, but the most 
 combustible substance in nature when air is 
 admitted. It forms a part of all animal and 
 vegetable matters. It is black, inodorous, 
 insipid, brittle, an excellent conductor of elec- 
 tricity, but a bad conductor of heat ; it re- 
 mains uninjured by time, or the effects of air 
 and moisture. It combines with most of the 
 gases ; united with oxygen it forms carbonic 
 oxyde, or carbonic acid. It also combines 
 with most of the simple substances, forming 
 carburets. Charcoal is valuable as a fuel, 
 which gives an intense heat without smoke ; 
 as an ingredient in gunpowder ; as a sub- 
 stance which ranidlv absorbs ill odours, and 
 
 considerably retards the putrefaction of ani- 
 mal substances ; as an ingredient in indestruc- 
 tible writmg inks ; by artists as a crayon, and 
 nxunerous other purposes. 
 
 Carbonated Water. Water holdmg car. 
 bonic acid gas in solution. (See Aerated 
 Waters and Soda Water.) 
 
 Carbonates. Salts formed by the com- 
 bination of carbonic acid with alkalies, earths, 
 and certaui metallic oxydes. The carbonates 
 used in the arts are chiefly the following : — 
 
 Carbonate of Ammonia. A salt, called 
 in modem chemistry the sesquicarbonate of 
 ammonia, to indicate its composition to con- 
 sist of 1 and a ^ atoms of carbonic acid to 
 1 of ammonia. This salt is the common 
 smelling salts of commerce. It is much em- 
 ployed in medicine, m chemical analysis, and 
 by the pastrycooks instead of yeast ; by ex- 
 posure to the air, the ammonia exhales, and 
 it becomes the scentless bicarbonate. 
 
 Carbonate of Copper. Malachite ; a 
 beautiful green mineral, used in brooches, 
 for seals, &c. 
 
 Carbonate of Lead. White lead; used 
 as a white coloring matter by the painter. It 
 is made by subjecting plates of lead to flie 
 fumes of vinegar, and afterwards decomposing 
 the acetate of lead thus formed by a carbonate. 
 
 Carbonate of Lime. Chalk, limestone, 
 &c. In a crystalline form it is called calca- 
 reous spar, (which see,) and Iceland spar, or 
 double refractive spar. 
 
 Carbonate of Magnesia. Much used 
 in medicine as an absorbent, to correct acidity, 
 &c. 
 
 Carbonate of Potass. Better known as 
 wood ashes, potash, and pearlash, according 
 to its state of purity or impurity. It is made 
 by burning wood and terrestrial vegetables, 
 dissolving the potass out of the ashes, and 
 afterwards evaporating the liquor to obtain 
 the potass held in solution. It is also made 
 from tartar in the same manner ; in that case 
 the residue being called salt of tartar. Pearl- 
 ash is very soluble in water, and exposed to 
 the air it deliquesces, forming what is called 
 oil of tartar per deliguium. 
 
 Carbonate op Soda, obtained in the 
 same manner as the carbonate of potass, but 
 using marine vegetables, or by decomposing 
 sea salt. It is, like the last, extensively used 
 in the arts, in the soap and glass manufactures, 
 and in medicine. 
 
 Carbonic Acid, Carbonic Acid Gas, 
 Fixed Air, Aerial Acid, Choke Damp, 
 &c. A union of oxygen and carbon, in the 
 proportion of 1 atom of the latter to 2 of 
 oxygen. Its natural state is that of a gas. 
 It combines with most of the alkalies, me- 
 tallic oxydes, earths, &c. , forming carbonates. 
 Its specific gravity is half as much again as 
 water, or 1*5245. It therefore sinks in the 
 air. It exists abundantly in nature, in chalk, 
 
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 marble, limestone, &c., each grain of wliich 
 will yield 1 cubic inch of gas. It frequently 
 occurs in mines, pits, and wells. It is yielded 
 in abundance by bodies passing through the 
 vinous fermentation, and is absorbable by 
 water. It cannot be inhaled for a single 
 minute without destroying life. Carbonic 
 acid gas may be condensed into a liquid state 
 by a pressure of 40 atmospheres, and this 
 liquid may then be solidified by the cold pro- 
 duced by its own spontaneous evaporation. 
 
 Carbonic Oxyde. Gaseous oxyde of car- 
 bon. A gas obtained by subjecting carbonic 
 acid gas to the action of substances that ab- 
 stract a portion of oxygen. It may be pro- 
 duced by heating in an iron retort, a mix- 
 ture of chalk and charcoal, or equal weights 
 of chalk, and iron or zinc fiUngs. It is lighter 
 than atmospheric air, has no taste and httle 
 odour, extinguishes flame, and burns with a 
 blue light when heated and exposed to at- 
 mospheric air. It does not affect vegetable 
 colors, occasions no precipitate with lime 
 water, and is very sparingly absorbed by water. 
 Carbonous Acid. A name given to oxalic 
 acid by Dobereiner. 
 
 Carboy. A large green glass bottle, of 
 from 4 to 10 gallons ; used for holding the 
 qU of turpentine, the powerful acids, and other 
 dangerous fluids. 
 
 Carbazotates. Salts formea of bases 
 and carbazotic acid. 
 
 Carbazotic Acid, is procured by dis- 
 solving bits of indigo in 8 or 10 times their 
 weight of nitric acid, moderately strong, and 
 boiling the solution till it ceases to fume. On 
 cooling, the acid crystallizes in semi-transpa- 
 rent yellow ciystals. It is the same as aleotic 
 acid, and is soluble in cold and hot water, al- 
 cohol, &c. 
 
 Carbuncle. A precious stone, thecclor 
 of which is a dark red, with an admixture 
 of scarlet. It is rather rare ; is found on y 
 in the East Indies, adhering to a heavy and 
 ferruginous stone of the emery kind. 
 
 Carburets. Combinations of carbon with 
 any of the simple substances. 
 
 Carburet of Sulphur, called also Sul- 
 PHURET OF Carbon and Alcohol of Sul- 
 phur. A limpid volatile liquid, of a pene- 
 trating fetid smell, and an acrid burning taste. 
 Its specific gravity is 1-265, and its boiling 
 point about 112° Fahr. It evaporates so 
 readily, and absorbs so much heat in the 
 vaporousstate, that if a tube containing quick- 
 silver, surrounded with Unt dipped in it, be 
 suspended in the receiver of an air pump, 
 and the air lichausted, the quicksilver will be 
 frozen. It consists of 15*8 carbon and 84*2 
 sulphur, in 100 parts. 
 
 Carburetted Hydrogen. A compound 
 of carbon and hydrogen, of which there are 
 several species — some gaseous, others liquid ; 
 8uch as Oil Gas, Coal Gas, Olefiont Gas, 
 
 Naphtha, Caoutchoucine, Hfc, (which see.) 
 
 Carburetted Hydrogen Gas, is of two 
 kinds ; one procured by art, called heavy 
 carburetted hydrogen, such as coal and oil 
 gas, and which burns with a pure white 
 flame ; and light carburetted hydrogen gas, 
 procurable from, and emitted by the water 
 of stagnant pools and ditches, and which is 
 so frequently to be dreaded in coal mines, 
 under the name of the fire damp. It bums 
 with a yellowish light, and is a sub -carburet 
 of hydrogen. 
 
 Carcase. The work of a house before it 
 is either lathed or plastered, or the floors 
 laid. As the whole house thus unfinished is 
 called a carcase, so certain portions of it, 
 when in like msmner incomplete, are also said 
 to be carcases ; thus, carcase flooring, car- 
 case roof, &c. 
 
 Cardinal Points. The four chief points 
 of the compass, east, west, north, and south. 
 These being the points from which all other 
 names are taken. 
 
 Cardinal Signs. Those at the four 
 quarters of the year ; that is, the signs 
 Aries, Libra, Cancer, and Capricorn, or the 
 two equinoxes and the two solstices ; answering 
 to the beginning of spring, summer, autumn, 
 and winter. 
 
 Cardioide Curve. A curve so named 
 from its resemblance to a heart. It is to be 
 made as follows : — 
 
 Through one extremity A of the diameter 
 A B of the circle A P B, draw a number of 
 lines A P Q, cutting the circle in P P, &c ; 
 and upon these set off P Q, equal to the 
 diameter AB. Then the curve passing through 
 all the points Q is termed the cardioide. To 
 form the upper part of the curve, continue 
 any of the lines beyond A until the whole 
 length of each be equal to double the dia- 
 meter of the circle APE. 
 
 Cards. Brushes made of long bent wires ; 
 used in the cotton and woollen manufacture, 
 to straighten the fibres drawn through them ; 
 an operation of the utmost importance pre- 
 vious to spinning. 
 
 Carmine. A bright crimson pigment, ob- 
 tained by precipitating the coloring matter 
 of cochineal. One preparation is as fol- 
 lows ; — Pulverize 4 ounces of cochineal, and 
 add to it 4 quarts of rain water, previously 
 boiled ; boil the whole for six mimites, ad- 
 ding during the boiling 2 drams of pulverized 
 
CA 
 
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 crystals of tartar. Then add 8 scruples of 
 Roman alum in powder ; set it aside, and as 
 soon as the gross powder has subsided, and 
 the decoction become clear, decant it into 
 long glass vessels, and the powder which falls 
 to the bottom is carmine. It is afterwards 
 to be dried at a slow fire. 
 
 Carolytic Columns. Such columns as 
 have leaves and branches winding spirally 
 round them, or disposed in the form of fes- 
 toons and crowns. They were used by the 
 ancients in supporting statues, and are now 
 frequent in theatres and such places. 
 
 Caromel. The smell exhaled by sugar 
 when calcined. 
 
 Carpentry. The art of building or con- 
 structing the frame work and unornamental 
 parts of churches, houses, and other edifices. 
 Joinery is the art of finishing these with 
 smooth and ornamental work. The two arts 
 are mostly united in the same persons. 
 
 Carrara Marble. A fine kind of mar- 
 ble ; the quarries of which are on the south 
 side of the Appenines, at Carrara, a town 
 and principality of Italy. It is of various 
 colors ; the best is of a fine white, and when 
 broken resembles the whitest loaf sugar. 
 
 Carriage of a Wooden Stair, is the 
 frame of timber work which supports the 
 steps. 
 
 Cartesian Devils. A philosophical in- 
 strument so called. It consists of one or 
 more glass figures, floating in 
 water. The figures are hollow, 
 and have each a minute hole in 
 the foot. They are to be partly 
 filled with water, until they will 
 just float ; thus balanced, they 
 are to be put in a long glass 
 vessel, also filled nearly to the 
 top with water, and an Indian 
 rubber cover tied air-tight on 
 the top, over the whole. The 
 figures it will be observed con- 
 tain partly air and partly wa- 
 ter; upon pressing the Indian 
 rubber strongly, it compresses 
 the air within the vessel. The 
 increased pressure or density 
 given to this, is communicated 
 through the water to the glo- 
 bule of air within the figures. 
 As the air within the figures is 
 compi-essed, it occupies less 
 room than before, and consequently an extra 
 quantity of water enters them, and they 
 becoming heavier sink to the bottom, while 
 the removal of the hand from the top, by 
 relieving the compression, restores the first 
 condition, and they rise again. 
 
 Cartesian Philosophy, or Cartesi- 
 ANiSM, is founded on two principles ; one 
 physical, the other metaphysical, Des Cartes 
 States, " that nothing exists but substances, 
 
 and that substance is of two kinds ; one kind 
 that thinks — another kind that does not think, 
 but that has extension or dimensions ; actual 
 thought and actual extension then form the 
 essence of substance. The essence of mat- 
 ter being thus fixed in extension, Des Cartes 
 concludes that there is no vacuum, nor any 
 possibiUty of it, in nature, but that the uni- 
 verse is absolutely full, mere space being 
 quite excluded. 
 
 Cartesian Vortices. Des Cartes among 
 other hypotheses maintained, that at the crea- 
 tion of all things the universe was divided 
 into innumerable square portions, each of 
 which contains elements of various degrees 
 of density ; that the Creator put each por- 
 tion into a double motion, one around its 
 own axis, the other around a common centre. 
 In consequence of this rototary motion, the 
 square portions became rounded, the lighter 
 elements were collected together, as a sun 
 in the centre, the more gross as an atmo- 
 sphere throughout the whole system, and the 
 grossest particles of all formed planets, and 
 other opaque bodies. This system of crea- 
 tion is usually known by the name of the 
 vortices of Des Cartes. 
 
 Carthamine. Carthamic Acid. The 
 red coloring matter of carthamus tinctorius, 
 or saiJlower, which Biibeireiner considered a 
 peculiar acid — giving it the above name. 
 
 Carthamus, or Safflower. An annual 
 plant, cultivated in Spain, Egypt, and the 
 Levant. It is used in dyeing ; yielding two 
 coloi'ing matters, one of a yellow color, which 
 is soluble in water ; the other, a fine red color, 
 which is soluble in alcohol, and alkaline so- 
 lutions. The latter is that which is most 
 useful : it is the color called rouge, as used 
 by ladies to heighten their complexion, and 
 is also the ingredient which forms the coloring 
 matter of pink saucers. 
 
 Cartouch. In architecture, a shield or 
 carved ornament, various in form, whose use 
 is to receive an inscription, or motto. Its 
 form is frequently that of a scroll of paper, 
 somewhat unfolded, as used in the corners of 
 maps, to indicate the name of the country or 
 estate which may be represented. 
 
CA 
 
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 On a building it more commonly is in the 
 form of a panel, or shield. The raodillions, 
 or blocks, introduced into the cornices of 
 apartments are also called cartouches. The 
 following is a panelled cartouch of the time 
 of Elizabeth :— 
 
 ment the valve R is pressed into its seat by 
 the descent of the cross arm on the piston, 
 
 Cartoon. A drawing or painting upon 
 large paper, usually made as a pattern for 
 painting in fresco, tapestry, Mosaic, &c. In 
 either case, the artist cannot tra ;e his entire 
 outline, as on canvas ; therefore he joins se- 
 veral sheets of paper together, draws his full 
 design upon them, then pricks through the 
 outlines with a sharp point, and then each 
 part is transferred to the work as wanted. 
 Thus were traced the splendid cartoons of 
 Raphaelle, preserved at Hampton Court. 
 
 Cartwright's Steam Engine. An en- 
 gine moved by steam, the superiority of which 
 over the engines previously in use, consisted 
 • in compactness of parts ; and still more par- 
 ticularly in obliging the steam to be condensed 
 to pass through an air jacket, having cold 
 water on each side of it. The following is 
 the general structure : — 
 
 B is a piston, working in the steam cylin- 
 der A ; its rod is continued downwards, and 
 works the second piston D in the cylinder C. 
 The steam cylinder is connected by a pipe G 
 to the condenser F, which condenser consists 
 of two concentric circular vessels. The water 
 of condensation falls into the pipe E. To the 
 bottom of the cyhnder C a pipe M is carried 
 into a box N, having a float ball O, which 
 opens and shuts the valve P, communicating 
 with the atmosphere ; a pipe Q, is also fitted 
 to the box. There is a valve at I, opening 
 tipwards ; and another at N, also opening 
 upwards. The pipe N conveys steam from 
 the boiler into the cylinder, which may be 
 shut by the fall of the clack R. K is a valve 
 made in the piston B. In the figure the pis- 
 tons B and D are shown descending. When 
 the piston B reaches the bottom of the cy- 
 linder A, the tail of the valve K being pressed 
 upwards, opens the valve, and forms a com- 
 municatitjn between the upper side of the 
 piston and the condenser ; at the same mo- 
 
 which prevents the further admission of steam 
 from the boiler. This allows the piston to 
 be drawn up to the top of the cylinder by the 
 momentum of the fly wheel. The piston D 
 is also drawn up to the top of C, and the 
 valve I is raised by the condensed water and 
 air, which have accumulated in G, and in the 
 condenser F. At the moment when the pis- 
 ton has reached the top of the cylinder, the 
 valve K is pressed into its place, by the pin 
 or tail striking the cylinder cover ; and at 
 the same time the piston B striking the tail 
 of the valve R opens it, and letting in the 
 steam, the action goes on as at first. By the 
 descent of the piston D, the water and air 
 which were under it in the cylinder C being 
 prevented from returning into the condenser 
 by the valve I, are driven up the pipe M 
 into the box N, and are conveyed into the 
 boiler by the pipe O. The air rises above 
 the water in N, and when by its accumulation 
 its pressure is increased, it passes the float O 
 downwards ; this opens the valve P, and 
 allows it to escape into the atmosphere. This 
 simple machine is well adapted as a prime 
 mover on a small scale ; and it is to be re- 
 marked, that this is the first engine which 
 was furnished with a metallic piston. 
 
 Cartwright's Rotatory Stkam En- 
 gine. Of this engine it is only necessary to 
 
CA 
 
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 notice the moving power, the more especially 
 as it has never been employed to any extent. 
 
 The axis D has an unequal number of pis- 
 tons H H H, (not less than three,) upon it, 
 so disposed that no two shall be opposite. 
 In the cylinder in which the axis revolves 
 are two valves, at opposite sides of the cy- 
 linder C.C ; on the side of each valve is a pipe 
 for the admission of steam E , and another 
 communicating with the condenser F. It is 
 obvious that the number of pistons and valves 
 not corresponding, some one or other of 
 them will always be in action on one side or 
 the other of the cylinder. The engine will 
 consequently have no tendency to stop ; and 
 therefore no fly wheel need be attached to it. 
 
 Cascabel. The round ball, or knob of 
 metal, behind the breech of a cannon ; it 
 serves as a handle to elevate, or direct, the 
 piece, and likewise to fasten it. 
 
 Case. In printing, a large obiong frame, 
 placed aslope, divided into several little 
 square compartments, in each of which are 
 kept a quantity of types, or letters, of the 
 same kind, whence the compositor takes 
 them as they are required for the work he 
 has in hand. 
 
 Case op a Door. The frame in which a 
 door is hung, and which is exactly filled 
 up by the door when closed. 
 
 Case Bays, The joists framed between 
 a pair of girders ; they should not exceed 
 10 feet in length. 
 
 Cased. In masonry, a term indicating 
 that the outside of a building is covered with 
 some material better than that which forms 
 the main part of it. 
 
 Cased Sash Frames have their vertical 
 sides hollow, to conceal the weights for 
 hanging the sashes. 
 
 Case Hardening is a process by which 
 iron articles have their surfaces rapidly con- 
 
 verted into steel ; thus they are, at the same 
 time, cheap as iron, and retain their polish 
 Uke steel goods. The process is usually ap- 
 lied to fenders, fire-irons. &c. There are 
 many ways of case hardening iron goods, but 
 the following is the easiest, quickest, and 
 most convenient : — Make the iron red hot, 
 and then sprinkle it over with the ferrocy- 
 anate (prussiate) of potass, and when the 
 salt is apparently dissipated quench the iron 
 in cold water. 
 
 Case Shot. (See Canister Shot.) 
 
 Caseic Acid. An acid procured by M. 
 Proust from old cheese. 
 
 Caseous Oxide. The name given by 
 Proust to aposepedine. 
 
 Caseum. The curd of milk. When caseum 
 is dried, and afterwards mixed with a small 
 quantity of the carbonate of soda, it has 
 been used instead of milk on sea voyages, 
 and with much success. 
 
 Casemates. Vaulted apartments of ma- 
 sonry made in the bastions of fortifications ; 
 also a hollow cylindrical moulding, the sec- 
 tion of which is from one-sLxth to one-fourth 
 of a circle.. 
 
 Casement. One of the compartments 
 between the mullions of a window ; a frame 
 inclosing part of the glazing of a window, 
 with hinges to open and shut. 
 
 Cassegrainian Telescope. An astro- 
 nomical reflective telescope, which acts by 
 receiving the objects on a concave perforated 
 speculum, whence they are reflected on to a 
 small convex speculum, situated on the axis 
 of the instrument, andfinally are reflected by 
 this to the eye glass. The only difference, 
 therefore, between the Cassegrainian and the 
 Gregorian telescopes is in the small mirror 
 of the former being convex, instead of con- 
 cave. The advantage of which is, that the 
 present telescope is shorter than the Grego- 
 rian by more than twice the focal length of 
 the small speculum ; and it is generally ad- 
 mitted that it gives more light, and a dis- 
 tincter image, in consequence of the convex 
 speculum correcting the aberration of the 
 concave one. 
 
 A is the object. B B the large speculum. 
 C the small convex speculum. D the eye 
 glasses, E a tangent screw, connected with 
 the small speculum to regulate the focus of it. 
 
CA 
 
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 Cask. Any round vessel of capacity for 
 holding liquid or dry goods ; it differs from 
 a tub in having two ends or heads, while a 
 tub has but one. 
 
 Cassiana. a bitter principle, found in 
 the root of cassia fistula by M. Caventou. 
 
 Cassius, Pukple Precipitate of. 
 Gold thrown down from its solution in aqua 
 regia by metalUc tin ; it is of a splendid blue 
 Dolor, much used by painters in enamel. 
 
 Cast. Among plumbers a small brazen 
 funnel, through which molten lead is poured 
 in the making of cast lead in pipes, it being 
 placed at the mouth of the mould. 
 
 Castellated. Built after the manner of 
 a castle. 
 
 Casting. The art of taking the impres- 
 sion of any surface, whether plain or orna- 
 mental, by pouring a liquid matter on that 
 surface. 
 
 Casting, or Warping, said of any thing 
 which has become twisted by unequal pres- 
 sure, heat, moisture, &c. 
 
 Casting of Draperies. In painting, 
 the proper distribution of the quantity and 
 folds of curtains, garments, &c., in painting 
 an 1 sculpture, so that they may appear the 
 result of nature rather than of art. 
 
 Catacoustic. The science of reflected 
 sounds, or echoes. 
 
 Catacaustic Curves. Curves formed 
 by reflection from a circular concave surface. 
 Let A B, A C, A D, be rays of light reflected 
 from the cui-ve B C D in the lines B I, C E, 
 D F. The angles of incidence being equal 
 to the angles of reflection. Then the curve 
 E F G will be a caustic formed by reflection, 
 or a catacaustic. 
 
 A perfect curve of this nature may be seen 
 on the surface of milk in a round smooth 
 basin, when it is exposed to the sun's light. 
 
 Catacombs. Subterraneous vaults for bu- 
 rial. The catacombs of Egypt are much ce- 
 lebrated ; the ciypts under many of our old 
 churches are of this nature. 
 
 Catadioptical. Reflecting. 
 
 Catadrome. An instrument used in build- 
 ing, for raising or letting dbwn great weights. 
 
 Catch. Various contrivances of a me- 
 chanical nature, to take hold of, or connect 
 one thing with another ; it may be on the 
 principle of a hook, latch, or otherwise, as 
 most convenient. 
 
 Catch-water Drains. Drains, or chan- 
 nels, cut in a slanting direction across and 
 down embankments, therefore catching and 
 carrying off" the water which falls upon them. 
 Catechu, or Japan Earth. An extract 
 prepared in India from the juice of the mt- 
 mosa catechu. It is a diy pulverable sub- 
 stance, outwardly of a reddish color, and 
 internally of a shining dark brown. It con- 
 tains a greater portion of tannin than any 
 other vegetable, and what is very remarkable, 
 no gallic acid. 
 
 Catenarian Curve. The curved line 
 described by a chain, cord, or other flexible 
 body, when hanging freely and unloaded 
 from any two fixed points, whether they be 
 horizontal or not. This form of curve is 
 considered superior to any other for inverted 
 arches, such as are requisite in chain bridges, 
 as there is no strain, except the weight of 
 the materials, and consequently the abut- 
 ments are less affected by lateral pressure, 
 than in arches of any other curvature. 
 
 Catgut. A name given to strings formed 
 out of the intestines of animals, particularly 
 those of the sheep. Catguts are used for 
 whip-cord, cords for hatter's bow^, for clocks, 
 lathe bands, strings for musical instruments, 
 &c. For the latter purpose, the strings 
 made in Italy are far superior to those of 
 English manufacture, the reason of which is 
 supposed to be the different breed, or perhaps 
 condition, of the Italian sheep, when com- 
 pared with ours. 
 
 Cathartin. An alkaline substance, found 
 by M. Lassaigne and Fenneule, in the pods 
 and leaves of senna. It is soluble in hot 
 and cold water, and alcohol, not in ether ; 
 is nauseously bitter ; of a peculiar odour ; 
 and a yellowish brown color. 
 
 Cathelectrode. The negative pole of a 
 galvanic battery. 
 
 Catherine-wheel Window. (See Rose 
 Window.) 
 
 Cathetus. An old mathematical word 
 for perpendicular. 
 
 Cathode. The negative pole of a galvanic 
 battery. 
 
 Catoptric. Any thing which acts by re- 
 flecting the rays of light, as a catoptric 
 telescope, a catoptric dial, &c. 
 
 Catoptrics. The science of reflected 
 vision, or that branch of optics which illus- 
 trates the laws and properties of hght, re- 
 flected from mirrors or specula. 
 
 Catoptric Cistula. Boxes, of various 
 shapes, lined as to their sides with looking 
 glass. The rays of light falling from an ob- 
 ject upon either of these sides, is reflected 
 from the rest, so that the object appears 
 indefinitely multiplied. The boxes may have 
 any number of sides, or these set to any 
 angle, according to the effect required to be 
 oroduced. 
 
CA 
 
 CA 
 
 Tlie following represents one of these in- 
 struments. It is formed from a sLi-sided box ; 
 the top of it is left open, or only covered 
 
 with a transparent medium, that light may 
 freely penetrate. The sides of the box are 
 lined with looking glass, and a hole is made 
 through one side, to look through. A flower, 
 or other object, may be placed i.i a small 
 hole in the centre of the bottom, so as to 
 reach half up the box ; this being illuminated, 
 upon looking through the hole, the flower, 
 owing to the continued reflection of the light 
 from it, from one side to another, will seem 
 as if it were hundreds of flowers collected 
 iu the box. A mouse put into the box will 
 produce a still more astonishing optical de- 
 ception. 
 
 Catoptric, or Reflective Dial, is a 
 kind of dial which shows the hours by means 
 of a piece of looking glass, adjusted to reflect 
 the solar rays upwards to the ceiling of a 
 room, on which the hour lines are delineated. 
 
 Catoptric Telescopes. (See Reflective 
 Telescopes.) 
 
 Cat's Eye A mineral, brought from 
 Ceylon, of various shades of grey, green, 
 brown, and red colors, and remarkable for 
 a particular play of light, proceeding from 
 interposed white fibres.. From this circum- 
 stance the name is derived ; it is often set as 
 a precious stone. 
 
 Cat's Head. A particular architectural 
 ornament used in the early English and Nor- 
 man style of building ; it varies but little 
 from the beak-head ornament, and is used 
 in edifices of the same age and character, 
 and in similar situations, such as in the 
 mouldings around door-ways and arcades. 
 
 the extremity proceeds a glass tube, covered 
 with sealing wax, and terminated by a cork 
 ball. From this cork ball are suspended two 
 pith balls, tied to filaments of linen thread ; 
 also a string runs loosely along the rod, and 
 by means of a common pin is attached to the 
 cork ball. To use the instrument, hold it 
 from a house, or otherwise, so as to project 
 into the air as clear as possible from obsta- 
 cles. After a minute or two pull the string, 
 which will insulate the electrometer, and the 
 divergence of the pith balls of it will indi- 
 cate the electric state of the air around. 
 
 Cav ALLOCS Air Pistol. (See Air Pistol.) 
 
 Cavallo's Atmospheric Electro- 
 
 .-cope. It consists of a common jointed 
 
 i.shing rod, without the smallest joint ; from 
 
 Cavallo's Bottle Electroscope, 13 
 formed by two silver wires, each carrying at 
 one of its ends a little ball 
 made of pith. The other ends 
 of the wires being suspended 
 from a cork, which is rather long 
 and tapering at both ends, so as 
 to fit either way into the mouth 
 of a varnished glass tube, serving 
 both as a handle to the instru- 
 ment when in use, and as a case 
 for itwhen carriedin the pocket. 
 When it is to be employed as 
 an electroscope, the cork is so 
 placed, that the wires hang out 
 of the tube, and will indicate 
 by their divergence any elec- 
 tricity that may be communi- 
 cated to them. When not in 
 use, reversing the cork closes up the instru- 
 ment, and renders it more portable. 
 
 Cavallo's Rain Electroscope, varies 
 considerably from the above ; it is represented 
 in the cut. A is a strong glass tube, about 
 2 feet and a ^ long, having a tin funnel ce- 
 mented to its extremity, which funnel de- 
 fends part of the tube from the rain. The 
 outside surface of the tube is wholly covered 
 
CA 
 
 CA 
 
 with sealing wax ; C is a piece of cane, 
 round which brass wires are twisted in dif- 
 ferent directions, so as to catch the rain easily, 
 and at the same time to make no resistance 
 to the wind. The cane is fixed into the tube, 
 and a piece of wire proceeding from it, goes 
 through the tube, and is terminated by a 
 ring, upon which a pair of pith balls are 
 suspended. This instrument is suspended 
 by the side of a window frame, with the fun- 
 nel projecting outwards, while the pith balls 
 are preserved dry within. 
 
 Cavallo's Self-Charging Leyden 
 Jar. Procure a glass tube of about an inch 
 internal diameter, and 18 inches long ; coat 
 one end of this tube, about half its length 
 within and without, with tin foil, the tin foil 
 however not reaching quite to the end by 
 about 2 inches. Put in a cork, and a wire 
 through the cork at the coated end. Then 
 hold the tube in one hand by the glass end 
 of it, and rub up and down on the coated 
 end with a piece of flannel, or silk, it will 
 thereby become charged ; observing, how- 
 ever, to leave off the rubbing every now and 
 then to touch the ball at the end of the wire. 
 This will charge the tube ; the discharge is 
 made in the usual way. 
 
 Cavazion, or Cavasion. An excavation 
 made in the ground for the foundation of a 
 building. 
 
 Cavetto. a small hollow moulding, com- 
 prising a quarter of a circle ; also the hol- 
 low, whatever its depth, between the tori on 
 the base of the Corinthian and Composite 
 columns. The workmen call it mouth when 
 the upper part projects forward, and throat 
 when the lower part is most prominent. 
 
 Caulicoli. The smaller central volutes of 
 the Corinthian capital. 
 
 Caulking. A term applied in ship build- 
 ing to the driving of a quantity of oakum, 
 saturated with tar, into the seams between 
 the planks of ships, which is effected with a 
 mallet and blunt chisel. The term is applied 
 to many operations similar to the above, as by 
 
 engineers in stopping the joints of boilers 
 with iron cement. Coopers also stop up in 
 like manner the minor leakages between the 
 staves and head pieces of new casks, with 
 brown paper. This they call chincing, and 
 the blunt chisel used a chincing iron. 
 
 Caustic. In chemistry, applied to those 
 bodies which rapidly corrode animal sub- 
 stances, particularly certain salts, which be- 
 come thus decomposed, one of their con- 
 stituents actingvery powerfully upon the skin. 
 Also alkalies are extremely caustic, when de- 
 prived of carbonic acid, either by heat, or by 
 the addition of quick lime. 
 
 Caustic Curves. (See Catacaustic.) 
 
 Caustic, Lunar. The nitrate of silver, 
 fused and formed into small cylindrical pieces 
 in a mould. 
 
 Cawk. Sulphate of barytes. 
 
 Cavendish's Eudiometer. An instru- 
 ment for the detonation of mixed gases. It is 
 made and used as follows : — 
 
 A is a strong glass vessel, with a glass stop 
 cock B, with a second stop-cock and brass 
 collar at E, and with a ground stopper, firmly 
 secured by the brass strap and screws at C. 
 Through this stopper the platinum wires D D 
 pass, and project a little into the cavity of A. 
 The vessel A, previously exhausted of air, is 
 screwed by E on to a receiver of the mixed 
 gases, over a pneumatic trough. Upon 
 opening the cocks B and E the gas will as- 
 cend, and fill A, where after having carefully 
 closed the stop-cocks, it may be inflamed by 
 an electric spark passed through the platinum 
 wires. 
 
 Cavendish's Maximum and Minimum 
 Thermometers. The former of these in- 
 struments is represented in figure 1 ; it con- 
 sists of a cylindrical bulb A, and a stem B, 
 terminating in an open capillary orifice, co- 
 vered by a glass ball or cap C, which com- 
 
 o 
 
CE 
 
 CE 
 
 pletely closes it. The bulb and part of the * 
 stem are filled with mercury, the rise and fall | 
 of which indicate the temperature in the usual j 
 way. Above the mercury a portion of spirit 
 of wine is introduced, sufficient to fill the ] 
 rest of the tube, and a small part of the cap. 
 When the mercury rises, it drives the spirit 
 before it into the cap C, from which it cannot 
 return while the instrument remains erect, 
 and the deficiency of spirit in the tube on 
 the subsiding of the mercury will show the 
 maximum rise of the thermometer. No. 2 
 shows another form of the instrument, which 
 being filled with spirit at the larger end, ob- 
 viates the inconvenience of having so heavy 
 a bulb of mercury. No. 3 is the minimum 
 thermometer. Its bulb A, three -fourths of 
 the ball E, and part of the leg B, are filled 
 with spirits of wine. From B to C is filled 
 with mercury, and so also is about one-fourth 
 of the ball E. Above C is a little spirits of 
 wine, and the tube is hermetically sealed at 
 the u]>per end. The mercury wiU, by the 
 addition of a scale, indicate the temperature 
 in the usual way, but when cold contracts the 
 spirits of wine in the bulb A, the mercury 
 will rise in the short tube B, and fall into 
 the ball E, from which it cannot get back 
 again into B. The quantity of mercury 
 lost, indicated in the short leg, will show the 
 minimum temperature. Fig. 4 is another 
 form of the instrument, which is rather more 
 convenient than the former. 
 
 Elizabeth, and previously, although of plaster, 
 they were made highly ornamental, as may 
 be seen from the following example : — 
 
 Ceiling. The inside of a roof, or top of 
 an apartment, more especially the stone work, 
 and the lath and plaster which covers the 
 under-side of rafters, or of flooring joists. 
 Ceilings in ordinary domestic buildings, of the 
 present time, are usually quite flat, and 
 Tvithout ornament, except perhaps a slight 
 cornice around the edges ; but in the age of 
 
 In public edifices of the more ornamental 
 character, the ceilings are often divided into 
 rectangular compartments, or sunk panels, 
 with mouldings, formed of three fillets be- 
 tween them, and a rosette in the centre of 
 each. This kind of ceiling, particularly when 
 it applies to octagonal-shaped panels, with 
 squares in the interstices, is called c(ffering, 
 and the recessed parts coffers ; and is used 
 not merely in flat, but in arched and cylin- 
 drical vaults. The borders of the coffering 
 are often terminated by belts, charged with 
 foliage, or with guilloches. A ceiling may be 
 either plain, coved, domed, or vaulted ; if 
 made on the under -side of the rafters, it is 
 said to be camp-ceiled, or tent-ceiled. The 
 under-side of arches and recesses is called 
 their intrados, or soffit, and not ceiling ; the 
 latter word being confined to inclosed, or to 
 extended spaces. 
 
 Ceiling. In carpentry, the wood-work 
 for supporting the lath and plaster at the top 
 of a room. 
 
 Ceiling Floor. The joisting and ceiling 
 supported by the beams of the roof. 
 
 Cklestine. Native sulphate of strontites. 
 
 Celestial. Anything relating to the hea- 
 vens, as a celestial globe is one upon which 
 the constellations are depicted. 
 
 Cell, in carpentry. (See Sill.) 
 
 Cell A. The inclosed space within the 
 walls of an ancient temple. 
 
 Cells. The hollow spaces between the 
 ribs of a groined roof. 
 
 Celsius's Thermometer. (See Centi- 
 grade.) 
 
 Cements. Substances employed to join 
 others in close adhesion which would not 
 otherwise unite. For this purpose, they are 
 employed in a semifluid or pasty state, so as 
 to be brought into closer contact with the 
 opposite surfaces, and becoming solid as the 
 moisture exhales, or in other cases as they 
 become cold, the whole forms as it were one 
 
CE 
 
 CE 
 
 mass. Wax, glue, sealing wax, rosin, mortar, 
 plaster of Paris, various gums, &c., are all 
 cements. (Various receipts will be found 
 under the heads of Cheese, Electrical, Arme- 
 %ian, Glass, Iron, Lapidary, Water, Roman, 
 Rice, Vancouver's, 8fc.,) besides the follow- 
 ing :— 
 
 Cement /or steam and hydraulic works, 
 such as the flanches of boilers, pumps, &c, 
 Boiled linseed oil, litharge, red and white 
 lead, mixed together till of a proper con- 
 sistence and spread upon both sides of flan- 
 nel, rag, paper, felt, &c., and screwed up 
 tight by the bolts of the joint. The respec- 
 tive quantities of the litharge and leads are 
 of little consequence. For copper boilers, 
 ike, a cement of powdered quickUme and 
 bullock's blood is generally used. 
 
 Cementation. A chemical process , which 
 consists in surrounding a body in the solid 
 state, with some powder of another body, 
 which is more combustible, or which unites 
 with it without the whole contents becoming 
 fused. Thus, iron is converted into steel by 
 cementation, by being surrounded with char- 
 coal powder, which, during combustion, 
 yields its carbon to the iron. 
 
 Cenotaph. An honorary monument, 
 erected to the memory of the dead when the 
 funeral rites have been performed in some 
 other place. 
 
 Center. (See Centre.) 
 
 Centering of Lenses. (See Lenses.) 
 
 Centesm. The hundredth part of a thing. 
 
 Centigrade Thermometer. A ther- 
 mometer, known in the north of Europe, 
 where it is most used, as the thermometer of 
 Celsius, that philosopher having suggested 
 that the scale of this instrument ought to be 
 divided into 100 parts or degrees, reckoning 
 from the height at which the mercury stands 
 when the instrument is placed in freezing 
 and in boiling water ; the freezing point being 
 indicated by 0, and the boiling point by 100°. 
 This division of the scale has two inconve- 
 niences ; one, that the sign — is necessarily 
 often introduced, to indicate ordinary degrees 
 of cold, and the degrees are so large that frac- 
 tional parts of a degree are frequently to be 
 noted. 
 
 Central. Relating to a centre. 
 
 Central Eclipse, is when the centres 
 of the heavenly bodies, which are affected, 
 exactly coincide, or are directly in a line with 
 the spectator. 
 
 Central Forces. Tlie two antagonist 
 forces by which bodies are caused to revolve 
 round a central point. These are the centri- 
 fugal and centripetal forces, acting in equili- 
 brium to each other • were the former of 
 these only to act, the moving body would fly 
 away from the centre ; if the latter, it would 
 soon approach and coalesce with the centre, 
 or be attracted to it. If these forces act un- 
 
 equally, a corresponding effect will be pro- 
 duced, according as one or the other prepon- 
 derates ; but when they are in equilibrium, 
 they of necessity balance each other, and 
 rotatory motion is produced. Thus it is that 
 the satellites or moons revolve around their 
 primary planets, and these around the sun. 
 
 Centre. The middle point of anything ; 
 that is, a point which is equally distant from 
 every part of the circumference or extremity, 
 as in a circle, a sphere, &c. The above de- 
 finition is not correct in practice so much as 
 in theory, as, by it, no solid body which is 
 not globular, nor any flat body which is not 
 a circle, can have a centre ; yet the term is 
 used to designate a point in a body nearest 
 to where the mathematical centre should be. 
 For example — cut a circular piece of wood 
 of which the centre is known, into a hexagon, 
 octagon, or other regular figure, and the point 
 which was the centre before the wood was cut, 
 will be the centre still, although the angles of 
 it are farther from that point than the centre 
 of the sides. 
 
 Centre of Attraction, is that point in a 
 body, into which, if all its substance be col- 
 lected, its action upon any remote object would 
 be just the same as if that body retained its 
 form. 
 
 Centre of Equal Attraction, is that point 
 between two bodies in which it is equally at- 
 tracted to both, as an iron ball may be equally 
 attracted to two opposite magnets, and conse- 
 quently will coalesce with neither. 
 
 Centre of a Conic Section, is that point 
 which bisects any diameter, or that point in 
 which all the diameters intersect each other. 
 This point is in an ellipse within the figure, 
 in the hyperbola without, and in the parabola 
 at an infinite distance. 
 
 Centre of a Dial, is that point where the 
 gnomen or style, which is placed parallel to 
 the axis of the earth, intersects the plane of 
 the dial. 
 
 Centre of Friction, that point on which 
 anything turns, when put in rapid and inde- 
 pendent motion, as a top spins round upon 
 the end of the peg ; this point therefore is 
 the centre of friction. 
 
 Centre of Gravity of any body or system 
 of bodies, is that point upon which the bojJy 
 or system of bodies acted upon only by the 
 force of gravity, will be balanced in every 
 possible position in which it can be placed : 
 thus — if a scale beam be horizontal when 
 suspended, it shows that it is suspended by 
 its centre of gravity. The whole stability of 
 buildings and the art of balancing depends 
 upon knowing the centre of gravity of the 
 body set up, and keeping that point as near 
 the centre of the base of the body as possible. 
 
 Centre of Motion. That point which 
 remains mathematically as rest when the other 
 parts of the body are in motion. For ex!un- 
 
CE 
 
 CE 
 
 pie — tlie centre of a revolving wheel, a lathe 
 mandril, &c., is mathematically at rest, 
 though the other parts are revolving rapidly. 
 
 Centre of Oscillation. The centre of 
 gravity of a pendulum. As it is advisable to 
 have this as near to the lower end as possible, 
 the pendulum is loaded with a ball or bob, 
 the shank of it being made very light. 
 
 Centre of Percussion. That point in 
 which the whole force of a striking body is 
 concentrated. If you strike anything a 
 heavy blow with the part near the top of a 
 round stick, such as a broom handle, it will 
 jar the hand, or if struck with the part too 
 near the middle, it wiU also jar the hand, 
 but at a point about one-third the distance 
 from the end, it will not affect the hand, but 
 the blow will be powerful and steady, that 
 being the centre of percussion. In a hammer 
 the centre of percussion is in the head, that 
 part being made heavy on purpose. 
 
 Centre. In building, the convex frame- 
 work, generally constructed of wood, and 
 used for the purpose of supporting an arch 
 of stone or brick, during the time of its 
 erection. 
 
 Centres, Line of. The line which con- 
 nects the centres of two wheels, which work 
 into each other. 
 
 Centrifugal. Flying from the centre. 
 
 Centrifugal Force. That power which 
 tends to throw an object from a centre out- 
 wards, as mud from a coach wheel. It is 
 this force which prevents the planets from 
 falling towards the sun, and which makes 
 them more massive towards the equatorial 
 parts, than around in the polar direction. 
 The centrifugal force of a revolving body will 
 be in proportion to its rapidity of motion. 
 
 Centrifugal Check Hooks. Supposing 
 the machinery which raises and lowers the 
 workmen, ores, &c., in mines were to break, 
 or be set in too rapid motion, the suspended 
 boxes which hold them might be dashed 
 against the bottom of the mine, and the de- 
 struction of life or property ensue ; to pre- 
 vent this, centrifugal check hooks are used. 
 
 Let A in the preceding cut be a frame work, 
 fixed against the side of the shaft of the mine. 
 B the end of the drum, bearing the hooks, and 
 C to represent the drum itself, upon which the 
 rope is wound, and which rope is supposed to 
 be on the other side of B, between it and A. 
 If this drum obtain a dangerously-rapid mo- 
 tion, the hooks fastened to B fly out by cen- 
 trifugal force, and one or other of them, 
 perhaps all of them, catch hold of the studs 
 D, and check the rapidity of motion of the 
 descent of whatever is attached to the rope. 
 The drum C ought besides this to be fur- 
 nished with a spring, otherwise the jerk 
 arising from the sudden stoppage of the rope 
 would produce, perhaps, worse effects than 
 its rapid motion. 
 
 Centrifugal Hoops. An astronomical 
 instrument, to show that the earth, if revol- 
 ving at all, must revolve upon its shortest 
 axis, and that owing to centrifugal force. 
 The structure of the instrument is very sim- 
 ple : it consists of two or more hoops of 
 thin tin, or brass. These are fastened below 
 to a spindle, so that they must turn with it, 
 but move easily above up and down that 
 spindle when put in motion. The spindle 
 has a pulley below, and is supported at top 
 by a cross arm. The pulley is turned by a 
 string passing over a multiplying wheel. 
 Upon turning this wheel, the hoops being 
 put in motion will endeavour to fly out by 
 centrifugal force, and assume the shape re- 
 presented by the dotted line ; that is, will 
 become an oblate spheroid, or a globular 
 body flattened towards either pole. 
 
 Centrifugal Pump. A machine for 
 raising water, dependent upon centrifugal 
 force, combined with the pressure of the atmo- 
 sphere. It consists of one, two, or more arms, 
 erect below, and branching out above, joined 
 to a vertical axle. Near the upper extremity of 
 each arm is a clack valve opening upwards, 
 while near the bottom of the vertical tube, 
 or the bottom of each, (if these are more 
 than one,) is a similar valve, also opening 
 upwards. Water being poured into the ma- 
 chine before using, and a rapid motion being 
 given to it by a handle at top, the water In 
 
CH 
 
 CH 
 
 the arms acquires a centrifugal force, opens 
 the valves at the end, and flies out into a cir- 
 cular trough prepared for it. This machine 
 is simple, but not so effective as a well-made 
 pump. 
 
 4 poles, at every tenth link is a brass mark 
 or number indicative of the distance of that 
 mark from the end nearest to it. The chain 
 is employed to measure land, ten chains in 
 length and one in breadth making an acre 
 or 100000 links. Occasionally chains of a 
 different length are used in measuring streets, 
 canals, roads, &c. 
 
 Chain Pump. An instrument for raising 
 water, which acts upon a principle contrary 
 to that of the bucket engine : it may be 
 either formed of buckets in the same manner, 
 or what is more simple and common, instead 
 of buckets, there are set at certain and regu- 
 lar intervals on an endless chain a series of 
 pistons or round plates of metal, which nearly 
 fit the cahbre of the tubes in which they 
 work. Putting the chain in motion, sup- 
 posing the bottom of it to dip into the water 
 of a well, each piston will inclose above it a 
 certain quantity of water, and bear this water 
 to the top, where it overflows into a cistern 
 prepared to receive it. 
 
 Centripetal Force. (See Gravitation,) 
 
 Centro-Linead. An instrument for 
 drawing lines towards a distant centre, as 
 towards a distant vanishing point. 
 
 Cerasin. The name given by Dr. John 
 to those gums which swell, but do not dis- 
 solve in water— such as gum tragacanth. 
 
 Cerate. A composition of hog's lard, 
 bees' wax, and olive oil : it is used as an 
 oLitment. 
 
 Cerin. That part of common wax which 
 is soluble in alcohol. 
 
 Cerium. A peculiar metal, discovered in 
 the rare metal cerite ; found only in the cop- 
 per mine of Bastnaes, in Sweden. Cenum 
 extracted from its chloride by potassium, ap- 
 pears of a dark red or chocolate color. It 
 acquires a metallic lustre by friction, but 
 it does not conduct electricity well, like other 
 metals. It has not been applied to any use- 
 ful purpose. 
 
 Cero-plastic. The art of modelling in 
 
 WfX. 
 
 Ceruse. (See Carbonate of Lead.) 
 
 Cetine. a name given by Chevreul to 
 s} ermaceti. 
 
 Cetic Acid. Procured from spermaceti, 
 ccnsisting of margarine and fatty matter. 
 
 Cevadic Acid, is prepared by converting 
 in'o soap the seeds of the veratrum sabadilla. 
 
 Chafery. a kind of forge in the iron 
 manufacture, where iron is exposed to a 
 V. elding heat. 
 
 Chain, Surveyor's Chain, or Gunter's 
 Chain. A chain made of thick iron wire, 
 (onsisting of 100 hnks., each of which is 
 ; '92 inches, altogether making 22 yards or 
 
 Ch AiR/or Railways. A socket of cast iron, 
 used upon railways to support and secure the 
 rails. If intended to support the ends of two 
 consecutive rails, it is called a double chair, 
 otherwise a single or intermediate chair. 
 
 Chalk. Carbonate of lime ; it occurs of a 
 white color, without lustre, of a fine earthy 
 fracture, gives a white streak, and adheres to 
 the tongue. It effervesces violently with 
 acids, and when contaminated with iron, 
 
CH 
 
 CH 
 
 becomes harder, and more or less of an ochrey 
 tinge. In a pure state, it appears to consist 
 of water 3 parts, lime 53, carbonic acid 42, 
 and alumine 2 parts, in every 100. It is 
 said, that there is but one chalk bed in the 
 world. This begins in Poland, runs through 
 a part of Hungary, Germany, and the Da- 
 nish Islands, passes across the East and South 
 of England, and is finally lost in the North- 
 west of France, or rather in the Atlantic 
 Ocean. Considering chalk geologically, it 
 is one of the later formations or deposits, 
 and shows by its texture, its analysis, and 
 the very numerous remains of marine ani- 
 mals that have been found in it, that it has 
 been derived by the previous agglomeration, 
 and subsequent decomposition of testaceous 
 animals. In the arts, chalk has many uses ; 
 as a building stone ; as a material from which 
 lime may be made ; as the substance which 
 when pounded and washed produces whiting ; 
 as an absorbent in medicine, &c. 
 
 Chalk, Black. A mineral called also 
 drawing slate. (See Black Chalk.) 
 
 Chalk, French j or Spanish. Steatite, or 
 soap stone. A soft magnesian mineral, 
 used for the purpose of extracting grease 
 from cloth, and as an anti-attrition powder. 
 
 Chalk, Red. A clay colored with the 
 peroxyde of iron, of which it contains about 
 17 per cent. 
 
 Chalcography. The art of engraving 
 on brass or copper. (See Engraving.) 
 
 Chalybeate Waters. Such mineral 
 waters as contain iron. Professor Hare gives 
 the following galvanic method of making 
 them. Form a metallic pile of pieces of 
 silver or clear copper coin, alternating with 
 discs of sheet iron. Such a pile placed in a 
 vessel containing water will render it chaly- 
 beate in twenty-four hours. 
 
 Chamber of a Lock. — In inland na- 
 vigation, the space between the gates of a 
 lock in which a boat rises and sinks from 
 one level to another, in order to pass the 
 lock. 
 
 Chamblanle. The border of stone or 
 the wooden frame, surrounding the three 
 sides of a door, window, or chimney. The 
 head i» called the traverse^ and the two sides 
 the ascendants. 
 
 Champ. A small sloping surface in archi- 
 tecture. 
 
 Chamfer. A groove to receive the tenon 
 in carpentry. 
 
 Chamfer. Any sharp edge which is pared 
 
 off, is said to be chamfered : it differs from 
 the splay in being smaller, and an equal 
 portion being taken off on both sides, whereas 
 a splay is taked off more on one side than 
 another. If the corner of a wall is cham- 
 fered off, the chamfered part is often ter- 
 minated by a trefoil or other ornament. 
 
 Chancel. The eastern part of a church, 
 generally divided from the rest by a screen, 
 or railing, (canceUus;) hence the name. The 
 chancel of a small church answers to the 
 choir of a large one. 
 
 Changes. In mathematics, the number of 
 combinations that may be made of any cer- 
 tain number of things, all taken together. 
 Thus, the number of changes that may be 
 rung upon six bells, will be Ix2x3x4x 
 5x6 = 720. 
 
 Channel. A canal or long gutter, sunk 
 within the surface of a body. 
 
 Channel of the Larmier. (See Canal.) 
 
 Channel of the Volute. (See Canal.) 
 
 Channel Stones. In paving, are those 
 prepared for gutters, or channels, for col- 
 lecting and turning off the rain water. 
 
 Chantry. A sepulchral chapel, in whiA 
 masses for the dead were chanted ; when de- 
 dicated to a saint, it was called a shrine. 
 
 Chapiter. An old word for the capital of 
 a column. 
 
 Chaplet. a small ornament, cut in beads, 
 &c. (See Bead.) 
 
 Chapter House. A room in a cathedral 
 where the dean and chapter assemble on 
 affairs of business. 
 
 Char. To hew or work, as charred stone 
 is hewn stone ; or it means partially to bum, 
 as charred piles, stakes, &c., are such as 
 are burned on the surface, to render them 
 less perishable in water. 
 
 Characters. The peculiarities by which 
 substances in chemistry, styles of architec- 
 ture, &c., are known and designated ; also, 
 all the marks, symbols, and abbreviations, 
 by which they are represented, or which are 
 used instead of the words necessary to ex- 
 press certain operations. The characters 
 used in various sciences are for the most part 
 peculiar to them, or are used only in the 
 same range of operations. Thus all the ma- 
 thematical sciences employ but one class of 
 characters ; astronomy another ; and so on. 
 (See Mathematical: Astronomical, Sfc.) 
 
CH 
 
 CH 
 
 Verbal characters may represent a whole class 
 of bodies, as characters of the acids, or they 
 may refer only to a particular family, when 
 they would be called generic characters ; or 
 to a single individual, when the term specific 
 character would be more applicable. 
 
 Characteristic. In mathematics, the 
 same as exponent. 
 
 Charcoal. Half burnt wood — that is, 
 wood so dried by fire as to have the whole 
 of the oxygen and hydrogen which is inhe- 
 rent in all woody substances driven off, while 
 the third constituent, carbon, remains. (For 
 its manufacture and properties, see Carbon.) 
 Charcoal, used by the engraver for cleaning 
 copper and steel plates, and also that used by 
 the artist for drawing, should be chosen of 
 clean grain without knots, and with every 
 particle of bark or other impurity scraped 
 away, willow, alder, and poplar, is most 
 esteemed. By the lecturer to burn in oxygen, 
 it should be the bark or near the out-side of 
 the stick, because such throws ofiFmore beau- 
 tiful sparks. The chai'coal most proper for 
 galvanic deflagration is always made of box 
 wood — thus : cut the wood into slips with a 
 saw ; nearly fill a crucible with the slips, cover 
 these entirely with sand, and put the crucible 
 in the fire : after the whole has become red 
 hot, and remained so half an hour, the char- 
 coal is ready. The more it is burnt, the 
 better conductor of electricity charcoal be- 
 comes — that is, within certain limits. 
 
 Charge, Electrical, signifies such a con- 
 centration of the electrical fluid at any given 
 part of an apparatus as induces it to fly off" 
 with violence from the charged body. The 
 term is generally applied to Leyden jars, or 
 batteries and prime conductor, when the fluid 
 within or on the surface of them is disturbed 
 to the greatest degree of which they are 
 capable. 
 
 Charged. In architecture, implies that 
 one member of an edifice is loaded with and 
 supports another. Thus a frieze is said to 
 be charged with such and such an ornament. 
 A column supporting an entablature is also 
 said to be charged with it. In painting the 
 same term is used to express the character 
 of a picture, when derived from color rather 
 than from drawing ; for example, sunlight is 
 indicated, not so much by figure, as by 
 charging particular parts of the picture by 
 strong touches of light. 
 
 Chart, or Sea Chart. A certain portion 
 of the sea depicted on paper, with the bear- 
 ings of the land, magnetic variation, &c., 
 expressed upon it, for the use of navigators. 
 If in the projection of these, the earth is 
 considered a flat surface, they are called j9/a>ie 
 charts. If of any extent plane charts must 
 be distorted representations, because of the 
 earth being globular. When drawn so as to 
 make due allowance for the earth's rotundity. 
 
 though the lines of latitude are still straight ; 
 the chart is called a Mercator's chart. Hy- 
 drographical charts are such as have several 
 parts of the land and sea depicted, with their 
 bearings, coasts, rocks, &c. Selenographic 
 charts are particular descriptions of the ap- 
 pearances and spots on the moon. Topo- 
 graphical charts are draughts of some small 
 portion of the earth's surface, as of a district, 
 town, &c. 
 
 Chase. A frame of iron, used by the 
 printer to block or wedge up, and hold the 
 type, when set up and arranged ready for 
 printing from. Chases are of various sizes, 
 but always six-tenths of an inch in thickness. 
 Chasing. The art of embossing upon me- 
 tals, or of representing in has relief vai-ious 
 ornamental figures and designs, by punching 
 them out from behind, and carving them on 
 the front with small chisels and gravers. 
 Chased articles, when made solid, are cast at 
 first as near as possible of the proper form. 
 Chaufer. The name given to a small 
 table furnace. It may be made of iron, or 
 what is cheaper, of a large 
 black-lead crucible, or melt- 
 ing pot. Tlie usual form of 
 the iron chaufer is repre- 
 sented in the cut : it is made 
 in two parts, the lower of 
 which is a cylinder of sheet 
 iron, with a close bottom ; 
 holes around and above it, 
 to supply air to the fire, and 
 a grating loosely dropping in, 
 and resting above the holes. 
 The fuel is put in at the top, 
 as is also a crucible to be 
 heated. When a greater de- 
 gree of heat is required, a. 
 funnel-shaped chimney is fitted on to the iron 
 cylinder. If made of a black-lead crucible, 
 holes may be drilled through the substance of 
 it, near the bottom, and a moveable set of 
 bars may drop it to the proper depth. This 
 retains the heat better than an iron furnace. 
 Chaya Root. The root of oldenlandia 
 umbellata, which grows wild on the coast of 
 Coromandel ; and is likewise cultivated there 
 for the use of dyers and calico printers. It 
 produces a color similar to, but superior to 
 that of madder. 
 
 Cheese Cement. A kmd of glue, parti- 
 cularly serviceable in joining broken china, 
 wood that is exposed to wet, painter's panel 
 boards, &c. It may be made as follows : — 
 Pound some Cheshire cheese, wash away the 
 soluble part with warm water, dry the re- 
 mainder, and mix it with quick lime. Pound 
 them together, and when wanted for use, 
 add water to make the mixture of a proper 
 consistence. This cement laid on like glue, 
 dries quickly, becomes very hard, and when 
 dry cannot be afterwards dissolved. 
 
CH 
 
 CH 
 
 Chef d'CEuvre. A masterpiece, a fine 
 work of art. 
 
 Chemical Action. The effect which 
 takes place when two bodies combine or are 
 disunited from each other, one or both bodies 
 being altered in properties by the combina- 
 tion or disunion. Thus, chlorate of potass 
 and sulphuric acid, show when united a che- 
 mical action, as they burst into flame and are 
 resolved into other substances. (See Chemical 
 Attraction,) This action may be induced by 
 mixture as above ; by heat as in firing gun- 
 powder ; by electricity as in the decompo- 
 sition of water ; by light as in the blackness 
 induced upon nitrate of silver when exposed 
 to the sun ; and by other causes, such as 
 pressure, cold, &c. 
 
 Chemical Attraction, or Affinity. 
 (See Attraction.) 
 
 Chemical Combination is that intimate 
 union of two or more bodies, which forms a 
 compound differing in one or more of its 
 essential qualities from either of the simple 
 bodies from which it was formed. 
 
 Chemical Eq,uivalents. (See Equi- 
 valents.) 
 
 Chemical Furnace. Such a furnace as 
 is adapted to chemical purposes. It ought 
 to be capable of heating vessels not merely 
 as in a common fire, but if necessary, such as 
 may be used as a blast furnace. It should also 
 be furnished with a tube running through the 
 fire for the decomposition of liquids, and 
 with a sand bath for the gradually drying of 
 powders and heating of glass vessels. Such 
 a furnace is described under the woi'd Black. 
 The following is the form used at the Royal 
 Institution, and advocated by Professor 
 Brande. 
 
 C C is an iron plate supported upon four 
 brick walls, and perforated with a square 
 hole D, and a round one E. In D is placed 
 a square iron trough filled with sand, for a 
 sand bath. In the hole C fit various vessels, 
 such as an iron pot, still, &c., or it is left open 
 for the insertion of crucibles, mufiles, and 
 other chemical apparatus. C is exactly over 
 the fire ; D is over the flue only, and about 
 three inches deep ; A is the fire-place door ; 
 B the ash -hole ; F a hole proceeding to the 
 fire for the insertion of a tube. When not 
 
 wanted, this hole is stopped with a plug. 
 G a cupboard under the flue for holding fuel* 
 or with shelves to keep deliquescent salts* 
 dishes for slow evaporations, &c. 
 Chemical Test. (See Test.) 
 Chemical Thermometer. A thermo- 
 meter, the scale of which is not exposed to a 
 contact with corrosive or coloring liquids. 
 The French chemical thermometer is mostly 
 a glass tube, which contains a thermometer 
 and scale, or else the scale alone is defended 
 by the extra tube. See figures ABC. The 
 English chemical theraiometer is made and 
 graduated like the common one, except that 
 the lower part of the scale is made with a 
 hinge which folds back, so that the ball alone 
 is immersed in the liquid, the temperature 
 of which is to be ascertained, fig. D. 
 
 i 
 
 Chemistry. Biande defines chemistry aa 
 " an art which teaches us the properties of the 
 elementary substances, and of their mutual 
 combinations. It inquires into the laws 
 which affect, and into the powers which pre- 
 side over their union ; it examines the pro- 
 portions in which they combine, and the 
 modes of separating them when combined ; 
 and endeavours to apply such knowledge to 
 the explication of natural phenomena, and 
 to useful purposes in the arts of life." It is 
 divided into organic chemistry, and inorganic 
 chemistry. The first treating of organized 
 bodies, such as plants and animals ; the 
 other of unorganized, such as minerals and 
 factitious products. The latter division of 
 the subject is further subdivided into analy- 
 tical and synthetic, or the art of separating 
 and the art of combining bodies ; also that 
 part of inorganic chemistry which relates to 
 the gases is often called pneumatic chemistry. 
 
 Chevaux de Frise. Fixed lances, or 
 spikes, so arranged that their points cross 
 
CH 
 
 CH 
 
 each other, and offer an impediment in every 
 direction to the passage of a person or horse 
 across them. 
 
 Chkvkon, or Zigzag Work. An orna- 
 ment characteristic of Norman architecture, 
 though found occasionally among the early 
 English buildings. 
 
 Chiaro-obscuro. In painting, the art of 
 judiciously distributing the lights and shadows 
 of a picture ; also it is used to designate those 
 pictures which are painted with white and one 
 other single color, yet representing the object 
 in its natural tint — such, for example, would 
 be the representation of a piece of statuary, 
 if drawn upon tinted paper with black chalk, 
 the lights being thrown in with white. 
 
 Chiliad. An assemblage of several things 
 ranged by thousands. The term was parti- 
 cularly applied to tables of logarithms, which 
 were first arranged in thousands. 
 
 Chiliagon. a plain figure of 1000 sides 
 and angles. 
 
 Chill Hardening. A method of tem- 
 pering steel cutting implements , by subj ecting 
 them, when red hot, to a strong blast of cold 
 air, by which they become hardened, as if 
 they had been plunged into a cold liquid, 
 though more delicately. It is said that the 
 method succeeds best with case-hardened 
 goods. 
 
 Chime, Electrical. An instrument to pro- 
 duce the musical sound of a small chime of 
 bells by electrical agency. 
 
 The foot-board has arranged on it several 
 bells, placed so that their inner edges are in 
 a circle. In the centre is a glass rod, bearing 
 upon it a moveable flyer, made of wire. (See 
 Flyer.) A wire hangs perpendicularly down 
 from one arm of this, near to the bells, and 
 has the lower end turned up at an angle, and 
 perforated, to guide a silk thread, which 
 bears a small metal ball. When the appa- 
 ratus is electrified, the flyer turns round, and 
 the ball or clapper strikes each bell in succes- 
 sion, producing thereby an agreeable sound. 
 
 Chime, Electro -magnetic. Any of the 
 rotatory electro-magnetic apparatus may be 
 made subservient in moving a clapper against 
 a chime of bells. The rotatory bucket of 
 Ampere, (see Ampere,) is that usually em- 
 ployed for the purpose, as follows : — 
 
 A is the rotating bucket. B the magnet, 
 about the pole of which it rotates. C the 
 clapper, suspended on a thread, with a wire 
 to control its centrifugal motion. D the 
 stand for the chime of bells. 
 
 Chimney. That part of a building in 
 which the fire is contained, and through 
 which the smoke passes away. The parts of 
 a chimney are as follows : — The opening into 
 the room, called the fire-place. The stone 
 or bricks under the fire-place, or the hearth. 
 That on the same level before the fire-place, 
 or the slab. The vertical sides of the opening, 
 and which form also part of the walls of the 
 apartment, are called jambs. The stone or 
 wood resting on these is the mantle. The 
 shelf which rests upon this, the mantle shelf. 
 The whole hollow space from the fire-place 
 to the top of the wall is the funnel. The 
 part of the funnel where it contracts above 
 the stove is the gathering. From this place, 
 which is called the throat of the chimney, 
 to the top is the flue. The wall of the apart- 
 ment, which covers over the flue, and pro- 
 ceeds from the mantle upwards to the ceiling, 
 is the breast of the chimney. The portion 
 above the roof is the shaft, and the upper 
 extremity the chimney top, which is usually 
 crowned with a hood, vane, or chimney pot. 
 
 p 
 
CH 
 
 CII 
 
 China Glaze, for printing blue ware, is 
 made by mixing 10 parts of glass, 2 parts of 
 lead, and 3 or more of blue calx. 
 
 China Ware. A fine description of por- 
 celain, either brought from the East, or formed 
 in imitation of such as is made there. Its 
 particular excellence is derived from the fine 
 quality of the clay employed. (See Clay.) 
 Chinese Fire. A composition used in 
 fire works. It is made by mixing the fol- 
 lowing ingredients, and ramming the mixture 
 into rocket and other cases : Red — Salt- 
 petre, lib. ; sulphur, 3 oz. ; charcoal, 4 oz. ; 
 iron-sand, 7 oz. White — Saltpetre, 1 lb. ; 
 bruised gunpowder, 12 oz. ; charcoal, 8 oz. ; 
 iron-sand, 11 oz. 
 
 Chip. A small piece cut away from any 
 material by an acute angled instrument. 
 
 Chipping. The operation of cutting away 
 smaU irregular pieces from a block of stone, 
 or a brick, to hew it into a required form. 
 Also taking off, by means of chisels, the outer 
 rind or coat of cast iron, previous to smooth- 
 ing the surface by files. 
 
 Chipping Pieces. The projecting pieces 
 of iron cast on the facings of iron framing, 
 when intended to be rested against each other. 
 Chisel. An instrument used in masonry, 
 carpentry, and joining ; and also by statuaries, 
 carvers, and numerous other artizans, for 
 cutting either by the impulse of pressure, or 
 of the blows of a mallet or hammer. There 
 are numerous kinds of chisels, named ac- 
 cording to the uses to which they are applied. 
 Chit. An instrument for cleaving lathes, 
 sometimes called a cleaving iron. 
 
 Chitine. a new principle discovered by 
 M. Odier in insects, by plunging beetles, &c. 
 into a hot solution of potass, which dissolves 
 all but the chitine. It is, therefore, inso- 
 luble in a solution of potass, but soluble in 
 hot sulphuric acid. It bums without losing 
 its form, and nitric acid does not turn it 
 yellow. It contains no azote. 
 
 Chlandi's Lines. If a plate of glass 
 be held either by the middle, the edge, or 
 the comer, some sand or other powder be 
 sprinkled over it, and a violin bow be then 
 drawn across the edge of the glass, so as to 
 produce a sound from it, it wUl be observed 
 that the glass vibrates only in particular parts, 
 where the sand will be scattered, the re- 
 maining parts of the glass remaining at rest ; 
 the sand will then become collected together 
 in the form of lines of considerable regularity 
 and variety ; these are called nodal lines, or 
 from their discoverer, Chlandi's lines-. Their 
 variety and frequency depends upon the de- 
 gree of pressure of the bow, and the part of 
 the glass to which the force is applied. In 
 the complex figures annexed as examples, 
 two and sometimes three bows are used at 
 different parts of the glass, giving it a com- 
 pound vibration : — 
 
 Chloral. A kind of ether, produced by 
 passing a large quantity of chlorine, carefully 
 dried, through anhydrous alcohol. This pro- 
 cess is continued for several days, and seve- 
 ral hours each day. The product is mixed 
 with twice its weight of sulphuric acid, and 
 distilled, and afterwards again distilled oft 
 fresh acid. It is of no known use. 
 
 Chlorates. Combinations of the chloric 
 acid and alkaline or metallic bases. They 
 were formerly called oxymuriates. 
 
 Chlorate Matches, are made by dip- 
 ping small strips of wood, or card, into a 
 mixture of chlorate of potass, made as fol- 
 lows : — Gently mix together, with a knife or 
 spatula, 30 parts of the chlorate of potass, in 
 fine powder, with 10 parts of powdered sul- 
 phur, 8 of sugar, 5 of gum arable, both also 
 powdered, with enough of vermillion to give 
 it a rose-colored tint, and water to reduce it 
 into a thin paste ; the sulphur should be ad- 
 ded last. When dry, the matches are to be 
 inflamed by touching them with sulphuric 
 acid, which is usually kept in a phial for that 
 purpose. 
 
 Chloric Acid. A sOur colorless fluid, 
 not existing but in union with water or some 
 base. It may be procured by passing a cur- 
 rent of chlorine through a mixture of oxyde 
 of silver and water. The excess of chlorine 
 which the filtered liquid contains is separable 
 by heat, and the chloric acid dissolved in 
 water remains. Its compounds are called 
 chlorates, or oxymuriates. 
 
CH 
 
 CH 
 
 Chlorides. Salts which are a combina- 
 tion of hydrochloric acid, with bases, formerly 
 called muriates. 
 
 Chlorine. The name given by Sir Hum- 
 phrey Davy to a gas, which long went 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 obtained in the small way by 
 distilling in a glass retort, at a gentle heat, 
 3 parts of common salt, 1 part of black 
 oxyde of manganese, and 2 parts of sulphu- 
 ric acid. The gas which comes over is of a 
 yellowish green color, and its odour and taste 
 are so strong, stifling, and 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. 
 First — Its affinity for hydrogen is superior 
 to that .of any other substance, whence it is 
 extremely useful in destroying contagious 
 miasmata; and second — Its destructive ac- 
 tion upon vegetable colors, when aided with 
 a little moisture. Scheele first remarked 
 this property; Berthollet applied it to bleach- 
 ing, in France, and Mr. Watt introduced its 
 use into Great Britain. The alkaUne metals, 
 as well as copper, tin, arsenic, zinc, anti- 
 mony, in fine laminae or filings, burn spon- 
 taneously in chlorine, and phosphorus takes 
 fire in it at ordinary temperatures. 
 
 Chloriodic Acid. A union of 2 pro- 
 portionals of chlorine, and 1 of iodine. 
 
 Chlorionic Acid. A union of 1 pro- 
 portional each of chlorine and of iodine, but 
 which forms no permanent compound. — 
 Brande. 
 
 Chloro-carbonic Acid. A gaseous 
 compound, procured by exposing a mixture 
 of equed measures of dry chlorine and car- 
 bonic oxyde gases to sunshine. 
 
 Chlorochromic Acid. A gaseous com- 
 pound, formed by the action of sulphuric 
 acid on a mixture of chloride of sodium, 
 (common salt,) and chromate of lead. 
 
 Chlorocyanic Acid, was named by 
 BerthoUet the oxyprussic acid. It is pro- 
 cured by transmitting a stream of chlorine 
 gas into an aqueous solution of hydrocyanic 
 acid, removing the excess of chlorine by agi- 
 tation with mercury, and then expelling by 
 heat the gaseous cyanide of chlorine. It is 
 soluble in water and alcohol. 
 
 Chloroform, A dense limpid fluid, ob- 
 tained by the distillation of chloral with lime 
 and water, and afterwards shaking it with 
 sulphuric acid, and finally distilling it over 
 barytes, in a dry retort. 
 
 Chlorometry, is the name given by the 
 French to the process for testing the de- 
 coloring power of any combination of ehlo- 
 
 n 
 
 fine. The usual method is to procure a so- 
 lution of indigo of a known strength, and 
 mixing the solution of chlorine with it until 
 the blue color is destroyed, when the greater 
 or less quantity of chlorine which has been 
 found necessary will indicate the strength of 
 it. 
 
 Chlorometer. An instrument to mea- 
 sure the quantity of chlorine in any salt or 
 solution. One described by 
 Dr. Ure is as follows : — He 
 says, " as chlorine or chlo- 
 ride of lime, when mixed 
 with water of ammonia, cau- Q 
 ses the dis-engagement of 
 azote, the quantity of this 
 gas evolved may be made the 
 foundation of an accurate 
 dhlorometer. The two sub- 
 stances should be mixed over 
 mercury in a graduated sy- 
 phon tube. The short end 
 A, and the open end B, are 
 both graduated to one scale ; 
 for example, to hundredths 
 of a cubic inch, or to grain 
 or 10-grain measures. The 
 tube is to be filled with mer- 
 cury, and then ten measures 
 of it are to be displaced at the 
 open end, by inserting a wooden plug. This 
 space being filled with the solution of chlo- 
 ride of lime is to be turned up into the short 
 end, by covering the open end with the fin- 
 ger, and inverting the tube. Tlie ammonia 
 being now let up will cause a reaction, and 
 evolve a quantity of azote, equivalent to the 
 chlorine present." 
 
 Chloronitrous Gas. When fused chlo- 
 ride of calcium, (muriate of lime,) is moist- 
 ened with nitric acid, a pale reddish yellow 
 gas is evolved, composed of equal volumes 
 of chlorine and nitric oxyde, combined 
 without condensation. 
 
 Chloro-oxalic Acid. Procuredbytreat- 
 ing crystaUizable acetic acid with dry chlorine 
 in excess. It forms rhombic, dendritic crys- 
 tals. 
 
 Chlorophane. a bluish green variety 
 of Derbyshire spar or fluate of lime, which, 
 when slightly heated, gives, for some time 
 afterwards, a beautiful green phosphorescent 
 Ught. 
 
 Chlorophyle. The green coloring mat^ 
 ter of the leaves of plants. 
 
 Chloric Oxyde. Deutoxyde of chlo- 
 rine. 
 
 Chlorous Acid, supposed to be identical 
 with peroxide of chlorine. 
 
 Chlorous Oxyde. Protoxyde of chlo- 
 rine, called also euchlorine. 
 
 Chlorurets, the same as chlorides, for- 
 merly called muriates. 
 Choak Damp. Carbonic acid gas. 
 
CH 
 
 CH 
 
 Chock. A loose piece of wood, stone or 
 metal, put into any piece of machinery for 
 the purpose of filling up a cavity, or of 
 adding a greater weight to it. Thus the 
 stones with which a mangle is filled are 
 chocks, so also is the weight rested upon a 
 bush harrow — upon a bellows, &c. 
 
 Choir. The chancel of collegiate or ca- 
 thedral churches. 
 
 Cholesterates. Salts formed with cho- 
 lesteric acid. 
 
 Cholesteric Acid is formed by heating 
 cholesterine with its own weight of concen- 
 trated nitric acid. It is orange yellow in 
 the mass, but the crystals are white and aci- 
 cular. It is soluble in alcohol, insoluble in 
 water. 
 
 Cholesterine. The basis of animal bile, 
 procured by reducing human gall stones to 
 powder, adding boiling alcohol, and filtering 
 the solution rapidly. It is crystalline, lamel- 
 lar, white, brilliant, and very like spermaceti. 
 
 Cholates. Salts formed with cholic 
 acid. 
 
 Cholic Acid. A peculiar animal acid 
 found in human gall, in which it exists as 
 cholate of soda. 
 
 Chondrometer. a balance for weighing 
 com ; upon the principle of the steel-yard. 
 
 It consists of a small measure holding about 
 half a pint, which is balanced by a beam 
 and sliding weight on the opposite side of 
 the fulcrum. This beam is so graduated that 
 when the measure is filled even with the top 
 with corn, and the weight is moved along the 
 beam, it indicates not the positive weight of 
 the corn in the measure, but how much such 
 com would weigh per bushel ; for example — 
 if the weight stands at 40, the com would 
 weigh so much per bushel ; and the other 
 conditions of it being the same, the value of 
 the corn would be in proportion, according 
 to its kind. 
 
 Chord. A right line joining the extremi- 
 ties of an arc. 
 
 Chorography. Tlie art of drawing maps 
 of particular provinces or districts. It is, 
 therefore, less extensive than geography, 
 which includes a description of the whole 
 earth, and more extensive tlian topography, 
 which confines itself to a single place or town. 
 
 Christison's Apparatus, for detecting 
 poisons. Fig. A, B, C, D, E, F. A is an 
 instrument for reducing the sulphurets of 
 some of the metals by a stream of hydrogen 
 gas. B a funnel-shaped tube for testing 
 minute portions of liquids. C a tube for 
 reducing a small quantity of mercury. D a 
 tube for taking up a minute globule of ditto. 
 E bottle and tube for washing down scanty 
 precipitates or filters. F apparatus for the 
 distillation of fluids supposed to contain 
 acids. 
 
 Chromates. Salts formed by a union 
 of the alkalies, earths, and metals, with Ihe 
 chromic acid. The principal chromates used 
 in the arts are those of potass, and lead. 
 
 Chromate of Potass is prepared by ex- 
 posing a mixture of 4 parts native chro- 
 mate of iron with 1 of nitre, to a strong 
 heat for some hours, and washing out the 
 resulting soluble matter ; these washings yield 
 chromate of potass by evaporation. It is in 
 the state of yellow crystals, which dissolve in 
 water, but not in alcohol. It is valuable 
 to the calico printers, in the manufacture of 
 chrome colors, and as a chemical test, preci- 
 pitating the metals of very different and often 
 beautiful colors. The bichromate of potass 
 is made from the chromate by adding to its 
 solution a sufficiency of sulphuric acid to 
 give it a sour taste, setting it aside for a day 
 or two, when deep red crystals will be de- 
 posited. This salt is largely memufactured 
 in the North for the use of calico printers. 
 
 Chromate of Lead. (See Chrome Yel* 
 low.) 
 
 Chromatics. That division of the science 
 of optics which treats of the colors of light, 
 their several properties, and the laws by 
 which they are separated, and their sepa- 
 rated parts re-combined. 
 
 Chromatic Vernier. An instrument, 
 invented by Dr. Brewster, for ascertaining 
 by comparison faint differences in the tints 
 of polarized light. It consists of a thick 
 piece of plate glass, ground to the shape of a 
 wedge, and which has been rendered red hot, 
 and then rapidly cooled at the edges, which 
 
CH 
 
 CH 
 
 gives it a double-refractive structure. (See 
 A B in the following cut.) By this operation 
 
 its tints will increase from B to A, so that if 
 the maximum tint near A is a full yellow, it 
 will shade oflF in white near B. In a wedge 
 of this kind, 2 inches long and 8° of anguleir 
 measurement, we have an instrument of con- 
 siderable extent. To use it, if it be required 
 to ascertain very exactly the tint of a plate 
 of crystal, it must be held to the light, as in 
 the figure, and moved gradually from A to B. 
 When it has the position C D, the figure m 
 is opened horizontally, which proves that 
 the tints of the wedge are higher at the 
 point m than those of C D. In the po- 
 sition G H the tints are opened vertically, 
 and therefore the tints of the crystal are 
 higher than those of the wedge. But in the . 
 intermediate position E F a dark cross is 
 produced, which indicates the perfect equality 
 of the tints of the glass and crystal. Thus 
 by a graduated scale attached to the instru- 
 ment all tints may be compared to each other. 
 
 Chrome Colors. A name employed by 
 artists and painters to designate any colors, 
 which, when dry, are of that soft powdery 
 consistence that they may be mixed up with 
 oil, and form a uniform soft color, without 
 grinding with the muller. Those colors 
 which are truly chromes must have the metal 
 chromium in their composition, and are the 
 following, though many other colors besides 
 these would be included in the first general 
 definition. 
 
 Chrome Blue, or a blue oxyde of chro- 
 mium, may be made thus : — Make a satu- 
 rated solution of chromate of potass, add 
 weak sulphuric acid to combine with the 
 potass. Then add one-eighth part of com- 
 mon salt, and one-sixteenth by weight of 
 strong sulphuric acid. The liquor will now 
 assume a green color. It is then evaporated 
 to dryness ; then re-dissolved, and filtered ; 
 finally the greenish blue oxyde of chromium 
 is to be precipitated by caustic potash, and 
 collected on a filter. It is used chiefly as an 
 enamel color. 
 
 Chrome Green. A color extensively 
 used in dyeing, and for the staining articles 
 of porcelain of a fine green color. It may be 
 economically and easily made by boiling 
 
 chromate of potass, dissolved in water, with 
 half its weight of flowers of sulphur, till 
 the resulting green precipitate ceases to 
 increase, which may be readily ascertained 
 by filtering a little of the mixture. The 
 addition of some potass accelerates the 
 operation. 
 
 Chrome Red. This is a subchromate of 
 lead procured thus — Into saltpetre, brought 
 to fusion in a crucible at a gentle heat, pure 
 chrome yellow is to be thrown by small por- 
 tions at a time. A strong ebullition takes 
 place at each addition, and the mass becomes 
 black and remains so while it is hot. Suf- 
 fering it to rest for a few mmutes, during 
 which the dense basic salt falls to the bottom, 
 the fluid part is to be poured off. The mass 
 remaining in the crucible is to be washed 
 and dried, forming the red powder required. 
 This color as well as the next are used ex- 
 tensively in dyeing, and by the painter both 
 in oil and in water colors. 
 
 Chrome Yellow, Orange, &c., or 
 Chromate of Lead. A rich pigment of 
 various shades from deep orange to pale 
 yellow. It is made by adding a limpid solu- 
 tion of the chromate of potass to a solution, 
 equally limpid, of acetate or nitrate of lead. 
 A precipitate falls, which must be well washed 
 and carefully dried out of the reach of sul- 
 phuretted vapours, a lighter shade of yellow 
 is obtained by mixing some solution of alum 
 or sulphuric acid with the chromate, before 
 pouring it into the solution of lead, and an 
 orange tint is to be procured by the addi- 
 tion of subacetate of lead in any desired 
 proportion. 
 
 Chromic Acid, or Peroxyde of 
 Chrome, is a ruby red powder, of a sour 
 metallic taste, extracted from the red lead 
 ore of Siberia, and also from the mineral 
 chromate of iron. From the former it 
 is procured by treating it with carbonate 
 of potass, and separating the alkali by means 
 of a more powerful acid, or it may be made 
 by decomposing any of the artificial chro- 
 mates. Chromic acid unites with the alka- 
 lies, and most of the earths and metals ; form- 
 ing chromates. 
 
 Chromium. A metal of an iron grey co- 
 lor, procured by intensely heating its native 
 combinations, which are those of iron and 
 lead, with charcoal. It is brittle, difficult of 
 fusion, and not easily acted upon by acids. 
 It unites with oxygen in three proportions, 
 forming a sesquioxyde, a deutoxyde, and a 
 peroxyde ; the latter of which having acid 
 properties is called also chromic acid. It 
 also unites with chlorine, fluorine, sulphur, 
 nitrogen, phosphorus, and carbon. 
 
 Chronometer. A watch or small time 
 piece, made with such exactness as not to 
 alter its rate of going by change of climate, 
 or position, or any other natural and orili- 
 
CI 
 
 CI 
 
 nary casualty to which it may be exposed. 
 As ships at sea have in hazy weather no 
 means of ascertaining time but by the chro- 
 nometers, it is necessary that every care 
 should be taken in their construction. 
 
 Chrysoberyl. a precious stone of a pale 
 green color, resembling the beryl and aqua- 
 marine. 
 
 Chrysolite. A precious stone of a yel- 
 low color, intermediate in hardness between 
 amethyst and felspar. It is often called the 
 yellow topaz. 
 
 Chuck. An appendage to a lathe, which 
 being screwed on to the nose of the mandril 
 enables the workman to fix firmly any mate- 
 rial that he may be desirous of turning. 
 Chucks are either simple or compound. 
 Simple chucks, the names of which are the 
 Arbor, Branch, Driver, Ring, Surface, Uni- 
 versal, ^c, and under which names they are 
 described and figured, have no tendency to 
 alter the centre of rotation of the work fiiJed 
 to them, it always corresponding to that of 
 the mandril ; but the compound chucks, such 
 as the oval, the eccentric, &c., have such 
 capabilities of adjustment, that the centre 
 may be changed at pleasure, and also allow 
 of such movements that the circularity of 
 motion may be changed into other curves. 
 
 Cilery. The drapery or foliage on the 
 heads of columns, not applied to the clas- 
 sical orders, but rather to the undefinable and 
 diversified ornaments found in Gothic, Moor- 
 ish, and similar buildings. 
 
 CiLL. (See Sill.) 
 
 CiMA, or Ogee. A moulding waved on 
 its contour; one part being concave, the 
 other convex. There are two kinds — the 
 upright ogee, in which the concave part pro- 
 jects most, and the heel or inverted ogee, 
 which has the convexity most prominent. 
 This last, with its fillet above, is always the 
 upper moulding of a classical cornice. 
 
 CiMBiA. A fillet, string, list, or cincture, 
 around any part of a building. 
 
 CiNCHONATES, Or QuiNATES. Compo- 
 sitions of cinchonic acid and various bases. 
 
 CiNCHONic, or KiNic Acid. An acid, 
 contained in different species of cinchona, 
 existing in the state of cinchonate of lime. 
 
 CiTREAL. Oil of lemons. 
 
 CiNCHONiNE, or CiNCHONiA. An alka- 
 loid which forms the distinguishing charac- 
 ter of Peruvian bark, and in which alone its 
 medicinal properties appear concentrated. 
 
 It is extracted from ihepale bark, while an 
 analogous substance, called quinia, is ex- 
 tracted from the red bark. The only diffe- 
 rence between them appearing to be that the 
 latter contains a double quantity of oxygen 
 in its composition. 
 
 Cincture. A ring or fillet at the top or 
 bottom of the shaft of a column, called also 
 the astragal, (which see.) 
 
 Cinnabar. A beautiful red pigment, 
 composed of sulphur and mercury ; hence in 
 chemical nomenclature called sulphuret of 
 mercury. (See Vermillion.) 
 
 CiNdUEFOiL. An ornament of five leaves 
 united ; common in the tracery of windows, 
 in parapets, &c., of Gothic buildings. 
 
 Cipher. One of the numerals, marked 0, 
 signifying nothing by itself, nor yet when 
 placed on the left-hand side of a common 
 number, or the right-hand of a decimal; 
 yet when placed on the left of the latter it 
 diminishes it ten-fold, and when on the right 
 of a common number it increases it in a like 
 proportion. 
 
 Circle. A plane figure, bounded by a 
 curved line, which is everywhere equally dis- 
 tant from a certain point within it, called 
 the centre. All circles are supposed to be 
 divided into 360". {^te Angle.) The length 
 of the degree varying according to the size 
 of the circle. 
 
 The principal parts of a circle are the 
 centre, A ; the circumference or outer line 
 B B B C E D ; the diameter, which is any 
 line drawn across from one side to the other, 
 and through the centre, as B A B, and the 
 radius, which is half a diameter, or the dis- 
 tance from the centre to the circumference 
 A B. Half a circle is a semi-circle ; one 
 quarter is called a quadrant ; one-sixth is a 
 
CI 
 
 CI 
 
 •extant, &c. A line which passes across a 
 circle, if not a diameter, is called a chord, 
 as C D, and the portion of the circle cutoff 
 by it is a segment, while the part of the cir- 
 cumference thus cut off is an arc, as C E D. 
 
 Circles of Altitude, the same as the 
 circles of latitude, but instead of being ap- 
 plied to find the latitude of a place, they are 
 used to find the altitude of a heavenly body 
 above the horizon. 
 
 Circle of Curvature. That circle the 
 curvature of which is equal to that of any 
 curve at a certain point. It is also called 
 the circle of equal curvature. 
 
 Circles of Declination. A number 
 of circles drawn around the tropical regions 
 of the earth, parallel to the equator, and in- 
 tended to indicate the declination of the sun 
 as he passes either of them in his passage 
 either to or from the colures or tropics. 
 
 Circles, Diurnal. Circles parallel to 
 the equinoctiad, described by the stars in 
 their apparent diurnal rotation about the 
 earth. 
 
 Circles of Excursion. Circles parallel 
 to the ecliptic, and at such a distance from it 
 as that the excursions of the planets may be 
 included within them ; they are usually fixed 
 at 10°. 
 
 Circle, Galvanic. Every galvanic appa- 
 ratus so arranged that the fluid can circulate 
 around, provided that apparatus also excites 
 or disturbs the fluid in the first instance, is 
 called a galvanic circle, because the electric 
 fluid always endeavours to pass from one 
 end to the other of it and back again by some 
 other conducting channel, it may be a wire, 
 water, charcoal, &c. Galvanic circles are 
 either simple or compound ; the former is 
 composed of a single pair of elements and 
 one conductor, and the latter of several sim- 
 ple circles following each other. A simple 
 galvanic circle is seen below, where there are 
 two metals ; in A touching one another at top, 
 (one metal is copper, the other zinc,) in B 
 connected with each other by two wires, there 
 being acidulated water between in the glass 
 vessel. The galvanic fluid passes from the 
 zinc to the acidulated water, hence to the 
 copper, and through that to the zinc again, 
 passing in a circuit or circle. A compound 
 galvanic circle is seen in the Couronne de 
 Tosses. 
 
 Circles, Horary, in dialling, are the lines 
 which show the hours on dials, though these 
 
 may be drawn straight rather than circular. 
 
 Horary, or hour circle, is also a small circle 
 revolving with or attached to an artificial 
 globe, being situated concentric with the 
 pole, and intended to indicate the relative 
 time at particular places, and to solve other 
 problems connected with geography and 
 astronomy. 
 
 Circle of Illumination. If a globular 
 body be presented to a strong light, as that 
 of the earth to the sun, one half of it exactly 
 will be illuminated, the rest will remain in 
 darkness. The boundary between this light 
 and darkness is the circle of illumination. 
 If there were no atmosphere to the earth ; in 
 passing this circle, we should immediately 
 plunge from one extreme to the other ; but 
 owing to the refraction of the atmosphere 
 and reflection from the surface of the earth, 
 we have an intermediate state called twilight. 
 This state, however, is exterior to the true 
 circle of illumination. 
 
 Circles of Latitude. Circles drawn on 
 the artificial globe, parallel to the equator, 
 to indicate the latitude of places upon the 
 earth's surface. On the celestial globe they 
 are parallel to the ecliptic, or sun's course, 
 and serve to indicate the latitude of the stars. 
 
 Circles of Longitude, or Meridians 
 OF Longitude. Great circles extending from 
 pole to pole of the earth , at equal distances from 
 each other ; of use to indicate the time of 
 the sun's arrival at each in his apparent diur- 
 nal rotation ; and thereby to indicate the 
 relative time at different places, or their po- 
 sition from each other, reckoning east or west 
 from a certain point. 
 
CI 
 
 CI 
 
 Circle op the Sphere. Any circle de- 
 picted on the artificial globe, for the purpose of 
 marking the position of places, the course of 
 a heavenly body, &c. These circles are divi- 
 ded into two kinds ; great circles, or such as 
 divide the globe into two equal portions or 
 hemispheres ; and less circles, or such as cut 
 off a portion less than half. For example, 
 the meridians of longitude, the ecliptic and 
 the equator, are great circles. The tropics, 
 the polar circles, the lines of latitude, both 
 above and below the equator, are less circles, 
 the whole of them being circles of the sphere. 
 Corresponding terms may be used for the 
 corresponding parts of all globes. (See Ar- 
 millary Sphere.) 
 
 Circle of Perpetual Apparition and 
 Perpetual Occult ation. The first is a cir- 
 cle drawn at such a distance from the pole of 
 the heavens, that the stars within it never set 
 in that latitude for which the circle has been 
 drawn. The circle of perpetual occ\iltation 
 is that the stars of which never rise in that 
 latitude ; therefore these circles are always 
 of corresponding size, one around the north 
 pole, the other round the south pole. In the 
 space between them the stars rise and set 
 daily. At either pole these circles will be 
 united together in the equator, the inhabi- 
 tants, if any, never seeing more than one 
 hemisphere of stars, while those at the 
 equator see all the stars of both hemispheres 
 nightly. To them, therefore, the names of 
 these circles do not apply. 
 
 Circles, Polar, Two circles around the 
 globe, at the distance of 23^^° from either 
 pole, and forming the boundary between the 
 polar regions and temperate zones. That 
 near to the north pole is called the arctic 
 circle, and that around the south pole the 
 antarctic. 
 
 Circular Magnetic Coil. A flat coil 
 of wire rolled up, for the purpose of trans- 
 mitting a current of the electric fluid, which, 
 passing through it, produces the effects of 
 polarity and magnetic attraction, one side of 
 the coil being north, the other side south. 
 The term is used in distinction to that of 
 helix, or along coU of wire. The following 
 
 is one of the numerous magnetic circular 
 coils. (For others, see Cumming, De la Rive^ 
 Sturgeon, 8fc.) 
 
 Circular Polarization. (See Polaris 
 zation.) 
 
 Circular Saw. A thin plate of steel, 
 having saw-like teeth cut on the circumfer- 
 ence, and revolving by means of a lathe, or 
 rotating spindle, attached to it. Circvdar 
 saws are much used to cut veneers as well as 
 for rougher purposes. 
 
 Circulating Decimals. Those which 
 consist of a repetition of a small number of 
 digits, therefore not terminal. For exam- 
 ple, bring one-third into a decimal, which is 
 done by dividing the one with ciphers added 
 to it by 3, it will be found equsd to •3333. 
 The figure 3 being repeated continually, and 
 still leaving the remainder 1 , which prefixed 
 to another cipher, will, when divided, still 
 yield a 3, and would so for ever. -3333 is 
 therefore a circulating decimal ; so is '234 
 234234, &c. 
 
 Circumference. The outer boundary of 
 a circle or globe. (See Circle.) Often used 
 to signify the outer boundary of any other 
 shaped body, though the word periphery 
 would here be more proper. 
 
 Circumferentor. An instrument used 
 in surveying, in the same manner as a theo- 
 dolite, but being a less perfect instrument, 
 it is only employed where great accuracy is 
 not required. It consists of a tripod stand 
 which supports a magnetic compass famished 
 with two sights, the box which contains the 
 compass being divided on its circumference 
 into 360 degrees. The following cut is a 
 view of the top of the box, with the sights 
 attached to it. When used, the sights are 
 to be directed to an object in the distance 
 until it can be seen through them ; the num- 
 ber of degrees indicated by the magnetic 
 needle is then to be noted. Afterwards, the 
 sights are to be directed to a second object, 
 and the degrees observed in like manner ; 
 the difference between these and the former, 
 shows the angle of position between the two 
 places, which it is the object of the instru- 
 ment to ascertain. 
 
 Circumgyration. The whirling motion 
 of a body on any given centre. 
 
 CiRcuMPOLAR Stars. Those which re- 
 volve about the pole of the earth without 
 setting. 
 
 Circumscribe. To draw one figure on 
 the outside of another, the one being recti- 
 
CI 
 
 CL 
 
 linear, the other circular ; or else both figures 
 rectilinear, the sides- of one figure touching 
 all the angles of that within it. 
 
 CiRCUMVALLATioN. A round inclosure of 
 trenches or fortifications. 
 
 Circumvolution. The act of rolling 
 round. In architecture,^ the term is applied 
 to the spirals of the Ionic capital, every turn 
 of which is called a circumvolution. 
 
 CiRRHUs, Cirrus, or Curl Cloud. An 
 extended mass of light, fleecy, or fibrous 
 clouds, appearing like long locks of wool or 
 cotton stretched out. Its appearance is a 
 general indication of wind. 
 
 Cirro-cumulus, or Sonder Cloud. 
 Clouds differing from the cirrus, in being in 
 rather more solid and rounded masses, ex- 
 tended horizontally across the sky. This 
 usually accords with a rising barometer. 
 
 Cirro-stratus, or "Wane Cloud. A 
 horizontal stratum of clouds, attenuated 
 towards the circumference, the clouds being 
 separate or in groups, large or small. It in- 
 dicates a decrease of temperature, wind, and 
 rain : it is often called a mackerel sky. 
 
 CissoiD. A particular kind of curve, re- 
 presented and formed as follows : — 
 
 Let A B be a diameter of the circle, of 
 which half is seen in the figure, and B C an 
 indefinite line at right angles to A B. From 
 A draw several lines to B C, each line cutting 
 some part of the circumference, such as A D, 
 A E, A F, AC; and upon these lines set off 
 the corresponding equal distances ; viz. D G 
 = AH, EI = AK, FL=AM, andCN = 
 A O, then the curved line drawn through all 
 the points is the cissoid. 
 
 Citrates. Combinations of the citric 
 acid with various bases. The citrate of potass 
 is used in medicine as a mild diaphoi'etic. 
 
 Citric Acid. The acid which occasions 
 the sour taste and properties of the lemon, 
 lime, and other fruits. It is made thus : — 
 Saturate the lemon jviice with chalk, noting 
 
 the quantity of chalk used. The citrate of 
 lime precipitates, the supernatant liquor ts 
 poured off, clean water added, and for every 
 19 pounds of chalk used, 9 and a ^ of sul- 
 phuric acid are mixed with it. At the end 
 of twelve hours the citrate of lime will be 
 decomposed ; dilute nitric acid will float 
 above, and sulphate of lime be found at the 
 bottom. The acid may be drawn off, filtered 
 and evaporated to obtain the crystals of the 
 acid. Citric acid forms citrates with tbp 
 usual bases. • 
 
 Citric Ether. When a hot solution of 
 citric acid, mixed with alcohol, muriatic acid, 
 and a certain proportion of sulphuric ether, 
 is kept for six or eight hours at a temperature 
 between 125° and 135°, and then water added, 
 citric ether separates in the form of an oil- 
 like liquid. 
 
 Civil. In opposition to military or eccle- 
 siastical ; thus civil engineering is the science 
 and art of constructing machinery for ma- 
 nufacturing uses, constructions, and exca- 
 vations, of general transit, or ordinary pur- 
 poses, &c. Civil architecture teaches the 
 construction of private dwellings, public 
 offices, palaces, &c. A civil year is one by 
 which we compute ordinary time, without 
 reference to exact astronomical accuracy. A 
 civil day has no reference to light or dark- 
 ness, but consists of twenty-four hours, and 
 begins at 12 o'clock at night, &c. 
 
 Clack. A bell, so contrived that it shall 
 ring when more corn is wanted in a com 
 mill ; when any thing is wrong in the working 
 of a steam engine, &c. ; or generally a clack 
 is any thing which makes a clacking or ring- 
 ing noise. 
 
 Clack Valve. An extremely common 
 valve, used generally in hydraulic and steam 
 machinery, also for blowing machines, bel- 
 lows, &c. The following figure will render 
 its construction evident : — A represents the 
 valve open. B the same closed. It is merely 
 a flap of leather, wood, or metal, which covers 
 a hole, and which is attached to the side of 
 that hole by a hinge. It is often called a flap 
 valve. 
 
 Clamp. A bar of metal bent, or piece of 
 wood cut into a curved form, and furnished 
 at one end with a screw ; the whole intended 
 to affix two articles together, sometimes per- 
 manent, but more frequently for a temporary 
 purpose. For example, in glueing together 
 various parts of furniture, clamps are used 
 
CL 
 
 CL 
 
 until the glue is dry ; so also a small air 
 pump, electrical machine, or other apparatus, 
 is held to a table while working it, by means 
 of a clamp. The following are among the 
 numerous forms given to clamps : — 
 
 Clamp. A pile of unburnt bricks raised 
 for burning. 
 
 Clarification. The process of freeing 
 any liquid from its impurities, by throwing 
 them down by a chemical or mechanical mix- 
 ture added to them. For example, boiling 
 clarifies numerous extracts ; hops clarify 
 beer ; alum added to new gin throws down 
 any excess of the oil of juniper, and enables 
 it to mix with water without turning cloudy. 
 These are instances of clarification, and as 
 such are not to be confounded with filtering. 
 
 Clark's (Dr.) Compression Blow- 
 pipe. A powerful, but somewhat dangerous 
 instrument, the action of which is derived 
 from mixed gases ; (that is, oxygen 1 part, 
 and hydrogen 2 parts,) being powerfully com- 
 pressed in an appropriate vessel, and rushing 
 out with force through a jet upon the sub- 
 stances to be operated upon. Its construction 
 is as follows : — 
 
 A is an exhausting and condensing syringe ; 
 intended, first, to draw the atmospheric air 
 from the "square box C, and afterwards to 
 compress into it the mixed gases contained 
 in B. The stop-cock L is then closed, and 
 the gases within C rush down the tube E, 
 through a piece of fine wire-gauze at the top 
 of it, and afterwards through the water F 
 in<e the vessel D. This vessel is filled with 
 
 water to about H, and has a piece of wi'e- 
 gauze across it at G, and another piece at I. 
 Through this piece it is that the gas finally 
 escapes to supply the jet K. The cock be- 
 longing to this being opened the gas issues. 
 It is a dangerous instrument, because in pro- 
 jjortion as the gas issues, and the compression 
 is diminished, the flame has a tendency to 
 recede through the jet, and ignite the gas 
 within the box D ; this breaking the wire- 
 gauzes renders the whole imperfect, and a 
 sudden and general explosion almost inevi- 
 table. It is, however, somewhat more safe 
 wlien accompanied with Gurney's blow-pipe 
 jet. (See Gurney.) 
 
 Clarke's (E. M.) Electrepeter. An 
 instrument for changing rapidly the direction 
 of electric currents. 
 
 A B B D are four brass cups, screwing 
 into, and passing through the bottom board 
 C C ; two brass pillars also screv»!^ing into, 
 and passing through the bottom board, having 
 slits filed in their heads, into which two 
 moveable brass frames fit ; these being con- 
 nected together by two ivory rods at the ends. 
 Tour brass cups E E F F also screw into the 
 bottom board, and pass through it ; cvxp A 
 is connected beneath by a wire with cups E E ; 
 cup D with F F, and cups B B with the 
 pillars C C. Consequently the fluid en- 
 tering the cup A will pass to E, then to the 
 other E, and then up the frame, down the 
 nearest pillar, and so on to B ; upon re- 
 versing the frame so that its points dip into 
 the other small cups, the fluid will pass from 
 A to the nearest cup E, thence up the frame, 
 and down the pillar C, to the farthest stud B, 
 instead of the nearer stud as before. Mer- 
 cury is put into the small cups, into which 
 the points of the frames dip before using the 
 instrument. 
 
 Clarke's (E. M.) Electro-Gasome- 
 ter. An instrument for collecting and ascer- 
 taining the quantity of mixed gases, which 
 rise from the decomposition of water by the 
 galvanic apparatus. 
 
 A a glass vessel, having at and through 
 the bottom of it two wires, as repi'esented at 
 B. C a graduated glass tube, sealed at the 
 top, and standing over the platiimm wires. 
 D a circular piece of wood, in which A fits 
 loosely. In the centre is a divided chamber, 
 the two cells of which are connected by wires 
 with the mercury cups. To use the instru- 
 
CL 
 
 CL 
 
 merit ; having filled the vessel A with water 
 up to A, close the air-liole F, and invert 
 
 the whole that the water may flow into, and 
 fili C ; liaving put mercury into each divi- 
 sion of the chamber E, and also in the mer- 
 cuiy cups, place A in D, so that the points 
 of the platinum wires may dip one into each 
 of the divisions at E. The power of the bat- 
 tery is noted by the amount of gases given 
 off. 
 
 Clarke's (U.) Electro - Magnetic 
 Coil Machink. A slight modification of 
 Bachhoffner's coil machine, the difference 
 being in the wheel which breaks contact, in 
 the bundle of wires being hid, and in the 
 compound coil being placed upright, instead 
 of across. (See BachJioffner.). 
 
 The part for breaking contact consists of 
 a v.heel made of brass, with notches cut out 
 of the circumference, in which notches small 
 pieces of ivory are inserted ; one of the bat- 
 tery wires touching the spindle, or axis, of 
 this wheel preserves its contact with the brass, 
 but the otlicr wire, v/liich leans against the 
 
 rim, touches metal and ivory alternately. To 
 the brass studs A and B ai-e fastened the ends 
 of the secondary wire ; to this part is at- 
 tached, v/hen occasion requires, the wires to 
 communicate the shock. The terminations 
 of the primary coil are joined to the pillars 
 at the back of the machine, one of which is 
 seen at F. The wires from the battery are 
 attached to C and D ; these pillars being also 
 attached to the back pillars. 
 
 Clarke's (U.) Electro - Magnetic 
 Engine. It is known that while an electric 
 current is traversing along a wire, which is 
 coiled over a bar of iron, that bar of iron 
 acts like, or in fact becomes a magnet, but as 
 soon as the contact is broken its magnetic 
 power ceases, to be renewed again, and again 
 broken at every change. 
 
 In the above cut A is a crank, attached to 
 a fly wheel, and to a light bar of iron B. 
 is a temporary magnet, such as has been spo- 
 ken of ; if then the horse-shoe iron C be con- 
 nected with an electrepeter, and that with a 
 battery, it will at one moment draw down 
 the bar B ; but the next moment let it go 
 again, when the fly wheel being put in mo- 
 tion v/ill draw it up. At the next instant, 
 the firet action is renewed, but only to be as 
 quickly broken a second time. Thus alter- 
 nately rising and falling, a rotative action is 
 preserved in the wheel. 
 
 Clarke's (E. M.) Magneto-Electric 
 Machine ; or a machine to produce elec- 
 trical effects from a magnet. 
 
 A is a very powerful compound horse-shoe 
 magnet, each bar being 2 or 3 feet in its 
 whole length. It is fastened upright to a 
 back -board B, by means of the screw C: it 
 is elevated slightly upon a square piece of 
 wood at the foot. E and F are the two coils 
 of thin covered copper wire, each consisting 
 of about 700 yards of wire ; the ends of 
 which are soldered to the bar of iron in front 
 of them. From the centre of this bar pro- 
 jects a brass spindle, which passes on one 
 side, between the coils of the armature and 
 the cheeks of the magnets, through the board 
 B, and out at the back, where there is •*- 
 
CL 
 
 CL 
 
 tached to it a small wheel, that is worked by 
 a cord passing the larger wheel D. The fore 
 
 part of the spindle is terminated by a wire G, 
 and a break piece at the end of it, and is seen 
 of a larger size above ; the spindle being 
 marked K, the wire G, and the break piece I. 
 J is a brass pillar, inserted into the stand, 
 and holding on the upper end a wire, which 
 presses against the break piece I. H is a 
 block of wood, with a strap of brass on each 
 side ; one bearing a wire which reaches to K, 
 the other the pillar and wire J. The circuit 
 then will be complete, by joining the metala 
 on each side of the block H. This may be 
 done either by a wire, or by a pair of handles 
 attached in a proper manner ; of course any 
 thing connecting these parts will receive the 
 magnetic shock. 
 
 Clarke's (E. M.) Thermo-Electro- 
 METER. A name given by Mr. Clarke to an 
 instrument which professes to ascertain the 
 deflagrating, or heating power of an electric 
 current. 
 
 A and C are the two wires, connected with 
 the galvanic battery, dipping into the mercury 
 cups B and E. D is a piece of platinum 
 wire, say the ninetieth of an inch diame- 
 ter, secured at B by a small forceps ; at the 
 other end E is also a pair of forceps, insu- 
 lated by a piece of ivory F ; having a binding 
 screw to press it tightly upon the ivory scale 
 G, which may be elongated by passing it 
 more or less thi-ough the socket of the foot 
 
 stand. It is needless to add, that the length 
 of wire, made red hot or burned, is the 
 measurer of power. 
 
 Claude Lorraine Glasses. The paint- 
 er Claude was accustomed to judge of the 
 effect of different lights, such as sunset, sun- 
 rise, moonlight, &e. upon a landscape, by 
 viewing it through an appropriately-colored 
 glass ; such glasses, therefore, as are tinted 
 blue, red, or yellow, and adapted for this 
 purpose, are called Claude Lorraine glasses. 
 Spectacles are sometimes made of a corres- 
 ponding nature for the use of artists. 
 
 Clay. An earth, consisting of alumina, 
 generally contaminated with silica, and occa- 
 sionally with lime, magnesia, and various 
 metallic oxydes, particularly those of iron. 
 It is readily diif usable in water, forming with 
 it a plastic mass, which may be kneaded or 
 moulded to any shape. It concretes on be- 
 coming dry, and when burnt, assumes a state 
 of extreme hardness, shrinking considerably 
 in the fire, and losing its capability of be- 
 coming ductile, when mixed with water. 
 Clays are divided into, first, fire clays, or 
 such as become extremely hard in the fire, 
 and remain afterwards scarcely altered by it ; 
 used for lining furnaces, making crucibles, 
 &c. Second, common clay, used in the ma- 
 nufacture of bricks, tiles, and the coarser 
 kind of pottery ware. Third, potter's or 
 plastic clay, or pipe clay, which is very duc- 
 tile, and becomes white in buniing, such as 
 is used for the common white ware, tobacco 
 pipes, &c. Fourth, Kaolin or China clay, 
 such as is used in the finer kind of porcelain. 
 This kind is found not only in China, but in 
 Saxony, France, Spain, and England, (in 
 Cornwall.) 
 
 Claying, Process of. Sugar after having 
 been boiled and purified by the sugar refiner, 
 is poured into conical pans ; these are placed 
 with their small ends downwards, and after 
 having somewhat cooled and drained, a thin 
 paste of pipe clay and water is placed on the 
 top of the sugar in the pans ; the water out 
 of this paste trickles through the mass of 
 sugar, and carries down with it the impurities 
 in the loaf; this process is called clayiny. 
 Some sugar requires it to be repeated four or 
 five times before it becomes perfectly purified. 
 
 Cleavage. Those who are accustomed 
 to polish precious stones and minerals are 
 aware that they afford smooth surfaces only 
 when broken in particular directions. This 
 is the case with crystallized bodies in general. 
 The power which they have of thus break- 
 ing is called their cleavage, and the particu- 
 lar directions in which they break, are called 
 their cleavage-jilanes. 
 
 Clerestory. The upper story or row of 
 windows in a Gothic church ; also the win- 
 dows in the lantern of the tower aie so 
 called. 
 
CL 
 
 CO 
 
 Clepsydra, or Water Clock. A con- 
 trivance, of very great antiqviity, to note the 
 lapse of time, and indicate 
 the hour by the flowing of 
 water into or out of a vessel 
 properly graduated. Tlae 
 margin shows a clepsydra of 
 the latter kind, invented by 
 Mr. Partington, and by 
 which equal quantities of 
 water are discharged m equal 
 times. A is a cylindrical 
 vessel to hold the water, and 
 B a cork float on its sur- 
 face, through which is pass- 
 ed the short leg of a narrow 
 syphon C, which is sus- 
 pended by a silk cord over 
 a wheel D, the syphon being 
 nearly balanced by the weight 
 
 E, at the other end of the 
 cord. Near the extremity 
 of the long end of the sy- 
 phon is fastened an index 
 
 F, that points out upon a 
 graduated scale the hour, 
 according to the depression 
 within the tube. It is obvi- 
 ous that as the float by which 
 the syphon is supported, is 
 always submersed to the same depth in the 
 water, the outer leg will always remain in 
 the same relative position to the surface : 
 thus, the same hydrostatic pressure being 
 preserved, the flow of water will be uniform. 
 Tlie water falls into a reservoir G, which 
 forms the base of the instrument, and may 
 be made to fall back into the tube by putting 
 a valve between them, and inclining the 
 instrument. 
 
 Climate. The word has two meanings ; 
 one used in the older books of geography to 
 designate certain belts of the earth, which 
 have a reference to the length of the longest 
 day in each belt, half an hour difference con- 
 stituting different climates in the tropical 
 regions ; one hour difference was allowed 
 between one climate and another in the tem- 
 perate zones, and one month within the polar 
 circles. This application of the term is now 
 quite disused, and it is considered to signify 
 the prevailing constitution of the atmosphere, 
 relative to heat, wind, and moisture, to any 
 region. This depends chiefly upon the lati- 
 tude of the place, its elevation above the 
 level of the sea, and its insular or continental 
 position, in addition to its general situation 
 on the globe. 
 
 Clinometer. An instrument upon the 
 principle of the level, for measuring the dip 
 of mineral strata. 
 
 Clock. An instrument for measuring and 
 indicating time. 
 
 Cloisters. A quadrangular arcade of 
 
 heavy and often rich architecture, surrounded 
 by monastic buildings, and enclosing an open 
 space within, used formerly for the exercise 
 of the monks. 
 
 Clorophane. (See Chlorophane.) 
 
 Close . The conflnes of a cathedral, usually 
 enclosed by a wall. 
 
 Cloud. An accumulation of the vapors in 
 the atmosphere, so far condensed as to be 
 visible. Clouds have various names, accor- 
 ding to the different degrees of their fleeciness 
 and apparent solidity; being called cirrhus, 
 if light and fleecy ; cumulus, if in rounded 
 or conical heaps ; and stratus, if in one con- 
 tinued sheet. A detached and moving rain 
 cloud is called nimbus. 
 
 Cloves. A spice, which consists of the 
 buds and young flowers of the caryophyllus 
 aromaticus. 
 
 Clustered Column, rather Clustered 
 Pillar. A pier, consisting of several pillars 
 united. 
 
 Clyssus. a word formerly used to denote 
 the vapor produced by the detonation of nitre 
 with any inflammable substance. •• 
 
 Clutch, or Gland. A piece of wood or 
 metal with two legs, to disengage and re- 
 engage machinery. It is represented as 
 follows : — When the part A is drawn back, 
 the part B is freed ; when A is thrust for- 
 ward so that its two arms are inserted into 
 two holes, on the face of B, then one turns 
 the other, and they both revolve together. 
 
 Coal. A carbonaceous substance, lying in 
 strata at various depths beneath the surface 
 of the earth, and extensively used for fuel, 
 and the making of gas. In a practical point 
 of view, coals may be divided into three kinds. 
 First, anthracite, or stone coal, of which 
 class is the Welsh and Kilkenny coal. It is 
 chiefly used in smelting furnaces, lime -kilns, 
 &c. Secondly, open burning coal, kindles 
 quickly, makes a hot pleasant fire, but is 
 soon consumed, and produces smoke and 
 flame in abundance. It does not cake to 
 gether, but bums to a white ash ; of this 
 kind are most of the inland counties' coals, 
 the Scotch coals, cannel coal, &c. Thirdly, 
 close burning coal, kindles quickly, makes 
 a very hot fire, melts and cakes together," is 
 more durable than the former kind, and burns 
 to a brown ash ; of this kind are most of the 
 sea-borne coals, particularly those from the 
 north, around Newcastle, &c. These kinds 
 of coal often run into each other. 
 
CO 
 
 CO 
 
 Coal Gas. The carburetted hydrogen gas, 
 which arises from the distillation of coal. 
 (See Gas Works.) 
 
 Coating, or Lorication. The operation 
 of covering retorts, and similar vessels, with 
 a clayey substance, to enable them the better 
 to bear an intense heat. A coating substance, 
 recommended by Dr. Ure, is a soft mixture 
 of marly earth and fresh horse-dung, kneaded 
 together. 
 
 Cobalt. A metal, which is of a reddish 
 grey color, brittle, and difficultly fusible. It 
 combines with oxygen in two proportions, 
 the dark blue protoxide and the black per- 
 oxyde ; the former of these varies much in 
 color. Cobalt also unites with chlorine, iodine, 
 bromine, fluorine, sulphur, phosjjhorus, and 
 cyanogen. Cobalt is not used in a metallic 
 state, but as an oxyde, under the name of 
 gaffre, smalt, and azure blue. Its employ- 
 ment is either to color glass and porcelain, 
 which it does of a fine blue color, or as a 
 pigment for the painter. 
 
 CoBALTic Acid. An acid only inferred to 
 exist, because ammonia combines with the 
 oxyde of cobalt, forming as some suppose a 
 cobaltate of ammonia. 
 
 CoBWALL. A wall built of unburnt clay, 
 sometimes mixed with straw ; common in the 
 south and west of the kingdom, as walls for 
 inclosures, cottages, &c. 
 
 CocciNELLiN. The name given by Dr. 
 John to the red coloring matter of cochineal. 
 
 Cochineal. A fine scarlet color, produced 
 from a small insect of the beetle kind, com- 
 mon in Mexico, which lives upon the cactus 
 opuntia, or Indian fig cactus, enveloping 
 itself during a great part of its existence in a 
 fine cottony down or web. Its coloring prin-- 
 ciple is extracted by grinding the insect, and 
 steeping it in water, in which it is very solu- 
 ble. Alumina rapidly combines with it, ren- 
 dering the water colorless, and itself be- 
 coming of a fine lake, crimson, or violet, 
 according to the temperature of the solution 
 acted upon. The salts of tin also rapidly 
 act upon the color, forming, according to the 
 salt used, a violet or fine carmine color. 
 Cocluneal is used for dyeing scarlet and 
 crimson colors, and by the painter, under the 
 name of carmine, as the finest of all red colors. 
 
 Cochlear. The same as Archimedes 
 screw ; a water engine. 
 
 Cock. An instrument for permitting or 
 arresting the flow of a liquid at pleasure. It 
 is an article too well known to need descrip- 
 tion. 
 
 Cockle. The body or fire-place of an air 
 stove is sometimes so called. 
 
 Cockling. Anything becoming entangled. 
 
 CocooN. The bag of silk made by the silk- 
 worm. A good cocoon weighs without the 
 worm about 4 grains, and usually contains a 
 fibre of silk from 3 to 400 yards m length. | 
 
 CoDEiA. An alkaloid, discovered by Re- 
 biquet, in 1832, in the muriate of morphia. 
 
 CoDDRiNGTON Lens. A Small sphere of 
 glass, with its equatorial parts ground away, 
 that it may thus at the same time magnify, 
 and yet be corrected for spherical aberration. 
 
 Co-efficient. In algebra, are numbers 
 or letters prefixed to other letters or unknown 
 quantities, into which they are supposed to 
 be multiplied ; thus in the quantities ah, cx^, 
 2d, &c., the a, c, and 2, are the co-efficients 
 to the quantities b, a^, and d. 
 
 Coffer. A deep panel in a ceiling. 
 
 Coffer Dam. A term applied by engi- 
 neers to denote the inclosures formed for 
 laying the foundation of piers and other works 
 in v/ater, to exclude the surrounding fluid, 
 and thus forming a protection both to the 
 work and the workmen. Coffer dams are 
 usually made of two circles of piles driven in 
 at some distance from each other, and clay 
 rammed between them; the water being after- 
 wards pumped out of the circle leaves an 
 empty space for the pier to be built in. 
 
 Coffer Works. In masonry, are rubble 
 walls faced with free-stone. 
 
 CoG. The tooth of a wheel. 
 
 CoG, Hunting. In a cogged wheel if the 
 number of teeth were exactly a multiple of 
 the number of pallets which work in it, each 
 pallet would, in every revolution, strike the 
 same tooth or cog, and an uneveness of wear 
 be likely to ensue ; to prevent this the cogged 
 wheel is made with One cog more than the 
 multiple ; this extra cog is called the hunting 
 cog. 
 
 CoG Wheel. Any wheel furnished with 
 cogs or teeth around its circumference — dis- 
 tinguished from a toothed wheel by the cogs 
 being of a different material. 
 
 Coil, Electro-magnetic Machine. A 
 machine which derives its chief properties 
 from the electric fluid being made to pass 
 along a coil of wire. Full descriptions of 
 several machines of this kind will be found 
 under Bachhoffner, Clarke, Bird, Stur- 
 geon, 8fc. 
 
 Coil, Callan's. (See Callan.) 
 
 Cohesion. {See Attraction.) 
 
 Cohobate. To re-distil a liquid ; that is, 
 to collect the products of distillation and 
 pour it back again into the still, that it may 
 
CO 
 
 CO 
 
 j-ise a second time of a stronger quality. 
 Creosote and numerous oils are stronger by 
 a re-distillation from the original matter in 
 the still. 
 
 Coke. Pitcoal burnt to a charcoal, that is 
 burnt without contact with the air, so as to 
 have its gaseous and volatile particles burnt 
 or driven from it. 
 
 CoLCOTHAR OF YiTRioL,Jeweller'sRouge 
 or Plate Powder, is the brown red peroxyde 
 of iron ; it may be made by adding solution 
 of soda to the solution of sulphate of iron 
 or copperas, washing, drying, and calcining 
 the powder with a gentle heat in shallow 
 'ressels, till it assumes a deep brown red 
 color. 
 
 Cold. The privation of heat. 
 
 Collar of a Steam Cylinder, Pump, 
 &c., is a plate of metal screwed down upon 
 the stuffing box, with a hole to allow the pis- 
 on to pass tlirough it. 
 
 CoLLiMATioN, LiNE OF. On a telescope 
 is a line passing through the intersection of 
 those wires that are fixed in the focus, and 
 the centre of the object glass. 
 
 CoLLiTioN. The meeting and mutual strik- 
 ing of two or. more bodies, one of which at 
 least is in motion. 
 
 CoLocYNTiN. The peculiar principle of 
 coloquintida. 
 
 Colonnade. A range of open columns, 
 detached from a wall, and supporting an en- 
 tablature. When in the front of a building, 
 it is called a portico ; when entirely sur- 
 rounding a building it is a peristyle : and 
 when double or treble it is a polystyle. Co- 
 lonnades also often support ten-aces, galle- 
 ries, &c. The colonnade in Regent Street 
 is one of the most extensive and beautiful of 
 modem times, but is far surpassed by the 
 Greeks in mimerous of their edifices, and by 
 the Romans, especially in the splendid re- 
 mains of Palmyra. 
 
 Colophony. Black rosin ; the residuum 
 of the distillation of turpentine. 
 
 CoLOPHONic Acid. An acid existing in 
 colophony. 
 
 Colossus. Applied to any figure twice or 
 more than twice as large as life ; also to any 
 building, or part of ditto, of immense size. 
 
 Color, 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 color. 
 The light of the sun, which seems perfectly 
 homogenous and white, is capable of being 
 separated into seven tints or colors, called 
 red, orange, yellow, green, blue, purple and 
 violet, as is proved by holding a prism before 
 the sun's light, when these colors will be 
 manifested on a white paper, held so that the 
 ray of light is reflected on it, or as we wit- 
 ness naturally in the rainbow. These colors 
 aro t»uly but three in number, red, yellow, 
 
 and blue or violet ; the green, orange and 
 purple being but a combination of the other 
 three, as may be proved by mixing them 
 artificially ; red and yellow forming orange, 
 yellow and blue forming green. The colors 
 of natural objects, of trees, flowers, minerals, 
 and factitious products, do not always accord 
 with the colors of light ; inasmuch as there 
 are numerous reds, blues, and yellows, thus 
 the orange, green, and purple colors vary in 
 like degree ; besides which, if a substance 
 be so constituted as to absorb all the rays of 
 light, it will appear black ; if it absorb none 
 of the rays, it will constitute white ; if it 
 absorb all the rays but one, it will appear of 
 that one color : thus by the aid of the various 
 reds, blues and yellows, together with black 
 and white, we are enabled to produce, arti- 
 ficially, all tints whatever. Erown is pro- 
 duced by a combination of red, black and 
 yellow ; chocolate, or claret color, red and 
 black ; olive, green and black ; maroon, 
 purple and black ; salmon color, pink, peach 
 color, flesh color, &c., red and white ; cream 
 color and primrose, yellow and white ; sage 
 green, green and white ; and so on for other 
 colors. For other properties of colors, (see 
 Accidental, Adjective, Substantive, 8fc.) 
 
 Coloring Matter. That which produces 
 the color of material substances, as indigo 
 is the coloring matter of the indigo plant. 
 Sap green, the coloring matter of the buck- 
 thorn berry. Dyes are all coloring matters. 
 
 Columbates. Combinations of the co- 
 lumbic acid, with various bases. 
 
 Columbic Acid. A combination of the 
 metal columbium with oxygen. 
 
 Columbin. A peculiar principle in co- 
 lumbo root. 
 
 Columbium. A peculiar metal extracted 
 from a rare mineral brought from Connecti- 
 cut. It is also called tantalium, from the 
 mineral tantalite, found in Sweden. It has 
 hitherto no application in the arts. It com- 
 bines with oxygen in two proportions ; in one 
 forming an oxyde, in the other an acid, 
 called the columbic acid. 
 
 Column. A round tapering pillar, com- 
 posed of a base, (except in the Greek Doric,) 
 a shaft, and a capital, over which is an 
 abacus. The word column is, in its true 
 meaning, confined to designate the pillars of 
 classical buildings only, or such as are made 
 of certain exact pre-arranged proportions, 
 and attended by only certain ornaments. All 
 other supports for buildings varying from 
 these standards are properly pillars, or, if 
 square and unornamented, piers. Each of 
 the Grecian and Roman orders required 
 columns of different altitudes and dimensions, 
 from the low stature of those of the massive 
 Doric to the lofty and slender Corinthian. 
 The followmg cut will show the appearance 
 and relative dimensions of the five orders ; 
 
CO 
 
 CO 
 
 S^^reater details of them will be found under 
 the names of those orders. 
 
 Column, Electric. (See De Luc.) 
 
 Combination. The intimate union of the 
 particles of different substances by chemical 
 attraction, so as to form a compound possessed 
 of new and peculiar properties. 
 
 Combinations. In mathematics, denote 
 the different collections that may be made 
 out of a certain number of articles, taking a 
 certain number at a time, without regard to 
 the order in which they are to be arranged. 
 
 CoLURES. In astronomy and geography, 
 are two great circles, supposed to intersect 
 each other at right angles in the poles of the 
 world, and to pass through the solstitial and 
 equinoctial parts of the ecliptic ; that which 
 passes through the former point being called 
 the solstitial colure, and the other the equi- 
 noctial colure. 
 
 Combustible. Any substance capable of 
 being consumed by fire, giving out, during 
 its destruction, both light and heat. 
 
 Combustion. The act of burning, and 
 which results from a sudden chemical change 
 in the combustible body, most of its solid 
 particles becoming changed into gaseous, 
 whereby its aggregation is destroyed, and 
 new combinations are formed ; thus dry wood, 
 when burnt, no longer exists as wood, still 
 not a particle of it is destroyed during its 
 combustion. Oxygen, hydrogen, and car- 
 bonic acid gas fly off, the latter floats in the 
 atmosphere, or may be absorbed by a proper 
 apparatus : part of the oxygen exists in the 
 carbonic acid gas, the rest unites with the 
 hydrogen and fornls water, while scoria or 
 ashes remain unconsumed. All these being 
 collected and weighed, will exactly agree with 
 the original weight of the wood, so that 
 nothing is lost, but the particles of bodies 
 are merely compelled to form new com- 
 binations. 
 
 Combustion, Supporters of. Such sub- 
 stances as will support combustion; these 
 
 are various of the gaseous elements, parti- 
 cularly oxygen. 
 
 Comets. Those heavenly bodies which 
 revolve around the sun in long, elliptic or- 
 bits, appearing at uncertain times, and which, 
 during the time of their appearance, have a 
 motion in some respects similar to that of 
 the planets. The courses of comets, how- 
 ever, are not confined to any particular an- 
 gle, relative to the sun's poles, as the planets 
 are ; nor yet are they all rotative in the same 
 direction, some being direct, others retro- 
 grade. Comets, according to the circum- 
 stances in which they are seen, are called 
 bearded or tailed. They are also divided 
 into the following parts : — The nucleus, or 
 thick part of the comet, which is thought to 
 be of the same nature as the planets. The 
 head, or light, which surrounds this nucleus. 
 The coma, which is a still fainter light around 
 the head; and the tail, or stream of light, 
 which follows the comet. The following cut 
 shows a comet in different parts of its eccen- 
 tric orbit : — 
 
 Commensurable. Among geometricians, 
 an appellation given to such quantities as are 
 measured by one and the same common mea- 
 sure, such as 8 and 12, both of which may 
 be divided by 4. 
 
 Commissure. The joint between two 
 stones in masonry. 
 
 Common Electricity, is that free kind 
 of electricity, which is produced by friction, 
 as contra-distinguished from galvanic, mag- 
 netic, and thermo-electricity. 
 
 Common Measure, or Divisor, is that 
 number which will divide two other numbers, 
 without leaving a remainder ; 2,3,4, and 6, 
 are all common measures of 12 and 18 ; and 
 6 is the greatest common measure of those 
 numbers, because no other larger than it will 
 divide them both equably. 
 
 Common Pitch. A roof is so called when 
 the rafters are about three-quarters the width 
 of the building. 
 
 Commutation. In astronomy, the angle 
 of commutation is the distance between the 
 sun's true place, seen from the earth, and 
 the place of a planet, reduced to the ecliptic, 
 or in common language it may be called the 
 apparent difference .of longitude between the 
 sun and a planet. 
 
 Compartition. The division of theground 
 plan of a building into its various compart- 
 ments. 
 
CO 
 
 CO 
 
 Compartment. One portion of an ex- 
 tended subject, or edifice. For example, one 
 arch is a compartment of an arcade ; the 
 choir is one compartment of a cathedral. 
 The term is particularly applicable when 
 chosen as a sample of the rest of the edifice. 
 
 Compass, TTie Mariner's. A magnetic 
 instrument, used at sea to ascertain the 
 bearing of places, the course of the ship, the 
 position of objects, &c. It consists of a 
 brass box, bearing on a central pin or pivot 
 within, a magnetic needle, which either turns 
 round upon the surface of a graduated card, 
 (see below ;) or else it is so fastened to the 
 card that they both turn together. In the 
 first case, the degrees upon the card, which 
 are beneath the needle, indicate its quantity 
 and direction of motion : in the other case, 
 in which the card and needle are attached to 
 each other, a hand or stud upon the box is 
 applied to the same purpose, by showing how 
 much of the card has passed under it. 
 
 Compass, Points of the, are the thirty- 
 two principal divisions on the card of a mag- 
 netic compass ; each of which has a parti- 
 cular denomination, either that of the cardi- 
 nal points, east, west, north, and south, or 
 composed of various combinations of them, 
 as follows : — 
 
 Each of these points contains 11° 15 , and 
 is again divided into quarter points. The 
 points of the compass are also called rhumbs. 
 
 Compass Dials. Small pocket sun dials, 
 fitted to a box carrying a magnetic needle ; 
 in order to place them in the meridian at the 
 time of observation. 
 
 Compass, Variation of. The magnetic 
 pole to which magnetized needles turn does 
 not coincide with the pole of the earth's axis, 
 therefore the mariner's compass does not 
 point north and south, relative to the earth's 
 motion and position ; as it is the object of 
 the mariner, however, to ascertain this very 
 accurately, he is obliged to make a due al- 
 lowance for this variation of the compass, and 
 which in high latitudes is very considerable. 
 
 Compasses. A mathematical instrument, 
 for describing circles, measuring and divid- 
 ing lines, &c. There are numerous kinds of 
 compasses, of which the principal are the beam 
 compasses and calipers, already described. 
 The German compasses A, which have their 
 legs a little bent outwards near the top, so 
 that when shut the points only meet. Hair 
 compasses are so constructed withinside, by a 
 smaU adjusting screw to one of the legs, as 
 to take an extent even to a hair's breadth. 
 Spring compasses, such as are expanded by 
 a spring, and closed by a screw B . Tnangular 
 compasses are made with three legs, to mea- 
 sure triangles, C. Bow compasses are of a 
 small size, and shut up in a bow or hoop. 
 Proportional compasses are those in which 
 the joint lies, not at the end of the legs, but 
 is moveable up and down, so that it may be 
 set at any distance from either end, and con- 
 sequently a distance measured by the points 
 at one end, is diminished or enlarged in a 
 proportion^ degree at the other, D. 
 
 Compasses, Elliptic. (See Trammel.) 
 
 Compass Headed. An arch with a cir- 
 cular head, whether it be of a semi-circular, 
 segmental, or horse-shoe-like form. 
 
 Compass Window. Synonymous with 
 bow window. 
 
 Compass Roof. Synonymous with span 
 roof ; that is, a roof which extends from one 
 wall to the opposite, and the rafters of which 
 meet in the centre between them. 
 
 Compensation Balance, {^et Arnold.) 
 
 Compensation Bars. Bars made of two 
 or more metals, of such a nature that the 
 expansion of one metal shall counteract the 
 expansion of another. Such bars are used in 
 the balances of chronometers, in pendulums, 
 &c., in order to produce perfect equality ot 
 motion, notwithstanding changes of tempe- 
 rature. 
 
 Complement. Aportion requisite to make 
 up a certain quantity ; for example, the com- 
 plement of an angle is the number of degrees 
 which must be added to it to make up 90°. 
 The complement of a logarithm is what it 
 wants to make it up to 10*000000 ; thus the 
 complement of 8-250139 is 1-749861. Com- 
 plement, in Eistronomy, denotes the distance 
 of a star from the zenith, and is the same as 
 the CO -latitude, or the complement of the 
 latitude of it. The complements of a pa- 
 rallelogram are the two smaller parallelo- 
 grams made by drawing two right lines 
 
CO 
 
 CO 
 
 
 through a point in the diagonal, and parallel 
 to the sides of the parallelogram. These 
 complements are always equal to each other. 
 In the following cut, A and B are the com- 
 plements of the parallelogram D C E F. 
 
 Composite. An order of architecture, 
 composed of the Ionic and Corinthian, the 
 capital uniting the leaves of the one with the 
 heavier volute and sculptured mouldings of 
 the other. This order was intended to be 
 more delicate than the Corinthian, but the 
 corona being very heavy, the modillions 
 square, and the entablature generally over- 
 loaded with ornament, it becomes even more 
 massive. The base and shaft of the column 
 scarcely differ from the Corinthian, except in 
 the shaft being half a module longer ; the 
 tapital shows the chief differences between 
 them. The volute is larger, and usually rests 
 upon the second row of leaves, and the leaf 
 which tops it grows also upon its side, while 
 a second small leaf leans on the angle of it. 
 The flower in the centre of the acabus con- 
 sists of two rows of leaves ; the smaller vo- 
 lute of the Corinthian are changed into leafy 
 tendrils, bearing a flower, immediately above 
 which is a sculptured egg, and tongue mould- 
 ing. The chief buildings of this order are 
 the baths of Diocletian, the arch of Titus, 
 the temple of Bacchus, and the arch of Sep- 
 tiniius, all at Rome. 
 
 time, the types as he takes them from the 
 cases. It may be adjusted to any width, by 
 means of a moveable arm and a screw, which 
 retains this arm in any position in which it 
 may be placed. 
 
 Compositor. A workman in a printing 
 ofl&ce who arranges the types in proper order, 
 ready for the pressman ; that is, for him who 
 takes the impression of them on paper. 
 
 Composite Arch. The pointed or lancet 
 arch. 
 
 Composite Number, is that which is pro- 
 duced by the multiplication of two other 
 numbers. For example, 24 and 36 are com- 
 posite numbers ; the first being produced by 
 the multiplication of 4 and 6, the other oi 
 3 and 12. 
 
 Composition. The disposition or arrange- 
 ment of the various parts of a design, so as 
 to produce an harmonious whole. 
 
 Composition of Forces, is the finding 
 the quantity and direction of a single force, 
 which is equivalent to two or more forces, 
 acting each differently, and of which the 
 quantity and direction are given. 
 
 Composition or Forces, Ma hine to ex- 
 plain. The following machine will prove how 
 two forces conspire to produce one motion, 
 and that intermediate between them. 
 
 Composing Stick. An iron or brai ; 
 frame, held in the left hand of the compo 
 tutor, in order to deposit and retain, for a 
 
 At bottom is a square frame or table ; at 
 one comer rises a slender rod, and on each 
 side of it an upright wire, bearing a ball, 
 which by a hole is made to slip easily up and 
 down. In the centre beneath is a third ball, 
 resting loosely on the table. If the ball A 
 falls, it would strike the ball C, and drive it 
 to D ; if B falls, it would drive it to E, but 
 if both A and B are suffered to fall at exactly 
 the same time, the ball C would obey the 
 impulse of both at once, and take an in'"er- 
 mediate course ; that is, be propelled across 
 the board to E. 
 
 Compound Addition, Subtraction, 
 Multiplication, and Division. Those 
 
CO 
 
 CO 
 
 rules of aritlimetic when applied to com- 
 pound quantities, or quantities of different 
 denominations. 
 
 Compound Arch, or Recessed Arch. 
 One arch receding within another. 
 
 Compound Microscopes, are such as 
 have two sets of glasses. Single microscopes 
 consist of a single glass or lens, or of two 
 lenses, acting as a single one. 
 
 Compound Motion, is that which arises 
 from the effect of several conspiring forces. 
 
 Compound Pier. Synonymous with clus- 
 tered. 
 
 Compound Quantities, in algebra, are 
 such as are linked together by the signs + 
 or — ; Qsa + b, c — dyxy + ab, are compound 
 quantities. These are distinguished into bi- 
 nomials, trinomials, Sec, according to the 
 number of the quantities which compose them. 
 
 Compressibility. That quality of a body 
 by which it jdelds to the pressure of another 
 body or force, so as to be brought into a 
 narrower compass. 
 
 Computation. Calculation or reckoning. 
 
 Concamerate. To arch over. 
 
 Concatenate. To link together. 
 
 Concave. A hollow curved surface, like 
 the inside of a cup. 
 
 Concave Lens. A lens which has one 
 side flat, the other slightly hollowed out, A. 
 A double concave lens has both sides hollowed, 
 B. A concavo-convex lens is concave on 
 one side, and convex on the other, C, the 
 centre part being thinner than towards the 
 edges. Objects viewed through concave 
 glasses appear more distant^ or diminished 
 
 3 
 
 Concavity. The cavity within hollow 
 bodies. 
 
 Concentric Having a common centre ; 
 such as concentric circles, ellipses, &c. 
 
 Concentric 
 
 Wh<>eL) 
 
 Engine. (See Sieam 
 
 Concha. The concave ribless surface of 
 a vault. 
 
 Conchoid. The name of a particular 
 mathematical curve, which may be made as^ 
 follows : — 
 
 A P and B C, being two lines intersecting 
 at right angles ; from P, draw a number of 
 other lines P.F D E, &c., on which take 
 always DE = DF = AG: so shall the curved 
 line drawn through all the points E E E be 
 the first conchoid, or the conchoid of Nicho- 
 medes ; and the curve that may be drawn 
 through aU the other points F F F is called 
 the second conchoid. 
 
 Concrete. A mixture of lime and sand 
 or small pebbles, which when mixed to- 
 gether, concrete or harden into a solid rocky 
 mass. It is used for the foundation of build- 
 ings, paved roads, &c. 
 
 Concretion. The growing together, or 
 hardening of any thing. 
 
 Concrete Numbers, are such as are used 
 to designate any particular thing, as 3 pounds, 
 &c., in opposition to absolute numbers, 
 (which see.) 
 
 Concrete Oils. Such as are in the usual 
 state of the atmosphere of a congealed, tal- 
 low-like consistence, such as the oils of the 
 palm, the cocoa nut, &c. 
 
 Condensation. The art by which a body 
 is rendered more dense or heavy ; it is ato 
 plied chiefly to the changing of vapour inp- 
 a liquid, as in distillation and similar arts. 
 
 Condenser. The name of any vessel in 
 which a vapour is condensed by cold into a 
 liquid. Those vessels in which a hot liquid 
 is changed to one that is cold is called a 
 refrigerator. The worm belonging to a still 
 is both, as the vapour of the spirit distilled 
 is first changed by cold into a liquid, and this, 
 hot at first, becomes in its descent through 
 the worm gradually cooled. 
 
 Condenser of the Steam Engine, is 
 a vessel attached to the steam cyhnder, and 
 between it and the air-pump. The position 
 and action of the condenser, as well as ot 
 the neighbouring parts, will be understood 
 by the following cut, which is a part of 
 Watt's steam engine. 
 
 AAA A is a section of the cistern, con- 
 taining cold water. B the eduction pipe from 
 the steam cylinder. C the condenser, whiclft 
 
CO 
 
 CO 
 
 rommunicates by the clack valve D, situated 
 in a pipe at bottom, with the air-pump E, 
 (this is of the common saction kind, but the 
 piston i& furnished with two valves.) The 
 
 valve G opens into the hot well H, and the 
 opening at H is the end of a pipe, that allows 
 the surplus hot water to run off; the re- 
 mainder being pumped into the boiler. The 
 pipe I leads to the cold water cistern at top, 
 and by an injection cock and a rose into the 
 condenser, near the bottom. Before the en- 
 gine is set a-going, the injection cock is shut, 
 and steam is admitted to the cylinder, which 
 passing down through the pipe B into the 
 condenser fills it ; there being no cold water 
 yet admitted, it finds no other escape than 
 through the valve M, which is covered with 
 a little water ; the air previously in C passes 
 out at the same time. The injection cock is 
 then opened, and the steam being condensed, 
 the piston begins to move. The piston rod 
 and air pump rod rise and fall together, being 
 attached to the same end of the beam. When 
 the piston rises, the valves in the piston of 
 the air pump will be shut, and all the air and 
 water above it, lifted into the well H at the 
 same time, owing to the vacuum formed 
 beneath at E. The valve D will open, and 
 let out from the condenser all the air and 
 water contained in it. The downward action 
 of the piston rod will close the valves G and H, 
 and open those in the air pump piston which 
 was to admit the water above them, ready to 
 be discharged at the next stroke of the en- 
 gine, which the injection pipe again opening 
 produces a second condensation. The con- 
 denser and air pump of an engine should be 
 each about one-eighth the capacity of the 
 steam cylinder. 
 
 Condenser Pump. Another name for the 
 air pump which is attached to the condenser 
 of the steam engine, as described under con- 
 denser, and shown at letter E. 
 
 Condenser Guage. A tube of glass, 
 32 inches long, open at both ends ; the up- 
 per end being fixed to the condenser, the 
 lower end dipping into mercury. It is to 
 
 ascertain the degree of exhaustion within the 
 condenser. If there were a perfect vacuum 
 within the condenser, the atmosphere would 
 press the mercury up the tube to a height of 
 from 28 to 32 inches. This degree of va- 
 cuity, however, is never attained in practice. 
 Condenser, Volta's Electrical, is re- 
 presented as follows ; and is attached, as is 
 usual with it, to a gold-leaf electrometer. It 
 consists of two brass plates, one connected 
 with the cap of the electrometer ; the other 
 supported on a glass pillar. The use of the 
 instrument is to render apparent such por- 
 tions of electricity, as are too weak to be in- 
 dicated by the electrometer only. 
 
 Condensing Syringe. An instranent 
 of the nature of a squirt , furnished with ^ 
 handle, moving a solid piston B air- 
 tightly in a cylindrical barrel, which 
 barrel is furnished with a valve at 
 the foot, opening outwards A ; and 
 either a small hole near the top 
 of the barrel C ; or else the piston, 
 instead of being solid, is perforated, 
 and has a valve also opening down- 
 wards. It will be evident, that 
 working the handle up and down 
 will alternately fill the barrel with 
 air from the upper part, and con- 
 dense it into any vessel attached to 
 the screw at the foot. By reserving 
 the valves it forms an exhausting 
 syringe. ^^~^ 
 
 Condensing Syringe, is also an instru- 
 ment for procuring an instantaneous light, 
 by means of the condensation 
 of air, A is a solid piston, 
 with a small piece of tinder at 
 the end of it. B is a strong 
 barrel or tube, with a hole into 
 which the piston fits, but with- 
 out amy hole at one end, and 
 no part of the instrument is 
 furnished with a valve. Upon 
 forcing down the piston quickly, 
 the air within the tube is rapidly condensed, 
 and the condensation occasions so great an 
 evolution of heat as to light the tinder. 
 
 Conductor for Lighxnino. (See 
 Lightning.) 
 
CO 
 
 CO 
 
 Conductors or Caloric, are bodies, 
 which when heated at one part, communicate 
 the effects to another part. This is the case 
 with most natural bodies, but some have that 
 power in a greater degree than others ; thus 
 metals conduct caloric rapidly ; wood but 
 slowly ; and glass still more slowly. 
 
 Conductors of Electricity. Such sub- 
 stances as conduct the electric fluid along 
 their surface. The principal of these, ar- 
 ranged according to their degree of con- 
 ducting power, are as follows : — The metals, 
 charcoal, black lead, acids, ores, animal 
 fluids, water, snow, living vegetables, and 
 animals, flame, smoke, steam, salts, rarefied 
 air, vapor of alcohol and ether, earths and 
 stones, in their natural state. Almost all 
 other bodies are non-conductors, or electrics. 
 
 Conductor, Prime. That part of an 
 electrical machine, which collects and retains 
 the electric fluid, as it passes from the cy- 
 linder, or plate of glass. The following cut 
 shows the prime conductor of the common 
 cylinder machine : it is supposed to be placed 
 with one end of it towards the glass. This 
 end is furnished with several points to collect 
 the fluid, while the opposite end is terminated 
 by a ball, upon which various apparatus may 
 be attached. It is necessary that all prime 
 conductors should be supported upon a glass 
 pillar. 
 
 ^^^ 
 
 Conge. Synonymous with apophyge. 
 
 Congelation. The transition of a body 
 from a liquid to a solid state, in consequence 
 of an abstraction of heat, as water congeals 
 into ice. 
 
 Cone. A solid body, having a circidar base, 
 and its other extremity terminated in a single 
 point, or vertex. Cones are either right or 
 oblique ; a right cone is that in which the 
 apex is exactly over the centre of the base, 
 as A. All other cones are called oblique, 
 asB. ^ 
 
 Cones may be either right, acute, or ob- 
 tuse-angled, according to the magnitude of 
 the angle of the vertex. 
 
 Cone of Rays. In optics, the rays of 
 light which are thrown off from a luminous 
 point, and intercepted by a lens, or mirror ; 
 also, those which proceed from a lens, or mir- 
 ror, to its focus, and from that focus beyond. 
 
 Cone, Double. A simple mechanical ex- 
 periment, to show that although it is a natu- 
 ral law that the centre of gravity of a body 
 always tends to, and endeavours to obtain 
 the lowest station, yet there may be cases in 
 which it appears to roll upwards. 
 
 The double cone rests upon the two sides 
 of a sloping railway ; if the cone be placed 
 at the narrow end of this, it will roll towards 
 the other, and as the other is the higher end, 
 the cone appears to roll upwards ; though 
 upon observing the height of the apex at 
 each end, at the beginning and end of its 
 course, it will be seen that in reality it rolls 
 downwards ; the centre of gravity being 
 situated in the axis. 
 
 Congeries. A collection or heap of seve- 
 ral bodies, collected into one mass or aggre- 
 gate. 
 
 CoNGRUiTY. , In geometry, the same as 
 identity or perfect agreement of lines, sur- 
 faces, &c. with each other, in direction, size, 
 &c. 
 
 Conical. Any thing formed like a cone. 
 
 Conical Pendulum. (See Governor.) 
 
 Conical Wheels. (See Bevel Wheels.) 
 
 Conical Valve. A valve, as represented 
 in the margin, of a conical form, lifting up 
 and down when in action ; fit- 
 ting when down into a socket of 
 the same shape, and kept in its 
 position, by means of a pin 
 which passes through it. One 
 or other end of the pin is often 
 made to pass through a hole 
 made in a cross stay ; at other 
 times a weight attached below 
 serves to keep it perpendicular. 
 In the cut both these contri- 
 vances are shown. 
 
 Cones, or Conic Sections. That part 
 of mathematics which treats of the proper- 
 ties, proportions, and measurements of the 
 cone ; and also those figures and solids which 
 are produced by cutting the cone in various 
 directions. In cutting a cone, there are truly 
 five sections: viz., a triangle, circle, ellipse, 
 parabola, and hyperbola, yet only the three 
 latter are peculiar to the cone ; and, there- 
 
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 fore, these alone are usually denominated 
 conic sections. The triangle is seen when- 
 ever a plane passes through the apex and any 
 part of the base, «s at A. The circle is a 
 transverse section, cut parallel to the base, as 
 B. The ellipse is a transverse section cut 
 through both sides obliquely with the base 
 as C. If the plane pass across from one 
 side to the base, and parallel to the other side, 
 it will ht Q. parabola, as D ; but if the plane 
 cutting the side and base, be perpendicular 
 to the base, the part cut off is a hyperbola, 
 as E. 
 
 Conjunction. In astronomy , is the meet- 
 ing of two or more stars in the same sign of 
 the zodiac. Conjunction may be considered 
 true or apparent. When the two bodies meet 
 in the same point of both longitude and la- 
 titude, the conjunction is true. When they 
 agree in longitude, but differ in latitude, the 
 conjunction is only apparent. Grand con- 
 junctions are when two or more planets are 
 seen together. 
 
 Connecting Rod. The rod which joins 
 the beam of a steam engine to the crank ot 
 the fly wheel, or generally any rod or bar 
 of iron which unites one part of machinery 
 to another. 
 
 Conoid. A solid figure, generated by the 
 revolution of any conic section about its axis, 
 and hence it receives particular denominations, 
 according to the section from which it is pro- 
 duced, as elliptical conoid, parabolic conoid, 
 &c. 
 
 CoNSECTARY. The same as corollary. 
 
 CoNSEauENT. The latter of two terras of 
 a ratio, or that to which the antecedent is re- 
 ferred and compared ; thus, in the ratio a : b, 
 b is the consequent, and a the antecedent. 
 
 CoNSEdUENTiA. In astrouomy, the real 
 or apparent motion of a planet, or comet, 
 when it is moving from west to east, or ac- 
 cording to the order of the signs ; and is thus 
 opposed to antecedentia, wliich denotes a 
 contrary motion. 
 
 Consistent Bodies. An old philosophi- 
 cal term for solid. 
 
 Console. An ornament, cut upon the 
 keystone of an arch, which projects, and 
 sometimes is made to support a figure, vase, 
 or other object ; also a bracket for the sup- 
 port of a canopy, balcony, &c. (See Corbel 
 and Truss.) 
 
 Conspiring Forces. Various forces com- 
 bined into one, and therefore all acting^ to 
 produce the same effect. 
 
 Constant Galvanic Battery. (See 
 Daniell.) 
 
 Constellation. An assemblage of stars, 
 expressed and represented under the name 
 and figure of some animal, or other emblem. 
 
 Construction of Equations, &c. The 
 finding the roots of equations by means of 
 geometry ; so also in algebra, a geometrical 
 construction of any given triangle will show, 
 by mechanical measurement alone, the di- 
 mensions of those parts which are not known 
 otherwise than by mathematical calculation. 
 
 Contact. The relative state of two things 
 that touch, but do not enter into each other ; 
 for example, the contact of two globes, or 
 circles, is in a single point. 
 
 Content. A term commonly used to de 
 note the surface or solidity of bodies, so that 
 to find the content of a body is to find its 
 capacity, or its measurement of surface. 
 
 Contiguous Angle. (See Angle.) 
 
 Continual Proportionals. Numbers, 
 or quantities, that increase, or decrease, by 
 an equal ratio as 1,2, 4, 8, 16, 32, are con- 
 tinual proportionals. 
 
 Continued Proportion, is that in which 
 the consequent of the first ratio is the same 
 as the antecedent of the second ; thus 
 2 : 6 :: 6 : 18 is a continued proportion. 
 
 Continuity. An uninterrupted connec- 
 tion. 
 
 Continuity. Law of, is that by which 
 variable quantities, passing from one magni- 
 tude to another, pass through all the inter- 
 mediate magnitudes without passing over any 
 of thena abruptly. Thus the distances of 
 bodies can never be changed without their 
 passing through all the intermediate dis- 
 tances ; so also no body becomes more or 
 less dense without passing through all the 
 internnediate degrees of density, &c. 
 
 Contour. The outline, or general peri- 
 phery of any figure. 
 
 Contractile Forces. Forces which 
 diminish. 
 
 Contraction. The diminishing the size 
 of a body, either by pressure, by cold, or by 
 chemical action. 
 
 Contra-Harmonical Proportion, is, 
 when of three terms, the difference of the 
 first and second is to the difference of the 
 second and third, as the thu'd is to the 
 first. 
 
CO 
 
 CO 
 
 CoNTRAMURE. In fortification, an exter- 
 nal wall built about the walls of a city. 
 
 Constant Quantities. In algebra, 
 those whose values are known, or which re- 
 main constantly the same. 
 
 Contrary Flexure, Point of. The 
 point in which two curves meet, that have 
 the convexity of the one, and the concavity 
 of the other, on the same side of the line, as 
 is seen in the cima, or ogee. 
 
 CoNTRATE Wheel. (See Crown Wheel.) 
 
 Convergent. The tendency of different 
 things, coming from different directions, to 
 unite in a single point. It is also sometimes 
 used to denote the approximate value of a 
 thing, or quantity. 
 
 Converse. In mathematics, the same as 
 reverse. 
 
 Convex. Round, curved, or projecting 
 outwards, as the outside of a globular body. 
 
 Convex and Concave Screw. (See 
 Screw.) 
 
 Convex Lens, or Mirror. That which 
 is bowed or curved outwards ; if one side 
 only of a lens be convex, and the other flat, 
 it is called a plano-convex lens ; if both be 
 curved outwards, it is a double-convex lens. 
 
 P 
 
 Lenses of this kind converge the rays of light 
 and heat, and therefore magnify the object 
 seen through them. They are called also 
 burning glasses and magnifying glasses. 
 
 Convexity. The exterior or convex sur- 
 face of any thing. 
 
 Cooler. A large shallow vessel, in which 
 worts are rapidly cooled in the brewery. 
 Were these not used, the wort would most 
 probably enter at once into the acetous, in- 
 stead of the vinous fermentation, and be- 
 coming vinegar rather than beer. 
 
 Cooper's Lamp Furnace. A lamp 
 which is made of an elongated form, and is 
 furnished with two rows of broad wicks, the 
 whole or part of which may be lighted at 
 once. Professor Faraday recommends this 
 simple furnace as valuable for the heating of 
 tubes, or any long and narrow vessel. Near 
 the ends are two twisted wires, for the sup- 
 port of the tube to be heated. 
 
 Cooper's Mercurial Tube. A small 
 instrument to supply the place of a mercurial 
 trough. It consists of a bent tube, closed 
 at top, open at the foot, siipported in any 
 manner which may be convenient, and filled 
 previous to use with mercury. The open end 
 is then connected with a retort, or alembic, 
 which is giving off the gas to be collected. 
 The gas rises up through the mercury, and 
 occupies the upper arm of the tube, while 
 the mercury which is displaced drops into a 
 dish put underneath to catch it. 
 
 Co-ordinates. In the theory of curves 
 signify any absciss, and its corresponding 
 ordinate. 
 
 Copal. A resin, the produce of three or 
 four different trees. It occurs in irregular 
 lumps, of various forms and sizes. It is 
 without taste or smell, from a transparent 
 white to a brown color : it is scarcely soluble 
 in alcohol alone, unless by long-continued 
 heat : it is soluble in ether ; in alcohol when 
 mixed with camphor ; still more so in alco- 
 hol mixed with caoutchoucine, and by par- 
 ticular management in naphtha and the oil 
 of turpentine. 
 
 Copal Varnish. This hard, clear, and 
 imperishable varnish, which is used so much 
 for the bodies of carriages, cabinet work, &c. 
 may be made as follows : — Take hard copal 
 300 parts, drying linseed, or nut oil, from 
 125 to 250 parts, spirits of turpentine 500. 
 These three substEinces are to be put in three 
 separate vessels. The copal is to be fused, 
 the drying oil heated nearly to boiling, and 
 added by a small portion at a time to the 
 copal. When this combination is made, and 
 the heat a little abated, the essence of tur- 
 pentine, likewise previously heated, is to be 
 introduced by degrees. When cooled down 
 to about the 130th degree of Fahr., t may be 
 strained through a filter. This varnish im- 
 proves by keeping. 
 
 CopERNiCAN System of Planetary 
 Motion, is that system in which the sun is 
 supposed at rest, and the earth and other 
 planets to revolve about him as a centre, 
 while the moon, and other satellites, revolve 
 about their respective primaries in like 
 manner. 
 
 The heavens and stars are here supposed 
 at rest, and that diurnal motion that they 
 appear to have from east to west is imputed 
 
CO 
 
 CO 
 
 to the earth's rotation on its axis from west 
 to east. This system, which we now know 
 *to be the true one of the universe, was known 
 to many of the ancients, particularly Pytha- 
 goras, and therefore is sometimes called the 
 Pythagorean, after his name ; yet as it was 
 more fully explained and completed by Co- 
 pernicus — the appellation of Copernican is 
 now more frequently employed. 
 
 Coping, or Capping. The covering course 
 of a wall, or buttress, mostly projecting 
 beyond the general surface to throw off the 
 wet. 
 
 Copivi, Oil and Balsam of. The re- 
 Linous exudation from several species of the 
 copaifera is commonly called the balsam of 
 copivi, or copaiva. If this be distilled, a 
 fragrant volatile oil passes over, very much 
 resembling the oil of lemon, though of less 
 agreeable fragrance. 
 
 Copper. A metal of a reddish brown co- 
 lor, hard, very malleable, sonorous, of con- 
 siderable tenacity, and capable of a high 
 polish, though soon tarnishing afterwards. 
 There are two oxydes ; the black or deutoxyde, 
 and the orange or protoxyde. Copper unites 
 with chlorine in two proportions ; with io- 
 dine, phosphorus, sulphur, &c. Its solutions 
 in the acids produce often very fine colored 
 pigments. Copper in all its combinations is 
 poisonous : it is used, not only in its me- 
 tallic uncombined State, for numberless ves- 
 sels ; but is a component of many alloys, such 
 as bell metal, brass, &c. 
 
 Copperas. Sulphate of iron : It is chiefly 
 used as one of the ingredients of ink and 
 black dyes. 
 
 Conia, or CoNiciNB. The active prin- 
 ciple peculiar to hemlock. 
 
 CoppBR-PLATE. Artists understand by this 
 term a sheet of copper, flattened, smoothed, 
 and polished, ready for the engraver. The 
 
 preparation of copper-plates is very simple ; 
 the sheet of copper is first cleaned and 
 examined for imperfections, if none appear 
 it is fit for the purpose. It is then beaten or 
 rolled, afterwards cut into proper sizes; 
 ground on the surface, first with emery of 
 different degrees of fineness, then with a hone 
 stone or snake stone, and finally with char- 
 coal and oil ; when thus polished the edges 
 are planed, and the plate is fit for use. 
 
 CoppER-PLATB Engraving. (See £w- 
 graving.) 
 
 CoppER-PLATE Printing. The printing 
 from engraved plates, whether of copper, 
 steel, pewter, or other metal, indicating a 
 style of printing which is equsdly applicable 
 to any metallic plate, though copper being 
 the commonest gives its name to the entire 
 art. The process is as follows : — The plate 
 is first warmed by putting it on an iron 
 plate, heated by steam, or by a charcoal fire. 
 The ink is pressed into the lines of it, by a 
 wad, made of woollen cloth, rolled up like a 
 ball, with a handle. The superfluity of ink 
 resting on the general surface of the plate is 
 then wiped off, first with a rag, then with the 
 workman's hand, slightly rubbed with whiting. 
 The paper being previously damped, a piece 
 is placed on the plate, and being drawn 
 through the press comes out on the other 
 side printed. 
 
 Copper-plate Press. The press used 
 by the copper-plate printer. (See Rolling 
 Press.) 
 
 CopyiNG Press. A machine for speedily 
 producing a fac-simile copy of any manu- 
 script already written. The method is to 
 place on the letter a sheet of tliin damp pa- 
 per, 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. The ink used is the same as 
 common ink, but with sugar added to it. 
 The presses are of various shapes ; but the 
 following, which is the invention of the cele- 
 brated James Watt, is that most generally 
 used. 
 
<30 
 
 CO 
 
 Coral. AcsQcareous substance, formed by 
 various species of sea polypus,which construct 
 in concert immense ramified habitations, con- 
 sisting of an assemblage of small cells, each 
 the abode of an animal. The finest is found 
 in the Mediterranean; it is of a fine red 
 color, and used for making necklaces, crosses, 
 and other female ornaments. It is worked 
 up like precious stones. 
 
 Coral, Artificial, for grottos, &c. may 
 be made by painting the peeled twigs of the 
 hawthorn, or other tree, with melted sealing 
 wax, or dipping them in common wax, or 
 common rosin, colored with vermiUion. The 
 painted twigs afterwards to be held near the 
 fire, until a smooth and glossy surface is 
 obtained. 
 
 Corbel. Corbett. A short projecting 
 piece of wood or stone, intended to carry 
 the groins, or trusses of a roof, or other 
 weight above it. It is often elaborately and 
 grotesquely ornamented. 
 
 Corbelling. A term to signify the pro- 
 jection of one stone, or one brick over ano- 
 ther in a wall, in the manner of a corbel. 
 
 Corbel Step, or Corbie Step. When 
 the gable of a house is broken into apparent 
 steps, or ledges. 
 
 Corbel Table. A row of corbels sup- 
 porting an overhanging cornice, parapet,&c. ; 
 very common in the Norman buUdings. 
 
 Cordon. The edge of a stone on the out- 
 side of a building. 
 
 Core. The internal mould which forms a 
 hollow in foundry, as the hollow of a tube or 
 pipe. 
 
 Corinthian. The fourth order of archi- 
 tecture ; the richest and most delicate. Its 
 
 capital is adorned with rows of leaves, and 
 with eight volutes, which support the acabus. 
 The height of the column is 9^ diameters, 
 and its cornice is supported by sculptured 
 modiUions. The Corinthian order is a general 
 favorite, both by the ancients and the mo- 
 derns, Without being overloaded with orna- 
 ment, like the composite, it is graceful and 
 rich, light and impressive. The splendid 
 ruins at Balbec and Palmyra are noble an- 
 tique specimens of this style, while there are 
 numerous buildings in London, such as 
 Goldsmith's Hall, which show its true cha- 
 racter and beauty, 
 
 Corinthian Brass. It ispretended, that 
 at the burning of Corinth, by Mummius, in 
 the year 146 before Christ, the brazen, gold, 
 and silver vessels of the city were melted 
 accidentally together, and as the ancients 
 knew not how to separate them, they used 
 this valuable alloy wherewith to cast statues, 
 bronzes, vases, &c. 
 
 Cork. The bark of the quercus liber, a 
 species of oak which grows abundantly in the 
 southern provinces of France, Italy, and 
 Spain. The bark being stripped from the 
 tree in the spring of the year ; it is soaked 
 in water, then pressed flat by the weight of 
 large stones,next dried, and afterwards some- 
 what charred on the surface by fire. The chief 
 uses of cork are for stoppers of bottles, floats 
 for fishermen's nets, as a buoyant material 
 in life boats, preservers, &c., for the inner 
 soles of shoes, and to line the drawers in 
 which collections of insects are preserved. 
 
 Cornice. The uppermost moulding in 
 any part of a building ; thus we say the cor- 
 nice of a room, of a pediment, of a frieze, 
 pedestal, &c. 
 
 Cornish Reducing Flux. Ten ounces 
 of tartar, 3 ounces and 6 drachms of nitre, 
 and 3 ounces and 1 drachm of borax ; mixed 
 well together. 
 
 Cornish Refining Flux. Deflagrate, 
 and afterwards pulverize, 2 parts of nitre, 
 and 1 part of tartar. 
 
 Corollary. In mathematics, a conse- 
 quent truth, which foUows immediately from 
 some preceding truth, or demonstration. 
 
 Corona. The lower member or drip of a 
 classical cornice. The flat under-part of it 
 is called the soffit. 
 
 Corpuscle. An atom, or one of the mi- 
 nute ultimate particles of whichbodies consist. 
 
 Corpuscular Philosophy. That scheme 
 or system of physics, in which the pheno- 
 
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 mena of bodies are accounted for, from the 
 motion, rest, position, &c., of the atoms that 
 compose them. 
 
 Corridor. An open passage, or gallery. 
 
 Corrosive Sublimate. Bi-chloride of 
 mercury, formerly called the oxy-muriate of 
 mercury. It is a most deadly poison, and as 
 such is used in a weak solution to wash over 
 the plants in herbaria, that they may not be 
 subject to the attacks of insects. It is also 
 destructive to vegetable life, therefore a small 
 portion added to blacking, to ink, &c., pre- 
 serves them from mould and other funguses ; 
 hence its solution is used to soak timber in, 
 to preserve it from the dry rot. It is a most 
 powerful antiseptic, and animal bodies im- 
 mersed in it have remained a great length of 
 time so fresh and uninjured, that no signs of 
 putrescence were discovered in them. 
 
 ConsA. (See Fascia.) 
 
 Corundum. A genus of har.d, aluminous 
 minerals, to which the sapphire, ruby, and 
 adamantine spar belong. 
 
 CoRYDALiA. An alkaloid, foxmd in cory- 
 dalis and fumaria 
 
 Cos, Rule of. The term applied by the 
 Italians to denote the science of algebra, on 
 its first introduction into Europe. 
 
 Co-secant, Co-tangent, Co-versed 
 Sine, are the secant, tangent, and versed 
 sine of the complement of their arc or angle. 
 The prefix co being merely a contraction of 
 the word complement. 
 
 CosMiCAL. An old astronomical word, 
 used to express the rising or setting of the 
 sun, or a star ; but more commonly to denote 
 a star's rising or setting with the sun. 
 
 CosMOLABE. An ancient instrument for 
 measuring distances, both celestial and ter- 
 restrial. 
 
 CosMORAMA. The name of an optical ex- 
 hibition, in which different places are repre- 
 sented as if of their proper size. It is 
 nothing more than an oil painting, seen 
 through a magnifying glass ; a square black- 
 
 ened frame being interposed between the glass 
 and the picture, so that the edges of it shall 
 be hid from the observer. The light may be 
 thrown upon the picture, either from a win- 
 dow above and before it, or by a lamp placed 
 upon the square frame; the effect of sun- 
 set, moonlight, &c., being produced by one 
 or more colored screens placed between the 
 picture and the hght. 
 
 Cove. Any hollow or concave moulding ; 
 a recess ; the concavity of an arch or ceiling. 
 
 Coved Ceiling. When the sides of a 
 ceiling are curved downwards towards the 
 walls, forming part of an arch. 
 
 Co vered Way. A narrow passage between 
 different parts of a castle or fort, for the 
 protection of the garrison. 
 
 Coving. The projection of the upper parts 
 of a building beyond its ground plan, as is 
 seen in very numerous old houses, where one 
 story projects beyond that which is under it. 
 
 Couch. The laying of any adhesive sub- 
 stance on wood, plaster, canvas, &c., to 
 overcome, or destroy its porosity ; thus, in 
 painting, the canvas is first prepared vdth 
 couch of size ; oil-cloth, with a couch 
 whiting, and so on. In many cases this 
 injurious, in others highly beneficial, as ena- 
 bling the substance couched to bear better 
 the injuries of the weather. 
 
 Coulomb's Tortion Electrometer is 
 represented in the margin. A is a glass ves 
 sel, fitted into a stand at 
 the foot, and having a cir- 
 cular poi-tiOn of its circum- 
 ference graduated. Upon 
 A is fixed a long glass tube 
 B ; at the top of which is 
 a circular scale of ivory C, 
 with a small hand movea- 
 ble around the centre. 
 Upon the centre of motion 
 of this hand is suspended 
 a single untwisted fibre of 
 silk, which passes down 
 the tube B, and into the 
 vessel A, where it is ter- 
 minated by a small piece 
 of straw D, across which 
 passes a wire and light 
 ball E, forming a balance. 
 Also through the top of A 
 passes the wire F, which 
 has a ball at each end. When the upper ball 
 F is electrified, it acts upon the ball E, re- 
 pelling this to a certain distance, which dis- 
 tance, and consequently the degree of elec- 
 trization, is indicated by the graduated scale. 
 
 Coulter. A stout iron knife, which is 
 fixed in the front of a plough, and which cuts 
 along the edge of the furrow, before it is 
 turned up by the plough-share. 
 
 Counter Drawing. Tracing a picture 
 by laying a transparent medium upon it and 
 
 IS a 
 
CO 
 
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 marking down the lines beneath, according 
 as they are seen through the medium. 
 
 Counter-Fort. A pier, buttress, or 
 oblique wall, built up against a wall to 
 strengthen and support it. It is used in for- 
 tification, to resist the pressure of a rampart, 
 &c. 
 
 Counter-Guard. An outwork, formed 
 in order to retard the formation of a breach 
 in a fortress. 
 
 Counter-Harmonical. <'See Contra- 
 Harmonical. 
 
 Counter-Light. A window opposite to 
 any thing which makes it appear to a dis- 
 advantage. A single counter-hght is suf- 
 ficient to take away all the beauty of a fine 
 painting. 
 
 Counterpoise. Any weight which placed 
 in opposition to an'other weight produces an 
 equilibrium. The weight used with the steel- 
 yard is usually called the counterpoise. 
 
 Counter-Proof. In engraving, an im- 
 pression taken from a newly-printed proof 
 of a copper-plate, printed for the purpose of 
 a closer investigation of the state of the plate ; 
 as the proof is in every respect the reverse 
 of the plate, while the counter-proof has 
 every thing the same way. 
 
 Counter-Sink. To bore such a hole in 
 a plate of brass, iron, &c., that the head of 
 a screw may be buried in it. 
 
 Countervallation. a chain of redoubts 
 raised about a fortress, to prevent sorties of 
 the garrison. The works being either un- 
 connected, or united by a line of parapets. 
 
 Counter Weighing Machine. By the 
 following cut will be recognized a very com- 
 
 mon and useful instrument, differing from 
 the common balance in having the scales 
 above, instead of below the beam. The beam 
 is composed of two parallel bars, vsdth three 
 cross pieces terminating in suspension pivots ; 
 one in the middle, and one at each end. A 
 table B is placed at one end to receive the 
 weights, and a dish C at the other, to hold 
 whatever matter is to be weighed. The dish 
 rests loosely on a sprandel, or bracket, so 
 that the scale may easily be taken off. Two 
 hollow standards D E, a connecting piece F, 
 and the channelled bottom G, consists of one 
 stout casing uf iron. The vertical motion of 
 
 the table B, and the scale C, is obtained by 
 the contrivance of two rods descending 
 through D and E, which are connected at 
 their lower ends to a second beam, suspended 
 like the first, and concealed in the base of 
 the stand. 
 
 CousiNET. A cushion. A stone on the 
 impost of a pier, destined to receive the first 
 course of an arch ; also that part of the Ionic 
 capital between the abacus and the echinus. 
 
 Court Plaster is made as follows : — 
 Black silk is strained, and washed over seve- 
 ral times with the following mixture. Dis- 
 solve half an ounce of balsam of benzoin in 
 6 ounces of spirits of wine ; and in a sepa- 
 rate vessel dissolve 1 ounce of isinglass, in 
 as little water as possible. Strain each solu- 
 tion, mix them, and let the mixture rest, so 
 that any undissolved parts may subside ; 
 when the clear liquid is cold, it will form a 
 jelly, which must be warmed before it is ap- 
 plied to the silk. When the silk coated with 
 it is quite dry, it is to be finished off with a 
 solution of 4 ounces of Chian turpentine in 
 6 ounces of tincture of benzoin. 
 
 Coward's Air Electrometer, con- 
 sists of a glass cylinder, 3 inches diameter by 
 
 8 inches m length ; on each end of which a 
 brass cap is cemented air-tight. Passing 
 through the upper cap, and near to the edge- 
 is a glass tube B, blown with a funnel-shaped 
 end, for the purpose of exposing a greater 
 surface, and bent so as to leave a short pa- 
 rallel arm of 2\ inches. To the long arm of 
 this tube a narrow graduated scale of ivory is 
 attached. C and D are brass wires and balls 
 passing through the caps ; the upper one 
 sliding in a collar of leather. To use the in- 
 strument, fill the tube B to the height of 
 about 2 inches, with any fluid ; on the sur- 
 face of which, iu the long arm, is to rest a 
 lieht sniage made of quill, part being cut so 
 
CO 
 
 CR 
 
 as to act as a spring, which will hold it at 
 any part of the tube. When a shock is 
 passed from D to C, the air withui A is agi- 
 tated, and pressing upon the fluid drives the 
 guage upwards, where it is retained at the 
 highest point by its spring. 
 
 Cowl. The moveable top of a chimney ; 
 also a wire cap, covering the top of a loco- 
 motive engine, and intended to prevent the 
 escape of lighted flakes, of fuel, &c. It is 
 made of various shapes. 
 
 Crab. A small portable crane, used for 
 raising materials, &c. 
 
 Crackers. Fire -works, which when fired 
 go off with several small explosions. They 
 are made in a long case, formed of three or 
 four thicknesses of paper, rolled round a 
 long wire, and pasted at the outer edge ; then 
 loosely filled with gunpowder, folded up in 
 short alternate doublings, and tied very 
 tightly in the middle, around each doubling. 
 When fired, the various doublings inflame in 
 repeated succession. 
 
 Coupled Columns. Columns arranged 
 in pairs. 
 
 Couples, or Main Couples. The same 
 as trusses for roofs, which support the roof 
 in different lays. 
 
 Couplings. In many cases, particularly 
 where many machines are moved by the same 
 power, it is important to possess the means 
 of stopping any one of them at pleasure, and 
 of restoring its motion without interfering 
 with the rest. To produce this efilect, a 
 great variety of combinations have been in- 
 vented, under the name of couplings. The 
 clutch is an example ; the fast and loose 
 pulley another. (See Pulley.) 
 
 Coupling Box. An angular box, or frame 
 of iron, or wood, which fitting upon a spin- 
 dle enables the motion of the frame to be 
 continued to the spindle, while the removal 
 of the coupling box again restores it to a 
 state of rest. 
 
 Courantine. (See Rocket.) 
 CouRONNE DE Tasses. A galvanic bat- 
 tery so called. It consists of a number of 
 
 glasses, jelly pots, or similar vessels, in each 
 of which are placed two pieces of metals, of 
 dissimilar electric properties ; for example, 
 zinc and copper — the zinc of one vessel being 
 connected with the copper of the other. The 
 outer cups, or vessels, having a wire only to 
 its extreme plate of metal ; the wire there- 
 fore of one extremity being joined to the 
 wire of the other extremity completes the 
 electric circuit, and causes the fluid to cir- 
 culate around the whole series. 
 
 Course. A continued level range of stones 
 or bricks in a wall, as far as the solid part runs. 
 In slating or tiling it is a range of slates or 
 tiles. 
 
 Course. In navigation, the point of the 
 compass, or horizon, which the ship steers on. 
 It is sometimes reckoned in degrees ; some- 
 times in points of the compass. 
 
 Course or Plinths. The same as string 
 course. 
 
 Coursing Joint. The joint between two 
 courses of brick, or stone work. 
 
 Cradle. In engineering, is a large wooden 
 frame, into which a boat or barge may be » 
 floated, in order to be conveyed by pulleys, I 
 &c., from one level of a canal to another, ^ 
 without the aid of the usual locks. 
 
 Cradle Vault. The same as cylindric 
 vault. 
 
 Cradling. A mass of timber work in 
 arched and groined ceilings, in order to sup- 
 port the lath and plaster ; also the rough 
 timbering which supports the entablature of 
 a shop front. By coopers it signifies the 
 cutting a cask in half lengthways, in order 
 to make it pass a narrow passage, and re- 
 storing it afterwards to its original form and 
 degree of tightness. 
 
 Cramp. A metal tie, for securing the se- 
 veral stones of a wall together. A vertical 
 cramp is called a dowel, or plug. Iron is 
 the usual material employed, though copper 
 is far superior. Also synonymous with 
 clamp, (which see.) 
 
 Crampoons. Pieces of iron, hooked at 
 the ends for the drawing or pulling up tim- 
 ber, stones, &c. 
 
 Crane. A machine used in raising or 
 lowering heavy weights. Cranes are gene- 
 rally constructed upon the principle of the 
 wheel and axle, or else upon that of Bramah's 
 press ; of these the former is much the more 
 common. 
 
 The collar B is made to revolve in an iron 
 or stone block, fixed in the ground. The 
 post C is firmly attached to the collar, and 
 carries the jib D E ; it has a double stay, 
 one on each side of the post C, the pulley 
 E working between them. The workman 
 turns the handle F, which moves the toothed 
 wheel G ; this turns a second wheel H, on 
 the axis of which the rope is coiled up, 
 liftinec the weight at the same time. L is a 
 
CR 
 
 OR 
 
 fly wheel with a brake upon it, in order that 
 the workman may have complete control 
 over the crane when lowering any goods. 
 
 Crane, Chinese. A modification of the 
 wheel and axle, which for simplicity of struc- 
 ture and immensity of power is worthy of 
 more attention than it has received. As a 
 portable crane, for the lowering of wine casks 
 into cellars and similar purposes, it is in- 
 valuable 
 
 would work three piston rods at the same 
 time : — 
 
 A B is a windlass, worked by the handle C ; 
 this windlass has two diameters. The cord 
 is woimd round the part A, then passed un- 
 der the moveable pulley E, then carried to 
 the narrower part of the windlass B. In pro- 
 portion to the square of the diameters of the 
 two parts of the windlass, so will be the 
 power of the instrument. 
 
 Crank. A contrivance for changing cir- 
 cular into alternate motion, or vice versa. 
 Cranks are either single or multiplied ; if 
 single, there is but one connecting rod at- 
 tached to the crank, and consequently but 
 one reciprocating motion is produced at each 
 revolution of the crank ; if the crank be 
 double, two motions are produced — one in 
 each connecting rod ; if still more compound, 
 the like multiplication of motion will take 
 place: for example, the following crank 
 
 The motion produced hy cranks is easy 
 and gradual, being most rapid in the middle 
 of the stroke, and gradually retarded towards 
 the extremes, so that shocks and jolts in the 
 moving machinery are diminished, or wholly 
 prevented by their use. 
 
 Crape. A transparent textile fabric, some- 
 what like gauze, made of raw silk, gummed 
 and twisted at the mill. 
 
 Crater. The mouth of a volcano. 
 
 Crayons. Slender, soft, chalk-like pen- 
 cils, used by the artist for sketching upon 
 paper. The hard black crayons, called French 
 crayons, are made of charcoal, cut into slips, 
 and afterwards soaked in hot wax. Other 
 crayons are made of various colored powders, 
 united together by different cements, of which 
 the following is recommended : — 6 parts of 
 shell-lac, 4 parts of spirits of wine, 2 parts 
 of turpentine ; to which quantity of ingre- 
 dients are to be added, 12 parts of the co- 
 loring matter, and 12 parts of blue clay. 
 (See also Creta Leevis.) 
 
 Crayons, Lithographic. Mix together by 
 a gentle heat, white wax 4 parts, hard tallow 
 soap, and shell-lac, each 2 parts, lamp black, 
 1 part. It may be cast into moulds for use. 
 
 Crazing. A term employed by potters to 
 indicate the cracking of the glaze upon por- 
 celain and delft articles. 
 
 Cream of Tartar. Supertartrate of 
 potass ; or now called cream tartrate of potass, 
 from the supposition that it owes its charac- 
 ters to a peculiar acid, called the cream tar- 
 taric acid. 
 
 Creepers. Synonymous with crockets, 
 (which see.) 
 
 Crenellated. An embattled moulding, 
 used in Norman buUdings. 
 
 Crenelles. Loop-holes or open work in 
 parapets, &c., for archers to shoot through. 
 (See Embrasure.) 
 
CR 
 
 CR 
 
 Creosote. A liquid obtained by the dis- 
 tillation of wood tar. It is a corrosive, lim- 
 pid, colorless, strongly-scented liquid ; is a 
 non-conductor of electricity ; refracts light 
 powerfully, and bums in a lamp with a ruddy, 
 smoky flame. Creosote combines with al- 
 cohol, hydric ether, naphtha, potass, soda, 
 ammonia, lime, baryta, and certain oxydes. 
 It prevents the putrefaction of animal sub- 
 stances, and is therefore used in curing pro- 
 visions, though a few drops communicates a 
 strong smoky flavor to many pounds of meat. 
 Its action on the nervous system is so great 
 that it is applied with considerable success to 
 cure the tooth-ache, and to recent burns and 
 scalds. 
 
 Crepusculum. Twilight. 
 Crescent. A representation of the moon 
 in her state of increase. Having been once 
 stamped on the coins of Byzantium, indi- 
 cating that that city was the moon of the 
 Roman empire, as Rome itself was the sun ; 
 the Turks have adopted the crescent as their 
 national emblem, although the appropriate- 
 ness of its first adaptation is no longer 
 considered. 
 
 Crest. The ornamented work which 
 finishes the upper part of a cornice, canopy, 
 parapet, &c. The Vitruvian ornament was 
 common among the Romans ; the Tudor 
 among the buildings of decorated and per- 
 pendicular Gothic styles. Also the highest 
 part of a shrine. Among carvers a crest is 
 a piece of work to adorn the upper part of 
 any thing, as the top of a looking glass 
 frame, &c. 
 
 Crest Tiles. Ornamental tiles, formerly 
 used to cover the ridge and hips of a roof. 
 
 Creta L^vis Pencils. A soft kind of 
 drawing crayons, made of pipe clay, mixed 
 with various Earthy and metallic pigments, 
 and occasionally hardened by a small quan- 
 tity of glue. The mixture is either to be put 
 when soft into pencil sticks, or moulded into 
 shape. These crayons have much brilliancy, 
 and from their soft texture, the tints blend 
 easily into each other. 
 
 Creux. a French word, to which there is 
 no corresponding English term. It implies 
 a hollow in any thing, or a scooping out. 
 
 Crighton's Metallic Thermometer, 
 derives its action from the different expansi- 
 bility of metals by heat. A compound bar 
 is formed by uniting together a bar of zinc, 
 A B, eight inches long, one inch broad, and 
 a quarter of an inch thick, to a plate of iron, 
 E F, of the same size. The lower extremity 
 of the compound bar is firmly fixed to a ma- 
 hogany board at B F. A pin above A E, 
 plays in a forked opening of the short end 
 of the lever or hand C. When the tempe- 
 rature is raised, the superior expansion of the 
 2inc will bend the whole bar, as in the figure, 
 and the index C will move along the gradu- 
 
 ated arc, from right to left, in proportion to 
 the temperature. In order to convert it into 
 a register thermometer, Crighton contrived 
 two slender hands, D D, on the axis of the 
 index ; these lie below the index, and are 
 pushed in opposite directions by a stud on 
 the central part of C. 
 
 Crockets, CRoauETs. Leaves, or bunches 
 of foliage on the angles of a Gothic building, 
 particularly on spires, pinnacles, canopies, 
 and drip-stones. The varieties are numerous. 
 
 Croconic Acid. A substance of peculiar 
 properties, procured by distilling potassium 
 from a mixture of carbonate of potass and 
 charcoal. 
 
 Crocus Head. A flower used in scroll 
 ornaments, to break the length of a con- 
 tinued tendril, and to relieve the stiffness and 
 meagreness of its appearance. Like the flower 
 itself, it has three leaves, and is without a 
 calyx or cup. It is usual also to make it 
 contracted, like a nearly-closed crocus. 
 
CR 
 
 CR 
 
 Cronical. (See Achronical.) 
 
 Cronos. A name anciently given to the 
 planet Saturn. 
 
 Cross. The symbol of the Christian re- 
 ligion ; therefore a common decoration of 
 Christian buildings, particularly as a terminal 
 ornament. Churches and cathedrals are 
 most generally of this form, for example, 
 St, Paul's. If the four arms be equal in 
 length, it is called a Grecian cross ; if one 
 be longer than the others, it is Roman. The 
 monumental buildings erected in different 
 parts of the kingdom by Edward I., in honor 
 of his queen, are called crosses ; so also are 
 numerous market houses, &c., a cross being 
 a constant ornament upon them. The follow- 
 ing are some terminal crosses from English 
 cathedrals : — 
 
 Cross, Surveyor's. An instrument used in 
 surveying, for the purpose of raising per- 
 pendiculars ; it consists of a simple flat piece 
 of wood, with two saw cuts at right angles 
 to each other ; or else of a flat piece of wood, 
 with four sights upon it, the lines joining 
 which are also at right angles to each other : 
 thus— 
 
 It is used as follows : — Let two of the 
 sights agree with the base line of the survey, 
 and carry the cross along this line, until some 
 object, which it is wished to draw the per- 
 pendicular from, be seen through the other 
 two sights ; then marking on the base line 
 the position of the cross, the perpendicular 
 can be noted as arising from that spot. 
 
 Cross Banded. In cabinet work, is when 
 a narrow ribbon of veneer is inserted into 
 the surface of any piece of furniture, wains- 
 coting, &c., so that the grain of it is con- 
 trary to that of the general surface. 
 
 Cross Garnets. Hinges which have a 
 cross piece on one side of the joint, and a 
 long strap on the other. 
 
 Cross- Hatching. A term used by en- 
 gravers, to signify such shades or tints as are 
 produced by crossing the lines. The fol- 
 lowing is an example of cross-hatching in 
 wood : it is the most difl&cult part of the art 
 to learn, because as the black parts require 
 to be left, and the rest to be cut away, there 
 is great danger in cuttmg the lines through 
 each other, and in taking away cleanly the 
 diagonal interstices between them. 
 
 Cross Multiplication. {See Duodeci- 
 mals.) 
 
 Cross Staff, or Fore Staff. An in- 
 strument used formerly by mariners for ta- 
 king the meridian altitude of the sun or stars. 
 
 Cross Springers. The transverse ribs 
 of a groined roof. 
 
 Cross Quarters. (See Quatrefoil.) 
 
 Crossette. a truss or console on the 
 flank or return of an architrave of a door, 
 window, or other aperture. 
 
 Cross Vaulting, is formed by the in- 
 tersection of two or more simple vaults of 
 arch-work. 
 
 Crossing on Railways. The necessary 
 arrangement of rails to form a communica- 
 tion from one line to the other. 
 
 Crossing Point, Fixed Point, or Point 
 Plate. The points where one rail of a rail- 
 way crosses another. 
 
 Crotonic Acid. The active principle of 
 the seeds, or of the oil of croton tiglium. 
 
 Crow-Bar. a strong bar of iron, used 
 as a temporary lever. 
 
 Crown, or Crowning. The upper mem- 
 ber of an arch, a wall, a battlement, &c., is 
 called a crown ; also the corona and superior 
 mouldings in an architrave. 
 
 Crown of an Arch. The top, or high- 
 est part. 
 
 Crown Glass. Best window glass ; its 
 composition is 200 parts of soda, 300 parts 
 of fine sand, 33 parts of lime, and 250 ground 
 fragments of glass. 
 
 Crown Saw. A species of circular saw, 
 formed by cutting the teeth round the edge 
 of a cylinder. The surgical instrument, called 
 the trepaai, is an example. 
 
 Crown Wheel, or Contrate Wheel. 
 
 A wheel, the teeth of which are at right 
 
 I angles to the plane of the wheel, or parallel 
 
CR 
 
 CR 
 
 to the axis of it. It is employed occasionally 
 where an alteration of motion from a perpen- 
 dicular to a vertical position is required. 
 Crown wheels have more friction than bevel 
 wheels, thus they are seldom used, except in 
 small pieces of machinery. There is one in 
 a watch, as may be easily seen. 
 
 Crucible. A small conical vessel, made 
 of some material which, when burnt, is very 
 refractory in the fire, impervious to moisture, 
 and not readily acted upon by corrosive 
 liquids. Crucibles are used by the founder 
 and the chemist for holding ores, metallic 
 substances, earths, &c., which are to be sub- 
 jected to a strong heat. The following is a 
 receipt for forming a proper clay wherewith 
 they may be made : — Half a pound of Stour- 
 bridge clay drie4, quarter of a pound of old 
 crucibles ground fine, one-eighth of coke 
 powdered, and one-eighth of pipe-clay. The 
 black lead crucibles are made of two parts 
 black lead and one of fire-clay, mixed with 
 water, and moulded into form. 
 
 Crude. Raw, unfinished, or unrefined. 
 In painting, crudeness is when the colors are 
 laid on roughly, and are not blended properly 
 and softly together. 
 
 Cruickshank's Galvanic Battery, 
 or Trough, is formed of a series of double 
 metallic plates, formed of two dissimilar me- 
 tals, as copper and zinc, soldered together at 
 top, and cemented into a trough or long box, 
 with any resinous cement ; each pair of plates 
 is separated by a narrow space from the rest. 
 When a trough of this description is filled 
 with a mixture of acid and water, a galvanic 
 action ensues ; and if a wire be connected 
 with the cell at each end, and the wires made 
 to touch each other, the circuit will be com- 
 plete, and the effects become apparent. 
 
 
 Crushing. The breaking of materials into 
 small parts, such as is practised in mines and 
 in various manufactures — either by stamping, 
 pounding, pressing, &c. ; by weights, presses, 
 rollers, or hammers. 
 
 Cryophorus. a simple instrument, in- 
 vented by Dr. Wollaston, for the purpose of 
 
 illustrating the effect of evaporation in pro- 
 ducing cold. It consists of a glass tube, 
 from 18 inches to 2 feet in length, having 
 an internal diameter of one-eighth of an inch. 
 The tube is bent at right angles near the ends, 
 both of which are terminated by bulbs. 
 
 One of the bulbs is nearly filled with wa- 
 ter, which being made to boil, the air is ex- 
 pelled from the tube and bulbs, which remain 
 filled with steam. The o])en bulb is then 
 closed, by melting the glass at its capillary 
 termination. When the empty bulb is im- 
 mersed in a mixture of salt and snow, the 
 vapor existing within it is condensed, which 
 removing pressure from the surface of the 
 water in the other bulb, enables it to evapo- 
 rate rapidly, and the vapor being condens^ 
 as speedily as it is formed, the water W 
 readily frozen. 
 
 Crystal. Any solid body which has as- 
 sumed a regular and determinate angular 
 form. Crystals are either natural or artificial ; 
 the natural crystal is one that is formed 
 without the intervention of human art, and 
 which cannot be thus formed. The artificial 
 crystal is such as may be manufactured, 
 though the particular forms that even these 
 last assume are no less subject to natural 
 laws. Natural crystals are seen in numerous 
 
CR 
 
 cu 
 
 gems, quartz, metals, and minerals. Arti- 
 ficial crystals are exemplified by chemical 
 salts, sugar, &c. The forms that cxystals 
 assume are almost endless, though each, 
 with a few exceptions, remains constant to 
 one appearance. The preceding cut shows 
 various forms of crystals. 
 
 Crystalline Heavens. In old astro- 
 nomy, two orbs imagined between the pri- 
 mum mobile, or firs.t power, and the firma- 
 ment, in the Ptolemaic system, in which 
 the heavens are supposed solid, and only 
 susceptible of a single motion. 
 
 Crystallization. The process of nature, 
 by which the particles of bodies are arranged 
 systematically in passing from a liquid to a 
 solid state, or changing into what are called 
 crystals. Melted sulphur, for example, when 
 cooling, is seen to shoot into needle-shaped 
 crystals, and a mass of it being afterwards 
 broken, is found to consist of a mass of such 
 crystalline bodies. 
 
 Crystallography. The science that 
 treats of the formation, shape, and peculiarities 
 of crystalline bodies. 
 
 Crypt. A vault under a sacred building. 
 
 Ctesibitjs's Pump. A pump much used 
 among the ancients, and still a valuable in- 
 strument. It combines the principle both of 
 the common suction pump and the force 
 pump, as follows : — 
 
 Cube. A regular solid body, consisting of 
 six equal sides or iaces — it is also called an 
 hexaedron. 
 
 Suppose A A are two pipes, leading from 
 a well below, to the vessels B and E. Each of 
 these vessels is furnished with a valve at bottom , 
 a pipe DD, leading to the vessel C, and a 
 solid piston, capable of an alternate motion 
 up and down by a connecting rod at top ; 
 moving so that when one piston is up the 
 opposite one is down. When the piston of 
 E rises, the water from the well passes 
 through the valve at bottom into E, and when 
 it sinks by the return stroke, the valve at 
 bottom is closed, and the water which is now 
 in E is forced along the pipe D into C ; 
 while the same action, but in alternate times ^ 
 is taking place in B, both tending to force 
 water into C, and propelling it up the pipe F. 
 Cubature, is the finding the solid or 
 cubic contents of any proposed body ; the 
 same as quadrature signifies tiie findmg the 
 superficial area. 
 
 Cube Number, is a number produced by 
 multiplying a number into itself twice : thus 
 27 is a cube number, because 3 multiplied 
 by 3, and the product afterwards by 3, 
 makes 27. 
 
 Cube Root. The cube root of any number 
 is such a number as being multiplied twice 
 by itself will produce that number : thus 2 
 is the cube root of 8, because 2 + 2 + 2 = 8. 
 
 Cubic Equation. That equation in al- 
 gebra in which the unknown quantity rises 
 to the third or cubic degree of power ; as, 
 for example, x^ xax^ y.bx=\Q is a cubic 
 equation. 
 
 Cubic Nitre. Nitrate of soda. 
 
 CuBO-cuBE. The sixth power, as 64 is 
 the sixth power, or the cubo-cube of 2. 
 
 CuBO-cuBo-cuBE. The ninth power ; as 
 512 is the ninth power of 2. 
 
 Cudbear. The dyeing material, or color- 
 ing matter of the orchil, or archil lichen, 
 called also litmus and lacmus ; and sometimes, 
 though improperly, turnsole. It is used in 
 dyeing to communicate a bloom to other 
 colors. 
 
 Cuddy. A three-legged stand, forming a 
 fulcrum upon which a long pole is placed, 
 which is used as a lever to lift and lay rail- 
 road blocks. 
 
 CuLLET. In the manufacture of all com- 
 mon glass, a portion of broken glass is always 
 mixed up with the raw materials ; this is 
 technically known under the name of cullet. 
 
 Culm Coal. The same as anthracite 
 
 Culminate. To be vertical, or on the 
 meridian. 
 
 Culminating Point. That point of a 
 circle of a sphere that is on the meridian. 
 
 Culmination. In astronomy, the passage 
 of any heavenly body over the meridian, or 
 its highest altitude during its diumal revo- 
 lution. 
 
 Culpepper's Microscope, or the Py- 
 ramidal Microscope. This instrument, 
 though of an old construction, and inconve- 
 
 T 
 
cu 
 
 cu 
 
 iiient form, is yet one which possesses con- 
 siderable power, and was at one time almost 
 the only one sought after. It is shown in 
 the cut as set out for use ; it stands 12 or 14 
 inches high, and has four or six different 
 powers. 
 
 A is the slide-head, turned concave. B the 
 €ye tube, containing two powerful lenses. 
 C the slide tube, by which the instrument is 
 adjusted. D the body, in which the upper 
 part slides, having in some cases a rack and 
 pinion movement at K. E is a circular brass 
 table, supported upon three legs, which are 
 screwed upon the stand F, In the middle of 
 E is a spring object holder. G the mirror, 
 which reflects the light through the object to 
 the eye. H an illuminator or lens, for re- 
 flecting light upon opaque objects. I is a 
 contrivance, called the frog plate ; and J is 
 the nippers and needle. 
 
 Culvert. An arched drain, for conveying 
 rills and brooks of water under canals or 
 roads, from the higher level on the one side 
 to the lower level on the other ; they are 
 also employed for discharging the rain water 
 out of hollows, 
 
 Cumming's (Dr.) Statical Thermo- 
 meter. An instrument intended as a mode 
 of opening windows and ventilators in apart- 
 ments, by the variations in temperature of 
 the included air. 
 
 A is a tube and ball, either of glass or 
 iron, the ball being capable of holding 4 or 5 
 pints of air, and the tube B, about 25 inches 
 long. A portion of the tube is filled with 
 mercury, and in this state is inverted, and 
 the end plunged in a jar of the same fluid ; 
 
 to the top of the ball is attached a string, 
 which after passing over the puUies D and E» 
 is finally fastened to the window F. When 
 the heat of the apartment rarefies the air in 
 the ball, the mercury is driven out, and the 
 
 ball and tube being thereby lightened, rise 
 and suffer the window to swing itself open. 
 An increase of cold will produce the con- 
 trary effect. 
 
 Cumming's (Dr.) Register Thermo* 
 METER, Barometer, &c., may be under- 
 stood by the following explanation and cut •. — - 
 
 A is a ball and tube, formed, filled, and 
 inverted, as in the last instrument. The cord 
 of it after passing over the pulley, carries a 
 barometer tube, B, which, equally with A, 
 dips into the syphon filled with mercury, 
 D D, in both sides of which the mercury 
 will always remain at the same level. On 
 the wheel or pulley C C, is an index, to 
 which a pencil may be attached, for tracing 
 the variations of the instrument, on a plate, 
 revolving by means of clock-work. 
 
 Cumming's (Dr.) Hygrometer, is 
 merely a tube of bright metal, containing an 
 
cu 
 
 cu 
 
 s^z 
 
 air thermometer and scale, the bulk 
 of the former being surrounded 
 with fine sponge. This is attached 
 to a portable exhausting or con- 
 densing syringe, by which a current 
 of air is produced through the 
 tube. The sponge is damped with 
 ether, or other very evaporable 
 fluid, and the current of air in 
 passing through it, produces evapo- 
 ration in proportion to the strength 
 of the current, which evaporation 
 is rendered conspicuous on the 
 surface of the metallic tube, as 
 well as the degree of cold induced 
 by the thermometer. 
 
 CuMULO-STRATus, 7\vain Cloud. Masses 
 of rounded clouds mixed with those that are 
 fleecy, the former being the lowest in po- 
 sition — mostly accompanied by a westerly 
 wind. 
 
 CUMULO- CIRRO-STRATUS, Or NiMBUS, 
 
 The Rain Cloud. A horizontal sheet of clouds, 
 over which the cirrus clouds spread, and the 
 cumulus enters it from beneath. 
 
 Cumulus. Clouds which are in conical or 
 rounded convex heaps ; as is frequently ob- 
 servable in the west at sun-set, when the 
 rest of the sky is clear, and otherwise, both 
 in fine weather, and at the clearing-up of 
 wet. 
 
 Cup and Bell. A scroll-work ornament 
 of considerable beauty and variety, used oc- 
 casionally to terminate a tendril, but more 
 frequently as a springer for smaller tendrils, 
 as in the following example : — 
 
 Cup Valve. A vaire exactly resembling 
 a conical valve, except that it is made in a 
 semi-circular or cup-shaped form . 
 It is superior when used as a 
 safety valve, because it is not so 
 apt to stick in its socket as the 
 conical safety valve is. This is 
 particularly the case with loco- 
 motive engines, in which the vi- 
 bration of the boiler, by dis- 
 turbing the pendant ball, has the- 
 effect of liberating the valve, 
 should it be inclined to adhere 
 to the valve box, or cavity, in which it is 
 placed. 
 
 Cupel. A shallow earthen vessel, used in 
 that part of the process of assaying, called 
 cupellation. It is made of the residue of 
 
 burnt bones, wetted, and rammed into a 
 mould, which gives it its shape. The furnaces 
 used in smelting iron are also called cupels. 
 
 Cupellation. A process in assaying the 
 precious metals. It is performed as follows : — 
 The metal is put into a cupel, together with 
 a certain proportion of lead, and then ex- 
 posed to a considerable heat in a muffle, or 
 small earthen oven, fixed in the midst of a 
 furnace ; the lead vitrifies, and collects to 
 itself all the alloys and impurities combined 
 vdth the precious metal. The lead thus 
 rendered into a glass, combines with the 
 cupel itself, and leaves the precious metal 
 pure and uncontaminated. 
 
 Cupola. A small dome, terminating one 
 which is larger, or else rising from the roof 
 itself, erected either for ornament, for a bell 
 turret, a ventilator, or to light a staircase, &c., 
 often synonymous with lantern. 
 
 Curb. In a general sense, a check, or re- 
 straint. A curb-stone is the outer edge of 
 a foot pavement, and between it and a road. 
 The curb to brick steps is a piece or pieces 
 of timber running from end to end to pre- 
 vent the wearing of the bricks. The wooden 
 frame around the brick-work on the top of 
 a pit or well, is also a curb. 
 
 Curb Roof. A roof formed of two sets 
 of rafters on each side, arranged in the 
 following form : — 
 
 Curdled Lenses. A name given to those 
 optical glasses which have been so imper- 
 fectly ground as to show minute ridges or 
 cavities to the naked eye. This defect arises 
 from three causes. First, an irregular or 
 ill-formed tool. Secondly, the lens being 
 polished with an improper motion. Thirdly, 
 the covering of the tool with the requisite 
 grinding and polishing powders, which ans 
 emery and washed putty powder, being im- 
 properly laid on. 
 
 Currying. 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. 
 
 Currents, Electrical. The passage of 
 the electric fluid from one pole of an appa- 
 ratus to the other. 
 
 Cursor. Any part of a mathematical in- 
 strument that slides backwards and forwards, 
 for example the moveable leg of a bcani 
 compass : the joint of the proportional com- 
 passes ; the hand of a barometer ; the beam, 
 of the trammel, &c. 
 
cu 
 
 CY 
 
 Curtail Step. The lower step of a flight, 
 finishing at the end in the form of a scroll, 
 following the plan of a hand-rail. 
 
 Curtain. That part of a battlement be- 
 tween any two towers or bastions. 
 
 Curtate. In astronomy, is the distance 
 of a planet's place from the sun or earth, 
 measured to the ecliptic ; or the interval be- 
 tween the sun and earth, and that point 
 where a perpendicular, let fall from the 
 planet, meets with the ecliptic. 
 
 Curtatiox, is the interval between a 
 planet's distance from the sun, and the cur- 
 tate distance. 
 
 Curvature of a Line, is its bending or 
 flexure, by which it becomes a curve of any 
 particular form or properties. 
 
 Curve, In geometry, is a line, the several 
 parts of which proceed in different directions, 
 and are successively directed towards different 
 points in space. A plane curve is that of 
 which the several points in it lie in the same 
 plane, and when this is not the case, the 
 curve is said to be one of double curvature. 
 The principal curves are the catenary, cis- 
 soid, cycloid, cardioide, caustic, epicycloid, 
 &c., (which see.) 
 
 Curves, Magnetic. The particular ar- 
 rangement of particles of iron when acted 
 npon by a magnet ; they emanate from one 
 pole, and are attracted towards the other, as 
 may be seen in the following cut :-- 
 
 Curvilinear. Any thing relating to 
 curves, as curvilinear angle, figure, surface, 
 &c., being such as are formed or bounded 
 by curves. 
 
 Curvilinead. Any instrument adapted 
 to form a curve, as that described under 
 Arcograph,&.c. The following is an ingenious 
 contrivance of this kind, having the peculi- 
 
 arity that it can form a hollow, an irregular, 
 and a mixed curve, as well as one which is ' 
 regularly convex. : 
 
 A A is a light flexible bar of steel or brass. * 
 B B, &c., are a series of wires at regular 
 short distances, fastened to the bottom of A A, 
 and moveable up and down in the wooden 
 bar C C. Pulling these down, or pushing 
 them up, will of course, bend A A into the 
 required shape. It may be retained in this , 
 shape by the aid of the keys D D. 
 
 Cushion. In electricity, that part of an 
 electrical machine which presses against the 
 glass cylinder or plate. According to the 
 size of the machine, it may be from one to 
 two inches wide, and should be stuffed with 
 a conducting substance, or if not, the amal- 
 gam upon the flap of it, should be connected 
 with the chain that reaches to the ground. 
 In the front of the cushion is fixed a loose 
 piece of leather, bearing a black siUc flap 
 upon the top of it. 
 
 Cushion Capital. A capital so sculp- 
 tured as to appear like a cushion pressed upon, 
 as is very common in Indian buildings, and 
 of which there is a cut under Abacus and 
 Capital. The name has also been given to 
 the common Norman capital, consisting of a 
 cube rounded off at its lower extremities, as 
 is seen imder Arcade and Arch. 
 
 Cusp, or Feathering. Small projecting 
 arcs, with which the heads of Gothic windows 
 are ornamented. 
 
 Cusp. In astronomy, signifies the horns 
 of the moon, or other heavenly body. In 
 geometry, it is the point where two curves 
 meet each other. 
 
 Cuthbertson. (See Balance Electro- 
 meter.) 
 
 Cutting. A name applied to excavations. 
 
 Cut-water. The lower portion of a pier, 
 separating two arches of a bridge crossing a 
 river. It is usually of hard stone, and pointed 
 towards each end, that it may the better re- 
 sist the action of the stream, and the blows 
 of floating ice. 
 
 Cyanic Acid. A union of cyanogen and 
 oxygen. 
 
 Cyanides, or Cyanurets. Combinations 
 of cyanogen, with various bases. 
 
 Cyanogen. The base of prussic acid ; 
 called also prussine, and from its composition, 
 the bicarburet of nitrogen, consisting of 2 
 atoms of carbon to 1 of nitrogen. It may 
 be obtained from the pure crystals of the 
 
CY 
 
 CY 
 
 cyanuret of mercury, by distilling this salt, 
 and collecting the gas which is evolved over 
 mercury : under a pressure of 3 or 4 atmos- 
 pheres it condenses into a limpid colorless 
 liquid. The gas is colorless, with a strong 
 smell of bitter almonds ; it burns with a pe- 
 culiar purple flame, and its specific gravity is 
 1*82. By peculiar management, it unites 
 with oxygen, chlorine, hydrogen, iodine, sul- 
 phur, phosphorus, and bromine, and many 
 of the metals, constituting with the last class 
 of substances what have been called equally, 
 cyanides, cyanurets, and nitro- carburets. 
 These unite with each other, and form double 
 cyanurets. 
 
 Cyanometer. An instrument contrived 
 by Mr. Sausseur, to measure the intensity of 
 the color of the sky, and thereby to deduce 
 the quantity of vapour floating in the atmos- 
 phere, it being known that the color is weak- 
 ened in proportion to the abundance of 
 aqueous particles in the air. The cyanometer 
 is a circular band of thick paper or paste- 
 board, divided into 51 parts, each of which 
 is painted of a different shade of blue, de- 
 creasing gradually from the deepest to the 
 weakest. The colored zone is held in the 
 hand of the observer, who notices the par- 
 ticular tint which corresponds to the color of 
 the sky. The number of this tint, reckoning 
 from the darkest, is the intensity. 
 
 Cycle. A certain period or circle of num- 
 bers, proceeding orderly from first to last ; 
 then returning again to the first, and so cir- 
 culating perpetually. Cycles were invented 
 in order that we may calculate time in spaces 
 convenient for daily use, and yet make due 
 allowance at the same time for the irregula- 
 rities of the motions of the heavenly bodies, as 
 will be seen from the following examples : — 
 
 Cycle of the Sun, or Solar Circle. 
 A revolution of 28 years, in which time the 
 days of the month return again to the same 
 days of the week — the sun's place to the 
 same signs and degrees of the ecliptic on the 
 same month and days — and the leap years 
 begin the same course over again, with re- 
 spect to the days of the week on which they 
 fall. 
 
 Cycle of the Moon, commonly called 
 the golden number, is a revolution of 19 years, 
 in which time the conjunctions, oppositions, 
 and other aspects of the moon, are within an 
 hour and a half of being the same as they 
 were on the same days of the month 19 years 
 before. 
 
 Cyclograph. Synonymous with arco- 
 graph, (which see.) 
 
 Cycloid, or Trochoid. A mechanical 
 curve of somewhat curious properties : it 
 may be understood and formed as follows : — 
 
 Conceive the circle C to revolve or roll 
 along the straight line A B, until a fixed 
 point in the circumference at D, which at first 
 
 touched the right line at A, touches it again 
 at B, after an entire evolution of C. Then 
 the curve A E B, traced by the point D upon 
 the plane, will be the cycloid ; if instead of 
 the line A B being a straight line, it were the 
 part of a circle, the curve described would 
 
 c?rT]^ 
 
 have been an epicycloid. The cycloid is the 
 curve of swiftest descent ; if we suffer a ball 
 to roll down the concave side of a cycloid, 
 it will reach the bottom in less time than by 
 running in any other curve. 
 
 Cyanuric Acid. A peculiar acid in urea 
 Cyclopian Walls. (See Masonry,) 
 Cylinder. A solid having two equal cir- 
 cular ends, parallel to each other ; and every 
 plane section parallel to the ends, is also a 
 circle, and equal to them. Cylinders are 
 either right, that is erect, or oblique and 
 sloping. 
 
 Cylinder Electrical Machine. An 
 electrical machine, the moving part of which 
 is a cylinder of glass. The arrangement 
 of the various parts is as follows : — 
 
 A is the cylinder, fixed into two brass or 
 wooden caps, one at each end. B is the silk 
 flap belonging to the cushion, and which 
 passes over the cylinder until it approaches 
 the points of the prime conductor C. D is 
 a handle, whereby the cylinder is turned. 
 E is a screw to regulate the pressure of the 
 cushion upon the cylinder. F is a chain 
 reaching to the groimd, to collect and supply 
 the fluid to the cushion. 
 
 Cylinder, Steam. That part of a steam 
 engine in which the piston moves, and in 
 
CY 
 
 CY 
 
 which the motion of the whole is produced, 
 by the alternate admission and condensation 
 of the steam from the boiler. The length of 
 the cylinder should be about twice its di- 
 ameter, though occasionally cylinders have 
 varied much from this proportion. Steam 
 cylinders have mostly an erect position: that 
 belonging to Maudsley's steam engine vi- 
 brates to and fro. In some engines the 
 cylinder is placed horizontally, or else at a 
 certain angle with the horizon. 
 
 A is a barrel ground smoothly inside, 
 within which is a piston, moveable up and 
 down. C is a square box, called a valve box, 
 divided by a partition, containing the slide 
 valve D, and connected with two pipes, one 
 the pipe to admit steam E, and the other the 
 eduction pipe F, which lets off the steam into 
 the condenser. (See Slide Valve.) 
 
 Cylindric. Any thing in form of a cy- 
 linder. 
 
 Cylindrical Mirrors. All objects seen 
 by reflection in a cylindrical mirror are ne- 
 cessarily distorted, and that either in width 
 or length, according as the mirror is pre- 
 sented to them. Cylindrical mirrors, which 
 are now very uncommon, used to be made 
 for this purpose, and were accompanied with 
 a series of distorted figures, which, when 
 
 seen by the eye, have neither shape nor 
 meaning, but when laid down before a cylin- 
 drical mirror, the reflected image of them 
 has the most perfect proportions. The effect 
 is shown below, where the lower object is the 
 distorted figure, whose image in the mirror 
 has the appearance of a regular portrait. 
 
 Cylindrical Vaulting. A vault, con- 
 sisting of a plain half cylinder ; called also 
 barrel, wagon, tunnel, or cradle roof. The 
 Thames Tunnel and arches of London Bridge 
 are examples. 
 
 Cyltndroid. a solid, resembling a cy- 
 linder, except that it has elliptical ends, in- 
 stead of circular ones. 
 
 Cymatium. a small moulding, termi- 
 nating several members of a building, as the 
 upper moulding of a Roman Doric abacus. 
 The moulding around the top of a modillion ; 
 also between a tympanum and its cornice, 
 or on the upper part of the architrave. The 
 upper mouldings of a pedestal, when it is 
 without a regular cornice, are also so called. 
 (For figure see Corona.) 
 
 Cytisin. a peculiar principle supposed to 
 exist in the laburnum. 
 
 The fourth letter of 
 our alphabet, of the or- 
 der of mutes. The an- 
 cient Coptic Dau was 
 represented by a cha- 
 racter like a modern D 
 turned sideways Q . — 
 Whence the Greeks de- 
 rived their delta A, and from this last the 
 Romans their D. In Greek it signifies 4; among 
 the Roman numerals 600, though the Ro- 
 mans themselves did not use it with this sig- 
 nification, it not being considered indicative 
 of 500 till the sixteenth century after Christ. 
 In inscriptions, mottos, titles, &c., D im- 
 plies doctor, dominus, dat, donat, dedicat, 
 defensor, &c., besides being occasionally 
 
 used for B and L, as des for les. On French 
 coins it indicates Lyons. In music D desig- 
 nates a particular note, supposed to be re- 
 presented by the monosyllable re. 
 
 D Valve. A sliding valve, common in 
 steam engine work, the use and structure of 
 which are as follows: — D in 
 the cut represents a square 
 box, supposed to be full of 
 steam,which is supplied by the 
 pipe B. Passing through this, 
 and capable of moving up and 
 down is the rod G ; to which 
 is fastened the valve itself A, 
 which is merely a solid piece 
 of metal of the shape repre- 
 sented. C is a cavity or tube 
 
DA 
 
 DA 
 
 connected with the top of a steam cylinder. 
 E a similar pipe, passing to the condenser ; 
 and F a thii'd pipe leading to the bottom of 
 the cylinder. Each of these pipes opens into 
 D. When the valve is in the position re- 
 presented, there is a communication within- 
 side the valve, between the top of the cylin- 
 der and the condenser. The steam, there- 
 fore, in that part is escaping, while a supply 
 is rushing by the bottom hole into F, that is, 
 under the piston. Rushing down the valve 
 to the bottom of the case will reverse these 
 communications, letting off the steam from F 
 and giving a fresh supply to C. 
 
 Daguerreotype. A process invented by 
 M. Daguerre, a Frenchman, by which, de- 
 lineations of views, portraits, &c., are taken 
 with the greatest conceivable accuracy, with- 
 out the aid of artistical genius in drawing, 
 by means of reflection from the images them- 
 selves, when illmninated by a strong solar 
 light. The process may be understood as 
 follows : — A sheet of copper, plated with 
 sUver, is made extremely bright and clean. 
 It is then exposed in a well-closed box to 
 the vapour of iodme ; when become of a 
 slightly-yellow color, the plate is withdrawn 
 and placed in a box camera obscura, and 
 preserved from the action of light tUl the 
 box is offered to the proper object or land- 
 scape to be represented. When this is the 
 case light is admitted, and the objects become 
 delineated on the silver plate, though very 
 faintly : to bring them out with greater 
 strength, the plate is next submitted to be 
 acted upon by the vapour of mercury in 
 another box. The plate being put in the box 
 at an angle of 45^, and after some time it 
 being taken out, must be washed with the 
 hypo-sulphite of soda, and finally with warm 
 water, when the picture will be clear, and 
 not alterable by the further action of the light. 
 
 Dais. An elevated part of a floor, or a 
 platform in a hall, or banqueting room. 
 
 Dahline. (See Datiscine.) 
 
 DAlembert's Principle, in Mechanics 
 is tliis. If several non-elastic bodies have a 
 tendency to motion, and in directions which 
 they are constrained to change, in consequence 
 of their reciprocal action on each other, then 
 these motions may be considered as com- 
 posed of two others ; one which the bodies 
 actually take, and the other such, that had 
 the bodies been acted upon by it alone, they 
 would have remained in equilibrium. 
 
 Dam. a small dock or reservoir, in which 
 the water of mill streams is accumulated ; 
 also an embankment of stone or timber raised 
 for the purpose of turning the direction of 
 a stream of water, so that it may be thrown 
 iipon a particular object. 
 
 Damaskeening. The art of ornamenting 
 iron, steel, &c., by making incisions upon its 
 surface; and filling them up with gold or silver 
 
 wire ; chiefly used in enriching sword blades, 
 locks of pistols, &c 
 
 Damascus Steel. A particular fine kind 
 of «teel of a streaky mottled appearance, 
 used for the manufacture of the best sword 
 and scymitar blades, of which a great trade 
 was once carried on at Damascus. 
 
 Damper. A flap, or sliding piece of iron, 
 which being raised, depressed, or more or 
 less drawn out, increases or diminishes the 
 draught of air in the flue of a furnace. 
 
 Damps. The permanently elastic fluids 
 which are extricated in mines, and are de- 
 structive to animal life ; are called damps by 
 the miners. The principal are choak damp, 
 or carbonic acid gas, and fire damp, or car- 
 buretted hydrogen. 
 
 Dan. a small truck used in mines, for 
 the conveyance of coals to the pit's mouth. 
 
 Dancing Images. An electrical experi- 
 ment, to show the effects of electrical attrac- 
 tion. The apparatus necessary, is a pair of 
 plates of metal, or wood covered with metal. 
 The upper one, which is rather the smaller, 
 is attached by a wire to the prime conductor 
 of the machine; the other plate is placed 
 upon a stand connected with the ground, so 
 as to be three or four inches distant from 
 the former : when figures of pith or paper 
 are placed on the lower board, and the upper 
 charged by turning the machine ; the figures 
 will dance up and down between the two 
 plates. 
 
 Dancing Pith Balls. An experiment 
 illustrating electrical attraction. It is per- 
 
DA 
 
 DA 
 
 formed thus : — Fasten to the prime conductor 
 of the machine a pointed wire. Turn the 
 handle, and hold a tumbler, previously 
 warmed, over the wire. When charged with 
 the fluid, which it will be in two or three 
 minutes, turn it down over some small balls 
 made of the pith of the elder tree, lying 
 upon the table. These will immediately fly 
 up and down till the glass is discharged. 
 
 Dactyliogkaphy. a description of en- 
 graved finger rings and precious stones. 
 
 Dactyliology. The science which de- 
 scribes or treats upon the history, nature, 
 and qualities of engraved gems for finger rings. 
 
 Daniell's Constant Galvanic Bat- 
 tery. A galvanic battery, which may be con- 
 sidered, as compared to previous inventions, 
 constant, its action lasting unimpaired for a 
 great length of time. It consists of a cop- 
 per vessel A, holding about a pint of liquid. 
 In and through the centre of the bottom of 
 this is a cork E, (fig. 2,) with a syphon tube 
 attached. On the top end of the cork is tied 
 a long narrow bladder D, the upper end of 
 ■which is also tied around a cork, piece of 
 wood, or something similar C, which rests 
 upon the edge of the copper vessel ; within - 
 side the whole is a rod of zinc B, attached to 
 which is a wire G, the outer copper vessel 
 having soldered upon it a similiar wire. At 
 a short distance down the copper vessel is a 
 ring-shaped shelf F. Fig. 1 is the external 
 appearance of the battery, the wire from the 
 copper being marked C. To use the instru- 
 ment, fill the space between the outer vessel 
 and membrane D, with a saturated solution 
 of sulphate of copper, and put some crystals 
 of the same salt on the shelf F, and suffer 
 water, acidulated with sulphuric acid, to 
 trickle slowly into the inner vessel, around 
 the zinc ; any thing placed between the wires 
 will be subjected to a galvanic action. When 
 the inner vessel is too full, or becomes loaded 
 with the oxyde of zinc, the liquid will pass ofi" 
 through the syphon tube. 
 
 Daniell's Hygrometer. An instrument 
 for ascertaining the dew point and other me- 
 teorogical phenomena. The lower ball is of 
 black glass, about an inch and a quarter in 
 
 diameter, and is connected by a bent tube 
 with the other ball, which is of the same 
 size, but of white glass, and covered with a 
 piece of linen. Withinside the longer arm 
 of the tube is fixed a delicate thermometer, 
 and another delicate thermometer is affixed 
 to the stand. Sulphuric ether, enough to 
 fiU three-quarters of the cavity of one of the 
 balls, is introduced, then boiled, and the tube 
 sealed. To ascertain the dew point, incline 
 the hygrooaeter till all the ether is in the 
 lower ball. The instrument is put down so 
 as to stand steadily, and the temperature of 
 the air noted on the thermometer on the 
 stand. Ether is poured on the muslin, \mtil 
 the cold produced by its evaporation, so 
 cools the temperature of the lower ball, that 
 dew is deposited on its surface. The degree 
 of the thermometer within, shows the accu- 
 rate dew point. 
 
 Daniell's Jet. A contrivance to ensure 
 the safety of the oxy-hydrogen blow-pii)e, 
 which it does to a certain extent ; that is, 
 while the pressure upon the bladders which 
 holds the gases is equal to both. 
 
 A bladder of oxygen is screwed on to the 
 end A, and when the stop-cock of the bladder 
 is turned, and pressure applied, the gas passes 
 through the centre of the jet. A bladder of 
 hydrogen is screwed upon C, and passes along 
 a tube, which is on the outside of, and com- 
 pletely incloses the oxygen tube, so that the 
 two gases are only in contact at the extremity 
 B, where they both issue. 
 
 Danish Balance. A kmd of steel yard, 
 in which the counterpoise or weight, is fixed, 
 but the fulcrum or support, js moveable. 
 It is represented below : — 
 
DA 
 
 DA 
 
 Daphni::^. The bitter principle of daphne 
 alpina and daphne mezereon. 
 
 Darcey's Alloy. (See Fusible Alloy.) 
 
 Dark Tent, or Chamber. The same as 
 the camera obscura, (which see.) 
 
 Data. In mathematics, certain quantities 
 whicli are given or known, and by means of 
 which other quantities which are unknown are 
 to he determined. 
 
 Datiscine, or Dahline. A vegetable 
 principle, which differs only from starch in 
 not having a blue, but a yellow color, when 
 iodine is added to it. It is produced by 
 boiling with water the roots of angelica, dah- 
 lia, sunflower, &c., evaporated till a pellicle 
 forms on the surface, and then left to cool ; 
 when datiscine will settle in the form of a 
 white powder. 
 
 Datum. The singular number of data, 
 (which see.) 
 
 Daturine. An alkaloid obtained from the 
 datura stramonium. 
 
 Davy's, (Sir H.) Analyzing Appa- 
 ratus. An instrument under this name is 
 sold by the chemical instrument makers, and 
 is adapted to analyze gaseous products. A is 
 a vessel, in which the substance to be ex- 
 amined is placed, either alone, or with water, 
 or some liquid which is necessary to de(>om- 
 pose it. If a gas arises from it, that gas 
 would pass to the vessel B, where it may be 
 absorbed, or purified, according to circum- 
 stances ; from thence it would pass to C, 
 where the final result may be examined. The 
 vessel D is a safety vessel, to prevent the 
 fracture of A by the too great pressure of 
 the gas formed within. 
 
 Davy's, (Sir H.) Decomposing Appa- 
 ratus. For tV'f* decomposition of water under 
 
 oil, and by electricity. A is a glass vessel, 
 with a glass tube closed at the top, in the 
 middle of it. D D are the two wires to 
 communicate the shock to explode the gases 
 formed. C C the wires connected with the 
 galvanic battery which decomposes the water. 
 Davy's, (SirH.) Furnace. A chemical 
 furnace, recommended and used by Sir H. 
 Davy. It is made wholly of sheet iron, the 
 fire-place being lined with fire-brick. The 
 fender below contains, first, the lower part 
 of the furnace, as represented. B is the 
 ash-hole, the upper part above B being the 
 place for the fire. I is a door covering 
 a hole leading to the fire, for the introduction 
 of muffles, tubes, &c. A is a smaller cylin- 
 der, which fits upon the former part, having 
 a door for the supply of fuel, and a chimney 
 to carry off the fumes. C is a third vessel, 
 which may be lifted off and on, as ocjasiou 
 requires ; the still, retorts, &c. are placed 
 here. The chimney F H runs through a 
 square iron trough G, which is used as a 
 gentle sand bath. 
 
 Davy's, (Sir H.) Safety Lamp, or 
 Miner's Friend. An instrument to pre- 
 vent the fatal explosions of fire-damp, to 
 which miners are exposed when working in 
 coal mines. It acts upon the principle, that 
 the flame will not penetrate a fine wire-gauze: 
 if, therefore, the flame of a lamp be surrounded 
 with wire-gauze, no danger is to be appre- 
 hended, even when surrounded by explosive 
 mixtures. A and B represent the lamp in 
 section, and according to its usual external 
 appearance. The other letters apply to both 
 figures. C is tlie cover of wire-gauze. D the 
 foot of the lamp, containing the oil and 
 cotton. E a tube for the supply of oil. Gthe 
 flame of the lamp, in the front of which is 
 a plano-convex lens, to increase the light. 
 H is a stout wire frame-work, by which the 
 lamp is held; and I is a hook to hang to the 
 miner's clothes, that the lamp may keep 
 steady. Around the wick is a small coil of 
 fine platinum wire, the use of which is as 
 follows : — When the lamp is carried into any 
 mixture of gases where there is no oxygen, 
 the flame goes out, and thus warns the miner ; 
 when he retires from the dangerous locality 
 and comes into a purer air, the platinum 
 
DA 
 
 DE 
 
 which has still remained red-hot, re-lights 
 the lamp. 
 
 "Daw's, (Sir H.) Tube Holder. A 
 stand of tin, with a spring socket, to hold a 
 eudiometer tube, when the 
 gases are to be exploded. This 
 simple instrument should have 
 the foot made like a tin dish, 
 in order that it may catch any 
 mercury or other liquid that 
 may be spilt by the explosion. 
 The eudiometer tube may be 
 taken out, and put in from 
 the top ; the finger or a cork 
 closing the lower extremity at 
 the time. 
 
 Davy's, (Sir H.) Radiating Appara- 
 tus. For showing the effects of the radiation, 
 from charcoal points, or incandescent wire, 
 when in vacuo. The figure will explain itself. 
 
 The poles of a galvanic battery are attached 
 one to each of the upper wires. These are 
 inclosed in glass tubes, which project into a 
 glass jar, which is supposed to be placed on 
 the table of the air pump, and exhausted of 
 air. Within the glass is a concave mirror, 
 a thermometer, and the lower tips of the 
 wires, or charcoal points. 
 
 Day. The bay or light of a window, be- 
 tween two mullions, that is, one of the com- 
 partments of a Gothic window, measuring it 
 from the tracery at top to the sill below. 
 
 Day. In astronomy, is that portion of 
 time which elapses between two successive 
 transits of the sun over the same meridian, 
 the hours being counted from the one transit 
 to the other, or from 1 to 24 ; this is the 
 civil day. In common conversation, day is 
 the period of time during which we have the 
 sun's light, and used in contra-distinction to 
 niffkt, or the time of darkness. A solar 
 day is the exact time from one transit of the 
 sun over a meridian to its return to the same 
 point again. This varies slightly at different 
 times of the year, sometimes being rather 
 more, and at others rather less than the 
 ordinary or civil day; on account of which, 
 the time as indicated by clocks is at certain 
 seasons before that shown on a sun-dial, at 
 other seasons proportionably behind. A 
 mean between all the differences of the solar 
 days, is called mean solar time. 
 
 Day, Siderial. The time in which the 
 earth makes one complete revolution on its 
 axis, as indicated by the two successive 
 transits of a star over a certain meridian. 
 The siderial day is about 4 minutes less than 
 the mean solar day, the difference arising 
 from the motion of the earth in its orbit. 
 Hence there are 366 siderial days, and 365 
 solar days in a year. 
 
 Day Telescope. (See Telescope.) 
 
 Day and Night Thermometer. (See 
 Rutherford.) 
 
 Dead Level. (See Level.) 
 
 Dead Lights. The shutters which close 
 over the windows of a cabin in stormy 
 weather. 
 
 Dead Water. The still water always ob- 
 servable immediately behind the stem of a 
 ship. 
 
 Dead Reckoning. An account of the 
 progress of a vessel, showing the courses 
 steered by compass, with the distance in 
 leagues, miles, &c., on each course. When 
 lee-way, variation, &c. have been allowed 
 for, it is called corrected dead reckoning. 
 The term is used in contra-distinction to a 
 reckoning obtained by celestial observations. 
 
 Deafening, or Deadening. Filling up 
 the interstices of partitions, floors, &c. with 
 cork, or other material, for the purpose of 
 preventing the communication of sounds from 
 one apartment to another. 
 
 Deal. The wood of the fir tree, as cut 
 up for the purpose of building. It is of two 
 kinds, white and yellow. The white deal is 
 soft, and fit only for in-door work ; the 
 yellow, owing to its being filled with turpen- 
 tine, is harder, stronger, and more durable 
 when exposed to the weather. Deals are 
 usually 9 inches wide and 2^ or 3 inches thick. 
 
DE 
 
 DE 
 
 De Butt's Differential Thermo- 
 meter, is represented annexed. It consists 
 of a tube of glass, with a ball at each 
 end, the lower ball being turned up, 
 as in the figure, and a scale attached 
 to the stem. The reason of the lower 
 ball being turned up is, that it 
 may hold a portion of air, without 
 that air escaping into the tube, and 
 thence into the upper ball. This 
 instrument is either to be suspen- 
 ded perpendicularly, or supported 
 on a stand. There being a differ- 
 ence in the volume of air in the 
 two balls, one is more affected 
 than the other by a change of tem- 
 perature ; hence the term applied 
 to these instruments of differential 
 thermometer. The liquid recom- 
 mended is sulphuric acid, tinged 
 with carmine ; a fluid which easily 
 evaporates, such as spirits, being 
 inapplicable. 
 
 Debris. The fragments of rocks, &c. 
 
 De Caus's Stkam Engine. A kind of 
 fountain, acting by the force of steam : useful 
 to record now, only because of being the 
 first application of the elasticity of steam, 
 and its force when under a pressure. 
 
 cagon, multiply its side by 7'G942088, that 
 being the area of a decagon whose side is one. 
 
 A globular vessel A is nearly filled with 
 water by the pipe '. When thus supplied, 
 fire i« placed beneath the vessel until the 
 water boils. The cock in B being closed, 
 the steam will soon accumulate, and being at 
 a pressure will drive the water up the pipe C. 
 
 Decantation. The action of pouring off 
 the clearer parts of a fluid, by gently inclining 
 the vessel after the grosser parts have been 
 suffered to subwde. 
 
 Decagon. A geometrical figure, ^vith ten 
 sides and ten angles. If all these be alike, it 
 is a regular decagon. To find the area of a de- 
 
 Decastyle. a building, of which the 
 portico has ten columns. 
 
 Decimal. Any number increasing or de- 
 creasing by tens. . 
 
 Decimal, Arithmetic. That part of the 
 science of numerical calculation, which treats 
 of decimal fractions. 
 
 Decimal Fractions, or Decimals. 
 Such fractions as have 10, or some multiple 
 of 10 for a denominator ; for example 5 
 with a dot before it, thus "5 is a decimal, and 
 signifies 5-lOths, or 5 parts out of 10. '67 
 is also a decimal, reckoning for 67 parts out 
 of 100. -433 is so many parts of 1000; 
 the number of cyphers belonging to the de- 
 nominator being always equal to the number 
 of figures which compose the decimal. The 
 following is a decimal and whole number 
 joined together, I'25, and which signifies 1|-, 
 the decimal '25 meaning so many parts of 
 100 ; this is one-quarter of it. 
 
 Decimal Point. A full point placed on 
 the left hand of decimal fractions, intended 
 to separate them from whole numbers when 
 both are imited, or to distinguish them as 
 decimals when standing alone, as 5*7143 and 
 •4038. 
 
 Decimal Scale. Any scale in which a 
 certain distance is divided into ten equal 
 parts. Scales of this kind are infinitely more 
 valuable to the artist and builder in setting 
 out or altering the size of drawings, than 
 such as are divided into twelves, unless inches 
 be indispensable. (See Diagonal Scale.) 
 
 Declination. In astronomy, the distance 
 of the sun, star, or other heavenly body, from 
 the equator, either north or south. Similar 
 therefore to latitude in geography. 
 
 Declination. Parallel circles of. (See 
 Circles.) 
 
 Declination, Parallax or Refraction of 
 is such an arc of the meridian as is equal to 
 the change produced in the declination by 
 parallax or by refraction. 
 
 Declination op the Doric Mutule, 
 is the acute angle which the planes of the 
 wall and soffit make with each other, which 
 with the soffit or underpart of the mutule is 
 lower at its projecting extremity than it is at 
 its receding extremity where it commences. 
 
 Declinator. An instrument used in 
 dialling, for taking the angle or degree of 
 slope of inclined planes. 
 
DE 
 
 DE 
 
 Decliners, or Declining Dials. Such 
 dials as cut either the plane of the prime ver- 
 tical circle or plane of the horizon obliquely. 
 
 Declivity. A sloping or oblique descent. 
 
 Decoction. The operation of boiling ; 
 also the liquid which by boiling has been made 
 to dissolve and imbibe any substance boiled 
 with it. 
 
 Decomposing Apparatus. An instru- 
 ment made of glass, wires, &c., to show the 
 decomposition of water by galvanic action. 
 It may be of two kinds ; in one, the compo- 
 nents of water, which are oxygen and hy- 
 drogen, are caught in the same tube, as in 
 fig. 1. In the other instrument there is a 
 tube for each, as in fig. 2. 
 
 A is a glass vessel, furnished with a foot, 
 and with two necks B and C. Through these 
 necks are placed wires of platinum, one end 
 of each wire being out of the glass cup, the 
 other end projecting into the tabe D, which 
 takes off and on as required ; thus in fig. 1 , 
 the inner ends of both wires are in the same 
 tube ; in fig. 2, in different tubes. To use 
 the apparatus, fill A with acidulated water ; 
 also fill D with the same, and put it in its 
 place over the wire ; then pass a galvanic 
 current through the wires, and the water 
 between will be decomposed into its two ele- 
 ments, oxygen and hydrogen ; the latter 
 being half the oxygen. 
 
 Decomposition. The separation from each 
 other of the constituents of a compound body ; 
 thus atmospheric air decomposed gives out 
 oxygen and nitrogen. Decomposition may 
 be occasioned by chemical action, however 
 such action may be produced, whether by 
 mixture, heat, light, electricity, &c. Hence 
 we speak of electrical, chemical, and other 
 decompositions. If one body or compound 
 is alone acted upon, the decomposition of it 
 is called simple; but if two substances act 
 upon each other, so that they are both sepa- 
 rated into their elements ; and these elements 
 ■gain unite in any different manner, »o as to 
 
 form substances of properties distinct from 
 the first, the decomposition is called double. 
 The former arises from simple or single 
 affinity ; the latter from double affinity or 
 attraction. 
 
 Decomposition of Forces. The same 
 as resolution of forces. 
 
 Decomposition of Light. The dividing 
 a ray of solar light into its seven prismatic 
 colors. 
 
 Decrements are the small quantities by 
 which a variable quantity decreases ; and are 
 thus opposed to increments, which are the 
 small parts by which a variable quantity 
 increases. 
 
 Decrepitation. The crackling noise 
 which several salts make when suddenly 
 heated, accompanied by a violent throwing 
 off of their particles. 
 
 Decuple. Ten-fold ; a term of relation 
 between quantities, one of which is 10 times 
 as much as the other. 
 
 Decussation. Cutting or crossing. 
 
 Defecation. The freemg from impurities 
 or dregs. 
 
 Deficient Numbers are those the sum 
 of whose divisors are less than the number 
 itself; for example, the only numbers which 
 will divide 27, without a remainder, are 9, 3, 
 and 1. These added together make 13, or 
 a number less than 27, which is therefore a 
 deficient number. 
 
 Definite Proportions. The exact pro- 
 portions in which chemical substances unite 
 with each other. 
 
 Definite Quantities. In mathematics, 
 such as are of a certain and determined mag- 
 nitude. 
 
 Definition. A brief enumeration of such 
 attributes of a thing as serve to distinguish 
 it from all others. 
 
 Deflagrating Jar and Spoon. The 
 first is a glass jar, with a large opening at the 
 top for the insertion of a cork or stopper, 
 through which is thrust in some experiments 
 a metal spoon, shap>ed as in the cut; in other 
 experiments, a coiled wire, a piece of char- 
 coal, &c. The whole is intended to show 
 that oxygen and other gases are supporters 
 of combustion. Sometimes the mouth of 
 the deflagrating jar is ground flat, that it may 
 be covered with a piece of plate glass, instead 
 
DE 
 
 DE 
 
 of being stopped with cork. The jar when 
 in use stands in a basin of water or mercury, 
 according to the gas operated upon. 
 
 Deflection, or Deflexion. The turning 
 any thing aside from its previous course, by 
 some adventitious or accidental circumstance ; 
 also the bending of a beam of timber by its 
 own weight, or by a weight placed upon it. 
 Deflective Forces are those forces 
 which act upon a moving body in a direction 
 different from that of its actual course ; such 
 is the attractive force of the sun to the earth 
 in its orbit. 
 
 Degree. In algebra, is a term applied to 
 equations to distinguish the highest power of 
 the unknown quantity; thus, if the index 
 of that power be 3 or 4, the equation is said 
 to be of the third or fourth degree. In 
 geometry, astronomy, &c., a degree is the 
 360th part of a circle, the length of the de- 
 gree varying according to the size of the cir- 
 cle ; thus, a degree of the equator is 69^ 
 statute miles ; but a degree measured on a 
 smaller circle is proportionably less. A de- 
 gree is indicated by a small circle, and is 
 sub -divided into 60 minutes, and that into 
 60 seconds; thus, 34°, 27', 55", signifies 
 34 degrees, 27 minutes, and 55 seconds. All 
 angular measurement is taken in degrees. 
 (See Angle.) 
 
 Degree of Latitude^ is such a distance 
 on a meridian as the observer must pass to 
 vary his latitude one degree, or to increase 
 or diminish the distance of a star from the 
 zenith by one degree. It is by the exact 
 measurement of a degree of latitude, or what 
 is the same thing, a degree of the arc of the 
 meridian, that the peculiar oblately spheroidal 
 figure of the earth is determinable. 
 
 Degree of Longitude, is the space between 
 two lueridians, that make an angle of 1° with 
 each other at the poles ; thus meridians ap- 
 proach each other from the equator, and join 
 at the poles. The degrees of longitude vary 
 in every degree of latitude, until at either 
 pole they become nothing — the poles there- 
 fore have no longitude. 
 
 De la Faye's Pump. An hydraulic en- 
 gine, of very simple structure, of considerable 
 power, and with little friction. 
 
 AAA represent the arms of a wheel. 
 These arms are hollow, and communicate at 
 the centre with the barrel O, and project 
 through the rim, opening there by the holes 
 C C C. When the wheel is turned roimd by 
 the action of the stream against the float 
 boards B B B, it scoops up the water by the 
 holes C C C, and as this turns round, the 
 water passing along the channels A A, is 
 finally deposited in O ; running thence it is 
 caught by the trough B, and may be con- 
 veyed afterwards to any situation where it is 
 required. It will be seen that the water 
 cannot be raised higher than the axis of the 
 
 wheel, but that is generally enough for the 
 purposes of irrigation. 
 
 De la Hire's Pump. A lift and force 
 pump combined, which raises a like quantity 
 of water both by its up and down stroke. 
 
 J is the working barrel in which the solid 
 piston I moves up and down by the pump 
 rod A. G is the feeding pipe, and H the 
 stop valve upon it. K is a lateral pipe, pro- 
 ceeding upwards from the bottom of the 
 working barrel, until it terminates in the 
 under part of the air vessel I, where it is 
 closed by a valve. This working barrel is 
 closed at the top, the pump rod A working 
 tightly through a hole at B. Consequently 
 when the piston rod is depressed to expel the 
 water from the lower part of the barrel into 
 L, the vacuum formed above the piston is 
 filled not by air, but by water from the 
 vessel E, while a contrary stroke shuts the 
 valve D, and forces the water above the pis- 
 ton into L by the pipe F. 
 
 De la Rive's Floating Galvanic 
 Apparatus, consists of a coil of fine wire, 
 about 3 inches diameter, A ; the ends of this 
 pass through a round cork B, and are ter- 
 minated below; the one by apiece of zinc Z, 
 the other by a piece of copper C — each about 
 1 inch square. This apparatus shows the 
 magnetic polarity when put to float in a basin 
 
DE 
 
 DE 
 
 of acidulated water ; one side of the coil 
 turning to the north ; the other to the south. 
 (For an improvement of this insti-ument, see 
 Marsh.) 
 
 Db la Rue's Gax^vanic Battery, 
 represented below :— 
 
 It consists of a series of copper cells, or 
 square boxes. Each box is furnished with 
 a plate of zinc, and the various boxes are 
 arranged along a square frame, depending 
 from it by lips or shoulders of copper. It is 
 to be filled with a saturated solution of sul- 
 phate of copper, and some crystals of the 
 salt placed in the solution, in order to supply 
 the waste occasioned by the decomposition 
 of the solution which arises from the gal- 
 vanic action. 
 
 Deleterious. Deadly or poisonous ; as 
 many plants, also the following and many 
 other gases, chlorine, arseniuretted hydrogen, 
 and sulphurous acid gas. 
 
 Delft Ware. A kind of pottery, co- 
 vered with a white glazing, which gives it an 
 appearance of porcelain, such as the com- 
 mon plates, cups, basins, &c. 
 
 Deliquescence. The spontaneous melt- 
 ing of certain saline bodies when left exposed 
 to the air, in consequence of the water they 
 attract from it. 
 
 Delphinia. a vegetable alkaloid, dis- 
 covered to exist in and which occasions the 
 peculiar medicinal properties of delphinium 
 staphysagria. 
 
 De Luc's Dry Pile, or Electric Co- 
 lumn. Take a tube of glass, and after having 
 prepared some 2 or 3000 pieces of paper, of 
 copper or silver leaf, and of zmc leaf or foil, 
 
 and cut or punched them into circular pieces 
 of the internal diameter of the tube ; fill it 
 by putting^ in first a piece of copper, then a 
 piece of zinc, then a piece of paper, again 
 copper, zinc, paper, and so on, until the tube 
 is quite full. This would constitute De Luc's 
 dry pile, and if the two poles are brought 
 near each other by a wire attached to the 
 upper end, and hanging downwards near to 
 the lower end, a small pith ball will play 
 between them, or be attracted first to one, 
 and then the other alternately, (see fig. 1 ;) 
 in which A is the pile — B the, wire and ball ; 
 and C a fine silk thread, holding the pith ball. 
 An instrument of this kind is commonly called 
 the electric perpetual motion, {see Melloni,) 
 from the long duration of its action. A pile 
 of this description, of 2000 pairs of plates, 
 has been known to go incessantly for twelve 
 years, and even then stopped by an injury 
 only. The other figure of the cut shows two 
 such piles D D, with their lower ends termi- 
 nated by bells F F ; the letter E being the 
 thread and balls. In a double tube of this 
 kind, it is essential that the upper end should 
 be in close contact with the ^scs of metal, 
 and the order of copper, zinc, paper, be 
 carefully continued throughout. 
 
 C ilA B 
 
 *H~" 
 
 "PT 
 
 11 
 
 1 
 
 i 
 
 1 
 
 1 
 
 1 
 
 § 
 
 E = D 
 
 1 
 
 
 1 
 
 1 
 
 A, 
 
 A^ 
 
 Demitint, is a gradation of color between 
 positive light and positive shade ; called 
 also half tint. 
 
 Demonstration. In mathematics, a me- 
 thod of reasoning, whereby the truth of an 
 assertion is shown by one or more propo- 
 sitions, the truth of which is already estab- 
 lished, or admitted. 
 
 Dendrometer. An instrument for mea- 
 suring the altitude of trees ; and in general 
 terms, any contrivance for measuring the 
 magnitude of objects at a distance. 
 
 Denominator. The lower term of a vul- 
 gar fraction : thus in i, f , i, &c., the de- 
 nominators are 2, 4, and 8. If two or more 
 fractions are placed together, having the same 
 number to constitute the lower line of each, 
 such number is called their common denomi- 
 nator. 
 
DE 
 
 DE 
 
 Density. Weight. Strictly speaking den- 
 sity denotes closeness of particles in any 
 body ; it being assumed that those bodies 
 are the most dense in which the particles are 
 more closely pressed together, or which con- 
 tain, in proportion to their size, the greatest 
 number of atoms. 
 
 Dent. The wire staple which forms the 
 tooth of a card. 
 
 Dentels, Dentils, Denticles, or 
 Blocks. Square, or tooth-like ornaments, 
 cut out of a square moulding ; common under 
 the cornice of Ionic, Corinthian, and Com- 
 posite buildings. The range of them is often 
 called the denticulated band or the block 
 course ; and a cornice so attended is a block 
 
 IWliiiilll 
 
 Denticule. The flat projecting part of a 
 cornice, on which dentiles are cut. 
 
 Deoxydating Rays of Light. In the 
 decomposition of white light into the pris- 
 matic colors, it has been observed, that the 
 violet end of the spectrum, and also a point 
 just beyond this, occasion chemical changes 
 more rapidly than the red and yellow rays ; so 
 that paper, imbued with the chloride of gold 
 or silver, remains nearly unchanged in the 
 latter place, but rapidly becomes blackened 
 in and beyond the violet rays. These, there- 
 fore, are called the deoxydating rays, the 
 change of color depending upon the reduction 
 of the metal. 
 
 Deoxydation is the depriving a body of 
 the oxygen which it contains : thus chlorate 
 of potass, oxyde of manganese, and numerous 
 other bodies part with oxygen when heated, 
 and in proportion become deoxydated. 
 
 Departure. In navigation, is the differ- 
 ence of longitude the ship has made, between 
 the place where the last reckoning was made 
 and that which she has now arrived at. 
 
 Depilatory. Is the name of any substance 
 capable of removing hairs from the human 
 skin, without injuring its texture. The fol- 
 lowing is such a composition ; it is called by 
 the hair- dressers roseate powder — quick-lime 
 12 oz., starch 10 02., orpiment 1 oz. — mix 
 them together ; put a small piece on the skin, 
 wipe it off, and wash the part immediately. 
 
 DEPHI.EGMATION. Any process by which 
 bodies are deprived of water. 
 
 Dephlogisticated. a term of the old 
 chemistry, implying deprived of phlogiston 
 or the inflammable principle, and nearly sy- 
 nonymous with what is now expressed by 
 oxygenized or oxygenated. 
 
 Dephlogisticated Air. The same as 
 oxygen. 
 
 Depolarization of Light. The redu- 
 cing or restoring a ray of polarized light to 
 
 its former state. If a slice of mica, tour- 
 maline, selenite, or certain other crystals, be 
 put so as to intercept a ray of polarized light, 
 and then be turned round, it will be found 
 that in two opposite parts of the revolution, 
 the images cast by the ray of polarized light 
 will become invisible. In this state it is said 
 to be depolarized. 
 
 Depression. A sinking or pressing down ; 
 thus the depression of the pole is the ap- 
 parent approximation of it towards the ho- 
 rizon as we sail towards the equator. The 
 depression of the sun or moon is its distance 
 below the horizon. The depression of ilie 
 visible horizon is its apparent extension, 
 either in consequence of our ascending an 
 eminence, or else from peculiar states of the 
 atmosphere. The word dip is often used in 
 the same sense. 
 
 Depth. The third dimension of a solid, 
 the others being length and breadth ; or it is 
 the distance of one object below another, as 
 the depth of a well is the distance from the 
 top to the bottom of it. 
 
 Derbyshire Spar. Iluate of lime. 
 
 Desagulier's Steam Engine, invented 
 about 1716, and adapted to the pumping of 
 water only , it not being furnished with either 
 beam or steam cylinder. 
 
 A spherical boiler is inclosed in brick- 
 work. B B are the two guage cocks. C is 
 the fire-place, and D the ash pit. E the 
 chimney. F the four- way cock, to turn the 
 steam off and on, and also to let in the water 
 for condensation. G the pipe to convey 
 steam from the boiler. H the condenser. 
 I the injection cock and pipe. L the well 
 of water. M the eduction pipe, to convey 
 away the water raised by the engine. Steam 
 being admitted to H, drives the water in L 
 before it, through the valve N, stopping up 
 at the same time the valve K. "When the 
 steam is shut off, and cold water admitted, 
 the removal of the steam pressure forces die 
 
DE 
 
 DE 
 
 water of the well through K into H again, 
 while the next admittance of the steam 
 carries this fresh portion of water also into 
 M, as in the first instance. 
 
 Descending Latitude, is the latitude of 
 a planet, in its return from the nodes to the 
 equator. 
 
 Descent of Bodies. The tendency to 
 fall, or to move towards the centre of the 
 earth. 
 
 Descknsion. In astronomy, the contrary 
 to ascension, it may be either right or ob- 
 lique. Right descension, is the arc of the 
 equator, which descends with the sign or 
 star below the horizon, of a direct sphere. 
 Oblique ascension, the arc which descends 
 with the star, on an oblique sphere. The 
 difference between this is called the dis- 
 censional difference. 
 
 Describent. In geometry, a line, or 
 surface, which produces a plain figure by 
 motion. 
 
 Desiccation. Drying any thing, whether 
 by evaporating the water contained in it, or 
 by absorbing the water by the addition of 
 any thing which rapidly attracts it. 
 
 Design. An original sketch, or drawing, 
 from which a building, or other work of art 
 or genius may be executed by other persons. 
 
 Destructive Distillation. When or- 
 ganized substances, or their products, are 
 exposed to distillation, until the whole has 
 suffered all that the furnace can effect ; the 
 process is called destructive distillation. 
 
 Detached. In painting, such figures, 
 buildings, trees, &c. as appear standing out 
 from the back ground in a natural manner, 
 the other parts appearing in their proper 
 relative situations. 
 
 Details. Such drawings, models, and 
 instractions, as are sufficiently large and 
 carefully executed to show the exact par- 
 ticulars of the more minute parts of a build- 
 ing, a machine, &c. 
 
 Detent. Something that locks or unlocks 
 a movement ; the word is chiefly applied to 
 clock-work. That particular catch which falls 
 into the striking wheel, and stops it from 
 striking more than the right number of 
 strokes, is called the detent ; so also is any 
 similar part which belongs to an escapement. 
 
 Deterioration. An act, or cause, by 
 which any thing is damaged or injured. 
 
 Detonating Oil. Chloride of nitrogen, 
 one of the most dangerously explosive com- 
 pounds known, a drop no larger than a 
 grain of mustard seed occasioning a dreadful 
 detonation when touched with phosphorus, 
 or either of the fixed oils. It may be made 
 thus : — partly fill a basin with a solution of 
 1 part of sal-ammoniac to 12 of water, and 
 invert over it a tall jar of chlorine. A yellow 
 oily film will soon form on the surface, which 
 is the chloride of nitrogen. 
 
 Detonating Powders. Certain chemical 
 compounds, which on being exposed to heat 
 or friction, explode with a loud report. Of 
 this description are gunpowder, the fulmi- 
 nates of gold, silver, and other metals. A 
 common detonating powder may be made by 
 triturating in a warm mortar, 3 parts by 
 weight of saltpetre, 2 of carbonate of potass, 
 and 1 of flour of sulphur. When thoroughly 
 mixed together, a little of the mixture may 
 be put in a ladle, and if suffered to heat 
 gradually, it will explode with a terrific 
 report. 
 
 Detonating Tube. (See Eudiometer.) 
 Detonation. A sudden combustion and 
 explosion. 
 
 Device. An emblem, or metaphor, which 
 represents one object, by another which bears 
 some resemblance to it ; such as the device 
 on a crest, shield, &c. 
 
 Devices on Glass. If a number of 
 spangles of tin-foil be pasted on a sheet of 
 glass so as scarcely to touch each other, and 
 an electrical current pass through them, by 
 holding one end of the glass in the hand, 
 and taking a spark with the other end ; this 
 spark will appear as a line of light, or a 
 continued series of sparks, in the intervals 
 between the spangles. A similar appearance 
 is produced by strips of tin-foil properly 
 connected at the end, as in fig. 2 ; and cuts 
 made with a pen-knife across the strips so as 
 to make an interruption in the circuit; words 
 are thus made. If it be desired to make a 
 complicated figure, or device, the tin-foil 
 must be carried first along one side, then 
 return by the other side of the glass, as in 
 fig. 3, where the different sides are made by 
 different colors in the cut. 
 
 Devil. A machine for dividing rags or 
 cotton, in the first process of paper making. 
 
 Deutoxvde, literally means the second 
 oxyde ; but is usually employed to denote a 
 compound containing 2 atoms, or 2 prime 
 equivalents of oxygen to 1 of metal : thus 
 we say deutoxyde of copper and deutoxyde 
 of mercury. 
 
DI 
 
 Dl 
 
 Dew. The moisture insensibly deposited 
 from the atmosphere on the surface of the 
 earth. 
 
 Dew Point. The degree indicated by the 
 thermometer, when dew begins to be de- 
 posited. 
 
 Dextrine, or British Gum. A matter 
 of a gummy appearance, formed from starch, 
 by the action of acids upon it. It is much 
 employed by the French pastry-cooks and 
 confectioners, and with us in the dressing of 
 various textile fabrics, instead of gum arable, 
 for which it is a good substitute. 
 
 DiAcousTics. The properties of sound, 
 refracted by passing through different media. 
 
 DiADROME. The swing of a pendulum. 
 
 DiAGLYPHic. Such works of sculpture, 
 engraving, &c., as represent the objects as 
 sunk into the general surface ; in opposition 
 to anaglyphic. 
 
 Diagonal. A straight line which stretches 
 across from one angle to another of a geome- 
 trical figure, not being either of the sides of 
 it. The dotted lines in the following dia- 
 grams are diagonals of the respective figures ; 
 besides which, others might have been drawn 
 from different angles : — 
 
 Diagonal Barometer. (See Barometer.) 
 Diagonal Moulding. (See Cheveron 
 
 and Fret.) 
 
 Diagonal Machine. A portable kind 
 
 of reflective cosmorama, for viewing pictures. 
 
 It is represented below : — 
 
 A is a large magnifying lens of about two 
 feet focus. B a looking glass, suspended 
 from the top of A, and moving so stiffly that 
 it may be set to any angle, that of 45° is 
 most usual. C is a socket and screw in the 
 stand to elevate or depress the upper part of 
 it. D the picture to be viewed. The light 
 from the picture impinges upon the face of 
 B ; here it is reflected to A, and passing 
 through A, reaches the eye considerably 
 magnified. 
 
 Diagonal Scale. A useful mathematic 
 scale ; so called, because the smaller divisions 
 are ascertained by lines which run diagonally 
 across the other divisions. It is usually made 
 to measure the decimated numbers, thou- 
 sands, hundreds, tens, and units. The whole 
 scale being 1000, the chief divisions of it 
 would reckon as 100 each. The sub -divisions 
 of one of these parts, as shown at the end 
 of the following cut, would be 10 each ; and 
 as the diagonal lines run from one 10 on one 
 side of the scale to the next 10 on the other 
 side of the scale, by counting on the longi- 
 tudinal lines, reckoning them from 1 to 10 
 upwards, the odd number of units may be 
 also easily ascertained. 
 
 Diagram. In mathematics, an outline 
 representation of a body, or of the properties 
 and progress of a mathematical demon- 
 stration. 
 
 Diagraphics. The art of design, or 
 drawing. 
 
 Dial, or Dial-plate. Tlie face of a 
 clock or watch, over which the hands move, 
 and upon which the figures denoting the 
 hours are delineated. 
 
 Dial, or Sun-dial. An instrument serving 
 to measure time, by means of a shadow cast 
 by the sun from a rod, stile, or gnomon, 
 fixed upon the dial. 
 
 Dialling. The art of drawing sun-dials, 
 so as to indicate the exact solar time. The 
 principles of dialling may be understood by 
 imagining a hollow sphere of glass with 
 24 lines painted upon it as meridians, one 
 for each hour of the day, in one of which 
 the given place is marked ; for example, Lon- 
 don, supposed at the point E, and at the 
 equator, on the same meridian, is marked 
 XII., and also on the opposite one; and on 
 all the other meridians, the other hours in 
 regular order ; these would be the hour 
 circles of London. Then, if the sphere had 
 an opaque axis, as A B, the shadow of the 
 axis would fall upon every meridian and 
 hour, as the sun came to the plane of the 
 
 X 
 
DI 
 
 DI 
 
 opposite meridian. If, then this sphere were 
 cut in two hy a solid plane D C, in the ra- 
 tional horizon of London, the shadow of 
 part of the axis above the plane would be 
 thrown across the plane, forming straight 
 lines from the axis to the various meridians, 
 the figures proper to each meridian being 
 painted on these lines. The globe may be 
 taken away, but the axis remaining would 
 nevertheless indicate on the dial now formed, 
 the true solar time : this is called a horizontal 
 dial, but upon precisely the same principle 
 a vertical or other dial may be formed. 
 
 Diameter. A straight line which cuts a 
 circle into two equal parts ; (see Circle.) The 
 diameter of a column is the thickness of the 
 shaft, measui-ed at the bottom. Its diameter 
 of diminution is measured across the shaft 
 at top. An ellipse has two diameters ; the 
 transverse, which measures from end to end, 
 and the conjugate, or the distance from side 
 to side. 
 
 Diamond. A precious stone, which is car- 
 bon in a state of crystallization. It is the 
 hardest known substance, and therefore, when 
 powdered, is used for grinding other stones 
 scarcely less hard, and which nothing else 
 would cut. When polished, which it may 
 be by its own powder, it shows so great a 
 power of reflection that a beautiful play of 
 colors is seen upon the surface. It is difficult 
 to inflame, but when once ignited, it con- 
 tinues to burn with a steady reddish light, 
 
 Diamond Fret. An architectural orna- 
 ment so called, and represented as follows : — 
 
 Diamond Microscopes. Microscopes, 
 the abject glasses of which are formed of 
 diamonds, ground of a lens-like form. The 
 light of this lens is said to be superior to 
 that of any compound microscope whatever, 
 acting with the same power and the same 
 angle of aperture. 
 
 Diamond Spotted Jar. A Leyden jar, 
 which, instead of a continuous coating, is 
 covered with diamond or 
 other shaped pieces of tin- 
 foil, just touching each 
 other. When a jar like this 
 is discharged in a darkened 
 room, it presents a beauti- 
 ful luminous appearance. In 
 making it, observe to cover 
 the bottom wholly with tin- 
 foil, both inside and out ; 
 then place the diamond 
 spots on the inside first, so 
 that they shall not quite 
 touch each other, and after- 
 wards, stick the outer ones 
 so as exactly to cover those within ; they 
 will, therefore, have an equal space between 
 each coi'ner, at which the luminous sparks 
 will be seen. 
 
 Diaper. Panelling, filled up with ara- 
 besque gilding and painting, or else carved 
 in low relief. Walls, both external and in- 
 ternal, are often diapered, particularly the 
 buildings of the thirteenth and fourteenth 
 centuries. 
 
 
 Diaper. The name of a kind of cloth, 
 used chiefly for table linen. 
 
 Diaphantine Analysis, or Problems. 
 In algebra, are certain questions relating to 
 square, cube, &c. numbers, and rational 
 right-angled triangles, the properties of which 
 were first discussed by Diaphantus. 
 
 Diaphonics. The same as diacoustics. 
 
 DiASTACE. A substance extracted by water 
 from crushed malt, and precipitated from 
 that solution by alcohol. 
 
 DiASTYLE. A term used by Vitruvius, to 
 signify a space between two columns, equal 
 to three diameters. 
 
 Diathermatous. a term to designate 
 those bodies which readily allow of the 
 passage of radiant heat ; for example, glass^ 
 alum, the sulphate of copper, &c., though 
 pervious to light, entirely or very nearly in- 
 tercept radiant heat : yet rock salt, rock 
 crystal, &c., suffer its ready transmission ; 
 these last then are diathermatous. 
 
 Die. a cube ; the term is applied in 
 architecture to any square or cubical part, 
 as the trunk or naked part of a pedestal, 
 between the base and the cornice. lu the 
 
DI 
 
 DI 
 
 arts, a die is a stamp, or reversed impression 
 of a coin, medal, or other similar object, 
 made for the purpose of impressing the de- 
 vice or motto cut out on the surface of it 
 upon a piece of metal prepared to receive 
 that impression. Thus, the coin of the realm, 
 figured buttons, and numerous other small 
 articles are placed and stamped between dies. 
 
 Differential. In the higher geometry, 
 is an infinitely small quantity, or part of a 
 quantity so small as to be less than any 
 assignable one. 
 
 Differential Calculus, is a method 
 of differencing quantities, or of finding an 
 infinitely small quantity, which being taken 
 infinite times, shall be equal to a given 
 quantity ; or it is the arithmetic of the in- 
 finitely small differences of variable quantities. 
 
 Differential Galvanometer. Two 
 wires of equal size and length are twisted 
 together so as to form a compound wire, 
 which is coiled around a compass needle, and 
 the four extremities of the wires are im- 
 mersed in four cups filled with mercury. By 
 this means any two currents that are to be 
 compared with each other may be sent in 
 contrary directions through the wires. These 
 opposite currents acting upon the needle 
 under precisely similar circumstances, will, 
 if they be equal, exactly counteract each 
 other, and the needle will be undisturbed. 
 If the currents be unequal, the needle will 
 be influenced accordingly. 
 
 Differential Thermometer. (See 
 Air Thermometer, ^therioscope, S^c.) 
 
 Digester. A kind of boiler, invented by 
 Mr. Papin, for raising water to a higher 
 temperature than the common boiling point, 
 212°. This is effected by forming a vessel 
 like a common iron saucepan, with a cover, 
 which fits tightly on, so tight indeed, that 
 steam cannot escape. The cover is furnished 
 with a safety valve. 
 
 Digestion. The slow action of a solvent 
 upon any substance. 
 
 Digestive Salt. Muriate of potass. 
 
 Digit. In arithmetic, any one of the ten 
 numerals, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0. Digit 
 is also a measure equal to three-fourths of 
 an inch ; and also a measure by which the 
 quantity of an eclipse is ascertained. Thus the 
 disc or face of the sun and moon is supposed to 
 be divided into twelve digits ; and therefore, 
 according to the proportion of the sun or 
 moon's face, which may be obscured, we 
 say that it is eclipsed 8, 10, 11 digits, and 
 so on. 
 
 DiGLYPH. A tablet with t^vo channels cut 
 upon it. (See Trigbjph.) 
 
 Dilatation. The expansion of a body 
 into a greater bulk by its own elasticity : 
 thus, if an elastic body be compressed, upon 
 the pressure being removed it will dilate 
 itself again. 
 
 Dilettanti. An admirer or lever of the 
 fine arts ; or one who delights in their pur- 
 suits. 
 
 Dimension is either length, breadth, or 
 thickness. A line has only one dimension, 
 length ; a surface, two dimensions, length 
 and breadth ; and a solid, three, as length, 
 breadth, and thickness. 
 
 Diminished Bar, of a window sash ; 
 one that is thinner on the inner edge than 
 where the glass touches it. It is thus cut 
 in order to give it a lighter appearance. 
 
 Diminution of Columns. The con- 
 tinued contraction of the diameter, from the 
 base to the top of the shaft. 
 
 Dioptric Telescope. (See Refractive 
 Telescope.) 
 
 Dioptrics, or Anaclastics. The pro- 
 perties of refracted vision, which investigates 
 and explains the effects of light refracted by 
 passing through different media, as air, water, 
 glass, &c. 
 
 Diorama. An exhibition of a painting, 
 seen through a darkened opening, which 
 having the effect of confining the sight and 
 attention to the objects of the picture, makes 
 it appear more natural than under ordinary 
 circumstances ; while the effect is heightened 
 by the variety and quantity of light thrown 
 upon the face of the picture by means of 
 red, yellow, and other colored blinds drawn 
 before the wmdow, which illuminates the 
 picture. 
 
 Dip of the Magnetic Needle. If a 
 finely balanced bar of steel be magnetized, 
 the north pole of it will, in this latitude, 
 dip or droop downwards, till it stands at from 
 70" to 75°, varying a trifle annually. This 
 is called the dip of the needle, and is owing 
 to the attraction of the earth upon that 
 pole. When the same magnetized needle is 
 carried further north, it dips still more, till 
 it stands perpendicular at the north mag- 
 netic pole of the earth. At the south magnetic 
 pole of the earth, the south pole of the mag- 
 net will be downwards ; but on the equator, 
 as both poles of the dipping needle are at- 
 tracted equally, but in contrary directions, 
 the needle stands horizontally. 
 
 Dip of the Horizon. (See Depression.) 
 
 Dippel's Animal Oil. An oily matter 
 obtained when horns are distilled in a retort : 
 rectified, it becomes colorless, aromatic, and 
 as volatile as ether. 
 
 DiPTEROs, or Dipteral. A temple, having, 
 a double range of columns around it. 
 
DI 
 
 DI 
 
 Dipping Needle. A magnetic needle 
 suspended so that it is capable of a vertical 
 motion, thereby being enabled to accommodate 
 itself to the earth's attraction ; though having 
 no horizontal freedom of motion, it is not 
 influenced to turn north or south. 
 
 A needle thus suspended, is usually sur- 
 rounded, as in the cut, with a circle of brass 
 or ivory, marked with degrees and minutes, 
 in order that the quantity of the dip may be 
 ascertained. 
 
 Direct. Straight, in opposition to in- 
 verse, or to oblique ; as direct proportion, a 
 direct ratio, direct rays, vision, &c. A di- 
 rect dial is one that points directly to any 
 one of the cardinal points, and is hence 
 called direct east, west, north, or south 
 dial, according to the point to which it is 
 directed. 
 
 Direction. In astronomy, the motion 
 and other phenomena of a planet, when 
 moving direct, and not retrograde in its 
 orbit. The line of direction in gunnery is 
 the direct line in which the piece is pointed. 
 In mechanics, it is the line in which a body 
 moves, or in which a force is applied. The 
 number of direction in the calendar is the 
 number of days that Septuagesima Sunday 
 falls after the 17th of January. 
 
 Direction, Quantity of. Synonymous 
 with momentum. 
 
 Directrix, or Dirigent. In geometry, 
 a term, expressing the line of motion, along 
 which a discribent line, or surface, is carried 
 in the formation of any plane or solid. 
 
 Disc. A circular flat piece of stone, wood, 
 metal, &c., of which the thickness is not 
 considered. The face of the sun, moon, and 
 other heavenly bodies, from their appearing 
 flat, are also called discs. 
 
 Discharge. In building, a term applied 
 to a brick wall or post, when trimmed up to 
 a piece of timber overloaded in its bearing, 
 in which case the wall or post is a discharge 
 to that bearing. 
 
 Discharge, Electrical. The sudden re- 
 storation to their natural condition of the 
 opposite parts of a body, the electrical fluid 
 of which is disturbed : thus, the two sur- 
 
 faces of the glass of a charged Ley den jar 
 are in different electrical conditions; when 
 these surfaces are made to unite by means of 
 a conducting body, which touches both of 
 them, their natural quiescent state is restored; 
 and a discharge takes place. 
 
 Discharger, Universal. (See Henley.) 
 Discharging Arch. An arch formed in 
 the surface of a wall, to relieve the part be- 
 neath from some part of the superincumbent 
 weight ; often used over openings. 
 
 Discharging Rod. A rod of metal, ter- 
 minated by balls, with or without a glass 
 handle, used to discharge a charged electrical 
 jar or battery. The common kind is merely 
 a bent wire, with a ball at each end, as A. 
 The better sort, or the jointed discharger, 
 is made with a glass insulating handle, and a 
 rule joint, that the wires may be made to re- 
 cede from each other, more or less, according 
 to the convenience of the operator, as at B. 
 
 Discharging Rod, Luminous. An elec- 
 trical instrument, formed of a tube of glass, 
 with an iron chain running through it, each 
 end being terminated by a brass cap or ball. 
 When a Leyden jar is discharged by this 
 rod, a brilliant spark is perceived at every 
 link of the chain, and the whole seems like 
 a continued stream of fire. 
 
 Dished Wheels. Wheels which are not 
 upright or perpendicular to the axletree ; 
 but such as are closer together below that at 
 the top, as the following : — 
 
 Dish Out, or Dishing Out. Any kind 
 of coved or groined work, formed of wooden 
 rafters, which are afterwards to receive lath 
 and plaster, therefore synonymous with cra- 
 dling. 
 
 Dissolution. The separation of a body 
 into its minute and ultimate parts or atoms. 
 
DI 
 
 DI 
 
 Dispersion. A scattering or dissipation 
 of the particles of any thing. In optics, the 
 same as divergence ; thus, the rays of light 
 are dispersed from, or diverge from a lumi- 
 nous body; and the point from which rays of 
 light diverge from the focus of a lens, or the 
 direct emanation of them from a substance 
 which is luminous, is called the point of 
 dispersion. 
 
 Distance of a Picture, or Point of 
 Distance. In drawing a picture according 
 to the rules of perspective, that line which 
 passes from the point of sight to that part 
 of the picture which is exactly opposite to it. 
 It is, therefore, the principal visual ray, or 
 the shortest line that can be drawn from the 
 eye to the perspective plane. 
 
 Distance. In painting, the degree of re- 
 moteness of the objects in a picture is divided 
 into three parts, called the remote distance, 
 the mid-distance, and the foreground, each 
 of which varies from the other in its clearness 
 of detail, arising both from drawing, size, 
 and tint. 
 
 Distemper. In painting, is the mixing up 
 and using various colors with size, the white 
 of egg, paste, gum, or other glutinous sub- 
 stance, in order that they may adhere, so as 
 not to be rubbed off when touched. Coloring, 
 by powders mixed with water only, is called 
 liming, and if with oil, oil painting, or simply 
 painting; when on a small scale distemper is 
 called body color painting. 
 
 Distillation is a process by which a 
 fluid, or portion of a fluid, is converted into 
 vapor by means of heat, and that vapor re- 
 turned into a state of fluidity by cold. (See 
 Still.) Distillation is applied to the ready 
 separation of fluids from each other, when 
 there is a chemical xinion between them, and 
 when one is more volatile than the other ; 
 thus, beer when distilled, yields a spirit 
 mixed with water, and a re-distillation of 
 that spirit renders it more pure by the ab- 
 straction of the water from it. 
 
 Ditriglyph. An interval between two 
 columns in the Doric order, admitting two 
 triglyphs. 
 
 Diverging Lines, or Rays. Such as 
 are continually increasing in their distance 
 from each other ; for example, the rays of 
 light from a candle diverge from each other 
 in every direction from the surface of the 
 flame. 
 
 Diverging Series. In algebra and arith- 
 metic, is such a series as diverges more and 
 more as it proceeds. 
 
 Dividend. (See Division.) 
 Dividers. A small pair of compasses, 
 and such as are adapted to set oflF and describe 
 mathematical figures. 
 
 Diving. The art of descending to consi- 
 derable depths under water. 
 
 Diving Bell. A machine shaped some- 
 
 what like a bell, or more usually a square 
 box of plate iron, to enable persons to descend 
 beneath the surface of water. 
 
 A represents the bell, the nearer side being 
 supposed to be removed. It is open below, 
 and is lowered into the water from a barge 
 or boat. The water does not rise far up the 
 inside, because of the air within pressing 
 upon it. A person therefore descending in 
 such a machine is in no danger of drowning, 
 but as he requires fresh air to breathe, that 
 within the bell would soon be unfit for respi- 
 ration, and the diver would die, were it not 
 for a pump which is also attached to the bell 
 by means of a flexible tube ; one or two men 
 working this pump, which is upon the prin- 
 ciple of the condensing syringe, are sufficient 
 to keep up a continued supply of air to the 
 diver. 
 
 Division. One of the principal rules of 
 arithmetic and algebra, by which is ascer- 
 tained how many times one number is con- 
 tained in another. The number to be di- 
 vided is called the dividend, the number to 
 divide it by is the divisor ; the result of the 
 division is called the quotient, and if any 
 number is left over it is called the remainder. 
 If the divisor be any number under 12, or, 
 if being another number, the sum can be done 
 in one line, it is called short division, but if 
 in several lines, long division. When num- 
 bers of a single denomination are divided it 
 constitutes simple division, while the division 
 of a quantity consisting of several denomi- 
 nations is compound division. 
 Divisor. (See Division.) 
 Diurnal. Any thuig belonging to the 
 day, in opposition to nocturnal belonging to 
 the night. The diurnal arc is the apparent 
 arc described by the planets, in consequence 
 
DO 
 
 DO 
 
 of the diurnal rotation of the earth. The 
 diurnal motion of a planet is the number of 
 degrees, minutes, &c., it passes over in 
 twenty-four hours. 
 
 Dobereiner's Lamp, or the Hydrogen 
 Lamp. An instrument for producing an in- 
 stanteous light by the action of a stream of 
 hydrogen gas on spongy platinum. 
 
 A and B are two glass vessels, fitting by a 
 ground neck tightly upon each other; the 
 upper glass terminates below by a tube C. 
 The lower vessel has a pecuharly-shaped stop 
 cock E attached to it. The lower end of 
 the tube C is to have a piece of zinc slipped 
 on it D ; this may be supported by a cork 
 below it. The vessel B is to be about three 
 parts filled with sulphuric acid and water, 
 and the vessel A, with its tube, zinc, &c. put 
 in its place. The acidulated water now acts 
 upon the zinc, producing hydrogen gas. This, 
 when a quantity has been accumulated, 
 exerts sufficient pressure upon the surface of 
 the water in B, to drive a part of it up 
 the tube C into A ; as the water becomes 
 driven up, the zinc becomes uncovered, and 
 no more gas is formed. Upon turning the 
 cock E, the gas passes out of the jet F, on 
 to the spongy platinum in G. This becomes 
 red-hot, and lights the gas, while the pres- 
 sure being removed, the water sinks out of 
 A, again covers the zinc, and produces a 
 fresh supply. H is a wire attached to the 
 cup G, to regulate the best position and dis- 
 tance of the platinum. 
 
 DociMASTic Art. The art of assaying. 
 
 Docks. Inclosed excavations or basins, 
 formed for the reception of shipping. There 
 are two descriptions of docks — wet docks and 
 graving, dry, or re^amn^ -docks. The foi- 
 mer are extensive basins, formed adjacent to 
 rivers and harbours, with which they are 
 connected by means of a lock and flood gates, 
 so that vessels may remain afloat at all times 
 of the tide. Graving docks are only of 
 sufficient size to hold one, or at most two 
 vessels at the same time. This is the kind 
 of docks in which state and other ornamental 
 barges are laid-up to defend them from the 
 tbo weather ; and also in which the hulks of 
 
 ships and other large aquatic carriages are 
 built and retained previous to launching. 
 
 Dodecagon. A geometrical figure with 12 
 equal sides and angles. 
 
 Dodecahedron. One of the five regular 
 solids or bodies. It is contained under 12 
 regular pentagonal sides, and maybe imagined 
 to consist of 12 five-angled pyramids, whose 
 apices meet in a point in the centre. 
 
 Dodecahedral crystals are often found 
 without pentagonal faces, of which the follow- 
 ing are two examples : in one, the faces are 
 rhomhoidal: in the other, triangular; the 
 whole solid consisting of two hexagonal pyra- 
 mids placed base to base. 
 
 Dodecastylos. a building having 12 co- 
 lumns in front. 
 
 Doffer. That part of a carding machine 
 which takes the cotton from the cylinder. 
 
 Dog. a piece of small machinery which 
 acts as a catch or clutch. 
 
 Dogs. Ancient fire-irons, used to rest the 
 burning logs upon. 
 
 Dog and Driver Chuck. The name of 
 a very common and exceedingly useful chuck ; 
 called also the carrier chuck, or the driver 
 and carrier. It is of two parts ; one of 
 them (the driver) fits on to the mandril by 
 a screw A, in the usual manner : — The body 
 of it is perforated with a square hole, in 
 which is a moveable elbowed iron rod D, 
 which may be held fast by the screw F. On 
 the point B is fixed the wood or metal to be 
 turned, G, and near the end of this is screwed 
 
DO 
 
 DO 
 
 the dog or carrier E ; so that when the 
 driver turns, the wood and dog turn with it. 
 
 Dog-Legged Stairs. A flight of stairs 
 built as in most ordinary houses, not straight 
 from bottom to top, nor yet built round a 
 single newell or a well ; but consisting of two 
 or more straight portions, with windins^ 
 stairs between them, so that one part of the 
 staircase appears to fold upon, or to be nearly 
 over the other. 
 
 Dog Tooth. A peculiar ornament used 
 in the Anglo-Norman buildings in the twelfth 
 century. 
 
 MPfflflWBli^lfi^^lM 
 
 
 Dome. Similar to a cupola, but of a 
 larger size. It is convex outside and con- 
 cave within, as the dome of St. Paul's, &:c. 
 Domes are common in Indian, Mahometan, 
 Moorish, and Italian buildings. 
 
 Domestic Architecture. The art of 
 designing and executing buildings for do- 
 mestic and private use, as villas, cottages, 
 farm-houses, mansions, &c. 
 
 Dominical Letter, or Sunday Letter. 
 One of the first seven letters of the alphabet, 
 used in almanacs, and annexed to the Sundays 
 of the year. It is intended to denote the 
 day of the week upon which the 1st of 
 January falls in each year. 
 
 Donjon. The principal tower of a castle, 
 usually built upon a rising ground. 
 
 Donovan's Filter. A small apparatus, 
 particularly adapted for the filtering of easily 
 vaporized and pungent smelt- 
 ing liquids. It consists of 
 two glass vessels connected 
 by a tube, made air-tight by 
 perforated corks at the union 
 of the tube and the two bot- 
 tles. The upper vessel ter- 
 minates in a conical pipe, 
 ground into the lower one, 
 and into which is stuffed a 
 piece of coarse linen. This 
 apparatus is also particularly 
 useful in filtering those li- 
 quids which are apt to ab- 
 sorb carbonic acid from the 
 atmosphere, as the solution 
 of potass, or those which are easily decom- 
 posed. 
 
 Doorway Plane. The space between 
 the actual door and the external arch in 
 front of it ; applied when the door is in a 
 deep recess, as in many of the old churches, 
 cathedrals, and castles. 
 
 Dorian. Any thing in the fine arts, after 
 the manner and style of the people of Doria. 
 
 Doric The second order of architecture, 
 divided into the ancient Doric and modern 
 Doric. In the ancient, the height of the 
 columns is but 4^ to 5^ diameters ; in the 
 modern, 8 diameters. In neither are there 
 bases to the columns, or ornaments on the 
 capitals. The frieze is decorated with tri- 
 glyphs and metopes ; the latter, either plain 
 or sculptured. The flutings of the columns 
 are 20 in number, very shallow, and without 
 any interval between them. The Parthenon, 
 at Athens, is an example of the ancient ; the 
 Colosseum, of modern Doric. 
 
 Dormer. A window set in the sloping 
 side of a roof; so called, because usually be- 
 longing to a dormitory, or sleeping room. 
 
 Dos d'Ane. The ridge on the top of stone 
 cofiins. 
 
 Dovetail. A method of fastening to- 
 gether pieces of timber, by indentations or 
 notches, resembling the tail of a dove or 
 swallow ; also a Gothic architectural orna- 
 ment, so called. 
 
 Double Affinity. (See Decomposition 
 and Attraction.) 
 
 Double Axle and Wheel. (See Crane^ 
 Chinese.) 
 
DR 
 
 DR 
 
 Double Cone. A particular kind of early 
 Gothic architectural moulding, represented 
 as follows : — (See Cone.) 
 
 Double Convex, Concave, &c. (See 
 Convex, 8^c.) 
 
 Double Decomposition. (SeeDeeompo- 
 sition.) 
 
 Double Refraction. (See Refraction.) 
 
 Double Touch. A method of making 
 magnets, so called. (See Mitchell.) 
 
 Dowels. Pins of wood or iron, used to 
 connect the joints of boards together. Floors 
 are sometimes dowled ; so are the pieces 
 forming the heads of casks, the boards of 
 wooden cisterns, &c. 
 
 Drag. A term applied to any thing bear- 
 ing down or rubbing upon another : thus, 
 a door is said to drag when its hinges are 
 so loosened that the lower edge rests on the 
 floor; a drag is also an iron shoe, upon which 
 the wheel of a carriage is made to rest when 
 descending a steep hill, in order that the 
 velocity it would acquire in moving down 
 such a declivity may be checked by the extra 
 friction occasioned by the drag. 
 
 Dragon's Blood. A brittle, dark, red 
 colored resin, imported from the East Indies, 
 the product of pterocarpus draco and dracoena 
 draco. It is insoluble in water, but soluble 
 in alcohol. The solution imparts a beautiful 
 red stain to hot marble. It dissolves in oils. 
 
 Dragon's Head and Tail. Particular 
 astronomical characters, marked ?j and Si , 
 signifying the moon's nodes : the former, 
 the dragon's head, signifying the ascending 
 node, or the point where the moon begins 
 to have north latitude ; and the other, the 
 descending node, or the commencement of 
 south latitude. 
 
 Drain. A subterraneous passage forwater. 
 
 Drapery. The dress of a figure in a 
 picture, or a statue ; while the word hang- 
 ings properly applies to the curtains of a 
 room. 
 
 Draught. In architecture, the represen- 
 tation of a building on paper, explanatory 
 of the various parts of the exterior and in- 
 terior, by means of plans, elevations, and 
 sections, drawn to a scale, by which all the 
 parts are represented in the same proportion 
 to each other, as the parts of the edifice to 
 be executed. In mechanics, the force or 
 power necessary to move any machine, as a 
 horse-mill, cart, plough, &c. In masonry, 
 it is the chiselling of a narrow margin on the 
 upper and lower edge, in order that when 
 this part is thus reduced to a proper shape | 
 
 and dimensions, the rest may be cut away 
 more easily. 
 
 Drawbridge. A wooden floor, so con- 
 structed as to be lowered or raised at pleasure. 
 The drawbridges of docks, &c., usually are 
 drawn aside horizontally, rather than up and 
 down. 
 
 Drawing. The art of representing objects 
 by means of lines or marks formed on any 
 convenient surface. 
 
 Drawing Slate. (See Black Chalk.) 
 
 Draw Plate. A steel plate, having a 
 gradation of conical holes, through which 
 wires are drawn to be reduced and elongated. 
 
 Dressed. In masonry, the trimming up 
 of rough stones, that they may have a suffi- 
 ciently smooth surface, to be placed in the 
 wall, pavement, &c., for which they are in- 
 tended. 
 
 Dressings. Those parts of an edifice 
 which are intended to set off or decorate the 
 coarser work, as the mouldings of a door- 
 way or window are its dressings ; so are also 
 the smooth quoins of a rustic wall, &c. 
 
 Drift. The tendency of any thing to force 
 itself outwards or sideways ; such as drift 
 sand, the drift of an embarkment, the drift, 
 or more properly the thrust of an arch, which 
 in each instance signifies its lateral pressure. 
 
 Drift. In mining, a passage dug imder 
 the earth, between one shaft and another. 
 
 Drill. In husbandry, a channel or small 
 furrow for the reception of seed. 
 
 Drill, Drill Bow, &c. A drill is a 
 small bitt, so formed, sharpened, and tem- 
 pered, as to adapt it to penetrate hard sub- 
 stances, such as metal, ivory, &c., fig. A. 
 It works by an alternate rotatory motion, 
 put in action by a bow of cane or steel B, 
 with a cat-gut string, which is twisted once 
 round the stock, or pulley, of the drill ; 
 sometimes a drill is attached to the common, 
 strong-made, bitt stock, when it is turned 
 round by the hand of the workman, there 
 being a pressure upon it above, C. A very 
 valuable drill is that of the Chinese, repre- 
 sented below. Fig. D. E F is a bar of 
 wood, with a hole in the centre, through 
 which the spindle G H works. A rope is 
 attached to E, passes through a hole in the 
 top of the spindle at G, and is fastened at F. 
 
DR 
 
 DU 
 
 By turning E F the rope is twisted round 
 the spindle, and E F drawn up towards G. 
 Forcing E F down with the hand, the rope 
 is suddenly untwisted, and the spindle, with 
 the drill at the end of it, is turned round. 
 With a little management it will, by the mo- 
 tion of the hands, wind itself up again, and 
 consequently the boring action may be re- 
 newed. 
 
 Drill Harrow. A small harrow used in 
 drill husbandry, to be used between the drills 
 or rows for the purpose of extirpating weeds, 
 pulverizing the earth between the plants, &c. 
 
 Drilling. The act of boring small holes 
 by means of a tool which turns round, cut- 
 ting by its point a hole through which it will 
 just pass when finished. 
 
 Drip. A projecting cornice; as for ex- 
 ample, that which belongs to a Grecian pe- 
 diment. Coping stones are often so called. 
 
 Dripstone Label. Weather Mould- 
 ing. Water Table. A large projecting 
 moulding over windows, doors, and other 
 openings, to throw oflF the wet. 
 
 Dropping Tube, or Separating Fun- 
 nel. A tube of glass, drawn to a point at 
 one end, and furnished with a bulb 
 in some part of its length, both 
 ends being open. To use it, im- 
 merse the finer end in the liquid 
 to be taken up, and thrust it down ; 
 the liquid will rise until it finds its 
 level withinside ; then closing the 
 upper end with the finger, it may 
 be conveyed away. The partial or 
 total removal of the finger occasions 
 the fluid to drop or run from the 
 lower end. Closing it again with 
 the finger, stops the flowing ; and t) 
 thus, if there are two liquids in the tube, 
 such as oil and water, the one may be sepa- 
 rated from the other. 
 
 Drops. (See Guttce.) 
 
 Drug. A general name of commodities 
 used for the purposes of medicine, dyeing, 
 tanning, and various other arts. 
 
 Druggett. a coarse, slight,woollen fabric. 
 
 Drum. A term in machinery, applied to 
 cylinders or barrels, around which endless 
 straps, chains, or cords, are passed to com- 
 municate motion or power to other ma- 
 chinery. When such cylinders or drums are 
 narrow in the direction of their axis, they 
 are caMedpullies or riggers. In architecture, 
 the drum is the centre of the Corinthian and 
 
 Composite capitals ; called also the bell, or 
 the basket. 
 
 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. It is a fungous substance, 
 or plant, which arises from the timber not 
 having been properly deprived of its sap 
 when drying ; this sap, when it gets after- 
 wards into a warm and moist situation, gives 
 rise to the fungus. The only remedy for this 
 pest of ship building is, to impregnate the 
 timber before it is used, with corrosive subli- 
 mate, a salt of iron, alum, or other antiseptic. 
 (See Kyan.) 
 
 Dry Point. A term used by the engraver 
 to designate a more or less obtusely pointed 
 needle, with which fine lines are scratched 
 upon a copper or steel plate, either as an 
 outline, previous to the use of the graver, to 
 put in delicate work where depth is not re- 
 quired ; or to touch up such parts of an 
 etching, &c. as require a little extra shade 
 given to them. 
 
 Dubbing. Making good the decayed part 
 of a wall, previous to the whole being pointed, 
 or the joints of the bricks fiUed up with fresh 
 mortar. 
 
 Ductility. The extensibility and co- 
 hesion of the particles of a metal, which en- 
 able it to be drawn out into wire without 
 breaking. 
 
 Du Fay's Electrical Hypothesis, is 
 that there are two electrical fluids, opposite 
 in their nature ; one of which he called the 
 vitreous fluid, from its becoming most appa- 
 rent by the friction of glass ; the other, the 
 resinous fluid, as being produced by resinous 
 substances. These two, assumed to be dis- 
 tinct fluids, correspond with the positive and 
 negative states of the Franklinean hypothesis 
 of a single fluid. One of them is never dis- 
 turbed, unless the other be equally so ; and, 
 consequently, when one is set at rest, the 
 other is no less quieted. The theory of there 
 being two fluids is maintained by numerous 
 philosophers, particularly the French. 
 
 Duhamel's Method of making Mag- 
 NETS. Lay the two bars of steel which are 
 to be magnetized parallel with each other, 
 as A, C, and connect their extremities by 
 two shorter bars of soft iron, D, D, so as to 
 form altogether a right-angled parallelogram. 
 Then take two parcels of bars already mag- 
 netized, B B, the separate bars of each parcel 
 being placed with their respective poles in 
 the same direction, and firmly tied together. 
 Bring the opposite poles, N, S, of these 
 bundles, into contact over the middle of one 
 of the bars, holding them rather slanting, as 
 shown in the figure ; draw them gradually 
 to the extremity of the bar, repeat this several 
 times, and pursue the same method with the 
 
 21 
 
EA 
 
 EA 
 
 other bar, when both A and C will become 
 permanent and strong magnets. 
 
 Dulcified Spirit of Nitre. Nitrous 
 ether ; used by the distillers to communicate 
 to British brandy the peculiar aroma which 
 that from France is naturally imbued with. 
 
 Dulcified Spirit of Salt. Muriatic 
 ether, or hydrochloric ether. 
 
 DuNGiN G. A term used by calico printers 
 to signify a process which cotton goods 
 undergo in the process of dyeing or printing, 
 that of immersing them in a bath made of 
 cow-dung and warm water. 
 
 DooDECiMALS, or Cross Multipli- 
 cation. A method of calculating the super- 
 ficial or solid contents of such surfaces or 
 solids as have a measurement in feet, inches, 
 and twelfths of an inch. 
 
 Duodecimo. The size of a book when 
 the sheets are folded into twelve leaves. 
 
 Duplicate. The double of any thing ; 
 a duplicate ratio is the square of a ratio. 
 
 Duplication of the Cube, is the find- 
 ing of the side of a cube, which shall be 
 double of a given cube. 
 
 Dutch Gold. An alloy of copper and 
 zinc, of no certain proportion, but containing 
 more of the former metal than exists in 
 
 Dwarf Walls. Walls of less height than 
 the story of a building ; the term is mostly 
 applied to garden walls, with or without an 
 iron railing at top ; floors, and the sides of 
 barns, granaries, &c. are often supported 
 upon dwarf walls. 
 
 Dyeing. The art of dyeing consists of 
 fixing upon cloths of various kinds, silks, 
 
 wood, marble, &c. any color that may be re- 
 quired, in such a manner as that they shall 
 not be easily altered by those agents to which 
 the cloth will most probably be exposed. 
 
 Dyer's Fuming Liquor. The proto- 
 chloride of tin, obtained by boiling 1 part of 
 tin with 2 of hydrochloric acid ; the clear 
 solution which remains, when cold, contains 
 the sadt. It is used very much by dyers to 
 change the color of numerous metallic dyes, 
 and to precipitate various vegetable extracts. 
 It is the sal jovis of old authors. 
 
 Dynamics. That part of the science of 
 mechanics which explains the laws of bodies 
 in motion. 
 
 Dynamometer. Instruments for mea- 
 suring the relative strength of men and ani- 
 mals ; and occasionally, the power of ma- 
 chinery. The following cut represents a very 
 simple dynamometer, adapted to this latter 
 purpose : — 
 
 A E B is a lever made of iron or steel, 
 having two spreading branches D A, D B, 
 and capable of being fixed on the circumfer- 
 ence of a pulley, by means of the pinching 
 screws A and B. The lever would, therefore, 
 revolve with the shaft C, were it not pre- 
 vented by the stud or pin F. A scale is sus- 
 pended from E, and according to the weights 
 requisite to be placed in the scale G, before 
 they will pull down the lever, will, of course, 
 ' indicate the power of the machinery. 
 
 The second vowel, and 
 fifth letter of the English 
 alphabet. It has many 
 sounds ; a short sound, in 
 bet; long, in revere; like 
 fl, in clerk: like u, in 
 voter : besides being fre- 
 quently silent, as in some, 
 time, &c. and joined to 
 the consonants ff and k, 
 renders them soft. It 
 also varies its sound in other languages, both 
 ancient and modern. E, standing alone, 
 signifies east. On medals, and ancient coins, 
 
 it stands for the name of any city, the name 
 of which begins with this letter. 
 
 Earth. The name of the world which we 
 inhabit. It is a planet situated at the distance 
 of 95 millions of miles from the sun, round 
 which it revolves at the rate of 1 7 miles each 
 second of time, completing its whole re- 
 volution in an elliptical orbit, in 365 days, 
 5 hours, 48 minutes, 57 seconds, while it 
 turns on its axis once in 24 hours ; that axis 
 being inclined to the axis of the ecliptic at 
 the angle of 23° and a half. Its form is that 
 of a sphere slightly compressed at the poles. 
 Its mean diameter, 7,916 miles, and its cir- 
 
EA 
 
 EC 
 
 cumference, 25,000. It is attended with 1 
 satellite, the moon. The earth's surface con- 
 tains nearly 197 millions of square miles, of 
 which, scarcely one-third is dry land, and not 
 one-tenth part inhabited by man. The popu- 
 lation of the whole earth is between 800 and 
 1,000 millions of human beings. The in- 
 terior is supposed by some persons, to be 
 hollow ; by others, a molten mass of metal, 
 or a body of fire ; others think it filled with 
 water. Man has never penetrated a mile 
 deep beneath the surface. 
 
 Earthenware. Articles made of burnt 
 or vitrified earth. 
 
 EARTHauAKE. A shaking of Certain parts 
 of the earth's surface, produced by causes 
 not perceivable by our senses. Three causes 
 have been assigned for earthquakes. First, 
 electricity, or the sudden passage of a large 
 quantity of the electric fluid through a certain 
 portion of the earth. Secondly, the for- 
 mation and sudden irruption of steam within 
 cavities under the crust of the earth. Thirdly, 
 the ignition of pyrites, detonation of gases, 
 or other violent chemical actions. 
 
 Earths. A class of chemical bodies, 
 which are tasteless, inodorous, dry, not in- 
 flammable, but little soluble in water ; not 
 readily to be fused, and of a moderate specific 
 gravity. They constitute the greater part 
 of the soils, gravel, and stones which form 
 the crust of our globe. Their number is 
 ten ; silex, alumina, magnesia, lime, barytes, 
 strontian, zircon, glucine, yttria, and tho- 
 rina, (see these names.) The four first have 
 been long known, the remainder have been 
 discovered within these few years. The 
 earths are all more or less alkaline, uniting 
 and forming salts with the acids. They were 
 formerly considered simple substances ; they 
 are now known to be composed of oxygen, 
 united to peculiar bases, and seen to form a 
 connecting link between the metals and the 
 alkalis. 
 
 Earth Table, Ground Table. That 
 course of stones in a building which is even 
 with the ground. 
 
 Earth-work. A term applied to cuttings, 
 embankments, and all other works where 
 earth is to be removed or collected together. 
 (See Embankment.) 
 
 Easel. A frame used to support a picture 
 while it is being painted. Easels are of various 
 forms and sizes, according to the size of the 
 picture, and the habits of the painter. 
 
 East. One of the principal or cardinal 
 points of the horizon, or of the compass. It 
 is that exact point in which the sun rises at 
 the time of the equinoxes. 
 
 Eau. a French word, signifying water, 
 &c. used in English with other words, for 
 several spirituous waters, particularly per- 
 fumes, as eau de Cologne. 
 
 Eau de Cologne. A celebrated odori- 
 
 ferous liquor, for the making of which there 
 are numerous receipts. One is as follows : — 
 Take of the essences of bergamot, lemon- 
 peel, lavender, and orange flower, each 
 1 ounce. Essence of cinnamon, half an ounce. 
 Spirit of rosemary, and of the spirituous 
 water of melisse, each 15 ounces. Strong 
 spirits of wine, 7i pints. Mix, let it stand 
 a fortnight, and distil by a heat not greater 
 than that of boiling water. 
 
 Eaves. Parts of the roof projecting be- 
 yond the walls of a building. 
 
 Eaves Board. Eaves Catch. Eaves 
 Lath. An arris fillet, nailed across the rafters 
 at the eaves of a roof, to raise the tiling or 
 slating in a small degree, that the wet may 
 be less inclined to drip or run down the 
 walls. 
 
 Ebb. The retiring of the tide is called the 
 ebb of the tide ; and the water left in holes 
 on the beach after the waves have retired is 
 called ebb water. 
 
 Ebony. A hard, heavy, black, valuable 
 wood, which admits of a fine gloss, the pro- 
 duce of the diosphyros ebenum. It is much 
 used by the turner and carver for small orna- 
 ments, and by the mathematical instrument 
 maker for the frames of quadrants, parallel 
 rules, &c. for which, and similar purposes, 
 it is admirably adapted, because it is but 
 little liable to warp when exposed to the sun 
 or air, and is little affected by moisture. 
 
 Ebullition. The art of boiling up by 
 heat. Fluids suffering ebullition are be- 
 coming, at the same time, converted into a 
 vapor, in consequence of the heat they have 
 imbibed, dilating and separating their par- 
 ticles. 
 
 Eccentric. Any thing out of a usual or 
 proper centre ; properly speaking, two circles, 
 one wholly or partly within the other, but 
 which have different centres. The following 
 shows various groups of eccentric circles :— 
 
 Eccentric A contrivance in mechanics, 
 whereby variation in the direction and velo- 
 city of motion is effected. An eccentric of 
 this description is usually employed in the 
 steam engine to work the valves attached to 
 the cylinder. 
 
EC 
 
 EC 
 
 No. 2 is the main shaft of the fly-wheel ; 
 upon the end of this is placed a pulley or 
 wheel eccentrically, A. As the shaft turns 
 round, it draws the wheel into the position, 
 
 D. Now recurring to No. 1, A is the axis 
 of the main shaft. B, the eccentric. C is 
 a loose collar in which B slides. As this 
 eccentric moves round, it draws C, and con- 
 sequently, all which is attached to it, back- 
 wards and forwards ; moving at the same 
 time the end F, and with it, the arm of the 
 cock or valve E. 
 
 Eccentric Chuck. A chuck of such a 
 nature, that work which is attached to it in 
 the lathe may be altered as to its centre of 
 motion, so as to produce eccentric arcs and 
 circles at the pleasure of the workman, when 
 cut with the usual turning tools. By means 
 of the eccentric chuck, the most beautiful 
 combinations of circles may be formed. The 
 illustration to Eccentric was turned by the 
 means of this chuck. 
 
 A is a round plate of metal, at the back of 
 which, in the centre of it, is a screw which 
 fits the mandril of the lathe. B is another 
 plate of metal, which slides backwards and 
 forwards over the surface of the other. It 
 moves smoothly between the two cheeks C C, 
 and is drawn more or less out of the centre 
 of A by the screw D, near the end of which 
 is the wheel E, which being graduated adapts 
 the instrument to a nice adjustment. On the 
 centre of B is a wheel of 96 teeth, F, capable 
 of being moved around its centre G, and of 
 being fixed at any place by the detent H, 
 which is made steady by the spring I. The 
 centre G is a prominent screw upon which 
 the work is to be fixed. 
 
 Eccentric Circle. In astronomy, a cir- 
 cle described from the centre of the orbit of 
 3 planet, with half the greatest axis as a 
 radius. 
 
 Eccentricity. In the orbit of a planet 
 is the difference between the centre and focvis 
 of the ellipse in which it revolves. 
 
 Echinus. That part of the egg and tongue 
 moulding which surroimds the egg ; some- 
 times also considered as synonymous with 
 ovolo. 
 
 Echo. The reverberation or reflection of 
 sound. 
 
 Eclipse. An obscuration of either the 
 sun or moon, arising from the peculiar posi- 
 tion of the earth and moon at the time. For 
 example, whenever it happens that the moon 
 in its monthly course around the earth comes 
 exactly between the earth and sun, the sha- 
 dow cast behind the moon would fall upon a 
 certain portion of the earth's surface, and 
 the inhabitants at that part would see that 
 a part of the sun's face or disc would be ob- 
 scured by the interposition of the moon, and 
 they would witness what is called a solar 
 eclipse ; and the number of digits seen to be 
 eclipsed would be according to the position 
 of the observer, whether in the centre or neai 
 the edge of the shadow. If exactly in the 
 centre he would see the moon in the centre 
 of the sun's disc, with a rim of light around 
 her, which would be called an annular eclipse. 
 Those parts of the world not within the sha- 
 dow would not be affected. A lunar eclipse 
 is when the earth is between the sun and 
 moon ; and as the earth is so much larger than 
 the moon, its shadow is large enough to cover 
 her whole face ; and when situated exactly 
 between the centres of the sun and moon, a 
 total eclipse of the moon takes place ; if not 
 centrally situated, it is only a partial eclipse. 
 
 Eccentric Pump, consists of a hoUow 
 drum or cylinder of metal, D D ; in the 
 interior of which, a solid cylinder B, of 
 the same length, but of less diameter, is 
 made to revolve in water-tight axes. The 
 inner cylinder being placed so much out of 
 the centre of D D, that in its revolution, one 
 side of it touches the side of B. The surface 
 of the inner cylinder is also furnished with 
 four circular flaps, C C C C. Two rods of 
 metal slide through B, so as to open the 
 valves on one side, when the opposite valves 
 close by pressing against the case of D D. 
 The water is supplied from the well, through 
 A; it '" *hen scooped up by the opening 
 
ED 
 
 EF 
 
 valve, and conveyed by that valve to the top, 
 where, as the valve closes, the water is 
 squeezed up into the pipe E. 
 
 Eckhardt's Capstan. A capstan which 
 acts upon the same principle as the Chinese 
 crane ; (See Crane.) It is shown in the 
 following cut, and wiU be recognized as of 
 very frequent use in rope-grounds. It has 
 an advantage over the common capstan, as 
 the ratchet wheel and catch are unnecessary. 
 
 Ecliptic. A great circle in the heavens, 
 in which the sun appears to move ; but cor- 
 rectly speaking, it is that path among the 
 stars in which the orbit of the earth is 
 situated. It is in the centre of the zodiac ; 
 is inclined to the earth's axis at an angle of 
 23° 28' which is called the obliquity of the 
 ecliptic : as depicted on an artificial terrestrial 
 globe, it crosses the equator at two opposite 
 points, that is, at the beginning of Aries, 
 and of Libra. It has marked upon it the 
 signs of the zodiac, with the degrees of each. 
 
 Edge. A narrow angle, made by the union 
 of two planes or surfaces ; also, the narrow 
 side of a very thin rectangular prism ; thus, 
 we say the edge of a tabular crystal, the edge 
 of a door, of a board, &c. 
 
 Edge, Railway. A certain description of 
 roadway, in which the carriages run upon 
 rails, or the edges of rails, as in ordinary 
 railroads; the term being used in distinction 
 to such roads as are made of flat blocks or 
 trams. In the latter case, the carriages can 
 run in any direction; but when between rails, 
 they are confined to a certain course. The 
 friction also of rails is much less, and they 
 are not so liable to be covered with stones 
 and other impediments. 
 
 Edge Tools. Such as cut by chipping or 
 shaving away, as the axe, chisel, plane, &c. 
 
 Eduction Pipe. In steam engines, that 
 pipe in which the expended steam escapes ; 
 in pumps it is that pipe by which the water 
 r£dsed is led away, or in which it is forced up. 
 Edulcorate. A cleansing of any thing 
 by means of copious washing with water, and 
 subsequent filtering. 
 
 Effect. That which is produced by an 
 operating cause. In works of art it is used 
 to indicate the appearance that is produced, 
 or is the result of their execution ; or the sen- 
 sation with which it aiFects the spectator. 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 
 every other source of loss. 
 
 Effection, denotes the geometrical con- 
 struction of a proposition. It is also used in 
 reference to problems, which, when they are 
 deducible from, or founded upon some gene- 
 ral propositions are called the geometrical 
 effections of them. 
 
 Efficient Cause. That which produces 
 an effect. 
 
 Efficient. In arithmetic, the same as 
 factor. (See Factor.) 
 
 Effluvium. A subtile vapour, which es- 
 capes from most substances, and which is 
 perceived only by the scent it yields. 
 
 Effervescence. The commotion pro- 
 duced in fluids by some parts of the mass 
 suddenly taking the elastic form, and escaping 
 in numerous bubbles. 
 
 Effigy. Effigies. In painting, resem- 
 blance, image, representation, or portrait of a 
 person. 
 
 Efflorescence. A term applied in che- 
 mistry to the crystals of certain salts, which, 
 on exposure to the air, part with a portion 
 of their water, and crumble down into a 
 white powder. 
 
 Effluent. Flowing from ; running out. 
 
 Efflux. A flowing out. 
 
 Effort. The force with which a body in 
 
 motion tends to produce an efiect, whether 
 
 the effect be really produced or impeded by 
 
 any obstacle which intervenes. 
 
 Egg and Tongue, or Ball and Arrow 
 Ornament, consists of oval and arrow-, 
 shaped bodies, placed in juxta-position along 
 a moulding. It is one of the boldest, most 
 elegant, and common decorations of classical 
 buildings. No other shows so strong a con- 
 trast between its members, or gives so fine 
 an eff"ect of light and shade. It is slightly 
 varied to suit the style which it embellishes, 
 whether Grecian, Roman, or Elizabethan. 
 
 
EL 
 
 EL 
 
 Egg Cement. Mix the white of eggs with 
 
 quick lime powdered, to the consistency of 
 
 a thin paste, and apply it to broken china, 
 
 glass, &c. the pieces of which it will unite 
 
 with considerable strength. 
 
 Egg Stand. An electrical apparatus for 
 
 the convenience of supporting eggs or oranges, 
 
 when a shock is to be passed through them, 
 
 whereby they are rendered 
 
 beautifully luminous. The 
 
 foot stand supports two 
 
 uprights, joined by a bar 
 
 at top, through which a 
 
 wire terminated by a ball 
 
 passes. The eggs are sup- 
 ported upon three little 
 
 stages, which slide up and 
 
 down between the uprights. 
 
 The lower one resting on 
 
 a piece of metal. When 
 
 to be used, place the eggs 
 
 so that they touch each 
 
 other, and slide down the 
 
 upper wire till it bears 
 
 upon the upper egg ; then pass the shock of 
 
 a Ley den jar through them. 
 Egg Varnish. (See Glaire.) 
 Elai'dic Acid. When elaidine has potass 
 added to it, it yields a peculiar fatty acid, 
 called the elaidic acid. 
 
 Elaidine. A solid substance, formed by 
 shaking olive oil, mixed with 3 per cent, of 
 nitrous, and 9 of nitric acid ; after resting an 
 hour it becomes concrete, or is converted into 
 elaidine. 
 
 Elaiodic Acid. A peculiar acid, obtained 
 from castor oil. 
 
 Elaine. The thin oil contained in tallow 
 and other fats, oils, &c. It may be procured 
 as follows : — Press taUow between some 
 pieces of blotting paper, the elaine will soak 
 into it ; then by taking away the rest of the 
 tallow, and soaking the paper in warm water, 
 the elaine will float upon the surface, from 
 which it may be collected, by skimming it 
 off, or by means of a dropping tube. 
 
 Elasticity. The property which nume- 
 rous bodies have of yielding to a certain 
 force, and afterwards of recovering their 
 original shape. 
 
 Elastic Bitumen, or Mineral Ca- 
 outchouc. A peculiar mineral, found only 
 near Castleton, in Derbyshire, and at Mon- 
 trelais, in France. 
 
 Elastic Curve. The curve formed by 
 any elastic body, when fixed by one end, the 
 rest of the body projecting horizontally, till 
 the other end is loaded with a weight, when 
 it would be bent into an elastic curve. 
 
 Elastic Fluids, are those which are 
 possessed of an elastic property, as air," 
 steam, &c. 
 
 Elastic Gum. Indian rubber, or ca- 
 outchouc. 
 
 Elatin. The active principle of elaterium, 
 or squirting cucumber. 
 
 Elbow. An abrupt turn in a river, or in 
 a piece of wood or iron-work ; often thus 
 made to strengthen adjoining surfaces, the 
 elbow-iron, &c. being screwed to each. 
 
 Elbows of a Window. The two flanks 
 of panelled-work, one under each internal 
 shutter. 
 
 Elective Affinity. The apparent pre- 
 ference which chemical substances show to 
 certain others when combining with them ; 
 for example, sulphuric acid will unite with 
 most of the metals, but will leave any of the 
 rest to unite itself to barytes : it is therefore 
 said to have an elective affinity, that is, a 
 stronger affinity for that than any other metal. 
 
 Electrepeter. An instrument for readily 
 changing the direction of electrical currents. 
 (See Clarke, Bird, 8fc.) 
 
 Electric. AU bodies are so called when 
 they show electrical appearances upon being 
 rubbed ; or which will not permit the electrit 
 fluid to pass along them. 
 
 Electrical, or Electric. Belonging to 
 electricity. 
 
 Electrical Amalgam. (See Amalgam.) 
 
 Electrical Apparatus, consists of all 
 the machinery used to illustrate the science 
 of electricity; (for a particular description 
 of each instrument, see its substantive name, 
 as Dance, Condenser, Discharger, Leyden 
 Jar, Magic Picture, Thunder House, ^c.) 
 
 Electric Attraction and Repulsion. 
 One of the visible effects of a disturbance of 
 the electric fluid. When two bodies are ex- 
 cited or electrified in a similar manner, they 
 repel each other ; if excited so that one shall 
 be in a different electrical state to the other, 
 they will be attracted. Suspend two feathers 
 on dry silken threads, and hold to them an 
 excited glass tube, they will be attracted to 
 it at first, being in a different state; but 
 afterwards they will be repelled from it, and 
 from each other, because they are then from 
 imbibing the fluid from the glass, both elec- 
 trified similarly. 
 
 Electrical Cement, for joining together 
 the various parts of an electrical apparatus. 
 
EL 
 
 EL 
 
 Melt together 5 ounces of resin, 1 of bees- 
 wax, and 1 of red ochre. This may be em- 
 ployed in cementing the plates of metal in 
 the galvanic troughs. 
 
 Electrical Charge. The greatest quan- 
 tity of the electric fluid which any body can 
 be made to contain ; or the greatest degree 
 of disturbance which can be given to its in- 
 herent fluid. The restoration of that fluid 
 to a state of quiescence, is called the discharge 
 or shock. 
 
 Electrical Circuit. Any series of wires, 
 or other conductors, intervening between 
 the inside and outside of a charged Leyden 
 phial, whereby the jar is discharged. Every 
 thing which is to receive a shock must form 
 a part of this circuit ; and connecting the 
 outside and inside of such a jar or battery, 
 is called completing the circuit. 
 
 Electrical Configurations. The pe- 
 culiar radiating forms taken by certain pow- 
 ders when sifted upon charged electrics. 
 They may be made as follows : — Put a sheet 
 of dry glass on a piece of tin -foil spread on 
 a table, and draw over the surface of it, in 
 any fanciful device, the knob of a small 
 charged Leyden jar ; then, having ready tied 
 up in a piece of loose muslin, a mixture of 
 equal parts of sulphur and red lead, in 
 powder, sift them on the plate of glass, 
 when it will be seen that the mixed powder 
 will separate ; and while the sulphur of it 
 settles in a close line on the exact tract of the 
 knob, the red lead will arrange itself at a 
 little distance on each side, in the most beauti- 
 ful star-like ramifications. The following 
 gives but a faint idea of the effect : — 
 
 Electrical Conductors. (See Con- 
 ductors and Lightning.) 
 
 Electrical Currents. The passage of 
 the fluids from one place or object to another, 
 through conducting substances : as for ex- 
 ample, from the different sides of a charged 
 jar ; from one end of a galvanic battery 
 to the other ; along conducting wires, &c. ; or 
 when a current passes through a wire, which 
 has another wire so near to it as to be affected 
 by the passage of the fluid, the fluid which 
 actually passes along the wire is called the 
 
 primary current; and that effect or dis* 
 turbance which takes place in the approximate 
 wire, is called the secondary current. 
 
 Electrical Excitation. The power of 
 disturbing the electric fluids, so that it be- 
 comes apparent either to our senses, or by 
 the well-known effects which it produces. 
 Bodies thus influenced are said to be ex- 
 cited. 
 
 Electrical Fluid. That particular and 
 universal power, substance, or property which 
 pervades all nature, occasioning, when dis- 
 turbed, those appearances and effects, known 
 in science as electrical and galvanic ; besides 
 numerous natural phenomena, such as light- 
 ning, the aurora borealis, and perhaps the 
 whole of chemical and magnetic action. 
 Some philosophers maintain that all these 
 effects are produced by different states of the 
 same electric fluid ; {sq& Franklin.) Others, 
 believe that two electric fluids exist ; one of 
 them always disturbed when the other is, and 
 each acting in opposition to the other at all 
 times. (See Du Fay.) 
 
 Electrical Induction. The power pos- 
 sessed by an excited body in influencing other 
 bodies in the vicinity of it, without touching 
 them. 
 
 Electricity. A science which explains 
 the laws which govern the excitation, distri- 
 bution, and other phenomena of a peculiar 
 element, called the electric fluid. Electricity, 
 in its more limited acceptation, explains the 
 electric effects produced upon various bodies 
 by friction or pressure only. In its general 
 meaning, it includes also, the explanation of 
 those departments of science, called galva- 
 nism, electro-magnetism, and thermo-elec- 
 tricity. That effect, resulting from friction 
 alone, constituting a branch only of a general 
 subject, and which, for distinction sake, is 
 called common, free, or frictional electricity. 
 
 Electricity, Disguised, is when the 
 electric fluid is accumulated upon the surface 
 of a body, and yet which has but little ten- 
 dency to fly off, in consequence of that body 
 being under the influence of another electri- 
 fied body, which is near to it and insulated. 
 The lower plate of the electrophorus is an 
 example of disguised electricity. 
 
 Electricity, States of. When the elec- 
 tric fluid in any body is so disturbed as to 
 become apparent, one part of that body has 
 the fluid in a redundant state ; in the other 
 part, it is deficient, or contains less than the 
 quantity natural to it. The former, is called 
 accumulated or positive electricity ; and the 
 latter, negative. Upon the supposition of 
 two fluids, the former, is the vitrious; the 
 latter, the resinous fluid. Free or common 
 electricity is popularly divided into atmos- 
 pheric, animal, chemical, mechanical, and 
 medical, according to its effects, and the 
 particular phenomena it explains. 
 
EL 
 
 EL 
 
 Electric Light, Brush, Star, Spark. 
 The spark or stream of brightness seen when 
 a considerable quantity of the electric flmd 
 passes through any imperfect conductor. If 
 it pass into the air from a point electrified 
 positively, it resembles a irush, as B. If 
 from a negative point, a star, A. If it pass 
 in a considerable quantity, and with rapidity, 
 from one conductor to another, through the 
 air, it will put on the appearance of a spark, 
 more or less zigzag, C, and be attended by a 
 snapping noise. 
 
 Electrical Machine. Any instrument 
 adapted to collect a considerable quantity of 
 the electric fluid, as produced by friction. 
 The principal electrical machines now in use 
 are of two forms ; in one, a cylinder of glass 
 is to be excited ; in the other, a plate of 
 glass, (see Cylinder and Plate.) In either 
 case, there are one or more cushions which 
 rub against the glass ; and a prime con- 
 ductor, (see Conductor,) to collect and re- 
 tain the electric fluid given off by the glass. 
 
 Electrical Non-Conductors. (See 
 Electrics.) 
 
 Electric Poles, or Electrodes. The 
 two opposite ends of a charged electric or 
 galvanic apparatus. When the word pole 
 is used, we distinguish them by the terms 
 positive and negative; but employing the 
 term electrodes, the positive, is called the 
 anode or platinode ; the negative, the ca« 
 thode or zincode. 
 
 Electric Shock. The rapid passage of 
 a quantity of the electric fluid through any 
 substance, which occasioning a disruption of 
 some bodies, and a convulsion to others, 
 renders the term appropriate. 
 
 Electro-chemical Action. The che- 
 mical changes that take place owing to the 
 interference or agency of an electric current. 
 
 Electro-chemical Equivalents, are 
 the same, and coincide with the ordinary 
 chemical equivalents. 
 
 Electro-chemistry. That division of 
 electricity, which treats of the chemical effects 
 produced by the passage of an electric current 
 through a chemical compound. 
 
 Electrodes. The poles of a galvanic 
 battery. That pole in which the electric fluid 
 enters, is called the negative pole, or elec- 
 trode. 
 
 Electro-dynamic Cylinder, {^ct Am- 
 pere.) 
 
 Electro-dynamics. That division of the 
 ^ence of electro -magnetism, which explains 
 
 the laws of all rotations, vibrations, and 
 other motions occasioned by the mutual 
 action of the magnetic and electric fluids. 
 
 Electro-Gasometer. A small apparatus 
 for collecting and measuring the amount of 
 gas, resulting from the decomposition of 
 water by electricity. (See Bachhoffner, 
 Clarke, Sfc.) 
 
 Electrolytes. All substances susceptible 
 of direct decomposition by a passage of the 
 electric fluid through them, as water. 
 
 Electrolytic Action, or Electro- 
 lysis. Galvanic action considered in refer- 
 ence to chemical decomposition. 
 
 Electro-Magnet. A bar of iron which 
 assumes temporary magnetic properties, in 
 consequence of a current of electricity being 
 made to pass through it. It is made by 
 twisting around the bar of iron, whether 
 straight or shaped like a horse-shoe, a wire 
 covered with silk or cotton, or other non- 
 conducting material, and passing a current 
 from one pole of a galvanic battery to the 
 other, along the coil of wire. The circulation 
 of the fluid through the wire, will render the 
 bar of iron within it a temporary but powerful 
 ms^net, capable of sustaining a considerable 
 weight. It loses this power the moment the 
 connection with the battery is broken. In 
 the cut, A is the electro-magnet. B and C, 
 the weight raised. N and P, the wires from 
 the poles of the battery. 
 
 Electro-magnetic Apparatus. (See 
 Ampere, Callan, Bachhoffner, Clarke, Bar- 
 low, Sturgeon, Faraday, Marsh, 8^c.) 
 Electro-magnetic Coil. (See Callan.) 
 Electro - magnetic Coil Machine. 
 (See Coil.) 
 
 Electro-magnetic Helix. (See Helix.) 
 Electro-magnetic Machine, or En- 
 gine. A machine by which the effects of 
 electro -magnetism may be noticed or ascer- 
 tained. 
 
 Electro-magnetic Multiplier. The 
 original name of the galvanometer, an in- 
 strument for measuring the intensity of an 
 electric current. The original instrument 
 
EL 
 
 EL 
 
 was merely a mariner's compass, with a co- 
 vered wire coiled five or six times round it. 
 When an electric current is made to pass 
 along the wire, the compass -needle is driven 
 out of its usual polar direction, the north 
 end heing turned east or west, according to 
 the direction of the current. The following 
 is another, but not a more powerful form of 
 the instrument : — 
 
 A B are mercury cups, to hold the wires 
 from the poles of the battery. C the mag- 
 netic needle, with a graduated card beneath 
 it, and the coil of wire around it. 
 
 Electromotive Force. Volta supposed 
 that when two metals were in contact, a certain 
 force was in operation, tending to effect a 
 transfer of electricity from the one metal to 
 the other. To this force he gave the name 
 of electromotive. 
 
 Electro-Magnetic Sphere. (See Bar- 
 low and Sturgeon.) 
 
 Electro-Magnetism. The science which 
 explains the action of the electric fluid and 
 the magnet upon each other. 
 
 Electrometer. An instrument to mea- 
 sure the quantity and quality of the electric 
 fluid disturbed during any experiment or 
 process. Some electrometers act upon the 
 principle of electrical attraction or repulsion, 
 certain parts of them becoming divergent in 
 proportion to the intensity of the disturbance 
 of the fluid within them, such as Coulomb's 
 electrometer, the quadrant electrometer, &c. 
 Others depend for their action upon the cir- 
 cumstance that the electric fluid acquires 
 momentum in proportion to its concentration, 
 as in the balance electrometer, the medical 
 electrometer, &c. (See Balance, Coulomb, 
 Lane, Medical, <^c.) 
 
 Electro-Micrometer. Any instrument 
 adapted to measure very minute quantities of 
 electricity ; synonymous with condenser. 
 
 Electro-Momentum. The power exerted 
 by an electric current when suddenly turned 
 out of its direct course ; or, when made to 
 pass from a good conductor to one which is 
 less perfect. 
 
 Electromotive. The power of motion 
 conferred upon magnets, &c. by electrical 
 action. 
 
 Electron, or Electrum. The former 
 is the Greek — the latter, the Latin name for 
 amber, which being rubbed, shows the pro- 
 perty of attracting light substances; from 
 which word and circumstance we derive the 
 word electricity. Glass, and also gold, or an 
 
 aUoy like gold was, by the ancients, called 
 likewise electrum. 
 
 Electro - Negative and Electro- 
 positive. Those bodies which, when sub- 
 jected to the action of a galvanic current, are 
 apparently attracted to the anode, or positive 
 pole of the battery, are called electro -positive, 
 or cathions. Those attracted to the cathode, 
 are electro-negative, or anions ; they being 
 supposed to be in a contrary electrical state 
 to the pole to which they are attracted. 
 
 Electrophorus. a simple instrument, 
 which, when once excited, retains its electrical 
 energy, which it is ready to give out con- 
 tinually for a long period. It consists of two 
 plates ; the lower one may be a plate of tin, 
 ten or twelve inches in diameter, with the 
 edges turned up, so as to hold the following 
 composition when poured hot into it, forming 
 a cake, when cold, of about one-eighth, or 
 from that to a quarter of an inch thick. The 
 composition is, pitch 1 part ; asphaltum 4 
 parts; and bees' -wax 1 part; or pitch, rosin, 
 andbees'-wax in the above proportions. The 
 upper plate may be of wood, covered com- 
 pletely with tin-foil, and having a glass handle 
 to lift it by. It is two or three inches less 
 ■in diameter than the lower stand. When to 
 be used, the instrument is to be warmed, 
 the resinous plate rubbed with a piece of 
 warm flannel, and the upper plate put upon 
 it, its glass handle being previously dried. 
 Lifting up the upper plate by the handle, the 
 edge of it will give a spark; touch the upper 
 plate with the finger, and put it down again 
 on the other ; upon lifting it a second time, 
 it will give another spark, and so on for a 
 considerable period. The upper plate has 
 often a wu*e with two pith balls attached 
 to it. 
 
 Electro-Pulsations. Electric currents 
 or shocks, which pass in such rapid succession 
 between the two sides of a charged Leyden 
 jar, or between the poles of a .galvanic 
 battery, that the shocks are not to be indi- 
 vidually distinguished. 
 
 Electroscope. Any instrument to indi- 
 cate the disturbance of the electric fluids; 
 but not of sufiicient accuracy to show the 
 precise amount of that disturbance, such as 
 Bennett's gold-leaf electroscope and Saus- 
 seur's pith ball ditto. 
 
 Electrotype. A method of taking re- 
 verse fac-similes of medals, coins, copper- 
 z 
 
 22 
 
EL 
 
 £L 
 
 plates, seals, &c. by means of the power 
 which voltaic electricity has of decomposing 
 metallic salts. A piece of zinc is soldered 
 at one end of a wire, and the medal, seal, &c. 
 (if a seal, or other non-metallic body, it 
 must be previously covered with black-lead,) 
 at the other end, and then the medal im- 
 mersed in a saturated solution of copper, and 
 the zinc end in acidulated water, there being 
 some membrane or other porous substance 
 between the two solutions. This being al- 
 together a galvanic circle, decomposition of 
 the sulphate of copper will take place, and 
 metallic copper be deposited on the medal ; 
 after some hours the deposit will be thick 
 enough to remove, and will be found an 
 exact reverse impression of the medal. The 
 following cut shows three forms of appa- 
 ratus: — 
 
 In No. 1, A is a jeUy pot. B a porous 
 tube within it. C is the wire, with a bar of 
 zinc inside the tube B, and the lower end 
 bent, holding the medal D upon it. E is a 
 shelf surrounding the tube B, to hold crystals 
 of sulphate of copper. No. 2 is a square 
 wooden box, with a division of plaster of 
 Paris across it. No. 3 is a glass jar, holding 
 a copper-plate to be copied, and also another 
 copper -plate ; when these are connected with 
 the poles of a galvanic battery, one of the 
 copper-plates will be dissolved and deposited 
 on the other. 
 
 Elements. The name assigned to those 
 simple substances, of which, by combination, 
 all bodies are supposed to be formed ; or in 
 other words, elements are those bodies which 
 have never yet been decomposed, and which, 
 are therefore, supposed to be simple bodies. 
 They are all the metals, supposing the earths 
 to have metallic bases, azote, bromine, car- 
 bon, chlorine, fluorine, hydrogen, iodine, 
 oxygen, phosphorus, and sulphur. 
 
 Elements. In geometry, denote inde- 
 finitely small portions of curves, surfaces, 
 and solids. 
 
 Elemi. a resin which exudes from the 
 amyris elemifera, a tree of South America. 
 It is yellow, comes in small lumps, is strongly 
 aromatic, and of a spicy taste. It is used by 
 the varnish maker, and in making lacquer. 
 
 Elemine. The crystalline and purified 
 resin of elemi. 
 
 Elevation. The altitude or height of any 
 thing. The elevation of the equator, in as- 
 tronomy, is an arc of the meridian, less than 
 
 a quadrant, intercepted between the equator 
 and the horizon of the place. The elevation 
 of the pole, or of a star, is the distance be- 
 tween the pole or the star, and the horizon. 
 
 Elevation. The front of a structure j 
 also a geometrical drawing of it, no regard 
 being had to perspective. 
 
 Elgin Marbles. A series of ancient 
 sculptured marbles, named after Thomas, 
 Earl of Elgin, by whom they were purchased 
 and brought to this country, and deposited 
 in the British Museum. They axe parts 
 of the celebrated Temple of Minerva, called 
 the Parthenon, and of other buildings, si- 
 tuated on the Acropolis, at Athens. 
 
 Elimination. In algebra, any operation 
 by means of which all the unknown quan- 
 tities, except one, are exterminated out of an 
 equation, whence the value of that one be- 
 comes determined, and hence by substitution 
 the value of all the rest. 
 
 ELiauATioN. 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 tincture extracted from many 
 ingredients, whereas a simple tincture is ex- 
 tracted from only one. 
 
 Elixir, Universal. An object endeavoured 
 to be discovered by the alchemists was to 
 find an universal elixir or a medicine that 
 would cure all diseases. 
 
 Ellagic Acid. A substance produced 
 along with gaUic acid, by the exposure of 
 moistened galls to air. It is insoluble in 
 boiling water ; therefore the gallic acid may 
 be washed away from a solution of gaUs, and 
 the ellagic acid remain. 
 
 Ellipse. Ellipsis, or Oval. In geo- 
 metry, a conic section formed by cutting a 
 cone entirely through the curved surface, r,ot 
 parallel to the base ; so that the ellipsis, like 
 the circle, is a curve that returns into itself, 
 and completely incloses a space. 
 
 Ellipsoid. A solid formed by revolving 
 an ellipsis on its axis ; if revolving on its 
 longest axis, it would be an oblong ellipsoid ; 
 if on its shortest, an oblate. 
 
 Ellipsograph. (See Trammel. 
 
 Elm. a tough, pliable kind of wood, the 
 produce of the ulmus campestris tree, and 
 other species of the same family, indigenous 
 to England. It is hard, does not easily split 
 with the driving of nails and spikes ; is very 
 perishable when placed purtly in and partly 
 
EL 
 
 EN 
 
 out of the ground ; but is very durable if 
 kept dry. It is used for mill-work, Windsor 
 chairs, coffins, water-pipes, and axletrees. 
 When stained, it much resembles mahogany. 
 Elongation. A lengthening. In astro- 
 nomy, it is the angle under which we see a 
 planet from the sun ; that is, the angle formed 
 by two lines drawn from the earth to the sun, 
 and to the planet. In the following cut, the 
 angle formed by the dotted lines on the one 
 side of the sun, A B, B C, show an angle of 
 28 20', which is the greatest elongation of the 
 planet Mercury; and the lower lines, C B, 
 D B, mark 47° 48', or the greatest elongation 
 of Venus : — 
 
 f. 
 
 Elydortc Painting. A method of paint- 
 ing in a vehicle composed of oil and water, 
 whereby the solidity of oil painting, and the 
 freshness and transparency of water colors 
 are combined. The process may be described 
 as painting in oil colors (using only poppy 
 oil,) under water, drying the painting after- 
 wards by a gentle heat, water being left for 
 some time previously floating upon it. This 
 style has been used only for very small 
 pictures, such as miniatures. 
 
 Embalming. A process by which animal 
 bodies are preserved, by means of impreg- 
 nating them with resinous and balsamic sub- 
 stances. 
 
 Embankment. A continued mound of 
 earth, thrown up to defend low lands from 
 the encroachments of the sea, for the forming 
 of roads over valleys, the raising of terraces, 
 confining the stream of a canal, &c. 
 
 Embattled. Provided with battlements. 
 
 Embellishment. Decorations ; some- 
 thing added to another ornament, yet of such 
 a nature that it may be removed without in- 
 jury, and therefore distinguishable from or- 
 nament. Thus panelling to a wainscot is an 
 ornament to it, but a mirror hung against it 
 an embellishment. The mouldings in a 
 building are ornaments ; the statues are em- 
 bellishments. 
 
 Embolus. In mechanics, any thing in- 
 serted and acting in another, as the sucker of 
 a pump, the piston of a steam engine, &c. 
 
 Embossing. The art of forming work in 
 relief, whether it be cast, moulded, or cut with 
 tools. According as it is raised little or 
 much above the general surface, it is said to 
 be in low, mean, or high relief. 
 
 Embossed. Adorned with bosses or raised 
 figures. 
 
 Embrasure. One of the openings of a 
 battlement, through which archers may shoot 
 or cannons be pointed. (See Battlement.) 
 Also long narrow openings in a wall, splayed 
 inwards, for the same purpose. 
 
 Embroidery. The enriching of cloth, 
 stuff, or muslin, by figures worked thereon 
 with a needle, with thread of gold, silver, 
 silk, or cotton. 
 
 Emerald. A green precious stone. It is 
 composed of silex, alumine, and carbonate 
 of lime ; and its color is produced by chro- 
 mium. Emeralds are now chiefly procured 
 from Peru. 
 
 Emergent Year. The first year of any 
 particular era. 
 
 Emersion. In astronomy, is the re- 
 appearance of the sun, moon, or planet, aftei 
 having been eclipsed. It is also used some- 
 times to denote the re-appearance of a star, 
 which has been hid by the sun's rays. Emer- 
 sion, in physics, denotes the rising of a solid 
 body above the surface of a fluid in which it 
 floats. 
 
 Emery. A hard mineral, of a dark grey 
 color. The best is obtained from the island 
 of Naxos, in the Mediterranean. The extreme 
 hardness of this substance has caused it to be 
 employed in vaiious arts, such as polishing 
 precious stones, grinding glass, for brighten- 
 ing and cleaning iron utensils, and generally 
 as a grinding and polishing powder. 
 
 Emetine. The peculiar principle of ipe- 
 cacuhana root. 
 
 Eminential Equation. A term used by 
 some authors for a certain assumed equation, 
 which involves in itself several particular 
 equations. 
 
 Empyreal Air. A name given by Scheele 
 to oxygen. 
 
 Empyreuma. a term implying a peculiar 
 odour, derived from the overheating of mat- 
 ters under the process of distillation, or when 
 otherwise scorched. 
 
 Emulsion. A principle very similar to, but 
 not identical with albumen, possessed by all 
 seeds which form an emulsion with water, 
 such as almonds. 
 
 Enamel. The art of painting with colors 
 on gold or copper, &c. which being burnt 
 are changed into a kind of glass. The most 
 familiar examples of enamel painting is the 
 white surface and black figures on watch and 
 clock faces or dials. 
 
 Enamelled Cards. Card^ which are co- 
 vered on one side with a coating of white lead 
 and size, and when dry passed between highly 
 polished steel rollers to give them the re- 
 quisite gloss. 
 
 Enamels. Colors or compounds, which 
 when heated to a certain degree becom* 
 changed into a kind of glass of a certam 
 
EN 
 
 EN 
 
 color, according to the ingredients contained 
 in the compound. The enamel which is the 
 simplest, and combines with all others, is an 
 oxyde made by calcining together about 30 
 parts of tin to 100 of lead — this is called 
 calcine. To every 4 parts of this, add 4 parts 
 sand, and 1 of sea salt, and melt them toge- 
 ther — this should be perfectly white. A blue 
 color is given by a very little oxyde of cobalt ; 
 a yellow by the sulphate of silver, or with 
 more certainty by equal parts of white lead 
 and white oxyde of antimony, fused with sal 
 ainmoniac ; a. green by the deutoxyde of cop- 
 per, or still better by the oxyde of chrome ; 
 red by the protoxyde of copper ; black by 
 the protoxyde of iron ; and violet by the 
 peroxyde of manganese. 
 
 Encarpi. Synonymous with festoons. 
 
 Encaustic Painting. A manner of paint- 
 ing which is executed by means of fire. It 
 is an art, practised by the ancients, the me- 
 thod not being now understood. It appears 
 to have been executed by pencils made of 
 wax colored, which were laid on the picture 
 by keeping the wax pencils warm by the 
 aid of a fire close to the artist's hand ; the 
 blending of the colors being eifterwards ac- 
 compHshed by similar means. 
 
 Enchased. Ornamented with figures, 
 scroll-work, &c. in low relief; such orna- 
 ments being carved with a tool, and not cast. 
 
 Endeca on. (See Undecagon.) 
 
 Endless Chain, Rope, &c. One of 
 which the two ends are joined together, 
 forming a loop or hoop ; as we see in the 
 lathe band, the spinning-wheel, and in very 
 numerous machines, where a rotatory motion 
 is continued from one wheel or axis to another 
 at a distance. 
 
 Engaged Columns. Such as are partly 
 united in^ and partly detached from walls 
 and piers. 
 
 Engine. The name given to all machines 
 for producing and applying any power to a 
 particular purpose. Engines take their names 
 either from the power which puts them in 
 action, as a steam engine, a water engine ; or 
 else from the purpose to which they are 
 applied, as a pile engine, a pumping engine, 
 &c. 
 
 Engiscope. a reflecting microscope. 
 
 English Bond. (See Bond.) 
 
 English Oak. That particular species of 
 oak timber which is indigenous to English ; 
 it is the wood of the quercus robur, and is 
 much harder, tougher, and more durable than 
 that of any other species. 
 ^ Engraving. The art of depicting, by in- 
 cisions in any matter or substance, but par- 
 ticularly on plates of metal, blocks of wood, 
 hard stones, &c. for the purpose of producing 
 certam impressions from them, called prints. 
 The art of engraving is divided into various 
 branches or classes; as engraving on hard 
 
 stones for rings, seals, &c. called seal eti' 
 graving f or gem sculpture ; engraving dies, 
 for coins and medals, called die sinking. On 
 copper and steel plates, which according to 
 the particular style practised, is called line 
 engraving, etching, mezzotinto engraving, or 
 scraping, aquatint, stipple, etching on stone 
 and glass, wood engraving, 8fc. (See these 
 words for each process.) 
 
 Engraver's Cushion, is used to sup- 
 port the plate or block of wood, upon which 
 any engraving is being executed. Cushions 
 are of various sizes, from 3 inches to 12 in 
 circumference, and are made of a thin leather 
 case, like the covering of a cricket ball. This 
 is filled with damp sand ; the orific 
 has admitted the sand then sewed • 
 the whole put in a press. The flat 
 now assumes it will long retain. 
 
 Engraver's Globe, is a globe of glass, 
 about 6 or 8 inches in diameter, which when 
 in use is to be filled with clear water. It 
 thus becomes a powerful lens, and will col- 
 lect and concentrate the light of a candle or 
 lamp upon any work which may be in hand, 
 as may be seen in the following illustration. 
 The first surface of the globe rendering the 
 rays parallel ; the second converging them to 
 a focus. These globes are usually made with 
 a foot to them, though not necessarily so. 
 
 Enrockment. a mass of large rocks or 
 stones piled up into a solid rough wall, to re- 
 sist the force of water beating against it. 
 
 Entablature. The whole of a story of 
 a building which is above the columns, in- 
 cluding the architrave, the freize, and the 
 cornice. 
 
EP 
 
 Enneagon. a figure of nine sides and 
 angles. 
 
 Entasis. A swelling in the middle of a 
 column or baluster. 
 
 EoLiPiLE. (See ^oUpile.) 
 
 Epact. The difference in length between 
 solar and lunar time ; if reckoned in months, 
 it is called the menstrual epact ; if reckoned 
 in years, the annual epact. For example, a 
 calendar month is 31, 30, or in February 
 28 or 29 days. Suppose January 31 days, 
 and that there is a new moon on the first of 
 the month. As a lunar month is 29 days, 
 12 hours, 44', 3'', the monthly epact, or the 
 age of the moon at the end of the month 
 would be 1 day, 11 hours, 15', 57". As the 
 civil year is 365 days, 6 hours, nearly, and 
 the lunar year 354 days, 8 hours, 48', 38", 
 the annual epact will be nearly 11 days. 
 
 Epicycloid. A curve generated by a 
 point in one circle, which revolves about 
 another circle, either on the concavity or 
 convexity of its circumference. If around 
 the outer part of the circumference, it is 
 called an exterior epicycloid ; if around the 
 concavity, it is an interior epicycloid. 
 
 A is a circle, around the circumference o" 
 which B revolves, A point on the circum- 
 ference of B bears a pencil, and as B re- 
 volves, the pencil forms the curved line 
 C D E, which is the epicycloid. In the nex*^ 
 cut are shown a series or system of external 
 
 EQ 
 
 and internal epicycloids made around and 
 within the same circle. 
 
 Epicycloidal Wheel. A very beautiful 
 method of converting circular into alternate 
 motion, or alternate into circular, as shown 
 in the annexed cut. The large wheel, which 
 is toothed on the inner side, is firmly fixed 
 to a frame-work. The smaller wheel is of 
 exactly half the diameter of the other, and 
 revolves about its centre. While this revo- 
 lution of the smaller wheel is taking place, 
 any point whatever on its circumference wiU 
 describe a straight line, or will pass and re- 
 pass through a diameter of the circle once 
 during each revolution ; and thus a piston 
 rod, or other reciprocating part, may be at- 
 tached to any point on the circumference of 
 the smaller wheel. 
 
 Epigraph. An inscription- of title, de- 
 noting the use or destination of the monument 
 inscribed. Thus, the name of a buildmg, if 
 put upon it, is an epigraph. 
 
 Epistylium. The architrave, or lowest of 
 the three divisions of an entablature. 
 
 Epoch. The beginning of a period when 
 a new computation is begun. Thus, the 
 great epochs of the world are its creation, 
 the deluge, and the time of the founder of 
 certain religions, or of great events. The 
 birth of our Saviour, among the Christians ; 
 the flight of Mahomet, among the Turks and 
 Arabs ; the Olympic games, of the Greeks ; 
 the building of Rome, by the Romans, &c. 
 
 Epsom Salts. Stdphate of magnesia. 
 
 EauABLE Motion. A motion that is re- 
 gular, steady, and uniform. 
 
 EauAL. A term of relation between two 
 or more thmgs of the same magnitude, 
 quantity, or quality. 
 
 EauAL Altitudes. A correct method of 
 calculating true time. Take the altitude of 
 the Sim at any time in the forenoon, and 
 mark the time by a watch ; then wait xmtil the 
 afternoon, when the sun is foimd to have the 
 same altitude. Half the elapsed period will 
 
EQ 
 
 EQ 
 
 be the exact noon, and the watch, if necessary, 
 is to be corrected accordingly ; for example, 
 if at 10 minutes to 12 by watch, the sun on 
 any day has 60° of altitude ; and if found to 
 have the same altitude at 12 minutes past 
 12, the watch will be too fast by 1 minute ; 
 because 10 added to 12, and the same di- 
 vided by 2, gives 11, instead of 10 minutes 
 before 12, consequently the watch is to be 
 put back 1 minute, when the whole elapsed 
 time would be equally divided. 
 
 EauAL Angles. Such angles as will ex- 
 actly cover over each other ; no relation being 
 had to the length of their sides, or to the 
 distance which each may extend from the 
 angular point. 
 
 EauAL Arithmetical Ratios, are those 
 
 wherein the difference of the two less terms 
 
 is equal to the difference of the two greater. 
 
 EauAL Curvatures, are such as have 
 
 equal radii of curvature. 
 
 EauAL Figures, are those whose areas 
 are equal, whether the figures be similar or 
 not. 
 
 EauAL Geometrical Ratios, are those 
 whose least terms are similar aliquot or ali- 
 quant parts of the greater. 
 
 EauAL Solids. Such as have the same 
 capacity or solidity. 
 
 EauALiTY. In algebra, is a comparison 
 of two quantities, which are in effect equal, 
 though differently expressed or represented. 
 Equation. In algebra, is any expression 
 in which two quantities, differently repre- 
 sented, are put equal to each other, by means 
 of the sign = between them, SiS cd+ab = l2. 
 These equations receive different names, ac- 
 cording to the circumstances contained in 
 them. For example, the above is a simple 
 or single equation ; when one of the parts 
 contains a square number, it is a quadratic 
 equation, Sisa^ x ab = l2 ; ifa cube number, 
 it constitutes a cubic equation, as a^ x a^ x 
 ab = 2i; while the following, which involves 
 a fourthpower, is biquadratic, a* + a' + a^=x. 
 A literal equation contains letters only ; a 
 numeral equation has numbers attached to, 
 or forming some of the quantities. An equa- 
 tion is called binomial, if of two terms only, 
 as ir^ = 16. Determinate, if containing only 
 one unknown quantity. Indeterminate, if of 
 more than one unknown quantity. Reciprocal 
 with the sum of each pair of terms equally 
 distant from the centre one are equal, as 
 
 X^ — OCi — X^ &c. 
 
 EauATioN OF Payments. In arithmetic, 
 is the finding the time to pay at once several 
 debts, due at different times ; so as to allow 
 of a proper average of interest or discount 
 for the whole. 
 
 Equation of the Centre, is the dif- 
 ference between the true and mean place of a 
 planet, or the angles made between the true 
 and mean place. 
 
 Equation of Time, denotes the diffe- 
 rence between mean and apparent time, or 
 the reduction of the apparently unequal time ; 
 or motion of the sun or a planet to equable 
 or mean time, or motion. 
 
 Equator. A great circle of the sphere, 
 equally distant from the poles of the world. 
 It is represented in the artificial terrestrial 
 globe, by a line graduated from a first meri- 
 dian into degrees, both eastward and west- 
 ward ; which degrees, and the lines that run 
 through them to the poles, indicate the longi- 
 tude, either east or west, from the first meri- 
 dian ; while the equator itself divides the 
 earth into the northern and southern hemi- 
 sphere. The distance from the equator north- 
 wards indicating north latitude of places, and 
 southwards, south latitude. The equator is 
 also called the equinoctial line, or simply the 
 line. 
 
 Equatorial. An astronomical instrument 
 adapted to perform several useful practical 
 purposes, independent of any particular ob- 
 servatory. Two of which problems are to 
 find the meridian by one observation only ; 
 and to point to a star in full day-light though 
 not in the meridian. 
 
 The instrument is attached to a strong 
 stand, upon which it is kept perfectly erect 
 by means of the tangent screws F G H I, 
 assisted by the two spirit levels L L. The 
 lower stage E, which represents the horizon, 
 has a scale of degrees marked upon it ; and 
 
EQ 
 
 ES 
 
 firmly fixed to the centre is the upright 
 spindle, to support the rest of the instrument. 
 The next circle A B is also in degrees, and 
 perpendicular to the horizon below. The 
 next circle M N turns upon its centre, hori- 
 zontally, and also vertically, by being attached 
 to the circle below, so that it maybe adjusted 
 to the latitude and longitude of the place. 
 This circle is called the hour circle. The 
 uppermost semi-circle D is attached per- 
 pendicularly upon M N. The sights O P 
 crown the whole, and by their support gliding 
 up and down on D may be directed to any 
 angle of altitude. 
 
 Equiangular Figures. Tliose which 
 have equal angles. 
 
 EciuiCRURAL Triangle. Isosciles Tri- 
 angle. 
 
 EauiDiFFERENT. In arithmetic, is when 
 in a series of quantities there is the same 
 difference between the first and second as 
 between the second and third, third and 
 fourth, &c. 
 
 Equidistant Ordinates, are a series of 
 lines drawn across an irregular figure, the 
 area or solidity of which cannot be accurately 
 measured, unless by dividing it into several 
 parts. The lines of separation in this and 
 other cases, if parallel to each other, and at 
 like distances, are called equidistant ordi- 
 nates. 
 
 Equilateral. Having equal sides. Of 
 such figures some have also equal angles ; as 
 an equilateral triangle, A; a square, B, &c.; 
 others, though their sides may be equal, may 
 vary as to their angles, as a rhombus, C. 
 
 Equilibrium. A state of quietude, arising 
 from any thing being equally balanced on 
 different sides ; as for example, scales equally 
 weighted, an object balanced upon a point 
 or edge, &c. ; also, the term is applied when 
 acted upon by two opposite and equal forces, 
 which neutralize each other, as a boat rowed 
 up a stream at the rate of four miles an 
 hour, while it is carried in the opposite di- 
 rection by the stream four miles an hour, 
 would be at rest, or in a state of equilibrium. 
 
 Equinoctial Colure. That great circle 
 which passes from the poles of the world 
 through the equinoctial points. 
 
 Equinoctial Dial, is one whose plane 
 is parallel to the equator. The properties of 
 this dial are that the hour lines are all equally 
 distant from each other, quite round the cir- 
 cumference of a circle. The gnomon or style, 
 is a straight pin or wire, set up in the middle 
 of the circle, perpendicular to the plane of 
 the dial, &c. The sun shines upon the upper 
 
 half of the dial-plate for half the year, and 
 on the other half during the remainder of it. 
 
 Equinoctial Line. A great circle in the 
 heavens, under which the equator of the 
 earth moves ; therefore, for the sake of con- 
 venience, we consider them as identical. (See 
 Equator.) 
 
 Equinoctial Points. The two points in 
 which the equator and ecliptic cross each 
 other, one being in the first point of Aries, 
 the other in the first point of Libra ; the 
 sun is in the first of these points at the time 
 of the vernal equinox, and in the latter point 
 at the autumnal equinox. 
 
 Equinox. The time when the sun enters 
 one of the equinoctial points. There are two 
 equinoxes, the vernal, which takes place on 
 the 21st of March, and the autumnal, which 
 occurs on the 24th of September. At the 
 time of the equinoxes, both day and night 
 consist of twelve hours each — the sun rises 
 and sets at exactly six o'clock : he rises ex- 
 actly in the east, and sets exactly in the west. 
 Also, at these periods, as well as at the sol- 
 stices, true and apparent time exactly cor- 
 respond. 
 
 Equinoxes, Precession of. It is found 
 by observation, that the equinoctial points, 
 and all the other points of the ecliptic are 
 continually moving backwards, or westward ; 
 this is called the precession of the equinoxes. 
 
 Equisetic Acid. A peculiar acid, said to 
 reside in a genus of plants, called equisetum. 
 
 Equivalents, Chemical. An expression 
 used by Dr. Wollaston to designate the 
 primary proportions in which bodies unite ; 
 the numbers representing these proportions, 
 being referred to one standard substance of 
 general interest, such as oxygen or hydrogen 
 being considered as one. Equivalent, there- 
 fore, is but another term for atomic ^weight. 
 
 Equivalents, Scale of Chemical. A 
 table in which the atomic weights of all the 
 simple and numerous compound bodies are 
 arranged, so that we may see at once the 
 atomic weight of any substance, and thereby 
 infer its composition ; and also in what mamier 
 it will combine with others. 
 
 Erect Dials. Such as stand perpendicu- 
 lar to the horizon. 
 
 Error. In arithmetic, is used to denote 
 the difference between the result of any ope- 
 ration obtained by trid, and the true result 
 required by the question. The term is chiefly 
 used in the rule called position. 
 
 Error. In astronomy, is the difference 
 between the places of the heavenly bodies, as 
 determined by calculation and observation. 
 
 Srythric Acid. A peculiar acid in 
 erythrea centaurium. 
 
 Escapement. The part of a clock or 
 watch movement which receives the force of 
 the spring or weight, to give motion to tlie 
 pendulum or balance. Escapements are of 
 
ES 
 
 ET 
 
 various kinds ; that used in ordinary clocks 
 is as follows, and will show the general con- 
 struction : — 
 
 The wheel A, which from the peculiar shape 
 of the teeth, and from its vise, is called the 
 escapement wheel, is supposed to be con- 
 nected with the rest of the wheel-work of the 
 clock, and moved round by the weight at the 
 other end of the train. B is an arc, with a 
 pallet at each end. The point of suspension 
 of this is connected with the pendulum, and 
 as this latter vibrates, the arc B vibrates 
 also, liberating at each vibration one of the 
 teeth of the wheel. 
 
 The next cut shows the scapement of the 
 common watch. A B is called the fusee, or 
 scape (escapement) wheel, moved round by 
 the main spring. C D are two pallets moving 
 in and out between the teeth of A B. G is 
 the balance wheel, which vibrates on the top 
 of the watch : — 
 
 EscuLic Acid. An acid peculiar to the 
 3iorse chesnut. 
 
 Escutcheon. A shield of armorial bear- 
 ings. 
 
 Essence. A thin, limpid, fragrant oil, or 
 else a heavy essential oil, diluted with alcohol 
 until it becomes limpid, still however re- 
 taining its full fragrance. 
 
 Essential Oils. Such oils as are volatile, 
 and generally obtained by the distillation of 
 the herbs and seeds which afford them. They 
 are fragrant, very inflammable, soluble in a 
 very small degree in water, but in any pro- 
 portion in spirits of wine. They evaporate 
 
 at a degree of heat a little above that of 
 boiling water. They leave no oily stain on 
 paper, and are decomposed with violent in- 
 flammation by the addition of nitric or sul- 
 phuric acid. The following three kinds may 
 be obtained by expression : — Lemon, orange, 
 auid bergamot. 
 
 EsTiVAL. Belonging to summer 
 
 Estuary. An arm of the sea. 
 
 Etching. A species of engraving in which 
 the copper or other plate is not cut by a tool, 
 but eaten away by acpxafortis poured upon it. 
 The process is as follows : — Procure a clean 
 copper or steel plate ; warm it, rub a little 
 etching ground upon it — spread this smoothly 
 over the plate by dabbing it, while still hot, 
 with a ball, made of a piece of silk, tied 
 round some cotton wadding. Then hold the 
 plate, with the covered side downwards, ovei 
 a smoky flame, until it appears quite black. 
 When cold, draw upon the surface of the 
 ground with a needle, which will cut through 
 the ground, and lay bare the copper beneath 
 wherever the needle touches. Next surround 
 the plate with an edging of etching waWj 
 putty, or other similar material, and pom 
 upon the plate some diluted aquafortis : after 
 a few minutes, according to the strength of 
 the acid, bubbles will arise from the bared 
 lines ; these being brushed off two or three 
 times, the lines will be bit in sufficiently. 
 The acid, therefore, may be poured ofi^, and 
 the plate cleaned with spirits of turpentine, 
 when the design will be seen etched upon it. 
 
 Etching on Glass, is performed in 
 nearly the same manner, except that as glass 
 will not bear heat like metal, the etching 
 ground must be put on like a varnish, and 
 may consist of melted wax, or mastic varnish. 
 The fluid used for biting-in is liquid fluoric 
 acid, or else the vapor arising from a mixture 
 of powdered Derbyshire spar and sulphuric 
 acid, assisted by heat. 
 
 Etching on Stone. A species of litho- 
 graphy, by which fine-lined etchings on metal 
 are well imitated. It is performed thus :— 
 The stone being prepared with a smooth, 
 clean surface, as lithography, it is covered 
 with a coat of gum water, blackened with 
 lamp-black ; when dry, the etching is made 
 with a needle, which, scratching through the 
 ground, lays the surface of the stone bare. 
 Linseed oil is now washed over the whole ; 
 this adheres to the bare lines only, and the 
 black gum ground being washed off" as soon 
 as the oil is dry, leaves that to receive the 
 ink used in printing. 
 
 Etching Ground. A varnish to cover or 
 form a ground upon copper and other plates, 
 previous to the etching needle tracing the 
 design upon them. It may be made thus : — 
 Melt together 2 ounces of white wax, 2 
 ounces of asphaltum, and half an ounce each 
 of black pitch and Burgundy pitch ; let the 
 
EV 
 
 EX 
 
 vhole boil ten or twelve minutes, then pour 
 it into cold water and mould it up into balls 
 with the hands. 
 
 Etching Liquid. (See Biting-In.) 
 
 Etching Needle. Any fine pointed, 
 stout needle, used for scratching through an 
 etching ground previous to biting-in 
 
 Ether. The name of a class of very light, 
 volatile, inflammable, and fragrant spirituous 
 liquids, obtained by distilling in a glass re- 
 tort, a mixture of alcohol with almost any 
 Strong acid. According to the acid employed, 
 so is the name, and in some degree the nature 
 of the ether. 
 
 Ether. Ethereal. Radiant or impon- 
 derable matter. (See jEther.) 
 
 Etherine. a combination of carbon and 
 hydrogen, in the proportion of 2 volumns of 
 carbon vapor to 4 of hydrogen, to form one 
 volumn of etherine. 
 
 Etherifioation. The process by which 
 an acid and alcohol are so united together as 
 to form ether. 
 
 Ethero^Sulphuric Acid. {See Ethionic 
 Acid.) 
 
 Ethionic Acid. An oleaginous liquid, 
 fbimed when the vapor of anhydrous sul- 
 phuric acid is slowly introduced into pure 
 alcohol, kept at a low temperature. 
 
 Ethiops. An old name given to numerous 
 blcck metallic preparations. 
 
 Ethiop's Mineral. The black sulphuret 
 of mercury.. 
 
 Ethuil, or Ethyle. The supposed com- 
 pound inflammable basis of ether. 
 
 Evaporation. The process by which any 
 body is converted into and carried off in 
 vapor. Many substances evaporate naturally, 
 such as camphor, ice, water, &c. Others 
 require the application of artificial heat, as 
 mercury. 
 
 Evection. The most considerable of the 
 moon's irregularities, occasioned by the action 
 of the sun upon the moon. 
 
 Even Number. That which may be di- 
 vided by 2, without a remainder. 
 
 Evenly - even Number. That which 
 may be divided by 4, without a remainder. 
 
 EvoLENT, or Evolvent. (See Involute.) 
 
 E volute. The curve formed by the un- 
 winding of a string which has been coiled 
 around another curve. For example, let 
 A B C be a certain curve with a string coiled 
 
 from A to D. Unwind this, still keeping it 
 tight, and with a pencil attached to the end, 
 describe the course this end of the string 
 will take during the unwinding, and the curve 
 thus formed will be the evolute. Thus, 
 D E F G will be the evolute of A B C. 
 
 EucHLORiNE. Protoxyde of chlorine. 
 
 Eudiometer. An instrument adapted to 
 the examination of the gases, atmospherio 
 air, &c. It is of two forms ; in one, it con 
 sists merely of a graduated tube, in which 
 the air to be examined is placed, and a glass 
 bottle (as in Dr. Hope's,) attached to it, E. 
 In Dr. Henry's, an Indian rubber bottle is 
 substituted for that of glass, as at D. The 
 other form of the instrument supposes that 
 the gases are to be inflamed by the electric 
 spark ; they therefore are furnished vnth two 
 wires nearly meeting each other, within the 
 tube. A is such an one as used by Volta. 
 B is that of Sir H. Davy ; and C the con- 
 trivance of Dr. Ure. 
 
 EuDiOMETRY, The art of analyzing the 
 respirable properties of any air, by ascer- 
 taining the quantity of oxygen contained in 
 it ; or generally, the analysis and purification 
 of gases comes under the term eudiometry. 
 
 EuPHORBiUM. A gum resin, exuding from 
 a large shrub of the East Indies, called 
 euphorbia officinalis. 
 
 EuPiON. A tasteless, colorless, inflam- 
 mable, inodorous, greasy, limpid liquid, ob- 
 tained from animal tar ; or that produced 
 by the distillation of horn, bones, &c. 
 
 EusTYLE. Buildings are in eustyle when 
 the space between the columns is 2^ diameters, 
 which Vitruvius maintained to be the best 
 distance. 
 
 Excavation. The art of hollowing or 
 digging a cavity, either for the foundation 
 of a building, the course of a canal, &c. 
 
 Exchange. In arithmetic, is the finding 
 how much money of one country is equal to 
 a certain sum in another. 
 
 Exchange, Arbitration of, is a rule in 
 arithmetic which detenniaes tiie method of 
 
 A A 
 
 23 
 
EX 
 
 EY 
 
 remitting money to, or drawing from other 
 cotintries, in such a manner as shall be ad- 
 vcntageous to the merchant. 
 
 ExcuusioN. In astronomy. (See Elonga- 
 tion.) 
 
 Exegesis. An ancient term for findirg 
 the roots of an equation. 
 
 Exhausted Receiver. The receiver of 
 an air pump when the air has been withdrawn 
 from it by the action of the pump. 
 
 Exhausting Syringe. The same as 
 a condensing syringe would be with its valves 
 reversed, or like one of the barrels of an air 
 pump. 
 
 Expansion. That degree of increase of 
 which bodies are susceptible when acted upon 
 by heat, the imbibing of moisture, &c. "When 
 bodies expand, their specific gravity decreases 
 in proportion to the expansion of them, ex- 
 cept in the case of their imbibing moisture, 
 when the quantity of moisture which fills the 
 pores must of course be allowed for, that 
 being an adjunct, and forming no part of the 
 body itself. The instruments by which ex- 
 pansion is measured are called thermometers, 
 pyrometers, hygrometers, &c. 
 
 Expansive Engine. A steam engine in 
 which the supply of steam is cut off, previous 
 to the stroke being complete ; the rest of 
 the power necessary being supplied by the 
 expansive power of the steam already ad- 
 mitted. In high pressure engines the whole 
 force is derived from the expansion of the 
 steam. 
 
 Experiment. A trial or practical proof 
 of any thing. Experiments are said to be 
 mechanical, chemical, electrical, magnetic, 
 &c. according to the subject to which they 
 more immediately belong. 
 
 Experimental Philosophy. A general 
 exposition of all those sciences which can be 
 illustrated by experiment. Such are che- 
 mistry, hydrostatics, hydraulics, pneumatics, 
 acoustics, optics, electricity in its numerous 
 forms, astronomy, heat, &c. forming alto- 
 gether one department oi natural philosophy; 
 the other department being natural history. 
 (See Science.) 
 
 Explorator. a contrivance invented by 
 Beccaria, consisting of a wire, whose insu- 
 lated ends, provided with knobs of tin, are 
 fastened to a pole over the chimney, or to the 
 top of a tree. From tliis wire, another leads 
 into a chamber, through a glass tube covered 
 with 8ealing-w«ix, communicating in the 
 chamber with an electrometer, by which the 
 electricity of the air may be daily observed. 
 
 Explosion. The breaking up, scattering, 
 or destroying, by means of sudden and 
 powerful chemical detonations ; or in some 
 cases, by undue mechanical pressure. Thus, 
 we speak of the explosion of a stone by gun- 
 
 powder, the explosion of a boiler by an over- 
 pressure of steam, &c. 
 
 Exponent. The smallnumber or character 
 attached to any quantity in arithmetic or al- 
 gebra, showing that the power of it is changefl. 
 Thus 2, 3, 4, are the exponents of as, a^, a*, 
 &c. 
 
 Exponent of a Logarithm. The index 
 which stands before the logarithmic numbers, 
 as in 1-6321784, the 1 is the exponent oi 
 index. 
 
 Extension. In philosophy, one of the 
 general and essential properties of matter ; 
 the extension of a body being the quantity 
 of space which the body occupies, the ex- 
 tremities of which limit or circumscribe 
 that body. It is otherwise called the magni- 
 tude, size, or bulk of that body. The ex- 
 tension of a body is measured in three different 
 ways, in length, breadth, and in thickness. 
 Extension may be finite or calculable, or 
 infinite. Thus, the atmosphere is supposed 
 to extend upwards to about forty-five miles ; 
 but the extension of the universe is infinite. 
 
 Extermination. A term employed by 
 algebraists, to denote the taking away or 
 cancelling of any of the terms of an equation, 
 still retaining the same value of the whole. 
 
 External. Exterior. Terms of relation, 
 expressive of whatever is on the surface o\ 
 outside of a body, and opposed to internal 
 or interior. 
 
 External Angle. (See Angle.) 
 
 Extra Constellary Stars. Such stars 
 as have not been classed under any of the 
 constellations. 
 
 Extraction of Roots, is the finding of 
 the square, cube, and other roots of a number 
 or quantity, whether arithmetical or algebraic. 
 
 Extracts. Products obtained by soaking 
 or boiling vegetable substances in such a 
 menstruum as will dissolve a certain portion 
 of them, which portion is called the ex- 
 tractive principle. This is sometimes soluble 
 in several menstrua, sometimes only in one 
 or two. From the nature of the mf.n&truum 
 used, the extract is either aqtceous, oily, or 
 spirituous. Spirituous extracts are often 
 called essences. Extracts are generally thicker, 
 and contam, proportionably, a much greater 
 quantity of vegetable extract than infusions 
 or decoctions. 
 
 ExTRADOS. The exterior curve of an arch. 
 
 Eye. In architecture, a name applied to 
 several circular parts and apertures, par- 
 ticularly the central circle of the Ionic volute ; 
 the circular or oval window in a pediment ; 
 a small sky-light in a roof ; and an aperture 
 in the summit of a cupola. The term, bull's 
 eye, is also used in a similar manner, par- 
 ticularly when applied to the holes in the deck 
 of a ship, to admit light to the cabin. 
 
FA 
 
 FA 
 
 The sixth English letter : 
 it is of rather uncertain 
 sound, passing readily into 
 V, h, b, and j9. It is a semi- 
 vowel, and one which has 
 what the Germans call a 
 blowing sound. It may be 
 produced by putting the 
 upper teeth against the 
 lower lip, and trying to hiss. This aspiration 
 may be more or less powerful. The character 
 is said to have been introduced by the Eolians, 
 who represented the sound by two r (gammas) 
 placed one above the other. The Romans 
 often used the F, inverted, instead of V ; with 
 them it indicated the number of 40, and with 
 a dash over it, 40,000. In engravings, or 
 pictures, stands for/ec?Y, (made.) On medals, 
 it stands for Felius, Felix, Fahhis, Fausius, 
 Sfc. F, with merchants, signifies folioy or 
 fiat. It also is the name of the fourth note 
 in music. 
 
 Fabric. The structure or construction of 
 any thing, particularly of a building. 
 
 Facade. The general face or front which 
 any considerable building presents towards a 
 street, court, or garden. 
 
 Face. The curved part of a cogged wheel 
 which gives the impulse to another wheel. 
 
 Face Guard. A mask to defend the face 
 and eyes from accident, in various chemical 
 and manufacturing processes. It is usually 
 a frame made to fit the face, and formed of 
 wire-gauze. 
 
 Face of a Stone. The surface intended 
 for the front of the work. 
 
 Facets. In jewellery and crystallography, 
 the flat surfaces which boimd the angles of 
 crystals, or into which a precious stone is 
 cut ; for example, a diamond cut so as to 
 have numerous faces, is called facetted ; but 
 if ground with a uniform globular surface, it 
 is called rose cut. 
 
 Facia, or Fascia. Any flat surface in a 
 building ; as for example, the plain flat part 
 over a shop front, upon which the trade or 
 name of the owner is painted. The bands 
 into which the architrave of classical buildings 
 is sometimes divided, are called so many fascia. 
 
 Facing. A small thickness of a better 
 material placed over any thing, either to im- 
 prove its appearance or to add to its strength ; 
 the brick or stone-woi-k on the sides of a 
 canal, a rampart, &c. is a facing 5 the fine 
 plaster and stucco on walls ; the panelling, 
 and other smoothed wood-work on rough 
 timbers, and other similar coarse substances. 
 
 Factors, or Multipliers, In arithmetic, 
 are the multiplicand and multiplier, or those 
 numbers, by the multiplication of which, 
 another number is produced : thus, 5 and 8 
 are factors of 40, because the factttm or pro- 
 duct of them is 40 ; so also a and y are the 
 factors of ay. 
 
 Factum. The result or product of multi- 
 plying two or more factors together, as 35 is 
 the factum or product of 5 and 7. 
 
 FacuL/E. A name given by some astro- 
 nomers to such spots of the sun's surface as 
 are brighter than the rest, as maculce denote 
 those spots which are less bright. 
 
 Faggot. Bars of iron bound together for 
 re-manufacture; also abundle of sticksforfuel. 
 
 Fahrenheit's Thermometer, is that 
 arrangement of the scale of the instrument, 
 in which the space between the freezing and 
 the boiling points of water, under a medium 
 pressure of the atmosphere, is divided into 
 180 parts or degrees ; the freezing being 
 marked 32°, and the boiling, 212°, This 
 scale was adopted by Fahrenheit, because he 
 supposed, erroneously, that 32 of those di- 
 visions, below the freezing point of water, 
 which was therefore nought (0) on his scale, 
 was the zero, or greatest degree of cold. 
 
 Faints. The impure spirit wliich comes 
 over last, during the process of distillation. 
 It being loaded with the impurities of all 
 which the still at first held, it is very fetid 
 and disagreeable. 
 
 Fairy Ring. A phenomenon frequent in 
 the fields, formerly supposed to be traced by 
 the fairies in their dances. There are two 
 kinds ; one of about seven yards in diameter, 
 containing a round bare path, a foot broad, 
 with green grass in the middle of it. The 
 other is of different sizes, encompassed with 
 a circumference of grass, greener and fresher 
 than that in the middle. Some attribute 
 them to lightning ; others to a kind of fungus 
 which breaks and pulverizes the soil. 
 
 Fake. One of the circles or coils of a 
 rope when coiled up. 
 
 Falcated. Scymitar-shaped ; a term ap- 
 plied to the appearance of the moon, when 
 in the first and last quarter, or as it is com- 
 monly called horned. 
 
 Falling Sluices, Such as are so con- 
 trived as to fall down of themselves, and en- 
 large the water-way, on the increase of a 
 flood in a mill-dam or river. 
 
 Falling Star. (See Meteor and Aereo- 
 lite.) 
 
 Falling Star Tube, An electrical ex- 
 periment to imitate a falling star. It is a 
 tube of glass four or five feet long, and of 
 half an inch internal diameter, similar to that 
 described under the word Aurora, but with 
 a small ball inside at both ends. When this 
 is exhausted of air, and a shock passed down 
 it, it will represent with much effect the 
 stream of light of the meteor. 
 
 False, Rule of. (See Position.) 
 
 False Roof. The part between the upper 
 ceiling and the true roof, called in ordinary 
 circumstances a cock-loft, or garret. 
 
 Fan. Any flat, light contrivance, intended 
 to catch the wind, and tliereby to occasion a 
 
FA 
 
 FA 
 
 current, either to produce coolness, to in- 
 crease the draught of a fire, or to turn a 
 machine into a certain required direction, 
 as in the small vertical wheel mostly seen 
 attached to the top of a windmill. 
 
 Fanners. Vanes or flat discs revolving 
 round a centre, so as to produce a current 
 of air ; generally used instead of a bellows 
 for forges. (See Blowing Machine.) 
 
 Fan-shaped Window. A window, con- 
 sisting of part of a circle, the frame of which 
 is cut into round notches. Such windows 
 are common in early English buildings. 
 
 Fan Tracery. A beautiful style of vault- 
 ing, in which the ribs spread out like a fan 
 from certain points at the sides of a building. 
 It was used in the Tudor buildings. Fine 
 examples are seen in Henry the Seventh's 
 Chapel,Westminster ; King's College Chapel, 
 Cambridge ; &c. 
 
 Faraday's Crucible Furnace, is thus 
 described: — Procure a black-lead crucible or 
 blue pot, about 12 inches high and 7 wide ; 
 then bore three rows of holes in it, as repre- 
 sented, five or six in each row, the holes being 
 about \^ inches in diameter in the bottom 
 row, and 1 inch in the upper two. Next 
 bind it round with stout iron or copper wire, 
 leaving a handle at each side, and cutting a 
 groove with a file around the pot to confine 
 the upper circle of wire, that it may not slip 
 down. A small, round, moveable grate of 
 plate iron, of a size to rest between the middle 
 and bottom row of holes, is all that is now 
 requisite. This being put in its place, a fire 
 may be lighted. The lower holes will supply 
 the necessary draught of air, and the vessel 
 to be heated may be placed above. 
 
 Faraday's Electro-Magnetic De- 
 composing Apparatus, is seen below ; it 
 is merely a wooden box, with a partition 
 formed of a piece of bladder, or brown paper, 
 put across it ; or else of four slips of plate 
 glass cemented into a wooden foot, with the 
 same partition, the whole being tightly boimd 
 together with string. Both sides of this 
 apparatus are to be filled with the liquid to 
 be decomposed, and the opposite poles of a 
 galvanic battery being placed in the cells, de- 
 composition readily takes place. 
 
 Faraday's Electro-Rotative Appa- 
 ratus, is of two kinds; both are represented 
 in fig. 1, and may be used together, or each 
 as a separate apparatus. A is a cup of quick- 
 silver, containing a magnet, capable of motion, 
 on a joint at the bottom of the cup, the wire 
 D dipping into the mercury in A. The wire 
 C is capable of motion around the joint at 
 top. B is a second cup filled with mercury, 
 for the end C to touch. It contains a magnet 
 fixed in the centre. "When a current of elec- 
 tricity passes from F, up the magnet and 
 mercury, along D and C, and again through 
 the mercury to the magnet in B, it finally 
 makes its exit by E. In this passage, the 
 magnet will turn round the wire in the cup 
 A, and the wire C revolve about the fixed 
 magnet in B. 
 
 Fig. 2 exhibits another form of the ro- 
 tating wire. D is a glass tube with a cork 
 at each end ; through the lower cork is 
 inserted the pole of a magnet ; through 
 the upper is a wire, terminating in a ring, 
 upon which is suspended, within the tube, a 
 moveable wire B. A little mercury is poured 
 into the tube, and a current of electricity 
 passed from one end to the other, when the 
 suspended wire will immediately rotate around 
 the pole of the magnet C. 
 
FA 
 
 FE 
 
 Faraday's Lamp Furnace, is repre- 
 sented in the margin ; it is recommended by- 
 Professor Faraday as ex- 
 tremely powerful and 
 cpnvenient. The lower 
 pjirt is a common tin box, 
 the lid of which lifts off 
 for the convenience of 
 trimming the lamp. The 
 . cover is pierced with one 
 romid hole, in which to 
 pour the oil, and four or 
 five long holes, with a raised rim to each, for 
 as many flat wicks. A wire is soldered to 
 the lid also, and bent so as to support a 
 copper tube, which, by being hung close over 
 the light, mcreases considerably the draught 
 of air, and consequently the intensity of the 
 flame. * 
 
 Faraday's Voltameter. Two instru- 
 ments of this kind were invented by Professor 
 Faraday ; one is shown in the 
 margin. It is made of a com- 
 mon glass bottle with two necks. 
 One of them, B, is for filling 
 and emptying the apparatus ; 
 the other neck has a glass tube 
 inserted into it, which tube is 
 closed at the top, and gradu- 
 ated ; the lower end dips be- 
 neath the surface of the acidu- 
 lated water in the bottle. The 
 tube A has two platina wires, 
 D, C, inserted in opposite sides, 
 and bent up,withinside the tube. 
 When the wires are made to 
 convey the electric current, the 
 water within the tube A is de- 
 composed. 
 
 The second instrument is yet more simple. 
 A is a heavy wooden foot. B is a tapering 
 tube, bent so that the end E may dip under 
 the shelf of the pneumatic trough, that the 
 gas may be collected. C and D are the two 
 wires, as before. The current is passed in 
 the same manner. 
 
 Farina. The flower of any kind of corn, 
 or starchy root, as the potato, ai-row- 
 root, &c. 
 
 Fascia. (See Facia.) 
 
 Fascia. Belts ; as those of Jupiter. 
 
 Fastigium. The same as pediment. 
 
 Fat. Animal oil, in a concrete state. Fat 
 is also a measure of capacity, differing in 
 
 different commodities. Thus, a fat of isinglass 
 is 3 or 4 cwt. A fat of wire, from 20 to 
 25 cwt. A fat of yam, 220 bundles. Fat 
 is also a term used by printers, to designate 
 such work as contains much white, and which 
 they can get over quickly. 
 
 Fata Morgana. (See Mirage.) 
 
 Fathom. A measure of six feet. 
 
 Fatty Acids. (See Acid.) 
 
 Fatuus. (See Ignis.) 
 
 Faults. In mining, are disturbances of 
 the strata, which interrupt the miner's opera- 
 tions, and put him ot fault, to discover where 
 the vein of ore, or bed of coal has been tlirown 
 by the convulsions of nature. The following 
 cut shows a fault in a coal mine, in wliich it 
 will be observed that the seam of coal is 
 considerably higher on the one side than on 
 the other : — 
 
 Feathered Shot Copper. If melted 
 copper be poured in drops into hot water, 
 the drops will harden of a round form, called 
 shot copper ; but if a constant supply of cold 
 water is kept running in, the drops will be 
 ragged, when they are said to he feathered. 
 
 Feather-Edged Boards. Such as are 
 thicker at one edge than the other. 
 
 Featherings. Foliations. Cusps, or 
 Foils. Small arcs in the tracery of Gothic 
 windows, &c. (See Foil.) 
 
 Feathers. A general name for the co- 
 vering of birds. In building, feathers are 
 any narrow slips of timber, to strengthen 
 framing, partitioning, &c. 
 
 Feeder. A cut or channel, by which a 
 stream or supply of water is brought into a 
 canal ; sometimes the stream of water itself 
 is called the feeder. 
 
 Feed Pipe. A part of the apparatus of a 
 steam engine boiler, for keeping up a regu- 
 lar supply of water, as follows : — 
 
 Suppose A to be an open pipe, connected 
 with a cistern of water above it. The water 
 would flow through A ; thence to B, by the 
 side of C, and finally through the pipe D into 
 the boiler. When the boiler has a sufficiency, 
 the stone E floats, and the rod connected 
 with it, and which passes througa a stufiing 
 box F, acts upon G, and lets do^^a the valve 
 H, whereby the passage of the water is 
 stopped. When more is wanted, the float 
 sinks, and again opens the valve at B, when 
 
FE 
 
 FE 
 
 of course the water from the cistern flows 
 again. The damper apparatus is always con- 
 
 nected with the feed pipe. It acts thus : — 
 "When the formation of steam is too rapid, 
 it presses upon the surface of the water in 
 the boiler, and drives part of it up the pipe 
 D, so as to lift the weight C, and this by 
 means of the chain I, lets down the damper 
 J, and thus the draught is decreased. 
 
 Feed Pipe of a Pump, is that which 
 extends from the well of water to the valves 
 or working barrel. 
 
 Felling. The cutting of trees close by 
 the root for the purpose of building. 
 
 Felloes. The curved pieces of wood 
 forming the rim of a carriage, cart, or other 
 wooden wheel. 
 
 Fellowship. Aruleinarithmetic,whereby 
 partnership or joint accounts are regulated ; 
 also for the just division of prize-money, 
 land, &c. 
 
 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 manu- 
 facture of hats. 
 
 Female Screw. The spiral threaded 
 cavity in which a screw works. 
 
 Fender, or Fender Piles. The timbers 
 placed in the front of a quay, wall, or other 
 work, to defend it from mjuries by vessels, 
 &c. 
 
 Feretory. A shrine, tomb, or relic box. 
 
 Ferguson's Pvrometer. A simple and 
 popular instrument, to show the extension of 
 metallic bars by heat. It will be readily 
 understood from the following cut : — 
 
 A is a solid piece of wood, which may be 
 fastened upright on any convenient foot. B 
 is a scale of degrees. C is a bar of iron to 
 be heated. "When this is in its place, it 
 presses upon the arm D, near its pivot. D 
 acts in a similar way upon the arm E, the 
 point of which traverses along the scale, 
 being kept steady by the spring F. To use 
 the instrument, put the bar, before heating 
 it, into its place, and turn the screw G one 
 way or the other, until the point of E is di- 
 rected to zero, on the scale ; then take the 
 bar out, without altering G, heat it, and put it 
 back again, when its extension will be shown 
 by the altered position of E. 
 
 Ferment, Yeast, or Balm. Tlie sub- 
 stance which when added in a small quantity 
 to vegetable or animal fluids^ tends to excite 
 fermentation. 
 
 Ferm entation. The changes which dead 
 animal, or vegetable matters spontaneously 
 undergo when subjected to warmth and 
 moisture, all arise fi*om fermentation ; and 
 according to the result and product of those 
 internal changes, so the kind of fermentation 
 is indicated. If gluten, sugar, and water 
 be mixed in certain propoi'tious, and assisted 
 by a proper degree of heat, they will pass 
 into the vinous fermentation, and a spirituous 
 liquor be the result. If gluten unduly 
 abounds, or the heat be too strong, or the 
 process too long continued, it passes into the 
 acetous fermentation, becomes sour, and 
 vinegar is formed. Many things enter at 
 once and very rapidly into the acetous fer- 
 mentation. The heat exhibited by hay-stacks 
 and similar collections of vegetable matter, 
 is produced by the bituminous fermentation ; 
 so also is the formation of peat, and 
 probably coal. Grain, when malted, be- 
 comes sweet, because of the saccharine 
 fermentation. Bread is rendered light and 
 spongy by the panary fermentation ; and 
 finally, all matter whatever, finally decays. 
 If, as in the case of animal flesh, it becomes 
 putrescent, it is because it has passed into 
 the putrefactive fermentation. 
 
 Ferretto. a substance used in coloring 
 glass ; obtained by the calcination of copper 
 and powdered brimstone, or of copper and 
 white vitriol. 
 
 Ferro-Cyanates, or more properly, 
 Ferro-Cy ANiDES. Compouuds of the ferro- 
 cyanic acid and various bases. 
 
 Ferro-Cyanic Acid. An acid of peculiar 
 properties, formed of the cyanic acid and 
 iron, which, although apparently a neutral 
 salt, yet will unite with the usual bases, and 
 form with that a class of double cyanides, 
 which are quite distinct in character from the 
 simple cyanides, formed by the action of the 
 cyanic acid. 
 
 Ferro-Cyanurets. The same as ferro- 
 cvauatea. 
 
FI 
 
 FI 
 
 Ferro-Cyanooen. a combination of cy- 
 anogen and iron, forming a proto-cyanuret 
 of iron. 
 
 Ferro-Prussiates. Another name for 
 ferro-cyanic acid. 
 
 Ferro-Prussic Acid. (See Ferro- Cyanic 
 Acid.) 
 
 Ferruginous Bodies. Those which con- 
 tain iron. 
 
 Ferruretted Chyazic Acid. CSee 
 Ferro-Cyanic Acid.) 
 
 Festoon. A garland of flowers, or folds 
 of drapery, when suspended so as to form 
 elliptic curves with the ends depending 
 downwards. 
 
 Fibre. A thread-like substance, mostly of 
 a vegetable origin, such as hemp, cotton, flax, 
 coir, &c. Wool and silk have been called 
 fibres, though very improperly. 
 
 Fibrin. A peculiar organic compound, 
 found both in animals and vegetables. It 
 may be procured by beating fresh blood with 
 twigs. Fibrin soon attaches itself to each 
 stem, under the form of long reddish fila- 
 ments, which become white by washing them. 
 It is solid, white, insipid, without smell, in- 
 soluble in water, softens in the air, becomes 
 viscid, brown, and transparent. 
 
 Fictile. Vases, figures, &c. formedof clay. 
 Field Book. In surveying, a book used 
 for setting dovm angles, distances, and re- 
 marks, as they arise in field practice, and from 
 which the map of the estate is constructed; 
 and the contents computed. 
 
 Figure. In arithmetic, is any one of the 
 numeral characters in present use, com- 
 monly called digits. Figure, in the arts of 
 painting, denotes a living creature generally ; 
 especially one that is human. In geometry, 
 it is the general form or shape of a body. 
 The figure of the moon is the general ap- 
 pearance of her disc, seen by the telescope. 
 
 Figure. In architecture and sculpture, is 
 the representation of any thing in solid mat- 
 ter, such as statues, &c. ; thus we say, figures 
 of brass, marble, plaster, &c. 
 
 Filament. A fine fibre or thread. 
 File. A well-known cutting instrument, 
 having teeth on the surface, for cutting metal, 
 ivory, wood, &c. When these teeth are made 
 by cuts crossing each other all over the sur- 
 face, then only are they properly called ^/e*. 
 If the cuts on the surface are only in one di- 
 rection they diXQ floats ; and if made of sharp 
 points, at certain intervals from each other, 
 they are called rasps. Files, according to 
 the degree of fineness of the teeth, are called 
 rubbers, rough, bastard cut, second cut, 
 smooth, and dead smooth. Files are also dis- 
 tinguished by their shape, as well as by the 
 purpose for which they are particularly de- 
 Bigncd. 
 
 Fillagree. a kind of ornamental work, 
 in which flowers, &c are formed of fine gold 
 
 and silver wire, curled or twisted in a serpen- 
 tine form, and soldered together. 
 
 Fillet. A small square moulding which 
 accompanies a larger moulding, as the upper 
 and lower part of the following are fillets ; — 
 
 Filter. Any material or contrivance of 
 such a nature, that a pure liquid may pass 
 through it without the grosser impurities 
 with which it may be contaminated passing 
 at the same time : of such a nature are all 
 porous stones, beds of gravel, sand, powdered 
 charcoal, folded linen, or flannel, sponge, 
 certain kinds of paper, &c. 
 
 Filtering Bag. A conical shaped bag, 
 made of close flannel, the seam being sewed 
 up tightly. It is kept open at top by being 
 tied to a hoop. It is used to filter the dregs 
 of wine, vinegar, and similar liquids. 
 
 Filtering Cup. A pneumatic apparatus, 
 to show that if the pressure of the atmosphere 
 be removed from an under 
 surface, that the pressure 
 still remaining on the sur- 
 face above, has the effect 
 of driving a fluid readily 
 through the pores of such 
 substance as it would not 
 otherwise penetrate. A is 
 a wooden cup. B is a plug 
 or nozzle of oak wood fast- 
 ened through the bottom 
 of the cup, and projecting 
 downwards two or three 
 inches. C is a vessel put beneath it, when 
 in use ; and D the open-topped receiver of 
 an air pump. To use the instrument, put a 
 little mercury into A, and exhaust the air 
 from D, when the mercury will soon filter 
 through the oak, and fall into the cup C. 
 
 Filtering Funnel. A glass or other 
 funnel, made with slight flutes or channels 
 down the lower parts of the sides. It is 
 lined, when in use, with a piece of bibulous 
 or filtering paper, folded, and loosely put in. 
 The channels allow of the oozing of the liquid 
 within more readily than a funnel of a 
 smooth regular surface. 
 
 Filtering Machine. Any contrivance 
 by which liquids may be filtered, particularly 
 water. The two following water fiMlfe will 
 be found useful and easily constructed : — No. I 
 shows how liquids may be filtered by upward 
 pressure. Water is poured into the upper 
 part of the vessel A . It runs down the pipe 
 in the centre B into the lower compartment, 
 C. The pressure of the water in A (enough 
 being poured in that the whole should be 
 full,) drives it through the perforated bottom, 
 D, — the filtermg material, (sand or powdered 
 
FI 
 
 FI 
 
 charcoal,) E, and perforated division F; 
 when, filling this chamber, it may be drawn 
 off by G, while the impurities will remain in 
 C, and may be let oflf by H. 
 
 The second figure is a filter by the descent 
 of the water through the purifying material. 
 It is poured into A, passes through the hole 
 partly stopped with sponge B, the perforated 
 cover C, the sand D, and the second division 
 E, into the vessel F, which is beneath, whence 
 it may be drawn off by G. 
 
 Filtering Paper. Any paper which is 
 sufficiently porous to suffer water to pass 
 through its substance, such as the common 
 blotting paper. 
 
 Filtering Stone. A lump of oolite, or 
 of sandstone, cut with a cup -shaped cavity 
 to hold water, which the stone from its po- 
 rous nature suffers to fall through in a series 
 of drops ; the impurities of it being left be- 
 hind in the cavity. 
 
 FiNiAL. A terminal ornament to a spire, 
 pinnacle, canopy, &c. ; most usually it con- 
 sists of a mass of foUa^e. 
 
 Finite. Limited either in time, power, or 
 dimensions. 
 
 FiitlTOR, is sometimes used to denote the 
 horizon. 
 
 Fir. a species of timber, much used in 
 building. The native fir of this country is 
 the Scottish Fir, wliich is chiefly employed 
 in out-houses and for railings. It is much 
 inferior to the Baltic timber, which is used 
 w^herever durabiUty is required. 
 
 Fire. That subtile, invisible cause, by 
 which bodies are made hot to the touch, and 
 
 expanded or enlarged in bulk; by which 
 fluids are rarefied into vapor ; solid' bodies 
 become fluid, and are finally either dissipated 
 and carried oflf in vapor, or otherwise melted 
 into glass. 
 
 Fires, Colored. Those beautiful and va- 
 ried parts of fire-works, which present, a pe- 
 cuUar and vivid color, different from that 
 produced by the ignition of the gunpowder 
 to which they owe their strength. They may 
 be either in the state of flame, or a glowing 
 fire. Colored flames are produced by setting 
 light to spirits of wine, in which one or more 
 of the following substances has been dis- 
 solved. For crimson, nitrate of strontian ; 
 blue, nitrate of barytes ; a sickly yellow, 
 common salt ; a lemon color, raspings of 
 amber ; russet, crude antimony ; bronze red, 
 use Greek pitch ; green is produced by ver- 
 digris ; pale white, by camphor ; strong sil- 
 ver white, by raspings of ivory. Sulphur 
 damped with alcohol bums with a bright blue. 
 For colored fires, see Theatrical Fires, and 
 Rocket Stars and Rains. 
 
 Fire Arms. All those sorts of arms 
 charged with powder and ball ; as cannon, 
 mortars, muskets, pistols, &c. 
 
 Fire Balls, are of three kinds ; one na- 
 tural — the other two artificial. The first are 
 collections of ignited gases, which shoot like 
 stars across the heavens ; or else masses of 
 metallic substances, which become incandes- 
 cent by falling into our atmosphere ; or else, 
 as some suppose, are stones thrown from 
 volcanoes in the moon. The second kind 
 of fire balls are merely round lumps of 
 baked clay, which are sometimes placed 
 at the bottom of a stove, to increase the 
 draught, and thereby promote the com- 
 bustion of the fuel. The third kind is in- 
 tended as a fuel by itself. It is usually a 
 composition of various combustible substances 
 so tempered together, and so united with 
 various earthy matters, as to possess the re- 
 quisite degree of combustibility, according to 
 the purpose for which it is to be used. The 
 principal object being to produce a fuel con- 
 venient in use, that shall be strong and 
 durable, and made of materials otherwise of 
 little value. Peat imbued with tar ; the dust 
 of coal, pitch, and clay ; peat, and coal, and 
 many other matters have been recommended. 
 It is usually made in the shape of balls. 
 
 Fire Brick. A very hard kind of brick, 
 made of a particular species of clay, which 
 resists the strongest action of a fire, therefore 
 used for the lining of furnaces, and other 
 similar purposes. 
 
 Fire Damp. (SeeCarburetted Hydrogen,) 
 
 Fire Engine. An engine for projecting 
 water upon buildings on fire. There are 
 several contrivances for this purpose. Those 
 of modern construction are made upon the 
 principle of the force pump. That used at 
 
FI 
 
 FI 
 
 the present time in London is the invention 
 of Mr.-Simpkin, and is thus described :— 
 
 A is part of the side of the engine. B a 
 pocket or square box, projecting from the 
 side to hold the hose and other necessary 
 implements. C G is the axis of the handles 
 which work the engine. F F the handles 
 themselves. D is the end of the pipe ad- 
 mitting the water from the plug to the working 
 part of the engine. E a handle, to turn the 
 cock beneath, inserted into the pipe D. I is 
 one out of the two working barrels, with its 
 piston withinside. L is the suction valve. 
 K the delivery valve. M the air chamber. 
 N a screw, upon which the delivery hose is 
 fixed. A hose being screwed upon D, the 
 other end of it lying in a well of water, and 
 the cock E being open ; upon working the 
 engine, the water passes through the valve L 
 into the chamber O. The contrary stroke 
 shuts the valve L, and opens that at K. The 
 «pater, therefore, is propelled into M ; the 
 elasticity of the air within which drives it with 
 force through the hose connected with N. 
 
 Fire Escape. Any contrivance adapted 
 for the rescue of persons from burning houses. 
 Fire escapes are of three kinds. First, those 
 which are kept by the inmates of the house, 
 such as knotted ropes, that they may let each 
 other, or themselves down. Second, fire 
 ladders. Third, carriage escapes, or such as 
 require a distinct vehicle for their conveyance, 
 and which are mostly furnished with a cradle 
 and tackling to let down the persons who 
 may be in danger. 
 
 Fire House, or Rosin House. An 
 ilectrical apparatus to show the inflammation 
 jf rosin by the electric shock ; the house 
 
 itself is of tin, and is the mere ornamental 
 adjunct to the experiment. 
 
 A is a glass tube extending downwards, and 
 passing through the side of the house. It 
 contains a wire throughout its whole length, 
 with a ball near A at one end, and a ball B 
 at the other. C D is also a tube and wire 
 similar to the other, but shorter, and straight; 
 and the wire passing through two corks in 
 the tube maybe drawn out as required. When 
 to be used, the two inner balls are to be 
 covered loosely with tow dipped in powdered 
 rosin, and an electrical shock of considerable 
 intensity passed through the wires ; if this 
 be done cleverly, the rosin will be inflamed, 
 and the house appear as if on fire. 
 
 Fire-Place. a general term for the 
 hearths and lower parts of the chimneys, 
 stoves, &c. in which the fires are made to 
 heat apartments. 
 
 Fire Pump. A force pump erected in a 
 populous neighbourhood for the extinguish- 
 ing of fires in the surrounding district. The 
 annexed is the view of the fire pump erected 
 at Aldgate, (London.) In some late ex- 
 periments, this pump delivered a stream oi 
 water with considerable force at a distance of 
 1600 feet from the source of supply. The 
 upper j)art of the cut is the pump, as viewed 
 externally. Below is the working barrel, in 
 which the piston and suction valve are con- 
 tained ; attached to which is the air vessel 
 to keep up the constancy of the supply during 
 the downward stroke of the handle, and to 
 increase the force of projection of the water. 
 The pipe on the upper part of the air vessel 
 is continued within the pump case, and ter- 
 minates by a union joint in the required 
 length of hose. From the working barrd 
 proceeds the feed pipe communicating to 
 the well. 
 
 Fire Ship. A small vessel filled with 
 combustible substances, and employed for 
 
 BB 
 
FL 
 
 FL 
 
 tiie destruction of an enemy's shipping, by 
 being run into the midst of them, and set on 
 fire by the crew before they quit tlie vessel. 
 
 Fire-works. Cases filled with various 
 compositions of an inflammable nature, which 
 when fired, bum with different circumstances 
 of motion, size, brilliancy, color, &c.; the 
 whole intended for the amusement of those 
 who witness the firing, and used to celebrate 
 particular events, or as a means of testifying 
 joy and congratulation. The principal com- 
 positions of all fire-works consist of gun- 
 powder, saltpetre, charcoal, and sulphur, 
 mixed occasionally with other ingredients. 
 The method of making the various kinds 
 will be found under their respective names 
 of Bengal Light, Cracker, Rocket, 8fc. 
 
 Firmament, The whole ether, or space 
 which constitutes the universe, and in which 
 the sun, stars, planets, and comets are 
 placed. 
 
 Fish Beam, Fish Back, or Fish- 
 Bellied Rail. Abeam or rail of iron, belly- 
 ing on the under-side, as are now commonly 
 those used on rail-roads. 
 
 Fixed Air. Carbonic acid gas. 
 
 Fixed Alkalis. Potass and soda. The 
 term distinguishing them from the volatile 
 alkali, ammonia. 
 
 Fixed Axis. The axis about which a plane 
 revolves in the formation of a solid. 
 
 Fixed Bodies, are generally those sub- 
 stances which are not to be separated into 
 their various elements by fire, or by a cor- 
 rosive menstruum, unless with great difficulty; 
 such are gold, platinum, lime, &c. 
 
 Fixed Ecliptic. A certain imaginary 
 plane, which never changes its position in 
 the heavens from the action of any of the 
 parts of the solar system on each other, 
 but like a centre of inertia remains im- 
 movably fixed. 
 
 Fixed Points. In carpentry, the points 
 at the angles of a piece of framing, or where 
 any two pieces of timber meet each other in 
 a truss. 
 
 Fixed Stars. Those which constantly 
 retain the same relative position with each 
 other, in contra-distinction to the planets 
 and comets, which are constantly changing 
 their relative positions. 
 
 Fixity, or Fixedness. The quality of a 
 body which renders it fixed, or a property 
 which enables it to endure fire, and other 
 violent agents. 
 
 Flags. Thin stones, used in paving, from 
 H to 3 inches thick, and of various lengths 
 and breadths, according to the nature of the 
 quarry. 
 
 Flake White. Lead corroded by the 
 pressings of grapes, or the remains of the 
 grapes after they have been pressed for wine. 
 It is brought to England from Italy, and far 
 surpasses in the purity of its whiteness, and 
 
 the certainty of its standing, all the ceruses 
 of white lead made with us in common. 
 
 Flail. An instrument for thrashing com. 
 
 Flame. The subtlest and brightest part 
 of fire, arising from the combustion of the 
 gaseous particles which are liberated by the 
 heat, these being in ordinary cases united 
 with carbon. 
 
 Flanche or Flange. A projecting piece 
 or table, for the more securely uniting toge- 
 ther the different parts of beams, pipes, &c. 
 by bolts which pass through the flanches. 
 
 Flanch Chuck. A common simple chuck, 
 formed like a flanch ; but instead of holes 
 being boiled in it to admit bolts, it is fur- 
 nished with several points, upon which the 
 article to be turned is fixed ; the other end 
 being supported by the popit head. 
 
 Flank. The straight part of the tooth of 
 a wheel, which receives the impulse. 
 
 Flank. That part of any body which ad- 
 joins the front, as flank walls or side walls. 
 
 Flaps. Folds or leaves attached to the 
 shutters of a window, which are not sufficiently 
 wide of themselves to cover the sash frames, 
 or exclude the light. 
 
 Flashes. Sluices erected on navigable 
 rivers to raise the water at such parts as are 
 impeded by shoals, that the navigation may 
 not be stopped. They are the same as locks 
 upon canals. 
 
 Flashings. Pieces of lead inserted in a 
 wall, for covering other pieces laid down for 
 gutters, &c. 
 
 Flatting. A mode of painting in which 
 the oil of turpentine only is used ; the result 
 of which is that the color remains without a 
 glossy surface. It is chiefly used for in-door 
 work. Nut oil and poppy oil are sometimes 
 used instead of turpentine. 
 
 Flax. The bast or inner bark of the flax 
 plant, linum usitatissimum, which is spun 
 into yarn for thread, and for weaving inen 
 articles. 
 
 Flemish Bond. (See Bond.) 
 
 Flemish Bricks. Strong bricks used in 
 paving. They are 6^ inches long, 2^ inches 
 broad, and 1^ thick. One hundred set on 
 edge will pave a square yard. 
 
FL 
 
 FL 
 
 Flexibility. The property or quality of 
 a body that enables it to be bent. 
 
 Flexure. The bending or curving of a 
 line or figure. 
 
 Flight. In staircasing, a series of steps, 
 whose treads are parallel and terminate 
 against a straight wall ; or, in general terms, 
 any series of stairs that lead from one apart- 
 ment to another. 
 
 Flint. (See Silex.) 
 
 Flint Glass. (See Glass.) 
 
 Flint, Liquor of. Flints fused with a 
 large quantity of potass, by which they be- 
 come soluble in water, forming a solution of 
 silicated potass, or liquor of flints. 
 
 Float. Any thing whicTi is so light as to 
 be able to sustain itself on the surface of a 
 liquid without having a tendency to sink. 
 
 Float Boards. Those boards which are 
 fixed to the rim or circumference of water- 
 wheels, serving to receive the impulse of the 
 stream, by which the wheel is put in motion. 
 
 Float of the Steam Engine Boiler. 
 (See Feed Pipe.) 
 
 Floating Bridge. Either a collection of 
 beams of timber, of sufficient buoyancy to 
 sustain itself on the surface of a river, and 
 reaching across it ; or else a certain description 
 of steam vessel, used only as a ferry boat. 
 
 Floating Electro-Magnet. (See De 
 la Rive, Marsh, Boss, ^c.) 
 
 Floating Harbour. A break-water, 
 formed of large masses of timber, securely 
 fastened together, which rise and fall with 
 the tide. 
 
 Flood Gate. A gate or sluice, that may 
 be opened and shut at pleasure, to give 
 passage to or retain the water of a river, 
 liable to be swollen by floods ; or where it is 
 necessary to dam up the stream for the use 
 of a mill. 
 
 Floor. The lowest horizontal side of an 
 apartment ; it also signifies all those parts of 
 a building which are upon the same level as 
 the first floor, the ground floor, &c. 
 
 Florentine Glasses. The first name 
 by which thermometers were known ; given 
 on account of their having been invented by 
 the Florentines. 
 
 Florid Style. A particular kind of 
 Gothic architecture, of great beauty and ela- 
 borateness of workmanship ; of which the 
 splendid chapel of Henry VII. at Westminster 
 is an example. The distinguishing charac- 
 teristics are large arched windows, with nu- 
 merous ramifications, consisting of cuspidated 
 mullions, filled with a variety of polyfoils ; 
 highly ornamental buttresses, crowned with 
 cupolas ; walls filled with niches, pinnacles, 
 and canopies, terminated with open mullion 
 work ; and the various projections adorned 
 with crockets, finials, bosses, and other en- 
 richments. 
 
 Floss Silk. The ravtellings or loose silk, 
 
 broken off" in winding the s?:k from the co- 
 coon or bag of the silk- worm. 
 
 Flour. The finely groiind meal of wheat, 
 oats, or other grain. 
 
 Flowers. A general "ppellation given by 
 the old chemists to all substances which have 
 received a fine powdery fonn by sublimation, 
 as the flowers of sulphur, the flowers of zinc, 
 &c. 
 
 Flower Pot. A particular kind of fire- 
 work, that when ignited throws out a foun- 
 tain of vivid spur-shaped sparks ; these al- 
 though so luminous, yet communicate no heat 
 to the hand held in them. The following 
 composition, which must be made very care- 
 fully, is to be rammed into small cases :— 
 Take saltpetre,4 J ounces ; sulphur, 2 ounces; 
 and lamp black, 1^ ounces. The ingredients 
 must be of the best quality, and well mixed 
 together. 
 
 Fluates. Compounds of metallic oxydes, 
 earths, and alkalies, with fluoric acid. 
 
 Fluent, or Flowing Quantity. In 
 mathematics, is a variable quantity, which is 
 considered as increasing or decreasing. 
 
 Fluid, or Fluid Body, is that whose 
 parts yield to the smallest force impressed 
 upon them, and by yielding, are easily moved 
 amongst each other ; in which sense it stands 
 opposed to a solid whose parts do not yield. 
 Fluids are divided into elastic and noU' 
 elastic. The former are those which may be 
 compressed into a smaller compass, but 
 which, on removing the pressure, resume 
 their former dimensions, as air. Non-elastic 
 fluids preserve tho same or very nearly the 
 same bulk, under all circumstances of pressure, 
 as water and other liquids. 
 
 Flue. The long tube of a chimney, from 
 the fire-place to the top of the shaft. 
 Fluid, Electrical. (See Electricity,) 
 Fluidity. The state or affection of bodies 
 which renders them fluid. 
 
 Fluoborates. Combinations of various 
 bases with fluoboric acid. 
 
 Fluoboric Acid, Fluoride op Boron, 
 or Fluoboric Gas. A gaseous compound 
 of fluorine and boron, obtained by heating a 
 mixture of vitrified boracic acid and fluor 
 spar. It is colorless, of a pungent odour, 
 highly deleterious to respiration, and ex- 
 tinguishes flame. Mixed with water, it 
 forms a caustic, fuming solution, called bo- 
 rohydrofluoric acid. Neither the gas nor 
 the liquid act upon glass, but they rapidly 
 destroy almost all organic substances what- 
 ever. 
 
 Fluoric Acid. A peculiar and highly 
 corrosive acid, procured by distilling equal 
 weights of fluor spar and sulphuric acid in a 
 leaden retort. A gas passes over, which is 
 the true fluoric acid, and which may be con- 
 densed into a liquid by cold. It is absorbable 
 by water, and is very volatile, sending out 
 
FL 
 
 FL 
 
 white fumes in the air. It rapidly corrodes 
 glass and flint, from which it may be known 
 from all other substances whatever. If a 
 drop touch the skin, even for an instant, 
 it completely disorganizes it. and produces a 
 rery painful wound. 
 
 Fluorides. Combinations of fluorine. 
 
 Fluorine. An imaginary radical of the 
 above acid. 
 
 Fluosilicic Acid. A combination of 
 hydro-fluoric acid and silex, obtained by 
 pouring hydro-fluoric acid on glass, when 
 dense white fames of the fluosilicio acid will 
 escape. 
 
 Fluor Spar. Derbyshire spar, or fluate 
 of lime. 
 
 Flush. A term used by builders and 
 artizans, to signify even with ; as a door may 
 be flush with the walls, or receding from them. 
 
 Fluting. The longitudinal grooves cut in 
 the shaft of a column. In the Doric order 
 there are always twenty, and these shallow. 
 In the other orders, twenty-four, semi- 
 circular, with a space between them, rounded 
 at either end, except where the column is 
 without a plinth, when they are carried quite 
 down to the base. 
 
 Flux. A general term made use of to de- 
 note any substance or mixture, added to as- 
 sist the fusion of minerals. In the large 
 way, limestone and Derbyshire spar are used 
 as fluxes, but the most powerful are those of 
 alkalis. The principal of which are crude 
 flux, black flux, and white flux. Crude flux 
 is a mixture of nitre and tai-tar. White flux 
 is formed by projecting equal parts of nitre 
 and tartar, by moderate portions at a time, 
 into an ignited crucible. Black flux differs 
 from the preceding in the proportion of the 
 ingredients ; in this the weight of the tartar 
 is double that of the nitre. 
 
 Flux and Reflux of the Sea. (See 
 Tides.) 
 
 Fluxional Analysis, is the analysis of 
 fluxions and fluents, distinguishable from the 
 difilerential calculus by its notation, but in all 
 other respects identical. Calculations by this 
 mode conceive that all finite magnitudes are 
 or may be resolved into infinitely small ones, 
 supposed to be generated by motion, as aline 
 by the motion of a point, a superficies by a 
 line, and a solid by a surface ; of which they 
 are the elements, moments, or differences. 
 The art of finding these infinitely small quan- 
 tities, and working with them, is called the 
 direct method of fluxions ; and the method 
 of finding the flowing quantities or fluents 
 is what constitutes the inverse method. 
 
 Fluxions, is the magnitude by which any 
 moving or flowing quantity would be uni- 
 formly increased in a given portion of time, 
 with the generating celerity at any proposed 
 instant, supposing it thence to continue in- 
 irariable. 
 
 Flt. a set of two or more farmers placed on 
 an axis, sometimes for the same purpose a* a 
 fanner, but more frequently to equalize the 
 motion of a small piece of machinery, by oo« 
 casioning a resistance of the air, and thereby 
 preventing it ninning down too rapidly. 
 Flies, therefore, answer ia some degree the 
 purpose of a pendulum ; for example, the 
 wheels of the time movement of a clock are 
 terminated by a pendulum ; the wheels of the 
 striking part by a fly. All machinery must 
 end either in a fly or a pendulum, or it must 
 have a certain part which acts upon a similar 
 principle of resistance ; such as the paddle 
 wheels of a steam-boat, the wheels of a car- 
 riage, the sails of a windmill, &c. 
 
 Fly Wheel. A large heavy wheel, at- 
 tached to machinery to equalize the motion 
 of it. It acts exactly upon the contrary 
 principle to the simple fly ; its action being 
 to collect the surplus power of the machine 
 when it can be spared, and to apply this 
 collected power when afterwards wanted. 
 For example, in the working of the crank B 
 in the following cut, it has no power to turn 
 the axle, when at the points C C, and would 
 therefore stop ; but the momentum of the 
 fly wheel A A carries it beyond the points 
 C C, when the crank acts by its own power 
 again. 
 
 Flyer, Electrical. A wheel of several 
 wires, projecting horizontally from the same 
 centre ; the outer end of them all being 
 turned at a right angle and pointed, the points 
 being all directed the same way. If such a 
 wheel be supported on a wire or pivot, which is 
 fastened upright on the prime conductor of 
 
FO 
 
 FO 
 
 an electrical machine, and the machine put 
 in action, the fluid will fly from each of the 
 points ; and the action of this upon the air 
 will give to the flyer a rapid motion. 
 
 Flyers. A straight row of steps or stairs. 
 Flying Buttress. (See Buttress.) 
 Fly Powder. The black colored powder 
 obtained by the spontaneous oxidisement of 
 metallic arsenic in the air. 
 
 Focal Distance. In the conic sections, 
 is the distance of the focus from some fixed 
 point, viz. : from the vertex of the parabola, 
 and from the centre in the ellipse and hyper- 
 bola. 
 
 Focus, is that point in the transverse axis 
 of a conic section, at which the double ordi- 
 nate is equal to the parameter or bounding 
 line. From which arises this property, that 
 when there are two foci, as in the ellipse : 
 if light be reflected from one focus, and 
 strike the surface of the curve, it will be re- 
 flected to the other focus, the heat and light 
 of the luminous body being there concen- 
 trated ; hence the name focus, or burning 
 point. Focus, in optics, is a point wherein 
 several rays concur, or are collected, after 
 having undergone either refraction or re- 
 flection. The focus of a lens, or combi- 
 nation of lenses, is the distance between the 
 centre of the lens and the point in which the 
 rays are concentrated. Some lenses have no 
 focus. A virtual focus, or point of diver- 
 gence, is the point /rom which lines tend. It 
 is therefore contrary to the true focus, al- 
 though it may, perhaps, be the same point. 
 
 Focus, Geometrical and Refracted. The 
 point in which the rays of light ought, ac- 
 cording to their known laws, to be concen- 
 trated, when reflected from a concave mirror, 
 or refracted through a lens, is termed the 
 geometrical focus ; that in which they are 
 actually formed, is the refracted focus. 
 Th«;se foci are separated from each other in 
 proportion to the degree of spherical aberra- 
 tion. 
 
 Foil. Among jewellers, is a thin leaf of 
 metal placed under a precious stone to in- 
 crease its brilliancy, or give it an agreeable 
 or a different color. Foils are made of plates 
 of copper, rolled and beaten as thin as 
 possible, then boiled in an earthen vessel 
 with equal quantities of tartar and salt. When 
 they have assumed a good white color, they 
 are taken out, dried, and afterwards polished 
 with whiting. If desired of a particular 
 color, it is only necessary to varnish them 
 with that colored varnish, observing that all 
 the colors must be quite transparent, such as 
 lake, Prussian blue, verdigris, and others. 
 
 Foil. In architecture; all those rounded 
 or leaf-like forms, seen in Gothic windows, 
 niches, crests, battlements, &c. are called 
 foils, and are distinguished according to the 
 number of them, which ar« combined to- 
 
 gether into the names Tre-foil, Quatre-foil, 
 Cinque-foil, 8fc. (See each of these terms.) 
 
 Folding Doors. Two doors which are 
 hung on the two side posts of a door frame, 
 and open in the middle. 
 
 Folding Joint. A joint made like a 
 hinge. 
 
 Foliage. In the fine and ornamental 
 arts, an artificial arrangement of leaves, 
 fruit, &c. 
 
 Foliation. (See Feathering, Cusps, and 
 Foils.) 
 
 FoNDUS. That particular kind of paint- 
 ing calico, paper-hangings, &c. in which the 
 colors are blended into each other. 
 
 Font. The basin to hold baptismal water. 
 
 Foot of a preis or other machine, is the 
 foundation upon which it stands ; also a 
 measure of length, derived from the human 
 foot, containing 12 linear inches. A square 
 foot is 144 inches, or a square surface 12 
 inches on each side. A cubic foot is a cube 
 of 12 inches in length, breadth, and thick- 
 ness. Its content therefore is 12x12x1 2, 
 or 1 728 cubic inches. 
 
 Footings. The lower part of a brick or 
 stone wall, in which a part of the bricks 
 project beyond the general surface. 
 
 Foot Iron. An iron fastened to the foot> 
 in order to preserve the shoe while digging. 
 
 Force. Whatever tends to produce mo- 
 tion, or a change of motion in any body, is 
 called force or power. It may be artificial^ 
 such as the force of steam and gunpowder,, 
 which constitute expansive forces. Natural 
 forces are of two kinds ; the first derived 
 from the bodily strength and vital energy of 
 animals, human power, &c. ; the other kind 
 is the effect of the atmosphere, water, and 
 other elements, as acted upon by the centri- 
 fugal, centripetal, electric, magnetic, and 
 chemical forces. Force is measured by the 
 mechanical result produced : thus, if a blow 
 be given to the ball A, which drives it to B, 
 the force is equal to A B. If A is driven to 
 C, the force would be A C. In the calcu- 
 lation of forces, allowance must be made at 
 
FO 
 
 FO 
 
 an times for any thing which can increase or 
 diminish the effect, such as friction, gravity, 
 &c. When a body is in motion, the force it 
 acquires, is the weight of the body multi- 
 plied by its velocity ; but when the body is 
 at rest, such as pressing upon any thing, or 
 suspended from a cord, its force is its weight 
 only. Forces may be either accelerative, 
 retardive, constant^ or variable. 
 
 Force, Centrifugal. (See Centrifugal.) 
 
 Force, Centripetal. (See Ce7itripetal.) 
 
 Forces, Composition and Resolution of. 
 Are the laws which explain the result pro- 
 duced by several forces acting in different 
 directions : thus, the power which keeps up 
 a boy's kite, may be resolved into three 
 forces. That of the wind, to drive it along 
 iind upwards. That of the string, to pull it 
 back ; and that of gravity, to draw it down. 
 These forces act variously until they exactly 
 balance each other, when the kite remains at 
 rest, and a single force only becomes ap- 
 parent, which is, a pulling at the string; this, 
 therefore, is the composition of the three 
 acting forces. 
 
 Forceps. A general term for all small 
 tools which act upon the nature of tongs, 
 such as pincers and plyers. 
 
 Force Pump. A pump which is capable 
 of driving a stream of water above the pump 
 barrel by means of compressed 
 air. It is shown in the margin, 
 where the lower pipe is sup- 
 posed to stand in the well of 
 water. When the handle of 
 the pump, and consequently 
 the piston is drawn up, a va- 
 cuum being produced below 
 the piston, the pressure of the 
 atmosphere on the water of 
 the well drives the water 
 through the valve at the bot- 
 tom of the pump barrel, and 
 thus the barrel is filled with 
 water. When the handle is 
 forced down again, the water 
 instead of .returning, (the 
 valve being now shut,) passes 
 
 to the side vessel, which has a ' _ 
 
 tube in it, reaching to near the 
 bottom : when, therefore, the water covers 
 the bottom of this pipe, the air above be- 
 comes compressed, and forces the water up 
 the pipe into the air, or into a vessel con- 
 nected with the pipe above. 
 
 Fore Front. The principal or front en- 
 trance to a building. 
 
 Foreshorten. In painting, the dimi- 
 nution in length which the parts of objects 
 appear to have when looked at obliquely. 
 
 Forge. The name either of the furnace 
 where wrought iron is hammered, and 
 fashioned with the aid of heat ; or the great 
 workshop where iron is made malleable. 
 
 Fork Chuck. This useful appendage to 
 the lathe may be understood by an inspection 
 of the figure below. The part which screws 
 to the mandril has on the outer side a square 
 hole, in which forked pieces of iron, (like that 
 represented,) of different sizes, according to 
 the strength required, are placed when in use. 
 This chuck always requires the work to be 
 supported at the other end. 
 
 Form. In printing, an assemblage of pages 
 or lines of type, arranged in order, ready to 
 be printed from. Every form is inclosed in 
 an iron chase, wherein it is firmly locked by 
 a number of small wedges of wood, called 
 quoins. There are two forms to every sheet 
 of a book, one for each side of the paper ; 
 and each form consists of more or fewer 
 pages, according to the size of the book. 
 
 Formiates. Combinations of the formic 
 acid and certain bases. 
 
 Formic Acid. An acid obtained from 
 ants. 
 
 FoRMULiE. Characters or symbols, by 
 which certain rules or quantities in mathe- 
 matics are represented ; or in chemistry, by 
 which substances, either simple or compound, 
 are known. 
 
 Forum. An open space, used among the 
 ancients for public assembly. 
 
 Fothering. a method sometimes re- 
 sorted to for stopping a leak in a vessel at 
 sea. It consists in stitching loosely a quan- 
 tity of oakum upon a sail, which is drawn 
 under the vessel's bottom, and by the flow 
 of water through the leak, the oakum is 
 drawn into the aperture. 
 
 Foundation. That upon which any thing 
 rests, particularly the lower part of a house, 
 wall, &c. or the beds of earth, concrete, &c. 
 upon which it stands. 
 
 Foundry. A place in which founding is 
 carried on. 
 
 Founding. Melting, and afterwards cast- 
 ing in moulds prepared for the purpose, 
 various articles in metal ; the general subject 
 being divided into iron founding, brass 
 founding, copper founding, bell founding, 
 bronze founding, and type founding. The 
 same operation in lead, tin, silver, gold, 
 zinc, &c. is usually called casting. 
 
 Fount, or Font. Among printers, a set 
 of types, sorted for use, that includes large 
 and small capitals, single and double ordinary 
 letters, points, lines, numerals, &c. as a fount 
 of pica, long primer, brevier, &c. 
 
 Fountain. A machine or contrivance by 
 which water is violently spouted or darted 
 
FO 
 
 FO 
 
 up. There are various kinds of artificial 
 fountains, but all formed by a pressure of one 
 sort or another, upon the surface of the 
 water, viz. : either the pressure or weight of 
 a head of water, or a pressure arising from 
 the spring or elasticity of the air. To con- 
 struct the first kind of foimtain is extremely 
 easy, nothing more being requisite than to 
 have a pipe, which leads from a reservoir, 
 higher than the mouth of the jet ; when the 
 water will spout to a height nearly equal to 
 the reservoir itself, if the conveying pipe be 
 more than half an inch in internal diameter. 
 Water spouting from and falling upon rock- 
 work, is the most effective in garden scenery. 
 
 Fountain Glass. A pneumatic appi- 
 ratus, showing the elasticity of the air. It 
 is a glass vessel with a brass 
 top, and a tube within it, ex- 
 tending to near the bottom 
 of the glass. When this glass 
 is partly filled with water, and 
 placed under a tall receiver of 
 the air pump, the air being ex- 
 hausted by the action of the 
 pump, the elasticity of that air 
 which remains within the vessel 
 drives the water through the 
 tube, and makes it play into 
 the receiver like a fountain. 
 This action continues either un- 
 til almost all the water is driven 
 out, or else until the air has 
 become so rarefied that it no 
 longer has sufficient force to 
 overcome the resistance. 
 
 Fountain of Condensed Air, will be 
 understood from the structure of the fountain 
 glass. The only difference being that the 
 present instrument throws up the water it 
 has been previously paitly filled with, in 
 consequence of air being first condensed into 
 the vessel by means of a condensing syringe 
 ■crewed to the top of it. A stop cock, there- 
 fore, is necessary on the upper part, in order 
 
 that the jet may be substituted for the con- 
 densing syringe, as occasion requires. 
 
 Fountain of Circulation. A curious 
 constructed glass apparatus, in which a co- 
 lored liquid is seen to flow 
 upwards. It is represented 
 in the margin, and con- 
 sists of a large glass tube 
 with a bulb at each end, and 
 a small tube connected with 
 each bulb, communicating 
 with the lower one B, but 
 not with A ; this small tube 
 being twisted and contorted 
 in and out in any fanciful 
 manner. The two large balls, 
 and the tube between them, 
 being filled with a colored 
 fluid, the air is completely 
 exhausted from the rest of 
 the apparatus, except a small 
 bubble left in the end of the 
 small tube nearest to A, and 
 the whole hermetically sealed. 
 The ball A being turned up- 
 wards, the fluid will pass 
 from B up the small tube, 
 and through all its con- ~ d^ f B 
 tortious, till it finds its level, 
 near the top. Upon reversing 
 the whole, so that B becomes the higher 
 ball, the fluid falls from B to fill up the 
 former loss of fluid in A, and consequently 
 the fluid in the small tube will follow it, 
 being pressed by the elasticity of the small 
 bubble of air left in it. The whole ought to 
 be inclosed m a case, so that the larger tube 
 and balls are hidden. 
 
 Fountain Pen, is a pen contrived to hold 
 a greater quantity of ink than usual, so as 
 to supply the writer for a considerable time, 
 without taking a fresh supply. 
 
 FouR-viTAY Cock. A description of valve, 
 much used in steam engines, to pass the 
 steam to and from the cylinder. The follow- 
 ing is a vertical section of one :— A is a pipe 
 connected with the condenser. B, with the 
 boiler. C, with the top of the steam cylinder ; 
 and D, with the bottom of the cylinder. E 
 is the key of the cock, which is capable of 
 being turned round, so as to stretch across 
 
FR 
 
 FR 
 
 from E to F. In its present position, the 
 fresh steam is passing to the bottom of the 
 cylinder, and the waste steam is passing from 
 the top of the cylinder to the condenser. 
 Upon giving the key of the cock a quarter 
 tmi), so that it reaches from E to F, B would 
 be connected with C, and A with D ; con- 
 sequently the action would be reversed, and 
 the steam pass away from the bottom, and 
 be admitted to the top of the cylinder. 
 
 Foxing. A term applied to beer, when it 
 turns somewhat sour and musty in the fer- 
 mentation. 
 
 Fox-TAiL Wedging. A method of fasten- 
 ing a tenon in a mortice, by means of splitting 
 or cutting a piece out of the tenon, so that 
 a wedge may be driven in after the tenon is 
 in its place. 
 
 Fraction. The part or parts of a whole 
 quantity, thus, if any thing be divided into 
 eight equal portions, each portion would be a 
 fraction, as one-eighth, three-eighths, five- 
 eighths, &c. which would be expressed in 
 figures, by two numbers, with a line drawn 
 between them, as i, |, f . The lower of these 
 figures, in every case, is called the numerator , 
 and shows how many parts the integer is di- 
 vided into ; the upper figure is called the 
 denominator, and indicates the number of 
 these parts that is to be taken. Fractions 
 may be either proper or improper, simple, 
 compound, complex, or mixed. A proper 
 fraction has the upper figure less than the 
 lower, as \, An improper fraction has the 
 upper figure equal to it, or else greater, as |. 
 A simple fraction is that which consists of a 
 single denominator and numerator, as f . A 
 compound fraction consists of two or more 
 simple fractions, as i of f . A compUx 
 fraction is that whose parts are both fractional, 
 
 as T A mixed number is a fraction and 
 
 ■J* 
 whole number united, as 4^, 9f , &c. 
 
 Frame. Various pieces of wood, metal, 
 &c. so bent or joined together as to inclose 
 a space. 
 
 Framing. All the timbers of a house are 
 so called, such as the partitioning, roofing, 
 flooring, &c. 
 
 Fran90is's Steam Engine. An engine 
 invented by M. Franfois, professor of phi- 
 losophy, at Lausanne, for the draining of 
 waste land, for which purpose it is well 
 adapted, equally on account of its simplicity 
 and eflScacy. The machine is composed of 
 the pipe B, the lower end of which is in- 
 serted in the water, and the upper end enters 
 the receiver A ; a pipe D proceeds from the 
 receiver, as high as it is required to elevate 
 the water, and has a cock or valve at L. 
 Another pipe having a stop cock at I, con- 
 ducts steam from the boiler C into the re- 
 ceiver A. E is a bucket turning on an axis : 
 to this bucket two levers are fixed, having 
 
 joints at the top; that is, turning partly on 
 their axes. G is a trough which conducts 
 away the water which may be raised by the 
 engine. The novelty of this engine con- 
 sists in the simple means by which it is made 
 to be self-acting. When the steam, flowing 
 from the boiler into the receiver, forces the 
 water which it may contain up the pipe D, 
 and is emptied into the swinging bucket E ; 
 this bucket being filled, turns on its axis, and 
 empties itself into the trough E, and is after- 
 wards brought into the horizontal position by 
 the counterpoise F. However, as the bucket 
 turned down, it depressed the lever J, and 
 raised the lever K ; the lever J acted on the 
 lever beneath G to shut the cock I, and the 
 lever K to shut L. The further passage of 
 the steam from the boiler into the receiver 
 was shut, and the water in the eduction pipe 
 prevented from flowing into the receiver. A 
 valve at H, in the trough, was also at this 
 moment raised, which permitted a small 
 quantity of cold water to fall into A, and 
 condense the steam it contained. The 
 pressure of the atmosphere then forced the 
 water into the receiver, and the counterpoise 
 F restoring the swinging bucket to its former 
 position, the cocks I and L are opened, the 
 steam escapes from the boiler, and the water 
 is again driven out ; and this takes place five 
 or six times in a minute. 
 
 Frankfort Black. A vegetable char- 
 coal, procured by calcining vine branches, 
 and other remains of the vinegar manufacture 
 01 Germany. 
 
 Frankincense. The gum of olibanum ; 
 it is of a powerful and pleasant smell, for 
 which reason it is highly esteemed, and used 
 both as a vulnerary and to mix in pastiles, 
 and the incense used in religious ceremonies. 
 
 Franklin's Hypothesis of electricity 
 is, that there is but one electrical fluid, tte 
 
FR 
 
 FR 
 
 redundancy of which occasions all those ap- 
 pearances which Du Fay attributed to that 
 which he called the vitreous fluid, and its 
 deficiency causing the effects attributed to the 
 resinous fluid. The former, Franklin called 
 plus, or positive ; the latter, he called minus, 
 or negative. 
 
 Frauenhofer's Lines. This optician 
 observed, when looking at & very small ray 
 of light passing through il narrow chink, 
 with a very excellent prism held close to the 
 eye, that it was intersected with a great 
 number of fine black lines, the distances and 
 regularity of which are different in different 
 media;, so much so, that the refractive power 
 of various media may be determined by the 
 condition of these minute lines, which are 
 called Frauenhofer's lines. 
 
 Freestone. A stone, consisting of sand 
 united together without any apparent cement. 
 It is rather soft, especially when fresh quar- 
 ried, but much used for building purposes, 
 it being easily cut into any required form, 
 and when of good quality it looks well, and 
 possesses considerable durability. 
 
 Freezing, or Congelation. The trans- 
 formation of a fluid body into a fii-m or solid 
 mass, by the action of cold. 
 
 Freezing Mixture. A preparation for 
 the congelation of water and other fluids. 
 An equal mixture of snow, or pounded ice, 
 and salt, sinks the thermometer to about 30°. 
 Equal parts of nitrate of ammonia and wa- 
 ter sinks it 46°. Muriate of lime, 3 parts, 
 and snow or ice, 2 parts, sinks it 80°, or 
 from the freezing point to 48° below zero. 
 
 Freezing Point, denotes the point or 
 degree of cold shown by a mercurial thermo- 
 meter, at which certain fluids begin to freeze, 
 or when frozen at which they begin to thaw 
 again. On Fahrenheit's thermometer this 
 point is at + 32 for water, and at — 40 for 
 quicksilver. Those fluids freezing at these 
 two points respectively. 
 
 Freezing Pump. (See Leslie. ) 
 
 French Berries. The fruit of the rAam- 
 nus infectorius, called by the French graines 
 d' Avignon. They are used in dyeing, and 
 yield a pretty good yellow color, though one 
 void of permanency. 
 
 Fresco Painting. An art of painting in 
 water colors upon the surface of wet stucco 
 or plaster, so that the colors are imbibed by 
 the wall when laid on. The Cartoons at 
 Hampton Court, by Raffaelle ; and the ceiling 
 of the Hall at Greenwich, by Sir James 
 Thornhill, are splendid examples. 
 
 Fretted Vaults. Vaults which are much 
 intersected with small groins or ribs. 
 
 Fret-Work. Any small and delicate car- 
 ving. 
 
 Fret. The ornamental iron-work below 
 the bars of a grate, so called because often 
 £ashioned of the fret ornament, which is any 
 
 combination or intermixture of straight lines 
 The following is an example of the fret or- 
 nament : — 
 
 Friability. That quality of certain bo- 
 dies whereby they are easily reduced to pow- 
 der. 
 
 Friction. The action of rubbing two bo- 
 dies together, or the resistance in machines 
 caused by the motion of the different parts 
 against each other. 
 
 Friction Balls. A contrivance for mo- 
 ving heavy weights around a centre ; such, 
 for example, as a block of marble from which 
 a piece of statuary is to be cut. The block 
 is placed upon a circular plate of iron, which 
 fits upon a similar plate beneath. A number 
 of iron or stone balls are placed between the 
 two plates, generally in a groove around the 
 edge, there being either a channel cut in the 
 touching surfaces of the two plates, sufficiently 
 deep to prevent the balls rolling out, or else 
 a rim is put round the lower plate with the 
 same object. 
 
 Friction Clutch. A mode of putting 
 machinery in and out of gear, when the ve- 
 locity of the parts is very great. 
 
 A is a pulley, revolving freely on the shaft 
 S. B is another pulley, also capable of 
 revolving on the shaft. C is a spring, se- 
 cured in its place by the pin E, and forcing 
 the pulley B against the collar D, which is 
 fixed permanently to the shaft. When motion 
 is required to be communicated to the shaft 
 S, the pulley A is moved towards the 
 pulley B, and the teeth projecting from the 
 side of A, taking hold of the teeth of B, 
 carries both pulleys round together. When 
 the friction of the pulley B against the collar 
 D gradually overcomes the inertia, it carries 
 the shaft and machinery attached to it all 
 round together. 
 
 Friction Cones. A method of disengaging 
 and re-engaging machinery, and that without 
 the sudden jolts to which some other modes 
 of coupling subject it to. 
 
 On the moving shaft A is fixed a cone C, 
 and on the shaft B is another cone D, made 
 
FR 
 
 FR 
 
 to fit in the cone C. The cone D is moveable 
 on a square part of the shaft B, and may, by 
 a lever, be moved in and out of the gear. 
 When the cone D is moved forward, the cone 
 C receives motion by friction against its in- 
 ternal surface. 
 
 Friction Rollers, are small cylinders 
 fixed between the axis on which a pulley 
 turns, and the pulley itself, the hollow axis 
 of the latter being made larger in order to 
 receive them. There may be about six or 
 eight of them ; they are formed like little 
 cylinders, fixed each on its own axis, and 
 working at the two ends into a corresponding 
 number of holes made equally distant, in a 
 brass ring, at each side, which is fastened to 
 the pulley itself. One side of the cut shows 
 the friction rollers without the i-ing holding 
 the end of them ; the other shows the whole 
 complete, the rollers being then scarcely 
 perceptible. 
 
 Friction "Wheels. "WTien the axle of a 
 wheel works in an immoveable bush, the 
 friction is often very great ; to prevent this, 
 sometimes the axle is made to rest upon the 
 circumference of two wheels, which turning 
 on their centres, and bearing the axle only 
 on two points or lines, very much diminish 
 the friction. In the cut the axle C is sup- 
 ported on the friction wheels A and B. 
 
 Friesland Green. Ammoniac© -muriate 
 of copper; the same as Brunswick green. 
 
 Frieze. A large flat member of a build- 
 ing, between the architrave and the cornice. 
 
 It is mostly ornamented with bas reli^, 
 or the figures of animals; hence it is some- 
 times called zoophorus. 
 
 Frigid Zones. Those two portions of the 
 earth's surface which surround the north and 
 south poles, extending towards the equator 
 23° 28' each, making a circle of 46° 56', and 
 which is bounded by one or other of the polar 
 circles ; the north frigid zone by tJie arctic 
 circle ; the south by the antarctic. 
 
 Frigorific. Producing cold. 
 
 Frigorific Mixtures. (See Freezing 
 Mixtures.) 
 
 Frigorific Particles. A term used by 
 some early philosophers to denote what they 
 considered the matter of cold, as modern 
 philosophers make caloric the matter of heat. 
 
 Frisket. An iron frame, forming part of 
 a printing press, used to keep the sheet of 
 paper on the tympan, and to prevent the 
 margin from being blacked during the 
 operation of printing. 
 
 Fritt. The materials of glass are first 
 mixed together, and then calcined, though 
 not melted ; in this state they are called 
 fritt. 
 
 Prizing of Cloth. A term applied to 
 the forming the nap of cloth into a number 
 of little hard burs or prominences, covering 
 almost the whole of the ground. 
 
 Frontispiece. In architecture, signifies 
 the decorations upon the principal front of a 
 building, as the frontispiece of Westminster 
 Hall, Abbey, &c. ; synonymous with portail. 
 
 Frost. That state of the atmosphere 
 which causes the congelation or freezing of 
 water, or other fluids into ice. 
 
 Frost Bearer. (See Cryophorus.) 
 
 Frost Smoke. A phenomenon peculiar to 
 the polar regions. Previous to the freezing of 
 the sea, it smokes like burning turf land, 
 and a fog or mist arises, called frost smcke. 
 This cutting mist frequently raises blisters on 
 the face and hands, and is very pernicious to 
 the health. It appears to consist of small 
 particles of ice, and produces the sensation 
 of needles pricking the skin. 
 
 Frosted Work. In architecture, is a 
 species of work imitative of ice formed by 
 irregular drops of water, bearing a rude re- 
 semblance to clustered icicles. 
 
 Frotering ham's Pyrometer, combines 
 simplicity with considerable delicacy. It is 
 also intended to indicate the changes of at- 
 mospheric temperature. 
 
 A is a bar of iron four feet long and an 
 inch and a quarter wide, having a polished 
 brass surface screwed to it by steel screws, 
 which are fitted to short slips in the brass to 
 allow of the expansion of the iron bar, 
 without permitting that of the brass ornamen- 
 tal surface to affect the hardened steel apex. 
 This apex moves tlie lever B, which raises 
 the lever C, both turning on fine axes. A 
 
FU 
 
 FU 
 
 chain from the extremity of C is lapped twice 
 round the pulley D, on the axis of the 
 index G, which moves round a graduated cir- 
 cle. The counterpoise F brings back the 
 index as the levers fall. 
 
 Prustrum, In geometry, is a part of a 
 solid next the base, left by cutting off the 
 top by a plane parallel to the base, as the 
 frustrum of a cone, pyramid, &c. 
 
 Frustrum. In the fine arts, is used to 
 designate a broken statue, a fragment of a 
 gem, or an antique coin or medal. 
 
 Fuel. Any solid material capable of sup- 
 porting its own combustion, ard at the same 
 time giving out heat. The ordinary fuels are 
 wood, coals, coke, and charcoid. 
 
 Fulcrum. In mechanics, the prop or 
 support upon which a lever is sustained. 
 
 Fun GATES. The combinations of a peculiar 
 acid, extracted from mushrooms. 
 
 FuNGic AcTD. (See Fungates.) 
 
 FuNGiK. The fleshy part of mushrooms 
 deprived by alcohol and water of every thing 
 soluble. 
 
 FuLGURATiON. The sudden brightening 
 of the melted gold and silver in the cupel of 
 the assayer, when the last film of vitreous 
 lead and copper leaves their surface. 
 
 Fuliginous. Smoky, or of the color of 
 smoke. 
 
 Fuller's Earth. A particular kind of 
 clay, of a greenish color, unctuous feel, and 
 which does not adhere to the tongue, nor yet 
 form a plastic paste with water. It has the 
 power of strongly absorbing greasy matters, 
 and is therefore valuable in cleansing woollen 
 and other goods. It is found abundantly in 
 
 Bedfordshire, Berkshire, Hampshire, and 
 Surry. 
 
 Fulling. The cleansing of wool and 
 woollen cloths from the greasiness with 
 which the former is naturally imbued. 
 
 Fulminating Powders, or Fulminates. 
 Highly detonating compounds of gold, silver, 
 mercury, &c. formed by acting upon their 
 nitric solutions by alcohol, in some cases by 
 ammonia. 
 
 FuLMiNATiON. Aninflammation so sudden 
 and violent that a loud noise is produced. 
 
 FuLMiNic Acid. An acid supposed to be 
 of the same composition as cyanic acid, but 
 known only in that particular state of union 
 with the metals in which a fulminating 
 powder is produced. 
 
 Fumigation. Smokmg, or the submitting 
 objects or apartments to the action of par- 
 ticular fumes, such as the smoking of pro- 
 visions, the disinfecting rooms by chlorine, 
 the burning of pastiles to remove disagreeable 
 smells, &c. 
 
 Function. A quantity is said to be a 
 function of another quantity, when its value 
 depends on that quantity and known quan- 
 tities only. 
 
 Funicular Machine, is a term used to 
 denote an assemblage of cords, by means of 
 which two or many powers sustain one or 
 many weights. 
 
 Funnel. A conical or bell-shaped instru- 
 ment with a narrow tube, for facilitating the 
 transferring of liquids or small substances 
 from one vessel to another. 
 
 Furlong. An English measure of length, 
 equal to the eighth of a mile, or to 220 
 yards. 
 
 Furnace. Any inclosed fire-place con- 
 structed so as to generate a great degree of 
 heat, and to continue that heat for a con- 
 siderable length of time. Furnaces are of 
 various kinds, according to the object for 
 which they are intended ; such as the glass 
 blow-er's furnace, the founder's furnace, the 
 cliemical furnace, the baker's oven, &c. The 
 following description of two or three furnaces 
 will explain the ordinary construction of all 
 furnaces : — The first cut represents a chemical 
 furnace of a form and size convenient for 
 experimental purposes ; the one side of the 
 cut showing the external, the other the in- 
 ternal structure of it. It is in three parts, 
 which fit on to each other. A is the semi- 
 circular cap which reverberates the heat 
 downwards : upon the top is a hollow socket 
 on which a short tin chimney is fitted occa- 
 sionally. B is the part where the fuel, (char- 
 coal,) IS placed. C is the ash-hole. D isan 
 earthenware cup or evaporating dish, which 
 rests upon a ledge left inside the top of B. 
 E^ is a plate of slieet iron for the fuel to rest 
 upon, it is pierced with holes for the sake 
 of draught. The iron plate rests upon a 
 

 FU 
 
 FU 
 
 small ledge left near the bottom of B. There 
 are, moreover, three holes, one in each com- 
 partment ; that in A for the introduction of 
 small retorts, tubes, &c. ; that in B for the 
 supply of fuel ; and that in C for the remo- 
 val of ashes, and also to supply air to the fire. 
 Small pieces of baked clay are made to fit 
 these holes when occasion requires. 
 
 The next represented is the air furnace, 
 and is that usually employed for the melting 
 of metals. The charcoal, coke, or coal, is 
 placed upon the grating in the centre of the 
 figure, B ; and the crucible, containing the 
 metal to be melted, is placed in the centre of 
 the fire, A. The chimney does not ascend 
 perpendicularly from the fire, but communi- 
 cates with it by a lateral opening. There is 
 an opening, (covered by the iron plate C,) 
 above the crucible, for the purpose of taking 
 it in and out of the furnace. 
 
 The following cut shows an air furnace of 
 the reverberatory kind. A is the ash-pit, 
 above which is the grate. B the door. C 
 the hearth, and D the chimney. In this sort 
 of furnace the heat generated is not made to 
 act immediately upon the crucible, but the 
 fire-place is arched over, and a horizontal flue 
 passes along to about four times the length 
 of the fire place, and opens at the farther 
 
 end into the bottom of the chimney. The 
 flame and heated air are reflected or rever- 
 berated from the arched roof above the fire, 
 and carried from thence along the flue to a 
 retort placed at the bottom of the chimney, 
 as at E. This kind of furnace, from the 
 great heat which may be procured by it, is 
 extensively used in the iron manufacture ; 
 the proper fuel for it is coal. (See ^last 
 Furnace, Glass Furnace, Brande, Davy, 
 Faraday, ^-c.) 
 
 Fusee. A mechanical contrivance for 
 equalizing the power of the main-spring of 
 a watch ; for, as the power of a spring de- 
 creases in proportion as it runs down, or in 
 proportion as its tension is diminished, it is 
 requisite that it should act upon such a wheel 
 as would make due allowance for the in- 
 equality of the spring's action ; such an one 
 is the fusee. The cut shows that as the 
 power of the spring diminishes, the chain 
 which it winds up will be on a wider part of 
 the conical fusee, consequently a less power 
 is necessary to continue the same tension on 
 the chain. A is the fusee. B the barrel 
 which contains the main-spring. 
 
 Fusible Metal, or Alloy. Darcey^s 
 Alloy. Newton's Fusible Metal. An alloy 
 which melts in the heat of boiling water. It 
 is composed of 3 parts by weight of tin ; 5 of 
 lead ; and 8 of bismuth. 
 
 Fusing Point. The degree of heat at 
 which any solid body melts. The fusing 
 points of the common metals are tin 442^*; 
 bismuth 497°; lead 612°; zinc 773°; silver 
 1173°; copper 1996°; gold 2016° ; cast- 
 iron 2786°. 
 
 Fusion. The melting of a solid substance 
 by the application of heat. 
 
GA 
 
 GA 
 
 Fust. The shaft of a column, (an old 
 word.) 
 
 Fustian. A species of coarse, thick, 
 twilled cotton, generally dyed of an olive, 
 leaden, or other dark color. The different 
 kinds of fustian are known by the names of 
 
 common fustian, or pillow, corduroy, velve- 
 rett, velveteen, and thicksett. 
 
 Fustic, or Yellow Wood. This wood is 
 the produce of the moms tinctoria, which 
 grows in the West Indies ; it is used in dyeing 
 yielding copiously a durable yellow color. 
 
 The seventh letter of 
 the English alphabet ; 
 having two sounds — a 
 hard sound before a, o, 
 and u, as in gain, go, 
 gun : and a soft sound 
 before the other vowels, 
 as in gem, ginger, dingy. 
 In old writings G is sometimes substituted 
 for c, V, and for n ; as Gains for Caius, 
 Gascon for vasco, aggelus for angelus ; also 
 Gu is occasionally put for W, as Guillaume 
 for William. 
 
 Gabion. A wicker basket, filled with 
 earth, and used in fortifications to shelter 
 men from an enemy's fire. 
 
 Gable. A triangular wall, or wood-work 
 at the end of a roof. 
 
 Gablets. Small gables ; triangular deco- 
 rations of buttresses, pinnacles, &c. 
 
 Gable Window. A window in the ga- 
 ble of a building. 
 Gage. (See Guage.) 
 Galactometer. An instrument for as- 
 certaining the specific gravity of milk. (See 
 Lactometer.) 
 
 Galaxy, or Milky Way. That long 
 luminous tract or zone, which encompasses 
 the heavens, forming nearly a great circle of 
 the celestial sphere. It is inclined to the 
 plane of the ecliptic at about an angle of 60°, 
 and cuts it nearly at the solstitial points. 
 The ancients had many singular notions as to 
 the cause of this phenomenon ; but modern 
 astronomers have long attributed it to a great 
 assemblage of stars ; and Dr. Herschel has 
 confirmed these conjectures, having dis- 
 covered, in a space about 15° long by 2° 
 broad, no less than 50,000 stars. 
 
 Galbanum, is the concrete juice of the 
 bubon galbaniferum, a shrubby plant of the 
 East Indies, Syria, and Persia, whence the 
 gum is imported. It is now but little used, 
 either in varnishing or in medicine. 
 Galena. The sulphuret of lead. 
 Galilee. A small gallery or balcony at 
 the west end of a collegiate church, from 
 which visitors might view the service beneath ; 
 in which persons did penance, &c. exposed 
 to the gaze of those beneath ; any division 
 of a church set apart for these and similar 
 purposes is called a galilee. 
 
 Galilean Telescope. A simple astro- 
 nomical telescope of two glasses only ; that 
 nearest the object being doubly convex, and 
 that near the eye a doubly concave lens, as 
 is seen in the following cut, where C is the 
 object. B the object, or field glass. A the 
 image of the object, as thrown in parallel 
 lines towards the eye by the double concave 
 lens near it : — 
 
 Gall Nut. A round, nut-shaped ex- 
 crescence, common to the oak, and occasioned 
 by the puncture of an insect. The gall nuts 
 of commerce are hard, woody, and heavy. 
 In medicinal qualities, powerfully astringent, 
 and are much used in the arts of dyeing and 
 ink making. In chemistry, their solution is 
 used as an excellent test for iron, precipi- 
 tating it of a purplish black color. 
 
 Gall op Animals, chiefly Ox Gall. A 
 secretion formed in a bladder which is at- 
 tached to the liver, and which communicates 
 with the stomach of animals. It is of a dark 
 green color, of an intensely bitter taste, and 
 of strongly alkaline propei-ties. In its na- 
 tural state it is much used by the scourers 
 of clothes, carpets, and stuffs ; and purified, 
 is of the greatest importance to miniature 
 water color painters, in increasing the bril- 
 liancy and durability of ultramarine, car- 
 mine, &c. ; and in making them lay evenly 
 on the paper or ivory, removing at the same 
 time all greasiness. 
 
 Gall of Glass, called also Sandiver, 
 is the neutral salt skimmed off the surface of 
 melted crown glass. 
 
 Gallates. Salts formed by the gallic acid 
 with the alkalis, alkaline earths, or metallic 
 
 Gallery. In architecture, a long narrow 
 room, the width of which is at least three 
 times less than its length, by which pro- 
 portion it is distinguished from a saloon. A 
 number of rooms opening into each other 
 is often called a gallery, especially if the 
 walls are decorated with fresco painting, or 
 covered with other paintings. In a mine, or 
 
GA 
 
 GA 
 
 a fortification, a gallery is merely a passage 
 from one apartment or division to another. 
 
 Gallic Acid. This acid derives its name 
 from the gall nut, from which it may be ex- 
 tracted by moistening bi-uised gall nuts, and 
 exposing them for four or five weeks to a 
 temperature of about 80°; a mouldy paste 
 is formed, which is to be squeezed dry, and 
 digested in boiling .water. It then affords a 
 solution of gallic acid, which may be whitened 
 by adding animal charcoal. Gallic acid, 
 when pure, is in the state of white needle- 
 shaped crystals, sour in taste, and of a pe- 
 culiar smell, when heated. It is very soluble 
 in hot water, and sparingly so in cold. It 
 also dissolves in alcohol and in ether. 
 
 Gallipoli Oil. An inferior kind of olive 
 oil, imported from a port so named in 
 Otranto, in Italy. 
 
 Gallipot. The name of a white, semi- 
 solid, viscid rosin, found on fir-trees. 
 
 Gallipot Varnish. Take 12 ounces of 
 pounded gallipot ; 5 ounces of white glass, 
 pounded ; 2 ounces of Venice turpentine ; 
 and 32 ounces of essence of turpentine. The 
 only use of the glass is, to prevent the union 
 of the small particles of gallipot with each 
 other, it being necessary that this should be 
 prevented, which is done by the glass inter- 
 mixing with the other ingredients. 
 
 Gally, or Galley. In printing, the frame 
 into which the compositor empties the lines 
 out of his composing stick, and in which he 
 ties up the page when completed. Common 
 galleys are made of wood, and have a flat 
 bottom, and a ledge, a little more than half 
 the height of the types, along one side, and 
 at the end. Other galleys have a ledge on 
 both sides as well as one end, with a groove 
 to admit a false bottom, called a galley slice. 
 Galvanic Apparatus. (See Battery, 
 Decomposing Apparatus, Davy, Faraday, 
 
 Galvanic Battery. Any arrangement 
 of galvanic circles, made so as to produce an 
 efiect greater than a simple circle could oc- 
 casion. (See Cruikshank, De la Rue, Grove, 
 Smee, Couronne de Tosses, Calorimotor, 
 Wollaston, <^c.) 
 Galvanic Circle. (See Circle.) 
 Galvanic Multiplier. (See Galva- 
 nometer.) 
 
 Galvanic Trough. (See Cruikshank.) 
 Galvanism. That science which explains 
 the facts and laws of a particular kind of 
 electricity, in which the fluid is put in motion 
 not by friction but by chemical means. As 
 soon as any chemical action takes place in 
 any compound, the capacity of the con- 
 stituents of the compoimd for the retention 
 of the electric fluid is altered, and that fluid 
 which was before latent becomes sensible ; 
 one portion of the compound having a capa- 
 city for more fluid ; the other being ready to 
 
 part with a portion of what it at first had. 
 These disturbances occasion re-action, so as 
 to occasion other changes ; sometimes che- 
 mical, at others mechanical or physiological. 
 The laws explanatory of the motives and pro- 
 perties of the electric fluid when thus dis- 
 turbed ; the effects which take place when a 
 current of the electric fluid is made to pass 
 through or near to a conducting substance, 
 and the arrangement and management of the 
 apparatus necessary to produce those effects 
 constitute the science of galvanism. 
 
 Galvanized Iron. A name given to 
 sheets of iron when they are tinned, by first 
 dipping them into a bath of melted zinc, and 
 when this has adhered so as to cover them 
 properly, plunging them into a second bath 
 of melted tin. Iron plates thus prepared 
 resist for a long time the effect of damp, on 
 account of the galvanic action of the various 
 metals. 
 
 Galvanometer and Galvanoscope. 
 Instruments which indicate the passage of a 
 small quantity of the galvanic fluid through 
 or around different circuits, by showing its 
 effects upon a freely-suspended magnet. The 
 only difference in the two instruments is, that 
 the latter is attended by some scale of de- 
 grees, by which the power of the fluid can 
 be exactly ascertained, the former being 
 without that scale. The cuts are therefore 
 those of galvanoscopes. The simplest form 
 of the galvanoscope is as follows, as originally 
 suggested by Schweigger : — It consists of a 
 wire bent once round a magnetic needle, as 
 A A, and terminated by a mercury cup at 
 each end, B, C, the needle being free to 
 turn horizontally on its axis. 
 
 The action of this instrument is explained 
 under Electro 'Magnetic Multiplier, where 
 
GA 
 
 GA 
 
 also another cut is given of the same instru- 
 ment. Another quite different form has been 
 given to the galvanoscope ; the needle being 
 suspended by a fine fibre of silk, and the coils 
 of wire bent so as to form four flat spirals, 
 all formed of the same wire, and consequently 
 all conveying the current in the same direction. 
 A is the stand. B the thread which supports 
 the magnetic needle. N and P the mercury 
 cups in which the ends of the coils terminate. 
 For other information, (see Gold Leaf, Rit- 
 chie, 8fc.) 
 
 GALVANOMETER,Z)/^eren^ia/. (SeeDiJ^er- 
 ential.) 
 
 Gamboge. A gum resin, the produce of 
 the garcinia gambogii, a large tree indigenous 
 to India, Ceylon, Siam, Cochin China, and 
 Cambodia. It is of a fine yellow color, when 
 diffused in water, and as such is much em- 
 ployed by painters in water colors. It is also 
 used to stain wood in imitation of box and 
 also marble ; and as a coloring ingredient in 
 lacquers and yellow varnishes. 
 
 Gargoyle. A projecting water-spout, at- 
 tached to old buildings, often grotesquely 
 carved and ornamented. 
 
 Garland. A band of ornamental work 
 around the top of a tower, &c. ; also a circlet 
 or continued wreath of flowers. 
 
 Garnet. A gem of a dark red color, of 
 which there are two kinds ; the precious gar- 
 net and the common garnet. The garnets of 
 Peru are most highly valued. The common 
 garnet is often of a brownish green color, 
 and used by lapidaries as a polishing powder. 
 
 Garnet's Friction Rollers. ''See 
 Friction Roller.) 
 
 Gas. The name of every permanently- 
 elastic aeriform substance. Gas is distin- 
 guished from steam or vapour by this cir- 
 cumstance, that vapours are raised from all 
 fluids by heat, and are again condensed by 
 cold into the same fluid form ; but gases are 
 obtained from the substances containing them 
 only by chemical decomposition, whether 
 this be spontaneous or artificial. They are 
 either not condensable, or only so when sub- 
 mitted to an excessive pressure or degree of 
 cold. Four of the gases are simple sub- 
 stances : oxygen, hydrogen, azote, and chlo- 
 rine. The rest are more or less compound, 
 as carbonic acid gas is a compound of oxygen 
 and carbon ; sulphurous gas of sulphur and 
 oxygen, &c. Gases are mostly colorless ; 
 nitrous acid gas, however, is red ; chlorine 
 and its prot and deutoxyde are of a yellowish 
 green ; the hydrochloric, hydriodic, fluo- 
 boric, and flno-silicic produce white fumes in 
 the air, and iodine violet-colored fumes when 
 heated. TTie gases which are inflammable 
 are hydrogen, and all its compounds ; carbo- 
 nous oxyde, and cyanogen. Those which 
 more or less support combustion are oxygen, 
 protoxide of azote, chlorine, and its oxydes. 
 
 Some gases are destitute of smell ; others 
 have an odour which is insupportable, and 
 often characteristic. In properties numerous 
 of the gases are acid ; some neutral ; two 
 alkaline. 
 
 Gas Coal, Oil, and Rosin. The carbu- 
 retted hydrogen extracted from bituminous, 
 fatty, or resinous substances, and which is so 
 extensively employed for purposes of illu- 
 mination ; each kind differing veiy slightly 
 from its other, and having different names 
 merely on account of the material employed. 
 The manufacture of coal gas may be stated 
 as follows : — Any kind of coal which con- 
 tains much bitumen is put into a retort ; se- 
 veral retorts, about three parts filled, are 
 placed in a furnace, and a strong fire kept up 
 around them. Each retort is furnished with 
 a small pipe, to convey into a larger pipe the 
 impure gas which the coals in the retorts 
 give off. This pipe conveys it into a cistern 
 of water, where the tar and the grosser im- 
 purities are retained. The gas passes to the 
 purifying vessel, which is filled with lime 
 water, or rather with lime so mixed with 
 water as to form a cream-like fluid, called 
 therefore cream of lime. From this vessel 
 it passes to a gasometer, where it is stored up 
 till wanted for use, when it has to pass through 
 the hydraulic valve, the gas governor, or 
 where this is not used, the gas regulating 
 valve, the main, the branch pipes, and bur- 
 ner; the gasmeter when used being placed 
 near to the burner, if for registering indi- 
 vidual consumption ; or near the gasometer, 
 if the whole quantity used is to be ascertained. 
 
 When gas is made from oil, the retorts 
 are filled with broken bricks, coke, or other 
 refractory substances ; which becoming red 
 hot, the oil is allowed continually to trickle 
 into them, when it becomes decomposed. 
 Gas of similar properties may be made from 
 peat, wood, dry vegetables, saw-dust, &c. ; 
 though being contaminated with much car- 
 bonic acid, such gas requires greater care in 
 its purification. 
 
 Gas, Portable. Coal gas, which after its 
 manufacture, is compressed by a condensing 
 or force pump into strong vessels prepared 
 to receive it. These vessels being portable, 
 the gas may thus be used where required, at 
 any distance from the gas works. 
 
 Gas Apparatus, includes the furnaces, 
 retorts, pipes, valves, pui'ifying machine, 
 lime machine, gasometers, gasmeters, gover- 
 nors, &c,, used in the manufacture, the pu- 
 rifying, and the supply of gases, particularly 
 of coal gas, as used for illumination. 
 
 Gas Bottle. (See GasRetort and Bottle.) 
 
 Gas Burner. The jet or contrivance 
 fixed to the end of a gas pipe for the purpose 
 of separating the flame, or in other words 
 for the division of the stream of gas into 
 minuter streams, that its light may be more 
 
GA 
 
 GA 
 
 diffused. Some of the more usual burners 
 and their mode of diffusing the light will be 
 seen annexed. 
 
 Gas Governor. A kind of gasmeter, 
 adopted in gas works, for equalizing the 
 pressure of gas previous to its issuing from 
 the gasometer for the supply of light, as well 
 as the inequalities arising from putting out 
 the lights at different periods of the night. 
 
 The cut shows the instrument in section. 
 A B exhibits the outer case. C an inner case, 
 made in the form of a small gasometer. D 
 the pipe by which the gas enters ; and E the 
 pipe by which it passes out. The conical 
 valve attached to the bottom of the spindle I 
 rises and falls, so as to contract or enlarge 
 the opening G, as the gasometer ascends or 
 descends by the entrance or passing out of 
 the gas ; and H is a flanch or tube to which 
 the instrument is affixed at the base. 
 
 Ga.s Holder. An instrument invented 
 by Mr. Pepys, for holding such gases as are 
 usually made the subject of experiment, or 
 for the purposes of the chemist. It consists 
 of two tin vessels ; the lower one is to hold 
 the gas, the upper one is used as a kind of 
 pneumatic trough, to hold gas jars, or other 
 apparatus. The lower vessel is closed on 
 all sides, but has a hole covered with a screw 
 on one side near the bottom ; a stop-cock 
 on the opposite side near the top ; also two 
 stop-cocks at the top, opening into the upper 
 Vessel, one of these being connected with a 
 
 long tin pipe, 
 bottom, inside. 
 
 which reaches to near the 
 A glass tube is usually put 
 
 from one end to the other, and connected 
 both at top and bottom with the vessel, by 
 which the quantity of gas within may be as- 
 certained. To use the apparatus ; first, open 
 all the cocks, then continue to pour water 
 into the upper vessel till the lower one is 
 filled ; then close all the cocks and open the 
 hole at the bottom, into which insert a tube, 
 proceeding from the retort where the gas is 
 making. When full, which will be known 
 by inspection of the glass tube, close the 
 lower hole. When the gas is to be used, 
 open the cock which has the tube reaching 
 downwards in the vessel, and pour water so 
 as to fill the upper part ; then upon turning 
 either of the other cocks the gas will issue 
 into bladders or jars placed to receive it, 
 while the water will flow down and occupy 
 its place. 
 
 Gas Hydraulic Main. The large pipe 
 or tube into which the tubes leading from the 
 various retorts are fixed, and which conveys 
 the gas to the tar vessel or cistern in which it 
 is cooled and purified from any undecomposed 
 tar. It is called the hydraulic main because 
 of its being partly filled with water. (See 
 Gas Retort. 
 
 Gas Hydraulic Valve, or Gas Hold- 
 er Valve. Tlie name given to the princi- 
 pal communication between the gasometer 
 or gas holder, (for in the gas manufacture 
 these terms are synonymous,) and the prin- 
 cipal pipe leading to the mains. Suppose 
 in the following cut, which is a section of 
 the apparatus, that A is connected with the 
 gasometer, and B the principal pipe. C is a 
 round cup or cover, which may be raised up 
 or let down upon the end of the pipe B, its 
 edges in the latter case dipping into the 
 water. It will be evident that when the 
 cup C is raised up to the position in which 
 it is represented, there will be a free passage 
 for the gas from A to B ; but when the cup 
 is let down, the water will prevent all com- 
 munication between the two pipes. Tlie 
 
GA 
 
 GA 
 
 valve may be fastened up or down by the 
 stem E, as may be found necessary. 
 
 Gas Jars. Glass jars for the holding of 
 the gases during the progress of experiments. 
 Fluoric acid gas must be retained in silver or 
 leaden vessels, as it immediately corrodes 
 glass. 
 
 Gas LiGHT; The light afforded by the 
 combustion of carburetted hydrogen gas, as 
 procured by the distillation of coal, oil, tar, 
 &c. ; therefore called coal gas, oil gas, &c. 
 
 Gas LiauoR. The liquid remaining in 
 the various parts of the apparatus of gas 
 works, after the manufacture of gas. It is 
 water much contaminated with tar, ammo- 
 nia, and sulphuretted hydrogen, as such it is 
 very offensive in odour, and injurious to fish 
 when suffered to escape into the ponds and 
 rivers where they abound. It is also dele- 
 terious to vegetation. (See Ammoniacal 
 Liquor.) > 
 
 Gas Main. The principal pipes which 
 conduct the gas from the gas works to the 
 places where it is to be consumed. 
 
 Gasmeter. An instrument for ascer- 
 tadning the quantity of gas that passes through 
 it, and thereby affords the consumer and 
 supplier a correct means of ascertaining the 
 consumption. The apparatus, as seen in 
 section, is as follows : — 
 
 A A is a cylindrical box of tin, within 
 which revolves a second cylinder, supported 
 by the axis C, and consisting of two circular 
 channels, concentric to each other. The 
 larger or outer chsmnel is divided into three 
 compartments, by cross plates of tin, and 
 opens into the outer vessel by means of 
 valves, as represented ; while three of the 
 compartments of the inner vessel open into 
 them in like manner, though the valves are 
 at a different end. These valves are marked 
 AAA and B B B, The action of the ap- 
 paratus is as follows : — Suppose it to be filled 
 to about an inch above the centre with water, 
 and the gas to enter at the centre, the pipe 
 which admits the gas being turned up a little, 
 so as to be above the surface of the water ; 
 then the gas would fill the upper small com- 
 partment, and passing through the inner 
 valve B would soon fill the left-hand large 
 compartment, and as it fills, that side of the 
 wheel would rise, until at length the gas would 
 escape by the outer valve, which is now at 
 the bottom of the case, but which would 
 then be above the water. The gas, therefore, 
 would be discharged by the pipe E to the 
 burner, while the action would go on with 
 the next division of the wheel. The num- 
 ber of revolutions of the wheel is registered 
 by a train of wheel- work at the side, or dial 
 at the top, and the capacity of the case being 
 known, the quantity of gas consumed is 
 easily ascertained. 
 
 Gasometer. A case of iron, tin, copper, 
 &c. so constructed as to hold gas, and at the 
 same time to enable a person to ascertain the 
 quantity collected. It is formed of two 
 cases, one fitting loosely within the other ; 
 the outer one being open at the top, the inner 
 one open at the bottom. The outer case 
 ought to have a cock near the bottom, with 
 a pipe attached to it, which extends half 
 way across the bottom, and up the middle. 
 The inner case is supported by cords and 
 counterpoise weights, and bears a graduated 
 rod, passing through a hole made in a frame, 
 connected with the outer vessel. The cock 
 
GA 
 
 GA 
 
 is opened, the whole instrument filled with 
 water, the inner case forced down into the 
 water ; the pipe from the retort is attached 
 to the cock, the gas ascends, and occupying 
 the inner vessel, raises it a certain height, 
 according to the quantity of gas introduced, 
 and which is indicated by the guage rod. 
 The gas may be drawn off by the same cock, 
 by another similarly situated, or by a cock 
 at the top of the instrument. 
 
 Gas Purifier, Purifying Machine, 
 or Lime Machine. A vessel into which the 
 coal gas enters from the retorts, after passing 
 through the vessel of cold water into which 
 it first enters. The purifier is intended to 
 deprive the impure gas of its sulphuretted 
 hydrogen, and thus to take from it the bad 
 smell which it has at first. There are nume- 
 rous forms given to the instrument ; the fol- 
 lowing is one of the simplest : — It represents 
 a tin or iron circular vessel, closed at both 
 ends. B B and C C are two shelves, which 
 slope downwards, and pass round the vessel. 
 A is a pipe, which extends very nearly to the 
 bottom. D D are two circular shelves, put 
 upon and fixed to the centre pipe A. E is a 
 pipe to fill the vessel with liquid. F the pipe 
 to convey away the purified gas. G and H 
 cocks to empty the vessel when requisite. 
 Nearly the whole of the purifier is filled with 
 the cream of lime ; that is, with lime and 
 water so mixed together, as to be a cream- 
 like substance. The impure ^s enters by 
 the centre pipe, passes round the lower shelf 
 D, and then gradually upwards, according to 
 the arrows, until it escapes by the pipe F. 
 
 Gas Register, is a simple instrument 
 for indicating and registering the impurities 
 of coal gas, and also the times when they 
 occur. 
 
 The instrument consists of a circular card, 
 which is connected with a time-piece, so as 
 to turn round once in 24 hours. The card 
 is divided into 3 circles, each of which is 
 subdivided into 24 compartments, one for 
 each hour of the night and day. The inner 
 circle has the numbers of the hours printed 
 upon it. The next circle is coated with any 
 test for ammonia. The third or outer circle 
 with a test for sulphuretted hydrogen. Oppo- 
 site each of the two larger circles a fine jet 
 
 of gas is made to play, and of course, if 
 contaminated, it will show the time and de- 
 gree of that contamination by the change of 
 color on the coated circles. 
 
 Gas Regulating Valve. A valve which 
 is sometimes used instead of, or in addition 
 to the gas governor. Suppose B in the 
 following cut to be the section of the gas 
 main. A is a plate of metal, which fits in a 
 channel in the manner of a damper, or slides 
 over the mouth of the pipe. This plate of 
 metal is attached to a rod, which projects 
 upwards as shown. The portion of circle 
 which is black is for the passage of the gas. 
 There is a guage C connected with the gas- 
 ometer, and another D connected with the 
 main beyond the valve, so that the workman 
 by raising or depressing the valve can regu- 
 late the pressure according to circumstances. 
 
 r , - ■- - ■- '■' B 
 
 - 
 
 
 i- 
 
 ; 
 
 so 
 
 f 
 
 50 
 
 
 ^ 
 
 40 
 
 1 
 
 ^ ■ so^ 
 
 iSO 
 
 n^ i 
 
 lie i 
 
 m 
 
 20 
 
 1 
 
 
 f^^^rt 
 
 1 
 
 "^^p 
 
 i 
 
 i 
 
 Gas Retort. A vessel used for holding 
 the coal or other material of which gas of any 
 kind is to be made. Sometimes the common 
 glass retort used by the chemist, is sufficient, 
 as in the making of chlorine, fluorine, and 
 other gases. For hydrogen it is usual to em- 
 ploy a peculiar-shaped bottle, (for the form 
 of which see Bottle.) For oxygen an ear- 
 thenware retort may be used, or else an iron 
 
GA 
 
 GA 
 
 retort, formed like a common wine bottle. 
 For the manufacture of coal gas, the retorts 
 are of iron and formed cylindrical, or of some 
 other elongated shape. The following cut, 
 (No. 1,) shows a coal gas retort, the man- 
 ner in which it is set in the furnace, and 
 the pipe which conveys away the gas that 
 arises. No. 2 shows a front view of several 
 retorts, as set in the furnace. The pipe of 
 each screwing to the same hydraulic main. 
 
 A is the retort. B the fire. C the gas 
 pipe. D the hydraulic main, which leads the 
 gas into the purifying vessels. A number of 
 retorts put together in the same furnace is 
 called a bench of retorts. 
 
 Gas Transferrer. A small instrument 
 invented by Mr. Pepys, for the conveyance 
 of a small quantity of gas 
 from one vessel to another. 
 It consists of a glass tube, 
 shaped as in the cut, both 
 ends being open, and one 
 of them drawn to a fine 
 point. A tight piston and 
 rod fits into the straight 
 part of the tube. All the [Qj 1 1 
 
 partsof the instrument be- \( \j 
 
 low the piston are filled ^^^=:: rr. ^ 
 
 with mercury. To use the instrument, im- 
 merse it in a jar of gas, by passing the point 
 upwards through the mercury in the mer- 
 curial trough. Draw up the piston, which 
 will draw up the mercury also, and suffer the 
 gas to enter the point of the transferrer. 
 When enough gas has entered, depress the 
 point below the surface of the mercury, and 
 eltivate the piston a very little to draw a glo- 
 bule of mercury into the fine orifice. When 
 this has been done, the instrument may be 
 taken out, and the gas it contains be carried 
 ■\vhere it may be required. 
 
 Gas Works. The manufactory at which 
 coal gas is made for public purposes, together 
 with the whole machinery and apparatus, are 
 included under the term gas works. 
 
 Gauge, is the name employed to denote 
 various instruments used for measuring. 
 
 Gauge, Air Pump. To the larger kinds of 
 air pumps are usually fixed what is called a 
 
 barometer gauge, which is a tube of glass 
 nearly 3 feet long, open at both ends, the 
 upper end passing through the plate of the 
 pump so as to be in connection with the re- 
 ceiver, the lower end dipping into a basin of 
 mercury. As the air in the receiver becomes 
 exhausted,, the mercury is driven up the tube 
 by the pressure of the atmosphere on the 
 fluid in the basin, and according to the 
 height of the column of mercury, so is the 
 degree of exhaustion ascertained. To small 
 air pumps a syphon gauge is used ; when this 
 is the case it is fixed on another plate dis- 
 tinct from that on which the receiver stands. 
 
 Gauge, Barometer. (See Air Pump 
 Gauge.) 
 
 Gauge, Carpenter'' s. An instrument con- 
 sisring of a shoulder and rod, which is made 
 to slide backwards and forwards through its 
 centre, there being a projecting point on the 
 underside of the rod. It is used for scribing 
 or marking, by means of the point, a line 
 parallel to the edge of a board, along which 
 the shoulder of the instrument is carried. 
 The following is a superior instrument in- 
 vented by Mr. Palmer, which is capable of 
 dividing a board or other body into exactly 
 two equal parts by a line drawn down it. It 
 consists of two sides or shoulders, B and D, 
 one of them having a screw C upon it. A 
 is the ann or rod. E F is a jointed hinge of 
 brass attached at either end to the shoulders. 
 H is a screw, terminated by a sharp point 
 beneath. If this instrument be placed on a 
 board so that its two edges grasp the sides, 
 and it be drawn along the point H, it will 
 mark a line exactly intermediate between 
 those sides. 
 
 Gauge Cocks. Tlie cocks usually con- 
 nected with the boilers of steam engines, 
 for the purpose of ascertaining the height of 
 water in the boilers ; glass tubes are also 
 sometimes employed for the same purpose, 
 not only in steam boilers, but to stills, stand- 
 ing casks partly filled with a liquid, &c. 
 Also, there is often attached to a steam engine 
 boiler a bent glass tube, open at each end, 
 and partly filled with mercury ; this is called 
 the steam gauge, and answers a double pur- 
 pose. First, as a safety valve ; and secondly, 
 as an instrument whereby to ascertain tlift 
 
GA 
 
 GA 
 
 pressure of the steam. Both these are re- 
 presented in the following cut : — 
 
 Besides these gauges, there are often others 
 adapted to particular purposes, as the gauge, 
 or graduated bent iron tube, attached to the 
 condenser of an engine, which indicates the 
 degree of condensation within. 
 
 Gauge, Pressure. An instrument to de- 
 termine the pressure exerted in hydrostatic 
 or pneumatic machines, as the hydrostatic 
 press, the air pump, steam engine, &c.' 
 When the pressure is very great, it is usual 
 to measure it by the compression of a certain 
 quantity of air contained in a tube of suffi- 
 cient strength. The following is a guage of 
 this description : — It is a glass tube closed 
 at one end, and with a ball near the other 
 end, which fits to the apparatus or engine. 
 The ball, under the ordinary pressure of the 
 atmosphere, should be about three-quarters 
 full of mercury, and the whole capacity of 
 the ball may be about twice that of the tube 
 beyond it. The tube is placed in a hori- 
 zontal position, and graduated with numbers 
 in geometrical progression. Thus, if the 
 tube be full of air under ordinary pressure, 
 the air will be compressed to No. 2 under a 
 pressure of two atmospheres ; to No. 4 
 with four atmospheres ; and so on to the 
 end. One-sixteenth of an inch is sufficient 
 for the internal diameter of the tube, and it 
 may be 6 or 8 feet long. 
 
 Gauge, Bain. (See Pluviometer.) 
 
 Gauge, Tide. (See Tide.) 
 
 Gauge of Way, or Railway Gauge. 
 The width in the clear between the top 
 flanches or rounded rims of the rails. Tne 
 gauge of way generally employed, and that 
 adopted on the London and Birmingham, 
 Grand Junction, and other great lines of 
 railway, is 4 feet 83- inches ; but it is made 
 7 feet on the Great Western. 
 
 Gauge Point of a Solid, is used to de- 
 note the diameter of that circle, or the di- 
 agonal of that square, whose area is ex- 
 pressed by the same number as is equal to 
 the number of cubic inches in the solid. 
 Thus, 18-79 being nearly the diameter of a 
 circle whose area is 277*274 ; this is called 
 tJie circular gauge point of the gallon, which 
 
 contains that number of cubic inches : and 
 16*6515 is the square gauge point of the 
 gallon — this last number being multiplied by 
 itself, forming 277*274. Gauge points are 
 marked on the gauge rule by certain letters 
 or characters. Elliptical, conical, and pris- 
 moidal vessels, have also gauge points adapted 
 to them. 
 
 Gauge, Syphon. A name given to any 
 gauge which is made in the form of a syphon ; 
 that is, with two legs bent upon each other — 
 such as that of the steam gauge, the conden- 
 ser gauge, &c. 
 
 Gauging. The art or act of measuring 
 the capacities of all kinds of vessels, and 
 thence ascertaining the quantity of liquor 
 which they contain. 
 
 Gauging, or Diagonal Rod, is a rod or 
 rule for determining the contents of casks, by 
 measuring the diagonal only ; viz. the diag- 
 onal from the bung to the extremity of the 
 opposite stave, next the head. It is a square 
 rod, having 4 faces or sides, being usually 
 4 feet long, and folding together by means of 
 joints. Upon one face of the rule is a scale 
 of inches ; upon the opposite face is a scale 
 of gallons. To use tiie rule : — Unfold it, 
 and put it into the bung-hole ; inserting it so 
 as to take as long a line as possible with it 
 within the cask. Note the inches and parts 
 up to 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 annexed 
 to them are found the contents in gallons. 
 
 Gauging Rule, is a sliding rule, par- 
 ticularly adapted to the purposes of gauging. 
 It is a square rule, about 12 inches long, made 
 of box wood ; of four faces or sides, which 
 are furnished with sliding pieces, running in 
 grooves. The lines upon them are mostly 
 logarithmic ones or distances which are pro- 
 portional to the logarithms of the numbers 
 placed at their ends. 
 
 Gauze. A thin transparent muslin. 
 
 Gauze Wire Cloth, or Wire Gauze. 
 A kind of open cloth, made of copper, brass, 
 or iron wire, of different degrees of fineness ; 
 used for the covering of meat safes, for wire 
 blinds, sieves, safety lamps, &c. 
 
 Gavkl. (See Gable.) 
 
 Gazolyta, or Gazolytes. Anamegiven 
 by Berzelius to such simple gases as are 
 permanently elastic. These are oxygen, ni- 
 trogen, and hydrogen. 
 
 Gearing, or Gear. Any series of large 
 wheels working into each other. According to 
 the position of the teeth of the wheels, or 
 the purpose which the whole is intended to 
 serve, so different names are added ; thus we 
 say, mill gearing, crane gearing, crown, be- 
 velled, spur gearing, &c. If the series be of 
 small wheels, the whole is called a move- 
 ment ; thus we say a clock movement, and 
 not clock gearing. 
 
GE 
 
 GE 
 
 Gelatin, or Gelatine. An animal sub- 
 stance, soluble in hot water, capable of as- 
 suming a well-known elastic or tremulous 
 consistence by cooling when the water is not 
 too abundant, and liquifiable again by in- 
 creasing its temperature. This last property 
 distinguishes it from albumen, which becomes 
 consistent by heat. It is precipitated in an 
 insoluble form by tannin. Glue and isinglass 
 are examples of gelatin. 
 
 Gem. a jewel ; a precious stone of any 
 kind. The principal gems are the diamond, 
 ruby, sapphire, emerald, chrysolite, hyacinth, 
 tourmaUn, opal, cornelian, onyx, topaz, 
 turquoise, beryl, amethyst, blood stone, cal- 
 cedony, jasper, garnet, cat's-eye, agate, &c. 
 
 Gem, Artificial. A kind of glass, so dense 
 and hard as to refi-act the rays of light in the 
 same manner as the precious stones, such 
 glass being colorless when intended to imitate 
 the diamond, or of appropriate colors when 
 intended to represent other gems. {SeePaste.) 
 
 Gem Cutting. (See Lapidary.) 
 
 Gemini. One of the northern zodiacal 
 constellations, denoted by the character n . 
 
 Generant. That which is generated or 
 supposed to be generated, by the motion of 
 any point, line, or figure ; for example, a 
 circle which revolves rapidly on any diameter, 
 generates a sphere ; a line moved steadily 
 along forms a surface. The circle and line 
 are therefore gene rants. 
 
 Generated. In mathematics, formed or 
 occasioned by motion, as a line is generated 
 by a point ; a solid by a surface ; and so on. 
 In the fluxional analysis aU kinds of quanti- 
 ties are supposed to be generated by the mo- 
 tion of other quantities. 
 
 Gentianin. The peculiar principle of 
 gentian. 
 
 Geocentric. Having the earth for a cen- 
 tre, as the moon. The planets moving round 
 the sun as a centre are not geocentric, yet we 
 speak of their geocentric places, latitudes, 
 longitudes, &c., meaning thereby as they 
 appear when viewed from the earth's centre. 
 
 Geodes. a kind of aetites, the hollow of 
 which, instead of a nodule, contains only 
 loose earth, and is commonly lined with 
 crystals. 
 
 Geodesia. That part of geometry and 
 trigonometry which appUes to the measuring 
 of whole countries or very large tracts of 
 land, or to the admeasurement of a degree of 
 the meridian. Originally the term geodesia 
 was considered as synonymous with land 
 surveying. 
 
 Geognosy. Synonymous with geology. 
 
 Geography. The science which describes 
 the surface of the earth, and in its more ex- 
 tended sense of its inhabitants also. It is 
 divided into physical geography, which ex- 
 plains the cause and result of the earth's 
 motions as a planet, and the effect produced on 
 
 its surface by the influence of the other hea- 
 venly bodies, such as the tides, seasons, 
 currents, winds, its shape, &c. ; descriptive^ 
 which gives an account of the climate, aspect, 
 surface, appearance, and natural boundaries 
 of different parts of the earth's surface. 
 Political geography treats of the inhabitants, 
 their institutions, languages, arts, customs, 
 civilization, relative importance, religion, ar- 
 tificial boundaries, produce of countries, &c. 
 
 Geology. That part of natural philosophy 
 which explains the structure and formation 
 of the earth beneath the surface, as to its 
 rocks, soils, minerals, &c. ; searching into 
 those different changes which have taken 
 place in it in these respects, as well as the 
 causes which have modified, and are now 
 modifying the surface and crust beneath, such 
 as volcanoes, currents, atmospheric pheno- 
 mena, the agency of man, &c. 
 
 Geometry. The science which explains 
 the proportions, properties, and measurement 
 of Imes and surfaces. Geometry is divided 
 into several parts ; as elementary, which 
 describes right lines, figures, and the proper- 
 ties of the circle ; the propositions of which 
 part is called theoretic, when any thing is to 
 be proved ; and practical when any thing is 
 to be done. There is also the geometry of 
 the compass, which is a part of the science, 
 the practice of which is entirely performed 
 by the aid of the compasses only. Descriptive 
 geometry is a name given to that part of 
 practical geometry which ascertains the in- 
 clination and particular form of the lines 
 produced by curved surfaces cutting each 
 other ; as for example in groined and vaulted 
 ceiUngs, &c., the higher or transcendental 
 geometry is that which treats of the higher 
 order of curves and problems. 
 
 Geometrical. Any thing relating to the 
 science of geometry. 
 
 Geometrical Elevation. In archi- 
 tecture, a design for any part of a building 
 drawn according to the rules of geometry, 
 as opposed to the perspective or natural 
 elevation. If of sufficient size to guide the 
 working builder, it is called the working 
 plan or drawing. 
 
 Geometrical Focus. (See Focus.) 
 
 Geometrical Pace. A measure of 5 
 feet. 
 
 Geometrical Pl^ne. In perspective, 
 the same as ground plane. (See Ground 
 Plane.) 
 
 Geometrical Progression and Pro- 
 portion. A series of numbers is said to 
 be in geometrical progression when they have 
 a common ratio or multiplier : thus, multiply 
 1 by 2, and the number produced by 2 again, 
 and the second result by 2, the numbers re- 
 sulting will consequently be in geometrical 
 progression. The series will, of course, be 
 1, 2, 4, 8, 16, 32. 
 
GI 
 
 Geometrical Solution. That result 
 which is obtained from the simple principles 
 of geometry. 
 
 Geometrical Staircase. A staircase is 
 so called when the stairs are supported only 
 by being inserted into the wall at one end, 
 with a continued range of ballisters at the 
 Other. 
 
 Georgium Sidus. (See Herschel.) 
 
 Germination. The vital development of 
 a seed when it first begins to grow. 
 
 Gibbet. That part of a crane which sus- 
 tains the weight of goods. 
 
 Gibbous, generally denotes a convexity or 
 protuberance. The moon is called gibbous 
 when in her second and third quarter, being 
 then protuberant or convex on both sides, 
 and not a crescent as in the other two quar- 
 ters. 
 
 Gig Wheel. A mill in which the nap of 
 woollen cloth is raised by the application of 
 teasles. 
 
 Gilding. The art of laying gold on any 
 surface by way of ornament. The art of 
 gilding is performed either upon metals, or 
 upon wood, leather, parchment, or paper. 
 There are three distinct methods in general 
 practice, namely, wash or water gilding, in 
 which the gold is first mixed with mercury, 
 then this amalgam rubbed over the article, 
 and afterwards the mercury driven off by 
 heat, when the gold remains ; this method 
 is only applicable to metals. Leaf gilding, 
 either burnished, or in oil, is performed by 
 cementing leaves of gold upon the work, 
 either by size, or an oily varnish, called gold 
 size. Japanner's gilding, in which gold dust 
 or powder is used instead of gold leaf. 
 
 Gilding Metal. An alloy composed of 
 4 parts of copper, 1 part of Bristol old 
 brass, and 14 ounces of tin, to every pound 
 of copper. This alloy takes a fine polish, 
 and as such is much used for common 
 jewellery. 
 
 GiMBOLS. Brass rings, by which a com- 
 pass box is suspended, in order that it may 
 have freedom of motion,j so as to swing 
 easily in every position of the ship, and thus 
 to preserve itself horizontally, when all around 
 is agitated by the pitching and tossing of the 
 vessel. They are applied also to numerous 
 pieces of machinery, and will be understood 
 by the following cut ; the one gimbol al- 
 lowing motion in one direction, and the 
 other gimbol allowing it in the opposite. 
 
 II n il I I - i . . ■ ^ 
 
 Gm. A jack, crane, pile engine, or any 
 other machine used for raising great weights, 
 is called a gin. 
 
 Ginning. The operation by which the 
 filaments of cotton are separated from the 
 seeds previous to the cotton being manu- 
 factured. 
 
 Girder. The main beam of a floor. 
 
 Girdle. A small circular band around 
 the sliaft of a column. 
 
 Girt. The circumference of any thing, as 
 the girt of a column, of a tree, &c. Girt is 
 also used as synonymous with fillet. 
 
 Given. A word used by geometricians to 
 denote any thing which is known. Thus, if 
 a magnitude be known it is said to be a 
 given magnitude. 
 
 Glaire. The white of eggs beaten up 
 with water until it assumes a varnish-like 
 consistence ; is used for many purposes in 
 the arts. As for example, to communicate a 
 polish to kid leather shoes ; to the covers of 
 books ; and often as a varnish for pictures : 
 in which latter case it is advisable to add a 
 small quantity of white sugar. It is laid on 
 with a sponge. 
 
 Glacial. Appearing like ice. 
 
 Glacial Acetic Acid, is this acid when 
 it exists in a crystalline state, as it does when 
 pure, united to an exact quantity of .water, 
 and subjected to cold. 
 
 Glacial Phosphoric Acid, is the phos- 
 phoric acid mixed with a certain definite 
 proportion of lime. "When bones are dis- 
 solved in sulphuric acid and water, the re- 
 sult is two compounds ; one a sediment of 
 sulphate of lime, the other a transparent 
 liquid. If this last be evaporated, it yields 
 a second sediment of the quadriphosphate of 
 lime, in the state of a white powder. Upon 
 placing this in a crucible, it fuses into glassy 
 scales, called glacial phosphoric acid, or glass 
 of phosphorus. It is this substance from 
 which phosphorus is made. 
 
 Glacial Sulphuric Acid. When sul- 
 phuric acid is procured by the distillation of 
 green vitriol, it is frequently observed that a 
 portion concretes into a white mass of radi- 
 ating crystals. This has been called glacial 
 or fuming sulphuric acid, and is supposed to 
 be the acid in an anhydrous state, or without 
 water. 
 
 Glacis. An insensible slope or declivity. 
 
 Glance Coal. Anthracite, (which see.) 
 
 Glance Cobalt. A sulpho-arseniuret of 
 cobalt ; an ore of cobalt, found in Funaberg, 
 in Sweden. 
 
 Gland. A contrivance for engaging and 
 disengaging machinery, moved by belts or 
 bands. 
 
 A, B, are two spindles, one of which is in- 
 tended to turn the other. Upon one is 
 fastened a pulley C, which fits on to a part 
 of the spindle B, the part where it fits being 
 
 
GL 
 
 GL 
 
 <;ut square. The pulley C may, by means 
 of a handle, be moved backwards and for- 
 wards, and it has upon it two studs or pro- 
 jecting pieces D, E. Upon the other spindle 
 
 is the gland F, which is merely a strong cross 
 piece either of wood or metal. As soon as 
 the pulley is moved towards it, the gland 
 takes hold of the projecting pieces, and is, 
 with its spindle, thereby turned round equally 
 with the other spindle. 
 
 Glass. An artificial transparent substance, 
 made by fusing various salts and metallic 
 oxydes with siUcious earths. There are several 
 distinct species of glass at present manufac- 
 tured. Flint glass, which is composed of 
 purified white sand, or else flints calcined and 
 powdered 100 parts ; litharge or red lead 60 
 parts; pearlash 30 parts. Plate glass. — 300 
 lbs. of fine sand ; 200 lbs. of soda ; 30 lbs. 
 of lime ; 2 lbs. of magnesia ; 3 oz. of cobalt 
 azure ; 300 lbs. of fragments of good glass. 
 Crown, or best window glass. — 300 parts of 
 soda; 300 parts of fine sand; 33 parts of 
 lime ; 250 fragments of glass. Green window, 
 or broad glass. — 11 lbs. of dry Glauber salt; 
 10 lbs. of soda ; half a bushel of soap makers' 
 waste ; 50 lbs. of sand ; 22 lbs. of glass pot 
 skimmings ; 1 cwt. of broken green glass. 
 Bottle glass. — White sand 100 parts ; kelp, 
 from 30 to 40 parts ; lixiviated wood ashes, 
 from 160 to 170 parts; fresh wood ashes, 
 from 130 to 140 parts ; potters' clay, from 
 80 to 100 parts ; cuUet or broken glass 
 100 parts. Glass for imitating gems. (See 
 Pastes.) 
 
 Glass Annealing Furnace, is an ex- 
 ceedingly long semi-cylindrical oven, with 
 one, two, or more large iron shelves, which 
 extend and present an even surface from one 
 end to the other. One extremity of the oven 
 is heated to such a degree as nearly to make 
 the glass red-hot ; the other extremity is 
 open to the air, consequently there is a 
 gradual diminution of heat throughout. The 
 glasses to be annealed are placed in iron 
 trays : each tray as it is filled is put into the 
 hot end, the workman making room for it 
 by pushing the other trays along the shelf. 
 Having just before taken away the last tray 
 from the cool end of the shelf, the glass in 
 its passage through the whole oven will be 
 submitted to the requisite heating and cool- 
 ing. The following is an internal view of 
 the furnace, the open end being nearest the 
 eye; the further end being inclosed by doors 
 
 to confine the heat in that part, having also 
 a furnace beneath it : — 
 
 Glass, Annealing of. Glass when it comes 
 from the hands of the blower is exceedingly 
 brittle, and unfit to bear sudden changes of 
 temperature. To render it more tough it is 
 placed in an oven, where it is first heated, 
 and afterwards suffered to cool very gradually, 
 by which gradual cooling, called annealing, 
 the purpose is accomplished. 
 
 Glass Blower's Furnace. The fur- 
 naces which are used in the manufacture of 
 the various kinds of glass are constructed 
 upon principles and in forms very difi*erent 
 from other furnaces. The following cut ex- 
 hibits one of the furnaces as employed in the 
 manufacture and blowing of flint glass : it is 
 a circular brick building, having a number of 
 doors or apertures around its sides, each like 
 the door of an oven. It is contracted into a 
 dome at the top, with a small chimney above. 
 Sometimes the fuel is cast into the chimney ; 
 at others there are fire-places in the story 
 beneath. To each door there is a glass pot, 
 or crucible, full of the melted metal, and a 
 workman belongs to each of these pots, so 
 that the furnace affords materials to as many 
 workmen as there are openings in the side ; 
 these openings may be six, eight, or more in 
 number. The whole is of course lined with 
 fire brick. 
 
 Glass Blowing. The art of converting 
 melted glass into the form requisite for the 
 various utensils made from it. It is performed 
 by the workman taking in hand a long hoi- 
 
GL 
 
 low tube of iron, called a blow-pipe ; dipping 
 this into the glass pot, it will take up a por- 
 tion of the melted glass, or metal, as it is 
 called by the workmen : then being withdrawn 
 from the furnace, with the metal attached to 
 it, the workman blows into the opposite end 
 of the tube ; the metal yields to the impulse 
 of the breath, swells out like a bladder 
 would under similar circumstances, and be- 
 comes a round hollow ball, which the work- 
 man fashions by roUing, pressing, and bend- 
 ing, while in a fluid state, into any required 
 shape or size. 
 
 Glass, Colored. In colored glass, the 
 whole body of the material is tinged through- 
 out by means of some coloring ingredient 
 uniformly diffused through, or dissolved in 
 the substance of the glass. The following 
 are the substances used at the glass houses : — 
 A blue color is given by oxyde of cobalt. 
 Green by the oxyde of iron or of copper. 
 Violet by the oxyde of manganese. Red by 
 a mixture of the peroxyde of iron and of 
 copper. Purple by the purple oxyde of 
 gold. White by the oxydes of arsenic and 
 zinc. Yellow by the oxyde of silver. The 
 coloring of glass in the manufacture is ac- 
 complished by adding to the melted glass in 
 the glass pot a portion of the above ingre- 
 dients. 
 
 Glass Cutting. The process by which 
 glass may be cut or ground into numerous 
 ornamental forms. 
 
 Glass Drops. (See Ruperfs Drops.) 
 Glass, Etching on. (See Etching.) 
 Glass, Frosting of. The art by which 
 glass is made to assume an opaque appearance. 
 This effect may be produced in various ways. 
 First, by grinding it with sand and water, by 
 means of a large cork held in the hand. 
 Second, by the same materials while the ar- 
 ticle is turning in a lathe. Third, by sub- 
 mitting it to the fumes of fluoric acid and 
 water. Fourth, by washing over it some 
 semi-transparent substance, either common 
 paste, a solution of gum tragacanth, &c. 
 Glass Gall. (Sea Gall of Glass.) 
 Glass of Antimony. A brown glass-like 
 substance, consisting of the protoxyde and 
 sulphuret of antimony, and procured by 
 roasting sulphuret of antimony over a slow 
 fire till it emits no fumes, and then melting 
 it in a brisk fire till it assumes the appearance 
 of glass. 
 
 Glass of Phosphorus. (See Glacial 
 Phosphoric Acid.) 
 
 Glass, Painting of, is of two kinds ; in 
 one the colors merely cover the surface, from 
 which they may be afterwards removed, sudh 
 as the painting of magic Ian thorn sliders, 
 and occasionally, the glass of windows. This 
 process is as simple as coloring upon paper ; 
 in the commoner kinds of it colors are rarely 
 placed upon each other ; in the better pic- 
 
 GL 
 
 tures the colors are blended according to the 
 talent of the artist, the plate of glass upon 
 which he paints being supported upon a 
 frame with a strong light behind it, the efiect 
 being ascertained by looking through the glass. 
 The colors used are all transparent, and 
 must be mixed with poppy oil, mastic varnish, 
 and turpentine, or the two latter menstrua. 
 The following colors are appropriate for the 
 purpose : — Prussian blue, verdigris, Indian 
 yellow, the lakes, carmine, burnt sienna, 
 umber, &c. The second method is by the 
 aid of vitrifiable colors, (see Glass Staining,) 
 which are burnt in, the outline being first 
 sketched with turpentine, mixed with Indian 
 ink, or umber. 
 
 Glass Pot. The crucible in which the 
 materials of glass are melted and kept in the 
 furnace. It differs from the common crucible 
 or melting pot, in being covered over at the 
 top and open on the side. Thus, the fuel 
 is not liable to fall into it ; and the side hole 
 allows the workman to take out the materials 
 more readily than he could otherwise do. 
 
 Glass Proofs. (See Bologna Phials.) 
 
 Glass, Silvering of. (See Silvering.) 
 
 Glass Soap. The name given by the 
 glass blower to the black oxyde of manga- 
 nese. 
 
 Glass, Soluble. A simple silicate of pot- 
 ass or soda, which unites perfect solubility 
 in boiling water to some of the general pro- 
 perties of common glass. 
 
 Glass, Staining of, is the communicating 
 to glass a certain tint or stain, by laying 
 a properly prepared liquid upon the surface, 
 and afterwards submitting the glass to such 
 a degree of heat as to occasion the liquid to 
 penetrate into the texture of it, thereby 
 staining it of a certain color in such a manner 
 that the stain cannot afterwards be removed. 
 Glass may thus be wholly covered, or only 
 partially, exhibiting therefore in the latter 
 case various devices, or a picture. All the 
 preparations for this art contain silver in 
 some form or other. A yellow is produced 
 by equal parts of carbonate of silver and 
 yellow lake ; lay it on thin. In orange, 
 take pure silver, in powder, 1 part ; lay it on 
 thin. For red, take of antimonial silver, 
 prepared by melting together 1 part of silver 
 and 2 of crude antimony, and pulverising 
 the mass, 1 part ; colcothar 1 part ; lay it 
 on thick. Green is formed by copper, in 
 powder, 1 oz. ; black lead 1 oz. ; and 4 oz. 
 of white lead, all calcined together ; and 
 then adding saltpetre one-fourth part. Azure, 
 purple, and violet, are prepared in a simliar 
 manner to green, omitting the copper, and 
 in its stead using sulphur for azure ; perig- 
 neau for purple ; and both these drugs for 
 violet. 
 
 Glass Worker's Table. A table fitted 
 up with double bellows, blow-pipe, jet, 
 
GL 
 
 GL 
 
 lamp, &c. for the use of those who manu- 
 facture small articles in glass, such as ther- 
 mometers, test tubes, ornamental objects, &c. 
 The materials used are glass rods and tubes, 
 of different colors and sizes. The apparatus 
 is merely intended to produce a steady and 
 intense heat, that the glass tubes may be 
 softened in a manner proper for the artist to 
 bend and blow them into the required form. 
 
 A in the cut is a jet, from which issues 
 the current of air. B is the lamp, which 
 has a long large wick ; the flame from this 
 is driven to a point by the agency of the 
 current of air. C is a tube communicating 
 between the jet A and bellows D. E is the 
 treadle to work the bellows. 
 
 Glauber's Apparatus. Synonymous 
 with Woolf s apparatus, (which see.) 
 
 Glauber Salt. Native sulphate of soda. 
 
 Glaze. Glazes are either polishing or vi- 
 trifiable. The polishing glazes, and which 
 are mostly attached to a lathe or revolving 
 spindle, are made of round pieces of wood, 
 covered with buff leather, then with glue, and 
 finally with emery powder, putty powder, or 
 other similar polishing ingredients. These 
 being prepared are made to revolve in the 
 manner of a grindstone, and the article to be 
 glazed is held against the edge. Glazes for 
 earthenware are of various kinds. Common 
 salt affords a cheap glaze for ordinary articles. 
 Another common glaze is 10 parts of litharge 
 and 4 parts of ground flints. Those recom- 
 mended for fine work are first, a compound 
 formed by equal parts of lead and tin kept 
 in fusion until completely oxydated. Second, 
 calcined flint 8 parts ; ground porcelain 15 
 parts ; crystals of calcined gypsum 9 parts. 
 
 Glazing has four distinct meanings. 
 First, the process of placing the panes of 
 glass between the frames of windows, doors, 
 &c., where it is to remain. Second, the art 
 of communicating a glass -like appearance to 
 an article ; for example, pottery and china- 
 ware, by means of a substance, called a 
 glaze. Third, the polishing of a metallic, 
 wooden, or stone surface, by the friction 
 against it of a polishing powder. Fourth, 
 glazing in the arts signifies the overlaying or 
 
 finishing of pictures in oil with brilliant and 
 pellucid colors, intended to soften the paint- 
 ing, and by blending the colors before laid 
 on to give it tone and harmony. 
 
 Gliadine. a name cjiven occasionally to 
 the gluten of wheat. 
 
 Glimmer. A name sometimes given to 
 micaceous earths. 
 
 Globe. Any round solid body. It is 
 supposed to be formed, or is such a body as 
 wovdd be formed by putting a circle in rapid 
 motion around one of its diameters ; hence 
 synonymous with sphere. When we speak 
 of the globe, the earth or world is understood 
 to be indicated. 
 
 Globe, Artificial. A sphere made of 
 metal, stone, paper, &c. The term, however, 
 is mostly applied to those globes which are 
 made of paste-board, and which have upon 
 their surfaces representations of the earth or 
 heavens, designed to illustrate certain parts 
 of the sciences of astronomy and geography. 
 The globe adapted to the former science 
 being called the celestial^ and the latter the 
 terrestrial globe. 
 
 The fundamental parts of these instruments 
 which are common to both are, first, the two 
 poles whereon the globe is supported, re- 
 presenting those of the world ; second, the 
 brazen meridian, which is divided into degrees, 
 and passes through the poles ; third, the 
 wooden horizon, whose upper side represents 
 the real horizon, and is divided into several 
 circles, (see Horizon:) fourth, a brass 
 quadrant of altitude, (see Altitude ;) fifth, 
 two hour circles, one moving round each 
 pole as a centre, and divided into twice 12 
 hours, to indicate those of the day and night. 
 The best globes have also a magnetic compass 
 attached to the frame. Upon the surface of 
 
 E B 
 
GL 
 
 GN 
 
 the globes are depicted the lines of latitude 
 and longitude, the equator, ecliptic, tropics, 
 and polar circles. On one globe, in addition 
 to these, are the various countries, seas, &c. 
 of the world ; and on the other, the stars in 
 their relative positions. 
 
 Globular. Relating to or partaking of 
 the nature of a globe. 
 
 Globules. Small globes ; such for exam- 
 ple as minute drops of quicksilver. 
 
 Glowing Light, or Lamp. A light is so 
 called when arising from a combustion of 
 such a nature as that no emission of an in- 
 flammable gas, consequently no flame arises ; 
 such as the light of charcoal, of a stick of 
 phosphorus, of platinum heated by hydrogen, 
 &c. 
 
 Glucina. An earth of peculiar character, 
 discovered by Vauquelin to exist in the gem 
 aqua marina, and afterwards in the emerald. 
 Its name is derived from its distinguishing 
 character, of forming with acids salts which 
 are sweet to the taste. Glucina is a white 
 soft powder, light, insipid, and adhering to 
 the tongue ; remains unaltered by heat ; does 
 not change vegetable blue colors, is inso- 
 luble in water, and dissolved by potass, soda, 
 and carbonate of ammonia, but not by pure 
 ammonia. 
 
 Glucinum. The supposed metallic base 
 of the earth glucina. 
 
 Glue. A dried jelly, made from the pa- 
 rings of hides and other offal, by boiling them 
 in water, straining through a wicker basket, 
 suffering the impurities to subside, and then 
 boiling a second time. In this state the glue is 
 poured into flat frames or moulds ; when con- 
 gealed it is cut into small pieces, and after- 
 wards dried in a coarse net. Shreds or pa- 
 rings of vellum, parchment, or white leather, 
 make a clear and almost colorless glue. 
 
 Gluten. If wheat flour be made into a 
 paste and washed in a large quantity of water, 
 it is separated into three distinct substances ; 
 a mucilaginous saccharine matter, which is 
 readily dissolved in the liquor, and may be 
 easily separated from it by evaporation ; 
 starch which is suspended in the fluid, and 
 subsides to thebottom by repose ; and gluten, 
 which remains afterwards ; it is tenacious, 
 very ductile, somewhat elastic, and of a brown 
 grey color. From the flour of barley, rye, 
 or oats, no gluten can be obtained, as from 
 that of wheat. 
 
 Glycerine, or the Sweet Principle. 
 A compound discovered by Scheele in soaps 
 and soap liquors. It may be made as fol- 
 lows : — Saturate the alkaline mother liquor, 
 from which soap has concreted, by dilute sul- 
 phuric acid, adding a little carbonate of ba- 
 ryta to remove any excess of acid ; filter, 
 evaporate to the consistency of thin syrup, 
 to which add alcohol, which dissolves the 
 glycerine, and leaves the alkaline sulphate. 
 
 Glycerizin. a kind of sugar extracted 
 from the liquorice root. 
 
 Glycium. Synonymous with glucinum. 
 
 Glyphic. In sculpture, the art of engra- 
 ving figures, &c., on stones and other hard 
 substances. 
 
 Glyptography. The knowledge of en- 
 graved gems. 
 
 Glyphs. The channels in a Doric frieze. 
 (See Triglyphs.) 
 
 Gnomon. In dialling, is the style, pin, or 
 cock of a dial, the shadow of which points 
 out the hours. This is always supposed to 
 represent the axis of the earth, to which it is 
 therefore parallel. 
 
 Gnomon. In geometry, is a space included 
 between the lines, forming two similar pa- 
 rallelograms, of which the smaller is inscribed 
 within the larger, so as to have one angle in 
 each common to both. The two parallelo- 
 grams A B C D and A G F E in the following 
 cut will be in this condition, the angle A 
 being common. The gnomon, therefore, will 
 be all the space outside the smaller parallelo- 
 gram A G F E. So also three other gnomons 
 may be made out of the same figure, taking 
 out each time the corner piece, as is seen 
 below 
 
 Gnomonic Projection. A representa- 
 tion of one of the hemispheres of the earth 
 on a flat surface, the pole being the centre of 
 that surface. It shows the earth as it would 
 
GO 
 
 GO 
 
 appear if looked down upon from the pole 
 itself; the meridians in this projection are 
 consequently straight lines. The annexed 
 is a gnomonic representation of a part of the 
 earth's surface around the north pole. 
 
 GxoMONics. The art of dialling. CSee 
 J)ialling.) 
 
 Gobel's Pyrophorus. The tartrate of 
 lead heated to a dull red in a glass tube, until 
 it acquires a brown color ; when cool, and it 
 is dropped from the tube into the air, it im- 
 mediately inflames. 
 
 GoDROON, or Gadroon. a kind of in- 
 verted fluting, beading, or cabling, with 
 which various architectural members and 
 ornaments are decorated. 
 
 GoLA, or Gyla. Synonymous with ogee, 
 a kind of moulding. 
 
 Gold. A yellow metal, which is soft, very 
 tough, ductile, and malleable ; unalterable 
 and fixed, whether exposed to the atmosphere 
 or to the strongest heat of furnaces. A heat 
 equal to about 1300° of Fahrenheit's ther- 
 mometer is required to melt it. Its color, 
 when melted, is of a bluish green. No acid 
 acts upon gold, it being soluble only in the 
 mixture of the nitric and hydrocliloric acids, 
 called aqua regia; and in the mixture of 
 chromic and hydrochloric acids. There is 
 but one oxyde, which is of a purple color, 
 and may be obtadned by sending an electric 
 shock through gold leaf inclosed by two 
 pieces of glass. Gold unites with most other 
 metals, and with sulphur, ammonia, &c. 
 
 Gold Manheim, or Similor, is an alloy 
 composed of 3^ ounces of copper ; l^ ounces 
 of brass ; and 15 grains of pure tin. 
 
 Gold-Beater's Skin. An extremely fine 
 membrane made of the intestines of animals, 
 principally sheep. It is used by gold- 
 beaters to interlay with the leaves of gold 
 which are under the process of hammering. 
 It has the peculiar property of not altering 
 its dimensions, even under the long-continued 
 beating it receives. 
 
 Gold Coin of England at the present 
 time consists of the five pound piece, the 
 two pound, the sovereign, and the half- 
 sovereign, the two former being scarce. Their 
 composition is not pure gold, but composed 
 of gold 11 parts, and copper 1 part. 
 
 Golden Number. A number showing 
 which year of the lunar cycle any given year 
 is. To find the golden number, add one to 
 the given year, and divide the sum by 19 ; 
 what remains will be the golden number, 
 unless (0) remains, and then 19 is the golden 
 number. (See Epact and Cycle.) 
 
 Golden Rule. In arithmetic, the rule of 
 proportion, called golden, from its extensive 
 application. 
 
 Golden Varnish, is made of 16 ounces 
 of boiled linseed oil ; 8 ounces of Venice 
 turpentine ; and 5 ounces of Naples yellow. 
 
 Heat the oil with the turpentine, and mix 
 the Naples yellow pulverised. 
 
 Gold Leaf. Gold beaten between skins 
 and membranes to a degree of extreme thin- 
 ness. The best wrought gold is so thin that 
 1 grain covers 57 square inches ; and 282,000 
 leaves are required to form a packet of an 
 inch in height. 
 
 Gold Leap Galvanoscope. The con- 
 struction of the gold leaf galvanoscope is 
 similar to the instrument of 
 Mr. Bennet, (see Bemiet,) ex- 
 cept that the leaf of gold is 
 single, and there is added a 
 forceps to retain the lower end 
 of the gold leaf, and complete 
 the galvanic circuit. The slip 
 of gold leaf B is freely sus- 
 pended from the pin or forceps 
 A, while the lower end is laid 
 hold of by another pin or 
 forceps C. The pin A is con- 
 nected with the cup P, and the 
 pin C with the cup N. The 
 whole, except the cups, is in- 
 closed in a cylindrical glass 
 case, the middle of which is placed between 
 the poles of a strong horse-shoe magnet D D, 
 so that the gold leaf may be equally distant 
 from them. When the current is made to 
 pass along the gold leaf, it will be attracted 
 to the one pole or the other, according as 
 the current is ascending or descending. The 
 degree of attraction may be estimated by 
 comparison with a line drawn perpendicularly 
 along the glass tube which forms the cover. 
 
 Gold Size. A thick tenacious kind of 
 varnish which dries rather quickly. It is used 
 by gilders to form the letters and other ob- 
 jects which are to be gilt, in order to make 
 the gold leaf adhere to them ; it is sometimes 
 slightly mixed with a yellow coloring sub- 
 stance. There are many receipts, among 
 which is the following : — Expose boiled 
 linseed oil to a strong heat in a pan ; when 
 it emits a black smoke, set it on fire, and 
 in a few minutes extinguish it by putting on 
 a cover ; then add some spirits of turpentine, 
 till of a proper consistence when cold. 
 
 Gold Solder. The alloy used for solder- 
 ing gold articles is composed of 12 dwts. pure 
 gold, 2 dwts. pure silver, and 4 dwts. copper. 
 
 Gold Thread, is a fibre of silk, covered 
 with gold wire. 
 
 Gold Wire. That which is usually called 
 so is merely silver wire gilt. 
 
 Goniometer. An instrument for mea- 
 suring the angles of solid bodies, particularly 
 the angles of crystals. The following is a 
 simple form of the instrument : — 
 
 A A is a semi-circle of brass, graduated 
 from to 180°. B B is an arm, which con- 
 nects the ends of the scale. C C is an arm, 
 moveable around the centre. Any crystal 
 
GO 
 
 GO 
 
 therefore put between the wider part of C and 
 B will occasion the narrower part of C to fall 
 
 upon one of the marked divisions of the scale, 
 which will therefore show the angular mea- 
 surement. 
 
 GoNioMETRiCAL LiNEs, are lines em- 
 ployed in measuring or determining the quan- 
 tity of angles, such as sines, tangents, se- 
 cants, &c. 
 
 GoNioMETRY. The art of measuring angles, 
 either by calculation, or by means of instru- 
 ments adapted to the purpose. 
 
 Gorge. Synonymous with cavetto. 
 
 GoRGERiN. (See Hypocrachelium.') 
 
 Gothic Any thing far removed from the 
 manner and proportions of the antique. 
 
 Gothic Architecture. A style of build- 
 ing of considerable strength, majesty, rich- 
 ness, and beauty, brought originally from the 
 North by the Goths into Germany, and hence 
 by the Saxons into England. The style thus 
 introduced was and is called the Saxon Go- 
 thic, or simply the Saxon style. Afterwards 
 the Normans introduced their own modi- 
 fication of Gothic architecture, hence called 
 the Norman style. English, French, and 
 German talent being added, the once rude 
 and heavy Gothic became more richly deco- 
 rative, and more finely proportioned. The 
 art advanced in successive periods, through 
 the varieties which have been since called, 
 the early English, the lancet-arched, the de- 
 corated, and the perpendicular or Tudor 
 style, when Gothic architecture was practised 
 in all its lavish beauties and sublime pro- 
 portions. 
 
 Gouge. A hollow chisel, for cutting holes, 
 channels, grooves, &c., in wood or stone. 
 
 Goulard's Extract, or Goulard Wa- 
 ter. A solution of the subacetate of lead, 
 (sugar of lead.) 
 
 Gould's Microscope. A compact, con- 
 venient, and powerful instrument, adapted 
 equally as a travelling and table instrument. 
 The whole fits into a mahogany box, when 
 put away, and which box forms a stand for it 
 when in use. 
 
 In the centre of the lid of the box screws 
 the upright square stem A. Tliis has upon 
 
 one side of it a rack movement, in whicb 
 works the screw B, intended to raise or de- 
 
 press the stage C, as occasion requires. C 
 consists of two plates of brass, held together 
 by a spring ; between these plates the object 
 slider D is placed. E is an arm at right 
 angles to A ; it is attached and confined by 
 the screw at the end of it, in A. F must be 
 supposed to represent three lenses or mag- 
 nifiers, screwed together ; the focus of each 
 being such that they act in unison together. 
 G is a reflector, to cast the light upwards 
 through the object to the eye. H is the main 
 tube, which bears the eye lens at one end, 
 and screws upon one of the object lenses at 
 the other. 
 
 When the instrument is in use, the focus 
 is adjusted by moving the screw B, and the 
 degree of magnifying power is according to 
 the lenses which are screwed on to the bottom 
 of H. Thus, if one lens obtain an increase 
 of 10, two lenses may obtain a power of 100, 
 and three lenses of 1000. Let it be always 
 remarked, that the more lenses the more 
 obscure will be the image. 
 
 Governor, Steam Engine: or Conical 
 Pendulum. This instrument is calculated to 
 equalize the rapidity of motion of the ma- 
 chine to which it is attached : it consists of 
 two balls, suspended on wires, jointed at the 
 top, and connected with two rods below, 
 which rods are connected with a socket, which 
 slides up and down the axis that supports the 
 whole. The instrument is turned by a wheel 
 or cord attached to it. The faster it turns the 
 higher the balls are separated by their centri- 
 fugal force, and consequently the higher the 
 lower socket rises, and with it rises also a rod, 
 which moving a valve in a distance admits 
 more or less steam, and thus reduces or in- 
 creases the motion. 
 
GR 
 
 GR 
 
 A is the point at which the ball rods are 
 fastened. E and B sockets on which they 
 tvim. C C the balls themselves. F the up- 
 right spindle. D D the joints of the lower 
 levers of the balls. G and H the bevelled 
 gear, which gives the governor its motion. 
 J the lever which is raised, and which regu- 
 lates the steam valve. ^ 
 
 GoWt, or Go Out. In engineering, a 
 sluice used in embankments against the sea, 
 for letting out the land waters when the tide 
 is out, and preventing the ingress of salt 
 water. 
 
 Gradation. A gradual blending of one 
 tint into another, or in the arts a regular and 
 equal disproportion of several things near to 
 each other, or of different parts of the same 
 object. 
 
 Gradient. A term indicative of the pro- 
 portionate ascent or descent of the several 
 planes upon a railway ; thus, an inclined 
 plane, 4 miles long, with a total fall of 36 
 feet, is described as having a gradient of 1 
 in 587, or 9 feet per mile. 
 
 Graduated. Any thing marked in de- 
 grees of equal parts, as distinguished from 
 the division into inches or other certain and 
 determinate measurements. Hence in gra- 
 duating an instrument, the length of the 
 degree is in proportion to the size of the 
 instrument ; but a measurement in inches, 
 &c. has no reference to the length of the 
 scale employed. 
 
 Graduation. The art of graduating or 
 dividing. 
 
 Grafting Tool. A kind of spade made 
 very strong and much curved, used in digging 
 canals ; often called only a tool. 
 
 Graham's Mercurial Pendulum. (See 
 Mercurial.) 
 
 Grain. The smallest nominated weight ; 
 supposed to have derived its name from being 
 the weight of an ordinary grain of barley. 
 If an object weighs less than a grain, its 
 weight is designated as a certain part of a 
 grain, such as the eighth, quarter, &c. 
 
 Grainer. The mixture obtained by in- 
 fusing pigeons* dung in water ; is used for 
 giving flexibility to skins in the process of 
 tanning, and is called the grainer. 
 
 Graining. The art of imitating the fancy 
 woods and marbles by means of water or 
 oil colors. 
 
 Grain Tin. (See Tin.) 
 
 Granite. A hard compact stone, much 
 used in building, composed of separate and 
 very large concretions rudely compacted. 
 The white granite, with black spots, some- 
 times called moorstone, which is much used 
 in the pavement of London, is a very firm, 
 and though rude, yet beautifully variegated 
 mass. Hard red granite, variegated with 
 black and white, called oriental granite, and 
 Devonshire granite, is valuable for its ex- 
 treme hardness and beauty, and its capabilitj 
 of receiving high polish. The Aberdeen, 
 Cornish, and Irish granites are particularly 
 fine. It is considered by geologists £is one 
 of the primitive rocks, that is, one of the 
 oldest formation, and forms the chief portion 
 of all large mountains. 
 
 Granulation. The method of dividing 
 metallic substances into grams or small par- 
 ticles, in order to facilitate their combination 
 with other substances ; and sometimes for 
 the purpose of readily subdividing them by 
 weight. 
 
 Graphic Microscope. An instrument 
 invented by Mr. Cornelius Varley, for the 
 purpose of depicting the objects represented 
 by the microscope. Its principle of action 
 is that of reflection, as will be immediately 
 seen by the following cuts of the micro- 
 scope : — No. 1 shows the outward form. 
 The object is placed on the stage. Light 
 passing through it in the usual manner from 
 the reflector beneath, its image is carried up- 
 wards till it strikes a plane mirror above ; 
 then passing along the tube, and through the 
 lenses of it, the light is again intercepted by 
 a second mirror, (this as well as the former 
 being at an angle of 45° with the tube,) and 
 cast down to a sheet of paper. The second 
 mirror is formed like a prism, so that, as in the 
 
GR 
 
 GR 
 
 camera lucida, the eye is capable of looking 
 across its edge, and seeing the object beneath, 
 which may therefore be drawn by the aid of 
 a pencil. 
 
 The second cut shows the glazing and in- 
 ternal structure of the instrument; the manner 
 in wliich the light is reflected will be easily 
 understood. 
 
 Graphite. Black-lead. 
 
 Graphometer. a semi-circle graduated 
 around its circumference, and by which angles 
 may be measured. The common goniometer 
 is one form of the instrument. 
 
 Graticulation. a term used by some 
 writers for dividing a drawing into com- 
 partments or squares in order to be reduced. 
 
 Graving Dock. (See Dock.) 
 
 Gravitation. The power or tendency of 
 moving towards a centre, therefore called 
 the centripetal force ; it is this which con- 
 stitutes the weight of bodies, and which keeps 
 the earth and planets in their respective or- 
 bits, and chiefly in their globular shapes. It is 
 also the cause of bodies falling to the earth. 
 The power of ordinary gravity depends upon 
 two causes. First, according to the size of 
 a body multiplied into its specific gravity ; 
 that is, in proportion to the quantity of matter 
 which a body positively contains. Second, 
 the weights of bodies being equal, gravitation 
 is stronger according to the square of the 
 nearness of the bodies to each other ; or as 
 mathematicians usually say, inversely as the 
 square of the distance. Thus, if one body 
 be five times as heavy as another, the larger 
 one will have five times the attractive force ; 
 but if one be twice as far off" a third body, 
 it will attract it with only one-fourth the 
 power; if three times the distance, the power 
 of gravitation will be one-ninth, and so on. 
 
 Gravity, Line of Direction of, is a straight 
 line which passes through the centre of gra- 
 vity of a body in a direction towards the 
 centre of the earth. If this line pass beyond 
 the base of the body, the body will fall. 
 
 Gravity, Specific, is the relative gravity 
 of any body or substance, considered with 
 regard to some other body which is assupied 
 as a standard of comparison, which standard, 
 by universal consent is rain water ; this 
 fluid not being subject to much variation 
 frorn time, place, or other circumstance. One 
 cubic foot of rain water weighs exactly 1000 
 (avoirdupois) English ounces ; hence the re- 
 lative weight of other bodies is easily referred 
 
 to this standard : for example, gold, when 
 hammered, weighs 19362 ounces the cubic 
 foot ; it is therefore more than nineteen times 
 heavier than water. The foot of cast iron 
 weighs 7207 ounces ; flmt 2594 ; brick 
 2000; marble 2742; cows' milk 1032; whale 
 oil 923 ; wax 897 ; oak 1170 ; poplar 383 ; 
 atmospheric air 1^ ; hydrogen gas one-tenth 
 of an ounce the cubic foot. 
 
 Great Circle. (See Circle.) 
 
 Greek Architecture. Such as was 
 practiced by the Greeks. Its chief charac- 
 teristic is the exact proportions of all its 
 various parts, members, and ornaments, as 
 known and explained by the names given to 
 the Grecian orders of Doric, Ionic, and 
 Corinthian. (See these terms.) 
 
 Greek Cross. (See Cross.) 
 
 Greek Fire. An inflammable composition 
 of such great power of combustion as when 
 once lighted not to be extinguished by any 
 means, not even by water. The composition 
 is now unknown, but asphaltum and a strong 
 kind of gunpowder are supposed to have 
 been its principal ingredients. 
 
 Greek Orders. {SeeGreek Architecture.) 
 
 Gregorean Telescope. A reflecting te- 
 lescope, the internal construction of which is 
 shown in the following sectional cut :— 
 
 
 
 ^=^t^^ 
 
 4*::::^ -^^^ 
 
 *^C^ 
 
 
 -jT 
 
 Rays of light from any distant object are 
 supposed to approach from the end A, and 
 passing along the tube of the telescope to 
 strike against the speculum B B. Here they 
 are reflected, come to a focus at C, and pass 
 onwards till they strike the concave mirror D, 
 from whence they are sent off parallel to the 
 compound eye glasses E and F. The use of 
 the screw S is to adjust the focus of the 
 small lens. 
 
 Green. A color produced by the union of 
 blue and yellow. In the Newtonian hypo- 
 thesis of the composition of light : it is con- 
 sidered as a distinct color, forming one of 
 the seven primitive colors. 
 
 Green Sand. A native submunate of 
 copper, found in Peru and Chili. 
 
 Green Verditer, or Mineral Green. 
 A bulky hydrated dicarbonate of copper, 
 obtained by precipitation from hot solutions 
 of copper, by the carbonates of the fixed 
 alkalis. 
 
 Green Vitriol. The sulphate of iron. 
 
 Green Earth. A frequent mineral in 
 Scotland, England, Ireland, Iceland, Saxony, 
 Hungary, &c. It is the mountain green of 
 artists in water colors ; the color is durable, 
 
GR 
 
 GR 
 
 but not so bright as the pigments made from 
 copper. The green earth of Verona is 
 reckoned the best. 
 
 Graver. A tool used by the metal and 
 wood engraver, chaser, &c. for the purpose 
 of cutting the lines and forming the design, 
 called therefore the engraving. Gravers are 
 sometimes straight, and sometimes rather 
 turned up at the point. They are made of 
 a square or rectangular piece of steel, ground 
 so that the face or cutting part resembles a 
 lozenge. The following cut shows a straight 
 graver, and the points of several others of 
 different sizes : — 
 
 Gridiron Pendulum. A pendulum so 
 called from its peculiar shape. It is formed 
 of five bars of metal, as re- 
 presented, the small cross 
 pieces fastening them together 
 not being shown. The two 
 outer bars, and also the centre 
 bar to which the bob is at- 
 tached are of steel, and the 
 two intermediate bars are of 
 an alloy of zinc and silver. 
 Both series of bars expand by 
 heat ; the steel bars have there- 
 fore a tendency to lengthen 
 the pendulum, but this is 
 comiteracted by the bars of 
 zinc and silver drawing the 
 pendulum up again by expand- 
 ing upwards, as will be seen. 
 The contrivance therefore com- 
 pensates for changes of tempe- 
 rature. It is often called from ,„ 
 this circumstance, and the name of the in- 
 ventor, Harrison's Compensation Pendulum. 
 
 Gripe, or Break. A pliable lever, which 
 can be pressed against a wheel to retard or 
 stop its motion by friction. 
 
 Grillage. A term applied to the sleepers 
 or cross beams supporting a platform, upon 
 which some erections are carried up, as piers 
 in the case of marshes or watery soils, whereby 
 an equal bearing is given to the foundation. 
 
 Grit Stone. A stone, consisting of par 
 -jles of sand agglutinated together 
 of the species are used for grinding ; others 
 
 Groins. The angles which vaults makebv 
 their mtersections. ■' 
 
 Groined Roofs. Vaulted ceiUngs, sup- 
 ported by groins and ribs, intersecting each 
 other. I 
 
 ^all, square, hollow channel, 
 1, flat stone, &c., either as 
 to insert a panel, or other 
 
 Groove. A 
 cut out of a bo 
 an ornament, o 
 similar piece. 
 
 GROTEsauE/ Distorted of figure uu- 
 natural. I ' 
 
 Grottesqu/. Artificial work, formed in 
 imitation of gMtoes or rock-work. 
 
 Grotto. M artificial cavern or cave, de- 
 corated withi-ock-work, shells, &c., con- 
 structed for oblness. 
 
 Ground, the surface of any thing, par 
 ticularly theUrface of the earth. In pain- 
 ting. It sign^s the first coats of color which 
 are put upd the canvass, previous to the 
 figures bemflepicted upon it. In a finished 
 picture It ishe scenery around the principal 
 objects, tWpart nearest to the eye beine 
 called the h-sfround, and the more distant 
 parts the Wc-ground, In sculpture it is 
 the flat siface at the back of bas or alto 
 rehef. / 
 
 GrouWCill. (See Ground Sill.) 
 
 GROuif Line. In perspective, the inter- 
 section dhe picture with the ground 
 
 Grou> Niche. A niche whose bottom 
 is on th^me level with the floor. 
 
 ^^T.u'^^''' 7^^ P^^ of a story of 
 a housed the same level with the surface of 
 the grdd, or elevated only a few steps be- 
 fore tWoor. ^ 
 
 GRcirD Plot. A piece of ground selected 
 for buuig upon. 
 
 Gr^d Sill, or Plate. The lowest 
 honzjfel timber or course of stones on 
 whicjhe exterior walls of a building are 
 consPted. ^ '"'' 
 
 GiJND Table Stones. Now pUnth. 
 
 ^UND-woRK. The same as foundation. 
 
 OUPED Columns, or Pilasters. 
 Thi which consist of more than two. 
 
 buT. A thin semi-fluid mortar, com- 
 
 pn of quickhme, with a portion of fine 
 
 s^ which IS prepared and poured into the 
 
 iijal joints of masonry or brick-work. 
 
 Tprocess is called grouting. 
 
 rove's Galvanic Battery. A battery 
 
 (posed of any number (usually six,) of 
 
 p, each of which may be explained as 
 
 >ws :--First, is a common jelly pot ; next 
 
 hmside this is a cylinder of zinc, without 
 
 •ottom ; next is a cup of the same shape 
 
 the jelly pot, but narrower, and made of 
 
 tides of sand agglutinated together. Some 
 
 of the species are used for grindmg ; others Pe jelly pot, but narrower, and made of 
 for sharpening edge tools ; and others for he porous substance, such as tobacco-pipe 
 filtering water. iy, common clay, &c. unglazed ; inside of 
 
 Groin. In engineering, is awooden break -As is a slip of platinum. Outside of the 
 water, intended chiefly to retain the mud ancProus vessel is poured dilute acid, or salt 
 sand thrown up by the tides, so as to gairf^d water, while the porous vessel 'is filled 
 land from the sea, or to restrain its inroad/it^ strong nitric acid. The zinc of one 
 
GU 
 
 Gt) 
 
 cup is connected with the platinum of the 
 next throughout the series. This battery is 
 very powerful till the nitric acid is exhausted, 
 which it will be in an hour or so. 
 
 GuAiACUM. A gum resin, xtracted from 
 the wood of the guaiacum oftinale, a large 
 tree of the West Indies ; the T)od of which 
 is often imported and known > the name of 
 lignum vitffi. The gum is use occasionally 
 in medicine, in rheumatic andther cases. 
 
 Guards. In engineering, bright pieces 
 of wood, iron, or stone, fasten* to the lock 
 gates of a canal, the corners of street, and 
 similar situations, to prevent tl passage of 
 barges in the one place, and aggons in 
 the other, from injuring the partflush with, 
 or near to the guard. 
 
 Gudgeon. The centre or pivotf a wheel. 
 
 GuiLLOCHi. Ornaments usecn Italian 
 
 cornices, very similar, but largethan the 
 
 braided ornament, and consistingf curved 
 
 lines interlacing each other. 
 
 Guinea and Feather Appara^. a 
 contrivance used in the illustration ^lieu 
 matics, to prove that the air 
 offers a considerable resis- 
 tance to the falling of light 
 bodies. A is a brass plate, 
 fitting on to the top of a 
 long open receiver. B is a 
 stuffing box, through a hole 
 in which the wire C moves 
 round. E and F are two 
 wires, screwing upon the 
 under side of A, and having 
 at the lower eud of each a 
 small flap, moveable on a 
 hinge. One "flap, H, is re- 
 presented as hanging down ; 
 
 the other flap, G, is supported at the free 
 end by a semi-circular, or rather segmental 
 flanch D, at the lower end of C. Suppose 
 the two flaps are both up, and loaded with a 
 guinea and a feather each ; upon turning C 
 round, one flap will soon be liberated, in 
 consequence of a portion of D being cut off, 
 which allows it to fall ; and the guinea and 
 feather being liberated at the same time, the 
 guinea, being the heavier object, will reach 
 the bottom of the receiver first. This being 
 proved, exhaust the air from the receiver, 
 and then let the other guinea and feather es- 
 cape, when it will be seen that in consequence 
 of the resistance of the air being taken away, 
 the two objects will reach the bottom at the 
 same moment. 
 
 GuLA. (See Cymatium. 
 
 Gullies, A name applied in some places 
 to the iron tram plates or rails, laid for the 
 use of tram waggons. 
 
 Gum. The mucilage of vegetables ; the 
 principal gums are : — 1. The common gum 
 obtained from the plum, cherry tree, &c. 
 Gum Arabic, which flows naturally from the 
 acacia of Egypt, Arabia, and elsewhere. 
 Gum Senegal, a similar species, brought 
 from Senegal and other parts of the coast of 
 Africa ; and gum adragant, tragacanth, or 
 gum dragon, obtained from a small plant of 
 the same name, growing in Syria. 
 
 Gum, British. (See Dextrine.) 
 
 Gum, Elastic. (See Caoutchouc.) 
 
 Gum Resins. A class of substances pos- 
 sessing properties intermediate between the 
 gums and resins. The principal are frank- 
 incense, scammony, asd"oetida, aloes, gum 
 ammoniac, and gamboge. 
 
 Gun-Barrel Apparatus, for making 
 Potassium, is thus described in " Brande's 
 Chemistry." A sound and perfectly clean 
 gun barrel is bent, as shown in the annexed 
 cut : — 
 
 It is then covered with an infusible lute 
 between the letters O andE, and the interior 
 of the luted part is filled witli clean iron 
 turnings. Pieces of fused potassa are then 
 loosely placed in the barrel between E and C. 
 A A is a copper tube and small receiver, 
 which are adapted to the extremity O, and 
 to each other by grinding. The apparatus is 
 next transferred to the furnace, (see following 
 cut ;) X and T representing two glass tubes 
 dipping into mercury. The furnace is well 
 supplied with air by a good double bellows 
 entering at B, and a small wire basket is sus- 
 
GU 
 
 GU 
 
 pended below the space E C. This part of 
 the barrel is cautiously raised to a white heat, 
 and the escape of air by the tube X shows 
 that all is tight. Some charcoal is put in the 
 end E of the cage G, which causes a portion 
 of the. potass to liquify and fall into the lower 
 part of the barrel upon the iron, and hydrogen 
 escapes by the tube X. Attention must 
 now be had to keep the tubes A A cool, by 
 laying wet cloths upon them. The potassium 
 will collect in the tube and receiver A A. 
 T is a safety tube, for whenever the tube is 
 stopped up with potassium, the gas will issue 
 at T, instead of at X. 
 
 Gun Metal. The alloy for large guns is 
 made of 112 parts brass, 14 zinc, and 7 grain 
 tin. For small guns the following is used : — 
 9 parts copper and 1 part tin. 
 
 Gunpowder. A compound powder, used 
 to explode in various descriptions of fire- 
 arms. The great quantity of air liberated by 
 the combustion occasioning a projectile force, 
 capable of propelling bodies to a very con- 
 siderable distance. Its ingredients are 78 
 parts of saltpetre, 12 of charcoal, and 10 of 
 sulphur. These are ground together with 
 great care and much labor, until they are 
 completely incorporated with each other, and 
 form a powder, commonly called meal powder, 
 in which state it is used for fire-works of 
 various kinds. For the use of fire-arms it 
 is formed into grains by being rubbed through 
 sieves, while yet in the state of a damp paste, 
 (the ingredients being ground in water.) 
 Being dried, it is next put in barrels, and 
 these are turned round, so that the grains 
 rubbing against each other become glossy, 
 forming then glazed powder, or the kind most 
 employed by sportsmen. 
 
 Gunpowder Apparatus. An invention 
 of Mr. Sturgeon, to show under what cir- 
 cumstance gunpowder may be inflamed by 
 the electric shock. 
 
 A is a brass wire which has a small ball 
 at one end, and is supported upon the glass 
 pillar B at the other, the cap connecting 
 the wire and glass having a chain attached to 
 it or slipped over it. I) is a metallic stand 
 upon which the gunpowder is placed. Around 
 D is tied a wet linen thread E about 3 inches 
 
 long, and this is terminated by a chain. 
 When gunpowder is placed upon the top of 
 
 D, and the shock of a pint Leyden jar sent 
 from one chain to the other, it will pass 
 thi-ough the grmpowder and inflame it. The 
 wetted thread is indispensable. 
 
 Gunter's Chain. (See Chain.) 
 
 Gunter's Line of Numbers. A loga- 
 rithmic line, usually graduated on scales, 
 sectors, &c., which therefore serves to solve 
 problems instrumentally, in the same manner 
 as logarithms do arithmetically. It is usually 
 divided into 100 parts, every tenth of which 
 is numbered. 
 
 Gunter's Scale. Usually called by sea- 
 men, " The Gunter,^^ is a flat scale about 
 2 feet long, and an inch and a half broad, 
 with various lines upon it, both natural 
 and logarithmic, relating to navigation, 
 trigonometry, &c., for solving questions in 
 which sciences it is chiefly employed. There 
 are two variations of form in the instrument, 
 giving the names of the plain Gimter and 
 the sliding Gunter. 
 
 Gurney's Oxy-hydrogen Blow-pipe. 
 A compact, powerful, and perfectly safe in- 
 strument, for procuring a constant and in- 
 tensely powerful flame, applicable to the usual 
 purposes of a blow-pipe ; that is, the melting 
 of small quantities of refractory or difficultly 
 fusible substances. 
 
 The above figure represents the apparatus 
 complete. A and E, (fig. 1,) is the safe ap- 
 
HA 
 
 HA 
 
 paratus, a section of which is seen in fig. 2, 
 and through which the gas must pass from 
 the gasometer, through the stop cock C. G 
 is a transferring bladder, screwed to the stop- 
 cock H, by which the gasometer is charged 
 by an assistant during its action, and such a 
 quantity of gas supplied as to keep up a flame 
 for any requisite time. Between the gasometer 
 and the charging bladder a valve is placed, 
 to prevent a return of the gas. I a wood or 
 pasteboard cap, so contrived as to unite light- 
 ness with strength ; this is attached by four 
 strings, K, to wires, which passing through 
 holes L L in the table of the instrument, are 
 fixed to M, a moveable press board below. 
 When the requisite pressure or weight is 
 placed on M, the cap I is drawn down hori- 
 zontally and equEdly on the gasometer D ; 
 upon which the gas, (this is oxygen and hy- 
 drogen mixed together in the proportion of 
 one part of the former to two of the latter ;) 
 is forced through the water tube B, the safety 
 apparatus A, and out of the jet C, at the 
 end of which it is burned. In fig. 2, the gas 
 enters B, passes through the water at D, then 
 through a series of wire gauzes at E, and 
 afterwards out at the jet. 
 
 GuTTiE, or Drops. An ornament of the 
 
 Doric architrave, six of which are usually 
 placed under each triglyph. 
 
 **!«**» 
 
 Gymnotus. The electrical eel. The name 
 of a fish common in the rivers of Guiana, 
 which possesses in itself the power of elec- 
 tricity, communicating a strong shock to all 
 conducting bodies that come within its in- 
 fluence. It is from 2 to 4 or 5 feet in length, 
 •with rather a flat black body, covered with 
 yellowish spots. 
 
 Gypsum. Plaster of Paris or sulphate of 
 lime in its natural state. (See Plaster of 
 Paris.) 
 
 Gyration. The art of whirling a body or 
 system of bodies about one common centre. 
 
 Gyration, Centre and Circle of. If a 
 stick move at one end on a pivot, and the 
 other end of it be whirled round that as a 
 centre, the whole force will be concentrated 
 into one point, which is called the centre of 
 gyration. In an equally-balanced wheel there 
 will be a number of such points, all equally 
 distant from the centre, called therefore the 
 circle of gyration. 
 
 This, is considered by 
 some grammarians not 
 to be entitled to the 
 character of a letter, be- 
 cause it requires no par- 
 ticular conformation of 
 the organs of voice to 
 
 pronounce it. Its use, 
 
 however, is established in almost all languages, 
 ancient and modern, as an aspirate. In 
 England it is now generally estimated as a 
 distinct letter, necessary to the spelling of 
 words, even more than to their pronunciation, 
 as alter, halter; arty hart. It is often silent, 
 as in honor, hour. 
 
 Hacking. In masonry, is the making up 
 a course of stone, partly and properly con- 
 structed of stone hewn to an equal size by 
 other stones which are smaller and less 
 regular. In the following illustration the 
 middle row of stones is hacked near one 
 end : — 
 
 Hackle. A kind of comb or brush made 
 of iron spikes ; used for combing or pulling 
 the fibres of wool, so as to reduce them from 
 a tangled to a smooth state. 
 
 Hade, or Hading. The direction of a 
 fault in mining ; or the different course which 
 a vein of metal, or seam of coal takes after 
 it has been broken or diverted from its former 
 position. 
 
 Hadley's Quadrant. (See Quadrant.') 
 
 H^machrome, or H^matosyn. The 
 coloring matter of the blood. 
 
 Hematite. Red iron stone. 
 
 H-,ematoxyline. The coloring principle 
 of the logwood, called botanically hcema- 
 toxylon campechianum. 
 
 Hail, or Hailstone. An irregular 
 rounded lump of ice falling from the atmos- 
 phere; occasioned by drops of rain being 
 frozen by the great cold of the air through 
 which they fall. 
 
 Hair. The covering of animals. In the 
 arts, hair is used for numerous purposes, as 
 for the stuffing and covering of chairs ; the 
 blending v/ith mortar for plastering; the 
 making of rope and cloth ; making of brushes 
 and brooms ; pencils for artists, &c. 
 
 Hair, Head of. An electrical experiment. 
 If a figure-head, covered with long straight 
 hair, be placed upon the conductor of aa 
 
HA 
 
 HA 
 
 electrical machine, and the machine put in 
 action, the various hairs will stand on end 
 and be repelled from each other, as in the 
 following cut, being an illustration of electri- 
 cal repulsion : — 
 
 Hair Pyrites. A native sulphuret of 
 nickel which occurs in capillary crystals. 
 
 Hair Powder. The flour of starch, 
 variously scented. 
 
 Hair Salt. The native sulphate of mag- 
 nesia, so called from the shape of the crystals. 
 
 Half-Round. a semi-circular moulding, 
 which may be either a bead or torus, that is, 
 either projecting or indented. 
 
 Half-Stuff. This term in general, im- 
 plies any thmg half formed, in the process of 
 the manufacture. 
 
 Half-Tide Dock. A basm connecting 
 two or more docks, and commvmicating with 
 the entrance basin. 
 
 Half-Tint, or Teint. In painting, such 
 a color as is intermediate between the ex- 
 treme lights and the strong shades of a 
 picture ; called also middle-tint. 
 
 Halo, or Corona. A luminous and some- 
 times colored circle, appearing occasionally 
 around the heavenly bodies, but more 
 especially the sun and moon. It is supposed 
 to be occasioned by the light from these 
 bodies bemg reflected by the vapors of the 
 atmosphere through which it passes. It is 
 remarkable that the large halos surrounding 
 the sun and moon are commonly of given 
 diameters, namely, about 23° or 24°, or else 
 double that magnitude. 
 
 Halogens, or Halogenia. Substances 
 which by combination with metals produce 
 saline compounds, such as chlorine, iodine, 
 bromine, fluorine, which are simple halogens, 
 and cyanogen, which is a compound halogen. 
 
 Haloid. The term is appUed to a class of 
 chemical combinations composed of two 
 elementary compounds, one or both of which 
 are analogous in composition to sea salt. The 
 principal groups consist of double chlorides, 
 iodides, fluorides, and cyanurets. 
 
 Halving. A method of joining timbers 
 by letting them into each other, cutting away 
 the half thickness of each. 
 
 Hammer. A well-known instrument for 
 driving nails. 
 
 Hammer Beams. Two beams of timber 
 projecting from opposite sides into an apart- 
 ment from the wall plate or springing of the 
 rafters, usually supported by a corbel and rib 
 beneath; the whole looking like a huge 
 bracket. These in their turn support other 
 ribs and hammer beams, of a smaller size, 
 forming altogether an arch. The ends of the 
 hammer beams are often grotesquely sculp- 
 tured, 
 
 Hand-Gear. That arrangement of levers, 
 tappets, or other contrivances, which is used 
 for opening and shutting the valves of a steam 
 engine. (See Beighton, Tappet, 8fc.) 
 
 Hand, or Hand's Breadth. A measure 
 of 4 inches ; used in ascertaining the height 
 of animals, particularly of horses. 
 
 Hand Mill. This term does not properly 
 apply to any particular kind of mill, but to 
 all that are worked by hand, such as are em- 
 ployed in the domestic offices of grinding 
 coffee, pepper, &c. 
 
 Hand -Rail of a Stair. A rail raised 
 upon slender posts, called balusters, in order 
 to prevent persons from falling down the 
 well hole, and to assist in ascending and 
 descending. 
 
 Handspike. A lever or pole of wood, 
 4 or 5 feet long, used to turn a windlass, 
 capstan, crane, &c. 
 
 Hanging of Doors, &c. The act of 
 placing them upon centres or hinges, for the 
 convenience of opening and shutting. 
 
 Hanging Style. The style of a door or 
 shutter to which the hinge is fastened. 
 
 Hanging Valve. A flap of metal hanging 
 down from a hinge, and which in this position 
 suffers a hole above it to remain open ; but 
 as soon as any piston or other solid body 
 drives against the back of it, it being thereby 
 forced from a vertical to a horizontal position, 
 closes the hole and acts as a valve. In ro- 
 tatory steam engines and pumps such a valve 
 is common. 
 
 Hangs Over. An expression which ap- 
 plies to a door, wall, partition, or other erec- 
 tion,when the top projects beyond thebottom. 
 
 Hank of Silk, Cotton, &c. Several 
 skeins tied together, or otherwise combined 
 into a small bundle. 
 
 Harbour. A port; the entrance of a 
 port, or such a part of a coast as incloses a 
 
HA 
 
 HA 
 
 space of comparatively smooth water, where 
 ships may anchor safely. 
 
 Hardening of Stekl and Iron, is ac- 
 complished by lowering its temperature from 
 one at or near to a red heat, to a considerably 
 less degree. This is mostly accomplished by 
 heating it to a certain extent, and then 
 plunging it into cold water, or in the case of 
 small cutting instruments into grease. (See 
 Case-hardening and Tempering.) 
 
 Hardness, or Rigidity. That quality in 
 bodies by which their parts so cohere as not 
 to yield to external influence ; that is, not 
 changing their form without breaking to 
 pieces. 
 
 Hard Soaps. (See Soap.) 
 
 Hardware. A general term to denote all 
 articles manufactured of metal. 
 
 Hard Waters. Such waters as are im- 
 pregnated with various salts, metals, and 
 earths, in consequence of which they curdle 
 soap when mixed with them. Lime, in some 
 one or other of its numerous combinations, 
 is the most common cause of the hardness of 
 water. 
 
 Hare's Battery Discharger. A name 
 given by Professor Hare to an instrument of 
 his invention ; the object of which is to ascer- 
 tain the power of an electrical battery by the 
 length of wire which the fluid will melt in 
 passing through it at the time of discharge. 
 It consists of a solid wooden foot, upon 
 which two bent arms are placed, one of them 
 being fixed, the other capable of moving 
 around the centre or axis of the foot. The 
 moveable arm is furnished with a small pair 
 of nippers at top. The upper part of the 
 fixed arm is of glass, and is attended by a 
 small screw at top. The lower part, and 
 also the foot of each, is of metal. The fine 
 wire, which is to be made the subject of 
 experiment, is extended across the top, from 
 one stem to the other, they being set at the 
 required distance, and tightened by the screw 
 on the foot of the stand. A shock is passed 
 through the wire, by the effect upon which 
 the power of the battery is ascertained. 
 
 HARE'sCALORiMOTOR.(SeeC«/ori»io/or.) 
 
 Hare's Freezing Apparatus. This 
 apparatus is to prove that water may be 
 frozen by the cold produced by the evapo- 
 ration from sulphuric acid whUe in vacuo, 
 or under an exhausted receiver of an air 
 pump. This instrument was contrived be- 
 cause the experiment frequently fails with 
 an ordinary apparatus. 
 
 A is a tube and stop-cock furnished with 
 a funnel at top, in which a little water is 
 placed. B is a pipe leading to the air pump. 
 C is a similar pipe leading to a barometer 
 gauge. D is a glass vessel fitted with a 
 brass cover at top, and with the wooden foot, 
 as represented. E is a vessel raised within 
 the outer vessel D by means of three short 
 feet. E is filled with sulphuric acid, upon 
 which floats a thin copper cup, containing a 
 very little water. Water is also allowed to 
 trickle now and then down the tube A from 
 the funnel above. The vessel D has sulphuric 
 acid covering the bottom, about half an inch 
 in depth. With the above instrument Pro- 
 fessor Hare was enabled to keep up a con- 
 gelation for several days. 
 
 Hare's Specific Gravity Apparatus. 
 (See Litrameter.) 
 
 Harmonical Arithmetic, is sometimes 
 used for the application of numbers to the 
 science of music. 
 
 Harmonical Curve. An ideal curve 
 into which a musical string is supposed to be 
 inflected, when put into such a motion as to 
 excite sound. 
 
 Harmonical Proportion, is when the 
 first term is to the third, as the diffierence 
 between the first and second is to the dif- 
 ference between the second and third ; or in 
 four terms, when the first is to the fourth, 
 as the difierence between the first and second 
 is to the difierence between the third and 
 
HA 
 
 HE 
 
 fourth. Thus 6, 4, 3, and also 24, 16, 12, 
 and 9, are in h&rmonical proportion. 
 
 Harmony. In the arts, is the agreement 
 between the various parts of a building, pic- 
 ture, or group of statuary, both as to the 
 symmetry of the various parts, their deco- 
 rations, and the tone of coloring. 
 
 Harmony of the Spheres. A sort of 
 music, conceived by ancient philosophers, 
 and supposed to be produced by the sweetly- 
 tuned motions of the heavenly bodies. 
 
 Harpoon. A small spear, with a cord at- 
 tached to it ; used chiefly in the whale fishery. 
 
 Harris's Unit Jar, is a Leyden jar, 
 having a smaller Leyden jar screwed on to 
 the top of it, so that the inside 
 coating of the larger is connected 
 with the outside coating of the 
 smaller jar. If the smaller jar 
 be charged, it may be discharged 
 into the larger, and so on for 
 several times, according to the 
 capacity of each, by which se- 
 veral interesting electrical ex- 
 periments, showing the prin- 
 ciple of charged surfaces, may 
 be performed with facility and 
 effect. It will be readily seen 
 also, that when one of these 
 jars is charged positively, the 
 other jar will be charged nega- 
 tively ; reckoning the inner sur- 
 face of each. 
 
 Harrison's Pendulum. (See Gridiron.) 
 
 Harrow. An agricultural instrument ; 
 used for raking and levelling the earth. 
 
 Hartshorn, Salt of. An impure carbo- 
 nate of ammonia. 
 
 Hartshorn, Spirit of. A solution of 
 amraoniacal gas in water or liquid ammonia. 
 
 Hartshorn Shavings. Formerly ob- 
 tained by shaving the horns of the deer tribe, 
 but now by cutting the bones of calves in the 
 same manner. They afford a nutritious and 
 speedily formed jelly. 
 
 Hart's Galvanic Battery, is com- 
 posed of a number of boxes or cells, made 
 of copper, in each of which is suspended a 
 sheet of zinc. The zinc of one cell being 
 
 connected with the copper of the next, and 
 so on throughout the series. Each piece Ox 
 zinc is kept firmly in its place by three small 
 pieces of wood, and a screw which passes 
 through a square bar of baked wood at the 
 top. This battery is powerful and compact, 
 not requiring porcelain troughs for holding 
 the acid and water, that being placed in the 
 copper cells themselves. 
 
 Harvest Moon. A remarkable pheno- 
 menon relating to the rising of this luminary 
 in the harvest season. During the time she 
 is at the full, and for a few days before and 
 after, in all about a week, there is less diffe- 
 rence in the time of her rising, between any 
 two successive nights, at this than at any 
 other season of the year. In order to con- 
 ceive this phenomenon, it may be first con- 
 sidered that the moon is always opposite the 
 sun when she is full ; that she is full in the 
 signs Pisces and Aries in our harvest months, 
 these being the signs opposite to Virgo and 
 Libra, the signs occupied by the sun about 
 the same season ; and because those parts of 
 the ecliptic rise in a shorter space of time 
 than others. The moon, when about the full 
 in harvest, rises with less difference of time, 
 or more immediately after sunset, than when 
 she is full at other seasons of the year. 
 
 Hatchetine. a kind of bitumen, or fatty 
 matter, found in the argillaceous iron ore of 
 Merthyr. It is fusible at about 160", and 
 inodorous when cold, but of a slightly bitu- 
 minous odour when heated, or after fusion. 
 
 Haunch of an Arch. The part between 
 the springing and the vertex. 
 
 Hauy's Electroscope. No instrument 
 can be more simple than this ; it is nothing 
 more than a light metallic needle, terminated 
 at each end by a light pith ball, which is 
 covered with gold leaf, and supported hori- 
 zontally by a cap at its centre, on a fine point. 
 The attractive or repulsive power presented 
 to one of the balls will be indicated by the 
 movements of the needle. 
 
 Hawser. A large rope or small cable. 
 
 Head of Water. A term signifying a 
 regular height of water in any stream or 
 basin, and intended for the supply of mills, 
 fountains, and the like. Heads of water are 
 usually supported by banks of earth, in the 
 same maimer as dams. 
 
 Headway. A name sometimes applied to 
 the clear height under the arches of bridges, 
 tunnels, &c. 
 
 Headers. In architecture, bricks or 
 stones with their short faces in front. 
 
HE 
 
 HE 
 
 Heading Courses. Those courses of 
 brick or stone-work which consist entirely 
 of headers. 
 
 Heald, or Heddle. That portion of a 
 weaver's loom which imparts motion to the 
 warp of a web during the process of manu- 
 facture. 
 
 Heart Wheel. A contrivance for con- 
 verting a uniform circular motion into a uni- 
 form rectilinear one. It is much employed 
 in the machinery of the cotton and flax 
 manufacture, and is formed after the following 
 manner : — 
 
 Hbartwood. The central or hardest part 
 of a trunk of a tree. 
 
 Heat. Either the sensation of burning or 
 warmth, or the cause of that sensation which 
 is supposed to arise from the presence in an 
 active state of caloric or the matter of heat. 
 (See Caloric.) 
 
 Heat, Latent, Capacity for^ Specific, 8fc. 
 (See Caloric.) 
 
 Heat Regulator. (See Thermostat.) 
 Heaven. In astronomy, the celestial 
 sphere or firmament, or sky ; denotes the 
 spaces in which the celestial bodies are placed, 
 or through which they apparently perform 
 their periodic revolutions. 
 
 HeavenlyBodies. In astronomy, include 
 the sun, planets, and their satellites, the 
 fixed stars, and comets. 
 
 Heavy Inflammable Air. Bi-hydro- 
 guret of carbon, light carburetted hydrogen, 
 fire damp of coal mines, inflammable air of 
 marshes, &c. Under these names an im- 
 portant variety of hydro-carbon is designated, 
 which occasionally occurs pent up in cavities 
 in coal mines, and arises from the mud in fetid 
 ponds and ditches ; but which cannot be pro- 
 cured artificially. It is eight times heavier 
 than hydrogen, burns with a yellow flame, 
 and a slightly disagreeable odour. It con- 
 sists of one volumn of carbon, combined 
 with two of hydrogen. 
 
 Heavy Oil of Wine. (See Oil of Wine.) 
 
 Heavy Spar. Native sulphate of barytes. 
 
 Height. The same as altitude, (which see.) 
 
 Heighten. In painting, a verb signifying 
 
 to make prominent, by means of touches of 
 
 light or brilliant colors, as contrasted with 
 
 the shadows. 
 
 Heliacal. As applied to the rising of a 
 star, planet, &c., denotes its emerging out of 
 the sun's rays, in which it was before hid. 
 When applied to the setting of a star, it de- 
 notes the entering or immerging into the sun's 
 rays, and thus becoming lost in the lustre 
 of his beams. A star arises heliacally when, 
 after it has been in conjunction with the 
 sun, and on that account invisible, it gets at 
 such a distance from him, as to be seen of a 
 morning before the rising of that luminary. 
 
 Heliocentric Latitude of a Planet, 
 is the inclination of the line drawn between 
 the centre of a planet to the plane of the 
 ecliptic. 
 
 Heliocentric Place of a Planet, is 
 the place in the ecliptic in which the planet 
 would appear, if viewed from the centre of 
 the sun ; and consequently the heliocentric 
 place coincides with the longitude of a planet, 
 viewed from the same centre. 
 
 Heliocometes, Comets of the Sun, is 
 used to denote a phenomenon, which some- 
 times attends the setting of the sun. It 
 seems to make a comet of that luminary, 
 having the appearance of a large tail or 
 column of light, which follows the sun at his 
 setting, much in the same manner as the tail 
 of a comet. 
 
 Heliometer. a micrometer, which may 
 be attached to a telescope, so that any small 
 apparent distance between two celestial bodies 
 may be easily ascertained. The best con- 
 structed heliometer is formed of two half 
 lenses, the centres of which may be made to 
 coincide, or to be separated by the screws S S, 
 which act each upon one half lens. The dis- 
 tance between the centres A and B, when one 
 is adjusted to one part of an object, and the 
 other to the opposite part, may be ascertained 
 by a vernier or finely divided scale, scratched 
 upon or annexed to the half lenses. 
 
 Helioscope. A telescope fitted for viewing 
 the sun without dazzling the eyes, by being 
 provided with object and eye glasses that are 
 colored red or green. 
 
 Heliotrope. An instrument invented by 
 Professor Gauss, of Berlin, to reflect light 
 to great distances. It consists merely of a 
 small mirror 3 or 4 inches in diameter, which 
 he says will reflect the sun's light 10 German, 
 or 40 English miles. This instrument has 
 been found useful in trigonometrical surveys, 
 as it reflects the light of lamps as well as 
 that of the sun- 
 
HE 
 
 HE 
 
 Heliotrope. A mineral of a dai-k green 
 color, commonly speckled with red, called 
 therefore bloodstone. 
 
 Helix. A wreath, ringlet, a snail-shell. 
 The smaller scroll or volute in the Coriathian 
 capital, called also the cauliculus or tendril. 
 Helix, in physics, is a coil of wire made long 
 and of the same thickness throughout, as in 
 the following example : — 
 
 Helm. In naval architecture, the appa- 
 ratus for steering or guiding a ship. It is 
 usually composed of three parts, the rudder, 
 the tiller, and the wheel, except in small 
 vessels, where the wheel is omitted. 
 
 Helver. The handle of a digging tool. 
 
 Hematin. (See Hcematin.) 
 
 Hemisphere. The half of a sphere. In 
 geography, that part of the earth, north of 
 the eqmator, is called the northern hemisphere, 
 and the other half the southern hemisphere. 
 
 Hemp. The fibres of the bark of cannabis 
 sativa. It is prepared for spinning, by 
 macerating in water, beating, washing off 
 the impurities, and combing. But little grows 
 in England, the greater part of our con- 
 sumption comes either from Russia, Prussia, 
 or Manilla. 
 
 Hendecagon. (See Undecagon.) 
 
 Henley's Universal Discharger. 
 One of the most useful of philosophical in- 
 struments ; the object of it is to enable the 
 electrician to send a shock of electric matter 
 through a body placed on the table of the 
 instrument, the form of which is as follows ; — 
 
 In the centre is a wooden pillar, with a 
 hole up it, to contain the rod of a small 
 table, which table has a piece of ivory or 
 other non-conductor inlaid across ; the table 
 also is adjusted as to height by a screw in 
 the side of the socket in which it fits. Near 
 each end of the stand is a glass rod, which 
 supports a brass cap and socket, which moves 
 up and down. Through the socket passes 
 a wire, which may be slipped out and in. A 
 ring is at one end of the wire, and a ball 
 that may be taken off or put on at the other. 
 Any thing placed between the two balls re- 
 
 ceives the electrical shock when a current of 
 electricity is made to pass from the one ring 
 to the other. A small press, formed of two 
 thin pieces of wood, adjusted by screws, is 
 occasionally substituted for the centre table. 
 
 Henley's Electrometer. (See Quad- 
 rant Electrometer.) 
 
 Henry's Freezing Apparatus. Dr. 
 Henry recommends the following instrument 
 as one convenient for trying the effect of 
 freezing mixtures : — 
 
 
 
 
 IpHBPl 
 
 WTnamm 
 
 
 
 Wm^ 
 
 iHlli 
 
 ^^S 
 
 ^H 
 
 The outer vessel A A is of wood, about 
 12 inches square and 7 inches deep. It 
 should have a wooden cover rabetted in, and 
 furnished with a handle. Within this is 
 placed a tin vessel B B, standing on feet, 
 which are 1^ inches high, and having a pro- 
 jection at the top half an inch broad and an 
 inch deep, on which rests a shallow tin pan 
 C. Within the second vessel is a third, D, 
 made of imtinned iron, and supported by 
 feet 2 inches high; this vessel is 4 inches 
 square, and is intended to contain mercury 
 or other liquid to be frozen. When in use, 
 this cup, with a little mercury in it, is to be 
 surrounded on all sides ; also above and below, 
 with a mixture of snow and muriate of Hme, 
 when the mercury will soon be frozen by the 
 intense cold produced by the mixture around. 
 
 Hepar. The liver, or any thing of a liver 
 color. Among the old chemists it was sy- 
 nonymous with such sulphurets as approached 
 this color. 
 
 Hepatic Air. Sulphuretted hydrogengas. 
 
 Heptagon. A figure or surface of seven 
 sides. 
 
 Heptagonal Numbers. Any series of 
 numbers formed by adding together the 
 various terms of such an arithmetical series 
 as increases by the addition of 5 each time^ 
 such as the following : — 
 
 Arithmetical series ..1, 6, 11, 16. 
 Heptagonal 1, 7, 18, 34. 
 
HE 
 
 HE 
 
 Herbarium. A collection of dried plants. 
 
 Herisson. In fortification, a beam armed 
 with iron spikes, and used as a barrier to 
 block up a passage. 
 
 Hermetic Art. Alchemy, (which see.) 
 
 Hbrmetical Philosophy, is that which 
 professes to explain all the phenomena of 
 nafure, from the three chemical principles of 
 salt, sulphur, and mercury. 
 
 Hermetical Sealing, is used to denote 
 the perfect closing of vessels, so as to pre- 
 vent the ingress or egress of the most subtil 
 fluids or bodies. In stopping glass vessels 
 it is usual to heat the neck, until it is quite 
 soft, and then twisting it with a pair of 
 pincers. 
 
 Hero's Altar. A kind of fountain, made 
 to have the appearance of an altar with a 
 priest standing beside it, which had the ap- 
 parently miraculous property of supplying 
 itself with oil ; thus acting upon the super- 
 stitious ignorance of the Alexandrians, who 
 considered this altar as under the immediate 
 patronage of their deities. Its construction 
 was exceedingly simple. The body of the altar 
 was hollow, and made of metal. A lower 
 compartment or pedestal to it was ailso of 
 metal, and partly filled with oil, beneath the 
 surface of which dipped the end of a pipe 
 that proceeded along the body of the priest, 
 through his arm, and to the cup in his hand. 
 As soon as a fire was lighted on the body of 
 the altar, the air within it was expanded by 
 the heat, and communicating by a hole at the 
 bottom with the lower vessel, the expanded 
 air pressed upon the surface of the oil so as 
 to drive it up the tube to the cup, from the 
 
 brim of which it overflowed on to the fire 
 beneath it. 
 
 Hero's Fountain. A jet of water which 
 is produced by the condensation of air in the 
 vessel from which it issues, similar in principle 
 to the altar last described. Fig. A shows 
 the outward form, and fig. B the inward 
 structure. It consists of two vessels C and D, 
 which are close on all sides. A tube G, open 
 at both ends, having a funnel at top, passes 
 through the upper vessel, and to near the 
 bottom of the lower one. There is another 
 open tube, H, soldered to the top of the 
 lower vessel, and extending into the upper 
 vessel to near the top of it. These two tubes 
 serve to support the upper vessel. A third 
 tube I is soldered to the top of the upper 
 vessel and extends almost to its bottom. 
 
 Stop the orifice I with the finger, and poui 
 water into F, the funnel. The water will 
 descend into D, will compress what air there 
 is in D, and drive the water up H into C. 
 The air in C will now be compressed, and 
 pressing upon the surface of the water in C, 
 will drive it up the pipe, and through the 
 jet I, producing the fountain of water. 
 
 Hero's Steam Engine. The first attempt 
 to derive motion from the expansion of air 
 or water by fire. The contrivance of Hero 
 is described under the word uEolipile. 
 
 Herring-Bone Work. Course of stone 
 laid angularly. 
 
HE 
 
 HI 
 
 Hkkschel's Aplanatic Combination 
 OF Lenses. The following combination of 
 lenses is recommended by Herschel to be 
 used where the rigorous destruction of 
 aberration for the central rays is required : — 
 Two of the lenses are double convex, with 
 the radii of their surfaces as 1 to 6, having 
 •the most convex side next the eye. The 
 radius of the other glasses (meniscus) are in 
 the first case as 1 to 1*70, and in the other 
 case as 1 to 3*957, with their concave sides 
 exposed to the object. 
 
 The above is to be considered as two illus- 
 trations of the same thing, the only difference 
 being the different focus of the meniscus 
 lens. This combination is strongly recom- 
 mended as an excellent object glass to micro- 
 scopes. 
 
 The following combination is also recom- 
 mended by Dr. Herschel to be used when 
 we are desirous of decreasing the aberration 
 of a lens: — This is made of two plano-convex 
 lenses, the foci of which should be in the 
 proportion of 1 to 2*3, when the aberration 
 will be 0*2481, or about one-quarter of an 
 equivalent lens of the best form. This com- 
 bination has also the advantage of decreasing 
 the distortion of the object and diminishing 
 the prismatic dispersion. 
 
 Herschel's Periscopic Combination 
 OF Lenses, consists of a double-convex 
 lens of the best form, (that is, with the radii 
 as 6 to 1,) but in its worst position. This 
 lens is to be employed for that next the eye, 
 as follows : — A 
 
 And a plano-concave lens B, with its con- 
 cave side next the object. The proportion 
 of the foci of the two lenses being as 5 to 13. 
 By this construction a very extensive field 
 of view is obtained with moderate distinct- 
 ness. In reading glasses and magnifiers of 
 
 lower power a distinct field of 80" may be 
 obtained. 
 
 Heterogeneous. Unlike each other. He- 
 terogeneoMS quantities in mathematics are 
 such as cannot be compared, as lines with 
 surfaces, surfaces with solids, &c. Hetero- 
 genous light, is that which consists of rays 
 of different degrees of refrangibility. 
 
 Heteroscii. In geography, are such in- 
 habitants of the earth as have their shadows 
 at noon always projected the same way with 
 regard to themselves, or always contrary 
 ways with regard to each other. Thus all 
 the inhabitants without the torrid zone have 
 their shadows at noon directed the same way ; 
 viz., always north of them in north latitude, 
 and south of them in south latitude. 
 
 Hewn Stone. Stone reduced to the shape 
 required for use, and cut with a mallet and 
 chisel. 
 
 Hexaedron. The same as cube. 
 
 Hexagon. In geometry, a plane figure 
 bounded by six straight lines. 
 
 Hexastyle. a temple with six columns 
 to the portico. 
 
 Hide. The strong skm of large animals, 
 such as the ox, horse, &c. 
 
 HiERO. (See Hero.) 
 
 HiGHGATE Rosin. A fossil resin, dis- 
 covered on cutting the road through Highgate 
 Hill ; it is embedded in the clay in roundish 
 nodules. 
 
 High Pressure Apparatus. An ap- 
 paratus intended to show that fluids, subjected 
 to a greater degree of pressure than the at- 
 mosphere, require hiejher degrees of heat te 
 make them boil. 
 
 The hollow globe A is composed of two 
 strong hemispheres of brass, screwed toge- 
 ther with flanches ; some quicksilver is first 
 poured into this globe, which is then about 
 half filled with water. The barometer tube 
 B passes through a steam-tight collar, and 
 has its lower end immersed in the quicksilver, 
 C is a thermometer, for ascertaining the tem- 
 perature of the water during the experiments » 
 its scale is graduated up to 400°, and passes 
 through a steam-tight collar. D is the brass 
 
HI 
 
 frame and stand upon which the globe rests. 
 E is a spirit lamp, and F is an aperture, 
 
 HO 
 
 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 follows : — Add four- 
 fifths of the days 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. The 
 time of high water at London, on the day of 
 the full moon, is 3 o'clock in the afternoon. 
 
 Hinge. Metal jointed bands, upon which 
 doors, shutters, lids, &c. turn in the act of 
 opening and shutting. There are twenty 
 or thirty kinds of hinges adapted for various 
 purposes. 
 
 Hip Knobs. Ornaments at the gable end 
 of houses, &c. 
 
 closed by a stop-cock. The stop-cock being 
 closed, and heat being applied, the mercury 
 gradually rises in the tube, indicating the 
 pressure ; while the temperature may at the 
 same time be known by the thermometer C. 
 High Pressure Engine. The simplest 
 form of the steam engine is the non-con- 
 densing or high pressure engine. In this 
 engine the condensing apparatus is done away 
 with, and steam being admitted into the cy- I 
 linder, at a high temperature, and conse- 
 quently high pressure, and having acted on 
 the piston is allowed to escape into the open 
 air. A part of the force of the steam is of 
 course expended in overcoming the pressure 
 of the atmosphere, and it is only that portion 
 of the steam's elastic force, that exceeds 
 15 lbs. to the square inch, that is effective in 
 moving the engine. Tlie surplus pressure is 
 usually from 30 to 40 lbs. on the circular 
 inch. The boiler must be amazingly strong, 
 and the water being heated to a very high 
 temperature, portions are successively let out, 
 and immediately bursts into steam. 
 
 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 
 th« water begins again to ebb or recede. The 
 
 Hippodrome. A horse course, or space 
 of inclosed ground adapted for the exercise 
 of horses. 
 
 HippURic Acid. A peculiar compound 
 deposited from the urine of the horse, when 
 it is mixed with hydrochloric acid. It closely 
 resembles, and is sometimes substituted for 
 benzoic acid, but it contains nitrogen, and 
 its salts are distinct from the benzoates. 
 
 Hips. The pieces of timber that form the 
 angles of a hipped roof, and upon which the 
 rafters are attached 
 
 Hip Roof. A roof whose ends slope in 
 the same degree with the sides. 
 
 Hiptiles. Tiles adapted to cover a ridge 
 or hip, therefore called ridge tiles. 
 
 Hircine. a liquid fatty substance which 
 is mixed with the oleine of mutton suet, and 
 gives it its peculiar rank smell. 
 
 HiRcic Acid. An acid obtained fron; 
 heroine. 
 
 Hoard, Hoarding, or Hording. An 
 inclosure about a building while erecting or 
 under repair. 
 
 HoE. An instrument used in agriculture 
 and gardening, for cutting up weeds and 
 earthing up plants. 
 
 Hold. The whole interior cavity of a 
 ship, comprehended between the floor of the 
 
HO 
 
 no 
 
 lower deck and the bottom of the vessel 
 throughout her whole length. 
 
 Holdfast. The name of a tool, used to 
 hold or retain steadily any work upon the 
 bench whilst being operated upon. The 
 common holdfast is merely a bar of iron bent 
 at right angles, one leg being driven into 
 a slightly oblique hole in the bench, the 
 extremity of the other leg holding the work. 
 The following is a much superior holdfast, 
 invented by Mr. Dungey, of Compton Street, 
 Soho : — The arm A, instead of being one 
 piece, with the rest of the bar, is moveable 
 on the screwed axis B, and is prolonged 
 backwards, as D. In this latter part is a 
 hole for the reception of a handled screw, 
 which bears on a projection of the main bar. 
 C is a hole in the bench E, and F is a flat 
 piece fixed by a loose joint to the arm A, and 
 therefore capable of bearing, by its whole 
 surface, on any piece of work placed under 
 it. By turning the screw in one direction, 
 the work is held fast ; by turning it in the 
 other, the work is loosened. 
 
 Holder of a Magnet. The same as 
 armature. 
 
 HoLiNti. A word used by miners, to 
 signify undermining coal, stone, &c. previous 
 to breaking it down from above. 
 
 Holland. A closely-woven linen cloth, 
 of a peculiar fabric, so called from its having 
 been originally imported from Holland. 
 
 Hollow. A concave moulding, synonymous 
 with casement, (which see.) 
 
 Hollow Newel. A well-hole or opening 
 in the middle of a staircase. The term is 
 used in contra-distinction to solid newel, into 
 which the ends of the steps are built. Hollow 
 newels always belong to geometrical stair- 
 
 Hollow Wall. A wall built in two 
 thicknesses, leaving a cavity between, which 
 may be either for saving materials, or for 
 preserving a uniform temperature in apart- 
 ments. 
 
 Hollow Quoins. In engineering, piers 
 of stone, large bricks, or solid posts of oak, 
 made behind each lock-gate of a canal, 
 which are formed into a hollow from top to 
 
 bottom, to receive the rounded head of the 
 lock-gate. 
 
 Homberg's Phosphorus. When chloride 
 of calcium, that is, perfectly dry muriate of 
 lime, is fused in a crucible, it acquires a 
 phosphorescent property, as was first observed 
 by Romberg, and hence it was termed Hom- 
 berg^s phosjfhorus. 
 
 Homberg's Pyrophorus. When potash 
 alum is ignited with charcoal, a spontaneously 
 inflammable compound results, which has 
 long been known by the above title. 
 
 Homberg's Sedative Salt. Boracic 
 acid. 
 
 HoMOCENTRic. Having the same centre ; 
 the same as concentric. 
 
 HoMOGENEAL. Similar to, or of like parts 
 and qualities. Homogeneal light is that whose 
 rays are all of one, and the same color, de- 
 gree of refrangibility, and reflexibility. 
 
 Homologous. Equal or similar to ; as in 
 mathematics, the corresponding sides of 
 similar figures are homologous. 
 
 Hone. A kind of stone ; called by mine- 
 ralogists tvhet-slaie, used for the sharpening 
 of cutting instruments. The best is found 
 in Germany. 
 
 Honey, a sweet and scarcely fluid sub- 
 stance, 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 ofispring. There are three sorts of 
 honey; virgin honey, which spontaneously 
 flows from the young combs when taken 
 from the hive, and put to drain. White 
 honey, which is thicker than the former, and 
 often indeed almost solid : it is procured by 
 pressing the combs, but without the assistance 
 of heat ; and the common yellow honey, ob- 
 tained from the combs, first heated over the 
 fire, and then pressed. 
 
 Honey Comb. Honey Comb Work. 
 A honey comb is 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 work. 
 
 Hood. A cowl or covering, placed on the 
 top of any thing, as the hood of a chimney 
 pot, &c. 
 
 Hood Moulding. A band or string over 
 the head of a door, so called from its in- 
 
HO 
 
 HO 
 
 closing, as with a hood, the inferior mould- 
 ings. This term, as well as label moulding 
 and weather moulding, are used synony- 
 mously. 
 
 Hoofs of Animals. Coagulated albu- 
 men, like horn. 
 
 Hooke'8 Universal Joint. A contri- 
 vance for producing an alteration in the axis 
 of motion of various parts of machinery. It 
 is either single or double, as exemplified 
 below. If the shanks or spindles to be 
 turned are less inclined to each other than 
 about 140°, the double joint must be made 
 use of. 
 
 Hoop. A pliant piece of wood or metal, 
 made into a ring or circular bandage, for 
 holding together the staves of casks, and 
 other similar purposes. 
 
 Hope's Eudiometer. (See Eudiometer.) 
 
 Hopper. A trough or funnel, employed 
 to supply corn to a mill, fuel to close fuinaces, 
 and a variety of other similar purposes. 
 
 Hops. The dried flower case and seed of 
 a British climbing plant, called by botanists 
 humulvs lupulus, which grows wild in many 
 parts of England ; but for the purposes of 
 commerce and brewing, cultivated chiefly in 
 the counties of Kent and Surrey. There are 
 several varieties in cultivation ; the principal 
 of which are the red bind, the green bind, 
 and the white bind. 
 
 HoaARY. Relating to hours. Horary 
 circles are hour lines or circles, marking the 
 hours on globes, dials, &c 
 
 Horary Motion. The motion or space 
 moved in an hour: the horary motion of the 
 earth on its axis, or the apparent horary 
 motion of the sun is 1°. 
 
 Hordeine. A name given by Proust to 
 the peculiar starchy matter of barley. It 
 seems to be a mixture of starch, lignine, and 
 husk, constituting barley-meal. 
 
 Hording. (See Hoard.) 
 
 Horizon. In geography and astronomy, 
 a great circle in the sphere, dividing the 
 world into two parts or hemispheres, the 
 one, upper and visible, the other, lower and 
 hid. The horizon is eitlier rational or 
 sensible. The rational, true, or astronomi- 
 cal horizon, which is also called simply and 
 absolutely the horiaou, is a great circle whose 
 
 plane passes through the centre of the earthy 
 and whose poles are the zenith and nadir. 
 It divides the sphere into two equal parts or 
 hemispheres. The sensible, physical, visible, 
 or apparent horizon, is a lesser circle of the 
 sphere which divides the visible part of the 
 sphere from the invisible ; or in other words — 
 If a person look around him, emd his view 
 be not obstructed by near objects, the sensible 
 horizon will be his utmost extent of view on 
 all sides, or the circle which bounds his view 
 on all sides. This circle or plane is divided 
 into two parts, the eastern or artive horizon, 
 where the heavenly bodies rise ; and the 
 western or occidual horizon, or that wherein 
 the stars and other bodies set. 
 
 Horizon of a Globe. The broad, wooden, 
 circular ring in which the globe is fixed. On 
 this are several concentric circles which con- 
 tain the months and days of the year, the 
 corresponding signs and degrees of the zodiac, 
 the 32 points of the compass, &c. 
 
 Horizon, Artificial. An instrument used 
 in connection with the quadrant or sextant 
 for obtaining the altitude of a heavenly body, 
 to procure which, a perfectly horizontal re- 
 flective surface is necessary. At sea, in fine 
 weather, the apparent horizon, as seen in the 
 distant water, is sufficient; but during a 
 hazy atmosphere, or when on land, tlie 
 artificial horizon is necessary. It consists of 
 a triangular box, the two sloping sides of 
 which are of glass. The box, which is 
 without a bottom, is placed over a shallow 
 dish of quicksilver. The ray of light from 
 the heavenly body A strikes the fltiid mercury 
 B, and is reflected by an equal distance to 
 the eye, or in other words, the quadrant 
 ate. 
 
 Horizontal. Relating to or parallel with 
 the horizon. A horizontal dial is one drawn 
 on a plane parallel to the horizon, having its 
 gnomon, or style elevated according to the 
 altitude of the pole of the place it is designed 
 for. Horizontal distance is that estimated 
 in the direction of the horizon. Horizontal 
 line, or base of a hill, in surveying, is a line 
 drawn on the horizontal plane of the hill, or 
 that surface on which it stands. Horizontal 
 moon, is the moon when rising or setting, at 
 which time she appears considerably larger 
 and redder than when nearer the zenith. 
 
 Horizontal Line. In perspective, is 
 such an imaginary line in a j)icture as is 
 parallel to the horizon, and at the height of 
 
HO 
 
 HO 
 
 the eye. It therefore passes through the 
 centre of the picture. 
 
 Horizontal Wheel, or Tub Wheel, 
 is a water wheel which is supported hori- 
 zontally, and moved by the stream of water 
 washing against one side of it. This method 
 is said to be common on the Continent, but 
 is seldom employed in England, on account 
 of the disadvantageous method in which the 
 power is appUed. 
 
 Horizontal Windmill. This name is 
 given to those windmills which turn on a 
 vertical axis. In the most common forms, 
 the sails, like float boards, present their 
 broadside to the wind on the acting side of 
 the wheel, but are folded up or turned edge- 
 wise on the returning side. These wheels, 
 however, are found to be greatly inferior to 
 the vertical windmill, in the amount of work 
 which they are capable of performing. 
 
 Hornblower's Steam Engine, is an 
 expansive engine, the principal force of which 
 is produced in two cylinders. The figure 
 annexed will give a general idea of this con- 
 trivance without showing any of the smaller 
 parts, which being similar to those of common 
 engines, and not to confuse the figure, are 
 omitted. A is a small cylinder, having a 
 piston within it, the rod of which is attached 
 to the beam ; this cylinder communicates 
 with the boiler by the pipe K. E is a pipe 
 with a stop -cock, which opens a communi- 
 cation between the bottom of the small 
 cyUnder A and the top of the larger cylinder 
 B. F is a pipe and cock leading to the con- 
 denser. 
 
 Horn. An animal substance, chiefly mem- 
 braneous, composed of coagulated albumen, 
 with a little gelatine, and abor.t half a per 
 cent, of phosphate of lime. The word horn 
 is also used by architects to signify the Ionic 
 volute, and artizans call by the word horn 
 any piece of timber, or metal, which projects 
 beyond the general surface, or beyond that 
 part of the timber which is useful. 
 
 Horn, Artificial, or Thinned Gelatine. 
 A French manufacture, for the construction 
 
 of a variety of articles, such as snuff boxes, 
 knife handles, &c. The gelatine is obtmned 
 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 hard and dry, it 
 assumes the appearance of horn or tortoise- 
 shell. It is softened by being boiled in water 
 with potass, when it may be formed into any 
 shape, and the figure preserved by drying the 
 articles between moulds. 
 
 Horn Drum. A particular kind of machine 
 for raising water, very similar to De la Faye's 
 pump. It is formed of a number of segments 
 passing from the circumference of a large 
 flat cylinder to its centre. The mouths or 
 scoops, at the circumference of the wheel, 
 by turns dip into the water, and as they rise 
 retain it, until passing over to the other side, 
 the water is discharged into a trough prepared 
 to receive it. The following cut shows the 
 horn drum in section, whereby its con- 
 struction may be immediately understood:— 
 
 Hornsilver. Chloride of silver. 
 
 Horography, or Horologiography. 
 The art of dialling, or otherwise ascertaining 
 the hours. 
 
 Horology. The art of constructing 
 machines for measuring time ; but from the 
 circumstance of clocks and watches having 
 very generally superseded all other con- 
 trivances for this purpose, the term is now 
 usually understood as referring to these 
 instruments solely. 
 
 Horopter. In optics, is a right line 
 drawn through the point where the two optic 
 axes meet parallel to that which joins the 
 two pupils. 
 
 Horoscope. In the exploded science of 
 astrology, denoted the degree or point of the 
 heavens rising above the eastern point of the 
 horizon at any given time, when a prediction 
 was to be made of a future event ; as the 
 fortune of a person then bom ; the success 
 of a design then laid; the weather, &c 
 Horoscope is also used for a scheme or figure 
 
HO 
 
 of the twelve hours, that is, the twelve signs 
 of the zodiac, wherein is marked the position 
 of the heavens for any given time. 
 
 Horse-power. In steam engines, is 
 estimated by Mr. Watt, that 30,000 pounds, 
 avoirdupois, lifted one foot per minute for 
 one horse. A steam engine, therefore, which 
 is capable of doing twenty times this work, 
 is said to be of twenty horse-power, and so 
 on for other measurements. 
 
 HoRSE-SHOE Magnet. (See Magnet.) 
 Hose. A term given to a flexible tube 
 attached to hydraulic engines, for conveying 
 water or other fluid to any required point. 
 
 Hot-beds. In gardening, are beds made 
 of fresh horse-dung or tanners' bark, and 
 covered with glasses to defend them from 
 inclement weather. 
 
 HoT-HousE. A garden erection, 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, strfctly speaking, the 
 art of applying heat in conjunction with 
 mechanical pressure; but it is generally 
 understood to mean the employment of that 
 process to paper, linen, and similar fabrics, 
 by which they acquire a smooth and glossy 
 surface. The mode of operating is as follows : — 
 A number of stout iron plates are heated 
 in an oven constructed for the purpose ; 
 when they have acquired the proper tempera- 
 ture, they are taken out and put into a screw 
 press, in alternate layers, with the goods to 
 be pressed ; and when paper is the material 
 to be operated upon, the various sheets are 
 put also between glazed boards, the smooth- 
 ness of which communicates the lustre by 
 which hot-pressed paper is distinguished. 
 
 Hour. An aliquot part of a natural day, 
 usually a twenty -fourth part, but among the 
 ancient Egyptians and Jews, a twelfth part. 
 
 Hour Circles, are depicted on the 
 artificial globe ; they are great circles of the 
 sphere meeting in the poles of the world, 
 and crossing the equator at right angles. 
 They are drawn through every fifteenth 
 degree of the equator or equinoctial, conse- 
 quently there are 24 around the circle, each 
 answering to an hour. 
 
 Hour Glass. A popular kind of time- 
 keeper, which indicates the hours by the 
 running of sand, water, or mercury, from 
 one vessel to another. 
 
 Hour Lines on a Dial, are those which 
 are drawn for the purpose of pointing out 
 the hours by the progress of the sim. 
 
 Houriet's Pyrometer, or Metalline 
 Thermometer. An extremely delicate and 
 compact instrument, which indicates with 
 rapidity and exactness, the smallest changes 
 of temperature. It is made in the foim of 
 tho common watch, marked on the face with 
 
 HU 
 
 a certain number of degrees, and having a 
 fine hand passing through the centre, by 
 which the indications of the instrument are 
 seen. Under the dial is the simple spring- 
 work seen in fig. 2, where A, B, C, is a 
 compound bar or wire coiled up and doubled 
 upon itself for the sake of convenience. This 
 part is composed of a plate of steel and one 
 of brass united together into one bar. The 
 steel plate is one-fiftieth of an inch in thick- 
 ness, and the brass twice as much, forming 
 altogether a bar 9^ inches in length and 
 about one-seventh of an inch m depth. One 
 extremity of this is fastened at C to the 
 frame. The other end is free to press against 
 the short arm E of the lever E, F, the longer 
 arm F turning a small toothed wheel which 
 works the hands on the opposite side of the 
 dial. Under G is a slight wire spring to 
 keep the lever closely pressed against D 
 during its recoil by cold. 
 
 Howard's Thermometer. This is a 
 modification of the valuable diff'erential ther- 
 mometer of Mr. Leslie : it 
 being considered by Dr. Howard 
 as more convenient, from occu- 
 pying less lateral space, and 
 from having one ball elevated 
 above the other. The included 
 liquor is not sulphuric acid, as 
 in Leslie's instrument, but alco- 
 hol or ether, colored, which is 
 made to boil for the purpose of 
 excluding the air. It is furnished 
 with a scale of 100 equal parts, 
 and is fixed to a wooden support. 
 When both balls are exposed to 
 the same temperature it is not 
 in the least affected ; but as soon 
 as one of the bulbs is exposed 
 to a higher temperature than 
 the other, the difference between 
 them is delicately shown by the falling of 
 the colored fluid below the bulb which ia 
 most heated. 
 
 Hue. In painting, any degree of strength 
 or vividness of color, from its greatest or 
 deepest, to its weakest shade. Hue is usually 
 applied to mixed or compound colors, and 
 tint, to the primitive or single colors. 
 
 Humidity. Moisture ; the quality or 
 power of wetting or moistening other bodies. 
 
HtT 
 
 HU 
 
 Hundred of Lime. A denomination of 
 measure ; in some places denoting 35, and 
 in others, 25 heaped bushels or bags. 
 
 Hungarian Machine. An instrument 
 for raising water, so called from its being 
 employed in draining a mine in Chemnitz, 
 in Hungary. It produces its action by the 
 condensation of a confined portion of air, 
 produced by the descent of a high column 
 of water contjuned in a pipe, and therefore 
 acts with a force proportionate to the weight 
 of such column. 
 
 A is supposed to be a well or the shaft of 
 a mine, from the bottom of which it is 
 necessaiy to raise the water standing at the 
 level B to the surface of the groimd C, where 
 the discharged water must have an oppor- 
 tunity of escaping, either by running to waste 
 or being converted to some useful purpose. 
 H is supposed to lead from the spring or 
 other elevated source, whence the supply of 
 water for working the machine may be 
 obtained. The acting part of the machine 
 consists of two cisterns, D and J, both made 
 strong and air-tight. The lower cistern is 
 sunk beneath the surface of the water in the 
 well, yet is not quite in contact with the 
 bottom of it. An open pipe F passes from 
 near the bottom of this cistern through its 
 top in an air-tight manner, and proceeds 
 upwards as far as the surface of the ground, 
 where it bends over to deliver the water, as 
 at G. Another open pipe I, which may be 
 of rather smaller dimensions than the last, 
 proceeds from the top of the lower chest to 
 very near the top of the chest J ; and a third 
 pipe of the same capacity as the first, pro- 
 ceeds from very near the bottom of this 
 chest up to the reservoir or sjjring, but has 
 a cock in it at K, by which it can be oc- 
 
 casionally shut or opened. A cock of large 
 dimensions is also fixed at M to withdraw 
 the water from J, and a smaller cock I for 
 discharging its air. To put the machine in 
 action, shut the cocks K and M, and open 
 the cock I. This, by withdrawing the air, 
 will fill D with water, which passes through 
 the valve E. When D is full of water, the 
 cock I is to be shut and K opened, when a 
 column of water, equal to the full height 
 and pressure of the cistern forming th( 
 reservoir, will rush down, partly fill J witl 
 water, condense the air above this, and als«' 
 condense the air in D, and this pressing oi 
 the water in D will drive it up the pipe F. 
 
 Hungary Water, is made by distillin) 
 in a water bath, two pounds of the fresl 
 gathered flowers of rosemary, with two quart, 
 of spirits of wine. 
 
 Hunter's Screw. An instrument c 
 great mechanical efficiency, the contrivanc 
 of Mr. Hunter, surgeon. A perspectiv. 
 drawing is given in the following cut :— 
 
 E E is a strong frame in which a board D 
 moves, so that when it is forced towards the 
 bottom it will exert a pressure on any 
 substance placed beneath. To the board D 
 is attached the screw B. C is a fixed board, 
 through which a screw A passes. The screws 
 move within each other, and according to the 
 relative size of the thread of each, so will 
 be the power of the whole. 
 
 Hunting Cog. When wheels of exact 
 ratios work into each other, there is ofte^-. 
 occasioned an inequality of wear arising from 
 one, two, or more cogs being of harder or 
 softer material than the rest. This is much 
 increased by the exact relative ratio of the 
 two wheels, because each cog of one wheel 
 meets the same cog of the other wheel a 
 certain number of times in every revolution 
 of the large cogs ; for example, if one wheel 
 have sixty cogs, and the other ten, the same 
 cog of the smaller wheel will always strike 
 every sixth cog of the other, and when this 
 has been turned once, it will take hold upon 
 the same cog again. To avoid this, the 
 larger wheel should be made with sixty-one 
 cogs ; the odd one, being called the hunting 
 
HY 
 
 HY 
 
 Hyacinth. A gem of a red, brown, or 
 more rarely, yellow, or green color. It occurs 
 in small angular crystals of considerable 
 lustre ; it is harder than quartz, but softer 
 than topaz. The best is brought from Ceylon. 
 
 Hydrates. Compounds in definite pro- 
 portions of metallic oxydes with water. 
 
 Hydraulics, is the science which explains 
 the laws and properties of fluids in motion. 
 
 Hydraulic, or Hydrostatic Press. 
 (See Bramah.) 
 
 Hydraulic Engines. All kinds of 
 machines which either receive motion from 
 the weight or impulse of water, or are 
 employed in raising it. (See Lift, Force, 
 Suction, Chain, Rope, and other Pumps, 
 Archimedes's Screw, Hungarian Machine, 
 Bucket Engine, Horn Drum, De la Faye, De 
 la Hire, 8fc. 8fc.) 
 
 Hydraulic Blow-pipe. (See Tilley.) 
 
 Hydraulicon, or Water Organ. A 
 musical instrument acted upou by water, the 
 invention of which is said to be of higher 
 antiquity than the wind organ. We are not 
 aware that its construction is anywhere 
 described. 
 
 Hydriodates. Salts consisting of hydrio- 
 dic acid combined in definite proportions 
 with various oxydes. 
 
 Hydrochloric Acid. Muriatic Acid. 
 A compound of chlorine and hydrogen. 
 In chemistry and medicine, the term Ixydroch- 
 loric acid ; and for its salts, the term hy- 
 drochlorides is used; but in the arts and 
 manufactures, the older words muriatic acid 
 and muriates are still mostly employed. 
 
 Hydrochlorides. Combinations of hy- 
 drochloric acid and various bases. 
 
 Hydrocyanic Acid. Prussic acid, (which 
 see.) Acompound of cyanogen and hydrogen. 
 
 Hydrodynanics. The science which 
 treats of the mechanical properties of fluids 
 in general. It is divided into hydrostatics, 
 hydraulics, and pneumatics. 
 
 Hydrogen, is a colorless gas, perma- 
 nently elastic, without taste, and when per- 
 fectly pure, without smell. It is the lightest 
 body known, being sixteen times lighter than 
 oxygen, or tlxirteen times lighter than atmo- 
 spheric air ; its specific gravity being 0*0694, 
 and 100 cubic inches of it weighing 2*118 
 grains. It cannot support combustion or 
 respiration, but is itself in an eminent degree 
 inflammable, requiring, however, oxygen to 
 support the combustion ; it may be set fire 
 to by any material made red hot, it explodes 
 when mixed with oxygen or the atmospheric 
 «ir, forming water, and its heat when burning 
 is greater than that of any other material. 
 
 Hydrography. That part of geography 
 which relates to seas or oceans. 
 
 Hydrographical MivP. A chart re- 
 presenting the ocean, or some part of it, 
 seas, rivers, &c. 
 
 Hydrology. A discourse upon the me- 
 chanical properties of water, or the science 
 of hydrodynamics. 
 
 Hydromancy. Divining by water. This 
 branch of the cabalistic art was performed by 
 means of a vessel, called a hydromantic ves- 
 sel, constructed as follows : — A B is a square 
 box with the glass partition C fixed water- 
 tight across it. Under this is a mirror D 
 placed at an angle of 45°, and in the side 
 opposite to it a tube holding a lens E. What- 
 ever was put before the lens, as for example, 
 the answer to a question, was reflected from 
 the mirror D to C, and through the water 
 above to the eye of the inquirer. If the 
 lens be extended through a partition, the 
 deception is more complete. 
 
 Hydrometer. An instrument for ascer- 
 tsuning the specific gravity of different liquids. 
 The commonest hydrometer is 
 formed of a glass tube, as in 
 the margin, the lower ball 
 being partly filled with shots, 
 and the stem containing a 
 paper scale. This being all 
 glass externally, it may be 
 applied to ascertain the specific 
 gravity of acids and other 
 corrosive substances. For as- 
 certaining the strength of 
 spirits, a superior instrument 
 is used, invented by Mr. Sikes ; 
 it is shown in the margin, and 
 is formed wholly of brass, and 
 may be described as consisting 
 of three parts : — A the scale, B the ball, and 
 C the stem, which terminates in a small 
 knob, intended to keep the instrument 
 upright when in use. Upon this being put 
 into a long glass, containing spirits of wine, 
 brandy, gin, &c. it will sink to a certain 
 depth. If the spirit be very weak, it may 
 not sink low enough to cover the ball B, in 
 which case one of the weights D, E, F, or 
 G, is placed above the knob of the lower 
 stem. According to the weight used, and 
 the degree to which the instrument sinks, 
 reference being had also to the temperature 
 of the fluid, the degree of strength is ascer- 
 tained. 
 
 Hydrometer Proof. An expression used 
 by distillers, publicans, and others, to signify 
 
HY 
 
 HY 
 
 a standard degree of strength of spirits of 
 any kind. The scale of the spirit hydrometer 
 is considered to range from 0, which signifies 
 water ; to 200, which indicates pure or absolute 
 alcohol. Half way between these two points, 
 that is, 100, is hydrometer proof, and the 
 strength of spirits is considered according to 
 this point. Thus, cordials, such as pepper- 
 mint, anise, &c. do not indicate a quantity 
 of spirit above 50° under proof , or are three- 
 quarters water. Best gin is about 22 per 
 cent, under proof. Strong brandy, 8 per 
 cent, over proof; and the strongest spirits 
 of wine that can be made by ordinary distil- 
 lation, about 66° mer proof, or it maybe said 
 to have one- sixth part water still attached 
 to it. 
 
 Hydrgmetry. The mensuration of water 
 and other fluids ; their density, gravity, 
 force, &c. 
 
 Hydrometric. Said of substances which 
 are easily affected by changes in the weather, 
 becoming dry or moist as the atmosphere 
 becomes so, or which readily absorb, and 
 part with moisture. Among such substances 
 are sea weeds, uncleaned sponge, several 
 saline substances, porous clays, potass and 
 its carbonate, sulphuric acid, chloride of 
 lime, &c. Dried animal bodies, such as 
 catgut, ropes, linen, &c. 
 
 Hydrogurets. Combinations of hydro- 
 gen and various bases. Thus most of the 
 carburetted hydrogens are hydrogurets of 
 carbon. 
 
 Hydroguret of Phosphorus. CSee 
 Phosphuretted Hydrogen.) 
 
 Hydroscope. An ancient instrument for 
 measuring time by the running of water. 
 (See Clepsydra.) 
 
 Hydrostatics. The sciencewhich explains 
 the properties of the equilibrium and pressure 
 of liquids, particularly of water, when in a 
 state of rest. 
 
 Hydrostatic Balance. An instrument 
 used for determining very accurately the spe- 
 cific gravity of bodies, whether fluid or solid. 
 There are various constructions given to this 
 instrument, but the following appears to be 
 one of the most accurate and delicate : — 
 A C C is the stand or pillar of this hydro- 
 static balance, the lower end of which is fixed 
 in a table. From the top A hangs, by two 
 silk strings, the horizontal bar B, from which 
 is suspended from a ring the fine beam 
 of a balance G, which is prevented from 
 descending too low on either side by the 
 gently springing piece F, supported by the 
 projecting arm E. The strings by which 
 the balance is suspended passing over two 
 pullies, one on each side of A, are carried 
 over a third pulley on the top of C, through 
 which they descend, and are attached to a 
 small lever at D, by means of which the ba- 
 lance is hfted or depressed when in use. H H - 
 
 is a small board, fixed to the stand, and xmder 
 the scales, and is moveable up and down on 
 the stand C, and fastened at any part by 
 means of a screw behind. From the point 
 in the middle of each scale hangs by a fine 
 hook a fine brass wire. These pass through 
 two holes in the table H H. One wire, 
 marked J O, is covered with a case of another 
 wire, which is marked in degrees and minutes, 
 arid is about 5 inches long. This passes 
 easily and smoothly through a hole in a bent 
 arm, projecting below the board H H. To 
 the lower end of the wire J O is suspended a 
 weight, and below that a wire with a small 
 brass ball P. To the wire I of the other 
 scale is suspended, by a single horse hair, 
 a large glass bubble. 
 
 Hydrostatic Bellows. (See Bellows.) 
 Hydrostatic Paradox, is that any 
 quantity of water, however small, may be 
 made to lift and balance any quantity however 
 great; thus, water in a pipe open at both 
 ends always rises to the same height in 
 each, whether those ends be wide or narrow, 
 equal or unequal. Thus, the small quantity 
 of fluid which fills the pipe B D in the 
 following illustration exactly balances the 
 large quantity of fluid in the vessel A E C, 
 the fluid standing at the same level in each. 
 It is quite immaterial what is the shape of 
 either vessel, or their relative sizes. The 
 weight of water in B D, be it ever so small, 
 
 H H 
 
HY 
 
 IIY 
 
 will nevertheless counterbalance that con- 
 tflined in the other vessel, however large or 
 however irregularly shaped it may be. 
 
 Hydrostatic Press. (See Bramah.) 
 
 Hydrous. Watery, or any thing con- 
 taining water in its composition. 
 
 Hydro -Oxalic Acid. A peculiar acid 
 formed during the action of nitric acid on 
 sugar, gum, and other substances. "When 
 in its utmost state of concentration, it is in 
 the form of a syrupy, colorless, inodorous, 
 and intensely sour liquid, of the specific 
 gravity of 1-415 at 60° Fahr. It is deli- 
 quescent, and unites in all proportions with 
 water and alcohol, but is only sparingly 
 soluble in ether. 
 
 Hydrurets. Compounds of hydrogen 
 with metals. 
 
 Hydro-Oxygen Blow-pipe. (See Clarke 
 and Gurney.) 
 
 Hydro-Oxygen Microscope. A mi- 
 croscope, the illuminating power of which is 
 derived from the intense reflection of light 
 produced by throwing the oxygen and hy- 
 drogen gases in an inflamed state upon lime. 
 (See Oxy -Hydrogen Microscope.) 
 
 Hydro-Phosphoric Gas. Hydro-phos- 
 phorous acid when in a gaseous state. 
 
 Hydro-Phosphorous Acid. A peculiar 
 combination of the phosphuric acid and hy- 
 drogen. It is not spontaneously inflamma- 
 ble, but explodes when heated with oxygen. 
 
 Hydro-Pneumatic Apparatus. A ge- 
 neral name for all the apparatus used in the 
 holding, measuring, making of, and otherwise 
 experimenting upon those gases which are 
 not absorbable by water, or which are ab- 
 sorbable in so small a degree as to render the 
 partial absorption of little practical conse- 
 quence. The hydro -pneumatic apparatus 
 may be said to comprise gasometers and 
 holders, gasjars, retorts, gas cocks, receivers, 
 pneumatic troughs, &c. 
 
 Hydro -Sulphates. Combinations of 
 sulphuretted hydrogen gas with various bases, 
 particularly metallic ; forming variously co- 
 lored pigments, called the metallic hydro- 
 sulphates. 
 
 Hydro-Sulpho-Cyanic Acid. A triple 
 compound of cyanogen, sulphur, and hydro- 
 gen. 
 
 Hydro - Sulphurets. Compounds of 
 sulphuretted hydrogen with the salifiable 
 bases. 
 
 Hydro-Sulphuric Acid. (See HydrO' 
 thionic Acid.) 
 
 Hydro-Sulphurous Acid. When two 
 volumns of sulphuretted hydrogen are mixed 
 in an exhausted vessel with one of sulphurous 
 acid they mutually decompose each other, 
 occasioning the production of water and the 
 deposition of sulphur. According to Thomp- 
 son, the deposited matter is not sulphur, 
 but a compound of sulphur, oxygen, and hy- 
 drogen, which he calls hydro-sulphurous acid. 
 
 Hydro -thionic Acid. Sulphuretted 
 hydrogen ; the hydro -sulphuric acid of M. 
 Gay Lussac. 
 
 Hygrometer, or Hygroscope. An in- 
 strument for ascertaining the degrees of 
 dryness or moisture of the atmosphere ; 
 therefore whatever substance expands by 
 moisture, or contracts by dryness, may be 
 employed for the purpose, in connection 
 with a suitable index and scale, showing 
 the changes it undergoes. The following 
 is a very simple and easily constructed hy 
 grometer : — 
 
 
 A 
 
 h 
 
 
 
 (3 m 
 
 (t5 \;.\ 
 
 \m 1 
 
 
 k& 
 
 <d 111! 
 
 C 
 
 L 
 
 R 
 
 4 
 
 A is a long piece of catgut, fastened to a 
 pin at one end, and made to pass over a 
 number of small pulleys, as represented, 
 terminating at the lower end with a small 
 weight, behind which is a scale of equal 
 parts. According to the drought or moisture 
 of the air, so the catgut will contract or 
 lengthen, the degree of such alterations 
 being indicated by the weight in front of 
 the scale. 
 
 Hygrometer, Thermometric. (SeeLesKe) 
 
 Hyosciana. a vegetable alkali, extracted 
 from the hyoscianus niger, or henbane. It 
 is a strong poison. 
 
 Hyp^thral Temple. A temple with 
 
IC 
 
 IC 
 
 ten columns in front and at the back, and 
 also two rows of columns entirely round the 
 walls of the building. The centre part, or 
 cell, was open to the air at top. 
 
 Hyperbola, Apollonian Hyperbola, 
 or Hyperbolic Curve. One of the sections 
 of a cone, being that which 
 is made by a plane perpen- 
 dicular to the base, but not 
 passing through the apex, as ap- 
 pears in the annexed cut, where 
 two hyperbolas are seen to be 
 cut off two opposite cones. 
 The next figure shows part of 
 the curved lines of these hyper- 
 bolas, with their different parts 
 and properties. A B joins the 
 vertices of the cones or hyper- 
 bolas. Bisecting A B in C, any 
 right line drawn through C, 
 which is called the centre, and terminating 
 in both curves, is a transverse diameter, and 
 of all these diameters A B is the shortest. 
 
 V 
 
 \ 
 
 D 
 
 J^ 
 
 \ 
 
 A 
 
 
 
 c) 
 
 /\ 
 
 
 / 
 / 
 
 
 / 
 
 /J 
 
 
 /- 
 
 ^^ E 
 
 ^^ 
 
 /A 
 
 I'l 
 
 
 Two points, D and E, in the line of the cutiSj 
 equally distant from either vertex of the 
 hyperbola, are called their foci ; and these 
 are so situated, that if we take any point, 
 M, in either of the curves, and draw the 
 straight lines M D and ME, the difference 
 of the length of those lines will always be 
 equal to A B, the shortest transvei'se dia- 
 meter. Again, any straight line, M F G, in 
 either hyperbola, crossing the axis at right 
 angles, and terminating at both ends in the 
 curve, is a double ordinate. M F, F G are 
 ordinates, and F B is the abscissa. 
 
 Hyperbolic Conoid, or Hyperboloid. 
 A solid formed by the revolution of an hy- 
 perbola about its axis. 
 
 Hyperoxymuriates. The old name for 
 chlorates. 
 
 Hypo. In chemistry, under, or an inferior 
 quantity ; thus hyposulphurous acid contains 
 less oxygen than the sulphurous acid, and 
 the hyposulphuric acid contains less than the 
 sulphuric. 
 
 Hypothenuse. The longest side of a 
 right-angled triangle. 
 
 Hypothesis, is generally a proposition or 
 principle which is supposed or taken for 
 granted, in order to draw conclusions for 
 the proof of a point in question. In physics, 
 it denotes a kind of system laid down from 
 our own imagination, whereby to account for 
 some phenomenon or appearance of nature. 
 Thus, we have hypothesis to account for the 
 tides, for gravity, electricity, &c. Hypo- 
 thesis, in astronomy, is often synonymous 
 with system ; thus, we have the Copemicsui 
 hypothesis, or system. 
 
 Hypotrachelium. The upper extreme 
 end of a column dividing the shaft from the 
 capital. It is only found in the more enriched 
 orders of architecture, where it is an astragal 
 or small round bead, (for figure, see Astragal.) 
 The term is generally applied to the Tuscan 
 and Roman Doric orders. 
 
 It the ninth letter 
 and third vowel of our 
 own and of most other 
 European languages, 
 having a soft open 
 sound. It is one of 
 the simplest of cha- 
 racters, being made 
 by a single stroke. It is, in classical words, 
 often interchanged with E ; and when two 
 I's follow each other, one was often among 
 the ancients omitted, as di for dii. As a 
 Roman numeral it signifies 1, and placed 
 before V or X, it diminishes by a unit 
 the number expressed by these two letters. 
 
 J is by some persons now considered a 
 distmct letter, but the form of both was 
 originally the same, and it is only within the 
 last century that any distmction was made 
 between them. 
 
 Iatrophic Acid. A name which has been 
 given to the acrid principle of croton oil, 
 Brande has since called it crotonic acid. 
 
 Ice. Water in a solid, crystallised state, 
 owing to the abstraction of its latent caloric. 
 Its specific gravity is 92, or rather less than 
 that of water. Water deprived of its air by 
 long boiling, or by being kept a long time 
 in the exhausted receiver of an air pump, 
 and then frozen, forms an ice more hard, 
 
ID 
 
 IM 
 
 solid, heavy, and transparent than common 
 ice. Ice after it has formed, continues to 
 expand by diminution of temperature. 
 
 Iceberg. The name given to the masses 
 of ice resembling mountains, often found 
 floating in the Polar seas. They are some- 
 times formed in the sea itself, by the ac- 
 cumulation of ice and snow ; at other times 
 they appear glaciers, which have been piling 
 up on shore till quite overgrown, and 
 ultimately broken and cast into the sea by 
 their own weight. 
 
 Ice-Beareu. (See Cryophorus.) 
 
 IcE-BoATS are of two kinds, one of which 
 is a common boat fixed upon a board, which 
 is furnished with irons like skates. It is 
 propelled by the wind impinging upon the 
 sails. The other kind of ice-boat is a heavily 
 laden barge, drawn along a frozen canal by 
 a number of horses, and in its passage break- 
 ing through the ice, and thus clearing the 
 navigation. 
 
 IcE-HousE. A repository for ice during 
 the summer season. In London, ice is pre- 
 served usually by fishmongers and con- 
 fectioners, by placing it on a frame of wood- 
 work in a dry, deep cellar, and covering it 
 over with a thick layer of straw. A large 
 heap of ice may thus be presei'ved on the 
 surface of the ground, provided the situation 
 be dry, and it be well covered. 
 
 Ice -Saw. A large saw used for cutting 
 through the ice, for relieving ships when 
 frozen up. 
 
 Iceland Spar. A fine variety of crystal- 
 lised carbonate of lime, remarkable for its 
 clearness, and for the beautiful double re- 
 fraction which it exhibits. (See Calcareous 
 Spar.) 
 
 IcHNOGRAPHY. In drawing, is synonymous 
 with jtf/an drawing, or making the horizontal 
 or perpendicular plan of a building or object, 
 each part of which has its proper relative 
 proportion. 
 
 IcoNOLOGY. A description of pictures, 
 statues, &c. 
 
 Icosahedron. In geometry, a regular 
 solid, consisting of twenty triangular pyra- 
 mids, whose vertices meet in the centre of a 
 sphere, which is supposed to surround it, 
 and therefore have their height and bases 
 equal. 
 
 Idrialing. The term is applied by Dumas 
 to a native hydrocai'bon found in the mercuiy 
 
 mine of Idria, in Camiola, and which appears 
 to be very analogous to naphthaline. 
 
 Igasuric Acid. A name given by Pelletier 
 and Caventou, to an acid which is found 
 combined with strychnia in the nux vomica, 
 and in St. Ignatius's bean. 
 
 Ignition. The setting fire to any thing, 
 but 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. 
 
 Ignis Fatuus. A kind of luminous meteor 
 which flits about in the air a little above the 
 surface of the earth, and appears chiefly in 
 marshy places, or near stagnant waters, 
 during the nights of summer. There are 
 many instances of travellers having been 
 decoyed by these lights into bogs, where 
 they perished, and hence the terms Jac/c- 
 with-a-Lanthorn, Will-wit h -a- Wisp ; the 
 people ascribing the appearance to the agency 
 of evil spirits, who take this way of alluring 
 men to their destruction. The cause of the 
 phenomenon does not appear to be perfectly 
 understood ; it is generally supposed to be 
 produced by the decomposition of animal and 
 vegetable matters, or by the evolution of 
 gases which spontaneously inflame in the 
 atmosphere. 
 
 Ignition. The act of kindling or taking 
 fire ; a term opposed to the continued com- 
 bustion or burning which afterwards ensues. 
 
 Illuminating. Enlightening. In the arts, 
 applied to a particular kind of miniature 
 painting, anciently much practised for illus- 
 trating and adorning books. Many of the 
 initial letters of this book are taken from the 
 illuminated letters of eincient manuscripts, 
 as A, B, C, and F. 
 
 Image. In optics, the appearance of an 
 object made either by reflection or refraction. 
 
 Imagery. In architecture, painted or 
 carved work. 
 
 Imaginary Quantities, or Impossible 
 Quantities, are certain expressions that 
 ax-ise in various algebraical and trigonometrical 
 operations, to which no value either rational 
 or irrational can be assigned ; yet being 
 substituted in the equation, whence they 
 were deduced, they are found to answer the 
 conditions of the question. 
 
 Imbow. To arch over ; to vault. 
 
 Imbowment. An arch or vault. 
 
 Immersion, In astronomy, denotes the 
 disappearance of any celestial object behind 
 another, or in its shadow. Thus, in the 
 echpse of one of Jupiler's satellites, the 
 immersion takes place when the satellite 
 disappears behind the body of the planet, or 
 enters into the planet's shadow ; and in an 
 occultation of a planet or fixed star by the 
 moon, the immersion is the disappearance of 
 the star or planet behind the body of the 
 
IM 
 
 IN 
 
 moon. In like manner, the re-appearance of 
 the body is called its emersion. 
 
 Impact. Striking; 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, re- 
 tard, or alter the direction of that motion. 
 The point against which the impelling body 
 acts, is called the point of inipaci. 
 
 Impalpable Powders. Powders so finely 
 levigated that the particles of which they are 
 formed cannot be distinguished by the senses, 
 especially by that of feeling. Fine pigments 
 prepared by a flat stone and muUer are in 
 this state. 
 
 Impastation. In sculpture, the mixing 
 of different matters, bound together by means 
 of cements, and capable of resisting the action 
 of air or fire. 
 
 Impenetrability. One of the essential 
 properties of matter, whereby is shown the 
 uncontrovertible fact that no two bodies can 
 occupy the same space at precisely the same 
 moment of time. 
 
 Imperfect Number, is a number the 
 sum of whose aliquot parts is diiferent from 
 the number itself; thus, 12 is an imperfect 
 number, for the sum of its divisors, 1, 2, 3, 4, 
 and 6 is 16, which is greater than 12. 
 
 Imperial. A name sometimes given to 
 the Moorish or Saracenic dome, particularly 
 when it tapers towards the top, and is more 
 than ordinarily spread out below. The follow- 
 ing is from a Mahometan tomb, at Delhi : — 
 
 Imperial Medals. This name is applied, 
 specifically, in art, to those coins and medals 
 struck after the conclusion of the Roman 
 republican era, and until the fall of the 
 Eastern empire. 
 
 Impermeable. Impervious. That can- 
 not be penetrated by fluids ; as glass is 
 impervious or impermeable to water, oils, 
 gases, &c. Cloth and other textile fabrics, 
 when rendered water-proof by oiling, tarring, 
 or varnishing them over, are also called 
 impermeable. 
 
 Impetus. Force, momentum, or motion. 
 
 Impinge. To strike against obliquely, as 
 oi.e cloud impinges upon another, &c. 
 
 Imponderable Matter. Some of the 
 substances which surroimd and affect our 
 globe are of so subtil a nature, that they can 
 neither be confined nor submitted to the 
 usual modes of examination, and are known 
 only in their states of motion, as acting 
 upon our senses, or as producing certain 
 changes in the more gross forms of matter. 
 These have been included under the general 
 term of radiant, imponderable, or ethereal 
 matter. Such are light, heat, electricity, and 
 magnetism. 
 
 Imposing. In printing, is the arrange- 
 ment of the pages of a sheet upon the im- 
 posing stone in their proper order, so that 
 when printed, and the sheet folded, they will 
 follow each other consecutively. It also 
 implies putting the chase and fiirniture, or 
 wedges, about these pages, and blocking them 
 up ready for printing. 
 
 Impost, The upper part of a pier or pil- 
 lar which sustains an arch, or the collection 
 of mouldings under an arch, forming a cor- 
 nice of small projection, as a finishmg to the 
 pier. 
 
 Imprint. The designation of the place 
 where, by whom, and when a book is printed. 
 When a book consists of more than one 
 sheet, the imprint is put upon the first and 
 last leaf. 
 
 Impression. In painting, means each 
 coat or stratum of color laid on the canvass 
 or other surface, to prepare it to receive 
 finally the colors proper to each object in- 
 tended to be delineated. It is also some- 
 times applied to that species of painting of 
 a single color, used upon the wall or wains- 
 cot of an apartment, for the purpose of 
 decoration ; upon timber or joiner's work to 
 preserve it from humidity ; and upon the 
 works of the locksmith to keep them from 
 rust. In printing, the word impression is 
 applied to the copy of an engraving or wood 
 cut, or to the number of a book printed at 
 one time. 
 
 Improper Fraction. (See Fraction.) 
 
 Impulse. A momentary action or force, 
 such as that which arises from the sudden 
 explosion of fired gunpowder, or the mo- 
 mentum of a moving body. 
 
 Inaccessible. That which cannot be ap- 
 proached. 
 
 Incandescence. A glowing heat without 
 flame, like that of burning coke. 
 
 Inceptive. A word used by Dr. Wallis 
 to express what may be otherwise denomi- 
 nated the- principles of magnitude ; thus a 
 point is inceptive of a line, a line of a sur- 
 face, &c. 
 
 Inch, A measure of length, supposed tq 
 be equal to three grains of barley laid end to 
 end. The twelfth part of a foot. 
 
 Incidence, or Line op Incidence. In 
 mechanics and optics, is the direction in 
 
IN 
 
 IN 
 
 which one body presses or strikes upon 
 another. 
 
 Incineration. The combustion of vege- 
 table or animal substances, for the purpose 
 of obtaining their ashes or fixed residue. 
 
 Incident Ray of Light. In optics, is 
 the line of direction in which a ray is pro- 
 pagated after striking a reflecting body. 
 
 Inclination. A word frequently used by 
 mathematicians, surveyors, and artizans. 
 The mutual approach of a line and a plane, 
 or of two planes to each other, so as to con- 
 stitute an angle ; thus we speak of the in- 
 clination of the side of a hill, the inclination 
 of the sun's rays, &c. 
 
 Inclination of Meridians. IndiaUing, 
 the angle that the hour line on the globe, 
 which is perpendicular to the dial plate, 
 makes with the meridian. Inclination of the 
 axis of the earth, is the angle which it 
 makes with the plane of the ecliptic, or the 
 angle between the planes of the equator and 
 ecliptic, which is 23° 28'. Inclination of 
 the magnetic needle, the same as dip. Incli- 
 nation of a planet, is an arc or angle com- 
 prehended between the ecliptic and the plane 
 of a planet in its orbit. 
 
 Inclined Plane. A plane or surface 
 which forms an angle with the horizontal 
 plane. It is usually considered as one of the 
 mechanical powers, as the force required to 
 draw a weight up such a plane, and the laws 
 which explain the amount of friction of bo- 
 dies sliding upon it, are explained by easy 
 mathematical rules, reference being particu- 
 larly had to the length of t]ie plane, in pro- 
 portion to its height. The inclined plane is 
 available where the other mechanical powers 
 are deficient in power. There is little doubt 
 but that the amazingly-heavy stones of Stone- 
 henge, of numerous of the Egyptian build- 
 ings, pyramids, &c., were raised to their 
 present position by being rolled up long slopes 
 or inclined planes of earth. 
 
 Incliners, or Inglixino Dials, are 
 such as are drawn on planes that are not 
 perpendicular to the horizon. 
 
 Incombustible. That cannot be burned. 
 
 Incombustible Cloth. (See Amianthus.) 
 
 Incommensurable Lines, are such as 
 have no common measure. The diagonal 
 and side of a square are incommensurable, 
 being to each other as V 2 to 1, and conse- 
 
 quently whatever number of parts the side 
 of the square may be divided into, the hy- 
 pothenuse will not be made of any exact 
 number of such parts. 
 
 Incompositb Numbers. The same as 
 prime numbers. 
 
 Increment. In the higher mathematics, 
 denotes a small but finite increase of a 
 variable quantity. It is the difference be- 
 tween two successive values of the function 
 of a quantity, increasing according to a 
 determinate law. 
 
 Incrustation. An adherent covering, 
 such as one of lime, calcareous matter, 
 plaster, &c. 
 
 Indefinite. That which is without any 
 assigned limits ; thus, we say an indefinite 
 line, meaning a line of any length. Some 
 authors use the term indefinite nearly in the 
 same sense as we commonly attach to the 
 word infinite. 
 
 Indelible. Something that cannot be 
 cancelled or effaced, as indelible ink. 
 
 Indelible Ink. Ink, wliich cannot be 
 obliterated by the usual chemical agents, 
 may be made as follows : — Dissolve 25 grains 
 of copal, in powder, in 200 grains of oil of 
 lavender, by the assistance of a gentle heat, 
 and then mix 2^ grains of lamp black, 
 and half a grain of indigo. If too thick, 
 add a little more oil of lavender, or of 
 turpentine. 
 
 Indeterminate. In mathematics, quanti- 
 ties which change their values are said to be 
 indeterminate, in opposition to those whose 
 values remain fixed and invariable. 
 
 Indeterminate Analysis. A branch 
 of algebra which has for its object the in- 
 vestigation of problems, which admit of an 
 infinite number of different solutions. 
 
 Index. A table of contents, a directing 
 point. In mechanism, a light rod, similar 
 to the hand of a clock, which being attached 
 to a graduated scale or dial plate, indicates 
 such alterations as take place. Index, in 
 mathematics, the same as exponent. (See 
 Exponent.) The index or characteristic of a 
 logarithm is the integral part which precedes 
 the logarithm. The index of a globe is a 
 small hand fitted to the extremity of the 
 north pole, which turning round with it, 
 points out the time upon the hour circle. In 
 modern globes the index is omitted, the hour 
 circle being moveable around its centre. 
 
 India, or Indian Ink. A preparation 
 manufactured in China, and other parts of 
 Asia, and there used in writing. In Europe 
 this ink is chiefly employed in shadowing 
 drawings. The art of making is supposed to 
 be involved in much mystery, and numerous, 
 even contrary, receipts have been given for 
 its manufacture. Careful experiment shows 
 it to be merely composed of fine lamp black 
 and animal glue, scented with a minute 
 
IN 
 
 IN 
 
 quantity of musk. Indian ink may be as- 
 certained to be good, by presenting a smooth, 
 glossy fracture when broken, by a total ab- 
 sence of grittiness when rubbed against the 
 front teeth, and by the fractured parts uniting 
 again strongly, after having been wetted by 
 the mouth. 
 
 Indian Rubber. (See Caoutchouc.) 
 
 Indian Steel. (See Wootz,) 
 
 Indiction, or Roman Indiction, is a 
 t«rm used for a sort of epoch amongst the 
 Romans, the origin of which is not distinctly 
 known. The Roman indiction consists of a 
 cycle of 15 years, which when expired begins 
 anew, and goes on again in the same order, 
 without any dependence upon the motions 
 of the heavenly bodies. The Popes usually 
 date their acts by the year of indiction. 
 
 Indigo. A drug of a fine, dark blue co- 
 lor, prepared from the leaves and small 
 branches of a low shrub, indigenous to the 
 warmer parts of Asia and Africa. Besides 
 the extensive use of indigo in dyeing, it is 
 of the utmost value both to the oil and water- 
 color draughtsman. It has considerable 
 brilliancy of tone, mixes well, and being, as 
 is believed, more permanent than any other 
 blue color. 
 
 Indigogene. White or deoxydated in- 
 digo. 
 
 Indiootic Acid. When indigo is acted 
 upon by dilute nitric acid, a peculiar acid 
 was obtained by Chevreul, which has been 
 termed indigotic acid. It is white, has the 
 lustre of silk, has a weak, acid, and bitter 
 taste, and unites with the alkalis, and some 
 of the earths and metals, forming indigotates. 
 
 Indivisible. In geometry, are those 
 small elements or principles into which any 
 body or figure may be ultimately resolved. 
 
 Induction, is a term used by mathema- 
 ticians to denote those cases in which the 
 generality of any law, or form, is inferred 
 from observing it to be correct in numerous 
 cases. Such inductions are, however, very 
 deceptive. 
 
 Induction, Electrical. The power or in- 
 fluence which an electrified body has over a 
 body not electrified, at some distance from 
 it, the two bodies not touching each other, 
 but yet being within the sphere of mutual 
 influence. 
 
 Induction, Magnetic. The influence 
 which a magnetized body has over another 
 near it which is not magnetized. 
 
 Indurating. Hardening, either becoming 
 harder itself, or imparting hardness to others. 
 
 Ineq,uality. In astronomy, any deviation 
 of the motion of a planet or satellite from 
 its uniform mean motion. 
 
 Inertia. That tendency which every piece 
 of matter has when at rest to remain at rest ; 
 and when in motion to continue that motion. 
 
 Infinite. A term applied to quantities 
 
 which are greater than any assignable quanti- 
 ties ; also quantities that are less than any 
 assignable quantity are said to be infinitely 
 small. 
 
 Infinite Decimal. The same as circu- 
 lating decimal. (See Decimal.) 
 
 Infinitesimal, or Infinitely Small 
 Quantity, is that which is so small as to be 
 incomparable with any finite quantity what- 
 ever, or it is that which is less than any 
 assignable quantity. 
 
 Inflammable Air. Hydrogen gas. 
 
 Inflammable Air, Heavy. Carburetted 
 hydrogen. 
 
 Inflammable Air Pistol. (See Air 
 Pistol.) 
 
 Inflection, called also Diffraction 
 and Deflection, is a property in light, by 
 reason of which, when it comes within a 
 certain distance of any body, it will be either 
 bent from it, or towards it, which is a kind 
 of imperfect reflection or refraction. 
 
 Inflection, Retrogression, &c., op 
 a Curve, Point of, is a point where the 
 curve begins to bend or turn the contrary 
 way. If the curve, or rather if the two 
 curves form one continued line, the point of 
 imion is called the point of inflection^ as B 
 in A B C. When the one curve turns back 
 upon the other, it is then called the point of 
 retrogression, as B in D B E, and in FB G. 
 If the concavity of the two parts lie in the 
 same way, it is called a ramphoid, as D B E ; 
 but if they lie the contrary way, having 
 their convexities towards each other, it is 
 called a ceratoid, as F B G. 
 
 Informed Stars. Such stars as are not 
 included in any of the constellations. 
 
 Ingenhouz's Electrical Machine. 
 (See Plate Machine.) 
 
 Ingress. In astronomy, is the entrance 
 of the sun into any of the signs of the zo- 
 diac, particularly Aries. 
 
 Injection Cock. The cock which ad- 
 mits the cold water into the condenser of a 
 steam engine, to condense the steam within 
 it. 
 
 Injection Engines. Those steam en- 
 gines in which the steam is condensed by an 
 injection of cold water into the cylinder, as 
 most condensing engines at present in use. 
 
 Ink. a colored liquid for writing or 
 printing with. According to its composition, 
 color, quality, and purpose for which it is 
 intended, so ink has obtained a great diver- 
 sity of names; as Writing Ink, IndiaUf 
 
IN 
 
 IN 
 
 China, or Drawing Ink ; Gold, Silver, and 
 other Metallic Inks : Red Ink ; Sympathetic 
 Ink ; Indelible Ink ; Marking Ink ; Litho- 
 graphic Ink : Printing Ink, &c. (See the 
 words in italics for receipts of the various 
 kinds.) 
 
 Inking Roller. A roller supported on 
 a spindle with handles, used by the printer 
 to supply the types being printed from with 
 ink. It is a wooden roller, from 6 or 8, to 
 24 or more inches in length, covered with an 
 elastic composition of glue and treacle to 
 hold the ink and bear it properly to the 
 types, (fig. A.) The lithographic printer's 
 roller is a round piece of wood, 4 inches in 
 diameter, turned with a handle at each end, 
 the thicker part being covered with leather, 
 (fig. B.) 
 
 Inking Table, or Apparatus. A table 
 of a peculiar construction, used by the 
 printer, to supply his rollers with a due and 
 uniform supply of ink during the process of 
 printing. It is usually made wholly of cast 
 iron, though many printers prefer that the 
 table should be of a smooth piece of ma- 
 hogany, believing that such distributes the 
 ink more equally and more readily. A is a 
 flat and perfectly smooth table supported on 
 an iron frame, which may be screwed to the 
 floor, if convenient, though its weight is 
 generally enough to keep it steady. B is a 
 round roller with an iron handle at one end. 
 Behind and under B is a channel to be filled 
 with ink, by lifting up the flap C. D D are 
 weights to regulate the depth into which B 
 shall descend into the channel of ink. B being 
 half immersed in ink, upon turning the 
 handle of B, it offers towards the side A 
 
 a well-inked surface. The inking roller is 
 rolled against this, and therefore takes up a 
 portion of this ink ; when rolling it on the 
 table A it is distributed equally over the 
 whole surface of the roller, and is thus fit to 
 be transferred to the type. 
 
 Inlaying. The art of taking away the 
 portion of the surface of a body, and substi- 
 tuting some other more ornamental material. 
 Thus, wood may be inlaid with brass, ivory, 
 and tortoiseshell. Where one substance may 
 be easily rendered soft and pliable, inlaying 
 may be performed by pressing the harder 
 ornamental material into the substance of 
 the other. 
 
 Inlet. A terra applied to an opening into 
 a drain or culvert. 
 
 Inner Plate. The wall plate in a double 
 plated roof, which lies nearest to the centre 
 of the roof ; the side of the other wall plate, 
 called the outer plate, being laid in the inner 
 surface of the wall. 
 
 Inordinate Proportion, is where the 
 order of the terms is not regular. 
 
 Instant. An infinitely small and indi- 
 visible portion of duration, being with regard 
 to time what a point is in respect to mag- 
 nitude. 
 
 Intaglio. In sculpture and gem sculp- 
 ture, a stone in which the subject is hollowed 
 out, so that an impression from it would 
 present the appearance of a has relief. 
 
 Inscribed, or Inscribed Figure. A 
 figure is so called when placed within another 
 figure or solid, so that all its angles may 
 touch either the angles or sides of it, or both. 
 In the following cut the circle is inscribed ia 
 the triangle : — 
 
 Inserted Column. One that is let into 
 a wall. 
 
 Insulation. In electricity when a body 
 is so supported and surrounded with non- 
 conducting substances, that it cannot readily 
 part with the portion of electric fluid com- 
 municated to it, it is said to be insulated. 
 
 Insulated Column. A column that 
 stands quite clear from a wall, so that it may 
 be seen all round. 
 
 Integer. Integral, or whole number, is 
 a unit or an assemblage of units, as 4, 16, 
 784. Used in distinction to a fraction or 
 part of a number. 
 
 Integral Calculus, is the reverse of 
 the differential calculus, and corresponds 
 with the inverse method of fluxions ; the 
 finding of an integral to a given differential, 
 
IN 
 
 IN 
 
 being the same as finding the fluent of a given 
 fluxion, and is performed by the same rules. 
 
 lyxEGRANT Parts of a Body. The 
 small atoms, particles, or molecules, of 
 which any body or substance is composed. 
 Thus, if a body be mechanically divided, 
 pounded, or ground, the fine powder re- 
 sulting will be its integrant parts. 
 
 Intensity. The power or energy of any 
 quality or action of a body ; thus, we say, 
 intensity of heat or cold, intensity of a blow, 
 &c. 
 
 Intercalary Day. The extra day which 
 is inserted into the calendar every fourth 
 year, to compensate for the odd hours and 
 minutes of the solar year, which consists of 
 365 days, 5 hours, 48 minutes, and 57 seconds. 
 An intercalary day in every four years being 
 however rather too much to make up the 
 deficiency of the odd hours and minutes, 
 the intercalary day is omitted three times in 
 four centuries, which renders the calculation 
 of time extremely accurate. (See Leap Year.) 
 
 Intercepted Axis. In the conic sec- 
 tions the same as absciss. (See Hyperbola.) 
 
 Intercolumniation. The space between 
 columns. It is of five different kinds„known 
 by the terms Picnostyle, Systyle, Eustyle, 
 Diastyle, and Arceostyle, (which see.) 
 
 Interdentils. The space between dentils. 
 
 Interference of Light. A term first 
 employed by Dr. Young to express certain 
 phenomena, which result from the mutual 
 action of the rays of light on each other. 
 The phenomena may be thus explained : — 
 Suppose two minute pencils of light, ra- 
 diating from two different luminous points, 
 to fall on the same spot of a screen, or piece 
 of paper, and making a small angle with 
 each other. If the spot on which both pen- 
 cils fall is at the same distance from both 
 foci, or luminous points, the intensity of the 
 illumination is greater than would have been 
 produced by either pencil alone. Now it has 
 been foimd that there is a certain difference 
 between the lengths of the paths, at which 
 the intensity of illumination produced by 
 their concourse is the same as when the paths 
 are equal. Call this difference d, then it is 
 also found by experience that similar bright 
 bands or fringes are produced, when the dif- 
 ference between the lengths of the paths of 
 the two pencils is 2 d, or Zd, or i d ; but 
 it is very remarkable, that when the diffe- 
 lynce between the lengths of the paths is ^ d, 
 l^d, or 2^d, the two pencils instead of adding 
 to each other's intensity destroy each other, 
 and produce a black spot or fringe. The two 
 pencils thus act on each other, increasing 
 the effect in one case and diminishing it 
 in another, and it is this mutual action wliich 
 is called interference. 
 
 Interior Angle. (See Angle.) 
 
 Interior Angle of a Polygon. Tliat 
 
 which is formed internally by the meeting of 
 any of the sides of the figure. 
 
 Interjoist. The space between one joist 
 and another; this is, according to the quality 
 of the house, from 10 to 20 inches. 
 
 Intermediate Space. On railroads, is 
 the centre space or distance between each 
 line of rails or double lines of railway. This 
 varies on different lines. It is frequently 
 made the same as the distance between the 
 rails, or 4 feet 8^ mches, although it is in- 
 creased to 6 feet on the London and Birming- 
 ham and other railroads. 
 
 Intermitting. Any thing so irregular 
 in its action as to act and then apparently 
 cease to act, and so on alternately and spon- 
 taneously. 
 
 Intermitting or Intermittent Spring, 
 A spring of water which stops and flows 
 alternately. Suppose the figure below to 
 represent a hill wliich has within it a cavity, 
 A. This, supposed at first to be void of 
 water, becomes filled by the water of the 
 rains and land springs trickling through the 
 various crannies of the liill. When so filled 
 as to be at a level in A, equal to the bent 
 channel or pipe B, it will flow away by B 
 into C, B acting like a syphon and drawing 
 off all the water in a continued stream. 
 When drawn off, the flow of course ceases, 
 and A begins to fill again, and when suf- 
 ficiently full, the same action goes on a 
 second time as at first, and the spring is 
 intermittent. 
 
 Intermodillion. The space between 
 modillions. 
 
 Interpolation. A branch of the mathe- 
 matics which teaches to find any interme- 
 diate term in a series ; its place or distance 
 from the first term being given. 
 
 Intersection. The cutting of one line 
 or plane by another ; the point or line in 
 which they meet being caUed the point or 
 line of intersection. 
 
 Interstellar. A term used by some old 
 authors to denote those parts of space which 
 are beyond the regions of the solar system. 
 
 Inverse Proportion. {See Proportion.) 
 
 Interties. Horizontal pieces of timber, 
 placed between upright posts to tie or bind 
 them together. 
 
IN 
 
 Inthados. The interior curve of an arch. 
 
 Inorganic Chemistry. That part ot 
 chemistry which relates to inorganic matters, 
 including all the materials of the mineral 
 kingdom ; the account of those substances 
 arising from animal and vegetable organi- 
 zation, constituting organic chemistry. 
 
 Inuline. a starch-like substance, ex- 
 tracted from the root of the inula hellenium, 
 or elecampane. 
 
 Inverse Method of Fluxions. The 
 method of finding the fluents of given fluxional 
 expressions, the same as the integral calculus. 
 
 Inverse Method of Tangents, is the 
 method of finding a curve belonging to a 
 given tangent ; being thus distinguished from 
 the direct method, or that of finding the 
 tangent from the properties of the curve. 
 
 Invertiqn. The inverting the terms of a 
 proportion : 
 
 Thus if a : b :: c :d. 
 
 Then by inversion . . b : a :: d : c. 
 
 Inverted Arch. Such as has its con- 
 cavity below the centre or axis. It is useful 
 in every part of a wall which is lower than 
 the two adjacent parts, or where an inter- 
 ruption is made by an aperture near its base ; 
 
 and particularly where the base of a build- 
 ing contains many breaks or openings, it is 
 necessary to introduce inverted arches in the 
 foundations to distribute the weight of par- 
 ticular points, such as of the piers, AAA, 
 over the whole extent of the foundation, that 
 the pressure may be equal throughout. 
 
 Invisible Girl. A particular instrument 
 in acoustics, often made the subject of public 
 exhibition, from which a weak girlish voice 
 appears to issue, in answer to questions 
 submitted to it by speaking opposite to either 
 of the four trumpets of the instrument. 
 It is formed as follows : — 
 
 10 
 
 A square mahogany frame stands upon 
 the floor, supported upon four legs, each of 
 which legs has a strong wire at top, so lean- 
 ing and meeting over the centre of the frame 
 as to support by a string C a large brass 
 ball A, having four trumpet or funnel-shaped 
 parts attached one to each side of it, (three 
 of these are seen at B B B,) the narrower 
 ends opening into the ball, the vpider ends 
 being close to the sides or rails of the frame. 
 Opposite one of the trumpets is a small hole 
 in the frame, leading to a hoUow pipe D 
 contained in the top of the frame and down 
 one leg of it, hence along the floor to another 
 apartment, supposed at E. When a person 
 speaks at the mouth of one of the trumpets, 
 the voice enters the globe ; here it is re- 
 verberated or echoed, a part proceeding out 
 of each of the trumpets. This is too weak 
 to be heard by the by-standers, but the 
 sound from one trumpet enters the small 
 hole of the frame, this being exactly the 
 focus of it. It passes along the pipe, and is 
 distinctly heard by a person whose ear is at 
 the farthest end of the pipe, who returns an 
 answer, which is distinctly heard by any 
 person opposite to either trumpet. 
 
 Involute Curve, is that which is traced 
 out by the extremity of a thread as it is 
 folded or wrapped about another figure or 
 curve; the contrary to Evolute, (which see.) 
 Involution. In arithmetic and algebra, 
 is the raising of a given number or quantity 
 to any proposed power. This consists merely 
 in multiplying the number by itself the 
 requisite number of times ; thus, the fifth 
 power of2is2x2x2x2x 2 = 32. 
 
 In Vacuo. Empty space, or a place from 
 whence the atmospheric air is excluded ; as, 
 •for example, the exhausted receiver of the 
 air pump. 
 
 loDATES. Compounds of iodic acid. (See 
 Iodine.) 
 
 Iodic Acid. (See Iodine.) 
 Iodides. (See Iodine.) 
 Iodine. A peculiar undecompounded prin- 
 ciple, discovered in 1812 among the ashes 
 of sea weeds. Its specific gravity is about 4. 
 It becomes a violet-colored gas at a tem- 
 perature below that of boiling water. It 
 combines with the metals, forming a class of 
 compounds, called iodides: with oxygen it 
 forms the iodic acid ; with hydrogen the 
 hydriodic acid. It is a most delicate test 
 for starch in solution, tinging of a blue co» 
 lor water containing only a 400000 part of 
 starch in cold solution. 
 
 Iodo-Sulphurtc Acid. "When sulphuric 
 acid is dropped into a concentrated and hot 
 solution of iodic acid, crystals form, which 
 have been termed iodo-sulphuric acid. 
 
 loDOUs Acid. A peculiar compound of 
 iodine and oxygen. 
 
 Ionic. The third order of Grecian archi- 
 
IR 
 
 IS 
 
 tectiire, intermediate between the strong 
 Doric and the delicate Corinthian. The 
 height of the columns is 9 diameters ; the 
 capital is adorned with volutes or scrolls, 
 and the cornice with brocks or dentiles. 
 
 Ions. The elements into which any body 
 is separated when subjected to electrolysation ; 
 that is, to electro-chemical decomposition. 
 For example, when water is thus electrolysed, 
 it is resolved into its two elements, oxygen 
 and hydrogen, these therefore are called ions, 
 that which is evolved at the anode, namely, 
 oxygen being therefore an anion — while hy- 
 drogen being evolved at the cathode is called 
 a cath'ion. 
 
 Iridio - Chlorides. Particular salts 
 formed by the union of the chlorides of 
 iridium with certjiin bases; very little is 
 known respecting them. 
 
 Iridium. A metal discovered by Dr.Wol- 
 laston, associated with certain ores of pla- 
 tinum. It is grey, brittle, very infusible, 
 and of a specific gravity of about 18-6. It 
 forms several oxides and chlorides, and com- 
 bines readily with carbon. 
 
 Iris. The name of the rainbow. (See 
 Rainbow.) 
 
 Iris Ornaments. (See Barton.) 
 
 Iron. A well-known metal, of a grey co- 
 lor, possessing when polished much lustre. 
 It is malleable, ductile, and tenacious ; at 
 common temperatures, hard and unyielding ; 
 but at a red heat soft and pliable. It is very 
 difficult of fusion, is attracted by the magnet, 
 and capable of being itself rendered mag- 
 netic; a property possessed by no other 
 metal, except nickel. It has never been 
 found native: that is, in its pure metallic 
 state, except in the form of meteoric iron. 
 It is abundantly mixed with oxygen, sulphur, 
 and occasionally other substances. There 
 are known in commerce two sorts of iron, 
 cast iron and wrought iron. The former 
 being distinguished, according to its quality, 
 by the terms white and grey : of these the 
 
 first is the hardest. Iron united with carbon 
 forms plumbago and steel; united with va- 
 rious earths and oxygen, it constitutes the 
 different ochres, &c. It unites with nun)e- 
 rous of the other metals, forming valuable 
 alloys, and is soluble in most of the acids. 
 
 Iron Pyrites. Yellow sulphuret of iron, 
 composed of iron 28, and svilphur 32 pai-ts. 
 It is a very abundant ore of iron. 
 
 Iron Smelting Furnace. (See Blast 
 Furnace.) 
 
 Irrational Number. (See Surd.) 
 
 IsAGONE. An old mathematical word de- 
 noting a geometrical figure with equal angles. 
 
 Isinglass. A substance procured from 
 different kind of fish. It is almost wholly 
 pure gelatine, ninety-eight parts out of every 
 hundred of good isinglass dissolving in water. 
 It forms a nutritious jelly when boiled, and 
 is in much request by confectioners and 
 others. Brandy added to the strong watery 
 solution renders it less liable to decay, and 
 forms it into a strong glue or cement, which 
 has been much used for joining china, glass, 
 &c. It will not, however, bear hot water. 
 
 IsocHROMATic. Having the same colors : 
 said of certain crystals, when the rings of 
 polarized light shown by the one agree in 
 tint and color with the rings formed by the 
 other crystal. 
 
 Isochronal. Isochronous. Of equal 
 duration, like the vibrations of a pendulum. 
 
 Isochronal Lines, are those along 
 which a heavy body descends with a uniform 
 velocity. 
 
 Isomerism. Compounds which contain 
 the same elements in the same ratio, and yet 
 exhibit distinct chemical properties, are said 
 to be isomeric. Thus, the cyanic and ful- 
 minic acids are isomeric compounds of 
 nitrogen, oxygen, and carbon. 
 
 IsoMORPHOus. Substances which resemble 
 each other in their crystalline forms, but 
 differ in their component parts, such as 
 the phosphate of soda and the arseniate of 
 
 I soperimetrical Figures. In geometry, 
 are those which have equal perimeters or 
 bounding lines. 
 
 Isoperimetry. a branch of geometry 
 which treats of the properties of isoperi- 
 metrical figures, viz. : of surfaces contained 
 under equal perimeters ; of solids under 
 equal surfaces ; of curves of equal lengths, 
 &c. 
 
 Isothermal. Isotheral. Isochime- 
 nal. Isothermal lines, are those which 
 pass through those parts of the earth's 
 surface at which the mean annual tempera- 
 ture is the same. Isothermal zones are spaces 
 on opposite sides of the equator, having the 
 same mean temperature and bounded by 
 correspondent isothermal lines. On account 
 of the irregular form and disposition of the 
 
JA 
 
 JA 
 
 continental masses, by which the climate of 
 different places is greatly influenced, the 
 isothermal lines are not parallel to the equator, 
 except in the very low latitudes. Humboldt 
 gives the name of isotheral lines to the 
 curves passing through those places at which 
 the mean summer heat is the same ; and of 
 isochimcnal to those which pass through the 
 places at which the mean temperature of 
 winter is the same. 
 
 Ivory. The tusk or tooth of defence of 
 the male elephant. It is an intermediate 
 substance between bone and horn. The entire 
 tooth is of a brownish yellowish color on the 
 outside, internally white, solid near the 
 point, and hollow towards the root. The 
 grand consumption is for making ornamental 
 utensils, mathematical instruments, cases, 
 boxes, balls, combs, dice, and an infinity of 
 toys. Boiling it in cochineal stains it red ; 
 in verdigris, green ; in French berries, yellow ; 
 in sulphate of indigo, blue ; and in common 
 ink, black. 
 
 Ivory Black. An animal charcoal pro- 
 duced by burning ivory in close vessels ; like 
 the other forms of animal charcoal, it is very 
 effective in depriving certain substances of a 
 bad odour and color. It is a valuable pigment 
 for the artist, both ground in oil and water, 
 forming a color of a good body, which dries 
 better than lamp black, and is pleasant to 
 work. 
 
 Ivory, Etching on. Cover the surface of 
 the ivory with a ground made of the following 
 ingredients, melted together : — Pure white 
 wax, 1 oz. ; transparent tears of mastic, 
 1 oz. ; asphaltum, \ an ounce. This com- 
 pound is to be poured in luke-warm water, 
 kneaded into a ball, and wrapped in tafFety. 
 The ivory being warmed, the ball of etching 
 ground is to be rubbed on it. The figured 
 design traced on this with a needle, a ledge of 
 wax put round it, and the surface then etched 
 or eaten away with strong sulphuric acid. 
 Simple white wax will answer instead of the 
 above prepared ground, and hydrochloric 
 acid instead of the sulphuric. 
 
 Jack. In mechanics, an instrument for 
 raising heavy weights. There are several 
 kinds; one of which, the Common Hand 
 Jack, is represented, where it is shown 
 in perspective and in section. A block of 
 wood, about 2 feet 6 inches long, 10 inches 
 broad, and 6 inches wide, is perforated with 
 a square hole or mortice through it, length- 
 wise, for the reception of an iron rack B. 
 This rack is formed with a double claw or 
 horn at its upper end. A small pinion is 
 made to work in the teeth of the rack. The 
 axis of the pinion is supported in iron plates, 
 bolted on each side of the block, and one 
 end of the axis projects through the side 
 plate, with a square to receive a which or 
 handle, which upon being turned, the pinion 
 
 elevates the rack, and raises up the claw to 
 meet the work. To prevent the weight of 
 the load running the pinion back, the rack is 
 detained by a hook or link C, fastened to the 
 outside of the block. When a greater power 
 is required, it is necessary to use a second 
 wheel and pinion, as represented in the same 
 figure, where H is the handle. G the first 
 pinion working a wheel ; that a second 
 pinion, and that second pinion the rack B. 
 The lower part of the rack is often furnished 
 with a second pair of horns or claws, as at N, 
 which projects sideways from the block. 
 
 I 
 
 Jack Timbers. Those in a row of tim- 
 bers which being intercepted by some other 
 piece are shorter than the rest. Thus in a 
 hipped roof those rafters which are shorter 
 than the side rafters are called jack rafters. 
 
 Jacks, "Wooden wedges, used in coal 
 mines to split the rocks asunder after blasting. 
 
 Jacket, Steam. The cylinders of steam 
 engines, of a large size, are usually encircled 
 with other cylinders of greater diameter ; 
 steam being introduced between them, in 
 order that the inner cylinder may be kept 
 warm. This envelope or outer cylinder is 
 called a, jacket. 
 
 Jacob's Ladder. A rope ladder, with 
 wooden steps or spokes. 
 
 Jacob's Staff. The same as Cross Sta^^ 
 (which see.) 
 
 Jalapin. The supposed base of jalap. 
 
 Jambs. The sides of a door, window, fire 
 place, or other opening. 
 
 Japan Copper. Copper cast into small 
 ingots for exportation, chiefly to the East 
 Indies. The copper is dropped from the 
 moulds immediately upon becoming solid 
 into cold water, by which the ingots acquire 
 externally a deep red color. It differs, 
 however, in no respect from common copper. 
 
 Japan Ink. A superior kind of writing 
 ink, so called from its better color and 
 lustre. To make it : — Take 8 oz. of Aleppo 
 
JO 
 
 JU 
 
 galls, 4 oz. of logwood, 4 oz. of sulphate of 
 iron, 3 oz. of gum arable, 1 oz. of sulphate 
 of copper, and 1 oz. of sugar candy. To be 
 boiled in 8 pints of water till reduced to 6 
 pints. 
 
 Japanning. The art of covering wood, 
 paper, or metal, with a thick coat of a hard, 
 brilliant varnish. It originated in Japan, 
 whence articles so prepared were first brought 
 to Europe. The material, if of wood, or 
 papier machee, is first sized, then covered 
 with several coats of hard copal varnish ; 
 each of the latter coats being polished with 
 putty powder and water, previous to laying 
 on the next. Metal work and numerous other 
 articles have but one or two coats laid upon 
 them, and these are dried by the heat of a 
 stove or oven. 
 
 Jar, Electrical. (See Let/den Jar.) 
 Jargon, or Zircon. A precious stone so 
 called. 
 
 Jasper. A siliceous mineral, of various 
 colors, sometimes spotted, banded, or varie- 
 gated. It takes a fine color, and the variety 
 and richness of its colors render it useful in 
 the ornamental arts. The blood stone is a 
 variety of it. 
 
 Jelly. (See Gelatine.) 
 Jerkin Head. The end of a roof that is 
 not hipped, down to the level of the opposite 
 adjoining walls ; the gable being carried 
 higher than the level of the said walls. 
 
 Jet. a bituminous carbon ; some varie- 
 ties admit of a brilliant polish, and are used 
 for ornamental purposes. 
 
 Jet. In the casting of statues this word is 
 used to denominate the channels by which 
 the metal, in a state of fusion, is introduced 
 into the mould. 
 
 Jet, Condensing. The water used for 
 condensing the steam in ordinary steam en- 
 gines is introduced into the condenser through 
 a rose or vessel, at the end of the injection 
 pipe, which is perforated with a great number 
 of small holes, so that the water enters the 
 condenser in a shower, and thus exposes the 
 greatest possible extent of surface to the 
 steam, in order to ensure rapidity of con- 
 densation. 
 
 Jet d'Eau. (See Fountain.) 
 Jette. In the construction of bridges the 
 same as starling. 
 
 Jib. The projecting beam or arm of a crane. 
 Jib Door. A door made without dressings 
 or mouldings, so as to be flush with both 
 sides of a wainscot, and to appear as a part 
 of it ; the intention being to conceal even the 
 appearance of a door. 
 
 Joggle. A mason's term to signify the 
 jointing of one stone into another, in such a 
 manner that they cannot slip away from each 
 other, without tearing the joint or joggle 
 asunder. A separate piece of hard stone, 
 called a joggle, is sometimes introduced at 
 
 joints of stones exposed to great strains, 
 thus : — 
 
 Joggle Piece. A truss post, whose 
 shoulders and sockets receive the lower ends 
 of the struts. 
 
 Joinery. The art of framing, fitting, and 
 finishing off the wood-work in the interior 
 of houses ; also windows and doors. Joinery 
 is distinct from carpentery, which is fitting 
 up the rough timbering, used in the first con- 
 struction of the walls, roof, floors, &c. 
 
 Joint. The place where two parts of a 
 machine, frame-work, &c., are joined to- 
 gether. 
 
 Joint, Universal. (See Hooke.) 
 
 Joint Chair. The chair which secures 
 the juncture of two railway bars together. 
 
 Joists. Timbers placed parallel to and 
 equally distant from each other to support 
 the boards of a floor. 
 
 Jones's Hygrometer, consists of a 
 delicate mercurial thermometer, with its tube 
 at A B bent so as to bring its 
 cylindrical ball C parallel with 
 and at a little distance from 
 the stem. The bulb is an inch 
 long, and is terminated by a 
 flattened surface D of black 
 glass, which projects a little 
 beyond the sides of the bulb. 
 The bulb below the blackened 
 surface is covered with black 
 silk. The instrument is sup- 
 ported on the wire E F, which 
 is attached to the scale by a 
 pivot that allows the black 
 surface to be inclined to the 
 light, and the whole, with a 
 phial of ether, are inclosed in a small case 
 When used, the temperature of the air is 
 first noted, then ether is poured on the silk 
 cover of the bulb, and the condensation of 
 the dew is seen on the black extremity of 
 the bulb. 
 
 Julian iERA. The commencement of a 
 period, invented to correspond with the 
 cycles of the Julian year. It coincides with 
 the 710th year before the creation of the 
 world, according to common chronology. 
 
 Julian Calendar. The civil calendar 
 introduced at Rome by Julius Csesar, and 
 used by all the Christian countries till it was 
 reformed by Pope Gregory XIII, in 1582. 
 
KA 
 
 KA 
 
 By it the year was to consist of 3G5^ days ; 
 and the vernal equinox, the time of which 
 had previously been much disturbed, was 
 again restored to the 25th of March. 
 
 Julian Epoch. In chronology, the epoch 
 or commencement of the Julian calendar. 
 The first Julian year commenced with the 
 1st of January of the 46th year before the 
 birth of Christ, and the 708th from the 
 foundation of Rome. 
 
 Julian Period. In chronology, is a 
 period consisting of 7980 Julian years. The 
 number, 7980, is formed by the continual 
 multiplication of the three numbers, 28, 19, 
 and 15 ; that is the cycle of the sun, the 
 cycle of the moon, and the cycle of indiction. 
 The first year of the Christian era had 10 
 for its number in the cycle of the sun ; 2 in 
 the cycle of the moon; and 4 in the indiction. 
 Now, the only number, less than 7980, which 
 on being divided successively by 28, 19, and 
 15, leaves the respective remainders, 10, 2, 
 and 4, is 4714 ; hence the first year of the 
 Christian era corresponded with the year 
 4714 of the Julian period. 
 
 Jump. One of the numerous appellations 
 given by miners to a fault or dislocation of 
 different mineral strata. 
 
 JuniperBerries. The fruit of the juniper 
 tree, used to flavor gin and hollands. 
 
 Juno. One of the four asteroids or small 
 planets, situated between the orbits of Mara 
 and Jupiter. It resembles a star of the 
 eighth magnitude, is of rather a reddish 
 color and without nebulosity. Its diameter, in 
 English miles, is 1425. Its mean distance 
 from the sun is 253,000,000 of miles, and it 
 rotates on its axis in 27 hours. Its annual 
 revolution around the sun is 4 years, 128 days, 
 and it is supposed to have an atmosphere 
 more dense than any of the older planets. 
 
 Jupiter. The largest planet of our system, 
 and the fifth in order from the sun, with re- 
 gard to the old planets ; but the ninth, in- 
 cluding the four new planets, lately discovered 
 between him and Mars. Jupiter is attended 
 by four satellites or moons. This planet is 
 j remarkable for the faint appearance of belts 
 ' or stripes with which he is surrounded. (See 
 Belt.) Jupiter is brighter in appearance 
 than any other planet, except Venus. He 
 performs his siderial revolution in nearly 
 12 years, and turns on his axis in 9 hours, 
 55 minutes, and 49 seconds. His diameter 
 is 91,522 miles, and consequently he is 1331 
 times larger than the earth. His mean dis- 
 tance from the sun is nearly 490 millions of 
 miles. 
 
 Jut, or Jutty. Any projecting part of a 
 building. 
 
 A consonant letter, be- 
 longing to most ancient 
 and modern languages. 
 It has a hard sound be- 
 fore all the vowels, as in 
 Jcali, keep, kirk, koran, 
 kufic. It is silent before 
 n, as in knoll, knight. 
 In Latin, K occurs only 
 in a few words, though often used in abbre- 
 viations instead of C. In French, it is also 
 a letter of rare occurrence. 
 
 Kaleidoscope. An instrument for creat- 
 ing and exhibiting an infinite variety of beau- 
 tiful forms. This instrument, the invention 
 of Dr. Brewster, in its most convenient 
 form, consists of a tin or brass tube, 6 or 8 
 inches long, containing two reflecting sur- 
 faces, inclined to each other, at any angle 
 which is an aliquot part of 360°. Tlie re- 
 flecting surfaces may be two plates of glass, 
 blackened at the back or quicksilvered, or 
 else two metallic surfaces. The two ends 
 being now closed, except a small round hole 
 at one end to look through, and a ground 
 glass plate at the other ; when the eye looks 
 through the hole, it will perceive a circle of 
 light, divided into as many segments as the 
 number of times that the angle of the reflectors 
 
 is contained in 360". If now any objects be 
 inclosed in a transparent box, at the oppo- 
 site end of the instrument, they will be mul- 
 tiplied according to the number of reflections, 
 and the images of them arrayed in the most 
 symmetrical manner, ever varying according 
 as the position of the tube is altered. The 
 objects used are mostly bits of colored glass, 
 lace, beads, &c. 
 
 Kalium. Synonymous with potassium. 
 
 Kali. The old name of potass. 
 
 Kaolin. The Chinese name of porcelain 
 clay. The same clay found in other places, 
 as in Cornwall, is called by the same Chinese 
 name. 
 
 Kater's Azimuth Compass. A B is a 
 brass cylindrical box containing the compass, 
 of which the card D is 5 inches in diameter. 
 The needle which is perforated in its centre 
 to admit an agate cap, set in brass for the 
 purpose of suspension, is fixed to a circular 
 piece of talc, over the circumference of which 
 a narrow circular ring of card is laid ; the 
 outer margin of this card is accurately gra- 
 duated into half degrees. The breadth of 
 the cylindrical box is exactly 1 inch, and it 
 is covered, as usual, with a piece of glass. 
 A slanting piece of ivory C is fixed to one 
 side of the box, so as just to come over the 
 
KR 
 
 KE 
 
 outer edge of the graduated circle of the 
 card ; a line at right angles to the circum- 
 ference of this circle is marked upon the 
 ivory to serve as an index for reading off the 
 degrees. To the opposite side of the box, at 
 O, a sight is affixed, consisting of a brass 
 frame in the form of a parallelogram, 5 inches 
 long. To this frame is adapted a shorter 
 frame E F, 2 inches in length, which slides 
 upon it, and carries the segment of a glass 
 cylinder, ground to a ra*clius of 5 inches. By 
 means of this piece of glass, when presented 
 to the sun, the rays are collected into a 
 linear focus, the line of light being thrown 
 on the index on the piece of ivory, which 
 may be seen at the same time as the degrees 
 on the card. The sight has a hinge where 
 it is connected with the box, by means of 
 which it can be folded down upon the glass 
 cover of the box. 
 
 Kedria Teurestris. Barbadoes tar ; a 
 species of bitumen. 
 
 Keep. The principal and strongest tower 
 of a castle, intended as a last resource in 
 case of attack. The round tower of Windsor 
 Castle is of this kind. 
 
 Keeping. In painting, a term which 
 signifies the peculiar management of those 
 parts of the art, coloring and chiaro-scuro, 
 which produces the proper degree of relief 
 in objects admitted into a composition, 
 according to their relative positions in the 
 imagined scene, and the degree of importance 
 the artist attaches to them. 
 
 Kelp. A general name for the common 
 sea weeds, from which soda is procured. 
 These are Fucus bulboms, serratus, nodosus, 
 Sec, Laminaria, and others. The sea weeds 
 after they are burnt are also called kelp, being 
 then an impure carbonate of soda, mixed 
 with much ashes. 
 
 Keith's Register Thermometer. AB 
 
 is a glass tube, 14 inches long, and % inch 
 
 diameter, sealed at the top, 
 
 and below communicating 
 
 with the bent tube B D, 7 
 
 inches long and 0'4 inches in 
 
 diameter, open at the top, 
 
 where it is cemented to a 
 
 metallic plate E, which sup- 
 
 ports the ivory scale F, 6| 
 
 inches long. From A to B, 
 
 the tube is filled with highly- 
 rectified spirits of wine, and 
 
 from B to C with mercury. 
 
 At C is a conical float of 
 
 ivory or glass, resting on the 
 
 surface of the mercury, and 
 
 supporting a kneed wire H, 
 
 intended for moving two in-" 
 
 dices of black silk I and K, 
 
 that slide along a fine gold 
 
 wire G K placed to receive 
 them. It is obvious, that as 
 the heat alters the dimensions of the column 
 of spirit in A B, the mercury will rise or fall 
 in the small tube, and the float swimming on 
 the surface of the mercury will raise or de- 
 press the wire H, which vdll move the in- 
 dices I and K. The instrument is defended 
 from winds and rain by the glass case L L, 
 which by means of its metal collar fits tight 
 on E, and is only removed to adjust the 
 indices. 
 
 Kepler's Laws. In astronomy, are the 
 lavrs of the planetary motions, first disco- 
 vered and demonstrated by Kepler, and 
 which form the basis of the whole theory of 
 gravitation and physical astronomy. They 
 are three : — First, that the planets describe 
 ellipses, each of which has one of its foci in 
 the same point ; namely, the centre of the 
 sun. Second, that every planet moves so 
 that the line drawn from it to the sun, de- 
 scribes about the sun areas proportional to 
 the times. Third, that the squares of the 
 times of the revolutions of the planets are 
 as the cubes of their mean distances from 
 the sun. 
 
 Keramos. In modelling and sculpture, 
 earth which is tenacious and malleable when 
 moist, but hardens on exposure to the sun 
 or fire. It is used in the construction of 
 vases, has reliefs, cornices, &c., as well as 
 that of bricks and tiles, and indeed all works 
 the substance of which is commonly dis- 
 tinguished by the term terra cotta. 
 
 Kerf. A word used by sawyers to signify 
 a saw cut, or the channel cut by the saw 
 through wood, &c. 
 
 Kermes. An insect found in many parts 
 of Asia and the south of Europe, inhabiting 
 certain species of the oak. On account of 
 their round figure, they were for a long time 
 
 I taken for the seeds of the tree on which they 
 
KE 
 
 KI 
 
 live, whence they were called grains of 
 kertnes. They are used to dye wool of a 
 scarlet color, though the color is far inferior 
 to that produced by cochineal. 
 
 Kermes, Mineral. Hydro -sulphuret of 
 antimony. 
 
 Kersey. Kerseymere. Kersey is a 
 kind of coarse cloth, usually ribbed and 
 woven from long wool. It is manufactured 
 chiefly in the north of England. Kerseymere^ 
 on the other hand, is a thin stuff, generally 
 woven plain from the finest wools. It is 
 principally made in the western districts. 
 
 Kewley's Thermometer. (See Balance 
 Thermometer.) 
 
 Key, Cottar, or Cottrel. A wedge-shaped 
 or tapering piece of iron or wood, which is 
 driven firmly into a mortice prepared to re- 
 ceive the same, to tighten and secure the 
 several parts of any framing or contrivance 
 together, thereby forming a fastening. When 
 a key is passed through a timber beam, or 
 two or more pieces of metal placed side by 
 side, it is customary to clasp them together 
 by irons, called gibs, previous to inserting 
 the keys ; as in the cut B B B B are the gibs, 
 and A A the keys. 
 
 Keys. In naked flooring, pieces of timber 
 framed in between every two joists by mor- 
 tice and tenon, and when driven fast between 
 each pair, with their ends butting against 
 the grain of the joists, are called strutting 
 pieces. Keys in joinery are pieces of timber 
 let into the back of a board, which is made 
 of two or more separate breadths of timber, 
 for the pupose of preventing warping of the 
 whole. 
 
 Keys op a Floor. The last board, or 
 the last two boards that are laid. 
 
 Key Board. The series of levers in a 
 keyed instrument, as a piano -forte or organ, 
 upon which the fingers press to produce 
 percussion of the strings, or in the organ 
 the opening of valves. It consists of short 
 black and long white keys. 
 
 Key Screw. A lever used for turning 
 screws. 
 
 Key Stone. The central stone on the 
 crown of an arch, binding the whole toge- 
 ther. Sometimes all the stones forming the 
 circular part of the arch are called key 
 stones. 
 
 Kiln. A stove or oven intended to dry 
 various substances, such as malt and other 
 
 grain, hops, &c. It also signifies a fabric or 
 building, constructed for the purpose of 
 burning limestone, chalk, and other calcareous 
 stones into lime. A clamp of bricks burnt 
 or ready for burning is likewise called a 
 kiln. 
 
 Kinates. Combinations of the kinic acid. 
 
 King Post. The central post of a framed 
 roof, reaching from the centre of the tie 
 beam to the ridge at top. (See Roof.) 
 
 King's Yellow? A pigment of a pale 
 yellow color, the basis of which is orpiment 
 or the yellow sulphuret of arsenic. 
 
 Kink, or Kinkle. The entangling of 
 cordage from overtwisting. 
 
 Kinic Acid. Synonymous with cinchonic 
 acid ; an acid discovered in Jesuit's bark. 
 
 Kinnersley's Electrical Air Ther- 
 mometer, is an instrument to show that 
 the air is dilated when it 
 is made the passage of the 
 electrical discharge. F is 
 a glass tube, on each end 
 of which a brass cap is 
 cemented. B A is a small 
 glass tube open at both 
 ends, which passes through 
 the upper and descends 
 nearly to the under plate ; 
 a box-wood scale, which 
 is divided into inches and 
 tenths, is fitted to the 
 upper part of this tube. 
 F is a brass wire, with a 
 ball on it, which is screwed 
 to the under plate ; a simi- 
 lar wire is made to pass 
 through a collar of leathers 
 on the upper plate, and 
 may be placed at any con- 
 venient distance from the 
 lower ball. The glass tube A dips into mer- 
 cury, or a colored fluid. Whenever a spark 
 passes from the one ball to the other, the air 
 within is dilated, and the mercury or colored 
 fluid rises in the glass tube. When the spark 
 or shock has passed it immediately returns 
 to its first condition. 
 
 Kino. An extractive matter obtained from 
 the nauclea gambir, a shrub which grows in 
 Sumatra and elsewhere. It is of a reddish 
 brown color, has a bitter styptic taste, and 
 consists chiefly of tannin. Kino is often 
 called a gum, but improperly so. 
 
 Kite, Electrical. An instrument very si- 
 milar to a common kite, invented by Dr. 
 Franklin to bring lightning from the clouds, 
 and thereby to prove the identity between 
 lightning and the electric fluid. It is best 
 made of a large silk handkerchief, having 
 placed across the back of it, from corner to 
 comer, two strips of light wood. The loop 
 to which the string is attached is made in the 
 usual manner. To one end of the kite is 
 
KN 
 
 KS 
 
 fastened to the tail ; to the opposite end or 
 head are fastened two or three fine pointed 
 wires, similar to a toasting fork, which pro- 
 ject somewhat beyond the kite above, and 
 are twisted partly down the loop so as to join 
 the string, which should have a fine wire in- 
 serted in it throughout the whole length. 
 When in use, the end of the string near the 
 ground is to be attached to a dry silk cord, 
 or ribbon, and a key or other piece of metal 
 fastened at the juncture of the string and 
 silk. Should there be lightning in the air, 
 and there mostly is both in summer and 
 winter, it will be attracted by the points on 
 the top of the kite, flow down the string, 
 and finally pass out at the key to the ground. 
 
 Knee. A piece of timber or metal, cut or 
 cast so that one part shall form an angle with 
 the adjoining side. 
 
 Knight's Assay Lamp. Such is the 
 name given by Mr. Knight, Foster Lane, to 
 an extremely useful Ar- 
 gand lamp, adapted to 
 heat retorts, and for gene- 
 ral chemical purposes. 
 A is a flat short cylindri- E 
 cal vessel, for containing 
 the oil. B is a double 
 cylinder of tin, about an 
 inch in diameter. The 
 outer cylinder passes 
 through, and is soldered 
 air-tight to the oil vessel ; 
 the inner cylinder passes 
 from the holes below to 
 the centre of the flame. 
 The oil and the cotton pass between the 
 two cylinders. B is furnished with a screw 
 below, which screws on to the foot C. D is 
 a rack and pinion to regulate the height of 
 the wick. E E E are three wires, formed 
 into a frame-work to support any thing 
 which is to be heated ; these wires slide 
 up and down in sockets on the sides of 
 A and C. F is a hole for the supply of oil. 
 There is usually a copper tube placed over 
 the flame, in the manner of a lamp glass, to 
 concentrate the heat by preventing its 
 radiation sideways. 
 
 Knight's Blow-Pipe Apparatus. This 
 instrument is of French invention, and in 
 travelling of considerable utility, being com- 
 pact and ea.sy to manage. A is an air-tight 
 
 bladder of silk or India rubber. B a clamp 
 to fasten the same to a table ; B is perforated 
 from C to A, and also to the jet D, but there 
 is a valve opening downwards at the lower 
 end of the tube C. When to be used, the 
 operator is to blow into C until A is full of 
 air ; then pressing A with the knee, (sup- 
 posing him seated in front of the instrument,) 
 the air rushes out of the jet D, on to the lamp 
 flame E, which it urges to a point in which 
 the substance to be operated upon is to be 
 held. Blowing occasionally into C renews 
 the supply of air to the bladder. 
 
 Knight's Chemical Furnace, is one 
 of simple construction and of generjd appli- 
 cation. It is repre- 
 sented as follows : — A 
 is the ash-hole door. 
 B the fire-place door 
 in which muffles, cru- 
 cibles, &c. are to be 
 introduced. C a door 
 above the fire for intro- 
 ducing retorts. The 
 top also may be wholly 
 removed to insert a 
 still or sand bath. D E 
 are doors of different 
 heights, leading to the 
 fire, for the more con- 
 venient introduction of 
 different apparatus. F the hole for the in- 
 troduction of a gun barrel. G and H handles, 
 by which the whole furnace may be removed. 
 
 Knight's Method of Making Mag- 
 nets, consists in employing two magnets in 
 the same operation, applying two dissimilar 
 poles of these magnets, each to a different 
 half of the bar to be impregnated, and con- 
 fining its action to that portion of the bar. 
 
 For this purpose, the two magnets are to be 
 joined lengthwise, with their dissimilar poles 
 in contact, and laid on the bar to be mag- 
 netized, in the manner represented in the 
 figure, where A and B are the magnets, and 
 
LA 
 
 LA 
 
 C the bar to be magnetized, so that the point 
 of junction of the magnets shall be imme- 
 diately over the centre of the bar. Then 
 separating the magnets, by drawing them op- 
 posite ways, in the direction of their length 
 as far as the extremities of the small bar ; 
 they are next to be removed to a considerable 
 distance and again joined, and afterwards 
 laid a second time in the centre of the bar, 
 in the same manner as at first. This opera- 
 tion is to be repeated several times on each 
 of the sides of the bar. 
 
 Knob. Synonymous with boss. 
 
 Knotting. A process of painting, for 
 preventing the knots of the wood from ap- 
 pearing through the various coats of paint. 
 Knotting is done first with size and red lead ; 
 then with white lead, red lead, and oil. When 
 the knots are very bad, and the painting 
 intended to be of the best finish, silver leaf 
 is laid over the knots by means of gold size. 
 
 Koumiss. A vinous liquid, which the 
 Tartars make by fermenting mare's milk. 
 Something similar is prepared in Orkney 
 and Shetland. 
 
 Kreosote. (See Creosote.) 
 
 Kyanize. To prepare timber by Kyan's 
 patent solution. (See Kyan.) 
 
 Kyan's Patent Preparation. A pro- 
 cess of preserving timber from the dry rot, 
 recently invented by Mr. Kyan, consisting of 
 a solution of corrosive sublimate, in which 
 the timber is immersed, whereby the primary 
 element of fermentation is neutralized, and 
 the timber rendered indestructible. It also 
 effectually seasons the timber, occupying a 
 space of only two or three months, instead 
 of from two to six years, which is usually 
 consumed in laying it to dry by the common 
 method ; and it also protects it from the 
 ravages of insects. 
 
 The first of the 
 liquid letters, so 
 .'called with the rest, that is, 
 with m, n, and r, because they 
 blend or produce a flowing sound 
 with other consonants, and be- 
 cause they can 
 ^^^be sounded for 
 a length of time. 
 L is a letter of almost all languages, ancient 
 and modern. As a numeral L reckons for 
 50. In abbreviations it stands for Lucius, 
 L.L.D., Learned Doctor of Laws, &c. &c. 
 Labuanum, or Ladanum. The resin of 
 the cistus creticus. 
 
 Label. A moulding projecting over a 
 window, door, or other aperture, withinside 
 the building. The word drip -stone applying 
 outside the building. Label is also a Gothic 
 architectural ornament,representedasfollows: 
 
 Laboratory. An apartment or series of 
 apartments, fitted up with the various utensils 
 used in the study and pursuit of chemistry. 
 
 Laboured. Any work which bears the 
 appearance of constraint and hardness of 
 style ; opposed to free, graceful, or flowing. 
 
 Labyrinth. A large and intricate edifice \ 
 or garden, cut into various passages or mean- ! 
 ders, running into each other, so as to render , 
 it difficult to get out. The followinc is the ! 
 
 ground plan of a celebrated one at Ver- 
 sailles : — 
 
 Labyrinth. In metallurgy, the name of 
 a series of wooden troughs, communicating 
 with each other. The ore of a metal being- 
 pounded is mixed with water, and poured into 
 the upper trough. Here the grosser parti- 
 cles subside, when the still thick liquid flows 
 to the next trough, where more of the ore is 
 left behind ; until at length all the troughs 
 are filled, each with particles finer than those 
 in the preceding trough. 
 
 Lac, a kind of resin, used in making 
 sealing-wax, lacquers, &c. There are three 
 kinds, called shell lac, seed lac, and stick 
 lac. 
 
 Laccic Acid. A peculiar acid, separated 
 by Dr. John from stick lac. It is yellow, 
 
LA 
 
 LA 
 
 crystallizable, and unites with the alkalis, 
 lime, nriccury, and lead. 
 
 Laccixe. a peculiar substance, said to 
 form the base or distinguishing property in 
 stick lac. 
 
 Lac Dye. Lac Lake. Two preparations 
 of stick lac, imported in small cubic cakes 
 from the East Indies, and extensively used 
 in the production of scarlet dye. 
 
 Lace. An ornamental transparent fabric 
 of linen or cotton thread, formerly made by 
 hand, when it was called pilloiv lace ; but of 
 late years produced by machinery, and ge- 
 nerally termed bobbin net. 
 
 Lacmus. (See Litmus.) 
 
 liAcauER. A yellow varnish, consisting 
 of a solution of shell lac in spirits of wine, 
 and colored by gamboge, saffron, annotto, or 
 other similar color. Lacquers are chiefly 
 used for varnishing brass and some other 
 metals, in order to give them a golden color 
 and preserve their lustre. 
 
 Lactates. Compounds of the lactic acid. 
 
 Lactic Acid. The acid of sour milk. 
 
 Lactometer, or Galactometer. An 
 instrument for ascertaining the quality of 
 milk, by the quantity of cream it casts up. 
 One kind of lactometer consists of a graduated 
 glass tube ; this is filled to a certain height 
 with milk, and set aside for some hours. 
 Being then examined, the quantity of cream 
 which rises is easily seen by the marks upon 
 the tube. When the milk of several cows 
 is to be compared, a number of similar tubes 
 is employed, in which case they are set in a 
 stand, like that of a test tube stand, as fol- 
 lows. The tubes are about half an inch in 
 "■ ■ meter. 
 
 Lactucic Acid. A peculiar acid, dis- 
 covered in the juice of a particular kind of 
 lettuce, called the lactuca virosa. 
 
 Lacunar. A ceiling or soffit, ornamented 
 with pannels. 
 
 Lagarouse's Lever, is a contrivance 
 by which a reciprocating circular motion 
 may be converted into a continued rectilinear 
 one. The centre channel represents a fixed 
 shaft, in which a centre is placed, upon 
 which the lever A B works. To A B are 
 attached two hooks, and as the lever moves 
 r.p and down on its centre, the hooks take 
 
 hold alternately of one of the teeth of the 
 rack, either on the one side or the other, 
 moving at the same time the rack steadily 
 up^^ards. 
 
 Lake. A general term for many yellowr 
 and red vegetable colors, when made of alu- 
 minous earth, and the coloring matter of a 
 particular plant or the insect ; thus we have 
 carmine, scarlet, madder, yellotv, cuchineat, 
 lac lakes, i^'c. 
 
 Lamina. A thin coat or plate of metal, 
 or other hard substance. 
 
 Laminable. Said of a metal which may 
 be flattened out into a thin sheet, by being 
 passed between steel rollers. 
 
 Lamp, Safety. (See Davy.) 
 
 Lamp Black. Finely divided charcoal, 
 or soot, obtained by the imperfect combus- 
 tion of various oily or resinous substances- 
 It may be obtained in small quantities by 
 holding any cold substance close over a com- 
 mon lamp. The manufacture on a large 
 scale is conducted in chambers lined with old 
 sacking, upon which the soot from a large 
 smoky fire is collected. It is used as the 
 basis of black paint, and for other purposes. 
 
 Lampic Acid. A term given by M. Daniell 
 to the acid produced by the slow combustion 
 of the vapor of alcohol and ether, in a lamp 
 without flame. It is supposed to be acetic 
 acid, modified by a peculiar hydro-carbon. 
 
 Lancet Window. A long and narrow 
 window, pointed like the blade of a lancet. 
 
LA 
 
 LA 
 
 Land Compass. (See Compass.) 
 
 Landing. In building, the first part of a 
 floor at the head of a stair. 
 
 Land-Locked. a term applied to a har- 
 bour or piece of water, which is so environed 
 by laud on all sides as to exclude the pros- 
 pect of the sea. unless over some intervening 
 land. 
 
 Land-Mark. Any thing by which the 
 boundary of a property is defined. In naval 
 language, it is applied to any conspicuous 
 objexjt, which serves as a guide on entering 
 a harbour, or avoiding a danger. 
 
 Landscape. The view or prospect of a 
 country, extended as far as the eye can I'each. 
 
 Landscape Gardening. The art of 
 laying out gardens, so as to produce the 
 effect of natural landscape. 
 
 Land -Slip. A portion of land on a coast, 
 the verge of a hollow, the side of a moun- 
 tain, &c., which has slipped out of its place, 
 in consequence of an earthquake, the effects 
 of rains, frosts, &c. In the south coast of 
 Isle of Wight, land-slips are very common, 
 and some of them consist of many acres ; 
 which, owing to the rains, joined with the 
 undermining action of the sea, have slidden 
 down, almost without disturbing the crops, 
 so as to look like a field upon the beach. 
 
 Land-Springs are sources of water, 
 which only come into operation after heavy 
 rains. The cause of them is, that at a short 
 distance beneath the surface of the ground, 
 a retentive stratum of ground, (clay, or marl, 
 for example,) prevents the rain from pene- 
 trating more deeply into the earth, conse- 
 quently it is kept near the surface, gushing 
 out as soon as it finds a channel, and being 
 in but a comparatively small quantity is soon 
 exhausted. 
 
 Lane's Discharging Electrometer, 
 or the Medical Electrometer, being used 
 chiefly for medical purposes. This useful 
 instrument is represented and described as 
 follows : — 
 
 A is supposed to be a cross section of tie 
 prime conductor of an electrical machine. 
 B is a brass cap, forming the end of the elec- 
 trometer ; it is made with a wire beneath to 
 fit the hole of the conductor. C is a bent 
 glass tube. D a brass ball at the end of it. 
 E is a wire with a ball at each end of it, 
 which wire is moveable backwards and for- 
 wards. When a shock is to be taken, the 
 ball E is placed at a certain distance from the 
 
 surface of A. A is connected with the inside 
 of the Leyden jar or battery which commu- 
 nicates the shock, and the chain is connected 
 with the outside of the jar. When the jar 
 is charged to such a degree of intensity as 
 to acquire force enough to strike across from 
 A to E, the discharge will spontaneously 
 take place. 
 
 Lantanium. a metallic substance, dis- 
 covered in a mineral called cerite, being 
 blended with the oxyde of cerium. The oxyde 
 of latanium is of a brick red color. 
 
 Lantern. A small turret or cupola, with 
 apertures, raised upon the summit of a build- 
 ing for the purpose of giving light to the in- 
 terior. The small round or octagonal termi- 
 nation to a dome or tower is also so called, as 
 in St. Paul's Cathedral. The roof of West- 
 minster Hall has a lantern on the ridge of it. 
 
 Lantern. In mechanics. {See Trundle.) 
 
 Lantern, Magic. {See Magic Lantern.) 
 
 Lanthorn. (See Lantern.) 
 
 Lapidary. A person who cuts and po- 
 lishes precious stones, forming them into 
 brooches, ear-rings, and other ornamental 
 articles. 
 
 Lapidary Style of Architecture, 
 denotes the style proper for monumental and 
 other inscriptions. 
 
 Lapidary's Wheel. A machine used by 
 lapidaries to grind and polish precious stones 
 and gems. The wheel is of various forms, 
 the most simple is represented below : — 
 
 A is a wheel, made of wood, iron, lead, or 
 other material, according to the hardness of 
 the stone to be ground. This may be taken 
 off its spindle, and another wheel, or lap as 
 it is called, substituted. The upright spmdie 
 C D, which bears the lap A, also bears be- 
 neath the table the pulley B. By a cord 
 which is attached to this, a connection is 
 made with the larger pulley F, the spindle 
 of which is terminated above by the handle G ; 
 so that upon being turned, motion is com- 
 municated by the pulleys and cord to the 
 lap A, and the workman holding a stone or 
 other body to A, at the same time that he 
 
lA 
 
 turns the nandle with the other hand, will, 
 of course, occasion a friction between the lap 
 and stone. It only remains, therefore, to 
 furnish A with some sharp-cutting substance, 
 such as emery, diamond dust, &c., and the 
 stone will be ground away, while a fine pow- 
 der, such as putty powder, and with another 
 lap, will polish it. 
 
 Lapidification. The art of cutting and 
 polishing stones, as practised by the lapidary. 
 Lapis Causticus. An old name for 
 caustic potass. 
 
 Lapis Electricus. A name given by 
 Linnaeus to the tourmalin, that stone exhi- 
 biting an electrical attraction when heated. 
 
 Lapis Infernalis. An old name for 
 lunar caustic, or fused nitrate of silver. 
 
 Lapis Lazuli. An argillaceous stone of 
 a beautiful blue color, which when pounded 
 and ground forms for the water color painter 
 the finest blue pigment hitherto discovered, 
 commonly called and known as ultramarine. 
 This stone is discovered in various countries ; I 
 those of Asia and Africa, however, greatly 
 surpass, both in beauty and real value, the 
 Bohemian and German sorts. 
 
 Larch. A kind of fir timber, useful for 
 railing, posts, and other similar purposes, 
 especially as worms will not destroy it, and 
 the weather exerts but little influence upon it. 
 Numerous machines are framed of larch, and 
 the masts of ships often made of it. 
 
 Lateral Equation. A term used by 
 some old authors for what is now more com- 
 monly called a simple equation. 
 
 Lateral Explosion. The name given 
 to certain effects of the electrical fluid when 
 discharged in considerable quantity through 
 a small substance. For example, if a large 
 jar or battery be discharged by a metallic 
 wire held in the hand, without the protection 
 of glass or other non-conductor, it often 
 happens that a slight shock is felt. This is 
 called the lateral explosion. 
 
 Lath. A slip of wood used to support 
 plastering, tiling, and slating. 
 
 Lath Floated and Set Fair. In build- 
 ing, three-coated plasterer's work, in which 
 the first is called pricking up, the second 
 floating, and the third ^nwAm^. 
 
 Lath Laid and Set. In building, two- 
 coated plasterer's work. The first coat is 
 called laying, the s^condi finishing . 
 
 Lathe. A machine used by various arti- 
 zans, particularly by the turner, for the pur- 
 pose of cutting the substance fastened to it 
 of a circular, or more rarely of an oval form. 
 Lathes are of two general descriptions ; in 
 one of which the tool revolves, such as the 
 brush-maker's lathe, and the seal engraver's 
 lathe, (see Seal Engraver.) In the other 
 kind, the material revolves, and the tool is 
 held towards it, such as the common lathe, 
 (about to be described,) the potter's wheel, 
 
 LA 
 
 &c. (See Patterns Wheel.) Common lathes 
 take also various names, according to the 
 manner of putting them in motion, as the 
 pole lathe. (See Pole ;) the foot lathe, &c. 
 The following is called the triangular bar 
 foot lathe ; the motion of it being occasioned 
 by the foot and the bed being formed of a 
 triangular bar of iron. It may be thus 
 represented : — 
 
 A is the fly wheel, which has mostly three 
 or four grooves around its circumference. 
 This is put in motion by its being connected 
 by means of the cranked spindle which passes 
 through its centre, and by the hook C with 
 the treadle D, which is worked by the foot ; 
 the back part of the treadle being on hinges 
 to allow it to rise and fall. A cord passes 
 under A on to the top of the mandrel B ; 
 (this is accidentally omitted in the figure,) 
 giving that a circular motion within a shoulder 
 at E, and a screw point at F. Whatever is 
 to be turned is fixed upon the projecting part 
 of the mandrel at E. G is called the poppit 
 head or hack poppit, or puppet, which slides 
 backwards and forwards, and holds by the 
 point near G, the end of the work to be 
 turned. H is called a rest ; it also slides 
 along the triangular bar or bed, and may be 
 adjusted to any height or distance required, 
 by means of a screw beneath, and one at the 
 side, shown by a black dot. When the treadle 
 is put in motion, it turns the crank, that the 
 fly wheel, then by the cord the mandrel, and 
 with it whatever may be attached to it. The 
 tool resting steadily upon H, cuts away all 
 the material which comes against its edge ; 
 and as the material turns round a centre, 
 the tool will, of course, cut away all parts 
 which are farther from the centre than its 
 point, consequently it cuts the material into 
 a circuleir form. 
 
LA 
 
 LE 
 
 IjAthe, Appendages to. Such implements 
 as are used with, and are indispensable to a 
 lathe, though forming really no part of it ; 
 such are chucks, boring collar, rests Src. 
 (See these terms.) 
 
 Latitude. In geography and navigation, 
 is the distance of a place from the equator, 
 reckoned on an arc of the meridian, inter- 
 sected between its zenith and the equator. 
 North latitude is north of the equator. South 
 latitude south of the equator. In astronomy, 
 as of a star or planet, its latitude is its distance 
 from the ecliptic reckoned towards the poles 
 of the ecliptic, either north or south. 
 
 Latitude, Difference of, is the nearest 
 distance between the parallels of latitude of 
 two places. To find this difference, when 
 the latitudes are both north or both south, 
 subtract them from each other ; when one is 
 north and the other south, add them together. 
 
 Latitude, Geocentric, of a Planet, is its 
 latitude as seen from the earth. This, though 
 the planet be in the same point of its orbit, 
 is not always the same, but alters according 
 to the position of the earth in respect to the 
 planet. 
 
 Latitude, Heliocentric, of a Planet, its 
 latitude or distance from the ecliptic, such 
 as it would appear from the sun. This, 
 when the planet comes to its orbit, is always 
 the same. 
 
 Latitude, Middle. The middle point 
 between two latitudes or places. A parti- 
 cular method of directing a ship's course, 
 and calculating her way, is called middle 
 latitude sailing. 
 
 Latitude of the Moon, is her ascending 
 or descending towards or away from one of 
 her nodes, and is according to circumstances, 
 called north ascending, north descending, 
 south ascending, and south descending. 
 
 Latitude, Parallels of. Circles of the 
 sphere parallel with each other and with the 
 equator, upon which the latitude of places is 
 seen. 
 
 Latten. a fine kind of brass, used in 
 the middle ages for crosses, candlesticks, &c. 
 The exact proportion of ingredients is not 
 known. Latten now signifies the thin plates 
 of iron covered with tin, of which domestic 
 articles, such as saucepans, &c., are made, 
 and which usually go by the name of tin- 
 ware. 
 
 Lattice. Windows formed of leaden 
 frames, as common, not merely in our days, 
 for cottages, attics, &c., but used almost 
 exclusively in the Gothic buildings of the 
 middle ages. They are properly called lattice 
 windows only when the panes of glass are 
 diamond-shaped, and placed with one of the 
 points upwards ; otherwise they are merely 
 called lead-lights. 
 
 Lava. The substances which flow in a 
 melted state from a volcano. 
 
 Laurine. a crystallisable substance 
 formed in laurel berries. 
 
 Lawn. A fine variety of cambric, formerly 
 manufactured almost exclusively in Flanders ; 
 now chiefly made in Scotland, and the north 
 of Ireland. 
 
 Lay Figure, or Mannikin. A figure of 
 wood, the joints of which are made to play 
 with as much ease as possible, for the purpose 
 of affording the artist opportunities to judge 
 of the different effects of various positions 
 of the human body. 
 
 Layer. (See Course.) 
 
 Laying. The first coat of plaster put 
 upon a partition, the surface whereof is 
 roughened by a birch broom, that it may 
 better hold the coat of fine plaster afterwards 
 to be put upon it. 
 
 Lead. A whitish blue metal, soft and 
 flexible, not very tenacious, and consequently 
 incapable of being drawn into wire, though 
 it is easily extended into thin plates under 
 the hammer. Its specific gravity is ir35. 
 It melts at 612°. In a strong heat it boils 
 and emits fumes, during which time, if 
 exposed to the air, its oxydation proceeds 
 with considerable rapidity. Most of the 
 acids attack lead, (not the sulphuric, unless 
 it be concentrated and boiling.) It also 
 unites with most of the metals, and with 
 sulphur. 
 
 Lead, for Sounding. A mass of lead of 
 about 11 pounds weight, which is attached 
 to a cord of about 20 fathoms (40 yards) 
 in length, used for ascertaining the depth of 
 the sea or a river. The line is marked at 
 5, 7, 10, 13, 17, and 20 fathoms; the 
 numbers between are called deeps. Thus, 
 by the mark 7, by the deep 9, indicates 
 7 and 9 fathoms respectively. 
 
 Lead, Black. (See Plumbago.) 
 
 Lead, Sugar of. The acetate of lead. 
 
 Leads. A printer's term for the thin 
 pieces of type metal used to space out 
 the lines in a page of type, when such is 
 
 Leaders. The principal wheels in any 
 kind of machinery are so called. 
 
 Leaf Bridge. A bridge similar to a draw- 
 bridge ; the only difference being that in a 
 draw-bridge one platform is let down, and 
 in a leaf bridge two platforms, one on each 
 side of the chasm to be passed. 
 
 Lean-face Letter. A letter is so called 
 when of slender proportions in comjiarisou 
 to the width of it. 
 
 Lean To. A small building which has a 
 shed roof, and is attached to a larger building. 
 
 Leap Year. A year containing 360 days. 
 It occurs every four years, omitting the years 
 that indicate three out of every four centuries. 
 To ascertain leap year, divide the number of 
 the year by four, if nothing remain it is leap 
 year, otherwise not : thus, 1600 was leap 
 
LE 
 
 LE 
 
 year, but 1700 and 1800 were not, nor will 
 1900 ; but 2000 will be leap year. 
 
 Leat. An artificial channel for conducting 
 water for the working of water wheels and 
 other purposes. 
 
 Leather. The skins of animals prepared 
 with lime water, and afterwards with astringent 
 substances, which penetrating the substance 
 of the skin, render it tougher, less porous, 
 and more lasting. 
 
 Leaven. A piece of sour dough used to 
 ferment and render light a much greater 
 quantity of dough or paste. 
 
 Leaves. In architecture, ornaments of 
 carved work, forming part of the more orna- 
 mental capitals ; also introduced into festoons, 
 scrolls, wreaths, &c. In the arts, leaf indi- 
 cates any thing fiat and thin, as leaves of 
 metal, the leaves of a pinion, &c. 
 
 the point A being reckoned double as the 
 curve there crosses itself. 
 
 Ledgers. In building, horizontal poles, 
 used in scaffolding, lying parallel to the 
 wall opposite to which the scaffold is erected. 
 
 Legs of a Right-angled Triangle, 
 are the base and perpendicular, or the two 
 shorter sides. 
 
 Lkgumine. a modification of gluten 
 found in peas and beans. 
 
 Lemna. In mathematics, a previous 
 proposition laid down in order to clear the 
 way for some following demonstration, and 
 prefixed either to theorems in order to render 
 their demonstration less perplexed and intri- 
 cate, or to problems to make their resolution 
 more easy and short. 
 
 Lemniscate. The name of a particular 
 mathematical curve, formed much like the 
 figure 8. It has the peculiar property, that 
 a straight line drawn through it lengthwise 
 will divide it into four parts, as D E J K ; 
 or if drawn across it transversely, into two 
 parts, as by the line F G. The line BAG, 
 and the line HI, are considered to cut the 
 curve in the same manner as the other lines, 
 
 G 
 
 Lemons, Acid of. The citric acid. 
 
 Lemons, Salt of. Tlie binoxalate of potash. 
 
 Length. The greatest extension of a body. 
 
 Lens. A piece of glass or other trans- 
 parent substance having its two surfaces so 
 formed that the rays of light in passing 
 through it have their direction changed, and 
 made to converge or diverge from their 
 original parallelism, or to become parallel 
 after converging or diverging. Lenses receive 
 particular denominations, according to their 
 form, as convex, that which is thickest in 
 the middle ; if one side only be rounding, 
 it is called piano - convex, as B ; if both 
 sides, it is called convexo convex, or now 
 more frequently doubly convex, C. If the 
 lens be thinnest in the middle, it is concave, 
 either plano-concave, D, or doubly concave, 
 E. If one side be concave, and the other 
 convex, it is a meniscus lens, F ; and if a 
 plano-convex lens be cut on its convex side 
 into a number of faces or facets, it is called 
 from the effect which it produces, a multi" 
 plying glass or lens. Some authors include 
 among lenses, the flat glass, calling it a 
 piano lens, as A, and also the triangular 
 prism, H, but these are not truly lenses. 
 A globe of glass may be considered as a 
 doubly convex lens. 
 
 n 
 
 B 
 
 (\ A 
 
 J W V 
 
 The axis of a lens is the line which passes 
 perpendicularly through the centre of it, as 
 I, I, I. Lenses are either blown or ground. 
 Blown lenses are small globules of glass, 
 melted in the flame of a lamp by a blow-pipe. 
 Ground lenses are such as are ground of the 
 required form, by means of a lathe, or other 
 machinery. Polyzonal lenses are large, and 
 made up of several pieces. 
 
LE 
 
 LE 
 
 Levity. Lightness, or the quality of cer- 
 tain bodies which gives them a power of as- 
 cent, either upwards in the atmosphere, to 
 the surface of water from a depth beneath, 
 &c. &c., being thus opposed to gravity, by 
 which bodies have always a tendency to 
 descend. Levity is therefore nothing distinct 
 in itself, but only an absence of weight. 
 
 Leslie's iETHRioscoPE. (See JEthrios- 
 cope.) 
 
 Leslie's Differential Thermome- 
 ter. (See Air and Differential.) 
 
 Leslie's Photometer. (See Photo- 
 meter.) 
 
 Leslie'sThermometric Hygrometer. 
 A thermometric hygrometer is an instrument 
 formed from a differential thermometer, by 
 covering one of its balls with tissue paper or 
 black silk. Being kept moist with water, 
 the evaporation produces cold, and that in a 
 degree exactly accordant with the state of 
 dryness in the atmosphere. A B is the dif- 
 ferential thermometer ; the ball B being 
 naked, that at A covered. C is a vessel of 
 water, which has a few filaments of cotton 
 that reach from the liquor in it to the covered 
 ball. This acts as a syphon, and keeps the 
 ball moist. The graduated scale shows the 
 degree of evapor-^ion. When this hygro- 
 meter stands at 15°, the air feels damp, from 
 30 to 40° we reckon it dry, from 50 to 60 
 very dry, and from 70° upwards we should 
 call it intensely dry. 
 
 Leupolp's Steam Engine, sometimes 
 called the high pressure lever engine, is 
 described as follows : — The boiler C com- 
 municates by a cock of a peculiar construc- 
 tion, (see Four-wmj Cock,) D, with the 
 bottom of two cylinders, having pistons A, B, 
 moving in them. These pistons are attached 
 by their rods to two levers, the other ends of 
 which work the pump rods F G. I is the 
 eduction pipe, to convey away the water 
 raised. H is the fire place. 
 
 In the situation of the engine shown, the 
 steam from the boiler flows through the pas- 
 sage into one of the cylinders, and presses 
 the piston upwards. This depresses the pump 
 
 rod K, fixed to the other end of the lever, 
 which forces the water up the pipe \. When 
 
 the steam has raised the piston A to nearly 
 the top of the cylinder, the cock is turned, 
 and the passage between this cylinder and the 
 boiler is closed, and a communication is 
 opened from the inside of the cylinder into 
 the atmosphere. At the same time a passage 
 is opened for the steam beneath the piston B 
 of the other cylinder, which then, in like 
 manner as the former, discharges its proper 
 quantity of water. Thus the action is con- 
 tinued alternately, owing to the cock altering 
 the channels of communication from one 
 cylinder to the other. 
 
 Level. A mathematical instrument, used 
 for drawing a line parallel to the horizon, 
 and continuing it out at pleasure, by 
 this means finding the true level, or the 
 difference of ascent and descent between any 
 two places ; for conveying water, levelling 
 the surface of floors, and for various other 
 purposes, connected with surveying, hydrau- 
 lics, architecture, &c. There are numerous 
 forms given to the instrument ; one of the 
 commonest of which is the spirit or air level. 
 This consists of a tube of glass, filled with 
 spirits of wine, except space enough for a 
 single bubble of air. When this tube is 
 placed upon a perfectly level surface, the air 
 bubble will rest exactly in the middle of the 
 upper surface of the tube. A figure of this 
 instrument is seen in the middle of the fol- 
 lowing cut. The water level is on a diffe- 
 rent construction. The most simple form is 
 that of a long trough, open at the top, in 
 which water being poured, it is seen if the 
 water continues of a true level, by a line 
 made along the side of the box, or else by 
 its running over at one end ; but a better 
 construction is that of a tube, open and bent 
 
LE 
 
 I,E 
 
 at both ends. This is nearly filled with 
 water or mercury, and two floating sights 
 are placed one at each end ; looking through 
 these, if the wire which is placed across one 
 of the sights, upon looking at it from a little 
 distance, exactly coincides with the wire 
 across the other sight, and also with any dis- 
 tant object whose level is to be ascertained, 
 it is known directly that the three are on 
 the same level. 
 
 The level used by the carpenter and mason 
 is well known, consisting of a straight bar 
 of wood as a foot, with an upright bar in the 
 centre of it, a plum-bob and line being sus- 
 pended in the centre of the upright piece, 
 as A and B. The artillery foot level has a 
 line and plu.nimet, or bob, with two legs, 
 and a scale of 90" between them. When 
 the bob hangs in the middle of the scale, the 
 feet rest on a level surface, otherwise one foot 
 must be raised accordingly. So on uneven 
 ground, the degree cut by the bob line 
 shows the decree of acclivity or descent as C. 
 Level is also a name given sometimes to a 
 canal, or to a low, flat tract of country. 
 Likewise in mining, a seam or stratum of 
 coals, or other mineral, running horizontally 
 is ia level. 
 
 Level Crossing, is such a part of a rail- 
 road as crosses a road upon the same plane 
 or level as the road itself. 
 
 Levelling. The art of finding a true 
 horizontal line, or of rendering a surface 
 parallel to the horizon. 
 
 Levelling Staff. A graduated rod or 
 staff, which is fixed up at a certain spot, as a 
 criterion whereby to estimate the level of a 
 neighbouring spot of ground. 
 
 Lever. In mechanics, an inflexible straight 
 bar, supported in a single point on a fulcrum 
 or prop, and used for the raising of weights. 
 In levers, three things are to be considered ; 
 the iveight to be raised, the fulcrum or sup- 
 port, and the power employed. According 
 to the relative position of these, levers are 
 said to be of three kinds. A lever of the 
 first kind has the fulci-um between the weight 
 and the power, as a poker when in use, and 
 also in the followiug figure, No. 1. Double 
 
 levers of this kind arc seen in scissars, pin- 
 cers, snuffers, &c. When the weight is 
 between the fulcrum and the power, it is 
 called a lever of the second kind, as the oars 
 and rudder of a boat, the water being the 
 fulcrum or resistance, the rower the power, 
 and the boat to be moved the weight. (See 
 fig. 2.) A lever of the third kind has the 
 power between the fulcrum and the weight, 
 such an one is a ladder lifted by the middle 
 to raise it against a wall, pushing open a gate, 
 the fire tongs, &c. Levers may be either 
 bent or straight. 
 
 Levigation. Tlie mechanical process of 
 grinding the parts of bodies to a fine paste. 
 
 Lewis. An instrument used by masons 
 for lifting stones of great weight, when they 
 are to be fixed in a building. The cut shows 
 a longitudinal section of one. A hole is first 
 cut in the stone, which hole is larger beneath 
 than at the surface. In this are inserted 
 two tapering pieces of iron, A and B. A 
 third iron C is driven between them ; a sta- 
 ple to lift by is put over these three irons, 
 and the whole fastened together by the bolt 
 D E. It is evident that as the irons fit the 
 hole, the stone if sound will readily be lifted 
 up. 
 
 Ley. (See Lye.) 
 
 Leyden Phial, Leyden Jar, or Elec- 
 trical Jar, is a glass phial or jar, coated 
 both within and without to a 
 certain height with tinfoil or 
 some other conducting sub- 
 stance, and having a chain, 
 wire, and ball, connected with 
 the inner surface, which may 
 be charged with, and em- 
 ployed as a recipient for the 
 electric fluid. This fluid 
 
 , being drawn off again sud- 
 denly, occasions an electrical 
 shock. Glass which is flat, 
 
 j or of any other shape, so 
 coated and used, has also 
 
 ' received the same denomi- 
 
 ; nation. There are various 
 modifications of this instru- 
 ment. (See Magic Picture, Harris^ s Diamond 
 
 \ Jar, 4-c.) 
 
 I. L 
 
LI 
 
 LI 
 
 Leyden Jar with Moveable Coatings. 
 The name of a particular modification of the 
 common Leyden jar ; the difference being 
 that in the present instance the coatings are 
 formed of tin, so that the glass when charged 
 may be taken out of its coatings, and placed 
 in others ; when the shock or discharge 
 being made, it will be proved that the electric 
 fluid, disturbed by charging the phial, ad- 
 heres to the glass, and not to the metallic 
 coats. In the cut, A represents the jar, 
 complete ; B shows the outer cover ; C tlie 
 inner covei* and ball attached. 
 
 LiBAVius, Fuming Liquor of. Deuto- 
 chloride of tin. 
 
 LiBRATiOTsr. A certain motion of either 
 the earth or moon. The libration of the 
 moon is more particularly an apparent 
 libratory motion of that body about her own 
 axis, whereby we see a little more than one- 
 half of the lunar disc ; or rather it is in 
 consequence of our seeing more than one- 
 half of it, that the moon appears to have 
 such a motion. The libration of the earth 
 is a term applied to that motion by which the 
 earth's axis is kept at one time parallel to 
 what it is at another, whereby the poles 
 always point to the same spot in the heavens. 
 
 LiCHENic Acid. An acid which has been 
 discovered in certain species of lichens. 
 
 LiCHENiN. A starch-like substance ex- 
 tracted from the Iceland moss. 
 
 Life -Boat. A large boat, made particu- 
 larly buoyant by hollow, empty tubes of 
 metal, or small casks being attached to it, 
 which prevents its sinking, even when loaded 
 with a crew, and full of water ; some life- 
 boats receive their buoyancy from being 
 cased with cork. The intention of life-boats 
 is to save the crew of stranded vessels. 
 
 Life-Buoys. a light substance or con- 
 trivance intended to support a person in the 
 water and prevent him from sinking. The 
 corks used by swimmers are of this de- 
 scription : — Bags or belts of air are perhaps 
 among the most simple and effectual life- 
 buoys. They are, when used, if small, to be 
 fastened round the neck of the person by 
 >neans of the strings attached to them, and 
 .vhile the bag is void of air, or in a collapsed 
 
 tate ; then air is to be blown ir.to the stop- 
 
 cock seen as an orifice in fig. A, and sideways 
 in fig. B, until it is properly inflated, when 
 the stop -cock being turned off, the apparatus 
 Ijecomes so buoyant as to sustain the head 
 of the person wearing it comfortably above 
 the water. If made larger, it is to be placed 
 under the arms. It may, as before, be either 
 tied on, or if made without strings, as A, 
 the v>earer steps into it. 
 
 Another life-buoy, the invention of Lieut. 
 Cook, R.N., for the assistance of persons 
 who may fall overboard at night, is seen in 
 the following cut : — It consists of two copper 
 balls A, B, connected together by a wooden 
 rod, and between the balls is a fusee, which 
 burns with a brilliant light and so strong a 
 fire that the washing of the sea cannot 
 extinguish it. This can be lighted and let 
 down from a ship in ten seconds, and falling 
 near the drowning man, not only is a mark 
 for him to reach, but of sufficient buoyancy 
 to sustain him above water until a boat can 
 arrive, to the course of which it is also a 
 sure beacon. The machine is so weighted 
 below as to stand erect in the water. 
 
 Lift Pump. The form and construction 
 ot the common or lift pump is shown in 
 section in the following figure, in which F is 
 the cylinder or barrel. D is an air-tight 
 piston, which moves or works within it, 
 worked by the handle or lever J. G is the 
 suction or feeding pipe descending into the 
 jar of water A, which represents the well. 
 C is a valve at the bottom of the barrel, 
 and covering the top of the feeding pipe ; 
 and E a valve in the piston, both which 
 valves open upwards. B B is a stand for 
 supporting the pump above the jar of water. 
 Raising the piston, from the bottom to the 
 top of the barrel, will produce a vacuum in 
 the lower part of the barrel, and the pressure 
 
LI 
 
 LI 
 
 of the air upon the surface of the water in 
 the well will force sufficient water through 
 C to fill this vacuum. Depressing the piston, 
 ^ the valve E would be opened, and the water 
 flow through the opening, while the next 
 upward stroke would lift it into H, whence 
 it would flow through the nozzle L 
 
 Lift Tenter. (See Governor.) 
 
 Lift Wall. The cross wall of a lock 
 chamber. 
 
 LiGGBK. Ledger. The horizontal timbers 
 of a scaffolding are so called by workmen, 
 when they are parallel to the building. 
 
 Light. The principle or substance which 
 renders objects perceptible to our sense of 
 seeing- Some consider light as a fluid of a 
 peculiar character ; others consider it merely 
 as a principle, and attribute it to a sort of 
 vibration propagated from the luminous body 
 through a subtile ethereal medium. The 
 chief properties of light are, that it always 
 travels in perfectly straight lines, yet is 
 capable of being diverted out of its course, 
 when striking against a polished surface, 
 suffering reflection : also when passing from 
 one medium to another of different density, 
 which is called the refraction of light. Each 
 ray of white or solar light may be decomposed 
 into rays having various colors, giving rise 
 to the sciences of chromatics and polarization. 
 It travels with astonishing rapidity, at the 
 rate of 12 millions of miles in a minute, or 
 from the sun to us in 8 minutes ; and under 
 certain circumstances, the rays of light 
 impede, in others strengthen each other's 
 action ; this is called the interference of 
 light. (See Aberration, Interference, Re- 
 jection, Refraction, Polarization, 8fC.) 
 Light, in a painting, is the part most illumi- 
 nated, and consecjuently represented as the 
 
 brightest. It is called a natural light, if 
 the result of the shining of the sun or moon ; 
 or artificial light, if occasioned by a fire, 
 candle, &c. 
 
 Light. The upright space between two 
 mullions of a window, or between a muUion 
 and a jamb. 
 
 Lights, Northern. (See Aurora Borealis.) 
 Light-house. An erection, generally in 
 the form of a tower, built upon a coast, 
 harbour, or adjacent to dangerous rocks, for 
 the purpose of warning ships of their 
 situation, lights of various descriptions being 
 introduced at night. 
 
 Lightness. In all the arts, a term opposed 
 to density, heaviness, or clumsiness ; for 
 example, in architecture, a building of airy 
 and elegant proportions. In painting, a 
 picture, whose effect is graceful, sunny, or 
 lively. In sculpture, a statue, capital, &c. 
 delicately cut, and with flowing drapery, 
 clear leaves, &c. 
 
 Lightning. The electric fluid in a state 
 of considerable disturbance and condensation, 
 which passes visibly from cloud to cloud, 
 from a cloud to the earth, or more rarely 
 from the earth to a cloud. Lightning is of 
 three kinds, sheet or summer lightning, 
 which is unattended with thunder, and which 
 appears in a diffused sheet of light near the 
 horizon in warm weather. Forked lightning 
 is that zigzag and rapid emanation which 
 attends and indeed constitutes a thunder 
 storm, thimder always accompanying it, and 
 indeed being the consequence of it ; and 
 ball lightning, a still more dreadful kind, 
 where the electric fluid descends in a dense 
 straight stream, and appears to roll along the 
 ground as a ball of fire ; this kind is very 
 rare and dangerous. (See Thunder Storm.) 
 Lightning Conductor. An apparatus 
 to preserve ships and buildings from the 
 effects of lightning. It consists of a pointed 
 rod of copper, half or three-quarters of an 
 inch in diameter, pointed at top, and pro- 
 jecting two, three, or more feet above the 
 chimney, or other highest part of the build- 
 ing, the lower end being inserted four or five 
 feet in the ground. Its action is as follows : — 
 Should lightning approach the building, it 
 would, most likely, be drawn away silently 
 by the pointed wire ; or, if it should strike 
 the building, the conductor would convey it 
 to the earth without its doing any injuiy. . 
 
 Lightning, Theatrical. This used to be 
 produced by the fine powder of lycopodium, 
 projected with a strong powder-puff, and set 
 light to. Rosin, finely powdered, is now 
 used in the same manner, and for the same 
 purpose. 
 
 LiGNiN. The woody fibre of vegetables. 
 Timber with the sap, oils, resins, &c. which 
 it may naturally contain being boiled o t is 
 lignin. 
 
LI 
 
 Lignite. Wood converted into a kind of 
 coal. 
 
 Lignum Yit/e. A very hard kind of wood, 
 whe produce of the guaiacum tree. The 
 aeart wood is a blackish brown ; the young 
 wood, nearly white. When used in machinery, 
 which it is for pulleys, gudgeons, &c. it has 
 the iieculiar property of not requiring oiling 
 to diminish friction, itself yielding copiously 
 a resinous substance. It is extremely hard, 
 and the grain of the wood so interlaced one 
 with another, that it is almost impossible to 
 split it, particularly of old trees. 
 
 Like Arcs. The parts of lesser circles, 
 containing an equal number of degrees with 
 the corresponding arcs of greater circles. 
 
 Like Quantities. In algebra, those 
 which consist of the same letter and power. 
 
 Limb. The outermost border, or graduated 
 edge of a quadrant, or other mathematical 
 instrument ; also the edge of the sun or 
 moon, as the U2}per limb signifies the highest 
 edge ; the lower limb the bottom edge, &c. 
 Thus, we speak of the altitude of the sun or 
 moon's lower or upper limb. 
 
 Lime. In chemical language, the oxyde of 
 calcium, or a substance composed of a white 
 metal, called calcium and oxygen ; commonly 
 known as a white alkaline earth, existing 
 abundantly in nature, in a great variety of 
 forms and combinations. The sulphate of 
 lime is well known as plaster of Paris. The 
 carbonate constitutes the great and valuable 
 class of the marbles, lime-stones, ooUtes, 
 chalk, &c. It may be obtained in con- 
 siderable purity by submitting a piece of 
 marble to a white heat for an hour in an 
 open crucible. Pure lime is white, acrid, 
 caustic, and converts the vegetable blues to 
 greens. It is difficult of fusion, but promotes 
 the fusion of other bodies. WTien intensely 
 heated, as by the oxy-hydrogen blow-pipe, 
 it is remarkable for its luminosity. It is an 
 essential ingredient in mortars and cements. 
 When fresh burned, and while perfectly dry, 
 it is called quick lime, and is then in its 
 most caustic state. When water is added to 
 this, there is a great rise of temperature, 
 and a bulky white powder is obtained, which 
 is a hydrate, and is commonly called slaked 
 lime. Lime obtained from certain hard 
 lime-stones is of a yellow color until slaked. 
 
 Lime, Cream of. Water added to quick- 
 lime, until it assumes a cream-like appearance 
 and consistence. 
 
 Lime, Oil of. An old term to designate 
 the chloride of calcium, (muriate of lime,) 
 which has become deliquescent by exposure 
 to the air. 
 
 LiME-KiLN. A kiln for the purpose of 
 burning hme. 
 
 Limestone. A calcareous stone, which 
 being sufficiently burned or calcined, falls 
 into uowder upon the application of water, 
 
 LI 
 
 and being then mixed with water and sand 
 in certain proportions, forms a strong cement, 
 called mortar. 
 
 Limning. The art of painting in water 
 colors, in which sense it is used to distinguish 
 it from oil painting. A word now seldom 
 used, unless to signify herald painting on 
 carriages, &c., which is done with oil colors. 
 
 Line. A quantity extended in length only. 
 A line may be conceived to be formed by 
 the motion of a point ; as for example, a 
 rocket ascending, is but a point of light, yet 
 traversing through the air it appears like a 
 line of fire : so again, the meteor commonly 
 called a shooting star, appears to be a line 
 of light rather than a point. The intersection 
 of surfaces are lines. A line is not con- 
 sidered to have any breadth. Lines are 
 either straight or right, A ; curved or bent, 
 B ; and cob or mixed, being partly straight 
 and partly curved, C. 
 
 Lines, according to their position, may be 
 either vertical or perpendicular ; horizontal 
 or sloping at a certain angle. Line also 
 denotes a French measure, containing the 
 12th part of an inch, or the 144th part of a 
 foot. 
 
 Line, Equinoctial. (See Equator.) 
 
 Line, Horary, or Hour Lines. In dialling, 
 the intersection of the hour plane with the 
 dial plane. 
 
 Line, Visual, or Visual Ray. A ray of 
 light reflected from an object to the eye. 
 
 Line of Centres. A line drawn from 
 the centre of one wheel to the centre of 
 another, when their circumferences touch 
 each other. 
 
 Line of Direction. In mechanics, the 
 line in which motion is communicated. 
 
 Linear. Relating to lines, as opposed to 
 the effects of light and shade : thus, linear 
 perspective, treats of the representations of 
 the forms of objects in different positions 
 and at different distances, without reference 
 to color, or other accidental circumstances. 
 
 Lining. The covering of the interior 
 surface of a hollow body. In canal making, 
 the thickness or coat of puddle or clay, 
 sometimes applied to the bottoms or sides o. 
 canals to prevent them from leaking. 
 
 Link. A portion of a chain. 
 
 Linseed. The grain or seed of the flax 
 plant, also the oil extracted from it. The 
 former is used merely as a medicinal emulsion, 
 in coughs, colds, &c., commonly called 
 linseed tea. The latter, that is, the oil, is 
 the usual vehicle employed by the painter, 
 wherein to mix and grind his pigments. 
 
 m 
 
LI 
 
 LI 
 
 Lintel. A piece of timber or stone 
 placed over a doorway, window, &c. 
 
 LiauEFACTioN. Melting or dissolving, as 
 of ice. 
 
 LiauiD. That which besides having the 
 property of fluidity has also a peculiar 
 quality of wetting other bodies immersed 
 in it. 
 
 Liquid, or Saxox Blue. A solution of 
 the sulphate of indigo. 
 
 List. Synonymous with fillet. 
 
 Listing. In building, cutting away the 
 sappy edge of a board. 
 
 Literal Equation. That which is 
 expressed in general terms by letters, being 
 thus distinguished from a numerical equation, 
 in which all the coefficients are given numbers. 
 
 Litharge. Calcined lead, forming a 
 vitrified oxyde. It is used by painters to 
 boil with linseed oil, which occasions it to 
 dry much more easily than in its uncombined 
 state, the litharge, or as it is called by work- 
 men lilherage, being dissolved in the oil. 
 
 LiTHiA. Lithium. A rare alkaline sub- 
 stance, extracted from petalite, and other 
 minerals. It is the oxyde of a white metal, 
 which has been called lithium. 
 
 LiTHic Acid. Synonymous with uric acid ; 
 it forms the commonest variety of urinary 
 calculus. 
 
 LiTHOGLYPH. The art of engraving on 
 precious stones. 
 
 Lithographic Chalk. A material made 
 in the shape of drawing crayons, and intended 
 to produce the same artistical effect upon 
 stone as the ordinary chalks do upon paper. 
 The receipt for an approved chalk of this 
 description is as follows : — Common soap 
 1^ oz.; tallow 2 oz. ; white wax 2^ oz.; 
 shell lac 1 oz. Soap is the only ingredient 
 which must not vary ; it is intended by the 
 alkali it contains to render the whole miscible 
 with water. When melted the last time, it 
 may be cast in paper cartridges, or on a 
 marble slab, and cut up into slips when 
 nearly cold. It must be kept in well-stoppered 
 phials that damp may not reach it. The wax 
 and tallow are heated in an iron saucepan 
 till they catch fire ; the soap is cut into 
 small pieces, and added by degrees, stirring 
 the whole time. When dissolved, the burn- 
 ing is continued, till reduced to the volumn 
 the mass was before the putting in of the 
 Boap : then extinguish the flame, add the 
 shell lac, pour a httle on a cold plate, and 
 see if, when cold, it breaks in two ; if so, it 
 is perfect. It is to be melted again, and the 
 lamp black added. 
 
 Lithographic Drawing Ink, is for 
 executing writings on stone, or drawing 
 plans, &c., which shall be representations of 
 those executed with a pen. Its composition 
 is as follows : — Equal portions of tallow, 
 white wax, shell lac, and common soap 
 
 melted together ; afterwards add lamp black 
 as a color. The method of manipulation is 
 the same as for lithographic chalk. When 
 finished, it ihould resemble Indian ink, and 
 is to be used in the same manner with a fine 
 pointed steel pen. 
 
 Lithographic Press. A machine for 
 printing from stone or for producing im- 
 pressions from a drawing made upon stone. 
 The press we have given is called the lever 
 press, and is one of the first constructed : 
 (a more modern one will be found under the 
 name of its inventor, Straker.) The present 
 one consists of a strong square table ; upon 
 this the prepared stone is placed, one side of 
 it beuig close to the lower end of a frame 
 covered with leather, which lets down upon 
 the stone, the sheet of paper being put 
 between them. The workman wets the 
 general surface of the stone, then inks the 
 drawing with an inking roller. (See Inking.) 
 He then adjusts the damp paper upon it, 
 shuts down the flap of leather, then puts his 
 foot upon a treadle seen beneath the table ; 
 this pulls down an obliquely-placed lever 
 connected with it. The oblique lever is 
 fastened to another lever at top, which, of 
 course, is also pulled down by the action of 
 the treadle, and the scraper hanging over the 
 stone is forced tightly upon the flap ; the 
 printer places this at one end of the stone, 
 and gradually draws it forward towards him, 
 by which the ink is transferred to the paper, 
 and the print is completed. It may be taken 
 away, and the operation repeated for each 
 impression. The above press is most fit for 
 small work. 
 
 Lithographic Stone. A hard, smooth, 
 compact kind of lime-stone, much resembling 
 the hone stone in appearance, and adapted 
 
LI 
 
 LO 
 
 for lithographic drawings. It is prepared 
 for the draughtsman by first sawing into 
 slabs, then grinding the surface with sand of 
 different degrees of fineness until perfectly 
 smooth and clean. 
 
 Lithography. The art of drawing upon 
 and printing from stone. The first part 
 consists in drawing on a stone previously 
 made smooth and level with an ink or chalk 
 composed of greasy materials, so mixed as 
 to resemble soap. It is then washed with 
 an acid, which changes the soapy ink truly 
 into grease. The stone is now ready for the 
 second process, the printing. It is washed 
 over with gum water, which is suffered to 
 dry ; then taken to the press, sponged over 
 with water, inked with a thick ink, which 
 being oily, adheres readily to the grease on 
 the stone, but not at all to the wetted surface ; 
 the paper is then placed upon it, and pressure 
 applied, when the ink leaves the stone and 
 adheres to the paper, forming the print 
 desired, and which, of course, will be the 
 reverse as to the position of the objects to 
 that upon the stone. 
 
 LiTHOLOGiCAL. The stony structure or 
 character of a body partly calcareous and 
 partly organized. Thus, speaking of shells, 
 we consider their hthological character ; 
 speaking of the molluscous animals which 
 inhabit them, we treat of their zoological 
 character. 
 
 Litmus. Lacmus. Turnsol. A blue 
 liquid color obtained from the archill weed, 
 (the lichen roccella tinctoria.) It is much 
 used in dyeing, in staining furniture, and by 
 the chemist as a test for acids, the most 
 minute quantity of which turns it red. 
 
 LiTRAMETER. An instrument invented 
 by Professor Hare, of Pennsylvania, to 
 ascertain the specific gravity of liquids ; owing 
 its efficacy 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 C C, of the size and bore 
 usually employed in barometers, are made 
 to communicate internally with each other, 
 and with an elastic bag G, by means of a 
 brass tube and two sockets of the same 
 metal, into which they are severally inserted ; 
 the brass tubes terminate 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 B enters through a 
 collar of leather. The tubes are placed 
 vertically in grooves, against an upright slip 
 of wood, tenonned into a pedestal of the 
 same material. Parallel to one of the grooves 
 is a brass scale so graduated that each degree 
 may be equal to -^ of the whole height of 
 the tubes. It is long enough to admit 140°. 
 
 Close to this scale a vernier E 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. There are also two 
 sliding indices F F, to one of the tubes. 
 To use tlie instrument, let a vessel of water 
 be placed under one of the tubes, and a vessel 
 of the liquid to be tried under the other, 
 the tubes dipping in the vessels. The bag 
 being compressed, the greater part of the 
 air of the tubes is driven out, and the liquids 
 occupy its place, and rise to a height accord- 
 ing to their gravity, the heavier liquid, of 
 course, occupying the lower place. 
 
 Liver of Sulphur. Fused sulphuret of 
 potassium ; so called from its liver color. 
 
 LixiviATioN. The washing of a substance 
 in water in order to extract any soluble and 
 saline particles contained in it. 
 
 Lixivium. A solution obtained by lixi- 
 viation. 
 
 Loadstone. A magnetic iron ore, which 
 is black, with a slight metallic lustre. It 
 occurs chiefly among the harder or primitive 
 rocks, and is very abundant at Roslagen, in 
 Sweden, where it is manufactured into a bar 
 iron, particularly esteemed for making steel. 
 Its name is derived from its inherent property 
 of attracting iron and steel, or being in fact a 
 
LO 
 
 T-O 
 
 natural magnet. (See Magnet.) Although 
 two or three instances are recorded of as- 
 tonishing powers of attraction being shown 
 by a loadstone, yet it is generally infinitely 
 surpassed in strength by a bar of steel mag- 
 netized. 
 
 Lock. A well-known instrument for 
 securing doors, and preventing their being 
 opened, except by means of the key adapted 
 to the lock. 
 
 Lock, or Weir. In engineering, all those 
 works of wood or stone, or of both combined, 
 which are erected to confine and raise the 
 water of a river. The term lock, or pound- 
 lock, however, more particularly denotes a 
 contrivance, consisting of two gates, or two 
 pair of gates, called the lock gates, and a 
 chamber between them, in which the surface 
 of the water may be made to coincide with 
 that of the upper or the lower canal, accord- 
 ing as the upper or lower gates are opened, 
 by which means boats are raised or lowered 
 from one level to another. 
 
 Lock Paddles. The small sluices used 
 in filling and emptying locks. 
 
 Lock Sills. The angular pieces of timber 
 at the bottom of the lock against which the 
 gates shut. 
 
 Locomotive Engine. A steam engine 
 adapted to move itself forward, generally 
 along a perfectly smooth surface, as the rails 
 of a railroad. The term is used in contra- 
 distinction to a stationary engine. 
 
 Lode. In mineralogy, a vein containing 
 metal. 
 
 Logarithms, are a series of numbers 
 in arithmetical progression, answering to 
 another series of numbers in geometrical 
 progression. These numbers are of the 
 greatest possible use in almost all arithmetical 
 and trigonometrical operations, because by 
 help of them multiplication is performed by 
 addition ; division by subtraction ; involution 
 by multiplication ; and evolution by division. 
 
 Logarithmic Curve, or Logistic 
 Curve. A curve of such a nature that when 
 it has its abscisses in arithmetical progression 
 and its corresponding ordinates in geometrical 
 progression, the abscisses may be considered 
 as the logarithms of the respective ordinates, 
 from which property the curve has its name. 
 It is represented as follows : — A, B, C. 
 
 the quadrant of a circle into any number of 
 equal parts in the points B, C, D, E, &c., 
 and from the radii A B, A C, A D, &c. cut 
 off A F, A G, A H, A I, &c. continually 
 proportional, then the curve passing through 
 the points F, G, H, I, J, K, will be the 
 logarithmic spiral. In this instance the areas 
 are as the logarithms of the ordinates, and 
 hence the denomination of the curve. 
 
 Logarithmic, or Logistic Spiral, is a 
 curve having properties similar to the above, 
 but differently constructed. Thus, divide 
 
 Logistic Logarithms, are certain logr- 
 rithms of sexagesimal numbers or fractions, 
 used in astronomical calculations. The logistic 
 logarithm of any number of seconds, is the 
 difference between the common logarithm of 
 that number and the logarithm of 3600, the 
 number of seconds in a degree. The use of 
 these numbers is in computing aproportional 
 part in minutes and seconds, or hours and 
 minutes, or other sexagesimal divisions. 
 
 Logotype. Two or more letters cast in 
 one piece, as fF, ffl, ae, oe, &c. 
 
 Logwood. The wood of a small tree, 
 called the hoematoxylon campechianum. It 
 is heavy, hard, compact, of a fine grain, 
 capable of being polished, and scarcely 
 susceptible of decay. Its chief use, however, 
 is not as a wood ; but on account of the fine 
 red or purple dye which it yields both to 
 water and alcohol, a solution with the formei 
 is valuable to the dyer, with or without alum 
 or tartar. 
 
 Lombardic Architecture. A style of 
 building the same as the Norman. 
 
 LoNGiMETRY. The art of measuring 
 lengths, accessible and inacessible. 
 
 Longitude. In astronomy, is the distance 
 of the meridian of a star from the first point 
 or degree of Aries, which is the position of 
 the sun in the ecliptic at the time of the ver- 
 nal equinox. In geography and navigation 
 is the distance between the meridian of a 
 place, and a certain fixed meridian from 
 which the longitude is reckoned. Longitude 
 is always east or west, and in this country is 
 reckoned from Greenwich, so that the places 
 on the meridian, (see Meridian,) which is 
 exactly on the opposite side of the world 
 from us have 180° of longitude, whichever 
 way round we reckon ; while those places 
 
LO 
 
 LU 
 
 on the same meridian as Greenwich have no 
 longitude. 
 
 Longitude Stars. A terra frequently 
 used to denote those fixed stars which have 
 been selected for the purpose of finding the 
 longitude by lunar observations. The chief 
 of these are as follows : — Aldebaran, Pollux, 
 Regulus, Spica Virginis, Antares, Forma- 
 nault, and the largest star in Aquila. 
 
 Long Primer. The name of a type. (See 
 Type) 
 
 Loom. The machine used by weavers for 
 the weaving of cloth, velvet, silk, &c. 
 
 Loop, or Loop Holk. A narrow opening 
 in a wall for the admission of light, and in 
 time of siege serviceable for the archers to 
 shoot their arrows thi-ough. They were in 
 all the old castles and churches made very 
 narrow outwardly, but widening gradually 
 inwards. 
 
 Lotus. A kind of water lily, of magni- 
 ficent appearance, growing abundantly in the 
 Nile, so much so as to have been considered 
 by the ancient Egyptians as a votive plant, 
 characteristic of the country. They, there- 
 fore, introduced a representation of it in most 
 of their edifices, hieroglyphical tablets, &c. 
 The lotus, as an architectural ornament, is as 
 follows : — 
 
 Louver Window. Those openings or 
 wiiidows in church steeples, which are left 
 open or crossed by bars of wood, placed so 
 as to exclude the rain, but admit air, and 
 allow the emission of sound from the bells. 
 
 Louver Stones or Boards, corruptly 
 Lufer Boards. Those bars of wood, &c. 
 which cross the lights of a louver window ; 
 also, the narrow boards lapping over each 
 other, yet at some little distance apart, which 
 are placed over the coolers in a brewery, or 
 which compose the whole walls of a whiten- 
 ing, and sometimes a floor-cloth manufactory. 
 
 Low^ER Case. That case or assemblage of 
 boxes, holding type for the printer, in which 
 the small letters are kept. This case from 
 being most used is always nearest to the 
 printer's hand. The upper case or that far- 
 thest from him contains the larger and smal- 
 ler capitals, figures, &c. 
 
 Low-Pressuke Engine. A steam en- 
 gine, the motion or force of which is pro- 
 duced by forming a vacuum within the cylin- 
 der, by drawing off the steam into another 
 vessel, called the condenser, and there con- 
 densing it, 
 
 Lovv^ Wines. A name given by the dis- 
 tiller to the product obtained by a single 
 distillation of the wash or fermented saccha- 
 rine and spirituous liquid first made for the 
 purpose. Low wines are stroDger than the 
 original, but require to be re-distilled before 
 they are fit foi ordinary consumption. (See 
 Distillation.) 
 
 Loxodromic Curve, or Spiral. Tlie 
 path of a ship when her course is directed 
 constantly towards the same point of the 
 compass, thereby cutting all the iricridians 
 at the same angle. It is presumed .hat the 
 ship is not sailing on a parallel, that is, not 
 due east or west. 
 
 Lozenge. A term used by mechanics and 
 old authors for rhombus and rhomboid, or 
 that shaped figure which we commonly call 
 a diamond, from its being so figured on part 
 of a pack of cards. 
 
 Lozenge Moulding. A particular shaped 
 ornament used in the earlier Guthic styles of 
 architecture. This moulding derives its 
 name from being composed of straight, plain 
 mouldings, crossing each other, and forming 
 a series of lozenge-shaped depressions. 
 
 Lubrication. The oiling or anointing 
 surfaces which rub together. This is most 
 essential in machineiy of all kinds to di- 
 minish friction. The common lubricating 
 substances are fine olive oil for watch-work ; 
 soft soap and black -lead for wood ; oil or 
 tallow for machinery of a large kind. 
 
 Lucernal Microscope, A microscope 
 adapted to exhibit objects of a magnified 
 size upon a screen, they being illuminated by 
 a lamp, and the rest of the apartment 
 
LU 
 
 LU 
 
 supposed to be in darkness. The general 
 external appearance of the instrument is 
 that of the magic lantern, being furnished 
 with a lantern of the same description to 
 hold the light ; and in the commonest kinds 
 of instruments having the same lenses. In 
 the better kind of lucernal microscopes, solar 
 microscopes, and magic lanterns, the lenses 
 are as follows : — 
 
 A represents the light, inclosed in a tin box. 
 B a doubly convex lens, the side nearest the 
 light beuig flatter than the other, in the pro- 
 portion of 3 to 5. At C is a hole in the tube, 
 where the object is introduced. At D and E 
 are the magnifying lens ; they are plano- 
 convex, with their convex sides towards each 
 other, and fixed in a small tube which slides 
 in and out of the larger one — these lenses 
 being fixed in reference to each other, ac- 
 cording to their foci. The light from A 
 strikes upon B, and passing through con- 
 verges on to the object ; passing thence to D, 
 it is there still more converged, till the rays 
 meet the third lens E. From this they di- 
 verge, and throw the appearance of the 
 object on a white screen F, with the common 
 lenses of the magic lantern. This screen 
 must be made of the form of a part of a 
 hollow globe, otherwise the figures will be 
 much distorted, and clear only in the centre 
 of the field of view ; with the above lenses a 
 flat screen may be used. 
 
 Lucifer. A name given to the planet 
 Venus when she appears in the morning 
 before sun-rise. 
 
 Lucifer Matches. Slips of wood dipped 
 in such a composition that it will inflame 
 either by friction, or when slightly touched 
 with sulphuric acid. Those which are fired 
 by friction are dipped in a mixture of gum 
 water and phosphorus, melted together at a 
 heat of not more than 120°. Those which 
 inflame by the contact of the acid are tipped 
 first with brimstone, and afterwards with the 
 chlorate of potass, previously mixed in pow- 
 der with twice its weight of powdered sugar ; 
 a little gum water being added to give con- 
 sistence to the mixture. 
 
 Luminaries. Any objects giving light, 
 but more particularly applied by way of 
 eminence to the sun and moon. 
 
 Luminosity. The power of emitting a 
 light. 
 
 Luminous Words. (See Devices.) 
 
 LuMiNOUsDiscHARGER. ^ SecDischarging 
 Rod.) 
 
 Lunar. Any thing relating to the moon ; 
 thus we say, lunar month, lunar cycle, &c. 
 
 Lunar Caustic, Fused nitrate of silver. 
 
 Lunar Cornka. Muriate of silver. 
 
 Lunar Distance. In navigation, a po- 
 pular term used to indicate the problem of 
 finding the distance of the moon from the 
 sun or some fixed star, for the purpose of 
 ascertaining the longitude. 
 
 Lunar Rainbow. A rainbow occasioned 
 by the reflection of the light of the moon. 
 It differs in no respect from the common 
 rainbow, except in being exceedingly faint 
 in colors. It is a very rare phenomenon. 
 
 Lunation. The time between one full 
 moon and the next. 
 
 LuNE, Lunette, or Crescent. The 
 space between two unequal arcs of circles 
 which cut each other. The apertures in a 
 cylindrical or domed ceiling are by architects 
 also called lunettes. 
 
 Lungs Glass. An instrument br appa- 
 ratus used with the air pump, intended to 
 prove the elasticity of the air. It consists of 
 a glass globe, of about 4 inches diameter, 
 with a foot to it, and also a brass cap at the 
 top ; within the glass is a small bladder, 
 tied to a short tube, which is attached to the 
 cap, and projects an inch or so within the 
 glass. This tube passes out at the top, and 
 is terminated by a small orifice. The lungs 
 glass is placed under the receiver of the air 
 pump, and as the air is exhausted the bladder 
 collapses ; being admitted it expands again, 
 showing the exact action of the animal lungs 
 in respiration. 
 
 Lupinite. a bitter substance, extracted 
 from the leaves of the lupin. 
 
 LupuLiN. The bitterand aromatic principle 
 of the hop. 
 
 Lustre. A bright brass chandelier, sus- 
 pended from a ceiling, as we see in churches, 
 theatres, &c. 
 
 Lute. A substance of a pasty consistence, 
 
 M M 
 
MA 
 
 MA 
 
 for joining or making tight the joints of ves- 
 sels. Lutes are of various kinds. Common 
 dough with salt in it is a useful lute for the 
 distiller; putty is also often employed, or 
 clay mixed with linseed oil. Lime slacked 
 in the air, and mixed with the white of eggs, 
 is another kind. 
 
 Lye. a solution of an alkali in watcr^ 
 particularly applied to dissolved potash. 
 
 Lye Trough. A square trough or box, 
 in which lye is kept for the printer's use, 
 that he may be enabled to wash the ink off 
 the type which has been just printed from. 
 
 A liquid consonant 
 and the twelfth letter 
 of the alphabet. It has 
 one unvaried sound, and 
 is pronounced by striking 
 the upper lip against the 
 lower: it is never mute, 
 often ends Latin words, but never 
 Greek ones, the Greeks changing it into N. 
 M is also a numeral letter, and among the 
 ancients it was used for a thousand, or with 
 a dash over it for a million. In contractions, 
 it signifies Master, Marcus, Manlius,Meridies, 
 misce or mix, or mixture, and maniple or 
 handful. 
 
 Macaroni. An Italian production, made 
 of a dough of fine wheat flour, and by passing 
 through an instrument like a funnel, it 
 assumes a round cyhndrical form of the 
 thickness of a goose-quill. It is used in 
 domestic cookery for soups, ragouts, &c. 
 
 Maceration. The steeping of a body in 
 a cold liquid. 
 
 Machicolations. Perpendicular holes 
 left in the under side of overhanging parapets, 
 gateways, and turrets, that the defenders 
 within might shower down hot water, lead, 
 &c. upon their besiegers. 
 
 Machine. In a general sense is any thing 
 that is used to augment or to regulate moving 
 forces or powers. The term, however, is 
 generally restricted to a certain class of 
 agents which seem to hold a middle place 
 between the simple tools and the more com- 
 plicated, termed engines ; this distinction, 
 ho\^ever, has not a place in a scientific point 
 of view ; all such compound agents being 
 really machines, the parts of which they are 
 compounded being mechanical powers. 
 
 Machinery. Any collection of machines. 
 
 Machinist. The constructor or director 
 of machinery ; synonymous with engineer. 
 
 Macle. The name of certain diagonal 
 blotches or spots in minerals, like the 
 diamond in cards ; supposed to proceed from 
 some disturbance of the particles in the act 
 of crystallisation. 
 
 Macule. Dark spots which occasionally 
 appear on the surface of the sun, moon, and 
 even some of the planets. 
 
 Madder. A substance very extensively 
 used in dyeing red colors, particularly oii 
 woollen cloths. The best is brought from 
 the Levant, but a very large quantity is now 
 brought from the East Indies. It is the 
 stalk and leaves, and still better the root of 
 a plant, called the rnbia tinctoria. 
 
 Magellanic Clouds. A name given to 
 three permanent whitish appearances re- 
 sembling the milky way near the south pole, 
 being distant from it 13°. 
 
 Magic Lantern. A well-known optical 
 instrument, by means of which small painted 
 figures on the wall of a dark room are 
 magnified at pleasure. The following shows 
 the common instrument: — A small lamp, 
 with a reflector behind it, is placed in a tin 
 lantern, to the front of which is a projecting 
 tube open on both sides ; at the side of which 
 tube, and near that end which is nearest the 
 light, is a hole, to m^ove the sliders in and 
 out. A second tube slides withinside the 
 first. The requisite lenses are a thick j)lano- 
 convex lens at that end of the tube which 
 is fastened to the lantern ; and a double con- 
 vex lens at the outer end of the smaller tube. 
 The slider of objects is placed in the square hole 
 prepared for it ; the light passes the plano- 
 convex lens, strikes the picture, and passes 
 to the smaller lens, whence it is cast on the 
 white wall of an apartment, or a sheet, or 
 other screen. An infinitely better way of 
 glassing the lantern is described under the 
 article Lucernal Microscope, (which see.) 
 
 Magic Landscapes. A name given to 
 pictures which have been washed over with 
 
MA 
 
 MA 
 
 G) mpathetic inks, so that in the natural tem- 
 peiature of the air the picture appears without 
 color, but when warmed it seems like a tinted 
 landscape. Chloride of cobalt forms the blue 
 of the sky ; chloride of copper gives a yel- 
 low, and acetate of copper a green color. 
 
 Magic Picture. An electrical apparatus, 
 which under the appearance of a picture is 
 so formed as to constitute a Ley den jar, and 
 consequently when charged by the electrical 
 machine will communicate a shock to those 
 who incautiously touch it. A plate of glass, 
 which fits a frame, is partly covered on both 
 sides with tin-foil, leaving however a space of 
 clear uncovered glass all round ; the tin-foil 
 on the side of the glass which is to be out- 
 wards is covered with a picture ; the under- 
 side of tin-foil has a long slip of the same 
 that reaches to the lower part of the frame. 
 To experiment with it : — Hold it by the lower 
 side of the frame — drop a piece of money on 
 the picture^ — take seversd sparks from the 
 machine on to the money ; then taking hold 
 of the top of the picture, instead of the bot- 
 tom, direct a person to hold it there with 
 one hand, and having done so, to take up the 
 money with the other. This it will be im- 
 possible for him to do, as the moment his 
 second hand approaches the picture he will 
 receive the shock. 
 
 Magic Square, is a square divided into 
 cells, in which the numbers from 1 to the 
 proposed square are so placed, that the sum 
 of each row, whether taken horizontally, 
 vertically, or diagonally, is equal to a certain 
 given number ; thus in the annexed figure, 
 which contains nine cells, the sum of the 
 numbers in each row is equal to 15. 
 
 4 
 
 9 
 
 2 
 
 3 
 
 5 
 
 7 
 
 8 1 
 
 6 
 
 Magic Vases. A very amusing electrical 
 instrument ; for the purpose at the same time 
 of exploding hydrogen gas, and giving a 
 shock to the person w^ho holds them. B 
 shows the outward appearance of one of the 
 vases. A also the section of the upper part 
 of them. They may be made and used thus :— 
 Procure two strong brass tubes, F G. Let 
 them be about 5 inches long and 1^ internal 
 diameter, open at the bottom, and contracted 
 at the top, so that ordinary corks will fit 
 them. To the lower end of the tubes fit 
 wooden stands or feet, (as represented,) and 
 let a strong wire pass up the centre of the 
 wooden support, and so bent at the top, that 
 the points approach the brass tube, (as at C.) 
 Partly fill both vases or tubes with hydrogen, 
 and cork them carefuUy ; put one on a chain 
 proceeding from the outside of a Leyden jar, 
 D ; the other on a chain, E, connected with a 
 discharging rod, and let a person hold the two 
 brass tubes. When the shock is passed, both 
 vases of gas will be exploded, and the person 
 who holds them receive the shock. 
 
 Magilp. Magilpii. Megilph. a kind 
 of gold size, or thick, tenacious varnish, 
 made for the use of the painter. Linseed 
 oil, boiled with sugar of lead until it is very 
 thick, is recommended by some. Others 
 say, grind 8 ounces each of sugar of lead 
 and rotten stone, with linseed oil, as stiffly 
 as possible. Then melt 16 ounces of white 
 wax, when melted, stir in 8 ounces of spirits 
 of turpentine. Let it get cold, and when it 
 is so, grind it with the rotten stone and sugar 
 of lead. When wanted for use, if too stiff, 
 add turpentine. 
 
 M AGISTER V. Chemists foi-merly applied 
 this term to almost all precipitates, parti- 
 cularly to those of a white color, as the ma- 
 gi stery of bismuth. Chemists no longer use 
 the word, but it is still appUed by the artizan 
 to a few substances. 
 
 Magistery of Bismuth. Subnitrate of 
 bismuth. 
 
MA 
 
 MA 
 
 Magma. The general name of any crude 
 mixture of mineral or organic matters in a 
 thin pasty state. 
 
 Magnesia, One of the earths, having a 
 metallic base, called magnesium. It is a 
 white, soft, light powder, which shows alka- 
 line properties. It is infusible, except by 
 the most intense heat ; has no smell and lit- 
 tle taste. It is nearly insoluble in water, 
 but combines readily with sulphur, forming 
 a sulphuret ; and with the acids forming neu- 
 tral salts, many of them of great value in 
 medicine and the arts. 
 
 Magnet. A substance endowed with the 
 property of attracting iron, and also of 
 pointing itself in a certain direction. These 
 properties it is capable of communicating to 
 iron and steel bars. Magnets are of two 
 kinds ; natural, (see Loadstone,) and arti- 
 ficial. The latter are, according to their 
 shape, known as bar magnets and horse-shoe 
 magnets. (For the method of making arti- 
 ficial magnets, see jEpinus, Canton, Knight, 
 Mitchell, 8fc.) To preserve them, it is ne- 
 cessary to connect together the ends or poles 
 ■with a piece of smooth iron, which is called 
 the armature. If of a single bar, it is a 
 single magnet ; if of several joined together, 
 a compound magnet ; and if they be cased 
 in brass, it is said to be armed. Two points 
 at or near the ends are called the poles, and 
 the whole power of the magnet seems con- 
 centrated in these points ; one is called the 
 north pole, and the other the south pole. 
 The line which joins the poles is called the 
 axis. The following figure, No. 1, represents 
 a natural magnet or loadstone ; its usual ar- 
 mature is a piece of iron attached to each 
 end, and a third piece to connect together 
 these two. No. 3 shows a horse-shoe mag- 
 net, with a single piece of iron as an arma- 
 ture. No. 2 exhibits two bar magnets, laid 
 Bide by side, the N pole of one being oppo- 
 site to the S pole of the other, and a small 
 piece of iron at each end, which connects 
 together the opposite poles of both. 
 
 Magnetic Alarum, or more properly 
 Electro-Magnetic Alarum. A curious and 
 simple instrument, used to strike an alarum 
 at a great distance, so as to give notice of 
 a telegraph working, starting of a railway 
 train, &c. A A in the cut represents a bar 
 of soft iron, with a long wire twisted round 
 it, terminating in mercury cups. G H are 
 two wires, extending from one station to 
 
 another. They may be 50 or 100 miles long, 
 if so required. They are throughout their 
 whole length kept apart, and surrounded 
 ■with resin, Indian rubber, or other non-con- 
 ductor, and then inclosed in an iron tube. 
 The farther ends of them are placed in the two 
 cells of a small galvanic battery, the nearer 
 ends resting in the mercury cups G and H. 
 When intelligence is to be given, the long 
 wires are to be united to the battery ; when 
 the circuit is complete, the fluid passing 
 round the soft iron will render it strongly 
 magnetic. When it is so, it will draw down 
 or attract the piece of iron B. This, by 
 means of the crank C and the wire D, will 
 raise up the hammer E, so as to strike the 
 bell F. Withdrawing one of the wires from 
 contact with the battery occasions the action 
 to cease ; the piece of iron B rising again 
 to its former position, by means of a spring 
 attached to E, or otherwise. 
 
 Magnetic Battery. The same as com- 
 pound magnet, or a series of simple magnets 
 so united together as to act in concert. 
 
 Magnetic Compensation Plate. (See 
 Barlow.) 
 
 Magnetic Curves. The position in 
 which iron filings arrange themselves from the 
 
MA 
 
 MA 
 
 one pole to the other of a powerful bar mag- 
 net over which they are sprinkled. The 
 foregoing cut shows their peculiar nature : — 
 When iron filings are scattered over two 
 similar poles, (as in the next figure over the 
 two north poles of two magnets,) the curves 
 produced are of a different character, and 
 are called divergent, the filings not passing 
 in a curve from one to the other pole, but 
 each pole having its distinct system of curves 
 diverging from it, the two systems afterwards 
 crossing each other, leaving little rhomboidal 
 interstices between them. 
 
 Magnetic Declination. Synonymous 
 with the variation of the compass, which in- 
 dicates the deviation of the magnetic needle 
 from the true geographical meridian, it 
 pointing not to the north and south poles of 
 the earth, but to a point some degrees from 
 it. The amount of this variation is according 
 to the place on the earth's surface where the 
 magnetic needle is situated. 
 
 Magnetic Dip. A property of the mag- 
 netic needle of inclining one of its poles 
 towards the earth, (see Dipping Needle.) 
 It differs in different latitudes. The dip at 
 London is about 69° 12' ; over the magnetic 
 poles the dip is 90*^ ; at a line around the 
 earth, forming an equator to these poles, 
 there is no dip. 
 
 Magnetic EauATOR. A line around the 
 earth, every where equally distant from both 
 magnetic poles ; here the magnetic needle 
 does not dip, but stands horizontally, being 
 equally attracted to both the terrestrial mag- 
 netic poles. 
 
 Magnetic Electricity. A science com- 
 pound in character as in name, being the 
 explanation of certain effects produced by 
 the action of a magnet, which so resemble 
 those of electricity as to induce philosophers 
 to believe that magnetism is but electricity 
 in another form, and that the magnetic and 
 electrical fluids are identical. 
 
 Magnetic Fluid. The property or the 
 fluid which produces those attractive, di- 
 rective, and other effects, commonly known 
 as magnetic. Some philosophers suppose it 
 
 to be a fluid distinct from all others, yet 
 produced naturally by the same causes as 
 those which occasion the developement of 
 the electric fluid ; others, with apparently 
 more reason, imagine it to be identical with 
 the electric fluid itself; and modern dis- 
 coveries show that many properties are 
 common to both. The magnetic fluid will, 
 when concentrated, and properly conducted, 
 give a shock and a spark similar to those 
 which are electrical, and also produce chemical 
 decompositions. 
 
 Magnetic Induction. The power which a 
 magnet has of communicating the power which 
 itself possesses to bars of iron or steel placed 
 near to it, though not touching. If two 
 magnets are so placed as to affect the same 
 piece of iron, it is called complex induction, 
 whether they by their relative position con- 
 spire to heighten the effect of the single 
 magnet or to counteract it. 
 
 Magnetic Instruments. (See CompasSf 
 Kater^s Compass, Dipping Needle, 8fc.) 
 
 Magnetic Meridian. A vertical circle 
 in the heavens which intersects the horizon 
 in the magnetic poles. 
 
 Magnetic Needle. A small artificial 
 magnet, balanced on its centre so that it may 
 direct itself in accordance with the magnetic 
 meridian, as influenced to do by terrestrial 
 magnetism. 
 
 Magnetic Poles, Terrestrial. Two points 
 of the earth to which the poles of an artificial 
 magnet always tend ; that in the northern 
 hemisi)here, is called the north pole ; and at 
 the antipodes to this is the south pole. The 
 north pole is situated in the north-eastern 
 part of Hudson's Bay, at about 80° west 
 longitude and 60° north latitude. From the 
 great irregularity of the needle in the high 
 northern latitudes, it is inferred that there 
 is a second north magnetic pole, situated at 
 102° east longitude, with the same latitude 
 as the other pole. If this be proved to 
 exist there will be a second south magnetic 
 pole also. 
 
 Magnetic Susceptibility and Re- 
 tentiveness. The power which some kinds 
 of iron, and more especially steel, has of 
 receiving and retaining magnetic properties. 
 
 Magnetic Swan, Duck, Syren, Fish, 
 &c. Toys which act upon the principle of 
 magnetism. They are of Dutch manufacture, 
 formed of two pieces of very thin brass 
 beaten into the shape of half the object, and 
 soldered together so as to be water-tight ; a 
 darning needle or iron wire is placed within- 
 side, extending from the head to the tail of 
 the animal. Being so thin, these objects 
 float in water, and are so balanced as to 
 continue upright ; a small bar magnet held 
 to one of them will cause it to be attracted 
 and follow the magnet around a basin ; a 
 piece of bread, covering the point of the 
 
MA 
 
 MA 
 
 magnet, makes it appear that the swan, &c. 
 comes to be fed. 
 
 Magnetism. The science which explains 
 the laws and properties of the magnet. 
 
 Magnetism, Terreatrial, is that property 
 of the earth from which the magnetism of 
 the ordinary magnets, the direction of the 
 magnetic needle, and other phenomena are 
 derived, and upon which they necessarily 
 depend. 
 
 Magneto-Electrical Machine. An 
 instrmnent whereby the magnetic fluid can 
 be procured in a large quantity, and so made 
 to traverse a coiled-up wire, that it presents 
 phenomena exactly accordant with those of 
 electricity ; namely, the spark, the shock, 
 the chemical and deflagrating powers, &c. 
 One such machine is described under the 
 word Clarke ; another, and which is a more 
 convenient form, was previously invented by 
 Mr. Saxton, and is as follows : — 
 
 A represents a powerful compound horse- 
 shoe magnet, about 2 feet long. C C C the 
 armature or keeper of soft iron, inclosed in 
 three helices of copper wire, covered with silk. 
 D a wooden cup for holding mercury, move- 
 able by its stem H. E a copper disc, dipping 
 into the mercury, and communicating by a 
 brass socket J with one pole of the helices. 
 I is a slip or cross bar of copper, connected 
 with the other pole of the helices. F a 
 grooved wheel, fixed upon a central axis, which 
 is connected with the armature and coils, to 
 which wheel a rapid motion is imparted by 
 turning the larger grooved wheel F, which is 
 connected with the other wheel by means of 
 a band. G a thumb screw, for adjusting the 
 axis of the wheel F, so as to tighten or slacken 
 the band. Upon turning the larger wheel, 
 it occasions the coils, and with them the ar- 
 mature to revolve rapidly, and in each revo- 
 lution the slip of metal I, (this may be a 
 starred wheel with advantage,) dips twice 
 into, and of course twice leaves the mercury 
 in the cup ; at each of which times the mag- 
 net gives a spark, (seen on the mercury,) 
 and also if a contrivance be added so that 
 the human body may be in the circvdt be- 
 tween one pole of the helices and the other, 
 a shock will be felt. Thus from the rapidity 
 of motion which may be given to the arma- 
 
 ture the shocks so rapidly succeed each othei , 
 that they may be considered continuoue. 
 
 Magnifying, is used to denote the ap- 
 parent enlargement of an object by means of 
 a convex lens, or some other optical instru- 
 ment. 
 
 Magnifying Glass. A popular term 
 for any convex glass or lens which has the 
 property of magnifying 
 
 Magnitude. The extension of any thing, 
 whether it be in one direction, as a line ; in 
 two directions, as a surface ; or in three, as 
 a solid. 
 
 Mahogany. A hard and fine wood, much 
 used in cabinet-making, upholstery, &c. It 
 varies much in quaUty ; that grown on rocks 
 is the hardest, heaviest, closest in the grain, 
 and most beautifully veined. That wood 
 brought from the neighbourhood of Hondu- 
 ras, growing in swampy ground, is light, 
 porous, pale colored, and open grained ; and 
 is used for inferior purposes, and for the 
 patterns of wheel-work, &c. That brought 
 from Jamaica, and the more elevated Spanish 
 Colonies, is of a finer and more mottled 
 description, and is generally known as Spanish 
 mahogany. 
 
 MaluEic Acid. An acid formed when the 
 malic acid is distilled at a heat of 400°.- Its 
 salts are called malseates. 
 
 Malates. Salts of the malic acid. 
 
 Malic Acid. An acid which exists in the 
 juices of many fruits and plants, alone, or 
 associated with the citric, tartaric, and oxalic 
 acids. It occasions the sour taste of unripe 
 apples, gooseberries, &c. It has no smell, 
 is in the form of crystals which deliquesce 
 in the air, is soluble in alcohol, and is de- 
 composed at a heat of 3-18°. It combines 
 with numerous of the bases. 
 
 Malleability. The property of a solid 
 that is hard and ductile, which enables it to 
 be beaten, forged, and extended under the 
 hammer without breaking ; as is the case 
 with most metals, gold, lead, copper, and 
 silver especially. 
 
 Malt. The chief ingredient of which beer 
 is made, and from which it derives its strength 
 and spirituous qualities. It is made from 
 barley, thus : — The grain is first steeped for 
 48 hours in a cistern of water ; when taken 
 out it is thrown into a heap, where it begins 
 to sprout. Having thrown out its first root, 
 or acrospire, to a length of from ^ to ^ an 
 inch, it is spread upon a floor, where be- 
 coming dry, the germination ceases. It is 
 finally taken to a kiln, and spread upon a wire 
 floor, under which a clear fire is kept up, 
 until the malt is thoroughly dry, and in some 
 cases partly roasted. 
 
 Malting. The process of making malt. 
 
 Malt Kiln. A kiln or oven for drying 
 malt. 
 
 Mandrel. That part of a lathe to which 
 
MA 
 
 MA 
 
 the work to be turned is fastened, and which 
 receives motion from the great or fly wheel, 
 oy means of a cord. A is the series of pul- 
 ies, usually four in number. B C the arbor 
 or spindle, supported at one end by the point 
 of the screw G, and at the other by passing 
 through a hole in the front leg E, and kept 
 in its place by a slight shoulder near C. D 
 is the screw at the nose or front end of the 
 arbor, upon which the chucks that hold the 
 work are fastened. F a support for the 
 screw G. The whole is usually made of 
 iron, with steel collar, &c., and is to be 
 screwed down to the bed of the lathe, imme- 
 diately over the foot wheel, (if there be one,) 
 so that a cord passing over the grooves of 
 both may turn the mandrel. 
 
 Manganese. A greyish white metal, of 
 a fine grained fracture, very hard, very brit- 
 tle, with considerable lustre ; of specific 
 gravity 8-013, and requiring for fusion the 
 extreme heat of 160° Wedgewood. In con- 
 tact with the air it is converted into a brown, 
 and which afterwards becomes a black oyde. 
 It is this latter oxyde, the black or peroxyde, 
 which is one of the materials from which 
 oxygen may most easily be obtained, as it 
 gives out a portion of its oxygen at a red 
 heat ; also heated with hydrochloric acid, it 
 yields its oxygen to the acid, thus converting 
 it into chlorine. It is used in a very small 
 quantity in flint glass, and in a larger quan- 
 tity in the manufacture of imitation gems, 
 (see Pastes ;) blue enamels, and black pot- 
 tery ware. 
 
 Manganesic Acid. One of the combi- 
 nations of oxygen and manganese ; its salts 
 are called manganesates. 
 
 Mangle. A well-known instrument for 
 smoothing linen and similar articles, giving 
 them a polish in consequence of the rolling over 
 them a smooth substance or roller, assisted by 
 a heavy weight placed over it. 
 
 Manheim Gold. An alloy, consisting of 
 3 parts of copper and 1 of zinc. 
 
 Manna. The concrete juice of the Fracci- 
 nus ornus, a tree much ctiltivated in Sicily 
 and Italy, 
 
 Manometer. Manoscope. An instru- 
 ment intended to measure the rarefaction and 
 condensation of elastic fluids in confined 
 circumstances. The following is a simple 
 contrivance of this kind, invented by Mr. 
 Boyle, and called by him the Statical Baro- 
 meter, or Manometer. It consists of a bub- 
 ble of thin glass, hermetically sealed, about 
 the size of an orange, which being delicately 
 counterpoised when the air is in a mean state 
 of density, sinks when the atmosphere be- 
 comes lighter, and rises as it grows heavier. 
 
 Mantel. A beam resting on the jambs of 
 a fire-place, to support the brick-work above. 
 
 Manufacture. Any thing capable of 
 being made by hand, or manual dexterity, 
 although it may for the greater economy be 
 made or prepared by machinery. 
 
 Map. a plane figure or picture, repre- 
 senting the surface of the earth or a part of 
 it, the same as if viewed from a great height 
 above. If representing a portion of the 
 land, it is called a geographical map ; if a 
 portion of the sea, a hydrographical map or 
 chart. 
 
 Marble. A variety of limestone, of so 
 compact a- texture as to admit of a beautiful 
 polish. The diflerent kinds of marble are 
 infinite. The finest white marble is brought 
 from Italy, and is used for statuary and or- 
 namental work. Marbles are distinguished 
 either from the place they are found in, or 
 from their color. Thus we have Sienna, 
 verde antique, Egyptian, black, black and 
 gold, white, grey, dove, and numerous other 
 species. 
 
 Margarates. Saline combinations of the 
 margaric acid. 
 
 Margaric, or Margarous Acid. One 
 of the fatty acids, produced by changing tal- 
 low into soap with an alkali, and decom- 
 posing the soap by dilute acid. 
 
 Margarine, The more solid parts of 
 olive oil, and also a constituent in tallow, 
 mutton, &c. It may be procured by drying 
 olive oil on bibulous paper; then dissolving 
 it in ether, and afterwards left to spontaneous 
 evaporation. The white flakes which are 
 deposited are margarine. 
 
 Margaritic Acid. An acid obtained 
 from castor oil. 
 
MA 
 
 MA 
 
 Marine Acid. Muriatic acid ; now called 
 the hydrochloric acid. 
 
 MarineBarometer. a barometer capable 
 of being so suspended upon gimbals that it 
 always preserves itself erect, not being 
 affected by the motion of the vessel. 
 
 Marine Salt. Common domestic salt, 
 or chemically, chloride of sodium, or more 
 popularly muriate of soda. 
 
 Mariner's Compass. (See Compass.) 
 
 Marking Ink tor Linen. Dissolve ni- 
 trate of silver in double its weight of water. 
 Wet the linen first with a solution of pure 
 carbonate of potass, to which has been added 
 a little gum water. When dry, write with 
 the ink. 
 
 Marle. a mixed earthy substance, con- 
 sisting of carbonate of lime, clay, and sili- 
 cious sand, in very variable proportions. It 
 is sometimes compact, and at others pulveru- 
 lent, when dry. 
 
 Marlinespike. An iron tool tapering to 
 a point ; used to separate the strands of a 
 rope in order to introduce those of another, 
 when they are to be spliced or joined evenly, 
 without knotting. 
 
 Marmoretum. a metallic substance 
 formed of mercury and tin-foil, mixed in 
 such proportions as to become a pasty sub- 
 stance. It is used by dentists for filling 
 decayed teeth. Another marmoretum of a 
 different nature is formed of the white of 
 egg, a little water, and quick-lime pounded 
 together ; this similarly applied becomes a 
 hard marble-like substance. In architecture, 
 it is cement or mortar made of equal parts 
 of lime and powdered marble mixed with 
 water. 
 
 Marmor Metallicum. Native sulphate 
 of barytes. 
 
 MARauETRY Work. Inlaid work formed 
 of fancy woods, and occasionally enriched 
 with valuable materials. The portions inlaid 
 are cut in the form of birds, flowers, leaves, 
 scrolls, &c. This style of ornament was 
 much used formerly to decorate the fronts 
 of cabinets, the tops of chests, tables, &c. 
 The Italians carried the art to great per- 
 fection in the 15 th century ; so did the 
 
 French in the 17th. From France it was 
 introduced into England ; the floors of 
 several mansions, at the end of the 17th 
 and beginning of the 1 8th century being thus 
 constructed. There are floors in the British 
 Museum of this work. 
 
 Mars. One of the planets of our solar 
 system, the fourth in order from the sun, 
 and consequently the next above our earth. 
 This planet, which is known in the heavens 
 by his red and fiery appearance, performs 
 a revolution in his orbit in 686 days, very 
 nearly ; the rotation on his axis is 1 day, h., 
 30', 21" ; his mean distance from the sun is 
 142 millions of miles ; and his mean diameter 
 4398 miles, consequently he is about one- 
 eighth the size of our earth. He is attended 
 with an atmosphere, but with no moon. Mars 
 appears to us either globular or gibbous, but 
 never as a crescent ; also are often observed 
 white spots or protuberances around his 
 poles, which are supposed to arise from 
 masses of ice accumulating there during the 
 long winter, and which by their whiteness 
 strongly reflect the sun's rays. 
 
 Mars. The alchemical name for iron. 
 
 Marsh. A flat surface, the soil of which 
 is so far saturated with water throughout 
 the year as to be unfit for culture by the 
 spade or plough, but not so much as to 
 prevent it producing coarse grass and other 
 kinds of herbage. If liable to be overflowed 
 by the sea, it is called a salt marsh. 
 
 Marsh's Arsenic Apparatus. This 
 little instrument is effectual in detecting the 
 most minute quantity of 
 arsenic in any solution. 
 It is composed of a bent 
 glass tube slightly widened 
 at both ends, one arm of 
 it being 3 or 4 inches 
 longer than the other. 
 Into the shorter arm a 
 small piece of zinc is 
 dropped ; a thread should 
 be attached to it so that 
 it shall not quite reach 
 the bottom of the tube. 
 The liquid suspected to 
 contain arsenic has a little 
 sulphuric acid mixed with it, and a portion 
 is poured into the arm B. The stop-cock 
 being open, the liquid will fully occupy A ; 
 but hydrogen gas being formed by the con- 
 tact of the acid and zinc this will ascend ; 
 and the stop -cock being closed it will ac- 
 cumulate. Upon being let off and a light 
 applied to the jet of the cock, the arsenu- 
 retted or common hydrogen, as the case may 
 be, will be lighted ; if it be the former, that 
 is, if arsenic be present, it will tinge with a 
 purplish metallic stain a piece of glass held 
 close over it; with common hydrogen no 
 stain will be perceptible. 
 
MA 
 
 MA 
 
 Marsh's Rotatory Bucket. An electro- 
 magnetic apparatus, which revolves when 
 filled with an acidliquor 
 and placed upon the 
 pole of a powerful mag- 
 net. A is the magnet. 
 B C a copper vessel of 
 an outer and inner side, 
 a space of half an inch 
 or so being between 
 them, and having a 
 bottom shaped like a 
 ring ; this is made 
 water-tight. D is a short cylinder of zinc 
 fastened to the upper bowed wire ; this is 
 supported upon a point resting in a mercury- 
 cup. The vessel A B C is also supported by 
 a wire resting on a point. When in use, the 
 copper vessel, (which should be as thin as 
 possible,) turns in one direction around the 
 pole of the magnet, and the zinc in the con- 
 trary. 
 
 Marsh's Rotatory Floating Appa- 
 ratus. This is an improvement upon the 
 invention of De Rive, 
 (see Be la Rive.) That 
 required to be floated in 
 a basin of acidulated 
 water ; this contains 
 within itself the acid, 
 and requires to be floated 
 in common water only, 
 and that only for the 
 sake of giving it freedom 
 of motion. A is a coil 
 of wire. B the end of 
 the glass tube C C. 
 Within B are seen two 
 circles, one within the other ; the outer is a 
 circle or strip of copper without a bottom, 
 and within this, at D, is a strip or circle of 
 zinc ; they both descend into the glass tube, 
 which is filled with acid and water. E E is 
 a cork which floats the whole. The glass 
 tube may be dispensed with altogether, and 
 a silver or copper thimble used instead ; this 
 will hold the acid, and a wire of zinc inside 
 will excite sufficient galvanic action. 
 
 Marsh's Thermo-Electrio Rect- 
 angles, consist of two rectangles of fine 
 wire crossing each other, the lower side of 
 each being of platinum wu-e, the other sides 
 of silver wire ; they are united together and 
 
 liiiHulUinilJIioulilllHiiliinilllOfillllUn 
 
 balanced on a point. When this little 
 apparatus is put close to the poles of a 
 powerful horse-shoe magnet, and heat from a 
 spirit lamp be applied to one corner, where 
 the metals join, the apparatus will revolve 
 with rapidity. 
 
 Marsh's Vibratory Wire. An electro- 
 magnetic instrument, showing the effect which 
 a magnet has upon a freely-suspended wire, 
 which is conveying a current of electricity. 
 Its ' construction is as follows : — A copper 
 wire, with a loop to it, is suspended from a 
 hook A, and is free to move in every direc- 
 tion ; the hook A is also a wire terminated 
 by a mercury cup. The lower end of the 
 suspended wire dips into a little channel cut 
 into the wooden stand ; to the bottom of the 
 channel leads another wire, leading to a se- 
 cond mercury cup B . A small quantity of mer- 
 cury bemg put into the channel of the stand 
 completes a metallic connection throughout, 
 the suspended wire being allowed to dip into 
 the mercury in the channel. If a little mer- 
 cury be placed on the hook A ; and if the 
 two cups and these be connected with a gal- 
 vanic battery, the wire would conduct the 
 fluid, but without being itself visibly afi'ected ; 
 but when a strong magnet is placed with its 
 poles near to the end of the wire, it is imme- 
 diately thrown up, vmtil leaving the mercury 
 surface the circuit is rendered incomplete, 
 when it falls again only to be thrown up a 
 second time, and thus a vibratory motion is 
 established. 
 
 Martial. Belonging to iron. 
 
 Martial Ethiops. ITie protoxyde of 
 iron, obtained by moistening iron filings 
 slightly with water, and exposing them for 
 a day or two to the air. A quantity of 
 black or protoxyde forms upon the surface. 
 
 Martial Regulus. An 'alloy formed by 
 melting together 1 part of iron filings with 
 2 parts of antimony. 
 
 Masonry. Any kind of stone-work. If 
 composed of exceedingly large rough stones, 
 not united by mortar, it is called crjclopian, 
 as the Egyptian temples, and many Druidical 
 remains in this country ; if formed of stones 
 of irregular shapes and sizes, it is called 
 rubble; if long or square stones were placed 
 
 N N 
 
MA 
 
 MA 
 
 angularly, it is called herring -hone; if smooth 
 and flat, ashlar; if roughly hewn into a 
 square form, and pitted with holes, it is rock 
 masonry ; if champfered at the edges, it is 
 called rusticated. 
 
 Mass. The quantity of matter in any 
 body, which is always proportioned to and 
 may be estimated by its weight, whatever be 
 its figure or magnitude. 
 
 Massicot. The yellow oxyde of lead ; it 
 is used as a pigment by the painter. 
 
 Masterman's Steam Engine. This is 
 an engine of the rotatory kind, which pos- 
 sesses much simplicity, and is especially to 
 be noted on account of its valves, which have 
 since its invention, (1820,) been called Mas- 
 terman's Valves. The following figure is a 
 transverse section of this steam wheel. A B 
 C D, &c. are weights at the end of short 
 levers, which open and shut the valves during 
 the revolution of the wheel. S S is a steam- 
 tight ring, divided into six or more com- 
 partments by the valves. Each of these 
 chambers has a communication with one of a 
 like series of perforations surrounding the 
 axis of the wheel, by the radiating arms or 
 channels, E, F, G, H, &c. This series of 
 perforations revolves with the wheel against a 
 fixed plate, which has three openings or per- 
 forations ; one leads to the condenser, one to 
 the boiler, and the other to the cistern of 
 water. The moveable series of perforations 
 are brought in rotation opposite each of the 
 three perforations in the fixed plate, conse- 
 quent in every rotation of the wheel ; each 
 arm and chamber will communicate in turn 
 with condenser, water column, and boiler. 
 In the position shown in the figure, the 
 moveable opening of arm G is opposite the 
 condenser ; the opposite arm, (hid by the 
 stand,) will be therefore connected with the 
 water column. When steam from the boiler 
 is allowed to pass through G, it will fill the 
 chamber connected with it, and prevent the 
 water rising on the side where there is no 
 valve to oppose it, and if of still greater 
 
 elasticity will force it up on the other side, 
 from the valves being made to open in that 
 direction only. The pipe G communicating 
 with the condenser, the column of water on 
 the circumference of the wheel being relieved 
 from the pressure of the steam will rise to a 
 height corresponding to the condensation 
 that takes place ; this gives a preponderance 
 to one side of the wheel, which brings other 
 arms into the same position, so that a con- 
 tinuous motion is generated. 
 
 Mastic. A resin procured by making 
 incisions in the bark of the pistacia lentiscvs, 
 a tree cultivated in the Levant. It is in 
 yellow, brittle, transparent, rounded tears, 
 which soften between the teeth, with bitterish 
 taste and aromatic smell. 
 
 Mastic Varnish. Mastic resin dissolved 
 in strong spirits of wine. It is quite trans- 
 parent, colorless, and dries quickly. It is a 
 good varnish for pictures and small cabinet- 
 work. 
 
 Materials. The different kinds of bodies 
 or substances used in the construction or ma- 
 nufacture of any thing. It differs from tools 
 or machines in being materially altered or 
 consumed in the operation of the artizan ; 
 thus, fir wood is the material from which 
 pitch is made, the wood at the same time 
 being consumed. Coal is the material of 
 which gas is manufactured, here the coal is 
 not wholly consumed, but greatly changed in 
 properties. 
 
 Mathematics. The sciences which treat 
 of the ratio and comparison of quantities. 
 Mathematics are divided into two classes : 
 the one called pure and abstract ; the other 
 compound or mixed. Pure mathematics re- 
 late to magnitudes generally, simply and 
 abstractedly. To this class belong arithmetic 
 or the art of computation ; geometry or the 
 science of measurement and extension ; and 
 analysis, fluxions, or the comparison of mag- 
 nitudes generally. Mixed mathematics are 
 those parts of natural philosophy, which are 
 by their nature susceptible of mathematical 
 investigation, such as astronomy, optics, me- 
 chanics, the laws of motion, &c. &c. 
 
 Mathematical. Relating to mathema- 
 tics. 
 
 Mathematical Combinations. A name 
 given by Messrs. Thorowgood and Besley, the 
 type founders, to various ornamental pieces 
 of type, so cast that they will fit each other 
 in different ways, yet form a continued line 
 or surface. They are particularly adapted for 
 the borders of cards, ornamental hand-bills, 
 &c. The examples, and detached pieces, 
 will explain their nature, observing that there 
 are several different patterns of type, and 
 that the combinations which they will form 
 are endless. The invention is French, anil 
 all the largest English type founders have 
 adopted the idea. The examples bear the 
 
MA 
 
 ME 
 
 names of the casters. Some type founders 
 call them changeable borders. 
 
 This example is composed of the following 
 six pieces, some of them repeated as re- 
 quired. It is evident to what a variety and 
 extent of combination even a few pieces may 
 be carried. 
 
 ^mm^ 
 
 ^ 
 
 The other example is a border of a lighter 
 character, and therefore better adapted to 
 small and delicate work. It is composed of 
 a repetition of only four distinct pieces of 
 type. 
 
 *^*^^^5^^^^^^ 
 
 Although the above contains but four pat- 
 terns, yet the founder supplies the six fol- 
 lowing ; thus fancy and taste may exercise 
 themselves to the utmost. 
 
 i# ^ |> s ^ ^ 
 
 Matras, or Mattrass. A thin flask or 
 bottle, with a thin egg-shaped bottom and 
 long neck, much used for digestions in chemi- 
 cal researches. 
 
 Matrice. a mould, particularly for the 
 casting of small articles in metal, such as types. 
 
 Matrix. The earthy or stony matter 
 which accompanies ores, or envelopes them 
 in the earth ; also a mould for any thing. 
 
 Matter. In philosophy and the arts, is 
 generally understood to mean that solid, 
 inert, divisible substances, accessible to the 
 senses, of which all bodies whatever are 
 composed. 
 
 Maugham's Blow-Pipe Jkt. The ap- 
 pended cut is a section of this excellent jet, 
 which is adapted to the oxy-hydrogen blow- 
 pipe. It is screwed by the end A to a 
 gasometer, containing oxygen, while the 
 flexible tube B is connected with the gasometer 
 of hydrogen. The cocks near A and B re- 
 gulate the supply of the gases. These 
 
 gases after passing through their respective 
 tubes meet in a square chamber near to the jet. 
 Through this part of the apparatus a wire 
 passes gas tight, (yet capable of motion.) To 
 the upper end of the wire, the cylinder of 
 lime F, (for the lime light when wanted,) 
 fits, and may be turned about by the lower 
 end of the wire. The terminating jet is for 
 this purpose bent at an acute angle as D £ ; 
 though other jets for other purposes may be 
 snbstituted. 
 
 t^ 
 
 Maximum and Minimum, In a variable 
 quantity or effect, that which is the greatest 
 possible, under the circumstances in which 
 it is placed, is called the maocimum. Thus 
 in respect to the sails of a windmill, they 
 may be placed at any angle, but there is one 
 angular direction in which the wind will have 
 more power than in any other, it will pro- 
 duce therefore the maximum at this angle. 
 There are other cases in which we seek for a 
 mininnm, that is the least possible. In ma- 
 thematics, they are the greatest and least 
 value of a variable quantity, and the method 
 of finding these greatest and least values, js 
 called the method of maxima and minima. 
 
 Mean. A middle state between two ex- 
 tremes ; thus we say mean distance, motion, 
 time, &c. An arithmetical mean is half the 
 sum of any two quantities ; thus 8 is the 
 mean between 2 and 14. K geometrical 
 mean is the square root of the product of 
 any two quantities ; therefore 4 is the geo- 
 metrical mean of 2 and 8. An harmonical 
 mean is double a fourth proportional to the 
 sum of two quantities and the quantities 
 themselves. Thus if 2 + 3 : 3 :: 2 : \\ — 
 this multiplied by 2 or 2f is the harmonical 
 mean. 
 
 Measure. Any determinate quantity, 
 used as a standard with which others may be 
 compared in space, time, quantity, velocity, 
 &c. The measure" of an angle is the number 
 of degrees, minutes, &c. contained in the arc 
 of a circle comprised between the two legs 
 which form the angle, the angular point 
 being the centre. Common measure in vul- 
 gar fractions is any number that will divide 
 both terms of the fraction without remain^ 
 der. The measure of a line is its length 
 compared with some determinate line, such 
 as a mile, foot, inch, &c. The measure of a 
 
ME 
 
 ME 
 
 surface is the number of square miles, feet, 
 inches, &c. contained on it. The measure 
 of a solid is the number of cubic inches, 
 feet, &c. it contains. Measures, in com- 
 merce, are of certain denominations ; those 
 chiefly used in this country are long, land 
 or square, and cubic or solid measure. 
 One for liquids, called wine measure; dry 
 measure for dry goods ; that of time : and 
 one for angular measurement, in degrees, 
 minutes, &c. 
 
 Measuring. The art of finding the exact 
 quantity, extent, or capacity of any thing. 
 
 Measuring Glass. A glass vessel used 
 to measure small quantities of liquid, less 
 than the usual commercial measures can 
 ascertain. Some are made so small as to 
 measure any number of drops, called there- 
 fore drop glasses ; others, drams up to 16 in 
 number ; while those of the large size may 
 measure ounces to half a pint, or more in 
 quantity. 
 
 Measuring Tape. A piece of tape, of 
 from 10 to 100 feet in length, marked on 
 one side with feet and inches, and on the 
 other with links and rods. It is rolled up in 
 a box for the convenience of carriage. Used 
 in land and house measuring. 
 
 MeasuringWhekl. (SeePerambulator.) 
 
 Mechanical. Relating to mechanics. 
 It also is used as opposed in meaning to 
 Bcientific or mathematical, as we speak of a 
 mechanical contrivance, a mechanical method 
 of solving a problem, &c. 
 
 Mechanical Carpentry. That part of 
 the art of construction in timber, which 
 treats of the proper disposition of framing, 
 so as to enable it to resist its own weight, or 
 any additional load or pressure that may be 
 laid upon it. 
 
 Mechanical Curve. A curve of such 
 a nature that the relation between the ab. 
 scissa and ordinate cannot be expressed by 
 an algebraic equation : such curves are now 
 generally called transcendental curves. 
 
 Mechanical Force. The power of any 
 machine or mechguiical contrivance. It may 
 be said to be the measure of all other force, 
 as it bears reference to the effect produced : 
 thus steam, water, man, and horse-power are 
 all represented by the amount of mechanical 
 force they can exert. 
 
 Mechanical PHiLosoPHy. The science 
 of mechanics ; applied to physical inquiries, 
 
 or on the other hand, the application of the 
 laws of general science to the improvement 
 and construction of machinery. 
 
 Mechanical Powers, are the simple 
 instrument? or elements, of which every 
 machine, however complicated, must be con- 
 structed. They are the lever, the wheel and 
 axle, the pulley, the inclined plane, tlie 
 wedge, and the screw. 
 
 Mechanics, is that science which investi- 
 gates the nature, laws, and effects of motion 
 and moving powers. It teaches the con- 
 struction of machinery, and the adaptation 
 of materials for required purposes. 
 
 Mechanism. The construction and em- 
 ployment of machinery. t| 
 
 Mechanist. One acquainted with the 
 laws of mechanics. 
 
 Mechloric Acid. A compound of mc- 
 conia and chlorine. 
 
 Meconates. Salts of the meconic acid. 
 
 Meconic Acid. A peculiar acid which 
 exists in opium. It crystallises in trans- 
 parent and micaceous scales of an acid 
 taste ; soluble in 4 paits of hot water, and 
 in alcohol. 
 
 Medallion. In architecture, a circular 
 tablet, on which are embossed figures, busts, 
 and other ornaments. In the fine arts, it is 
 a large medal or coin, stamped to com- 
 memorate a particular event, or in honor of 
 some distinguished person. 
 
 Medallurgy. The art of striking medals 
 and other coins. 
 
 Medical Electrical Jar, is the same 
 in principle as the ordinary Leyden jar, used 
 for electrical purposes ; the 
 difference consisting chiefly in 
 the arrangement of the parts 
 for the greater convenience of 
 electrifying a patient, when 
 such an application is required 
 medicinally. It is, in fact, 
 two Leydeu jars connected so 
 together that the one or the 
 other may be used according 
 to the strength of shock re- 
 quired. B is a common Leyden 
 jar, holding about a quart, 
 and having a brass hook, F, 
 at the bottom of'it, connected 
 with the outer coating. A is 
 a glass tube open at both ends, 
 lined partly inside and out with tin-foil, 
 there being about two inches of glass at each 
 end uncovered. This is fitted into the 
 wooden cover of B, and has a brass ball at 
 the top, terminating with a hook E, and 
 pierced with two holes, through which pass 
 two wires C and D. The wire C reaches 
 only to the tin-foil within the tube A, and 
 is bent so as to touch it. The wire D reaches 
 to the bottom of B. When the short wire 
 *only is in, the shock, or as it is then called, 
 
ME 
 
 ME 
 
 from its trifling character, thevibration, pro- 
 ceeds only from the tube ; but when both 
 wires are in, the shock is given from the 
 larger bottle. 
 
 Medium. Denotes that space or region 
 through which a body passes in its motion 
 towards any proposed point, being used in 
 contra-distinctioh to a vacuum, which is a 
 simple void space. Thus air, water, glass, 
 &c. are media of different densities, and 
 possessed of different powers of refraction, 
 resistance, &c. 
 
 Medium, Ethereal. (See ^ther.) 
 
 Meerschaum. A white mineral of a 
 somewhat earthy appearance, always soft, 
 but adhering to the tongue. It is not un- 
 common in Asiatic Turkey. The Turkish 
 pipes are mostly made of it. Pipe-bowls 
 are imported into Germany from Turkey. 
 The Germans soak thepi first in tallow, and 
 then in wax, to give them a transparent, 
 alabaster-like appearance. 
 
 Megameter. (See Micrometer.) 
 
 Melanic Acid. A black coloring matter 
 which has been observed in urine. 
 
 Mellitic Acid. An acid discovered in a 
 mineral called mellite or honeystone. 
 
 Mellon. A new compound of carbon 
 and azote, discovered by M. Liebig. By 
 heating bi-sulpho-cyanide of mercury, the 
 mellon remains at the bottom of the retort 
 in the form of a yellow powder. 
 
 Melloni's' Thermo -Electric Pile, 
 consists of 50 small bars of bismuth and 
 antimony, placed parallel, side by side, 
 forming one close bundle A B, the first and 
 last bars having wires to them, E F, which 
 reach to the binding screws G H, where are 
 two other wires that are connected with a 
 galvanometer. The bars are bound together 
 by a ring C, which is supported by the stand 
 D. The two ends of the bundle of bars are 
 Dlackened. The bars of bismuth which 
 succeed alternately those of antimony, are 
 soldered at their extremities to the bars of 
 the latter metal, and separated from each 
 other at every other part of their surfaces 
 by some insulating substance, such as paper 
 or silk. When one end of the pile becomes 
 warmer than the other, even to a very small 
 
 degree, it is indicated by the galvanometer, 
 showing that heat, under certain cii'cum- 
 stances, produces an electric effect. 
 
 Melting Point. That pomt of the tTier- 
 mometer which indicates the heat at which 
 any particular solid becomes fluid, is termed 
 the melting point of that solid. 
 
 Member. A part of any thing, as the 
 members of a steam engine are the boiler, 
 cylinder, piston, &c.; of an edifice, the 
 columns, fascia, pediraentj &c. 
 
 Memnon, Statue of. A celebrated statue 
 of King Memnon, erected in Egypt, which 
 had the peculiar property of uttering sounds 
 at particular times of the day. At sun-rise 
 it gave a melodious sound like the twang of 
 a wound-up harp string. This music was 
 said to have been produced by the rays of 
 the sun when they fell upon the statue. At 
 the setting of the sun, and in the night, the 
 sound was mournful. 
 
 Meniscus. A lens which is convex on 
 one side and concave on the other. (See 
 Lens.) 
 
 Menispermic Acid. An acid which has 
 been extracted from the berries of the 
 cocculus indicus, or as it is now called menis- 
 permum cocculus. 
 
 Menstruum. A solvent or dissolvent ; 
 any fluid that possesses the property of dis- 
 solving or separating the parts of solid bodies. 
 Mensurability. The capacity of being 
 measured. 
 
 Mensuration. That part of mathe- 
 matics which is employed in ascertaining the 
 extension, solidity, and capacity of bodies ; 
 synonymous with measuring. 
 
 Menyanthin. The peculiar principle of 
 menyanthes trifoliata, or bog bean. 
 
 Mephitic Air, or Mephitic Acid. Car- 
 bonic acid gas. 
 
 Mercaptan. Mercaptum. Mercaptan 
 is another name for hydro-sulphuric ether, 
 which Dumas considers as a binhydro- 
 sulphate of carbon. Zeise regards it as a 
 hydruret of a certain compound base, which 
 he calls mercaptum. 
 
 Mercator's Chart. (See Chart.) 
 Mercurial Cup. A cup-shaped piece oi 
 wood, with a wire through the lower part. 
 The object of it is to hold a 
 small quantity of mercury, 
 and thus to furnish the 
 means of a complete metallic 
 communication between one 
 part and another of an electro- 
 magnetic apparatus. A small 
 quantity of mercury being 
 put into the cup, and meet- 
 ing the end of the wire, previously brightened, 
 attaches itself to it ; a second wire, with 
 mercury attached to it in the same way, is 
 dipped into the top of the cup. 
 
 Mercurial Thermometer. A ther- 
 
ME 
 
 ME 
 
 mometer which is supplied with mercury, 
 rather than with spirits of wine, or other 
 fluid. 
 
 Mercurial Trough. An instrument 
 used for the collection of such gases as are 
 absorbable by water, and to which, there- 
 fore, the ordinary pneumatic trough is in- 
 applicable. One great object in the con- 
 struction of mercurial troughs is to have 
 them effective without requiring a large 
 quantity of mercury. The following is one 
 of the best construction — the part which 
 holds the mercury is made of cast iron : — 
 
 A is a tin trough, in which the instrument 
 stands. B is a gas-holder, into which a gas 
 jar C, may be dipped. D is a vessel in 
 which gas is being generated ; it ascends 
 through the mercury within the gas-holder 
 to the jar above. E and F are a lamp, 
 (moveable up and down,) retort, and small 
 jar, for making a small quantity of gas only. 
 G H is a trough lower than the square frame 
 at top, in the upper part of which is a long 
 channel holding mercury, terminating at one 
 end in the gas-holder. 
 
 Mercurius Dulcis. An old name for 
 calomel, or the proto-chloride of mercury. 
 
 Mercurius Vit^. Hydrated protoxide 
 of antimony, called also formerly Algarotti's 
 powder. 
 
 Mercury. The planet which is nearest 
 to the sun, his mean distance being 36 
 millions of miles. He revolves on his axis 
 in 1 day, h., 5', 28", and his year con- 
 sists of about 116 days. His diameter is 
 about 3123 miles, and the light and heat he 
 receives from the sun is six times greater 
 than by our planet. He changes his phases 
 like the moon, but generally appears to us 
 like a small crescent. 
 
 Mercury. A metal which is fluid at 
 common temperatures. It freezes at 39*^ 
 below zero Fahr., and boils at 656°, at which 
 heat it passes oS in vapour. Its specific gravity 
 
 is 13*6, and it has an exceedingly bright 
 silvery appearance. It combines with great 
 readiness with certain metals, such as gold, 
 silver, zinc, tin, and bismuth, forming in 
 certain proportions fluid solutions of these 
 metals : such mercurial combinations are 
 called amalgams. This property is extensively 
 used in many arts, such as separating gold 
 and silver from their ores, gilding, plating, 
 making looking glasses, &c. Mercury also 
 combines with sulphur, forming cinnabar 
 or Vermillion. It is also soluble in numerous 
 of the acids, forming compounds highly 
 useful in medicine and the arts. 
 
 Meridian, In astronomy and geography, 
 a great circle of the sphere passing through 
 the zenith, nadir, and poles of the world, 
 crossing the equator at right angles, and di- 
 viding the sphere into two hemispheres, the 
 one eastern, and the other western. When 
 the sun is in the meridian it is noon in all 
 places situated under it. There are as many 
 meridians as there may be conceived points 
 in the equator. In effect the meridians 
 always change, as the longitude of the place 
 varies, and may be said to be infinite ; each 
 respective place, from east to west, having 
 its respective meridian. The first meridian 
 is that from which all the rest are accounted, 
 reckoning from west to east. The first me- 
 ridian is the beginning of longitude. 
 
 Meridian Altitude. The height of the 
 sun, moon, &c., above the horizon, when it 
 crosses the meridian of a place. The meri- 
 dian altitude of the sun therefore will be his 
 altitude at noon day. 
 
 Meridian of a Globe, or the Brass 
 Meridian. The brass circle placed vertically 
 around an artificial globe from pole to pole. 
 It is graduated into four quadrants of 90*^ 
 each, and is used by means of this graduation 
 to ascertain the latitude of places. It also 
 acts as a universal meridian, to which if any 
 place be brought, its longitude may be known 
 by the degree of the equator, which may 
 come at the same time under the brass circle. 
 
 Meridian, Magnetic. (See Magnetic.) 
 
 Meridian Line, or North and South 
 Line, is a line drawn upon a flat surface, 
 such as the ground, so that it may be due 
 north and south. An upright object, there- 
 fore, placed on the line will, at exactly 
 12 o'clock each day throughout the year, 
 supposing the sun to shine, cast a shadow 
 exactly along the meridian line. On a dial 
 it is of course the line that points to noon. 
 
 Meridian, or Meridinal Distance. 
 The same as difference of longitude or dis- 
 tance between the meridians of two places. 
 
 Meros. The plane face between the chan- 
 nels of the triglyphs of the Doric order. 
 
 Mesolarb. An ancient instrument for 
 finding two proportionals between two given 
 numbers. 
 
ME 
 
 ME 
 
 Metagalltc Acid. An acid produced by 
 heating the gallic acid in a retort, at a tem- 
 perature not exceeding 410° or 420°. It is 
 black, shining, tasteless, insoluble in water, 
 but soluble in liquid ammonia, potass, and 
 soda. 
 
 Metal, Fusible. (See Fusible Alloy.) 
 
 Metallic Thermometer. S3'nonymous 
 with pyrometer, (which see.) 
 
 Metallization. A changing into metal, 
 a term particularly applied to ammonia when 
 combined with mercury by electrical in- 
 fluence. When mercury is negatively elec- 
 trified in a solution of ammonia, or when an 
 amalgam of potassium and mercury is placed 
 upon moistened muriate of ammonia, the 
 metal increases in volumn, and becomes of 
 the consistency of butter, an appearance 
 whirh has been called the metallization of 
 ammonia. 
 
 Metalloids. A name given by Berzelius 
 to certain simple substances. They are sul- 
 phur, phosphorus, carbon, boron, and sili- 
 con. The metaUic bases of potassium, so- 
 dium, and the other alkalis and earths, have 
 been by some also called metalloids. 
 
 Metallurgy. The art of extracting me- 
 tads from their ores. 
 
 Metals. By far the most numerous class 
 of undecompounded bodies in chemical ar- 
 rangements. They amount to 42, all more 
 or less remarkable for a peculiar lustre, called 
 the metallic. They are excellent conductors 
 df heat, and most of them of electricity. 
 All combine with oxygen, but with affinities 
 and in quantities extremely different ; some 
 of them becoming alkaline, others acid. 
 Combining with each other they constitute 
 alloys, or when mercury is one of the metals 
 employed, the jcompound is an amalgam. 
 They unite also with some of the other sim- 
 ple bodies, forming sulphurets, hydrurets, 
 phosphurets, &c. ; and are soluble in nume- 
 rous acids, constituting a class of salts of 
 various properties, but mostly existing in a 
 crystalline frame. 
 
 Metameconic Acid. An acid procurable 
 by boiling the meconic acid. It is this latter 
 acid deprived of part of the carbon which it 
 -contains, that being dissipated by the heat. 
 Its salts are metameconates. They are of no 
 known use. 
 
 Metaphosphoric Acid. A term by 
 which some chemists designate the dry flaky 
 acid, obtained by burning phosphorus under 
 a bell glass of air or oxygen. 
 
 Meteor. A term applied by some authors 
 to denote all the various phenomena of the 
 atmosphere, while others apply it exclusively 
 to denote those luminous bodies which appear 
 at a considerable height above the earth. 
 They sometimes proceed in this hemisphere 
 from north to south with vast velocity, fre- 
 quently breaking into several smaller ones. 
 
 sometimes vanishing with a report, sometimes 
 not. Considering meteor in its extended 
 sense, as including all atmospheric transitoi^ 
 phenomena, it is necessary to divide them into 
 classes, according to their origin or nature. 
 Thus winds, whirlwinds, &c., are aerial me- 
 teors ; dews, fogs, rain, snow, and other de- 
 positions or disturbances of the water of the 
 atmosphere, are called aqueous meteors. 
 Many arise from the refraction or reflection 
 of light from the aqueous particles auspended 
 in the air — these are called hcminous meteors, 
 such are halo, mirage, rainbow, &c. While 
 those that present the appearance and phe- 
 nomena of combustion are igneous meteors, 
 such are falling stars, lightning, the aurora 
 borealis, &c. 
 
 Meteoric Stones. Meteorites. (See 
 Uroliths.) 
 
 Meteorology. Tlie science which treats 
 of meteors, the state of the weather, &c. 
 
 Methyline. a peculiar liquid compound 
 of carbon and hydrogen, extracted from py- 
 roxilic spirit, which is reckoned to be a bi- 
 hydrate of methylene. 
 
 Metonic Cycle. A cycle of 19 years, 
 at the end of which time the new moon 
 occurs on the same days of the year, and 
 the eclipses return in nearly the same order. 
 The reason of this is, that in 19 solar years 
 there are 235 lunations ; and very nearly one 
 complete revolution of the moon's nodes. 
 
 Metope. The space between the triglyphs 
 on the Doric frieze, ofteii ornamented with 
 sculpture. 
 
 Metre. The French standard measure 
 of length, equivalent to 39*37 1, or very 
 nearly 39f English inches. 
 
 Metronome. An instrument for mea- 
 suring time in music. It is contrived on the 
 principle of a clock having a short pendu- 
 lum, whose bob being moveable up and 
 down on the rod, is thus capable of increasing 
 or decreasing the length of a note or bar, as 
 indicated by the character of the music. 
 The stem or pendulum rod is marked with 
 all the same characters that indicate musical 
 time, so that the instiument may be set as 
 required. 
 
 Mezzotinto. a particular mode of en- 
 graving on copper. The sheet of copper is 
 first scratched over and over in every direc- 
 tion, with an instrument made for the pur- 
 
MI 
 
 MI 
 
 pose, till the face of it be wholly covered 
 with lines or scratches, so close to each other, 
 4|iat if an impression were taken from it, it 
 would be one uniform blot or smut. This 
 being done, the design is marked on it ; 
 after which the engraver proceeds with bur- 
 nishers, scrapers, &c., to take out the fur- 
 rows in those places where the lights are to 
 be, leaving more or less black those parts 
 that are to remain in shadow. It is the most 
 expeditious mode of engraving. 
 
 Miasmata. Vapours or effluvia, which, by 
 their application to the human system, are 
 capable of exciting various diseases. Some 
 miasmata are generated in the human body, 
 and being given off by it, and intercepted by 
 a second human body, propagate those dis- 
 orders known as infectious, such as plague, 
 typhus fever, &c. Other miasmata arise 
 from marshes, decaying vegetable matter, 
 &c., occasioning various intermittent and 
 other fevers. These latter act at a much 
 greater distance than the former kind. 
 
 Mica. A transparent mineral, mostly of a 
 greyish color, which under the name of talc, 
 or Muscovy glass, is used for the panes of win- 
 dows ; the fronts of some furnaces ; the top of 
 the mariner's compass ; and more especially, 
 when split into exceedingly thin slices, instead 
 of glass, for mounting microscopic objects. 
 
 MicROCOSMic Salt. A salt extracted 
 from human urine. It is a phosphate of soda 
 and ammonia. It may be prepared otherwise 
 by mixing together solutions of equal pro- 
 portions of these salts, and evaporating so as 
 to crystallize the salt. 
 
 Micrometer, is an instrument fitted to 
 telescopes, microscopes, &c,, in the focus of 
 the object glass, for measuring small angles 
 or distances, as the apparent diameters of a 
 planet, part of an insect, vegetable fibre, &c. 
 Several forms have been given to the micro- 
 meter. A piece of glass, covered with fine 
 wire, spider's web, &c., so that the fibres 
 shall intersect each other at exact and 
 previously determined distances, forms one 
 of the simplest micrometers. Another kind, 
 called the wire micrometer, is that which is 
 usually appended to telescopes. It is formed 
 as follows : — A A is a brass box, seen as if 
 cut in two, longitudinally. H H are two 
 micrometer screws, which move the forks 
 or staples I and N backwards and forwards, 
 one sliding evenly within the other. Across 
 the forks are tWo fine wires C and E, the 
 inner fork having a cut along it to allow the 
 wire of the other to pass ; this being placed 
 in a hole cut in the eye tube of a telescope, 
 exactly in the focus of the lenses, the screws 
 are to be turned until the wires exactly 
 embrace the diameter of the object to be 
 measured. To ascertain this apparent dia- 
 meter, multiply the size of the thread of the 
 screw by the number of turns requisite to 
 
 bring the wires to touch each other : the 
 product will be the distance of the wires, 
 and consequently the measurement required. 
 Other micrometers are described under the 
 words Brewster and Hcrscfiel. 
 
 
 
 A 
 
 
 
 
 
 ^w 
 
 — - 
 
 
 
 "Til 
 
 B 
 
 f5 
 
 
 c 
 
 J 
 
 * 
 
 \ 
 
 Micrgmetric AL Eye-Piece. (See JKams- 
 den.) 
 
 Micrometer-Pyrometer. (See Smea- 
 ton.) 
 
 Micrometer Screw. A fine screw, with 
 a large head, attached to various parts of 
 philosophical instruments and delicate ma- 
 chinery, for the purpose of marking very 
 minute differences of length or distance. Its 
 usual construction will be understood by 
 what follows : — 
 
 A B is a very fine screw, perhaps of fifty 
 threads to the inch. It is supposed to pass 
 through a screwed socket at E, which socket 
 is capable of motion backwards and forwards 
 along a groove beneath. The screw at tha 
 end A abuts on a projecting piece, where it 
 is fastened, so that it can turn round, but 
 not draw out. The end B is furnished with 
 a large head, the margin of which is divided 
 into ten or more equal parts. A fixed stud 
 D is fastened to the frame below. Suppose 
 a screw of this description be attached to 
 the reflecting lens of a Newtonian telescope. 
 It may be adjusted with great accuracy and 
 facility. Turning the head wholly round 
 with the thread of the screw such as we 
 have supposed, it would move the socket E, 
 and with it the lens attached, the fiftieth of 
 an inch, but turning the head a tenth part 
 only, moves it but the five hundredth of the 
 same measure. A screw of this kind without 
 the margin graduated is called a tangent 
 screw. Were E fixed, the screw would move 
 A backwards in like maimer. 
 
 Microscope. An optical instrument for 
 viewing small objects, rendering those visible 
 which cannot be distinguished by the naked 
 eye, and magnifying those that can. The 
 form of microscopes is very numerous, but 
 they may all be included in two distinct 
 classes; namely, single miscroscopes, and 
 
MI 
 
 MI 
 
 compound microscopes; the latter, either 
 reflecting or refracting. A single or simple 
 microscope, is that which consists of a single 
 lens or spherical globule, fitted-up so that 
 it may be conveniently held to the eye, the 
 object being at the focus of the lens. A 
 common hollow globe of glass, an inch in 
 diameter, and filled with water, is of itself a 
 single microscope ; so would be a drop of 
 water placed upon a hole drilled in a thin 
 piece of brass. The following is a frequent 
 and convenient form of this instrument : — 
 A is a piece of thick brass, with a channel 
 cut along it, to enable B with the objects 
 attached to slide towards or away from the 
 lens. C is a pair of nippers to hold the 
 object. D is a brass socket and screw hold- 
 ing the glass, (magnifying or double convex 
 lens.) E the handle to hold the instrument 
 by. There is often in the socket D two 
 lenses, one at each side. These being com- 
 bined and acting only as a single lens, 
 without requiring focal adjustment with each 
 other, or complexity in the instrument, it 
 still retains the character of single. 
 
 The compound microscope is very varied 
 in its form. One of the most convenient is 
 called the pillar microscope. It does not, 
 like some others, require to be looked down 
 into, but may be turned by the screw at the 
 top of its pillar into any position convenient 
 for the eye of the observer. A is the body 
 of the instrument containing the lenses. B 
 is the stand, which has three feet, folding 
 under each other, when the instrument is 
 not in use. C is a square socket, moving 
 up and down by the joint on the top of the 
 pillar. D E is a square bar of brass sliding 
 along through the socket C. At the end 
 D is a cross arm supporting the body 
 A. At G is a second socket moving alon^ 
 D E to support the object holder and appa- 
 ratus, the position of which is adjusted by 
 
 the thumb screw at G. I is the reflector. 
 F is the object holder, shown with a slider of 
 objects within it. H is a second reflector, to 
 be taken off or put on, as required. This is 
 used when opaque objects are to be esamined. 
 
 The lenses requisite to the instrument are 
 shown beneath. The light from the object A 
 is thrown upon a small double convex lens 
 B. By this the rays are converged, and 
 form a magnified image of the object at C. 
 The rays of light still passing forward, strike 
 the second lens D, where they are converged 
 a second time, and consequently increase the 
 magnitude of the image still more, previously 
 to its entering the eye at E. The eye seeing 
 the imaffe of the object and not the object 
 itself, as in the former instance, constitutes 
 this a compound microscope. For other 
 microscopes, or parts of them, (see Culpepper, 
 Gould, Opaque Cups, Test Objects, ^e.) 
 
 Microscopic Objects, are those which 
 are too small to be distinctly seen by the 
 naked eye. The most interesting micro- 
 scopic objects are the sections of wood, the 
 various parts of insects, the infusorise, the 
 pollen, stomatse, and vessels of plants; the 
 crystals of salts, hairs of animals, scales of 
 fish, slices of fossils, &c. 
 
 Microscopic Objects, Machine for 
 Cutting of. Those microscopic objects which 
 consist of the cuttings of woods and similar 
 objects, require an instrument for the purpose 
 of cutting them. The following is one which 
 is at the same time convenient and efl&caj?/ 
 cious : — A represents a solid table of brass, 
 
 ^ 
 
 ^THmU^^ 
 
 JJ^ 
 
 (ThJL , 
 
MI 
 
 MI 
 
 about 6 inches long, 4 wide, and a quarter 
 of an inch deep, with a guide or stay-piece 
 rising above the general su.rface at the back 
 edge B. C is a hole through A, fitted with 
 a short cylindrical socket, that extends below 
 the Under surface of A : it is close at the 
 bottom, except that the screw passes through 
 it. The head of this screw is made by a 
 toothed wheel E, containing 10 teeth, while 
 the screw itself contains 30 threads to the 
 inch. The use of the screw is to move 
 up or down a brass cylinder, with a square 
 hole in it; the top of this is seen at D. The 
 wheel E is kept in its place by the spring F. 1 1 
 is a three sided brass frame, which has a sharp 
 razor blade across it at J. K is the wooden 
 stand to the whole. When used, the wood 
 to be cut is fixed tightly into the square hole 
 D ; the socket put into its place, and ad- 
 justed by the screw below. The knife being 
 then pushed forward will cut off a slice of 
 wood : upon turning the wheel one tooth, 
 and again moving the knife, a second slice 
 will be obtained, and so on. These sections, 
 if good, should float in spirits of wine. 
 
 Microscopic Objects, Mounting of. 
 Transparent objects for the microscope may 
 be fastened upon strips of glass, by means of 
 Canada balsam, warming the glass previously 
 to its application. This will render objects 
 extremely transparent and beautiful. Ordi- 
 nary objects may be placed loose between 
 two circular pieces of talc, cut very thin and 
 punched to a proper form and size. They 
 are then put into shallow holes cut in a piece 
 of ivory, and retained in their places by a 
 ring of wire ; the holes have a very slight 
 shoulder left to them to prevent the talc 
 falling out on the other side. 
 
 Opaque objects, such as small portions of 
 minerals, are placed upon a round piece of 
 thin soft leather, punched out in circles 
 of about f of an inch diameter, the leather 
 being previously covered with paper. A pin 
 run through the leather holds the object 
 conveniently. 
 
 Middle Latitude. (See Latitude.) 
 
 Middle Latitude Sailing. (SeeZa^t- 
 tude.) 
 
 Middle Post of a Roof. Synonymous 
 with king post. (See Roof.) 
 
 Middle Quarters, or Columns. When 
 the plan or horizontal section of a column 
 is divided into four quadrants, by lines not 
 at right angles to the front, but at an angle 
 of 45°, the four quarters are called the 
 middle quarters. 
 
 Mid-Heaven. The highest point of the 
 heavens, reckoning from one side of the 
 horizon to the other ; called also the nona- 
 gesimal, or 90th degree. 
 
 Mile. A measure of length, consisting of 
 1760 yards. It is the same measure as was 
 used in this country by the Romans. The 
 Scotch and Irish miles are longer by about 
 one-quarter. A sea mile is the 60th part 
 of a degree, or 2027^ yards. The miles 
 of various countries differ very materially. 
 
 Milk. A well-known, nutritious, white 
 fluid, secreted in the mammillary glands of 
 female animals, and intended to nourish 
 their offspring while yet too young to take 
 solid food. 
 
 Milk, Sugar of. When the whey of milk 
 is evaporated, it deposits a sweet crystallised 
 substance, called the sugar of milk. 
 
 Milk or Lime. (See Lime.) 
 
 Milk of Sulphur. Sulphur deposited 
 from its alkaline solutions by an acid. It is 
 in the form of a yellowish, grey, impalpable 
 powder. 
 
 Milky Way, Galaxy, or Via Lactea. 
 A broad and irregular zone of stars that 
 surrounds the heavens, so distant that their 
 united light gives but an indistinct and un- 
 defined whiteness to the whole appearance^ 
 whence its name. 
 
 Mill. A machine employed in grinding 
 or pulverising any substance, aa that of 
 grain, whereby it is formed into flour, which 
 is usually accomplished by rubbing it be- 
 tween two harder bodies, consisting generally 
 of stone, and termed »zz7/-*/one* — the operation 
 of turning these stones being effected by 
 water, air, human or animal power, or ma- 
 chinery ; hence the terms water-mill, wind- 
 mill, hand-mill, horse-mill, S^c. Mills are 
 also distinguished by the purposes to which 
 they are applied, as bark mill, flour mill, oil 
 mill, cotton mill, saw mill, &c. ; from which 
 it will be evident that the term mill is applied 
 to a great variety of machines besides those 
 of grinding. Also all descriptions of wheel- 
 work at the present time are known by the 
 general name of mill-work, or mill gearing, 
 originating no doubt from the circumstance 
 of this being one of its first applications. 
 
 Mill, Barker's. (See Barker.) 
 
 Mill Gearing. The general arrange- 
 ment and formation of large wheel-work. 
 
MI 
 
 MI 
 
 Mill Head. The head of water which is 
 to turn a mill. 
 
 Mill Tail. The water which has passed 
 below or over the wheel of a water-mill. 
 
 Minaret. A small turret or tower attached 
 to ISIahomedan buildings, provided with one 
 or more external balconies, from which the 
 Mahomedans are called to prayers by the 
 voices of the priests. 
 
 MiNDERERUs's Spirit. A solution of 
 acetate of ammonia ; obtained by saturating 
 distilled vinegar with the carbonate of am- 
 monia. 
 
 Mine. A term applied, generally, to 
 underground works or excavations, when 
 made for the purpose of obtaining metallic 
 ores and other minerals. The approach to 
 a mine, if perpendicular like a well, is 
 called a shaft ; if horizontal, an adit. Coals 
 and salt are found in beds ; metals in veins, 
 called lodes or courses, and only found in 
 primitive rocks ; they usually run from east 
 to west. 
 
 Mineral. A general term, including all 
 inorganic substances, or those that constitute 
 the earth itself ; such therefore are earths, 
 stones, metals, sulphur, and similar bodies, 
 in all their varieties of combination, as well 
 as in an uncombined condition. 
 
 Mineral Adipocere. A greasy bitu- 
 men found in the argillaceous ores of iron. 
 
 Mineral Alkali. Soda. 
 
 Mineral Analysis. That part of che- 
 mistry which explains and ascertains the 
 composition of mineral substances. 
 
 Mineral Caoutchouc. The elastic bi- 
 tumen found at Castleton, in Derbyshire. 
 
 Mineral Cam^leon. (See Cameleon.) 
 
 Mineral Charcoal. Coal, peat, or 
 other mineral, having had its gaseous particles 
 driven off by partial burning or scorching, 
 and left in the state of coke. 
 
 Mineral Green. Carbonate of copper, 
 obtained by precipitating a hot solution of 
 sulphate of copper by carbonate of soda. 
 
 Mineral Pitch, Maltha. A solid bi- 
 tumen, otherwise called asphaltum, (which 
 see.) 
 
 Mineral Tallow. A white, bituminous, 
 and greasy substance, of the consistence of 
 tallow. It is very rare, but has been found 
 in Finland, and in the rocky parts of Persia. 
 
 Mineral Tar. The same as petroleum ; 
 a brownish black, oily, bituminous fluid, 
 •which is found in the earth, and dropping 
 from rocks in many parts of Europe and 
 Asia ; also in the West Indies, whence it is 
 called Barbadoes tar. 
 
 Mineral Waters. This term is applied 
 to certain spring waters, containing so large 
 a proportion of foreign matter as to be unfit 
 for ordinary use. The principal mineral 
 springs of England are those of Harrowgate, 
 and one at Cheltenham, containing sulphur ; 
 
 another at Cheltenham ; one at Bristol, 
 Buxton, Bath, Scarborough; and two at 
 Leamington, containing different saline sub- 
 stances ; and those of Tunbridge, Brighton, 
 and a third at Cheltenham, containing iron, 
 and called chalybeate waters. The mineral 
 waters of Germany are numerous, and much 
 celebrated. 
 
 Mineral Yellow, or Patent Yellow. A 
 compound of oxyde and chloride of lead ; 
 obtained by digesting powdered litharge in a 
 solution of common salt — washing, drying, 
 and fushig the product. It is used as a 
 pigment. 
 
 Minrralisers. The substances with 
 which metals are combined in their ores. 
 Thus, in the native oxydes, oxygen is called 
 the mineraliser. Sulphur is also a common 
 mineraliser, as in the ores of copper, lead, 
 &c. 
 
 Mineralogy. That science which teaches 
 the properties, composition, and relations of 
 mineral bodies, and the art of distinguishing 
 and describing them. 
 
 Miner's Friend, or Miner's Lamp. 
 A name which has been given to Davy's 
 lamp, ensuring as it does comparative safety 
 to the miner from the effects of fire damp, 
 or the explosion of carburetted hydrogen. 
 
 Miniature. A representation of nature 
 on a very small scale. Hence the term minia- 
 ture painting, which is usually performed on 
 ivoiy or fine card board. The outline being 
 drawn with great delicacy, and the colors 
 used being mixed and tempered with water ; 
 a little gum to add brilliancy to the finishing 
 coats, and a minute quantity of ox gall, to 
 take off the greasiness of the ivory, being 
 frequently added. 
 
 Minim. The smallest liquid measure, 
 equal to about a drop. An ounce of liquid 
 contains 480 minims. 
 
 Minion. The name of a type. (See Type.) 
 Also an iron ore, which mixed with lime and 
 water makes a water cement. 
 
 Minium. Red oxyde of lead, commonly 
 called red lead. 
 
 Minimum. The reverse of maximum, 
 (which see.) 
 
 Minus Electricity. (See Franklin's 
 Hypothesis.) 
 
 Minute. The measure of a sixtieth part 
 of any thing, as the sixtieth part of a degree, 
 of an hour, or of a module. 
 
 MiNUTi^. The minute parts, ornaments, 
 or details of any thing. 
 
 Mirage, Looming, or Fata Morgana. 
 An aerial phenomenon, occasionally seen in 
 particular states of the atmosphere, in which 
 ships, coasts, mountains, &c., appear as if 
 suspended in the air, as is represented in the 
 following cut, illustrative of a mirage seen 
 by Captain Scoresby in the Greenland seas. 
 He saw the appearance of about 18 or 19 
 
Ml 
 
 MO 
 
 sail of ships at the distance of from 10 to 
 15 miles. As he viewed them from the mast 
 head, they seemed to change their form — one 
 was drawn out or elongated in a vertical 
 plane ; another was contracted in the same 
 direction. One had an inverted image im- 
 mediately above it, as at A and B ; and two 
 had two distinct inverted images in the air, 
 as at C. Along with these images there ap- 
 peared distinct images of masses of ice in two 
 strata, the highest of which had an altitude 
 of about 15'. 
 
 Mirror. A speculum or polished body, 
 which exhibits the images of objects by re- 
 flection. They may be made of glass, covered 
 on one side with a reflective metallic sub- 
 stance, like the common looking glasses ; or 
 else made wholly of metal and highly polished. 
 Mirrors are either plane, convex, or concave ; 
 these latter are also called burning mirrors. 
 They may of course be of any other form, 
 if required ; as for example that of a cylinder 
 or cone. 
 
 MispiCKLE. Common arsenical pyrites. 
 
 Mitchells. Among builders are Purbeck 
 stones, from 15 inches square to 2 feet, 
 squared and hewn ready for building. 
 
 Mitchell's Method of Making Mag- 
 nets, or the Method of Double Touch. 
 Arrange on a flat surface, two, three, or more 
 steel bars, to be magnetized. Then take 
 two bundles of strong magnets, parallel to 
 each other, but with the poles of one parcel 
 reversed to those of the other. Then holding 
 these parcels of magnets at a short distance 
 from each other, as represented, rub them 
 several times along the bars from end to end, 
 when they will become strongly magnetic. 
 
 Mitre. A line cut straight across an an< 
 gle, where two solids meet. 
 
 Mitre Drains, or Cross Mitrb 
 Drains. The drains laid under the surface 
 of roads to convey the water to the side drains. 
 They are usually placed 60 feet apart, and 
 filled up loosely with flints. 
 
 Mixed Angle. (See Angle.) 
 
 Mixed Figure. One that is composed 
 of straight lines and curves, and yet not a 
 regular geometrical figure. 
 
 Mocho Stone, or Moss Agate. A si- 
 licious mineral, often cut for brooches, rings, 
 &c., and deriving its beauty from a moss- 
 like branched form being imbedded in its 
 transparent substance. 
 
 Model. An original or pattern, proposed 
 for any one to copy or imitate. Sometimes 
 reference is made to another already-con- 
 structed object ; thus we say, that St. Paul's 
 Cathedral was built after the model of St. 
 Peter's, at Rome. At other times, and more 
 frequently, it designates a miniature repre- 
 sentation of a building, a statue, carving, ship, 
 &c., made of wood, plaster of Paris, clay, 
 wax, or other plastic material, and intended 
 to convey an idea of the effect which will be 
 produced when the thing itself is built or 
 fashioned of the requisite size. Model in the 
 fine arts signifies generally any thing to be 
 imitated, whether larger or smaller than the 
 proposed copy. Thus, the living figures 
 which the students of an academy of painting 
 imitate in their sketches are called models, 
 and thus we speak of the works of the great 
 painters being models of perfection, &c. 
 
 Modelling. The art of forming models 
 of any kind. 
 
 MoDiLLioN. Consoles or brackets, placed 
 under the cornice of buildings. In the Co- 
 rinthian they are always carved ; in the other 
 orders more simple, some of them must al- 
 ways correspond to the middle of a column. 
 
 Mitre Box. A trough for cutting mitres, 
 having three sides open at the ends. 
 
 Module. In architecture by module is 
 meant any extent taken at pleasure, to mea- 
 sure the parts of a building by, and is usually 
 
MO 
 
 MO 
 
 determined by the lower diameter of the co- 
 lumn, one half of which is a module. It is 
 divided in 30 parts or minutes. 
 
 Mohair. The hair of the goat of Angora, 
 famous for its whiteness and silky softness. 
 It is manufactured into camlets and expensive 
 stuffs, shawls, &c. Little has hitherto been 
 imported into England. 
 
 MOIKRE METALLiaUB, Or CRYSTAL- 
 LIZED Tin. a crystal -like appearance given 
 to tin plate or to the surface of tin foil, 
 when a dilute acid is passed with a sponge or 
 brush over it, and immediately afterwards 
 washed. It is colored with various colored 
 transparent varnishes. 
 
 Mole. The same as breakwater ; that is, 
 a rampart of stone, wood, gravel, &c., thrown 
 up and projecting into the sea, for the pur- 
 pose of breaking its force, and thus rendering 
 a harbour or roadstead more secure from the 
 effect of storms and boisterous waves. 
 
 Molecule. Denotes one of the minute 
 particles of which any mass or body is com- 
 posed. Molecules differ from atoms in this, 
 that they are never considered but as portions 
 of some aggregate. Atoms may be imagined 
 to exist alone. 
 
 Molybdenum. A peculiar metal, which is 
 white, brittle, very infusible, and of a specific 
 gravity, about 8*6. With oxygen, it forms 
 two oxydes and an acid. 
 
 MoLYBDic Acid. Composed of 1 atom 
 of molybdenum and 3 of oxygen. Its com- 
 pounds are called molybdates. 
 
 Molybdous Acid. A composition of 
 oxygen, 2 atoms, and molybdenum, 1. It is 
 procured by boiling metallic molybdenum 
 and molybdic acid together. 
 
 Moment. An indefinitely small portion 
 of time, having the same relation to duration 
 as a point has to a line. 
 
 Momentum. A force possessed by matter 
 in motion. A steam carriage detached from 
 the engine continues to move for some time 
 by its momentum or the force which its 
 mass of matter has accumulated.- The power 
 or quantity of momentum is reckoned by the 
 velocity of its motion. 
 
 Monkey. A weight or mass of iron let 
 fall from a height to drive piles into the earth. 
 
 Monochromatic Light. A light con- 
 sisting of one color only ; for example, bum 
 in a dish a mixture of common salt and spi- 
 rits of wine. The flame wiU be so entirely 
 of a yellow color, that the objects around 
 will not be seen in their natural tints, but 
 yellow, like that of the light. 
 
 Monochrome. A painting of a single 
 color. This art is often practised among ar- 
 tists, as sketches, either in Indian ink or se- 
 pia. It was much in vogue among the an- 
 cients, particularly the Etruscans. The terra 
 cotta vases of this people still remaining 
 show the extent to which it was carried. 
 
 MoNOLiTHAL. Works constructed of a 
 single stone. 
 
 Monomial. In algebra, is a quantity con- 
 sisting of only one term, as ax, 2txy, &c. 
 
 MONOPTERON, OR MONOPTERAL TeM- 
 
 PLE. An edifice consisting of a circular co- 
 lonnade, supporting a dome, without any 
 inclosing wall, and consequently without the 
 cell that there is in other temples. 
 
 Monotriglyph. a Doric entablature, in 
 which there is only one triglyph between two 
 adjoining columns. This is the usual prac- 
 tice in the Grecian Doric, as in the Parthenon, 
 or Temple of Minerva, at Athens. 
 
 Monsoons. The name given to certain 
 disturbances of the regular course of the 
 trade winds, which take place in the Arabian 
 and Indian seas. Between the parallels ot 
 latitudes of 10° and 30° south, the eastern 
 trade wind blows regularly, but from the 
 former parallel northwards, the course is re- 
 versed for half the year, and from April to 
 October the wind blows constantly from the 
 south-west ; during the rest of the year the 
 regular north-east trade wind prevails. The 
 S.W. monsoon is supposed to be occasioned 
 by the great rarefaction of the atmosphere 
 over the extensive regions of Eastern Asia 
 during the summer months. 
 
 Montgolfier, or Fire Balloon. A 
 name given to those balloons which receive 
 their buoyancy from the burning of combus- 
 tible materials, being thus denominated after 
 the name of their inventor. Their cause of 
 buoyancy distinguishes them from the air or 
 gas balloons. 
 
 Month. The twelfth part of the year, and 
 so called from the moon, by whose motions 
 it was regulated, being properly the time in 
 which the moon runs through the zodiac, or 
 passes round the earth. A lunar month is 
 the time from one new moon to another, or 
 29 days, 12 h., 44 m., 3 s. A solar month 
 is the time in which the sun rims through 
 one entire sign of the zodiac, the mean quan- 
 tity of which is 30 days, 10 h., 29 m., 5 s. 
 A civily calendar, or common month, is an 
 interval of a certain number of whole days, 
 approaching nearly to the quantity of a solar 
 month. 
 
MO 
 
 MO 
 
 Monument. A structure raised to pre- 
 serve the memory of some eminent person, 
 or to perpetuate some remarkable event. 
 
 Moon. One of the heavenly bodies ; the 
 constant attendant of our earth, about which 
 she revolves as a centre, illuminating us by 
 her reflected rays in the absence of the sun. 
 Her sidereal revolution isin27d., 7h.,43m. 
 Her synodical revolution in 29 days, 12 h., 
 44 m., 3 s. Her mean distance from the 
 earth about 237,000 miles. Her velocity 
 varies in different parts of her orbit ; she 
 moves swiftest when nearest the earth, and 
 slowest when at the contrary point. The 
 rotation on her axis is uniform, and is per- 
 formed in the same time as her revolution in 
 her orbit, whence she always presents nearly 
 the same face to the earth. Her figure is an 
 oblate spheroid, like that of the earth. Her 
 mean diameter being about 2160 miles, con- 
 sequently her volumn is about a fiftieth part 
 that of our planet. Her atmosphere, if any, 
 must be extremely attenuated, and looking 
 at h€r with a telescope we find her surface 
 greatly diversified, being covered with bright 
 spots and lines at one part, and with dark 
 shadows at another. Several planets, besides 
 our earth, are attended by moons — Jupiter 
 has four ; Saturn seven ; and Herschel six. 
 
 Moon, Harvest. (See Harvest Moon.) 
 
 Moon, Phases of. The different Jhces or 
 appearances which the moon presenfes^ us 
 in her monthly rotation around thc^rth, 
 are called her phases, and have distinctive 
 names, according to the quantity of the 
 surface of the moon which is at that time 
 visible. The following cut will at once show 
 and explain this. The sun is supposed at an 
 immense distance, sideways of the cut. He 
 would, in that position, illuminate the half 
 of the moon nearest to himself, whatever 
 position the moon might be in with reference 
 to the earth, (except she be exactly behind 
 it, as in the time of an eclipse,) this is seen 
 in the outer circle of the cut ; but that 
 illuminated side will only be wholly visible 
 to the inhabitants of the earth at the time of 
 
 r 
 
 v 
 
 
 iXD 
 
 D 
 
 ••v<) 
 
 C 
 
 •€ 
 
 full moon, or full phased moon, as at E. 
 While in the position A, the illuminated side 
 is whtily turned from us, and consequently 
 the moon is invisible. We call it then new 
 moon. Three or four days after this a cres- 
 cent is seen, as at B. Seven days after new 
 moon, she enters her^r*^ quarter, when half 
 a circle is seen, as at C ; afterwards, more than 
 half a circle, when the moon is called gibbous, 
 as D. The same changes occur between full 
 and new moon in the other half of the month, 
 but in reverse order, or as in F, G, H. 
 
 Moon Dial. A dial that shows the hours 
 of the night by the light of the moon. 
 
 Moon's Age. The number of days since 
 the new moon. 
 
 Moon's Nodes. (See Node.) 
 
 Moor. An uncultivated siirface without 
 trees, and with but a scanty and coarse 
 herbage. 
 
 Moor-Stone. a whitish kind of granite, 
 found in Cornwall, Devonshire, Ireland, and 
 some other places. It is brought from the 
 former places in immense masses to London^ 
 where it is used for the steps of public build- 
 ings, curb -stones, and other purposes, where 
 great strength and hardness are required. 
 
 Mordant. In dyeing and calico printing, 
 denotes a body which, having a two-fold 
 attraction for organic fibres and coloring 
 matter, serves as a bond of union between 
 the*i, and thus gives durability to dyes ; or 
 it signifies a substance which by combining 
 with coloring particles in the pores of textile 
 filaments, renders them insoluble in hot, 
 soapy, and alkaline solutions. The principal 
 mordants are alumina or the earth of alum, 
 tin, and oxyde of iron. 
 
 Mordant Varnish. (See Gold Size.) 
 
 MoREsauE. (See Arabesque.) 
 
 Morocco. A goat-skin leather, prepared 
 chiefly in Morocco. It is used in the bind- 
 ing of books, &c. 
 
 MoROXYLic Acid. An acid discovered 
 by Klaproth in the bark of the white mul- 
 berry. 1% distinctness is much doubted, 
 even by its discoverer. Its compounds are 
 moroxylates. 
 
 Morphia. A vegetable alkali, extracted 
 from opium, of which it consitutee the nar- 
 cotic principle. It was first obtained pure 
 by M. Sertiirner, about the year 1817. 
 
 Mortar. A cement used for building 
 purposes, composed of lime, sharp coarse 
 sand, and sometimes the hair of animals, 
 all thoroughly mixed together with water, 
 so as to form a half fluid, half solid mass. 
 
 Mortar. A strong hollow instrument, 
 usually made of marble, Wedgewood ware, 
 or metal, in which hard or brittle substances 
 are pulverised by percussion or grinding 
 with another instrument, called a pestle. 
 Mortars usually partake of the shape of an 
 inverted bell or cup, but their form, capacity, 
 
MO 
 
 MO 
 
 and solidity, as well as the material of which 
 they are made, vary with the object for 
 which they are designed. 
 
 Mortar, Electrical, or Electrical Bomb. 
 A small apparatus, intended to show the me- 
 chanical effects of electricity, upon the same 
 principle as Kinnersley's air thermometer. 
 The bomb is of ivory, bone, or other non- 
 conducting substance ; a ball of light wood 
 fits a semi-circular cavity at the mouth of 
 the bomb, and a small chamber is made 
 beneath it. Two wires, (one at top, the 
 other leading to the stand beneath,) pass into 
 the cavity, and are there separated by a small 
 interval. When a shock is passed through 
 the wires, the air within the cavity is rarefied ; 
 its sudden expansion throwing out the ball. 
 
 Mortar, Hydraulic, or Roman Cement. 
 A cement which acquires but little solidity in 
 the air, but becomes extremely hard under 
 water. The poorer kinds of lime stone are 
 burnt, ground, mixed with water and sand, 
 and immediately applied to the work. 
 
 Mortice and Tenon. A description of 
 joint used in wood-work. The extremity of 
 one piece of timber is let into the face of 
 another piece ; a tongue being formed at the 
 end of the piece to be let in, which is called 
 a tenon, and the hole cut in the face of the 
 other is called a mortice. 
 
 MoRVEAu s Platina Pyrometer. The 
 base of this instrument is a small, yet solid 
 plate of highly-baked porcelain, in which is 
 a groove, capable of containing a flat bar of 
 platina. If inches in length, -Jg- of an inch 
 in width, and about half this in thickness. 
 One end of this rests or abuts against the 
 bottom of the groove ; the other presses 
 against the short arm of a bent lever. The 
 long arm of which, moving on a pivot, be- 
 comes the index of the instrument. The 
 short arm of this lever is exactly ^ of the 
 
 long arm, consequently the space it moVes 
 over will be twenty times as great as the ex- 
 pansion of the platinum, or rather as the space 
 passed over by the short arm. There is a 
 finely- divided scale also of platinum attached 
 to the instrument. 
 
 
 
 
 
 n 
 
 k 
 
 
 IliilliilliillilM 
 
 i 
 
 ■■■ 
 
 1 
 
 
 4 
 
 "^ 
 
 
 p 
 
 
 ^^^ 
 
 
 
 
 1 
 
 
 \^ 
 
 
 
 
 n 
 
 
 \w\ 
 
 
 
 
 M 
 
 
 \N^x 
 
 
 
 
 ^ 
 
 
 ^ 
 
 ^ 
 ^ 
 
 
 E 
 
 1 
 
 Mosaic Gold, or Or-molu. A pecu- 
 liar alloy, formed of equal quantities of cop- 
 per and zinc, melted together ; when in a 
 fused state, about a tenth part more zinc is 
 added to bring it to a proper color, and to 
 compensate for the zinc that may have flown 
 off in fumes. Mosaic gold, (the aurum mu- 
 sivum of the old chemists,) is a sulphuret 
 of tin. 
 
 Mosaic Work. Representation of ani- 
 mals, flowers, or other objects, formed of 
 small pieces of colored marble, glass, &c. 
 The finer kinds are used upon seals, and in 
 rings and brooches ; the larger for the deco- 
 rations of walls and the formation of pave- 
 ments. A common kind of mosaic pavement 
 is frequent on summer houses, on terraces, 
 and similar places, made of horses' teeth, 
 sheep's knuckle bones, shells, and small 
 stones, arranged in some fanciful manner. 
 (See Quarry, Pavement, and Tessellated.) 
 
 Mother of Pearl, is the hard, silvery, 
 brilliant internal layer of several kinds of 
 shells, particularly of the oyster tribe, which 
 is often variegated with changing purple and 
 azure colors. These brilliant hues do not 
 depend upon the nature of the substance, but 
 upon its structure. The microscopic wrinkles 
 or furrows which run along the surface of 
 every slice, act upon the reflected light iu 
 such a way as to produce this chromatic 
 effect. Mother of pearl is brittle and very 
 delicate to work, but it may be fashioned by 
 saws, files, and drills, with the aid sometimes 
 of a corrosive acid. It is polished by crocus, 
 the peroxyde of iron, putty powder, &c. 
 
 Mother Water. When sea water, or any 
 other solution containing various salts, is 
 evaporated, and the crystals taken out, there 
 always remains a fluid containing deliques-. 
 cent salts, arid other impurities. This ia 
 called mother water. 
 
MO 
 
 MU 
 
 Motion, or Local Motion. A con- 
 tinued and successive change of place, which 
 occurs with a body ; or, in some cases, the 
 parts of a body when acted upon by an ade- 
 quate force. Motion is of various kinds : — 
 Absolute motion is that which is independent 
 of any other motion, or friction, or retarding 
 power ; in which general sense, however, it 
 never falls under our own observation. All 
 those motions which we call absolute, are, 
 in fact, only relative, being referred to the 
 earth, which is itself in motion. For conveni- 
 ence, however, we consider a change of place 
 on the earth's surface, from some certain 
 point of starting, as an absolute motion. 
 Angular motion is the motion of a body, as 
 referred to a centre about which it revolves. 
 Tliis is the only case in which the parts of a 
 body are in motion, without the whole of it 
 being so. Accelerated and retarded motions 
 are those which are continually increasing or 
 diminishing in velocity, while equable motion 
 continues uniform. Compound motion is the 
 result of two or more distinct forces acting 
 together. Natural motion is that which 
 arises from the effect of gravitation, or of 
 the centrifugal force. Relative motion is the 
 alteration of place between two objects in 
 motion relatively to each other. A resultant 
 motion is that which results from the diffe- 
 rent power of two opposite forces ; thus, a 
 a steam engine may have a power of six 
 horses, but the friction of the various parts 
 may diminish this two horses ; thus, the re- 
 sultant force or motion will be four horses. 
 
 Motion, Laws of, are as follows, as de- 
 livered by Sir I. Newton: — First, every 
 body perseveres in its state of rest, or 
 uniform motion in a right line, until a change 
 is effected by the agency of some external 
 force. Second, any change effected in the 
 quiescence or motion of a body, is in the 
 direction of the force impressed, and is pro- 
 portional to it in quantity. Third, action 
 and re-action are equal and in contrary 
 directions. 
 
 Moveable Pulley. (See Pulley.) 
 
 Movement. The working part of a clock 
 or watch. 
 
 Moving Power. A force or energy, or 
 impulse, sufficiently powerful to produce 
 motion. It may be the wind, water, animal 
 force, steam, &c. 
 
 Mould. That in which any thing has 
 been or may be cast. According to the ma- 
 terial of which a mould is composed, or the 
 purpose to which it is applied, so is its name, 
 as a plaster, sulphur, wax, or sand mould ; 
 candle mould, bullet mould, &c. 
 
 Moulding. An ornamental line, either 
 projecting or depressed. In classical archi- 
 tecture, and for ordinary embellishment, the 
 following are the most common : — -A, astra- 
 gal or bead ; B, ogee ; C, cymatium ; D, 
 
 cavetto; E, scotia or casement ; F, apophy- 
 ges ; G, ovolo or quarter-round ; H, torus ; 
 this is larger than a bead, and differently 
 placed ; I, reeding ; J, band ; and last, the 
 fillet, which is a small square member that 
 generally accompanies the other mouldings. 
 (See the above terms.) 
 
 ^ 
 
 In Gothic work, mouldings are extremely 
 varied, some peculiar to a particular age or 
 style ; others, common to a long period. 
 See Chevron, Nail-head, Billet, Scollop, 
 Tooth, Trefoil, Quatrefbil, Roll, Ball 
 Flower, 8fc. The following shows a series 
 of plain mouldings, forming a Gothic 
 cornice : — 
 
 Mountain Blue. Malachite ; a carbo- 
 nate of copper. Used as a pigment. 
 
 Mountain Cork and Mountain Lea- 
 ther. (See Asbestos.) 
 
 Mountain Green. A carbonate of cop- 
 per. 
 
 Mountain Milk. A very spongy soft 
 variety of carbonate of lime. 
 
 Mountain Soap. A soft, pale, brownish 
 black kind of unctuous chalk, found in the 
 Isle of Skye ; used in crayon drawing. 
 
 Mountain, or Rock Wood. (See .4*- 
 bestos.) 
 
 MoYA. Mud poured out of volcanoes. 
 
 Mucic Acid. The same as saccholactic 
 acid. It may be obtained by digestmg one 
 part of gum arable or of sugar of milk, with 
 twice or thrice its weight of nitric acid. 
 
 Mucilage. An aqueous solution of gum. 
 
 Muffle. A small earthen oven, made of 
 crucible clay of the following form. It is to 
 be fixed in a furnace, and is useful for cu- 
 
MU 
 
 MU 
 
 pellation and other smelting processes which 
 demand access of air. 
 
 Mui.LER. A tool employed in pounding and 
 grinding substances upon a stone. The glass 
 grinders thus call the instruments used for 
 grinding their glasses, which consists of a 
 round piece of wood, about 6 inches long ; 
 to one end of which is cemented the glass to 
 be ground. For grinding colors, the muller 
 is of stone, and is usually employed upon a 
 flat slab of stone. 
 
 MuLLioNS. Upright stone divisions of a 
 window. 
 
 MuLLiNs's Voltaic Sustaining Bat- 
 tery. This useful instrument of research 
 has been frequently confounded with Daniel's 
 constant battery, but they are essentially 
 different ; the latter, though constant, not 
 sustaining or keeping up an equally powerful 
 current of electricity for any period required, 
 which perfection has been attained by the 
 former. Its mode of arrangement and ele- 
 ments of power also materially differ ; the zinc 
 surface being brought within three-eighths of 
 
 an inch of the copper in the sustaining bat- 
 tery, whereas in the constant battery the inter- 
 val between the metallic surfaces amounts to 
 an inch and half ; also, in MuUins's invention 
 no acids are used, which is the case in Da- 
 niel's. The accompanying diagram will explain 
 more fully the arrangement of the parts : — 
 A A is an earthenware pot. B B a cylinder 
 of zinc, not amalgamated, about half the 
 height of the pot. C C C a diaphragm of 
 wood, properly prepared. D D a cylinder 
 of copper, without a bottom. E shelf for 
 holding crystals of sulphate of copper, com- 
 municating with the external surface of the 
 copper cylinder, by small holes on a level 
 with the upper surface of the shelf. F wire 
 and binding screw connected with the zinc 
 cylinder. G the same, connected with the 
 copper. To charge this battery, take equal 
 parts of a saturated solution of ammonia and 
 soft water, and having first inserted the 
 wooden diaphragm, pour the mixture into 
 the pot, between the diaphragm and the zinc, 
 until it stands at three -fourths of the height 
 of the pot, and into the diaphragm pour a 
 a saturated solution of sulphate of copper, 
 until the solution rises to half an inch above 
 the level of the shelf E. It is to be observed, 
 that when the battery is not in use, the 
 wooden cylinder should be removed, and kept 
 in water in which some common salt has 
 been dissolved. For all purposes of electro- 
 type this battery possesses great advantages, 
 as from its equality of current there is a 
 more equal and firmer deposition of copper 
 or other metal than with any other form of 
 battery. 
 
 MuLLiNs's Volta-Electrometer. In 
 this useful invention a slip of platina foil is 
 wound round the elongated bvdb 
 of a thermometer, on the scale 
 of which the degrees are sub- 
 divided into fifths. The ends of 
 the foil are connected with binding 
 screws, which unite them to the 
 poles of the battery. The quan- 
 tity of electricity is ascertained 
 by the heat developed in the pla- 
 tina foil during the passage of 
 the current, as shown by the 
 thermometer. A A is a stand, 
 to which the thermometer is, 
 afl&xed. B the bulb of the ther- 
 mometer, with the foil rolled 
 round it. C the thermometer, 
 binding screws, connected with 
 and also with the battery. 
 
 Multinomial. In algebra, a quantity 
 consisting of more than three terms, as 
 X* + ax^ + a^x^ + a^x + a*. 
 
 Multinomial Theorem, is a general 
 expression or formula, for determining any 
 power or root of a given quantity consisting 
 of any number of terms. 
 
MU 
 
 MU 
 
 MuLTiroiL. A leaf ornament of more 
 than five divisions. 
 
 MuLTi ANGULAR. Having many angles. 
 Multilateral. Having many sides. 
 
 Multiple. In arithmetic, is a number 
 which contains another number a certain 
 number of times : thus, 18 is the multiple 
 of 6, or of 3, or of 9, &c. The common 
 multiple of two or more numbers is that 
 which contains them both a certain number 
 of times : thus, 36 is the common multiple 
 of 4 and 9, being equal to 9 times the first, 
 and 4 times the second. 
 
 Multiple Points. In analytical geome- 
 try, when two or more branches of a curve 
 pass through the same point it is called a 
 multiple point. 
 
 Multiplicand. (See Multiplication.) 
 
 Multiplication. One of the principal 
 rules in arithmetic and algebra ; and consists 
 in finding the amount of a given number or 
 quantity, called the multiplicand, when re- 
 peated a certain number of times expressed 
 by the multiplier ; and this amount is gene- 
 rally termed the product ; also the multiplier 
 and multiplicand are commonly termed fac- 
 tors. Multiplication is either simple or 
 compound; simple multiplication is when the 
 proposed quantities are integers or whole 
 numbers ; compound multipUcation implies 
 that one of them is a compound quantity ; 
 that is, one consisting of several denomina- 
 tions, as pounds, shillings, and pence. 
 
 Multiplication Table. A. small table, 
 containing the product of all the simple di- 
 gits and onwards up to 12 times 12, or oc- 
 casionally up to 24 times 24. Its use is to 
 facilitate operations in arithmetical multi- 
 plication. 
 
 Multiplier, or Multiplicator. The 
 number by which another is multiplied. 
 (See Multiplication.) 
 
 MuTiPLiER, Galvanic. (See Galvano- 
 meter.) 
 
 Multiplying Glass. A plano-convcac 
 lens ; the convex surface of which is cut into 
 numerous faces, each of which reflecting the 
 light differently gives the appearance of very 
 numerous objects, (such as candles or fires,) 
 being before it when it is looked through. 
 
 MuNDic. The name given by miners to 
 copper pyrites. 
 
 MuNNioNS. (See Mullions.) 
 
 Mural. Connected with a wall, as a mural 
 monument, a mural column, &c. 
 
 Mural Arch. A wall or walled arch, 
 placed exactly in the plane of the meridian, 
 for the fixing of a large quadrant, sextant, 
 or other instrument, to observe the meridian 
 altitude of the heavenly bodies. 
 
 Murdoch's Steam Engine. This is 
 upon the rotatory principle, and extremely 
 simple. A and B are two wheels, working 
 into each other, and turning in a box, to the 
 inner circumference of which the ends of the 
 wheels are made to move round steam-tight 
 by packings or stuffings. The axis of one or 
 both of the wheels passes through the sides of 
 the box, and is made steam tight in the 
 usual manner. Steam bemg admitted into 
 this box by the pipe or channel G, and a 
 vacuum being formed by the condenser H, 
 the steam acts upon the teeth of the wheels, 
 and causing them to turn round in contrary 
 directions, produces a rotatory motion, which 
 may be communicated by means of the axis 
 to other machines. 
 
 Muriates. Synonymous with chlorides, or 
 compounds of the hydrochloric acid with 
 sahfiable bases. 
 
 Muriatic Acid. (See Hydrochloric 
 Acid.) 
 
 Muriatic Acid Gas. Chlorine in a 
 gaseous state ; when combined with water it 
 becomes the muriatic or hydrochloric acid. 
 
 Muscovado Sugar. Synonymous with 
 the common brown, raw, imrefined sugar 
 of our shops. 
 
 Muscovy Glass. (See Mica.) 
 
NA 
 
 NA 
 
 Mtjsic AL, or Harmonic AL Proportion. 
 (See Harmonical.) 
 
 Musk. A strong perfume, obtained from 
 an animal of the same name. It is much 
 used in perfumery. 
 
 Muslin. A fine sort of cotton cloth, first 
 imported from India, but now mostly manu> 
 factured in this country. 
 
 Must. The juice of grapes, composed of 
 sugar, water, jelly, gluten, and bitartrate of 
 potass. New and unfermented wine, of 
 whatever fruit it may be made, is also called 
 must. 
 
 Myriad. The number 10,000. 
 
 Myricine. a vegetable principle, which 
 constitutes from 20 to 30 per cent, of bees' - 
 wax, being the residuum when alcohol is 
 poured on that substance. 
 
 MuTULE. A flat square block, placed on 
 the soffit of Doric cornices, answering to the 
 modillions of the Corinthian order, and to 
 corbels in the Gothic. Guttoe are most ge- 
 nerally cut on the under surface. 
 
 Myrrh. A gummy, resinous, concrete 
 juice, which issues by incision, and some- 
 times spontaneously, from the trunk and 
 large branches of a tree growing in Arabia 
 and Egypt. It consists of two-thirds resin 
 and one gum. 
 
 The fourteenth let- 
 ter, eleventh conso- 
 nant, and third liquid 
 of the English alpha- 
 bet. It has something 
 of a nasal sound, as 
 in finger f tinker, 8fc. , 
 and is pronounced 
 chiefly by the action 
 of the tongue against the lower gum, much 
 like the letter L. It readily unites with 
 other letters, as in send, rant, tongue, tank, 
 lynx, 8fc. In Latin and Greek, the N is 
 often omitted, as mesibus for mensibus. As 
 a numeral it signifies 90, or with the Greeks 
 it stood for 50. As an abbreviation it indi- 
 cates noster, as N. D., dominus noster; 
 also novus, nobilis, 8fc. In geometry and 
 astronomy it signifies north. 
 
 Nacre. A name given to mother of pearl. 
 Nadir. That point of the heavens which 
 is diametrically under our feet, as opposed 
 to the zenith, which is the point directly over 
 our head. The zenith and nadir are the 
 poles of the horizon. 
 
 Nail-Head. a peculiar Norman Gothic 
 ornament, which consists of the resemblance 
 of a series of square-headed nails, such as the 
 following : — 
 
 Nails. Small metallic spikes, used for 
 fastening the parts of woodiwork together, 
 and similar purposes. 
 
 Nairne's Electrical Machine. The 
 same as the cylinder machine, but with a 
 second prime-conductor attached to the 
 cushion for the collection of the negative 
 
 fluid. (See Cylinder MacTiine^ The earlier 
 of Nairne's machines were made without 
 this, and with the usual prime-conductor 
 placed at right angles to the cylinder. It 
 was of tin, and instead of wire points, had 
 them cut like teeth out of the edge of the tin 
 itself. 
 
 Naked. Uncovered ; the bare surface of 
 a wall, which serves as a ground for the pro- 
 jections. 
 
 Naked Flooring. The assemblage of 
 timbers or joists upon which flooring boards 
 are placed. 
 
 Nanceic Acid. A name given by Bra- 
 connot to the lactic acid. 
 
 Nankin. A peculiarly colored cotton 
 cloth, originally manufactured in the above 
 named ancient capital of China, from a native 
 I cotton of a brownish yellow hue. 
 
 Naos. The chamber or inclosed apartment 
 of a temple. 
 
 Naphtha, or Rock Oil. A transparent 
 yellowish or brownish fluid, of strong pene- 
 trating odour, greasy to the touch, and 
 so light as to float on alcohol. Near Baku, 
 on the borders of the Caspian Sea, are 
 fountains of it. The ground also at Pitch- 
 ford, in Shropshire, is saturated with it ; 
 but the principal source whence it is now 
 obtained is from the distillation of coal tar. 
 It is, chemically speaking, a hydro-carbon, 
 not containing any oxygen in its composition ; 
 thus, it is useful to keep in contact with po- 
 tassium, sodium, and other substances, which 
 would be decomposed by contact with the 
 air. Its chief employment, however, is for 
 lamps, in which it bums with a brilliant 
 light. 
 
 Naphthaline. A peculiar, white, crystal- 
 Usable substance, which may be extracted by 
 distillation from coal tar. It is a solid bi- 
 
NA 
 
 NE 
 
 carburet of hydrogen. It has not been ap- 
 plied to any use. 
 
 Napier's Bones, or Rods. A method 
 contrived by Lord Napier for the more 
 easily performing the arithmetical operations 
 of multiplication and division. These rods 
 are five in number ; made of bone, ivory, 
 wood, horn, or paste-board. Their faces 
 are divided into nine little squares, each of 
 which is parted into two triangles by a 
 diagonal. In these little squares are written 
 the numbers of the multiplication table in 
 such a manner as that the units or right 
 hand figures are found in the right hand 
 triangle ; and the tens, if any, in the left 
 hand triangle. One of the rods has only the 
 units upon it. The following cut shows the 
 five rods. The other sides of them are 
 covered with the rest of the multiplication 
 table in like manner, up to nine times in- 
 clusive, with one for the cypher. To multiply 
 numbers by Napier's bones, dispose the rods 
 in such a manner that the top figures may 
 represent the multiplicand ; to the left hand 
 place the rod of units ; in which seek the 
 right hand figure of the multiplier ; and the 
 numbers corresponding to it on the other 
 rods, write out, adding each two together as 
 you go on. Then proceed with another 
 figure of the multiplier in like manner, and 
 finally add together the several lines thus 
 found — as in common multiplication. The 
 rods in the following cut are arranged as if 
 the multiplicand were 2345 ; to multiply 
 this by 8, we shall have first to put down 
 the right hand figure in the line of 8, which 
 is ; then we shall have 4 and 2 added to- 
 gether, or 6 ; afterwards 3 and 4 added to- 
 gether, or 7 ; then 2 + 6, or 8, and finally 1, 
 which is in the other half of the first square, 
 and the whole product wiU be these numbers 
 collected together. 18760. 
 
 Naples Yellow. A yellow colored pig- 
 ment, prepared by calcining lead with 
 
 antimony and potash in a reverberatory 
 furnace. 
 
 Narceia. An alkaloid discovered to exist 
 in Turkey opium. 
 
 Narcotina. An alkaloid extracted from 
 opium. It may be obtained by dissolving 
 opium in warm ether ; as this cools, it will 
 deposit crystals of narcotina. 
 
 Native. In chemistry, mineralogy, &c., 
 signifies that which is naturally produced, ia 
 opposition to which is made artificially — as 
 the native carbonate of lime, native cinnabar, 
 native copper, &c. In the last case it im- 
 plies that the metal is in a metallic state, 
 and not in combination with sulphur, lime, 
 acids, &c., when it would constitute an ore, 
 and not be considered native. 
 
 Natrium. The name given by the Ger- 
 man chemists to sodium, the metallic base of 
 soda. 
 
 Natron. The native sesqui-carbonate of 
 soda. It is found in vast abundance in the 
 lakes near Alexandria, in Egypt. It is also 
 found in many parts of North America, Asia, 
 Europe, &c. 
 
 Natural Beds of a Stone, are the 
 surfaces from which laminse may be split. 
 For example, slates are split only in one 
 direction, which is in accordance with the 
 natural beds in which they are found. 
 
 Natural Magnet. (See Loadstone.) 
 
 Natural Philosophy, or Experi- 
 mental Philosophy, is that branch of 
 knowledge which explains the laws and facts 
 of physical nature by means of experiments. 
 As such, it is distinguished from moral or 
 ethical philosophy, which treats only of the 
 working of the mind and imagination. To 
 natural philosophy belong the sciences of 
 chemistry, meclianics, hydrostatics, hydrau- 
 lics, pneumatics, electricity in its various 
 branches, magnetism, astronomy, heat, op- 
 tics, &c. 
 
 Nave. The central division of a cathedral 
 church, extending from the west end to the 
 choir. 
 
 Nave. The central boss, or hul, as it is 
 in some places called, of a wheel through 
 Which the axletree passes, and which receives 
 the inner ends of the spokes. 
 
 Navigation. The art of sailing or con- 
 ducting a vessel on the ocean. 
 
 Navigators. The name given to men 
 employed on canals, railways, &c. 
 
 Nealing. (See Annealing.) 
 
 Neap Tides. (See Tides.) 
 
 Nebule. An architectural ornament of a 
 
NE 
 
 NI 
 
 rigzag form, but without angles. It is 
 almost peculiar to Saxon and Norman 
 buildings. 
 
 Nebulas. In astronomy, faint luminous 
 spots in the heavens, some of which consist 
 of clusters of telescopic stars, others appear 
 OS luminous spots of different forms. 
 
 Nebulous Stars. A name given by Dr. 
 Herschel to those stars which are surrounded 
 with a faint luminous atmosphere of consi- 
 derable extent. 
 
 Neck of a Column. That part of the 
 shaft between the annulet and the capital 
 above. 
 
 CAPITAL 
 
 NECK 
 ASTRAGAL 
 
 Neck Mouldings. Those around the 
 lower part of a capital in classical architec- 
 ture. 
 
 Needle, Dipping » (See Dipping.) 
 Needle, Variation of. (See Magnet.) 
 Negative. In algebra, arithmetic, &c., 
 the reverse of positive, as negative index, 
 exponent, quality, &c., are such as are in- 
 dicated by the mark — which is called the 
 negative sign, and which signifies less than 
 nothing; as — 5° on Fahr. thermometer, 
 indicates that the temperature is five degrees 
 below zero or cypher. So, again, in alge- 
 bra, fl — J is read a minus b, and signifies 
 that the quantity i is to be subtracted from 
 the quantity a. 
 
 Negative Electricity. (See FranJc- 
 lin^s Hypothesis and Electricity.) 
 
 Negative Axis of Double Refrac- 
 tion. When a ray of light passes through a 
 crystal which has the power of double re- 
 fraction, (see Carbonate of Lime) ; one ray 
 or appearance is called the ordinary or na- 
 tural ray, the other, the extraordinary ray. 
 If this extraordinary ray be refracted towards 
 the axis of the crystal, the axis is called 
 positive ; if it be refracted away from the axis, 
 it is called a negative axis of double refrac- 
 tion. 
 
 Neroli. The name given by perfumers 
 to the essential oil of orange flowers. 
 
 Nerves. In architecture, the movddings 
 of the groined ribs of Gothic vaults. 
 
 Net. a trellis -like fabric of threads or 
 cords, chiefly used for entrapping fish, birds, 
 and other animals. The term is likewise ap- 
 plied to a particular branch of manufacture, 
 of a fine open texture, usually applied to the 
 purposes of dress. 
 
 Neutralization. The state produced, 
 when acids and alkaline matters are com- 
 
 bined, in such proportions that neither pre- 
 dominates, as evinced by the color of the 
 tincture of litmus, or of cabbage remaining 
 unchanged by the combination. 
 
 Neutral Salt. A combination of an 
 acid, with either an alkali, an earth, or a 
 metal ; of such a nature, that the two bodies 
 exactly neutralise each other, so that there 
 may be no preponderance of either. Most 
 salts are of this nature. (See Salts) 
 
 Newcomen's Engine. CSee Atmos- 
 pheric.) 
 
 Nevjtel. The column round which the 
 stairs of a staircase wind. 
 
 Newman's Mercury Trough. (See 
 Mercury Trough.) 
 
 Newtonian Philosophy. The doctrine 
 of the universe, and particularly of heavenly 
 bodies, their laws, affections, &c., as delivered 
 by Sir Isaac Newton. 
 
 Newton's Fusible Metal. (See Fusible 
 Metal.) 
 
 Newton's Telescope, or Newtonian 
 Reflector. This reflecting telescope con- 
 sists of a concave parabolic mirror A fixed 
 at the end of the tube D D. The plane 
 speculum C is fixed to a wire, having its 
 outer end attached to a dove-tailed sliding 
 piece I I ; and the face of the plane mirror 
 is inclined to the axis of the tube ; and the 
 large speculum at an angle of 45°. In the 
 sliding piece I I is inserted a short tube to 
 hold an eye-piece, which is a single lens 
 with its flat side outermost. The rays of 
 light from the object pass into the telescope 
 at R R. They pass onward along the tube 
 to the large speculum, and are here reflected 
 to C, and thence to the eye-piece. 
 
 Nic. Protoxyde of nickle. 
 
 Nicaragua Wood, is an inferior red 
 wood, used with a solution of tin to produce 
 a bright but fugitive red color upon silks and 
 cottons. It is the wood of the casalpinia 
 echinata. 
 
 Nickle. A metal usually associated in its 
 natural state with cobalt. It is always present 
 in meteoric stones. It has been much used 
 of late years as the principal metal in the 
 alloy called German silver. It possesses a 
 fine silvery white lustre, is hard, but malleable 
 both hot and cold, and ductile. It is sus- 
 ceptible of magnetism. 
 
 NicoTiANiNE. The name of an oil ex- 
 tracted from tobacco leaves, which possesses 
 the smell of tobacco smoke, and is a highly 
 dangerous narcotic poison. 
 
NI 
 
 NI 
 
 NicHB. A hollow space cut in a wall to 
 hold an image or statue. 
 
 Nicotine. A peculiar principle obtained 
 from the leaves and seeds of tobacco by in- 
 fusing them in acidulous water, evaporating 
 the infusion to a certain point, adding lime 
 to it, distilling, and treating the product 
 which comes over with ether. A single drop 
 of it will kill a dog. 
 
 Night. That part of the natural day in 
 which the sun is below the horizon, from 
 which is sometimes deducted a portion of 
 morning and evening, called twilight. Thus, 
 in the middle of the summer it is said that 
 we have no real night, although the sun is 
 below the horizon for nearly eight hours, be- 
 cause he never descends so low that we 
 entirely lose his light ; the evening twilight 
 not terminating before that of the morning 
 commences. 
 
 Night Telescope. This is a telescope 
 of the simplest of all constructions, con- 
 sisting merely of a tube, in which is inserted 
 two convex lenses, at a distance from each 
 other equal to the sum of their focal lengths, 
 such as is seen in the following diagram, 
 where A B represents the outer tubes, one 
 sliding within the other, for the adjustment 
 of the focus for near or distant objects. C 
 is the object lens. D the eye-piece or lens. 
 E F G rays of light proceeding from the 
 object to the eye. H the focus of both 
 lenses, and at which point an inverted image 
 of the object is formed. 
 
 Nihil Album. A name formerly given 
 to the white oxyde of zinc. 
 
 NiLOMETER. A column or obelisk erected 
 on the banks of the Nile and marked with 
 
 the divisions requisite for ascertaining the 
 height attained by the waters of the river. 
 
 Nimbus. A showery or rain cloud. 
 
 Nitrates. Compounds of the nitric acid, 
 with various salifiable bases. 
 
 Nitre. The usual name given to the ni- 
 trate of potass or saltpetre. 
 
 Nitric Acid. An acid af a highly corro- 
 sive nature, composed of nitrogen 1 part, 
 and oxygen 5 parts. It is, when pure, color- 
 less and fuming, the fumes being also color- 
 less. It tinges the skin yellow; dissolves 
 and unites with most of the metals, and all 
 the earths and alkalies ; forming nitrates. It 
 may be procured by the distillation of nitre 
 with sulphuric acid. 
 
 Nitric Oxyde. (See Nitrogen, Deut- 
 oxyde of.) 
 
 Nitrico-Oxyde of Mercury. When 
 the nitrate of mercury is exposed to heat, 
 gradually raised to dull redness, nitric acid 
 is given off, and a red substance remains, 
 consisting of peroxyde of mercury, with a 
 small portion of adhering nitrate. This is 
 the nitrico-oxyde. 
 
 Nitrites. Combinations of the nitrous 
 acid with the salifiable bases, alkalis, earths, 
 and metals. 
 
 NiTRo-^RiAL Particles. Oxj^gen be- 
 ing discovered as a constituent of the air, and 
 resembling the nitrates in assisting combus- 
 tion, was considered, as in some degree, an 
 analogous substance, and, therefore, was at 
 first called '* The Nitro- serial particles of the 
 air." 
 
 Nitro-Carburets. a name proposed by 
 Brande to be substituded for cyanides. 
 
 Nitrogen Gas, or Azote. A gaseous 
 element which is permanently elastic, desti- 
 tute of color, taste or smell. It extinguishes 
 all flame, and when unmixed with oxygen 
 is fatal to animal life, yet it constitutes 79> 
 hundredths of the bulk of atmospheric air. 
 It is disengaged from the earth in numerous 
 places, from all animal and many vegetable 
 substances, when in a state of decomposition. 
 It may be obtained artificially by burning 
 phosphorus in a jar of oxygen, the pyro- 
 phosphoric acid having subsided, the jar will 
 be found to contain nearly pure nitrogen. 
 It unites with oxygen in many proportions : — 
 
 Nitrogen 79 Oxygen 21 forms atmospheric air. 
 do. 1 do. 1 do. nitrous oxyde. 
 
 do. I do. 2 do. nitric oxyde. 
 
 do. I do. 3 do. hyponitrous acid, 
 
 do. I do. 4 do. nitrous acid, 
 
 do. 1 do. 5 do. nitric acid. 
 
 Nitrogen, Deutoxyde of. Nitrous Gas. 
 Nitric Oxyde. A gaseous body which may be 
 obtained by pouring upon copper or mer- 
 cury, in a retort, nitric acid of moderate 
 strength. The nitrous gas comes over in 
 abundance. If kept from the contact of air 
 it is colorless, but the instant it is exposed to 
 contact with this element, it absorbs oxygen 
 
NO 
 
 NO 
 
 and becomes nitrous or nitric acid. It con- 
 sists of 47 parts of nitrogen and 53 of oxygen 
 gas by weight, and of equal parts by bulk. 
 
 Nitrogen, Protoxyde of. Nitrous Ox- 
 yde. Laughing Gas. A gaseous product 
 obtained by distilling, at a gentle heat, the 
 nitrate of ammonia. It is colorless, in- 
 creases the bulk of the flame of a taper held 
 to it, and gives it a yellow color ; is absorb- 
 able to a certain degree by water, and very 
 remarkable in its effects when inhaled, occa- 
 sioning to most persons extraordinary sensa- 
 tions of pleasure, and producing laughter, 
 increased muscular exertion, &c. 
 
 NiTRO-MuRiATic Acid. Aqua Regia. 
 A compound formed by mixing I part of 
 hydrochloric to 2 of nitric acid. This com- 
 pound has the property of dissolving gold 
 and platinum, which neither of the acids will 
 separately, (unless assisted by electricity.) 
 Sometimes the proportions of the acids are 
 reversed from those given above, or otherwise 
 altered to suit particular purposes. An aqua 
 regia may also be made by dissolving nitre 
 in hydrochloric acid. 
 
 NiTRO-SuLPHURic AciD. A compound 
 of the nitric and sulphuric acids, which may 
 be also readily obtained by dissolving 1 part 
 of nitre in about 10 times its weight of sul- 
 phuric acid. This dissolves silver at a tem- 
 perature below 200. It scarcely acts upon 
 copper, lead, or iron, unless diluted with 
 water. It is therefore useful in separating 
 the silver from old plated articles. 
 
 Nitrous Acid. An acid which differs 
 from the nitric by having a fifth part pro- 
 portionably less oxygen, consisting of I atom 
 of nitrogen to 4 of oxygen, by being of an 
 orange color, and producing orange fumes, 
 rendered darker by increase of temperature. 
 It may be obtained by distilling the dry ni- 
 trate of lead. Its fumes also arise copiously 
 when diluted nitric acid is poured upon 
 copper. 
 
 Nitrous Gas. (See Nitrogen, Deutox- 
 yde of.) 
 
 Nitrous Oxyde. (See Nitrogen, Prot- 
 oxyde of.) 
 
 Nitrous Turbith. An old name for the 
 sub -nitrate of mercury. 
 
 NiTRUM FixuM. White Flux. (See Flux.) 
 NiTRUM Flammans. The former name 
 for nitrate of ammonia. 
 
 NiTRURETS. Bodies which consist of oxy- 
 gen, hydrogen, and carbon, joined with I 
 atom of nitrogen. Such are many vegetable 
 substances, mushrooms for example. 
 
 Noble Metals. This absurd name, as 
 Dr. Ure says, has been applied to gold, sil- 
 ver, and platinum. 
 
 NoBiLi's Galvanometer. Before a gal- 
 vanometer of a single magnetic needle can 
 obey the influence of the electric current, 
 this latter has to overcome the polar tendency 
 
 of the needle. To remedy this the present 
 instrument is adapted. It consists of two 
 magnetic needles, placed with their poles 
 opposite. Thus the tendency of one to turn 
 in a particular direction, owing to terrestrial 
 magnetism, is counteracted by the other, they 
 are therefore free to obey any influence other- 
 wise communicated to them. The needles 
 themselves are connected together by a straw, 
 and suspended by a silk thread A. One 
 needle is within the coil D, conveying the 
 electrical current ; the other above the coil, 
 and separated from it by a glass plate C— 
 a hole being pierced in the centre of this 
 plate ; and to prevent any agitation of the air 
 from interfering with the instrument, the 
 upper part is inclosed in a glass tube, and the 
 lower part in a glass box B B. As close as 
 possible to the lower needle is a compass 
 card, upon which the deviation of the needle 
 may be ascertained. 
 
 im 
 
 Nocturnal. Relating to the night ; for 
 example, the nocturnal arch is the course of 
 a heavenly body by night. 
 
 Nodes. In astronomy, are the opposite 
 points in which the orbit of a planet or of a 
 moon crosses the ecliptic. The ascending 
 node, marked by the character S3 , (denomi- 
 nated the dragon's head,) is that where the 
 planet or moon ascends from the south to the 
 north side of the ecliptic ; and the descending 
 node indicated by the character "Q . (the 
 dragon's tail,) is where it passes from the 
 north to the south side. The right line joining 
 these two points is called the line of the nodes. 
 
 Node. In the doctrine of curves is a small 
 
NO 
 
 NO 
 
 oval figure, made by the intersection of one 
 branch of a curve with another. 
 
 Node. In dialling, denotes a small hole in 
 the gnomon of a dial, which indicates the 
 hour by its light, as the gnomon itself does 
 by its shadow. 
 
 NoGoiNG. Brick- work which is carried up 
 between quarters. 
 
 N.OGS. Wooden bricks, introduced here 
 and there into walls, for the purpose of 
 fastening internal fittings, window frames, &c. 
 
 NONAGESIMAL DEGREE. (ScC Mid- 
 
 Heaven.) 
 
 NoNAGON. A figure of nine sides and nine 
 angles. The angle at the centre of a nona- 
 gon is 40"^, that at the circumference 140°, 
 and its area when the side is 1 is 6-1818242. 
 
 NoN-CoNDENSiNG ENGINE. (See Hiffk 
 Pressure Engine.) 
 
 Non-Elastic Fluid. Liquids ; or such 
 fluids as are not gaseous. 
 
 Non-Conductor. a term applied in 
 reference to electricity, to designate a certain 
 class of bodies which do not convey the 
 electric fluid along their surfaces, or through 
 their pores. Such are the following : — 
 Glass, resin, sulphur, silk, ivory, bone, 
 baked wood, &c. They are also called 
 eleetricSj from the circumstance, that not 
 conveying away the electric fluid communi- 
 cated to them by friction, or communication 
 with electrified bodies, they by retaining it 
 on their surfaces show electric appearances. 
 (See Conductor and Electric.) 
 
 Nonius. (See Vernier.) 
 
 Nooth's Apparatus. (See Crated 
 Waters.) 
 
 NoRiA. The name of a water engine, 
 common in Spain. It consists of a vertical 
 
 wheel, 20 feet in diameter, on the circum- 
 ference of which are fixed a number of 
 square "buckets for the purpose of raising 
 the water. The lower part of the wheel dips 
 into the water of a running stream, and the 
 wheel is turned round by the action of the 
 stream against float boards, with which the 
 wheel is furnished at the back. The buckets 
 dipping into the water become filled, and are 
 by the motion of the wheel carried upwards; 
 when near the top, they meet with the edge 
 of a trough, which turns them over, and 
 conveys away the water thus deposited in it, 
 while the empty buckets return for a fresh 
 supply. This machine is chiefly used for 
 irrigating land. 
 
 Normal. The same as perpendicular. 
 
 North. One of the four cardinal points. 
 
 Northern Lights. (See Aurora Bo- 
 realis.) 
 
 Northern Signs of the Zodiac, are 
 those that are on the north side of the 
 equator ; they are the six first, Aries, Tau- 
 rus, Gemini, Cancer, Leo, and Virgo. 
 
 Northing. In navigation, is the dif- 
 ference of latitude which a ship makes in 
 sailing towards the north. 
 
 North Pole. (See Pole.) 
 
 North Star. A small star so situated in 
 the heavens as to be very nearly opposite to 
 the north pole of the earth. It appears like 
 a fixture in the heavens, while all the other 
 stars seem to revolve around it, not that they 
 really do so, but only appear to have this 
 motion, in consequence of the rotation of the 
 earth on its axis. The north star is easily 
 found of a clear night, being very nearly in 
 a right line with the two last stars of the 
 great bear, or imagining this constellation to 
 represent a waggon drawn by three horses. 
 
NU 
 
 NU 
 
 it will be found in a line with the two hind 
 wheels of the waggon, which, from this cir- 
 cumstance, are called the pointers. 
 
 
 ^♦c ^ 
 
 
 Nosing. The moulding upon the upper 
 edge of a step. 
 
 Notation. In arithmetic, is the method 
 of expressing any number or quantity by 
 means of symbols or characters, which sym- 
 bols are 1, 2, 3, 4, 5, 6, 7, 8, 9, 0. In 
 algebra, the letters of the alphabet, and 
 numerous other marks are employed to in- 
 dicate the method in which quantities are 
 combined together. 
 
 Nozzle. A projecting part or piece be- 
 longing to an engine, particularly to pumps 
 and other water engines. Also that portion 
 of the steam engine in which are placed the 
 valves that open and shut the communication 
 between the cylinder and the boiler and con- 
 denser. (See Cylinder.) 
 
 Nucleus. Is used by many astronomers 
 to signify the head or body of a comet, as 
 distinguished from the beard or tail ; also 
 for the central parts of the earth and other 
 planets, which some authors suppose firmer, 
 and separated from the other parts as the 
 kernel of a nut is from its shell. 
 
 Number. In its most extended significa- 
 tion has a reference to every abstract quan- 
 tity that can be made the subject of arith- 
 metical computation, but in a more limited 
 sense it signifies only several things of the 
 same kind, and is defined by Euclid to be a 
 multitude of units. 
 
 Number, Golden. (See Golden.) 
 
 Number of Direction. Some one of 
 the 35 numbers within the Easter limits, or 
 between the earliest and latest days on which 
 it can fall, namely, between March 22nd 
 and April 25th, which is 35 days ; and is so 
 called because it serves as a direction for 
 finding Easter of any year, being indeed the 
 number that expresses how many days after 
 the 21st of March Easter-day falls. 
 
 Numeral Algebra, are those cases in 
 which numerals are employed, in contra- 
 distinction to literal, or where letters are used. 
 
 Numeral Figures, are those figures by 
 which all members are expressed in arith- 
 metic, 1, 2, 3, 4, &c. 
 
 Numeral Letters, are geren of the 
 Roman capitals, used by them in expressing 
 numbers ; they are I, V, X, L, C, D, M. 
 
 Numeration. In arithmetic, is the art of 
 reading or estimating the value of any num- 
 ber expressed by the numeral figures or di- 
 gits, any how combined or repeated, and is 
 therefore the reverse of notation. 
 
 Numerator of a Fraction Is that 
 number which stands above the line, as 7 ia 
 the numerator of ^. The whole fraction bears 
 the same proportion to the whole nimiber one, 
 as this numerator bears to the lower figure, 
 or denominator as it is called. 
 
 Numerical, or Numeral. Relating to 
 number. 
 
 NuNCARROw's Steam Engine. An im- 
 provement upon the engine of Savery, in 
 which the steam was condensed in a separate 
 vessel. The following is a detail of its struc- 
 ture ; it was, however, never much used, 
 being subsequent and far inferior to the en- 
 gines of Bolton and Watt. A is the boiler. 
 B the steam pipe, conveying the steam into 
 receiver D, through the valve C. I the con- 
 denser. O a reservoir for supplying the 
 boiler with water. J the injection cock. M 
 a pump, by which water is raised from the 
 well to the cistern O by the pipe N. G the 
 reservoir, from which the water raised through 
 the pipe F falls into the buckets of the water 
 wheel, and gives a rotatory motion. 
 
 EC 
 
 The steam being admitted into D, presses 
 upon the water which it contains, and which 
 is therefore raised through F into G. The 
 valve C being now shut, and H suddenly 
 opened, the steam rushes down I, and meeting 
 with a jet of cold water from J is condensed. 
 A vacuum being by this means made in the 
 
OB 
 
 -GiP 
 
 receiver, the water is forced up by the air's 
 pressure, and again fills it, when the valve C 
 is again opened, and H shut; the action 
 therefore goes on as at first. The condensed 
 steam is allowed to fall through the valve 
 into a small box K, whence it is pumped 
 into the boiler again, by the pump M, and 
 through the pipe N, the cistern O, and the 
 cock and pipe P. 
 
 Nut of a Screw. A piece of iron used 
 in connection with a bolt. It is pierced with 
 a hole, and tapped to fit the screw of the 
 bolt. The nut is screwed upon the end of 
 the bolt, when the latter has been passed 
 through the substances which are to be held 
 together. 
 
 Nutation. In astronomy, a kind of tre- 
 pidation or tremulous motion of the axis of 
 the earth, whereby its inclination to the 
 plane of the ecliptic is not always the same, 
 but varies backwards and forwards some 
 seconds. The period of these variations is 
 nine years. 
 
 Nut Galls. (See Galls.) 
 
 Nut Oil. A drying oil; at first of a 
 greenish, afterwards of a yellowish color, 
 much used by the artist in oil colors. It is 
 extracted by pressure from the common hazel 
 and from the walnut. 
 
 Nux Vomica. A poisonoiis nut, remark- 
 able for containing the vegeto-alkali, strych- 
 nia. 
 
 A vowel, having seve- 
 ral sounds, as are heard 
 in the words, soon,moan, 
 some, son, not. It unites 
 with all the other letters 
 of the alphabet, forming 
 of course dip thongs with 
 the other vowels ; the 
 combined sound of which, particularly of ou, 
 varies very considerably. O by itself is an 
 interjection of surprise, pain, desire, or sup- 
 plication. As a numeral, when standing 
 alone, it is without value, but placed on the 
 right hand of a number it increases it ten- 
 fold : it is then called nought or cypher. On 
 inscriptions it designates Octavius, Octavus, 
 &c. O. S. signifies old style, obt. obedient. 
 Oakum. The substance into which old 
 ropes are reduced, when they are untwisted, 
 loosened, and drawn asunder. It is chiefly 
 used for calking the seams of ships. 
 
 Oak. There are numerous varieties of this 
 tree, but that called for distinction sake, "The 
 English species," (Q^ercus robur,) is by far 
 the most valuable, for toughness, resistance of 
 pressure and strain, hardness, and durability. 
 Oak twists much in dr3ring, and in seasoning 
 shrinks about a thirtieth part of its width. 
 
 Object. Any thing presented to the mind, 
 either by sensation or imagination ; but in 
 optics it is more particularly employed to 
 denote that thing which is to be reflected, 
 magnified, &c. 
 
 Object Glass. In optical instruments, 
 is that which is placed towards the object ; 
 the other extreme lens is called the eye glass, 
 being that to which the eye is directed. 
 
 Obelisk. A tall, slender, quadrangular 
 pyramid, mostly truncated at the top. Obe- 
 lisks are a common characteristic of Egyptian 
 architecture ; and it is supposed were erected 
 chiefly as commemorative stones, or in some 
 
 i instances as gnomons, to show the hours by 
 the shadow which they cast upon a dial made 
 around them. The following shows the obe- 
 lisk, known by the name of Cleopatra's 
 needle. 
 
 Obelisk, Electrical. (See Pyramid.^ 
 Oblate. Flattened or compressed. 
 Oblate Spheriod. A round body of 
 greater width than length, as an orange. The 
 earth is an oblate spheroid. 
 
 OsLiauE. Aslant, indirect, or deviating 
 
 j either from perpendicularity or parallelism. 
 
 OfiLiauE Angle and Line. When one 
 
 I line stands upon another and makes unequal 
 
 j angles therewith, the angles are said to be 
 
 oblique ; the one being greater than a right 
 
 angle, the other less. Hence a line is only 
 
 I oblique when it relates to another line. 
 
 OBLiauE-ANGLED Triangle. A triau- 
 
 I gle containing three oblique angles. 
 
 I OfinauE Arches, or Skew Arches. 
 
 Those which cross a road in an oblique 
 
 direction. 
 
 I Oblong. A rectangle; the angles of which 
 
oc 
 
 OE 
 
 are ri^t angles, but only the opposite sides 
 equal to each oUier. 
 
 Oblong Spheroid. A round body of 
 greater length than width, as a lemon. 
 
 Observation. In astronomy and navi- 
 gation, denotes the measuring, with some 
 instrument adapted for the purpose, the an- 
 gular distance, altitude, &c., of the sun, 
 moon, or other celestial body. 
 
 Observatory. A building adapted for 
 the observation of the heavenly bodies. 
 
 Obsidian. A glassy looking mineral, of a 
 blackish color, found in volcanic countries, 
 and consisting of lava suddenly cooled. 
 
 Obtuse. Any thing blunt or dull, in op- 
 position to what is acute, sharp, or pointed. 
 
 Obtuse Angle. (See Angle.) 
 
 Obverse. The side of a coin or medal 
 that bears the head of the chief or sovereign 
 by whom it was cast. 
 
 Occident. Occidental. The western 
 quarter of the globe or horizon, or that point 
 of the latter where the sun descends into the 
 lower hemisphere ; in contradiction to orient 
 or oriental. Relative to precious stones, as 
 the finest are found in the eastern countries, 
 the term oriental is applied to them as indi- 
 cative of superior quality, while those of an 
 inferior kind are called occidental, though 
 not necessarily found in the western hemis- 
 phere. 
 
 Occult Line. In geometry, a line which 
 is necessarily drawn in the construction of a 
 figure, but which is not intended to appear 
 after the figure or plan is finished ; such are 
 all the vanishing lines in perspective. 
 
 Occultation. The obscuration of a 
 planet or star by the interposition of the 
 moon, or other planet, between it and our eye. 
 
 Ocean. Tliat gigantic body of salt water 
 which encompasses the great divisions of the 
 earth. It is but one continuous mass of 
 water, yet for convenience is divided mto 
 the Atlantic, Pacific, Southern or Indian, 
 and the Northern or Arctic Oceans. 
 
 Octagon. A figure of eight equal sides 
 and eight equal angles. 
 
 Ochre. A genus of earths, slightly co- 
 herent, and composed of fine, soft, smooth 
 particles, easily miscible with water. These 
 earths are of great value to the artist and 
 the house painter. They are of various 
 colors, yellow, red, and brown. The follow- 
 
 ing well-known paints are different varieties 
 of ochre : — Bole, or Armenian bole, terra 
 Sienna, red ochre, reddle, ruddle, or red 
 chalk, Venetian red, brown red, yellow 
 ochre, Spanish ochre, stone ochre, &c. 
 
 Octahedron. One of the five regular 
 solids, the surface of which consists of eight 
 equal triangles. 
 
 Octant. An eighth part of a circle. 
 
 OcTOGON. (See Octagon.) 
 
 Octostyle. a portico of eight columns. 
 
 • • 9 
 
 Ocular Spectra. (See Accidental 
 Colors.) 
 
 Odd Number. That which cannot be 
 divided into two equal whole numbers ; or in 
 other words, that cannot be divided by 2 
 without leaving a remainder, as 3, 5, 7, 1 7, &c. 
 
 Oddly Odd Number, is such a number 
 that when divided by 4 leaves a remainder of 
 3, as 19, 23, &c. 
 
 Odometer. An instrument for measuring 
 the distance travelled by a carriage. It is 
 attached to the wheel, and shows by means 
 of a dial-plate and index the space passed 
 over. (See Perambulator.) 
 
 Oelipile. (See ^olipile.) 
 
 Oenothionic. a new acid formed out 
 of the sulphuric during the making of sul- 
 phuric ether; not however proved to be 
 different from that acid. 
 
 Oested's Experiment. Professor Oested 
 trying the effect of holding a balanced mag-> 
 netic needle near to a wire that a current of 
 galvanism was passing along, found it diverted 
 from its polar direction, and to stand across 
 the wire conveying the current. This was the 
 foundation of electro-magnetism. The fol- 
 lowing apparatus was made to illustrate the 
 
OI 
 
 OM 
 
 fiict : — ^The upper part is of two wires, united 
 together at one end, but separated from each 
 other by a piece of paper, silk, or other 
 electric at the opposite end, where each wire 
 is terminated by a mercury cup. The stand 
 is of wood. When a current of galvanism 
 is passed from one end to the other, the 
 magnetic needle between the wires will be 
 deflected ; if the current pass along the upper 
 wire, the north pole of the magnet will turn 
 one way ; if it pass below, it will turn in the 
 contrary direction. 
 
 Off-Set, orSEx-OFF. The splay or nar- 
 row slanting course of stone or brick, serving 
 to connect two portions of a wall ; the up- 
 permost of which recedes from the face of 
 that beneath. 
 
 Off-Sets. In surveying, are those nar- 
 row, irregular slips of ground, which are 
 outside of the lines which form the measure- 
 ment of the principal part of a field or estate. 
 For example, in the following field, the parts 
 A, B, C, D, and E, are oflf-sets, being out- 
 side of the main lines, and they are measured 
 by perpendiculars drawn across them, as is 
 Been in C : — 
 
 Off-Set Staff. A rod or staff, generally 
 10 links long, and used in field surveying for 
 taking the dimensions of off-sets. 
 
 Ogee, or Cima. A particidar kind of 
 moulding. (See Cima.) 
 
 Ogives. Those ribs of a Gothic vault 
 that pass from one angle to the opposite, 
 crossing the vavQt therefore diagonally. 
 
 Oiii. An unctuous inflammable substance, 
 drawn from various bodies, both animal and 
 vegetable. From the peculiar properties of 
 different oils they are naturally divided into 
 two kinds ; the fixed or fat oils, which make 
 and leave a greasy stain upon paper, and the 
 volatile or essential oils, which leave no staia. 
 The former demand a high temperature to 
 raise them to a state of vapor, but the essen- 
 tial oils are volatilized at the temperature of 
 boiling water, or even at a lower one. Both 
 the fixed and essential oils may be obtained 
 from plants, and often from the same plant. 
 For example, almonds yield, by pressure, a 
 bland, limpid oil, similar to salad oil ; and by 
 distillation, an oil strongly impregnated with 
 prussic acid, and having the strong smeU and 
 
 taste so perceptible in the stones of fruit, 
 from the abundance of the acid they contain. 
 The chief oils used for burning and soap 
 making are train or whale oil, sperm oil, 
 and seal oil. Those used to lubricate ma- 
 chinery are mostly olive oU and palm oil. 
 The painter employs linseed oil, poppy oil, 
 nut oil, and sometimes the oil of lavender. 
 The perfumer and confectioner have occasion 
 for rose oil, neroli, the oils of cloves, cinna- 
 mon, carraway, peppermint, lavender, and 
 others of the essential oils. 
 
 Oil Colors. Colors mixed or miscible 
 with oil, to which they give a body and a tint ; 
 they are either transparent or opaque. The 
 transparent colors are the lakes, Indian yel- 
 low, sap green, indigo, Prussian blue, as- 
 phaltum. Sienna both burnt and raw, burnt 
 umber, verdigris, &c. The opaque are the 
 ochres, the chromes, vermillion, smalt, most 
 of the copper greens, Naples yellow, most 
 of the blacks, red lead, and numerous others. 
 
 Oil Gas. A bi-carburet of hydrogen, 
 obtained by the destructive distillation of oil 
 and fat of various kinds. It has several ad- 
 vantages over coal gas ; as the apparatus is 
 less extensive, the gas free from sulphur, 
 and possesses a double illuminating power. 
 
 Oil of Brick, or Philosopher's Oil, 
 When the fixed oils are boiled at a tempera- 
 ture of 600°, and the vapor collected, it is 
 found acrid, sour, and empyreumatic. This 
 was formerly employed in pharmacy, under 
 the name of philosopher's oil ; and as it was 
 often obtained by steeping a brick in oil, and 
 submitting it to distillation, it was called oil 
 of brick. It is still used by the lapidaries to 
 mix the diamond dust, emery, and other 
 powders with. 
 
 Oil of Vitriol. The old name for sul- 
 phuric acid. 
 
 Oil of Wine. Sulphatic Ether. Sul- 
 phate OF Hydro-Carbon. Names given 
 to a liquid, looking like oil, which is obtained 
 by continuing the distillation of alcohol and 
 sulphuric acid beyond the point at which 
 ether is produced. 
 
 Oil Painting. The painting in oil colors. 
 
 OiLLETS. Peep holes or small loop holes 
 in fortifications, castle walls, &c. 
 
 Oleates. Compounds of oleic acid with 
 the bases. 
 
 Olefiant Gas. The name originally 
 given to what is now called bi-carburetted 
 hydrogen, or bi-hydro-carbon. 
 
 Oleic Acid, is an acid produced by de- 
 composing by the aid of sulphuric acid the 
 soap made of olive oil. 
 
 Oleine. The thin oily part of fats. 
 
 Oleone, is a liquid obtained by distilling 
 oleic acid with lime. 
 
 Olibanum. a gum resin, used as an 
 incense. 
 
 Ombrometer. (See Bain Ouage.) 
 
OP 
 
 OP 
 
 Omfhalofter. An old name for a con- 
 vex lens. 
 
 Onyx. A semi -pellucid gem, covered 
 with lines or marks like belts or zones, as if 
 made up of a number of coats deposited 
 one upon another. 
 
 Oolite. A species of stone, composed of 
 minute round particles like mustard seeds 
 agglomerated together, apparently with inter- 
 vening cement. 
 
 Opacity. A state impervious to light; 
 the opposite of transparency. 
 
 Opal. A hard half-transparent stone, 
 which has the power of reflecting diiFerent 
 colors. Magnesia constitutes a large portion 
 of its composition. 
 
 OpAauE Cups, for Microscopes. When 
 the focal distance of a magnifier, either em- 
 ployed singly, or as the object glass of a 
 compound instrument, is too short to admit 
 of an opaque object being illuminated by a 
 light thrown between it and the lens, the 
 magnifier is mounted in the manner shown 
 in the following figure, where the lens is set 
 at such a distance from the surface of the 
 concave polished reflective cup, called an 
 opaque cup, A A, that the object O shall be 
 in its focus and in the focus of the lens at 
 the same time. When thus arranged, the 
 light is reflected from the opaque cup on to 
 the object. If the light be not sufficiently 
 condensed, a double convex lens is interposed 
 between the light and the opaque cup, as 
 ate. 
 
 Opening. (See Aperture.) 
 
 Opera Glass. A short telescope which 
 magnifies only three or four times. It is so 
 called because first used at the Opera House, 
 to obtain a clearer view of the persons and 
 scenes at a distant part of the house. Its 
 glasses are merely a double convex lens at 
 the larger end, and a concave lens at the 
 smaller, or that end to be applied to the eye. 
 Fig. A represents the bell opera glass, which 
 has not only an elegant appearance, but on 
 account of its shape, admits of a wide object 
 glass. Fig. B is a many-drawer opera glass ; 
 the shortness of the several tubes allows this 
 Instrument to shut up in a small space. 
 Kg. C shows one adapted to both eyes, 
 therefore called the binocular opera glass ; 
 and fig. D represents the diagonal or side 
 
 opera glass, which is of a totally different 
 construction from the rest ; they all require 
 to be directed to the object to be observed ; 
 this is pointed to a different part of the house. 
 This instrument has no object glass, but 
 instead of it a flat mirror occupying the 
 lower part of the body, and inclined at an 
 angle of 45° to the eye-glass, which is double 
 convex, so that the rays are reflected from 
 the mirror to the eye. 
 
 Opium. The juice which exudes from the 
 heads of ripe poppies, rendered concrete by 
 exposure to the air and the sun. 
 
 Opobalsam. The balsam of Peru in a 
 dried state. 
 
 Opoponax. a gum resin, occasionally used 
 in medicine. 
 
 Opposite Angles. (See Angle.) 
 
 Opposition. In astronomy, is that aspect 
 of two heavenly bodies, when they are dia- 
 metrically opposite to each other. 
 
 Optic, or Optical. Any thing relating 
 to optics. 
 
 Optic Inequality. In astronomy, is an 
 apparent irregularity in the motions of the 
 planets and other celestial bodies, being thus 
 called because it does not arise from any 
 irregularity of the bodies themselves, but 
 from the situation of the eye of the observer. 
 
 Optic Pyramid, is a pyramid formed 
 by the visual rays proceeding from the eye, 
 and passing through the extremities of any 
 picture ; when these rays are continued to 
 terminate in a plane perpendicular to the 
 observer, or else perpendicidar to the horizon* 
 as at A, B, C, D. 
 
 Optics. The science of vision ; in which 
 sense it includes the explanation of all tho 
 
OR 
 
 OR 
 
 phenomena dependent on light, its trans- 
 mission, reflection, &c., colors and their 
 combination ; and the construction of those 
 instruments which show the properties of 
 light and assist our natural vision, such as 
 spectacles, telescopes, microscopes, mirrors, 
 &c. The properties of light, when reflected, 
 constitutes catoptrics, and when refracted, 
 dioptrics, which sciences are therefore parts 
 of optics. 
 
 Orb. a hollow sphere, or shell ; in archi- 
 tecture, synonymous with boss and with bal- 
 lon. (See these terms.) 
 
 Orbit. The path of a planet, comet, or 
 other celestial body. The orbits of all these 
 are elliptical. Those of the comets especially 
 so. (See Kepler^ s Laws.) 
 
 Orchil. (See Archil.) 
 
 Orcine. The name of the coloring prin- 
 ciple of the lichen called Lecidia dealbatus. 
 
 Order. In architecture, a particular ar- 
 rangement and proportion of the parts of a 
 building, and dependent upon the relative 
 form of their columns. The term order is 
 applied only to the Greek and Roman styles, 
 in which are five orders ; namely, the Tuscan, 
 Doric, Ionic, Corinthian, and Composite, 
 (which see.) The first and last are Roman ; 
 the other three Grecian. Buildings wholly 
 or partially diflerent from the above are often, 
 though improperly, designated by the term 
 order. Thus if an entablature be supported 
 upon caryatides, it is often said to consist of 
 the caryatic order ; so also if there be a story 
 to a building above the cornice, and that de- 
 corated with pilasters, it is called the attic 
 order. The styles of Gothic, Moorish, In- 
 dian, and other buildings, are often impro- 
 perly called orders. Nothing is truly an 
 order which is not built on acknowledged 
 and established proportions. 
 
 Order of a Line. In the theory of 
 curves is denoted by the dimension of the 
 equation by which the line is defined or ex- 
 pressed. It may be said to be of the first, 
 second, third, &c., order, according as the 
 equation that expresses it is of the first, se- 
 cond, or third degree or dimension. 
 
 Ordinary and Extraordinary Rays. 
 (See Negative Axis.) 
 
 Ordinates. In geometry, are lines drawn 
 across a curve, from one side to the other, 
 and perpendicular to the axis, or else from 
 the surface of the curve to the diameter of it. 
 
 Ordonnance. An old word, to signify 
 the general arrangement and disposition of 
 the parts of a building, painting, procession, 
 &c. 
 
 Oroanical Description of Curves, 
 is the method of describing them on a plane 
 by means of instruments. 
 
 Ores are the mineral bodies which con- 
 tain so much metal as to be worth smelting, 
 or being reduced by fire to the metallic state. 
 
 Oriel. A window projecting beyond the 
 wall, and supported upon brackets. 
 
 Orient. The east or eastern part of the 
 horizon. 
 
 Oriental. The eastern quarter of the 
 world, in contradiction to occidental. 
 
 Oriental Gems. (See Occidental.) 
 
 Ornament. Those smaller and more de- 
 tailed portions of a work of art, which are 
 not essential to it, but added in order to aug- 
 ment its beauty and magnificence. Orna- 
 ments are more or less valuable, inasmuch as 
 they are made to blend harmoniously with 
 more important parts, and to assume to 
 themselves the air of essentials. 
 
 Ornaments, Iris. (See Barton.) 
 
 Orpiment. a sulphuret of arsenic, used 
 as a pigment. It is found native in many 
 parts of the world, and may be artificially 
 produced by fusing together in cmcibles a 
 mixture of sulphur and arsenious acid ; or 
 by passing sulphuretted hydrogen through 
 any arsenical solution. That used by the 
 painter is mostly the native orpiment, the 
 best kind of which is found in Persia. It is one 
 of the finest and most favorite yellow colors. 
 
 Orrery, or Planetarium. Aninstru-, 
 ment for exhibiting the motions of the hea- 
 venly bodies. The following shows one of 
 these instruments of a simple form : — It con- 
 sists of a table, upon the top of which may 
 be.delineated the signs of the zodiac, points 
 of the compass, days of the month, and 
 months of the year. In the centre is a strong 
 wire or brass rod, terminated by a brass ball 
 to represent the sun. On this rod are seve- 
 ral rings, each bearing a long wire, turned up 
 near the end. These have balls of various 
 sizes at their points, representing the planets 
 of our systems, with such moons as naturally 
 belong to them. The length of the wires 
 and size of the balls cannot be made accor- 
 dant with the real size of the planets and 
 their orbits, on account of the very great 
 extent of space which would be required. 
 The planets are seen in their natural order 
 of Mercury, Venus, the Earth and moon, 
 Mars, Jupiter and four moons, and Saturn 
 with seven moons. Herschel Is for want of 
 space omitted. 
 
OS 
 
 ou 
 
 Orrery, Electrical. A small instrument 
 which beautifully illustrates the motion of 
 the moon around the earth, and both together 
 around the sun. There are three wooden 
 balls of different sizes. The two smaller are 
 connected together by a wire, and are 
 balanced upon a point by a small brass cup 
 near the middle of the wire. The point 
 here alluded to forms part of the wire leading 
 to the ball representing the sun. There is a 
 second cup at the centre of gravity of the 
 whole, where a thick wire supports it, the 
 other end being inserted into the prime con- 
 ductor of an electrical machine. A small 
 point projects sideways from the moon, and 
 another point, also sideways, but in the con- 
 trary direction from the end of the longer 
 wire. When electrified, the escape of the 
 fluid from these points propels the apparatus 
 round its respective centres of motion. 
 
 Orselle. The same as archil or orchil. 
 
 Orthogonal. The same as rectangular. 
 
 Orthographical Projection. Inarchi- 
 tecture, is a correct delineation of any thing, 
 drawn according to its actual measurement, 
 without reference to the rules of perspective. 
 If the outside of a building be thus de- 
 lineated, it is called an elevation ; if the in- 
 terior, it constitutes a section. 
 
 Orthostyle. Any straight range of 
 columns ; a word but little used. 
 
 Ortive, or Eastern Amplitude. In 
 astronomy, is an arc of the horizon between 
 the place where a star rises and the eastern 
 point of the horizon. 
 
 Oryctnognosy. Synonymdus with mine- 
 ralogy. 
 
 Oscillation. Swinging. The term is 
 particularly applied to the motion of a pen- 
 dulum. 
 
 Oscillation, Axis of. A right line pass- 
 ing through the point of suspension, parallel 
 to the horizon. 
 
 Oscillation, Centre of. A pendulum 
 when oscillating has one pomt in which its 
 whole moving force is concentrated, and at 
 which, if it meet with resistance, it will 
 instantly stop without vibration or strain of 
 the other parts ; that point is called the 
 centre of oscillation. 
 
 Osculation. In the theory of curves de- 
 notes the contact between any curve and its 
 osculating circle ; or that circle which has 
 the same curvature as the curve at the given 
 point of osculation. Let AC, fig. 1, be 
 
 the evolute of the curve A E F, and (lie 
 tangent C E the radius of curvature at the 
 point E. With this distance, C E as a radius, 
 and the centre C, describe the circle BEG. 
 This circle is said to osculate or kiss the 
 curve A E F, at the point E, which point E 
 is called the point of osculation ; C E the 
 osculatory radius, or radius of curvature; 
 the circle, BEG, the osculatory circle ; and 
 the evolute, A C, the locus of all the centres 
 of the osculatory circles. A point of oscu- 
 lation is also used to denote the concourse of 
 two branches of a curve that touch each 
 other, as in fig. 2 ; supposing the two 
 branches of the curve are extended beyond 
 the point of osculation, otherwise it becomes 
 a cusp. 
 
 OsMAzoME. If cold wator, wliich has 
 been digested for a few hours on raw muscu- 
 lar fibre, with occasional pressure, be evapo- 
 rated, filtered, and then treated with pure 
 alcohol, a peculiar animal principle will be 
 dissolved to the exclusion of the salts. By 
 dissipating the alcohol by a gentle heat, the 
 osmazome is obtained. It has a brownish 
 yellow color, and the taste and smell of 
 soup. 
 
 OsMic Acid. This union of oxygen with 
 osmium, though called an acid by Berzelius, 
 has no acid re-action, yet combines with 
 alkalis. It is, according to Brande, the 
 peroxyde of osmium. It is volatile, has a 
 very peculiar odour, is acrid, poisonous, and 
 stains the skin. 
 
 OsMio - Chlorides. Compoimds of 
 osmium with the hydro-chloric acid. 
 
 Osmium. A metal discovered by M. 
 Tennant in 1803, among grains of native 
 platinum. It has not hitherto been applied 
 to any use in the arts. 
 
 Osteocolla. The glue obtained from 
 bones. The white or satin size used upon 
 paper hangings, previous to their being var- 
 nished, is of this manufacture. Its adhesive 
 properties are very inferior to hide glue. 
 
 Otocoustic. a name formerly applied to 
 any instrument used to assist the hearing, as 
 the ear trumpet. 
 
 OusE. Preparation of bark, used by tan- 
 ners. 
 
 Outline. The contour or boimdary of any 
 thing. Drawing or engraving m outline is 
 
ov 
 
 ox 
 
 depicting only the contour of an object, with- 
 out any shading within it. 
 
 Out to Out. An expression used by 
 builders to signify a measurement which is 
 taken from the outermost bounds of an object. 
 
 Oval. An oblong, curvilinear figure, 
 having two unequal diameters, and bounded 
 by a curve line returning into itself. Under 
 this general definition of an oval is included 
 the ellipse, which is a regular oval. All other 
 figures which resemble an ellipse, though 
 without possessing its properties, are classed 
 under the same general denomination ; as the 
 egg-shaped and pear-shaped body. The three 
 following figures, A, B,C, are therefore ovals, 
 but only the first of them is an ellipse. 
 
 Oval Chuck. An appendage to a 
 of such a nature that the work attached to 
 it and cut by the tool in the usual manner 
 becomes of an oval form. A in the follow- 
 ing cut shows the front of a mandril of an 
 ordinary lathe, fitted up with an oval chuck. 
 The lateral projections are for the support of 
 the director B B. This is a piece of cast 
 iron, having arms perforated with openings 
 in the direction of its diameter, so as to 
 allow it to be fastened in the required 
 position, by means of screws, on the face of 
 the mandril or puppet. From the surface 
 of the circular part projects a ring or neck 
 C, as shown vmderneath. The chuck or 
 sliding part consists of three circular plates 
 
 of considerable strengtti ; to the first is at- 
 tached the piece G, (lower figure,) which has 
 an internal screw that fits into the screw of 
 the mandril. The middle plate consists of 
 two semicircidar pieces, between which, and 
 upon the surface of the first plate, the piece 
 F is made to slide. To this slider is firmly 
 attached the nose E, to which is affixed the 
 article to be turned. The extremities F H 
 are bent so as to fit exactly upon the pro- 
 jection C ; their smooth and uniform motion 
 being still farther secured by means of two 
 screws. The action will be better under- 
 stood by referring to Trammel. 
 
 OvALBUMEN. Albumcu obtained from 
 the white of eggs, so called to distinguish it 
 from ser-albumen, or that obtained from the 
 serum of the blood. 
 
 Oven. An inclosed kiln, employed for 
 baking and drying various substances. 
 
 Overshot Wheel. A wheel which is 
 turned by water flowing on the top of it. 
 
 OvoLo, or Echinus. A quarter round 
 moulding. 
 
 Ovum. An egg ; part of the egg and tongue 
 ornament. (See Egg and Tongue.) 
 
 Oxalates. Salts compounded of oxalic 
 acid and earths, alkalies or metals. 
 
 Oxalic Acid. An acid first extracted 
 from the oxalis acetocella, or wood-sorrel ; 
 hence its name. It is now made entirely 
 from sugar, by digesting it in about four 
 times its weight of strong nitric acid. It is 
 often sold under the name of the salt of sor- 
 rel, and as such is used to take out stains 
 from furniture, dresses, &c. It crystallizes 
 in needle-shaped crystals, which are soluble 
 in water and in alcohol. Ure says that it 
 differs from all the other acid products of the 
 vegetable kingdom in containing no hydro- 
 gen. It is used chiefly as a bleaching mate- 
 rial in the calico printing, and to clean boot 
 tops. 
 
 OxALoviNic Acid. An acid appearing to 
 consist of two atoms of oxalic acid, and one 
 atom of etherine. 
 
 OxAMiDE, OxALAMiDE. When the oxa- 
 late of ammonia is distilled, it becomes 
 opaque from loss of water, fuses, boils, de- 
 composes, and volatilizes, leaving a littie 
 
ox 
 
 ox 
 
 carbon behind ; the liquid which passes over 
 contains a flocculent substance, which also 
 lines the neck of the retort; this has re- 
 ceived the name of oxamide or oxala- 
 mide. 
 
 Ox Gall. (See Gall.) 
 
 Oxidation. The process of converting 
 metals or other substances into oxydes, by 
 combining with them a certain proportion of 
 oxygen. 
 
 Oxides. (See Oxydes.) 
 
 OxioDic Acid. A union of iodine and 
 oxygen, in the proportion of one atom of 
 the former to seven of the latter. 
 
 OxisELS. Salts of which oxygen forms a 
 part, so called to distinguish them from the 
 halosqls, or those containing no oxygen, such 
 as the chlorides, iodides, and bromides. 
 
 Oxydes, or Oxides, are neutral com- 
 pounds, containing oxygen, united to some 
 base. (See Ojcygen.) According to the quan- 
 tity of oxygen that enters into the com- 
 bination, it is called the protoxyde, sesqui- 
 oxyde, deutoxyde, tritoxyde, or peroxyde. 
 
 OxYACiDS. Those acids which derive their 
 acid properties from the presence of oxygen. 
 
 Oxygen. A gaseous element, void of 
 taste, smell, and color ; heavier than at- 
 mospheric air, and constituting about a fifth 
 part of it ; also two parts of oxygen united 
 to two of hydrogen forms water. It is the 
 constituent necessary for the support of ani- 
 mal and vegetable life, as well as combustion. 
 There is no body in nature with which it will 
 not unite, forming oxydes, which according 
 to their properties are called simply oxydes, 
 if neutral ; alkalies, if showing alkaline pro- 
 perties ; earths, if earthy ; and acids, if the 
 oxygen so preponderates over the base as to 
 make the compound to assume the charac- 
 teristics of an acid. It may be obtained in 
 many ways— by the decomposition of water 
 by galvanism ; by putting green leaves in a 
 bell glass, exposed to the rays of the sun ; 
 by means of a glass retort, in which is placed 
 some of the chlorate of potass — heat being 
 applied, oxygen is given off. The most usual 
 way, however, is with an iron retort ; the 
 peroxyde, or as it is commonly called, the 
 black oxyde of manganese, is put in it, the 
 retort fitted with a tube which will convey 
 the gas to a receiver or gasometer, then 
 put into a strong fire, when the gas will 
 distil over. 
 
 Oxygenated Muriatic, or Oxt-Mu- 
 RiATic Acid. The name formerly given to 
 chlorine, under the supposition that oxygen 
 formed its acidifying principle, as well as 
 that of muriatic acid. 
 
 Oxygenation. This word is often used 
 instead of oxydation, and frequently con- 
 founded with it ; but it differs in being of 
 more general import, as every union with 
 oxygen, whatever the product may be, is an 
 
 oxygenation, but oxydation takes place only 
 when an oxyde is formed. 
 
 Oxygon. Oxygonal. Acute angled. 
 
 Oxy-Hydrogen Blow-Pipk. A blow- 
 pipe, the lamp or heat of which is urged by 
 a stream of the mixed gases, oxygen and 
 hydrogen. (See Clarke and Gumey.) 
 
 Oxy-Hydrogen Microscope. This is a 
 valuable instrument of public exhibition, so 
 called because the light is formed by the ac- 
 tion of hydrogen, thrown in an ignited state 
 upon a cylinder of lime ; its flame being at 
 the same time urged by a jet of oxygen, or 
 rather the two gases are previously mixed 
 together, and thrown upon the lime. The 
 instrument in other respects nearly resembles 
 the magic Ian thorn. Fig. 1 shows the whole 
 complete. A and B are two cocks, connected 
 with the bladders holding the geises, one of 
 which is twice the size of the other — twice 
 the quantity of hydrogen being necessary. 
 These cocks are connected with the blow- 
 pipe chamber C ; from the top of which a 
 jet conveys them against a small cylinder of 
 lime D, producing an intense white light, 
 which is reflected by the reflector E on to 
 the lenses in the tube of the instrument. 
 Fig. 2 shows the best method of arranging 
 the glasses ; A is here the reflector. B the 
 light. C a double convex lens, to condense 
 the light upon the object. D the slider of 
 objects. E two plano-convex lenses, forming 
 an achromatic eye piece, through which the 
 rays of light pass, and depict the object of 
 an immense size upon a screen prepared to 
 r^^eive it, in the same manner as in the ex- 
 liiWition of the magic lanthorn. 
 
 Oxy-Prussic Acid. Chlo'o-prussic or 
 chloro- cyanic acid. 
 
 R R 
 
IV 
 
 PA 
 
 __ A consonant, pro- 
 
 |9^^^|^i3||| nounced by the action 
 
 j^aflHH^^^ L of the lips, differing in 
 ^^^^^^^ a very slight degree in 
 sound from B, with 
 which it is frequently 
 confounded, particu- 
 larly by the inhabitants 
 of some parts of Wales, of Lower Saxony, 
 &c. It combines with several other conso- 
 nants, and is silent before n, *, and t, as in 
 pnenmatic, psalm, receipt, 8fc. P standing 
 alone signifies Publius, Publicola, post, 
 piano, parliament, professor, &^c. 
 
 Packing. The fastening of any thing up 
 tightly ; also the hemp or other material 
 put round or between the various parts of a 
 pump or steam engine piston to keep it tight 
 and prevent the steam or water from oozing 
 through. 
 
 Padding. That process in the art of 
 dyeing and calico printing which consists of 
 impregnating the article with a mordant, pre- 
 vious to imbueing it with the coloring 
 material. 
 
 Paddle. A small sluice similar to those 
 by which locks are filled and emptied. 
 
 Paddle. A flat piece of wood or metal 
 used to propel a boat by its counter-action 
 on the water. 
 
 Paddle Holes. The crooked arches 
 through which the water passes from the 
 tipper pond of a canal into the lock to fill 
 it ; or through which it is let out into the 
 lower pond, on the entrance and exit of 
 vessels. 
 
 Paddle Wheels. The wheels employed 
 in the propulsion of steam boats, supporting 
 paddles or floats fixed at equal distances 
 around the rim ; they are placed one upon 
 each side of the vessel, and are secured to a 
 strong shaft passing across it, which is turned 
 round by the engines, each engine working 
 a crank fixed to it. 
 
 Pagoda, or Pagod. A name which has 
 been given to all the temples of the Indians, 
 of whatever shape or size, or to whatever idol 
 or deity they may be dedicated. The Indian 
 pagodas are mostly square ; those of China 
 are lofty towers, which sometimes rise to the 
 height of many stories, and are exceedingly 
 magnificent. 
 
 Paints. Various vegetable and mineral 
 substances possessing a strong color, and 
 therefore used with water, oil, or other 
 medium with which they are blended, to 
 pass over the surface of wood, metal, stone, 
 canvas, &c., to communicate to that surface 
 the same color as the paint or pigment, or 
 the combination of them which is employed. 
 From the metallic oxydes are derived the 
 greater part of our pigments. 
 
 Painting. The art of covering over a sur- 
 face, by means of artificied colors. According 
 
 to the purpose and the material employed so 
 there are different stvles o painting ; of 
 which the following are cne principal : — Oil 
 painting, fresco, miniature, enamel, encaustic^ 
 distemper, water color eivdoric, on glass, 
 &c., and which styles are sub-divided, ac- 
 cording to the respective subjects chosen, 
 into historical, landscape marine, figure, 
 flower, architectural, stili life, portrait, and 
 many others. 
 
 Painter's Cream. Painters, who have 
 long intervals between meir periods of labor, 
 are accustomed to cover the parts they have 
 painted with a preparation which preserves 
 the freshness of the colors, and which they 
 can remove when they resume their work. 
 This preparation is as follows : — Dissolve 
 half an ounce of mastic in 3 ounces of nut 
 oil, over a gentle fire ; put it when melted 
 into a marble mortar, and stir into it i of an 
 ounce of sugar of lead, adding water in small 
 quantities till it assumes the appearance of 
 cream. 
 
 Painter's Varnish, is but another name 
 for boiled linseed or drying oil. It is made 
 by simmering over a slow fire for four or five 
 hours, in a pipkin, a mixture of a quart of 
 linseed oil, with about half an ounce of pow- 
 dered litharge, and a quarter of an ounce of 
 white vitriol. 
 
 Pale. A little stake or piece of wood, used 
 in making inclosures, separations, &c. 
 
 Pales. (See Piles.) 
 
 Palette. Among artists, is a little ivory 
 or wooden tablet, very thin and smooth, on 
 and round which are placed the several co- 
 lors required by the artist, that they may be 
 ready for the pencil. 
 
 Palette Knife. A long knife, with a 
 very thin well-tempered blade, used by artists 
 for mixing colors, or for rubbing down such 
 as have been previously ground on the palette. 
 
 Paling. In agriculture, a kind of fence- 
 work for trees, planted in exposed situations. 
 It consists of three small posts driven into 
 the ground, at a foot and a half distance, 
 with short bars nailed across them near the 
 top. 
 
 Palisades. A high and strong paling 
 used in fortification, to defend open and 
 exposed places ; they are driven strongly 
 into the ground, are well secured together, 
 and are pointed towards the enemy. 
 
 Pall. A detent, or click; that is, a small 
 piece of metal that falls between the teeth of 
 a ratchet wheel, to prevent a load which has 
 been raised from descending when the operative 
 power is removed. It is the pall falling 
 into the teeth of a ratchet wheel which is 
 heard when a clock is wound up, or when a 
 capstan is turned to heave up the anchor. 
 
 Palladium. The name given to a metid 
 discovered in 1803, by Sir H. Davy, 
 associated with platinum, among the grains 
 
PA 
 
 PA 
 
 of which he supposed the ore to exist, or 
 an alloy of it. with iridium and osmium, 
 scarcely disnnguishable from the crude plati- 
 num, tho»!^o ir !S harder and heavier. The 
 pure meta. a^so very nearly resembles plati- 
 num, and ^Kes a nigh polish. It is ductile, 
 very raalleaoie. and when reduced into thin 
 plates, fleiiOie. out not very elastic. It is 
 harder and iieavjer than iron ; its specific 
 gravity is irom iU*9 to ITS. 
 
 Pallas. One of the new planets dis- 
 covered by M. Olbers. It is situated between 
 the orbits of Mars and Jupiter. It is dis- 
 tinguished from all the other planets by the 
 great inclination of its orbit, being about 35°. 
 Its diameter is, according to Herschel, only 
 80 miles. Its mean distance from the earth 
 is 26G millions of miles. 
 
 Pallet. That part of a clock or watch 
 scapement on which the wheel strikes. (See 
 Escapement.) 
 
 Palmer's Electrical Machine. This 
 instrument is a great improvement upon the 
 common electrical machine. The difference 
 between them is, that this is furnished with a 
 double cushion and a double prime con- 
 ductor, whereby the power is increased, 
 though not by any means in a double ratio. 
 A is a thick brass tube, having a ball at the 
 top, and two arms projecting sideways, 
 furnished with points, as C C. The tube 
 A supports one end of the cylinder, and is 
 itself supported upon a solid glass pillar D. 
 B B are glass pillars which support the 
 cushions and flaps. (See Cylinder Machine.) 
 
 Palmer's Gas Lamp tor Heating 
 Tubes. The figure below will suificiently 
 explain this useful instrument. It is screwed 
 on to a gas-pipe, in the manner of aa 
 
 
 ordinary burner, the tube resting on two 
 supports at the end. 
 
 Palmer's Pneumatic Filterer. Avery 
 ingenious application of a well-known fact in 
 pneumatics, that the atmosphere presses upon 
 a surface with a force equal to 15 lbs. on the 
 square inch, when a vacuum is produced 
 beneath it. This filtering machine is formed 
 of two vessels, fitting air-tightly upon each 
 other. The upper vessel contains the sub- 
 stance to be filtered : it is open at top, and 
 with a perforated bottom, like an ordinary 
 coffee filterer ; the lower vessel, which is to 
 receive the liquid when filtered, is completely 
 air tight, and furnished with an exhausting 
 syringe, by which air is drawn from within it. 
 As soon as this is commenced, the atmosphere 
 presses upon the surface of the liquid in 
 the upper vessel, which forces it into the 
 receiver beneath, whence it may be drawn off. 
 The filterer is made of numerous forms ; the 
 foUowins: is one of the most ornamental : — 
 
 Palmer's Rotating Magnet. A pretty 
 electro-magnetic apparatus, of simple for- 
 mation. It consists of a bar of common iron, 
 (an iron hoop, 6 or 8 inches long, will do.) 
 It has covered wire coiled round it, as re- 
 presented ; the ends dipping into a cup of 
 mercury. The cup has a little division across 
 it of wood, so that when the wires are one 
 on each side of the partition, there is no me- 
 tallic communication between them ; the 
 wires proceed under the stand, one from each 
 side of this cup to two other distinct cups 
 near the end. The iron bar is nicely poised 
 upon a centre, so that it moves with little 
 friction. When the two poles of an electro- 
 magnetic battery are placed, one in each cup, 
 the iron, which has now become a magnet, 
 will rapidly rotate on its axis, provided one 
 end of it be placed between the poles of 
 another magnet. 
 
PA 
 
 PA 
 
 Palm Oil. A concrete oil, obtained from 
 different species of the palm tree, particularly 
 the Elceinus Guincensis, a tree of the Western 
 Coast of Africa. It is of a deep yellow co- 
 lor, and used in the manufacture of soap ; 
 occasionally candles ; and still more especially 
 for lubricating the axle-trees and other rub- 
 bing parts of railway carriages, &c. 
 
 Palm re Acid. When palmine is saponi- 
 fied, and the alkali precipitated by an acid, 
 palmic acid is separated. 
 
 Palmine. A substance obtained by M. 
 Boudet from castor oil, by solidifying it with 
 hypo-nitrous acid. 
 
 Pane. A distinct light in a window. 
 
 Pane, Electrical. (See Magic Picture.) 
 
 Panel. A compartment in a wall, ceiling, 
 &c., surrounded either by mouldings, or by 
 parts called styles, which are not usually flush 
 with the panels. Panels used to be once 
 made highly ornamental, not merely in form, 
 but by means of painting and gilding. 
 
 Panel. In masonry, one of the faces of a 
 hewn stone. 
 
 Panorama. A picture exhibiting a suc- 
 cession of objects upon a spherical or cylin- 
 drical surface, the rays of light being sup- 
 posed to pass from all points of external ob- 
 jects, through the surface to the eye in the 
 centre of the sphere, or axis of the cylinder, 
 as near as possible to which the spectator who 
 views the picture is to be situated. 
 
 Pantagraph. (See Pentagraph.) 
 
 Pantheon. In architecture, a temple or 
 building of a circular form, dedicated to all 
 the gods. The most celebrated Pantheon is 
 that of Rome. 
 
 Pantochronometer. a name given by 
 Mr. Essex to an instrument constructed as 
 follows : — A sun dial is affixed to a- magnetic 
 needle, suspended in the usual way, in such a 
 manner as to allow for the variation; it adjusts 
 itself in every position of the instrument. 
 The divisions of the hours and their fractions, 
 and which are carried on to an additional 
 exterior circle, correspondently divided ; and 
 a fixed circle around the dial, on which are 
 inscribed the names of a number of places. 
 By this arrangement the gnomon gives the 
 
 time at the place of observation, and also for 
 any other place inscribed upon it. 
 
 Paper. The leaves or sheets fabricated 
 of fibrous materials, and adapted to write or 
 draw upon, as well as for numerous other 
 purposes. The chief sorts are writing and 
 drawing papers, printing papers, packing 
 papers, and numerous others. Writing and 
 drawing papers are separated into wove, or 
 such as are perfectly smooth on the surface, 
 and laid, or those papers which retain on 
 them the marks of the wire frames upon 
 which the pulp is laid ; called water-marks. 
 Papers of this class varying in size, from demy, 
 a sheet of which is about 19^ inches by 15^, 
 up to antiquarian, the largest size made, 
 are called drawing papers. From demy down- 
 wards to the smallest, called pot ; they are 
 writing papers. Printing papers are rather 
 softer and lighter, and vary much in size. 
 That used for the best impressions of copper- 
 plates, is called plate paper, and is soft and 
 bibulous. India paper is made from the 
 bamboo ; it comes from China, and is used 
 as a superior article for the same purpose as 
 plate paper. Besides the above there are 
 cartridge paper, blue paper, brown paper, 
 hand, or white-brown paper, sugar paper, 
 blotting paper, tissue paper, a soft kind of 
 which is called copying paper ; Manchester 
 paper, which is a large, coarse, brown kind ; 
 sheathing paper, for the use of ship-builders ; 
 and tip paper, for hatters ; colored papers ; 
 rough crayon paper, for artists ; besides a 
 variety of papers differently ornamented 
 after their manufacture, as embossed, marbled, 
 colored, silvered, (^c. 
 
 Paper, Sand, Emery, Glass, 8fc. Sheets 
 of paper washed over with glue, and then 
 dusted with one or other of the above ma- 
 terials, previously ground or sifted to the 
 requisite degree of fineness. Such papers 
 are used for polishing and smoothing sub- 
 stances by artisans and others. 
 
 Paper, Tracing, is of two kinds ; one 
 perfectly transparent, made by rubbing 
 common tissue paper over with poppy oil, 
 Canada balsam or varnish. The other, 
 colored, and made by rubbing upon thin 
 paper a mixture of black-lead and water, 
 lamp black and soap, or sometimes red 
 chalk. The first kind being laid over a 
 drawing, the drawing appears through it, 
 and consequently can be traced. The second 
 being laid between a drawing and a sheet of 
 white paper, (the colored side being on the 
 paper,) when a hard point is passed over the 
 lines of the drawing, a part of the color 
 comes off and leaves corresponding lines on 
 the white paper beneath. 
 
 Paper-Hangings. Long sheets of paper, 
 stained and printed in various devices, for 
 the purpose of lining the walls of apartments^ 
 to give them an ornamental appearance. 
 
PA 
 
 PA 
 
 Papier Machee. A name given by the 
 French to an artificial substance, applied to 
 many useful and elegant purposes. It is made 
 of the waste cuttings of paper, boiled in 
 water, and beaten to a pulp in a mortar. It 
 is afterwards mixed with size, to give tenacity 
 to the paste, and when brought to the proper 
 consistency it is pressed in moulds of an in- 
 finite variety of forms, and thus made into 
 tea trays, snuffers, &c., which are afterwards 
 coated with pigments, varnished, and orna- 
 mented. 
 
 Papin's Digester. An iron pot or ket- 
 tle, which has a cover that fits and screws on 
 steam tight, and is furnished with a safety 
 valve, as represented below. The use of the 
 instrument is that bodies may be subjected to 
 a greater degree of heat than that of boiling 
 water, whereby their digestion and solution 
 is materially assisted. For example, bones 
 will dissolve in water by the assistance of a 
 Papin's digester, and yield a strong nutritious 
 soup, almost equal to that from meat. 
 
 Papin's Steam Engine. This engine, 
 which is one of the earliest, having been con- 
 structed in 1707, was intended only to raise 
 water. It was never extensively patronized, 
 but yet it had some important peculiarities, 
 particularly the introduction of the safety 
 valve, also the elasticity of the air in the 
 receiver producing a constant stream of water. 
 
 A is the boiler, set in brick-work, commu- 
 nicating by the steam pipe B with the pump 
 cylinder. This cylinder terminates in the 
 crooked pipe E S, leading to the straight 
 pipe X, which enters the air-tight cylinder R R, 
 rising to within a short distance of its top. F 
 is the safety valve. Within the cylinder I is a 
 float or piston N. When a sufficiency of 
 steam is generated in A, the cock C is turned, 
 allowing it to pass into I, where it presses 
 upon the piston N, forcing the water which 
 is beneath it through the pipe X into R R ; 
 this condenses the air in R R. The cock P 
 is then opened, and the water issues with 
 great velocity on to the float boards of the 
 water wheel, turning it round, and conse- 
 quently working pumps or other machinery 
 attached to it. When the piston N is driven 
 down, the steam is shut off at C, and the 
 cock D is opened. When this is the case 
 
 the steam in I escapes ; at the same moment 
 M is opened, which admits a fresh supply of 
 water into I, the valve O at the same time 
 closing, and preventing the return of the 
 water from R. W^hen the piston has risen 
 to the proper height, the steam is again ad- 
 mitted, and the action goes on as at first. 
 In the first form of the engine a heater H 
 was introduced at G, and rested upon the 
 top of the piston ; intended to prevent the 
 too sudden condensation of the steam by 
 contact with the otherwise cold piston. 
 
 Parabola. Parabolic. A curved line 
 made by the common intersection of a conic 
 surface and a plane which cuts it, supposing 
 this plane to be cut parallel to the side of the 
 cone. The curved line which bounds it is 
 called the parabolic curve. (See Conic 
 Sections.) 
 
Pa 
 
 PA 
 
 Paraboloid, or Parabolic Conoid, is 
 a solid generated by the rotation of a para- 
 bola about its axis, which remains fixed. 
 
 Paracentric Motion, is the motion of 
 a planet towards the centre of attraction, or 
 the sun. The orbits of the planets being 
 elliptical, they are sometimes nearer and 
 sometimes more remote from the sun, and 
 the difference in this distance is what is 
 called the paracentric motion. 
 
 Parachute, An instrument shaped like 
 the common umbrella, but infinitely larger, 
 invented by M. Garnerin, in order that he 
 might descend safely from his balloon in case 
 of any accident happening to it. "When 
 ascending, the parachute hung from the 
 balloon in a collapsed state, the car being 
 attached to it. When M. Garnerin de- 
 scended from his balloon, which he did 
 safely, in 1802, at London, the parachute 
 upon being cut away, vibrated considerably 
 for the first minute, but afterwards came 
 steadily and softly to the ground. The 
 following is the representation of M. Garne- 
 rin's parachute : — 
 
 Paracyanogkn. When cyanuret of mer- 
 cury is decomposed by heat, a brown solid 
 matter remains, having the same composition 
 as gaseous cyanogen ; hence denominated as 
 above. 
 
 Paradigrammatice. The art of work- 
 ing and forming figures in plaster ; a term 
 now obsolete. 
 
 Paradox. In philosophy, a seeming 
 contradiction and apparently absurd, yet 
 nevertheless accordant with fact. To say 
 that a person may move 1000 miles an hour 
 and yet be asleep appears absurd ; yet, the 
 earth in its rotation on the axis carries him 
 along faster than this. 
 
 Tamadox, Hi/drostatic. {^eeHydrostatic.) 
 
 Paraffine. a solid bi-carburet of hydro- 
 gen. It is white, void of taste and smell, 
 feels soft between the fingers, and burns 
 with a clear white flame, without smoke or 
 residuum. It is decomposed neither by 
 chlorine, strong acids, nor alkalis. It is 
 obtained by the distillation of beech tar. 
 
 Paragrandine. An instrument, the 
 object of which is to avert hailstones in the 
 same manner as electric conductors avert the 
 danger of lightning. 
 
 Parallactic Angle, is the angle sub- 
 tended by two lines drawn from the centre 
 of a planet ; the one to the centre of the 
 earth, and the other to some point on its 
 surface. 
 
 Parallax. An arc of the heavens inter- 
 cepted between the true and apparent place 
 of any of the heavenly bodies ; that is, 
 between its place as viewed from the earth, 
 and from any point on its surface. Thus, 
 let O be the centre of the earth. ABC 
 three different planets, or three different po- 
 sitions of the same planet. Then its true 
 places in these positions, as seen from the 
 centre of the earth, and as referred to the 
 heavens, will be A B C ; but their apparent 
 places will be AEF, if seen from the point D. 
 That seen in the same straight line with O D 
 will have no parallax ; but in the other in- 
 stances the arc E B, F C will be the measure 
 of the parallaxes or of the parallactic angles 
 E H B, F I C, and also of D I O and D H O, 
 to which being opposite angles they are equal. 
 
 Parallax receives particular denommations, 
 according to the circle upon which it is com- 
 puted. The above is called the parallax oj 
 altitude. Horizontal parallax is that which 
 it obtains when the star is on the horizon ; it 
 is greater than at any other time, as is obvious 
 from the above figure. Parallax of right 
 ascension and descension is an arc of the 
 equinoctial, by which the parallax of altitude 
 increases the ascension and decreases the de- 
 scension. Parallax of declination is when the 
 declination of a star is increased or diminished 
 by the same cause ; so also a parallax of latitude 
 increases or lessens the latitude of a star. 
 The mentrual parallax of the sun is an angle 
 formed by two straight lines ; one drawn 
 from the earth to the sun, and another drawn 
 from the sun to the moon, at either of their 
 quadratures. Parallax of the annual orbit 
 of the earth is the angle at any planet, sub- 
 tended by the distance between the earth and 
 sun. Parallax of the planets, the moon, 
 and the fixed stars, the angle made at ar»y 
 
PA 
 
 PA 
 
 planet, &c., by two lines drawn from the 
 centre of that planet, &c. ; one to the centre 
 of the earth, the other to its surface — a ra- 
 dius of the earth being the distance of the 
 lines at their divergent ends. It is from the 
 parallax of the planets that their distances 
 from the sun are computed. 
 
 Parallel. A term applied in geometry 
 to lines, figures, and bodies which are every 
 where equally distant from each other, and 
 which, though infinitely produced, would 
 never meet 
 
 Parallels of Latitude, Declination, 
 &c. (See these terms.) 
 
 Parallelism. The quality of being pa- 
 rallel. 
 
 Parallelism of the Earth's Axis, 
 is used to denote that invariable position of 
 the terrestrial axis, by which it always points 
 to the same point in the heavens, abstracting 
 for the trifling effect of nutation, &c. 
 
 Parallel Motion. A particular part of 
 the steam engine, the object of which is to 
 preserve the piston rod and pump rod always 
 perpendicular, or parallel to the sides of the 
 cylinder, that there may be less wear, and 
 consequently less friction and greater equality 
 of motion in these important parts. 
 
 Let R be the head of the piston rod P R. 
 B the end of the beam. B describes the 
 segment of a circle, and R moves vertically 
 up and down. These motions are adjusted 
 so as to harmonize with each other by the 
 following contrivance. Let a fixed point F 
 be taken, as near as possible to the line in 
 which the piston rod moves. From the 
 points B and E of the beam let inflexible 
 bars R and E H hang down, moving freely 
 on pivots at B and E. Let the extremities 
 
 H and R of these bars be connected by a 
 transverse bar R H, and let another rod pass 
 from H to F, all having free motion on-pivots 
 at both extremities. Let the head of the 
 piston rod be attached to the pivot at R. 
 Then it will have motion without any consi- 
 derable strain, and remain quite vertical 
 throughout its course, as although the end 
 of the beam projects the piston rod outwards, 
 as is seen in the arc L, yet the rod F H pro- 
 jects it equally in the contrary direction, ac- 
 cording to the arc I G J ; and as those side 
 motions counteract each other, the parallelism 
 of the piston rod is preserved. 
 
 Parallel Sailing. In navigation, sail- 
 ing on a parallel of latitude, that is, moving 
 exactly east or west. 
 
 Parallel Sphere. That position of the 
 artificial globe in which the equator coincides 
 with the horizon, and the poles with the zenith 
 and nadir. A spectator placed at the pole 
 would be situated on a parallel sphere. The 
 stars to him would appear to pass round the 
 earth in circles, and not rise or set ; and the 
 sun would rise and set only once in each year, 
 remaining for six months above the horizon, 
 and as many below it. 
 
 Parallelogram. A figure or substance, 
 the opposite ends of which are parallel to each 
 other. It may be a square, a rectangle, a 
 rhombus, or a rhomboid. Also a name some- 
 times given to the pentagraph, (which see.) 
 
 Parallelogram of Forces, is a term 
 used to denote the composition of forces, 
 or the finding a single force that shall be 
 equivalent to two or more given forces when 
 acting in given directions. Thus referring 
 to the following diagram ; if a body A receive 
 
 such a blow as will drive it from A to B in 
 a given time, and at the same moment 
 receives another blow which would drive it 
 to C in the same time, it would, if thus 
 doubly acted upon, obey neither of these 
 forces, nor yet proceed along either the line 
 A B, or the Une A C, but take a third 
 direction, and pass along a line between 
 them ; and if lines be drawn from the point 
 
PA 
 
 PA 
 
 D, where the ball actually stops, to the points 
 B and C, they would form a parallel figure, 
 which is called the parallelogram of forces. 
 When, therefore, any thing is acted upon 
 simultaneously by two forces, it will obey 
 neither, but proceed along the diagonal of 
 the parallelogram, the adjacent sides of which 
 are in proportion to the relative forces im- 
 pressed upon the object. 
 
 Parallelopiped, or Parallelopipe- 
 DON. One of the regular bodies or solids 
 comprehended under six parallelograms, the 
 opposite sides of which are equal and parallel. 
 
 Parallel Ruler. An instrument for 
 drawing parallel or straight lines. Parallel 
 rulers are of different construction. Fig. A 
 shows the ordinary form, as usual in a case 
 of mathematical instruments. The two paral- 
 lel bars are united together by long joints. 
 Holding one bar steady with the hand, the 
 other may be moved up and down, as re- 
 quired. The other form, represented by B, 
 is far superior. It consists of a single piece 
 of wood, having near the centre of it a 
 round or a grooved ruler turning in two 
 sockets, one at each end, and somewhat 
 increased in size towards the end by two 
 milled-headed or micrometer nuts, so that 
 being rolled down a paper, the ruler at the 
 same time remains perfectly steady, and 
 continues parallel. 
 
 Paramal^ates. Neutral combinations 
 of the paramalaeic acid. 
 
 Paramal^ic Acid, is produced by the 
 continuous action of a moderate heat upon 
 the malseic acid, or by boiling it in a long 
 tube, so that the evolved water constantly 
 falls back upon the acid. 
 
 Parameter. A certain and constant right 
 line in each of the three conic sections ; it 
 is always a third proportional to the trans- 
 
 verse and conjugate axes of the ellipse and 
 hyperbola ; and what is the same thing, a 
 third proportional to any absciss and its 
 corresponding ordinate in the parabola. 
 
 Paranaphthaline. a hydro-carbon ; 
 closely resembling naphthzdine in all its 
 properties, but less volatile, and therefore in 
 the distillation of coal tar, whence it is pro- 
 duced, it is among the latter of its products. 
 According to Reichenbach it is a mixture of 
 naphthaline and paraffine. 
 
 Parapet. A dwarf wall or railing, in- 
 tended as an inclosure, as the parapet of a 
 house incloses the roof; of a terrace or 
 bridge, it incloses those who pass along it : 
 often synonymous with balustrade. 
 
 Paraselena. A mock moon; or the 
 same phenomenon applied to the moon, as 
 parhelia is in reference to the sun, and 
 arising from a similar cause. (See Par- 
 helion.) 
 
 Para-Tartaric Acid. (See Racemic 
 Acid.) 
 
 Parchment. The skin of sheep, calves, 
 or goats, prepared after such a manner as to 
 render it proper for writing or drawing 
 upon. The finer kinds are called vellum. 
 
 Parget. A name given by workmen to 
 the various kinds of gypsum, which being 
 calcmed and ground, forms plaster of Paris ; 
 used by plasterers, &c. in pargetting, and 
 other ornamental work. 
 
 Pargetting, or Pergettin^ . A surface 
 of plaster made ornamental by slight waves, 
 mouldings, impressions, &c. The ceilings 
 of houses built in the time of Elizabeth 
 contain mostly fine specimens. Common 
 plastering is also sometimes called pargetting, 
 though improperly so. 
 
 Parhelion, or Parhelium, denotes a 
 mock sun or meteor, appearing as a very 
 bright light near the sun, being formed by 
 the reflection of his beams in a cloud pro- 
 perly prepared to receive it. 
 
 Parquetry. (See Marquetry.) 
 Particle. The minute portion of any 
 thing, whether single atoms or several united 
 together; more generally designating tht 
 latter. 
 
PA 
 
 PA 
 
 Parting. In metallurgy, an operation by 
 which gold and silver are separated from each 
 Other ; or in other words, the refining of the 
 precious metals. 
 
 Party Walls. In building, partitions of 
 brick made between separate buildings, to 
 prevent the spread of fire, &c. 
 
 Paste. A kind of glass, of great specific 
 gravity, made to imitate gems. Paste gems 
 look brightest to the wearer ; real ones to the 
 observer. The following receipt is recom- 
 mended as proper for the foundation of them 
 all, requiring only coloring with the requisite 
 ingredient. Purified white sand, 100 parts ; 
 red oxyde of lead, 200 parts ; calcined potass 
 and nitre, each 20 to 25 parts. It must be 
 kept fused for two or three days ; this will 
 imitate the diamond. For the emerald, add 
 to 160 parts of the above glass, 4 parts of 
 oxyde of copper, obtained by calcination. 
 For sapphires, add to 100 parts of the glass, 
 
 1 part of zaffre, and -Jjr of a part of oxyde 
 of manganese. For the amethyst, take 25 
 pounds of the glass ; ^ an ounce of the oxyde 
 of manganese ; 4 grains of purple precipitate 
 of gold ; and 1^ ounce of nitre. The fol- 
 fowing receipt is for the garnet : — glass, 
 
 2 ounces ; glass of antimony, 1 ounce ; cas- 
 eins precipitate, 1 grain ; and oxyde of man- 
 ganese, 1 grain. 
 
 Paste. A mucilaginous preparation of 
 wheaten flour, incorporated with water by 
 boiling. Soriletimes alum is put with it, to 
 increase its power of adhesion ; at other 
 times rosin, when it has to unite slightly 
 greasy substances. 
 
 Pasteboard. A thick kind of paper, 
 made by pasting several sheets together, 
 which are afterwards pressed or rolled to 
 give the fabric firmness and evenness of 
 surface. 
 
 Pastil, or Pastille. A dry composition 
 of odoriferous resinous matters, commonly 
 employed to burn in chambers to sweeten 
 the air. The ingredients chiefly used in the 
 composition are gum benzoin, cinnamon, 
 and other aromatics. 
 
 Pastil, or Pastel. Among painters, a 
 sort of paste made of various colors, ground 
 up with gum water, either separately or 
 together, in order to make crayons to draw 
 with on paper or parchment. 
 
 Patent. A writ or grant in the name of 
 the sovereign, and under the great seal ; de- 
 signed to secure to the proprietor of any new 
 invention the monopoly of its advantages for 
 the term of fourteen years, but this term is 
 sometimes extended, under extraordinary 
 circumstances, for a longer period. The 
 terra patent is also applied to the right con- 
 veyed, as well as to the instrument convey- 
 ing it. 
 
 Patent Yellow. A fused chloride of 
 lead. It is a pigment of a fine yellow color, 
 
 and considered more durable than the 
 chromes. 
 
 Patera. Any flat ornament upon a 
 frieze, ceiling, &c., often accompanied with 
 swags of flowers or drapery. 
 
 Paternosters. In architecture, a sort 
 of ornament in shape of beads, either round 
 or oval, used on bands, astragals, &c. (See 
 Bead.) 
 
 Paved Way. In engineering, a certain 
 description of tramway, but formed of stone 
 instead of iron ; it may be described as a 
 medium between a road and a railway. There 
 is a paved way along the Commercial Road, 
 near London. 
 
 Paving. The same as pavement, but 
 usually applied to roads, and pavement to 
 parts to be trodden upon by us. 
 
 Pavilion. A small slated building ; also 
 a projecting part of a large building. 
 
 Pavement. A layer of stone or other 
 hard substsmce, serving to cover or strengthen 
 the ground in such places as are subjected to 
 much traflic. Paving is performed with sub- 
 stances of very numerous kinds, with wood, 
 granite, and other stones, in slabs or pebbles ; 
 slates, bricks, clinkers, and tiles, laid in 
 different manners. Knob paving is formed 
 of large gravel stones, for garden seats, &c. 
 Bones and teeth, used for like purposes. 
 The pavements of churcties and halls are 
 often highly ornamental, either on account 
 
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 of the material employed or the manner of 
 its arrangement, of which examples are 
 given under the articles Tessellated and 
 Q^arried. The combinations of various 
 colored marbles are often made highly deco- 
 rative. The preceding is one of the very 
 numerous examples of marble pavement, 
 composed of black, white, and veined 
 marble. 
 
 Pearl. A hard, white, shining body, ge- 
 nerally roundish, and found in several species 
 of the oyster family, particularly of the Myca 
 margaritifera, a large species, common in 
 the Indian seas. 
 
 Pearls, Artificial. Small globules of thin 
 glass, perforated with two opposite holes. 
 They are lined with a pov/der or rather awash, 
 made of the brilliant scales of a small fish, 
 called the blay, soaked in liquid ammonia and 
 isinglass. The ammonia evaporating leaves 
 the scales adherent to the inner surface of the 
 flobules. 
 
 Pearlash. a purified carbonate of potass. 
 
 Pearl Micrometer. (See Breivster.) 
 
 Pearl, Mother of. (See Mother of Pearl.) 
 
 Pearl Shell. (See Mother of Pearl.) 
 
 Pearl White. Sub-muriate of bismuth, 
 a white pigment, used chiefly as a cosmetic. 
 It turns black upon the application of an al- 
 kali, sulphuret, or a sulphuretted gas. 
 
 Peat. A spongy black earth, combined 
 with decayed vegetable matter ; when dried 
 it forms a valuable fuel. 
 
 Pectic Acid. An acid inherent in many 
 vegetables, and which occasions the jelly-like 
 appearance that many of them assume when 
 boiled. It is in the form of a colorless jelly, 
 which tastes sour ; it is scarcely soluble in 
 cold water, but more freely so in hot water. 
 
 Pectine. a vegetable jelly, is made by 
 mixing alcohol with the juice of ripe currants, 
 till a gelatinous precipitate falls down. This 
 is to be washed and dried. 
 
 Pedestal. The foot or base of a column 
 or statue ; when used to support a column 
 it is mostly one-third the height of the co- 
 lumn above it. When complete it consists 
 of three parts ; a base or foot, a square 
 plinth or dado, and a cornice, as in the fol- 
 lowing cut : — 
 
 A double pedestal supports two columns ; 
 a continued pedestal sustains a range of co- 
 lumns, without any break or interruption in 
 it. The pedestals o^ statues and vases have 
 no determined character, being often round, 
 oval, oblong, or of other shape. 
 
 Pediment. The triangular part over the 
 entablature at the end of a building ; also a 
 similar part over windows, gates, niches, &c. 
 It is sometimes a portion of a circle. 
 
 Pedometer. A mechanical instrument, 
 in form of a watch, consisting of various 
 wheels, with teeth catching in one another, 
 all disposed in the same plane ; which by 
 means of a chain or string, fastened to a 
 person's foot, advance a notch each step, so 
 that the number being marked on each wheel, 
 one may number the paces, or measure 
 exactly the distance from one place to another. 
 (See Perambulator.) 
 
 The wheel-work of the pedometer is seen 
 above. A is a wire, fastened to the foot or 
 leg of the pedestrian ; as his foot moves 
 backwards and forwards in walking A will 
 act as a pendulum upon the pallet B. This 
 moves the wheel C, and the hand D ; C 
 moves the pinion and wheel E ; and this last 
 moves the pinion F, and with it the hand G, 
 as explained under Perambulator ; under the 
 wheel C is a spring to bring it forward a 
 tooth, when such is liberated by the pallet. 
 The hands of the dial register the number of 
 units, tens, hundreds and thousands of steps 
 taken. If the instrument is to be attached 
 to a carriage wheel, an endless screw like H 
 communicates to it the first motion, as is 
 explained under Perambulator. 
 
 Peirameter. An instrument, invented by 
 Mr. J. Macneil, which indicates the amount 
 of resistance offered by the surfaces of roads, 
 
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 of different constructions, to the passing of 
 wheel carriages, &c. The machine is as fol- 
 lows, and which being (irawn along a road, 
 the resistance is indicated by the dial plate at 
 the top. 
 
 Pelecoid. a peculiar-shaped curve, formed 
 somewhat like the head of a hatchet ; or con- 
 tained under the two inverted quadrantal 
 arcs A B and A D, and the semi-circle BCD. 
 
 The area of the pelecoid is demonstrated 
 to be equal to the square A B C D, and that 
 again to the rectangle E B D F. It is equal 
 to the square A B C D, because it wants of 
 the lower half of the square the two segments 
 A B, AD, which are equal to the two seg- 
 ments B C, C D, by which it exceeds it on 
 the upper half. 
 
 Pellet. A Gothic architectural ornament, 
 consisting of plain, flat, circular pieces or 
 pellets, arranged along a fascia or band, at 
 equal distances. 
 
 Pellicle. A thin stin which forms over 
 various liquids, &c. ; also a scum, or an ap- 
 parent dross, which is seen on the top of the 
 solutions of salts when the solution is satu- 
 rated. 
 
 Peltry. Synonymous with fur, or the 
 skins of different kinds of wild animals that 
 are found in cold countries. As they are 
 first received, they are called peltiy ; when 
 tanned or otherwise prepared for use, they 
 uxQfurs. 
 
 Pen. An instrument for writing with a 
 liquid. Pens are of various kinds : — First, 
 quill pens, or such as are cut by a knife out 
 of a common goose- quill. Second, such as 
 are tipped with metal, after having been thus 
 cut ; and metallic or steel pens, such as are 
 now in common use. The latter are very 
 varied in form, as will be seen below. Each 
 shape has its advocates, and numerous con- 
 trivances have been adopted to give greater 
 elasticity to the nib, which is one of the 
 greatest defects of this description of pen. 
 
 A, is Perry's three-slit pen. B, Perry's 
 regulating pen. C, Mordant's oblique pen. 
 D, Mordant's three-nibbed ipen, the extra nib 
 being cut out of the metal above the slit and 
 turned down to form a triangle with the 
 other nibs ; and E, is the lunar pen or the 
 spade pen. 
 
 Pens, Dotting, for writing music, consist 
 of a small brass cylinder, in which a pin of 
 the same material works vertically, being 
 kept down and projecting about the tenth of 
 an inch, by a spiral spring in the upper 
 part of the pen ; an opening about half way 
 up receives the ink. 
 
 Pen, Draiving or Ruling. (See Bow Pen.) 
 
 Pen, Fountain, or Hydraulic Pen. A pen 
 so contrived as to hold a quantity of ink that 
 it may serve both for pen and ink -stand. A 
 very simple one may be made with a common 
 quill pen, by filling the barrel of it with ink, 
 then stopping it with a plug of wood, leaving 
 a slight cavity next the slit of the pen for 
 the ink to flow out, which it must only do 
 when a slight shake is given to the pen. 
 
 Pen, Music. A ruling pen so contrived as 
 to draw the five lines of music at once. It 
 consists of a parallelogram of brass, termi- 
 nating in five slit points, communicating 
 with a reservoir above, in which the ink is 
 placed. 
 
 Pencil. In painting, an instrument em- 
 ployed by painters in laying on their colors. 
 They differ from tools and brushes only in 
 being smaller, more delicately made, and of 
 
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 finer materials. The chief substances em- 
 ployed in their manufacture are camel's, 
 badger's, and squirrel's hair ; the latter 
 forms those pencils known as yellow fitch. 
 The down of swans is sometimes used. 
 These materials are fastened at the thicker 
 end by a piece of strong thread, and inclosed 
 in the barrel of a quill. All good pencils, 
 upon being drawn through the lips, come to 
 a fine point. In drawing, a pencil consists 
 of a long slip of black-lead or colored chalk, 
 inclosed in a round stick of cedar wood. 
 
 Pencil, Ever-pointed. A contrivance pa- 
 tented by Mr. Mordant, in 1823. The pen- 
 cil case, which is of metal, has a slider ac- 
 tuated by a screw, for the purpose of pro- 
 jecting forward a little cylinder of black lead, 
 as it wears away ; the thickness of the lead 
 being so small as not to need cutting. The 
 figure is a section of the pencil case : — The 
 black rod A is the black lead ; immediately 
 behind this is a wire E, which is attached to 
 the screw B, and beyond that is a guide C, 
 passing through a small hole in the partition 
 at D. The nozzle being kept from moving 
 while the barrel of the pencil case is turned 
 round, or vice versa, the lead is drawn out 
 or in as required. 
 
 Pencil Drawings. Drawings which are 
 made by the aid of the black-lead pencil only. 
 
 Pencil of Rays. In optics, denotes a 
 number of rays diverging from some lumi- 
 nous point, which, after falling upon and 
 passing through a lens, converge again on 
 entering the eye. 
 
 Pendant. A sculptured ornament, sus- 
 pended from a Gothic roof, from the inter- 
 section of the ribs or bracketing. 
 
 Pendentive. Any part of a vault or ceil- 
 ing which projects beyond the perpendicular 
 of the walls. 
 
 Pendentive Bracketing. A cove 
 bracketing, springing from the walls of an 
 apartment upwards to the ceiling, so as to 
 form the horizontal part into a curve. 
 
 Pendulum. Any heavy body so suspended 
 that it may vibrate or swing backwards and 
 forwards, about some fixed point, by the 
 alternate action of momentum and gravity, 
 after having been once set in motion. The 
 vibrations of a pendulum are called its oscil- 
 lations ; the time of each being counted from 
 the time of its descent from the highest point 
 on one side till it attains the highest point on 
 the opposite side. The time occupied in a 
 single oscillation depends upon the length of 
 the pendulum, but the distance the weight 
 travels, or the length of the arc, is in pro- 
 portion to its weight. If, therefore, a clock 
 go too fast, the pendulum must be lengthened; 
 if too slow, it must be shortened ; making it 
 heavier or lighter will not affect the rate of 
 going of the clock. 
 
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 Pendulum, Ballistic. (See Ballistic.) 
 
 Pendulum, Compensation. A pendulum 
 which is so constructed that it always retains 
 precisely the same length, notwithstanding 
 the effect of heat and cold expanding and 
 contracting . the length of the rod. (See 
 Gridiron, Reed, Sfc.) 
 
 Penetrability. The capability of being 
 pentrated. 
 
 Penetration. The act of piercing one 
 solid body by another in motion. Thus, a 
 bullet fired from a gun penetrates a board. 
 We often use the term with considerably 
 greater latitude, and say that a liquid pene- 
 trates the earth ; steam penetrates into our 
 apai-tments. The word permeates or in- 
 sinuates itself w^uld be better ; penetrating 
 signifying rather a forcible entry of a solid 
 into another solid. 
 
 Penumbra. A faint or partial shade, ob- 
 served between the perfect shadow and the 
 fall of light in an eclipse. This arises from 
 the magnitude of the sun, for were he only 
 a luminous point, the shadow would be 
 every where perfect ; but in consequence of 
 his diameter it happens, that a place which 
 though not illuminated by the whole body of 
 the sun may, notwithstanding, receive a part 
 
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 PE 
 
 of his rays. This may be illustrated 
 follows : — 
 
 Let S be the sun and M the moon ; then 
 it is obvious that since luminous rays pro- 
 ceed from every part of the sun's disc, there 
 will be no part of the shadow in which the 
 light will be totally intercepted, except that 
 included within the rays, proceeding from 
 the extreme edges of the sun and moon 
 ABC, and E D C ; the other part of the 
 shadow, namely, from C to H, and I, ex- 
 periencing only a pai'tial obscuration. Thus, 
 a spectator of a total eclipse is situated in 
 the umbra or real shadow ; the spectator of 
 a partial eclipse in the penumbra ; and be- 
 yond the edge of this the eclipse is invisible. 
 
 Penstock. Pentrough. An instrument 
 intended to regulate the supply of water to 
 a mill or water-wheel. 
 
 Pentagon. A figure of five sides and 
 angles. 
 
 Pentagraph. An instrument for copy- 
 ing designs, in any proportion to the original. 
 It is of brass, and consists of four levers, 
 A B C D, the two longest of which, A and B, 
 are jointed together at their ends, and to the 
 levers at the others ; thus, the instrument 
 always forms a parallelogram. F, G, and H 
 are three tubes upon the levers, two of 
 which, F and G, slide along, and can be 
 fixed at any point by screws. If either of 
 these points be made a fixture ; for example, 
 H ; a drawing be placed under another point, 
 as G ; and a piece of white paper be placed 
 under the third point F, where there is a 
 pencil; upon moving the point at G over 
 the lines of the drawing, it will be found 
 that the pencil point at F will trace pre- 
 
 cisely corresponding lines on the white paper 
 beneath it, which will bear a propor.tion of 
 size with the original, according to situations 
 at which the sliding pieces G and F have 
 been set. 
 
 Pentastyle. a portico of five columns. 
 
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 Pepys's Balneo, or Filter Bath, being 
 made in the shape of a filtering bag. It is 
 a vessel of tin, shaped as represented ; 
 within this is a second vessel which fits into 
 the first, of a conical shape, and made of 
 glass. When any precipitate is to be dried, 
 such as an explosive compound, the outer 
 vessel is partly filled with water, boiling or 
 heated to any other certain degree, and the 
 precipitate is placed in the inner vessel ; the 
 point dipping into the water becomes heated, 
 and consequently the precipitate dries. 
 
 Pepys's Blow-Pipe, (bee Blow-Pipe.) 
 Pepys's Eitdiometer. (SeeEudiometer.) 
 Pepys's Gas-Holder. (See Gas-Holder^ 
 Per. In chemical words implies the highest 
 degree of oxydati on, &c., of which the sub- 
 stance is known to be capable ; thus, we say 
 a peroxyde, peracetic acid, perfluorine, &c. 
 
 Perambulator, or Measuring Wheel. 
 An instrument which being run along a road 
 or other level surface indicates and registers 
 the exact distance it passes over. The gene- 
 ral form of the instrument, and its system of 
 wheel-work, is seen as follows — 
 
 The wheel is 8^ feet in circumference, and 
 consequently measures exactly a pole in every 
 two revolutions. The number of re\olu^ 
 
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 PE 
 
 tions made, and consequently the distance 
 passed over, is seen on the dial-plate, where 
 there are two hands, one moving round a 
 circle, upon which are inscribed yards, poles, 
 and furlongs ; the other, that is the shorter 
 hand, indicates the number of miles travelled. 
 The movement will be seen in the lower 
 figure. A is a small pinion fitted on to the 
 axis of the measuring wheel. This pinion 
 turns the perpetual screw B ; and, of course, 
 the second perpetual screw C, which is upon 
 the same arbor. C turns D, and to the 
 arbor of D is fastened the longer hand H, 
 which moves around the dial-plate in forty 
 poles or one furlong, consequently in eighty 
 revolutions of the wheel. The wheel D, 
 besides moving the hand H, moves also the 
 pinion E, and the wheel F, which is united 
 to it. The wheel F moves the pinion G, 
 and to this is attached the second hand I, 
 which it will be observed is upon the same 
 arbor as H , like the two hands of a clock. The 
 hand I registers furlongs and miles ; ten 
 miles being complete when it has passed 
 round its appointed circle. 
 
 Perbend, Perpent, or Thorough. A 
 term applied to the heading stones of a 
 wall when they extend entirely from one side 
 of it to the other. 
 
 Perchloric Acid. Synonymous with 
 the hydro-chloric acid. 
 
 Percolator. A filtering machine. 
 Percussion. The striking of one body 
 against another, or the shock arising from 
 the collision of two bodies. It is either 
 direct or oblique. Direct percussion is 
 when the impulse takes place in a line per- 
 pendicular to the plane of impact. Percussion 
 in any other direction is called oblique. 
 
 Percussion, Centre of. In striking any 
 body with a bar or lever, it is always found 
 that if the blow be given at or near the end 
 of the bar, it will jar, or attempt to fly out 
 of the hand ; and if the blow be given by 
 that part of the bar near the hand, it will 
 also jar and attempt to fly from it. Now 
 there evidently must be a point between 
 these two, where if a stroke be given, the 
 full effect of the blow will be sensible, and 
 the bar will remain at rest, without jarring 
 the hand ; this is called the centre of per- 
 cussion, and in a straight uniform bar it 
 will be at the distance of one-third the 
 length of the bar from the outer end of it. 
 
 Percussion, Force of. The momentum 
 of one body communicated to it by the mo- 
 mentum of another; thus, a wedge pene- 
 trates into a fissure in proportion to the 
 force of percussion, the strength of the 
 blow, or the degree of momentum which it re- 
 ceives from a mallet or other body striking it. 
 Percussion Powder, for fire-arms, is 
 made thus : — 10 parts of gunpowder is dis- 
 solved in water, then filtered, and the paste 
 
 left is mixed with 5^ parts of finely-powdered 
 chlorate of potass, and a drop of it poured 
 into each of the little percussion caps used 
 with fire-arms ; when dry it is fit for use. 
 As this composition corrodes any part that 
 it touches, the fulminate of mercury is now 
 more generally used. 
 
 Peridrome. That open space or gallery 
 on the sides of a temple or other building 
 which is between the side columns and the 
 walls, and used as a promenade among the 
 ancients, Pronaos appUes to the same part 
 in the front of a temple. 
 
 Perigee. That part of the moon's orbit 
 in which she is at the least distance from 
 the earth ; contrary to apogee, or the 
 greatest distance. (See Apogee.) 
 
 Perihelion, or Perihelium. That point 
 in the orbit of a planet or comet which is 
 nearest to the sun, as opposed to aphelion, 
 the most distant point. (See Aphelion.) 
 
 Perimeter. In geometry, the boundary 
 of any body, whatever be its shape ; of a 
 circular body it is usually called a periphery, 
 or circumference. 
 
 Period. In astronomy, the time in which 
 a planet or satellite makes one entire re- 
 volution in its orbit, or returns again to 
 the same point in the heavens. In chro- 
 nology, an epoch or space of time, by which 
 events are reckoned. In arithmetic, it signi- 
 fies any particular division of numbers. 
 Thus we say, divide the number into periods 
 of 2 figures each, or 3 figures each, as the 
 case may be. In printing, the period or 
 full-point signifies a complete termination of 
 a sentence, or very often a contraction, as 
 A. M., &c. In decimal arithmetic, a period 
 is put between the whole number and the 
 decimals, as in 24-833. 
 
 Perioecians. In geography, those people 
 who inhabit the same parallel of latitude. 
 
 Peripatetic Philosophy. The system 
 of philosophy taught and established by 
 Aristotle. The word comes from the Greek, 
 and signifies to walk, because the students 
 were taught and argued while walking in the 
 Lyceum. 
 
 Periph ery. The circumference or bound- 
 ing line of a circle, ellipsis, parabola, or 
 other regular curvilinear figure. 
 
 Periputist, Patent. A small cooking 
 apparatus, invented by Mr. Welles. It is 
 formed of tin, and consists of several vessels 
 placed over each other, as is seen in the 
 following section. A is a conical vessel 
 holding burning charcoal. B a vessel sur- 
 rounding it, containing water. C the ash- 
 hole. D a steaming vessel with a perforated 
 bottom, and a conical tube in the centre to 
 fit over tlie fire-place cone ; this is oj)en 
 above, and is furnished with holes for the 
 emission of the steam and vapour from the 
 fire; above this is a saucepan E, and instead 
 
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 of a lid to the saucepan, 
 boiler, &c. -F is placed. 
 
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 Periptere. Any building surrounded 
 with a single row of columns, as the Par- 
 thenon, at Athens ; the Temple of Concord, 
 at Agrigentum, &c. 
 
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 Periscii. a term formerly applied to the 
 inhabitants of the two frigid zones, because 
 their shadows at times make an entire cir- 
 cumference in one day. 
 
 Periscopic. a name given by Dr.Wollas- 
 ton to such spectacles as allow the eye a con- 
 siderable latitude without fatigue. Their 
 form is that of a meniscus glass with the 
 concave side turned towards the eye ; they 
 are used for spectacles, microscopes, &c. 
 When spectacles, thus rendered periscopic, 
 are intended for long-sighted persons, or old 
 age, the anterior surface, or that next the 
 object, is formed spherically convex, with a 
 curve deeper than the concave, so as both to 
 gain the required power, and to compensate 
 for the divergency occasioned by the concave 
 side ; this form is shown in fig. A. The 
 contrary ratio of concavity and convexity 
 will, of course, be necessary for short-sighted 
 persons, as is seen at B. 
 
 Periscopic Combination of Lenses. 
 (See Herschel.) 
 
 Peristyle. A building encompassed by 
 a row of columns on the inside, by which it 
 is distinguished from periptere, or a building 
 having a row around the outside. The terms 
 are however often used synonymously. 
 
 Peritrochium. a word in mechanics, 
 signifying a wheel, as the axis in peritrochio ; 
 synonymous with the wheel and axis, (which 
 see.) 
 
 Perlatb Salt and Acid. The name ot 
 the perlate acid was given by Bergman to 
 the acidulous phosphate of soda ; Haupt 
 having called the phosphate of soda the per- 
 late salt. 
 
 Permanent. Remaining through every 
 change, as a permanent color, a permanent 
 dye, &c. are such as are not affected by the 
 sun, by washing, or the usual casualties to 
 which it may be subjected. 
 
 Permanent Ink for Linen. (See 
 Marking Ink.) 
 
 Permanent White, or Constant 
 White. The sulphate of barytes, a valuable 
 color for many purposes, as no chemical 
 substance will decompose it or change its 
 color. 
 
 Permanent Way. The finished road of 
 ' a railway. 
 
 Permanganic Acid. Manganic or man- 
 , ganesic acid united to an extra portion oi 
 I oxygen, containing 3^ atoms of oxygen to 
 every one of manganese. 
 
 Permutations. Changes in the positioi 
 of things, differing from combinations ii 
 this — that the latter has no reference to th 
 order in which the quantities are combined 
 whereas in permutations this order is con 
 sidered. 
 
 Perpendicular. A line falling direct!) 
 upon another line so as to make equal angle; 
 on each side. Thus, A B is perpendicular 
 to C D, because the angle A B C is equal to 
 A B D. E F is also perpendicular to G H 
 for the same reason. In both these cases, 
 and in all others, the two angles on the sides 
 of the perpendicular are right angles, and 
 must be so ; therefore when one line meets 
 another and makes a right angle with it, the 
 lines are perpendicular to each other, whiit- 
 ever be their position relative to our view o£ ^ 
 
PE 
 
 PE 
 
 them. However, in a right-angled triangle 
 the perpendicvilar is generally considered to 
 be that line which constitutes one of the legs 
 of the right angle, and which, at the same 
 time, most nearly approximates to an erect 
 position in the diagram. Thus E F, H F, 
 may each be called the perpendicular of the 
 triangle E F H, according as we view the 
 figure, the other leg being the base and the 
 longer line the hypothcnuse. An object is 
 said to stand perpendicularly where a line 
 let fall from its centre of gravity is perpen- 
 dicular to the general level of the earth's 
 surface, or which line, if produced, would 
 reach to the earth's centre. 
 
 Perpendicular to a Curve, is a line 
 perpendicular to a tangent of the curve at 
 that point. 
 
 Perpendicular Lift. A contrivance 
 on canals for passing the boats from one 
 level to another. 
 
 Perpent Stones. (See Perlend.) 
 
 Perpetual Lever. Another name given 
 to a wheel of any kind, a wheel being in 
 fact a series of levers or spokes, the fulcrum 
 of which is the centre of the axis ; the 
 moving power the circumference of the £ixis ; 
 and the weight, whatever is moved by the 
 wheel, so that it may be considered as a 
 perpetual oi uninterrupted series of levers, 
 one or other of which is always acting. In 
 other cases the circumference of the wheel is 
 the power. 
 
 Perpetual Motion, is that which 
 possesses within itself the principle of motion, 
 and that of sufficient force to overcome the 
 friction of its parts. In nature there are 
 numerous perpetual motions, such as the 
 revolution of the heavenly bodies, the tides, 
 organic and inorganic changes, vital functions, 
 &c. Artificial or mechanical perpetual 
 motion has never yet been attained, though 
 the subject has occupied the attention of the 
 ingenious for many ages, the nearest approach 
 to it being, perhaps, the dry electrical pile 
 of De Luc. 
 
 Perpetual Screw, or Endless Screw, 
 is a peculiar kind of axis, having upon it a 
 spiral thread, which works a toothed wheel, 
 which it turns round with a great decrease 
 of velocity by proportionate increase of 
 j'ower, at the same time the direction of 
 
 motion is altered from one 
 another, varying 90*^ from it. 
 
 direction to 
 
 Perpetuity. In the doctrine of annuities, 
 is the number of years in which the simple 
 interest of any principal sum will amount to 
 the same as the principal itself ; or it is the 
 quantity arising from dividing 100 by the 
 rate per cent, for one year. Thus, the per- 
 petuity at 5 per cent, is 20 years ; at 4 per 
 cent. 25 years. 
 
 Persian Wheel. (See Noria.) 
 
 Persians. Male figures used instead of 
 columns to support an entablature; the 
 female figures are called caryatides. 
 
 Perspective. The art of representing 
 objects on a definite surface, so as to affect 
 the eye when seen from a certain position, 
 in the same manner as the object itself would 
 when the eye is fixed at the same or a 
 corresponding point ; or, supposing we look 
 at a number of houses or trees, dispersed 
 over a view, through a pane of glass, and 
 draw upon that glass all the lines apparent 
 through it, such lines would represent the 
 houses in true linear perspective ; and such 
 as are farthest from the eye, as they appear 
 in reality to be the smallest, so they would 
 be represented. Again, if we color such a 
 picture as it appears through the same 
 medium, the effect of distance will be height- 
 ened, and our picture will have the colors 
 brighter and more distinct in the fore-ground, 
 and gradually becoming more and more 
 
PE 
 
 PH 
 
 obscure as the objects are farther off ; this is 
 called (Brial perspective. In linear per- 
 spective different terms are used to designate 
 the various parts of a picture, and the lines 
 necessary to construct that picture according 
 to the rules of the art. In the cut the 
 principal of these are seen. 
 
 The horizon is the line that extends hori- 
 zontally across the picture at the height of 
 the draughtsman's eye ; this is seen at H H. 
 A particular point in this, exactly opposite 
 the eye, is called the centre of the picture O ; 
 all the horizontal lines of the picture tend to 
 this point, as E O, C O, H O, I O, J O, 
 A O, BO, &c. ; all these lines are called 
 vanishing lines ; the line connecting the 
 centre of the picture and the eye is called 
 the principal visual ray : and its length is 
 the distance of the picture. Whatever is 
 delineated is called an original object. The 
 surface upon which these objects stand is the 
 ground plane, and the picture itself is the 
 perspective plane. 
 
 Perspective, Isomeirical. A particular 
 kind of perspective, in which the objects are 
 always represented at a 
 particular angle, show- 
 ing at the same time 
 tliree contiguous sides, 
 ust the same as would ■' BMBBiifckftiinilllliilB • 
 oe observed with a 
 cube, upon looking at 
 it exactly over one of 
 »ts angles, when, as is 
 seen in the margin, precisely one-half of the 
 cube is visible ; and any thing resting upon 
 either of the three apparent sides, would, 
 of course, be visible also. This kind of 
 perspective, therefore, has the advantage of 
 showing at the same time a correct view of 
 two horizontal sides of an object, and the top 
 of it also. In depicting machinery, masses 
 of buildings, or plots of estates, it is most 
 valuable, and the practice so easy that there 
 are no difficulties in its attainment, as there 
 are in the ordinary linear perspective. The 
 following cut shows the application of isome- 
 trical perspective in depicting a building and 
 garden : — 
 
 small two-drawer pocket telescope, which, 
 when closed, is about 4 inches long. It is 
 not calculated for distances above 3 or 4 miles. 
 Peiispectograph. An instrument for 
 the mechanical drawing of objects in per- 
 spective. The following is one invented by 
 Mr. Turrell, and described by him in the 
 " Transactions of tho Society of Arts," 
 vol. xxxii. 
 
 Perspective. The name given to a 
 
 Suppose A to be an object to be delineated 
 on the paper B. C is a bar of metal or 
 wood, which passes through the (damp D, 
 and which is held to the table by the screw 
 E. The rod F slides up and down through 
 the end of the bar C. G is another rod 
 having a joint at bottom, and a sliding piece 
 H. To use the instrument, look through 
 the hole I, and adjust H so that you can see 
 a certain point of the object through a hole 
 in H ; then turn the rod G downwards, and 
 the point attached to H will make a mark 
 upon the paper. A series of these marks 
 being thus taken, and lines drawn from one 
 to the other, as required, will give an out- 
 line of the original object. 
 
 Petrifactions. Stony matters deposited 
 either in the way of incrustation, or within 
 the cavities of organized bodies, are called 
 petrifactions ; also all organical substances 
 which have become so hard as to assume the 
 appearance and character of stone. 
 
 Petroleum. A fluid bitumen of a brown, 
 black, or dingy color, analogous to naphtha 
 in composition, but of a rather greater con- 
 sistence. 
 
 Pewter. A well-known alloy ; made by 
 melting 6 oz. of copper, and when melted, 
 adding 7 lbs. of tin, 1 lb. of lead, and 2 oz. 
 of zinc ; or for best pewter, 100 parts of 
 tin and 17 parts of regulus of antimony. 
 
 Phantasmagoria. Denotes a remarkable 
 optical illusion arising from a particular ap- 
 plication of the magic lantern. In the ex- 
 hibition of this spectacle, the spectators are 
 placed in a dark room having a transparent 
 screen between them and the lantern, which 
 screen ought to be let down after the lights 
 are withdrawn, and unknown to the spec- 
 tators. The lantern being then properly 
 
PI 
 
 PI 
 
 tected in the tar of beech wood. It consti- 
 tutes one -sixth of this tar. 
 
 Pick. A hammer for dressing the stones 
 of a flour mill. 
 
 PiCROMEL. A black bitter principle, sup- 
 posed to be peculiar to the bile or gall of 
 animals. 
 
 PicROTOxiNE. An intensely bitter, poison- 
 ous, vegetable principle, extracted from the 
 seed of the menispermum cocculus, (cocculus 
 indicus.) 
 
 Picture. An imitation or representation 
 by lines and colors of any natural or arti- 
 ficial object or appearance. 
 
 Pier. A square or rectangular pilaster 
 of stone, brick-work, &c., not fashioned in 
 classical proportions ; sometimes imbedded 
 in the wall ; sometimes free ; as the piers 
 which support a wall, arch, bridge, &c. It 
 has no base or capital. Pier is also a strong 
 marine erection, extending from the shore to 
 a considerable distance in the sea, and by 
 breaking the violence of the waves forming a 
 harbour within or towards the leeward of it, 
 for the protection of shipping and other 
 craft. If employed merely for landing goods 
 and passengers it is often called a jetty. 
 
 Pig Iron. Also known by the name of 
 crude iron or cast iron, never having been 
 subjected to the process of hammering. 
 
 Pigment. (See Paint.) 
 
 Pilaster. A square pier of brick-work 
 or stone, with similar capital ornaments, 
 proportions, and projections, as a column. 
 It is occasionally detached from a wall, but 
 mostly so imbedded in it as not to show 
 above one-fourth its thickness. These are 
 called by Vitruvius antce, while parastratoe 
 signified those which were free. Pilasters, 
 in carpentry, are square, flat columns or 
 ornaments, fluted or reeded, and made of 
 deal, with moulded caps and bases, and 
 placed either on broad styles or flat upright 
 members of a building to remove the flat 
 unornamented appearance of such parts. 
 
 Pilaster, Demi. A pilaster that supports 
 an arch ; it generally stands against a pier. 
 
 Pile. A word to signify an extensive 
 mass or body of building. 
 
 Piles. Rows of stakes or timbers driven 
 deep into the ground to make wooden bridges 
 over rivers, water inclosures, coff*er dams, 
 &c., and often to erect edifices upon. 
 
 Pile, Galvanic, or Voltaic. A number of 
 galvanic circles united together so as to form 
 a compound series of elements acting in 
 unison, or galvanic battery. Those batteries 
 may more peculiarly be called piles, in which 
 the elements are piled or heaped up upon 
 each other, as is seen in the following series, 
 which is built up of two different metals, 
 such as copper and zinc, with a piece of 
 damped cloth between each pair, in the 
 manner of De Luc's dry pile or column, and 
 
 according to the following cut, where the 
 white represents the copper, the black the 
 zinc, and the shaded intervals the moistened 
 cloth. If a pile of this kind, made of penny 
 pieces, and similar pieces of zinc be built up 
 till there are twenty or more of each, a 
 slight galvanic shock may be felt by touching 
 the ends with the fingers, they being pre- 
 viously moistened. (See Circle, Battery, 
 and De Luc.) 
 
 Pile, Thermo-Electric. (See Melloni.) 
 
 Pile Engine. A machine for driving piles 
 
 into the ground. There are several kinds of 
 
 pile engines, the principle of all of which is to 
 
 raise a great weight gradually by machinery ; 
 
PI 
 
 PI 
 
 or the united strength of several men to a 
 height of 30 or 40 feet, and then letting it 
 fall suddenly upon the end of the pile, until 
 by reiterated blows it is driven into the 
 ground. The foregoing cut shows the ordi- 
 nary pile engine, which may be thus de- 
 scribed : — A is the pile to be driven into the 
 ground. B is the ram, or a large heavy mass 
 of iron, which being let fall from the top of 
 the machine on to the head of the pile, 
 drives it downwards. At the back of the 
 part of the ram which is seen are two pro- 
 jecting pieces, which fit into grooves cut in 
 the sides of the uprights C C. The object 
 of these projecting pieces and grooves is to 
 guide the ram in its passage up and down. 
 There is a staple on the top of the ram, 
 which is caught hold of by two hooks, as seen 
 at D in the side cut. This part of the ap- 
 paratus is called ^q monkey, and is drawn up 
 by a chain, passing over the pulley I, and 
 coming down to the crab or crane F, where 
 the men work. As soon as the monkey and 
 ram get to the top, the upper ends of the 
 monkey press against the inclined planes E E, 
 and by this means the hooks below are sepa- 
 rated, and let go the ram. When D is 
 suffered to run down, its own weight brings 
 it to the bottom, and attaches it a second 
 time to the ram. 
 
 Pile Planks, are planks whose ends are 
 sharpened to drive into any canal or water, 
 close to each other, in order to form a dam, 
 by which the water may be stopped or dis- 
 charged. 
 
 Pillage. A word sometimes used for a 
 square pillar standing behind a column to 
 bear up the arches, having a round base and 
 capital as a pillar has. 
 
 Pillar. A round column, out of propor- 
 tion, either too massive or too slender ; thus 
 the thick supports of a Gothic vault, and the 
 apparently light iron rods, now so much in 
 use to carry the fronts of houses, &c., are 
 of this description. The following are all 
 pillars, but not columns : — 
 
 Pillowed, or Pulvinated. A term ap- 
 plied to a rounded frieze. 
 
 Pin. To strike a piece of metal with the 
 narrow end of a hammer to form dents and 
 produce expansion. For example, the iron 
 hoops of casks are made larger at one edge 
 than at the other by this means, in order 
 that the hoop may better fit the tapering 
 surface of the cask. 
 
 Pincers. A tool formed by placing two 
 levers on one fulcrum, for holding bodies 
 firmly. 
 
 Pinchbeck. An alloy composed of 5 oun- 
 ces of copper and 1 ounce of zinc, melted 
 together. The zinc must not be added till 
 the copper is fused. Some use only half the 
 quantity of zinc, in which proportion the 
 jdloy is more easily worked, especially in the 
 making of jewellery. 
 
 PiNEY Tallow. A concrete fat obtained 
 by boiling with water the fruit of the Valeria 
 Indica, a tree common upon the Malabar 
 coast. It is a substance intermediate between 
 tallow and wax, is white or yellowish, and 
 forms excellent candles. 
 
 PiNic Acid. A hard brittle substance, 
 procured by digesting common rosin in pure 
 alcohol, mbcing with the clear solution 
 another alcoholic solution of acetate of 
 copper ; thus a pinate of copper is formed. 
 This substaace washed in alcohol and hydro- 
 chloric acid furnishes a solution, from which 
 water throws down the pinic acid. 
 
 Pinion. A small toothed wheel, not in 
 general having more than twelve teeth, leaves, 
 or pallets, as they are here called ; also when 
 two cog wheels woi-k in each other, the 
 smaller is often called a pinion. The cut 
 shows various applications of the pinion. A 
 is a winch, turning the pinion B, which turns 
 the wheel C, while this latter turns the two 
 pinions D and E. A pinion may also turn, 
 or be turned by a rack as at F. 
 
 Pinning. The fastening of things together 
 with small pins, bolts, pegs, &c. 
 
 PiPERiNG. A crystalline substance ex- 
 tracted from black pepper by means of 
 alcohol. It is soluble in alcohol, but not in 
 water, and has scarcely any taste or color. 
 
 Pipe-Clay. a kind of aluminous clay, 
 fine, plastic, and tenacious, which require* 
 a considerable degree of heat to fuse it, and 
 then forms a white or cream-colored hard 
 
PI 
 
 PL 
 
 substance, which at first rapidly absorbs 
 nioistui'e. 
 
 Pinnacle. A pointed termination to 
 a turret, buttress, &c. 
 
 ih !l« 
 
 Pipes. Vessels employed for the con- 
 veyance of any fluid, and which are usually 
 of a cylindrical shape, and made of iron or 
 lead. Thus, we have main or large pipes, 
 and service or small pipes ; or designating 
 them by the use to which they are put, we 
 may say gas-pipes, water-pipes, &c. ]?ipe 
 is also a measure of capacity, used for wine, 
 and contahiing according to the kind of 
 wine from 110 to 136, or 140 gallons. 
 
 Pirn. The wound yarn that is on a 
 weaver's shuttle. 
 
 Pise. A style of building in which the 
 walls are made of a kind of clayey mortar 
 mixed with straws, which, when dry, forms 
 a solid mass ; such buildings are extremely 
 common in many of the western and northern 
 countries. 
 
 Piston. A plug made to fit tight and 
 move up and down a cylinder in pumps and 
 other hydraulic machines, the steam engine, 
 air pump, &c. 
 
 Piston Rod. The rod connected with a 
 piston, being passed through the centre of 
 it and secured by means of a screw or key, 
 the other end of the piston rod being attached 
 to the pump handle ; or if belonging to a 
 steam cylinder to the parallel motion. 
 
 Pitch. A hard, black, bituminous sub- 
 stance, obtained by boiling wood tar in an 
 ojjen vessel till the volatile matters are 
 driven off. 
 
 Pitch. In architecture, the proportion 
 between the height and the span of a roof. 
 If the rafters exceed in length the width of 
 
 the building, the roof is said to be of the 
 Elizabethan, or knife-edge pitch, as A B C; 
 if they are equal to the width, the pitch is 
 Gothic^ as ADC; if of two-thirds the 
 width, the roof is said to be of a true pitch, 
 or of the Roman pitch, as A E C ; a roof 
 still flatter than this is the Grecian pitch, as 
 AFC. 
 
 Pitch, Mineral. (See Asphaltum and 
 Bitumen.) 
 
 Pitch of a Wheel. The distance of the 
 centres of two teeth, measured upon their 
 pitch line. 
 
 Pitch Lines. Millwrights call by this 
 term the relative circles of wheels which 
 work one in the other ; called also pro- 
 portional lines or circles. 
 
 Pit Coal. A general name for the com- 
 mon coals used for firing, such being dis- 
 tinguished by this name from charcoal. 
 
 Pith Balls. Small balls made of the 
 pith of the elder tree, and used in numerous 
 electrical experiments to show the effects of 
 attraction and repulsion. 
 
 Pith Balls, Dancing. (See Dancing.) 
 
 Pittacall. One of the six curious sub- 
 stances discovered to be in the tar of beech 
 wood. It is a dark blue solid substance 
 somewhat like indigo, assumes a metallic 
 fiery lustre on friction, and varies in tint 
 from copper to golden. It is void of taste 
 and smell, is diffusible in water, and dyes a 
 fast blue upon linen and cotton goods with 
 the usual mordants. 
 
 Pivot. A short shaft or point upon 
 which a body turns or vibrates. 
 
 Plaister, or Plaster. Any thing of a 
 thick consistence and an adhesive property, 
 used to cover over a surface for the preser- 
 vation of it from injury. 
 
 Plaister, or Plaster of Paris. Cal- 
 cined gypsum, used by the builder and the 
 artist to form casts and moulds of varioxis 
 ornaments ; to mend defective places in de- 
 corative ceilings, cornices, and siiuilar ob- 
 jects, and to unite marble and other stone- 
 work together. 
 
PL 
 
 PL 
 
 Plafond. Synonymous with soffit or 
 ceiling. 
 
 Plan. The representation of something 
 drawn on a flat surface, as maps, charts, 
 draughts of the foundations or other sections 
 of buildings, ships, &c. If all the parts are 
 delineated in their true relative proportions, 
 it is called a geometrical plan ; if the parts 
 diminish in proportion to their distance, it is 
 a perspective plan. 
 
 Plain Angle. An angle contained under 
 two lines or surfaces, so called in contra- 
 distinction to a solid angle. 
 
 Plain Trigonometry. (See Triffo- 
 nometry.) 
 
 Plane. In carpentry, is a tool used to 
 produce straight, flat, and even surfaces upon 
 wood. The diflferent kinds of planes are very 
 numerous. 
 
 Plane. In geometry, is a completely flat 
 or even surface, or one with which a straight 
 line will every where coincide. They may be 
 horizontal, vertical, or perpendicular, and 
 inclined or oblique. Planes are also fre- 
 quently used for imaginary surfaces, supposed 
 to cut and pass through solid bodies, and on 
 this construction is founded the whole doc- 
 trine of conic sections. In astronomy, the 
 same term is used for an ideal plane passing 
 through certain parts or points of the hea- 
 vens, as the plane of the horizon, of the 
 ecliptic, equator, &c., by which is to be un- 
 derstood certain ideal planes passing through 
 those circles of the sphere, or on which they 
 are supposed to be described. 
 
 Plane of Cleavage in Crystals and 
 Stones. Those who are in the habit of cut- 
 ting gems know that they will only afford 
 smooth surfaces in certain directions. These 
 are called their planes of cleavage. 
 
 Plane, Geometrical. The same as ground 
 plane. (See Perspective.) 
 
 Plane, Inclined. (See Inclined.) 
 
 Plane, Perspective. (See Perspective.) 
 
 Plane Chart. In navigation, a sea chart 
 constructed on the supposition of the earth 
 and sea being an extended plane surface. 
 ?uch charts have, consequently, the meri- 
 dians represented as lines parallel with each 
 other. 
 
 Plane Sailing. The art of performing 
 the several reckonings necessary for con- 
 ducting a ship on the ocean, on the principles 
 of the plane chart. 
 
 Plane Table. An instrument formerly 
 much used in surveying for taking angles, 
 and laying down the work in the field as it 
 was measured. It consists of a board upon 
 which the paper is laid, and inclosed by a 
 frame, graduated along the sides, by which 
 the lines were plotted. It had a compass 
 and pair of sights connected with it. 
 
 Planimetry. That part of geometry 
 which measures and considers plane figures 
 
 or superficies only ; for example, land and 
 sea surveying. 
 
 Planisphere. A projection of the sphere 
 and of the several circles thereof on a plane, 
 as upon paper or the like. In this sense, 
 maps of the heavens or the earth, in which 
 are exhibited the meridians, parallels, and 
 other circles, are called planispheres. 
 
 Plank. A general name for all timber 
 excepting fir, which is from 1 inch and a 
 half to 4 inches thick ; if of less dimensions 
 it is called a board. 
 
 Plank-Hook. A pole with an iron hook 
 at the end, with which navigators shift their 
 runs or wheeling planks, as occasion re- 
 quires. 
 
 Plano-Concavr. Flat on one side and 
 concave on the other. (See Lens.) 
 
 Plano-Convex. Any thing which is 
 flat on one side and convex on the other. 
 (See Lens.) 
 
 Planting. In architecture, denotes the 
 laying the first courses of stone on the 
 foundation, according to the measures, with 
 all the exactness possible. 
 
 Planet. A wandering star, as dis- 
 tinguished from such as are fixed or stationary, 
 and likewise distinguished from the comets, 
 which are also wandering, by the planets re- 
 volving in oxbits, which are much less con- 
 centric. They are often called primart/ 
 planets, having the sun as their centre of 
 rotation, while the secondary planets or 
 moon revolve around their primaries. T\\e 
 names and characters given to the planets 
 belonging to our system, and which are 
 all that we know positively to exist are 
 Mercury $ , "Venus $ , the Earth 0, Mars 3 , 
 Jupiter 2/., Saturn h > and Herschel, or the 
 Georgium Sidus 1^1, besides four very small 
 ones between the orbits of Mars and Jupiter, 
 called sometimes Asteroids ; thoy are Ceres, 
 Juno, Pallas, and Vesta. The relative sizes 
 of the principal planets may be inferred from 
 the following comparative cut of them : — 
 
 It is to be further observed, that the extent 
 of their orbits varies no less than their rela- 
 tive sizes. Mercury being but 37 millions 
 of miles from the sun, while Herschel is 
 
PL 
 
 PL 
 
 1800 millions of miles ; also those which are 
 nearest the centre move with a greater velo- 
 city than those which are remote, and all 
 their motions are performed in the same or- 
 der from west to east, or according to the 
 order of the signs of the zodiac. They have 
 also each a rotatory motion about their own 
 axes, the time of which, however, appears to 
 have no relation with regard to their magni- 
 tude, or their distance from the sun. For 
 other particulars, see each planet by its name ; 
 also Kepler's laws, Asteriods, 8fc. 
 
 Planets, Elements of the, are certain 
 quantities which are necessary to be known in 
 order to determine the theory of their ellip- 
 tic motion. Astronomers reckon seven of 
 these elements, of which five relate to their 
 elliptic motion : viz. 1. The duration of the 
 sidereal revolution. 2. The mean distance. 
 3. The eccentricity. 4. The mean longitude 
 of the planet at any given epoch. 5. The 
 longitude of the perihelion at the same epoch. 
 The other elements relate to the position of 
 the orbits and are— 1. The longitude at a 
 given epoch of the nodes of the orbit with 
 the ecliptic. 2. The inclination of the orbit 
 to this plane. 
 
 Planetarium. (See Orrery.) 
 
 Planetary. Something relating to the 
 planets. 
 
 Planetary System. (See Solar System.) 
 
 Plat Band. A square moulding, having 
 
 projection less than its width. 
 
 Plate Electrical Machine. Anelec- 
 trical machine, so called because a plate of 
 glass is substituted for a cylinder. In the 
 cut, A represents the plate of glass, which is 
 made circular, and has a hole drilled through 
 the centre for the admission of a spindle, so 
 that it may be turned by the handle B. 
 C C C C are four cushions, fixed two and 
 two together, to rub against the glass. D D 
 are two double flaps of black silk. E is the 
 prime conductor, which is of metal, termi- 
 nated by a ball H at one end, and after 
 branching into two arms F F, which are bent 
 at the part next the plate, terminating with 
 
 points as at 6 G. I and J are glass rods, to 
 support the prime conductor. These are not 
 both necessary, if the machine be small ; the 
 rod marked I being sufficient. 
 
 Plate Glass. The fine kind of glass cast 
 in thick plates, and used for looking glasses, 
 the better kind of windows, &c. Its com- 
 position is 300 lbs. fine sand, 200 lbs. so<la, 
 30 lbs. lime, 2 lbs. manganese, 3 ounces co- 
 balt azure, and 300 lbs. fragments of good 
 
 Plated Ware. Articles made of a com- 
 mon metal, mostly copper, and washed over 
 with a thin coat of silver. 
 
 Pl A tin ODE. The cathode or negative pole 
 of a galvanic battery. 
 
 Platinum. The heaviest body in nature. 
 It is a metal of a white color; malleable, 
 ductile, tenacious, unalterable in the air ; not 
 to be melted, except by galvanism ; or by the 
 heat of the sun, concentrated by powerful 
 lenses ; nor acted upon by the most power- 
 ful acids, aqua regia alone dissolving it. When 
 thus dissolved, it may be united to ether, 
 forming what is called the etherial solution. 
 It is also capable of being welded at a white 
 heat. Platinum unites with most of the 
 other metals. From its hardness, infusibility, 
 and difficulty of being acted upon by most 
 agents, platinum is of great value for making 
 various chemical vessels. 
 
 Platinum Thermometer. (See Mor- 
 veau.) 
 
 Platonic Bodies. (See Bodies.) 
 
 Platonic Year, or the Great Year, 
 is the period of time determined by the revo- 
 lution of the equinoxes, upon the supposition 
 of the precession going on uniformly till they 
 have made one complete revolution. 
 
 Plenium. In philosophy, is that state of 
 things in which every part of space, or ex- 
 tension, is supposed to be full of matter ; in 
 opposition to a vacuum, which is a space 
 devoid of all matter. 
 
 Plinth. The square part under a pedestal, 
 forming the lowest member of a column, 
 wall, &c. 
 
 Plotting. Among surveyors, the art of 
 describing or laying down upon paper, the 
 several angles and lines of a tract of ground, 
 surveyed by a theodolite chain, &c. 
 
 Plough, Stationer's. (See Stationer.) 
 
 Plumbago, or Graphite. The chemical 
 name of black-lead. It is a carburet of iron, 
 containing 95 parts of carbon to 5 of iron. 
 It is infusible, and burns with great diffi- 
 culty. It is of an iron grey color, metallic 
 lustre, soft to the touch, and easily scratched. 
 (See Black-Lead.) 
 
 Plumbum Corneum. Chloride of lead ; 
 obtained by mixing hydro-chloric acid with 
 nitrate of lead. 
 
 Plummet, Plumb Line, or Plumb 
 Rule. An instrument used by masons, car- 
 
FN 
 
 PO 
 
 penters, &c. to draw perpendiculars. It 
 consists merely of a straight-edged piece of 
 wood, having a string and a leaden ball at 
 the end of it freely suspended, so that when 
 the edge is made to coincide with any thing, 
 the erect position of which is to be ascer- 
 tained, the plumb bob hangs freely in the 
 hole prepared for it, without inclining to 
 either side. 
 
 Plunger. A solid piston, particularly 
 such an one as is used in force pumps. 
 
 Plus. In mathematics, the affirmative or 
 positive sign + which signifies addition. In 
 a similar sense, bodies are said to be electri- 
 fied plus or positively, when they contain a 
 greater quantity of the fluid than is natural 
 to them. 
 
 Pluviameter. (See Rain Gauge.) 
 Pneumatic Filterer. (See Palmer.) 
 Pneumatic Telegraph. An invention 
 of Mr. Crossley, for communicating signals 
 to a great distance by means of the impulse 
 given to a column of Water at one end of the 
 apparatus. 
 
 A is a cylinder of air at one extremity of 
 the line. C is supposed to be a distant 
 station. There is a tube which connects these 
 places. D the index at one of the stations. 
 Each cylinder or air vessel contains a little 
 water, with a pipe below the surface of it. 
 When the air at one end is compressed, the 
 compression extends equally throughout the 
 whole extent of the instrument, and the sur- 
 face of the water being pressed upon, it rises 
 in the gages or index tubes equally at all the 
 stations ; these being numbered, and the 
 numbers made representative of certain pre- 
 viously arranged signals, communication 
 is of course readily indicated. F is a funnel 
 supplying the water, to produce the proper 
 adjustment at first, and also if it should be- 
 come incorrect by leakage or accident. G a 
 pipe leading to a further station, capable of 
 
 being acted upon at the same time as the 
 second ; or by a cock, each may be shut off 
 as required. 
 
 Pneumatic Trough. A tin box, or 
 sometimes a tub or a basin, made so that a 
 shelf reaches half across it, inside and near 
 the top. The shelf is made with one or more 
 holes through it, and a funnel-shaped piece 
 of tin below. It is used to purify, cool, and 
 collect such gases as are not absorbable by 
 water. The following cut shows, at the 
 same time, a tin pneumatic trough and its use. 
 A is the trough, with sufficient water in it to 
 cover the shelf B ; the jar C being filled with 
 water, by immersing it sideways in the trough, 
 is turned upright, and slid upon the shelf, 
 and over the hole of it. D is a retort, in 
 which gas is being liberated. The gas passes 
 out of the beak of the retort, up through 
 the funnel into the jar, where it is I'etained ; 
 displacing tlie water from it, and occupying 
 its place. For such gases as are absorbable 
 by water, a mercury trough is used. 
 
 Pneumatics. That branch of natural phi- 
 losophy which treats of the weight, pressure, 
 elasticity, &c., of elastic fluids, but more 
 particularly of the air. Explainuig therefore 
 the action of aU those machines and pheno- 
 mena which depend for their action or solu- 
 tion upon the above cause ; such as the air- 
 pump, barometer, thermometer, pumps, 
 aerostation, sound, echoes, acoustics, &c. 
 
 Point. The smallest possible space or 
 magnitude, so small indeed as to be imaginary 
 rather than real, and to indicate a situation 
 rather than an entity. For example, the 
 ends of a line are points ; so also is the spot 
 in which two lines meet, provided those two 
 lines make an angle. Yet join the ends of 
 the lines together, forming a continued line 
 and the points no longer exist ; so also ma- 
 king an angle of two lines, the four points, 
 natural to two lines, become three points 
 only. Any number of lines may thus unite, 
 and their place of union will still be a single 
 point. Among artists, a point is understood 
 to be any sharp instrument applicable to 
 etching or tracing ; therefore called an etching 
 point, dry point, &c. Points, as occurring in 
 the arts and sciences, are of various denomi- 
 nations, meaning a particular position or 
 situation. Thus we have vanishing point in 
 
 V V 
 
PO 
 
 PO 
 
 perspective. Point of support and of con- 
 tact in mechanics. Point in the zodiac, as 
 the first point of Aries ; and numerous other 
 points in astronomy. Point, dot, or full 
 point in printing. Points or chief marks 
 upon the mariner's compass, &c. The melt- 
 ing and fusing points of solids, and boiling 
 and freezing points of liquids, are those 
 degrees of heat at which melting, fusing, 
 boiling, and freezing respectively commence. 
 In physics, the acting point is the exact 
 spot at which any impulse is given ; and the 
 point of incidence is where, by striking a 
 resisting or refracting surface, the motion is 
 changed in direction, or as relates to light, 
 we should say refracted. 
 
 Pointed Arch, Architecture, &c. 
 An arch pointed at the top, as is common 
 in the Gothic buildings of the middle ages ; 
 indeed so common as to have occasioned the 
 buildings, to which such arches were attached, 
 to assume so decided a character as to be 
 said to be built in the pointed style of archi- 
 tecture. 
 
 Pointing. A term applied to the finish- 
 ing of the external face of the several courses 
 of a wall. The common mortar is first 
 scraped out, and the joints and courses 
 cleaned, when they are filled up with fine 
 mortar or Roman cement. 
 
 Polar. Something situated near to the 
 poles of the earth, the poles of a magnet, &c., 
 or relating to such parts, as polar distance, 
 the distance of a place of a star, &c. from 
 the nearest pole of the earth. 
 
 Polar Circles. (See Circle.) 
 
 Polarisation of Light. The means or 
 method of changing common light into po- 
 larised light, which may be done as follows : — 
 Let A in the following cut be a plate of glass, 
 placed diagonally at the end of the tube M N, 
 80 that a ray of light, R A, striking against 
 A may be reflected along the axis of the tube. 
 At the end of another smaller tube N P, 
 which can turn round within M N, place a 
 similar plate of glass, capable of reflecting 
 the continued ray A C to the eye at E. If 
 a ray strike the first glass at an angle of 56°, 
 in a horizontal direction, and is reflected from 
 the second glass C, at a similar angle in a 
 vertical direction, it will become so weak as 
 to be scarcely visible ; but if the tube N P be 
 turned round, the ray C E will become 
 
 •.E 
 
 brighter and brighter, till it is thrown off 
 horizontally ; continuing to turn the tube, it 
 will at another quarter turn be again dim ; 
 at a third quarter it will become bright again, 
 and when turned round a whole circle it be- 
 comes, as at first, scarcely visible. This 
 turning of the apparatus is called polarising 
 of the light ; there are other ways of pola- 
 rising light. 
 
 Polarised Light. When the light of 
 the sun is reflected from certain bodies, at 
 particular angles, according to the nature of 
 those bodies, or transmitted through certain 
 transparent uncrystallised, and also through 
 doubly refractive crystals, and these various 
 bodies are turned round, it becomes in a 
 measure, decomposed, one side of the ray 
 of light presenting an appearance and pro- 
 perties different from the other ; these two 
 contrary sides are said to be the poles of the 
 ray, and the whole becomes polarised light. 
 
 Polarised Light, Colors of. Let there 
 be an apparatus constructed similar to that 
 last described, in which the light polarised 
 by the first plate, shown in the following 
 cut at A, which is called the polarising 
 plate, refuses to be reflected at C, or at the 
 analyzing plate, it being placed vertical to 
 the first. Let a strong sun-light fall upon 
 A ; then take a very thin film or slice of 
 sulphate of lime or mica D F G H, and hold 
 it or insert it between the two plates, where, 
 previous to the interposition of the crystal- 
 lised plates, the eye at E scarcely saw even 
 a glimpse of light, it will now see the most 
 vivid, the richest, and most varied hues, and 
 following one another, according to the 
 thickness of the crystal, or the manner in 
 which it is held. If the crystal be turned 
 round while in this situation, the colors will 
 change at every quarter turn, becoming at 
 one time green, at the next red, and so on. 
 
 Polarising Apparatus. Polariscope. 
 Any instrument which is capable of showing 
 the phenomena of polarised light, such aa 
 that already described, or that which follows. 
 
 Polariscope, Oxy -Hydro. This is an 
 apparatus to show the phenomena of pola- 
 risation of light to a number of persons at 
 once. The name implies that the light de- 
 composed is produced by the united effect of 
 burning the two gases named. The burn- 
 ing gas is thrown upon lirae, exactly as 
 shown under Oxy-Hydro Microscope. The 
 polarising apparatus is in principle what has 
 
PO 
 
 PO 
 
 been already described ; but having magni- 
 fying lenses attached, it is capable of being 
 thrown upon an extended screen at a distance. 
 Suppose A A to be screwed on to the front 
 of a magic lanthorn, or oxy-hydrogen micro- 
 scope box, instead of the usual nozzle — the 
 light would pass through the two lenses 
 B and C, and be reflected from and polarised 
 at D, which is a bundle of glass plates. 
 Passing along the tube, it is again reflected 
 at G ; another bundle of glass plates, pre- 
 viously, however, passing through the lenses 
 under F. Finally it is thrown on to a screen 
 from G. Into the hole E is placed the film 
 of crystal, from which the colors are to be 
 thrown. 
 
 Polarity. The quality of a thing having 
 poles, or a tendency to turn itself into a 
 certain position, but more particularly used, 
 in reference to the magnet, to an electrical 
 apparatus, to certain modifications of light. 
 Sec. (See Pole and Polarisation.) 
 
 Pole. In geography and astronomy, a 
 point at 90° distant from a plane, made by 
 one of the circles of the globe, or opposite 
 to that point in the heavens, as the pole of' 
 the equator is 90° distant from every part of 
 the equator, and corresponds to the poles of 
 the earth, which are the extremities of that 
 line upon which the earth turns in its daily 
 rotation ; that pointing to the north part 
 of the heavens being called the arctic or 
 north pole ; the contrary one having the 
 name of the antarctic or south pole. The 
 poles of the ecliptic are also 90° from every 
 part of this circle, and as the obliquity of it 
 is 23i° from the equator, its poles will be 
 23i° from those of the earth. The'poles of 
 the horizon are the zenith and the nadir. 
 The poles of a magnet are the points of its 
 greatest attraction and repulsion. (See 
 Magnet.) The jwles of a galvanic series 
 are the extreme plates, or the ends of the 
 series, one being called the cathode or ne- 
 gative pole, and the other the anode or 
 positive pole. For pole star, (see North 
 Star.) 
 
 Pole Lathe. This is the simplest of all 
 lathes ; it is adapted only for common work, 
 and such as does not require much strength. 
 Its structure is as follows :— A is supposed 
 to be an elastic pole, about the size and 
 length of the shaft of a chaise. One end 
 
 of the pole is fixed to a distant part of the 
 ceiling or a beam. The other end bears a 
 string, as E. This is twisted once or twice 
 round the wood to be turned D, and its lower 
 end fastened to a treadle F. The wood is 
 supported between two pivots, formed by the 
 ends of the screws, which are in the poppets 
 C C. One of these poppets is fixed ; the 
 other moveable along the bed, as explained 
 under Poppet, (which see.) The rest is not 
 shown, as it differs in no respect from that 
 explained under Lathe, except that very 
 often a board is fastened from one poppet to 
 the other, at the proper height, for long 
 work, and upon the upper edge of this, the 
 tools are rested. 
 
 Pole Plate. A beam of timber placed 
 along a wall, and on the top of the ends of 
 the various tie-beams. (See Roof.) 
 
 PoLEMOscoPE. A reflective perspective 
 glass, invented by Hevelius, who recommends 
 it as useful in sieges, &c., for discovering 
 what the enemy is doing, while the spectator 
 is hid behind an obstacle. It is, however, 
 more used as a toy, or by lecturers to illus- 
 trate the phenomena of reflection. The an- 
 nexed is a section of the instrument ; it con- 
 sists of a rectangular box, 2 or 3 inches 
 square, bent four times at right angles, and 
 containing at those angles four looking 
 glasses, placed at the angle of 135" with the 
 adjacent sides. Suppose a ray of light to 
 enter at A, it would impinge upon B, and be 
 there reflected to C. At C a second reflec- 
 tion takes place, which passes the light to D. 
 A third reflection carries it to E, and a fourth 
 
PO 
 
 PO 
 
 reflection sends it to the eye. It is evident 
 the instrument will act equally well when a 
 solid is interposed between the one arm or 
 extremity and the other. 
 
 Poling of Copper. The stirring up of 
 the fused copper during its first manufacture 
 with a pole, generally of birch-wood, whereby 
 it acquires considerable tenacity and tough- 
 ness. The reason of this effect has not 
 been satisfactorily explained, but is supposed 
 to arise from the pole separating from 
 the mass a small portion of the oxyde of 
 copper. 
 
 PoLiNGS. The small boards supporting the 
 earth during the formation of a tunnel. 
 
 Polisher. Synonymous with burnisher. 
 
 Polishing. The art of giving a lustre or 
 gloss to a thing, whether of stone, wood, 
 metal, or other material. 
 
 PoLLENiN. A peculiar principle found in 
 the pollen of flowers. 
 
 PoLYACOusTic. Any thing that multiplies 
 sound, as a whispering gallery. 
 
 PoLYCHREST Salt. An old name for a 
 salt, once used in medicine, consisting of a 
 mixture of the sulphate and the sulphite of 
 potass ; procured by sprinkling powdered 
 sulphur upon hot nitre. 
 
 PoLYCHROiTE. The coloring matter of 
 saffron. 
 
 PoLYEDRON. (See Polyhedron.) 
 
 PoLYFOiLE. An ornament, like a leaf, of 
 many round lobes. (See Multifoile.) 
 
 Polygon. A figure of many sides and 
 angles ; if the sides and angles are equal it is 
 called a regular polygon. They are dis- 
 tinguished according to the number of then- 
 sides, as a pentagon, a hexagon, &c. 
 
 j/olygonometry. The art of measuring 
 polygons, regular and irregular, from a con- 
 sideration of their angles. 
 
 Polygram. In geometry, a figure con- 
 sisting of many lines ; a word now disused. 
 
 Polyhedron. Polyedron. A figure com- 
 prehended under many sides ; such as the 
 cube, icosaedron, octahedron, &c. 
 
 Polyhedron, Gnomomcal. A stone with 
 several faces, on which are projected many 
 kinds of dials. 
 
 Polynomial. In algebra, a quantity con- 
 sisting of many terms. 
 
 Polyscope. In optics, a multiplying 
 glass, or one which represents a single object 
 to the eye as if there were many. It con- 
 sists of several plane surfaces disposed under 
 a convex form, through each of which the 
 object is seen. 
 
 PoLYSTYLE. An cdificcwithmany columus. 
 
 Poppet, or Back Poppet. That part of 
 a lathe which holds that end of the work to 
 be turned which is farthest removed from 
 the mandril ; or in the pole lathe, which 
 holds both ends of such work. In the 
 common wooden-bedded lathes, the back 
 poppet is very simple. It is represented in 
 fig. 1, below, and consists of a block of 
 wood, cut as represented, with a hand-screw 
 pointed at the end, passing through it at the 
 exact height of the nose of the mandril. It 
 is fixed to its situation by the lower part 
 being cut with a shoulder that rests on the 
 upper face of the bed, and the tenon passing 
 through between the cheeks receives a wedge 
 into a mortice hole made below, which fixes 
 the whole poppet tightly. Fig. 2 shows a 
 poppet on a superior construction. A is a 
 round rod of steel sliding in and out of a 
 shoulder on the top of the iron upright E. 
 To the back of this upright is screwed a 
 frame D, intended for the support of a 
 second socket, which is tapped to receive 
 the screw B. This screw propels the steel 
 rod forward, when required. F is supposed 
 to be a triangular bar, forming the bed of 
 the lathe ; and G the screw which fastens 
 the whole poppet firmly to the bed. The 
 screw C is to hold the steel rod when set at 
 its proper distance. 
 
 Polyzonal. Composed of many zones or 
 belts. The term is particularly applied to 
 certain lenses, which are of such large di- 
 mensions that they cannot be cast in a single 
 piece ; such an one is described under the 
 word Buffon. 
 
 Pomel. a globular protuberance, or knob, 
 terminating a pinnacle, or similar ornament. 
 
PO 
 
 PO 
 
 PoMPHOLix. White oxyde of zinc. 
 
 Ponderability, is that quality of bodies 
 that relates to sensible weight. Every body 
 in nature possesses ponderability, that is, we 
 are capable of weighing aU bodies, except 
 light, heat, and electricity, which are there- 
 fore called the three imponderable bodies. 
 Magnetism, being supposed identical with 
 the last of these, is included in it. 
 
 PoNDERATiON. In sculpturc, painting, 
 &c., is the proper balancing or supporting a 
 figure or object, so that it shall not have the 
 appearance of instability or tottering. 
 
 Ponderous Spar. Any natural combi- 
 nation of barytes, particularly the carbonate 
 and the sulphate. 
 
 Poppy Head. The top of the boards 
 which form the ends of seats in churches, &c. 
 Some of these made in the middle ages are 
 extremely ornamental. 
 
 Poppy Oil. An oil much used by the ar- 
 tist, particularly for very light and delicate 
 colors ; it not being so apt to turn yellow by 
 age as linseed oil. 
 
 PopuLiN. A peculiar substance, found in 
 the bark of the poplar, and also several of 
 the willows ; called also salicin. 
 
 Porcelain. A beautiful species of ear- 
 thenware, which is, at the same time, clear in 
 color, hard, and semi-transparent. From its 
 being once brought principally from China, 
 it is often called by the name of that country. 
 The clay which forms the most necessary in- 
 gredient, called kaolin, was once only known 
 to be natural to China ; but as it is now 
 found in considerable abundance in England, 
 and on the Continent of Europe, porcelain 
 is manufactured in many other places. 
 
 Porch. A vestibule, projecting before the 
 walls of a building, and usually supported 
 by columns or pillars. 
 
 Pores. The small interstices between the 
 Bolid parts of bodies. 
 
 PoRiME. PoRiMA. PoRiSM. An axiom, or 
 what is self evident ; also a geometrical pro- 
 position proved with such evident force as to 
 be not merely beyond a cavil, but which 
 may be made a foundation or argument for 
 other geometrical propositions not otherwise 
 easy of solution. 
 
 Porosity. The quality of being porous ; 
 a term generally considered as contrary to 
 compactness or density. Porosity is ascer- 
 tained by the capability of the body to im- 
 bibe moisture. 
 
 Porphyry. A denomination that dis- 
 tinguishes a large class of primitive rocks. 
 There are several kinds, varying in color 
 and degree of hardness. It is used in build- 
 ing, for columns, statues, &c. 
 
 Portal. The arch over a door or gate- 
 way, the frame-work of a gateway, s, smaller 
 gate, where there are two of different di- 
 mensions, &c. 
 
 Portcrayon. A pencil case ; an instru- 
 ment serving to inclose a crayon or chalk 
 pencil, and occasionally used as a handle for 
 holding it. 
 
 Portcullis. A frame of iron or wooden 
 bars placed over a gateway, to let down as a 
 protection to the gate. It is also often an 
 architectural ornament. 
 
 Portico. 
 
 building. 
 
 The columns at the end of a 
 
 Portland Stone. An alkaline sandstone 
 of a dull, whitish color, heavy, moderately 
 hard, and composed of a large roundish 
 grit. It is one of the numerous varieties of 
 oolite. It is soft when first taken from the 
 quarry, but afterwards acquires considerable 
 hardness. It is much used in building. 
 The greater part of Westminster Bridge is 
 built with it. 
 
 Portrait. The delineation of a person's 
 face, &c. 
 
 Portrait Painting. The art of painting 
 portraits. 
 
 Position. Situation, or bearing of any 
 thing ; used in the mathematics and arts in 
 contra-distinction to magnitude, as the po- 
 
PO 
 
 PO 
 
 sition of a line, of an object, &c. has no 
 reference to its size or other properties. 
 Position, in astronomy, relates to the 
 sphere or globe, which is either in right, 
 parallel, or oblique position, whence arise 
 inequality of days, the difference of seasons, 
 &c. Position, in arithmetic, is a rule so 
 called, because to procure a correct answer 
 to a question, we suppose a certain number 
 to be the true one, and make this a support 
 for, or a position whence to proceed in the 
 required calculation ; and as this number is 
 taken at random, it will, most probably, be 
 an erroneous one — hence the rule was 
 formerly called the rule of false. It is 
 divided into single and double position. 
 
 Positive. In electricity ; (See Franklin'' s 
 Hypothesis.) In algebra, those qualities are 
 called positive which have the sign 2)lus + 
 before them, and which therefore indicate 
 that they are to be added to the rest. 
 
 Positive Axis of Refraction. (See 
 Negative. ) 
 
 Post. In building, a large piece of timber, 
 placed upright, either alone, or to support 
 other parts. (See Roof.) 
 
 PosTicuM. A portico at the back or rear 
 of a temple. 
 
 PosTiauE. An ornament of sculpture is 
 said to be postique, when it is superadded 
 after the work itself is done. 
 
 Postulate. In geometry, a thing which 
 is granted or allowed to be done without 
 aasigning a reason for, or giving an expla- 
 nation of the manner of doing it. For ex- 
 ample, a circle may be made from any cen- 
 tre ; a line may be made from one point to 
 another, or may be produced at either end, 
 without explaining how ; the method of doing 
 so being self evident. 
 
 Potash, or Potassa. The protoxyde of 
 potassium. It is called the vegetable alkali 
 from its strongly alkaline properties, and its 
 being inherent in vegetables, from whence it 
 is obtained by burning them, and lixiviating 
 the ashes, and afterwards concentrating the 
 lixivium which contains the alkali, by boiling 
 and leaving it to crystallize. Potash is solid 
 when dry, rapidly deliquesces in a moist at- 
 mosphere, is soluble in half its weight of 
 water ; soluble also in alcohol. It destroys 
 all animal textures, changes most vegetable 
 blues to green, and the yellow of turmeric to 
 brown. 
 
 Potassium. A metallic substance, the base 
 of potash ; first procured by Sir H. Davy, by 
 submitting pure potash in small quantities 
 to the action of a powerful galvanic battery, 
 when the potash became decomposed, yielding 
 oxygen to the one pole, and potassium to the 
 other. Potassium is white, of metallic bril- 
 liancy, and so soft as to be cut easily with a 
 knife. A grain of it dropped into water, or 
 suspended in a iar of oxygen gas, so rapidly 
 
 unites with the oxygen, as to burst into 
 flame, becoming, at the same time, in the 
 one case, the protoxyde ; and in the other, 
 the peroxyde of potassium. It melts at 150^^, 
 is considerably lighter than water, opaqne, 
 and a good conductor of electricity. It com- 
 bines not merely with oxygen, but with 
 chlorine, iodine, hydrogen, sulphur, and 
 phosphorus. 
 
 Potential Cautery. Caustic potash. 
 Pot Metal. A species of stained glass, 
 in which the colors have been incorporated 
 while the glass was in a state of fusion. 
 
 Pottery. The manufacture of all kinds 
 of earthenware, particularly such articles as 
 are common, whether for domestic or manu- 
 facturing purposes, as crockery, garden pots, 
 sugar pans, crucibles, &c. ; and also Wedg- 
 wood, porcelain, biscuit and other ware, of 
 a better description, glazed or unglazed. 
 
 Pounce. Gum sandarac, pounded and 
 sifted very fine ; mixed or not with the fine 
 powder of the cuttle fish bone, and used for 
 rubbing on paper, to prevent the writing 
 from sinking or blotting. 
 
 PouNXA. Impure borate of soda, as im- 
 ported from India. 
 
 Powder, Fulminating. (See Fulminating.) 
 Powder of Algaroth. The white oxyde 
 of antimony, thrown down from the muriate 
 by water. 
 
 Powder of Projection. (See PhilO' 
 sopher's Stone.) 
 
 Powder House. An electrical apparatus, 
 to show, in an amusing manner, the firing of 
 gunpowder by electricity, and thereby proving 
 the effect of lightning upon buildings in 
 setting them on fire. The house itself is 
 made of seven pieces of mahogany, joined 
 together by hinges, so as to be capable of 
 falling flat on the table ; a small projecting 
 ridge along the top of the roof holding it up 
 until the powder is fired. The scientific 
 part of the apparatus is seen by the letters, i 
 A is a ball of brass with wire reaching partly 1 
 down the house, and across it, inside to the 
 brass top of the table C. This has the gun- 
 powder placed upon it. Immediately above 
 the powder is a second ball, which leads by 
 a wire to the outside of the house at the 
 
PR 
 
 PR 
 
 opposite end, passing through the wood at 
 the end of the house. Then follows the 
 wetted thread E, and afterwards the chain B. 
 Passing an electrical shock from A to B, the 
 powder will be fired and the house thrown 
 down. 
 
 PowDERiNGS. A term sometimes used 
 for devices serving to fill up vacant spaces in 
 carved work, as also in escutcheons, writings, 
 &c. 
 
 Power. In mechanics, is, as Mr. Smeaton 
 defines, the exertion of strength, gravitation, 
 impulse, or pressure, so as to produce mo- 
 tion in what is previously at rest, called 
 therefore a moving power ; or else to retard 
 the motion of such things as are acted upon 
 by the moving power ; this is called the 
 sttstaining or restraining power. For exam- 
 ple, in throwing a stone up into the air, the 
 hand is the moving power, and gravitation, by 
 retarding it, is the restraining power. Ac- 
 cording to the origin of it, it is either animal ; 
 natural, as proceeding from water, air, &c, , 
 or mechanical, arising from steam, &c. 
 
 Power. In mathematics, is that which 
 arises from the continued multiplication of a 
 number or quantity, and is named according 
 to the number of multiplications ; thus 2 
 standing alone is th© first power ; 2 x 2 = 4 is 
 the square or second power ; 2x2x2 = 8 is 
 the cube or third power ; 2x2x2x2 = 16 is 
 the biquadrate or fourth power of 2 ; and so 
 on for higher powers. The power is often 
 indicated by a small figure or exponent, at- 
 tached to the factor, as x, x^, ,r^, .r* ; and 
 2, 22, 23, 2*, signify the first, second, third, 
 and fourth powers of x and 2. 
 
 Power. In optics, expresses the effect 
 producible by lenses, or other instruments, 
 as magnifying power, heating power, illu- 
 minating power, &c. 
 
 Practice. An arithmetical rule, prin- 
 cipally employed in ascertaining the value of 
 a number of articles at so much each, being 
 therefore a compendious form of compound 
 multiplication. There are numerous cases 
 or divisions of the rule, according to the 
 amount of the price, whether it be under a 
 penny ; more than a penny, and under a 
 shilling ; between a shilling and a pound ; 
 or consistmg of several pounds, and smaller 
 monies. The same rule may be applied to 
 weights and measures. 
 
 Precession of the Equinoxes, is a 
 slow retrograde motion of the equinoctial 
 points: viz., from east to west, or contrary 
 to the order of the signs. In consequence 
 of this motion the sun crosses the equator 
 at different points each succeeding year, 
 which points are distant from those of last 
 year about 53^". Dividing 360° by this it 
 will be found that the sun does not return 
 exactly to the same spot again at the same 
 season until after 25745 years. In con- 
 
 sequence of this, the earth's equator is 
 yearly changing its position in reference to 
 the ecliptic, which latter is fixed; or in other 
 words, the equator, and consequently the 
 axis of the earth, is continually altering its 
 inclination to the plane of the earth's orbit, 
 and the pole of the earth will, in the 25745 
 years before mentioned, make a complete 
 revolution in a circle, the radius of which is 
 equal to the obliquity of the equator, or 
 23° 28': therefore, every part of the equator 
 will, in the course of the above period, re- 
 present each equinox, and also represent 
 the solstices, and the seasons will also make 
 a complete revolution in the same period, 
 that which is now mid-winter being in 
 12872 years hence the height of summer. 
 The cause of the precession of the equinoxes 
 is the attraction of the sun and moon upon 
 the mass of matter which is accumulated • 
 around the equatorial regions, rendering the 
 earth an oblate spheroid. 
 
 Precipitate. Precipitation. The sub- 
 sidence or settlement of a powder at the 
 bottom of a fluid in which it has been dis- 
 solved or suspended, while the precipitate is 
 the powder so separated. 
 
 Precipitate per se, or Red Precipi- 
 tate. Red oxyde of mercury procured by 
 heat. 
 
 Press. An instrument for exerting and 
 continuing a pressure upon any article or 
 substance placed within it, for the purpose 
 of smoothing, flattening, drying, embossing, 
 printing from, or diminishing the size of the 
 matter subjected to the pressure. So general a 
 definition includes a vast number of machines, 
 named according to the purposes to which 
 they are applied; thus we have cheese press, 
 wine press, printing press, &c. The principles 
 upon which the whole are constructed are 
 four, as will be seen in the following ex- 
 amples : — 
 
 The lever press consists of a long lever, 
 bearing upon a strong gudgeon that runs 
 between two uprights. There are holes at 
 different distances along these uprights, that 
 the gudgeon may be shifted according to the 
 thickness of the matter to be pressed. There 
 is a foot-board to the whole, and often 
 wheels ; the material being placed under the 
 lever and near the fulcrum, with or without 
 a board on the top of it, is pressed by human 
 
PR 
 
 PR 
 
 power, or else by a weight suspended from 
 the far end of the lever, which may be of 
 any length. This press is adapted to com- 
 press peat, cheese, earth, corks, &c. 
 
 The dead-weight, or cheese press, has an 
 immense block of wood B, or a large box 
 filled with stones, suspended by a screw C. 
 
 This passes through a hole in the upper bar 
 of the frame, and has a large nut D with 
 handles that rests on this bar. Suppose a 
 cheese or other matter to be placed on the 
 lower board A ; upon turning the nut D in the 
 proper direction, the block B would be let 
 down, and removing D entirely away, or to 
 some distance from the bar, the block B 
 would continue to exert a pressure equal to 
 its weight for any length of time ; the pressure 
 continuing the same, notwithstanding the 
 shrinking of the substance pressed upon. 
 
 The screw press is of very different con- 
 struction ; here the power obtained is very 
 great, but if it be required to press a shrink- 
 
 ing substance, the pressure diminishes, and 
 finally ceases altogether, unless attention is 
 paid to work the screw. A A A A is a strong 
 frame-work, sometimes of iron, at others of 
 wood, as are also the other parts. B is the 
 screw — it passes through a female screw in 
 the upper board A, and is fastened below, 
 (so however as to have freedom of circular 
 motion) to the upper board of the press. 
 Turning the iron lever C, by means of manual 
 labor, draws up or down the screw B, and of 
 course with it the upper board, thus increasing 
 or diminishing the pressure, as required. 
 This press is often called the standing press. 
 (See Standing Press.) 
 
 The rolling press consists of one hard sub- 
 stance rolling upon another, the pressure 
 being exerted upon whatever lies between 
 them, and continuing only while the wheel 
 continues in motion, unless indeed at a sin- 
 gle line, should the roller be suffered to rest. 
 The most valuable is, perhaps, the copper- 
 plate press, described under the word /?o//m^. 
 The most familiar examples are the garden 
 and field i-ollers, the mangle, and the crimping 
 board. There are numerous machines of 
 this nature, also called mills ; as the cyder 
 mill, the whitemng mill, &c. All these 
 would become presses, ' were the material 
 acted upon merely smoothed or flattened, 
 rather than crushed. 
 
 The wheel and pinion press, which is the 
 invention of a Mr. Baird, is an extremely 
 useful press for many purposes, though the 
 power is not very great ; yet as it may be 
 continued or not, as required, it is valuable 
 as a wine or cheese press. It is as follows : — 
 
 A and B are the bottom and top plates ; the 
 lower being fixed — the upper moveable. 
 
PR 
 
 PR 
 
 There are two ways of moving this upper 
 plate ; one quick and easy, until the resistance 
 becomes great ; and the other slower, but 
 more powerful, and used for the conclusion 
 of the operation. On the axis of the wheel 
 C there is a pinion of eight teeth, (not seen 
 in the engraving,) which works in the rack D. 
 On the further end of the axis E there is a 
 second pinion of eight teeth, (concealed in 
 ihe engraving by the other parts,) which 
 acts in the wheel C of twenty-four teeth. 
 I'his axis E may be turned by the winch 
 handle H ; three turns of which will make the 
 rack descend through a space equal to eight 
 of the teeth in the wheel C. In this way 
 the plate B is made to descend at first, but 
 when the pressure becomes great, the lever 
 must be resorted to. This lever I is forked 
 at the end F, and fits loosely on the axis E ; 
 one of the forks being on each side of the 
 ratchet wheel F. The upper part of the lever 
 having a pall or click on the top, this 
 catching the teeth of the wheel F turns it 
 round a certain portion ; according as the 
 lever is worked, a second pall or click behind 
 F keeping it from returning when a second 
 stroke is made with the lever. If it be de- 
 sired to continue the first given degree of 
 pressure, the lever I is i-aised considerably 
 above the horizontal position, and a weight 
 W attached to it; as the material below 
 shrinks, the lever descends until stopped by 
 the pin, which is inserted in the frame-work, 
 or lower than this if the pin be taken out. 
 For other presses, (see Bramah, Copying, 
 Hunter, Lithographic, Printing, Ruthven, 
 Stanhope, Straker, ^e.) 
 
 Press, Hydrostatic. (See Bramah.) 
 Pressure. Weight, or a continued power 
 or exertion of force. 
 
 Primative Colors. The same as pris- 
 matic colors. These, although formerly con- 
 sidered as seven in number, are more pro- 
 perly restricted to three ; namely, red, yel- 
 low, and blue, from the mixtures and com- 
 binations of which all the other colors, tints, 
 and gradations, are composed ; white being 
 a combination of all these, and black a total 
 deprivation of color. This, although true 
 in nature, is not true in art. In solar light 
 there are three primative colors, as above 
 stated. The mixture of the red and yellow 
 producing orange ; of the yellow and blue, 
 green ; of the blue and red, a purple or violet ; 
 and these of various degrees of tint, according 
 to the proportion of one or other of the 
 colors. But there are numerous tints to which 
 other colors must be added to produce them 
 artificially ; thus red and black constitutes 
 brown ; black and green, or brown and green, 
 an olive ; brown and red, a chocolate ; a 
 white is no less necessary to produce salmon 
 color, pink or flesh color, straw color, stone 
 cobr, &c. 
 
 Primative Form of Crystals. When 
 crystals are split in their cleavage planes es 
 much as possible, and then their angles 
 examined by the goniometer, they will be found 
 to present one or other of the regular bodies, 
 which are called their primitive forms. They 
 are the cube, the tetrahedron, theoctaedron, 
 the hexangular prism, the rhombic dodeca- 
 hedron, and the dodecahedron, with isosceles 
 triangular faces. 
 
 Prime Figure. In geometry, one that 
 cannot be divided into any other figures more 
 simple than itself. Such are a triangle and a 
 pyramid. 
 
 Prime Numbers, Those which cannot be 
 divided into equal integral parts, less than 
 the numbers of units of which they are com- 
 posed. Such are 2, 3, 5, 7, 11, 13, 17, 19, 
 23, &c. 
 
 Prime Vertical, is that vertical circle 
 or azimuth, which is perpendicular to the 
 meridian, and passes through the east and 
 west of the horizon. 
 
 Prime Vertical Dials, are those which 
 are projected on the plane of the prime ver- 
 tical circle, or in a plane parallel to it. These 
 are likewise called direct, erect, north and 
 south dials, &c. 
 
 Prime of the Moon, is the new moon 
 at her first appearance, until about three days 
 old. It also means the golden number. 
 
 Primum Mobile. (See Ptolemy.) 
 
 Priming. Among painters, the laying on 
 of the first color. Priming, in engineering, 
 is the name given to the hot water which is 
 carried along with the steam into the cylinder 
 of the steam engine. 
 
 Prince Rupert's Drops. Drops of 
 green glass, suddenly cooled by letting them 
 fall into water. As soon as the small end is 
 broken off", they immediately fall into dust, 
 with an explosion. The exact cause of this 
 has never been satisfactorily explained. 
 
 Prince's Metal, or Prince Rupert's 
 Metal. An alloy of 3 ounces of copper to 
 1 of zinc. 
 
 Principal. The chief object proposed, 
 delineated, or constructed, and to which all 
 the other parts are subservient. Principal, 
 in arithmetic, any sum of money lent on in- 
 terest, either simple or compound. 
 
 Principle of D'Alembert. (See 
 D^Alembert.) 
 
 Principle of Virtual Velocities. 
 When a system of material points, elicited 
 by any force, is in equilibrium, if the system 
 receive a small alteration in its position, by 
 virtue of which every point describes an in- 
 finitely small space ; the sum of each force 
 multiplied by the space described by the 
 point to which it is applied, according to the 
 direction of the force is always equal to zero. 
 Tliis is called the general principle of virtual 
 velocities. 
 
pp 
 
 PR 
 
 Printing. The art of taking copies by 
 impression of type, drawings on stone, en- 
 graved blocks, plates, or rollers, in inks, 
 J igments, dyes, &c. Thus we have letter- 
 press printing, calico or roller printing, pa- 
 per staining or printing, copper-plate print- 
 ing, lithography, and many other styles ; but 
 the word printing, standing alone, without 
 any distiuctiye addition, is usually understood 
 to imply typography, or printing from type, 
 commonly called letter-press printing. In 
 the other kinds of printing, the preparer of 
 the plates, rollers, blocks, &c., is mostly a 
 different person from him who really prints 
 from them, yet in the letter-press work the 
 same tradesman conducts the whole process, 
 and which may be briefly described as fol- 
 lows * — The type is received from the type- 
 founder, and distributed in cases, where each 
 letter has a separate box for itself; those 
 most wanted being nearest the hand. The 
 compositor taking a composing stick in his 
 left hand, first sets it to the requisite measure 
 or width. He then picks up the required 
 letters from the cases, one by one, and ar- 
 ranges them in order, until he has one line 
 complete, adding during his progress spaces 
 between the letters, and such others after- 
 wards as exactly fill up the line ; another, 
 and afterwards a third, fourth, and fifth line 
 is proceeded with in the same manner. The 
 lines thus set up aie then placed on a board, 
 called a galley. When sufficient progress 
 has been made, the quantity requisite for a 
 page is tied up with a thin twine, and when a 
 sufficient number of pages are thus complete, 
 they are put in proper positions with each 
 otlier on a flat stone ; a chase or iron frame 
 is put over them — long pieces of wood, called 
 furniture, are put around each page, and 
 wedges, called quoins, are driven tightly, at 
 various places around, to keep the whole in 
 their places. The chase with the pages in it 
 is called a form. It is taken to the press, 
 properly adjusted, inked by dabbing it with 
 an inking ball or roller, and the paper being 
 placed upon it, the press is pulled down, and 
 an impression taken. The whole number of 
 prints being taken off, the form is washed 
 with potash lye, to cleanse it of superfluous 
 ink ; it is unlocked or unfastened, and the 
 type by little and little distributed, or placed 
 in the cases, as at first, ready for other work. 
 
 Printing Apparatus. For other appa- 
 ratus belonging to the art of printing, (see 
 Ball, Composing Stick, Inking Table, ^c.) 
 
 Printing Ink. The ink used by the prin- 
 ter. It is of two kinds ; one used by the 
 Cwpner-plate printer and the other by the type 
 printer— each kind being made of various 
 colors. Conper-plate ink is mostly made 
 extemporaneously by the printer^ of Frank- 
 fort black, mixed witii uryii.g linseed oil, or 
 linseed oil boiled until it is quite thick and 
 
 brown. Lithographic printing ink diflfers tn 
 no respect from the preceding, except in 
 being used of different degrees of thickness, 
 according to the work to be executed. For 
 a fine ink, adapted to letter-press work, 
 Mr. Savage gives the following receipt : — 
 Balsam of capivi, 9 oz. ; lamp black, H oz. ; 
 indigo and Pi'ussian blue, together, 14: oz. ; 
 Indian red, f oz. ; dry yellow soap, 3 oz. 
 Printing Press. An instrument used to 
 produce impressions from properly-arranged 
 types, engraved plates, or painted stones, 
 called according to the use to be made of 
 them respectively, the letter-press; the 
 rolling press, or the copper-plate press ; 
 and the lithographic press. The two last 
 are described under the words RolVmg and 
 Lithographic. The first is alone referred to 
 in the following explanations : — All the 
 presses used by the letter-press printer, ex- 
 cept that called the Ruthven press, are acte 1 
 upon by manual power applied at the end oi 
 a lever, by a stroke similar to that of rowing. 
 The power is continued to the surface of the 
 type, where it is alone required, by means of 
 other levers connected with the first lever or 
 handle. The wooden j-^res* is the most 
 ancient, being that used by the first printers, 
 and no alteration having been made in it till 
 a very recent period ; and though far inferior 
 to the modern iron presses, yet, as it is 
 much cheaper, the v»'Ooden press is still much 
 used in country and small offices. The 
 annexed cut shows its form and principle. 
 
 The frame-work A A A A is made strongly 
 of wood, and fastened to the floor. B is 
 called the platten — it is a square block of 
 mahogany or other hard wood, hung by four 
 small hooks to what is called the hose, which 
 is a square trunk in which the spindle D fits. 
 This spindle is made conical at the lower 
 end, so that when pressed down, it presses 
 down at the same time the hose and the 
 platten, and when drawn up, it is prevented 
 from leaving the hose by a pin or a strap, 
 called the garter, which fits into a groove 
 cut round the spindle ; thus the spindle may 
 
PR 
 
 PR 
 
 turn round, yet not be drawn out without 
 removing the garter. The spindle has on 
 the upper part of it a screw which fits into 
 a contrary screw cut in the cross bar of wood 
 immediately above it, which is called the 
 head of the press. The lower part of the 
 press consists of the frame-work, called the 
 carriage^ G. The part marked H is called 
 the bed. It consists of a large and very flat 
 stone, imbedded in a frame called the coffin, 
 made of wood, and strengthened with clamps 
 of iron at the corners. This may be run 
 under or away from the platten by means of 
 a strap fastened at each end, and passing 
 around a roller beneath the carriage, which 
 is worked by a handle at the side. I is 
 called the tympan — it consists of two frames 
 covered with parchment, and with two or 
 more folds of flannel between them ; this is 
 fastened to the coffin by pivot joints, or by 
 hinges, and rests upon a frame called the 
 gallovis. K is the frisket, which is a light 
 iron frame, mostly with strings across it to 
 hold the paper steady, and paper fastened on 
 it to keep the margins, &c. clean. The 
 pressman having damped paper at the side 
 of him, on a table, called a bank, and having 
 placed the form of type on the stone, inks 
 the type, takes a sheet of paper, places it 
 carefully on the tympan, turns down the 
 frisket over it, then turns both down upon 
 the face of the type, rolls the coffin under 
 the platten, j)ulls the handle once or twice, 
 runs the coffin out again, and turning up the 
 tympan and frisket, finds the sheet of paper 
 printed. The chief iron presses now in use, 
 are the Stanhope, the Ruthven, (see Stan- 
 hope and Ruthven,) the Columbian, the 
 Imperial, and the Albion. 
 
 The Columbian printing press is considered 
 more powerful than any other. It was the 
 invention of Mr. Clymer, a North American, 
 in 1817. The whole of the press is of solid 
 iron. The under surface of the platten and 
 
 ; upper surface of the table are turned truly 
 I flat in a lathe. The tympan has a counter- 
 poise weight attached to the lower end, to 
 assist in lifting it up. The carriage con- 
 sists of two ribs, as is seen more clearly in 
 the Albion press. The leverage to produce 
 the pull is of the greatest power. It consists 
 of four levers acting upon each other, not 
 merely pressing down the platten, but lifting 
 up the counterpoise lever, (that which Dears 
 the eagle.) This falling down again, draws 
 the platten up and the handle back, ready 
 for the next pull. 
 
 The Albion press is another most valuable 
 instrument ; it is lighter and neater, more 
 easy to work, and of a power nearly, if not 
 quite equal, to that of the Columbian. It is 
 the invention of Mr. Cope, of London, but has 
 been greatly improved by Mr. Hopkinson. It 
 consists of feet, staple, and other parts con- 
 stituting the frame-work ; platten, table, 
 tympan, &c. Its power is a very simple 
 combination of levers, which are mostly in- 
 closed in the head of tlie press. The platten 
 rises in consequence of a spring being 
 contained in the box at the top, which is 
 connected with the top of the spiudle. 
 
 Printer's Types, Metal for. Melt 
 together 10 lbs. of lead and 2 of antimony. 
 Each founder, however, has his own receipt. 
 The following is recommended for small type : 
 — Melt 9 lbs. of lead, and when melted add 
 2 lbs. of antimony and 1 lb. of bismuth. 
 
 Prism. A geometrical figure or solid, whose 
 two ends are parallel, equal, and straight, 
 and whose sides are rectangles joining these. 
 Hence every section parallel to the base is 
 equal and similar to the base. Prisms re- 
 m- e particular names, according to the figure 
 of their bases ; as a triangular prism ; a 
 
PR 
 
 PR 
 
 square prism ; an hexagonal prism ; and so 
 on. Also a prism may be either regular or 
 irregular, according as its ends are regular or 
 irregular polygons. 
 
 Prism. In optics, is an instrument em- 
 ployed for showing the properties of solar 
 light ; and consists merely of a triangular 
 prism of glass, which separates the rays of 
 ligbt in their passage through it, in conse- 
 quence of the different degrees of refrangi- 
 bility that has place in the component part 
 of the same ray. It is by means of this in- 
 strument, that the origin of colors is shown 
 to be owing to the decomposition which 
 takes place in the rays of light ; each ray 
 consisting of innumerable rays of different 
 colors. Thus a sunbeam being let into a 
 darkened room, through a small round aper- 
 ture A., and falling upon a glass triangular 
 prism P, is by the refraction of the prism 
 considerably dilated, and will exhibit on the 
 opposite wall an oblong image C D, called a 
 spectrum, various colored ; the extremities 
 of which are bounded by semi-circles, and 
 whose sides are straight. The colors are 
 commonly represented as seven in number, 
 which however have various shades, gradually 
 intermixing at their juncture. Their order 
 is as represented in the cut ; violet, indipo, 
 blue, green, yellow, orange, and red. The 
 obvious conclusion from this experiment is, 
 that the several component parts of solar 
 light have different degrees of refrangibility, 
 and that each subsequent ray in the order 
 above mentioned is less refrangible than those 
 which precede it ; the violet being the most 
 refrangible, and the red the least. 
 
 Prismatic Colors. The colors into which 
 a ray of light is decomposed, when refracted 
 from a prism, as before explained. Newton 
 considered these as seven in number. (See 
 Primative Colors.) The proportion which 
 
 these colors bear to each other in a ray of 
 light, are violet 80, indigo 48, blue 60, 
 green 60, yellow 40, orange 27, red 45 ; and 
 if a large card have its rim painted of these 
 colors in the above proportion, and then be 
 made to revolve rapidly, the seven colors will 
 become so blended as to give the appearance 
 of whiteness, just the same as these colors, 
 in like proportions, constitute in nature a 
 white light. 
 
 Prismatic Spectrum. (See Prism tn 
 Optics.) 
 
 Prismoid. a solid, similar in form to a 
 prism. 
 
 Problem. In geometry, a proposition in 
 which something is required^to be done, and 
 which is afterwards to be proved to be the 
 thing required. A problem consists of three 
 parts— the proposition or thing proposed to 
 be accomplished ; the resolution or solution, 
 which is the method of performing the thhig 
 required ; and the demonstration or proof 
 of the correctness of the operation. 
 
 Problkm of thk Three Bodies, is the 
 term by which is denoted the celebrated 
 problem of finding the inequalities of the 
 lunar orbit. The problem is as follows: — 
 Three bodies of given magnitudes, as the sun, 
 the earth, and the moon, being projected into 
 space with given velocities, and in given di- 
 rections, and attracting each other according 
 to a given law, (the inverse ratio of the 
 square of their distances from each other, 
 and directly as their masses,) it is required 
 to determine the nature of the curve, that 
 one of them as the moon, describes about 
 one of the others as the earth. This is a 
 problem which has engaged the attention of 
 the most celebrated analysts of modern times. 
 
 Producing. In geometiy, the continuing 
 a straight line, or drawing it out to any 
 assigned length. 
 
 Product. In arithmetic and algebra, is 
 the quantity arising from the multiplication 
 of two or more factors, as 24 is the product 
 of 6 and 4, or the number produced by the 
 multiplication of 6 and 4. 
 
 Profile. The outside or contour of any 
 thing, such as a figure, building, ornament,&c. 
 
PR 
 
 PR 
 
 Profile Instrument. (See Silouette.) 
 
 Progression. In arithmetic and algebra, 
 a series of numbers advancing or proceeding 
 in the same manner, or according to a certain 
 ratio. It is either arithmetical or geometrical. 
 Arithmetical progression is when the numbers 
 proceed by some common difference, as 
 1, 3, 5, 7, 9, &c. In geometrical pro- 
 gression, the series of numbers increase or 
 decrease by a common ratio, as 1,2, 4, 8, 16, 
 and so on, the constant ratio in this case 
 being 2. 
 
 Projectiles, is that branch of mechanics 
 which relates to the motion, velocity, range, 
 &c. of a heavy body projected into void 
 space, practically speaking, into the air, by 
 any external force, and then left to the free 
 action of gravity, by which it descends to 
 the earth, such as a ball fired from a cannon, 
 the flight of an arrow, rocket, &c. A pro- 
 iectile is always acted upon by two forces ; 
 the propelling force, which carries it along, 
 and which is always decreasing ; and the 
 power of gravitation, which draws it down- 
 wards, and which is an accelerating force. 
 These two forces acting upon a projectile, 
 which moves perpendicularly, will merely 
 counteract each other after a short time, 
 when the body projected will have attained 
 its highest point, after which it will fall, 
 being influenced by gravitation alone ; or if 
 projected horizontally or obliquely to the 
 earth's surface, the combined forces will 
 occasion its path to be that of a parabola. 
 
 Projection. The art of forming the re- 
 presentation of a body upon a plain surface ; 
 also any thing which appears similar to such 
 a drawing. Thus we say the projection of 
 an estate, or the plotting of it ; also the 
 projection of a shadow, though caused 
 naturally. Projection or projecture, is also 
 any thing projecting beyond a general flat 
 surface ; thus prominent mouldings, cor- 
 nices, &c. are projectures from a building. 
 Workmen often call them sailings over. 
 
 Projection, Powder of. (See Philo- 
 sopher's Stone.) 
 
 Prolate. An epithet applied to a sphe- 
 roidal body which turns on its longer axis, 
 or which resembles the figure made by re- 
 volving a semi-ellipse on its conjugate di- 
 ameter. A lemon is a prolate spheroid. 
 
 Pronaos. A vestibute ; the space under 
 a portico, a porch, &c. 
 
 Proof. In engraving, a print taken off 
 in the course of the engraver's process, 
 that he may ascertain how far his labors 
 have been successful. In copper-plate print- 
 ing, proofs are the earliest and most careful 
 prints taken from an engraved plate. In 
 letter-press printing, a proof is a rough 
 print taken as soon as the type is arranged, 
 in order to enable the printer to correct 
 errors, and the author to re-examine his 
 
 work before it is finally printed off. Proof 
 spirit signifies any spirituous liquor which is 
 of a certain strength. (See Hydrometer.) 
 
 Proofs. (See Bologna Phials.) 
 
 Proportion. The just relative magnitude 
 of the parts of an object or of a scene to 
 each other. Thus the different members of 
 a building, machine, statue, drawing, &c., 
 may or may not be in just proportion. 
 
 Proportion. In mathematics, signifies an 
 equality or similarity of ratio ; that is, if 
 the ratio of 6 to 3 be the same as tliat of 
 24 to 12 ; then 6, 3, 24, and 12, are in pro- 
 portion, which is denoted by placing the 
 quantities thus, 6 : 3 :: 24 : 12, and is read, 
 as 6 is to 3, so is 24 to 12. This, because 
 three of the numbers are usually given to 
 find a fourth, is often called the rule of three, 
 and is divided into direct and inverse. In 
 direct proportion, the second term, if greater 
 or less than the first, requires the fourth to be 
 in like manner greater or less than the third, 
 as in the above example. In inverse pro- 
 portion, the fourth term does not agree with 
 the second, in being greater or less than that 
 which precedes it, but is reversed ; thus, if 
 the second be greater than the first ; the 
 fourth will be less than the second, and so on. 
 (For other kinds of proportion or progression, 
 see Arithmetical, Geometrical, and Hat'- 
 monical.) 
 
 Proportion, Compass of. A name by 
 which the French and some English authors 
 call the sector. 
 
 Proportion, Definite. (See Atomh 
 Weights.) 
 
 Proportion, Rule of. The rule of three. 
 
 Proportional. Relating to the propor- 
 tion which objects, quantities, and numbers 
 bear to each other, as proportional parti, 
 scales, &c. 
 
 Proportional Circles. (See Pitsh 
 Lines.) 
 
 Proportional Compasses. (See Com- 
 passes.) 
 
 Proposition. In mathematics, is either 
 some truth advanced, which is to be demon- 
 strated, or some operation proposed, which 
 is to be performed, and shown to be that 
 which was required. Being in the former 
 case called a theorem ; in the latter a problem. 
 (See these terms.) 
 
 Propylceum. a court or vestibule before 
 a building. The word is now chiefly applied 
 to the building forming the entrance to the 
 Acropolis of Athens, which is called " The 
 Propyloea," without any other designation. 
 
 Prostyle. A temple having columns in 
 front only. 
 
 Prot, or Proto. In chemistry, signifies 
 a combination, in which the base is in the 
 largest proportion to the combining substance. 
 Thus a protoxyde contains a less proportional 
 quantity of oxygen than a deutoxyde or a 
 
PR 
 
 PQ 
 
 peroxyde ; a protochloride proportionably 
 less chlorine ; and so on. 
 
 Protractor. A scale for the purpose of 
 measuring or laying out angles on paper. It 
 is one of the instruments ordinarily belong- 
 ing to a case of mathematical instruments, 
 and consists of a semi-circular arc of brass, 
 with a straight edge joining the two ends 
 of the seiui-circle. This latter is gra- 
 duated from each end ; so that when it is 
 required to lay down an angle of a certain 
 measurement, the protractor is laid upon the 
 paper in such a way, that the centre of the 
 straight limb exactly coincides with the an- 
 gxilar point, and the edge with one of the 
 lines of the angle ; a point being made with 
 the pencil, adjoining to the circular arc, and 
 at the required degree, shows where the 
 second line of the angle is to come. 
 
 Prussian Alkali. Ferro-pinissic or 
 ferro- cyanic acid. 
 
 Prussian Blue. The percyanide of iron. 
 Heat to redness dried blood or other animal 
 matter, with an equal weight of pearl-ash, 
 till reduced to a paste ; dissolve the residue 
 in water, filter and mix with a solution of 
 1 part of proto-sulphate of iron and 2 parts 
 of alum ; the greenish precipitate absorbs 
 oxygen from the atmosphere, and it is thence 
 tinged to the proper color. 
 
 Prussian Green. A celebrated pigment, 
 consisting of an imperfect Prussian blue, 
 containing excess of the oxyde of iron, to 
 which the yellow tincture of French berries 
 is added. 
 
 Prussiate. Any salt of the prussic acid. 
 
 Prussic Acid, or Hydro-Cyanic Acid, 
 is a compound of hydrogen and cyanogen. 
 It is a clear, limpid liquid, of a strong 
 pungent odour, very like that of bitter 
 almonds, in which, as well as in other species 
 of stone fruit, it is found. Its taste is acrid, 
 and it is highly poisonous, so that the utmost 
 care should be taken to avoid inhaling its 
 vapour. It volatilises so rapidly as to freeze 
 itself when a drop of it is placed on a glass 
 plate. It feebly reddens litmus. It is de- 
 composed by many of the metallic oxydes, 
 and water and a metallic cyanuret are the 
 result. 
 
 PRussiNE,or Prussic Gas. (See Cyanogen 
 Prussic Acid.) 
 
 T' . .->n.i)iPTERA. A temple with two 
 
 rows of columns in front, and with a single 
 row of columns all round the other part. 
 
 O O O O 
 
 o o o o 
 
 o o o o o 
 
 o o i 
 o o 1 
 
 1 
 
 fl o 1 
 m o o o 
 
 o o o o 
 
 o o o o 
 
 o o o o o 
 
 Ptolemaic System op Astronomy. 
 
 Ptolemy, the celebrated astronomer, believed 
 and taught that the universe was thus con- 
 stituted : — That our earth was the centre of 
 the whole. That there revolved about the 
 earth — first, the moon, then the sun ; more 
 distant, in regular rotation. Mercury, Venus, 
 Mars, Jupiter, and Saturn ; outside of which 
 planet were the starry heavens, and beyond 
 this three different strata, or hollow spheres 
 within each other, called the first, second, 
 and third crystalline heavens, and to bound 
 them was the Primum Mobile, or Great 
 First Ca ise. 
 
 Puddle. A mixture of good tempered 
 clay and sand reduced to a semi-fluid state, 
 and well combined. It is used for the pur- 
 pose of retaining the water in any particular 
 situation, or for excluding it from any 
 works, and is usually spread in layers of 
 about 12 inches in thickness. 
 
 Puddling. A curious process by which 
 cast iron is made into w^rought iron. Cast 
 iron, after it has been in some degree re- 
 fined by fusion, in contact with charcoal, is 
 put into a reverberatory furnace, and when 
 in fusion, is stirred, so that every part may 
 Vo oy,-ncofi ffi the air an<^ ^-^.-o. After a 
 
PU 
 
 PU 
 
 time, the mass heaves, emits a blue flame, 
 and gradually grows tough, becoming less 
 fusible, and at length pulverulent ; the fire 
 is then urged so that the particles again 
 agglutinate at a welding heat, and are gra- 
 dually wrought up into masses. In that 
 state of immense heat the masses are passed 
 successively between rollers, by which a 
 large quantity of extraneous matter is squeezed 
 out, and the iron becomes malleable. 
 
 Pugging. A coarse kind of mortar laid 
 upon the boarding between joists, in order 
 to prevent sound reaching from one apart- 
 ment to another. Filling up the intervals in 
 flooring, &c. with the refuse cuttings of 
 cork is far superior to deaden sound, though 
 more dangerous in case of fire. 
 
 Pulley. One of the mechanical powers. 
 It consists of a small wheel with a groove 
 round it, and turning on an axis, and hence 
 by means of a rope it is employed to raise 
 weights or to draw them in any direction. 
 The moveable wheel is called the shieve or 
 sheave. The axis is the gudgeon, and the 
 fixed piece of wood or brass in which the 
 sheave is placed is the block. By a simple 
 or single pulley, as fig. 1, in the cut, no 
 
 power is gained, A and B is the cord which 
 passes off it, being equally balanced by an 
 equal weight. It is valuable only in altc^Ving 
 tie direction of motion ; but if inverted like 
 tl e pulley P, in fig. 4, so that one end of 
 tie hne is fixed above, the fixed side of the 
 line G will bear half its weight, and the 
 other side of the line will support the other 
 half, F. Instead of fastening F to a second 
 hork at top, let it be attached to a second 
 pi lley O. Here the weight is again divided, 
 oi e half being borne by F, the other by D. 
 A third pulley B will halve it again, and a 
 fi urth pulley, in like manner, halve the 
 wc'ght of B. Tlius supposing tlie pulley P 
 
 to sustain the weight W of 16 lbs. ; O has 
 to bear 8 lbs. ; B only 4 lbs. ; the pulley 
 above 2 lbs. ; and the cord above dividing 
 this, the weight X is but 1 lb., and yet it 
 supports 16 lbs. at the offer end, not allow- 
 ing, however, for the weight of the various 
 pulleys, which is very trifling. In all systems 
 of pulleys, the weight is divided, or what is 
 the same thing, the power is increased in 
 the same geometrical ratio for every moveable 
 pulley, whatever be the general form of the 
 whole system or arrangement. Thus in 
 figs. 2 and 3, as there are two moveable 
 pulleys to each, the power applied at one 
 end is increased four-fold at the other ; that 
 is, a man pulling at the cord can raise four 
 times his own weight, or the power he chooses 
 to employ. Fig. 2 is usually called a tackle, 
 and is the form most commonly employed. 
 
 Pulley, Live and Dead, or Fast and 
 Loose. Two pulleys placed close together, 
 and attached to a crane, lathe, mandril, or 
 other machinery, to carry the band which 
 turns it. The band sUpped on to the dead 
 or fixed pulley, turns the machineiy ; slipped 
 on to the live or moveable pulley, that alone 
 moves round while the machinery rests. It 
 is represented below, the pulley B being im- 
 moveably fixed to the shaft C, and the pulley 
 A turning round upon the axis. 
 
 PuLf.EY, Sliding. A means of coupling 
 and disengaging machinery, as follows : — 
 A is the axis or shaft. P is a i)ulley, fixed 
 to a hollow cylindri(;al bush, made so that it 
 can revolve easily upon the axle, and slide 
 backwards and forwards upon it. B a part 
 of the bush projecting on one side of the 
 pulley, having a groove sufficiently large to 
 admit the lever I to lay in it without im- 
 peding its motion. C G is a cross or gland 
 
 fixed firm to the axle ; and I one or more 
 teeth projecimg from the face of the pulley. 
 When the axle AD is to be put in motion, 
 the lever I must be moved towards the cross 
 or gland C G, so that the teeth upon the 
 pulley may catch hold of and carry it round 
 with it. 
 
PU 
 
 PU 
 
 Pulse Glass. A little instrument to show 
 the effects of heat. It consists of a small 
 glass tube, with a bulb at each end, and 
 partly filled with^lored spirits of wine, the 
 space above the spirit being void of air. 
 When this tube is held in the hand obliquely, 
 a small bubble of air remaining in the lower 
 ball, the heat of the hand will expand the 
 air in this bubble, and its escaping into the 
 vacant space above with a pulsatory motion, 
 occasions the instrument to be called a pulse 
 f:Iass, though it has no reference to the state 
 of the pulse. 
 
 If the glass be made in the shape of the 
 following tube, the liquid will appear to boil 
 rather than rise in pulsations : — 
 
 PuLViNATED, or PiLLOWED. The Swelling 
 of the frieze in the Ionic order. 
 
 Pumice Stone. A porous substance, 
 procured from the volcanic countries, and 
 generally considered as the result of volcanic 
 eruptions. It is used in this country chiefly 
 as a polishing powder, when ground, or as a 
 material to smooth the surface of painted 
 work, &c. ; nsed in a lump. 
 
 Pump. A machine for raising fluids by 
 means of pistons or buckets, working in tubes ; 
 valves also being placed within them. The 
 principal and most useful pumps are the lift 
 pump, the ybrce pump, the common or suction 
 pump, and the air pump ; each of which is 
 described under its distinctive name. Tlie 
 following is a pump but little known, and yet 
 very simple in structure, great in power, not 
 liable to get out of order, and 
 which may be made by any 
 ordinary workman : — A BCD 
 is a square trunk of wood, 
 with a partition across it, near 
 the bottom ; a hole being in 
 the partition, covered with a 
 valve, opening upwards, E. 
 Above the valve, and sur- 
 rounding it is a bag of canvas, 
 sewed and t irred so as to be 
 water tight ; hoops placed 
 around it at intervals prevent 
 bursting when the bag is filled 
 with water. The upper end of 
 the bag is tied tightly to a 
 
 round board, also with a hole 
 
 in it, and covered by a valve F. =5 
 
 To this is fastened the piston ^^^^^5 
 
 rod G. Pulling up the rod, ^ ~" 
 
 I and thus elevating the bag, opens the lower 
 j valve, and shuts the upper one. The water, 
 ] therefore, from the well rushes up to fill the 
 vacuum formed ; when the piston rod is de- 
 pressed, the lower valve closes, and the return 
 of the water is prevented, while the water 
 already in the bag flows out through F. The 
 next stroke of the pump handle lifts a fresh 
 supply of water, and discharges the former 
 quantity. (See Force, Lift^ Suction, Ctese- 
 bius, De la Hire, Spiral, Concentric, Chain, 
 Bucket, Air, ^c.) 
 
 Punch, Puncheon, or Punchion. A 
 little bar of steel, plain at the end, or im- 
 pressed with some letter, figure, or device, 
 which is impressed upon a substance by 
 striking the opposite end of the punchion 
 with a hammer. Instruments of this kind 
 are extremely common in all the arts. Pun- 
 cheon is also the general name for most of 
 the instruments used by stone-cutters, sculp- 
 tors, locksmiths, &c., for the making holes in, 
 or cutting their various matters. An upright 
 arbor in machinery is frequently called a 
 puncheon. 
 
 PuRBECK Stone. A hard conglomerate, 
 of an ashy grey color, which very frequently 
 contains nodules of flint or other crystalline 
 substance. The starlings of Old London 
 Bridge were of Purbeck stone. The harder 
 kinds, for there is much difference in this 
 respect, take a fine polish, and are usuallv 
 called Purbeck marbles. 
 
 Purfled. Richly sculptured. 
 
 Purlins. The horizontal pieces of timber 
 lying on the main rafters, to support the 
 common rafters in the middle of their length. 
 
 Purple Powder of Cassius. (See 
 Cassius.) 
 
 Purpurates. Compounds of the purpuric 
 acid. 
 
 Purpuric Acid. An acid obtained by 
 treating uric or lithic acid with dilute nitric 
 acid. It has a fine purple color, but hais 
 hitherto been applied to no use in the arts. 
 
 Purpurine. The name of a coloring mat- 
 ter supposed to exist in madder. 
 
 Pursuit, Curve of, is one generated by 
 the motion of a point, which is always di- 
 rected towards another point, also in motion, 
 along a straight line ; the velocity of the two 
 f)oints bearing any determinate ration to each 
 other. 
 
 Thus let A and B be two bodies ; the one 
 B moving along the line B E, with any gi\^n 
 velocity, and the other A moving with another 
 
PY 
 
 PY 
 
 given velocity, and in such a manner as to be 
 always directed towards the body A B ; then 
 is the curve A E, thus described by A, the 
 curve of chase, or the curve of pursuit. 
 
 Putlog Holes. The small holes left in 
 a wall, for the use of the workmen in erecting 
 their scaffolding ; the cross pieces of wood 
 which support the boards of a scaffold being 
 called putlogs. 
 
 Putrefaction. The spontaneous decom- 
 position of such animal or vegetable matters, 
 as exhale a fetid smell. The solid and fluid 
 matters are resolved into gaseous compounds 
 and vapors, which escape, and into an earthy 
 residuum. 
 
 Putrefactive Fermentation. (See 
 Fermentation.) 
 
 Putty. A kind of paste, compounded of 
 whiting and linseed oil, with or without white 
 lead. It is used by glaziers, for fastening 
 the panes of glass into their frames, and 
 stopping holes in wood-work previous to 
 painting it. 
 
 Putty Powder. Oxyde of tin; used as 
 a polishing powder in many of the arts. 
 
 PuzzoLANA. A substance formed of vol- 
 canic ashes, more or less compacted together. 
 When mixed with a small portion of lime, and 
 water is added, it forms a mortar, which 
 becomes extremely hard under the surface of 
 water, consequently puzzolana is valuable for 
 the foundation of lighthouses and other 
 marine erections. 
 
 Pycnostyle. a term when columns are 
 arranged at only a diameter and a half from 
 each other. 
 
 Pyramid, Electrical. An apparatus in 
 electricity, showing the effect of interrupted 
 conductors, in occasioning 
 destruction to buildings, 
 instead of protecting them 
 from lightning. It is of 
 two parts, A and B. B is 
 a square base, which is 
 fixed ; it has a square hole 
 in the front, a quarter of 
 an inch deep, and one inch 
 on each side ; to this hole 
 is fitted a piece of wood D, 
 so slightly, however, that 
 a mere trifle will remove 
 it. A wire is let in across 
 the wood ; a wire also runs 
 down tlie front of A, and 
 partly the front of B, 
 where it terminates by a 
 hook C. The wood being placed one way, the 
 wire is continuous ; in another way, that is 
 transversely, the wire is interrupted. The 
 pyramid A rests on three brass balls ; the ball 
 in the front resting upon the moveable piece 
 of wood. If a shock be passed from the 
 chain E, through the wire C, the wood D, 
 and second chain F, provided the wire be 
 
 continuous all the way down, no efi*ect will 
 take place, but if the wire of D be transverse, 
 and therefore not connected with the wire C 
 the piece of wood D will be thrown out, and 
 the pyramid A immediately fall. 
 
 Pyramid. In geometry, is a solid having 
 any plane figure for its base, and triangles 
 for its sides, all terminating in one common 
 point. If the base of the pyramid is a 
 regular figure, the solid is called a regular 
 pyramid, which then takes particular names, 
 according to the number of its sides, as 
 triangular, square, pentang«lar, &c. 
 
 Pyramid Optic. (See Optic.) 
 
 Pyramidoid. a figure resembling a 
 pyramid. 
 
 Pyrites. Native compounds of metals 
 with sulphur; as iron pyrites, copper pyrites, 
 &c. • 
 
 Pyroacbtic Ether. Pyroacetic spirit ; 
 acetone. (See Acetone.) 
 
 Pyrocitric Acid. When citric acid is 
 distilled in a retort alone, an acid liquid is 
 obtained, which, when saturated by lime, 
 affords a precipitate, that can be decomposed 
 by oxalic acid, and thus furnishes a peculiar 
 product, called, by Lassaigne, pyrocitric acid. 
 It forms salts, perfectly distinct from the 
 citrates. 
 
 Pyroelectricity. (See Thermo-Elec- 
 tricity.) 
 
 Pyrogallic Acid. An acid produced by 
 the action of heat upon gallic acid ; the heat 
 by which it is distilled being from 410° to 
 420°. If the heat exceeds this, another pro- 
 duct called the metagallic acid is obtained. 
 It is in the form of brilliant white crystals, 
 very soluble in water, alcohol, and ether; 
 and slightly reddening litmus. 
 
 Pyroligneous Acid. A vinegar pro- 
 duced by the destructive distillation of wood, 
 particularly of birch and beech. The wood 
 is placed in retorts, similar to those used in 
 the gas works, and the retorts being heated, 
 the acid passes off by a pipe connected with 
 the retorts, and passing through a worm or 
 refrigerator is cooled, and collected in a vessel 
 beneath. The retort holds about 8 cwt. ot 
 wood, which yields about 35 gallons of crude 
 or impure acid ; tb« weight of this 'n 3C0 'bs. 
 
PY 
 
 FY 
 
 It is rectified by a second distillation. It is 
 used as a household vinegar, and for nume- 
 rous other purposes. 
 
 Pyromeconic Acid. This acid is among 
 the products of the destructive distillation of 
 the meconic acid. It is a crystalline sub- 
 stance, volatile, soluble in water and alcohol, 
 and forms many soluble salts. 
 
 Pyrometer. An instrument formeasuring 
 the expansion of bodies by heat. It differs 
 in no respect from the thermometer, except 
 that it is applied more particularly to measure 
 such high degrees of heat as the thermometer 
 cannot ascertain, particularly the heat of 
 furnaces. Thermometers mostly act by the 
 expansion of liquids, occasioned by a mo- 
 derate heat ; pyroscopes by the expansion of 
 air ; and pyrometers by the expansion of 
 metallic substances. Equal additions of heat, 
 at all times, and -in all of them producing 
 equal expansions, with the single exception 
 of water, under certain circumstances. There 
 are numerous pyrometers, described under the 
 names of their inventors, Froteringham, 
 Ferguson, Regnier, Morveau, Crighton, 
 Breguet, Houriet, Wedgewood, 8fc. 
 
 Pyromucic Acid. An acid procured from 
 the destructive distillation of the mucic acid. 
 It is permanent in the air, inodorous, very 
 sour, fusible at 270°, crystallises in needles 
 in the ordinary state of the atmosphere, 
 soluble in 26 parts of cold, less of hot 
 water, and still less of alcohol. 
 
 Pyrophoric Antimony. It is tartrate 
 of antimony and potass, or emetic tartar, 
 heated to redness, and out of contact with 
 the air. 
 
 Pyrophoric Lead. The tartrate of lead 
 mixed with charcoal, and exposed to a red 
 heat in close vessels; it takes fire when 
 brought into contact with the air. 
 
 Pyrophorus. An artificial compound 
 that takes fire or becomes ignited on exposure 
 to the air. It is prepared from alum, with 
 the addition of various inflammable sub- 
 stances. It may be made thus : — Mix 3 parts 
 of alum with 1 of wheat flour, and calcine 
 them in a common phial till the blue flame, 
 which will arise, disappears. Keep it in the 
 same phial, well stopped with a good cork, 
 when cold. If this powder be exposed to the 
 atmosphere, the sulphuret attracts moisture 
 from the air, and generates sufficient heat to 
 kindle the carbonaceous matter contained 
 in it. The following are other pyrophori : — 
 Intimately mix together about 2 parts of 
 sulphate of potass with 1 of lamp black ; 
 heat them to redness in a coated phial, and 
 exclude the air carefully during cooling. 
 Take equal parts of brown sugar and alum, 
 and proceed as in the first receipt. Instead 
 
 of sulphate of potass in the second receipt, 
 the sulphate of soda may be used. 
 
 Pyrophosphoric Acid. When a salt of 
 the phosphoric acid, for instance the phos- 
 phate of soda, is heated to redness, an acid 
 arises from it, different from the phosphoric, 
 as is shown by its forming a white precipitate 
 with the nitrate of silver, instead of a yellow 
 one. This acid is the pyrophosphoric. Its 
 salts are pyrophosphates. 
 
 Pyrotartaric Acid. An acid thus ob- 
 tained : — Distil the tartaric acid. Filter the 
 brown liquid obtained ; saturate it with car- 
 bonate of potass, and evaporate to dryness. 
 Distil this salt with sulphuric acid, diluted 
 with its weight of water ; an acid liquor 
 i passes over, succeeded by a white sublimate 
 t of pure pyrotartaric acid. 
 , Pyrotechny. The science which treats 
 of the application and management of fire, 
 particularly as applied to the art of war, and 
 the making of ornamental fire-works, such as 
 rockets, Bengal lights, &c. 
 
 Pyroscope. When one ball of the diffe- 
 rential thermometer is smoothly covered with 
 thick silver leaf, or inclosed in a polished 
 sphere of silver, and the other bgdl is naked, 
 it forms the pyroscope ; an instrument in- 
 tended by its inventor, Mr. Leslie, to mea- 
 sure the intensity of heat radiating from a fire 
 into a room, or the frigorific influence from a 
 cold body. A figure is unnecessary, as the 
 instrument is usually made either like the 
 differential thermometer, as represented un- 
 der the word Air, or like Leslie^ s Hygrometer. 
 
 Pyrouric Acid. When uric acid is dis- 
 tilled alone it yields carbonate and hydro- 
 cyanate of ammonia, and a sublimate of 
 pyrouric or cyanuric acid. 
 
 Pyroxylic Spirit. Pyroligneous Spi- 
 rit. Bi-HYDRATE OF Methylene. A lim- 
 pid liquid, of a peculiar odour, inflammable 
 and volatile, hot and pungent to the taste, 
 and not altered by exposure to the air. It is 
 used in varnish-making, and burnt in lamps 
 under the name of naphtha, and for other 
 purposes, as a cheap substitute for spirits of 
 wine. It is procured by the destructive dis- 
 tillation of wood, appearing along with the 
 tar, acetic acid, and other products. 
 
 Pythagorean System of Astronomy. 
 The same as that of Copernicus, (which see,) 
 being that adopted by all modern astronomers. 
 
 Pythagorean Table. The multipli- 
 cation table. 
 
 Pythagorean Theorem. A name some- 
 times given to the forty-seventh proposition 
 of the first book of Euclid, which is, that 
 the sum of the squares of the two legs of a 
 right-angled triangle is equal to the square 
 of the hypothenuse. 
 
QU 
 
 QU 
 
 The seventeenth letter in 
 the English alphabet, and 
 a mute. It was unknown 
 to the Greek and more 
 ancient Latin authors ; and 
 when introduced was con- 
 sidered as representing the 
 sound of two letters, q and 
 w, as qid for quid ; qis for 
 quia ; or otherwise, to represent the sound of 
 c hard, or oi k ; as in Latin, cuique ; or in 
 French, coq, Acqs, SfC; in Spanish, cuanto 
 for quanto. Its sound, in English, is very 
 similar to that of k or kw. Q, as a Roman 
 numeral, signified 500 ; with a dash over it 
 500,000. As an abbreviation, it stands for 
 quxstor, quartus, que, quod, quo, question, 
 &c. 
 
 Quadra. In building, any square mould- 
 ing, frame, or border, encompassing a bas- 
 relief; also used, but erroneously, for a 
 border of any other shape. 
 
 Quadrangle. In geometry, a figure of 
 four sides ; otherwise called a quadrilateral. 
 Also a four -sided rectangular court yard or 
 open space, inclosed by buildings. 
 
 Quadrant. In geometry, the fourth part 
 of a circle, made by two radii and an arc of 
 90". Quadrant is also a name common to 
 several mathematical instruments, used for 
 measuring altitudes and angular distances, 
 which are commonly distinguished from each 
 other by the names of their authors, or the 
 purposes they are intended to answer. The 
 principle upon which the construction and 
 use of this instrument depends may be illus- 
 trated by the aiinexed figure : — 
 
 A B C is a quadrant, or quarter of a circle, 
 of brass, wood, or other material, having the 
 arc A B divided into degrees and minutes, 
 from A to B. On one side B C are two 
 fixed sights D E, and at C is fixed a plumb 
 line. The use will be easily understood by 
 the explanation given under Quadrat, which 
 is indeed a similar instrument. The above 
 quadrant would be extremely imperfect in 
 practice ; numberless improvements have 
 therefore been suggested, but the quadrant 
 of Hadley is so superior to all others that it 
 is now universally employed in taking celestial 
 altitudes. It is thus figured and described :— 
 
 The instrument consists of an octant, or 
 the eighth part of a circle, ABC. An index D. 
 
 The speculum E . Two horizontal glasses 
 F G. Two screens K, and two sight vanes 
 H and I. The octant consists of two radii 
 A B, A C ; strengthened by the braces L M, 
 and the arc B C, which though containing 
 only 45° is nevertheless divided into ninety 
 primary divisions. The index D is a flat 
 bar, moveable about the centre of the in- 
 strument, and that part of it which slides 
 over the scale is perforated, and contains a 
 vernier for registering minute divisions. The 
 rays from the object, whose altitude is re- 
 quired, are received on the speculum at the 
 top E, from thence reflected on one of the 
 sights F or I, which are two small pieces of 
 looking glass placed on the limbs. The 
 screens K are of colored glass, to temper 
 the too great light of the sun or moon when 
 their altitude is taken ; a red glass being used 
 for the sun, and a green one for the moon. 
 Quadrant of Altitude, {^ee Altitude.) 
 Quadrant Electrometer. A most 
 valuable instrument to ascertain the intensity 
 of electricity, contained in any electrical ap- 
 paratus, particularly a Leyden jar or battery. 
 Its cause of action is by electrical repulsion. 
 It consists of an upright stem of wood, the 
 lower end of which is capped with brass, and 
 furnished with a thick wire, that fits into one 
 of the holes of the prime conductor of an 
 electrical machine. The upper part of the 
 stem is terminated by a ball, and on the side 
 of it is a scale of degrees, numbered from 
 the lower parts upwards. From the centre of 
 the scale is freely suspended a thin wooden 
 rod, at the end of which is a pith ball ; this 
 part is as light as possible. When attached 
 to the conductor, while a Leyden jar or bat- 
 tery is being charged, the pith ball will rise. 
 
Qtr 
 
 QU 
 
 and indicate by the degrees on the scale the 
 intensity of the charge. 
 
 QuADRANTAL Space. The same as quad- 
 rant ; that is, the fourth part of a circle. 
 
 QuADRANTAL Triangle. A Spherical 
 triangle, having a quadrant or an arc of 90° 
 for one of its sides. 
 
 Quadrat. A mathematical instrument, 
 called also a geometrical square and line of 
 shadows. It is frequently an additional mem- 
 ber on the face of the common quadrant. It 
 is made of any solid matter, as brass, wood, 
 &c., of any four plain rules, joined together 
 at right angles ; where A is the centre, from 
 which hangs a thread, with a small weight at 
 the end, serving as a plummet. Each of the 
 sides B E and E D is divided into 100 equal 
 parts, or if the sides be long enough to admit 
 of it into 1000 equal parts. C and F are two 
 sights, fixed to the side A D. There is, 
 moreover, an index G H, which, when there 
 is occasion, is joined to the centre A, in such 
 a manner as that it can move freely round, 
 and remain in any given situation. There 
 are also two sights, K and I, perpendicular to 
 the right line, going from the centre of the 
 instrument. To measure the height of an 
 object by this instrument, hold it in the hand, 
 so that the eye may see the top of the object 
 through the sights. Note the division, cut 
 off the line E B by the plummet ; this giving 
 the angular altitude, the true altitude may 
 be found by trigonometry. 
 
 Quadrat. In printing, a piece of metal 
 cast like the letters, to fill up the void spaces 
 between words, &c. There are quadrats of dif- 
 ferent sizes, called m quadrats, n quadrats, &c. 
 
 Quadratic, is a name given in geometry 
 to various mechanical curves. 
 
 Quadratic Equation. In algebra, is an 
 equation in which the highest power of the 
 unknown quantity is of the second degree. 
 If this power enter alone as x^ + 2, it is a 
 simple quadratic equation ; if the first power 
 is also present, it is called an adfected quad- 
 ratic equation, as a:''* + .r + 2. 
 
 Quadrature. In geometry, is the finding 
 a square equal in area to another figure ; or 
 in other words finding the area of plane 
 surfaces. 
 
 Quadrature. In astronomy, is that as- 
 pect of the moon when she is a quadrant, or 
 90° from the sun, when entering the second 
 or fourth quarter. 
 
 QuADRELS. A kind of artificial stone, 
 perfectly square, hence their name. They 
 are made of a chalky, or a white, pliable 
 earth, &c., dried in the shade for at least two 
 years. They were formerly in great request 
 among the Italian architects. 
 
 QuADRi. In chemical compounds, signifies 
 that the base is in the proportion of one- 
 fourth to the combining matter; thus the 
 quadrioxalate of potass consists of 1 part 
 potass to 4 of oxalic acid. 
 
 Quadrilateral. Any figure of four 
 sides, whether a square, a rectangle, rhombus, 
 trapezium, or other similar figure. 
 
 Quadrillion. The fourth power of a 
 million ; but according to the French only 
 the square of a million, or the fourth power 
 of 1000. 
 
 Quadruple. Four-fold. 
 
 Quality. The power in any body of ex- 
 citing some impression on the mind ; thus, 
 a snow-ball having the power to excite in us 
 ideas of cold, whiteness, hardness, and 
 roundness ; this substance is said to have the 
 corresponding qualities, or that it is cold, 
 white, hard, and round. 
 
 Quantity. Any thing capable of esti- 
 mation or measurement, or which being 
 compared with another thing of the same 
 kind, may be said to be greater or less than 
 it, equal or unequal to it. 
 
 Quarry. A word of very different appli- 
 cations. It implies, first, a place or pit, 
 where stone, slate, chalk, &c. is dug up. 
 Secondly, a diamond-shaped piece of glass, to 
 be used sis a window pane, such as is often 
 seen in cathedral and cottage windows, where 
 one point of the quarry is placed uppermost 
 in the leaden frame. Thirdly, an arrow, with 
 a barbed head, is called a quarry ; and 
 fourthly, the word signifies a small square 
 tile, made for paving. It is about 6 inches 
 square, of a red color, and impressed with 
 
QU 
 
 QU 
 
 some device, which is either white, yellow, 
 b]ack, or blue. Examples of quarries are 
 given under Abaciscus, the ancient name of 
 this kind of material. Quarried pavements 
 are by no means uncommon in old village 
 churches. The following is one from a 
 church at Oxford : — 
 
 Quarrying Slates and Stones. The 
 method of preparing them for their different 
 uses and applications at the quarries and 
 pits where they have been raised. 
 
 QuARRYiNGS. The small pieces that are 
 broken or chipped off from the different sorts 
 of materials found and wrought in quarries, 
 while preparing for different uses. 
 
 QuARTATioN, is an operation by which 
 the quantity of one thing is made equal to a 
 fourth part of the quantity of another thing. 
 Thus when gold, alloyed with silver, is to be 
 parted, we are obUged to facilitate the action 
 of the aquafortis by reducing the quantity of 
 the former of these metals to a fourth part 
 of the whole mass, which is done by 
 sufficiently increasing the quantity of the 
 silver, if it be necessary. This operation is 
 called quartation. 
 
 Quarter. A square panel inclosing a 
 tre-foil or other ornament. 
 
 Quarter. In speaking of the moon's 
 age, is a fourth part of a lunation. 
 
 Quarter-Point. In navigation, is the 
 fourth part of the measure of one of the 
 principal points of the compass. For ex- 
 ample, a fourth part of the distance between 
 N. and N by E. 
 
 Quarter-Round. A term that explains 
 itself, but applied by workmen to any mould- 
 ing whose contour is the arc of a circle. 
 (See Ovolo and Echinus.) 
 
 Quartite Aspect. Where two heavenly 
 bodies are 90° distant from each other. 
 
 Quartz. A genus of hard, and in most 
 cases, transparent minerals, assuming a 
 crystalline or conchoidal structure. The 
 former, from the shape of the crystals, is 
 called rhomboidal quartz, and the latter 
 indivisible quartz. Of rhomboidal quartz. 
 
 there are fourteen varieties: viz. amethyst, 
 rock crystal, milk quartz, common quartz, 
 prase, cat's-eye, fibrous quartz, iron flint, 
 hornstone, flinty slate, flint, calcedony, helio- 
 trope, and jasper. To indivisible quartz 
 belong floatstone, quartz sinter, hyalite, opal, 
 melilite, obsidian, pitch stone, pearl stone, 
 and pumice stone. 
 
 Quartre-Foil. An ornament resembling 
 a four-leaved flower ; common in Gothic 
 buildings. 
 
 Quassia. A vegetable substance, disco- 
 vered in quassia wood by Dr. Thompson. It 
 is brownish yellow, somewhat transparent, 
 and solid like an extract. It is soluble in 
 ether, and intensely bitter. 
 
 Queen Post. (See Roof.) 
 
 Queen's Metal. A white alloy, used for 
 tea pots, spoons, &c. Its composition is 
 9 ozs. of tin, 1 oz. of bismuth, 1 oz. of an- 
 timony, and 1 oz. of lead. 
 
 Queen's Ware. A particular kind of 
 pottery goods. 
 
 Queen's Yellow. An old name of the 
 turbith mineral, or yellow sub-sulphate of 
 mercury. 
 
 Quercitrin. The coloring principle of 
 quercitron bark. 
 
 Quercitron Bark. A most valuable drug 
 for dyeing yellow ; the bark of the Quercus 
 tinctoria of North America. With the salts 
 of iron it gives a variety of olive and drab 
 tints, dependent upon the presence of more 
 or less tannin, and the degree of dilution. 
 
 Quicklime. (See Lime.) 
 
 Quicksilver, or Mercury. (See Mer- 
 cury.) 
 
 Quill. The larger feathers of the wings 
 of birds, the barrel part of which is used 
 chiefly for writing pens, the floats of angler's 
 lines, and to inclose the hair in hair pencils. 
 The feathery portion is useful to the artificial 
 flower maker, and as the featherings to arrows. 
 
 Quincunx. Five-twelfths of any thing. 
 
 Quincunx Order. A peculiar arrange- 
 ment of any thing in rows, so that the arti- 
 
 M ^ ^ ^ 
 ^. ^ ^ ^ ^ 
 
 m. ^ ^ ^ 
 
 ^ ^ .^ j^ ^ 
 
 j& -^ _^ ^ 
 
 ^ j^ ^ ^ ^ 
 
 ^ ^ ^ ^ 
 ^ ^ j^ ^ ^ 
 
RA 
 
 RA 
 
 cles in one row are not opposite those of the 
 next, but opposite to the intervals between 
 them. This method is peculiarly applicable 
 to planting trees and herbs, as by it a great 
 saving of ground is obtained, and a great 
 degree of regularity preserved. The pre- 
 ceding figure shows the method. 
 
 QuiNDECAGON. A figure of fifteen sides. 
 
 QxTiNiA, or Quinine. An alkaloid, valu- 
 able in medicine, existing in the red Jesuit's 
 bark, {Cinchona longifolia,) in the state of 
 kinate or quinite of lime. 
 
 QuiNODiA, or QuiNODiNE. A substance 
 similar to, and perhaps identical with quinine. 
 It is extracted from the yellow bark. 
 
 QuiNauEANGULAR. Having five angles. 
 
 Quintessence. A concentrated essence, 
 or one in which the oil preponderates over 
 the alcohol. It is a term used chiefly in 
 perfumery. 
 
 QuiNTiLE Aspect. When two heavenly 
 bodies are a fifth part of a circle, or 72° 
 distant from each other. 
 
 QuiNTiLLioN. The fifth power of a mil- 
 lion. 
 
 Quirk. A piece of ground taken out of 
 any regular ground plat or floor ; thus if the 
 ground plat were square or oblong, and a 
 piece be taken out of one corner to make a 
 court or yard, &c., the piece is called a quirk. 
 The irregular garden beds, cut out of grass 
 lawns, are not usually called by any other 
 
 name than beds, although as truly quirks as 
 any other example that can be adduced. 
 
 Quirk Moulding. Any moulding which 
 is increased by an additional turn or twist, 
 in order to give it a greater apparent projec- 
 tion. For example, A and B in the cut are 
 the common ovolo and ogee mouldings. C 
 and D are the quirked ovolo and the quirked 
 ogee. 
 
 Quoins. In printing, are the small wedges 
 used to tighten the furniture around the type 
 when it is set up. (See Printing.) In ar- 
 chitecture, quoins are the stones which are 
 placed at the angles of buildings, particularly 
 brick buildings in order to strengthen them. 
 When these stand out beyond the brick -work, 
 their edges being chamfered off", they are 
 called rustic quoins. 
 
 Quotient. The quantity which arises by 
 dividing one number by another. 
 
 The letter R is a liquid, 
 a semi- vowel, and a lin- 
 gual, the sound of it being 
 pronounced by the action 
 of the tongue, though this 
 much varies in different 
 languages, as well as in 
 the different dialects of 
 English. Hence independent of the varied 
 sound which the letter properly has, others 
 are given to it, thus, the American, the 
 Irishman, the Yorkshireman, and the Lon- 
 doner, pronounce the word " morning " very 
 differently. The utterance of r is either 
 with a trill or slight shake of the tongue, as 
 in rhetoric, Rizzio ; or when followed by 
 e or i, pronounced rapidly — so much so, that 
 e and r coming together, are often trans- 
 posed, as childern for children, prespiration 
 for perspiration ; and i following the r, is by 
 some persons omitted altogether, as curosity 
 for curiosity. R, among the Latins, signified 
 80 ; among the Greeks 100 ; and by the 
 Jews 200. R, on ancient coins, stands for 
 Ravenna, Regia, Roma, Romanus, Regulus, 
 &c; in modern times, Rex or Regina, 
 
 i (King or Queen,) or for rare; R R for more 
 I rare ; and R R R for unique or very rare. 
 I Rabbet. (See Rebate.) 
 j Race, or Race-Course. The cut or 
 I canal along which the water is conveyed to 
 I a water-wheel. 
 
 Racemic Acid. (See Paratartaric Acid.) 
 Rack and Pinion, and Rack and 
 Sector. A rack is a straight bar of metal 
 having cogs or teeth cut along its edge, by 
 which it is moved up and down, in conse- 
 quence of a pinion of similar sized teeth i 
 working in it ; (see Pinion.) Sometimes the 
 rack is moved by means of a sector, which i 
 
RA 
 
 RA 
 
 may be called the quarter of a wheel, moving 
 the rack by an alternate motion. The preced- 
 ing shows two racks moved by sectors, the 
 velocity of each rack being in proportion to 
 the distance from the centre of each respective 
 sector. 
 
 Radiant. Any thing proceeding like rays 
 from a body ; in contradiction to reflected, 
 as radiant heat. 
 
 Radiant Point. Any point from which 
 rays of light, heat, or color proceed. 
 
 Radiation, is the shooting forth in all 
 directions from a central point. 
 
 Radiator. A body from which rays 
 emanate. 
 
 Radical. A term used in chemistry, as 
 nearly synonymous with base, but more par- 
 ticularly applicable to the acids, as consti- 
 tuting their distinguishing part, by its union 
 with oxygen or other acidifiable principle. 
 Thus sulphur is the radical of the sulphuric 
 and sulphurous acids. 
 
 Radical Sign. In the mathematics, is 
 the character by which the root of a quantity 
 is expressed, and is formed thus V, while 
 the particular root is indicated by a small 
 figure placed on the left side of it ; thus 
 2 // signifies the square root, ^ V the cube 
 root, and so on. When the radical sign 
 stands alone, without a figure, the square 
 root is always understood. 
 
 Radical Vinegar. Strong acetic acid. 
 
 Radius. The semi-diameter of a globe 
 or circle ; that is, a right line drawn from 
 the centre to the circumference. 
 
 Radius, is a shoot or rod, and its plural 
 radii, or rays in English, used both literally 
 and metaphorically. They may be the spokes 
 of a wheel, or the beams shot by the sun. 
 
 Radius Vector, is a right line drawn 
 from the centre of force in any curve in 
 which a body is supposed to move by a 
 centripetal force, to that point of the curve 
 in which the body is supposed to be. For 
 example : — Suppose that in the annexed cut 
 the ellipse represents the path of a plane, 
 and S the sun or centre of force. The lines 
 extending from the sun to that part of the 
 orbit in which the planet is placed will be 
 the radius vector, and as the planet varies its 
 distance from the sun in passing from one 
 end of its orbit to the other, so the radius 
 vector also varies, being at one time S A ; at 
 another SC; at others SB, SD, SE, SF, &c. 
 
 Radix. The same as root, but used in a 
 different sense by different authors ; thus we 
 say, the radix of a system of logarithms, a 
 system of notation, &c., meaning the funda- 
 mental quantity on which the system is con- 
 structed, or by which all the others are 
 compared. 
 
 Rafters. Tlie sloping timbers of a roof. 
 
 Rag Wheel and Chain. A contrivance 
 for the same purpose as the band which passes 
 over a lathe to turn the mandril, but used 
 where there is any very great resistance to be 
 overcome. The rag wheel is furnished with 
 projecting cogs or pins, at equal distances 
 around the circumference as at A. The 
 chain is made with links, as represented, 
 the length of the links correspondiug to the 
 distance of the pins from each other ; the 
 chain passing round two such wheels, at some 
 distance apart. Upon one of them being 
 turned, the other will, by the chain catching 
 hold of the teeth, be also put in motion. 
 
 Rail. In architecture, is particularly ap- 
 plied to those pieces of timber, which lie 
 horizontally between the panels of wainscot 
 and over and under them. In rural economy, 
 the rails are those pieces of timber which lie 
 horizontally from post to post in fences. 
 
 Railway, or Railroad. A track con- 
 structed of iron, stone, timber, or other ma- 
 terial, for the purpose of diminishing friction, 
 and thus serving for the easy conveyance of 
 heavy loads, whether of carriages, of pas- 
 sengers, cattle, or goods. 
 
 Railvjtay Slide. A contrivance on a 
 railway, for the purpose of shifting a carriage 
 from one line of rails to another. 
 
 Rain. A well-known phenomenon, the 
 cause of which is explained thus : — The 
 moisture which is always more or less present 
 on the earth's surface, is raised into the at- 
 mosphere by evaporation. It floats there, 
 the particles repelling each other by electri- 
 cal repulsion, until some electrical change in 
 the condition of the air takes place. When 
 this is the case, the drops no longer repel 
 each other, but coalesce with more or less 
 rapidity; and being now too heavy to be 
 buoyed up any longer, they fall either in the 
 state of rain, hail, or snow. 
 
RA 
 
 RA 
 
 Rainbow. A circular image of the sun, 
 variously colored. It is thus produced : — 
 The solar rays, entering the drops of falling 
 rain, are refracted to their farther surfaces, 
 and thence, by one or more reflections, trans- 
 mitted to the eye. At their emergence from 
 the drop, as well as at their entrance, they 
 suffer a refraction, by which the rays are se- 
 parated into their various colors ; and thus 
 therefore are exhibited to the eye properly 
 placed to receive them. In the following cut 
 let E be the spectator, looking at a shower of 
 rain, with his back to the sun. Let A be a 
 drop of rain, and S T a ray of the sun, 
 falling upon the upper part of it, T. Here 
 the greater portion of the rays will suffer 
 refraction, more or less, according to their 
 degree of refrangibility ; the violet passing to 
 V ; the red to R ; and the intermediate co- 
 lors between these points. Some of the rays 
 will here be lost, but the remaining rays 
 will be reflected to B and C, and some, as 
 in the former instance, will pass out of the 
 drop ; but instead of being lost, as before, 
 they will pass to the eye, situated at E, and 
 we shall see them in the direction of the 
 drop, or as reflected against the clouds or sky 
 in the distance. The bow thus formed is 
 called the primary bow ; but there is often 
 perceived a larger and more faintly-colored 
 bow, exterior to the primary — this is called 
 the secondary bow, and is produced by 
 another reflection. It was seen that a ray of 
 light falling upon the top of the drop of rain 
 was brought to the eye after a double re- 
 fraction and one reflection, but when the ray 
 strikes the drop near the bottom, it cannot 
 reach the eye till after two reflections and 
 two refractions, as is seen at O. The light 
 strikes the drop at P, it is refracted to M 
 It passes to N. and afterwards to I. whence 
 it would pass to the eye E ; the differently 
 colored rays separating as before, but ap- 
 pearing to the spectator in the reverse order. 
 When no rain is falling between the spectator 
 and the part of the sky at which the bow 
 passes, a part of the bow will be wanting at 
 that place, so that portions of rainbows are 
 frequently seen, especially near the horizon. 
 
 Rainbow, Lunar. A phenomenon similai 
 to the rainbow, but produced by the light 
 of the moon falling upon drops of rain. 
 
 Rainbow, Marine, or Sea-Bow. This is 
 a phenomenon sometimes observed in a much 
 agitated sea, when wind sweeping over the 
 tops of the waves, carry part of them aloft, 
 so that the rays of the sun are refracted, &c.. 
 as in a common shower. 
 
 Rain Cloud. (See Nimbus.) 
 
 Rain Gauge, or Pluviometer. A mi 
 chine for measuring the quantity of rain thav 
 falls. There are various kinds of rain gauges. 
 An extremely simple one may be made of a 
 tin or copper funnel A B, the area of whose 
 opening is exactly 10 square inches; this 
 funnel is fixed in a bottle C, as shown in 
 fig. 2, and the quantity of rain caught, is 
 ascertained by multiplying the weight in 
 ounces by 173, which gives the depth in 
 inches and parts of an inch. 
 
 Another and superior kind of pluviometer 
 is represented in fig. 1. It consists of a 
 hollow cylinder A, having within it a cork 
 ball B attached to a wooden stem, which 
 jiasses through a small opening at the top, 
 on which is placed a large funnel C. When 
 this instrument is placed in the open air in 
 an exposed place, the rain that falls within 
 the circumference of the funnel will run 
 down into a tube and cause the cork to float, 
 and the quantity of water in the tube may 
 be seen by the height to which the stem of 
 the float is raised. The cock D is to empty 
 the instrument, when necessary. 
 
 Raiser. A board set on edge under the 
 foreside of a step, a stair, &c. 
 
 Raking. In architecture and the arts, is a 
 substance which is placed at any irregular 
 angle with the surface upon which it is placed ; 
 as, for example, the erect frame at the corner 
 of a square bay window, not being set so as 
 to correspond with the mitre, and not agreeing 
 with either the front or side, is said to rake. 
 
 Ram, Water. {See Water Ram.) 
 
 Ramp. In hand-railing, a concavity on the 
 ujiper side, formed over risers, or over a half 
 or quarter space, by a sudden rise of the 
 
RA 
 
 RE 
 
 steps above, which frequently occasions a 
 knee above the ramp. 
 
 Rampant Arch. One whose abutments 
 %pnng from an inclined plane. 
 
 Ram's Horn. A particular kind of scroll 
 
 •ornament, the origin of which is from the 
 
 ■kuU and horns of the ram, as seen below ; 
 
 ttough now more usually partaking of a very 
 
 different and more ornamental character. 
 
 Ranctdity. The change which oils and 
 fats undergo by exposure to the air. 
 
 Range. A term applied to the edges of a 
 number of bodies, placed on a given surface ; 
 thus, if the edges of the ribs of a groined 
 roof were placed on a cylindric surface they 
 would be said to range. 
 
 Rarefaction. In physics, is the making 
 a body to expand or occupy more space or 
 room, without the accession of new matter. 
 The term is more particularly applicable to 
 elastic fluids, which expand so as to fill the 
 vessel in which they are contained after part 
 is extracted. The gas becomes rarefied in 
 consequence of the partial exhaustion. Li- 
 quids are expanded by means of heat, and 
 thence become thinner and more rarefied. 
 
 Rarity. Lightness; thinness; the reverse 
 of density. 
 
 Ratchet Wheel. Ratchet, or Ratch, 
 A bar or a wheel, containing angular teeth,' 
 into which a pall or detent is dropped to pre- 
 vent machines from running back. As, for 
 example, in winding up a clock or watch, 
 the clicking noise heard is derived from the 
 fall of the click or detent into the teeth of 
 the ratchet wheel. 
 
 Ratio, IS the relation or proportion of two 
 or more quantities of the same kind, as to 
 hmit, quantity, or quality. (See Propor- 
 tion: also Arithmetical, Geometrical, and 
 Harmonical.) 
 
 Rational Fractions, is the term com- 
 monly used to express those fractions which 
 may be decomposed into other fractions, the 
 sum of which shall be equal to the original 
 or given fraction. 
 
 Rational Horizon. (See Horizon.) 
 
 Rational Quantities. In algebra, are 
 those which are expressed without any radical 
 sign, bemg equivalent to integers or fractions 
 m arithmetic, which are called rational num. 
 bers or quantities, in contra-distinction to 
 surds. 
 
 Ray, is a single radiation from a body 
 which sends out emissions in all directions. 
 Kays may be convergent, divergent, or pa- 
 rallel according as they are differently re- 
 fleeted or refracted. 
 
 Ray, Calorific. (See Calorific.) 
 Ray, Ordinary ?inA Extraordinary. (See 
 Negative Axis of Double Refraction.) 
 
 Rays, Solar. The light which emanates 
 from the sun, which, as already explained 
 under Prism, are compound ; each simple 
 ray possessing different properties, relative to 
 color degree of refrangibility, illuminating 
 and chemical power, from the rest ; therefore 
 called prismatic rays ; most or least refran- 
 gible rays ; magnetising rays ; illuminating 
 rays ; heating rays, &c. 
 
 Re-Agent. In the experiments on che- 
 mical analysis, the component parts of bodies 
 may either be ascertained in quantity as well 
 as quality, by the perfect operations of the 
 laboratory; or their quality alone may be 
 detected by the operations of certain bodies 
 called re-agents or tests. Thus the infusion 
 of galls is a re-agent, which detects iron by 
 a dark purple precipitate ; the prussiate of 
 potass exhibits a blue with the same metal. 
 &c. 
 
 Realgar. Red orpiment, or the red 
 sulphuret of arsenic. It is employed some- 
 times as a pigment, and occasionally in fire- 
 works. 
 
 Reaumur's Thermometer, (so called 
 from the name of the inventor,) is that in 
 which the space between the freezing and 
 boiling points of water is divided into 80 
 parts or degrees, the freezmg point being 
 marked 0, or zero, and the boiling point 80. 
 The degrees are continued of the same size, 
 both below and above these points, those 
 below being reckoned negative. 
 
 Rebate, or Rabbet. A channel cut in 
 the edge of one board, that another board 
 similarly cut may fit it ; also doors fit into a 
 rabbet cut in the door post. 
 
 Receiver. Generally a vessel to receive 
 the product of any operation ; for example, 
 
RE 
 
 RE 
 
 the globular glass receiver attached to a re- 
 tort, alembic, or matrass, showm at A. It 
 may be either with or without a stopper. 
 A gas receiver is of a different form, being 
 made as shown at B. It is, when in use, 
 placed over the hole of the pneumatic trough, 
 and receives the gas which is made in any 
 other apparatus. The receiver of an air 
 pump is the large glass vessel placed over 
 the pipe or valve, in order to be exhausted 
 of air, being thus called from its being the 
 recipient of those things on which experi- 
 ments are made. One form of it is that 
 «f C. 
 
 Recessed Arches. One arch within 
 another. 
 
 Recession. Going backwards. 
 
 Reciprocal. In arithmetic and algebra, 
 is the quotient arising from dividing unity 
 by any quantity ; thus l-r-^=f. Therefore 
 ^ is the reciprocal of the fraction ■^. 
 
 Reciprocal EauATioNS, are those which 
 contain several pairs of roots, which are the 
 reciprocals of each other ; thus an equation, 
 whose roots are 4,^; 8,-|-; 7,7-, &c., is 
 called a reciprocal equation. Thus far, in 
 fact, it differs in no respect from any other 
 equation, in which a similar relation is known 
 to have place between its roots ; but what 
 is most characteristic of these equations is, 
 that they are known to be reciprocal as soon as 
 they appear, by the order and signs of their co- 
 efficients ; that is, the terms equally distant 
 from either extreme have the same co-efficient ; 
 thus x^ + 5 x*+7 x'^ + 7 a;^ + b af+l=0, is 
 a reciprocal equation. 
 
 Reciprocal Proportion, is when the 
 reciprocal of the two last terms have the 
 same ratio as the quantities of the first terms, 
 or when the antecedents are compared with 
 the reciprocals of the consequents ; thus 
 5 : 8 :: 24 : 15 is a reciprocal proportion, be- 
 cause 5 • 8 :: T^ : -Jj, or 5 : 75^: :: 8 : ^ 
 
 Reciprocal Ratio, is the ratio of the 
 reciprocals of two quantities. 
 
 Reciprocally. Reciprocity. The pro- 
 perty of being reciprocal ; thus we say that 
 bodies of the same weight, the density is re- 
 ciprocally as the magnitude — namely, the 
 greater the magnitude the less is the density, 
 and the less the magnitude the greater the 
 density. So again, the space being given 
 over which a carriage shall pass, of course, 
 the greater the speed the less the time, that 
 is, the velocity and time are reciprocal. 
 
 Reciprocating Spring. An intermitting 
 spring of such a nature, that instead of flow- 
 ing and then ceasing to flow, alternately, it 
 flows at one time rapidly and at another 
 slowly ; its action is of the same nature as 
 the intermitting spring, (which see.) 
 
 Reciprocating Steam Engine. Any 
 steam engine which works by the propulsion, 
 backwards and forwards, of a piston in a 
 cylinder; the word being used in contra- 
 distinction to rotatory engine. 
 
 Reciprocating System, (on a railway,) 
 consists of a succession of stationary steam 
 engines along the whole line, which are fixed 
 about a mile and a half apart, having ropes 
 from one to the other, rollers being fixed 
 along the line to receive the same. When 
 a train of carriages leaves a station, it is 
 secured to the rope, and is thereby drawn 
 along the line, in which case the rope is 
 termed the head rope, and another is secured 
 to the last waggon, which is therefore called 
 the tail rope, which is thus pulled along by 
 the train ; upon returning, it becomes the 
 head rope, and the other the tail rope, thus 
 alternately too and fro. The rope is mostly 
 single, being wound up at one end as it is 
 unwound at the other. 
 
 Reckoning. In navigation, is that account 
 whereby at anytime the latitude and longitude 
 of a ship becomes known, and hence the 
 course she ought to steer to gain the desired 
 port. This is sometimes made from obser- 
 vations, and sometimes from the log book, 
 in which latter case it is called dead reckoning. 
 
 Recliner. In dialling, is used for any dial 
 whose plane reclines from the perpendicular, 
 and if besides reclining it also declines from 
 any of the cardinal points, it is called a re- 
 clining declining dial, and the quantity or 
 angle at which it decUnes or reclines is called 
 its reclination or declination. 
 
 Recoil. The rebound or flying backwards 
 of any kind of fire-arms when discharged. 
 
 Rectangle, Oblong, or Long Square. 
 A geometrical figure whose opposite sides 
 only are equal, and all its angles right angles, 
 as ABCD. 
 
 Rectangular. Any geometrical figure, 
 containing one or more right angles. Solids 
 are said to be rectangular or right, when 
 standing perfectly erect either upon the earth 
 or any other surface. 
 
 Rectangular Lever. A lever made in 
 the form of two sides of a rectangle, as fol- 
 lows : — Its power is the same as if straight. 
 Thus supposing the arm G B to be twice as > 
 
RE 
 
 RE 
 
 long as 6 C ; a weight of one pound at 
 P would raise up two at C. Clawed hammers 
 used to draw nails are bent or rectangular 
 levers. 
 
 Rectification. In mathematics, is the 
 finding of a right line equal to a proposed 
 curve, or simply finding the length of a curved 
 line, a problem which even in the present 
 advanced state of analytical knowledge is 
 often attended with considerable difficulty. 
 In chemistry, rectification signifies the 
 strengthening and purifying various liquids, 
 particularly spirituous liquors, by means of 
 re-distillation ; after which process they are 
 called rectified spirits. 
 
 Rectifying the Globe, is a previous 
 adjustment of it, to prepare it for the solu- 
 tion of particular problems. 
 
 Rectilinear. A figure or solid bounded 
 by straight lines. 
 
 Recurring Decimals. Those which are 
 continually repeated in the same order at 
 certain intervals, as |=-6666, and ^ = 
 •272727, &c. These numbers are therefore 
 recurring decimals. 
 
 Red. One of the primative colors, of con- 
 siderable brilliancy and liveliness. There are 
 an infinite number of tints of red, serving to 
 the uses of painting, as lake, carmine, Ver- 
 million, red lead, orpiment, Venetian red, 
 red ochre, &c., which multiply their own 
 varieties by admixture with other colors, 
 darker or brighter. 
 
 Red Chalk. Red Ochre. A kind of 
 clay iron-stone. 
 
 Reddle. Red chalk. 
 
 Red Fire. This splendidly-colored Are, 
 used in numerous ornamental fire-works, and 
 in imitative conflagrations at theatres, &c., 
 is made by mixing intimately together dry 
 nitrate of strontian, 1^ oz., ; sulphur, 3 
 drachms and 6 grains ; chlorate of potass, 
 1 drachm and 10 grains ; sulphuret of an- 
 timony, 2 drachms ; and charcoal, 1 scruple. 
 The following receipt is as good and more 
 simple : — Nitrate of strontian, 1 oz. ; chlo- 
 rate of potass, 3 dwts. ; charcoal, 3 dwts. ; 
 and pulverized gunpowder, 3 dwts. The 
 chlorate of potass must be powdered by itself, 
 and mixed carefully and gently with the other 
 ingredients afterwards, or the whole .will 
 explode. 
 
 Red Lead. Minium, or the red oxyde of 
 lead ; used as a pigment. 
 
 Red Liquor. The solution of a crude 
 acetate of alumina, employed in calico 
 printing, and prepared from pyroligneous 
 acid. 
 
 Red Precipitate. The nitric oxyde of 
 mercury. 
 
 Red Saunders. A dye drug ; the wood 
 of the Pterocarpus santolina. 
 
 Red Writing Ink. Brazil wood, boiled 
 in water ; or still better boiled in vinegar. 
 
 Reduction, or Revivification. In 
 chemistry ; this word in its most extensive 
 sense is applicable to all operations by which 
 any substance is restored to its natural state, 
 or which is considered as such ; but custom 
 confines it to operations by which metals are 
 restored to their metallic state, after they 
 have been deprived of this, either by com- 
 bustion, as the metallic oxydes ; or by the 
 union of some heterogeneous matters which 
 disguise them, as fulminating gold, luna cor- 
 nea, ciunabar, and other compounds of the 
 same kind. These reductions are also called 
 revivifications. 
 
 Reduction. In arithmetic, is the con- 
 verting or changing a quantity from one de- 
 nomination or state to another, without 
 altering its real value. Thus forty shillings 
 are equal to two pounds — the name is 
 changed, but the value is the same. The 
 reduction of fractions is the bringing them 
 into a simpler and more convenient form ; 
 thus ^^ is equal to f and # of f of |=:^. 
 
 Reduction of a Figure, Design, or 
 Draught. The making a copy of it, either 
 larger or smaller than the original, still pre- 
 serving the form and proportion. The great 
 use of the proportional compasses is in the 
 reduction of figures, &c., whence they are 
 called compasses of reduction. 
 
 Reduction to the Ecliptic. In astro- 
 nomy, is the difference between the argument 
 of latitude, as N P and an arc of the eclip- 
 tic N R intercepted between the place of a 
 planet and the node. To find this reduction 
 or difference, there are given in the right- 
 angled spherical triangle N P R, the angle of 
 inclination and the argument of latitude N P, 
 to find N R ; then the difference between 
 N P and N R is the reduction sought. 
 
RE 
 
 RE 
 
 Reed. That part of a loom resembling 
 the teeth of a comb, between which the 
 threads of the warp are separated. 
 
 Reeding. A number of beaded mould- 
 ings united together, as is often seen in 
 chimney jambs, wooden pilasters, common 
 picture frames, &c. 
 
 Re-Enter. In engraving, this phrase is 
 sometimes used to denote the passing of the 
 graver into the incisions of a copper plate, 
 either when worn out, or when the acid has 
 not bitten enough, in order by deepening 
 them to give them greater strength. 
 
 Reels. Rotatory cylinders or bobbins, on 
 which lines, threads, &c. are wound. 
 
 Refi-ection, or Reflexion, is a term 
 generally used in natural philosophy, to de- 
 note the rebound of the rays of light, heat, 
 or sound, from an opposing surface. Polished 
 surfaces reflect the light to the eye, and are 
 therefore more generally called reflectors or 
 mirrors. Heat and sound are reflected with- 
 out reference to the eye, and are returned 
 from more rugged objects. 
 
 Reflection, Angle of. (See Angle of 
 Incidence and Reflection.) 
 
 Reflectors. (See Reflection.) 
 
 Reflecting Microscopes and Tele- 
 scopes, are those which act by reflecting the 
 light from a specula within them to the eye ; 
 such are the Newtonian and Gregorian tele- 
 scopes. 
 
 Reflectoire Curve, is a term given to 
 the curvilinear appearance of the plane sur- 
 face of a basin containing water to an eye 
 placed perpendicularly over it. In this po- 
 sition, the bottom of the basin will appear 
 to rise upwards from the centre outwards, 
 but the curvature will be less and less, and 
 at last the surface of the water will be an 
 asymptote to it. 
 
 Reflex, or Reflect. In painting, is 
 understood of those places in a picture which 
 are supposed to be illuminated by a light re- 
 flected from some other body represented in 
 the same piece. 
 
 Refraction. When we immerse one end 
 of a rod in a slanting direction, in a vessel of 
 water, the part immersed appears as if it were 
 bent or broken at the surface of the liquid. 
 This phenomenon is in the consequence of 
 the rays of light, (by which the rod is ren- 
 dered visible,) being bent in their course ; 
 the straight lined direction in which they 
 originally issued, being changed by falling on 
 another medium. Refraction is therefore 
 used in natural philosophy as the denomina- 
 tion of that deviation from its course, which 
 a body invariably experiences when passing 
 
 in an oblique direction from one fluid medium 
 to another of a different density. The term 
 is generally appUed to the rays of light as 
 they pass through transparent bodies. 
 
 Refraction, Atmospheric. As the den- 
 sity of the atmosphere increases from the 
 highest limits of it, more and more, till it 
 reaches the earth's surface, so a ray of light 
 passing through it from the sun, &c. , becomes 
 in like manner more and more refracted, and 
 instead of continuing in a straight line be- 
 comes bent into a curve, unless it strikes the 
 atmosphere perpendicularly, when no refrac- 
 tion takes place ; but becomes greater and 
 greater in proportion as the radiant or illu- 
 minating, or, in other words, in proportion as 
 the ray of light passes near to the horizon, 
 thus : — 
 
 Let A represent a portion of the earth. 
 BB the atmosphere. E the place of the 
 spectator, and F G his horizon. The ray of 
 light C D coming perpendicularly is not re- 
 fracted, but the other rays H I, J K, and LM, 
 are refracted, and the more so as they are 
 nearer the horizon. Thus H I will take the 
 course indicated by I E ; J K will pass along 
 K E ; and the course of L M will be repre- 
 sented by M E. Now as it is a well-known 
 fact, that objects always appear in that di- 
 rection in which they last meet the eye, so in 
 all the above cases, except the first, the ray 
 of light or the luminous body will appear in 
 a higher position than that it really occupies. 
 Thus the star at L will not appear in its true 
 place, but considerably higher up, as seen atN, 
 and be in reaUty visible for some minutes 
 after it has been below the horizon. Thus in 
 all astronomical and nautical observations the 
 refraction of the atmosphere must be ascer- 
 tained and allowed for. 
 
 Refraction of Altitude, of Ascen- 
 sion OR Descension, of Latitude, 
 Longitude, &c., are the alterations which 
 take place in the apparent altitude, ascension, 
 &c. of the heavenly body examined, which 
 are occasioned by atmospheric refraction. 
 
 Refraction, Double. A peculiar kind of 
 refraction observed in Iceland spar, and some 
 other crystals, in looking through which an 
 object appears double ; an example of which 
 is given under the word Carbonate of Lime. 
 
 Refracting Microscopes, Telks- 
 ccfPEs, 8fc., are such as show a magnified 
 
RE 
 
 RE 
 
 image of an object, by means of rays of light 
 refracted and collected into a focus through 
 
 Refractive Power. The various trans- 
 parent media refract the rays of light in dif- 
 ferent degrees. Let A B, H I in the following 
 cut be a transparent body, on which a ray C D 
 falls or incides from a luminous point C, 
 upon the plane surface AD at D. Where 
 this ray to preserve a straight course, it would 
 pass on to the point E ; but meeting with 
 another medium at the point D, it is reflected 
 to F, so that the luminous point C would be 
 seen by the eye at F, and not at E. Draw 
 the right line C D H perpendicular to A B, 
 through the point of incidence D, the angle 
 C D G is the angle of incidence, and H D F 
 is the angle of refraction. These angles have 
 a fixed relation to each other, in the same 
 transparent body, whatever the angle of inci- 
 dence may be ; but that proportion is diffe- 
 rent in some bodies from what it is in others, 
 and hence those bodies are said to have a 
 greater or less refractive power. 
 
 Refrangibility, is the capability of 
 being refracted, and has been employed to 
 designate the degree of that property which 
 is possessed by the several divisions of a ray 
 of light. It is owing to their various re- 
 frangibilities that the threads or rays sepa- 
 rate from each other in passing through 
 the prism, and thereby form the colored 
 spectrum. 
 
 Refrigerator. An apparatus designed 
 to cool the worts of a brewhouse or any 
 other hot liquid, which it is desirable to cool 
 rapidly. There are numerous kinds of re- 
 frigerators in common use. That of the 
 screw-shaped pipe, used with the still, is 
 well known. The following is one out of 
 the very numerous designs furnished by the 
 inventor, Mr. Yandall, for this purpose. 
 The principle of all is the same, namely, pass- 
 ing the hot liquid through or between pipes or 
 silxfaces which are immersed in cold water : — 
 A shows a series of zigzag channels made 
 in obliquely descending planes. B is the 
 funnel for the hot liquor, whence it descends 
 through the pipe D into the upper channel ; 
 passing through all the channels it is ulti- 
 mately discharged through the pipe C at the 
 
 cock E. The cold water being introduced 
 into the funnel E, and passing down the pipe 
 I, enters and fills the spaces between the 
 channels, and rising through the apparatus, 
 runs off by the pipe G, and is discharged at 
 the cock below. 
 
 Regenerated Sea Salt, or the Di- 
 gestive Salt of Silvius. The muriate 
 of potass, or rather the chloride of potassium. 
 
 Register. An aperture or valve placed in 
 a chimney, stove or furnace, furnished with 
 a turning or sliding door, for regulating the 
 quantity of air to be admitted to the fire, or 
 to open and shut the communication with the 
 chimney at pleasure. A register is also any 
 contrivance for noting down or calculating 
 the performance of an engine, or the rapidity 
 of a process. (See Gas.) 
 
 Register Thermometers, are those 
 instruments which by some contrivance re- 
 gister the greatest or least degree of heat 
 which has occurred since the time of the last 
 observation. (See Keith, Cavendish, Six, 
 BlacJcadder, Trail, &^c.) 
 
 Reglet. In architecture, a flat narrow 
 moulding, employed to separate panels and 
 other members, or to form knots, frets, or 
 other ornaments, on a flat surface. 
 
 Regnier's Metalline Thermometer. 
 This instrument consists of two plates of 
 brass, fixed in an iron frame, in a bent posi- 
 tion, with their concave surfaces towards each 
 other ; (see cut.) On one is a pinion of 
 eight pallets on an axis, the end of which 
 supports an index to mark the temperature. 
 To the centre of the other plate is attached 
 a toothed rack, in the position of the versed 
 side of the curve, playing in the pallets of 
 
RE 
 
 RE 
 
 the pinion. When the plates are cooled they 
 approach each other ; when heated their cen- 
 tres recede, and the only circumstances of 
 consequence in the position of the bars or 
 plates, are that they should be at some little 
 distance from each other, and so bent that 
 they cannot become parallel by any reduction 
 of temperature to which they may be exposed. 
 
 Regrating. Among masons, &c., taking 
 off the outer surface. &c., of an old hewn 
 storre wall, in order to whiten and make it 
 look fresh again. 
 
 Regular Body. (See Body.) 
 
 Regular Figure. Any figure all of the 
 sides and angles of which are equal. 
 
 Regulator. (See Governor.) 
 
 Regulator. A small lever in watch work, 
 wnich by being moved increases or decreases 
 the amount of the balance spring that is 
 allowed to act. 
 
 Regulus. An old name to designate a 
 metal when in a refined metallic state, as op- 
 posed to the state of sulphuret, or other ore 
 of the same. It is now principally applied 
 to the regulus of antimony and arsenic. 
 
 Regulus Stellatus, or Martial Re- 
 gulus, is an alloy formed by melting anti- 
 mony and iron together. 
 
 Rejointing. The filling up the old joints 
 of walls with fresh mortar. 
 
 Relation. In mathematics, is the same 
 as ratio, although it is sometimes used in a 
 more general sense, indicating any depen- 
 dence of one number or quantity upon 
 another. 
 
 Relievo. A projection of carved work. 
 (See alto-relievo and basso-relievo.) 
 
 Relievo. In painting, denotes the degree 
 of force or boldness, by which a figure seems 
 at a due distance to stand out from the ground 
 of the painting, as if really embossed. 
 
 Remainder. That which is left after 
 taking away a number or quantity from one 
 which is greater. It is therefore the result 
 of substraction. 
 
 Rendering. A name for the first coat of 
 plaster on walls, and to the inside of chimney 
 flues ; also called pargetting. 
 
 Repetend. In arithmetic, denotes that 
 part of a circulating decimal which is re- 
 
 peated, as in 1*666 the repetend is tiie 
 figure 6. 
 
 Repulsion, is the name of a power or 
 principle in the particles of natural bodies, 
 by which under certain circumstances they 
 refuse to meet or coalesce with each other. 
 It is the opposite of attraction, and equally 
 inexplicable. 
 
 Repulsion, Electrical. Two bodies elec- 
 trified in the same manner repel e£ich other, 
 because the particles of the electric fluid are 
 repellant one of another. Very numerous 
 experiments exemplify this kind of repulsion ; 
 one example may suffice : — Warm a thick 
 glass tube, then rub it with dry flannel, and 
 lay a fleecy feather upon it ; after a few mo- 
 ments the feather will be repelled from the 
 electrified tube, and may by holding the tube 
 towards it be driven about the room. 
 
 Repulsion, Mc^ne^ic. The power exerted 
 by the similar poles of two magnets upon 
 each other ; thus two north or two south 
 poles repel one another. 
 
 Reservoir. A large pond or pen of 
 water artificially made, in order to retain 
 and collect it for the use of canals, rivers, 
 mills, &c. 
 
 Residual Quantity. In algebra, is a 
 binomial connected by the negative sign ; 
 thus a—h and a— Vb are residual quanti- 
 ties. 
 
 Residue, or Residuum. That which re- 
 mains as the fingJ result of any mechanical 
 or chemical operation ; thus coke is the re- 
 siduum left in the retort after gas has been 
 extracted from coal. 
 
 Resins. Peculiar vegetable principles, 
 which are known by being insoluble in water, 
 but soluble in alcohol. They are procured 
 in two ways, either as a spontaneous exudation 
 from plants, or by extraction by heat or 
 alcohol. Resins melt by the application of 
 heat, but do not volatilise without partial 
 decomposition. They are mostly translucent, 
 and more or less of a brown color. A few 
 of them are soft, but the greater number 
 hard and brittle. They take fire by contact 
 of an ignited body, and burn with a bright 
 flame and much smoke ; assisted by heat 
 they combine readily with the oils, and also 
 with alkalies, in the latter case forming soaps. 
 The soft resins which contain a portion of 
 essential oil, are called balsam. The hard 
 resins are amber, anime, benzoin, colophony, 
 (common rosin,) copal, dammara, dragon's 
 blood, elemi, guaiacum, lac, resin of jalap, 
 ladanum, mastic, sandarac, storax, and 
 tacamahac. 
 
 Resin of Copper. Proto-chloride of 
 copper. 
 
 Resinous Electricity, or Resinous 
 Fluid of Electricity. That which is pro- 
 duced by the friction of resinous substances, 
 which is contrary in its nature from thai 
 
RE 
 
 RE 
 
 produced by the friction of vitreous bodies. 
 (See Du Fay.) 
 
 Resistance, or Resisting Force. Any 
 power that acts in opposition to another, so 
 as to destroy or diminish its effect. Of re- 
 sistance there are several kinds, arising from 
 the various natures and properties of the re- 
 sisting bodies, and governed by various laws, 
 as the resistance of solids, the resistance of 
 fluids, the resistance of the air, &c. 
 
 Resistance, Solid of Least. That shaped 
 body which will be least impeded in passing 
 through the air or water. The figure is 
 thus :— 
 
 Let D N G be a curve of such a nature, 
 that if, from the point N, the ordinate N M 
 be drawn perpendicularly to the axis A B ; 
 and from a given point G there be drawn 
 G B parallel to a tangent at N, and meeting 
 the axis produced in R ; then if N M be to 
 G B as G R3 to 4 B R X B G2, a soUd de- 
 scribed by the revolution of this line about 
 its axis A B, moving in a medium from A to 
 B, will be the solid required. 
 
 Resolution. In a general sense, is the 
 separating of a compound body into its sepa- 
 rate original parts. 
 
 Resolution of Forces. (See ParaU 
 lelogram of Forces.) 
 
 Rest. The continuance of a body in the 
 same space, either relatively or absolutely. 
 We have no example in nature of a body 
 being absolutely at rest; thus, the earth 
 moving, all upon it must move also; the 
 sun himself has two motions, not merely re- 
 volving around his axis, but even in an orbit 
 around a certain point near to his body. 
 
 Rest. That part of a lathe upon which 
 the tools are supported during the operation 
 of turning. The ordinary rest is exhibited 
 below, where A A represents part of the bed 
 of the lathe. B P B is the foot of the rest. 
 It is fastened down by means of the clamp 
 F, which is connected with the screwed bolt 
 and nut G. Turning this nut one way or 
 the other, as required, loosens or fastens the 
 rest to the bed of the lathe. C is a hollow 
 cylindrical socket for the reception of the 
 round shank of D. This part, which is truly 
 the rest, and upon which the tools are held, 
 may be loosened or held fast, and set higher 
 or lower, as required, by means of the screw 
 at E. The top of D is made of steel, and 
 
 quite smooth and flat, 
 instrument is of iron. 
 
 The remainder of the 
 (See Slide Rest.) 
 
 Restii UTION, Motion of. A term used by 
 some to denote the return of elastic bodies to 
 their nat\iral form, after compression or 
 bending. 
 
 Resultant. In mechanics, is used to de- 
 note that single force or the line representing 
 the quantity of that single force, which is 
 equivalent to two or more forces whose quan- 
 tities and directions are given. 
 
 Resultant Force. That which results 
 or proceeds from a power exerted ; the com- 
 bined eflFect of several powers. 
 
 Retaining Wall. A wall used for the 
 support and maintainance of a body of earth, 
 when circumstances render it inexpedient to 
 slope the same gradually down. 
 
 Reticulated Work. A species of ma- 
 sonry, formed of small square stones or bricks, 
 placed lozenge-wise. 
 
 Retinasphaltum. a resinous substance, 
 which accompanies certain kinds of coal, 
 particularly the Bovey coal of Devonshire, 
 and some of the Staffordshire coal. It was 
 first analyzed by Mr. Hatchett, who found it 
 to consist of 55 parts of rosin, 41 asphaltum, 
 and 4 earthy matter. 
 
 Retort. A chemical instrument, for 
 holding solids or liquids for the purpose of 
 distillation. According to the heat that it is 
 to be submitted to, and the nature of the 
 substance contained, so retorts are of diffe- 
 rent forms, and made of different materials ; 
 thus for the making of various gases cast- 
 iron retorts are commonly employed. Fluo- 
 rine requires one of silver or lead. In the 
 manufacture of the acids, earthenware retorts 
 are mostly employed ; and for ordinary pur- 
 poses of distillation, and other chemical 
 operations, glass is the material approved of ; 
 
RH 
 
 RH 
 
 such retorts being usually made of the re- 
 presented shape. 
 
 Retrogradation, or Retrogression. 
 In astronomy, is an apparent motion of the 
 planets, by which they soem to move back- 
 wards in the ecliptic, or in antecendia or 
 contrary to the order of the signs. 
 
 Return. In building, denotes a side or 
 part that falls away from the front of any 
 straight work. 
 
 Revels, or Reveals. The space between 
 the exterior surface of a wall and the frame 
 of a recessed window or door. 
 
 Reverberatory Furnace. ''See Fur- 
 nace.) 
 
 Reversion. An annuity which is not to 
 commence till after a certain number of years. 
 
 Revolution. In geometry, the motion 
 of any figure quite round a fixed line, as an 
 axis. Thus a right-angled triangle, revolving 
 round one of its legs as an axis, generates by 
 that revolution a cone. 
 
 Revolution, Period of. In astronomy, 
 is the time a planet, comet, &c., employs in 
 passing from one point of its orbit to the 
 SBme point again. This with regard to the 
 earth determines the length of the year. 
 
 Rhabarbarin. The purgative principle 
 of rhubarb. 
 
 Rhabdology. a name given by Napier to 
 his method of performing multiplication, 
 division, &c., by means of small bones or 
 rods. (See Napier's Bones.) 
 
 Rhaponticin, is a substance obtained 
 from the Rheum rhaponticum in the form 
 of yellow scales, inodorous, insipid, and in- 
 soluble in cold water ; soluble in 24 parts of 
 hot water, and in 2 of anhydrous alcohol. 
 
 Rhein. When 1 part of powdered rhu- 
 barb is gently heated with 8 of nitric acid, 
 sp. gr. 1*37, and the liquor evaporated to 
 the consistence of syrup and diluted with 
 cold water, an orange colored powder is de- 
 posited, which M. Vaudin has termed Rhein. 
 
 Rhodio-chlorides. Compounds of rho- 
 dium and chlorine, in combination with the 
 chlorides of potassium or sodium, thus 
 forming double salts. They are composed of 
 1 atom of the perchloride of rhodium and 
 1 of the basic chloride. 
 
 Rhodium. A metal discovered in 1803 by 
 Dr.WoUaston, disseminated in an ore of pla- 
 tinum. It is very difficult of fusion ; its 
 specific gravity is about 11. When pure it 
 is not soluble in any of the acids, unless 
 previous to immersion it is alloyed to some 
 other metal. It unites to oxygen in one 
 proportion, forming a peroxyde ; also with 
 chlorine forming a perchloride. It forms 
 alloys with other metals, but not with mer- 
 cury. Its alloy with steel is a valuable 
 compound. 
 
 Rhombic Spar. Iceland spar, or the 
 doubly-refractive carbonate of lime. 
 
 Rhomboid. A geometrical figure, with the 
 opposite sides equal, but not the adjacent 
 sides, and the angles not right angles. The 
 figure is shown with that of rhombus at 
 letter A. 
 
 Rhombus. A geometrical figure, whose 
 sides are all equal, and its angles not right 
 angles, as B. 
 
 Rhumb Line, or Loxodromia. In na- 
 vigation, is a line prolonged from any point 
 in a sea chart, except in the direction of any 
 one of the cardinal points. A ship's way is 
 therefore not to be computed, as if her cdurse 
 were made in a great circle of the sphere, but 
 as made up of the successive arcs of this line 
 or spiral, the principles of which may be 
 illustrated as follows : — 
 
 Let P be the pole. RW the equator. 
 A B C D E F a spiral rhumb, divided into an 
 indefinite number of equal parts at the points 
 B C D, &c., through which are drawn the 
 meridians PW, PR, &c., and the pa- 
 raUelsFB, K C, DD, &c., also draw the 
 parallel A N. Then as a ship sails along the 
 rhumb line towards the pole, or in the direc- 
 tion A B C D from A to E ; the distance 
 sailed A E is made up of all the small equal 
 parts of the rhumb AB + BC + CD + DE, 
 and the sum of all the small differences of 
 latitude inake up the whole difference of 
 latitude A M or E N ; and the sum of all the 
 parallels FB + GC + HD + IE is what is 
 called the departure in plane sailing, and M E 
 is the meridional distance, or distance between 
 the first and last meridians, measured on the 
 last parallel ; also R W is the difference of 
 longitude, measured on the equator ; so that 
 these last three are all different, viz. the de- 
 parture, the meridional distance, and the 
 difference of longitude. 
 
RI 
 
 RI 
 
 Ribs. The mouldings upon a groined roof, 
 distinguished by their position as groined 
 ribs, ridge ribs, and surface ribs, horizontal, 
 transverse, and diagonal. 
 
 RiciNic Acid. An acid obtainable from 
 the ricinus communis, or castor oil. 
 
 Ricochet Firing. In the practical part 
 of gunnery, is a method of firing with small 
 charges and at small degrees of elevation, 
 in consequence of which the bedl is constantly 
 bounding and rolling along, and thus destroy- 
 ing more men than a greater charge and 
 greater elevation. 
 
 Ridge. The upper edge of a roof. 
 
 Ridge Piece. The piece of timber which 
 lies along the ridge of a roof, and to which 
 the rafters are attached at top. 
 
 Rigger. A cylindrical or drum-shaped 
 pulley. 
 
 Rigging. A general term given to all the 
 ropes of a ship, whether to support the masts 
 or to maneige the sails. 
 
 Right-Angle, Line, &c. (See Angle, 
 Line, 8fc.) 
 
 Rigidity. A stiffness or hardness ; par- 
 ticularly applied to ropes and other matters 
 which should be pliable, but which lose their 
 pliability by want of use, wet. or some other 
 similar cause. 
 
 Rilievo. (See Relievo.) 
 
 Ring. In architecture, an annulet around 
 a column. 
 
 Ring. In geometry, a surface or solid ; 
 the space between one concentric circle or 
 oval and another cut out of it. It may be 
 either superficial or sohd. 
 
 Ring of Saturn. In astronomy, is a 
 broad, opaque, circular body encompassing 
 the equatorial regions of that planet at a 
 considerable distance from him. This ring, 
 which is very thin, (about 4500 miles,) re- 
 volvesfromeasttowestinl0h.,29ra.,16",8'", 
 being nearly the time of the diurnal revo- 
 lution of Saturn. When examined in its 
 most favorable situation, it is found to con- 
 sist of a double ring, one within the other. 
 The diameter of the planet is 76068 English 
 miles ; the inner diameter of the double 
 ring is 146345 miles ; the outer diameter of 
 the outer ring 204883 miles. 
 
 Ring Chuck. A very useful chuck for 
 many purposes, and one which is easily made. 
 It consists of a block of hard wood, turned, 
 and tapped with a screw at one end, to fit 
 the screw of the mandril of a lathe. The 
 surface is turned slightly, tapering towards 
 Uie point, a hole turned some distance up 
 
 the axis, and two saw-cuts made across the 
 axis, and continued some distance, longi- 
 tudinally, up the chuck. An iron or brass 
 ring fits tightly over the end. If the piece 
 of wood to be turned be fitted tightly in the 
 hole, it may be further tightened by driving 
 the ring upwards. 
 
 Ring Fence. An estate or portion of 
 ground is said to be inclosed by or contained 
 in a ring fence, when a line may be carried 
 around every part ; that is to say, when a 
 person may pass quite round it without 
 entering another person's premises, or leaving 
 out any of his own : or, when no part of the 
 estate is detached from the rest by lands be- 
 longing to other proprietors. 
 
 Rising. In astronomy, the first appear- 
 ance of the sun, moon, or other celestial 
 body above the horizon. 
 
 Ritchie's Electro-Magnetic Rota- 
 tory Apparatus. This is an extremely 
 interesting piece of apparatus, simple in itself, 
 and which yet shows the power of electro- 
 magnetism, in producing rapid and powerful 
 rotatory motion. It consists of a horse- 
 shoe magnet A A, supported on a stand B. 
 
 A central wire C supports a wooden cup D, 
 which has a channel in it to hold mercury, 
 and a bar across it to cut this channel into 
 two cells, so that the mercury of the one 
 does not touch the mercury of the other, 
 and yet enough of mercury is to be put in 
 that it may rise rather above the cross piece. 
 F is a bar of soft iron of a length just suffi- 
 cient to pass between the poles of A. It has 
 a point proceeding from the centre, upon 
 which it is supported upon the top of C. It 
 is also twisted round with a coil of wire, the 
 two ends of which dip into the mercury of 
 the cells, but they are not so long as to be 
 impeded by the cross bar. In the cup D 
 are two holes, one in each cell, proceeding 
 from the upper rim, slanting so as to touch 
 the mercury ; these holes are for the wires 
 proceeding from nn electro-magnetic battery, 
 z z 
 
 46 
 
RO 
 
 RO 
 
 Ritchie's Galvanometer, is thus des- 
 cribed and figured : — A representing the ex- 
 ternal form, and B the section of the instru- 
 ment. It acts upon the principle of tortion. 
 G is a fine thread of glass, which is suspended 
 from the top of the frame, so that it shall be 
 free to move the index C, which travels 
 round a small graduated circle. The lower 
 end of the glass filament bears two small 
 magnets SN, placed with their poles reversed 
 to each other. A B is a coil of fine wire, 
 covered with silk or wax, to convey the 
 galvanic fluid so as to influence the magnets, 
 which magnets it may be remarked are made 
 of common sewing needles magnetised. The 
 glass thread is kept steady by passing through 
 a hole made in a little arm below, and through 
 a hole made in the centre of the upper side 
 of the coil A B, by turning the wires some- 
 what aside each way. The frame is of two 
 long strips of wood, supported on a wooden 
 foot, and the coil and needles are inclosed in 
 a glass box to prevent agitation from the air. 
 
 River. In geography, a stream or current 
 of fresh water flowing in a bed or channel 
 from its source or spring into the sea. 
 
 Rive, De la. (See De la Rive.) 
 
 RocELLA. The name of a lichen used in 
 dyeing, 
 
 RocELLic Acid. An acid extracted from 
 the rocellaweed and some other lichens. It 
 combines with lime, forming a rocellate. 
 
 RocHELLE Salt. Tartrate of potass and 
 soda. 
 
 Rock Cork. A kind of asbestos. 
 
 Rock Crystal. Quartz or silica, in a 
 State of very considerable purity, transparent, 
 
 and crystallised in hexagonal prisms, with 
 pyramidal terminations. 
 
 Rock Salt. The common marine salt, or 
 chloride of sodium, in mass, as dug up at 
 various places, particularly near Cracow, in 
 Poland, and at Northwich, in Cheshire. 
 
 Rock Wood. One of the numerous 
 varieties of asbestos. 
 
 Rocket. A fire-work or military pro- 
 jectile, which being lighted, is carried by its 
 own conflagration to a considerable distance, 
 and finally explodes, scattering sparks or 
 burnin g materials in every direction . Rockets , 
 as made for amusement, consist of the stick, 
 which steadies them in their flight ; the body 
 of the rocket, which contains the composition 
 that propels it forward ; and the head of the 
 rocket, which finally bursts and scatters 
 stars, rains, sparks, &c. The sizes of rockets 
 are known by the size of the cases ; that case 
 in which a leaden bullet of 2 oz. weight 
 will just fall, is called a 2 oz. rocket, 
 and so on for other sizes. The manufacture 
 of rockets may be briefly stated as follows : — 
 The case is first made, by rolling thick paper, 
 pasted at the outer edge, round a stick of 
 the proper size, called a former, until of 
 proper thickness, which is about one-third 
 that of the former ; while still damp with 
 the paste, tie or choke one end, leaving a 
 hole in the middle of the choke. When the 
 case is dry, put it in a proper sized rocket 
 mould, and ram in, a little at a time, some 
 of the composition. When nearly full, turn 
 down the edges of the paper upon it, and 
 pierce some holes through the edges when 
 turned down — then fill up with stars, rain, 
 or sparks, and scatter among them some loose 
 gunpowder ; close the top with a conical 
 paper cap, and tie it on the stick, the length 
 of which is 5 feet 1 inch for 2 oz. rockets ; 
 5 feet 3 inch for 4 oz. ; 6 feet 2 inch for 
 8 oz., &c., each about f of an inch thick. 
 There are several kinds of rockets. A re- 
 presents a common small rocket, the head of 
 which is supposed to be loaded with a quarter 
 of an ounce, or more, of gunpowder. B is 
 called a petard rocket, or one with stars, 
 rains, &c. ; the head is made of a separate 
 
RO 
 
 RO 
 
 case, made larger than in the common rocket. 
 C is called a caduceus rocket — it consists of 
 two rockets joined together, as represented. 
 When fired, this rocket assumes a beuutifully 
 spiral course upwards. D is an honorary 
 rocket — it is made without a head of starS; 
 but instead of this has a small case filled 
 with a strong composition, which takes fire 
 when at the highest point of the rocket's 
 course, which, therefore, in descending, de- 
 scribes a beautiful scroll of fire. E is a line 
 rocket, or one which has a second case at- 
 tached to it, in which is passed a long rope ; 
 when fired, the rocket will run swiftly along 
 the rope. 
 
 Rockets, Composition for. Small rockets 
 may be filled with a composition of meal 
 powder 1 lb. 4 oz. ; saltpetre 4 oz.; and 
 charcoal 2 oz. For large rockets, take meal 
 powder 1 lb. ; saltpetre 4 oz. ; brimstone 
 
 3 oz. ; charcoal 1^ oz. 
 
 Rocket, Rains for. Golden rain: — Saw- 
 dust 1 oz. ; sulphur 2 oz. ; glass-dust 3 oz. ; 
 nitre 8 oz. ; and meal powder 2 oz. Silver 
 rain: — Nitre ^oz.; sulphur 2 oz.; &nd char- 
 coal 4 oz. Ram it into small cases. 
 
 Rocket, Stars for. Nitre 1 lb.; sulphur 
 4i oz. ; sulphuret of antimony 4 oz. ; isinglass 
 i oz. ; camphor \ oz. ; spirits of wine f oz. 
 White stars :—lslea\. powder 3 oz.; nitre 
 16 oz.; sulphur 8 oz. Blue stars: — nitre 
 
 4 oz.; meal powder 8 oz.; sulphur 2^ oz. 
 Crimson stars: — Sulphur 1 oz.; sulphuret 
 of antimony 1 oz. ; chlorate of potass 1 oz. ; 
 and nitrate of strontian 5 oz. Make into 
 a paste with spirits of wine and ishiglass, 
 and cut up into small pieces. 
 
 Rocket Mould and Rammer. A mould 
 in which to ram rockets, and a driver for it. 
 The former consists of a solid wooden foot, 
 with a projecting piece above, C, a tapering 
 wire passing upwards, D, and a thick brass or 
 iron cylinder A, that exactly fits on to the pro- 
 jection on the top of the foot-board. The hole 
 in the cylinder exactly fits the rocket case. 
 The rammer E is made of hard wood, with 
 a hole drilled up it for ths wire to penetrate 
 when the rocket is rammed, the intention of 
 the wire being to preserve a hole up the 
 centre of the rocket, that a large quantity of 
 the composition may be fired at once. 
 
 RocK-woRK. A construction of mis- 
 shapen, rough, and irregular blocks or pieces 
 of stone, sonaetimes intermixed with shells, 
 and designed to represent the unpolished and 
 angular appearance of a surface of rock. 
 This kind of work is principally employed to 
 construct grottos, banks, &c. 
 
 RoESTONE, Oolite. It is called roestone 
 from being composed of an aggregation of 
 very small circular grains, like those of the 
 roe of a fish. When the grains are of a large 
 size it is called peastone. 
 
 Roll and Fillet. A round moulding 
 with a small square fillet on the face of it. 
 
 Roll Moulding. A moulding used in 
 Gothic architecture, the upper half of which 
 projects over the lower part, as if it were 
 formed of a thick substance rolled up. 
 
 Roller. A cylinder of metal or wood 
 used for various purj)oses. A roller placed 
 under a heavy body will enable it to move 
 with leiis friction than a wheel, that is as long 
 as the roller's path does not deviate from the 
 line of motion. 
 
 Rollers, Friction. (See Friction.) 
 
 Rolling Mill. A term frequently ap- 
 plied to the machinery by which metals are 
 compressed into sheets by means of rollers. 
 
 Rolling Press. Under this term very 
 numerous machines might be described, even 
 the common mangle is a rolling press, and 
 so may be considered the garden roller. 
 The instrument, however, which peculiarly 
 is called the rolling press, is that used by the 
 copper-plate printer, and which still more 
 frequently is called the copper-plate press. 
 Its construction is as follows : — 
 
 A A A is a frame -work of iron or wood ; 
 at C is a large roller underneath the platform 
 or bed of the press F. In some presses there 
 are, instead of this, a series of small rollers 
 under F, as in the cut ; but these are not 
 used in conjunction with the larger roller. 
 D is a fold of flannel passed partly round the 
 great roller ; this is held up by one or two 
 strings, with a pin to hook on to the flannel, 
 and at the other end to pass over a pulley I, 
 the weight K keeping the string tight. L L L 
 are four arms, whereby the press is worked. A 
 
RO 
 
 RO 
 
 properly-inked copper-plate is placed upon 
 the table F and under the flannel, a sheet of 
 damped paper is placed over it, and the arms 
 being turned round, the roller D presses 
 upon the paper and plate, and, at the same 
 time, carries them forward to the other side ; 
 where, upon being taken up, the paper will 
 be found impressed with the ink of the plate. 
 
 Roman Balance, or Steelyard. (See 
 Steelyard.) 
 
 Roman Candle. A particular kind of 
 fire-work, made thus : — Take a long case, 
 choked at one end, pour into it a thimble 
 full of gunpowder — then a round rocket star, 
 which has a hole pierced through it — then 
 ram down a rocket composition to the depth 
 of about an inch. Again pour in gun- 
 powder, a star, and composition, as before, 
 till the whole case is filled up. When fired, 
 the first composition bums, throwing up 
 sparks — then the star is ignited, and thrown 
 upwards by the gunpowder ; the same effect 
 takes place agahi, and again, till the whole 
 contents are consumed. 
 
 Roman Cement. A species of lime, 
 which when mixed with river sand soon 
 consolidates into an extremely hard concrete, 
 or mortar, which is valuable in building, to 
 imbed the brick and stone-work for foun- 
 dations, as a lining for reservoirs, and par- 
 ticularly as a covering for buildings, defend- 
 ing them from the weather. 
 
 Roman Order. An order of architecture 
 invented by the Romans from the Ionic and 
 Corinthian orders of the Greeks, and hence 
 it has also obtained the name of the Com- 
 posite order. (See Composite.) 
 
 Roman Vitriol. Blue vitriol, or sulphate 
 of copper. 
 
 RoMANEsauE. A term applied to the ar- 
 chitecture and other works of art executed 
 during the fall of the Roman empire, inclu- 
 ding the period from the reign of Constantine 
 to the introduction of the pointed Gothic, 
 about the year 1100. 
 
 Rood Loft. The gallery over the entrance 
 into the choir in our ancient cathedral and 
 abbey churches, in the front of which, looking 
 towards the west window, a large rood or 
 crucifix was usually placed. 
 
 Roof. A covering to a building. A roof 
 of one row of rafters is called a lean-to roof ; 
 of two rows, meeting in the middle, a span 
 roof; if sloped at the end a hipped roof; if 
 upright at each end a gabled roof. Large 
 roofs are formed upon trusses or frames 
 of timber. The two most common trusses 
 are the king-post truss, where a single post 
 supports the ridge of the roof, and the queen- 
 post truss, where two posts are placed under 
 the purlins, as is seen in the following cuts, 
 where the position of the principal timbers 
 is shown : — 
 
 A king post. B B queen posts. C C C C 
 braces. D D tie beams. E E E E principal 
 rafters. F F ridge piece. G G G G purlins, 
 which are pieces of timber running length- 
 wise along the roof. J J J J common rafters. 
 K K K K the pole plates. L L L L wall 
 plate, on which the ends of the tie beams rest. 
 
 Root. In arithmetic and algebra, denotes 
 a quantity which being multiplied a certain 
 number of times into itself, produces another 
 number called a power, and of which power 
 the original quantity is called the root. If 
 one multiplication only is necessary, it forms 
 the second power, and the original number is 
 called the squai-e root. The root of a third 
 power is the cube root ; the root of a fourth 
 power the biquadrate root, &c. 
 
 Roots of an EauATioN, are those num- 
 bers or quantities which substituted for the 
 unknown quantity render the whole equation 
 equal to zero. 
 
 Rope Pump. A machine for raising water, 
 thus described : — A is an endless rope, that 
 is, a rope of which the two ends are joined 
 together ; one part of it passes over the pul- 
 
RO 
 
 RO 
 
 ley B at the top, the lower part passes under 
 a similar pulley, situated at the bottom of 
 the well, or at least under the surface of the 
 water. C C is a frame-work to keep the 
 rope tight, and to support the cistern at top. 
 Over one end of the pulley B passes a rope 
 which extends to the large wheel E. As soon 
 as the large wheel is put in motion it turns 
 the pulley B ; this puts the rope A in motion, 
 in consequence of which the water adheres 
 to the rope A, and is brought upwards by 
 the momentum it acquires. When the rope 
 turns over at the top, the water flies off into 
 the cistern, and flows away at D. 
 
 RosAcic Acid. A peculiar acid, or as 
 some think a modification of the uric acid, 
 which is deposited as a sediment from the 
 urine of persons in certain febrile disorders. 
 
 Rose Cut. The name given to such 
 precious stones as are cut of a smooth rounded 
 surface, to distinguish them from such as are 
 cut with numerous faces or facets. 
 
 Rose Ornament. A common ornament 
 in cornices, around apertures, and in other 
 parts of Gothic architecture, particularly 
 that of the Tudor style. (See Tudor Rose 
 and Jhidor Flower.) 
 
 Rose Pink. A pigment made by dyeing 
 chalk or whiting with a decoction of Brazil 
 wood and alum. 
 
 Rose Window. Catherine Wheel 
 Window. Marigold Window. A circular 
 window of the Gothic style, but not common. 
 
 The chapter house at Salisbury Cathedral has 
 one on each side. Also a splendid window 
 of this description is at York Minster. 
 
 Rosewood. A fine dark grained wood, 
 which when fresh cut has a sweet rose-like 
 scent. It is much used for cabinet work, 
 picture frames, &c. 
 
 Rosette. Any ornament shaped like a 
 rose, whether sculptured, carved, cast, made 
 up, or painted. Thus a rosette is placed in 
 the centre between the caulicoles or smaller 
 tendrils of the Corinthian capital. It is also 
 a common design for a patera, for the cen- 
 tral ornament of a ceiling, or as one of the 
 members of a scroll ornament. Its identical 
 form varies with the taste of the artist. 
 
 Rosix. (See Resin.) 
 
 Pot, Drp. A highly destructive vegetable 
 disease, affecting the timber in the foundations 
 and other parts of buildings in particular 
 soils and situations. It affects the wood in 
 such a manner as to leave it connected by 
 nothing but small, hard, fibrous portions, but 
 all of which, when touched by the hand in 
 the more advanced stage of the disease, 
 readily moulder into a brown snuff-like dust. 
 It is attended with a peculiar earthy smell, 
 and has been supposed to arise from various 
 causes. It is now clearly proved to be oc- 
 casioned by the growth of a peculiar vegetable 
 substance or mould, called meruliw^achry- 
 mans, the sjiores or seeds of which are usually 
 present in most timber, but only germinate 
 
RU 
 
 RU 
 
 when under the joint influence of moisture 
 and warmth. To preserve timber from this 
 destructive pest, it is necessary to imbue it 
 with some subst-ance which acts as a poison 
 to the dry rot. That which has been found 
 most efficacious for this purpose is a solution 
 of corrosive sublimate ; this is called Ryan's 
 preservative, and the soaking of timber in it 
 is usually known as Kyan's process. 
 
 Rota Aristotelica, or Aristotle's 
 Wheel, denotes a problem in mechanics, 
 proposed by Aristotle, concerning the motion 
 of a coach wheel ; viz., that the nave of a 
 wheel describes by its motion, supposing it 
 to roll along a plane, a line of the same 
 length as the circumference, by its motion on 
 the ground, which was long considered para- 
 doxical ; nor was it clearly understood till 
 M. Meyran, a Frenchman, sent a satisfactory 
 solution of it to the Academy of Sciences ; 
 the principle of which is, that every point of 
 the circumference of the nave, as it ap- 
 proaches the plane, is drawn forward over a 
 space greater than itself, whereas every point 
 and part of the circumference passes over a 
 space exactly equal to itself. 
 
 Rotation. The motion of the different 
 parts of a solid body about an axis, called 
 the axis of rotation, being thus distinguished 
 from the progressive motion of a body about 
 some distant point or centre ; thus the diurnal 
 motion of the earth is one of rotation, but 
 its annual motion one of revolution. 
 
 Rotatory. That which rotates on a 
 centre. 
 
 Rotatory Steam Engines. Such as act 
 
 by a rotatory motion, instead of the alternate 
 
 or reciprocating one of the piston and beam. 
 
 Rotten Stone. A soft stone, used for 
 
 polishing. 
 
 RoTUNDo, or Rotunda. Any building 
 which is circular, both within and without, 
 whether it be a church, hall, saloon, vesti- 
 bule, or any other. ^ 
 
 Rouge. A beautiful red coloring matter, 
 supposed to be of an acid nature, which is 
 extracted from the safflower, by soaking it 
 in a solution of the carbonate of soda, and 
 afterwards neutralising the soda by lemon 
 iuice. 
 
 Rough Cast. A species of plaster to 
 cover the exterior of a building, containing 
 lime, small shells, or pebbles, fragments of 
 glass, &c. 
 
 Rubber. That part of the electrical 
 machine which rubs against the cylinder, and 
 by the friction thus occasioned produce 
 electrical excitation. 
 
 Rubber, Indian. (See Caoutchouc.) 
 RuBBLE-woRK. A rough description of 
 masonry, the stones being merely roughly 
 flattened on the side which is to lay out- 
 wards, and the whole well connected by large 
 quantities of mortar. The fiUing-in at the 
 
 back of arches, &c., is also called rubble- 
 work, it not being done so carefully as the 
 surface which is to meet the eye. 
 
 Ruby. A precious stone of a fine red 
 color. 
 
 Ruby Copper. Native oxyde of copper. 
 RuDENTURE. The figure of a rope or 
 staff, sometimes plain, sometimes carved, 
 with which a third part of the fluting of 
 columns is frequently filled up. It is by 
 some called a cabling. 
 
 RuDERATioN. Au oUl word signifying the 
 laying a pavement with small stones or 
 pebbles. 
 
 Ruins. A term particularly used for 
 magnificent buildings fallen to decay through 
 lapse of time, and of which there only re- 
 mains a confused heap of materials. 
 
 Rule, or Ruler. A simple instrument, 
 ordinarily of hard wood, thin, narrow, and 
 straight, serving to direct the drawing of 
 straight lines ; sometimes marked so as to 
 act as a measure, for feet, inches, &c. 
 Rule, Parallel. (See Parallel.) 
 Rule of Five. The same as the double 
 rule of three; so called, because it often 
 comprises five terms, two of which, and 
 afterwards the two others, are compared 
 with the fifth. 
 
 Rule of Three. A rule in arithmetic. 
 (See Projmrtion.) 
 
 Rule of Three, Compound or Double. 
 A compendious method of computing ques- 
 tions in the rules of proportion, when there 
 are more than three numbers to be compared 
 together. 
 
 Rule, Sliding. A mathematical instru- 
 ment serving to perform computations in 
 gauging, measuring, &c., without the use of 
 compasses, merely by the sliding of the parts 
 of the instrument one by another, the lines 
 and divisions of which give the answer or 
 amount by inspection. 
 RuMB. (See Rhumb.) 
 
 Runner. A single moveable pulley. (See ? 
 Pulley.) ' 
 
 Rupert's Drops. (See Prince Rupert.) 
 Rust. The peroxyde which forms upon 
 the surface of iron when left exposed to 
 damp. The oxyde formed by the weather 
 from any other metal, may, with equal pro- 
 priety, be considered as the rust of the metal. 
 Rustic. Any thing built in imitation of 
 simple nature ; thus we say a rustic bridge, 
 summer-house, &c. 
 
 Rustic Quoins and Masonry, is when 
 the quoins, or often the whole building is so 
 constructed, that the stones have their angles 
 or arrises cut off at an angle of 135° with 
 the face of the stone, so that between every 
 two stones there is a right angular opening 
 or joint ; besides this, ruiitic masonry has 
 the face of the stone chipped or marked with 
 the chisel, sometimes round the edge of 
 
SA 
 
 SA 
 
 the Btones only, at others over the whole 
 surface. 
 
 Rutherford's Day and Night Ther- 
 MOMETER, is represented in the annexed 
 cut, where A represents a spirit, and B a 
 mercurial thermometer, each provided with 
 its own scale, placed horizontally on the same 
 piece of box-wood or ivory. B contains, as 
 an index, a bit of steel wire, which is pushed 
 before the mercury, and is left in that 
 situation to mark how high the temperature 
 has been. A contains a glass index, half an 
 inch long, with a small knob at each end ; 
 it lies in the spirit, which can freely pass 
 beyond it, when expanded by heat ; when 
 contracted by cold, from the attraction be- 
 tween spirit and glass, the last film of the 
 column of spirit is enabled to overcome the 
 slight friction of the index on the inside of 
 the tube, and to carry it back towards the 
 bulb. 
 
 RuTHVEN Press. A press for the use of 
 the letter-press printer, which is totally 
 different from all others in the position and 
 nature of the levers which produce the ne- 
 cessary pressure, as will be seen by inspection 
 of the cut, and a comparison between it and 
 the others previously explained under the 
 head Printing Press. In the other instances, 
 the platten is brought down so as to exert 
 a pressure upon the form of type ; but in the 
 Ruthven press, the table and form are forced 
 upwards against the platten, by means of 
 forcing down the handle, which works the 
 lever below the press. Other peculiarities 
 will be observed ; for example, the platten 
 rolls out sideways of the press, as each 
 printed sheet of paper is removed, while the 
 tympan is turned up at the end. This press 
 occupies but little space, but having the 
 whole weight of the form to lift at each 
 pull, much of the power is wasted. As a 
 press, however, for working wood-cuts only, 
 it is strongly recommended. 
 
 Rynd. The piece of iron that goes across 
 the hole in an upper mill-stone. 
 
 This letter abounds more in 
 English than any other conso- 
 nant — not only being used in 
 radical words, but in numerous 
 of their inflections, and even 
 frequently doubled in the same 
 syllable ; hence the hissing sound so 
 repeatedly observed in ordinary con- 
 versation. It also combines with 
 other letters to a great extent ; hence, 
 when combined, it considerably modi- 
 fies the pronunciation of them. Of 
 itself, it may be considered as having 
 two sounds; one hard, as m this, sack, 
 
 possess; the other soft, like z in as, fias, 
 wise, 8fc. S, among the Romans, signified 
 7 ; among the Greeks 200. It is the com- 
 mon abbreviation for socius and societas. 
 S S signifies sanctissime. S, in geography, 
 stands for south. In music, for solo or alone. 
 On coins, it may imply senatus or salutem. 
 
 Sabadii.line. A peculiar crystalline sub- 
 stance, abstracted from the roots of the vera^ 
 trum sabadilla and the veratrum albxim. 
 
 Saccharine. Any thing relating to sugar. 
 
 Saccharine Fermentation. A kind of 
 spontaneous fermentation which takes place 
 in various bodies, by which sugar is formed 
 in them, at the expense of the gluten, and 
 sometimes at the expense of an acid. Thus 
 grain in malting from being glutinous be- 
 
SA 
 
 SA 
 
 comes saccharine. Fruit also when ripening 
 enters into the saccharine fermentation, and 
 becomes sweet. 
 
 Saccharometer. An instrument for as- 
 certaining the strength of worts, in the pre- 
 paration of malt liquors for beer, or distilling 
 spirits. It differs in no respect whatever 
 either in form or use from the hydrometer. 
 (See Hydrometer.) It is graduated from 
 at the top to 100°. When immersed in dis- 
 tilled water, at the temperature of 70°, it 
 stands at 0, but rises higher and higher in 
 proportion to the strength, or rather the 
 specific gravity of the liquid in which it is 
 immersed. 
 
 Saccholactic, or Saclactic Acid, is 
 procured by digesting gum arable in concen- 
 trated nitric acid. It is also called mucic 
 acid. 
 
 Safety Lamp. (See Davy.) 
 
 Safety Valve. A valve which fits on 
 the boiler of a steam engine, to guard against 
 accidents by the steam obtaining too high a 
 pressure. Its usual construction is as shown 
 in the cut ; where A indicates the boiler. 
 B the valve, pressing air-tight into a conical 
 hole on the top of the boiler. C is a sup- 
 port or fulcrum for the steelyard lever D, 
 which is fastened to and presses down upon 
 the valve B, with a force in accordance with 
 the weight and distance from the fulcrum at 
 which E is placed. 
 
 Safflower. a dyeing material for the 
 making of rouge, and giving a pinkish bloom 
 to lavender and other colored silks ; also the 
 material with which pink saucers are filled. 
 It comes to this country in small compressed 
 cakes, which are formed of the petals and 
 stamens of the carthamus tinctorius. 
 
 Saffron. A filamentous cake, composed 
 of the stigmata of the flowers of the crocus 
 sativus. Saffron is used as a seasoning in 
 French crockery, and to give a color to certain 
 confectionary articles, liqueurs, and var- 
 nishes, but rarely as a pigment, though as a 
 water color it might be used with advantage, 
 particularly in the artificial formation of 
 greens. 
 
 Saffron of Antimony, Sesquisulphu- 
 ret of antimony-, 
 
 Saffron of Mars. Crocus martis, or 
 the red peroxyde of iron. 
 
 Sag, or Sagging. The bending of a body 
 that would be straight while in a vertical 
 position, but when inclined or when laid 
 horizontally upon supporters at each end, it 
 
 becomes curved in the middle by its own 
 gravity, when it is said to sag. 
 
 Sago. A species of starch, extracted from 
 the pith of the sago palm. 
 
 Sail. A sheet of canvass, extended on a 
 stay, yard, &c., for the purpose of receiving 
 the pressure of the wind, and thereby com- 
 municating motion to the vessel to which it 
 is attached. 
 
 Sail, or Whip. Part of a windmill. The 
 sails of windmills are 9 yards long ; the ex- 
 treme ends move at a rate of about 30 miles 
 when at their most effective speed. 
 
 Sal Alembroth. A compound chloride 
 of mercury and ammonia. 
 
 Sal Ammoniac, Secret. Sulphate of 
 ammonia. 
 
 Sal Ammoniac. Chloride of ammonia. 
 
 Sal Catharticus Amarus. Sulphate 
 of magnesia. 
 
 Sal de Duobus. Sulphate of potass. 
 
 Sal Diuretics. Acetate of potass. 
 
 Sal Enixum. Supersulphate of potass. 
 
 Sal Gem. Native chloride of soda, or 
 rock salt. 
 
 Sal Glauberi. Sulphate of soda. 
 
 Sal Jovis. The protomuriate of tin. 
 
 Sal Martis. Green sulphate of iron. 
 
 Sal Mir a bile. Sulphate of soda. 
 
 Sal Perlatum. Phosphate of soda. 
 
 Sal Polychrest. Sulphate of potass. 
 
 Sal Prunella. Fused nitre, cast into 
 balls or cakes. 
 
 Sal Volatile. Sesquicarbonate of am- 
 monia. 
 
 Salep, or Saloup, is the name of the 
 dried tuberous roots of the orchis, imported 
 from Persia and Asia Minor, which are the 
 product of a great many species of the plant, 
 but especially of the orchis mascula. 
 
 Salicine. a febrifuge substance, which 
 may be obtained in white pearly crystals from 
 the bark of the white and other willows, and 
 some poplars. It has a very bitter taste. 
 
 Salifiable Bases, are the alkalis and 
 those earths and metallic oxydes which have 
 the power of neutralizing acidity, entirely or 
 in part, and producing salts. 
 
 Salmi AC. A word sometimes used as a 
 contraction of sal ammoniac. 
 
 Salon. A saloon, hall of audience, &c. 
 A large apartment, usually of two stories in 
 height, and decorated internally with archi- 
 tectural ornaments. 
 
 Salt, Ammoniacal, Fixed. Chloride of 
 lime. 
 
 Salt, Arsenical Neutral, of Macquer. 
 Super-arseniate of potass. 
 
 Salt, Common. Chloride of soda. 
 
 Salt, Digestive, of Silvius. Acetate of 
 potass. 
 
 Salt, Epsom. Sulphate of magnesia. 
 
 Salt, Febrifuge, of Silvius. Chloride of 
 potass. 
 
r>A 
 
 SA 
 
 Salt, Fusible, of Urine. Triple phosphate 
 of soda and ammonia. 
 
 Salt, Glauber^s. Sulphate of soda. 
 
 Salt, Green. In mines, the workmen 
 give this name to the upper stratum of native 
 salt, which is rendered impure by the ad- 
 mixture of clay, so when impregnated with 
 iron it is called from its color red salt. 
 
 Salt, Marine. Chloride of soda ; the 
 same as sea salt, or our common table salt. 
 
 Salt, Argillaceous Marine. Chloride of 
 ammonia. 
 
 Salt, Microcosmic. Triple phosphate of 
 soda and ammonia, the same as the fusible 
 salt of urine. 
 
 Salt, Nitrons Ammoniacal. Nitrate of 
 ammonia. 
 
 Salt of Amber. Succinic acid. 
 
 Salt of Benzoin. Benzoic acid. 
 
 Salt of Canal. Sulphate of magnesia. 
 
 .Salt of Chalk. Acetate of lime. 
 
 Salt of Colcothar. Sulphate of iron. 
 
 Salt of Egra. Sulphate of magnesia. 
 
 S A LT OF Lemons, Essential. Super-oxalate 
 of potass. 
 
 Salt of Riverius. Citrate of potass. 
 
 Salt of Saturn. Acetate, or sugar of 
 lead. 
 
 Salt of Seidlitz. Sulphate of mag- 
 nesia. 
 
 Salt of Seignette. Triple tartrate of 
 potass and soda. 
 
 Salt of Soda. Sub-carbonate of soda; 
 used much in the present day by the laun- 
 dress, as a detergent; and to assist with tar- 
 taric acid in making an extemporaneous effer- 
 vescing draught, or soda water. 
 
 Salt of Sorrel. Super oxalate of potass, 
 the same as the essential salt of lemons. It 
 is used to take out iron moulds and other 
 stains from clothing or furniture. 
 
 Salt of Tartar. Sub-carbonate of 
 potass. 
 
 Salt of Vitriol. Sulphate of zinc, 
 otherwise called white vitriol. 
 
 Salt of Venus. Roman Vitriol. Blue 
 Vitriol. Blue stone, or sulphate of copper. 
 
 Salt of Wisdom. The same as sal alem- 
 broth, or a compound of the chloride of 
 mercury and ammonia. 
 
 Salt of Wood Sorrel. Binoxalate of 
 potass. 
 
 Salt of Wormwood. Carbonate of potass. 
 Salt of Perlate. Phosphate of soda. 
 Saltpetre. Nitre, or nitrate of potass. 
 Salt, Rochelle. Tartrate of potass and 
 soda. 
 
 Salt, Sedative. Boracic acid. 
 Salt, Spirit of . Hydrochloric acid, com- 
 monly called muriatic acid. 
 
 Salt, Sea. The common chloride of soda 
 or table salt, procured from sea water. 
 
 Salts, Smelling. Sesquicarbonate of 
 ammonia. 
 
 Salt, Sulphureous, of Stahl. Sulphite of 
 potass. 
 
 Salt, Wonderful. Sulphate of soda. 
 Salt, Wonderful Perlate. Phosphate of 
 soda. 
 
 Salts. An important class of chemical 
 substances, composed of two or more dis- 
 similar elements, in such combination with 
 each other as chemically to unite, forming a 
 substance dissimilar to either. They are 
 divided into three orders : — First, the binary, 
 consisting of two single members. Such are 
 the bromides, chlorides, cyanides, fluorides, 
 iodides, carburets, phosphorets, sulphurets, 
 &c. Second, the bi-binary, consisting of two 
 double members, such as those formed of an 
 ordinary acid and alkali, as the borates, car- 
 bonates, sulphates, nitrates, &c. Third, the 
 ternary, consisting of two single members of 
 one genus and one of another, as the boro- 
 fluorides, the sulpho-cyanides, &c. Salts 
 also combine together in various ways for 
 triple salts, such as the sulphate of alumina 
 and potass, or common alum. Some chemists 
 will only allow such compounds to be really 
 salts which have a distinct acid principle as 
 one of their constituents, so as to exclude 
 the class first above mentioned. Others, 
 considering that salts of this class contain no 
 oxygen in their composition, have called them 
 haloide salts, being formed of the hydracids, 
 while all others are classed as oxy-salts, oi- 
 salts of the oxy-acids. 
 
 Sand. A name given to all mineral ma'icr 
 that exists in minute detached grains, and 
 more particularly denominated from some 
 prevailing substance, as siliceous sand, iron 
 sand, &c., or else from its derivation, as pit 
 sand, river sand, or sea sand. 
 
 Sandal, or Red Saunders Wood. The 
 produce of a tree which grows in Ceylon, and 
 various parts of India. It is used as a dyeing 
 material, yielding by immersion in water 
 a deep colored red pulverulent substance, 
 called santaline. 
 
 Sandarac. A gum resin, which oozes 
 spontaneously from the bark of the old trunks 
 of the common juniper, and which is used 
 in considerable quantities in the making of 
 varnish. When pounded, it is known as 
 jjounce. 
 
 Sandarac Varnish, is made thus : — 
 Mix, by means of the gentle heat of a slow 
 fire, 8 oz. of gum sandarac, 2 oz, of powdered 
 mastic, 4 oz. of clear turpentine, 4 oz. of 
 pounded glass, and a quart of spirits of 
 wine. The use of the pounded glass is to 
 prevent the other ingredients from coagu- 
 lating together, and thus preventing the 
 proper action of the alcohol. Sandarac 
 varnish is very durable. 
 
 Sand Bath. A vessel filled with sand 
 and heated by a fire beneath, the sand being 
 made hot, that it may convey a certain ap<l 
 
 AAA 
 
SA 
 
 fcA 
 
 Kteady heat to any vessel immersed in it, for 
 the purpose of drying precipitates, distilling 
 liquids, &c. 
 
 Sandiver, or Glass Gall. A saline 
 matter which rises as a scum in the pots or 
 crucibles in which glass is made. 
 
 Sandstone. In mineralogy, a stone 
 essentially composed of grains or particles of 
 sand, either united with other mineral sub- 
 stances, or adhering without any visible 
 cement. The number and variety of sand- 
 stones, and their diversity of quality, fits 
 them for the various purposes of building 
 stones, grindstones, filtering stones, &c. 
 
 Santaline. The coloring principle of 
 sandal wood. 
 
 Sapan Wood. A wood brought from 
 Japan ; the produce of a species of the ccesal- 
 pina, to which genus Brazil wood belongs. 
 It is used in dyeing red colors — usually 
 combined with red saunders or sandal wood. 
 
 Sap Green. A pigment prepared by 
 mixing the juice of the ripe berries of the 
 buckthorn with alum. The juice of the un- 
 ripe berries has the color of saffron, and is 
 used to color maps, &c. They are known 
 in common under the name of French berries. 
 
 Saponic Acids, or Adipose Acids. 
 ITiese substances, when solid, resemble fat, 
 wax, or spermaceti ; when liquid, tbey look 
 like thin oils. They are more or less volatile ; 
 colorless when pure ; lighter than water ; 
 soluble in alcohol and ether, and in the fixed 
 and volatile oils. They are inflammable, 
 and little affected by the air or acids at com- 
 mon temperatures. The greater number of 
 these acids are not found in a separate state, 
 but they appear to exist in oils and fats, in 
 union with an organic base. 
 
 Saponification. The art of converting a 
 fatty substance into soap. 
 
 Sapphire. A genus of precious stones of 
 a blue color, and the hardest of all, except 
 the ruby and diamond. They are found in 
 the East Indies, in Bohemia, Alsatia, Sibe- 
 ria, Scotland, &c. Some are found half 
 green and half red. 
 
 Sardonyx. A variety of cornelian, com- 
 posed of layers of white and red alternately. 
 
 Sash. A checkered frame, for holding the 
 squares of glass in a window. 
 
 Sash Frame. The frame in which window 
 sashes are hung. 
 
 Satellite. In astronomy, certain secon- 
 dary planets moving round their primary 
 planets, as the moon does round the eatth. 
 The number of satellites, at present known as 
 belonging to our system, is eighteen ; viz., 
 the moon, the satellite of the earth ; four be- 
 longing to Jupiter ; seven to Saturn ; and six 
 to Uranus ; but of these the moon only is 
 visible to the naked eye. ('See Moon.) 
 
 Satin. A kind of silken stuff, very smooth, 
 and shining. The woof is coarse, and hidden 
 
 underneath the warp, which is fine and pro- 
 minent, and on this depends its gloss and 
 beauty. 
 
 Satin Spar. Carbonate of lime, in deli- 
 cate, almost compact, white fibres. 
 
 Satin Wood. A fine, hard, lemon-colored 
 wood, having a fragrant odour. It grows 
 chiefly in India, and is va'ued there for its 
 medicinal virtues. Its chief use in the arts 
 is for the finer specimens of cabinet and inlaid 
 work, the fabrication of fans, rules, and 
 various sm<iU articles of turnery. * 
 
 Saturation. A fluid which holds in so- 
 lution as much of any substance as it can 
 dissolve is said to be saturated with it ; but 
 saturation with one substance does not always 
 deprive the fluid of its power of acting on 
 and dissolving some other bodies, and in 
 many cases it increases this power. A solid 
 is also sometimes said to be saturated ; thus 
 a garment may be saturated with rain, the 
 sand of the sea shore is saturated with water, 
 and so on. The word saturation is also em- 
 ployed in another sense The union of two 
 principles produces a body, the properties of 
 which differ from those of its component 
 parts ; when the principles are in such pro- 
 portion that neither predominates, they are 
 said to be saturated with each other ; but if 
 otherwise, the most predominant principle is 
 said to be sub-saturated, and the other super- 
 saturated. 
 
 Saturn. One of the primary planets, 
 being the sixth, in order of distance from the 
 sun, of the old planets, but the tenth, inclu- 
 ding the four new ones, and the outermost of 
 all, except Uranus. This planet is, perhaps, 
 one of the most engaging objects that as- 
 tronomy presents to our view, being sur- 
 rounded by a double ring and seven satellites, 
 all visible by a moderate telescope. Saturn 
 lias also at times certain obscure belts across 
 his disc, like those of Jupiter. His form is 
 like that of the other planets, an oblate 
 spheroid. His sidereal revolution is per- 
 formed in 29-456 years. His distance from 
 the sun is above 890 millions of miles. The 
 rotation on his axis, or the length of his day, 
 is 10 h., 16', 19", and his mean diameter 
 76078 miles, consequently he is nearly 1000 
 times as large as our earth. 
 
 Saunders Wood. (See Sandal Wood.) 
 
 Sausseur's Cyanometer. (See Cyano- 
 meter.) 
 
 Sausseur's Electrometer. This instru- 
 ment is pecvdiarly adapted to ascertain the 
 electrical stale of the atmosphere. It con- 
 sists of a glass case or bottle, with a metal 
 bottom, four pieces of tin-foil being pasted 
 on the sides of the glass, in connection with 
 the bottom ; withinside the glass are two 
 very fine silver wires, swinging freely in a 
 loop above, and ending below in two small 
 pith balls. The upper part of the instrument 
 
SA 
 
 SC 
 
 is a brass cap, terminated by a ball and a 
 rod of three or four feet, made in joints, for 
 the sake of greater convenience, and pointed. 
 This instrument, when used, is to be placed in 
 some exposed situation. When an approach- 
 ing storm or other cause indicates the elec- 
 tric fluid in the atmosphere to be disturbed, 
 the silver threads, by their divergence, will 
 show the degree and character of the fluid in 
 contact with the instrument. When it is 
 used in rainy weather, the upper part of the 
 glass is covered with a hood, like an umbrella, 
 to keep the glass dry, and consequently the 
 electrometer insulated. Such a hood is re- 
 presented upon it in the figure given. 
 
 Sausseur's Hygrometer, consists of 
 single human hair, suspended from a wire. 
 The changes of moisture in the atmosphere 
 twists or untwists the wire, when a fine index 
 suspended at the end of it shows, by moving 
 round a small dial plate, the degree of mois- 
 ture or drought. 
 
 Savory's Steam Engine. This, which 
 may truly be considered as the first that 
 was applied to useful purposes, was called 
 by its inventor "The Miner's Friend ;" it 
 being emplojed to drain mines, which it 
 did with considerable effect. Savory con- 
 structed engines with a single, and with two 
 steam receivers — the first appears the most 
 simple. Its mode of action and working 
 parts are as follows : — 
 
 A is the fire. B the boiler, the steam 
 from which is admitted into the receiver E, 
 through the pipe D, driving the air at first 
 contained in it into F, and thence, by means 
 of a valve, into the atmosphere. When E 
 and F are full of steam, the cock M is turned, 
 and so is the handle C, to shut ofi the steam, 
 by which means water from I flows upon E, 
 condensing the steam within it, and forming 
 a vacuum in the vessel. In consequence of 
 this, water rushes up from the well H, 
 through the pipe G, at a valve at the top, 
 until E and F are filled : then shut off the 
 cock M, and open that at C. . The steam 
 
 rushes into the receiver E, and will press 
 upon the surface of the water, driving it up 
 the pipe I, whence it runs away by the 
 shoot O. The funnel and cock N are to 
 supply the boiler w'th water, when required. 
 
 The second and more powerful engine is of 
 a very similar nature, but has most of these 
 parts double ; thus there are two boilers 
 and fire-places, and two receivers. Thus 
 while the water is rising in the one receiver 
 it is sinking in the other, so that a stream of 
 water is projected from each alternately, and 
 a constant supply is obtained, as well as a 
 great economy of time and fuel. 
 
sc 
 
 sc 
 
 Water being admitted from D to either of 
 the receivers marked P P, by its tube O, the 
 air is driven out by the clack valve R. The 
 steam is not turned off entirely at all, but 
 turned so that it enters the other receiver P, 
 and the cold water from Y falling upon the 
 first P, raises the water through T, and the 
 valve above it. Reversing the action of the 
 steam and cold water- cocks a second time, 
 admits the steam into the first P again, while 
 that in the second P is condensed, the water 
 being raised by each admission of steam. 
 Now it is evident that the water in the boiler 
 would, without other contrivance, be soon 
 exhausted, but this is prevented by the 
 double boiler, &,c. Shutting the cock E, 
 cuts off the communication between the pipe 
 S and the small boiler D ; and as D is sur- 
 rounded by the fire equally with the larger 
 boiler, and which is seen behind the receivers, 
 the water of D becomes very soon hot, and 
 acquires a 'great power of steam, greater than 
 that of the larger boiler, whose steam is 
 continually drawn off. When this is the 
 case, it drives the water of D through the 
 pipe N, (which reaches to nearly the bottom 
 of D,) into the great boiler. The size of the 
 small boiler D is so regulated that the water 
 thus thrown out will sufficiently replenish 
 the large boiler. The cock E being again 
 turned on, water descends from S into D, 
 ready for a future occasion. G is a gauge 
 cock to ascertain the amount of steam or 
 water in the boiler. 
 
 Saxon Blue, or LiauiD Blve, is a so- 
 lution of the sulphate of indigo. 
 
 Saxton's Magneto-Electrical Ma- 
 chine. (See Magneto.) 
 
 Scaffold. An assemblage of planks or 
 boards, sustained by tressels or pieces of 
 wood, fixed in the wall, upon which masons, 
 bricklayers, &c., stand, while carrying up a 
 wall, or for other purposes of support, at a 
 distance above the ground. 
 
 Scagliola. An imitation of the most 
 beautiful marbles, such as Sienna, jasper, 
 porphyry, &c. It is hard, and when finished 
 bears a beautiful polish. 
 
 Scale. A line divided into a certain num- 
 ber of equal parts, each of which is sub- 
 divided into others, in order to express the 
 parts of an object of a different size, either 
 in a drawing or in a model, but in the same 
 proportion as the original. (See Diagonal 
 Scale, Protractor, Sfc.) 
 
 Scalene Triangle. (See Triangle.) 
 
 Scalloped Moulding. A moulding 
 common in Anglo-Norman edifices. 
 
 Scantling. The transverse dimensions of 
 a piece of timber in width and thickness. 
 Scantling is also the name given to all timber 
 used for the quartering of partitions, as posts, 
 tie beams, rafters, &c., if less than 5 inches 
 in width and depth. Scantling in masonry 
 is the size of the stones in length, as well as 
 breadth and depth. 
 
 Scape. A name sometimes given to the 
 shaft of a column. It is also used for the 
 little hollow above and below which connect* 
 a shaft to its base and capital. 
 
 ScAPEMENT. (See Escapement.) 
 
 Scarfing. A term used to denote the 
 junction of two pieces of timber, by being 
 bolted or nailed transversely together, so that 
 the two appear but as one. The joint is 
 denominated a scarf, and the timbers are said 
 to be scarfed. 
 
 Scenography. The method of repre- 
 senting solids in perspective. The ichnogra- 
 phy is the ground plan j the elevation, a re- 
 presentation of the vertical places upon a 
 vertical plane given in position, and when the 
 whole is represented at one view, the repre- 
 sentation is called the scenography. 
 
 Scheele's Green. The arsenite of cop- 
 per ; a valuable pigment both for oil and 
 water colors. 
 
 Scheme. The representation of anything 
 by lines only. 
 
 Scheme Arch, or Skene Arch. A cir- 
 cular arch, whose dimensions are not greater 
 than a semi-circle. 
 
 Schmidt's Ayi Pyrometer. (See Air 
 Pyrometer.) 
 
 Scholium. A note, annotation, or remark, 
 occasionally made on some passage, propo- 
 sition, or the hke. The term is much used 
 in geometry and other parts of the mathe- 
 matics ; where, after demonstrating a propo- 
 sition, it is frequent to point out how it might 
 be done some other way ; or to give some 
 advice or precaution in order to prevent mis- 
 takes, or add some particular use or appli- 
 cation thereof. 
 
 Schools of Art. Painters understand by 
 this term certain classes of artists, whose 
 works are all referable to one common ori- 
 gin, or painted in the same style. The phrase, 
 however, at times takes a more limited mean- 
 ing, and refers to the followers of one par- 
 ticular meaning, as the school of Raphael, 
 the school of Rubens, &c. In the first and 
 most comprehensive sense, however, the 
 schools of painting may be divided into nine ; 
 namely, the Florentine, the Roman, the Ve- 
 netian, the Lombard, the Flemish, the Dutch, 
 the German, the French, and the English. 
 All except the three latter are now extinct. 
 
 Schweigger's Galvanometer, or Gal- 
 vanic Multiplier. (See Galvanometer.) 
 Schweinfurth Green. Arsenite of cop- 
 per, united with the acetate of copper, made 
 
sc 
 
 sc 
 
 by adding 8 parts of arsenious acid to 9 or 
 10 of verdigris, previously dissolved in water. 
 
 Sciagraphy, or Sciograpay. The 
 draught of a building, &c., cut in its length 
 and breadth to display the interior ; in other 
 words, the profile or section of it. 
 
 Scribing. A term applied to fitting the 
 edge of a board to an irregular surface. 
 
 Science, denotes any doctrine deduced 
 from facts, or self-evident principles. Tims 
 we have natural sciences, mathematical scien- 
 ces, and speculative sciences. The first de- 
 pend upon our senses, the second upon our 
 reason, and the third upon our experience. 
 The first class opens a wide field for contem- 
 plation, comprising as it does the whole of the 
 sciences of natural history, experimental phi- 
 losophy, and astronomy. The mathematical 
 sciences, among which are the properties of 
 number, time, and space, absolute and rela 
 tive, require the deepest exercise of the 
 reasoning powers ; and the last, or the specu- 
 lative sciences, appeal to our wants, feelings, 
 and mental capacities ; such are ethics, logic, 
 language, political economy, agriculture, &c. 
 Notwithstanding the name given to these 
 sciences, yet they, as well as all others, must 
 rest upon facts only ; it is to them alone to 
 which we must look for conclusions, and upon 
 them only can we found just or rational 
 hypotheses. 
 
 Scientific. Relating to or conducted by 
 the rules of science. 
 
 SciLLiTON. A white, transparent, acrid 
 substance, extracted from squills by Vogel. 
 
 ScioPTic, or SciopTRic Ball. A sphere 
 or globe of wood, with a circular hole or per- 
 foration, filled with a lens, and mounted in a 
 frame, so as to turn about in any direction, 
 being used in making experiments on light 
 in a darkened chamber. 
 
 Scoop Wheel. A wheel, made like an 
 over-shot water wheel, with buckets around 
 the circumference. This being turned round 
 by a steam engine or other power, scoops up 
 the water in which the lower part of it dips, 
 and thus raises it to a height equal to that of 
 the diameter of the wheel ; when the buckets 
 turning over, deposit the water in a trough 
 ready to receive it. The scoop wheel is 
 sometimes used for irrigating lands from a 
 neighbouring stream, or draining such as are 
 overflowed, but seldom for any other purpose. 
 
 Scoria. Ashes, dross, or slag, from a 
 smelting furnace. 
 
 Scotia. Trochilus ; synonymous with 
 cavetto ; a hollow moulding. 
 
 Scotching. The operation of packing 
 hemp before it goes to the market ; also the 
 operation of preventing a wheel, cask, roller, 
 &c., from running down a declivity, by 
 placing any thing under the lower side of it ; 
 or it may be scotched on both sides to keep 
 it steady. 
 
 Scouring. Cleansing ; particularly ap- 
 plied to renovating articles of dress. 
 
 Scouring Barrel. An octagonal or 
 other shaped barrel, in which cast nails, 
 scrap iron, &c. is cleaned from rust by 
 friction as it revolves. 
 
 Scrap Iron. Various pieces of old iron 
 to be re-manufactured. 
 
 Screen. A light ornamental partition 
 between one part of a church and another; 
 or, generally, any slight division or blind. 
 
 Screw. One of the six mechanical powers, 
 chiefly used in pressing or squeezing things 
 together, but sometimes also in raising 
 weights. The screw is a s{)iral thread oi 
 groove cut round a cylinder, and evei-y where 
 making the same angle with the length of it ; 
 so that, if the surface of the cylinder with 
 this spiral thread upon it were unfolded and 
 stretched into a plane, the spiral thread 
 would form a section of an inclined plane, 
 whose length would be to its height, as 
 the circumferance of the cylinder is to the 
 distance between two threads of the screw ; 
 as is evident from considering that in making 
 one turn, the spiral rises along the cylinder 
 the distance between the two threads. When 
 the spiral thread is upon the outside of the 
 cylinder, the screw is said to be a male one ; 
 but if the thread be cut along the inner sur- 
 face of a hollow cylinder, or a round perfo- 
 ration, it is said to he female. This latter is 
 sometimes called a box or nut. 
 
 Screw, Archimedes. (See Archimedes.) 
 Screw, Hunter'' s. (See Hunter.) 
 Screw, Micrometer. (See Micrometer.) 
 Screw, Original. Any screw formed by 
 a tool at once, with the intervention of dies 
 or taps. Original screws are made in a lathe 
 by the use of the screw tool. 
 
 Screw, Perpetual. (See Perpetual.) 
 Scroll. A consolidated or twisted orna- 
 ment. Scroll-work adds much beauty to 
 innumerable objects in art. The frieze of 
 the more elaborate orders of architecture is 
 often ornamented by a running scroll ; and 
 numerous articles of domestic ornament are 
 thus enriched, particularly the frames of 
 pictures and looking glasses. Good or bad 
 taste and drawing is, perhaps, shown more, 
 in scrolls than in any other work. They 
 should always have a regular flowing outline, 
 in whatever style, or for whatever purpose 
 
kSE 
 
 SE 
 
 they may be applied. Scrolls are applicable 
 to almost every description of running orna- 
 ment. The Greek buildings were often en- 
 riched with scrolls of extreme simplicity and 
 elegance, and of the style of which the 
 following may convey a faint idea : — 
 
 The scroll adopted by the Romans differed 
 but little, in character, from the last, except 
 in being commonly more leafy, gaining in 
 massiveness, but losing in simplicity. In 
 Gothic architecture, scroll-work is never 
 used, the nearest approach to it being a 
 bunch or chaplet of intertwining leaves. 
 The scrolls of the age of Elizabeth were 
 massive and simple, but stiff and inelegant. 
 Witness the following example, and also 
 a different kind of scroll at the word Car- 
 touch : — 
 
 The scroll-work of the French, particularly 
 of the age of Louis XIV., is free, flowing, 
 made viTith bold irregularity, and infinitely 
 varied, as may be seen in the corners, crests, 
 and other parts of looking glass frames, 
 which will be recognised as of the following 
 character : — 
 
 Arabesque and Moorish scroll-work 0> 
 combines the characters of the Greek ad 
 the French, and is, besides, intermingled 
 with the figures of animals and grotesques. 
 
 Scruple. In astronomy, the same as 
 digit. 
 
 Sculpture. The art of imitating visible 
 forms, by chiselling and working solid sub- 
 stances. The word properly includes images 
 of clay, wax, wood, metal, and stone, but is 
 generally restricted to the last material ; the 
 terms modelling, casting, and carving being 
 applied to the others. 
 
 Scutcheon. Escutcheon. A shield for 
 armorial bearings ; also an ornament put 
 round a key hole, door handle, knob of a 
 a or, or other similar object. 
 
 Seal Engraver's Lathe. This very 
 simple instrument is exhibited below. It con- 
 sists of a table, upon which is fixed the man- 
 dril, or as it is here called, the mill. This is 
 a brass upright, with a spindle through it, 
 and a pulley upon the middle of the spindle ; 
 there being a cavity cut in the mill of suf- 
 ficient size for it to fit and revolve, which it 
 does in consequence of a string or cat-gut 
 band which passes over the pulley, and thence 
 to a fly wheel and foot treadle beneath the 
 table. The tools are small pieces of steel, 
 of various forms. A tool being inserted into 
 a square socket at the end of the spindle of 
 the mill or mandril, the stone to be engraved 
 is held against the point of the tool, and at 
 the same time a minute quantity of a thin 
 paste, made of the oil of brick and diamond 
 
SE 
 
 SE 
 
 dust, or of emery powder, is placed upon the 
 point. The stone is by these simple means 
 gradually worn away, until it becomes a per- 
 fect seal, with initials, motto, or device, as 
 required by the artist. In the cut, A is the 
 treadle. B the hook, to connect it with the 
 crank of the fly-wheel, C. D the cord. E 
 the mill ; and F the nose or spindle of it, 
 where the tools are inserted. 
 
 S E A I- , Hermetic. ( See Hermetical Sealing. ) 
 
 Seamng Wax. A composition wherewith 
 to seal or fasten letters, and other small 
 packets. The principal ingredient in all 
 sealing wax is shell lac. The following re- 
 ceipts are recommended. Red: — 4 ounces of 
 shell lac, 1 oz. of Venice turpentine, and 
 3 drachms of Vermillion. Melt the lac first, 
 then add gradually the turpentine, and after- 
 wards the Vermillion ; stir the whole well 
 together, pour out on a marble slab, and 
 while yet ductile roll out into sticks, by 
 means of a smooth wooden board. Black : — 
 Use ivory black, instead of vermillion. For 
 gold: — Stir in gold-colored mica spangles, 
 or bronze powder. For purple : — Use rose 
 pink. For yellow : — Use Naples yellow, or 
 yellow orpiment. 
 
 Sea Salt. Chloride of sodium. 
 
 Sea Salt, Regenerated. Chloride of 
 potass. 
 
 Sbasons. Certain portions of the year 
 regulated by the revolution of the earth in 
 its orbit, or as it iS more convenient to refer 
 to the apparent path of the sun through the 
 twelve signs of the zodiac, we usually say, 
 that while the sun passes through the three 
 first signs, or from the first point of Aries to 
 the first point of Cancer, which corresponds 
 with the time from the 21st of March to 
 Midsummer, it is spring ; while he passes 
 through Cancer, Leo, and Scorpio, or from 
 Midsummer to Michaelmas, it is summer ; 
 thence to Christmas, it is autumn ; and to 
 complete the year to March again, it is winter, 
 or the fourth season. The reason of the sea- 
 sons is the obliquity of the ecliptic ; in con- 
 sequence the sun shines more vertically over 
 the northern hemisphere at one season of the 
 year than another; therefore that portion 
 over which he shines most direct is hotter 
 than others which receive his rays more 
 obliquely, making the difference between 
 summer and winter. 
 
 Sea Wax, or Maltha. A white, solid, 
 tallowy-looking, fusible substance, soluble in 
 alcohol ; found on the Baikal Lake, in Siberia. 
 
 Sebacic Acid. An acid extracted from 
 hog's lard. 
 
 Sebate. a salt of the sebacic acid and a 
 base, as the sebate of lime. 
 
 Sebic Acid. The same as sebacic acid. 
 
 Secant. A line that cuts another or di- 
 vides it into two equal parts. In trigonometry, 
 the secant is a line drawn from the centre of 
 
 a circle to some point in the tangent, which 
 consequently cuts the circle. 
 
 Second. The sixtieth part of a minute, 
 both as it relates to the measure of angles or 
 time. 
 
 Secondary Circles. In astronomy, are 
 any circles that intersect one of the great 
 circles of the sphere at right angles. All the 
 meridians and parallels are therefore secon- 
 dary circles. 
 
 Secondary Coil and Current, Elec- 
 tro-magnetic. When the electric fluid passes 
 along a wire, the current is called a primary 
 current, and the wire a primary wire ; if 
 twisted around a bobbin it would be a pri- 
 mary coil. The influence of the electric 
 fluid is not entirely confined to the wire which 
 serves for its immediate conveyance, but also 
 influences and excites a current in a second 
 wire, which may be twisted round the bobbin 
 which contains the first. This is called the 
 secondary current, and this outer coil of wire 
 the secondary coil. (See Callan.) 
 
 Secondary Planets. (See Satelliteg.) 
 
 Section. A representation of any thing 
 supposed to be cut in two parts to show the 
 internal structure of it. A section may 
 be longitudinal, transverse, horizontal, or 
 oblique. 
 
 Sections, Conic. (See Conic.) 
 
 Sector. An instrument for measuring or 
 laying off" angles, and for dividing straight 
 lines and circles into equal parts. 
 
 Sector OF a Circle. The space compre- 
 hended between two radii of a circle and the 
 circumference. It may be larger or less 
 than a semi-circle. 
 
 Secular Eouations. In astronomy, 
 are corrections required to compensate such 
 inequalities in the motions of the heavenly 
 bodies as are ound to take place in the 
 course of a century. Thus there are secular 
 inenniilities in the motion of the mot- 
 
SE 
 
 SE 
 
 which require for their correction so many 
 secular equations. 
 
 Sedative Salt. Boracic acid. 
 
 Seebeck's Thermo-Electric Circuit. 
 An instrument which shows the electric 
 effect produced by heating dissimilar metals. 
 It may be made of many forms. That of a 
 parallelogram is the most usual. The two 
 arms A and B are of one metal, for example, 
 antimony ; the other two arms C and D of a 
 different metal, as bismuth — these are soldered 
 at the corners. A stand supports the whole, 
 and bears besides a small magnet, the point 
 of suspension of which is about the centre 
 of the parallelogram. When the heat of a 
 flame is thrown upon either of the corners 
 where the two metals meet, an electrical 
 current is established, and the magnet is 
 diverted from its polar direction, the north 
 pole turning towards the east or west, ac- 
 cording to the position of the two metals, 
 that is, according to the course of the current. 
 
 
 Seed Lac. (See Lac.) 
 
 Seggar, or Saggar, is the cylindric esse 
 of fire-clay in which fiue stone- ware is in- 
 closed while being baked in the kiln. 
 
 Segment. Any part of a whole subst mre. 
 
 Segment of a Circle. The area com- 
 prehended between an arc and a chord of a 
 circle ; that is, a portion of the surf.ice a'" a 
 circle cut off by a straight line, supposi i.,' it 
 not to be a semi-circle. 
 
 Segment of a Sphkre, is any part of it 
 cut off by a plane, the section of which, 
 with the sphere, is always a circle. 
 
 Sel de Skignette. The triple tartrate 
 of potass and soda, or Rochelle salt. 
 
 Skleniates. Salts compounded cf the 
 selcnic acid. 
 
 Selenic Acid. A composition of 1 part 
 of selenium and 3 parts of oxygen. 
 
 Skleniocyanuhet. a compounl of 
 selenium and cyanogen. 
 
 Selenious Acid. A composition of 
 1 part of selenium and 2 parts of oxygen. 
 
 Selenious Oxyde, or Oxvde of Sele- 
 nium. A combination of 1 part of selenium 
 and 1 part of oxygen. 
 
 Selenite. In mineralogy, is the name of 
 sparry gypsum ; in chemistry, it is any salt 
 of the selenious acid. 
 
 Selenium. A metalloid discovered by 
 Berzelius in 1817. It occurs sparingly in 
 combination with several metals, as lead, co- 
 balt, copper, quicksilver, silver, bismuth, 
 iron, gold, &c. It is of a blueish grey, or a 
 reddish brown color, with a glistening me- 
 tallic surface, brittle, not very hard, and with 
 little tendency to crystallize. It softens at a 
 temperature of 176° of Fahrenheit; is of a 
 pasty consistence at 212"^ ; becomes liquid at 
 a somewhat higher heat, forming in close ves- 
 sels dark yellow vapours, which condense 
 into black drops ; but in the air the fumes 
 have a cinnamon red color. This singular 
 substance, apparently intermediate between 
 the metals and sulphur, has not hitherto been 
 applied to any use in the arts. 
 
 Seleniuret. a compound of selenium. 
 
 Seleniuretted Hydrogen Gas. Hy- 
 drogen contaminated with selenium. 
 
 Self-RegisteringThermometer. (See 
 Sia^ and Rutherford.) 
 
 Sell. (See Sill.) 
 
 Semi. In words of science, signifies a 
 half, as semi-transparent means partly trans- 
 parent. 
 
 Semi-Circle. The half of a circle con- 
 tamed by the diameter and the circumference. 
 
 Semi-Diamkter. The same as radius. 
 
 Senegin. a i)eculiar principle discovered 
 in the senega root. 
 
 Sepia. A pigment of a fine brown color, 
 prepared from a black juice secreted by cer- ' 
 tain glands of the cuttle fish, which the ani- ' 
 mal ejects to daiken the water when pursued. 
 One part of it is capable of making 1000 
 parts of water nearly opaque. It consists of 
 carbon in a finely-divided state, together with 
 albumen, gelatine, and phosphate of lime. 
 
 Seralbumen. Albumen obtained from 
 the serum of the blood ; so called to distin- 
 guish it from ovalbumen, or that obtained 
 from the white of eggs. 
 
 Series. In algebra and arithmetic, is a 
 continued rank or progression of quantities, 
 connected together by the signs + or — ; 
 usually proceeding according to a certain 
 determinate law. Series receive different de- 
 nominations, according to certain circum- 
 stances relative to their formation, the law 
 which they observe, &c. A converging series 
 is one in which the terms decrease, or become 
 successive by less and less, as 1 + -g^ + -^ + -g^, 
 &c. A diverging series is the contrary to 
 this, or where the terms increase continually, 
 as 1 — 2 + 4 — 8 + 16, &c. A iieutral series 
 has all the terms equal, as x -r x~x+ x, &c. 
 I lid e terminate series is one whose terms 
 
SH 
 
 SH 
 
 proceed by the powers of an indeterminate 
 quantity, asx + ^x^ + -^x^, &,c., and this is 
 either ascending or descending. 
 
 Serpentine. A kind of marble of a fine 
 green color, found abundantly in two or 
 three parts of Scotland, and in the Isle of 
 Holyhead. 
 
 SEsaui. A word signifying one and a 
 half. It is now much used in chemistry, to 
 designate those compound substances in 
 which there is one proportion and a half of 
 oxygen, chlorine, hydrogen, &c. to one of 
 the base ; thus the sesquicarbonate of am- 
 monia contains 1^ proportionals of carbon 
 to each one of ammonia. The sesquioxyde 
 of lead is composed of 1^ parts of oxygen to 
 each one of lead. 
 
 Sesquialterate Ratio, is an old mathe- 
 matical term for a ratio between two numbers 
 or lines, when the greater is equal to one 
 and a half times the less. 
 
 SEsauiDUPLiCATE Ratio, is when the 
 greater term is twice and a half times the 
 less. 
 
 Setting. In astronomy, is the disappear- 
 ance of any of the heavenly bodies below the 
 horizon. 
 
 Settofp. (See Offset.) 
 
 Skwer. a subterranean channel or canal, 
 made in cities, towns, and other places, to 
 carry off the water and other matters. 
 
 Sexagenary. Something relating to the 
 number 60. 
 
 Sexagesimal. The division of a line 
 first into 60 ; then each of the parts again 
 into 60 ; and each of these again into 60 ; 
 and so on, as long as division can be made. 
 
 Sexagesimals, or Sexagesimal Frac- 
 tions, are fractions whose denominators 
 proceed by the powers of 60 instead of the 
 powers of 10, as in common decimal fractions ; 
 that is, in sexagemimals, a prime or first 
 minute is ^ ; a second ^ x ^, or ^^ : 
 but here, as in decimal fractions, the deno- 
 minators being always the powers of the 
 same number, they are not put down, their 
 real value being indicated by the place they 
 occupy ; thus we say 26°, 9', 31", 16"', or 
 26 degrees, 9 minutes, 31 seconds, and 
 16 thirds. From the frequent use of these 
 fractions in jistronomy, they are often called 
 astronomical fractions. 
 
 Sexagon. (See Hexagon.) 
 
 Sextant. The sixth part of a circle, or an 
 arc of 60° ; also the name of an instrument 
 resembling a quadrant, differing from it only 
 in its arc consisting of 60° instead of 90°. 
 
 Sextile Aspect. When two heavenly 
 bodies are at the distance from each other 
 of 60°. 
 
 Sextillion. The sixth power of a million. 
 
 Sextuple. Six-fold. 
 
 Shade. Shadow. A partial obscurity 
 seen in such objects, or such parts of an 
 
 object as do not receive the direct rays which, 
 emanate from a luminous body. Though 
 the above is a general definition, yet the 
 terms shade and shadow are by no means 
 synonymous. Shade is a general and extended 
 mass of obscurity ; but a shadow is defined, 
 and forms a strong contrast with the illumi- 
 nated portion of the object adjoining to it. 
 Thus suppose the sun to shine through the 
 window of a Gothic cathedral, its beams 
 striking on the pillars, groins, pendants, &c., 
 will occasion strong shadows behind them, 
 while the rest of the cathedral will be in 
 shade only. 
 
 Shadowing. In drawing, the art of re- 
 presenting the various degrees of light and 
 shade, by means of a dark fluid or color. 
 
 Shadows, the Doctrine of. In perspective, 
 is the theory and practice of representing 
 shadows from a given point at a finite dis- 
 tance, such as a candle ; or as projected 
 from the sun, where the distance, though 
 not infinite, is for the sake of simplicity con- 
 sidered as such, in order that the rays may 
 be all parallel. The following cut will show 
 the different effect of the shadows of the 
 same object, one of which is illuminated by 
 the sun, the other by a candle :— 
 
 Shaft. In mill-work, is a large axle, in 
 contra-distinction to a spindle or small axle ; 
 thus we say the shaft of a fly-wheel, the 
 spindle of a piston. Shafts are said to be 
 lying when in a horizontal position, and 
 vertical when they are upright. 
 
 Shaft. In engineering, is a vertical sink- 
 ing or well, excavated and dry, for the pur- 
 pose of working or ventilating mines, also 
 tunnels, and for ascertaining the nature of 
 the ground before commencing any engineer- 
 ing operations. The principal shaft of a 
 mine is usually called the engine shaft. 
 
 Shaft. That part of a column between 
 the base and the capital. 
 
 Shaft of a Chimney. That part of it 
 above the roof. 
 
 Shagreen. A peculiar substance some- 
 what similar to parchment ; used occasionally 
 to cover spectacle and other small cases. It 
 is prepared from the skins of horses, camels, 
 &c. 
 
 48. 
 
SH 
 
 Shake, or Shaken. Terms used of timber 
 that is rent by drying too suddenly, in 
 which the fissure occasioned by too great a 
 heat is called a shake. 
 
 Shakey Timber. That which is full of 
 shakes or cracks. 
 
 Shammey, or rather Chamois. A very 
 pliable kind of leather, originally prepared 
 from the chamois goat ; now manufactured 
 from the skins of sheep or lambs, and known 
 by the name of wash-leather. 
 
 Shanks, or Legs. The spaces between 
 the glyphs of a Doric frieze. 
 
 Shape. In all the arts, form, external 
 appearance. The word shapely is used when 
 speaking of any object, the proportions of 
 which are elegant and harmonious. 
 
 Shear Steel. So called, because fitted 
 for making clothiers' shears, scythes, &c. ; 
 is prepared by laying several bars of common 
 steel together, and heating them in a furnace 
 until they acquire the welding temperature. 
 The bars are then beaten together with forge 
 hammers, after which they are drawn anew 
 into bars for sale. 
 
 Sheave. A single pulley, used either as 
 an alterative of motion, as in a block or 
 crane, or to prevent the friction of a rope 
 running along it; such are placed on those rail- 
 roads which are worked by stationary engines, 
 or on the reciprocating principle, to sustain 
 the weight of the rope which draws the 
 carriages, and prevent its friction on the 
 ground, or its deviation from the centre of 
 the road. 
 
 Shelf. Among miners, the strata which 
 they find lying in a very even manner. 
 
 Shell-Lac. (See Lac.) 
 
 Shides. The same as shingles, (which 
 see.) 
 
 Shield. Synonymous with scutcheon, but 
 more applied to a surface representing the 
 ancient defensive armour which goes by that 
 name. 
 
 Shift. The name employed in reference 
 to the gangs of men employed in excavating 
 and other works ; for instance, when two 
 different sets of men are employed alternately, 
 they are described as working double shifts. 
 The word double here appears superfluous, 
 shift of itself implying a change ; thus shift- 
 ing the wheels of a carriage, is the changing 
 them for each other, or a man may shift a 
 tool from one hand to the other, or a board 
 or bar end for end. 
 
 Shillibeer's Galvanic Battery and 
 Pole Director. The instruments are thus 
 described and figured by the inventor : — 
 The apparatus consists of a well-made copper 
 trough, about 3 inches deep and 2\ wide, 
 divided into compartments, according to the 
 number of zinc plates employed ; (see cut, 
 which represents a section of the trough that 
 receives the plates.) These plates are sol- 
 
 SH 
 
 dered firmly to a copper bar, and by the aid 
 of a screw are fastened to a piece of hard 
 wood, answering for a cover to the trough. 
 In a groove cut out of the cover, on each side 
 the screw, is fitted a copper slide, and these 
 slides are joined by an elbow to a piece of 
 ivory forming a handle, which passing imme- 
 diately above the screw, each wing of the 
 slide may be brought readily into contact with 
 the copper or zinc. Tlie use of this move- 
 ment or pole director I will endeavour to 
 make apparent. In the figure, let A A re- 
 present a section of the wood cover, with a 
 groove for the slide to stand in. B the screw, 
 in connection with the zinc. C C the oppo- 
 site side of the copper trough. D E the two 
 wings of the slide. Now let the wing D D 
 be in contact with C, and E with B ; it is 
 evident that the stream of electricity is going 
 out from the wire in connection with the wing 
 D, and is returning by the wire appended to 
 E into the zinc plates, by way of B. Shift 
 the slide so that E be in connection with C, 
 and D with B ; the stream will be reversed, 
 making its exit by E, and returning by D 
 through B. The zinc plates should be co- 
 vered tightly with a membrane, so as to pre- 
 vent any deposition of copper upon them ; 
 a solution of the sulphate of copper being 
 that with which the copper cells are filled, 
 while salt and water fills the membrane. 
 
 
 Shingles. Pieces of wood, cut about 
 12 inches long and 4 wide, one edge of them 
 being thin, the other thick ; used instead of 
 tiles for flooring. The external covering of 
 spires is often of this description. The boards 
 before cut into lengths are called weather 
 boards. 
 
 Shoad. a term given by miners to stones 
 containing ore, mixed with rubbish, in a loose 
 soil, and sometimes near the surface. When 
 deep, the miners consider it as indicating 
 that some vein is at no great distance. 
 
 Shoar. a prop or support, placed ob- 
 liquely against any thing to hold it up, so 
 that it may not fall forwards, while it may be 
 undermined, or its proper perpendicular sup- 
 ports taken away, loosened, or repaired. 
 
SI 
 
 SI 
 
 Shock, Electric. The rapid passage of a 
 current of the electric fluid through any 
 thing, particularly through any part of the 
 animal body; when it occasions a sudden 
 convulsion of the muscles, similar to that 
 caused by a blow. The shock passing from 
 a common electrical battery is sudden, in- 
 stantaneous in its passage, and momentary 
 only in duration ; that from the galvanic and 
 magnetic battery is more continuous. 
 
 Shoe. The part at the bottom of a water 
 trunk or leaden pipe, for turning the course 
 of the water. 
 
 Shooting Stars. (See Aeroliths.) 
 
 Shrine. A small chest or coffer, for con- 
 taining the ashes of saints or other holy 
 relics. 
 
 Shuttle. The instrument employed in 
 weaving to hold the bobbin of silk, cotton, 
 &c., with which the cross threads are made. 
 The weaver throwing the shuttle backwards 
 and forwards through the alternately-raised 
 long threads, the silk, cotton, &c., unwinds, 
 and leaves a cross thread behind it in its 
 course. 
 
 Shwawpan. (See Swanpan.) 
 
 Side. In geometry, is used for any line 
 which forms one of the boundaries of a right- 
 lined figure, as the side of a triangle, squai-e, 
 &c. 
 
 Side Cutting. A term applied to earth 
 cut away on the side of a canal or rail-road, 
 for the purpose of obtaining material for an 
 embankment, when there is not sufficient 
 excavation upon the line to form it. 
 
 Side Forming. A road-way formed by 
 paring down part of a hill or other steep, so 
 as to form a road upon the side of it or near 
 the bottom ; in the latter case by means of 
 the earth thrown down. 
 
 Sideling Ground. Such as is inclined 
 or sloping, 
 
 SiDERi al. Any thing relating to the stars. 
 (See Dai/ and Year.) 
 
 SiDERUM. Bergman's name for phos- 
 phuret of iron. 
 
 Siding, Passing Place, or Turn Out, 
 (on railways.) A short line of additional 
 trackway laid by the side of railway, and 
 connected therewith at each extremity by 
 suitable curves ; the rails being constinicted 
 and disposed in such a manner, that the car- 
 riages can either proceed along the main line 
 or turn into the siding, as may be desired. 
 To accomplish which, the portion of rails for- 
 ming the junction of the siding with the 
 main line is made moveable to suit either 
 trackway, and is termed a switch. The oc- 
 cuiTcnce of sidings is most frequent in the 
 vicinity of depots and stations. 
 
 Sieve. An instrument for separating the 
 smaller particles of substances from the 
 
 symbols employed to indicate certain opera- 
 tions, as addition, subtraction, &c. 
 
 Signs of the Zodiac. (See Zodiac.) 
 Silex. (See Silica.) 
 
 Silica. The earth which constitutes nearly 
 the whole of rock crystal, flint, and other 
 stones of the quartz family. It was formerly 
 considered as a pure earth, but it is now 
 considered by chemists as of an acid ten- 
 dency, and called silicic acid. Pulverized 
 and assisted by heat it dissolves readily in 
 the alkalies potass, and soda, forming what 
 is called soluble glass, and is then soluble in 
 water, making the liquor of flint. Silica, 
 when pure, is a white powder, rough to the 
 touch, gritty between the teeth, insoluble in 
 water and acids, except in the fluoric acid. 
 
 Silicates. Compounds of silicic acid, and 
 the bases alumina, lime, magnesia, &c. 
 They constitute the greater number by far 
 of the hard minerals which encrust the ter- 
 restrial globe. 
 
 Siliceous. Containing flint or silica. 
 
 Silicic Acid. (See Silica.) 
 
 Silicon, called also Silicium, the base 
 of silica. It may be obtained by burning po- 
 tassium in silicated fluoric gas. The pro- 
 duct of the combustion is a brown cinder, 
 which, on being thrown into water, disen- 
 gages hydrogen with violence, and lets fall a 
 dark, liver-colored powder, upon which 
 water exercises no action. This matter is 
 silicon mixed with a salt of difficult solution 
 composed of fluorine, potassium and sodium. 
 The salt may, however, be removed by a 
 great deal of washing. 
 
 Silk. A glossy fibrous substance, the 
 produce of ditierent species of the silk-worm, 
 and woven in numberless fabrics, and textile 
 articles. 
 
 Sill. Cill. The horizontal part below a 
 window or door, whether of wood or stone. 
 
 Silouette. The profile of a person's face, 
 not painted according to natural colors, nor 
 yet in outline, but the exact side face, painted 
 so as to present an even black surface. 
 
 Silouette, or Profile Instrument. 
 A contrivance for taking the exact outline of 
 an object, particularly the outline of a per- 
 son's side face, the surface within which 
 outline is mostly filled up with a black color, 
 forming a silouette. The instrument is as 
 follows : — 
 
 Signs. In algebra and arithmetic are 
 
 A B is a slender rod, 6 or 8 feet long, 
 which is suspended by gimbals at C, so that 
 
SI 
 
 SI 
 
 it has freedom of motion in every direction, 
 the end B moving contrary wise to A. D is 
 a small frame, hanging on two uprights, or 
 in any other convenient mode, so that it 
 bears very slightly upon the point B, where 
 there is a pencil placed. E is the foot-board 
 of the whole. Now it is evident that as A 
 is moved, so will B move also, and trace at 
 the same time its course upon a piece of 
 paper, if that piece of paper be suspended on 
 D. We have then only to pass the end A 
 over the face of an object or person, and a 
 counterpart will be traced on D, the size of 
 which will be in proportion to the originals, 
 as A C is to C B. 
 
 Silt. The alluvial soil washed down, and 
 deposited upon the bottoms and sides of 
 rivers, by the action of the tides ; the term 
 is also indicative of any soft light description 
 of soil. 
 
 SiLURUS Electricus. a fish of the ray 
 kind, which gives shocks similar to those of 
 the gymnotus electricus or electrical eel. 
 
 Silvan. A name given by Werner to 
 tellurium. 
 
 SiLVATES. Compounds of the silvic 
 acid. 
 
 Silver. A well-known metal of a whiter 
 color and brighter lustre than any other ; it 
 melts at a bright red heat. It is exceedingly 
 malleable and ductile, affording leaves not 
 more than the ten thousandth of an inch 
 thick, and wire much finer than a human 
 hair. Pure atmospheric air scarcely alters 
 it, but such as is contaminated with smoke 
 or sulphureous vapors soon covers it with a 
 brown sulphuret. It is distinguished from 
 gold and platinum by its readily dissolving 
 in nitric acid ; and from other metals by its 
 salts (except its chloride), forming white 
 curdy precipitates, with a minute quantity 
 of sea salt, or any other soluble chloride. 
 Silver unites with oxygen in two proportions 
 forming oxydes ; also with sulphur, chlorine, 
 phosphorous, &c., and forms valuable alloys 
 with the other metals. 
 
 Silver, German. An alloy much used 
 for domestic articles, such as forks, spoons, 
 &c. Its composition is 8 parts of copper, 
 2 of nickel, and 3| of zinc. A better kind 
 is made by adding 1 part more of nickel. 
 
 Silvering. The art of covering any thing 
 Trith silver, or sometimes covering it with 
 what resembles silver in appearance, though 
 not really such. Silvering such articles as 
 picture frames is performed by painting over 
 the material with an adhesive varnish, and 
 then laying on silver leaf. Copper may be 
 sUvered over by rubbing it with the following 
 powder : — 2 drachms each of tartar and com- 
 mon salt, and ^ a drachm of alum, are mixed 
 with 15 or 20 grains of silver, precipitated 
 from nitric acid by copper. The surface of I 
 the copper becomes white when rubbed with J 
 
 this powder, which may afterwards be polished 
 with leather. 
 
 Silvering of Clock Dials, Scales 
 OF Barometers, &c., is performed by rub- 
 bing upon them a mixture of muriate of sil- 
 ver, sea salt, and tartar, and afterwards 
 carefully washing off the saline matter with 
 water. 
 
 Silvering of Pins, is effected by boiling 
 them with tin filings and tartar. 
 
 Silvering Glass Globes, &c., is done 
 with an amalgam, consisting of 1 part by 
 weight of lead, ^ a part of lead, the same of 
 pure tin, and 2 parts mercury. The solid 
 metals are first fused together, and when 
 nearly congealed the mercury is added. A 
 very gentle heat is sufficient to fuse this 
 amalgam. In this state it is poured into a 
 clean glass globe, intended to be silvered, by 
 means of a paper funnel, which reaches tr 
 the bottom. At a certain temperature i 
 will stick to the glass, which by a prope. 
 motion may thus be silvered completely, and 
 the superfluous amalgam poured out. 
 
 Silvering of Looking Glasses, is 
 done by laying out a sheet of tin foil, and 
 spreading over it some mercury with a hare's 
 foot ; these metals will unite, and the sheet 
 of glass being carefully slipped over it, so as 
 to exclude air bubbles, and pressed with a 
 heavy weight, it will unite with the metal, 
 and become what is commonly called silvered. 
 
 Silvio Acid, is an acid produced from 
 common rosin. It is of no useful applica- 
 tion in the arts. 
 
 SiMA, or SiMA Recta. (See Ogee.) 
 
 Similar Bodies. In physics, are such 
 as have the same component parts. 
 
 Similar Curves, are such, that any 
 right-lined figure being inscribed within the 
 one, a similar rectilinear figure may be in- 
 scribed within the other. 
 
 Similar Ellipses. Parabolas and hy- 
 perbolas are such as have their axes and 
 parameters proportional. 
 
 Similar Figures. Those of which the 
 several angles are respectively equal, with 
 the sides about the equal angles proportional. 
 The following are therefore similar though 
 not equal : — 
 
 Similar Sectors and Segments, 
 are those contained under equal arcs. 
 
 Similar Solids, are those which are 
 contained under the same number of similar 
 faces alike placed ; or such as have their 
 soUd angles equal each to each, and all such 
 
SI 
 
 SI 
 
 bodies are to each other as the cubes of their 
 like sides. 
 
 Similitude. The relation of things that 
 are similar to each other. 
 
 SiMiLOR. A gold-colored variety of brass. 
 
 Simple. That which is mixed or com- 
 pounded of other quantities or things. 
 
 Simple Equation. In algebra, is that 
 in which only the simple power of the un- 
 known quantity enters, as 7 co; = 6; or 
 3 X + ax = b. 
 
 Simple Galvanic Circle. (See Circle.) 
 
 Simple Quantity, is that which consists 
 of but one term as 4 a i ; a^ ; 20 b^, &c. 
 
 Simple, or Single Microscope. (See 
 Microscope.) 
 
 Sine, Cosine, and Versed Sine of 
 AN Arc In trigonometry, the sine of an arc 
 is a right line drawn from either extremity 
 of an arc, perpendicular to the radius, 
 joining the other extremity, and the centre 
 of the circle ; or it is half the chord of the 
 double arc. Thus the line D E, in the fol- 
 lowing figure, is the sine of the arc B D, 
 because it is drawn from the extremity D of 
 the arc B D, perpendicular to the radius C B. 
 Hence also D E is the sine of the arc A D. 
 Hence every angle and its supplement, or 
 what it wants of 180°, have the same sine 
 common to both. The cosine is the com- 
 plement of the sign, or what it wants of 90°, 
 the word co being merely a contraction of 
 the word complement. Thus D H, or its 
 equal C E, is the cosine of the arc B D, as is 
 also of the arc A D ; only in the latter case 
 it is accounted negative. The versed sine is 
 that part of the diameter intercepted between 
 the sine and the extremity of the arc. Thus 
 E B is the versed sine of the arc D B and A E, 
 the versed sine of the arc A D ; also G H is 
 the versed sine of the arc D G, or the co- 
 versed sine of the arc B D. 
 
 Sines, Arithmetic of, is a term frequently 
 employed to denote that branch of science 
 which exhibits the relation of the sines, co- 
 sines, tangents, &c., of arcs. 
 
 Sines, Law of the. When refraction takes 
 place in any media, the ratio between the 
 sines of the angles of incidence and of re- 
 fraction is constant, and is termed the index 
 
 of refraction. Thus in water, if the sine of 
 the angle of refraction be taken as unity, that 
 of incidence will be 1^ ; and therefore, the 
 index of refraction in water is marked as 
 1-336. This is called the law of the sines. 
 
 Singer's Electrical Column. (See 
 De Lu&s Dry Pile,) which is the same 
 instrument, Singer having only arranged it 
 in a neater and more convenient form. 
 
 Singer's Electrometer. An improve- 
 ment upon Bennett's gold-leaf electrometer, 
 inasmuch as it has a double 
 insulation, and therefore 
 retains its electricity for 
 a longer period. The in- 
 strument is represented 
 annexed. The outer case 
 is of glass, with a wooden 
 foot and brass top, 
 through the centre of 
 which top passes a glass 
 pipe of about half em 
 inch internal diameter. 
 A small brass table rests 
 upon this, and a wire 
 proceeds from the brass table downwards 
 through the glass pipe, and terminates in two 
 slips of gold-leaf, the wire not being allowed 
 to touch the glass tube, in consequence of 
 silk being twisted aroimd it in two places. 
 A body slightly electrified held towards 
 the upper table so influences the instrument 
 that the gold leaves diverge. 
 
 Single Floor and Single Frame. A 
 floor with only one tier of joists. 
 
 Single Hung. An expression applied to 
 window sashes, when only one of them is 
 moveable in the same vertical plane. 
 
 SiNicAL Quadrant, is a quadrant made 
 of wood or metal, with lines drawn from 
 each side, intersecting each other, with an 
 index divided by sines, also with 90° on the 
 limb, and sights at the edge. This quadrant 
 was formerly used for taking the altitude of 
 the sun, but it is grown into disuse since the 
 great improvement in the construction of 
 other instruments for the same purpose. 
 
 Siphon, or Syphon. A bent tube used 
 in drawing off wine, liquors, and other fluids ; 
 the principle of which may be illustrated as 
 follows : — If one end of the siphon or bent 
 tube M N O be put into a vessel of water, 
 and the other end without be lower than the 
 surface of the water, then, if the air be drawn 
 out, the water will ascend in the leg M N in 
 consequence of the pressure of the atmosphere 
 on the external surface of the liquid, from 
 which it will descend to by its own gravity, 
 and be there discharged, and will continue to 
 flow until the water is below the M end of 
 the siphon, or until it gets even with the 
 mouth O, whichever may first happen. The 
 atmosphere presses equally upon both ends 
 of the siphon, when the latter is fall of water ; 
 
SI 
 
 SK 
 
 but the water flows out of, that is, falls from 
 the longer tube, because the perpendicular 
 lieight of the water is greater in that than in 
 the shorter tube, consequently they do not 
 balance each other, but the heaviest falls ; 
 and as the water continually flows upwards 
 to supply the deficiency, or fill the vacuum 
 thus occasioned, the flow is constant. For 
 practical purposes, the siphon is usually 
 made with a cock to shut off the stream, 
 when required, and a mouth pipe to draw 
 away the air, and give it the first impulse, 
 as is represented in A. 
 
 Siphon, Wirtemherg, is a peculiar form 
 given to this instrument, to obviate the 
 difficulty there is in withdrawing the air from 
 a large tube. It is as shown in the above 
 figure B, and may be of glass or metal. Its 
 peculiarity consists in having equal legs, and 
 the lower end of them being turned up. 
 When used, the tube is immersed in water, 
 and thereby filled. It is th^n lifted up, and 
 one leg immersed in the liquid to be drawn 
 off, and which flows away by the leg which 
 is not immersed. It will be seen how in- 
 convenient this instrument is compared to 
 the other in general application. 
 
 Site. The situation of a building, and 
 sometimes the ground plot or spot of earth 
 it stands on. 
 
 Six's Register Thermometeb. This 
 instrument is represented below. It is a spi- 
 rit of wine thermometer, 
 with a long cylindrical 
 bulb, and a tube bent in 
 the form of a siphon, 
 with parallel legs, and 
 terminating in a small 
 cavity. A portion of 
 the two legs of the si- 
 phon from A to B is 
 filled with mercury ; the 
 bulb and the remainder 
 of both legs, as well as a 
 small portion of the 
 cavity, are filled with 
 highly-rectified and co- 
 lored alcohol. The 
 double column of mer- 
 cury is intended to give 4' 
 motion to two indices 
 C D ; the form of which 
 is better shown at E. Each index con- 
 Bists of a bit of iron wire, inclosed in a 
 
 tube, which is capped at each ex- 
 tremity by a button of enamel. Their di- 
 mensions are such, that they would move, 
 freely in the tube, were it not for a thread 
 of glass drawn from the upper cap of each, 
 and inclined so as to press against one side 
 of the tube, forming a dehcate spring of 
 sufficient power to retain the attached index, 
 at any part of the tube to which it is driven 
 by the mercury column. When heat expands 
 the spirit in the bulb, it depresses the mer- 
 cury in the limb A, and proportionably raises 
 it in B, and with it the index ; this last re- 
 maining fixed at the highest point that the 
 mercury reaches. On the other hand, a de- 
 crease of temperature allows the side A to 
 rise, and to carry up also its index ; and thus 
 the highest and lowest temperature since the 
 last examination of the instrument is regis- 
 tered. The indices are again brought down 
 to the surface of the mercury, by holding a 
 small magnet towards them. 
 
 Size. A kind of weak glue, used in many 
 trades. It is made of the shreds and parings 
 of leather, parchment, vellum, &c., boiled in 
 water and strained. The boiling is continued 
 for six or eight hours, and of course the finer 
 the material employed, the more transparent 
 will be the size. 
 
 Size, Gold. (See Gold Size.) 
 
 Skeleton. In its common signification, 
 all the bones of a dead animal, dried, cleaned, 
 and disposed in their natural position. The 
 term is, however, applied by mechanics to 
 the principal framing of various things, as 
 the skeleton of a house, which implies merely 
 the walls, rafters, roof, &c., as left from the 
 hands of the bricklayer. A skeleton clock 
 is one which is without the usual case, and 
 so fitted up, that the interior wheel- work is 
 visible. Skeleton keys are thin light keys, 
 with almost the whole substance of the bits 
 filed away, so that they may the more easily 
 escape the opposition presented by the wards 
 in ordinary locks. ■ 
 
 Sketch. In painting, drawing, &c., the 
 first idea of the subject of any given picture. 
 
 Skew-back, or Askew-back, The 
 course of masonry, forming the abutments to 
 a segmental arch, or to the cast iron ribs 
 employed in bridges. The skew-backs in 
 the following cut are shaded. 
 
 Skin. The external membrane of animal 
 bodies. 
 
SL 
 
 SL 
 
 Skirting. A narrow board forming a 
 slightly projecting base to a partition, in- 
 ternal wall, Sec. 
 
 Sky. The atmosphere, as divested of clouds 
 and vapour. 
 
 Skylights. Glass frames placed in a 
 roof with one or more inclined planes of 
 glass. 
 
 Slab. An outside plank or board, sawn 
 from the sides of a timber tree, and fre- 
 quently of very unequal thickness. Also a 
 thin, flat, square piece of marble, or other 
 stone. 
 
 Slacked Lime. (See Lime.) 
 
 Slag. Vitrified clinkers. 
 
 Slake. The saturating of quick lime with 
 water. 
 
 Slakin. a term used by smelters to ex- 
 press a spongy, semi-vitrified substance, 
 which they mix with the ores of metal to 
 prevent their fusion. It is the scoria or scum, 
 separated from the surface of a former fusion 
 of the same metal. 
 
 Slam. The refuse of alum works, often 
 employed as a manure in combination with 
 seaweed and lime. 
 
 Slap-Dash. A provincial term, more 
 commonly called by builders rough cast. It 
 is a composition of lime, and coarse sand or 
 gravel, reduced to the state of thin mortar, 
 and applied to the exterior of walls as a 
 preservative and ornament. 
 
 Slate. A blueish fossil stone, very soft 
 when dug out of the quarry, and thereby easily 
 cut or sawed into long thin squares, to serve 
 either for tiles for the covering of houses, 
 making tables, &c. Slate for these purposes 
 comes from Caenarvonshire, Westmoreland, 
 and Scotland. The principal kinds of slate 
 are : — 1. Mica slate, occasionally used for 
 covering buildings, when it appears as large 
 rough pieces. 2. Clay slate, the proper slate 
 for the above purpose, and* for tables, paving, 
 cisterns, school tablets, &c. 3. Whet slate, 
 used as a sharpening stone ; one variety of 
 which is known among workmen as Charley - 
 Forest stone; another is called Turkey stone. 
 4. Polishing slate, used by watch-makers, 
 engravers, &c. 5. Drawing slate, or black 
 chalk. 6. Adhesive slate. 7. Bituminous 
 shale. And 8. Slate clay. 
 
 Slatt. a thin slab of stone used to cover 
 buildings, distinct from what are called slates, 
 though the latter are used for the same pur- 
 pose, and have the same name. 
 
 Sledge. A carriage without wheels, 
 which moves along by a sliding motion. 
 
 Sleepers. The name of any pieces of 
 wood laid horizontally on the ground, or on 
 brick-work, &c., close or near to the ground, 
 to support a superincumbent weight, or to 
 steady any rails or frame- work. The follow- 
 ing shows the usual sleepers used upon rail- 
 and upon which the chairs for the 
 
 rails are fastened. They are about 9 ieet 
 long, 5 inches by 9 scantling, and 3 feet from 
 each other : — 
 
 Sleetch, corrupted into Slush. The thick 
 mud at the bottom of rivers. 
 
 Slide Rest. An appendage to a lathe, 
 which differs from the common rest, (see 
 Rest,) in this respect, that instead of the 
 tool being held in and guided by the hand, it 
 is made a fixture in the rest itself. It is, 
 however, capable of being moved in several 
 directions. First, backwards or forwards, in 
 front of the work. Secondly, more or leys 
 near to it ; and thirdly, higher or lower, as 
 occasion may require. An inspection of the 
 cut will show how these motions are obtained. 
 A is an iron foot, with upright socket, which 
 fastens to, and moves along the bed of the 
 lathe, as in the common rest. B is a screw, 
 to fasten the upper part at the requisite 
 height. C C is a piece of steel, 4 or 5 inches 
 long, of the shape represented, with a groove 
 along the middle of it, and graduated on one 
 side in equal parts. The whole of the part D 
 moves backwards and forwards upon C, owing 
 to a micrometer screw at the end of C, and 
 which extends along the whole of the channel, 
 and through a corresponding screw in the 
 side of D ; owing to the screw having a mi- 
 crometer head, it can move D in the most 
 exact and regular manner. In the upper 
 part of D is a groove, in which fits and slides 
 a second slider, and which is at right angles 
 to the first. This has a handle near one end, 
 and a square socket near the other end at E, 
 where the tool is fastened tightly by the screw 
 
SM 
 
 SM 
 
 at top. The use of the screws F and G is to 
 adjust the exact degree that the tool shall be 
 allowed to move forwards. A small handle 
 accompanies the micrometer screw, which 
 may be used or not as required. 
 
 Sliding. In mechanics, the motion of a 
 body along a plane, when the same face or 
 surface of the body keeps in contact with 
 the surface of the plane, being thus dis- 
 tinguished from rolling. 
 
 Slip, or Land Slip. A falling away of 
 the land on a railroad cutting, precipitous 
 beach, &c., in consequence of being under- 
 mined by wet, or other similar causes. 
 
 Slit Deal. Deals cut into two boards 
 only. 
 
 Slope. The name given to any inclination, 
 but more particularly to land, whether so 
 formed naturally, or in consequence of being 
 thrown up, or cut away into embankments or 
 excavations. 
 
 Sluice, or Sluice Gate. A description 
 of sliding shutter made in a lock or flood- 
 gate, that being lifted up the water may pass 
 through, but being closed down the water 
 may be stopped. 
 
 Small Wares, is the name given in this 
 country to textile articles of the tape kind, 
 narrow bindings of cotton, linen, silk, or 
 woollen fabric, plaited sash cord, braid, &c. 
 
 Smalt and Azure Blue. Glacial oxydes 
 of cobalt, made by fusing zaffre, which is the 
 impure oxyde of cobalt, with glass, or by 
 calcining a mixture of equal parts of roasted 
 cobalt ore, common potass, and ground flints. 
 In this way a blue glass is formed, which, 
 while hot, is dropped into water, and after- 
 wards reduced to a very fine powder. The 
 coarser particles constitute smalt : the finer, 
 azure blue. 
 
 Smeaton's Micrometer -Pyrometer. 
 The basis of this instrument is of solid brass, 
 which was chosen as of a mean expansibility 
 among the metals. E F is the bar to be 
 measured, resting on two notches ; one at- 
 tached to the fixed upright A B, and the other 
 to the principal lever HI. K is a strong ar- 
 bor* fixed to the basis, and intended to re- 
 
 ceive the ends of the two screws, H L, upon 
 which the principal lever H I turns. O is a 
 slender steel spring, intended to press against 
 the extremity of the bar ; and P is a check 
 rod to support the lever when the bar is re- 
 moved. T is called the feeler ; it is in the 
 form of the letter T, and is suspended^freely, 
 but without shake, between the points of the 
 screws M N. Q is the handle of the feeler, 
 which is moveable on a loose joint, so that 
 the feeler may be moved by the handle with- 
 out being irregularly aifected by the pressure 
 of the hand. The principal part of the in- 
 strumentfis S the micrometer screw, and W 
 the graduated circle or index plate, fixed on 
 the screw, which indicates the revolutions of 
 the screw on the index V. The micrometer 
 screw passes through two solid heads, per- 
 forated by a corresponding screw ; the piece 
 Y Z is made somewhat springy, and tends to 
 draw the micrometer screw backwards fromD, 
 by which its motion is rendered equable and 
 easy. The instrument is useful to ascertain 
 the expansion of different bodies when heated. 
 Thus immerse the base of the instrument up 
 to the dotted line in water of a known tem- 
 perature, and mark the effect upon the bar 
 *vhich is placed in the position E F upon the 
 micrometer screw. Taking away this bar, 
 and substituting another of different material, 
 their relative expansibilities can be compared, 
 the water remaining at the same temperature. 
 
 Smee's Galvanic Battery. A small 
 but extremely powerful arrangement of gal- 
 vanic circles. The construction will be un- 
 derstood by the figure, which shows a num- 
 ber of jelly pots, properly connected together. 
 
 Each jelly pot contains a double ring of zinc, 
 and between these a slip of platina, whick 
 
so 
 
 so 
 
 platina is made rough on the surface by de- 
 positing upon it also platina, by means of 
 
 ^^nn'.t ^PJ^' ^^' "^^^^^ *^« previously, 
 smooth surface into one which is rough, and 
 therefore as far as galvanism is concerned 
 more energetic. Silver leaf, copper leaf, or 
 charcoal, covered in the same way with pla- 
 tina, IS equally efficacious. The liquid em- 
 ployed to fill the cells is water with i of sul- 
 phuric acid. There is no necessity' for po- 
 
 though to prevent local action the zinc ought 
 to be amalgamated. 
 
 Smelling Salts. The sesquicarbonate 
 of ammonia, often improved in scent by an 
 essential oil, as that of bergamot or lavender. 
 
 Smelting. The melting of a metal in a 
 furnace by a blast or reverberating heat, par- 
 ticularly applied to the meltmg of iron n the 
 first manufacture of it from the ore. 
 
 fn fhl":^ V ""• ^ ^^S^^table principle peculiar 
 to the smilaa- sarsaparilla. 
 
 Smockmill. a windmill, only the top of 
 which turns to meet the wind 
 
 throw^n^ ^'"^^y ^i^id.^'l particles of carbon 
 thrown off from burning bodies, generally 
 more or less contaminated with oil tfr, acids! 
 or other substances, according to the nature 
 of the material which is on fire 
 
 Snail Movement. A name someti-xies 
 
 ^^e^^-r^ ^' ^ -- engi.:! 
 
 i."^ot^deJ^?::sj^^^ 
 
 (as in Beighton's and others,) always confaiiS 
 air the accumulation of which is prevented 
 by a small pipe with a valve to it, which 
 when the piston ascends, is kept close by 
 the pressure of the atmosphere, but which 
 during the downward stroke, openrand 
 suffers the air to escape. This is called the 
 snifting valve, because the air makes a noise 
 every time It blows through it, like a ma^ 
 snifting with a cold. 
 
 mlfUfj: \^^^^™^cal compound of fats or 
 oils with potash or soda, prepared for the 
 
 kinds, all of which come under the denomi- 
 nation of hard soaps or soft soaps ; the former 
 bemg made with soda, the latter with potass. 
 O the hard soaps, the principal are as 
 folows:-re//o^^or rosin soap, which con! 
 terns from one-quarter to one-half rosin to 
 the fat employed, either tallow or coarse 
 
 soap-this last is entirely a tallow soap, and 
 neither of them contain any rosin. Of" oilet 
 soaps, there are those called Windsor, rose 
 cinnamon, musk, camphor, 8fc., according as 
 they are scented. Transparent soap is made 
 by dissolvmg a hard soap in alcohol^ po^rLg 
 off the clear hquid in proper shaded pans 
 and allowing it to cool and harden. ^The 
 soft soaps are much used in them anufa;turcs 
 
 they are made with whale, seal, olive, and 
 Imseed oils boiled with strong caustic potass. 
 l<or the toilet, are used the celebrated shaving 
 soap, called Naples soap ; also pearl soap! 
 and almond cream. 
 
 Snow. A well-known phenomenon, of the 
 same nature as rain, but arising in a freezing 
 atmosphere, whereby the particles of mois- 
 ture are graduaUy crystallized, and unite in 
 such a manner together as to form a fleecy or 
 feathery mass of crystals, light compared 
 wi h hail or rain, yet of sufficient weight to 
 ta.ll to the ground with more or less rapidity. 
 The form of the Jlakes of snow are infinitely 
 varied, yet all partake more or less of an 
 hexagonal figure, some of extreme beauty, as 
 may be seen by the following forms, which 
 are only a few of those depicted bv Captain 
 Scoresby, as having been observed by him in 
 the Arctic regions : — 
 
 Soap-Stone. a species of steatite. It 
 imparts to the touch a peculiar feeling, like 
 fine white soap. The soap-stone of this 
 country is chiefly obtained from the Lizard, 
 m Cornwall, where it is found in connection 
 with serpentine, with which it is nearly 
 allied. It is much used in the manufacture 
 of porcelain ; also for polishing marble and 
 other stones. It is the basis of various 
 cosmetics, and is combined with carmine or 
 safflower to form rouge; it is also used under 
 the name of French chalk, in takin'^ out 
 grease spots from silks, stuffs, &c. 
 
 Socle, or Zocle. A square piece of ma- 
 sonry, of less height than its horizontal dimen- 
 sions, serving to raise pedestals, or to support 
 vases or other ornaments ; the socle is some- 
 c c 
 
so 
 
 so 
 
 times continued round a building, or an entire 
 part of a building. It has neither base nor 
 cornice, but is a plain, flat, and unoma- 
 mented stone, or range of stones. 
 
 Soda. One of the fixed alkalis, an oxyde 
 of sodium. It is generally procured from 
 the ashes of marine plants ; indeed its great 
 repository is the ocean, soda being the basis 
 of sea salt. Combined with carbonic acid, 
 soda is found in a mineral state in Egypt, 
 where it abounds, under the name of natron, 
 whence it is frequently called the mineral 
 alkali. It is a white, brittle mass, of a 
 fibrous texture, of a specific gravity of 1*536 ; 
 melting at a temperature under that of 
 redness ; dissolving readily both in water and 
 alcohol ; attracting carbonic acid when ex- 
 posed to the atmosphere, but hardly any 
 water. It forms soaps with tallow, oils, 
 wax, rosin ; dissolves wool, hair, silk, horn, 
 alumina, silica, sulphur, and some metallic 
 •'Bulphurets. It is used in chemical researches ; 
 in bleachmg ; as a detergent ; and in the 
 manufacture of soap and glass. That sub- 
 stance, commonly called soda, which is used 
 . by laundresses, &c., is in the state of a car- 
 i Iwnate. Crude soda is known in commerce 
 by the name of barilla. 
 
 Soda Water. Water impregnated with 
 carbonic acid gas ; so called, because fre- 
 vquently made by mixing together, in water, 
 ) tiie carbonate of soda and tartaric or citric 
 r acid. The union of these produce the solution 
 f cf a tartrate or citrate of soda, according to 
 'fthe acid used, while the carbonic acid 
 \ priginally in the carbonate, escapes with 
 effervescence, in the state of gas, supposing 
 the vessel uncovered, but if quickly corked 
 up, the gas is retained, and forms aerated 
 soda water. JErated waters may be, and 
 usually are, made without soda, although the 
 name is still retained. (See the next article.) 
 Soda Water Apparatus, or Fountain, 
 is an instrument for impregnating water with 
 carbonic acid gas. It may be made of various 
 forms. The following, however, is that 
 which is most usual : — It represents a double 
 fountain, one half of which is for soda water, 
 the other for ginger beer. Suppose K to be 
 the counter of a shop — all above this is only 
 for the conveyance of two pipes to H and I. 
 The lower part of the apparatus may be at 
 any distance, as in an adjoining shed or 
 apartment. A is a cask. Into this is to be 
 put some powdered chalk, and afterwards a 
 little sulphuric acid and water, through the 
 funnel F. The chemical action of these 
 liberate carbonic acid gas from the chalk. 
 This gas passes along the pipe B to another 
 cask C, which has been previously partly 
 filled with water through G. It rises through 
 the water, becoming partly condensed by the 
 water, and partly at a pressure above the 
 water; as soon therefore as the cock I is 
 
 turned, the condensed gas in C acts upon 
 the surface of the water, and drives it up the 
 pipe D to H, where it is drawn off. The 
 other side of the apparatus is precisely the 
 same, except that the water in the cask is 
 flavored previously with sugar and ginger. 
 
 Sodium. The metallic base of soda. It is 
 white like silver, softer and more malleable 
 than any other metal, and may be readily re- 
 duced into thin leaves. It is lighter than 
 water; its specific gravity being -970. It 
 softens at the temperature of 122°, and at 
 200° it is perfectly fluid. In the air it oxi- 
 dizes slowly, and gets covered with a crust of 
 soda. When thrown upon water, it is ra- 
 pidly oxidated, but does not take fire like 
 potassium. There are three oxydes of sodium. 
 
 Soffit. The ceiling of an apartment, di- 
 vided by cross beams into compartments ; 
 the hollows or pannels being enriched with 
 sculptures or painting. Also the under part 
 of an overhanging cornice or projecting bal- 
 cony, which may be supported by brackets, 
 &c. 
 
 Softening. In painting, the mixing and 
 blending of colors into each othes, by which 
 hard outlines, violent contrasts and crude- 
 ness, and abruptness of tint, is avoided. 
 
 Soft Soap. (See Soap.) 
 
 Soft Solders. Such as melt at a com- 
 paratively small degree of heat. (See Solder.) 
 
 Sol. The name given to the sun. (See 
 Sun.) 
 
 SoLANiA. The chemical principle peculiar 
 to aolannm or night-shade. 
 
 Solar. Relating to the sun ; as solar 
 month, solar year, solar eclipse, &c., for 
 which see the various substantives. 
 
 Solar Microscope. This instrument 
 consists of a common microscope, connected 
 to a reflector and condenser ; the former 
 being used to throw the sun's light on the 
 latter, by which it is condensed to illuminate 
 the object placed in its focus. One of these 
 microscopes is shown in section below, with 
 
so 
 
 so 
 
 a double object glass E C. The rav* fr««, 
 the sun op O L received ol'thXkW 
 glass or reflector D, which is capable of beinf 
 directed in any position, to throw the rays of 
 the sun on a condensing lens A. The object 
 Ln ?"r tl'^^y^ Illuminated by the con- 
 densed hght of the sun. This object is 
 placed ,n the focus of the microscopic lens C 
 which m the common instrument is the 
 
 natfon'"? r^^'^' >^* "^^" ^he combi! 
 nation of two lenses is used, the magnified 
 image is improved. This representation or 
 picture of the object is received on a wall or 
 screen, and the magnifying power will be 
 a ways as the distances I C to C A ; thus if 
 the acting force of the lens C is 1 inch, when 
 It forms an image on the other side at 5 feet 
 the linear amplification will be 60 times, o^ 
 the increase of surface 3600. 
 
 An improved modification of this micros- 
 cope IS shown in the next figure, where R is 
 the reflector. C the condenser. A the ob- 
 ject. B the microscope, which is here the 
 compound instrument, (see Microscope,) 
 with Its eye-piece fitting into the darkened 
 box D, having a concave at the bottom to re- 
 
 ! ceive the representation of the object. When 
 It »s used for drawmg, the front E is let down 
 to admit the hand. 
 
 Solar Rays. The particles of light which 
 emanate from the sun. (See PriJatJ.) 
 
 tru^^TpfZT^'- ('^^^''^«^-^^- 
 SoLAR System. That part of the universe 
 which comprises our sun and the various 
 heavenly bodies which revolve around him. 
 These are the eleven primary planets, their 
 
 The mn T'^'^It' ""^. innumerable comets! 
 The most noted hypotheses or systems, which 
 have endeavoured to explain the variois mo- 
 tions which take place m the solar system, 
 are those of Copernicus, Tycho Brahe, and 
 Ptolemy; (see these words.) There is rea- 
 son to suppose that the whole universe is but 
 a contmued series of solar systems ; each star 
 being a sun, and having its own planets and 
 other bodies attending upon him. 
 
 Solder. A metallic composition ; usedir 
 soldering or joining together other metals h^ 
 fusion. It IS a general rule with regard to 
 solders, that they should melt at a lower heat 
 than the metals which are to be united. The 
 solder of the plumber is composed of lead 
 and tin ; so also is that used by the tinman, 
 there being about 1 part of lead to 1 or 2 of 
 tin, according to the fineness required Pew- 
 ter IS soldered by the above, to which a little 
 bismuth IS added to render it more fusible. 
 Iron, copper, and brass, are soldered with an 
 alloy of zmc and copper, in nearly equal 
 parts. Silver sometimes with pure tin, but 
 more frequently with silver solder ; an alloy 
 consistmg of 5 parts of silver, 6 of brass, 
 and 2 ot zinc. Platinum is soldered with 
 fine gold. Gold with an alloy of silver and 
 gold or copper and gold. The copper- 
 smiths solder is made of 8 parts brass and 
 1 zmc, or else 6 parts brass, 1 tin, and 1 zinc. 
 Soldering. The art of uniting metals 
 together, by fusing between them an alloy or 
 solder. The conditions of soldering are the 
 perfect brightness of the edges to be soldered, 
 a solder wluch fuses at a less heat than the 
 metal itself the appUcation of a sufficient 
 heat to melt the solder and not the metal, 
 and prevention of oxidation on the bright 
 surfaces during the operation. The last is 
 effected by laying upon the bright parts either 
 turpentme, as the jewellers do ; or rosin, 
 like the plumbers and other artizans. Sal 
 ammoniac is also very serviceable for this 
 purpose. 
 
 Soldering, Autogenous. A method of 
 joining metals without the aid of what is 
 called a solder. The parts of the metals to 
 be united are brought close together and 
 brightened ; then held under a fine jet of 
 burning gas. The intense heat of this, urged 
 as It may be by a blow-pipe, uistantaneously 
 melts the metal at the edges, so that the one 
 
so 
 
 so 
 
 times continued round a building, or an entire 
 part of a building. It has neither base nor 
 cornice, but is a plain, flat, and unoma- 
 raented stone, or range of stones. 
 
 Soda. One of the fixed alkalis, an oxyde 
 of sodium. It is generally procured from 
 the ashes of marine plants ; indeed its great 
 repository is the ocean, soda being the basis 
 of sea salt. Combined with carbonic acid, 
 soda is found in a mineral state in Egypt, 
 where it abounds, under the name of natron, 
 whence it is frequently called the mineral 
 alkali. It is a white, brittle mass, of a 
 fibrous texture, of a specific gravity of 1*536 ; 
 melting at a temperature under that of 
 redness ; dissolving readily both in water and 
 alcohol ; attracting carbonic acid when ex- 
 posed to the atmosphere, but hardly any 
 water. It forms soaps with tallow, oils, 
 wax, rosin ; dissolves wool, hair, silk, horn, 
 alumina, silica, sulphur, and some metallic 
 sulphurets. It is used in chemical researches ; 
 in bleaching ; as a detergent ; and in the 
 manufacture of soap and glass. That sub- 
 stance, commonly called soda, which is used 
 by laundresses, &c., is in the state of a car- 
 bonate. Crude soda is known in commerce 
 , |»y the name of barilla. 
 I Soda Water. Water impregnated with 
 ; carbonic acid gas ; so called, because fre- 
 j- quently made by mixing together, in water, 
 l tiie carbonate of soda and tartaric or citric 
 f acid. The union of these produce the solution 
 f of a tartrate or citrate of soda, according to 
 j-the acid used, while the carbonic acid 
 fpriginally in the carbonate, escapes with 
 'effervescence, in the state of gas, supposing 
 ' the vessel uncovered, but if quickly coi-ked 
 ; up, the gas is retained, and forms serated 
 Boda water. iErated waters may be, and 
 usually are, made without soda, although the 
 name is still retained. (See the next article.) 
 Soda Water Apparatus, or Fountain, 
 is an instrument for impregnating water with 
 carbonic acid gas. It may be made of various 
 forms. The following, however, is that 
 which is most usual : — It represents a double 
 fountain, one half of which is for soda water, 
 the other for ginger beer. Suppose K to be 
 the counter of a shop — all above this is only 
 for the conveyance of two pipes to H and I. 
 The lower part of the apparatus may be at 
 any distance, as in an adjoining shed or 
 apartment. A is a cask. Into this is to be 
 put some powdered chalk, and afterwards a 
 little sulphuric acid and water, through the 
 funnel F. The chemical action of these 
 liberate carbonic acid gas from the chalk. 
 This gas passes along the pipe B to another 
 cask C, which has been previously partly 
 filled with water through G. It rises through 
 the water, becoming partly condensed by the 
 water, and partly at a pressure above the 
 water; as soon therefore as the cock I is 
 
 turned, the condensed gas in C acts upon 
 the surface of the water, and drives it up the 
 pipe D to H, where it is drawn off. The 
 other side of the apparatus is precisely the 
 same, except that the water in the cask is 
 flavored previously with sugar and ginger. 
 
 X 
 
 _^^^ss^ 
 
 
 H/ 
 
 1 -^ 
 
 vP° 
 
 
 Sodium. The metallic base of soda. It is 
 white like silver, softer and more malleable 
 than any other metal, and may be readily re- 
 duced into thin leaves. It is lighter than 
 water; its specific gravity being -970. It 
 softens at the temperature of 122°, and at 
 200° it is perfectly fluid. In the air it oxi- 
 dizes slowly, and gets covered with a crust of 
 soda. When thrown upon water, it is ra- 
 pidly oxidated, but does not take fire like 
 potassium. There are three oxydes of sodium. 
 
 Soffit. The ceiling of an apartment, di- 
 vided by cross beams into compartments ; 
 the hollows or pannels being enriched with 
 sculptures or painting. Also the under part 
 of an overhanging cornice or projecting bal- 
 cony, which may be supported by brackets, 
 &c. 
 
 Softening. In painting, the mixing and 
 blending of colors into each othej, by which 
 hard outlines, violent contrasts and crude- 
 ness, and abruptness of tint, is avoided. 
 
 Soft Soap. (See Soap.) 
 
 Soft Solders. Such as melt at a com- 
 paratively small degree of heat. (See Solder.) 
 
 Sol. The name given to the sun. (See 
 Stm.) 
 
 SoLANiA. The chemical principle peculiar 
 to solemum or night-shade. 
 
 Solar. Relating to the sun ; as solar 
 month, solar year, solar eclipse, &c., for 
 which see the various substantives. 
 
 Solar Microscope. This instrument 
 consists of a common microscope, connected 
 to a reflector and condenser ; the former 
 being used to throw the sun*s light on the 
 latter, by which it is condensed to illuminate 
 the object placed in its focus. One of these 
 microscopes is shown in section below, with 
 
so 
 
 so 
 
 a double o^ect glass E C. The rays from 
 the sun O O O are received on the lookinff 
 glass or reflector D, which is capable of beinf 
 directed m any position, to throw the rays of 
 the sun on a condensing lens A. The object 
 I IS thus strongly illuminated by the con- 
 densed light of the sun. This object I 
 placed m the focus of the microscopic lens c! 
 which m the common instrument is the 
 n^irt ^'^Pl^y^d; b^t when the combi- 
 nation of two lenses is used, the magnified 
 image is improved. This representadoTor 
 picture of the object is received on a wall or 
 screen, and the magnifying power will be 
 always as the distances I C to C A ; thus if 
 he acting force of the lens C is 1 inch, when 
 t forms an image on the other side at 5 feet, 
 the linear amplification will be 60 times, o^ 
 the mcrease of surface 3600. 
 
 An improved modification of this micros- 
 cope IS shown in the next figure, where R is 
 the reflector. C the condenser. A the ob- 
 ject. B the microscope, which is here the 
 compound instrument, (see Microscope,) 
 with Its eye-piece fitting into the darkened 
 Dox D, having a concave at the bottom to re- 
 
 ceive the representation of the object. When 
 It >8 used for drawing, the front E is let down 
 to admit the hand. 
 
 P J° W ^""^u ^^^ P^'"*^*^^^^ «^ ^'Sht which 
 emanate from the sun. (See PHsr^atic.) 
 
 Solar Spectrum. {Sq& Prismatic Spec 
 trum or Prism.) ^ 
 
 Solar System. That part of the universe 
 which comprises our sun and the various 
 heavenly bodies which revolve around him. 
 inese are the eleven primary planets, their 
 various satellites, and innumerable cimets. 
 Ihe most noted hypotheses or systems, which 
 have endeavoured to explain the various mo- 
 tions which teke place in the solar system, 
 are those of Copernicus, Tycho Brahe, and 
 Ptolemy; (see these words.) There is rea- 
 son to suppose that the whole universe is but 
 a continued series of solar systems ; each star 
 
 «r^ I T' ^"^ ^^^^S ^^ o^n planets and 
 other bodies attending upon him. 
 
 Solder. A metallic composition ; usedir 
 soldering or joining together other metals b, 
 fusion. It IS a general rule with regard to 
 solders, that they should melt at a lower heat 
 than the metals which are to be united. The 
 solder of the plumber is composed of lead 
 and tin ; so also is that used by the tinman, 
 there being about 1 part of lead to 1 or 2 of 
 tin, according to the fineness required. Pew- 
 ter ,s soldered by the above, to which a little 
 bismuth IS added to render it more fusible. 
 Iron, copper, and brass, are soldered with an 
 alloy of zmc and copper, in nearly equal 
 parts. Silver sometimes with pure tin, but 
 more frequently with silver solder ; an alloy 
 consistmg of 5 parts of silver, 6 of brass, 
 and 2 ot zinc. Platinum is soldered with 
 fine gold. Gold with an alloy of silver and 
 gold, or copper and gold. The copper- 
 smiths solder is made of 8 parts brass and 
 1 zmc, or else 6 parts brass, 1 tin, and 1 zinc. 
 Soldering. The art of uniting metals 
 together, by fusing between them an alloy or 
 solder. The conditions of soldering are the 
 perfect brightness of the edges to be soldered, 
 a solder winch fuses at a less heat than the 
 metal itself, the application of a sufficient 
 heat to melt the solder and not the metal, 
 and prevention of oxidation on the bright 
 surfaces during the operation. The last is 
 eflfected by laying upon the bright parts either 
 turpentme, as the jewellers do; or rosin, 
 like the plumbers and other artizans. Sal 
 ammoniac is also very serviceable for this 
 purpose. 
 
 Soldering, Autogenous. A method of 
 joining metals without the aid of what is 
 called a solder. The parts of the metals to 
 be united are brought close together and 
 brightened ; then held under a fine jet of 
 burning gas. The intense heat of this, urged 
 as It may be by a blow-pipe, mstantaneously 
 melts the metal at the edges, so that the one 
 
so 
 
 edge unites with the other, without the neigh- 
 bouring parts being injured. 
 
 Solid. In geometry, a magnitude of three 
 dimensions, extended in length, breadth, and 
 thickness. A solid is terminated by, or con- 
 tained under one or more surfaces, as a sur- 
 face is by one or more lines ; from the 
 circumstance of the terminating lines, solids 
 are either regular or irregular. 
 
 Solid. In physics, is that whose parts ad- 
 here to each other with a greater or less force ; 
 being thus distinguished from a fluid, whose 
 parts yield to the least external pressure. 
 
 Solid Angle, is an angle formed by three 
 or more plane angles meeting in a point, as 
 the angle at the top of a pyramid. (See 
 Angle.) 
 
 Solid Numbers, are those arising from 
 the product of three prime factors ; thus 
 2, 3, and 5, multiplied together, makes the 
 solid number 30 : so 7 x 11 x 13 = the solid 
 number 1001. 
 
 Solid Problem, is that which cannot be 
 constructed geometrically ; namely, by means 
 of right lines and circles, but requires the 
 introduction of some curves of a higher order, 
 as the ellipse, parabola, hyperbola, &c., 
 which being the sections of solids, give rise 
 to the term solid problem ; it is not, however, 
 often employed by modern writers. 
 
 Solid or Least Resistance. (See Re- 
 sistance.) 
 
 Solidific A.TI0N. The making of any thing 
 solid ; thus we say the freezing or solidi- 
 fication of water into ice. 
 
 Solidity. In geometry, denotes the quan- 
 tity of space contained or occupied by a 
 solid body, called also its solid content, 
 being estimated by the number of solid 
 inches, feet, yards, &c. which it contains. 
 
 Solstice, In astronomy, that time when 
 the sun is in one of the solstitial points, that 
 is, when he is at the greatest distance from 
 the equator ; thus called, because he then 
 appears to stand still and not to change his 
 distance from the equator for some time. 
 The solstices are two in each year, called 
 respectively the summer and the winter 
 solstice. The former is where the sun is in 
 the tropic of Cancer, which is about the 
 21st of June, being then the longest day. 
 The winter solstice is when he enters the 
 first degree of Capricorn, about the 22nd of 
 December, being then the shortest day. 
 This is to be understood only of the northern 
 hemisphere, it being directly the reverse 
 with regard to the longest and shortest days, 
 and summer and winter, in southern latitudes. 
 
 Solstitial Colure. (See Colure.) 
 
 Solstitial Points. Those two points in 
 the ecliptic which are farthest from the 
 equator, and diametrically opposite to each 
 other, being the first pomts of Cancer and 
 Capricorn. 
 
 SO 
 
 ^ 
 
 Soluble Cream of Tartar, or Sal 
 GuMMosuM, is made by adding 2 parts of 
 borax to 5 of crystals of tartar, in powder, 
 and evaporating the solution to the con- 
 sistency of honey ; it then concretes into the 
 above substance. 
 
 Soluble Prussian Blue. Prussian blue 
 is only soluble in water when a persalt of 
 iron is added to excess of a solution of ferro- 
 cyanuret of potassium. The compound thus 
 formed is soluble in pure water, but not in 
 saline solutions ; it consists of 1 atom of 
 ferro-cyanuret of potass and 1 of Prussian 
 blue. 
 
 Soluble Tartar. The tartrate of potass ; 
 so called in opposition to the bi-tartrate, 
 which is less soluble. 
 
 Solution. In mathematics, is the opera- 
 tion whereby the answer of a question or 
 problem is determined. In physics, it is the 
 reduction of a solid to a fluid state, by dis- 
 solving it in some liquid. 
 
 SooT. The powdery black mass, deposited 
 by smoke when becoming cool. It is often 
 collected as a pigment, making lamp black 
 and Frankfort black. 
 
 Sorbic Acid. The same as malic acid. 
 
 SoRTANT Angle. (See Angle.) 
 
 SoRY. An old name for sulphate of iron. 
 
 Sough. A small drain, situated at the top 
 of an embankment, for the purpose of con- 
 veying the surface water from it into the side 
 drain. The term is also applied to an adit in 
 some parts of the counti-y, 
 
 Sound. A noise or perception of the mind, 
 communicated by means of the ear, being the 
 effect of the collision of bodies, and their 
 consequent tremulous motion, communicated 
 to the surrounding medium, and hence trans- 
 mitted to the organs of hearing. Sound 
 therefore to be heard requires three con- 
 ditions. First, a sufficient collision to cause 
 vibration. Second, a medium of sufficient 
 mobility to receive a similar vibration, and 
 consequently to transmit the sound; and 
 thirdly, a certain degree of perfection of the 
 organs of hearing to receive the transmitted 
 impression. Sounds are as various as are 
 the means that concur in producing them ; 
 particularly the form, character, and condi- 
 tion of the sonorous body, the rapidity of 
 vibration given to it, and the state of the 
 atmosphere or other medium, which trans- 
 mits the vibration. The velocity of sound, 
 however, never varies ; the rate at which it 
 travels being 1142 ; or, as some say, 1107 
 English feet in a second of time. 
 
 Sound Board. The same as a canopy 
 over a pulpit, or a part of a musical instru- 
 ment, placed so as to intercept and reverbe- 
 rate the sound. 
 
 South. One of the four cardinal points 
 of the compass, being that directly opposite 
 the north. 
 
SP 
 
 SP 
 
 South Poles. (See Pole.) 
 
 Southern Hemisphere, Latitude, 
 &c. Those on the south side of the equator. 
 
 Southing. In navigation, the difference 
 of latitude made by a ship in sailing to the 
 southward. 
 
 Space. A simple idea, of which the modes 
 are distance, capacity, extension, duration, 
 &c. Space considered with regard to length 
 only is the same idea as we have of distance. 
 If it be considered with respect to length 
 and breadth, or length, breadth, and thick- 
 ness, it is the same as capacity. When con- 
 sidered between the extremities of matter, 
 which fills the capacity of space with some- 
 thing solid, tangible, and moveable, it is 
 synonymous with extension. Space, therefore, 
 in the general signification, is the same thing 
 with distance, considered every way, whether 
 there be any solid matter in it or not. 
 
 Span of an Arch. Its width from hut- 
 ment to butment. 
 
 Span Roof. A roof consisting of two 
 inclined sides or sets of rafters, such as are 
 used to cover ordinary houses. 
 
 Spandrel Bracketing. A cradling of 
 brackets fixed between two or more curves, 
 each in a vertical plane, and in the circum- 
 ference of a circle, whose plane is horizontal. 
 
 Spandrels. The triangular spaces be- 
 tween the curve of an arch and a square 
 head or dripstone over it. It is usually 
 ornamented with foliage or a shield. 
 
 Spanish Burtons. (See Burtons.) 
 SPANNSiRS. A certain portion of some of 
 the old steam engines, the object of v^hich is 
 to catch hold of the tappets on the plug 
 frame, that when this latter is lifted up and 
 down by the action of the engine, they may, 
 by their alternate motion, move the valves to 
 
 admit or shut off the steam. (See BeightorCa 
 Hand Gear.) 
 
 Spar. In mineralogy, those minerals that 
 break easily into crystals or laminated frag- 
 ments with polished surfaces. A spar, among 
 builders, is a large round piece of timber, 
 fit for making masts, yards scaffolding poles, 
 &c. 
 
 Spar, Doubly -Refractive. (See Carbonate 
 of Lime.) 
 
 Spar, Fluor, or Derbyshire Spar. The 
 fluate of lime in a crystallised form. 
 
 Spar, Ponderous. Heavy spar ; barytes 
 in the state of a carbonate, as it occurs in 
 many parts of Great Britain, &c. 
 
 Spark, Electrical. (See Electric Light.) 
 
 Spatula. A thin knife, used mostly to 
 extend, superficially, some semi-fluid matter. 
 
 Species. In algebra, are the letters, 
 symbols, marks, or characters, which re- 
 present the quantities in any operation or 
 equation. 
 
 Specific Caloric. (See Caloric.) 
 
 Specific Gravity. A comparison of 
 every solid or fluid with the weight of the 
 same magnitude of rain water. Rain water 
 is chosen as the standard of comparison on 
 account of its being less subject to variation 
 in different circumstances of time, place, &c. 
 than any other body, whether solid or fluid ; 
 and by a very fortunate coincidence, at least 
 to English philosophers, it happens that a 
 cubic foot of rain water weighs 1000 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, de- 
 note the weight of a cubic foot of each, in 
 avoirdupoise ounces, which is a great con- 
 venience in numerical computations. 
 
 Spectacles. An optical instrument, con- 
 sisting of two lenses set in a frame, and ap- 
 plied on the nose to assist in defects of the 
 organs of sight. 
 
 Spectacles, Periscopic. (See Peria- 
 copic.) 
 
 Spectra, Ocular. The same as acci- 
 dental colors, (which see.) 
 
 Spectrum. In optics. (See Prism. 
 
 Speculum. The same as a mirror. (See 
 Mirror.) 
 
 Speculum Metal, An alloy adapted for 
 making the specula of telescopes, &c. It 
 is composed of 6 parts copper, 2 tin, and 
 1 arsenic. 
 
 Spermaceti. A substance obtained from 
 the oil found in the head of several species 
 of whale, but chiefly from the Physeter 
 macrocephalus. An ordinary-sized whale 
 will yield, it is said, upwards of twelve large 
 barrels of crude spermaceti. The chief em- 
 ployment of spermaceti is for making candles 
 and ointments. 
 
SP 
 
 SP 
 
 Sphere, or Globe. A ball or solid, whose 
 Burface is everywhere equally distant from a 
 certain point within the solid, which point 
 is called the centre of the sphere. 
 
 Sphere. In astronomy, that concave orb 
 or expanse which appears to invest our globe, 
 and in which all the heavenly bodies appear 
 fixed. This is also called the sphere of the 
 world, and is the subject of spherical trigo- 
 nometry. The sphere as it relates to the fixed 
 Btars being immensely great, the spectator 
 always judges himself in the centre, and the 
 calculations made on this supposition deviate 
 not in the least sensible degree from the truth. 
 
 Sphere, Armillary. (See Armillary.) 
 
 Sphere, Direct or Right, is that which 
 has the poles of the world in the horizon, and 
 the equator in the zenith and nadir. An 
 oblique sphere cuts the horizon obliquely: 
 in a parallel sphere the poles are in the 
 zenith and nadir, and the equator coincides 
 with the horizon. 
 
 Sphere, Circles of. (See Circle.) 
 
 Sphere of Activity of a Body, is 
 used to denote the space through which the in- 
 fluence of any body, as a magnet, &o. extends. 
 
 Spherical. Relating to a sphere. 
 
 Spherical Aberration. (See Aberra- 
 tion.) 
 
 Spherical Bracketing. The forming 
 of brackets to support lath and plaster work, 
 80 that the surface of the plaster shall form 
 the surface of a sphere. 
 Spherical Polygop. A figure of more 
 than four sides, formed on the surface of a 
 sphere by the intersection of several of its 
 great circles. 
 
 Spherical Valve. (See Ball Valve.) 
 
 Sphericity. The quality of a sphere, or 
 that by which a thing becomes spherical. 
 
 Spherics. The doctrine of the sphere, 
 particularly of the several circles described 
 on its surface, with the method of projecting 
 the same on a plane. 
 
 Spheroid. A solid somewhat resembling 
 a sphere, differing from it however in not 
 having every part of the surface equi-distant 
 from the centre ; but yet if one diameter of 
 it be taken as an axis, the surface perpen- 
 dicular to that axis will always be a circle. 
 Spheroids are irregular or universal, as an 
 egg ; or regular, when they are called oblate, 
 and oblong or prolate ; according as they 
 may differ from a true sphere is being broader 
 than long, like an orange; or longer than 
 broad, like a lemon. 
 
 Spheroidal, or Spheroidical. Having 
 the form of a spheroid. 
 
 Spheroidal Bracketing. The bracket- 
 ing prepared for a plaster ceiling, whose 
 surface is to form that of a spheroid. 
 
 Spherule. A little globe or sphere. 
 
 Spider, Electrical. A small ball of 
 pith, cut of the size, and into the form of a 
 
 spider, suspended by a long filament of iilk, 
 and with eight linen thread legs. When this 
 is held between the knob connected with the 
 inside of a Leyden jar, and a ball connected 
 with the outside, (as shown in the cut,) or 
 otherwise, as may be most convenient, and 
 the bottle or jar has been charged by an elec- 
 trical machine, the spider will pass alternately 
 from one ball to the other, until by the con- 
 veyance of the accumulated fluid from the 
 inside of the bottle to the outside it will be 
 discharged. 
 
 Spindle. In geometry, as a solid, is a cir- 
 cular body, tapering towards both ends ; as 
 a superficies, it is flat, tapering also at both 
 ends. The same as would be caused by two 
 equal arcs of equal circles, meeting each 
 other, so as to inclose the greatest space 
 possible. 
 
 Spindle, in mechanics, is a thin arbor, by 
 which to connect together wheel-work, to 
 support wheels in their requisite position, 
 &c. &c. In weaving, it is a thin piece or 
 bobbin of wood or steel, on which yam, linen, 
 &c., is wound after it has been twisted. 
 
 Spinning. The art of combining vegeta- 
 ble fibres into threads, by twisting them 
 together, as in cotton, silk, wool, flax, hemp, 
 &c. 
 
 Spiral. A curved line, of a circular form, 
 which in its progress always recedes more and 
 more from a point within, called the centre. 
 There are various kinds of spirals, namely : — 
 The spiral of Archimedes, the logarithmic 
 spiral, the loxodromic spiral, the parabolic 
 spiral, &c., according to the law by which the 
 point recedes from the centre. The Archi- 
 median spiral is generated by supposing the 
 arc of a circle to be divided into any number 
 of equal parts in P P P P P, &c. ; then radii 
 being drawn from the centre to these points, 
 
SP 
 
 SP 
 
 divide one of them into the same number of 
 equal parts, and make C M, C M, C M, &c., 
 equal to I, 2, 3, &c., of these parts ; and 
 the line drawn from the centre passing through 
 these several points will be the spiral of 
 Archimedes. It differs from the logarithmic 
 spiral in this, that here the distances C M are 
 in arithmetical progression, but in the loga- 
 rithmic Spiral in geometrical progression. 
 
 It is particularly called the first spiral when 
 it has made one revolution to the point A, 
 and the space included between the spiral and 
 the radius A C is called the spiral space. The 
 first spiral may be continued to a second, by 
 describing another circle with a radius double 
 that of the first, and continuing proportional 
 divisions as before. This spiral may be made 
 mechanically by winding a thread round a 
 pencil, ruler, or other cylinder. On gradually 
 unwinding it the loose end will describe the 
 spiral. The hyperbolic or reciprocal spiral is 
 as follows: — If from one of the extremities C 
 of the right line F C as a centre, with the 
 distances C D, C E, C F, &c., as radii, a 
 number of arcs D E F G H be described, so 
 as to be all equal in length to each other, the 
 curve C K L M N drawn through the extre- 
 mities is called the hyperbolic or reciprocal 
 spiral, of which the line C F is called the 
 axis, and the point C the centre. 
 
 For the logarithmic spiral, see Logarith- 
 mic : and for the loxodromic spiral, see 
 Rhumb. The spiral of pappus is a spiral 
 formed on the surface of a sphere, in the 
 same manner as that of Archimedes is on a 
 plane. A natural spiral is constructed in the 
 same manner as the Archimedean, with the 
 difference that it is traced upon the surface 
 of a cone. This kind of spiral is seen on 
 many screws ; for example, the gimlet point. 
 
 It is also the spiral which is so common on 
 the shells of fish and snails, as the whelk, 
 periwinkle, &c. The parabolic or helicoid 
 spiral is a curve arising from a supposition of 
 the common parabola being bent round into 
 the periphery of a circle. If, for instance, the 
 axis of a parabola be bent into the peri- 
 phery of the circle B D M, then the curve 
 B E G N A which passes through the ex- 
 tremities of the ordinates C E, D G, &c., 
 which converge towards the centre of the 
 circle A, will constitute the curve, which is 
 called the helicoid or parabolic spiral. 
 
 Spirai,, Electro-Magnetic. (SeeDeRivef 
 Sturgeon, Sfc.) 
 
 Spiral Pump. (See Archimedes Screw.) 
 Spiral Tube. An electrical apparatus to 
 show that the electric fluid, although passing 
 invisibly through or over con- 
 ducting substances, yet becomes 
 visible when an interruption in 
 those conducting bodies takes place. 
 The spiral tube consists of two glass 
 tubes, one fitting within the other ; 
 on the outside of the inner tube a 
 spiral line of spangles of tin-foil is 
 pasted — they being placed so as 
 very nearly to touch each other. 
 A brass ball at each end secures 
 the tubes together. "When one 
 ball is held in the hand, and the 
 other made to approach the prime 
 conductor of an electrical machine, 
 a spark will run along the tube 
 and be visible at every interval 
 between the spangles. When a 
 number of these tubes are placed upon 
 a stand, a rapid succession of sparks may 
 be given to each in rotation, by means 
 of a central piece A and B. A is a brass 
 wire terminated by two balls, and poised by 
 a pin at the centre. B is a glass rod with a 
 brass cap and socket at top to support A. 
 When this brass cap is connected with the 
 machine, and A is made to turn round by 
 the finger, each time one of its balls comes 
 in contact with the balls on the top of the 
 spiral tube, a spark wiU be given off" and run 
 
SP 
 
 sv 
 
 down the tube. This instrument is called 
 the set of spirals, and is represented beneath. 
 
 Spire. A long pyramid erected upon the 
 lantern of a tower, mostly polygonal or 
 square, rarely round ; often called a steeple. 
 Spirit Blow-Pipe. (See Alcoholic.) 
 Spirit Lamp. Any small lamp which is 
 fed by spirits of wine, or pyroacetic spirit, 
 rather than by oil, producing a large and 
 hot flame, though little light and no smoke ; 
 the lamp being used in chemical operations, 
 to heat retorts, test tubes, &c., and not for 
 tiie light it affords. Spirit lamps are usually 
 made of glass, with a brass top to hold the 
 wick, and supplied with a cover, which fits 
 over the top when it is desirous to extinguish 
 the flame. 
 
 Spirit Level. (See Level.) 
 
 Spirit of Mindererus. A solution of 
 acetate of ammonia ; made by adding con- 
 crete carbonate of ammonia to distilled vinegar 
 till saturation takes place. 
 
 Spirit of Nitre. Nitric ether. 
 
 Spirit of Sal Ammoniac. Liquid am- 
 monia. 
 
 Spirit of Salt. Hydro-chloric, formerly 
 muriatic acid. 
 
 Spirits of Turpentine. A highly in- 
 flammable and strongly smelling liquor, ob- 
 tained by the distillation of turpentine. 
 
 Spirit of Wine. Alcohol. 
 
 Spirit, Pyroacetic. (See Acetone.) 
 
 Spirit, Rectified. (See Alcohol.) 
 
 Spirit, Sulphuretted. A liquid obtained 
 by passing a current of sulphuretted hydro- 
 gen through an aqueous solution of ammonia. 
 It is indifferently called the hydro -sulphuret 
 of ammonia, hydro -sulphate of ammonia, 
 Boyle's fuming liquor, and Beguin's sulphu- 
 retted spirit. 
 
 Spirit, Vinous. Alcohol. 
 
 Spirituous Liquors. Such as contain 
 alcohol, and which therefore are the result of 
 fermentation, with or without being afterwards 
 concentrated by distillation ; such as beer, 
 wines, gin, rum, brandy, cider, &c. 
 
 Splay. A sloping surface, as windows of 
 Gothic buildings are splayed inwards ; the 
 muUions of a window are often splayed or 
 pared off. 
 
 Splice. To conjoin lengthwise two flexible 
 pieces by the interposition of their respective 
 parts, so as to maintain them in conjunction 
 by friction. 
 
 Spoil, or Spoil Bank. The surplus eexth 
 thrown up on the side of an excavation, 
 placed there for no particular use, but merely 
 to save the expense of removal. 
 
 Spokes. The radial pieces wliich connect 
 the periphery of a wheel with its centre-piece 
 or nave ; this term is only applied to carriages. 
 
 Spongy Platinum. The metal platinum 
 in a state of minute sub-division. 
 
 Sporades. a name given by the ancients 
 to those stars that were not included in any 
 of the constellations. 
 
 Sportsman, Electrical. An amusing and 
 ingenious instrument, to illustrate the fact 
 that a charged electrical jar will discharge 
 itself if the outer and inner coating approach 
 too closely. The inner coating of the Leyden 
 jar is connected with two wires, one of which 
 proceeds to the birds, (these are small piecesi 
 of pith, with feathers for wings, and attachedl 
 to 4 or 5 inches in length of a fine linen" 
 thread ;) the other wire proceeds to within 
 a small distance of the muzzle of the gun. 
 
 The gun is connected with the outer coatin j 
 of the phial by means of the wire proceeding 
 
SP 
 
 ST 
 
 from it to the figure, and a slip of tin-foil, 
 which is pasted along the figure to the 
 muzzle. Connecting the phial with the 
 electrical machine in action, it will, of course, 
 become charged, during which time the birds 
 will elevate themselves by electrical repulsion ; 
 when the bottle is charged to a certain extent, 
 the dist-ance between the muzzle of the gun 
 and the ball near it will not be sufficient to 
 restrain the passage of the fluid, which will 
 therefore pass between them, occasioning at 
 the same time a flash of light, a loud report, 
 and the falling of the birds. 
 
 Spots. In astronomy. (See Facula and 
 Maculce.) 
 
 Spring. In natural philosophy, is a foun- 
 tain or source of water rising out of the earth, 
 and yielding a supply more or less constant, 
 according to different circumstances. Those 
 which run continually are called perennial; 
 while such as run only for a time, and at 
 certain seasons of the year, are called tempo- 
 vary springs. Others again are called inter- 
 mittent springs, because they flow and then 
 stop, and flow and stop again ; (see Inter- 
 mittent.) And finally, reciprocating springs, 
 whose waters rise and fall, or flow and ebb at 
 regular intervals. 
 
 Spring. In mechanics, is used to denote 
 any thing which is perfectly elastic. The 
 following is one of a spiral form, of common 
 use in watch and clock-work. It possesses 
 very considerable power and long continued 
 action in a small space : — 
 
 Spring. In astronomy, that season of the 
 year in which the sun passes through the 
 three first signs of the zodiac, Aries, Taurus, 
 and Gemini, extending from the time of the 
 vernal equinox, or the 21st of March, to the 
 period of the summer solstice, or the 21st of 
 June. During this period the sun's decli- 
 nation is north, and continually increasing, 
 consequently his meridian altitude, the length 
 of the days, and the warmth of the weather 
 increases also. 
 
 Spring, Strength or Force of, is used for 
 the force or weight, which when the spring 
 is wholly compressed or closed will just 
 prevent it from unbending itself; also the 
 force of a spring partly bent or closed, is the 
 force or weight which is just sufficient to 
 keep the spring in that state by preventing 
 it from unbending itself any farther. 
 
 Spring Arbor. The arbor or spindle 
 
 round which the main spring of a watch is 
 turned. 
 
 Spring Box. The box in which the main 
 sprhig of a watch is contained. 
 
 Springers. The two first slwnes of an 
 arch, one above each impost. 
 
 Spur Gear. Wheels whose axles are 
 parallel to each other, that is, those wheels 
 the teeth of which are perpendicular to their 
 axles. 
 
 SauARE. In geometry, is a superficies 
 inclosed by four equal sides, and having the 
 four angles of it right angles, and con- 
 sequently equal. As an adjective, it is any 
 thing the section of which would be a square 
 or part of a square. 
 
 SauARE. Among workmen, is a term 
 applied to any material when two of the 
 sides stand perpendicular to each other; 
 also an instrument for trying whether an 
 angle be a right angle or not. 
 
 Square, Magic. (See Magic.) 
 
 Square-Framed. Amongjoiners, signifies 
 work which has all the angles of its styles, 
 rails, and mountings square, without being 
 moulded. 
 
 Square Number, is the product arising 
 from a number being multiplied by itself, or 
 a number formed of two equal factors ; 
 therefore 64, 36, and 25, are square numbers, 
 being produced by the multiplication of 
 8 by 8, 6 by 6, and 5 by 5. We conse- 
 quently call 64 the square of 8 ; 36 the 
 square of 6 ; and 25 the square of 5. 
 
 Square Root. (See Root.) 
 
 Square Staff. A piece of wood used 
 for fortifying the angles of plaster-work in- 
 tended to be papered over. 
 
 Squaring a Material. The cutting it 
 into a square or rectangular form. 
 
 Staff. A thick round stick ; the upright 
 pieces of wood which form the front of a bay 
 rack are called staffs^ and so are the teeth o» 
 a trundle. 
 
 50 
 
ST 
 
 ST 
 
 gradually screwing it up, cuts the edge of the 
 paper or book with an even surface. 
 
 Stationer's, or Bookbinder's Sewing 
 Press. This is very erroneously called a 
 press, its use being merely to keep a book 
 steady, while the several sheets of it are 
 sewed together. B B are two upright screws, 
 fastened to a base board A A, which has a 
 channel cut along, and through it, towards 
 the front edge and between the screws. C is 
 a cross bar, fitting loosely on B B, and sup- 
 ported at any required height by the two 
 nuts D D. When a book is to be sewed, 
 strings are fastened to the cross bar C, 
 brought through the channel of the base 
 board, and confined underneath by small pins. 
 The sheets of paper are folded, pressed, 
 knocked so as to be level at the back and top 
 edge, put in the cutting press, screwed up, 
 and with a small toothed saw, several grooves 
 for the string and thread are cut transversely 
 across the back, all but the two end ones 
 having a string for it. The first sheet of 
 paper is taken, the strings adjusted to the 
 saw cuts ; a needle and strong thread is en- 
 tered at one of the terminal cuts, where there 
 is no string, passed within the sheet, out at 
 the next cut, across the first string ; into 
 the sheet again at the second string, out at 
 the third, and so on to the end cut, where 
 there is no string. It is, therefore, made 
 immediately to pass into the next sheet of 
 paper, and passing along it in like manner is 
 finally fastened to where it first entered the 
 first sheet, thus connecting both sheets to- 
 gether. The process is continued until the 
 whole number Of sheets are connected. 
 
 Statue. A solid representation of a 
 human form, free and unconnected with 
 any building. The size of statues, among 
 the ancients, was dependent upon the use to 
 
 be made of them, and the person represented. 
 First, those smaller than life were mostly 
 carved in wood, or cast in bronze, and kept 
 as moveable ornaments, or as relics in houses ; 
 such were the penates or household gods. 
 Second, of natural size, made to perpetuate 
 the memory of some renowned individual; 
 the deities were sometimes of this size, as the 
 Apollo Belvedere, and the Venus de Medicis. 
 Third, statues half as large again as life, re- 
 presenting emperors. Fourth, twice as large 
 as life, to celebrate heroes, such as the 
 Falernian Hercules. Fifth, of a yet greater 
 size, called colossi, to represent the gods ; 
 for example, the statue of Minerva, within 
 the Parthenon ; the Colossus of Rhodes, &c. 
 
 Statuary. In a general sense, the art of 
 casting statues ; also a statue or a group of 
 statues. The Laocoon is a fine example of 
 the latter ; as are also many of the monu- 
 ments within St. Paul's Cathedral — the death 
 of General Abercrombie for example. 
 
 Statuary Marble. Any marble adapted 
 to the use of the statuary. 
 
 Staves. Any long narrow pieces of wood 
 that are braced together side by side, for the 
 formation of a cask, a hollow cylinder, cone 
 or conoid, or any frustrum of these bodies. 
 
 Steam. The name given to the visible 
 moist vapour, which arises from all bodies 
 that contain juices easily expelled from them 
 by heats not sufficient for their combustion. 
 Thus we say, the steam of boiling water, of 
 malt, of a tan bed, &c. It is distinguished 
 from smoke by its not having been produced 
 by combustion, by not containing any soot, 
 and by its being condensed by cold into wa- 
 ter, oil, inflammable spirits, or Uquids com- 
 posed of these according to the substance it 
 arose from ; the steam from fermented 
 liquors being condensable into a spirituous 
 Uquid, that from coal tar yielding naphtha, 
 and that from water turning to water again. 
 It is the latter kind, indeed, that is usually 
 understood to be implied when steam is al- 
 luded to, and it is this which is applied to 
 such numerous purposes of steam machinery 
 and engines, and as the means of supplying 
 heat to various bodies. Steam possesses 
 great elasticity when confined ; it also has a 
 great degree of latent heat, which it readily 
 gives out to surrounding bodies. Steam, 
 when rising from water in an open vessel, is 
 only able to counteract the downward pres- 
 sure of the atmosphere, or but little more ; 
 it is then called low pressure steam ; but ii 
 the water whence it arises is contained in a 
 close vessel, as steam is constantly generated^ 
 without having the power to pass off, it soon 
 accumulates and obtains a proportionately 
 greater power, it is then called high pressure 
 steam. 
 
 Steam Boat. Any boat, the impulse of 
 which is derived from the power of steam 
 
ST 
 
 acting upon an engine, connected with pad- 
 dle wheels attached to the sides of the vessel. 
 
 Steam Carriage. Any carriage or land 
 vehicle which is worked by steam, and 
 carries passengers or goods. This latter 
 circumstance distinguishing it from a loco- 
 motive engine, which draws other carriages 
 after it. 
 
 Steam Cylinder, Chest, Case, Jacket, 
 Valve, Cock, &c. &c. Portions of various 
 apparatus for the containing or the con- 
 veyance of steam. 
 
 Steam Engine. A machine wrought by 
 the force obtained from the expansion and 
 contraction of the steam of boiling water, 
 and employed as a first moving power t6 
 other machines. All steam engines consist 
 of two distinct parts, necessarily connected 
 together ; these are, the boiler, in which 
 steam is generated, and the enffitie, properly 
 so called, where it is applied to produce 
 motion, and where it is condensed. Steam 
 engines are divided into stationary, marine, 
 and locomotive, into low pressure or at- 
 mospheric engines, and hiffh pressure en- 
 gines, and are often known by the purposes 
 to which they are applied, the principle in- 
 volved in their structure, or the name of 
 their inventor ; thus we have, as applied to 
 them, the terms cylinder, beam, bell-crank, 
 rotatory, pumping, stamping, Savary, New- 
 comen, &c. The history and progress of 
 this noble implement of manufacture, drain- 
 ing and locomotive, may be traced by turn- 
 ing to the names of the various inventors, 
 in the following order, the dates of inven- 
 tion being annexed : — ^ropile and Hero's 
 Fountain, 130 years B. C. ; De Caus, 1615 ; 
 Branca, 1629; Worcester, 1663; Savary, 
 1698 ; Newcomen's, or the atmospheric en- 
 gine, 1705; Papin, 1707; Desagulier, 1716; 
 Beighton, 1718; Leupold, 1720; James 
 Watt, 1765; Cartwright, 1782; Cooke, 
 1786; Francois, 1791; Murdock, 1799; 
 Nuncarrow, 1799; Trevithick and Vivian, 
 1802, (this is a locomotive engine) ; Boaz, 
 1805 ; and Masterman, 1822. The par- 
 ticulars of an ordinary steam engine boiler 
 are already given under the word Boiler. The 
 usual parts of the engine itself are, perhaps, 
 best shown by Watt's double -action engine, 
 figured in the section beneath, where A is 
 the steam-pipe conveying the steam from the 
 boiler into the cylinder B, by means of the 
 slide valves C ; D is the condenser ; E the 
 air-pump, the rod of which is connected 
 with the working beam P ; F the injection 
 cock ; G the cold water cistern ; H the hot 
 water cistern ; I a jacket, called a steam 
 jacket, to inclose the cylinder, and by keep- 
 ing its exterior warm to prevent condensa- 
 tion in that part ; K is the piston rod ; I the 
 parallel motion ; M the governor connected 
 with the throttle valve in the steam pipe ; 
 
 ST 
 
 N the hot water pipe for the supply of the 
 boiler by means of the pipe Q ; O the eold 
 water pipe to supply the cold water cistern ; 
 P the working beam ; R the crank beam ; 
 S the fly-wheel. The valves are worked by 
 tappets on the air-pump rod, as at T. The 
 principle of these parts are described under 
 their respective names. (See Cylinder^ Con- 
 denser, Governor, Valve, 8fc.) 
 
 Steam Gauge. (See Gauge Cocks.) 
 
 Steam Pipe. The pipe communicating 
 with the upper part of the steam engine 
 boiler, through which the steam passes in its 
 passage to the cylinder. 
 
 Steam Tight, denotes such a degree of 
 closeness as prevents the escape of steam. 
 
 Steam Wheel. A rotatory steam engine, 
 such as are described under the words Cooke 
 and Cartwright. 
 
 Steam Whistle. A device attached to 
 locomotive engines for giving warning when 
 the engine is starting or approaching the 
 terminus. It consists of a pipe situated at 
 the top of the boiler, with a cock to the 
 same, within reach of the engine man, who 
 is thus enabled to turn off or on the steam 
 at pleasure. When turned on, it issues 
 through the pipe into a hollow cup, passing 
 through four holes in a plate placed at the 
 bottom of it ; the steam then escapes at the 
 top, round the thin edge of the cup, and 
 striking it with considerable force, produces 
 a loud shrill whistle, which can be heard at 
 a distance of many miles. 
 
 Stearic Acid, otherwise called Stea- 
 rin e. The solid constituent of fatty sub- 
 stances, as of tallow and olive oil, converted 
 
ST 
 
 ST 
 
 into a crystalline mass by saponification with 
 alkaline matter, and abstraction of the alkali 
 by an acid. By this process fats are con- 
 verted into three acids, called stearic, mar- 
 garic, and oleic ; the first two being solid, 
 and the last liquid. The solid acids are se- 
 parated from each other by washing them in 
 alcohol, which holds the margaric acid in so- 
 lution after it has deposited the stearine in 
 crystals. These are of a pearly whiteness, 
 insipid, and inodorous ; insoluble in water ; 
 of a needle-like form, and grouped together. 
 Beautiful candles are often made from stearic 
 acid. 
 
 Stkarone. When stearic acid is distilled 
 with a fourth part of quicklime, a substance 
 is obtained sparingly soluble in ether and 
 alcohol ; concrete at common temperatures, 
 but fusible at 180°. This is called siearone. 
 
 Steatite. (See Soap Stone.) 
 
 Steel. A compound of iron and carbon ; 
 made by placing bars of iron, surrounded by 
 charcoal powder, in a box of fire-stone, co- 
 vering the layers of iron and charcoal, with 
 sand, and placing the whole in a strong oven 
 or furnace. These are kept in a red hot 
 state for eight or ten days. This process is 
 called cementation. The bars of steel formed 
 in this way are raised in many parts iut.o 
 small blisters ; on this account steel made 
 thus is called blistered steel. The bars 
 of blistered steel are heated to redness, and 
 drawn out into smaller bars by means of a 
 hammer, called a tilting hammer ; on which 
 account the bars made by it are called tilted 
 steel. When the bars are broken in pieces, 
 welded repeatedly, and then drawn out 
 into bars again, they acquire the name of 
 German or shear steel. Blistered steel is 
 never quite equable in its texture, but it is 
 rendered quite so by fusing it in a crucible, 
 and then casting it into bars ; thus treated it 
 is called cast steel. It is used chiefly for 
 edge tools, and other cutting instruments, 
 for the rubbing parts and points of ma- 
 chinery ; and from the fine polish of which 
 it is susceptible, its applications to orna- 
 mental, as weU as useful purposes, are as 
 obvious as they are well known. 
 
 Steel, Gilding of. Delicate steel instru- 
 ments, painted with or dipped into an ethereal 
 solution of chloride of gold, become covered 
 with a bright surface of the latter metal. In 
 this way swords, &c. are gilt. 
 
 Steelyard. A kind of balance, called 
 also statera Romana, or the Roman balance, 
 by means of which the weights of different 
 bodies are discovered by using one weight 
 only. The common steelyard consists of an 
 iron beam, B C, resting upon knife edges or 
 a pivot, and having one arm, B C, much 
 longer than the other D G ; yet the end G 
 being large and heavy, it with the proper 
 seale attached exactly balances the long arm 
 
 E C. On the long arm slides a moveable 
 hook E, and weight P. Equilibrium is esta- 
 blished, or in other words the weight of any 
 thing placed in the scale W is ascertained by 
 moving the weight P backwards and forwards, 
 until it acquires such a leverage that the beam 
 is horizontal, and as the long arm is graduated 
 from E to B the weight is immediately seen 
 upon the scale. 
 
 Steelyard Valve. (See Safety Valve.) 
 Steeple. Any part of a church above the 
 roof. It may be a tower only, or a tower 
 and spire. 
 
 Stencilling, or Oriental Tinting. 
 A method of producing the picture of an ob- 
 ject without drawing it. The method is as fol- 
 lows : — Suppose a heart's-ease flower is to be 
 represented ; lay a piece of thick transparent 
 paper over it, and with a pencil trace round 
 such parts of it as are to be blue ; for in- 
 stance, the upper petals and three spots on 
 the lower ones. Then at a little distance 
 trace the lower or yellow petals, and on a 
 separate part of the paper, the green leaves 
 and the stem, in the manner represented ; 
 taking care that different colors do not 
 run into each other: Cut out all these 
 places, then lay the blue part over a sheet of 
 white paper, and rubbing the proper colors 
 on a pallet, take up a little with a stiff, short- 
 haired brush, and rub it on the holes apper- 
 taining to the blue petals ; the color will of 
 course be left on the paper below. Then 
 change the position of the guide paper for the 
 yellow petals, and placing it carefully, rub 
 on with another brush a yellow color ; after- 
 wards, in like manner, the green color for the 
 leaves. This bemg done, the flower will be 
 complete and effective, in proportion to the 
 care bestowed upon it. The walls of rooms 
 are often stencilled in this manner, but with 
 little care, and more rapidity than can be 
 used with delicate objects. The following 
 cuts show the guide, and the figure of the 
 object made by putting its various holes in a 
 proper juxta-position. The black parts are 
 
ST 
 
 ST 
 
 to be considered as holes cut through a piece 
 of thick transparent paper. 
 
 Steps. The various lifts or degrees of a 
 staircase, by which we ascend or descend ; 
 divided into treads, or the portion trodden 
 upon ; and risers, which are those parts that 
 elevate the treads above each other. 
 
 Steps, or Bearings. In engineering, 
 those parts that receive the lower gudgeons 
 of upright shafts. 
 
 Stereobate. An old word synonymous 
 with the modem socle. 
 
 Stereo-electric Current. (See T/ter- 
 mo-electric Current.) 
 
 Stereography. That branch of solid 
 geometry which demonstrates the properties, 
 and shows the construction of all solid bodies 
 which are regularly defined. It also explains 
 
 the methods for constructing the surfaces in 
 planes, so as to form the entire body, or to 
 cover the entire surface of the solid. As an 
 example, the five regular bodies (see Bodies,) 
 maybe formed by cutting paper or card of the 
 various forms represented in the cut, when 
 folding them up their edges will coalesce, 
 and the required solid be formed. A is the 
 tetrahedron ; B the cube ; C the octahedron ; 
 D the dodecaliedron, and E the ieosahedron. 
 
 Stereotype. The art of casting solid 
 plates from moveable types, in order that 
 the former may be used at a future time, in- 
 stead of incurring the expense of recom- 
 posing or resetting the type. The process 
 of stereotyping is as follows : — The page (or 
 pages) of type are laid back downwards on a 
 smooth horizontal surface, and either oiled, 
 or preferably rubbed over with black-lead. 
 It is then surrounded with a brass edge or 
 frame, plaster of Paris is mixed with water 
 and poured upon it, so as to make a cast of 
 the type ; this, when set, is taken off and 
 dried in an oven. When dry, each cast is 
 laid with the impression downwards, upon a 
 flat cast iron plate, called the floating plate, 
 this plate being itself laid on the bottom of 
 the dripping pan, which is of cast iron ; a 
 lid is put upon thin and secured in its place 
 by a screw. The pan having been heated to 
 400° in the oven, previous to receiving the 
 mould, is ready to be plunged into the bath 
 of melted alloy, contained in an iron pot 
 placed over a furnace ; into this it is dipped, 
 and as there is a small space between the 
 cover of the dripping pan and the top of the 
 floating plate, the hot metal running in at 
 the corners, lifts up the mould and flows 
 freely into all its interstices. When full, it 
 is taken out and placed with its bottom 
 touching a surface of water. The metal thus 
 congeals at the bottom first ; metal is poured 
 in to allow for shrinking in cooling, and pro- 
 duce a fine impression. The pan being taken 
 asunder, the compound cake of metal and 
 mould is taken out, and beat upon its edges 
 with a wooden mallet to detach the super- 
 fluous metal. The stereotype plate is then 
 handed over to the picker, who planes its 
 edges truly square, turns its back flat in a 
 lathe to a determinate thickness, and carefully 
 removes any imperfections which may have 
 arisen from dirt or air left in the letters, &c. 
 
 Stereotype Metal. An alloy for the 
 casting of stereotype plates, consisting of 
 9 lbs. of lead ; to which, when melted, are 
 added 2 lbs. of antimony and 1 lb. of bismuth. 
 This alloy expands as it cools. 
 
 Sterling, Standard or Guinea Gold, 
 consists of 11 parts of pure gold and 1 of 
 copper. 
 
 Stibium. Antimony. 
 
 Stick Lac. Lac or lac resin, which still 
 adheres to the sticks or twigs of the tree from 
 
ST 
 
 ST 
 
 which it has exuded. It is of coarser quality 
 than shell lac. 
 
 Stile. (See Style.) 
 
 Still. A chemical apparatus, for vapo- 
 rizing liquids in one part, called by chemists 
 'he cucurbit ; and condensing the vapors in 
 nother part, called the refrigeratory. The 
 general purpose of both combined being to 
 eparate the more volatile fluid particles for 
 hose that are less volatile. In its simplest 
 Drm it consists of a retort and a receiver, or 
 
 of a pear-shaped alembic or mattrass, and 
 head, furnished with a slanting tube for con- 
 veying away the condensed liquid in drops ; 
 whence the term still, from stillare, to drop. 
 
 by this process a purer and stronger liquid 
 than when first put into the still. 
 
 Stills like the above are used for the ma- 
 king of various oils, acids, and other liquids, 
 in small quantities ; for the purposes of ma- 
 nufacture, particularly of ardent spirit, a 
 larger apparatus is necessary. The following 
 is the. still used by the distiller : — 
 
 B is the still itself, which is like a copper 
 with a contracted top, set in brick-work, and 
 with a fire-place beneath. C is the head and 
 neck of the still, which fits tightly on to the 
 body of it. E the end of the neck, where 
 the head unites to the worm. F the worm 
 tub, containing the worm or refrigerator. 
 (See Worm.) G the cock, supplying cold 
 water to condense with. Impure spirit being 
 placed in B, it is made to boil. The steam 
 from, it rises, passes over the head into the 
 worm, and around the various coils ; being 
 condensed, and more and more cooled 
 in its passage, until it issues in a stream 
 from the lower end of the worm, becoming 
 
 Still Life. In painting, the representa. 
 tion of inanimate objects, such as dead ani- 
 mals, sometimes with fruit and flowers in 
 addition. The interest of such represen- 
 tations can consist only in the form, grouping, 
 and light ; hence the pictures of still life 
 belong to the lowest description of painting. 
 Still YARD. (See Steelyard.) 
 Stippling. A mode of engraving on cop- 
 per or steel, or painting on paper, by means 
 of dots, as contradistinguished from a course 
 of continued lines. The term is likewise ap- 
 plied to the mode adopted by some artists, in 
 drawing, of putting in the tints and shadows 
 of black lead or crayons, by means of the 
 end of a piece of coiled paper or leather, 
 (called a stump,) charged with the pigment 
 with which it is stippled or stamped on to 
 the surface of the paper. 
 
 Stocks. A frame erected on the shore of 
 a river or of the sea ; and in large establish- 
 ments in the inside of docks, for the purpose 
 of building ships. It generally consists of a J 
 number of solid wooden blocks, ranged pa- I 
 rallel to each other, at convenient distances, '' 
 upon a very firm foundation, and with a 
 gradual declivity towards the water. 
 
 Stoichiometry. That branch of chemical 1 
 knowledge which treats of the proportions "jj 
 that substances must have when they enter 
 the state of neutrality ; that is, when they 
 counteract each other's effects. 
 
 Stones. Mineral bodies ; hard, insipid, 
 not either ductile, malleable, metallic, or so- 
 luble in water. Used for almost endless pur- 
 poses of ornament, paving, building, polishing, 
 grinding, slating, road-making, &c. Stones 
 are usually divided into three heads ; the 
 siliceous, or those formed of silex, which are 
 the hardest and least liable to decay, com- 
 prising granite, sand-stone, &c. Second, the 
 arffillaceous, or those composed of clay, 
 which class comprehends basalt, and nearly 
 all the slate stones ; these are mostly soon 
 affected by the atmosphere when exposed. 
 
ST 
 
 And, thirdly, the calcareous, or those formed 
 of lime ; a very numerous class, containing 
 all the lime- stones from the marble down- 
 wards to chalk. These are the principal in- 
 gredients in all cements, and the remains of 
 antiquity sufficiently prove their durability. 
 
 Stone, Artificial. A composition which 
 stands the weather, and has the appearance 
 of stone. There are three kinds ; one made 
 of the same materials, and resembling pot- 
 tery ware, baked for a long time, until it 
 becomes veiy hard. The second is laid on a 
 surface, becoming harder by time ; such are 
 Parker's cement, stucco, &c. A third kind, 
 adapted for statues, vases, &c., is made of 
 plaster of Paris and powdered marble dust, 
 mixed up with alum water. 
 
 Stones, Precious. (See Gem.) 
 
 Stone Blue. A compound of indigo and 
 starch. 
 
 Stoneware. A hard kind of pottery. 
 
 Stool, Electrical. This is a stool, fur- 
 nished with glass legs, for the purpose of in- 
 sulating a person or object placed upon the 
 top of the stool, in order that they may be 
 subjected to electrical influence. A person 
 placed upon a stool of this kind, (its legs 
 being perfectly dry,) and connected with the 
 prime conductor of an electrical machine, 
 when the machine is put in action, the per- 
 son forming in fact a part of the prime con- 
 ductor, will become charged with the fluid, 
 so that sparks may be taken from any part 
 of him. A stool of this kind is used in 
 administering electricity medically. 
 
 Stop-Cock. The ordinai-y name given to 
 the small brass taps or cocks used in pneu- 
 matic apparatus, and of which the follow- 
 ing are representations : — The first figure 
 shows the common stop-cock, which has a 
 male screw at each end. The figure on the 
 side of it is a connecting piece, used to join 
 one stop-cock to another, when it is necessary 
 
 ST 
 
 to transfer gases through or into them. The 
 lower figure shows a stop-cock so contrived 
 at one end, that a bladder may be firmly 
 united to it ; the other end having a small 
 screw, to which a tube or other apparatus 
 may be attached. 
 
 Storax. Styrax. a resin which flows 
 from the twigs and trunk of the liquid amber 
 styraciflua, a tree which grows in Louisiana, 
 Virginia, and Mexico. Liquid amber, as the 
 resin is so called, is a brown or ash-grey 
 substance, of the consistence of turpentine, 
 which dries up quickly, has an agreeable 
 smell like benzoin, and a bitterish, sharp, 
 and burning taste. It dissolves in 4 parts of 
 alcohol, and afibrds 1*4 per cent, of benzoic 
 acid. 
 
 Story Post. An upright piece of timber 
 disposed in a story of a building, for sup- 
 porting the superincumbent part of the 
 exterior wall, by means of a beam over them 
 resting upon two or more story posts. 
 
 Stove. A fire-place, more or less close, 
 for warming apartments. When it allows 
 the coals to be seen, it is called a stove-grate. 
 
 Straight Line. (See Line.) 
 
 Straining Piece. In building, a piece 
 of timber used as a strut between other 
 timbers which press equally upon both its 
 ends. This is a general term, and does not 
 imply any particular piece of timber or 
 portion of a building. 
 
 Straker's Lithographic Press. This 
 is an elegant and powerful instrument for the 
 taking oft" lithographic impressions. A is a 
 heavy strong table, supporting the rest of 
 the press, which is iron. B is the table, upon 
 which the stone is laid ; it draws in and out, 
 when without pressure, by a handle attached 
 
 51 
 
ST 
 
 ST 
 
 to one end. C is the scraper, -a piece of box 
 wood with a sharp and smooth edge. E is 
 the tympan, supposed in the cut to be turned 
 upon the stone which lies on the table. The 
 scraper is borne down upon E by the screw H, 
 or rather by a short lever which is placed in 
 that situation. F F are the two sides or 
 frame work. D is the handle. To work the 
 press, the stone is placed upon B, a sheet of 
 paper is then put over it ; E is then turned 
 down upon the paper. The scraper G ad- 
 justed by the lever above ; turning the han- 
 dle draws the table and tympans under the 
 scraper, which thus produces the impression, 
 as explained in Lithography. 
 
 Strand. One of the twists or divisions 
 of which a rope is composed ; also the name 
 applied to any sea beach or shore that slopes 
 gradually down to the water's edge. 
 
 Stranded. As applied to a rope, signifies 
 that one, at least, of its strands is broken ; 
 but when applied to a ship or vessel, it 
 means that she has run on a rock or shoal, 
 and been either rendered unmanageable or 
 entirely dashed to pieces. 
 
 Strata. Stratum. A single layer or 
 bed of any thing, as a stratum of stone, of 
 gravel, &c. ; as applied to a natural deposit 
 of coals or salt, the term seam is more 
 commonly used. 
 
 Stratus. A widely-extended and con- 
 tinued sheet of cloud is so called. 
 
 Stream. A flow of water, gas, &c. from 
 one place to another. 
 
 Stream Wheels. (See Water Wheels.) 
 
 Strength. In physiology, the same as 
 force. 
 
 Strength of Materials. The force 
 which any material is capable of resisting 
 before it breaks, whether from pulling, com- 
 pressing, squeezing, from being twisted, or 
 from bending by a force applied laterally. 
 
 Stretching Cqurse. In brick-work and 
 masonry, a row of bricks or stones, with 
 their longest sides exposed to view. The 
 bricks or stones thus laid are called stretchers, 
 and those disposed with the ends outwards 
 are called headers. 
 
 Stri^. The fillets or rays that separate 
 the furrows of fluted columns. 
 
 Striges. An old word for the flutes of a 
 column. 
 
 Striking Distance op Electricity. 
 The distance at which the electric fluid will 
 pass away in a decided shock or spark from a 
 charged surface to any conductor held near 
 it, particularly as applied to the charged Ley- 
 den jar, where it signifies the interval at 
 wWch the shock passes, when any (ionductor 
 connected with the outer coating approaches 
 the inner or charged coating. (See Lane's 
 Medical Electrometer.) 
 
 Stringing. A name given to a particular 
 land of inlaying, and also to the material 
 
 which is inlaid. It is used chiefly around 
 tables, bird cages, Tunbridge-ware boxes, 
 dressing cases, &c., and consists of very 
 small square, triangular, or other shaped 
 pieces of wood, united by their various edges 
 with glue, so that when done the whole re- 
 sembles a very long, thin, and regular lath 
 or string of wood, of various colors, according 
 to the woods used. This is let into a channel 
 cut on the surface to be ornamented, glued 
 down and polished. The following shows one 
 among endless patterns of stringing. 
 
 String Board. In wooden stairs, aboard 
 placed next to the well-hole, and terminating 
 the ends of the steps. 
 
 String Course. A line of mouldings 
 running along the face of a building, usually 
 under the windows. 
 
 Stroke of Piston. The elevation or 
 distance which the rod of a pump or of a 
 steam engine piston rises each time, reckoning 
 from its lowest to its highest point of motion. 
 In pumps this may be of any convenient 
 length ; in the steam engine it is generally 
 about twice the diameter of the steam cylin- 
 der. Thus we speak of a cylinder of 2 feet 
 diameter and 4 feet stroke. The word stroke 
 may also apply to the height to which ham- 
 mers or stampers are raised, or in other 
 machinery where a blow is produced. 
 
 Strontia. One of the alkaline earths, of 
 which strontium is the base, occuring in a 
 crystalline form, as a carbonate in the lead 
 mines of Strontian, in Argyleshire, whence 
 its name. The pure earth is a greyish white 
 powder, infusible in the furnace, of an acrid 
 burning taste, like that of lime, but even 
 sharper. It becomes hot when moistened, 
 and slakes into a powder ; dissolves in 
 150° parts of water at 60°, and in much less 
 at the boiling point, forming an alkaline 
 solution called strontia water. It is not 
 poisonous. The only preparation of strontia 
 used in the arts is the nitrate, which mixed 
 with charcoal or gunpowder, bums with an 
 intensely crimson color; hence it is used 
 in artificial fire-works and theatrical con- 
 flagrations. 
 
 Strontia Water. (See Strontia.) 
 
 Strontites. The same as strontia. 
 
 Strontium. The supposed metallic base 
 of strontia. 
 
 Struck. An expression used to signify 
 not merely the giving a blow to any thing, 
 but also when any thing of a temporary 
 kind is taken away which has been used for 
 the support of some part of a building during 
 its erecting, as the centre of a vault, &c. ift 
 said to be struck. 
 
ST 
 
 ST 
 
 Struts. Any support or straining piece 
 placed upright or nearly so. 
 
 Strychnia. An alkaloid principle in- 
 herent in the strychnos nux vomica and 
 other plants ; it is used in medicine. 
 
 Stucco. A kind of mortar, which becomes 
 of a great hardness even under water. It 
 consists of 2 parts fresh-burnt plaster of 
 Paris and 1 of marble dust, mixed with water 
 to the consistence of cream, and poured into 
 moulds, or laid upon the surface of buildings. 
 
 Studies. In painting, a term applied to 
 those separate parts of a picture first de- 
 signed and painted unconnectedly, with a 
 view to their future introduction and compo- 
 sition in the entire work. Thus whole figures, 
 in some instances ; in others, human hands 
 or feet, animals, trees, plants, flowers; and 
 in short, any thing designed after nature, 
 receive the general denomination of studies. 
 
 Stud Work. The same as brick nogging. 
 (See Nogging.) 
 
 Stuff. This term is applied to an infinite 
 variety of things ; wood is by the carpenter 
 called stuff ; so is lime and hair by the brick- 
 layer ; plaster by the plasterer, &c. In com- 
 merce, stuff is the general name for all kinds 
 of fabrics of gold, silver, silk, hair, wool, 
 cotton, or linen, manufactured by the loom, 
 of which number are velvets, brocades, mo- 
 hair, serges, cloth, &c. The term is also 
 particularly applied to a slight woollen fabric, 
 used principally for linings and female apparel. 
 
 Stuffing Box. A small box at the top 
 of the cylinder of a steam engine, stuffed 
 with a wadding of hemp and tallow, intended 
 to keep the orifice around the piston rod 
 steam-tight. It is formed as follows : — A is 
 the piston rod. C C the top of the steam 
 cylinder, which is made prominent towards 
 the middle. D is a plate pierced so as to admit 
 the piston rod, and furnished with screws to 
 fasten it down to the prominent part of C C, 
 which is the stuffing box. B B is a groove, 
 cut in the box round the piston rod. This is 
 the part to be stuffed full of hemp, anointed 
 with tallow, and this being compressed by the 
 plate D, is packed close to the rod on all sides. 
 
 Stum. In the wine trade, the name for the 
 unfermented juice of the grape, when it has 
 been several times racked off and separated 
 from the sediment. The casks to hold this 
 liquor are well fumigated with brimstone, in 
 order to prevent fermentation, through which 
 the juice would become wine. 
 
 Sturgeon's Cast-Iron Galvanic Bat- 
 tery. This is a galvanic battery of ten cast 
 iron cylindrical vessels, and the same num- 
 ber of cylinders of amalgamated rolled zinc, 
 used with diluted sulphuric acid. The cast 
 iron vessels are 8 inches high and 3^ inches 
 diameter. The zinc cylinders are the same 
 height as the iron ones, about 2 inches 
 diameter, and open throughout. The iron 
 and zinc cylinders are attached in pairs to 
 each other, by means of a stout copper wire. 
 The zinc of one pair is placed in the iron of 
 the next, and so on throughout the series, 
 contact being prevented by discs of mill- 
 board placed in the bottom parts of the iron 
 vessels. Mr. Sturgeon speaks of this battery 
 as one of extreme power. 
 
 Sturgeon's Electro-Magnetic Bat- 
 tery, consists of a double cylinder of cop- 
 per, with a ring-shaped bottom connecting 
 the two cylinders, but leaving the outer cy- 
 linder without a bottom ; the outer cylinder 
 having one or two mercury cups soldered to 
 it. This is shown at B. A cylinder of sheet 
 zinc, without a bottom, is made of a size in- 
 termediate between the two copper cylinders. 
 This also has a mercury cup attached, as is 
 seen at C. When the zinc cylinder is placed 
 witliin those of copper, it has the appearance 
 of A. The zinc is prevented touching the 
 copper either by a string tied round it, or 
 three pieces of cork fastened to the outside 
 of the lower end of the zinc cylinder. It is 
 charged with sulphuric acid and water. 
 
 Sturgeon's Electro-Magnetic Coil 
 Machine. This instrument is for the same 
 purpose, and almost of the same structure, 
 as that already described under Bachhoffner : 
 the chief difference being in the method of 
 breaking and renewing contact. The gene- 
 ral principle and construction will therefore 
 be easily understood ; Z and C being the two 
 wires connected with the battery, and con- 
 sequently with the primary coil. L H are 
 the ends of the secondary coil. A the foot- 
 board. F an upright pillar with an open 
 glass phial at top, partly filled with mercury. 
 B a cam or break, connected with a small 
 pulley behind, over which a string passes to 
 the larger wheel C. D is a wire, connected 
 with the upright adjoining, and with a socket 
 or a hinge at one end, holding the second 
 
ST 
 
 ST 
 
 wire E. G are the coils. The parts D E 
 &nd F being made part of the circuit for the 
 fluid passing jdong the primary coil, and one 
 end of the wire dipping into the mercury at 
 F, the circuit is complete when the cam B 
 lies flat, but when turned partly round, as in 
 the figure, it lifts up this wire so that its 
 point is removed out of the mercury, and 
 consequently the contact is broken, and an 
 interruption in the continuity takes place. 
 This action and cessation of action is repeated 
 with great rapidity at the revolution of B. 
 
 ^gk^^^g^^^ 
 
 Sturgeon's Electro-Magnetic En- 
 gine. Contrived for the purpose of moving 
 various pieces of machinery, boats, carriages, 
 &c. A is the base board. B B two wooden 
 uprights, supporting the cross bar C C, which 
 passes diagonally from corner to corner across 
 the board. In this cross bar are inserted 
 two smaller pillars, which also carry a cross 
 piece. In the centre of the engine is a ver- 
 tical shaft, which works freely in two me- 
 tallic collars ; one of which is in the centre 
 of the base board, the other in the centre of 
 the cross piece C C. Above the base board 
 are two circular channels, marked O ; one 
 placed above the other. Through the centre 
 of these channels the shaft passes, and is 
 fixed to them. Lower down the shaft passes 
 through the centre of another cross piece; 
 also supported on two pillars. On this cross 
 piece, and concentric with the shaft, are four 
 quadrantal arcs of metal, sepai-ated from each 
 other by four narrow openings. Near the 
 top of the shaft is a straight, transverse, 
 compound magnet, N, about 18 inches long. 
 Near the bottom of the shaft is a second 
 similar magnet, marked N S ; its poles being 
 reversed to those of the former. In a circle 
 on the base board are the four bars of soft 
 iron 1 1 1 I, each wound with six coils of co- 
 vered bell wire ; the similar ends of the coils 
 are united to a stout wire. Thus, although 
 there are six coils, yet two wires only proceed 
 from each, or eight wires in all ; four of 
 these are soldered to the quadrantal plates, 
 
 each to each. The other four stout wires, 
 which proceed from the top of the coils, ter- 
 minate by a proper connection with the chan- 
 nels on the spindle, which are filled with 
 mercury. The channels are connected with 
 mercury cups, in which the wires from a bat- 
 tery are placed ; one battery at each end oi 
 the lowest cross piece. The connections 
 being properly made, the iron bars or cylin- 
 ders I 1 1 1, become magnetic in succession ; 
 and by the joint attractive and repulsive 
 forces of the permanent magnets N and N S, 
 and the temporary magnets 1 1 1 1, the for- 
 mer with the shaft and appendages are pulled 
 and driven round. The fly F is intended 
 merely to steady the motion, and the endless 
 screw and wheel W shows one, among nume- 
 rous other, methods of applying the power. 
 
 Sturgeon'sElectro-Magnetic Globe. 
 This apparatus was intended to show the 
 effect of an electric current, passing round 
 the equatorial regions of tlie earth, occa- 
 sioning the effects of magnetism. Suppose 
 a globe of pasteboard to contain a strong 
 magnet, coincident in position with the mag- 
 netic poles or ^iis of the earth ; a delicate 
 dipping needle suspended over this in various 
 parts would be affected in the same way as 
 ordinary needles are by terrestrial magnetism. 
 
ST 
 
 su 
 
 Now take away the central magnet, insert a 
 bar of iron, and wind covered copper wire 
 in a coil around the equator, having the two 
 ends connected with the poles of a galvanic 
 battery, so that a current of electricity runs 
 along the wire. It will now be found that 
 the same magnetic effect will be produced as 
 in the former instance. (See Barlow.) 
 
 Sturgeon's Gunpowder Apparatus. 
 (See Gunpowder.) 
 
 Sturgeon's Magnetometer. The same 
 as the oscillatory plate claimed by M. Arago. 
 (See Arago.) 
 
 Sturgeon's Parallelogram, is repre- 
 sented below. It consists of a flat paral- 
 lelogram of copper wire, bent so that one end 
 dips into a mercury cup on the stand ; and 
 after passing along the four sides, a part is 
 tied with silk to the former end, (so how- 
 ever that the silk should be between them, 
 that they may not touch ;) the wire is then 
 brought straight downwards, and terminates 
 in the mercury cup near N, the former 
 mercury cup A being connected with the 
 cup lower down the stand, near P. When 
 the wires N and P are connected with a 
 charged electro-magnetic or galvanic battery, 
 the fluid will pass along the wire, and giving 
 the one side a north, and the other a south 
 polarity, the parallelogram will arrange itself 
 east and west. 
 
 Sturgeon's Revolving Crown. Thi 
 differs in principle in no respect whateve 
 from the revolving wire, 
 though it does some- 
 what in the mode of its 
 suspension. The upper 
 pole of the magnet has 
 a cap which fits upon 
 it, and a wire proceeds 
 upwards from the cap, 
 upon which a point 
 underneath the crown 
 of wires rests as on a 
 pivot. The mercury 
 cup A is soldered on 
 to the top of the crown 
 D. The lower end of the crown is a cir- 
 
 cular rim of very thin brasS;"1vifilcfi'" ffl^' 
 into the channel for mercury, made in the 
 disc C. The cup B is connected with this 
 channel of mercury, or it may be formed 
 and connected as in the last apparatus ; the 
 present is, however, the usual form, when a 
 steel magnet is used. When there are two 
 crowns on separate magnets, or upon the 
 different poles of the same magnet, it forms 
 a most beautiful experiment. 
 
 Sturgeon's Revolving Magnet. There 
 are two distinct instruments known by this 
 name, though one of them is sometimes 
 called Watkins's revolving magnet. They 
 are as follows : — Fig. 1 shows a straight bar 
 magnet A, poised between two pivots, one 
 at each end. The upper point is adjusted 
 by a screw ; the lower rests on a piece of 
 brass in the centre of the foot-board. Around 
 this brass piece is a circular cup holding 
 mercury, and connected by a wire with the 
 mercury cup on the side. Half way up t|je 
 stand is a platform, and a second circular 
 cup also for mercury, the centre being hollow 
 that the magnet may pass freely through it ; 
 this is also connected to a cup at the side. 
 Two brass wires screwed into the magnet, 
 one above each cup, dips into the mercury 
 of them. If now an electrical current be 
 sent from B to C, it will pass along the 
 lower half of the magnet, and at the same 
 time occasion the magnet to revolve on its 
 axis. 
 
 The second instrument is to show the 
 revolution of a magnet around a wire which 
 conveys a current of the fluid. A B is the 
 wire. It commences in the mercury cup C, 
 and passes down to the brass cup D, which 
 holds a little mercury, and leads to a wire E, 
 that dips into the mercury channel F. The 
 magnet is bent, as represented, D being 
 fastened to it. It rests merely for support 
 however upon the wire G, and has a ring H 
 clasping G to keep the magnet steady in its 
 revolution. When a current of electricity 
 is made to pass from C to F, it passes near 
 to one pole of the magnet and causes its 
 revolution ai-ound A B. 
 
ST 
 
 ST 
 
 ^-.uwixiu electrical apparatus of the same 
 nature as the spiral tube. The figures show 
 the front and side-view of the instrument. 
 A A is the foot-board. B B an upright 
 wooden support. C a staple to form with 
 the top of B, a support for the axle, and 
 small pulley P. A cord passes from this to 
 the multiplying wheel W. S is a glass stem, 
 upon the top of which is the wire ring O O. 
 The axis is terminated by a brass ball, on 
 two opposite sides of which are short spiral 
 tubes — these are put in motion by the wheel, 
 cord, and pulley. If, while the spiral re- 
 volves, sparks be taken from the machine 
 by the ball shown on the side of O, they 
 will pass down the spiral and produce a most 
 beautiful effect. 
 
 Sturgeon's Revolving Wheel. This 
 electro-magnetic instrument will be best 
 understood by reference to Barlow's Spur 
 Wheel, Mr. Sturgeon having discovered that 
 a whole disc is capable of a similar revolution, 
 when placed in like manner between the 
 poles of a magnet, and subjected to the 
 influence of an electrical current passing 
 through it. 
 
 Sturgeon's Revolving Wire. The 
 necessity of employing very powerful magnets 
 in all electro -magnetic experiments, induced 
 Mr. Sturgeon to substitute the temporary 
 electro-magnet for the ordinary steel magnet 
 in numerous experiments, particularly to 
 
 produce rotations of wires, &c., as follows:— 
 A bar, or else a hollow cylinder of iron, 
 (the latter is to be preferred,) is placed 
 upright in a wooden foot ; a copper wire, 
 covered with silk or cotton, is coiled round 
 the bar, the lower end being furnished with 
 a mercury cup, the upper end passing into a 
 circular channel, which is cut on the upper 
 side of a round disc, through the centre of 
 which the iron bar passes. The disc supports 
 a wire ; on the top of the wire is a mercury 
 cup ; under the mercury cup a hook or ring; 
 and to the ring is suspended a wire, of suffi- 
 cient length to dip into the channel. When 
 a little mercury is put into the channel for 
 the end of the wire to dip into, also a little 
 mercury put into the two cups, and the two 
 poles of a battery be united to the cups, the 
 current will make the iron bar into a tempo- 
 rary magnet ; and the current passing at the 
 same time along the wire, it will rotate 
 around the pole of the magnet in one di- 
 rection or the other, according to the passage 
 of the electrical fluid, whether it be upwards 
 or downwards. 
 
 Sturgeon's Semi-Spiral Disc. This is 
 a galvanic apparatus, showing the light given 
 out by various metals when deflagrated by 
 the galvanic fluid. It consists of a brass 
 wheel, set upright on a wooden stand. Upon 
 the face of this wheel are sixteen studs, rising 
 above the surface half an inch or more. These 
 are set in two semi-spiral rows, and are 
 formed of eight different metals in each semi- 
 spiral. The wheel is connected to one pole 
 of a strong galvanic battery by a wire behind 
 it. In the centre is inserted a piece of ivory, 
 and through this an axis of brass, connected 
 with a small handle and mercury cup behind 
 the wheel, and having on the front end an 
 arm of brass, with eight springs on the under 
 side, so placed as to touch the studs during 
 the revolution of the arm. When the poles 
 of a battery are connected with the mercury 
 cups of the disc and of the arm, and the 
 latter turned round, connection with one pole 
 
ST 
 
 SU 
 
 and the other will take place, whenever the 
 springs touch the metal studs, and not at 
 other times ; a series of sparks will therefore 
 ensue, and the metals being diiferent in na- 
 ture, the color of the spark from each will 
 vary from the rest. 
 
 Sturgeon's Spiral Card. If a piece of 
 wire be bent in the form of a flat spiral, as 
 shown in the figure, and this be suspended in 
 mercury cups at the top and bottom, the 
 mercury cups themselves bearing wires from 
 the two poles of an electro -magnetic battery, 
 as is seen at A P, B N, (the whole distance 
 between A and P, and also B N, being me- 
 tallic,) a current of electricity sent from 
 P to N will of necessity pass through the 
 coil, and changing it into a temporary mag- 
 net, it will at the same time obtain polarity, 
 and turn in the direction E and W ; one side 
 of the wire having a north polarity, and the 
 other side a south polarity. The instrument 
 is best made with a card, upon which the 
 wire may be shown. The straight part of it 
 from the centre downwards, passing through 
 the middle and at the back of the card. 
 
 Style. In all the arts, the union of all 
 those several parts which unite in the con- 
 ception, composition, and execution of a work 
 of art. The word is applied to painting, 
 poetry, sculpture, architecture, &c. A style 
 is also any thing with a sharp point, and of a I 
 small size, as a graver, an etching needle, &c. ■ 
 
 Style. In chronology, a particular man- 
 ner of counting time, as the new style, the 
 old style. The old style is the Jnlian manner 
 of computing, as instituted by Julius Caesar, 
 in which the mean year consists of SGS?^ days. 
 New style is the Gregorean manner of com- 
 putation, instituted by Pope Gregory XIII. 
 in the year 1582, and is used in most coun- 
 tries of Europe in the present day. In this 
 the year consists of 365^ days, but it differs 
 from the old style inasmuch as this quantity 
 being rather too much to agree with the solar 
 year, three days are omitted in 400 years ; thus 
 reducing the year so as very nearly to agree 
 with the earth's revolution round the sun. 
 
 Style. In architecture, is any particular 
 fashion or general method of building, not 
 confined in the relative proportion of parts to 
 any set of rules or scientific regulations, 
 distinguished therefore from order. Thus 
 each coimtry, even the most savage, has its 
 peculiar style of building. The different 
 wants of succeeding ages of civilization also 
 required alterations of style, while improved 
 taste will improve style also. Thus we speak 
 of the different styles of Gothic architecture, 
 distinguishing them as the Anglo-Saxon^ 
 Norman, the early English, the decorated, 
 the perpendicular, and the Flamnioyant. 
 So also speaking of different countries and 
 times we say, the Moorish style, the Chinese, 
 Persian, Turkish, Hindoo, Venetian, Eliza- 
 bethan, Anglo-Greek, &c. 
 
 Stylobate. a basement of brick-work, 
 or of masonry beneath columns. 
 
 Sub-contrary Position. In geometry, 
 is when two similar triangles A E D, A E C, 
 are so placed as to have one common angle A 
 at the vertex, and yet their bases not pa- 
 rellel, consequently the angle at the bases 
 are equal, but on contrary sides. 
 
 If an oblique cone with a circular base, 
 whose diameter is B C, be so cut by a trans- 
 verse plane, as to make in the section ABC, 
 
su 
 
 tiirough the vertex A, the angle E = the 
 angle B and D = C ; then the cone is said to 
 be cut by the transverse plane in a sub-con- 
 trary position to the base B C , and in this 
 case the section whose diameter is D E is 
 always similar to B C. 
 
 SuBDUCTioN. (See Subtraction.) 
 
 SUBDUPLICATE RaTIO OF TwO QUAN- 
 TITIES, is the ratio of their square roots ; 
 as Va : -v/b is the subduplicate ratio of a : b. 
 
 Suberic Acid. An acid obtained from 
 cork ; suber being the specific name of the 
 cork tree. 
 
 Sublimate. Any solid matter resulting 
 from sublimation. 
 
 Sublimation. A process by which vola- 
 tile particles are raised by heat, and condensed 
 into a crystalline mass. Zinc when melted 
 and burned in a hot fire becomes sublimed, 
 or flies off in a copious white powder, which 
 is an example of sublimation. 
 
 Sublime Geometry. The geometry of 
 curve lines. 
 
 Submultiple. The same as aliquot or 
 equal part; thus 3 is the submultiple of 21. 
 That is, when 3 is multiplied by another num- 
 ber it will make 21. 2, 3, 4, and 6, are all 
 Bubmultiples of 12. 
 
 Subnormal, or Subperpendicular. 
 The distance upon the axis between the foot 
 of the ordinate, and a perpendicular to the 
 curve or its tangent. In all curves the sub- 
 normal is the third proportional to the sub- 
 tangent and the ordinate, and in the parabola 
 it is a constant quantity. 
 
 Subsalt. a salt having an excess of base 
 beyond what is requisite for saturating the 
 acid, as supersalt is one with an excess of 
 the acid. Thus sulphate of potass is the 
 neutral compound of sulphuric acid and 
 potass ; subsulphate of potass, a compound 
 of the same ingredients, in which there is an 
 excess of base ; supersulphate of potass, a 
 compound of the same acid and the same 
 base, in which there is an excess of acid. 
 
 Substantive Colors. In dyeing, are 
 Buch colors as unite immediately with the 
 stuflF, without the necessity of using a mor- 
 dant. 
 
 Substitution. In algebra, is the putting 
 or using one quantity for another to which 
 it is equal. 
 
 Substraction. (See Subtraction.) 
 
 Substyle. In dialling, the right line on 
 which the style or gnomon is fixed. 
 
 Subtense of an Arc or Angle, is the 
 line by which it is subtended or cut off. 
 
 Subtraction. One of the fundamental 
 rules of arithmetic, and by which numbers 
 or quantities are taken from each other, and 
 their difference ascertained. It is divided 
 into simple subtraction, or that which relates 
 to whole numbers of one denomination only ; 
 and compound subtraction, where the differ- 
 
 ences of compound amounts of monies, 
 weights, or measures, are ascertained. 
 
 Subtangent. The line that determines 
 the intersection of a tangent with the axis, 
 or that determines the point wherein the 
 tangent cuts the axis prolonged, as T B in 
 the annexed figure. 
 
 Subtrahend. In subtraction, is the 
 smaller number, or that which is to be taken 
 from the other, which other is called the 
 minuend, that is, the number to be di- 
 minished. 
 
 Subtriple. One number or quantity 
 which is the tliird part of another ; and sub' 
 triple ratio is the ratio of 1 to 3. 
 
 SuBTRiPLicATE Ratio, is the ratio of 
 the cube root ; thus ^ Va to ^ Vb is the 
 subtriplicate ratio of a to b. 
 
 Succession of Signs. In astronomy, 
 called also consequentia, is the same order 
 as that in which the sun enters the signs of 
 the zodiac and passes through them, as 
 Aries, Taurus, Gemini, Cancer, &c. When 
 a planet's motion is according to this order, 
 it is said to be direct ; but when it moves in 
 a contrary way, it is said to be retrograde. 
 
 Succinic Acid. Acid of Amber. Salt of 
 Amber. Obtained by distilling coarsely 
 pounded amber in a retort by itself, with a heat 
 gradually raised, or mixed with one-twelfth 
 of its weight of sulphuric acid, diluted with 
 half its weight of water. It is afterwards 
 purified. Its salts are called succinates, one 
 of which, the succinate of ammonia, is an 
 excellent test for iron in solution. 
 
 SuccuLA. In mechanics, a bare axis or 
 cylinder, with staves in it to move it round, 
 but without any periphery or drum. 
 
 Suction. The action of sucking is per- 
 formed by the child's making a vacuum in its 
 mouth, which exhausts the air from the pores 
 of the nipple, and the milk is consequently 
 ejected from the breast by the unresisted 
 elasticity of the air within. The naising of 
 liquids through a tube, by means of a piston 
 which lifts and sustains the weight of the 
 atmosphere from that part of the well which 
 is covered with the tube, leaving it to press 
 on the other parts of the surface is also 
 metaphorically termed suction. 
 
 Suction Pipe. The lower pipe of a pump, 
 that which proceeds to the well. 
 
 Suction Pump. This is the common 
 household pump, called a suction pump from 
 the old belief that it derived its action from 
 a principle of suction. Suppose A to be a 
 
su 
 
 su 
 
 pipe, leading to the well of water. G tLe 
 pump barrel, part of which is removed to 
 show the valves. E is the pump handle. F 
 a spout, to throw off the water 
 raised. G the bucket or valve 
 belonging to the piston which 
 is at the end of the pump rod. 
 H the lower valve or suction 
 valve. When E is drawn up, 
 it will, at the same time, draw 
 up G, and occasion a vacuum 
 ar empty cavity between G 
 and H. The water below H 
 will immediately rush up and 
 fill the cavity. It was formerly 
 said it was sucked up ; its 
 ascent is now known to arise 
 from the pressure of the at- 
 mosphere upon the water in 
 the well, forcing up the water 
 until it rises in the pipe to a 
 height of 32 feet, a column of water of that 
 height weighing 15 lbs. per square inch of 
 surtace, which is equal to the weight of the 
 atmosphere. When E is entirely drawn up, 
 the water will have filled the space between 
 the valves. Upon pressing E down again 
 the water cannot return, because the valve H 
 closes ; instead of which the valve G opens, 
 and the whole of the bucket descends through 
 the water. When E is again drawn up, G 
 shuts, and the water above G is lifted up, 
 and flows away ; at the same time H opens, 
 and a fresh supply of water fills the lower 
 part of the pump barrel as at first. 
 
 Sugar. A sweet constituent of animal and 
 vegetable products. There are two principal 
 classes of sugars ; one derived from the juice 
 of the sugar cane, (Saccharum oj^cinale,) 
 the beet root, and the maple. This is com- 
 monly known as sugar, divided into treacle^ 
 when liquid ; foots, when partly crystaUized ; 
 Muscovado or raw sugar, when crystallized, 
 but still impure, and more or less colored ; 
 refined or/ofl/"sugar, when purified and hastily 
 congealed into small crystals ; sugar candy, 
 when set aside to ciystallize very gradually. 
 The second class of sugars contains such as 
 are derived from fruits, as from the fig, the 
 grape, dates, &c. This does not crystallize, 
 and has scarcely more than half the sweetening 
 power of the former. It is also produced 
 artificially, by treating starch with sulphuric 
 acid, and boiling them together. Chemists 
 enumerate other kinds of sugar, as the sugar 
 of milk, diabetes sugar, of manna, of certain 
 mushrooms, of liquorice root, &c. 
 
 Sugar of Lead. Acetate of lead. 
 
 Sulphates. Saline compounds of sul- 
 phuric acid, with oxidized bases. The mi- 
 nutest quantity of them present, in any so- 
 lution, may be detected by the precipitate, 
 insoluble in nitric or hydrochloric acid, which 
 they afford with the nitrate or chloride of 
 
 barytes. The sulphates are mostly insoluble 
 in alcohol. 
 
 Sulphate of Alumina and Potass. 
 The same as alum. 
 
 Sulphate of BarY^ta. A mineral, called 
 also heavy spar. 
 
 Sulphate of Copper. Blue vitriol ; 
 blue stone ; Roman vitriol. 
 
 Sulphate of Iron. Green vitriol, or cop- 
 peras. This is the basis of all black inks and 
 black dyes. When calcined, it forms jewel- 
 ler's rouge, crocus of Mars or colcothar of 
 vitriol ; used for polishing steel and other 
 goods, and to apply to razor strops. 
 
 Sulphate of Lime. Gypsum or plaister 
 of Paris. (See Plaister.) 
 
 Sulphate of Magnesia. Epsom salts 
 or hair salt of old writers. 
 
 Sulphate of Manganese is much used 
 by the calico printer. 
 
 Sulphate of Soda. Glauber's salts. 
 
 SuLPHATK of Zinc. White vitriol. This 
 is used in drying lotions, in preparing drying 
 oils for varnishes, and in the reserve or resist 
 pastes of the calico printer. 
 
 SuLPHATic Ether. Sulphate of hydro- 
 carbon ; oil of wine ; heavy oil of wine. 
 
 Sulphites. A class of salts, consisting of 
 sulphurous acid, combined with the various 
 bases. 
 
 Sulphoadipic Acid. When olive oil is 
 carefully mixed with sulphuric acid, so as to 
 avoid the heating of the mixture, a thick 
 brown compound is formed, from which water 
 separates all the oil in an altered state, and 
 retriins in solution a peculiar compound of 
 hyposulphuric acid and organic matter, which 
 Chevreul has termed sulphoadipic acid. 
 
 Sulphoctanic Acid. Hydrosulpho- 
 CYANic Acid. Sulphuretted Chyazic 
 Acid. Sulphuro-prussic Acid. A triple 
 compound of sulphur, cyanogen, and hydro- 
 gen. It is thus procured : — Mix equal 
 weights of flowers of sulphur and powdered 
 ferrocyanuret of potassium, and keep the 
 mixture melted in a flask for half an hour ; 
 when cold reduce the mass to powder, and 
 digest it in water. Filter the solution, and 
 add a suflftciency of liquid potassa to throw 
 down the iron held in solution. The liquid 
 thus obtained is a solution of the sulpho- 
 cyanuret of potassium, from which liquid 
 sulphyocyanic acid may be obtained by dis- 
 tillation with phosphoric or sulphuric acid. 
 It is of a pinkish hue, with an acetic odour, 
 and is characterized by the peculiar blood-red 
 color, which it produces when mixed with 
 persulphate of permuriate of iron. 
 
 Sulphocyanic Ether. By distilling a 
 mixture of 1 part of sulphocyanuret of potas- 
 sium, 2 of sulphuric acid, and 3 of anhy- 
 drous alcohol, Leibig obtained a compound 
 consisting apparently of sulphuret of cyanogen 
 and etherine. 
 
 52 
 
su 
 
 su 
 
 SULPHOGYANURET OF POTASSIUM. (See 
 
 Sulphocyanic Acid.) 
 
 SuLPHOCYANURETS. Compounds of sul- 
 phuretted hydrogen and cyanogen. 
 
 SuLPHOMETHYLic AciD. An acid sab- 
 stance, obtained by the decomposition of the 
 sulphate of methyline by boiling water ; this 
 liquid resolving it immediately into regene- 
 rated methyline and sulphomethylic acid. 
 
 SULPHONAPHTHALIC AciD. SuLPHO- 
 
 NAPHTHALiN. A Combination of naphtha- 
 line and sulphuric acid. 
 
 SuLPHOviNic Acid. The name given by 
 Vogel to an acid or class of acids, which may 
 be obtained by digesting alcohol and sul- 
 phuric acid together with heat. It is probable 
 that this acid is merely the hyposulphuric, 
 combined with a peculiar oily matter. 
 
 SuLPHOSELS, or SuLPHOSALTS, is a name 
 given to a double sulphuret, prepared as 
 follows : — Dissolve a salt, consisting of an 
 oxide and an acid, (an oxisalt,) in a very 
 small quantity of water, and pass through 
 the solution a stream of sulphuretted hydro- 
 gen, till the salt be entirely decomposed. In 
 this operation the oxisel is transformed into 
 a sulphosel, by the action of the compound 
 gas, while its hydrogen forms water with the 
 oxygen of the saline base. This process is 
 applicable only to the metallic salts, and 
 among these not to the nitrates, carbonates, 
 or phosphates. 
 
 SuLPHosiNAPic Acid. An acid found in 
 the seeds of mustard, radish, and turnip, and 
 some other cruciferous plants ; in the roots 
 of horse-radish, &c. 
 
 Sulphur. Brimstone ; a simple combus- 
 tible, solid, non-metallic, brittle, hard, crys- 
 taUized, yellow substance ; the produce chiefly 
 of volcanic countries. It burns with a blue 
 flame and pungent suffocating odour ; melts 
 at a heat of 226° ; becomes thick and dark 
 colored by an increase of heat, and takes fire 
 at 569°. When a lump of it is rubbed, it 
 becomes negatively electrical. It unites readily 
 with oxygen, metals, &c. ; forming sulphurets 
 m the latter case and acids in the former. 
 Sulphur unites with oxygen in four propor- 
 tions, forming acid products ; the constituents 
 of which are as follows : — 
 
 Sulp. l,ox, 1 atom, forms hyposulphurous acid 
 Sulphur 1 .oxygen 2 atoms, forms sulphurous acid. 
 Sul. 1, ox. 2i, atoms, forms hyposulphuric acid. 
 Sulphur I, ox. 3 atoms, forms sulphuric acid. 
 
 Sulphur is found in commerce of various 
 forms. Massive or native sulphur, as found 
 in the volcanic countries. Roll sulphur, 
 made usually from the sulphurets of copper 
 or iron, and cast in the shape of rolls or 
 cylinders. Sublimed sulphur or flowers of 
 tulphur, in the state of a fine powder, and as 
 precipitated from the alkaline sulphuret by 
 an acid, called then milk of sulphur, or pre- 
 cipitated sulphur. 
 
 Sulphur Cone. An electrical experiment 
 and apparatus to prove the effect of sepa- 
 ration of the contact of 
 two bodies, occasioning 
 them to show signs of 
 electricity. Take a large 
 wine glass, paste a small 
 piece of tin-foil over the 
 lower part of the glass, 
 twist a wire round it, and 
 sufisr the end to project, 
 in order to support a pair 
 of pith balls. Pour melted 
 sulphur into the ^lass, 
 and insert a glass rod into 
 the sulphiir while yet 
 liquid. In the present state no electrical 
 effect will be perceived, but when the sulphur 
 cone is lifted out by the glass rod, the pith 
 balls will immediately diverge, collapsing 
 again when the sulphur is replaced, and 
 thus the divergence and collapse may be re- 
 newed at pleasure for a long period of time. 
 Sulphur Vivum. The impure sulphur 
 remaining in the alembic after sulphur has 
 been sublimed from the crude state. 
 
 SuLPHURATioN. The act of bleaching 
 any thing by subjecting it to the fumes of 
 burning sulphur shut up with it in a box or 
 close room. This is done as a means of 
 bleaching the article. 
 
 Sulphureous. Any thing containing or 
 appearing by the senses to contain sulphur. 
 
 Sulphuret. A combination of sulphur 
 with a metal or other simple body, or with 
 an earth or alkali. 
 
 Sulphuretted Alcohol. A solution of 
 sulphur in alcohol ; obtained by boiling them 
 together, or preferably by suffering the fumes 
 of boiling alcohol to unite with the fumes ot 
 burning sulphur in a close vessel. 
 
 Sulphuretted Chyazic Acid. (See 
 Sulpho-Cyanic Acid.) 
 
 Sulphuretted Hydrogen. A gaseous 
 compound of hydrogen and sulphur ; formed 
 by pouring a little sulphuric or muriatic acid 
 upon the black sulphuret of iron or antimony 
 in a retort. It takes fire when a lighted 
 taper is brought in contact with it, and 
 burns with a pale blue flame, depositing 
 sulphur. Its smell is extremely fetid, re- 
 sembling that of rotten eggs. It reddens 
 vegetable blues. It is absorbable by water 
 and of all the gases — sulphuretted hydrogen 
 is perhaps the most deleterious gas to animal 
 life. A goldfinch plunged into air which 
 contained only a fifteen hundredth part o* 
 its volumn, perished instantaneously. A dog 
 of middle size is destroyed in air containing 
 ■g^ ; and a horse would fall a victim in an 
 atmosphere containing ^^ part. Sulphu- 
 retted hydrogen combines with an equal 
 volumn of ammonia, and unites to alkalis 
 and oxydes, so that it has all the characters 
 
su 
 
 su 
 
 of an acid. These compounds are called 
 hydro-sulphurets. 
 
 Sulphuretted Spirit. A compound of 
 sulphuretted hydrogen and ammonia. 
 
 Sulphuretted Sulphites. The same as 
 the hypo -sulphurous acid. 
 
 Sulphuric Acid. Oil of Vitriol. A 
 compound of sulphur and oxygen, in the 
 proportion of 1 atom of the former to 3 of 
 oxygen. It is almost universally procured 
 in this country by the combustion of a mix- 
 ture of about 8 parts of sulyhur and 1 of 
 nitre. The fumes arising pass into a leaden 
 chamber, the floor of which is covered with 
 water ; this absorbs the acid fumes, and 
 when it heis thus acquired a certain specific 
 gravity it is drawn off, and concentrated by 
 boiling, the water being lighter than the 
 acid flies off in vapour. Sulphuric acid 
 is intensely acrid and caustic, has a soapy 
 feel, is extremely sour, and has so strong an 
 attraction for water that their quick union 
 produces very considerable heat. It possesses 
 intense chemical powers, it displaces the 
 greater number of acids from their combi- 
 nations, and chars most animal and vegetable 
 substances. 
 
 Sulphuric Acid, German. When the 
 sulphate of iron is calcined, till it falls down 
 in a white powder, then put into an earthen 
 or glass retort, and gradually exposed to a 
 red heat, a dark colored acid liquor distill 
 over, of a specific gravity of about 1-89, 
 which has been called Nordhauson or German 
 sulphuric acid. This brown fuming acid is 
 in request as a ready and perfect solvent of 
 indigo. It smokes when exposed to the 
 air. 
 
 Sulphuric Acid, Glacial or Anhydrous. 
 When sulphuric acid was procured by the 
 distillation of green vitriol, it was frequently 
 observed, that a portion concreted into a 
 white mass of radiated crystals. This has 
 been called glacial ox fuming sulphuric acid, 
 and is considered as the pure or anhydrous 
 acid. 
 
 Sulphurous Acid. An acid whose con- 
 stituents are 1 atom of sulphur and 2 of oxy- 
 gen. It was first examined by Stahl, who 
 called it phloginticated sulphuric acid. It 
 may be procured by burning sulphur in 
 oxygen gas. It is a gaseous body, rapidly 
 absorbed by water. Its specific gravity, as 
 compared to hydrogen, is as 32 to 1, or more 
 than twice the weight of atmospheric air. It 
 is easily condensable by cold and pressure 
 into a liquid. It has a suffocating odour, 
 extinguishes the light of a taper, and the life 
 of an animal. 
 
 Sulphuric Ether. An ether procured 
 either by distilling a mixture of sulphuric 
 acid in alcohol, or by suffiering alcohol 
 gradually to dribble into the heated, and 
 somewhat dilnted acid. 
 
 Sum. The aggregate of any two or mor« 
 quantities ; formed by adding them together. 
 
 Sumach. The name of a shrub, (Rhus 
 coriariaj which grows natureilly in Spain 
 and other places ; the wood of which dried 
 and pounded is used for the purposes of 
 dyeing and tanning. In the former art it 
 produces, when used alone, a fawn color, 
 when with the acetate of alumina as a mor- 
 dant, a good yellow. 
 
 Summer. One of the seasons or quarters 
 of the year, beginning about the 21st of June 
 and ending on the 22nd of September, 
 Summer is also often used to denote one half 
 of the year : viz. the time in which the sun 
 passes through the northern signs, namely 
 from about the 21st of March to the 22nd of 
 September, exceeding the winter, or the time 
 in which he passes through the southern signs 
 by about seven days. 
 
 Sun, The. In astronomy, the great source 
 of light and heat to the solar system, about 
 which as a centre the several planets perform 
 their revolutions, and to the influence of 
 which, combined with their sidereal and 
 diurnal revolution, they owe the successive 
 alternations of summer and winter, day and 
 night. The sun is the largest of all the hea- 
 venly bodies ; his diameter is 111*454 times 
 that of the mean diameter of the earth, whence 
 his volumn is 1384472 times greater than 
 that of the earth, but its density being only- 
 one quarter as great, we may consider his mass 
 to be 337086 times that of the earth. He is 
 surrounded by an atmosphere of great extent, 
 and is frequently obscured by spots, some of 
 which have been observed so large as to 
 exceed the earth five or six times in diameter. 
 The observation of these spots shows that the 
 Sim turns on his axis in 25^ days. The sun, 
 together with the planets, moves round the 
 common centre of gravity of the system, 
 which centre is nearly in the centre of the sun, 
 and this motion changes the orbits of the 
 planets into epicycloids. The sun also ap- 
 pears to have a particular motion, which 
 carries our system towards the constellation 
 Hercules. 
 
 Sun and Planet Wheel. A contrivance 
 
su 
 
 su 
 
 dfthe celebrated James Watt, for superseding 
 the crank in the steam engine. Suppose A 
 to be a cogged wheel, attached to the shaft of 
 the fly wheel B B ; and that another wheel C, 
 with cogs similar to those upon A, be sus- 
 pended from the end of the beam D, which 
 is connected with the working beam of the 
 steam engine.- As D ascends and descends, 
 it will necessarily work the wheel A, putting 
 that and all connected with it in motion ; at 
 the same time it will travel round A, in the 
 same manner as a planet travels round the 
 sun ; A rod B, (not shown in the cut,) con- 
 nects the axes of the wheels A and C. 
 
 Sunday Letter. (See Dominical Letter.) 
 
 Sun Dial. (See Dial.) 
 
 Superficial. Shallow ; relating to sur- 
 face only. 
 
 Superficial Content of any Thing. 
 The number of square inches, feet, &c., con- 
 tained on its surface. 
 
 Superficial Measure. The same as 
 square or land measure. 
 
 Superficies. The outside or exterior sur- 
 face of any body. This is considered as of 
 two dimensions ; viz. length and breadth, but 
 "without thickness, and therefore forms no 
 part of the substance, or solid content of the 
 Dody. The boundaries or extremities of a 
 superficies are lines, and it is said to be a 
 rectilinear or curvilinear superficies, ac- 
 cording as the bounding lines are curved or 
 straight. Superficies are further divided in 
 plane ox flat, concave and convex. 
 
 Superparticular Ratio. An obsolete 
 term for a ratio when the two terms differ 
 only by units. 
 
 Superpartient Ratio. Also obsolete, 
 is a ratio where the terms differ by more than 
 unity, but the greater is less than double the 
 other. 
 
 Supers ALT. (See Suhsalt.) 
 
 Superstructure. Any thing built upon 
 a foundation previously made to receive it. 
 
 Supple. A quality opposed to hardness or 
 inflexibility. 
 
 Supplement of an Arc In trigono- 
 metry, is what it wants of 180". 
 
 Supporters of Combustion. The only 
 true and perfect supporter of combustion is 
 oxygen, though the gases chlorine and nitrous 
 oxyde, also iodine and bromine, will in some 
 cases act as such. 
 
 SuRBASE. A cornice or series of mould- 
 ings on the top of the base of a pedestal, 
 podium, &c. 
 
 Surd. In arithmetic and algebra, denotes 
 the root of any quantity, when that quantity 
 is not a complete power of the dimension 
 required: thus V2, ^ V^, *V7, are surds 
 or irrational quantities. Surds are either 
 simple or compound. A simple surd is that 
 which consists of only one term, as */2, 
 3 Ve, &c. A compound surd is that which 
 
 consists of two or more terms or radicals ; 
 thus VS + a/2 arc compound. These last, 
 when consisting of only two terms, are also 
 called binomial. 
 
 Surface. The same as superficies ; the 
 former word being generally used on orcKnary 
 occasions ; the other when treating of mathe- 
 matical subjects. 
 
 Surface Chuck. A chuck used for the 
 purpose of holding any flat material, while 
 the surface of it is turned flat and even ; for 
 example, the backs of stereotype plates. The 
 chuck is formed of course with a screw which 
 fits the mandril of the lathe ; the front of it 
 presents a true and even surface, sometimes 
 of a foot or more in diameter ; four holes 
 pass through the face. The work is held by 
 dogs, screws or flanches ; three sorts of which 
 are represented below. The screw of these 
 passes through the holes in the face of the 
 chuck, and the work being placed between 
 them, and properly adjusted to the centre, 
 the dogs are screwed up from behind, or in 
 the front, as may be found most convenient. 
 Flat and very irregularly-shaped bodies may 
 thus be attached to the lathe more readily 
 than by any other means. 
 
 SuRSOLiD. A term given by the early 
 algebraists to what we now call a fifth power. 
 
 Survey. A measured plan and description 
 of any line or area of country. 
 
 Surveying. In a general sense denotes 
 the art of measuring the angular and linear 
 distance of objects, finding their superficial 
 content, ascertaining their nature, solidity, 
 and adaptation to specific purposes, &c. ; 
 thus, measuring the distance and position of 
 a lighthouse ; depth of water in a bay ; the 
 measurement of land ; of artificer's work ; 
 the repairs or solidity of a building ; position 
 and level of roads and canals ; condition of 
 a camp, or of a mine, of machinery ; exca- 
 vations of the earth ; and numberless other 
 matters, are the subjects of surveying. Many 
 kinds of surveying, therefore, are in use, 
 each distinct from the other ; thus we have 
 marine surveying, land surveying, house 
 surveying, military surveying, &c. In the 
 more limited acceptation of the word, land 
 surveying only is intended. This is conducted 
 in several manners, according to the nature of 
 the ground ; for example, supposing it should 
 be an irregular field of the shape beneath, 
 it would be measured by taking the base 
 line along the field, aind by means of the 
 
su 
 
 sw 
 
 theodolite, the cross, or some other instru- 
 ment, taking lines perpendicular to this, 
 reaching to the various angles. If the length 
 of these lines be taken, and also the veirious 
 distances along the base line where they start 
 from, it will divide the field into a number 
 of right-angled parallelograms or right-angled 
 triangles, A, B, C, D, E, F, G, H, I. The 
 content of each is calculated, and then the sum 
 of all of them is the content of the field. 
 
 It will be obvious upon looking at the fol- 
 lowing cut that a difterent measurement would 
 be more convenient. Here the field is divi- 
 ded into triangles, the perpendicular height 
 of each of which is taken at the same time, 
 BB, C C, D D, &c., forming one triangle. 
 The content of each is ascertained, and the 
 area found as before. 
 
 It often happens that the intervention of 
 water, wood, corn-fields, &c. prevents the 
 actual passage of the surveyor over the ground ; 
 in that case he must contrive to take some 
 one base line across a field or along a hedge, 
 and from the ends of that line take the 
 angular position of distant points, calculating 
 afterwards the remaining sides of the triangles 
 thus got out by trigonometry. Marine sur- 
 veying, such as that of harbours, bays, &c., 
 is performed by this method. The implements 
 used in surveying are Gunter's Chain, the 
 Cross, and the Theodolite, (see these words ; 
 also Arrow, Base Line, Offset, 8fc.) 
 
 SurveyingWheel. {^qq Perambulator.) 
 
 Suspension. In mechanics, the balancing 
 or supporting any body from a point above 
 it, which pouit is called the point or centre 
 of suspension. 
 
 Suspension Bridge. A bridge suspended 
 from inverted bows, by means of rods, being 
 usually formed of iron. The bows are sup- 
 ported by stone piers erected at or near the 
 
 ends, and from thence carried down and 
 secured in the ground. From the bows being 
 of numerous Mnks, united together, this is 
 often called a chain bridge. 
 
 Swag. An unequal or hobbling motion. 
 
 Swallow Tail. The same as dove tail, 
 (which see.) 
 
 Swan, Electrical. An experiment to show 
 electrical attraction. Procure a swan, made 
 of wax, wood, or very thin metal ; when of 
 wax or wood, cover a part of its body with 
 tin-foil, fioat this in a large bason of water 
 and put the water on an electrical stool. 
 Turn the machine, and upon holding the 
 finger or a piece of bread towards the swan, 
 it will be attracted to the hand. 
 
 Swan, Magnetic. A figure like the last ; 
 but containing a large sewing needle, placed 
 from the head to the tail. Floating in a 
 bason of water on a table, this figure will be 
 attracted by a magnet held tov;ards it. 
 
 Swanpan, or ScHWAMPAN. The abacus 
 or counting table of the Chinese, by which 
 they perform their usual mercantile calcu- 
 lations. It is a square frame of wood or 
 bamboo, with a division across it, and ten 
 transverse wires, upon each of which, both 
 below and above the division, are five beads ; 
 each wire representing a number, (as the 
 digits do among us,) and each bead giving a 
 a particular value to the number, like units, 
 tens, hundreds, and so on. (See Abacus.) 
 
 Sweets. A technical word for molasses 
 or treacle. 
 
 Sweet Spirits of Nitre, or Dulci- 
 fied Spirits of Nitre. Nitrous ether. 
 This is used to communicate a flavor to 
 British brandy. 
 
 Sweet Spirit of Salt, or Dulcified 
 Spirit of Salt. Hydrochloric ether. 
 
 Sweet Wines. Those wines are called 
 sweet which are made by the addition of 
 sugar to the juice of the fruit, and the fer- 
 mentation of which is not carried so high as 
 to convert all this sugar into alcohol, but 
 leaving it in the wine, occasions a sweet flavor. 
 
SY 
 
 SwEiNFORD Green. (See Scheele's 
 Green.) 
 
 Swelled Column. One the shaft of 
 which is largest in the middle of its length. 
 
 Swing, Electrical. An experiment of 
 electrical attraction, in which a figxire, sus- 
 pended from a silk thread, and supported 
 upon two glass pillars, is made to vibrate 
 between a ball which is charged with elec- 
 tricity, and one which is connected with the 
 earth. Suppose A to be connected with the 
 prime conductor of an electrical machine. 
 B a stand of baked wood. C a ball, con- 
 nected with the earth. The figure, when the 
 machine is .put in action, would vibrate 
 between the two balls. 
 
 Swing Tree. Any beam that vibrates. 
 
 Switch. That part of the rails of a rail- 
 way where a side cutting joins the main rail, 
 and which being moveable sideways enables a 
 carriage to continue straight forwards, or to 
 move into the side rails, as may be desired. 
 The switches are in some cases fixed ; in 
 othe s moveable sideways by a cross rod and 
 leve attached to them. 
 
 Swivel. A thing fixed in another body to 
 turn round upon. 
 
 Swivel, or Swing Bridge. A moveable 
 bridge, much employed in docks, in order to 
 admit the passage of shipping, consistmg of 
 two parts or platforms, thek point of meeting 
 being midway between the abutments ; each 
 portion turning upon a centre pivot, and 
 supported upon rollers ; the overhanging por- 
 tion is balanced and kept in position by a 
 counter -balancing weight fixed within the 
 framing of the other end. 
 
 Sylvius, Salt of. Muriate of potass. 
 
 Symbols. Marks or chaiaciers, used as 
 
 SY 
 
 an abbreviation for objects, substances, or 
 scientific operations. The symbols relative 
 to the subjects in this " Dictionary" are 
 chiefly those belonging to astronomy, che- 
 mistry, and the mathematics. The first class 
 are given under Astronomy. The chemical 
 symbols are extremely various, each distin- 
 guished chemist forming for himself a collec- 
 tion of them. Thus we have the symbols of 
 the alchemists, of Bergman, Berzelius, Dal- 
 ton, and others. These are for the most part 
 arbitrary, and now but little attended to ; it 
 being considered suflScient to indicate the 
 component parts of a body, by the initial let- 
 ter or letters of its constituents, and the 
 equivalents of them, with the sign of addition 
 between, as may be seen in the following 
 example : — 
 
 Carbonic oxyde (car + o) or C^O 
 
 Carbonic acid {car-^20) 
 
 Carbonate of ammonia (fl + CCir) 
 
 Peroxyde of nickel (WiC + Uo) 
 
 Deutoxyde of antimony {CLTl + 20 j 
 
 Most of the symbols used in the mathe- 
 matical sciences are well known. They, with 
 their names, are as follows : — 
 
 + Plus or more, the sign of addition. 
 
 — Minus or less, the sign of subtraction. 
 
 X Multiply or multiplied by. 
 
 -5- Divide or divided by. 
 
 = Equal or equal to. 
 
 As : is to :: so is : to, ratio or proportion. 
 
 1 2 Square V Square root. 
 
 13 Cube 3V Cube root. 
 
 D Square ; and numerous others 
 
 Symmetrical EauATioNs. In algebra, 
 are those equations consisting of two or more 
 unknown quantities similarly involved, so 
 that no difference will arise by writing these 
 quantities reciprocally for each other. 
 
 Symmetry. Exact accordance with the 
 rules of beauty. It is absolute or relative, 
 uniform or respective. Absolute or uniform 
 symmetry is when every part accords with 
 all the rest in size, form, and material. Re- 
 lative symmetry implies also uniformity or 
 structure, as a building may be in just pro- 
 portion, and therefore absolutely symmetrical, 
 but having one wing larger than the other, 
 it is not relatively so, the opposite sides not 
 corresponding with each other. 
 
 Sympathetic Ink. An ink which makes 
 no mark upon the paper until it is submitted 
 to heat, or until a second liquid is passed 
 over it. Of the first kind, numerous ex- 
 amples might be given, as milk, onion juice, 
 lemon juice, sulphuric acid, &c. This makes 
 no mark until the paper is heated, when the 
 writing appears more or less black, and 
 always .remains so. If a solution of the 
 muriate of copper be used, it will appeal' 
 
SY 
 
 SY 
 
 yellow when heated. The acetate of cohalt 
 will give a green color, and the chloride of 
 cohalt a fine blue. These colors again dis- 
 appear as the paper cools. The second class 
 of sympathetic inks may be understood by 
 the following examples : — Write with a so- 
 lution of sulphate of iron ; the writing will 
 not appear till the paper be washed over 
 with some substance which will decompose 
 this ; for example, tincture of galls will pro- 
 duce a purple, and prussiate of potass a blue. 
 
 Sympiesometer. The invention of Mr. 
 Adie, optician, of Edmburgh, and for which 
 a patent was procured. It 
 is thus described in the 
 words of the patent : — 
 The principle of the in- 
 strument consists in mea- 
 suring the weight of the 
 air by the compression of 
 a column of gas. It is 
 formed of a tube of 
 glass, A B C D, about 
 18 inches long and 0*7 
 of an inch in diameter 
 inside, terminated above 
 by the bulb D, and having 
 the lower extremity bent 
 upwards, and expand- 
 ing into an oval cistern A, 
 open at the top. The 
 bulb D being filled with 
 hydrogen gas ; and a part 
 of the cistern A, and the 
 tube B with almond oil, 
 colored with alkanet 
 root, the inclosed gas, by changing its bulk 
 according to the pressure of the atmos- 
 phere on the oil in the cistern, produces a 
 corresponding elevation or depression of the 
 oil in the tube. The scale for measuring 
 these changes is determined by placing the 
 instrument, with an accurate barometer 
 and thermometer, in an apparatus where 
 the air can be rarefied or condensed, so as 
 to make the barometer stand at 27"30, or 
 any other number of inches. The different 
 heights of the oil in the tube correspond- 
 ing to those points being marked on its 
 scale E F, and the spaces between them 
 being divided into 100 equal parts ; these di- 
 visions represent hundredths of an inch in the 
 mercurial column. To allow for the effect 
 of variations of temperature upon the in- 
 closed gas, the principal scale E F is made to 
 slide on another G H, so graduated as to re- 
 present the amount of such changes, corres- 
 ponding to the degrees of a thermometer, 
 I K, which is attached to the instrument. 
 
 Synchronism. The being or happening 
 of several events at the same time, as isochro- 
 
 nism denotes two or more things being per- 
 formed at the same time ; the first arising 
 from a natural, the other firom an artificial 
 ca]ise. 
 
 Synodic, or Synodical Month, is the 
 interval or period of time in which the moon 
 passes from one conjunction with the sun tQ 
 another, and is therefore precisely one lunation, 
 the mean duration of which is 29 d., 12 h., 
 44', 28". 
 
 Synodic Revolution of a Planet, 
 is the time between two conjunctions or two 
 I oppositions of the same planet and the sun. 
 ( Synthesis. Denotes a method of compo- 
 sition as opposed to analysis or resolution. 
 In chemistry, for example, we prove the 
 composition of a substance by mixing to- 
 gether what we know to be its constituent 
 principles, thereby forming that substance. 
 In mathematics, by the synthesis or synthetic 
 method, we pursue the truth by reasoning 
 drawn from prmciples before established or 
 assumed, and propositions formerly de- 
 monstrated ; thus proceeding by a regular 
 process till we arrive at a conclusion. 
 
 Synthetical Method. (See Synthesis.) 
 
 Syphon. (See Siphon.) 
 
 Syphon Barometer, or Reduced Baro- 
 meter. This instrument is about 4 inches 
 long. It consists of a tube doubled upon 
 itself twice, and very nearly filled with mer- 
 cury. It serves the purpose of a manometer, 
 in showing the dilations of the air in the re- 
 I ceiver of an air pump, for which purpose it 
 1 is commonly employed. 
 
 Syphon Gauge. (See Gauge.) 
 
 Syringe. In hydraulics, a small simple 
 machine serving first to imbibe and suck in 
 a quantity of water or other fluid, and then 
 to expel the same with violence in a small 
 jet. The boy's squirt is an example. (See 
 Condensing Syringe.) 
 
 Syrup. A solution of sugar in water. 
 
 System. In a general sense, denotes an 
 assemblage or concatenation of principles 
 and conclusions ; or the whole of any doctrine, 
 the several parts of which are united together, 
 and follow or depend on each other, as 
 a system of astronomy, Tsee Copemictts, 
 j Ptolemy, and Tycho Brahe^ a system of the 
 planets, a system of philosophy, &c. 
 
 System of Pulleys. A number of pulleys 
 united together with one rope over all, so 
 that all the pulleys unite to produce the 
 effect required. (See Pulley.) 
 
 Systile. The manner of placing columns 
 where the space between the two shafts con- 
 sists of two diameters. 
 
 Syzygy. a term equally used for the 
 conjunction or opposition of a planet with 
 I the sun. 
 
TA 
 
 The twentieth letter 
 of the English alphabet, 
 a lingual letter, and a 
 mute, having a sound 
 very similar to d, but 
 uttered with a sharper 
 emission of the breath. 
 Combined with A, it has 
 two other sounds, as in 
 the words this and thing : the former is a 
 sound between d and t ; the latter between 
 t and 8; so that foreigners whose native 
 language does not contain these sounds, often 
 say dis and sing for this and thing ; or, 
 nossing for nothing. T is used as an abbre- 
 viation on monuments, &c., for Titus, 
 Titius, TuUius, &c. In music, T signifies 
 tenor ; also tace, to indicate sUence ; and 
 in concerts it is also the sign of tuttit a di- 
 rection for the whole band to play after a 
 solo. In the arts,- it is used as a word to 
 denote things of the form of this letter as a 
 capital; thus we say a T square ; the T piece 
 of a Stanhope press ; a T bandage ; or the 
 T palace at Mantua. 
 
 Tabby. A kind of rich silk, watered, 
 that is, passed between metal rollers variously 
 engraved, which bearing unequally on the 
 stuff, renders the surface unequal, so as to 
 reflect the rays of light differently, making 
 the representation of waves thereon. 
 
 Table. In mathematics, is a series or 
 system of numbers methodically arranged, 
 for the more ready calculation of various 
 problems in annuities, astronomy, logarithms, 
 &c. Astronomical tables are computations 
 of the motions and other phenomena of the 
 heavenly bodies. Tide tables give the time 
 of high water at the places for which they 
 are made. Meteorological tables are a register 
 of the state of the weather, temperature, 
 dryness, &c. at the time that the tables are 
 kept. Chemical tables, and others relative 
 to natural philosophy, contain generally a 
 comparative account of various classes of 
 substances, or of different conditions of the 
 same substance. 
 
 Table, or Tablet. In architecture, &c., 
 a flat surface charged with any ornamental 
 device. 
 
 Table, Corbel. (See Corlel Table.) 
 
 Table, Water, A coping or flat stone or 
 stones placed on the top of the various stages 
 of buttresses, tops of battlements, &c., to 
 throw off the wet. 
 
 Table Diamond, or other precious stone, 
 is one whose upper surface is quite flat, and 
 the sides cut in angles ; in which sense a 
 diamond cut table-wise is used in opposition 
 to a facetted diamond, which is cut in facets, 
 coming to a point in the front, and a rose 
 diamond, which is of a smooth regular surface. 
 
 Table Microscope. Any microscope 
 adapted to stand upon or to be fastened to a 
 
 TA 
 
 table ; the term being used not as expressive 
 of any particular kind of instrument, but in 
 contra- distinction to those small microscopes 
 which are held in the hand. 
 
 Table of Glass. In glass works, and 
 among glaziers, a circular plate of window 
 glass, being the original form in which it is 
 cast. 
 
 Tablet. The same as table. 
 
 Tacamahac. a peculiar resin extracted 
 from a particular species of poplar. It has 
 much the scent of benzoin and musk com- 
 bined. 
 
 Tachom ETEU. An instrument invented by 
 Mr. Doi^kin, to indicate the velocity of 
 machinery. It is represented below. A B 
 is a glass tube open at both ends'; it is fixed 
 to an upright board, and dips into the cup C, 
 but is not connected witli it. The cup C 
 passes through a socket at D, and is united 
 with the pulley E. A cord passes over this 
 pulley, and over another pulley attached to 
 some part of the machinery. C is partly 
 filled with mercury, and the glass tube partly 
 filled with colored spirits of wine. When 
 the cup is whirled round, the mercury, by 
 centrifugal force, is collected about the edge 
 of the cup, leaving a cavity towards the 
 centre. This occasions the spirits of wine to 
 sink in the tube, and as the bore of the tube 
 above the cup is much less than that part 
 in the cup, (for every inch that the mercury 
 falls, the spirits of wine falls several inches ;) 
 and as the centrifugal force is in proportion 
 to the rapidity of motion given to the cup ; 
 and its sinking, and that of the spirits of 
 wine in proportion to the sinking of the 
 mercury, it is evident that by attaching a 
 scale to the long tube, the velocity of the 
 motion of the machinery will be easily and 
 accurately indicated. 
 
TA 
 
 TA 
 
 Tackle. Another name for a pulley, or 
 system of pulleys. Ground tackle implies 
 anchors, cables, and buoys. 
 
 Taction. Touching or tangency. 
 
 Taffety. a very rich, glossy, silk stuff; 
 plain, flowered, gold striped, &c. 
 
 Tail In. In carpentry, to fasten any thing 
 into a wall at one end, as the steps of a stair, 
 a bracket, &c. 
 
 Tail Water. Water which impedes a 
 water wheel. 
 
 Talc. A well-known and widely-diffused 
 species of mineral, remarkable for its perfect 
 capability of cleavage, as it may be split into 
 laminae much finer than the thinnest paper. 
 The finer kinds are perfectly transparent, and 
 are used by the Russians, instead of glass, 
 for windows. We have also a great con- 
 sumption of it for the tops of the boxes, 
 containing the mariner's compass needle, and 
 for mounting microscopic objects. When 
 pounded, it is used along with carmine or 
 safflower for rouge ; also, to communicate a 
 flesh-like softness to plaster figures, and other 
 minor purposes. 
 
 Tallow. Animal fat, melted and sepa- 
 rated from the fibrous matter mixed with it. 
 
 Talon. The same as ogee. 
 
 Talus, or Talut. The same as batter, 
 (which see.) 
 
 Tambour. The vase or naked part of a 
 Corinthian or Composite capital, and on 
 which the ornaments are supposed to rest. 
 Also, the wall of a circiJar temple when sur- 
 rounded with columns. Also, a lobby or 
 vestibule, inclosed with folding doors, to 
 break the current of wind from without, as at 
 tiie entrance of churches, banking houses, &c. 
 
 Tambour. A species of embroidery, in 
 which threads of gold, silver, colored silks, 
 &c., are worked by needles of a peculiar form 
 into flowers, leaves, or other ornamental 
 objects, upon a silk stuff, stretched over a 
 circular frame, called a tambour. 
 
 Tangent. A line which touches a circle 
 or other curve without cutting it, extending 
 however only on one side. Thus, in the fol- 
 lowing figure, C C C and other lines are 
 tangents to the circle. 
 
 In a circle, a tangent is perpendicular to 
 the radius at the point of contact; that is, 
 
 A B is perpendicular to B C ; also A B* = 
 AExAF; orAB is a mean proportioiud 
 between A £ and A F. 
 
 Tangent, in trigonometry, has a more K- 
 mited meaning. It is a right line touching 
 one extremity of an arc, and limited between 
 that point, and its intersection with the se- 
 cant passing through the other extremity. 
 Thus A G is the tangent to the arc B A, and 
 also to the arc which forms all the rest of 
 the circle A C B, and A H is a tangent to the 
 arc A K ; and also, as in the other case, it is 
 tangent to the rest of the circle A B C K, 
 So also L M is the tangent to the arc L B, 
 or the co-tangent to A B. Hence the tan- 
 gents in the first and third quadrants are 
 positive, in the second and fourth negative ; 
 that is, they are drawn in an opposite di- 
 rection to the former. Also the tangent of 
 0° is zero, or nothing, but the tangent of 90* 
 is infinite ; so likewise the tangent of 180° ia 
 zero, but of 270° infinite. 
 
 Tangents, Artificial. A term used by 
 some authors to denote the logarithmic tan- 
 gents, in contra-distinction to natural tan- 
 gents, or the absolute tangents to any given 
 radius. 
 
 Tangents, Method of. Is a method of 
 drawing tangents to any algebraical curve, or 
 of determining the magnitude of the tangent 
 and sub-tangent ; the equation of the curve 
 being given. 
 
 Tangents, Inverse Method of. This is 
 the reverse of the foregoing, and consists ia 
 finding the nature of the curve that has a 
 given sub -tangent. 
 
 Tangential Force. Any force whidi 
 acts 80 as to give a tendency to any body to 
 
 53 
 
TA 
 
 TA 
 
 fly off from ,the centre. Thus mud from a 
 wheel, water from a mop, and a stone from a 
 sling, are thrown off at a tangent from the 
 rotative body. So also would the planets, 
 which are acted upon by the same force, the 
 centrifugal, be thrown off into infinite space 
 were it not for the power of gravitation which 
 restrains them. 
 
 Tank. Any large square or oblong vessel, 
 whether formed of wood, stone, or metal, 
 adapted to hold a liquid. 
 
 Tannates. Combinations of the tannic 
 acid and metallic solutions. The tannates 
 are mostly insoluble. 
 
 Tannic Acid, or Tannin. A peculiar 
 vegetable principle, so named because it is 
 the effective agent in tanning. It is found in 
 considerable quantities in oak bark, sumach, 
 nut galls, fern roots, willows, and other ve- 
 getables. It is owing to the existence of 
 tannin that leather tanned with it for a long 
 period is so impervious to wet, and so much 
 more durable than untanned skins. 
 
 Tannin, Artificial. A species of tannin 
 may be formed artificially, by digesting char- 
 coal in dilute nitric acid for several days. It 
 is at length dissolved, and a reddish brown 
 liquid is obtained, which furnishes, by careful 
 evaporation, a brown, glossy substance, 
 amounting to about 120 parts to every 100 
 of charcoal. This is soluble in water and 
 alcohol. 
 
 Tanning. A chemical process, by which 
 the hides and skins of various animals, par- 
 ticularly those of neat cattle, are made into 
 a hard and durable leather. 
 
 Tanno-Gelatine. The white precipitate 
 which is formed when tannin is added to a 
 solution of gelatin. 
 
 Tannous Acid. The tannin of catechu, 
 which is said to contain less oxygen than the 
 tannin from oak bark. 
 
 Tantalum. A metal, otherwise called 
 columbium, (which see.) 
 
 Tantalus Cup. A siphon so adapted to 
 a cup, that the short leg being in the cup, 
 the long leg may go down 
 through the bottom of it. 
 When a liquid is poured 
 into the cup, it will rise 
 in the cup until the height 
 of it is above that of the 
 bend of the siphon, when 
 the siphon will begin to 
 act, and the whole of the 
 water run out. It is 
 called Tantalus cup, be- 
 the siphon is usually 
 
 concealed by a small figure endeavouring to 
 drink, but who is foiled, for immediately the 
 water reaches his mouth it flows away. 
 
 Tapering. A term expressive of the na- 
 ture of a solid, contained between two or 
 more opposite planes inclined towards each 
 
 other, or inclosed by a surface which is nar- 
 rower at one end than at the other. Thus 
 the wedge, the pyramid, the fVustriim of a 
 pyramid, the cone, and the frustrum of a 
 cone, are all tapering solids. 
 
 Tapestry. A kind of woven hangings, 
 of wool and silk, frequently raised and en- 
 riched with gold and silver, representing 
 figures of men, animals, historiod subjects, 
 landscapes, &c. 
 
 Tapioca. A kind of starch, procured by 
 the Brazilians from the root of the cassava 
 plant. 
 
 Tappets. The small levers which are con- 
 nected with the valves of the cylinder of a 
 steam engine, and which are worked by the 
 air-pump rod. {^ee Steam Engine.) 
 
 Tar. a well-known substance, obtained 
 chiefly from the pine by burning it in a close 
 smothered heat. Some of the unctuous spe- 
 cies of bitumen are also called mineral tar, 
 and during the manufacture of coal gas a tar 
 exudes from the coals, and is deposited in a 
 receiver, called the tar vessel. This is coal 
 tar. 
 
 Tare and Tret. A rule in arithmetic, 
 which ascertains the allowance to be made on 
 any goods on account of the weight of the 
 packages, dross, &c. 
 
 Tarpauling. a broad piece of canvas, 
 well daubed with tar, and used to cover the 
 hatchways of a ship at sea, to prevent the 
 penetration of sea water. Tarpaulings are 
 used for similar purposes on shore. 
 
 Tarras, or Terras. A volcanic earth, 
 similar to that of puzzolana, which, wl en 
 calcined and mixed with sand and water, 
 makes a hard and durable mortar, applicable 
 particularly to stand in situations under 
 water. 
 
 Tartar. A substance deposited on fhe 
 sides of wine casks, during the time that the 
 wine is in a state of fermentation. Tliis sub- 
 stance being scraped off, and in its natural 
 and junpurified state is called by chemists 
 bitrate or supertartrate of potass, and popu- 
 larly crude tartar. When this is purified by 
 solution, crystallizing, and boiling along with 
 a clayey earth, it is known as cream of tartar y 
 or the acidulous tartrate of potass, or purified 
 tartrate of potass. 
 
 Tartar, Boraxated. When borax is ad- 
 ded to tartar, it becomes much more soluble. 
 It is then called boraxated tartar, Le Fevre's 
 soluble cream of tartar, or sal gummosum. 
 
 Tartar, Emetic, The tartrate of potass 
 and antimony. 
 
 Tartar, Regenerated. The acetate of 
 potass. 
 
 Tartar, Salt of. The sub-carbonate of 
 potass. 
 
 Tartar, Salt of, per deliquium. The sub- 
 carbonate of potass, liquified by a small 
 quantity of water or by exposure to the air. 
 
TE 
 
 TE 
 
 Tartar, Secret Foliated Earth of. Ace- 
 »te of potass. 
 
 Tartar, Soluble. The neutral tartrate of 
 potass. 
 
 Tartar, Soluble Cream of. (See Tartar 
 Boraxated.) 
 Tartar, Vitriolated. Sulphate of potass. 
 Tartaric Agio. An acid obtained from 
 tartar, by boiling it in water, and saturating 
 its potass by sulphuric acid. This, by con- 
 tinuing the boiling will fall down, and the 
 supernatant liquid being poured off, boiled to 
 the consistence of a syrup, and set aside, de- 
 posits crystals of tartaric acid, equal in weight 
 to half the tartar employed. 
 
 Tartarine. The name given by Kirwan 
 to the vegetable alkali or potass. 
 
 Tartaric Ether. An ether formed by 
 distilling together 5 parts of tartaric acid, 
 7 of alcohol, and 2 of sulphuric ether. 
 
 Tartrates. Neutral compounds of the 
 tartaric acid with a base. 
 
 Tassels. The brackets or pieces of wood 
 which sometimes support the mantle shelf in 
 common buildings. 
 
 Tawing. The preparation of white leather. 
 Teak. A valuable timber, which abounds 
 in various parts of the East Indies, and is 
 applied to domestic and nautical purposes. 
 Ships built with teak are far more durable 
 than those built of English oak. 
 
 Teasel. The head of a plant, called dip- 
 sacus fullonum. It is employed to raise the 
 nap upon cloth ; a number of the prickly 
 heads being fastened to a wheel, to which a 
 rapid motion is given by hand or by machi- 
 nery, and the cloth when dyed being placed 
 beneath the wheel, the points or hooks of 
 the teasels catch the finer fibres of the wool, 
 and draw them in one direction, which con- 
 stitutes the nap of the cloth. 
 
 Technical. Signifies in general that which 
 belongs to any art, or to any branch of it in 
 particular. A technical term is an expression 
 peculiar to any art or profession. In the 
 fine arts, the technical comprises every thing 
 relating to the material execution of works 
 of art. 
 
 Technology. The science which treats 
 of the arts, particularly those which are 
 mechanical. 
 
 Teint. (See Tint.) 
 
 Telamones. The images of men sup- 
 porting a cornice or entablature. 
 
 Telegraph. A name given to any instru- 
 ment, by means of which intelligence can be 
 rapidly communicated to a considerable dis- 
 tance. There are numerous kinds of tele- 
 graphs in use ; that at the Admiralty, in 
 London, consists of a perpendicular post, 
 bearing six arms, as represented in the cut. 
 Each of these is worked by a cord, and may be 
 folded up within the post, or directed to three 
 different positions ; oblique upwards, hori- 
 
 zontal, and oblique downwards. The changes 
 that may be made by them is therefore almost 
 endless ; and if certain words, numbers, or 
 phrases, are attached to each position of the 
 arms, it is evident that the intelligence may 
 pass as rapidly as the boards or arms can be 
 moved. The figures show the telegraph with 
 all the arms extended, and also a variety of 
 the positions into which it may be put. 
 
 Telegraph, Electrical. A means of rapid 
 communication by the science of electron 
 magnetism. It is known that when a current 
 of electricity passes around a magnet, it 
 occasions that magnet to diverge from its 
 former position in proportion to the strength 
 of the current. In the electrical telegraph, 
 a current is sent along a wire inclosed in a 
 waxen or resinous material to keep it dry 
 and insulated, from one station to another, 
 where it acts upon several magnets, in accord- 
 ance to a similar set of magnets at the first 
 station. According to the manner in which 
 it acts upon these, driving them to the right 
 or left, more or less, it is instantly known 
 what it is intended to communicate. 
 
 TEL^GKAPH,Pneumatic. {See Pneumatic.) 
 Telegraphic Alarum. (See Magnetic 
 Alarum.) 
 
 Telescope. An optical instrument em- 
 ployed in viewing distant objects. Telescopes 
 are either refracting or reflecting ; the former 
 consists of different lenses, through which 
 the objects are seen by rays refracted by them 
 to the eye ; and the latter consists of lenses, 
 and also mirrors, from which last the raya 
 are reflected to the eye. The lens or glass 
 turned to the object, is called the object 
 glass, and that next the eye the eye-glass ; 
 and when the telescope contains more than 
 two lenses, all but that next the object are 
 called eye-glasses. The simplest of all tele- 
 scopes is that used for observations by night, 
 called the astronomical telescope, and which 
 is described under Night. The telescope 
 used by day, and upon ordinary occasions, 
 contains three lenses ; or if of four lenses, 
 those two '^xt the eye act as one only— 
 
TE 
 
 TE 
 
 they are but of half the thickness a single 
 kns would needs be in that situation. The 
 reason that two lenses are here used as one, 
 is to obviate as much as possible the effects 
 of spherical aberration. The action of the 
 ordinary day tekscope is as follows : — Suppose 
 the rays from A B strike the object glass C D ; 
 they are refracted and form an inverted 
 image of the object at the focus ; they then 
 strike the second glass E F, and passing off 
 ki parallel lines strike the third glass G ; 
 here the image appears erect, and thence 
 proceeding to the last glass H, the rays are 
 »ot again inverted, because the eye is placed 
 within, and not beycHid the focus. 
 
 For other telescopes, (see Cassegrainian, 
 Gregorian, Galilean, Newtonian,and Night.) 
 
 Tklescope, Achromatic. A telescope, the 
 eye-glass of which is achromatic. 
 
 Telescope, Caiadioptric. The same as 
 reflecting telescope. 
 
 Telescope, Dioptric. The same as re- 
 fracting telescope. 
 
 Telescopical. Belonging to a telescope ; 
 seeing at a distance. 
 
 Telescopic, or Telescopical Stars, 
 lire such as are not visible to the naked eye, 
 but only seen by means of a telescope. 
 
 Tellurates. Combinations of the telluric 
 acia. 
 
 Telluretted Hydrogen. A gaseous 
 combination of tellurium and hydrogen, 
 which may be made by submitting an alloy 
 of tellurium and tin to the action of hydro- 
 chloric acid. It reddens litmus, dissolves 
 in water, and possesses the general habitudes 
 of sulphuretted hydrogen. 
 
 Telluric Acid, or Peroxyde of Tel- 
 lurium. When the tellurous acid is de- 
 flagrated with nitre, it is converted according 
 to Berzelius into telluric acid. It contains 
 half a proportion more oxygen than tellurous 
 acid. 
 
 Tellurion. An instrument for showing 
 the effect of the earth's motions and the 
 obliquity of her axis ; the one occasioning 
 the seasons, the other the succession of day 
 and night. A is a lamp, representing the 
 sun. B a pasteboard globe, showing the 
 earth ; this is set at an angle of 23a° with 
 the perpendicular. The axis fits loosely into 
 a socket I, and bears a wheel H ; this works 
 in another wheel G, which is fixed to the 
 pulleys K and M. C is a stand that bears 
 at various heights the multiplying wheel D, 
 the cross bar of wood E, the pulley I, and 
 tiie lamp A. C» D, I, and A being fastened 
 
 together, but E turning round. An endless 
 cord passes from K to I, and another from 
 M to D. Turning the shaft E O around its 
 centre by the end O, gives the earth a motion 
 like that of its annual revolution around the 
 sun ; at the same time it turns on its axis, 
 owing to the wheel D working the pulley M, 
 that the wheel G, and G the wheel H. This 
 shows the cause of the succession of day and 
 night, the earth being supposed to turn round 
 once in 24 hours. It has moreover a third 
 motion, by means of the short cross bar I, 
 which moves loosely on the arbor of G. The 
 pulley being fixed to I, and a cord passing 
 round the equal sized pulley K, the earth will 
 turn round G once in the whole revolution 
 around the sun, and present its axis in a 
 different manner to that luminary. As repre- 
 sented in the cut, it would show the winter 
 solstice; after a quarter of a revolution it 
 would represent the position of the axis at 
 the vernal equinox ; at another quarter, the 
 summer solstice, when the north pole would 
 be illuminated ; and three months afterwards 
 the autumnal equinox would be shown ; thus 
 explaining the nature of the four seasons, 
 and sliowing that they arise from the ob- 
 liquity of the earth's axis. 
 
 Tellurium. A rare metal discovered in 
 an ore of gold by Kloproth, in 1798. It is 
 of a silver white color, brilliant with a lami- 
 nated texture, brittle, and melts at a tempe- 
 rature a little higher than lead does. It com- 
 bines with oxygen in two proportions, forming 
 tellurous and telluric acid. It also unites 
 with chlorine, hydrogen, sulphur, and iodine. 
 
 Tellurous Acid, or Oxyde of Tellu- 
 rium. A combination of 1 atom of oxygen 
 to 1 of tellurium. It is procured by burning 
 tellurium in the air ; it is of a yellowish white 
 color, and of a peculiar odour. 
 
 Temperature. Implies that degree of 
 sensible heat which a body possesses when 
 compared with other bodies. The tempe- 
 rature of bodies is ascertained by means of 
 the thermometer, cethioscope, pyroscope, 
 pyrometer, &c. 
 
 Tempering. The art of altering the 
 existing degree of elasticity of metals. For 
 example, steel is rendered more or less soft 
 or hard, or more or less brittle or elastic, 
 according to the degree of tempering, given 
 to it. Tempering is performed hy heating 
 the metal in the fire, and afterwards CO<diitg 
 it more or less rapidly. 
 
TE 
 
 TB 
 
 Template. A sort of guide, used in cut- 
 ting and placing masonry and stucco work. 
 It is a thin iron plate, upon the edge of 
 which is cut the reverse of the various 
 mouldings or indentations which the stone is 
 to be worked with, so as to form an exact 
 counterpart to it. Thus the workman, ap- 
 plying his template firom time to time, can 
 ascertam how the work proceeds. In laying 
 on plaster or cement cornices, mouldings, 
 string bands, &c., the template is furnished 
 with a back, fixed at right angles to the plate. 
 By laying on the liquid plaster, and running 
 the template along steadily, the back resting 
 against a straight edge, the plaster is left at the 
 indentations, but carried forwards where the 
 template of iron touches it. 
 
 Templet. A short piece of timber or a 
 large stone placed in a wall, to receive the 
 end of a girder, brestsummer, or other large 
 beam of timber. 
 
 Temple. A building appropriated to re- 
 ligious uses. 
 
 Tenacity. In natural philosophy, is that 
 quality of bodies by which they sustain a con- 
 siderable pressure or force without breaking, 
 being the opposite quality to brittleness or 
 fragility. 
 
 Tender. The name given to the waggon 
 which accompanies a locomotive engine, for 
 the conveyance of fuel and water. 
 
 Tenon. A projecting rectangular prism, 
 formed on the end of a piece of timber, to 
 be inserted in a mortice of the same form. 
 
 Tension. The quality of being stretched 
 beyond that length which a thing retains in 
 ordinary circumstances. 
 
 Tension Bridge. {SeeBowstring Bridge.) 
 
 Tenter, Trier, or Prover. A machine 
 or frame, used in the cloth manufacture, to 
 stretch out the pieces of cloth, and make 
 them set even and square. It is a very long 
 frame-work, or posts and rails ; the lower 
 rail lifting up and down, and both of them 
 being furnished with tenter hooks, upon 
 which the cloth is held by its selvages. 
 
 Ter. As a prefix to chemical and other 
 words, signifies three proportions of that sub- 
 stance to which the ter is affixed to each one 
 of the base. Thus the teroxyde of osmium 
 consists of 1 atom of osmium and 3 of oxy- 
 gen. The terchloride of chromium has 3 parts 
 chlorine to one of chromium, and so on for 
 other compounds. 
 
 Term. In geometry, the extreme of any 
 magnitude, or that which bounds or limits 
 its extent, thus the terms of a line are points ; 
 of a surface are lines ; and so on. Terms of 
 an equation or of any quantity in algebra, 
 are the several members of which it is com- 
 posed, separated from one another by the 
 signs + or — . Thus a^ + a^ + a^ is said to 
 consist of three terms. 
 
 Terminal Velocity. la the theory of 
 
 projectiles, is the greatest velocity which a 
 ball can acquire by descending vertically in 
 air ; and with which, when attained, it would 
 descend uniformly, if no solid obstacle de- 
 stroyed the motion. 
 
 Terminator. In astronomy, the earUi 
 being a ball, one half of it is always illumi- 
 nated by the sun ; the other half is in dark- 
 ness. The line which intervenes between the 
 light and darker sides is popularly called the 
 terminator. 
 
 Terminus. As applied to a railroad, is 
 the place of starting the trains, and the 
 termination of their journey; intermediate 
 places of stopping being called statiotis. In 
 architecture, a terminus is a trunk or pedestal, 
 adorned at the top with the figure of tiie 
 head of a man, woman, satyr, or animal, 
 whose body seems to be inclosed in a trunk, 
 as in a sheath, which usually tapers down- 
 wards. Termini are used for the support of 
 interior cornices, &c., and other purposes of 
 internal decoration. 
 
 Terra. The earth. 
 
 Terra Cotta. Baked earth. Earth or 
 clay was the first matter employed by ai'tists, 
 whether in building or modeUing ; and at 
 much more recent periods, was abundantly 
 used for the latter purpose, and is the sub- 
 stance of many beautifully executed bassi 
 relievi, of which relics and examples have 
 been found among the ruins of Herculaneum, 
 Pompeii, and other places. In fact it is 
 greatly used at the present day for construct- 
 ing architectural ornaments, &c., it being 
 plastic, cheap, readily worked, and at the 
 same time hard and durable. 
 
 Terra Ponderosa. Heavy spar. 
 
 Terra Sienna. A kind of umber or 
 brown iron ochre, used as a pigment. In its. 
 natural state it is of a light, transparent^ 
 yellowish brown, and is called raw sienna. 
 Wlien submitted to the action of fire, it be- 
 comes much more red. It is then the fine 
 color known as burnt sienna. 
 
 Terra Verte. A green earth, used as a 
 pigment. It is a good glazing color, being 
 of thin body. 
 
 Terrace. An area raised before a house 
 for walking upon. 
 
 Terrace Roof. Those which are flat 
 like terraces. 
 
 TERRAauEOUs. An epithet applied to 
 our earth when considered as consisting of 
 land and water. 
 
 Terrestrial. Any thing relating to the 
 earth, as terrestrial globe, line, &c. 
 
 Terrestrial Globe. (See Globe.) 
 
 Terrestrial Magnetism. (See Mag' 
 netism.) 
 
 Tesselated Pavement. A pavement of 
 mosaic work, made of small square dies or 
 tesserae of burnt clay or hewn stone, arranged 
 as to color so as to form an ejttremely oma- 
 
TE 
 
 TE 
 
 rQ^iiital pavement. Various ancient specimens 
 of these have been from time to time exhumed 
 in different parts of England ; two very 
 lately, 14 feet below the more modern pave- 
 ment of the French Church, Threadneedle 
 Street. The figure of a part of one of these 
 is seen below, the different shading showing 
 a difference of color. Tesselated pavements 
 are almost wholly the work of the Romans, 
 and are not to be confounded with the 
 quarried or the particolored marble pave- 
 ment of more modern times. 
 
 Tesskra. The name Of any small square 
 or cubical piece of wood, stone, baked clay, 
 or other material, formed for various purposes 
 among the Romans ; but more especially the 
 cubical bodies used to form tesselated pave- 
 ment, and which were somewhat about an inch 
 in length and breadth, and somewhat more 
 in thickness. (See Tesselated Pavement.) 
 
 Tests. A standard by which the certain 
 character of any thing may be ascertained ; 
 in which general definition the word test ap- 
 plies to all subjects and sciences. In a limited 
 sense, it is used in chemistry to denote those 
 re-agents which act in a peculiar manner upon 
 some substances, and not in the same way 
 up-on others. Thus they afford criteria by 
 which simple as well as compound bodies may 
 be distinguished. For example, suppose you 
 have a sdt, of the nature of which you are 
 ignorant, but which you suppose to be cop- 
 peras or the sulphate of iron. You may 
 prove it by various tests ; for example, add a 
 little muriate of barytes, if this occasion a 
 white precipitate, you prove one part, and 
 show that the substance contains sulphuric 
 acid ; then add a little tincture of galls, and 
 if it turns the solution of a black or dark 
 purple color, it shows iron to be present, be- 
 cause no metal will be rendered black by galls 
 but iron ; it is therefore a sure test. Other 
 tests apply to other bodies. 
 
 Test Objects for Microscopes. Those 
 objects which are selected as most appropriate 
 to test the discerning power of the compound 
 
 microscope; the perfection of the instru- 
 ment being ascertained by its rendering clearly 
 visible the various markings or structure of 
 the object. The chief tests are the dust or 
 scales from the wings of several kinds of but- 
 terflies, as the menelaus, the white cabbage 
 butterfly, the small brown house moth, the 
 scales of the diamond beetle, and best of all 
 the scales of the Podura, or spring-tail insect. 
 Among opaque objects are to be reckoned 
 the hair of the bat and of the mouse. The 
 figures on the enamelled dial plate of a watch 
 determine the quantity of chromatic or sphe- 
 rical aberration in a lens. 
 
 Test Papers. Pieces of thin soft paper, 
 stained with various chemical substances, to 
 be used instead of solutions of the various 
 tests ; it being more convenient to dip a paper 
 in the subject to be tested than to use a so- 
 lution of it. 
 
 Test Tube. A small tube of glass, closed 
 at the lower end and rather widened at the 
 top. The use of them is to hold small quan- 
 tities of any solution, in order that it may be 
 tested by necessary re-agents, and for other 
 purposes, in chemistry. Test tubes are usually 
 placed in a stand, from which they are taken 
 out at pleasure. 
 
 imm 
 
 Test Tube Holder. A contrivance of an 
 extremely simple nature, having for its object 
 the holding of a test tube, that a spirit lamp 
 may be placed beneath it, during any ope- 
 ration that requires heat to be applied to it 
 for a continuance, as is requisite in making 
 various solutions and combinations. It may 
 be made of wood, with a spring of tin, as 
 represented below. 
 
 Tetp^a. Any thing in which a part of i\ 
 occurs four times, as a tetrasulphuret, where 
 tv,^,-« oro foui- proportions of sulphur.. 
 
TH 
 
 TH 
 
 Tethagon. A figure of four angles, 
 whether a square, rectangle, trapezium, pa- 
 rellelogram, rhombus, or rhomboid. 
 
 Tetrahedron. One of the five regular 
 bodies. It has four equal triangular faces. 
 
 Tetrastoon. a court yard, with porticoes 
 or open colonades on each of its four sides. 
 
 Tetrastyle. a building having four 
 columns in front. 
 
 • • 
 
 Textile Fabrics. Any thing woven, such 
 as muslins, calicoes, silks, lace, &c. 
 
 Texture. Degree of strength, evenness, 
 elasticity, or other property in a body, by 
 which it may be indicated ; thus we say the 
 texture of a mineral may be fibrous or la- 
 mellar, or have some other property. 
 
 Thaumathrope. The name given to a 
 little amusing optical toy, whose effects are 
 founded upon the well-known principle, that 
 an impression made on the retina of the eye, 
 lasts for a short interval after the object 
 which produced it is withdrawn. It con- 
 sists of a card with two opposite strings ; 
 on each side of the card a device is introduced, 
 and when the card is rapidly whirled round, 
 the figures on each of its sides are presented 
 with such quick transition that they both 
 appear at the same instant, and thus occasion 
 a very striking and magical effect. For 
 example, depict a mouse on one side the 
 card and a mouse-trap on the other, upon 
 being whirled round, the mouse will appear 
 within the trap. 
 
 Thaw. Such an increase of temperature 
 as will restore frozen bodies to a state of 
 fluidity or suppleness. 
 
 Theatre. A building used for the per- 
 formance of plays and other scenic repre- 
 sentations ; also any place where lectures 
 are given to a large audience ; or a room 
 adapted to convey impressions from a distant 
 part to the eye, ear, &c. in the best manner. 
 
 Theatrical Fires, are those compo- 
 sitions used at the theatres to increase the 
 effect of conflagrations, incantation scenes, 
 &c., by a strong red, blue, or other colored 
 fire. The compositions are as follow : — 
 Red : Dry nitrate of strontian, 1| oz. ; suU 
 phur, 3 dr. 6 gr. ; chlorate of potass, 1 dr. 
 12 gr. ; sulphuret of antimony, 2 dr. ; char- 
 
 coal, 1 scruple. First pound the chlorate, 
 then mix it carefully on paper with the other 
 ingredients, previously pounded. Blue : Ni- 
 trate of barytes, 77 parts by weight; sul- 
 phur, 13 ditto ; chlorate of potass, 5 ditto ; 
 realgar, 2 ditto ; charcoal, 3 ditto. To fire 
 either of the above, lay them on a sheet of 
 tin, and apply a lighted match. A colored 
 flame is also often wanted; (for various of 
 them see Mre.) 
 
 Thebaia. An alkaline property existing 
 in opium. It has not been applied to any 
 use, and exists in a very minute quantity 
 
 Thein. a peculiar principle in tea, from 
 which it derives its flavor and exhilerating 
 properties. 
 
 Thenard's Blue. Phosphate of cobalt, 
 formed by the double decomposition of phos- 
 phate of soda and chloride of cobalt, cal- 
 cined with twice as much pure alumina at a 
 white heat. 
 
 Theodolite. An instrument employed by 
 surveyors for measuring angles, whereby to 
 compute the heights, distances, &c., of re- 
 mote objects. A B, in the figure beneath, is 
 a small telescope, which is made capable of a 
 vertical motion around the centre C. The 
 frame Vork which supports the telescope, 
 also supports the segmental scale E D, which 
 is divided into degrees of a circle. Upon 
 raising or depressing the end A of the tele- 
 scope, the scale will, of course, be equally 
 moved, and as the hand F stands at O, when 
 the telescope is horizontal, the proper angle 
 of its elevation will be indicated by the same 
 hand F, when the end of the telescope is 
 raised or depressed. Thus the height of any 
 object in angular measurement may be ascer^ 
 tained, and by this, and other measurements, 
 its true height may be afterwards found by 
 trigonometry. If it is desired to ascertain 
 the magnitude of a horizontal angle, it may 
 be done with equal facility by another motion 
 
TH 
 
 TH 
 
 th« instrument has ; this is around or within 
 its centre pin or support I, at the same time 
 the table G H remains fixed. This table 
 is graduated with a circular scale, in seg- 
 ments of 180° each ; a hand upon the moving 
 part of the instrument will at once indicate 
 the degrees passed over by the telescope when 
 turned horizontally from one point to another. 
 K L P are three tangent screws, for the ad- 
 justment of the instrument in a perfectly 
 horizontal position, and which is proved by 
 the spirit level O, and another running at 
 right angles to it, the end of which is seen at 
 F under the hand. M N is the end of the 
 tripod stand, upon which the theodolite usually 
 stands when in use. 
 
 Theorem. A proposition to be proved. 
 (See Proposition.) 
 
 Theoky. a rule, or set of rules or obser- 
 vations, for the explanation of any art or 
 science, or for the better understanding any 
 doubtful fact or phenomenon. It stands op- 
 posed to practice, or the performance of 
 what theory teaches. 
 
 Theory of Numbers. A modem branch 
 of analysis, which has for its object the in- 
 vestigation of certain properties of numbers, 
 such as the sum of two odd squares cannot 
 make a square number, that every number is 
 composed of four or a less number of squares, 
 &c. &c. 
 
 Thermal. Hot or occasioned by heat, as 
 thermal or hot springs. 
 
 Thermo-Electric Circuit. A combi- 
 nation of two metals, in distinct pieces, to 
 which heat being applied at one end of each, 
 they being united together by twisting or 
 soldering, the electricity of those pieces is 
 thereby disturbed, and the other ends being 
 connected with the cups of a galvanometer, 
 the disturbance becomes visible by its effects 
 upon the magnetic needle. Suppose A B to 
 be a galvanometer ; C D two wires, one of 
 platinum, the other of copper or silver, which 
 wires dip at one end into the cups A and B, 
 and are twisted together at E. If a spirit 
 lamp, hot ball of metal, flame of a candle or 
 other hot body, be held for a moment under 
 E, a thermo-electric current is established, 
 and it will be seen to cause considerable 
 divergence of the magnet of the galvanometer. 
 
 This experiment may be varied by a com- 
 pound rod of metal, as seen below. A is a 
 rod of bismuth, 4 or 5 inches long, with a 
 
 wire soldered in one end, and terminating ia 
 a mercury cup D. B is a rod of antimony, 
 of like size, and also furnished ydth a wire 
 and cup E. The two dissimilar bars are sol- 
 dered together at C, and the whole may be 
 supported upon wires. If D and E are con- 
 nected with the poles of a galvanometer, and 
 a spirit lamp is placed for a moment under C. 
 The effect upon the galvanometer will be the 
 same as in the former instance. 
 
 When the several pieces of each of the two 
 chosen metals are united in pairs, and those 
 pairs joined together, or else so placed as to 
 act in unison, a correspondingly greater 
 effect is produced, and the instrument may 
 then be called a thermo-electric battery ; such 
 a one is described under the word Melloni. 
 Also the magnetic needle may be placed so as 
 to be affected by the metals themselves, 
 without the aid of the galvanometer. The 
 converse, as may be witnessed by the fol- 
 lowing instrument, which is also a simple 
 circuit or circle. Let A B be a bar of anti- 
 mony, bismuth, tin, lead, or zinc ; and C D 
 a strip of copper, bound on to the ends of 
 A B by copper wire. E is a delicate, astatic 
 magnet, suspended on a point, projecting 
 above the bar of metal. When heat is applied 
 to the end, the magnet will be deflected on 
 one side ; if heat be applied to B, A being at 
 the same time cool, the magnet will turn to 
 the contrary side. 
 
 TflERMO-ELECTRic PiLES. {^e^Melltmi.) 
 Thermo-Electric Rectangle. ^ (See 
 Marsh.) 
 
 Thermo-Electric Thermometer. A 
 contrivance of Mr. Solly, to ascertain the 
 temperature of apartments, fire-places, &e. 
 It is exactly similsir in principle to the first 
 described thermo-electric circuit, consisting 
 of two wires, one of iron, the other of copper, 
 twisted together at one end, and that tioA 
 
TH 
 
 TH 
 
 placed in the furnace, or other place to be 
 tested. The wires are long enough to reach 
 to a distant apartment, of which the tempe- 
 rature is uniform, where the ends of the wires 
 are connected to a galvanometer, to which a 
 scale of degrees is attached. As the furnace 
 varies in temperature, so will the galvano- 
 meter indicate the changes that occur. The 
 reason the wires are so long is, that one end 
 may remain cool,, however hot the other may 
 be made. 
 
 Thermo-Electricity. a portion or de- 
 partment of the general science of electricity, 
 which explains the effects which arise when 
 electric currents are put in motion by means 
 of heat, as explained, when treating of the 
 various apparatus, under the words Melloni, 
 Marsh, Seebeck, Thermo-electric Circuit, 
 
 Thermo-Electrics. Metallic bodies, the 
 union of which show the effects attributed to 
 thermo-electricity. The following arrange- 
 ment considers each as positive to those below 
 it, when a single pair only is used ; but ne- 
 gative to all below it, when several pairs of 
 metals are employed. Therefoie to construct 
 any thermo-electric apparatus, those two 
 metals will cause the greatest effect which are 
 farthest from each other in the list. Galena, 
 bismuth, mercury, nickel, potassium, palla- 
 dium, cobalt, manganese, tin, lead, brass, 
 rhodium, gold, copper, silver, zinc, cadmium, 
 plumbago, iron, arsenic, antimony. 
 
 Theumo-Electrometer. (See Clarke.) 
 Thermometer. An instrument for ascer- 
 taining the exact degree of heat which any body 
 possesses. The thermometer ap- /?=*s. 
 plies chiefly to the lower degrees p-// ^ \^ 
 of heat ; for indicating high tempe- 
 ratures, the instrument is usually 
 called a pyrometer. The ordi- 
 nary thermometer consists of a 
 narrow tube of glass, closed at 
 the top, and with a much larger 
 bulb below. This, and also a 
 part of the tube, is filied with 
 mercury, (or in other cases with 
 colored spirits of wine.) The 
 tube is fastened to a narrow 
 board or piece of ivory or metal, 
 which is so graduated as to 
 form a scale, proceeding from 
 the heat of boiling water, which 
 forms the upper mark, to about 
 40° below the freezing point, so 
 that the mercury ascends or de- 
 scends as it becomes hotter or 
 colder. As spirits boil at a much 
 less degree of heat than water, the scale at- 
 tached to spiritthermometers is less extensive. 
 Brewing thermometers, and those attached to 
 hot-houses, or to ascertain the state of the 
 weather have a still more limited scale ; the 
 scale at all times being adapted to circum- 
 
 stances. The varieties of thermometers are 
 almost endless ; a spirit thermometer is one 
 the bvdb of which is filled with spirits of 
 wine, colored with cochineal. This will as- 
 certain degrees of cold greater than mercurial 
 thermometers, but no degree of heat above 
 180°, as Spirits of wine boil at that heat. 
 The mercurial thermometer is filled with 
 mercury, and is applicable to heats between 
 40° below zero on Fahrenheit's scale, when 
 mercury freezes, up to 600° above the fneezing 
 point when mercury boils. An air thermo, 
 meter or one containing a bulb of inclosed 
 air, is, owing to its readiness of expansion 
 and contraction, very serviceable to note sud-* 
 den and trivial changes. (See Air, Boyle, 
 Leslie, Photometer, ^thioscope, Cryopho- 
 rus. Differential Thermometer, ^c.) 
 
 Thermometer, Balance. (See Balance.) 
 
 Thermometer, Barometrical, (Seei?a- 
 rometrical. 
 
 Thermometer, CAemjcfl/. {See Chemical.) 
 
 Thermometer, Differential. Shows the 
 difference of expansion in the contents of two 
 tubes. (See Leslie, Air, and De Butt.) 
 
 Thermometer, Electrical. (See Kinners- 
 ley.) 
 
 Thermometer, Metalline. This is but 
 another name for pyrometer. (See Ferguson, 
 Regnier, Crighton, Breguet, and Houriet.) 
 
 Thermometer, (S^c^ica/. (See Cumming.) 
 
 Thermometer Scale. The graduated 
 scale which is attached to the stem of a ther- 
 mometer, in order that the degree of heat may 
 be noted. Two points, one of water just 
 boUing, the other of water on the point of 
 freezing, universally form two points from 
 which a scale of equal parts is constructed. 
 Reaumur, whose thermometer is used in 
 France, divided this space into 80 parts, be- 
 ginning at zero. Celsius's, the Swedish, or 
 centigrade thermometer, has the division of 
 100 parts, beginning also at zero ; and Fah- 
 renheit, whose thermometer is used in Eng- 
 land, called the freezing point of water 32** 
 above soro, and the boiling point 212°, or 
 180° above the other. 
 
 Thermometric Hygrometer. (See 
 Leslie.) 
 
 Thermoscope. a term used most com- 
 monly as synonymous with thermometer, but 
 differing from it in not offering to the eye 
 the exact degree of heat or cold which in- 
 fluences it. It is, therefore, but an imper- 
 fect thermometer. Although this is the true 
 meaning, yet thermometer and thermoscope 
 are often used synonymously. 
 
 Thermostat. The name of an apparatus 
 for regulating temperature in vaporization 
 distillation, heating baths and hot-houses, 
 ventilating apartments, &c., invented and pa- 
 tented, in 1831, by Dr. Ure. It proceeds 
 upon tiie principle of the unequal expansion 
 I caused by heat on various metals. The fol- 
 h H H 
 
 54 
 
TH 
 
 TH 
 
 lowing will show three among very numerous 
 applications of the instrument: — A, in the 
 first figure, is a compound bar, made of a rod 
 of steel and one of brass, united together. 
 The end at A is fixed to the inside of a dis- 
 tern, boiler, or apartment, A M L. The end 
 B is free to move downwards towards C> 
 which it does when the temperature is raised, 
 pulling down at the same time the lever D to 
 which it is connected by the rod B, raising 
 the contrary end to G, and with it any thing 
 attached to the rod which hangs down from G. 
 Suppose this is the damper 1, it will raise it 
 to H K, and if a regulator be fixed to N O, 
 it will turn that also, and in either case may 
 be made to regulate the temperature. 
 
 In the next figure, the metallic bars are se- 
 parated by the block at A, where they are 
 fixed. They are of unequal length, and their 
 ends C and E act upon the cross links DandF, 
 and through them upon the stop cot;k, in- 
 serted on the connecting link which joins 
 these cross pieces. The cock will therefore 
 be turned off or on in proportion to the wi- 
 dening of the end ; thus hot water, air, steam, 
 &c., may be admitted only as required. 
 
 In the next figure, the same principle is 
 applied to the register of an air stove. There 
 are two pair of bars connected in a manner 
 similar to the last to cross links. The bars 
 ore brass and steel, as before, and form two 
 pairs, the ends of each pair being united 
 together. When cold, the bars are nearly 
 straight ; but as they become hot they bend, 
 and by that flexure regulate the register. 
 
 Tholobate. That part of a building on 
 which a cupola is placed. 
 
 Thorina. a primitive earth, with a me- 
 
 tallic base, discovered in 1828, by Berzelius. 
 It is extracted from the mineral thorite, of 
 which it constitutes 58 per cent. When pure 
 it is a white powder, without taste, smell, 
 or alkaline properties. This earth consists 
 of 74-5 parts of the metal thorinum, com- 
 bined with 100 of oxygen. It is of no known 
 use in the arts. 
 
 Throttle Valve. A contrivance to regu- 
 late the supply of steam to the cylinder of a 
 steam engine. It is situated between the 
 boiler and the cylinder. In locomotive en- 
 gines it is worked by the engine man ; in 
 stationary engines by the governor. Its form 
 and mode of action is as follows : — A is the 
 valve inside the pipe. B, C, and"D, are 
 levers outside the pipe. B is connected by 
 an axis with the centre of the valve. F G is 
 the steam pipe. In the position shown, the 
 valve rests quite across the pipe, consequently 
 no steam can pass ; but if the end E be thrust 
 down, the end D will be raised in like pro- 
 portion, and pulling up the end of B to 
 which it is attached, will alter the direc- 
 tion of A, so that instead of standing up and 
 down it will be turned sideways, and conse- 
 quently an opening will be made on each side 
 of the pipe, through which the steam will 
 pass onwards. 
 
 Thorough Carved Work. Carved work 
 which is entirely cut through, better called 
 pierced work. 
 
 Thorough Lighted. An apartment 
 which has windows on two opposite sides. 
 
 Thorough Stones. Stones which extend 
 quite from one side of a wall to the other. 
 
 Thunder. The noise occasioned by the 
 explosion of a flash of lightning passing 
 through the air, or it is that noise, which is 
 excited by a sudden ex]ilosion of electi-ical 
 clouds, which are therefore called thunder 
 clouds. Perhaps it may be better defined, 
 as occasioned by the collapse of portions of 
 the air which have been rent asunder by the 
 passage of a flash of lightning. 
 
 Thunderbolt. When a thunder storm is 
 at its greatest violence, and the lightning is 
 so powerful as to occasion destruction to any 
 object, it is said by the ignorant to be a 
 thunderbolt, they cherishing the idea that a 
 stone, or semi-metallic substance, at that 
 time falls ; and as if in evidence of the truth 
 of the opinion, stones to which this name is 
 given are often preserved. These Lave no 
 connection with the phenomenon of thunder 
 
TI 
 
 TI 
 
 and lightning, but are nodules of the sul- 
 phuret of iron. These are extremely com- 
 mon on the Downs in Sussex, Wiltshire, 
 and other counties ; so common indeed that 
 they are collected by bushels for the manu- 
 facture of the sulphate of iron. 
 
 Thunder House. An electrical appara- 
 tus in the form of the gable end of a house, 
 made to show that the cause of injury to 
 houses by lightning is the absence of a good 
 and continuous conductor for the lightning 
 from the summit to the ground. Suppose 
 we take a board, like B B, made of baked 
 wood, which is a non-conductor, as much so 
 as the bricks of a house, and that we attach 
 a wire C down the board ; such wire being 
 terminated above by a ball A, and below by 
 a hook E, and having two interruptions in it, 
 of an inch in space each, where we cut a 
 square hole in the board to receive two small 
 squares of baked wood, D and E ; each square 
 fitting very loosely, and having a wire down 
 it. Placing the squares so that this wire 
 unites all the ends of the long wire, as at E, 
 of course the conductor would be continuous, 
 and an electric shock sent down the wire 
 would not disturb either square ; but if one 
 of the squares be placed so that its wire lies 
 across the board, as is seen at D, then the 
 whole conductor not being continuous, the 
 shock will throw out the piece D, which has 
 been placed across, exactly m the same man- 
 ner as stones, bricks, &c., are thrown out 
 from buildings by lightning. 
 
 Tide. A periodical motion of the waters 
 of the sea, called also the flux and re-flux^ 
 or the ebb and flow. When the motion 
 of the water is against the wind, it is called a 
 windward tide ; when wind and tide go the 
 same way, leeward tide ; when it runs very 
 strong, it is called tide-gate. The tides are 
 found to follow periodically the course of the 
 sun and moon ; hence we look to the attrac- 
 tion of these luminaries as their cause, par- 
 ticularly to that of the moon. The interval 
 between two higli waters is about 12 hrs. 25' 
 or half of the moon's daily circuit round the 
 earth. _ The tides have a particular reference 
 
 to the position and phases of the moon, and 
 her distance from the earth. They have also 
 a dependence upon the position of the sun 
 and moon to the earth. To explain the cause 
 of the tides, the following diagram will assist 
 us: — 
 
 The larger body is the earth ; the two 
 smaller bodies are the moon in different po- 
 sitions. The earth is naturally within the 
 sphere of the moon's attraction, in conse- 
 quence of which the waters of the earth, 
 (the only moveable part of it,) will be ga- 
 thered together towards that side where the 
 moon is placed, forming a prominent surface 
 of water, as is represented at H, occasioning 
 high water at that place, and consequently 
 low water at B and F, because these are the 
 parts from which the water is attracted. Now 
 as the earth turns round on its axis in twenty- 
 four hours, so it turns from beneath this 
 accumulation of waters, and in six hours 
 after high water the point H will turn round 
 to A F, and consequently have low water. 
 But the moon will during this six hours have 
 gone a portion of her monthly course around 
 the earth, and have arrived at P ; therefore it 
 will take rather more than six hours before H 
 arrives at low water, so that two whole tides 
 occur in 24 hours, 48 minutes, instead of 
 twenty-four hours, and high water at any 
 place is so many minutes later each succeeding 
 day. The time of high water is not exactly 
 when the moon is on the meridian of a place, 
 but three hours after, because the waters being 
 once put in motion cannot stop immediately ; 
 the cause which raised them is removed, but 
 by their momentum they continue to rise for a 
 considerable time afterwards. The reason why 
 there are two tides in the day and not one, 
 or why the waters are accumulated about N 
 is said to be this, that the moon attracts the 
 waters on the side nearest to her, away from 
 the earth ; and also attracts the earth itself 
 away from the water on the contrary side. 
 If therefore she attracted the waters nearer 
 to her 40 feet, and the earth 20 feet, there 
 would be an extra accumulation of 20 feet 
 water on each side : that is at H and at N. 
 
TI 
 
 TI 
 
 Tide, Neap and Spring. These arise 
 from the attraction of the sun, uniting with 
 or opposing the attraction of the moon on the 
 waters of the earth. The power of the sun's 
 attraction to us is about \ that of the moon. 
 Now at the time of new moon, the earth, 
 moon, and sun, are in a straight line. See 
 the following diagram, where S is the sun, 
 and M the moon. If the moon attract the 
 water 25 feet, the sun would attract 5 feet, 
 and the whole tide would be 30 feet ; and 
 this being more than what is owing to the 
 moon alone, it would be a spring tide. Next, 
 suppose a week has elapsed, and the moon 
 occupies the position B, then the sun and 
 moon would oppose each other, and the rise 
 of the waters would be less than ordinary. 
 In the case we have supposed, the waters 
 would rise only 25 — 5 or 20 feet, occasioning 
 what is called a neap tide. The seime thing 
 would hold good at full moon, and at the 
 third quarter. 
 
 Tide Gauge. Any contrivance to ascer- 
 tain the time of high water, or the height to 
 which the tide rises at any place. The sim- 
 plest tide guage is a post with numbers at a 
 foot distance from each other painted upon it. 
 If it be desirable to ascertain the height of 
 the water at any place inland, as at a distant 
 observatory, a pipe must be laid on, one end 
 of which extends to the water in the sea or 
 river ; then the pipe carried under ground, 
 being at no part placed higher than the level 
 of low water ; its other end may terminate in 
 a well, upon the sides of which a gauge of 
 feet is painted. The water will rise and fall 
 in the well in the same way as it does in the 
 open sea or river. 
 
 Tide, or Guard Lock. A lock situated 
 between an entrance basin and a canal, har- 
 bour or river, and forming a communication 
 between them. It is furnished with double 
 gates, whereby craft can pass them either way 
 at all times of the tide. 
 
 Tide Mill. A mill which is moved by 
 tidal water. Tide mills may be moved by 
 the water rushing into a dam when the tide 
 is rising, or when the water thus accumulated 
 is afterwards flowing out, or both. 
 
 Tide Wheel. (See Water WJieel.) 
 
 Tie. Any thing to bind together what has 
 a tendency to separate. 
 
 Tie Beam. In a roof is that beam which 
 
 extends from one wall to the opposite, and 
 connects together the lower extremities of 
 the rafters. 
 
 Tile. An artificial stone or broad thin 
 brick, made of dried earth, and burnt in a 
 kiln, used in covering buildings or for paving. 
 Tiles have various names, according to their 
 surface, shape, use, or situation. Those of 
 a rectangular form, with a flat surface, are 
 denominated plane tiles and crown tiles. 
 Those of a semi-cylindrical form are called 
 ridge tiles or hip tiles. Others from their 
 use are called gutter tiles, paving tiles, drain 
 tiles, &c. The hollow-surfaced tiles used to 
 cover houses are called pan tiles. 
 
 Tile Ckeasing. Two rows of tiles placed 
 horizontally under the coping of a wall, and 
 projecting about three inches from the sur- 
 face, for discharging the rain water therefrom. 
 
 Tilted Steel. (See Steel.) 
 
 Tilt Hammer. A large hammer, lifted 
 by machinery, to forge iron or steel. It is 
 shown beneath. A is supposed to be a wheel, 
 having upon its circumference a certain num- 
 ber of breaks ; each of which catches hold 
 of the lever F I, during its passage past it. 
 C is a fly wheel, attached to A. ' B is an up- 
 right shaft, supported above the hammer, 
 and upon which the hammer turns, as upon 
 a centre of motion. It may, however, be 
 supported by the strong frame work D. I is 
 the head of the hammer. H the anvil. As 
 the wheel A revolves, it presses down the end 
 F with so sudden a jerk, that the under part 
 of F strikes forcibly against the cushion G, 
 in consequence of which the end A falls with 
 considerably greater force upon the anvil 
 than it otherwise would do. 
 
 Timber. A term applied to trees after they 
 are felled ; also wood-work iri general. The 
 main beams of a house or other buildmg, 
 ship, &c,, are usually called the timbers 
 of it. 
 
 Time. A certain degree of duration , marked 
 by periods or measures, chiefly formed from 
 the motions of the heavenly bodies ; as a 
 year, a month, and a day. It is necessary 
 for various purposes to consider time as of 
 several kinds. Absolute time has no reference 
 
TI 
 
 TO 
 
 to objects or their motion, but has flowed on 
 uninterruptedly and equably from the be- 
 ginning of all things, and shall so pass on till 
 the end, when time will merge into eternity. 
 Relative time is the sensible measure of any 
 duration, usually calculated by means of some 
 standard of motion, as the course of one of 
 the heavenly bodies, or the vibration of a 
 pendulum. Relative time is distinguished 
 into astronomical and civil. Astronomical 
 time is that measured by the heavenly bodies 
 only. Civil time is the former accommo- 
 dated to civil uses, and formed into distinct 
 periods, such as years, days, hours, &c. 
 Again, astronomical time is either apparent 
 solar or true ; mean or sidereal. Apparent 
 solar time, otherwise called true time, is that 
 which is estimated by the sun's passage over 
 the meridian of any place, and which is some- 
 times sixteen minutes sooner or later than 
 that shown by a good clock. Mean time is 
 the apparent solar time corrected to the ave- 
 rage time or to the time indicated by the 
 clocks. Sidereal time is that which is esti- 
 mated by the passage of the same star over 
 the meridian of any place, and which is the 
 most exact measure of time we are acquainted 
 with, the most accurate observations never 
 having detected in it the least inequality. 
 
 Time, Equation of. (See Equation.) 
 
 Time Keepers. Any instruments used 
 for measuring time ; such are hour glasses, 
 clypsydrse, clocks, chronometers, sun dials, 
 &c. 
 
 Tin, a metal which in its pure state has 
 nearly the color and lustre of silver. It is 
 very malleable, exhales on friction a peculiar 
 odour, is flexible, and when bent emits a 
 crackling sound, called the creaking of tin. 
 It melts at 442" Fahr. When heated it ab- 
 sorbs oxygen with rapidity, and changes 
 finally into a white oxyde, called putty of tin. 
 
 Tin Plate. A very thin sheet of iron, co- 
 vered on both surfaces v/ith tin, so as to be 
 white and shining ; for this reason often 
 called white iron or tin plate. It is exten- 
 sively used for what is commonly called tin- 
 ware, such as saucepans, mugs, watering 
 pots, kettles, &c. 
 
 Tin Plate, Crystallized. (See Moiree 
 Metallique.) 
 
 Tinning. The art of covering another 
 metal with a surface of tin. It is performed 
 as follows : — To tin copper or brass : Boil 
 6 lbs. of cream of tartar, 4 gallons of water, 
 and 8 lbs. of grain tin. Put in the articles 
 to be tinned, and continue boiling until they 
 are sufficiently covered. To tin iron : First 
 make it bright, then soak it in an acid, such 
 as sour whey, sour grains, or something 
 similar ; rub it over with sal ammoniac, and 
 dip it in melted tin. Saucepans, &c. of cop- 
 per are first well cleaned ; then melted tin 
 and sdi ammoniac are put into them ; then 
 
 put on the fire, and when the tin is melted 
 they are turned about until it adheres. 
 
 Tin, Butter of. The perchloride of tin, 
 
 TiNCAL. Crude borax. 
 
 Tinctorial Matter. The same as co- 
 loring matters, or the colors given out by va- 
 rious animal and vegetable matters, when 
 soaked or boiled in a liquid. 
 
 Tincture. Dilute alcohol, impregnated 
 with the active principles of either vegetable 
 or animal substances. 
 
 Tinge. A very faint tint or color. 
 
 Tin Glass. Bismuth. 
 
 Tints. Uniform, thin, delicate colors, 
 laid on to a painting, mostly in an extended 
 surface, so as to give it a uniform appearance. 
 Also we speak not merely of the tints of a 
 picture, but of any natural object equally 
 colored, as the blue tint of the sky, the 
 bright tints of autumn, &c. 
 
 Titanic Acid. The peroxyde of titanium. 
 It is called an acid merely because it unites 
 with the alkalies. 
 
 Titanium, A rare metal, discovered by 
 Klaproth, in 1794, in a mineral called me- 
 nachanite. Also traces of this metal may be 
 found in many varieties of iron. It is very 
 brittle, so hard as to scratch steel, and of 
 little specific gravity, It will not melt in the 
 heat of any furnace, nor dissolve when crys* 
 tallized even in nitro-muriatic acid, but only 
 when in fine powder. It has not been ap- 
 plied to any use ; calcined with nitre, it 
 becomes oxygenated, forming a titanate of 
 potass. 
 
 Tolu, Balsam of. This substance is ob- 
 tained from the toluifera balsamum, a tree 
 which grows in South America. It comes to 
 Europe in small gourd shells. It is of a red- 
 dish brown color ; of a fragrant odour, which 
 it imparts to v/ater by distillation, and to 
 alcohol by solution. 
 
 Tombac, or White Copper. An alloy 
 formed of variable proportions of copper, 
 arsenic, and tin. Red tombac is made by 
 fusing 5^ lbs. of copper, and then adding 
 ^ lb. of zinc. It is more durable than copper. 
 
 Tone. In painting, a tenn employed to 
 designate the prevailing hue or degree of 
 harmony in coloring in a picture. Thus we 
 say, this picture is of a dull tone, of a lively 
 tone, of a clear tone, &c. Tone is not pre- 
 cisely synonymous with tint ; the latter re- 
 lating rather to the mixture of colors, and 
 the former to their effect. 
 
 Tongue. A projecting part at the edge of 
 a board, to be inserted into a groove ploughed 
 in the edge of another. 
 
 Tongue. (See Egg.) 
 
 Tools. Implements used by artificers in 
 the formation of the various articles they 
 fashion or manufacture. 
 
 Tooth op a Wheel, is a projection on 
 the edge of it, either parallel, oblique, or 
 
TO 
 
 TO 
 
 perpendiculBr to the axis, and by means of a 
 series of which motion is communicated to 
 the different parts of a machine. The teeth 
 of wheels may be either external or internal, 
 as in the following cut : — 
 
 Tooth Ornament. A decoration pecu- 
 liar to early English buildings. It has seve- 
 ral varieties, some very ornamental. (See 
 Dog Tooth.) 
 
 Toothed Wheel. A wheel with teeth cut 
 out around the circumference. 
 , Topaz. A gem or precious stone of a yel- 
 lowish, or sometimes of a rose red color. 
 
 Topiary Work. A sort of garden orna- 
 mental work, which consists of giving all kinds 
 of fanciful forms to arbours and thickets, 
 trees and hedges. 
 
 Tornado. A sudden and violent gust of 
 wind arising from the shore, and afterwards 
 veering round all the points of the compass. 
 These are very frequent on the coast of 
 Guinea. 
 
 Torricellian Experiment. A famous 
 experiment, which ended in the discovery of 
 the barometer, by which the philosopher 
 Torricelli demonstrated the pressure of the 
 atmosphere, in opposition to the doctrine of 
 motion, which pressure he showed was able 
 to support only a certain length of mercury 
 or any other fluid in a tube. 
 
 Torricellian Tube. The same as the 
 barometer tube. 
 
 Torricellian Vacuum, is that made in 
 the barometer tube, between the upper end 
 and the top of the mercury. This is, per- 
 haps, never a perfect and entire vacuum, 
 though it is certainly the nearest to one that 
 human ingenuity can devise. To procure it, 
 take a tube of glass, 33 inches or more in 
 length, and closed at one end ; fill it with 
 mercury, taking care that no bubbles of air 
 remain in the tube ; then putting the finger 
 over the open end, carefully invert the tube 
 into a basin of mercury. Upon removing 
 the finger, the mercury will sink in the tube, 
 according to the buoyancy of the atmosphere, 
 until its upper end stands at a height of from 
 27 to 32 inches above the surface of mercury 
 in the basin. The space void of mercury at 
 the top of the tube will be the vacuum 
 Bought, and the method adopted to produce 
 it is the Torricellian experiment. 
 
 Torrid Zone, is the middle of the five 
 zones into which the surface of the earth is 
 supposed to be divided, and the hottest of 
 
 them ; the sun being at all times of the year 
 vertical over some part of it. It extends 23^° 
 on each side of the equator, or to the tropic 
 of Cancer northward, and the tropic of Ca- 
 pricorn southward. 
 
 Torsion. A twisting like that of a rope 
 or thread. 
 
 Torsion Electrometer. (See Coulomb.) 
 
 Torsion, Force of. A term applied by 
 Coulomb, in some of his experiments, to de- 
 note the effort made by a thread, which has 
 been twisted, to untwist itself again. 
 
 Tortion Galvanometer. (SeeUtVcAie.) 
 
 Torso. The name given by artists to those 
 mutilated statues, of which nothing remains 
 but the trunk. The word torso is also ap- 
 plied to those columns, the shafts of which 
 are twisted. 
 
 Tortoiseshell. The plates which form 
 the shell or covering of the Testudo imbri" 
 cata. The number of plates which cover this 
 animal are thirteen. They vary in thickness 
 from -^ to ;|^ of an inch, according to the age 
 and size of the animal, and weigh altogether 
 from 5 to 25 lbs. Tortoiseshell is used for 
 combs, boxes, and numerous ornamental 
 trinkets. 
 
 Torus. A round moulding, used in the 
 base of columns, &c. It is the same as a 
 bead, but larger and differently applied. In 
 the cut A and B is each a torus. 
 
 ..../ 
 
 UuUUUuL 
 
 d 
 
 TouRBiLLiON. An ornamental fire-work, 
 peculiar for turning round when in the air, so 
 as to present the appearance of a scroll of fire. 
 The cases are 7 or 8 diameters of them in 
 length, made like rocket cases. The com- 
 position to fill them, and the manner of 
 filling them, is also like that of rockets, except 
 that 1 inch of clay is first rammed in ; then 
 the composition is to reach to within an inch 
 of the top, and clay to fill up the remainder ; 
 when rammed, pinch up the end before left 
 open. Balance each case on the finger, and 
 at the centre of gravity, thus found, tie a cross 
 stick, as represented; then bend the ends of the 
 stick up a little, so that they shaU be rather 
 rounding, that the tourbiUion may spin upon 
 the centre of them. Then bore a hole near the 
 clay, on each side of the case, and two holes 
 underneath, and connect the holes with quick 
 match. When to be fired, place them on a 
 board, and set fire to the quick match, ia 
 
TR 
 
 TR 
 
 consequence of which fire will issue from 
 four holes ; that from the two lower holes 
 will drive the tourbillion into the air, and 
 that from the side holes will spin it i ound. 
 
 Tourmaline. A mineral, of somewhat 
 peculiar principle, particularly that when 
 heated it shows, at different parts of it, elec- 
 tric poles ; a fact which was known to the 
 ancients, who called the stone lyncurium. It 
 is also doubly refractive, for which and other 
 reasons it is used in experiments on the 
 polarization of light. 
 
 Tow. Coarse undressed hemp or old rope 
 reduced to the state of filaments. This last 
 is more generally called oakum, and is used 
 to fill up the chinks 8md seams of ships. 
 
 Tower. A lofty building, mostly round 
 or polygonal ; used to strengthen the angles 
 of a fortress, to hold the bells of a church, 
 as a place of observation, &c. 
 
 Tracery. The ramified stone-work in the 
 upper part of Gothic windows, connecting 
 the mullions with the frame. 
 
 Tracing Instrument. This is very si- 
 milar to the profile or silouette instrument 
 already described ; (see Silouette,) for which 
 it may be substituted, even for the taking of 
 likenesses. The chief difference is that the 
 shorter end of the rod or tracer is curved, as 
 shown in the figure ; so that the point A may 
 trace over the outlines of an object, which 
 rests upon the frame work ; at the same time 
 B traces it of a larger size, on a sheet of 
 paper at a distance, and vice versa. 
 
 shrubs. It is firm, rather heavy, tough, and 
 difficult to powder, unless previously heated ; 
 of a pale, yellowish white color, sometimes 
 brownish ; has no smell, and but little taste ; 
 dissolves in water very slowly, and becomes 
 mucilaginous. It is used chiefly by confec- 
 tioners to make gum paste, to harden lozen- 
 ges, &c. ; also as a dressing or stiffening 
 material to some textile fabrics. 
 
 Trail's Register Thermometer. This 
 is a single spirit thermometer, in which a 
 column of mercury, one- 
 third of an inch in length, 
 is introduced. At each 
 end of this column lies an 
 index of fine steel wire, 
 gilt. The variations of bulk 
 which take place in the 
 spirit will move the column 
 of mercury, and by this the 
 indices are pushed in oppo- 
 site directions, but will re- 
 main at the highest and 
 lowest points to which they 
 are driven by the mercury. 
 The indices are brought 
 back again into contact 
 with the mercury by means 
 of a magnet. 
 
 Trajectory. A term generally used for 
 the path of any body moving either in a void 
 or in a medium, which resists its motion, or 
 even for any curve passing through a given 
 number of points. Thus astronomers speak 
 of the trajectory of a comet, a planet, &c. 
 
 Tram. The name given to coal waggons 
 in the north ; hence the words tram road. 
 
 Trammel. In mechanics, an instrument 
 used by artificers to describe ellipses. It 
 consists of a cross, with two grooves at right 
 emgles to each other, and a beam, containing 
 two pins that are made to traverse in the 
 grooves by the revolution of the bar ; the 
 bar carries a pencil that describes the ellipse. 
 
 Tracing Paper. (See Paper.) 
 Traction. The drawing of one body after 
 another. 
 
 Tractive Power. The force necessary 
 to drag any thing along a road or other sur- 
 face, overcoming the friction occasioned by 
 the transit. 
 
 Trade Winds. (See Winds.) 
 Tragacanth. a gum, also called gum 
 adracant and gum dragon, is the produce of 
 Astragalus tragacantha, and some other 
 
 Tram Road, or Track Way. A road- 
 way, consisting of narrow tracts, plates, or 
 rails, of wood, stone, or iron, upon which 
 waggons are made to pass backwards and 
 forwards, for the conveyance of wood, coals 
 from the pit, &c. 
 
 Transcendental, is a term applied to 
 any equation, curve, or quantity, which can- 
 not be represented or defined by an alge- 
 braical eauation of terms, with numeral and 
 
/w ^^ lUUU^ Sr Liu . ^nclU^e ^ ^^^^rr^ 4^^^>^ my 
 
 TR 
 
 TR 
 
 determjnate indices. Transcendental quan- 
 tities, therefore, include all exponential, lo- 
 garithmic, and trigonometrical formulae, by 
 which these quantities can be expressed. 
 
 Transept. The tranverse division of those 
 churches which are built in a cross form. 
 The transept runs north and south ; the nave 
 and choir east and west. 
 
 Transferography. An art invented by 
 Mr. "Williams for the copying of inscriptions, 
 from ancient tombs, tablets, &c., which it 
 does with the greatest accuracy. It is done 
 IS follows : — Provide a quantity of thin 
 pliable paper (thin printing paper is the best.) 
 A sheet of this is to be laid over the object 
 to be copied, and fixed there steadily by paste, 
 applied in two or three places at the corners 
 or edges. Over this is laid a black tracing 
 paper, made by rubbing paper over with lamp- 
 black and soap, with a little water ; the black 
 side is of course to be laid inwards. Then 
 rubbing the back of this second sheet of pa- 
 per, with a smooth wooden knife, the pres- 
 sure will transfer the black ground on to the 
 first sheet of paper, wherever the surface of 
 the inscription underneath is flat ; but where 
 there are any depressions, no transfer of the 
 black will take place, consequently when done, 
 the under sheet of paper will have in white 
 every indentation of the stone beneath, while 
 the general surface will be black. 
 
 from the air pump, and set aside, that the 
 continued result of the experiment, whatever 
 it may be, may be noted afterwards, and the 
 air pump in the interim used for other 
 purposes. 
 
 Transferrer. An instrument used with 
 the air pump, as a moveable portion or plate, 
 for numerous purposes of experiment. There 
 are single transferrers and double transfer- 
 rers ; the latter of which is shown annexed. 
 It consists of two plates, ground truly flat, 
 and having pipes beneath, communicating 
 with each other by connecting tubes, and a 
 large pipe and cock below, which fits on to 
 the table of the air pump. If a glass re- 
 ceiver be placed over each transferrer plate, 
 they may be exhausted of air, and the lower 
 cock being turned, they may be removed 
 
 Transferring. The passing of one thing 
 to another. The term is particularly applied 
 to the printing of a design first upon paper, 
 and afterwards placing that printed paper 
 upon the article for which the design is in- 
 tended ; the paper being afterwards removed 
 either by rubbing, burning, or other method, 
 the design only remains, and looks as if it 
 were originally printed upon the article. In 
 this manner, plates, basins, and other crockery 
 and china ware are printed. So also litho- 
 graphic and other prints, may be transferred 
 to wood, by first soaking the print in water, 
 then varnishing the wood, sticking the print 
 face downwards upon the varnish, while it is 
 yet wet, and then carefully rubbing the paper 
 from the back of the print. Wlien as much 
 as possible of this paper has been removed, 
 and the whole is dry, a coat of varnish over 
 it brings up the design, almost as clearly as 
 in the original print. In lithography and 
 copper or steel engraving, a transfer is the 
 impressing a drawing, or writing upon a stone 
 or metal plate. In lithography, a paper, 
 called transfer paper, is previously prepared 
 by washing a thin paper over with starch, 
 and afterwards glazing it. This being drawn 
 upon by lithographic ink is wetted, placed 
 upon the stone to be used, and the whole 
 covered over and passed through the press. 
 The pressure here given to it transfers the 
 ink from the paper to the stone, as if it were 
 originally placed there. A transfer in the 
 art of engraving is the drawing made on 
 paper with chalk or black lead pencil. This 
 being laid over the ground upon the plate, 
 (see Etching,) and passed through the press, 
 transfers the drawing to the ground of the 
 plate, where it may be afterwards etched. 
 
 Transformation. In geometry, is nearly 
 the same as reduction, being used to denote 
 the changing of any proposed figure to a 
 diJBTerent one of equal surface or solidity. 
 
Transformation of Equations, in algebra, 
 is a method of changing one equation to 
 another form, but one of equal value. 
 
 Transit. In astronomy, signifies the pas- 
 sage of any planet over a fixed star or the 
 sun ; and of the moon covering or moving 
 over any planet. 
 
 Transit Instrument. In astronomy, 
 is a superior kind of mounted telescope or 
 theodolite, for the purpose of noting accu- 
 rately the transits of Mercury and Venus. 
 
 Transmission. Passage through a body, 
 as of the rays of light through transparent 
 objects, the transmission of the electric fluid 
 through good conductors, &c. 
 
 Transmutation. In geometry. (See 
 JVansformation.) 
 
 Transoms. The iron or stone bars which 
 run horizontally across a window, dividing it 
 into stories. 
 
 Transparency. A transparent painting, 
 made by painting on fine linen, thin paper, 
 silk, &c., with transparent colors. It is illu- 
 minated by lights skilfully introduced behind, 
 and produces a striking effect, either to 
 illustrate scientific lectures, or on occasions 
 of public rejoicings. Transparency, in paint- 
 ing, is when the painting is so executed as 
 that the object appears light, lively, and as 
 it were in reality transparent ; such, for 
 example, as water or the air. This effect 
 is produced chiefly by the use of varnish, 
 added to such colors as have not much body 
 or opacity. 
 
 Transparent. Any thing which can be 
 seen through. 
 
 Transparent Colors. Certain colors 
 are thus called to distinguish them from 
 others which are opaque. Among the trans- 
 parent colors are lake, verdigris, Indian 
 yellow, gamboge, sap green, Prussian blue, 
 burnt umber, sienna, &c. Among the opaque 
 colors are vermillion, emerald green, Naples 
 yellow, smalt, verditer, lamp-black, &c. 
 
 Transparent Paper. (See Paper 
 Tracing.) 
 
 Transparent Soap. (See Soap.) 
 
 Transposition. In algebra, is the bring- 
 ing any term of an equation over to the other 
 side of it, in which case the sign of the 
 quantity thus transferred is changed; viz. 
 from plus to minus, and from minus to plus. 
 For example, if a + x = d, then transposing 
 a, and changing its sign, we have a^—b = a; 
 and if on the other hand we have x—a = h, 
 then by transposition we have x=a-^h. This 
 operation is performed in order to bring all 
 the known terms to one side of an equation, 
 jmd all those that are unknown to the other 
 side, whereby the value of these last become 
 determined. 
 
 Transverse. Across, or a section or 
 measurement parallel to the ground, as the 
 transverse section of a building shows the 
 
 TR 
 
 various compartments of any floor looking 
 down upon it from above. The transverse 
 section of a tree is cut across the grain of 
 the timber. 
 
 Transverse Axis, or Diameter. In 
 the conic sections, is the first or principal 
 diameter passing through both the foci of the 
 curve. In the ellipse, the transverse is the 
 longest of all the diameters ; in the hyper- 
 bola it is the shortest ; and in the parabola 
 it is like all the other diameters, infinite in 
 length. 
 
 Transverse Vaults. Those which run 
 from windows, recesses, &c., into the main 
 and central vault. 
 
 Trapezium. In geometry, a four-s^ded 
 figure of which neither of the opposite sides 
 are parallel. 
 
 Trapezoid. A four-sided figure, of which 
 two of the opposite sides are parallel, but not 
 the other sides. Thus it is intermediate 
 between a parallelogram and a trapezium. 
 
 Traverse. In navigation, is the variation 
 or alteration of a ship's course, occasioned 
 by the shifting of the winds, currents, &c., 
 or a traverse may be defined to be a compound 
 course, consisting of several courses and dis- 
 tances ; thus a ship much driven about is 
 said to traverse, and the calculations neces- 
 sary to reduce these traverses to one recti- 
 linear course is called traverse sailing. 
 
 Treacle. A thick brown liquid, which 
 exudes from partially-refined sugar, it being 
 that part which has not crystallized. 
 
 Treadle. A lever attached to a crank, 
 which communicates motion to machinery by 
 the movement of the foot of the workman. 
 
 Trefoil. A Gothic ornament, representing 
 a clover leaf or three-leaved flower. 
 
 Trellice Work. Small bars of wood, 
 nailed together obliquely, and crossing each 
 other at regular intervals ; used for summer 
 houses, verandahs, &c. 
 
 Trenail. A wooden pin, employed in 
 timber frame work in situations where iror 
 
 55 
 
m::} 
 
 TR 
 
 bolts are considered objectionable, as under 
 water, in securing piles, ship's timbers, and 
 the like. They are mostly used in fastening 
 down the chairs of railways to the stone 
 blocks beneath ; holes being first drilled in 
 the stone, then oaken trenails are driven in, 
 and afterwards the iron pins which secure the 
 chairs. The utility of the wooden trenail is 
 to form a firm body around the iron pin. 
 
 Trepidation. A trembling. In the old 
 system of astronomy by Ptolemy, it denotes 
 a motion which was attributed to the firma- 
 ment, in order to account for several changes 
 and motions observed in the axis of the world, 
 and for which he could not account upon any 
 other principle. 
 
 Tressel. (See Trussel.^ 
 
 Tret. In commerce, is an allowance made 
 for waste, dust, &c., in various commodities, 
 at the rate of 4 pounds to every 104 pounds 
 purchased. 
 
 Trevithick's Steam Engine. This is 
 the first application of steam to the motion 
 of carriages, or the first locomotive engine, 
 and is the joint invention of Messrs. Trevi- 
 thick and Vivian. It is extremely compact 
 and simple in its construction. Steam is ad- 
 mitted to the lower part of the cylinder R 
 from the boiler ; this raises the piston B. 
 When it has reached the top, the communi- 
 cation between the boiler and the under-side 
 of the piston is shut off, and the steam which 
 has raised the piston escapes into the at- 
 mosphere. A passage is now, by means of 
 a four-way cock, made for the steam above 
 the piston, which drives it down, and the 
 esteam is again allowed to escape. From this 
 it is obvious, that the engine acts upon the 
 liigh pressure principle, and that its power 
 will be equal to the difference between the 
 pressure of the atmosphere and that of the 
 
 TR 
 
 steam. H in the cut is a pipe which con- 
 veys the spent steam to the chimney. It la 
 surrounded with a tube of hot water, to pre- 
 vent its condensation before it arriy^s at the 
 chimney, which would occasion it to nin back 
 as a liquid into the cylinder, and therefore 
 soon fill it. X are guide rods, for the piston 
 rod to work in. The connection between the 
 piston rod and fly wheel is not shown. 
 
 Tri-. Tris-. Trit-. Trito-. In chemi- 
 cal composition, has the same meaning as ter, 
 indicating three proportions of the base to 
 one of the solvent ; thus, the tri-sulphate of 
 copper contains three atoms of copper to one 
 of acid. 
 
 Triangle. In geometry, a figure bounded 
 by three lines, and consequently containing 
 three angles, whence its name. Triangles 
 are of various kinds, as plane or rectilinear, 
 or those that consist of straight lines, as A ; 
 spherical, or those which are bounded by 
 three arcs or great circles of the sphere ; or 
 curvilinear f which are such as are bounded by 
 any curved lines, as B. 
 
 Rane triangles are also distinguished by 
 their shape, and the nature of their con- 
 tained angles, as follows : — An equilateral 
 triangle has its three sides equal, as C. An 
 isosceles triangle is^ that in which only two 
 sides are equal, as D. A scalene or oblique 
 triangle is that which has its sides all unequal^ 
 as £. 
 
 A right-angled triangle contains one right 
 angle, as F. An acute- angled triangle has 
 its three angles acute, as G ; and an obtuse- 
 angled triangle has one that is obtuse, as H, 
 
 Spherical triangles are also divided into 
 right angled^ oblique, equilateral, isoscelcsy 
 
TR 
 
 TR 
 
 scalene, &c. They are also said to be quad- 
 rantal, when they have one side a quadrant. 
 Also two sides or two angles are said to have 
 the same affection when they are either both 
 greater or both less than a quadrant or 90° ; 
 and of different affections, when one is 
 greater than a quadrant, and one less. 
 
 Triangle, Isometrical, and Ruler. 
 Contrivances of Mr. Pease, of Woolwich, for 
 the more easy laying out of the lines of 
 isometrical figures. The rulers may be 12 or 
 14 inches long, and about If broad. The 
 triangle must be equilateral, and may be 
 4*92 inches each side. Both are made of box, 
 about i inch thick. They are graduated at 
 their edges, and it is obvious that as all the 
 angles in rectangular solids are by isometrical 
 perspective either 60°, or the supplement 
 thereof, (120°,) the above triangle requires 
 only to be slid along the ruler, and lines 
 drawn to follow its edges. The drawing is 
 then complete. To graduate them, both 
 must be marked in the ratio of 0'82 to 1, 
 that is, a space of 0*82 inches on the triangle 
 and ruler, will isometrically represent 1 inch 
 of the model to be delineated ; or if the ori- 
 ginal object be measured by feet, yards, or 
 any other magnitude, the same space will 
 also represent one of either of these measures. 
 Smaller parts are taken by the sub -divisions 
 between these larger isometrical divisions. 
 The following cross was drawn by aid of one 
 of these simple, but very useful instru- 
 ments :— 
 
 Triangular. Relating to a triangle. 
 
 Triangular Compasses. Such com- 
 passes as have three legs or feet, by which 
 any triangle or three points may be taken off 
 at once. (See Compasses.) 
 
 Triglyph. An ornament of the Doric 
 frieze, placed directly over each column, and 
 at equal distances between. It has two en- 
 tire evlnhs or triangular channels ""gra- 
 
 in it, and the sidei so cut away, that if two 
 triglyphs were put together at their union 
 would be a third channel 
 
 'H^mMT 
 
 \lMJiMMf 
 
 Trigon. The same as triangle. In as- 
 tronomy, the same as trine or aspect. 
 
 Trigonometry. The art of measuring the 
 sides and angles of triangles, whether plane or 
 spherical, hence called plane trigonometry 
 and spherical trigonometry ; or rather itis the 
 determining certain parts which are unknown, 
 from others that are known. It is used in 
 almost every part of practical mathematics, 
 navigation, and surveying, as very often by 
 this science only can altitudes and distance i 
 be ascertained. It is founded upon the prin- 
 ciple, that if one side of a triangle and two 
 of its angles be known, the rest may be de- 
 termined. Suppose we wish to ascertain th3 
 height of an inacessible rock, which we can- 
 not even approach near to, it is to be done 
 by trigonometry, as follows, referring to the 
 cut. Stand at any remote distance, as A, 
 
 and by means of a quadrant or theodolite 
 take the angle of altitude CAD. This sub- 
 tracted from 180° will give the angle CAB. 
 Then measure a straight line on the ground, 
 the longer the better, A B, and at B take a 
 second angle C B A. Then the base and ad- 
 jacent angles being known, the side C A is 
 easily determined by trigonometry. Then 
 suppose the line B A produced to D, and D C 
 drawn perpendicular to the base line, then we 
 should have the angles at D and A known, 
 and also the side A C, whence the perpen- 
 dicular height and the base from A to D is 
 easily determined. This added to A B gives 
 the distance of the object from B, as well as the 
 trigonometrical calculations the altitude of it. 
 ■" trisronometry the extent of woo^" ''"""^ 
 
TR 
 
 TR 
 
 surfaces of water, and estates, which cannot 
 be passed over, may be ascertained. It being 
 only necessary to find the area of the triangle 
 whose parts can be ascertained. 
 
 Trilateral. Any figure of three sides. 
 
 Trillion. With the English arithme- 
 ticians it signifies a million billions, repre- 
 sented by 19 figures in a row ; but with the 
 French it is a thousand billions, their billion 
 itself signifying a thousand millions, so that 
 it is represented by 13 figures in a row. 
 
 Trimmer. A small beam, receiving the 
 ends of several joints, and to which they are 
 trimmed or adjusted. 
 
 Trine Aspect. That situation of the 
 planets and stars to each other in which they 
 are at 120° angular distance. 
 
 Trine Dimensions. Three-fold dimen- 
 sions, or length, breadth, and thickness. 
 
 Trinomial. In algebra, any quantity of 
 three dimensions, as x- + xy + y^ or a + h — c. 
 
 Tripartition. a division into three equal 
 parts. 
 
 Triple. Three-fold, or multiplied by 
 three. 
 
 Triple Salts. Neutral salts, into the 
 composition of which three substances enter. 
 For example, common alum is a triple salt of 
 alumina, potass, and sulphuric acid. Its 
 proper name is, therefore, the sulphate of 
 alumina and potass. 
 
 Triplicate Ratio. The ratio of the 
 cubes of two quantities ; thus the ratio of a^ 
 to i^ is triplicate of the i-atio of a to b. 
 
 Tripod. Any sort of vessel, table, seat, 
 or instrument, having three feet. 
 
 Tripoli. An earthy mineral ; used as a 
 grinding and polishing substance. The most 
 valuable comes from Corfu ; a finer kind is 
 found in Derbyshire and other places, where 
 it is known as rotten stone. Unaccountable 
 as it may apjiear, yet the strong powers of 
 modern microscopes prove that all the tripoli 
 of the world is composed of the exuviae or 
 skeletons of insects, the species of some of 
 which still exist, and are even common. 
 
 Trisection. The division of any thing 
 into three equal parts. The trisection of an 
 angle, by which any angle is indicated, is 
 considered one of the impossibles of geometry, 
 equal in difficulty to the quadrature of the 
 circle, or the duplicature of the cube. 
 
 Trispast. a name given by the ancients 
 to a combination of three pulleys. 
 
 Trochilus. The same as scotia. 
 
 Trochlia. The Latin name for a pulley. 
 
 Trochoid. The same as cycloid. 
 
 Tropics. In astronomy and geography, 
 are two circles supposed to be drawn parallel 
 to the equinoctial line, one on each side of it, 
 at the distance of 23^° nearly. That on the 
 north is called the Tropic of Cancer, and that 
 on the south the Tropic of Capricorn. On 
 tlic terrestrial globe they bound the torrid 
 
 zone, and divide it from the north and south 
 
 temperate zones. 
 
 Trough, Galvanic. (See CruicX;shank.) 
 Trough, Pneumatic. (See Pneumatic.) 
 Trowel Point. An ornament in a wall, 
 
 string course, &c., made with the point of a 
 
 trowel, if in mortar ; or of the same form, 
 
 but larger, if in stone. 
 
 V^ 'H :^^ '> »iJ^«»mi^Pfi^iKnmi^!^mm^^nmKim 
 
 Truck. A wheeled carriage, moved by 
 hand, or as applied to rail-roads, it is the 
 name given to those low platforms upon 
 wheels, which are used to contain stage- 
 coaches and other vehicles carried along the 
 line of a rail-way, the passengers mostly 
 keeping their places. 
 
 Truckles. Small wheels, for diminishing 
 friction. 
 
 Trumpet, The name of an instrument ; 
 used either for the purpose of being heard at 
 a great distance, when spoken through, or of 
 applying to the ear for increasing sound, and 
 rendering it distinct ; the former being called 
 a speaking trumpet, the latter a hearing 
 trumpet. Both of them act by reverberating 
 the sound conveyed to them. If a speaking 
 trumpet be attached to the mouth of a gun 
 or cannon, the effect is astonishingly loud, 
 and might be used as a signal at sea. 
 
 Trundle, or Wallower. Awheel, which 
 instead of being moved by teeth or cogs is 
 furnished with round staves, upon which the 
 teeth of another wheel take hold, and thus 
 the trundle and wheel turn each other. That 
 which is a pinion in iron work is usually a 
 trundle in wooden machinery. 
 
 I 
 
 Truncated. That quality of a solid by 
 which a portion is cut off parallel to the base, 
 or perpendicular to the axis, supposing there 
 to be no base, as in crystals. In the foUowmg 
 cut, one figure has truncated edges ; the se- 
 cond, truncated angles ; and the third, a 
 truncated apex. 
 
TU 
 
 TU 
 
 Trunk. A vessel open at each end for the 
 discharge of water, &c. Also the shaft of a 
 column is sometimes so called. 
 
 Truss. Any method of uniting beams of 
 timber, so that they shall touch each other 
 only at certain points, and yet each mutually 
 support the other ; and all together unite 
 equally in sustaining a weight laid upon the 
 uppermost. (See Roof.) 
 
 Trussels. Props for the support of any 
 thing, the under surface of which is hori- 
 zontal ; each trussel consists of three or four 
 legs, with a horizontal piece at top. 
 
 Trussing Beam. The beam of steam 
 engines, previous to the time of Watt, was 
 composed of several beams of timber, of 
 immense size, firmly bolted together. These, 
 so cumbrous and expensive, were superseded 
 by beams constructed of a single piece of 
 timber, strengthened by slight trusses of iron 
 work, similar to that represented in Watt's 
 engine. (See Walt.) Iron beams are now 
 almost universally adopted. 
 
 Trussing Pieces. Those timbers in a 
 roof that are most pressed upon, consequently 
 those which are the nearest to the perpen- 
 dicular position. 
 
 Tube. A hollow cylinder, such as the tube 
 )f the telescope, barometer, &c. In the arts, 
 '.ubes, when of a large size and common ma- 
 erials, are usually called pipes. (See Pipe ; 
 Uso Capillary Tube.) 
 
 Tube of Safety. A tube open at both 
 inds, inserted into a receiver, the upper end 
 ;ommunicating with the external 
 lir ; the lower being immersed f^^ 
 n water. Its intention is to pre- 
 •ent injury from too sudden con- 
 lensation or rarefaction taking 
 Dlace during an operation. For if 
 a vacuum be produced within the 
 vessel, the external air will enter 
 through the tube, and if air be 
 generated, the water will yield to 
 the pressure from the confined 
 gas or gases. It is now more fre- 
 quently used of a curved form, 
 like that represented in the margin, 
 with or without a bulb in the up- 
 right stem ; the lower end of this, 
 instead of being immersed under 
 the liquid in the receiver as the 
 straight tube, is merely inserted into the tube. 
 The requisite tightness and pressure is ob- 
 tained by pouring a little mercury, or in 
 some cases oil into the tube ; this x-esting in 
 the legs of the lower bend, keeps the vessel 
 perfectly air-tight. (See Welter and Woulfe.) 
 Tufa. A soft sandy stone, of a calcareous 
 nature, porous, soft, light, and ductile ; 
 formerly used in the construction of some 
 edifices. It is said to be admirably adapted 
 for the formation of vaults. 
 Tudor Flower. An open crest or para- 
 
 pet formed of tre-foil leaves 
 the time of the Tudors. 
 
 much used, in 
 
 Tudor Rose. 
 the same period. 
 
 An ornament common to 
 
 Tula Metal. An alloy of silver, copper, 
 and lead. 
 
 Tumbling Bob. A name given to a 
 loaded lever or counterpoise weight, (Jften 
 attached to machinery to produce a backward 
 or contrary motion to that occasioned by the 
 machinery itself; for example, suppose in 
 the following cut, that C is connected with 
 a valve or cock, and that A D is a lever 
 attached to C, and turning on a centre at 
 the lower end of B. When the end A is 
 pushed down by the plug frame, it will open 
 the valve and lift up the tumbling bob D ; 
 when the plug frame rises, it may not lift up 
 the end A, yet the tumbling bob will, by its 
 weight, move the lever C contrariwise, and 
 thereby close the valve. 
 
 TuNBRiDGE Ware. Boxes, tea-chests, 
 dressing cases, trays, writing desks, and 
 numerous light and elegant works of the 
 like kind, made of ornamental woods, and 
 highly wrought and polished, the produce of 
 various manufactories in Tunbridge ; hence 
 all work of a similar kind is called Tunbridge 
 ware. 
 
 Tungstates. Salts of the tungstic acid. 
 
 Tungsten. A white, ponderous mineral, 
 found in Sweden, composed of- lime and a 
 
TU 
 
 TV 
 
 peculiar earthy substance, which from its 
 properties is called tungstic acid. The basis 
 of this acid was found to contain a metal 
 which has been named tunsten, and which was 
 obtained from the acid by calcining the acid 
 along with charcoal powder. 
 
 Tunnel. A subterraneous gallery or pas- 
 sage, excavated or dug through the earth for 
 the passage of a canal, road, or railway. 
 
 TuRBETH Mineral. The yellow sub- 
 deuto-sulphate of mercury. 
 
 Turkey Red. A brilliant red color, pro- 
 duced by madder upon cotton goods. 
 
 Turkey Stone. A species of slate, used 
 as a whetstone for the sharpening of tools. 
 
 Turmeric, or Indian Saffron. A root 
 brought from the East Indies, and employed 
 in making a yellow dye. The coloring mat- 
 ter it yields is abundant and brilliant, but not 
 durable. By chemists papers stained with 
 turmeric, or a solution of the coloring mat- 
 ter is used as a test for alkalies, which turn 
 the yellow into a brown color. By house- 
 wives, pastrycooks, &c., it is used forgiving 
 a yellow tinge to cakes and similar articles. 
 
 Turning. The art of carving or working 
 metals, ivory, wood, and other materials, so 
 as to give to them a circular, or in some in- 
 stances an oval form, using at the same time 
 an instrument, called a lathe, (see Lathe,) 
 one part of which gives the material a rota- 
 tory motion, while another part holds it tight, 
 and a third part, equally necessary, secures 
 the steadiness of the tool. (See Lathe, Rest, 
 Chuck, Slide Rest, 8fc.) 
 
 Turn-Cap. A chimney top, which turns 
 round with the wind. 
 
 Turn Bridge. (See Swing Bridge.) 
 Turn Plate, or Turn Table. A con- 
 trivance for removing railway carriages from 
 one line of rails to another. They are generally 
 made for crossings at right angles with each 
 other, but can be adapted to any angle that 
 may be required. 
 
 Turnsole. (See Archil.) 
 Turpentine. A transparent resinous 
 juice,^ flowing either naturally or artificially 
 from incisions cut in the bark of numerous 
 trees of the pine and fir species. The essen- 
 tial oil distilled from this resin is called spirit 
 or oil of turpentine, or turps. There are 
 various kinds of turpentine, as follows : — 
 Venice turpentine, procured from the larch 
 tree, (Pinus larix.) Common turpentine, 
 procured from the Scotch and the spruce fir, 
 (Pinus abies and Pinus sylvestris.) French 
 turpentine from the Pinus maritimus. Stras- 
 burg turpentine extracted from the Pinus 
 picea and Abies excelsa. Chio turpentine 
 from the Pistacia terebinthus; the tree which 
 produces the Pistacia nut; and, lastly, Ca- 
 nada balsam, which is a turpentine extracted 
 from tife Pinus canadensis and balsamea. 
 This kiua'is very pure and transparent. ] 
 
 Turnpike Staircase. A winding stair, 
 where the stairs are all made around a cen- 
 tral newel or post. 
 
 Turquoise. An ornamental stone of 
 bright blue color, found only in Persia, where 
 it is much esteemed. Bone turquoise is phos- 
 phate of lime, colored with oxyde of copper. 
 
 Turrell's Perspectograph. (See 
 Perspectograph.) 
 
 Turret. A small, slender, tall tower. 
 
 Tuscan Order. A Roman order of 
 architecture, with the general simplicity and 
 character of the Grecian Doric; divested 
 however of the flutes of the columns and the 
 peculiar ornaments of the entablature. It is 
 plainer and less exact in its proportions than 
 any other order, and used only for inferior 
 buildings or parts of buildings, such 
 porches, &c. The following cut shows the 
 Doric entablature, capital, and base to the 
 column : — 
 
 TuTANiA, or Britannia Metal. An 
 alloy, for the composition of which the fol- 
 lowing receipts are given : — To 4 ounces each 
 of brass and of tin, add when in fusion 
 4 ounces each of bismuth and of antimony. 
 This is the composition or hardening that is 
 to be added at discretion to melted tin, until 
 it has acquired the requisite degree of hard- 
 ness and color ; or else lib. of copper, 1 lb. 
 of tin, and 2 lb. regulus of antimony, with 
 or without a little bismuth. For the German 
 tutania take 2 drachms of copper, 1 ounce 
 regulus of antimony, and 12 ounces of tm. 
 For the Spanish tutania, melt together 4 oz. 
 of antimony, 1 oz. of arsenic, and 2 lbs. of 
 tin. 
 
 Tutenag. a name given in India to me- 
 tallic zinc. The Chinese copper is also called 
 by this name, which is allovedwith ■»'-- — -* 
 
TY 
 
 TV 
 
 forms a very hard white metal, but little dis- 
 posed to tarnish. 
 
 TuTTY. An old name for impure protoxyde 
 of zinc. 
 
 Tuyere, Tue-Iron, or Tew-Iron. An 
 orifice through which a blast or strong cur- 
 rent of air is passed into forges. 
 
 Twilight, is that faint light which is 
 perceived before the rising of the sun, and 
 after his setting, or when he is in either in- 
 stance less than 18° below the horizon. The 
 twilight is occasioned by the earth's at- 
 mosphere refracting the rays of the sun, and 
 reflecting them among its particles. 
 
 Tw^iNKLiNG OF THE Stars, deuotes that 
 tremulous motion which is observed in the 
 light proceeding from the fixed stars ; a phe- 
 nomenon which is said to arise from the un- 
 equal refraction of light, in consequence of in- 
 equalities and undulations in the atmosphere. 
 
 Tychoean System. A system of as- 
 tronomy, taught by Tycho Brahe, to account 
 for the motions of the bodies belonging to 
 the solar system. He imagined the earth to 
 be in the centre of all ; that the moon re- 
 volved around the earth nearest to her, next 
 the sun, at a still greater distance, the 
 planets Mars, Jupiter, and Saturn, but that 
 the inferior planets. Mercury and Venus, re- 
 volve not around the earth, but around the 
 sun, like satellites to him, and were conse- 
 quently carried round the sun's supposed 
 orbit with him. 
 
 Tympan. That part of the printing press 
 on which the paper is laid, when about to 
 receive the impression. It is a double frame, 
 one half of which folds upon the other. 
 
 Tympanum, is a hollow wheel, wherein 
 one or more persons or animals walk to turn 
 it, such as that of some cranes, treadmills, 
 &c. 
 
 Tympanum. The flat triangular part of a 
 pediment, corresponding to gable. It is often 
 richly sculptured. 
 
 Type. In general terms, is an emblem, or 
 example of any thing more valuable, or more 
 conspicuous ; thus we say that a medal is a 
 tjrpe of a certain victory ; a certain sentiment 
 is the type of a man's mind, &c. In the 
 art of printing, types signify the different 
 pieces of metal which represent the various 
 letters, stops, figures, &c. These types are 
 of various sizes, each known by a particular 
 name. Those used chiefly for book-work 
 are as follows : — The numbers attached to 
 each show the number of lines in a page of 
 6 inches long, and also the number of ens 
 which would fill a measure of 3-^ inches 
 wide. 
 
 English 32 47 
 
 Pica 35f 49 
 
 Small Pica 4H 55 
 
 Long Primer . . 45^ 62 
 
 Bourgeois .... b\^ 68 
 
 Brevier 56^ 72 
 
 Minion 64 75 
 
 Nonpareil .... 7H 87 
 
 Pearl 89 103 
 
 Diamond 102^ 128 
 
 The above is not always exactly correct, 
 because founders differ in a slight degree in 
 the size of their letters, though called by the 
 same name. Types larger than the above sizes 
 are used for posting bills, and are called 
 by the names of 2-line pica, 3, 4, 6, 8-/me 
 pica, and so on, and are often of wood. 
 Types are also distinguished by their shape 
 and the character of their ornament ; hence 
 arise the terms Roman, italic, script, black 
 letter, ronde or engrossing , flowered, Tuscan^ 
 phantom, Egyptian, and sans serif; besides 
 types that are cast for different foreign 
 languages, symbolical characters. Sec. A 
 fount of type is a collection of all letters and 
 characters necessary in printing a work of a 
 particular sized letter ; these letters being in 
 the average proportion in which they are 
 likely to be required. Types of a particular 
 fount are variously called, as capitals, small 
 capitals, lower case or small letters, stops 
 and accents, figures, quadrats, and spaces ; 
 both which last signify the blank squares 
 placed between the words to divide them 
 from each other; the larger blanks being 
 called en, em, 2, 3, or 4-em quadrats, and 
 the others thick, middle, thin, and hair 
 spaces, according to the size of each re- 
 spectively. 
 
 Type Founding. The art of easting 
 printers' type. The process may be briefly 
 described as follows : — A well tempered steel 
 punch is first prepared. The founder stamps 
 this upon a piece of brass or copper, to be 
 used as a matrix or mould. The sides of 
 the mould separate into two parts, and are 
 of steel, cased with wood. The type metal 
 is poured into a hopper-like top. The ma- 
 trix being placed in the bottom of the mould, 
 
UL 
 
 UN 
 
 the type metal is poured in by a small ladle. 
 The workman then jerks the mould upwards, 
 which at the same time drives out the air, 
 and cools the metal ; he then uncloses the 
 mould, takes out the cast letter, closes the 
 mould again, ready for another operation, all 
 in the space of ^ of a minute of time. From 
 the table of the caster, the types are taken 
 to another table by a boy, whose business is 
 to break off the superfluous metal. They are 
 then rubbed on their sides on a grit-stone, to 
 make them perfectly flat and square. They 
 are then arranged in a frame, and tied up in 
 packets ready for sale. The rubber will 
 
 The fifth vowel. It has 
 two sounds ; one clear, ex- 
 pressed at other times by 
 eu, as in obtuse; and the 
 other close and approaching 
 to the sound of double o, as 
 )in obtund. Its form is quite 
 of modem date, having been 
 originally identical with V. (See F.) It is, 
 therefore, not seen in inscriptions nor on an- 
 cient coins. We, however, at present use 
 the following contractions: — U, united as 
 U.S., United States ; urb., urbanus; ult., 
 ultimo ; ur., uranium, &c. 
 
 Ullage of a Cask. In guaging, is what 
 it wants of being full. 
 
 Ulmin. a vegetable principle, supposed 
 to be distinct and confined to the Ulmus 
 niger or Hack elm, from the trunk of which 
 it is said to have exuded. In appearance 
 and character it is something like a coarse 
 brown gum. 
 
 Ultimate Principles. Those simple 
 bodies into which a compound may be sepa- 
 rated. Thus to say, that the chloride of so- 
 da or common salt consists of hydrochloric 
 acid and soda is separating it only into its 
 proximate elements, and not its ultimate, 
 which are oxygen, hydrogen, and chlorine, in 
 the acid, and oxygen and sodium in the al- 
 kali. The principal ultimate elements of all 
 organic bodies are oxygen, hydrogen, and 
 carbon, to which animal substances add nir 
 trogen, together with other principles, pecu- 
 liar to certain of them. 
 
 Ultramarine. A beautiful blue color, 
 used by painters, and prepared by calcination 
 from Lapis lazuli. The genuineness of this 
 ailicle may be proved by putting a portion 
 into an iron ladle, and if when the ladle be- 
 comes red hot, the paint retains its color, it 
 is unexceptionable. This exquisite color has 
 the virtue of being extremely lasting, perhaps 
 more so than any other blue ever produced. 
 Ultramundane. Beyond the world, or 
 that part of the universe which is supposed 
 
 smooth 2000 types in an hour ; and breaUng 
 off" the superfluous metal is yet more e^e> 
 ditiously performed ; and yet so true that all 
 the types are exactly of the same height, 
 and their sides perfectly symmetrical and 
 uniform, otherwise they would be quite use- 
 less. 
 
 Type Metal. For the casting of ordi- 
 nary large type, the founders use an alloy of 
 3 parts lead and 1 of antimony. Though the 
 composition varies from ^ to ^ of antimony. 
 For smaller type may be used, 9 lbs. lead, 
 2 lbs. antimony, and 1 lb. bismuth. This 
 last alloy expands in cooling. 
 
 m 
 
 to be beyond the limits of our system, or 
 that planetary system of which the earth 
 forms a part. 
 
 Umber, or Umbre. A brown irony earth, 
 used both as an oil and water color; of a 
 fine and durable tint, the beauty of which 
 is much increased by calcining it ; then called 
 burnt umber. It came originally from Om- 
 bria, in Italy ; but is now chiefly brought from 
 Cypress. An inferior kind, called English 
 umber, is found in Derbyshire, Somersetshire, 
 and other parts of England ; also in Wales 
 and Ireland. 
 
 Umbra. A shadow, particularly the shadow 
 cast by one heavenly body upon another, as 
 during the time of an eclipse. 
 
 Uncial. A term applied to letters which 
 stand for words in inscriptions and epitaphs, 
 titles, &c. ; as A.M., Master of Arts ; D.D., 
 Doctor of Divinity. Our initial letters give 
 the chief of these abbreviations, used both 
 among the ancients and moderns. 
 
 Uniformity. Resemblance of shape, ot 
 aim, or of style, between the several parts 
 of a whole. 
 
 Undecagon. a figure of eleven sides. 
 
 Undercroft. A subterraneous apartment 
 or crypt. 
 
 Undersetting. The supporting a wall or 
 edifice, or an overhanging projection of rock, 
 &c., after the lower part has been removed, 
 or an excavation made beneath. Thus the 
 Custom House, London, was underset some 
 years ago, a new foimdation having been 
 
UN 
 
 UR 
 
 made to it without the superstructure being 
 disturbed. The following shows an under- 
 setting of a chalk cliff : — 
 
 Undershot Wheel, is one which is 
 turned by a stream of water flowing against 
 its lower side. 
 
 supposed to be at A, beneath which, and on 
 the face of the chuck is a hole ; in this is to 
 be inserted the substance to be turned. B B 
 is a screw placed transversely, which is pre- 
 vented moving endwise by a collar in the 
 middle of it. One end of the screw is cut 
 right-handed, and the other end left-handed, 
 so that by turning it one way the nuts 
 p and C recede from each other, or by turn- 
 ing it the contrary way they advance towards 
 each other. These two nuts pass through 
 grooved openings in the plate E, and project 
 beyond it, carrying jaws like those of a vice, 
 by means of which the substance to be turned 
 is held. 
 
 Undulatory Motion, is applied to de- 
 note a motion in any fluid, by which its parts 
 are agitated like the waves of the sea, and is 
 particularly applied to the motion of the air 
 in the propagation of sound. 
 
 Uneven Number. That which cannot 
 be divided into two equal parts, 
 
 Ungula. In geometry, is the bottom part 
 cut off by a plane passing obliquely through 
 the base of a cone or cylinder, being thus 
 called from its resemblance to the ungula or 
 hoof of a horse. 
 
 Uncia. The twelfth part of any thing. 
 
 Unici^e. The same as co-efficients. 
 
 Unit, or Unity. The representation of 
 any thing considered individually, without 
 regard to the parts of which it is composed.. 
 
 Universal Chuck. The name given to 
 the following chuck : — The screw which at- 
 taches it to Uie mandril is not shown. It is 
 
 Universal Discharger. (See Henley.) 
 
 Universal Joint. (See Hooke.) 
 
 Universe, The whole of created nature, 
 including our solar system, and all the starry 
 regions beyond. 
 
 Unlike Quantities. In algebra, are 
 such as are expressed by different letters, or 
 different roots or powers of the same letter. 
 
 Unlimited Problem. That which admits 
 of an indefinite number of solutions. 
 
 Uphers. Fir poles, fit for scaffolding, or 
 the making of ladders. 
 
 Uranic Acid. Peroxyde of uranium, or 
 the sesquioxyde of uranium. 
 
 Uranium. A rare metal, discovered first 
 by Kloproth, in the black mineral, called 
 pech-blende. 
 
 Uranus, Herschel, or Georgium Si- 
 Dus. The last or most distant planet of the 
 solar system, discovered by Dr. Herschel, in 
 1783. It is 1800 millions of miles from the 
 sun, and performs its revolution around him 
 in 83 years, 150 days, and 18 hours. Its 
 diameter is about four times larger than that 
 of the earth, being nearly 35,112 English 
 miles. Uranus is attended by six satellites. 
 
 Ure's Chlorometer. (See Chlorometer.) 
 
 Ure's Eudiometer. (See Eudiometer.) 
 
 Urn. a low wide vase, distinguished ac- 
 cording to its applied use, as a funeral urn, 
 a fountain urn, &c. 
 
 Urea. A substance which forms part of 
 urine. This and uric acid, which is urea 
 united with oxygen, contains proportionably 
 more nitrogen than any other animal sub- 
 stance. 
 
 f Urobenzoic Acid. An acid thrown down 
 »from the urine of horses and cows, by mixing 
 with it hydrochloric acid. 
 
 56 
 
VA 
 
 VA 
 
 This letter in ancient times 
 was synonymous with U, 
 and considered to express 
 that letter when used as a 
 consonant ; the same cha- 
 racter representing both. V 
 is now considered a distinct 
 
 7 . , iniiiiiiniMiP ^^^^''' and which has a sourul 
 
 ' ''' 'i ' ' ' ' ' i '| ''' ' i ' 1 1 ' 'intermediate between B and 
 F. In ancient insci-iptions it is very frequent, 
 and in Roman notation signifies the number 5. 
 V Tube. A glass tube, in the form of the 
 letter V (see the preceding cut,) to show the 
 decomposition of a neutral salt by galvanism. 
 It is a common glass tube, with a cork at each 
 end, and a platinum wire through each cork. 
 The solution of a neutral salt, colored by lit- 
 mus, is poured into the tube ; a galvanic 
 current being made to pass from v.'irc to wire, 
 through the hquid, decomposes it, drawing 
 the jilkali to one pole, and the acid to the 
 other, as is made visible by the changes of 
 color produced in the different ends of the 
 solution ; it being reddened on one side, and 
 rendered green at the other. 
 
 Vacuum, is literally an empty space; but 
 is generally used to denote the interior of a 
 close vessel, from which the atmospheric air 
 and every other gas has been extracted. (See 
 T'orricellian.) The vacuum produced by 
 means of the air pump is always imperfect ; 
 the vessel is nevertheless termed an exhausted 
 receiver. 
 
 Vauley. Any extended recess between 
 two prominences. In building it is the in- 
 ternal angle or gutter between two inclined 
 sides of a roof; the timbers used in such 
 places are called valley rafters, valley hoards, 
 valley pieces, &c. 
 
 Valonia. a kind of acorn, imported from 
 the Levant and the Morea, for the use of 
 tanners, as the husk or cup contains abun- 
 dance of tannin. 
 
 Valve. A moveable cover to an aperture, 
 occurring in various hydrostatic and pneu- 
 matic engines. Valves are sometimes moved 
 by a contrivance independent of the medium 
 in which they act \. at other times by the 
 power of the heavier medium, they bein:f 
 placed between two, as for example, water 
 and air. Valves are constructed of a variety 
 af forms, but they may be described gene- 
 rally as of four kinds. First, those of the 
 revolving description, comprising all cocks 
 from that in common use to the four-way 
 cock of the steam engine. Secondly, those 
 which are lifted by a power beneath, such as 
 the conical valve, the ball valve, cup valve, 
 and safety valve. Thirdly, those which are 
 hinged, such as the clack valve and the but- 
 terfly valve. Fourthly, such as slide back- 
 wards and forwards, as the air valve, the gas 
 regulating valve, the D valve, and the sliding 
 ▼alve of the steam engine ; all but the last 
 
 have been already described, and will be found 
 under their respective names. And, fifthly, 
 such valves as are kept to their places by a 
 spring, and are moved by human touch ; oi 
 this kind are the valves or keys of the flute 
 or organ, the valve of the water closet, &c. 
 
 Valved. Any thing that opens upon 
 hinges or to which a valve of any kind is 
 attached. 
 
 Vanadium. A rare metal, discovered in 
 Swedish iron in 1830. It is also found in a 
 lead ore from Mexico ; in both cases com- 
 bined with oxygen into the state of an acid, 
 called the vanadic acid. It also combines with 
 oxygen in two other proportions, forming 
 oxydes. The metal is white, like silver. The 
 vanadate of ammonia, mixed with a solution 
 of nut galls, is the best writing ink known. 
 
 Vancouver's Cejment. The white of egg, 
 dried, pounded, and mixed with a sixth part 
 of quicklime, in powder ; when afterwards 
 wetted, it becomes a very tenacious cement, 
 not injured by water or heat. 
 
 Vane. A flat surface, capable of being 
 moved by the current of a fluid ; as for in- 
 stance, the vanes of a windmill, the vane 
 which surmounts a weather cock, &c. Vane 
 is also synonymous with fly or fly wheel. 
 The sights which slide backwards and for- 
 wards upon levels, cross staffs, &c., are also 
 called vanes. 
 
 Vane, Electrical. Awheel, made of card 
 board, and balanced upon the point of a pin 
 or other wire. When a stream of the elec- 
 tricity from a common electrical machine is 
 allowed to issue from a blunt point, and the 
 vane is placed near to it, the strength of the 
 current will be sufficient to impel the vane 
 forward, so that it will rotate on its centre. 
 It may be made to turn either vertically or 
 horizontally, and of many forms. The fol- 
 lowing is one which will generally succeed, 
 as the friction upon a point is very little : — 
 
 Vanishing Fractions, are fractions in 
 which, by giving a certain value to the va- 
 riable quantity or quantities which enter into 
 them, both numerator and denominator be- 
 come zero, and the fraction itself %. For 
 
VA 
 
 VE 
 
 example, if a = 2, and x = 4, then the frac- 
 as 
 tion, — will be a vanishing: one, or of no value. 
 
 Vanishing Line. (See Perspective.) 
 
 Vapour. A watery emanation, uprising 
 either from the earth or from the surface of 
 aqueous bodies. If the latter, and assisted by 
 heat, it is commonly called steam ; if arising 
 from a gradual evaporation from the earth, 
 such are called terrestrial vapours, and fill 
 the atmosphere, descending afterwards as dew, 
 rain, or other falling liquid. These while 
 buoyant in the air produce various phenomena 
 of unequal refraction, reflection, clouds, &c. 
 
 Variable Quantities, are such as are 
 continually decreasing or increasing, in oppo- 
 sition to those which are constant. 
 
 Variation of Curvature. The change 
 made on a curve, so as to occasion it to be 
 flatter or sharper in each succeeding part. 
 For example, spirals are flatter as they pro- 
 ceed from a centre. 
 
 Variation of the Magnetic Needle. 
 (See Magnetic Declination.) 
 
 Variation of the Moon. (See Lihra- 
 iion.) 
 
 Varley's Graphic Microscope, &c. 
 (See Graphic.) 
 
 Varnish. A clear limpid fluid, capable of 
 hardening without losing its transparency ; 
 used by painters, gilders, cabinet makers, &c., 
 to give a lustre to their work, to preserve 
 them, and defend them from the air. The 
 properties of good varnish are that it shall 
 become quite hard, not crack, become dis- 
 colored, nor lose its lustre by time, lay upon 
 the work in an even coat, not be affected by 
 water or a damp atmosphere, and not alter 
 the colors over which it is applied. The base 
 of all varnishes are the various resins, which 
 are soluble in fixed oil ; volatile oil, of which 
 spirits of turpentine is the most used ; and 
 alcohol. The spirit of turpentine is mostly 
 added to the oil vai'nishes to produce sufficient 
 fluidity. The spirit or alcoholic varnishes 
 are the following: — White spirit varnish, 
 (see Sandarac /) cabinet -maker's varnish, 
 made of pale shell lac, 750 parts ; mastic, 
 64 parts; alcohol, 1000 parts by measure. 
 It is made cold, and is easily injured by heat 
 and spirituous liquors spilt on it. Golden 
 varnish : Gum lac in grains, 25 parts ; gam- 
 boge, 25 ; dragon's blood, 25 ; annatto, 25 ; 
 saffron, 6 parts. Strong alcohol to be added 
 till sufficiently thin. Mastic or picture var- 
 nish, (^Qe Mastic.) C?'2/*/a^ varnish is made 
 of. Canada balsam and spirits of turpentine 
 mixed together when both are warm. White 
 hard varnish : Agitate together in a large tin 
 bottle, 2^ lbs. of gum sandarac and 1 gallon 
 of spirits of wine, when dissolved it will be* 
 fit for use- Brown hard varnish : Agitate 
 together till dissolved 1^ lb. snndaiac, 1 lb. 
 shell lac- and 1 gallon alcohol. Oil var- 
 
 nishes : — Turpentine varniqih is made with 
 common rosin, boiled in linseed oil and di- 
 luted with spirits of turpentine. For copal 
 varnish, (see Copal.) For amher varnish : 
 Take 8 ozs. of amber, coarsely powdered, 
 1 oz. of Venice turpentine, 5 ozs. of linseed 
 oil, and 8 ounces of spirits of turpentine ; 
 boil the amber in the oil, and then add the 
 turps. For a black varnish, (see Brunswick 
 Mack.) For a varnish for iva. and brass ware, 
 (see Lacker.) For balloon varnish, (see 
 Caoutchouc.) 
 
 Varnish. Among medallists, is the term 
 used to signify those hues which antique 
 medals have acquired by laying in the earth. 
 
 Varnish Lenses. Small lenses made by 
 putting a drop of transparent copal varnish 
 on to a flat piece of oiled glass. It congeals 
 into a plano-convex lens, of considerable 
 magnifying power. 
 
 Vase. A large ornamental cup or pitcher ; 
 used either to contain liquids, flowers, or 
 other articles, for use or decoration, or as a 
 termination to columns, pedestals, and the 
 like, either in gardens, galleries of art, court 
 yards, on walls, &c. 
 
 Ya?,es, Magic. (See Magic.) 
 
 Vault. A subterraneous room, arched 
 over with masonry. Also a bricked grave. 
 Vaults have different names, according to 
 their shape and style of decoration, as plane, 
 ribbed, groined, cylindric, conic, spherical, 
 annular, and simple or compound. 
 
 Vault, Reins of. The sides or walls which 
 sustain the arch. 
 
 Vaulted. Any part of a building, covered 
 with arched stone or brick work ; as we say, 
 vaulted aisles, vaulted corridors, vaulted roof, 
 and so on. 
 
 Vegetation of Salts. A curious phe- 
 nomena, which takes place when strong 
 solutions of metallic salts 
 are left in glass, earthen- ,.^ „^ 
 ware, or other vessels, by ^%^^ 
 which they appear to grow 
 up the sides of the vessels, 
 and above the surface of 
 the solution, presenting a 
 beautiful cavdiflower-like 
 appearance. This may be 
 easily seen in a solution of 
 the sulphate of iron, cop- 
 per, or zinc, when left undisturbed for some 
 days in the light, for it is a remarkable fact. 
 that the eff'ect does not, according to M, 
 Chaptal, take place in the dark. The annexed 
 cut may convey a faint idea of the experi- 
 ment, observing that to produce so con- 
 spicuous an effect, a wine glass should be filled 
 to within half-an-inch of the top with the 
 solution. 
 
 Vegeto-Alkalis. Tlie alkalis potass and 
 soda, which are extracted from the ashes of 
 vegetables ; the terra being used to distinguish 
 
VE 
 
 them from ammonia, which is an animal 
 product ; and from the alkaline earths, which 
 are minerals. 
 
 VBGETO-ALKALOins, (See Alkaloids.) 
 
 Vehicle. A support or conveyance. Thus 
 we speak of a waggon, being a vehicle of 
 conveyance for goods ; and no less correctly 
 that an oil is a vehicle for color for the 
 painter ; a book a vehicle of information ; 
 or a particular menstruum a vehicle for the 
 solution of a salt or a gum ; though these 
 latter and other applications of the word 
 have evident reference to its first import. 
 
 Veins. Fissures or rents in rocks, which 
 are filled with peculiar mineral substances, 
 most commonly metallic ores. The earthy 
 parts found with such ores are called gangues 
 or vein stones 
 
 Valerianic Acid. An acid product, ex- 
 tracted from common valerian. 
 
 Vellum. Prepared calf's-skin or amb- 
 skin , which being finer in texture , and smoother 
 than parchment, is often used to write and 
 print upon, as well as in drawing and painting. 
 
 Velocity. The measure of swiftness with 
 which a body moves. 
 
 Velocipede. An instrument of loco- 
 motion, moved by the impulse given to it by 
 the rider's feet against the ground. The front 
 wheel is moveable horizontally, to enable the 
 rider to guide the machine. 
 
 Velocity, Principle of Virtual. An im- 
 portant principle in mechanical science, 
 indeed the foundation of all principle, as 
 it proves the power of every machine is 
 only an application of the force which is ap- 
 plied to it, and that no machine can multiply 
 power, for where it gains in impulse it loses 
 in time ; so on the contrary, if the velocity 
 of any thing is increased, it has received a 
 proportionately-increased impulse. In every 
 case, therefore, we may say that the power 
 multiplied by its velocity is the same as the 
 weight multiplied by its velocity ; thus if a 
 ball of 1 lb. weight, moving 3 feet per second, 
 strike a ball of 6 lb. weight, it would drive 
 it forward with a velocity equal to J, be- 
 cause 3 X 1 = 6 X |. So again, a power 
 multiplied by the distance it moves in, is 
 always equal to the weight multiplied by its 
 distance. If a pump throw up 30 gallons 
 
 VE 
 
 of water per minute, at a power equal to 
 40 lbs. , and it he made to throw up 90 gallons, 
 you must increase the power to 120, either 
 working three strokes in the time of one 
 before, by making those strokes three times 
 as long, or else increase the size of the pump 
 barrel, and apply three men instead of one. 
 Nothing is ever made, no power is ever 
 created by machinery. This is the principle 
 of virtual velocities, and is applicable to 
 thousands of applications, observing always 
 thdXfriction must be allowed for, as it much in- 
 fluences the practical result, thoughit does not 
 interfere with the grand theory or principle. 
 Velvet. A silken or cotton fabric, made 
 so as to have a short nap or pile similar to 
 that upon woollen cloths. 
 
 Veneer. A very thin leaf of wood of a 
 superior quality, for covering articles of fur- 
 niture or ornament which are made of an 
 inferior wood. 
 Venetian Chalk. Steatite or soap stone. 
 Venetian Door. A door lighted by 
 panes of glass on each side. 
 
 Venetian Window. A window in three 
 separate apertures, the two side ones being 
 narrow, and separated from the centre by 
 timber only. 
 
 Vent. The tube of a chimney for con- 
 veying the smoke from the fire. In London 
 it is called ^Me, and in some parts of England 
 funnel. 
 
 Ventilation. The renewal of fresh air 
 in places where without ventilation it would 
 be stagnant. 
 
 "\^entilator. a small machine made to 
 turn with the wind, and placed in a wall, 
 roof, or window, in order to let out heated 
 and impure air, and admit a supply of fresh. 
 Venus. The second planet of our system 
 in order from the sun, revolving between the 
 orbits of Mercury and the earth, at a mean 
 distance from the sun of 68 millions of miles. 
 She performs her siderial revolution in 224 d., 
 16 h., 49', 11". ; her rotation on the axis is 
 in 23 h., 21', 7", 2'"; and the diameter 
 7702 miles, or nearly that of the earth. 
 She is also surrounded by an atmosphere, 
 the refractive powers of which differ but little 
 from those of ours. As viewed from the 
 earth, Venus is the brightest and largest 
 planet, being often visible at noon-day, and 
 frequently noted as a brilliant morning or 
 evening star. Venus changes her phases like 
 those of the moon, according to her position, 
 relative to the earth and sun. 
 
 Vera's Rope Pump. (See Rope Pump.) 
 Veratrine. a poisonous, vegetable alka- 
 loid, extracted from the seeds of the veratrum 
 sabadilla ; the roots of veratrum album, or 
 white hellebore; and oicolchicum autumnale, 
 or meadow saffron ; in which plants it exists, 
 combined with gallic acid. It is obtained in 
 the state of a white powder. 
 
VE 
 
 VI 
 
 Verd ANTiauE. A beautiful green marble. 
 
 Verdigris. The acetate of copper. It 
 is a color much used in painting. Venetian 
 blinds are painted with common varnish 
 mixed with verdigris and white lead. It is 
 a favorite pigment with the artistical painter 
 for garden scenery. It serves also (mixed 
 with cream of tartar or vinegar) to make a 
 kind of water-green for coloring maps. 
 
 Verdigris, Distilled. A bin-acetate of 
 copper, made by dissolving in a copper 
 kettle, 1 part of verdigris in 2 of distilled 
 vinegar, aiding the solution by slight heat, 
 and occasional agitation with a wooden spa- 
 tula. 
 
 Verdic Acid and Verdous Acid. Two 
 acid principles extracted from various plants 
 of the umbellate kind, and from some of the 
 scabiosas. It is of no known use. 
 
 Verditer, or Blue Verditer. This is 
 a precipitate of oxyde of copper with Ume ; 
 made by adding that earth in its purest state 
 to a solution of nitrate of copper. The pre- 
 cipitate, when nearly dry, is triturated with 
 lime. 
 
 Verjuice. A harsh, austere vinegar, made 
 of the expressed juice of vine leaves, tendrils, 
 unripe grapes, crab apples, and other unripe 
 fruits. 
 
 Vermicelli. A paste of wheat-flour 
 drawn out and dried in slender cylinders, 
 more or less tortuous, like worms ; hence the 
 Italian name. 
 
 Vermillion. An extremely bright and 
 beautiful red color, composed of quicksilver 
 and sulphur, in great esteem as a body color, 
 and held equally in esteem by the ancients, 
 under the name of minium ; (the minium of 
 modem times is red lead.) There are two 
 kinds known in our market ; that prepared 
 in England, and called English vermiUion ; 
 and the Chinese vermiUion, which last is 
 more finely ground, and of a more brilliant 
 color. 
 
 Vernier. A contrivance connected with 
 a graduated scale, and employed for mea- 
 suring any portions of the space between its 
 most minute divisions. Verniers are applied 
 to astronomical and surveying instruments, 
 quadrants, &c. ; for example, let A G be any 
 portion of the limb or scale of a quadrant, 
 that is, half a degree divided into 6 parts, 
 AB, B C, &c., of 5 minutes each. 
 
 Let H I be another limb of equal extent 
 divided into 5 parts. In consequence of the 
 
 relation of these divisions, we see that the 
 line K L will be further advanced than N by 
 a fifth part. The next line M O, in the lower 
 scale, by % ; the next by f ; the one after- 
 wards by ^ ; and the last by f , or a whole di- 
 vision. By this means, each of the divisions, 
 A B, B C, &c. may be divided into 5 parts 
 or minutes, by shifting the moveable limb or 
 vernier H I to any part of the quadrant 
 where the sub-division is required. 
 
 Vernier, Chromatic. (See Chromatic.) 
 Versed Sine. (See Sine.) 
 Vertex. The top of any thing ending in 
 a point, as the vertex of a spire, pinnacle, &c. 
 Vertex of a Conic Section. The ex- 
 tremity of the abscissa. 
 
 Vertex, or Vertical Point. In astro- 
 nomy, the same as zenith. 
 
 Vertical. Erect ; that is, perpendicular 
 to the horizon, as a vertical plane. 
 Vertical Angles. (See Angle.) 
 Vertical Circle, is a great circle of the 
 sphere passing through the zenith and nadir 
 of a place : they are also called azimuth 
 circles. The meridian of a place is always 
 a vertical circle 
 
 Vertical, Prime. (See Prime.) 
 Vertical of the Sun, is that vertical 
 circle which passes through the centre of the 
 sun at any moment of time ; thus the shadow 
 thrown by the gnomon of a dial is always a 
 vertical of the sun at the time when the 
 shadow is observed. 
 
 Vertical Dial. One which is placed 
 vertically with the horizon, such as those 
 upon church walls, &c. 
 
 Vertical Windmill. (See Windmill.) 
 Vesper. One of the names formerly given 
 to the planet Venus. 
 
 Vesta. One of the four new planets 
 which revolve between the orbits of Mars 
 and Jupiter. It may be seen on a clear 
 evening by the naked eye, appearing like the 
 very smallest star. Its revolution around 
 the sun is in 3 years, 66 days, 4 hours. Its 
 size has not yet been determined, but it is 
 known to be very small, though its aspect 
 is extremely brilliant. 
 
 Vestibule. A porch ; also the hall of a 
 house, or an anti- chamber. 
 
 Viaduct. An elevated erection, usually 
 consisting of a series of arches, and similar 
 in construction and appearance to an aque- 
 duct, except that it is used for the con- 
 veyance of a road or railway, instead of a 
 canal or other body of water. 
 Via Lactea. (See Galaxy.) 
 Vibrating Electro-Magnet. (See 
 Bird's Contact Breaker.) 
 
 Vibrating Steam Engine. The great 
 loss of power and inconvenience of the work- 
 ing beam of a steam engine, suggested nume- 
 rous alterations in its structure to obviate 
 the necessity of this part ; hence arose the 
 
VI 
 
 VI 
 
 bell crank engine, the vibrating engine, &c. 
 In this last the piston rod is connected at once 
 with the crank of the fly wheel ; the steam 
 cylinder vibrates upon two hollow gudgeons 
 below ; to one gudgeon is attached the steam 
 pipe, and underneath the cylinder is the 
 four-way cock, so arranged that as the cylinder 
 vibrates, the cock is turned backwards and 
 forwards, admitting the steam alternately 
 above and below the piston ; the waste steam 
 being carried off by a second pipe fitting into 
 the other gudgeon, or otherwise, as most 
 convenient. The following cut shows the 
 general arrangement. It is to be observed 
 that vibrating engines are liable soon to get 
 out of order, in consequence of the constant 
 shock given to the working parts, whereby 
 the stuffing box and piston wear unequally. 
 
 Vignette Moulding. A moulding orna- 
 mented or enriched with vine leaves, grapes^ 
 or tendrils. 
 
 Vibration. A rapid alternating motion 
 like that of a pendulum. Vibration, in 
 electricity, is known as a quantity of the 
 fluid intermediate between a spark and a 
 shock. It occurs when using a very small 
 Leyden jar, such as that belonging to the 
 medical bottle. With a moderately sized 
 machine, vibrations may be given almost as 
 rapidly as sparks, and yet be felt like shocks, 
 which in fact they are. 
 
 ViKNNA Green. The same as Schweinford 
 green ; it is an arseniate of copper. 
 
 Vignette, An ornamental drawing with- 
 out any determined border or regular edge, 
 introduced into a page of a book, but not 
 occupying the whole of it. It was originally 
 a wreath of vine leaves, whence the name. 
 
 Vice. An instrument consisting chiefly^ 
 a pair of stout jaws or chaps, which are 
 brought together by the aid of a screw, to 
 compress or hold fast any substance placed 
 between them. 
 
 Villa. A country house or rural mansion , 
 mostly of an ornamental style of building. 
 
 Vinculum. In algebra, a mark or character, 
 either drawn over or including a quantity 
 when it is compounded of several letters or 
 terms to connect them together as one, and 
 show that they are to be multiplied or di- 
 vided, &c. Thus a + bx c, or (a + b)xc 
 denotes the product of c, and the sum a+b 
 considered as one quantity. 
 
 Vinegar. See Acetic Acid, with which 
 it is synonymous. 
 
 Vinegar, Aromatic. (See Aromatic.) 
 
 Vinegar, Radical. This differs from the 
 acetic acid, procured by the acetous fermen- 
 tation only, in being prepared by the de- 
 composition of an acetate, such as those of 
 lead or zinc. 
 
 Vinegar of Saturn. Solution of the 
 acetate or sugar of lead. 
 
 Vinegar of Wood. (See Pyroligneons 
 Acid.) 
 
 Vinous Fermentation. (See Fermeri' 
 tation.) 
 
 Virtual Velocity. (See Velocity.) 
 
 Vis. In writings on physical and mathe- 
 matical subjects, signifies force, as vis abso' 
 luta, absolute force ; vis motrix, moving 
 force. These Latin expressions are now 
 seldom used in English treatises. 
 
 Vis Inertia, or Power or Inactivity, 
 is defined by Sir J. Newton to be a power 
 implanted in all matter, by which it resists 
 
 1 
 
vo 
 
 vo 
 
 any change endeavoured to be made in its 
 state, whether of rest or of motion; for 
 example, a horse would be a long time in 
 putting in motion a large ship, or increasing 
 its speed, if before in motion, because of its 
 ■vis inertise, which must first be overcome. 
 
 Visible. Any thing that is an object of 
 vision or sight ; or, any thing whereby the 
 eye is affected so as to produce the sensation 
 of sight. 
 
 Visual. Relating to sight or seeing, as 
 visual angle, visual ray, &c. 
 
 Visual Point. The point of vision from 
 which an object is viewed, synonymous with 
 the point of sight ; (see Perspective.) So 
 the visual ray is the thread or beam of light 
 reflected to the eye from a certain point of 
 the object. 
 
 Vital Air. (See Oxygen.) 
 
 Vitreous Electricity. (See Du Fay.) 
 
 Vitrifiable Colors. Such pigments 
 and compositions as come to the state of 
 glass when submitted to the proper degree 
 of heat. (See Enamel and Glass Staining.) 
 
 Vitrification. The turning of any thing 
 into glass. 
 
 Vitriol. The old chemical, and still the 
 common appellation of sulphuric acid, and of 
 many of its compounds : thus vitriolic acid, 
 or oil of vitriol, is sulphuric acid ; blue 
 vitriol, or Roman vitriol, is the sulphate of 
 copper ; green vitriol is green sulphate of 
 iron ; vitriol of Mars is the red sulphate of 
 iron ; and white vitriol the sulphate of zinc. 
 
 Vitruvian Scroll. A particular orna- 
 ment used in classical architecture. 
 
 Vivian and Trkvethick. (See Treve- 
 thick.) 
 
 Void Space. (See Vacuum.) 
 
 Volatile Alkali. (See Ammonia.) 
 
 Volatile Oils. (See Oils.) 
 
 Volatility. That property of bodies by 
 which they are disposed to assume the va- 
 porous or elastic state, and quit the vessels 
 in which they are placed. 
 
 Volcano. A burning mountain, hollow 
 below, and communicating in all probability 
 with cavities still deeper than its own, from 
 which it is supplied with fire, and ignited 
 materials ; these it usually throws up at un- 
 certain intervals, in the state of ashes or of 
 liquid lava, through one or more external 
 apertures or craters. Some volcanoes throw 
 up torrents of water, others mud. There 
 are in the world, perhaps, 200 volcanoes. 
 Those, with the eflfects of which we are best 
 acquainted, are Hecla, in Iceland ; Etna, in 
 Sicily ; and Vesuvius, in Italy. Volcanoes 
 
 are also thought to exist in the moon, of far 
 greater power and magnitude than those of 
 the earth. 
 
 Volta's Air Lamp. A contrivance for 
 procuring a light instantaneously. One of 
 the illustrations shows the external appear- 
 ance of the lamp ; the other, the section of 
 it. In the latter, A represents a leaden bot- 
 tle, which has a pipe from the top of it, 
 through the bottom, and extending some dis- 
 tance below, as B. The case is divided into 
 two compartments ; the lower one, into which 
 B dips, is filled with water. The bottle A is 
 for the generation of hydrogen gas, by the 
 aid of iron, sulphuric acid, and water ; the 
 gas when made passes down the tube B, 
 through the water in the lower department, 
 and filling the tube D and cock E. The gas 
 having no outlet, occupies also the upper part 
 of O, driving the water up the pipe C into 
 the upper vessel. Whenever, therefore, the 
 cock E is turned, the gas rushes out of a 
 small orifice H, where there are two wires, 
 separated from each other by a small interval. 
 One of these wires is connected to the lower 
 plate of the electrophorus, seen at F, and is 
 a fixture. The other wire G is connected 
 with the cock E, and meets the former wu-e 
 near enough to give a spark, whenever the 
 cock E is turned ; and as this also lets on 
 the gas, this is inflamed by the spark, and in 
 its turn lights the candle in the front af the 
 instrument. 
 
 Volta's Condensing Plate. An elec- 
 trical doubler of the form shown in the cut. 
 The upper plate C is formed 
 of metal or wood, covered 
 with tin foil, and furnished 
 with a glass handle. B is 
 a non-conducting plate ; (a 
 piece of baked wood, mar- 
 ble, or pasteboard, does 
 very well.) A is a common 
 gold-leaf electrometer. To 
 use this apparatus : — Put 
 the plate B upon the elec- 
 trometer, and the plate C 
 upon B, connected, for 
 example, with a pointed 
 wire extending some dis- 
 tance into the atmosphere. 
 
vo 
 
 vo 
 
 Although the pointed wire may collect, if 
 attached to the electrometer, so little fluid as 
 to be vmappreciable, yet connected with this 
 upper plate C, this plate will concentrate the 
 quantity, until the plate B, by being let down 
 upon A, will by electrical induction affect the 
 fluid of the gold leaves, and render the 
 experiment successful. (See also Condensing 
 Plate, where another form of the instrument 
 is figured and explained.) 
 
 Volta's Electrqphquus. (See Elec- 
 tropJiorus.) 
 
 Volta's Eudiometer. {S,etEudiom,eter.) 
 
 Voltaic Apparatus. (See various ar- 
 ticles under Galvanic.) 
 
 Voltaic Battery. (See Galvanism.) 
 
 Voltaic Electricitv, or Voltaism. 
 The same as galvanism, it being to M. Volta 
 that we owe the first knowledge of the powers 
 of voltaic circuits, as shown by him in the 
 couronne de tasses and the galvanic pile. (See 
 Couronne and Pile.) 
 
 Voltaic Magnets. (See Electro -maff- 
 nets.) 
 
 Voltameter. An instrument for ascer- 
 taining the power of a galvanic battery, by 
 means of the quantity of 
 water it will decompose in 
 a given time ; and also of 
 showing the analysis of 
 water by galvanism. Two 
 such instruments are de- 
 scBSjed under the words 
 Bachhoffner and Faraday, 
 also two others under the 
 word Decomposing. The 
 principle of the following 
 simileur, but more simple 
 and superior instrument, "^^ 
 win be easily understood 
 by reference to the others. 
 It is the invention of Mr. ^ 
 De Moleyns. A A are two ' 
 graduated tubes of glass, for receiving the two 
 gases. B B are two binding screws, con- 
 nected with the poles of the battery. C C 
 are platina wires, united to the binding screws, 
 and to which the platina electrodes are joined. 
 D D is a brass bar, through which the tubes 
 pass, and also the wires are insulated. By 
 these arrangements all leakage is prevented, 
 and the parts are easily cleaned. 
 
 VoLTAPLAST. Such is the name given to 
 that form of galvanic battery which is adapted 
 to the electrotype, and of which several 
 kinds are already described, (see Electrotype.) 
 The following account of another kind has been 
 sent us by the inventor, Mr. De Moleyns : — 
 •*AAis a square mahogany trough, ce- 
 mented inside, to make it water-tight. On the 
 right hand is a plate of zinc B, not amalga- 
 mated. Connected with the longer wire is a 
 plate of copper C, doubled backwards on itself 
 iato the form D represented in the figure, 
 
 forming thus a shelf, intended to hold crystals 
 of sulphate of copper, which keep the solution 
 saturated, through small holes in the front of 
 the plate. When the battery is used for pre- 
 cipitations, this plate is removed, and the wax 
 or other impression substituted ; in this case 
 the crystals of sulphate are placed in the other 
 cell E. The metals and casts are suspended 
 from brass bars which extend across and rest 
 on the sides of the trough ; and there is an 
 arrangement by which the metals may be 
 approached nearer the diaphragm or drawn 
 back, as occasion may require, so that the 
 force of the current may be regulated to a 
 nicety. A saturated solution of muriate of 
 ammonia, diluted with soft water, is used in 
 connection with the zinc ; thus dispensing 
 with acids and their accompanying annoy- 
 ances. The diaphragms in these batteries 
 are prepared by a peculiar process, not yet 
 made public, which greatly increases their 
 Gonductibility." As the diaphragms are not 
 described, it may be stated that a division of 
 plaster of Paris, brown paper, wash-leather, 
 or parchment, will do equally well. 
 
 VoLUMN. The apparent space which a 
 body occupies is termed its volumn ; the real 
 space which such a body occupies, or its 
 real bulk of matter, is called its mass. The 
 relation of the mass to the volumn, or the 
 quotient obtained by dividing one by the 
 other, is its density ; and the empty spaces 
 or voids which render the volumn larger than 
 the mass, are its pores ; or in the case of 
 fluids, the interstices between its particles. 
 
 Volute. A principal ornament in the 
 Ionic, Corinthian, and Composite capitals. 
 There are eight angular volutes in the Co- 
 rinthian and Composite capitals, and eight 
 
WA 
 
 WA 
 
 smaller ones between them. In the Ionic 
 three are but four. The cut on the preceding 
 
 page shows the Ionic volute ; the annexed is 
 that of the Corinthian, taken from an elegant 
 
 Greek example. The volutes of the Corin- 
 thian are much more varied. The inner 
 volutes are generally called caulicoles. There 
 are, in every Corinthian capital, eight of the 
 larger, and as many of the smaller. The 
 volutes of the Composite order partake of a 
 mixed character, being intermediate between 
 the Ionic and the Corinthian; the scroll 
 portion or head being sometimes plain; and 
 at others ornamented with leaves, running 
 in between the channels. The most cele- 
 brated example is the Arch of Titus at Rome. 
 
 Vortex. (See Whirlwind and Whirlpool.) 
 
 Vortices of Descartes. (See Car- 
 tesian.) 
 
 VoussoiR. The stones which form an 
 arch. 
 
 Vulgar Fraction. (See Fraction.) 
 
 A letter which equally 
 partakes of the nature 
 of a vowel and a conso- 
 nant, being the latter 
 when at the beginning 
 of words and syllables, 
 but a vowel in every 
 other situation. In En- 
 glish, to is scarcely used as a vowel, except 
 when united to another vowel, as in strew, 
 show, Sfc. : though in Welsh the w is used 
 alone, as in cwm. The soxmd of u> as a con- 
 sonant is nearly uniform ; as a vowel it is 
 quite arbitrary, and seems to depend upon 
 custom alone, as is seen in the following ex- 
 amples : — sew, low, saw, brew, cow, bow,snA 
 sow, which two last, with some other words, 
 have each two sounds. W not being known 
 in the ancient languages, is, of course, not 
 found in the remains of antiquity, nor do we 
 use it as an abbreviation, except W., as west, 
 and wk., as week. 
 
 Wabble. A hobbluig unequal motion. 
 Wadd, is a provincial name of plumbago 
 in Cumberland, and also of an ore of man- 
 ganese in Derbyshire. 
 
 Wafer. A thin pasty material ; used to 
 close letters, and stick other smaller articles 
 together. Wafers are of four kinds. Paste 
 or common wafers, which are made of wheat 
 flour and water, with some coloring matter. 
 The thin fluid paste is poured on to a square 
 iron frame, made of a very little depth ; a 
 second frame or rather cover is put over it, 
 which squeezes out the superfluous paste, 
 and being warm, the iron at the top and 
 bottom bakes the paste into a thin cake, 
 which is afterwards punched out into form. 
 Second, transparent wafers, which are made 
 of fine glue, poured out on to a marble slab; 
 when cold and dry, it is punched out with 
 
 proper shapes. Third, ffum wafers, lately 
 much used, are merely colored paper, gummed 
 on the blank side, and cut out with a stamp 
 that at the same time impresses them with a 
 device or letter. Fourth, medallion wafers, 
 for these, dies with various devices are 
 taken ; a mixture of flake white or ceruse 
 is painted over the depressed portions of the 
 die ; the superfluity of this is wiped off with 
 the hand, and dissolved isinglass afterwards 
 poured over the whole. When dry, and 
 taken off, the wafers present the appearance 
 of a white figure upon a different colorea 
 ground. 
 
 Waggon. A four-wheeled carriage for 
 the conveyance of heavy goods and ma- 
 terials. 
 
 Wagstaff's Electro -Magnetic Ma- 
 chine. This is a coil machine, which varies 
 in its form and method of breaking contact, 
 (see Bachhoffner, Bird, Sturgeon, 8fc.) Its 
 principle however is the same. A is the 
 double coil of insulated wire. B a bundle of 
 straight iron wire. C a break-wheel, better 
 seen in the side-cut K. It is of brass, with 
 a brass axis, and several cavities cut in the 
 circumference, which are filled with pieces of 
 ivory, so that upon turning the wheel the 
 wire at the top of it is in contact vdth the 
 brass, or not, according to whether it touches 
 the metal or ivory, and contact is rapidly re- 
 newed and broken. The two ends of the 
 primary coil are connected with B and D, and 
 with the centre of the break- wheel, upon the 
 circumference of which rests another wire 
 that goes under, and is secured by I. It 
 passes on the under side from I to H, and is 
 then secured by H. The ends of the secondary 
 wire are secured by the balls E and F, The 
 ends of the battery are connected with G and 
 H. L shows the wires beneath the stand ; 
 
 LX. L 
 
 57 
 
WA 
 
 WA 
 
 the points near the centre is where they issue 
 from the coils, thence ji&ssing to the balls. 
 
 Wagstaff's Wire Covering Ma- 
 chine. This simple and effective machine 
 was invented to cover with silk or cotton 
 the wire used for electro -magnetic purposes ; 
 but it is equally applicable to cover violin 
 strings, or wire for bonnets. The frame- 
 work is of wood. A B the foundation of it. 
 C is a drum, upon which the wire which is 
 to be covered is first wound. This wire 
 passes round the pulley L, through the tube 
 T>, round the pulley E, and on to the wheel 
 F, upon the back of which is a groove to re- 
 ceive it, of a diameter exactly equal to the 
 drum C. When the handle G is turned round 
 it moves the pulley J ; this by a cord turns 
 the smaller pulley I ; and I is connected by 
 a bent wire with the bobbin of cotton K ; so 
 that as I is turned, the bobbin rotates about 
 the wire to be covered, and in fact covers it ; 
 at the same time it is drawn forward very 
 slowly, in consequence of the handle G turn- 
 ing at tlie same time the toothed-wheel F, 
 so that the wire is unwound at one end, well 
 and rapidly covered by cotton, and wound up 
 on a reel, all by turning a handle. 
 
 Wainscot. Thelining of walls, constructed 
 of wood, and most generally panelled ; when 
 it does not reach the top of the walls it is 
 called dwarf wainscotting ; also from the 
 circumstance of a soft and straight-grained 
 species of oak being used originally for this 
 purpose ; such timber is still, although 
 mostly superseded by fir, called wainscot. 
 This timber, and by the same name, is now 
 chiefly used for the inner part of drawers 
 wid other fiirniture. 
 
 Wall. A fabric of stone, brick, chalky 
 or clay, erected around gardens, to. incloso 
 or form a part of houses, &c., either as de- 
 fence, inclosure, or support for other parts. 
 Walls are, in ordinary circumstances, built 
 erect or vertical on both sides : in embank- 
 ments they may be battered, that is, be made 
 wider at the bottom ; and in both cases, if of 
 great height, and not tied by cross walls, 
 they should be strengthened by piers of 
 stronger work ei-ected at mtervals. In the 
 walls of houses, as they are liable to be 
 broken through by apertures for doors and 
 windows, they are strengthened by bond 
 timbers placed even with the inner surface, 
 and running horizontally through the wall. 
 Brick walls are known by their thickness, as 
 4 -inch work, that is the thickness of a brick 
 laid flatways: 9-inch work, or the thickness 
 of a brick lengthways ; brick and a half; 
 2 bricks ; 2\ bricks, &c. Stone walls are 
 distinguished not only by their thickness, but 
 also by the character of surface given to the 
 stones. (See Masonry.) 
 
 Walls, Cased, those that are faced up 
 anew, in order to cover an inferior, material, 
 or old work gone to decay. 
 
 Walls, Abutments in. The beds that are 
 prepared for the springing of an arch. 
 
 Wall Plate. A beam of timber lying 
 upon a wall to rest the timbers of the root 
 upon, or the joists of a flooring. 
 
 Wallace's Eidograph. This instrument 
 is for copying drawings accurately at an equal, 
 reduced, or enlarged size from the original. 
 A B is a bar of wood sliding along the 
 centre pulley C, which is fixed to a table. 
 This bar is graduated, and, according to the 
 lengths from the two ends, so wiU the size ol 
 the drawing be regulated. E E are two pul- 
 leys turning on their centres, and having the 
 graduated sliding bars F F passing through 
 or under them ; a cord connects the pulleys 
 E E, which are furnished with guards at K K, 
 to keep the cord from slipping. One of the 
 points G, carries a tracing point, the other G 
 a pencil, from which proceeds a string to lift 
 it from the paper when no mark is to be made, 
 E and F being set at such lengths as corres- 
 pond with the two ends of the centre bars, the 
 pencil will mark upon a piece of paper placed 
 beneath whatever the tracer passes over. 
 
WA 
 
 WA 
 
 Wallowbr. (See Trundle.) 
 
 Warehouse. An erection for the pre- 
 lervation of goods and materials. 
 
 Warp. The layer of threads, which ex- 
 tends the length of the piece of cloth, calico, 
 &c. which is to be woven. 
 
 Wash. The fermented wort of the distiller. 
 
 Washers. Small pieces of metal, placed 
 under a nut to reduce friction. 
 
 Washing of Ores. The purifying of any 
 ore of a metal, by means of water, from 
 earths and stones, which would otherwise 
 render it difficult of fusion. Washing of a 
 picture, is the slightly coloring of it with a 
 very light and thin tint, to indicate various 
 colors, which the mere drawing will not give, 
 for the colors of different marbles, flowers, 
 &c., cannot always be indicated by words or 
 drawing, though a very slight wash will give 
 them accurately. The coloring of maps is 
 a kind of washing. 
 
 Wash Leather. (See Shammey.) 
 
 Waste Weir. A channel constructed to 
 carry off surplus water from a mill, canal, 
 &c., when in too great abundance for its in- 
 tended purpose. 
 
 Watch. A small time-keeper, to be 
 carried on the person. 
 
 Water. A well known fluid, which, when 
 pure, has neither color, taste, nor smell. 
 When existing naturally, it is however never 
 pure, the nearest approach to purity being 
 in snow or rain water. It is the material 
 from which the specific gravity of all liquid 
 and solid bodies is determined, itself being 
 reckoned as one. We give to water various 
 appellations, according to its contained in- 
 gredients or its source ; thus, soft water is 
 known as such ais is nearly pure, and which 
 combines well with soap. Hard water is 
 contaminated with various earths and min- 
 erals, particularly lime in different states. 
 If it contain such substances as are benefi- 
 cial to the human constitution, we call it 
 mineral or medicinal water. The water of 
 the sea contains the muriate of soda. Water 
 was supposed by the ancient chemists, indeed, 
 till within a little more than half a century, 
 to be a simple substance ; it is now known to 
 consist of oxygen and hydrogen. Water may 
 be formed artificially by exploding these 
 gases in the eudiometer, (see Cavendish,) 
 by the air-pistol, the electrical spark ; or the 
 fact of its composition may be proved by 
 analysis with the galvanic decomposing ap- 
 paratus. (See Decomposing,) 
 
 Water of Crystallization. Many 
 salts require a certain proportion of water to 
 enable them to retain the crystalline form, 
 and this is called their water of crystalliza- 
 tion. Some retain this so feebly, that it flies 
 off on exposure to the air, and they fall to 
 powder. These are the efflorescent salts. 
 Others have so great an affinity for water, that 
 
 their crystals attract more from the air ia 
 which they dissolve. These are the deliques- 
 cent. 
 
 Water Cement. (See Puzzolana.) 
 Water Colors. Such pigments as are 
 miscible with water ; these are usually sold 
 in small rectangular cakes, made by grinding 
 the proper pigment along with water until it 
 makes a uniform paste ; to this a little size 
 is added, and then a portion of it, sufficient 
 for a cake, is pressed into a mould, which has 
 been slightly oiled ready to receive it. 
 
 Water Color Painting. A painting 
 colored with such pigments as are miscible 
 with water. There is not in water color 
 painting so much breadth, brilliancy, and 
 force as in oil, but in general more light, 
 airiness, and transparency. 
 
 Water Gilding. (See Gilding.) 
 Water Hammer. A tube of glass, about 
 a foot long and half an inch internal diameter, 
 with a bulb at one end. This is exhausted 
 of air, partly filled with distilled water, and 
 hermetically sealed. If it be now turned up- 
 side down suddenly, the water having no air 
 to intercept its motion, will fall to the lower 
 end of the tube, and at the same time pro- 
 duce a loud report, like the blow of a ham- 
 mer. It is made by pouring water into a 
 tube of glass of proper size, and sufficiently 
 strong to bear the pressure, then boiling the 
 water, and when steam only occupies the tube, 
 hermetically sealing it. 
 
 Watering of Stuffs. (See Tabby.) 
 
 Water Level. (See Level.) 
 
 Water-Mill, or Water-Wheel. Any 
 wheel turned by running water. According as 
 the water is applied, they are called Under- 
 shot, Overshot, and Breast -Wheels, (which 
 see.) The first is used only in streams, the 
 water striking against the lower part. In 
 the overshot wheel, the water passes over the 
 top ; and in the breast-wheel, the water falls 
 perpendicular to the buckets or float-boards. 
 
 Waterpoise. (See Hydrometer.) 
 
 Water-Proof. Any thing which resists 
 the passage and action of water. 
 
 Water Ram. An ingenious machine 
 whereby water is raised much above its level, 
 by the momentum of a larger stream than 
 that raised. Suppose that the water from 
 a butt be required to be carried to a 
 cistern at the top of a house, it may be 
 done by this means. A pipe is led from 
 the butt to the ram, and to a valve beyond 
 it, which is forced down and kept opeo 
 by the weight T. The water rushing down 
 the pipe Q, acquires momentum, and strikinf 
 
WA 
 
 WA 
 
 against the underside of the valve S, closes 
 it. The course of water is stopped, but the 
 inomentum cannot be so easily overcome, 
 therefore that part of the column nearest to 
 the butt still endeavours to escape, and as it 
 cannot do so through R it opens the valve 
 in the ram, and rushes up the pipe X. The 
 momentum ceases, and S again opens, and 
 allowing a fresh flow of water, occasions the 
 former impulse to be renewed, and more 
 water to pass into X. So rapid is the action 
 of this machine that the vedve S is in cou- 
 tinual and incessant vibration. 
 
 Water-Shoot. A wooden trough for the 
 discharge of water. 
 
 Water-Spout. A remarkable kind of 
 raeteor, consisting of a moving column or 
 pillar of water. Its first appearance is in 
 tile form of a deep cloud ; the upper part of 
 wnich is white, the lower black. Soon after- 
 wards there hangs, or rather falls down, what 
 IS properly called the spout, resembling a 
 conical tube, largest at the top. This varies 
 in length, and generally assumes a waving or 
 rotatory motion. The sea beneath is always 
 more or less agitated, drawn up and scattered 
 in spray : after a time the spout recedes into 
 the clouds, and the whole passes away. This 
 phenomenon is accounted for by electrical 
 attraction. Waterspouts occasionally pass 
 over the land, and when they meet with any 
 thing to draw off their electricity, they break 
 and deluge the ground beneath. 
 
 Water-tight. That degree of tightness 
 in a vessel which prevents the passage of 
 
 water through it. Thus a cask must be 
 water-tight, or its contents will leak out ; a 
 buoy must also be water-tight, that the 
 water may not get in, and thereby sink it. 
 
 Water- Wheel. (See Water-MiU.) 
 
 Water Wings. The walls erected on the 
 banks of a river next bridges, to secure the 
 foundations from the action of the current. 
 
 Water-Works. The name applied to every 
 description of works, for raising and sus- 
 taining water-wheels, sluices, and other hy- 
 draulic structures ; and particularly to works 
 erected to supply towns and cities with water 
 for the use of the inhabitants. 
 
 Watkins's Heliacal Rotative Wire. 
 This instrument shows the effect of an elec- 
 trical current, passing along a wire, twisted 
 heliacally around the pole of a magnet. Let 
 A B be a horse-shoe magnet, fastened verti- 
 cally to the stand by a screw C. Upon each 
 arm of the magnet is a circular mercury chan- 
 nel E E, furnished with mercury cups, and i 
 fastened to the magnet by side screws. F F 
 are the two heliacal wires ; they have mer- 
 cury cups at top, and are supported by points 
 on to the poles of the magnet. G is another 
 mercury cup. I a cross bar, appended to the 
 standard H. When a current is sent through 
 the coils of wire, in any direction, they will 
 rotate around the poles of the magnet within 
 them. 
 
 Watkins's Rotating Magnets. It will 
 be seen that this instrument is but a modi- 
 fication of another, described under the word 
 Sturgeon. It acts upon the same principle, 
 and like the other may be of varied form. 
 One of the neatest is as follows : — A B are 
 two bent magnets. C C are two wires to 
 support them. D D and E E are mercury 
 cups, the wires of E E dipping into D D. 
 From the lower ends of the naagnets proceed 
 two wires H and I, that are long enough to 
 dip into the troughs for mercury F G. When 
 the electrical current is passed cither down 
 or up both magnets, they will rotate in the 
 
WA 
 
 same direction with each other ; but if the 
 current be passed down one and up the other, 
 they will rotate both the same way. 
 
 Watt's and Boultgn's Steam En- 
 GINE. One of these engines, for there are two 
 is akeady described under the word Steam 
 The other, called usually Watt's single en- 
 gine, is as follows : — This was invented be- 
 fore his admirable contrivances of the gover- 
 nor and parallel motion. It might be thought 
 unnecessary to show more than the repre- 
 sentation of it, yet it differs so very materially 
 from former engines in its condensing appa- 
 ratus, its valves, and trussed working beam, 
 as to claim attention to these particulars. 
 A is the cylinder. B the piston. C the 
 steam pipe. D the throttle valve. E the 
 
 WE 
 
 lower steam valve. F the passage to Ine ey- 
 linder. G the pipe leading to the coadeiksei la/ 
 I is the air pump, opening into the hot water 
 cistern by the valve. L the hot water pump. 
 M and N the tappets, which work the valves. 
 O the cold water pump, which supplies the 
 cistern R. 
 
 WaVe. a volumn of water, elevated by 
 the action of the wind, &c. upon its surface, 
 into a state of fluctuation, and accompanied 
 by a corresponding cavity between each two 
 waves. Natural waves are such as arise from 
 this cause, and are found only in open seas. 
 Artificial waves, or breakers, are those 
 motions of the water, occasioned by objects 
 passing through it, by its beating on the 
 beach, or against rocks, or other obstacles. 
 
 Wax. The substance which forms the cells 
 of bees, and also a vegetable product. Bees* 
 wax is yellow, has a peculiar smell, derived 
 from the honey lodged in the cells. Those 
 cells in which no honey has been deposited 
 are scentless and white, called virgin wax ; 
 a name also given to common wax when 
 purified and bleached, by exposure to air, 
 light, and moisture. Wax is often adulterated 
 with starch and with mutton suet. 
 
 Wax, Mineral. A bituminous substance, 
 found at the foot of the Carpathian moon- 
 tains, near Slarick. 
 
 Way-Wiser. (See Perambulator.) 
 Weather. Denotes the state of the at- 
 mosphere, with regard to heat and cold, 
 dryness and moisture, wind, rain, hail, &c. 
 
 Weather-Boarding. The nailing of 
 boards upon each other, so that the upper 
 laps over the under board, and thereby throws 
 off the wet ; the boards used for this purpose 
 are cut thicker at one edge than the other, 
 and are called feather-edged boards, or more 
 properly, but less frequently, weather-edged 
 boards. 
 
 Weathered. When horizontal stonework, 
 such as window sills, cornices, coping stones, 
 battlements, &c., are sloped oflF to throw off 
 the wet, they are then called weathered. 
 Weather-Glass. (See Barometer.) 
 Weathering. Among millwrights, is the 
 angle at which the sails of a windmill are set 
 to receive the impulse of the wind. 
 
 Weather, or Water Mouldings. (See 
 Dripstones.) 
 
 Weather Tiled. The covering of' an 
 upright or wall with tiles. 
 
 Weaving. The art of manufacture of 
 textile fabrics in a loom. 
 
 Wedge. One of the five mechanical powers 
 or simple engines, being a geometrical wedge 
 or very acute triangular prism, applied to the 
 splitting of wood, rocks, or raising heavy 
 weights. The wedge is the most powerful 
 of all the simple machines, having an almost 
 unlimited advantage over all the other simple 
 mechanical powers, both as it may be 
 
WE 
 
 WE 
 
 very thin in proportion to its height, in which 
 consists its own natural power ; and as it is 
 urged by the force of percussion, the greatest 
 of all forces. To the wedge may be referred 
 all edge-tools, and tools that have a sharp 
 point, in order to cut, cleave, slit, split, 
 chop, pierce, bore, or the like, as knives, 
 hatchets, &c. 
 
 Wedgewood's PiROMETER. An instru- 
 ment for ascertaining very great degrees of 
 heat. Its indications depend upon 
 the contraction of pure clay when 
 much heated. This reduction of 
 heat is first observed when the 
 clay acquires a red heat, and 
 continues to increase until vitrifi- 
 cation ensues ; the contraction of 
 volumn being permanent, and 
 amounting in the whole to about 
 one-fourth. The pyrometer con- 
 sists of a guage of brass of two 
 straight pieces, 2 feet long, fixed 
 upon a plate, a little nearer to 
 each other at one end than at the 
 other, the space between them at 
 the widest end being -^ of an 
 inch, and at the narrowest ^. 
 The converging pieces are divided 
 into inches and tenths. The piece of clay, 
 the contraction of which is to be measured, is 
 made of a cylindrical form, but flattened on 
 one side, and of such a size as to be exactly 
 adapted to the wider end of the guage, so 
 that it may slide farther in, in proportion to 
 the degree of heat applied to it. The scale 
 of this pyrometer proceeds from 1 to 240 ; 
 1 is the heat at which zinc melts, equal to 
 700° Fah. ; 240° of Wedgewood is equal to 
 32277° of Fah., a greater heat than that of 
 the hottest furnace, this latter being about 
 160° of Wedgewood, or 21877° of Fah. The 
 heat at which enamel colors are burnt on is 
 6° W. (Wedgewood) ; flint glass is poured 
 at 29° ; plate glass at 57° ; Delft- ware baked 
 at 41°; least welding heat of iron 90°; 
 greatest 95° ; stone- ware baked in at 102° ; 
 greatest heat of a smith's forge 125°; cast 
 iron melts at 130°. 
 
 Weighing Beam. (See Balance.) 
 Weighing Machines, (See Balance, 
 Counter-weighing MacJdne, Danish Balance, 
 Steelyards, Sfc.) 
 
 Weight. In mechanics, denotes anything 
 to be raised, sustained, or moved by a ma- 
 chine, as distinguished from the power, or 
 
 that force by which the machine is put in 
 motion. Weight, in commerce, is a ceitaii* 
 known and standard quantity of a heavy ma- 
 terial, used together with a balance, steel- 
 yard, &c., to ascertain particular quantities 
 of goods, suspended so as to counterpoise the 
 weight. In natural philosophy, the weight 
 of an object is synonymous with its specific 
 gravity, multiplied by its bulk ; or in other 
 words, it is the measure of the amount of 
 gravitation in any body, compared with that 
 of other bodies. 
 
 Weight of the Atmosphbre. (See 
 Atmosphere.) 
 
 Weir. (See Dam.) 
 
 Weld. The dried stalks, leaves, and flowers 
 of an annual herbaceous plant, called Reseda 
 luteola. They are used by the dyers as 
 affording a brilliant and durable yellow color. 
 Welding. The property of uniting to- 
 gether and incorporating with each other 
 two or more pieces of metal, by heating and 
 hammering. The property of welding or 
 becoming thus united is only possessed by 
 certain metals, particularly by iron and 
 platinum, 
 
 Welf. (See Woof.) 
 
 Well. A narrow and deep pit, dug in the 
 ground for the purpose of obtaining water ; 
 for burying valuable matters from the de- 
 vastation caused by fire ; or, in some cases, 
 for the conveyance of workmen and goods 
 up and down from a mine beneath : in this 
 latter sense it is mostly called a shaft. 
 Wells, Artesian. (See Artesian.) 
 Well-Hole. In building, the space in- 
 closed by the walls of a circular staircase. 
 Some builders confine the term to the void 
 space left in the middle of such a staircase, 
 and which opens a cavity from the top to 
 the bottom of the edifice. 
 
 Well Staircase. A winding staircase, 
 the walls of which are built round so as to 
 resemble a well. 
 
 Welter's Safety Tube. (See Tube.) 
 The following different form is often given to 
 the safety tube, for the 
 greater convenience of 
 performing certain ex- 
 periments ; its principle 
 is the same as that before 
 described. The two ends 
 dip into various of Woolf 's 
 bottles, while the tube 
 may be either left open 
 for particular gases to 
 escape, or it may be 
 loaded by quicksilver, oil, 
 or spirit being poured .J 
 into it. ^ 
 
 West. One of the four cardinal points. 
 being that opposite to the east, and that 
 nearest to which the sun sets. 
 WitT Dock. (See Dock.) 
 
 
 
 I? 
 
WH 
 
 WH 
 
 Whalebone. The name of the horny 
 laminae found in the mouth of the whale, 
 which by the fringes upon their edges, enable 
 the animal to allow the water to flow out 
 from between its jaws, but to catch and de- 
 tain the small fishes upon which it feeds. 
 There are about 300 blades of whalebone in 
 the mouth of each fish ; these are of various 
 lengths, from 12 or 14 feet to 3 or 4. 
 Whalebone is used for the ribs of umbrellas ; 
 to stiffen stays ; and for the frame-work of 
 some hats. Heated by steam it softens, and 
 may then be moulded to many forms like 
 horn ; in this way snuff-boxes and the knobs 
 of walking sticks are sometimes manufac- 
 tured. 
 
 Wheel. In mechanics, an engine con- 
 sisting of a circular body turning on an axis, 
 for enabling a given power to overcome or 
 move a given weight or resistance ; or in 
 many cases as a roller to diminish friction. 
 Wheels are extremely diversified in shape as 
 they are in application. (See the words 
 Bevelled, Break, Cam, Crown, Cogged, Tooth, 
 Trundle, Pinion, Ratchet, Spur, Water- 
 Wheel, Escapement, Fig, Friction, Heart, 
 Dished, Rag, 8fc.) 
 
 Wharf. A firm landing place, built be- 
 side the water, for the convenience of loading 
 or unloading ships, barges, or other vessels, 
 and therefore usually furnished with cranes 
 and various appendages, according to the 
 nature and extent of the business to be per- 
 formed. 
 
 Wheel, Persian. (See Noria.) 
 
 Wheel, Sun and Planet. (See Sun.) 
 
 Wheel and Axis. (See Aans in Peri- 
 irochio.) 
 
 Wheel Race. The place in which a water- 
 wheel is fixed. 
 
 Whetstone. A kind of slate, by which 
 various tools are whetted or sharpened, after 
 having been ground by a rougher stone to 
 the requisite shape and bevel. Whetstones 
 go by the names of Turkey stone, Charley 
 forest, hones, snake-stone, &c. 
 
 Whims. Large capstans connected with 
 the shafts of mines, and worked by horses. 
 
 Whip. To bind two rods or bars together 
 with twine or wire ; also the length of the 
 sail of a windmill measured from the axis. 
 
 Whirl, A rotatory motion given to any 
 thing. 
 
 Whirl, Electrical. (See Flyer.) 
 
 Whirling Table. A machine intended 
 to represent the several phenomena in philo- 
 sophy and nature, relative to the power of 
 the centrifugal force, particularly in its efiects 
 upon the shape of the earth and planets. The 
 whirling table consists of a steady foot-board 
 A, with a large wheel B, grooved around the 
 edge, turning upon it. A cord passing round 
 this wheel passes also over a pulley C ; to 
 this is attached an arm D, with two uprights 
 
 E and F. Upon the uprights, and also upon 
 the centre, rest two glass tubes, closed at both 
 ends, and holding air, water, and small shots. 
 While the machine is at rest, the shots, being 
 the heaviest, will occupy the lower part of 
 the tubes ; but when rapidly whirled round, 
 by turning the wheel B, centrifugal force will 
 so act upon the tubes as to drive the heaviest 
 matter most outward. The shots, theiefore, 
 will be found at the top of the tubes, the 
 water next, and the air at the bottom. 
 
 Whirlwind. A sudden, rapid, violent 
 motion of the air, in circular whirling direc- 
 tions. 
 
 Whirlpool. A body of water in certain 
 seas and rivers which runs rapidly round, 
 forming a sort of cavity in the middle ; the 
 same as is occasioned by water running down 
 a funnel. 
 
 White. A negative color ; the effect of 
 the admission of light upon any object whioh 
 reflects it directly. It is, therefore, the color 
 most significant of light, and more especially 
 is that which is produced by the naturai 
 combination of the rays of the solar spec- 
 trum. (See Prismatic Colors.) Numerous 
 bodies of this color are used as pigments by 
 the painter, as ceruse, flake wlute, constant 
 and permanent white, Krems white, &c. 
 
 White Copper. (See Tutenay.) 
 
 White Enamel. (See Enamel.) 
 
 White Flux. {SqqFIux.) 
 
 White Lead. The white oxide of lead, 
 used for numerous purposes of painting, and 
 also, instead of glue, for such joints of show 
 boards, rails, &c., as are exposed to the 
 weather, and for the uniting of water-pipes, 
 steam engine boiler joints, "and numerous 
 similar purposes. 
 
 White Metal. A kind of queen's metal, 
 made as follows : — Fuse together 10 ounces 
 of lead, 6 ounces of bismuth, and 4 drams 
 of regulus of antimony ; or else, 2 pounds 
 of regulus of antimony, 8 ounces of brass, 
 and 10 ounces of tin : a third receipt is, 1 
 pound of brass, 1| ounce of zinc, and J an 
 oimce of tin. 
 
 White, Permanent. Sulphates of barytes. 
 
 White Tombac. (See Tomhas.) 
 
 Whiting. Chalk cleared Oi Tts grjsser 
 impurities, then ground in a jaU, lu^ed 
 with water, made up into small luafes, and 
 dried. 
 
WI 
 
 wo 
 
 WirKKT. A small door made in a gate, or 
 by tJ\f. RJUe of a pate. 
 
 Winch. A handle acting in the nature of 
 a crank, for the moving of any description of 
 machine. 
 
 Wind. A sensible current m the atmo- 
 sphere, arising from the various conditions of 
 heat and cold that affect it, from the action 
 of the sun and other causes : for example, if 
 one portion of the atmosphere be heated by 
 a bright sun, the air will ascend, and its 
 place below be filled by air of a less tem- 
 perature, and thus a current be established ; 
 which, when of sufficient magnitude, will be 
 perceptible to our senses, and be known as 
 wind. Thus the sun, when passing through 
 the northern signs of the zodiac, heats the 
 air to the north of the equator, a current 
 rushes therefore from the south, occasioning 
 a constant wind for six months in the same 
 direction. For the other half of the year 
 the wind will blow always from the north, 
 and at the period of the equinoxes, when 
 these winds change their courses, the atmo- 
 sphere of the whole earth is much agitated, 
 whence what are called equinoctical gales 
 occur, while the former are called monsoons, 
 or trade winds, they blow either NE or SE ; 
 the eastern direction being caused by the 
 rotation of the earth on its axis. The variable 
 winds of temperate regions depend also upon 
 other causes, such as evaporation, the fall of 
 rain and snow, which occasions strata of un- 
 equal density, the neighbourhood of moun- 
 tains, state of electricity of the air, &c. 
 
 Wind Guage. (See Anemometer.) 
 
 Wind Gun. (See Air Gun.) 
 
 Windlass, or Windlace. A machine 
 for raising weights, in which a rope or chain 
 is wound about a cylindrical body, moved by 
 several levers, or, as in the case of a windlass 
 for a well, by a handle. The cut shows an 
 ordinary windlass for the latter purpose ; 
 A B being a cylinder upon which the rope is 
 coiled. C the winch to turn it ; and D the 
 bucket. The action of the whole is obvious. 
 
 Windmill. An instrument turned by the 
 wind, intended to grind corn, and for other 
 purposes. Windmills may be horizontal or 
 vertical. 
 
 Windmill, Vertical. That which is com- 
 monly seen consists of a vertical shaft, fur- 
 
 nished with a nearly horizontal spindle at the 
 upper end, and which bears the sails. To 
 enable the whole to turn round so that the sails 
 may catch the wind at any point, there are 
 two methods : one where the upper part rests 
 upon a firm round post or tree, cut down to 
 about 12 feet from the top, the upper end 
 resting in a socket ; thus the whole mill turns 
 together. The second method is called a 
 smock mill, in which the head only is capable 
 of motion. 
 
 Windows. Those apertures in walls 
 through which light is admitted to the in- 
 terior of buildings. 
 
 Window Shutters. Those wooden or 
 iron doors by which windows are sometimes 
 closed. 
 
 Wine, Oil of. (See Oil.) 
 
 Wine, Spirit of. (See Spirit ; also Al- 
 cohol.) 
 
 Wine Stone. Synonymous with tartar. 
 
 Winze. In mining, a small pit or shaft 
 sunk from one level to another for the purpose 
 of ventUation. 
 
 Wiper. A cam, eccentric, or projecting 
 piece attached to a wheel, in order to pro- 
 duce a sudden motion to something which 
 strikes against it in its revolution. {See Break 
 Wheel.) 
 
 Wire Covering Engine. (See Wag- 
 staff.) 
 
 Wire-Draw. To reduce a wire, pipe, or 
 other longitudinal body exceedingly in the 
 transverse section, and at the same time in- 
 creasing it in length. 
 
 Wire -Gauze. Wire woven into a surface, 
 in the same manner as vegetable fibres ai'e 
 into cloth, or rather like a gauze or fine net- 
 work. Wire-gauze is used extensively for 
 window-blinds, and as the cover for Davy's 
 safety lamp, it having the peculiar property 
 of not suffering flame to pass through it. 
 
 WlRTEMBURG SiPHON. (ScC Siphon.) 
 
 Wo AD. A blue dyeing drug, the produce 
 of the British plant, called Isatis tinctoria. 
 Its use is now nearly superseded by indigo. 
 The ancient Britons are said by Phny to 
 have dyed their skins with woad. 
 
 Wolfram. The native tungstate of iron 
 and manganese. It is used by chemists for 
 obtaining tungstic acid and tungsten. 
 
 Wollaston's Barometrical Ther- 
 mometer. (See Barometrical Thermometer.) 
 
 Wollaston's Blow-Pipb. (See Blow- 
 Pipe.) 
 
 Wollaston's Camera Lucida. (See 
 Camera Lucida.) 
 
 Wollaston's Cryophorus. (See Cryo- 
 phorus.) 
 
 Wollaston's Galvanic Battery. This 
 is a trough batteiy, the outer case of which 
 is of porcelain, with divisions across it, in 
 number according to the pairs of elements 
 employed. These elements are zinc and 
 
wc 
 
 wo 
 
 copper plates ; those of copper being doubled 
 around the zinc, so that each zinc plate has 
 the copper plate on each side of it : by this 
 method of arrangement the power of the 
 battery is very greatly increased. A strip of 
 copper is continued from one copper plate 
 to the zinc plate of the next pair, and so on 
 throughout the series. 
 
 
 ip^^^m 
 
 iiiy^llk 
 
 Wollaston's Periscopic Spectacles. 
 (See Periscopic.) 
 
 Wood. The hardest product of vegetation, 
 existing only in trees, and becoming de- 
 posited in them beneath the bark in each 
 succeeding season. Acted upon by chlorine, 
 all woods become colorless. Sulphuric acid 
 converts them first into gum, and then, if 
 assisted by heat, into sugar. In nitric acid 
 wood becomes yellow, finally dissolves, and 
 is converted into oxalic acid. In strong 
 caustic alkaline lyes, in a hot state, wood 
 swells, dissolves, and becomes a blackish 
 brown mass. The uses of wood in the arts 
 are endless, and the names and different kinds 
 of it that are employed in England extremely 
 numerous. Among the woods celebrated for 
 utility rather than beauty, we may rank oak, 
 ash, beech, fir of all kinds, birch, elm, 
 chesnut, apple-tree, poplar, and lime-tree. 
 Among the dye-woods are log-wood, Brazil 
 wood, red saunders, Japan wood, Nicaragua 
 wood, fustic, sumach, walnut, &c. The 
 chief of the fancy or ornamental woods are 
 mahogany, rose-wood, king-wood, tulip-wood, 
 zebra-wood, satin-wood, ebony, bird's-eye- 
 maple, and numerous others. 
 
 Wood, Acid of. Pyroligneous acid, (which 
 see.) 
 
 Wood, Staining of. The giving a color to 
 the surface of wood, different from that it 
 naturally possesses, the object of which is to 
 make it resemble other woods of a more 
 ornamental character ; thus beech- wood bed- 
 flteads are stained of a reddish purple by 
 passing over them a brusbf dipped into a 
 solution of ar<;hil, which is improved by an 
 after-wash of a solution of pearl-ash. For a 
 
 black stain, add I ounce of pearl-ash to 
 8 ounces of log- wood, in chips ; boU them 
 together in 2 quarts of water, and apply hot 
 with a brush ; when dry, brush it a second 
 time with a solution in a quart of water, of 
 I ounce of blue-stone, and 2 ounces of 
 copperas. To stain beech-wood like maho- 
 gany, wash it in a solution of dragon's blood 
 in spirits of wine, or a solution of alkanet 
 root ; this wiU also darken mahogany. To 
 accomplish this latter purpose, so as to make 
 the mahogany very dark, wash it with lime 
 water. 
 
 Wood Bricks. Blocks of woodcut to the 
 form and size of bricks, inserted in the in- 
 terior walls of apartments as holds for the 
 partitioning, &c. 
 
 Wood-Cut, or Wood Engraving. As 
 the name implies, is a cutting or engraving 
 on wood ; also by the latter terra is under- 
 stood the art by which such is produced. 
 Wood-cuts are of two kinds ; in the one, the 
 general surface of the wood is left, and the 
 figures or designs are cut out, as is seen by 
 reference to the word Snow; this is the most 
 easily executed. In the other kind, the wood 
 is cut away, the lines of the design only being 
 left, as is seen in ordinary pictures and illus- 
 trations. The wood employed is, except for 
 very coarse work, that of the box-tree, cut 
 in slices across the grain, i inch thick each, 
 and polished on one surface. In this state 
 the wood engraver receives it. He first 
 whitens the surface somewhat with flake 
 white, water, and size ; then with a fine hard 
 pencil draws the design, reversing every part, 
 so that what is, when printed, to appear on 
 the right hand, must be drawn on the wood 
 to the left hand ; he then by the aid of 
 gravers, or small gouges, (called scaupers,) 
 and chisels, cuts away all the parts of the 
 wood left white, and leaves untouched the 
 pencil lines ; and as these constitute the 
 picture itself, it will be complete when the 
 white parts are removed. A proof is then 
 taken by blacking it with printer's ink, laying 
 a piece of slightly damped paper upon it, and 
 rubbing the back of the paper with a smooth, 
 flat, and hard substance. Wood engravings 
 are inclosed along with the letter-press in 
 printing. (See Cross- Hatching, Engraver, 
 Graver, 8fc.) 
 
 Wooden Press. (See Printing Press.) 
 
 Wood Vinegar, {hee Pyroligneous Acid.) 
 
 Woof. In weaving, those portions of 
 thread or yarn in cloth which lie across the 
 length of the warp. 
 
 Wool. The produce of the coat of the 
 sheep. 
 
 WooTZ. The Indian name for steel. 
 
 Worcester's Steam Engine, The 
 Marquis of Worcester in his extraordinary 
 book, the ** Century of Inventions," (1663,) 
 says — " I have invented an admirable and 
 
wo 
 
 wo 
 
 forceable way to draw up water by fire, 
 which hath no bounds, if the vessel be strong 
 enough." No description is given, but two 
 or three engines have been contrived as 
 illustrating the Marquis's invention. These, 
 although called Worcester's engine, were not 
 invented by him ; and it is very doubtful 
 whether his vague and gasconading remark 
 was ever put in practice by himself. The 
 engines alluded to are as follows : — The first 
 is by Professor Millington ; it is represented 
 below. 
 
 The two spherical vessels A and O have 
 each a pipe, D and F, proceeding from them, 
 and entering the boiler G. These pipes have 
 two stop-cocks, Z and W. There are also 
 four other pipes, two of them opening into 
 the pipe E E, which is 40 feet high, and 
 terminates in a tank U. These pipes have 
 valves at S and X. The other two pipes, 
 V and N, are short, and merely intended as 
 valves between the cistern of water H, and 
 the vessels A and O. B is the fire-grate, 
 shown open. T the same closed. C the 
 outside of the boiler. I the chimney. When 
 steam is generated in the boiler, the cock Z 
 being open, and W closed, it presses upon 
 the water in A, drives it through S, and 
 up E. When Z is closed, and W opened, 
 the steam drives the water from O, while the 
 steam in A becomes gradually condensed ; a 
 fresh supply of water running into A by the 
 Talve V. This alternate action drives the 
 water up the pipe E ; a man being employed 
 to lura the eocks. A second contrivance, by 
 
 Mr. Stuart, also illustrates the Marquis*s 
 invention. 
 
 A is a boiler. C C a pipe having a stop- 
 cock D connecting the boiler with the cold 
 water vessel E, from which proceeds the 
 eduction pipe F. G a pipe and funnel to 
 supply the boiler with water. I a pipe to 
 supply the vessel E. K a valve to prevent 
 the return of the water from F. When the 
 steam from the boiler is allowed to enter E, 
 the water is raised through F, until E is 
 emptied. When this is the case, D is shut, 
 I is opened, and thereby E becomes filled 
 again. The cock I is again closed, and D 
 being opened, the first action of the steam is 
 repeated, and water again forced up the 
 pipe F. 
 
 Words, Luminous. Electrical. (See De" 
 vices.) 
 
 Wormwood, Salt of. (See Salt.) 
 
 Wort. The fermentable infusion of malt 
 or grain. 
 
 Woulfe's Apparatus. A series of two 
 or three necked bottles, called Woulfe's 
 bottles ; intended to retain the different pro- 
 ducts which are the result of chemical evapo- 
 ration or distillation. The number of bottles 
 required for any operation depends upon 
 circumstances. Suppose it be desired to im- 
 pregnate water with carbonic acid gas; a 
 retort or other vessel, in which the gas is 
 
YA 
 
 YE 
 
 generated, is attached to B by the pipe A, 
 jirhich, as well as all the other pipes, fits 
 through a cork. The gas passes into the 
 water with which B is filled ; a part is ab- 
 sorbed, the rest escapes through E. It 
 passes into C, where another pKjrtion is re- 
 tained. The rest flies from F into D, where 
 a third absorption takes place. It might 
 thus be continued along any series of bottles. 
 G and H are safety tubes, (see Tube,) which 
 are useful in preventing accident during any 
 operation. 
 
 Wrkathed Columns. Such columns as 
 are twisted in the form of a screw. They 
 are the sign of a barbarous taste. 
 
 Wrest, or Wrist. The partitions which 
 determine the form of the bucket in an over- 
 shot wheel 
 
 Writing Ink and Fluid may be of 
 various colors. A good black is, however, 
 the most essential. The following receipts for 
 that and other colors are recommended: — 
 Black: For a gallon, take 1 lb. of nut-galls, 
 
 bruised ; 6 oz. of green vitriol ; 6 oz. of gum 
 Senegal, or Arabic ; and 1 gallon of water. 
 The galls to be boiled, and then left to settle. 
 The clear liquor to be added to the vitriol 
 and gum. Japan black ink: The green 
 vitriol is first calcined ; the ink is blacker, 
 but not so durable ; more gum is added than 
 to ordinary ink, and sometimes sugar also. 
 Red ink is made by boiling Brazil-wood in 
 vinegar or water. Log- wood makes it darker 
 colored. Yellow, green, blue, and other 
 colored inks are made by the infusion of 
 gamboge, sap-green, sulphate of indigo, or 
 other pigments. An ink, called Stephens's 
 writing fluid, is said to consist of a tanno- 
 gallate of iron and the sulphate of indigo 
 combined. To make it, boil together nut- 
 galls, indigo, and green vitriol. (See Ink 
 and Vanadium.) 
 
 Wrought Iron. Iron which after having 
 been cast in bars, is again heated and ham- 
 mered, by which it becomes more tough and 
 pliable. 
 
 No word, truly English, 
 begins with X ; the very 
 few known as terms of 
 science are chiefly confined 
 to natural history, and are 
 derived from the Greek 
 language. X, as an initial 
 letter, and in names, has 
 the sound of z, as in Xenophon. When 
 occurring betwen the other letters of a word, 
 it has a different sound, like that of sk, as 
 in excuse ; in Xerxes both the sounds are 
 contained. X, in the Roman notation, stands 
 for 10 ; and on account of its cross-like 
 form is used as a contraction for Christ 
 
 and cross, as Xmas. for Christmas, Xpher, 
 for Christopher, &c. 
 
 Xanthene. The coloring principle of 
 madder. 
 
 Xanthogene, a substance composed of 
 carbon and sulphur, which is a base that 
 becomes acidified by hydrogen, called then 
 hydro -xanthic acid ; the base is called xan- 
 thogene, from the yellow color of its im- 
 pounds. 
 
 Xystos. Among the ancient Greeks was 
 a portico of uncommon length, either covered 
 or open, in which the people used to exercise 
 themselves in running races, &c. 
 
 Is both a consonant and 
 a vowel ; the former at the 
 beginning of words or 
 syllables. It is used instead 
 of i at the end of words, 
 as in thy ; or when two ii 
 would come together, as in 
 dying ; and sometimes for the sake of dis- 
 tinction, as in the word die and dye. In 
 words derived from the Greek, y is made to 
 represent the Greek upsilon, as in syllable, 
 syntax, 8fc. Y, in modem contractions, is 
 intended for th., as ye, the; yr,,your; ym., 
 them, 8fc. 
 
 Y-PiECE. (See Beighton's Steam Engine.) 
 Yarn, Twist, or Thread. The combi- 
 nation of fibrous materials into a linear form 
 
 by tortion. Yam is more applied to woollen 
 and hempen goods ; twist and thread to 
 cotton, linen, and silk. 
 
 Year. The portion of time occupied by 
 the earth in its revolution around the sun, 
 and in which are comprehended the several 
 changes of the seasons. Various circum- 
 stances require that the year should be dis- 
 tinguished by different names and measure- 
 ments, as follows : — The first is the astro- 
 nomical or solar jeax, or that which is de- 
 termined by astronomical observations, and 
 is of two kinds, tropical and sidereal. A 
 tropical or natural solar year is the time 
 which the sun, or rather the earth, employs in 
 passing through the twelve signs of the zodiac, 
 and which contains 365 d., 5 h., 48', 48". 
 
ZA 
 
 ZA 
 
 Tliis is the only natural year, because it 
 always keeps the same seasons in the same 
 months. The sidereal or astral year is the 
 space of time the sun takes in passing from 
 any fixed star till his return to it again. 
 This consists of 365 d., 6h., 9', 11", being 
 20', 29" longer than the tropical year. An 
 anomalistic year is the interval which is 
 occupied by the earth passing from apogee 
 to apogee ; it is greater than the sidereal 
 year, by the time i-equired to describe the 
 annual progression of the apogee. The length 
 of the anomalistic year is 365 d., 6h., 14', 1". 
 Lunar year is the space of twelve lunar 
 months. There are two kinds of lunar years. 
 The astronomical lunar year consists of 
 twelve lunar synodical months, and contains 
 354 d., 8 h., 48', 38", and is therefore 
 10 d., 21 h., 0', 10" shorter than the solar 
 year ; a difference which is the foundation of 
 the epoch. The common lunar year consists 
 of tcvelve lunar civil months, and therefore 
 contains 354 days. The emholismic or inter- 
 calary lunar year consists of thirteen lunar 
 civil months, and therefore contains 384 days. 
 The civil year is that form of the year which 
 every nation has contrived or adopted for 
 
 computing their time by. It is either com- 
 mon or leap year. The common year is that 
 consisting of 365 days, having seven months of 
 31 days each ; four of 30 days ; and one of 28 
 days. Bissextile or leap year contains 366 
 days, as explained under the word Xeo/? Year. 
 
 Yeast. The froth arising from any liquid 
 which is passing the vinous fermentation. 
 
 Yellow. The lightest and warmest of 
 the prismatic colors, situated in the solar 
 spectrum, between the red and blue ; blend- 
 ing with the former to make orange on the 
 one side, and with the blue to make green on 
 the other. Very numerous pigments of a 
 yellow color are used by the painter — some 
 of vegetable origin, as gamboge, Indian 
 yellow, yellow lake, &c. Others derived 
 from minerals, constituting, in some cases, 
 oxydes ; in others, metallic salts. Among 
 the former are king's yellow, Naples yellow 
 orpiment, raw Sienna, yellow ochre, &c 
 Among the latter, the various chrome yellows, 
 mineral yellow, or chloride of lead, iodide of 
 lead, &c. 
 
 Yttria. a rare earth, extracted from the 
 minerals gadolinite and yttrotantalite, being 
 I an oxyde of the metal yttrium. 
 
 No word of Saxon derivation 
 contains this, the last letter of 
 the English alphabet ; and the 
 few words we now have be- 
 ginning with this letter are all 
 derived from other languages, 
 mostly from the Greek. Z has invariably 
 the sound of s, but without the hissing that 
 usually attends it ; or like the sound of this 
 letter in the word rosy and osier. 
 
 Zaffre. The residuum of cobalt, after 
 the sulphur, arsenic, and other volatile matters 
 have been expelled by calcination. 
 
 Zealand (New) Flax. The fibres of the 
 Phormium tenax, a plant of New Zealand. 
 Zamboni's Perpetual Motion. This 
 is a good electrical apparatus, which acts 
 «pon the same principle as Singer's or De 
 Luc's dry pile ; the only difference con- 
 sisting in the form of the instrument, and 
 the material of the small plates. The form 
 is as represented. D is a box containing a 
 drawer : on the centre of the top of the box 
 is a glass pillar, with a steel point at top C ; 
 upon this rests a very light frame -work of 
 wire or wood, with six arras at the lower 
 part, upon each of which is suspended a 
 small strip of thin sheet brass or gold. The 
 drawer is filled with several rows of pieces of 
 paper, about an inch square each, altogether 
 about 20,000 in number : one side of the 
 paper is covered with silver leaf, the other 
 
 painted over with black oxyde of manganese, 
 honey, and water. The papers are arranged 
 so that they should form one continued 
 series throughout. Pieces of tin-foil unite 
 the rows together. One end of this pile is 
 connected with the pole or brass stud A, the 
 other with the contrary pole A. The strips o* 
 metal hanging from the cross arms B B, strike 
 one pole and then proceed to the other to 
 deposit the electrical fluid they acquired by 
 
 ^ 
 
21 
 
 ZU 
 
 the first impulse. So in the rotation the 
 several strips are in like manner affected, and 
 the frame with its various arms is in con- 
 tinued motion, which it will maintain for 
 years. It is necessary that it should be 
 covered with a glass shade to prevent the 
 disturbance of wind, &c. 
 
 Zkine. a soft, tough, elastic substance, 
 obtainable from maize or Indian corn. It is 
 procured by treating the gluten or starch 
 with alcohol, and evaporating the clear 
 solution. 
 
 Zenith. An Arabic word, used in astro- 
 nomy to denote the vertical point of the 
 heavens, or the point directly over our heads. 
 It is, of course, the pole of the horizon. 
 
 Zenith Distance. The arc intercepted 
 between any celestial object and the zenith, 
 being the same as the co-altitude of an object. 
 
 Zetetic Method. An old term for what 
 we now call analytic method or analysis. 
 
 Zigzag. An oi-nament peculiar to Norman 
 architecture. (See Chevron.) 
 
 ZiMOME. The gluten of wheat, treated 
 with alcohol, and reduced to the third part 
 of its bulk. The result is zimome. 
 
 Zinc. A metal of a bluish white color ; 
 lustrous when fresh broken, but soon tarnish- 
 ing in the air. It granulates in irregular 
 crystals, and when cold is brittle, but becomes 
 ductile and malleable at a heat from 220° to 
 300° Fah., and if then rolled out or hammered 
 it retains its ductility aftenvards. It melts 
 at 680°, and with contact of air and a slight 
 increase of heat above this, it burns with a 
 bluish whito brilliant hght, and becomes 
 converted into a copious white oxyde, called 
 the flowers of zinc. Zinc is soluble in most 
 of the acids. It is used greatly in the manu- 
 facture of brass and other alloys ; as a ma- 
 terial for water cisterns, pipes, baths, plates 
 for doors, and for the zincographer ; for 
 voltaic batteries, covering roofs, and numerous 
 other purposes. In commerce it is called 
 spelter. 
 
 ZiNcoDE. The positive pole of a galvanic 
 battery. 
 
 Zincography. The art of drawing upon 
 and printing from zinc. The art, and the 
 whole of the inks and other materials, are 
 precisely similar to those used in lithography, 
 except that, uistead of stone, polished sheets 
 of zinc are used ; and instead of nitric acid 
 to wash over the drawing, and set in the ink, 
 as in lithography, sulphuric acid is usually 
 employed. Zincogi'aphy has this advaintage, 
 that the sheets of zinc are much less cumbrous 
 and more convenient to use and preserve 
 than blocks of stone. 
 
 Zircon. The name of a precious stone ; 
 called also the hyacinth. 
 
 Zirconia. A rare earth, extracted from 
 
 the zircon ; it is an oxyde of zirconium, a 
 substance possessing, externally, none of the 
 metallic characters, but rather resembling 
 ch£u:coal powder, which bums briskly, and 
 almost with explosive violence. 
 
 ZocLE. A name given to a low, plain, 
 square member, forming the base to a column 
 or obelisk. 
 
 Zodiac An imaginary ring or broad 
 circle in the heavens, in the form of a belt or 
 girdle, within which the planets all make 
 their excursions ; in the very centre of it runs 
 the equator or path of the sim in his apparent 
 annual course. Its breadth is 16°. It cuts 
 the equator obliquely at an angle of 23°, 28', 
 and is divided into twelve signs, each of which 
 contains 30°. 
 
 Zodiac, Signs of the. The twelve constel- 
 lations which are assigned to or represent the 
 »' various great divisions of the zodiac. For 
 their names and the symbols by which they are 
 usually expressed, see Astronomical Sym- 
 bols. 
 
 Zodiac of the Comets. A tract in the 
 heavens, which most of the comets, though 
 not all of them, are observed to keep. It is 
 about as broad as the other zodiac, and con- 
 tains the constellations AntinOus, Pegasvs, 
 Andromeda, Taurus, Orion, the Lesser Dog, 
 Hydra, Centaur, Scorpion, and Sagittarius. 
 
 Zodiacal Light. A brightness sometimes 
 observed in the zodiac, resembling that of the 
 galaxy or milky way. It appears at certain 
 seasons, namely, towards the end of winter, 
 or in spring. It resembles a pyramid lying 
 lengthwise, with its axis along the zodiac ; its 
 base being placed obliquely with respect to 
 the horizon. It is supposed to be an elec- 
 trical phenomenon, and similar to the aurora 
 borealis. 
 
 Zone. A division of the earth's surface, 
 by means of parallel circles, chiefly with 
 respect to the degree of heat in the different 
 parts of tliat svirface. The zones are five in 
 number : one extending 23°, 28' on each 
 side of the equator, called the torrid zone. 
 Next from the tropic of Cancer in the north, 
 and the tropic of Capricorn in the south to 
 the polar circles, constituted two temperate 
 zones ; and the circular spaces within the 
 polar circles completed the number ; these are 
 called the north and south frigid zones. 
 
 ZoPHORic Column. Any column support- 
 ing the figure of an animal. 
 
 ZoPHORUs. The frieze or broad member 
 which separates the corruce and architrave. 
 It was so called by the Greeks, because they 
 adorned it with representations of animals. 
 
 ZuMic Acid. An acid discovered in many 
 acescent vegetable substances ; in sour rice ; 
 in sour decoction of carrots, pease, &c. It 
 I is doubtful if distinct from the acetic acid. 
 
CO 
 
 DI 
 
 ADDENDA. 
 
 Abuttals. Boundaries of land. 
 
 Anemonine. An acrid crystallizable 
 substance, obtained from some species of 
 anemone. 
 
 Antarctic. As arctic signifies the north, 
 so antarctic is the south, or those parts of 
 the world opposite to the north. Thus the 
 arctic circle bounds the north frigid zone, 
 and the antarctic circle the south frigid zone ; 
 so the south pole of the world is called the 
 antarctic pole, and the watery or icy regions 
 around it the antarctic ocean. 
 
 Back-Ground. That portion of a picture 
 which is furthest removed from the eye. \ 
 
 Breadth of Light. That part of a 
 picture most brilliantly colored, or where 
 the great portion of light is seen to fall. In 
 historical pictures, the greatest breadth of 
 light should fall upon the principal characters, 
 that the eye may have not merely the action 
 and prominent situation of them, but their 
 greater brilliancy to rest upon. 
 
 Catching Lights. The edges or small 
 parts of objects touched with brilliant colors, 
 to bring them out in relief; for example, 
 the edges of clouds, moon-beams on the 
 water, &c. 
 
 Ceres. The name given by its discoverer, 
 M. Piazze, to a small planet or asteroid, 
 which circulates between the orbits of Mars 
 and Jupiter. It is of a ruddy color ; is 
 surrounded by an extensive and dense at- 
 mosphere ; and with a telescope having the 1 
 magnifying power of 200, exhibits a distinct 
 disc. It performs its revolution round the 
 sun in about 4 years, 7 months, and 10 days. 
 Its mean distance from the sun is nearly 
 2 "669 times that of the earth, and its diameter 
 has been variously estimated at from 163 to 
 1630 miles. 
 
 Circular Polarization of Light. 
 Certain crystals, particularly rock-crystal, or 
 quartz, have the property of dividing a ray of 
 reflected light transmitted through them, so 
 as to show perfect series of rings around the 
 axis of the crystal ; these rings vary with 
 the thickness of the plate of quartz, but they 
 suffer no change by turning the plate round 
 its axis : yet they do become changed when 
 the analyzing plate (see Polarization,) is 
 turned round from right to left; the red 
 changing successively to orange, yellow, 
 green, and violet. 
 
 Cologne, or Cas&el Earth. Two bi- 
 tuminous earths, originating, as it is supposed, 
 from the decomposition of wood. They are 
 used occasionally by the oil painter, as brown 
 for the hair, &c., but are not to be recom- 
 
 mended, as they become lighter by time, and 
 dry very slowly. 
 
 Conflicting Lights in a Picture, are 
 seen when an object is illuminated by two 
 lights at once, as of the sun and of a con- 
 flagration, or a torch-bearing procession by 
 moonlight. 
 
 Contrast. In painting, opposition of two 
 things as to character, whether it be in lines, 
 light, shade, or color. 
 
 Contraction. The substitution of part 
 of a word for the whole of it. Contractions 
 are particularly used in mathematics, as tan. 
 for tangent; sec. for secant; com. for 
 compliment ; step, for supplement ; anff. for 
 angle ; sq. for square ; big. for biquadrate, 
 &c. : and in chemistry, where the initial 
 letter, sometimes with one or two others 
 added to it, designates all the simple sub- 
 stances, as 0. for oxygen ; car. for carbon ; 
 ht/d. for hydrogen ; sulph. for sulphur, and 
 others. 
 
 Cumming's Magnetic Coil. Contri- 
 vances of Professor Cumming to exhibit the 
 polarizing effects of a current of electricity 
 sent through a wire twisted in the form of a 
 flat spiral. There may be several forms. 
 The following are given as examples. The 
 method of suspension and action will be 
 easily understood by reference to the word 
 Sturgeon, where similar apparatus is de- 
 scribed. 
 
 ^b^zsJbss^^ 
 
 Directors. Instruments used in medical 
 electricity to rest against that part of the 
 body through which a shock is to be sent. 
 One director being connected to the outside 
 of a Leyden jar by a chain, and another di- 
 rector to the front part of a medical electro- 
 meter, the shock will pass along the space 
 
GL 
 
 LE 
 
 between the ball of one director and the ball 
 of the other, provided it be a conducting 
 substance, like that of the human body. A 
 director is formed of a glass handle, upon 
 which is fitted a cap, furnished with a brass 
 wire and ball. 
 
 DouBLER, Electrical. (See Condenser.) 
 
 Elizabethan. A peculiar style of archi- 
 tecture used in the age of Queen Elizabeth, 
 and lately coming again into vogue. It may 
 be truly considered as a massive but very 
 inferior style of Gothic. Examples of the 
 peculiar character of the ornamental portion 
 may be seen by reference to the words Car- 
 touch and Scroll, and the initial letter E. 
 
 Firk-Cloud. a fountain of compressed 
 air, upon exactly the same principle as the 
 fountain-glass. The vessel contains ether. 
 It is placed in another vessel of hot water ; this 
 boils the ether, and drives it up the central 
 jet to a considerable height. When set fire to, 
 the particles of the steam of the ether bum 
 vividly, and represent a complete cloud- 
 shaped mass of flame. The ether may be 
 made to give a red, blue, or other colored 
 flame, according as it is imbued with nitrate 
 of strontian or other ingredient. (See Fires, 
 Colored.) 
 
 Flexible Tube. A tube made of three 
 joints of tin or brass, with a short chain 
 from one to the other, the chain being covered 
 with silk. At one end is a moveable joint, 
 to connect it with the prime conductor of an 
 electrical machine ; the other end joint is 
 furnished with a socket in the middle, upon 
 which a director handle may be fixed, and a 
 screw at the end, to connect it to a ball, 
 point, &c. It is for two uses : one to unite 
 the conductor to a stool ; the other to 
 direct the spark immediately to any part of 
 the body, the operator holding the glass 
 handle which fits into the appointed socket. 
 
 Force, Active. Any power which is con- 
 ducive to motion ; the term being used in 
 opposition to vis inertiae, or resistance. 
 
 Forb-Ground. (See Distance.) 
 
 Glaire. White of egg mixed with water. 
 It is \ised by the bookbinder to varnish 
 leather bindings, to put a gloss upon kid 
 shoes, &c. ; also sometimes by the gilder. 
 Such a varnish will wear well if not wetted. 
 
 Glass Cement. Any cement for uniting 
 broken glass ; nothing is better than those 
 recommended under the words Armenian, 
 Vancouver, and Cheese. Gum mastic is 
 often used for the same purpose, and answers 
 
 well, but will not bear heat. White lead is 
 also employed ; it remains firm, but shows a 
 dark mark at the joint. 
 
 Herschel. (See Uranus.) 
 
 Honey-Suckle Ornament. Aparticular 
 shaped ornament introduced into architectural 
 embellishment by the Greeks, and super- 
 seding with them the lotus, so common, and 
 so highly regarded by the Egyptians. The 
 honey- suckle ornament is seen engraved on 
 acroteria ; in friezes, external and internal ; 
 on vases ; in paintings ; and embroidery ; 
 in carvings and metal castings ; in a thousand 
 varied forms — all combining the most elegant 
 combinations of beautiful curves, as witnessed 
 in the following sketch : — 
 
 Insulate. A term of electricity, signifying 
 to separate from the earth and all other con- 
 ducting substances, so that the electrical 
 impulse given to a body may remain with it, 
 and the fluid not be carried off by contact 
 with surrounding bodies. 
 
 Iron Cement. A cement for uniting 
 together, or rather assisting in uniting to- 
 gether pieces of iron, such as the joints of 
 steam boilers, stoves, pipes, &c., so as to 
 prevent leakage. It is made as follows : — 
 Pound together, in a mortar, 2 oz. of sal 
 ammoniac, 1 oz. of sulphur, and 5 lbs. of 
 iron filings. This will become as hard as 
 iron itself in a few days. 
 
 Isochronous. (See Synchronous.) 
 
 IsocHRONiSM. The property of being 
 isochronous. 
 
 Lapidary Cement. Gum mastic is used 
 to fasten gems into their settings, the gum 
 being melted by heat. For larger articles, 
 and also for fixing the stones when they are 
 being cut or engraved, bees'-wax 1 part ; 
 yellow rosin 2 parts ; and plaster of Paris 
 sufiicient to bind it together, and make it 
 white, is mostly employed. 
 
 Letter Balance. Since post letters have 
 been charged by weight, numberless small 
 and elegant table balances have been con- 
 structed ; to specify even a few of them 
 would be tedious. The following is one of 
 the neatest. The letter brings up the counter- 
 poise, weighing down its own side of the 
 
MA 
 
 MO 
 
 scale at the same time, and bringing the hand 
 to a certain part of the graduated arc at top, 
 according as the weight of the letter may be, 
 1, 2, 3, or 4 ounces, or any intermediate 
 portion of them. 
 
 Magdeburg Hemispheres. An appa- 
 ratus used with the air-pump, and intended 
 to prove the weight of the 
 atmosphere. It consists of 
 two hemispherical metallic 
 cups, having their rim 
 widened out and ground, so, 
 that with a little grease be- 
 tween, the cups fit each 
 other air-tight. The upper 
 cup has a handle attached : 
 the lower cup is perforated 
 at bottom, and affixed to a 
 stop-cock, which screws to 
 & stand when not in use, 
 and to the plate of the air- 
 pump when wanted. To 
 show the weight of the at- 
 mosphere, attach the lower 
 cup to the pump plate, carefully rest the 
 upper cup upon it, turn the cock on, (as 
 drawn,) and exhaust the air as much as 
 possible from withinside ; then turn the cock 
 off, remove the apparatus from the pump, 
 and screw a second handle on to the end of 
 the cock. Two persons pulling one at each 
 end will most probably not separate the 
 cups; the strength to do which will be 15 lbs. 
 multiplied by the area of the cups. 
 
 Marine Barometer. The barometer 
 constructed in the usual way would evidently 
 be useless on board a ship at sea, as the 
 pitching and rolling of the vessel would keep 
 the mercury in a state of perpetual oscillation. 
 This inconvenience has been overcome by 
 making the greater portion of the tube of 
 very narrow bore, but terminated by a cylin- 
 drical portion of a larger size, about ^ of 
 an inch in diameter ; the instrument is sus- 
 pended by a spring and gimbals, at a point near 
 
 the top, which is found in each case by trial. 
 Mercurial Gauge. (See Sijjhon Gauge.) 
 Mercurial Pendulum. This pendulum, 
 instead of a weight or bob, has a tube partly 
 filled with mercury. The object is, that the 
 heat of the air which would elongate the 
 pendulum bar may be counteracted by its 
 effect upon the tube of mercury ; for, as the 
 metal rod and the mercury are both affected 
 by the same cause, the one will counteract 
 the other; the elongation of the rod is 
 downwards, making the pendulum longer ; 
 the elongation of the mercury is upwards, 
 like in a thermometer tube, and consequently 
 making it shorter : the centre of gravity of 
 the whole, therefore, remains the same, and 
 the pendulum is of a true length at all times 
 and in all circumstances. 
 
 Messo-Relief. Carvings and castings of 
 such a nature, that the figures or ornaments 
 are neither very prominent, as in alto-relief ; 
 nor depressed, as in bass-relief. 
 
 Metallic Ink, Gold Ink, Silver 
 Ink, &c. These inks are made by grinding 
 gold leaf, silver leaf, or laminae of any other 
 metal with honey, until it forms a uniform 
 paste ; the honey is then washed away with 
 water, and the residuum dried. It is now 
 known as bronze powder. To reduce it to the 
 state of ink it must be mixed with weak 
 gum-water. 
 
 Mid-Distance. (See Distance.) 
 Mountain Barometer. A form given 
 to the ordinary barometer, to render it poi-t- 
 able and convenient for travellers, in ascer- 
 taining the height of mountains, &c. In the 
 brass box A, which covers the cistern of 
 mercury, are two slits made horizontally, 
 precisely similar, and opposite to each other ; 
 these represent the zero or beginning of the 
 scale of inches. The screw B performs a 
 
 double oflfice ; first, it is the means of adjust- 
 ing the surface of the mercury in the glass 
 cistern to zero ; secondly, by screwing it 
 
PA 
 
 RA 
 
 entirely up it incloses all the mercury in the 
 tube, and thus prevents waste in carrying 
 the instrument. By the help of a vernier, 
 the scale of the upper part is divided to 
 the five hundredth of an inch. The screw 
 C, at the top, moves a sliding piece, on which 
 the vernier scale is divided. The barometer 
 is attached to the stand by a ring, in which 
 it turns round with a smooth and steady 
 motion, for the purpose of placing it in the 
 best light for reading off, &c. ; and the tripod 
 stand, when closed, forms a convenient 
 jacking-case for the instrument. 
 
 Neutral Tint. Grey is called by way 
 cf eminence the neutral tint, being the mean 
 letween black and white. It is made by 
 mixing together a transparent red, blue, and 
 yellow ; or else either two of the secondary 
 colors, purple and green ; or green and orange. 
 
 Oil Color Printing. Every kind of 
 printing with ink may truly have this name ; 
 but it particularly appUes to an invention of 
 Mr. Baxter, of Charter House Square, 
 London, whereby the depth and brilliancy 
 of an oil painting is produced by the whole 
 of the colors being laid on and blended 
 together by the operation of the printer's 
 press; the ground-work upon which they 
 are laid being an engraving on metal or 
 wood, and printed in black, neutral tint, or 
 other color, according to the effect ulti- 
 mately to be produced. For each color 
 afterwards to be laid on, a separate wood- 
 cut is so prepared, that it exactly covers an 
 appointed part of the picture^ the edges of 
 the wood-cut being left shrap, if the color 
 is to end in an abrupt line, or hollowed 
 out, or sloped away more or less, where the 
 color is to be gradually softened off. The 
 whole of the wood-blocks, (sometimes thirty 
 in number,) being prepared, a peculiar ink, 
 tinted with the requisite color is taken, and 
 by means of small balls is dabbed upon the 
 block of wood first to be used. The print, 
 by a very nice adjustment with the points of 
 needles, is placed upon the block, and which 
 is already laid upon the table of a printing 
 press, and being passed through the press, 
 the color from the wooden block is impressed 
 upon the print : it is then printed upon in 
 like manner by a second block of wood ; 
 afterwards in regular order by all the rest, 
 until the whole is complete, the picture then 
 assuming the utmost delicacy and power. 
 The fine painted prints of the Death of Mr. 
 Williams, and the Coronation of Her Majesty, 
 by this artist, show strongly the capacity 
 and beauty of the result of the art. 
 
 Oriental Tinting. (See Stencil.) 
 
 Palmer's Blow-Pipe Jet. When it is 
 desired to bum the mixed gases, oxygen and 
 hydrogen, it is desirable that the jet should 
 be so constructed, that they may be united 
 previously to being inflamed, and that they 
 
 shall not return through the jet into the re- 
 servoirs. To avoid the danger which would 
 accrue from this accident, the gases should 
 be kept in separate vessels till^wanted. Mr. 
 Palmer's safety jet is well adapted to meet 
 these various contingencies. Ib.is shown' in 
 section beneath. The stand may be used or 
 not, as foimd most convenient, it forming no 
 part of the contrivance; which consists of 
 two tubes E E, fitted at the outward ends 
 with screws adapted to stop-cock or gas re- 
 ceivers. The end A being connected with 
 the receiver for hydrogen, and the end B 
 with that containing oxygen, the cocks of 
 the respective bladders being turned on, the 
 gases pass through the separate tubes into 
 the chamber, which is filled with the finest 
 wire gauze ; in filtering through this, the 
 gases become perfectly mingled ; they then 
 pass on to the jet, which is secured to the 
 hole D. At E E are two conical valves 
 opening inwards, which allow a free passage 
 for the gases passing in the direction of the 
 arrows, but which, from the nicety of their 
 construction, instantly close if there is any 
 pressure in the opposite direction. 
 
 Picking In. In painting, the restoring of 
 any accidental unevenness or inequality in a 
 tint in a picture, by neatly and carefully 
 covering the unseeihly or deficient spots with 
 a small pencil, and with a tint accurately 
 prepared to match with the parts to be 
 picked in. 
 
 Printer's Mordant. Acetate of alumina, 
 used by the calico printers. (See Mordant.) 
 
 Racemic Acid. A curious modification of 
 tartaric acid, termed, by Berzelius, para- 
 tartaric acid, otherwise called racemic acid, 
 under the supposition that it is peculiar to 
 certain kinds of grapes. It is less soluble 
 than tartaric acid, and contains twice as much 
 water of crystallization. It is obtained by 
 neutralizing the tartar which contains it with 
 soda, and separating the double tartrate of 
 soda and potassa by crystallization. "The 
 double racemate remains in the mother liquor, 
 which, filtered through animal charcoal, and 
 decomposed by a solution of acetate of lead, 
 
RI 
 
 yields a mixed tartrate and racemate of lead ; 
 these diffused through water, and decomposed 
 by sulphuretted hydrogen, furnish a solution 
 of racemic and tartaric acid, from which the 
 former may be perfectly separated by crystal- 
 lization, while the latter remains in the 
 mother liquor." — Brande. 
 
 Reflected Lights. Lights which fall on 
 the shaded sides of objects, by being reflected 
 from water or the like. 
 
 Retort Stand. Any stand used to sup- 
 port a retort. Retort stands usually consist 
 of a solid foot, which supports an upright 
 rod of metal, upon which are fitted three 
 slides, adjustable to any height which may be 
 required by screws ; each slide bears a ring 
 of wire, upon which the bottom or neck of 
 the retort rests ; the rings being of different 
 sizes to suit various apparatus. 
 
 Rice Cement. A kind of paste used in 
 different degrees of hardness, according to 
 the purpose for which it is required. It may 
 be made thin, like the ordinary paper paste, 
 or of nearly a solid consistence ; in the latter 
 case, it is used especially among the Chinese 
 in moulding various ornaments, vvhich, when 
 dry, have much the appearance of ivory. 
 The thinner kind is for the ordinary purpose 
 of common paste, to which it is superior for 
 some delicate purposes, in being more trans- 
 parent. In making it, rice and flour must 
 be used, (not ground rice,) and this boiled 
 for some time. 
 
 Ritchie's Air-Pump. A contrivance of 
 the late Mr. Ritchie, whereby the use of 
 valves, which are always troublesome in 
 pneumatic apparatus, is avoided ; besides 
 which, this air-pump is very simple in for- 
 mation and easily worked. The stand, re- 
 ceiver, pump.plate, &c. are the same as in 
 the ordinary air-pump. The barrel A is the 
 only difference. This (see the cut,) proceeds 
 below the tube leading to the receiver. The 
 piston is quite solid, and works through an 
 air-tight collar at top ; also near the top of 
 the barrel is a small hole or tube D, which 
 
 SC 
 
 gy'-""M'"'TT ', r -'-'"'-' "V^^^^=g?ss 
 
 may be closed by the finger. Upon driving 
 down the piston to its utmost extent, air 
 
 barrel. I 
 
 air nnn. • 
 
 will occupy the upper part of the barrel. 
 Upon drawing up the piston, the air con- 
 tained in the barrel itself will escape by the 
 hole D. When the piston is arrived at the 
 top, the hole is closed by the finger, and the 
 piston thrust down again to C, or below the 
 orifice of the tube B. The barrel is therefore 
 filled with "air from the receiver a second 
 time, which is removed in like manner, and 
 so on as long as may be required to empty 
 the receiver. 
 
 Scintillation. A burning away in bril- 
 liant sparks, as is seen when tools are ground 
 on a dry stone ; when charcoal is burned in 
 oxygen gas, or when certain fire -works are 
 set light to. 
 
 Scraping. An operation whereby a pe- 
 culiar kind of roughness or frothiness is 
 given to water color drawings, so as to 
 imitate what is commonly called a mackerel 
 sky ; and still more especially to give the 
 efiect of splashing water, as the surf of tlie 
 sea, the breaking of the waves, &c. The 
 picture is completely colored with its proper 
 tints ; then the artist takes a pen-knife, 
 sharp towards the point, and scrapes out the 
 color, holding the knife firmly or loosely, 
 according to the effect desired. If the light 
 of moon-beams on a smooth lake be wished 
 for, the knife may be held tightly in the 
 hand ; but if to imitate beating or rippling 
 water, falling snow, &c., the knife should 
 be held very loosely, near the end of the 
 handle, and the point of it be allowed to 
 jump along ; thus taking out specks of color 
 only. 
 
 ^CKKK>i , Magic Lanthorn. A medium upon 
 which are thrown the figures exhibited by the 
 magic Ian thorn, phantasmagoria, &c. For 
 ordinary purposes of the magic lanthorn -a 
 common sheet, pinned tightly against a wall, 
 at 10 or 12 feet distance from the lanthorn, 
 is employed. For the phantasmagoria the 
 screen must be transparent, because the 
 figures are to be seen through it ; for such a 
 screen as this nothing is better than common 
 tissue paper, stretched on a frame ; it may be 
 oiled or not, according to the pleasure of the 
 operator, or be nibbed over with turpentine 
 and bees-wax, so much turpentine being used 
 that the mixture is quite soft. For theatrical 
 exhibitions of this kind, where greater 
 strength is requisite, fine thin muslin is used. 
 It is joined so as to show the seams as little 
 as possible, stretched on a frame or fastened 
 to rollers, and washed over with white wax 
 and turpentine, transparent varnish and tur- 
 pentine, or Canada balsam and turpentine. 
 For the oxy-hydrogen microscope a different 
 screen is necessary. The objects are thrown, 
 as in the ordinary lanthorn, upon a wall, but 
 a sheet pinned up will scarcely offer a surface 
 sufficiently smooth ; therefore for purposes 
 of public exhibition at least, the wall itself 
 
SL 
 
 TI 
 
 is made perfectly smooth and white, or else 
 the screen is made of stiff and wide cloth, 
 covered with paper, and then painted of a 
 pure white color. 
 
 Sharpin's Hydraulic Blow-Pipe. A. 
 m the figure, is a cylindrical tin vessel, 
 13 inches deep and 10 inches in diameter. 
 B is a loose lid, to which is soldered air- 
 tight the vessel C, which is 6^- inches in 
 diameter, but without a bottom, and ap- 
 proaches to within a quarter of an inch of 
 the bottom of the former vessel A. D is a 
 piece of ^-inch lead pipe, with a tap at the 
 lower end, which communicates with the 
 interior of the vessel C. E is a piece of 
 ■|-inch pipe, which also communicates with 
 the vessel C. F is the lamp. G G are two 
 pins of wire, to prevent the lid from being 
 lifted up by the pressure of the water when 
 in action. I is a lip, which must be left un- 
 covered, so as to allow the air free access to 
 the space between the vessels A and B. 
 
 ^.-JGE 
 
 
 m 
 
 )^G 
 
 To use the blow-pipe, take off the lid, 
 and nearly half fill the vessel A with water ; 
 then put on the lid, and fasten it down by 
 the wire pins G G. Put a glass nozzle on 
 the pipe E ; open the tap, and blow down 
 the pipe D, so as to force all the water out 
 of the vessel C. Then shut the tap, and 
 you will have a steady stream of air for about 
 three minutes, providing the orifice in the 
 glass nozzle be not too large. 
 
 Slider. Any thing which slides, particu- 
 larly those oblong pieces of glass, inclosed in 
 a wooden frame and covered with painted 
 devices, which are illuminated and magnified 
 by the magic lanthorn, phantasmagoria, &c. 
 The difference between the sliders fit for 
 the two instruments consists in the general 
 ground of those used with the magic lanthorn 
 being left uncolored, and those of the phan- 
 tasmagoria being blackened. The size of 
 the slider must, of course, be accordant to 
 the size of the lanthorn with which it is to be 
 used. It may be of a fixed unchangeable 
 
 device, as the picture of a ship in full sail ; 
 or it may change, and assume a different as- 
 pect, as the ship on fire ; or, thirdly, one 
 portion may be fixed, and figures move across 
 it. The first effect is produced by a mere 
 painting on the glass. Changes may be given 
 by two or more glasses being inserted in the 
 same frame ; all but one glass being move- 
 able either sideways or up and down. Upon 
 these other glasses the second parts of the 
 picture, for instance, the flames of the ship, 
 or the moving objects are to be depicted. 
 To paint the sliders : — Draw the design on a 
 piece of paper ; lay it under the glass, sketch 
 the outline with a fine brush, dipped in very 
 dark color, mixed with varnish, and after- 
 wards fill up the outlines with the various 
 colors requisite. These must be all trans- 
 parent, such as are recommended for trans- 
 parent painting, mixed with mastic or other 
 colorless varnish. (See Transparent and 
 Glass Painting.) 
 
 Spelter. A common nameamongfounders, 
 and others, for metallic zinc. 
 
 Spottiness in a Picture. A part or 
 parts either of light or of dark, too con- 
 spicuous to agree with the situation in the 
 scene. The correction of such spottiness 
 is necessary to the preservation of keeping. 
 
 Teinoscope. By combining a concave 
 lens of a substance, having a higher dispersive 
 power than the convex object glass of the 
 achromatic telescope, its color may be 
 corrected without destroying the whole of the 
 refraction produced by it. From numerous 
 experiments made by Dr. Brewster, to de- 
 termine the inequality of the length of the 
 different colored spaces in spectra of equal 
 lengths, he found that the least and most 
 refrangible colors might be destroyed, and 
 refraction produced when he employed two 
 prisms of the same substance, provided that 
 the prism, with the least refractive angle, 
 was inclined so that the incident rays entered 
 obliquely, by which means the dispersion is 
 increased in a greater ratio than the refraction. 
 From this very curious circumstance of pro- 
 ducing refraction without color by two prisms 
 of the same substance. Dr. Brewster has 
 proposed that opera glasses should be con- 
 structed, and to which the name of teinoscope 
 has been given. 
 
 Tilley's Hydraulic Blow-Pipe. The 
 structure of this instrument, and which was 
 invented previously to that of Mr. Sharpin's, 
 (see Sharpin,) is very similar to it. 
 
 A is the outer vessel, which is square. B 
 a division across it. D a pipe fitted with a 
 cock that may be turned off, or a valve 
 inside, which opens downwards. E is the 
 jet, through which issues the blast of air, or 
 oxygen, supposing such supplied to the 
 instrument previously. F the lamp. To 
 use the instrument, blow strongly into D, 
 
TI 
 
 WO 
 
 the jet E being either furnished with a cock, 
 or made so that when it is partly turned 
 
 round, it may shut off the communication 
 with the inside of A. A will become filled 
 with the air from the lungs, and drive the 
 water into B, compressing the air above it. 
 When the operator ceases to blow, and the jet 
 E is turned towards the flame, the elasticity 
 of the air in B will press upon the surface of 
 
 the water, drive it into A, and expel the air 
 in A, through the jet, producing what is re- 
 quired, namely, a strong and regular blast. 
 
 Tone of a Picture. The general effect 
 or appearance of the coloring. 
 
 Wollaston's Steam Apparatus. Such 
 is the somewhat indefinite name given to a 
 small but neat contrivance 
 of Dr. WoUaston, to illustrate 
 the principle of the con- 
 densing steam engine. It is 
 represented annexed, and 
 consists of a glass flask fitted 
 with a belt outside, and 
 handle screwed to the belt. 
 Inside it has a solid piston 
 working with little friction, 
 yet steam-tight, up and down. 
 A little water or ether is 
 placed in the bulb of the flask 
 and made to boil ; the piston 
 is then put in, and the bulb being dipped for 
 a moment in cold water, the steam withinside 
 condenses, and the piston descends ; making 
 the liquid boil a second time drives up 
 the piston, &c. ; thus the piston rises at 
 every formation, and falls at every con- 
 densation of the steam 
 
 ERRATA AND NOTICES. 
 
 Fraction. In the explanation of this word, reverse the position of the words " numerator " and 
 •' denominator." 
 
 Sail, or Whip. After '* miles " insert " per hour." 
 
 SiLVKBiNo Glass Globes. For "1 part by weight of lead, J part of lead, 8;c.;" read "I part by 
 weight of bismuth, | part of lead, &c." 
 
 The words Carbazotic Acin, Cragkeb, and one or two more words are accidentally misplaced. A few 
 others are necessarily so, because of the cuts accompanying them. 
 
 Note. — Agricultural and Gardenino Instruments, although first intended to be introduced, were 
 afterwards purposely omitted, as the space they would have occupied would have been considerable. 
 
THIS BOOK IS DUE ON THE LAST DATE 
 STAMPED BELOW 
 
 RENEWED BOOKS ARE SUBJECT TO IMMEDIATE 
 RECALL 
 
 LIBRARY, UNIVERSITY OF CALIFORNIA, DAVIS 
 
 Book Slip-50m-12,'64(F772s4)458 
 
361830 
 
 Francis, G.W. 
 
 Dictionary of the 
 arts, sciences and 
 manufactures • 
 
 T9 
 F8l 
 
 LIBRARY 
 
 UNIVERSITY OF CALIFORNIA 
 
 DAVIS