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 THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 OF CALIFORNIA 
 
 PRESENTED BY 
 
 PROF. CHARLES A. KOFOID AND 
 MRS. PRUDENCE W. KOFOID 
 
 &> 
 
 
 "A . i 
 
 of cleanup up mailers WhicTiTfequently come under no 1 ice in conversation, but 
 are only known in a vague and obscure way." Chambers' Journal. 
 
 V Of the above popular Work 10,000 Copies were sold within Ten 
 Months from the first day of its publication. 
 
 KENT AND CO. (LATE BOGUE), FLEET STEEET. 
 
NEW WORK ON PAINTING. 
 
 Just ready, in small 8vo, with Frontispiece and Vignette, 
 
 PAINTING 
 POPULARLY EXPLAINED; 
 
 WITH 
 
 j* Jratfia jrf 
 
 AND 
 
 HISTOKICAL NOTICES OF ITS PEOGBESS, 
 
 BY 
 
 THOMAS J. GULLICK, PAINTER, 
 
 AND 
 
 JOHN TIMES, F.S.A. 
 
 THE plan of this work is thus sketched in the Intro- 
 duction : 
 
 "There have been in the history of Art, four grand styles of 
 imitating Nature Tempera, Encaustic, Fresco, and Oil. These, 
 together with the minor modes of Painting, we propose arranging 
 in something like chronological sequence but our design being to 
 offer an explanation of the Art derived from practical acquaintance, 
 rather than attempt to give its history, we shall confine ourselves 
 for the most part to so much only of the History of Painting as is 
 necessary to elucidate the origin of the different practices which have 
 obtained at different periods." 
 
 By this means, the Authors hope to produce a work which may 
 be valuable to the Amateur, and interesting to the Connoisseur, the 
 Artist, and the General Reader. 
 
 LONDON: 
 KENT & CO. (LATE BOGUE), FLEET STREET. 
 
MOUTH OF THE GREAT ROSSE TELESCOPE, AT PAK80NSTOWN. 
 FROM A PHOTOGRAPH. 
 
Things not generally Known 
 Familiarly Explained. 
 
 CURIOSITIES OF SCIENCE, 
 
 fast an* present. 
 A BOOK FOR OLD AND YOUNG. 
 
 BY JOHN TIMES, F.S.A. 
 
 AUTHOR OF THINGS NOT GKNERALI.Y KNOWN; AND EDITOR OF THE 
 YF.AR-BOOK OF FACTS. 
 
 Model of the Safety-Lamp, made by Sir Humphry Davy's own hand 
 in the possession of the Royal Society. 
 
 LONDON: 
 KENT AND CO. (LATE BOGUE), FLEET STREET. 
 
 MDCCCLYIII. 
 
The Author reserves the right of authorising a Translation oj this Work. 
 
 LONDON : 
 
 PRINTED BY LEVEY, ROBSON, AND FRANKLYJT, 
 Great New Street end Fetter Lane. 
 
GENTLE READER, I 
 
 The volume of "CURIOSITIES" which I here present to your 
 notice is a portion of the result of a long course of reading, obser- 
 vation, and research, necessary for the compilation of thirty volumes 
 of "Arcana of Science" and "Year -Book of Facts," published 
 from 1828 to 1858. Throughout this period nearly half of the 
 Psalmist's "days of our years" I have been blessed with health 
 and strength to produce these volumes, year by year (with one 
 exception), upon the appointed day; and this with unbroken at- 
 tention to periodical duties, frequently rendered harassing or 
 ungenial. Nevertheless, during these three decades I have found 
 my account in the increasing approbation of the reading public, 
 which has been so largely extended to the series of " THINGS NOT 
 GENERALLY KNOWN," of which the present volume of" CURIOSITIES 
 OF SCIENCE" is an instalment. I need scarcely add, that in its pro- 
 gressive preparation I have endeavoured to compare, weigh, and 
 consider, the contents, so as to combine the experience of the Past 
 with the advantages of the Present. 
 
 In these days of universal attainments, when Science becomes 
 not merely a luxury to the rich, but bread to the poor, and when 
 the very amusements as well as the conveniences of life have taken 
 a scientific colour, it is reasonable to hope that the present volume 
 may be acceptable to a large class of seekers after " things not 
 generally known." For this purpose, I have aimed at soundness as 
 well as popularity; although, for myself, I can claim little beyond 
 being one of those industrious " ants of science" who garner facts, 
 and by selection and comparison adapt them for a wider circle of 
 readers than they were originally expected to reach. In each case, 
 as far as possible, these "CURIOSITIES" bear the mint-mark of au- 
 thority; and in the living list are prominent the names of Humboldt 
 and Herschel, Airy and Whewell, Faraday, Brewster, Owen, and 
 Agassiz, Maury, Wheatstone, and Hunt, from whose writings and 
 researches the following pages are frequently enriched. 
 
 The sciences here illustrated are, in the main, Astronomy and 
 Meteorology ; Geology and Paleontology ; Physical Geography ; 
 Sound, Light, and Heat; Magnetism and Electricity, the latter 
 with special attention to the great marvel of our times, the Elec- 
 tro-magnetic Telegraph. I hope, at no very distant period, to ex- 
 tend the " CURIOSITIES" to another volume, to include branches of 
 Natural and Experimental Science which are not here presented. 
 
 I. T. 
 
 November 1858. 
 
 M35S761 
 
CONTENTS. 
 
 PAGE 
 
 INTRODUCTORY . I_IQ 
 
 PHYSICAL PHENOMENA 11-26 
 
 SOUND AND LIGHT 27-53 
 
 ASTRONOMY 54-103 
 
 GEOLOGY AND PALEONTOLOGY . . . . 104-145 
 
 METEOROLOGICAL PHENOMENA 146-169 
 
 PHYSICAL GEOGRAPHY OF THE SEA .... 170-192 
 
 MAGNETISM AND ELECTRICITY 193-219 
 
 THE ELECTRIC TELEGRAPH 220-228 
 
 MISCELLANEA , . 229-241 
 
&{u dT0ttibpb.ce. 
 
 THE GREAT ROSSE TELESCOPE. 
 
 The originator and architect of this magnificent instrument had long 
 been distinguished in scientific research as Lord Oxmantown ; and may 
 be considered to have gracefully commemorated his succession to the 
 Earldom of Rosse, and his Presidency of the Royal Society, by the com- 
 pletion of this marvellous work, with which his name will be hereafter 
 indissolubly associated. 
 
 The Great Reflecting Telescope at Birr Castle (of which the Fron- 
 tispiece represents a portion*) will be found fully described at pp. 96-99 
 of the present volume of Curiosities of Science. 
 
 This matchless instrument has already disclosed "forms of stellar 
 arrangement indicating modes of dynamic action never before contem- 
 plated in celestial mechanics." "In these departments of research, 
 the examination of the configurations of nebulae, and the resolution of 
 nebulae into stars (says the Rev. Dr. Scoresby), the six-feet speculum 
 has had its grandest triumphs, and the noble artificer and observer the 
 highest rewards of his talents and enterprise. Altogether, the quan- 
 tity of work done during a peiiod of about seven years including a 
 winter when a noble philanthropy for a starving population absorbed the 
 keenest interests of science has been decidedly great ; and the new- 
 knowledge acquired concerning the handiwork of the great Creator 
 amply satisfying of even sanguine expectation." 
 
 SIR HUMPHRY DAVY'S OWN MODEL OF HIS SAFETY-LAMP. 
 
 Of the several contrivances which have been proposed for safely light- 
 ing coal-mines subject to the visitation of fire damp, or carburetted 
 hydrogen, the Safety- Lamp of Sir Humphry Davy is the only one which 
 has ever been judged safe, and been extensively employed. The in- 
 ventor first turned his attention to the subject in 1815, when Davy 
 began a minute chemical examination of fire-damp, and found that it 
 required an admixture of a large quantity of atmosphei'ic air to render 
 it explosive. He then ascertained that explosions of inflammable gases 
 were incapable of being passed through long narrow metallic tubes, 
 and that this principle of security was still obtained by dimiiiishing 
 their length and increasing their number. This fact led to trials upon 
 sieves made of wire-gauze ; when Davy found that if a piece of wire- 
 gauze was held over the flame of a lamp, or of coal-gas, it prevented 
 the flame from passing ; and he ascertained that a flame confined in a 
 cylinder of very fine wire-gauze did not explode even in a mixture of 
 oxygen and hydrogen, but that the gases burnt in it with great vivacity. 
 
 These experiments served as the basis of the Safety-Lamp. The 
 apertures in the gauze, Davy tells us in his work on the subject, should 
 not be more than ^d of an inch square. The lamp is screwed on to 
 the bottom of the wire-gauze cylinder. When it is lighted, and gradu- 
 ally introduced into an atmosphere mixed with fire-damp, the size and 
 length of the flame are first increased. When the inflammable gas forms 
 as much as T \th of the volume of air, the cylinder becomes filled with a 
 feeble blue flame, within which the flame of the wick burns brightly, and 
 the light of the wick continues till the fire-damp increases to ith or -J-th ; 
 
 * From a photograph, with figures, to show the relative size of the tube aperture . 
 
Viii THE VIGNETTE. 
 
 it is then lost in the flame of the fire-damp, which now fills the cylinder 
 with a pretty strong light ; and when the foul air constitutes one-third 
 of the atmosphere it is no longer fit for respiration, and this ought to 
 be a signal to the miner to leave that part of the workings. 
 
 Sir Humphry Davy presented his first communication respecting 
 his discovery of the Safety- Lamp to the Royal Society in 1815. This 
 was followed by a series of papers remarkable for their simplicity and 
 clearness, crowned by that read on the llth of January 1816, when the 
 principle of the Safety- Lamp was announced, and Sir Humphry pre- 
 sented to the Society a model made by his own hands, which is to this 
 day preserved in the collection of the Royal Society at Burlington House.' 
 From this interesting memorial the Vignette has been sketched. 
 
 There have been several modifications of the Safety-Lamp, and the 
 merit of the discovery has been claimed by others, among whom was 
 Mr. George Stephenson ; but the question was set at rest forty-one 
 years since by an examination, attested by Sir Joseph Banks, P.R.S., 
 Mr. Brande, Mr. Hatchett, and Dr. Wollaston, and awarding the inde- 
 pendent merit to Davy. 
 
 A more substantial, though not a more honourable, testimony of 
 approval was given by the coal-owners, who subscribed 2500^. to pur- 
 chase a superb service of plate, which was suitably inscribed and pre- 
 sented to Davy.* 
 
 Meanwhile the Report by the Parliamentary Committee " cannot 
 admit that the experiments (made with the Lamp) have any tendency 
 to detract from the character of Sir Humphry Davy, or to disparage 
 the fair value placed by himself upon his invention. The improvements 
 are probably those which longer life and additional facts would have 
 induced him to contemplate as desirable, and of which, had he not been 
 the inventor, he might have become the patron." 
 
 The principle of the invention may be thus summed up. In the 
 Safety-Lamp, the mixture of the fire-damp and atmospheric air within 
 the cage of wire-gauze explodes upon coming in contact with the flame ; 
 but the combustion cannot pass through the wire-gauze, and being there 
 imprisoned, cannot impart to the explosive atmosphere of the mine any 
 of its force. This effect has been erroneously attributed to a cooling 
 influence of the metal. 
 
 Professor Playfair has eloquently described the Safety- Lamp of Davy 
 as a present from philosophy to the arts ; a discovery in no degree the 
 effect of accident or chance, but the result of patient and enlightened 
 research, and strongly exemplifying the great use of an immediate and 
 constant appeal to experiment. After characterising the invention as 
 the shutting-up in a net of the most slender texture a most violent and 
 irresistible force, and a power that in its tremendous effects seems to 
 emulate the lightning and the earthquake, Professor Playfair thus con- 
 cludes : " When to this we add the beneficial consequences, and the 
 saving of the lives of men, and consider that the effects are to remain 
 as long as coal continues to be dug from the bowels of the earth, it may 
 be fairly said that there is hardly in the whole compass of art or science 
 a single invention of which one would rather wish to be the author. . . . 
 This," says Professor Playfair, " is exactly such a case as we should 
 choose to place before Bacon, were he to revisit the earth ; in order to 
 give him, in a small compass, an idea of the advancement which philo- 
 sophy has made since the time when he had pointed out to her the 
 route which she ought to pursue." 
 
 * Weld's History of the Royal Society, vol. ii. p. 188. 
 
CURIOSITIES OF SCIENCE. 
 
 Entrotiuctorg. 
 
 SCIENCE OF THE ANCIENT WORLD. 
 
 IN every province of human knowledge where we now possess 
 a careful and coherent interpretation of nature, men began by 
 attempting in bold flights to leap from obvious facts to the 
 highest point of generality to some wide and simple principle 
 which after-ages had to reject. Thus, from the facts that all 
 bodies are hot or cold, moist or dry, they leapt at once to the 
 doctrine that the world is constituted of four elements earth, 
 air, fire, water ; from the fact that the heavenly bodies circle 
 the sky in courses which occur again and again, they at once 
 asserted that they move in exact circles, with an exactly uni- 
 form motion ; from the fact that heavy bodies fall through the 
 air somewhat faster than light ones, it was assumed that all 
 bodies fall quickly or slowly exactly in proportion to their 
 weight ; from the fact that the magnet attracts iron, and that 
 this force of attraction is capable of increase, it was inferred 
 that a perfect magnet would have an irresistible force of at- 
 traction, and that the magnetic pole of the earth would draw 
 the nails out of a ship's bottom which came near it ; from the 
 fact that some of the finest quartz crystals are found among 
 the snows of the Alps, it was inferred that the crystallisation 
 of gems is the result of intense and long-continued cold : and 
 so on in innumerable instances. Such anticipations as these 
 constituted the basis of almost all the science of the ancient 
 world ; for such principles being so assumed, consequences were 
 drawn from them with great ingenuity, and systems of such 
 deductions stood in the place of science. Edinburgh Review, 
 No. 216. 
 
 SCIENCE AT OXFORD AND CAMBRIDGE. 
 
 The earliest science of a decidedly English school is due, 
 for the most part, to the University of Oxford, and specially 
 to Merton College, a foundation of which Wood remarks, that 
 
 B 
 
Things not generally Known. 
 
 there was no other for two centuries, either in Oxford or Paris, 
 which could at all come near it in the cultivation of the sci- 
 ences. But he goes on to say that large chests full of the 
 writers of this college were allowed to remain untouched by 
 their successors for fear of the magic which was supposed to be 
 contained in them. Nevertheless, it is not difficult to trace 
 the liberalising effect of scientific study upon the University in 
 general, and Merton College in particular ; and it must be 
 remembered that to the cultivation of the mind at Oxford we 
 owe almost all the literary celebrity of the middle ages. In 
 this period the University of Cambridge appears to have ac- 
 quired no scientific distinction. Taking as a test the acqui- 
 sition of celebrity on the continent, we find that Bacon, Sa- 
 crobosco, Greathead, Estwood, <fcc. were all of Oxford. The 
 latter University had its morning of splendour while Cambridge 
 was comparatively unknown ; it had also its noonday, illus- 
 trated by such men as Briggs, Wren, Wallis, Halley, and 
 Bradley. 
 
 The age of science at Cambridge may be said to have begun 
 with Francis Bacon ; and but that we think much of the dif- 
 ference between him and his celebrated namesake lies more in 
 time and circumstances than in talents or feelings, we would 
 rather date from 1600 with the former than from 1250 with 
 the latter. Praise or blame on either side is out of the ques- 
 tion, seeing that the earlier foundation of Oxford, and its 
 superiority in pecuniary means, rendered all that took place 
 highly probable ; and we are in a great measure indebted for 
 the liberty of writing our thoughts, to the cultivation of the 
 liberalising sciences at Oxford in the dark ages. 
 
 With regard to the University of Cambridge, for a long 
 time there hardly existed the materials of any proper instruc- 
 tion, even to the extent of pointing out what books should be 
 read by a student desirous of cultivating astronomy. 
 
 PLATO'S SURVEY OF THE SCIENCES. 
 
 Plato, like Francis Bacon, took a review of the sciences of his time : 
 he enumerates arithmetic and plane geometry, treated as collections 
 of abstract and permanent truths ; solid geometry, which he *' notes 
 as deficient" in his time, although in fact he and his school were in 
 possession of the doctrine of the " five regular solids ;" astronomy, iu 
 which he demands a science which should be elevated above the mere 
 knowledge of phenomena. The visible appearances of the heavens 
 only suggest the problems with which true astronomy deals ; as beau- 
 tiful geometrical diagrams do not prove, but only suggest geometrical 
 propositions. Finally. Plato notices the subject of harmonics, in which 
 he requires a science which shall deal with truths more exact than the 
 ear can establish, as in astronomy he requires truths more exact than 
 the eye can assure us of. 
 
 In a subsequent paper Plato speaks of Dialectic as a still higher 
 
Curiosities of Science. 
 
 element of a philosophical education, fitted to lead men to the know- 
 ledge of real existences and of the supreme good. Here he describes 
 dialectic by its objects and purpose. In other places dialectic is spoken 
 of as a method or process of analysis ; as in the Pkcedrus, where Socrates 
 describes a good dialectician as one who can divide a subject according 
 to its natural members, and not miss the joint, like a bad carver. 
 Xenophon says that Socrates derived dialectic from a term implying 
 to divide a subject into parts, which Mr. Grote thinks unsatisfactory as 
 an etymology, but which has indicated a practical connection in the 
 Socratic school. The result seems to be that Plato did not establish 
 any method of analysis of a subject as his dialectic ; but he conceived 
 that the analytical habits formed by the comprehensive study of the 
 exact sciences, and sharpened by the practice of dialogue, would lead 
 his students to the knowledge of first principles. Dr. Whewell. 
 
 FOLLY OF ATHEISM. 
 
 Morphology, in natural science, teaches us that the whole 
 animal and vegetable creation is formed upon certain funda- 
 mental types and patterns, which can be traced under various 
 modifications and transformations through all the rich variety 
 of things apparently of most dissimilar build. But here and 
 there a scientific person takes it into his foolish head that there 
 may be a set of moulds without a moulder, a calculated grada- 
 tion of forms without a calculator, an ordered world without 
 an ordering God. Now, this atheistical science conveys about 
 as much meaning as suicidal life : for science is possible only 
 where there are ideas, and ideas are only possible where there 
 is mind, and minds are the offspring of God ; and atheism 
 itself is not merely ignorance and stupidity, it is the purely 
 nonsensical and the unintelligible. ProfessorBlackie; Edin- 
 burgh Essays, 1856. 
 
 THE ART OF OBSERVATION. 
 
 To observe properly in the very simplest of the physical 
 sciences requires a long and severe training. No one knows 
 this so feelingly as the great discoverer. Faraday once said, 
 that he always doubts his own observations. Mitscherlich on 
 one occasion remarked to a man of science that it takes 
 fourteen years to discover and establish a single new fact in 
 chemistry. An enthusiastic student one day betook himself to 
 Baron Cuvier with the exhibition of a new organ a muscle 
 which he supposed himself to have discovered in the body of 
 some living creature or other ; but the experienced and saga- 
 cious naturalist kindly bade the young man return to him with 
 the same discovery in six months. The Baron would not even 
 listen to the student's demonstration, nor examine his dissec- 
 tion, till the eager and youthful discoverer had hung over the 
 object of inquiry for half a year ; and yet that object was a 
 mere thing of the senses. North-British Review, No. 18. 
 
Things not generally Known. 
 
 MUTUAL RELATIONS OF PHENOMENA. 
 
 In the observation of a phenomenon which at first sight 
 appears to be wholly isolated, how often may be concealed the 
 germ of a great discovery ! Thus, when Galvani first stimu- 
 lated the nervous fibre of the frog by the accidental contact of 
 two heterogeneous metals, his contemporaries could never have 
 anticipated that the action of the voltaic pile would discover 
 to us in the alkalies metals of a silver lustre, so light as to 
 swim on water, and eminently inflammable ; or that it would 
 become a powerful instrument of chemical analysis, and at the 
 same time a thermoscope and a magnet. When Huyghens first 
 observed, in 1678, the phenomenon of the polarisation of light, 
 exhibited in the difference between two rays into which a pencil 
 of light divides itself in passing through a doubly refracting 
 crystal, it could not have been foreseen that a century and a 
 half later the great philosopher Arago would, by his discovery of 
 chromatic polarisation, be led to discern, by means of a small frag- 
 ment of Iceland spar, whether solar light emanates from a solid 
 body or a gaseous covering ; or whether comets transmit light 
 directly, or merely by reflection. Humboldi's Cosmos, vol. i. 
 
 PRACTICAL RESULTS OF THEORETICAL SCIENCE. 
 
 What are the great wonders, the great sources of man's 
 material strength, wealth, and comfort in modern times? The 
 Railway, with its mile-long trains of men and merchandise, 
 moving with the velocity of the wind, and darting over chasms 
 a thousand feet wide ; the Electric Telegraph, along which 
 man's thoughts travel with the velocity of light, and girdle the 
 earth more quickly than Puck's promise to his master ; the 
 contrivance by which the Magnet, in the very middle of a strip 
 of iron, is still true to the distant pole, and remains a faithful 
 guide to the mariner ; the Electrotype process, by which a 
 metallic model of any given object, unerringly exact, grows 
 into being like a flower. Now, all these wonders are the result 
 of recent and profound discoveries in theoretical science. The 
 Locomotive Steam-engine, and the Steam-engine in all its other 
 wonderful and invaluable applications, derives its efficacy from 
 the discoveries, by Watt and others, of the laws of steam. The 
 Railway Bridge is not made strong by mere accumulation of 
 materials, but by the most exact and careful scientific exami- 
 nation of the means of giving the requisite strength to every 
 part, as in the great example of Mr. Stephenson's Britannia 
 Bridge over the Menai Strait. The Correction of the Magnetic 
 Needle in iron ships it would have been impossible for Mr. 
 Airy to secure without a complete theoretical knowledge of 
 
Curiosities of Science. 
 
 the laws of Magnetism. The Electric Telegraph and the Elec- 
 trotype process include in their principles and mechanism the 
 most complete and subtle results of electrical and magnetical 
 theory. Edinburgh Review, No. 216. 
 
 PEKPETUITY OF IMPROVEMENT. 
 
 In the progress of society all great and real improvements 
 are perpetuated : the same corn which, four thousand years 
 ago, was raised from an improved grass by an inventor wor- 
 shiped for two thousand years in the ancient world under the 
 name of Ceres, still forms the principal food of mankind ; and 
 the potato, perhaps the greatest benefit that the old lias derived 
 from the new world, is spreading over Europe, and will con- 
 tinue to nourish an extensive population when the name of the 
 race by whom it was first cultivated in South America is for- 
 gotten. Sir H. Davy. 
 
 THE EARLIEST ENGLISH SCIENTIFIC TREATISE. 
 
 Geoffrey Chaucer, the poet, wrote a treatise on the Astro- 
 labe for his son, which is the earliest English treatise we have 
 met with on any scientific subject. It was not completed ; and 
 the apologies which Chaucer makes to his own child for wilting 
 in English are curious ; while his inference that his son should 
 therefore " pray God save the king that is lord of this lan- 
 guage," is at least as loyal as logical. 
 
 PHILOSOPHERS' FALSE ESTIMATES OF THEIR OWN LABOURS. 
 
 Galileo was confident that the most important part of his 
 contributions to the knowledge of the solar system was his 
 Theory of the Tides a theory which all succeeding astrono- 
 mers have rejected as utterly baseless and untenable. Des- 
 cartes probably placed far above his beautiful explanation of 
 the rainbow, his d priori theory of the existence of the vortices 
 which caused the motion of the planets and satellites. New- 
 ton perhaps considered as one of the best parts of his optical 
 researches his explanation of the natural colour of bodies, 
 which succeeding optical philosophers have had to reject ; and 
 he certainly held very strongly the necessity of a material cause 
 for gravity, which his disciples have disregarded. Davy looked 
 for his greatest triumph in the application of his discoveries to 
 prevent the copper bottoms of ships from being corroded. And 
 so in other matters. Edinburgh Review, No. 216. 
 
 RELICS OF GENIUS. 
 
 Professor George Wilson, in a lecture to the Scottish So- 
 ciety of Arts, says: "The spectacle of these things ministers 
 
6 Things not generally Known. 
 
 only to the good impulses of humanity. Isaac Newton's tele- 
 scope at the Royal Society of London ; Otto Guericke's air- 
 pump in the Library at Berlin ; James Watt's repaired New- 
 comen steam-engine in the Natural-Philosophy class-room of 
 the College at Glasgow ; Fahrenheit's thermometer in the cor- 
 responding class-room of the University of Edinburgh ; Sir H. 
 Davy's great voltaic battery at the Royal Institution, London, 
 and his safety-lamp at the Royal Society ; Joseph Black's 
 pneumatic trough in Dr. Gregory's possession ; the first wire 
 which Faraday made rotate electro-magnetically, at St. Bar- 
 tholomew's Hospital ; Dalton's atomic models at Manchester ; 
 and Kemp's liquefied gases in the Industrial Museum of Scot- 
 land, are alike personal relics, historical monuments, and 
 objects of instruction, which grow more and more precious 
 every year, and of which we never can havo too many." 
 
 THE ROYAL SOCIETY I THE NATURAL AND SUPERNATURAL. 
 
 The Royal Society was formed with the avowed object of 
 increasing knowledge by direct experiment ; and it is worthy 
 of remark, that the charter granted by Charles II. to this cele- 
 brated institution declares that its object is the extension of 
 natural knowledge, as opposed to that which is supernatural. 
 
 Dr. Paris (Life of Sir H. Davy, vol. ii. p. 178) says : " The 
 charter of the Royal Society states that it was established for 
 the improvement of natural science. This epithet natural was 
 originally intended to imply a meaning, of which very few 
 persons, I believe, are aware. At the period of the establish- 
 ment of the society, the arts of witchcraft and divination were 
 very extensively encouraged ; and the word natural was there- 
 fore introduced in contradistinction to supernatural." 
 
 THE PHILOSOPHER BOYLE. 
 
 After the death of Bacon, one of the most distinguished 
 Englishmen was certainly Robert Boyle, who, if compared 
 with his contemporaries, may be said to rank immediately 
 below Newton, though of course very inferior to him as an ori- 
 ginal thinker. Boyle was the first who instituted exact expe- 
 riments into the relation between colour and heat ; and by 
 this means not only ascertained some very important facts, 
 but laid a foundation for that union between optics and ther- 
 motics, which, though not yet completed, now merely waits 
 for some great philosopher to strike out a generalisation large 
 enough to cover both, and thus fuse the two sciences into a 
 single study. It is also to Boyle, more than to any other Eng- 
 lishman, that we owe the science of hydrostatics in the state 
 
Curiosities of Science. 
 
 in which we now possess it.* He is also the original discoverer 
 of that beautiful law, so fertile in valuable results, according 
 to which the elasticity of air varies as its density. And, in 
 the opinion of one of the most eminent modern naturalists, it 
 was Boyle who opened up those chemical inquiries which went 
 on accumulating until, a century later, they supplied the 
 means by which Lavoisier and his contemporaries fixed the 
 real basis of chemistry, and enabled it for the first time to 
 take its proper stand among those sciences that deal with the 
 external world. Buckle's History of Civilization, vol. i. 
 
 SIR ISAAC NEWTON'S ROOMS AND LABORATORY IN TRINITY 
 COLLEGE, CAMBRIDGE. 
 
 Of the rooms occupied by Newton during his early resi- 
 dence at Cambridge, it is now difficult to settle the locality. 
 The chamber allotted to him as Fellow, in 1667, was " the 
 Spiritual Chamber," conjectured to have been the ground- 
 room, next the chapel, but it is not certain that he resided 
 there. The rooms in which he lived from 1682 till he left 
 Cambridge, are in the north-east corner of the great court, 
 on the first floor, on the right or north of the gateway or 
 
 Principal entrance to the college. His laboratory, as Dr. 
 lumphrey Newton tell us, was " on the left end of the garden, 
 near the east end of the chapel ; and his telescope (refracting) 
 was five feet long, and placed at the head of the stairs, going 
 down into the garden. "f The east side of Newton's rooms has 
 been altered within the last fifty years : Professor Sedgwick, 
 who came up to college in 1804, recollects a wooden room, 
 supported on an arcade, shown in Loggan's view, in place of 
 which arcade is now a wooden wall and brick chimney. 
 
 Dr. Humphrey Newton relates that in college Sir Isaac very rarely 
 went to bed till two or three o'clock in the morning', sometimes not till 
 five or six, especially at spring and fall of the leaf, when he used to 
 employ about six weeks in his laboratory, the fire scarcely going out 
 either night or day ; he sitting up one night, and Humphrey another, 
 till he had finished his chemical experiments. Dr. Newton describes 
 the laboratory as " well furnished with chymical materials, as bodyes, 
 receivers, heads, crucibles, &c., which was made very little use of, ye 
 crucibles excepted, in which he fused his metals : he would some- 
 times, though very seldom, look into an old mouldy book, which lay in 
 his laboratory ; I think it was titled Agricola de Metallis, the trans- 
 muting of metals being his chief design, for which purpose antimony 
 
 * Dr Whewell (Bridgewater Treatise, p. 266) well observes, that Boyle and 
 Pascal are to hydrbstatics what Galileo is to mechanics, and Copernicus, Kepler, 
 and Newton are to astronomy. 
 
 t The Kev. Mr. Tumor recollects that Mr Jones, the tutor, mentioned, in one 
 of his lectures on optics, that the reflecting telescope belonging to Newton was 
 then lodged in the observatory over the gateway; and Mr. Turner thinks that 
 he once saw it, with a finder affixed to it. 
 
Things not generally Known. 
 
 was a great ingredient." " His brick furnaces, pro re nata, he made 
 and altered himself without troubling a bricklayer." " What obser- 
 vations he might make with his telescope, I know not, but several of 
 his observations about comets and the planets may be found scattered 
 here and there in a book intitled The Elements of Astronomy, by Dr. 
 David Gregory."* 
 
 NEWTON'S " APPLE-TREE." 
 
 Curious and manifold as are the trees associated with the 
 great names of their planters, or those who have sojourned in 
 their shade, the Tree which, by the falling of its fruit, sug- 
 gested to Newton the idea of Gravity, is of paramount interest. 
 It appears that, in the autumn of 1665, Newton left his college 
 at Cambridge for his paternal home at Woolsthorpe. " When 
 sitting alone in the garden," says Sir David Brewster, "and 
 speculating on the power of gravity, it occurred to him, that as 
 the same power by which the apple fell to the ground was not 
 sensibly diminished at the greatest distance from the centre of 
 the earth to which we can reach, neither at the summits of 
 the loftiest spires, nor on the tops of the highest mountains, 
 it might extend to the moon and retain her in her orbit, in 
 the same manner as it bends into a curve a stone or a cannon- 
 ball when projected in a straight line from the surface of the 
 earth." Life of Newton, vol. i. p. 26. Sir David Brewster 
 notes, that neither Pemberton nor Whiston, who received from 
 Newton himself his first ideas of gravity, records this story of 
 the falling apple. It was mentioned, however, to Voltaire by 
 Catherine Barton, Newton's niece ; and to Mr. Green by Mar- 
 tin Folkes, President of the Royal Society. Sir David Brewster 
 saw the reputed apple-tree in 1814, and brought away a portion 
 of one of its roots. The tree was so much decayed that it was 
 cut down in 1820, and the wood of it carefully preserved by 
 Mr. Tumor, of Stoke Rocheford. 
 
 * The story of the dog " Diamond" having caused the burning of certain 
 papers is laid in London, and in Newton's later years. In the notes to Maude's 
 ~W enUysdal?. a person then living (1780) relates, that Sir Isaac being called out 
 of bis study to a contiguous room, a little dog, called Diamond, the constant 
 but incurious attendant of his master's researches, happened to be left among 
 the papers, and by a fatality not to be retrieved, as it was in the latter part of 
 Sir Isaac's days, threw down a lighted candle, which consumed the almost 
 finished labour of some years. Sir Isaac returning too late but to behold the 
 dreadful wreck, rebuked the author of it with an exclamation (ad sidern p/ilmas), 
 " O Diamond ! Diamond ! thou little knowest the mischief done!" without adding 
 a single stripe. M. Biot gives this fiction as a true story, which happened 
 Borne years after the publication of the Prii.cipin; and he characterises the acci- 
 dent as having deprived the sciences forever of the fruit of so much of Newton's 
 labours. Brewster's Life. vol. ii. p. 1P9, note. Dr. Newton remarks, that Sir 
 Isaac never had any communion with dogs or cats; and Sir David Brewster 
 adds, that the view which M. Biot has taken of the idle story of the dog Dia- 
 mond, charged with fire-raising among Newton's manuscripts, and of the influ- 
 ence of this accident upon the mind of their author, is utterly incomprehensible. 
 The fiction, however, was turned to account in giving colour to M. Biot'b misre- 
 presentation. 
 
Curiosities of Science. 
 
 De Morgan (in Notes and Queries, 2d series, No. 139, p. 169) ques- 
 tions'whether the fruit was an apple, and maintains that the anecdote 
 rests upon very slight authority ; more especially as the idea had for 
 many ye irs been floating before the minds of physical inquirers ; al- 
 though Newton cleared away the confusions and difficulties which pre- 
 vented very able men from proceeding beyond conjecture, and by this 
 means established universal gravitation. 
 
 NEWTON'S " PKINCIPIA." 
 
 " It may be justly said," observes Halley, " that so many 
 and so valuable philosophical truths as are herein discovered 
 and put past dispute were never yet owing to the capacity and 
 industry of any one man." " The importance and generality 
 of the discoveries," says Laplace, "and the immense number 
 of original and profound views, which have been the germ of 
 the most brilliant theories of the philosophers of this (18th) 
 century, and all presented with much elegance, will ensure to 
 the work on the Mathematical Principles of Natural Philosophy 
 a preeminence above all the other productions of human 
 genius." 
 
 DESCAKTES' LABOURS IN PHYSICS. 
 
 The most profound among the many eminent thinkers 
 France has produced, is Rene Descartes, of whom the least 
 that can be said is, that he effected a revolution more decisive 
 than has ever been brought about by any other single mind; 
 that he was the first who successfully applied algebra to geo- 
 metry; that he pointed out the important law of the sines; 
 that in an age in which optical instruments were extremely 
 imperfect, he discovered the changes to which light is sub- 
 jected in the eye by the crystalline lens ; that he directed at- 
 tention to the consequences resulting from the weight of the 
 atmosphere ; and that he moreover detected the causes of the 
 rainbow. At the same time, and as if to combine the most 
 varied forms of excellence, he is not only allowed to be the first 
 geometrician of the age, but by the clearness and admirable 
 precision of his style, he became one of the founders of French 
 prose. And, although he was constantly engaged in those lofty 
 inquiries into the nature of the human mind, which can never 
 be studied without wonder, he combined with them a long 
 course of laborious experiment upon the animal frame, which 
 raised him to the highest rank among the anatomists of his 
 time. The great discovery made by Harvey of the Circulation 
 of the Blood was neglected by most of his contemporaries ; but 
 it was at once recognised by Descartes, who made it the basis 
 of the physiological part of his work on man. He was likewise 
 the discoverer of the lacteals by Aselli, which, like every great 
 
10 Things not generally Known. 
 
 truth yet laid before the world, was at its first appearance, not 
 only disbelieved, but covered with ridicule. Buckles History 
 of Civilization, vol. i. 
 
 CONIC SECTIONS. 
 
 If a cone or sugar-loaf be cut through in certain directions, 
 we shall obtain figures which are termed conic sections : thus, 
 if we cut through a sugar-loaf parallel to its base or bottom, 
 the outline or edge of the loaf where it is cut will be a circle. 
 If the cut is made so as to slant, and not be parallel to the base 
 of the loaf, the outline is an ellipse, provided the cut goes quite 
 through the sides of the loaf all round ; but if it goes slanting, 
 and parallel to the line of the loaf's side, the outline is a para- 
 bola, a conic section or curve, which is distinguished by charac- 
 teristic properties, every point of it bearing a certain fixed rela- 
 tion to a certain point within it, as the circle does to its centre. 
 Dr. Paris' s Notes to Philosophy in Sport, <c. 
 
 POWEE OF COMPUTATION. 
 
 The higher class of mathematicians, at the end of the seven- 
 teenth century, had become excellent computers, particularly 
 in England, of which Wallis, Newton, Halley, the Gregorys, and 
 De Moivre, are splendid examples. Before results of extreme 
 exactness had become quite familiar, there was a gratifying 
 sense of power in bringing out the new methods. Newton, in 
 one of his letters to Oldenburg, says that he was at one time too 
 much attached to such things, and that he should be ashamed 
 to say to what number of figures he was in the habit of carrying 
 his results. The growth of power of computation on the Conti- 
 nent did not, however, keep pace with that of the same in Eng- 
 land. In 1696, De Laguy, a well-known writer on algebra, and 
 a member of the Academy of Sciences, said that the most skil- 
 ful computer could not, in less than a month, find within a unit 
 the cube root of 696536483318640035073641037. De Morgan. 
 
 " THE SCIENCE OF THE COSMOS." 
 
 Humboldt characterises this " uncommon but definite ex- 
 pression" as the treating of " the assemblage of all things with 
 which space is filled, from the remotest nebulas to the climatic 
 distribution of those delicate tissues of vegetable matter which 
 spread a variegated covering over the surface of our rocks." 
 The word cosmos, which primitively, in the Homeric ages, 
 indicated an idea of order and harmony, was subsequently 
 adopted in scientific language, where it was gradually applied 
 to the order observed in the movements of the heavenly bodies ; 
 to the whole universe ; and then finally to the world in which 
 this harmony was reflected to us. 
 
Curiosities of Science. 1 1 
 
 ALL THE WOELD IN MOTION. 
 
 HUMBOLDT, in his Cosmos* gives the following beautiful illus- 
 trative proofs of this phenomenon : 
 
 If, for a moment, we imagine the acuteness of our senses preterna- 
 turally heightened to the extreme limits of telescopic vision, and bring 
 together events separated by wide intervals of time, the apparent re- 
 pose which reigns in space will suddenly vanish ; countless stars will be 
 seen moving in groups in various directions ; nebulae wandering, con- 
 densing, and dissolving like cosmical clouds ; the milky way breaking 
 up in parts, and its veil rent asunder. In every point of the celestial 
 vault we shall recognise the dominion of progressive movement, as on 
 the surface of the earth where vegetation is constantly putting forth its 
 leaves and buds, and unfolding its blossoms. The celebrated Spanish 
 botanist, Cavanilles, first conceived the possibility of " seeing grass 
 grow," by placing the horizontal micrometer wire of a telescope, with a 
 high magnifying power, at one time on the point of a bamboo shoot, and 
 at another on the rapidly unfolding flowering stem of an American aloe ; 
 preciselv as the astronomer places the cross of wires on a culminating 
 star. Throughout the whole life of physical nature in the organic as 
 in the sidereal world existence, preservation, production, and develop- 
 ment, are alike associated with motion as their essential condition. 
 
 THE AXIS OF ROTATION. 
 
 It is remarkable as a mechanical fact, that nothing is so per- 
 manent in nature as the Axis of Rotation of any thing which is 
 rapidly whirled. We have examples of this in every-day prac- 
 tice. The first is the motion of a boy's hoop. What keeps the 
 hoop from falling ? It is its rotation, which is one of the most 
 complicated subjects in mechanics. 
 
 Another thing pertinent to this question is, the motion of a 
 quoit. Every body who ever threw a quoit knows that to make 
 it preserve its position as it goes through the air, it is necessary 
 to give it a whirling motion. It will be seen that while whirl- 
 ing, it preserves its plane, whatever the position of the plane 
 may be, and however it may be inclined to the direction in 
 which the quoit travels. Now, this has greater analogy with 
 the motion of the earth than any thing else. 
 
 Another illustration is the motion of a spinning top. The 
 greatest mathematician of the last century, the celebrated 
 Euler, has written a whole book on the motion of a top, and 
 his Latin treatise De motu Turbinis is one of the most remark- 
 able books on mechanics. The motion of a top is a matter of 
 
 * Bolm's edition. 
 
12 Things not generally Known. 
 
 the greatest importance ; it is applicable to the elucidation of 
 some of the greatest phenomena of nature. In all these in- 
 stances there is this wonderful tendency in rotation to preserve 
 the axis of rotation unaltered. Prof. Airy's Lect. on Astronomy. 
 
 THE EARTH'S ANNUAL MOTION. 
 
 In conformity with the Copernican view of our system, we 
 must learn to look upon the sun as the comparatively motion- 
 less centre about which the earth performs an annual elliptic 
 orbit of the dimensions and exeentricity, and with a velocity, 
 regulated according to a certain assigned law ; the sun occupy- 
 ing one of the foci of the ellipse, and from that station quietly 
 disseminating on all sides its light and heat ; while the earth 
 travelling round it, and presenting itself differently to it at dif- 
 ferent times of the year and day, passes through the varieties of 
 day and night, summer and winter, which we enjoy. Sir John 
 HerscheVs Outlines of Astronomy. 
 
 Laplace has shown that the length of the day has not varied 
 the hundredth part of a second since the observations of Hippar- 
 chus, 2000 years ago. 
 
 STABILITY OF THE OCEAN. 
 
 In submitting this question to analysis, Laplace found that 
 the equilibrium of the ocean is stable if its density is less than the 
 mean density of the earth, and that its equilibrium cannot be sub- 
 verted unless these two densities are equal, or that of the earth 
 less than that of its waters. The experiments on the attraction 
 of Schehallien and Mont Cenis, and those made by Cavendish, 
 Reich, and Baily, with balls of lead, demonstrate that the mean 
 density of the earth is at least five times that of water, and hence 
 the stability of the ocean is placed beyond a doubt. As the seas, 
 therefore, have at one time covered continents which are now 
 raised above their level, we must seek for some other cause of 
 it than any want of stability in the equilibrium of the ocean. 
 How beautifully does this conclusion illustrate the language of 
 Scripture, " Hitherto shalt thou come, but no further" ! (Job 
 xxxviii. 11.) 
 
 COMPRESSION OF BODIES. 
 
 Sir John Leslie observes, that air compressed into the fiftieth 
 part of its volume has its elasticity fifty times augmented : if it 
 continued to contract at that rate, it would, from its own in- 
 cumbent weight, acquire the density of water at the depth of 
 thirty-four miles. Bat water itself would have its density 
 doubled at the depth of ninety -three miles, and would attain the 
 density of quicksilver at the depth of 362 miles. In descending, 
 therefore, towards the centre, through nearly 4000 miles, the 
 condensation of ordinary substances would surpass the utmost 
 
Curiosities of Science. 13 
 
 powers of conception. Dr. Young says, that steel would be 
 compressed into one-fourth, and stone into one-eighth, of its 
 bulk at the earth's centre. Mrs. Somerville. 
 
 THE WORLD IN A NUTSHELL. 
 
 From the many proofs of the non-contact of the atoms, even 
 in the most solid parts of bodies ; from the very great space 
 obviously occupied by pores the mass having often no more 
 solidity than a heap of empty boxes, of which the apparently 
 solid parts may still be as porous in a second degree and so on ; 
 and from the great readiness with which light passes in all direc- 
 tions through dense bodies, like glass, rock-crystal, diamond, 
 &c., it has been argued that there is so exceedingly little of 
 really solid matter even in the densest mass, that the whole 
 world, if the atoms could be brought into absolute contact, 
 might be compressed into a nutshell. We have as yet no means 
 of determining exactly what relation this idea has to truth. 
 Arnott. 
 
 THE WORLD OF ATOMS. 
 
 The infinite groups of atoms flying through all time and 
 space, in different directions and under different laws, have 
 interchangeably tried and exhibited every possible mode of ren- 
 counter : sometimes repelled from each other by concussion ; 
 and sometimes adhering to each other from their own jagged 
 or pointed construction, or from the casual interstices which 
 two or more connected atoms must produce, and which may be 
 just adapted to those of other figures, as globular, oval, or 
 square. Hence the origin of compound and visible bodies ; 
 hence the origin of large masses of matter ; hence, eventually, 
 the origin of the world. Dr. Good's Book of Nature. 
 
 The great Epicurus speculated on " the plastic nature " of 
 atoms, and attributed to this nature the power they possess of 
 arranging themselves into symmetric forms. Modern philoso- 
 phers satisfy themselves with attraction; and reasoning from, 
 analogy, imagine that each atom has a polar system. Hunt's 
 Poetry of Science. 
 
 MINUTE ATOMS OF THE ELEMENTS I DIVISIBILITY OF MATTER. 
 
 So minute are the parts of the elementary bodies in their 
 ultimate state of division, in which condition they are usually 
 termed atoms, as to elude all our powers of inspection, even 
 when aided by the most powerful microscopes. Who can see the 
 particles of gold in a solution of that metal in aqua regia, or 
 those of common salt when dissolved in water ? Dr. Thomas 
 Thomson has estimated the bulk of an ultimate particle or 
 atom of lead as less than ^a^saoogooooooth of a cubic inch, 
 
14 Things not generally Known. 
 
 and concludes that its weight cannot exceed the 
 of a grain. 
 
 This curious calculation was made by Dr. Thomson, in order 
 to show to what degree Matter could be divided, and still 
 be sensible to the eye. He dissolved a grain of nitrate of lead 
 in 500,000 grains of water, and passed through the solution 
 a current of sulphuretted hydrogen ; when the whole liquid 
 became sensibly discoloured. Now, a grain of water may 
 be regarded as being almost equal to a drop of that liquid, 
 and a drop may be easily spread out so as to cover a square 
 inch of surface. But under an ordinary microscope the mil- 
 lionth of a square inch may be distinguished by the eye. The 
 water, therefore, could be divided into 500,000,000,000 parts. 
 But the lead in a grain of nitrate of lead weighs 0*62 of a 
 grain ; an atom of lead, accordingly, cannot weigh more than 
 sioooooooooo th of a grain ; while the atom of sulphur, 
 which in combination with the lead rendered it visible, could 
 not weigh more than ^orgooooooooo? that is, the two-billionth 
 part of a grain. Professor Low ; Jameson's Journal, No. 106. 
 
 WEIGHT OF AIE. 
 
 Air can be so rarefied that the contents of a cubic foot shall 
 not weigh the tenth part of a grain : if a quantity that would 
 fill a space the hundredth part of an inch in diameter be sepa- 
 rated from the rest, the air will still be found there, and we 
 may reasonably conceive that there may be several particles 
 
 resent, though the weight is less than the seventeen-hun- 
 red-millionth of a grain. 
 
 DURATION OF THE PYRAMID. 
 
 The great reason of the duration of the pyramid above all 
 other forms is, that it is most fitted to resist the force of gra- 
 vitation. Thus the Pyramids of Egypt are the oldest monu- 
 ments in the world. 
 
 INERTIA ILLUSTRATED. 
 
 Many things of common occurrence (says Professor Tyndall) 
 are to be explained by reference to the quality of inactivity. 
 We will here state a few of them. 
 
 When a railway train is moving, if it strike against any ob- 
 stacle which arrests its motion, the passengers are thrown 
 forward in the direction in which the train was proceeding. 
 Such accidents often occur on a small scale, in attaching car- 
 riages at railway stations. The reasofi is, that the passengers 
 share the motion of the train, and, as matter, they tend to 
 persist in motion. When the train is suddenly checked, this 
 tendency exhibits itself by the falling forward referred to. In 
 
Curiosities of Science. 15 
 
 like manner, when a train previously at rest is suddenly set in 
 motion, the tendency of the passengers to remain at rest evinces 
 itself by their falling in a direction opposed to that in which 
 the train moves. 
 
 THE LEANING TOWER OF PISA.* 
 
 Sir John Leslie used to attribute the stability of this tower 
 to the cohesion of the mortar it is built with being sufficient to 
 maintain it erect, in spite of its being out of the condition re- 
 quired by physics to wit, that " in order that a column shall 
 stand, a perpendicular let fall from the centre of gravity must 
 fall within the base." Sir John describes the Tower of Pisa to 
 be in violation of this principle ; but, according to later au- 
 thorities, the perpendicular falls within the base. 
 
 EARLY PRESENTIMENTS OF CENTRIFUGAL FORCES. 
 
 Jacobi, in his researches on the mathematical knowledge of 
 the Greeks, comments on " the profound consideration of nature 
 evinced by Anaxagoras, in whom we read with astonishment a 
 passage asserting that the moon, if the centrifugal force were 
 intermitted, would fall to the earth like a stone from a sling." 
 Anaxagoras likewise applied the same theory of " falling where 
 the force of rotation had been intermitted" to all the mate- 
 rial celestial bodies. In Aristotle and Simplicius may also be 
 traced the idea of " the non-falling of heavenly bodies when 
 the rotatory force predominates over the actual falling force, 
 or downward attraction ;" and Simplicius mentions that " wa- 
 ter in a phial is not spilt when the movement of rotation is 
 more rapid than the downward movement of the water." This 
 is illustrated at the present day by rapidly whirling a pail half- 
 filled with water without spilling a drop. 
 
 Plato had a clearer idea than Aristotle of the attractive force 
 exercised by the earth's centre on all heavy bodies removed 
 from it ; for he was acquainted with the acceleration of falling 
 
 * When at Pisa, many years since, Captain Basil Hall investigated the 
 origin and divergence of the tower from the perpendicular, and established 
 completely to his own satisfaction that it had been built from top to bottom 
 originally just as it now stands. His reasons for thinking so were, that the line 
 of the tower, on that side towards which it leans, has not the same curvature as 
 the line on the opposite, or what may be called the upper side. If the tower 
 had been built upright, and then been made to incline over, the line of the wall 
 on that side towards which the inclination was given would be more or less 
 concave in that direction, owing to the nodding or "swagging over" of the top, 
 by the simple action of gravity acting on a very tall mass of masonry, which is 
 more or less elastic when placed in a sloping position. But the contrary is the 
 fact; for the line of wall on the side towards which the tower leans is decidedly 
 more convex than the opposite side. Captain Hall had therefore no doubt 
 whatever that the architect, in rearing his successive courses of stones, gained 
 or stole a little at each layer, so as to render his work less and less overhanging 
 as he went up; and thus, without betraying what he was about, really gained 
 stability. See Patchwork, 
 
16 Things not generally Known. 
 
 bodies, although he did not correctly understand the cause. 
 John Philoponus, the Alexandrian, probably in the sixth cen- 
 tury, was the first who ascribed the movement of the heavenly 
 bodies to a primitive impulse, connecting with this idea that 
 of the fall of bodies, or the tendency of all substances, whether 
 heavy or light, to reach the ground. The idea conceived by 
 Copernicus, and more clearly expressed by Kepler, who even 
 applied it to the ebb and flow of the ocean, received in 1666 
 and 1674 a new impulse from Robert Hooke ; and next New- 
 ton's theory of gravitation presented the grand means of con- 
 verting the whole of physical astronomy into a true mechanism 
 of the heavens. 
 
 The law of gravitation knows no exception ; it accounts ac- 
 curately for the most complex motions of the members of our 
 own system ; nay more, the paths of double stars, far removed 
 from all appreciable effects of our portion of the universe, are 
 in perfect accordance with its theory. * 
 
 HEIGHT OF FALLS. 
 
 The fancy of the Greeks delighted itself in wild visions of the 
 height of falls. In Hesiod's Theogony it is said, speaking of the 
 fall of the Titans into Tartarus, " if a brazen anvil were to fall 
 from heaven nine days and nine nights long, it would reach 
 the earth on the tenth." This descent of the anvil in 777,600 
 seconds of time gives an equivalent in distance of 309,424 geo- 
 graphical miles (allowance being made, according to Galle's 
 calculation, for the considerable diminution in force of attrac- 
 tion at planetary distances) ; therefore 1 times the distance 
 of the moon from the earth. But, according to the Iliad, He- 
 phaestus fell down to Lemnos in one day ; " when but a little 
 breath was still in him." Note to Humboldt's Cosmos, vol. iii. 
 
 KATE OF THE FALL OF BODIES. 
 
 A body falls in gravity precisely 1 6 T ^ feet in a second, and 
 the velocity increases according to the squares of the time, viz. : 
 
 In i (quarter of a second) a body falls . . 1 foot. 
 i (half a second) 4 feet. 
 
 1 second . . . . . . . 16 ,, 
 
 2 ditto 64 
 
 3 ditto 144 
 
 * Lord Bacon proposed that, in order to determine whether the gravity of the 
 earth arises from the gravity of its parts, a clock-pendulum should be swung in 
 a mine, as was recently done at Harton colliery by the Astronomer Royal. 
 
 When, in 1812, Ampere noted the phenomena of the pendulum, and showed 
 that its movement was produced only when the eye of the observer was fixed 
 on the instrument, and endeavoured to prove thereby that the motion was due to 
 a play of the muscles, some members of the French Academy objected to the 
 consideration of a subject connected to such an extent with superstition. 
 
Curiosities of Science. 1 7 
 
 The power of gravity at two miles distance from the earth is 
 four times less than at one mile ; at three miles nine times 
 less, and so on. It goes on lessening, but is never destroyed. 
 Notes in various Sciences. 
 
 VARIETIES OF SPEED. 
 
 A French scientific work states the ordinary rate to be : 
 
 per second. 
 
 Of a man walking 4 feet. 
 
 Of a good horse in harness 12 
 
 Of a rein- deer in a sledge on the ice . . . 26 
 Of an English race-horse . . 43 
 
 Of a hare 88 
 
 Of a good sailing ship 19 
 
 Of the wind 82 
 
 Of sound 1038 
 
 Of a 24-pounder cannon-ball .... 1300 
 
 LIFTING HEAVY PERSONS. 
 
 One of the most extraordinary pages in Sir David Brewster's 
 Letters on Natural Magic is the experiment in which a heavy 
 man is raised with the greatest facility when he is lifted up the 
 instant that his own lungs, and those of the persons who raise 
 him, are inflated with air. Thus the heaviest person in the 
 party lies down upon two chairs, his legs being supported by 
 the one and his back by the other. Four persons, one at each 
 leg, and one at each shoulder, then try to raise him the per- 
 son to be raised giving two signals, by clapping his hands. At 
 the first signal, he himself and the four lifters begin to draw a 
 long and full breath ; and when the inhalation is completed, or 
 the lungs filled, the second signal is given for raising the per- 
 son from the chair. To his own surprise, and that of his bearers, 
 he rises with the greatest facility, as if he were no heavier than 
 a feather. Sir David Brewster states that he has seen this 
 inexplicable experiment performed more than once; and he 
 appealed for testimony to Sir Walter Scott, who had repeatedly 
 seen the experiment, and performed the part both of the load 
 and of the bearer. It was first shown in England by Major H., 
 who saw it performed in a large party at Venice, under the di- 
 rection of an officer of the American navy.* 
 
 Sir David Brewster (in a letter to Notes and Queries, No. 143) 
 further remarks, that " the inhalation of the lifters the moment 
 the effort is made is doubtless essential, and for this reason : 
 when we make a great effort, either in pulling or lifting, we 
 always fill the chest with air previous to the effort ; and when 
 
 * This curious fact was first recorded by Pepys, in his Diary, under the date 
 31st of July 1665. 
 
 
 
18 Things not generally Known. 
 
 the inhalation is completed, we close the rima glottidis to keep 
 the air in the lungs. The chest being thus kept expanded, the 
 pulling or lifting muscles have received as it were a fulcrum 
 round which their power is exerted ; and we can thus lift the 
 greatest weight which the muscles are capable of doing. When 
 the chest collapses by the escape of the air, the lifters lose their 
 muscular power; reinhalation of air by the liftee can certainly 
 add nothing to the power of the lifters, or diminish his own 
 weight, which is only increased by the weight of the air which 
 he inhales." 
 
 " FORCE CAN NEITHER BE CREATED NOR DESTROYED." 
 
 Professor Faraday, in his able inquiry upon " the Conserva- 
 tion of Force," maintains that to admit that force may be de- 
 structible, or can altogether disappear, would be to admit that 
 matter could be uncreated; for we know matter only by its 
 forces. From his many illustrations we select the following : 
 
 The indestructibility of individual matter is a most important case of 
 the Conservation of Chemical Force. A molecule has been endowed with 
 powers which give rise in it to various qualities ; and those never change, 
 either in their nature or amount. A particle of oxygen is ever a particle 
 of oxygen ; nothing can in the least wear it. If it enters into combina- 
 tion, and disappears as oxygen ; if it pass through a thousand combina- 
 tions animal, vegetable, mineral ; if it lie hid for a thousand years, and 
 then be evolved, it is oxygen with the first qualities, neither more nor 
 less. It has all its original force, and only that ; the amount of force 
 which it disengaged when hiding itself, has again to be employed in a 
 reverse direction when it is set at liberty : and if, hereafter, we should 
 decompose oxygen, and find it compounded of other particles, we should 
 only increase the strength of the proof of the conservation of force ; for 
 we should have a right to say of these particles, long as they have been 
 hidden, all that we could say of the oxygen itself. 
 
 In conclusion, he adds : 
 
 Let us not admit the destruction or creation of force without clear 
 and constant proof. Just as the chemist owes all the perfection of his 
 science to his dependence on the certainty of gravitation applied by the 
 balance, so may the physical philosopher expect to find the greatest 
 security and the utmost aid in the principle of the conservation of force. 
 All that we have that is good and safe as the steam-engine, the electric 
 telegraph, &c. witness to that principle ; it would require a perpetual 
 motion, a fire without heat, heat without a source, action without re- 
 action, cause without effect, or effect without cause, to displace it from 
 its rank as a law of nature. 
 
 NOTHING LOST IN THE MATERIAL WORLD. 
 
 "It is remarkable, 1 ' says Kobell in his Mineral Kingdom, 
 " how a change of place, a circulation as it were, is appointed 
 for the inanimate or naturally immovable things upon the earth ; 
 and how new conditions, new creations, are continually deve- 
 loping themselves in this way. I will not enter here into the 
 
Curiosities of Science. 19 
 
 evaporation of water, for instance from the widely-spreading 
 ocean ; how the clouds produced by this pass over into foreign 
 lands and then fall again to the earth as rain, and how this 
 wandering water is, partly at least, carried along new journeys, 
 returning after various voyages to its original home : the mere 
 mechanical phenomena, such as the transfer of seeds by the 
 winds or by birds, or the decomposition of the surface of the 
 earth by the friction of the elements, suffice to illustrate this." 
 
 TIME AN ELEMENT OF FOKCE. 
 
 Professor Faraday observes that Time is growing up daily 
 into importance as an element in the exercise of Force, which 
 he thus strikingly illustrates : 
 
 The earth moves in its orbit of time ; the crust of the earth moves in 
 time ; light moves in time ; an electro-magnet requires time for its charge 
 by an electric current : to inquire, therefore, whether power, acting either 
 at sensible or insensible distances, always acts in time, is not to be me- 
 taphysical ; if it acts in time and across space, it must act by physical 
 lines of force ; and our view of the nature of force may be affected to 
 the extremest degree by the conclusions which experiment and obser- 
 vation on time may supply, being perhaps finally determinate only by 
 them. To inquire after the possible time in which gravitating, magnetic, 
 or electric force is exerted, is no more metaphysical than to mark the 
 times of the hands of a clock in their progress ; or that of the temple of 
 Serapis, and its ascents and descents ; or the periods of the occultation 
 of Jupiter's satellites; or that in which the light comes from them to 
 the earth. Again, in some of the known cases of the action of time 
 something happens while the time is passing which did not happen be- 
 fore, and does not continue after ; it is therefore not metaphysical to 
 expect an effect in every case, or to endeavour to discover its existence 
 and determine its nature. 
 
 CALCULATION OF HEIGHTS AND DISTANCES. 
 
 By the assistance of a seconds watch the following inter- 
 esting calculations may be made : 
 
 If a traveller, when on a precipice or on the top of a building, wish 
 to ascertain the height, he should drop a stone, or any other substance 
 sufficiently heavy not to be impeded by the resistance of the atmosphere ; 
 and the number of seconds which elapse before it reaches the bottom, 
 carefully noted on a seconds watch, will give the height. For the stone 
 will fall through the space of 16J feet during the first second, and will 
 increase in rapidity as the square of the time employed in the fall : if, 
 therefore, 16j be multiplied by the number of seconds the stone has 
 taken to fall, this product also multiplied by the same number of seconds 
 will give the height. Suppose the stone takes five seconds to reach the 
 bottom : 
 
 16^ x 5=80| x 5=403&, height of the precipice. 
 
 The Count Xavier de Maistre, in his Expedition nocturne autoiir de 
 ma Ckambre, anxious to ascertain the exact height of his room from the 
 ground on which Turin is built, tells us he proceeded as follows : " My 
 heart beat quickly, and I just counted three pulsations from the instant 
 
20 Things not generally Known. 
 
 1 dropped my slipper until I heard the sound as it fell in the street, 
 which, according to the calculations made of the time taken by bodies 
 in their accelerated fall, and of that employed by the sonorous undula- 
 tions of the air to arrive from the street to my ear, gave the height of 
 my apartment as 94 feet 3 inches 1 tenth (French measure), supposing 
 that my heart, agitated as it was, beat 120 times in a minute." 
 
 A person travelling may ascertain his rate of walking by the aid of a 
 slight string with a piece of lead at one end, and the use of a seconds 
 watch ; the string being knotted at distances of 44 feet, the 120th part 
 of an English mile, and bearing the same proportion to a mile that half 
 a minute bears to an hour. If the traveller, when going at his usual 
 rate, drops the lead, and suffers the string to slip through his hand, the 
 number of knots which pass in half a minute indicate the number of 
 miles he walks in an hour. This contrivance is similar to a log-line for 
 ascertaining a ship's rate at sea : the lead is enclosed in wood (whence 
 the name log), that it may float, and the divisions, which are called 
 knots, are measured for nautical miles. Thus, if ten knots are passed in 
 half a minute, they show that the vessel is sailing at the rate often knots, 
 or miles, an hour : a seconds watch would here be of great service, but 
 the half-minute sand-glass is in general use. 
 
 The rapidity of a river may be ascertained by thro wing- in a light 
 floating substance, which, if not agitated by the wind, will move with 
 the same celerity as the water : the distance it floats in a certain number 
 of seconds will give the rapidity of the stream ; and this indicates the 
 height of its source, the nature of its bottom, &c. See Sir Howard 
 Douglas on Bridges. Thomson's Time and Time-keepers. 
 
 SAND IN THE HOUE-GLASS. 
 
 It is a noteworthy fact, that the flow of Sand in the Hour- 
 glass is perfectly equable, whatever may be the quantity in the 
 glass ; that is, the sand runs no faster when the upper half of 
 the glass is quite full than when it is nearly empty. It would, 
 however, be natural enough to conclude, that when full of sand 
 it would be more swiftly urged through the aperture than when 
 the glass was only a quarter full, and near the close of the hour. 
 
 The fact of the even flow of sand may be proved by a very 
 simple experiment. Provide some silver sand, dry it over or 
 before the fire, and pass it through a tolerably fine sieve. Then 
 take a tube, of any length or diameter, closed at one end, in 
 which make a small hole, say the eighth of an inch ; stop this 
 with a peg, and fill up the tube with the sifted sand. Hold the 
 tube steadily, or fix it to a wall or frame at any height from a 
 table ; remove the peg, and permit the sand to flow in any mea- 
 sure for any given time, and note the quantity. Then let the 
 tube be emptied, and only half or a quarter filled with sand ; 
 measure again for a like time, and the same quantity of sand 
 will flow : even if you press the sand in the tube with a ruler 
 or stick, the flow of the sand through the hole will not be in- 
 creased. 
 
 The above is explained by the fact, that when the sand is 
 poured into the tube, it fills it with a succession of conical 
 
Curiosities of Science. 
 
 heaps ; and that all the weight which the bottom of the tube 
 sustains is only that of the heap which first falls upon it, as 
 the succeeding heaps do not press downward, but only against 
 the sides or walls of the tube. 
 
 FIGURE OF THE EARTH. 
 
 By means of a purely astronomical determination, based 
 upon the action which the earth exerts on the motion of the 
 moon, or, in other words, on the inequalities in lunar longi- 
 tudes and latitudes, Laplace has shown in one single result the 
 mean Figure of the Earth. 
 
 It is very remarkable that an astronomer, without leaving his obser- 
 vatory, may, merely by comparing his observations with mean analytical 
 results, not only be enabled to determine with exactness the size and 
 degree of ellipticity of the earth, but also its distance from the sun and 
 moon ; results that otherwise could only be arrived at by long and ar- 
 duous expeditions to the most remote parts of both hemispheres. The 
 moon may therefore, by the observation of its movements, render ap- 
 preciable to the higher departments of astronomy the ellipticity of the 
 earth, as it taught the early astronomers the rotundity of our earth by 
 means of its eclipses. Laplace's Expos, du Syst. du Monde. 
 
 HOW TO ASCERTAIN THE EARTH'S MAGNITUDE. 
 
 Sir John Herschel gives the following means of approxima- 
 tion. It appears by observation that two points, each ten feet 
 above the surface, cease to be visible from each other over still 
 water, and, in average atmospheric circumstances, at a distance 
 of about eight miles. But 10 feet is the 528th part of a mile ; 
 so that half their distance, or four miles, is to the height of 
 each as 4 x 528, or 2112:1, and therefore in the same propor- 
 tion to four miles is the length of the earth's diameter. It 
 must, therefore, be equal to 4x2112=8448, or in round num- 
 bers, about 8000 miles, which is not very far from the truth. 
 
 The excess is, however, about 100 miles, or s^th part. As convenient 
 numbers to remember, the reader may bear in mind, that in our latitude 
 there are just as many thousands of feet in a degree of the meridian as 
 there are days in the j^ear (365) ; that, speaking loosely, a degree is 
 about seventy British statute miles, and a second about 100 feet ; that 
 the equatorial circumference of the earth is a little less than 25,000 
 miles (24,899), and the ellipticity or polar flattening amounts to ^th 
 part of the diameter. Outlines of Astronomy. 
 
 MASS AND DENSITY OF THE EARTH. 
 
 With regard to the determination of the Mass and Density 
 of the Earth by direct experiment, we have, in addition to the 
 deviations of the pendulum produced by mountain masses, the 
 variation of the same instruments when placed in a mine 1200 
 feet in depth. The most recent experiments were conducted 
 
Things not generally Known. 
 
 by Professor Airy, in the Harton coal-pit, near South Shields :* 
 the oscillations of the pendulum at the bottom of the pit were 
 compared with those of a clock above ; the beats of the clock 
 were transferred below for comparison by an electric wire ; and 
 it was thus determined that a pendulum vibrating seconds at the 
 mouth of the pit would gain 2 seconds per day at its bottom. 
 The final result of the calculations depending on this experiment, 
 which were published in the Philosophical Transactions of 1856, 
 gives 6*565 for the mean density of the earth. The celebrated 
 Cavendish experiment, by means of which the density of the 
 earth was determined by observing the attraction of leaden 
 balls on each other, has been repeated in a manner exhibiting 
 an astonishing amount of skill and patience by the late Mr. F. 
 Baily.f The reoult of these experiments, combined with those 
 previously made, gives as a mean result 5 '441 as the earth's 
 density, when compared with water ; thus confirming one of 
 Newton's astonishing divinations, that the mean density of the 
 earth would be found to be between five and six times that of 
 water. 
 
 Humboldt is, however, of opinion that " we know only the mass of 
 the whole earth and its mean density by comparing it with the open 
 strata, which alone are accessible to us. In the interior of the earth, 
 where all knowledge of its chemical and mineralogical character fails, 
 we are limited to as pure conjecture as in the remotest bodies that 
 revolve round the sun. We can determine nothing with certainty re- 
 garding the depth at which the geological strata must be supposed to 
 be in a state of softening or of liquid fusion, of the condition of fluids 
 when heated under an enormous pressure, or of the law of the increase 
 of density from the upper surface to the centre of the earth." Cosmos, 
 vol. i. 
 
 In M. Foucault's beautiful experiment, by means of the 
 vibration of a long pendulum, consisting of a heavy mass of 
 metal suspended by a long wire from a strong fixed support, is 
 demonstrated to the eye the rotation of the earth. The Gyro- 
 scope of the same philosopher is regarded not as a mere philo- 
 sophical toy ; but the principles of dynamics, by means of 
 which it is made to demonstrate the earth's rotation on its own 
 axis, are explained with the greatest clearness. Thus the inge- 
 nuity of M. Foucault, combined with a profound knowledge of 
 mechanics, has obtained proofs of one of the most interesting 
 problems of astronomy from an unsuspected source. 
 
 THE EARTH AND MAN COMPARED. 
 
 The Earth speaking roundly is 8000 miles in diameter ; 
 
 * The result of these experiments for ascertaining the variation of the gra- 
 vity at great depths, has proved beyond doubt that the attraction of gravitation 
 is increased at the depth of 1250 fret by -^-^ part. 
 
 t See the account of Mr. Baily's researches (with two illustrations) in Things 
 not generally Known, p. vii., and " Weight of the Earth," p. 16. 
 
Curiosities of Science. 23 
 
 the atmosphere is calculated to be fifty miles in altitude ; the 
 loftiest mountain peak is estimated at five miles above the level 
 of the sea, for this height has never been visited by man ; the 
 deepest mine that he has formed is 1650 feet; and his own 
 stature does not average six feet. Therefore, if it were possible 
 for him to construct a globe 800 feet or twice the height of 
 St. Paul's Cathedral in diameter, and to place upon any one 
 point of its surface an atom of 45 ' 6(j th of an inch in diameter, 
 and ^th of an inch in height, it would correctly denote the 
 proportion that man bears to the earth upon which he moves. 
 When by measurements, in which the evidence of the method ad- 
 vances equally with the precision of the results, the volume of the earth 
 is reduced to the millionth part of the volume of the sun. ; when the sun 
 himself, transported to the region of the stars, takes up a very modest 
 place among the thousands of millions of those bodies that the telescope 
 has revealed to us ; when the 38,000,000 of leagues which poparate the 
 earth from the sun have become, by reason of their comparative small- 
 ness, a base totally insufficient for ascertaining the dimensions of the 
 visible universe ; when even the swiftness of the luminous rays (77,000 
 leagues per second) barely suffices for the common valuations of science; 
 when, in short, by a chain of irresistible proofs, certain stars have re- 
 tired to distances that light could not traverse in less than a million of 
 years ; we feel as if annihilated by such immensities. In assigning to 
 man and to the planet that he inhabits so small a position in the ma- 
 terial world, astronomy seems really to have made progress only to 
 humble us. Arago. 
 
 MEAN TEMPERATURE OF THE EARTH'S SURFACE. 
 
 Professor Dove has shown, by taking at all seasons the 
 mean of the temperature of points diametrically opposite to 
 each^ other, that the mean temperature of the whole earth's sur- 
 face in June considerably exceeds that in December. This re- 
 sult, which is at variance with the greater proximity of the 
 sun in December, is, however, due to a totally different and 
 very powerful cause, the greater amount of land in that 
 hemisphere which has its summer solstice in June (i. e. the 
 northern) ; and the fact is so explained by him. The effect of 
 land under sunshine is to throw heat into the general atmo- 
 sphere, and to distribute it by the carrying power of the latter 
 over the whole earth. Water is much less effective in this 
 respect, the heat penetrating its depths and being there ab- 
 sorbed ; so that the surface never acquires a very elevated 
 temperature, even under the equator. Sir John HerscheVs 
 Outlines. 
 
 TEMPERATURE OF THE EARTH STATIONARY. 
 
 Although, according to Bessel, 25,000 cubic miles of water 
 flow in every six hours from one quarter of the earth to another, 
 and the temperature is augmented by the ebb and flow of every 
 
Things not generally Known. 
 
 tide, all that we know with certainty is, that the resultant 
 effect of all the thermal agencies to which the earth is exposed 
 has undergone no perceptible change within the historic period. 
 We owe this fine deduction to Arago. In order that the date 
 palm should ripen its fruit, the mean temperature of the place 
 must exceed 70deg. Fahr. ; and, on the other hand, the vine 
 cannot be cultivated successfully when the temperature is 
 72 deg. or upwards. Hence the mean temperature of any 
 place at which these two plants flourished and bore fruit must 
 lie between these narrow limits, i. e. could not differ from 
 71 deg. Fahr. by more than a single degree. Now from the 
 Bible we learn that both plants were simultaneously cultivated 
 in the central valleys of Palestine in the time of Moses ; and 
 its then temperature is thus definitively determined. It is the 
 same at the present time ; so that the mean temperature of 
 this portion of the globe has not sensibly altered in the course 
 of thirty-three centuries. 
 
 THEORY OF CRYSTALLISATION. 
 
 Professor Pliicker has ascertained that certain crystals, in 
 particular the cyanite, " point very well to the north by the 
 magnetic power of the earth only. It is a true compass-needle ; 
 and more than that, you may obtain its declination." Upon 
 this Mr. Hunt remarks : " We must remember that this crystal, 
 the cyanite, is a compound of silica and alumina only. This 
 is the amount of experimental evidence which science has 
 afforded in explanation of the conditions under which nature 
 pursues her wondrous work of crystal formation. We see just 
 sufficient of the operation to be convinced that the luminous 
 star which shines in the brightness of heaven, and the cavern- 
 secreted gem, are equally the result of forces which are known 
 to us in only a few of their modifications." Poetry of Science. 
 
 Gay Lussac first made the remark, that a crystal of potash- 
 alum, transferred to a solution of ammonia-alum, continued to 
 increase without its form being modified, and might thus be 
 covered with alternate layers of the two alums, preserving its 
 regularity and proper crystalline figure. M. Beudant after- 
 wards observed that other bodies, such as the sulphates of iron 
 and copper, might present themselves in crystals of the same 
 form and angles, although the form was not a simple one, like 
 that of alum. But M. Mitscherlich first recognised this cor- 
 respondence in a sufficient number of cases to prove that it was 
 a general consequence of similarity of composition in different 
 bodies. Graham's Elements of Che, 
 
 IMMENSE CRYSTALS. 
 
 Crystals are found in the most microscopic character, and 
 
Curiosities of Science. 25 
 
 of an exceedingly large size. A crystal of quartz at Milan is 
 three feet and a quarter long, and five feet and a half in cir- 
 cumference : its weight is 870 pounds. Beryls have been found 
 in New Hampshire measuring four feet in length. Dana. 
 
 VISIBLE CRYSTALLISATION. 
 
 Professor Tyndall, in a lecture delivered by him at the Royal 
 Institution, London, on the properties of Ice, gave the following 
 interesting illustration of crystalline force. By perfectly clean- 
 ing a piece of glass, and placing on it a film of a solution of chlor- 
 ide of ammonium or sal ammoniac, the action of crystallisation 
 was shown to the whole audience. The glass slide was placed 
 in a microscope, and the electric light passing through it was 
 concentrated on a white disc. The image of the crystals, as 
 they started into existence, and shot across the disc in exqui- 
 site arborescent and symmetrical forms, excited the admira- 
 tion of every one. The lecturer explained that the heat, causing 
 the film of moisture to evaporate, brought the particles of salt 
 sufficiently near to exercise the crystalline force, the result 
 being the beautiful structure built up with such marvellous 
 rapidity. 
 
 UNION OF MINERALOGY AND GEOMETRY. 
 
 It is a peculiar characteristic of minerals, that while plants 
 and animals differ in various regions of the earth, mineral matter 
 of the same character may be discovered in any part of the world, 
 at the Equator or towards the Poles ; at the summit of the 
 loftiest mountains, and in works far beneath the level of the 
 sea. The granite of Australia does not necessarily differ from 
 that of the British islands ; and ores of the same metals (the 
 proper geological conditions prevailing) may be found of the 
 same general character in ail regions. Climate and geographi- 
 cal position have no influence on the composition of mineral 
 substances. 
 
 This uniformity may, in some measure, have induced philo- 
 sophers to seek its extension to the forms of crystallography. 
 About 1760 (says Mr, Buckle, in his History of Civilization), 
 Rome de Lisle set the first example of studying crystals, ac- 
 cording to a scheme so large as to include all the varieties of 
 their primary forms, and to account for their irregularities and 
 the apparent caprice with which they were arranged. In this 
 investigation he was guided by the fundamental assumption, 
 that what is called an irregularity is in truth perfectly regular, 
 and that the operations of nature are invariable. Haiiy ap- 
 plied this great idea to the almost innumerable forms in which 
 minerals crystallise. He thus achieved a complete union be- 
 tween mineralogy and geometry ; and, bringing the laws of space 
 
Things not generally Known. 
 
 to bear on the molecular arrangements of matter, he was able 
 to penetrate into the intimate structure of crystals. By this 
 means he proved that the secondary forms of all crystals are de- 
 rived from their primary forms by a regular process of decrement ; 
 and that when a substance is passing from a liquid to a solid 
 state, its particles cohere, according to a scheme which provides 
 for every possible change, since it includes even those subse- 
 quent layers which alter the ordinary type of the crystal, by 
 disturbing its natural symmetry. To ascertain that such viola- 
 tions of symmetry are susceptible of mathematical calculation, 
 was to make a vast addition to our knowledge ; and, by proving 
 that even the most uncouth and singular forms are the natural 
 results of their antecedents, Haiiy laid the foundation of what 
 may be called the pathology of the inorganic world. However 
 paradoxical such a notion may appear, it is certain that sym- 
 metry is to crystals what health is to animals ; so that an irre- 
 gularity of shape in the first corresponds with an appearance of 
 disease in the second. See Hist. Civilization, vol.i. 
 
 REPRODUCTIVE CRYSTALLISATION. 
 
 The general belief that only organic beings have the power 
 of reproducing lost parts has been disproved by the experiments 
 of Jordan on crystals. An octohedral crystal of alum was frac- 
 tured ; it was then replaced in a solution, and after a few days 
 its injury was seen to be repaired. The whole crystal had of 
 course increased in size ; but the increase on the broken surface 
 had been so much greater that a perfect octohedral form was 
 regained. G. H. Lewes. 
 
 Tnis remarkable power possessed by crystals, in common 
 with animals, of repairing their own injuries had, however, 
 been thus previously referred to by Paget, in his Pathology, 
 confirming the experiments of Jordan on this curious subject: 
 " The ability to repair the damages sustained by injury . . . 
 is not an exclusive property of living beings ; for even crystals 
 will repair themselves when, after pieces have been broken from 
 them, they are placed in the same conditions in which they 
 were first formed." 
 
 GLASS BROKEN BY SAND. 
 
 In some glass-houses the workmen show glass which has 
 been cooled in the open air ; on this they let fall leaden bul- 
 lets without breaking the glass. They afterwards desire you 
 to let a few grains of sand fall upon the glass, by which it is 
 broken into a thousand pieces. The reason of this is, that the 
 lead does not scratch the surface of the glass ; whereas the sand, 
 being sharp and angular, scratches it sufficiently to produce 
 the above effect, 
 
Curiosities of Science. 27 
 
 Sountr ant ILtgfjt 
 
 SOUNDING SAND. 
 
 MR. HUGH MILLER, the geologist, when in the island of Eigg, 
 in the Hebrides, observed that a musical sound was produced 
 when he walked over the white dry sand of the beach. At each 
 step the sand was driven from his footprint, and the noise was 
 simultaneous with the scattering of the sand ; the cause being 
 either the accumulated vibrations of the air when struck by 
 the driven sand, or the accumulated sounds occasioned by the 
 mutual impact of the particles of sand against each other. If 
 a musket-ball passing through the air emits a whistling note, 
 each individual particle of sand must do the same, however 
 faint be the note which it yields ; and the accumulation of 
 these infinitesimal vibrations must constitute an audible sound, 
 varying with the number and velocity of the moving particles. 
 In like manner, if two plates of silex or quartz, which are but 
 crystals of sand, give out a musical sound when mutually 
 struck, the impact or collision of two minute crystals or par- 
 ticles of sand must do the same, in however inferior a degree ; 
 and the union of all these sounds, though singly imperceptible, 
 may constitute the musical notes of " the Mountain of the 
 Bell" in Arabia Petraea, or the lesser sounds of the trodden 
 sea-beach of Eigg. North-British Review, No. 5. 
 
 INTENSITY OF SOUND IN RAREFIED AIR. 
 
 The experiences during ascents of the highest mountains 
 are contradictory. Saussure describes the sounds on the top 
 of Mont Blanc as remarkably weak : a pistol-shot made no 
 more noise than an ordinary Chinese cracker, and the popping 
 of a bottle of champagne was scarcely audible. Yet Martius, 
 in the same situation, was able to distinguish the voices of the 
 guides at a distance of 1340 feet, and to hear the tapping of a 
 lead pencil upon a metallic surface at a distance of from 75 to 
 100 feet. 
 
 MM Wertheim and Breguet have propagated sound over 
 the wire of an electric telegraph at the rate of 11,454 feet per 
 second. 
 
 DISTANCE AT WHICH THE HUMAN VOICE MAY BE HEARD. 
 
 Experience shows that the human voice, under favourable 
 circumstances, is capable of filling a larger space than was ever 
 
28 Things not generally Known. 
 
 probably enclosed within the walls of a single room. Lieutenant 
 Foster, on Parry's third Arctic expedition, found that he could 
 converse with a man across the harbour of Port Boweu, a dis- 
 tance of 6696 feet, or about one mile and a quarter. Dr. Young 
 records that at Gibraltar the human voice has been heard at a 
 distance of ten miles. If sound be prevented from spreading 
 and losing itself in the air, either by a pipe or an extensive flat 
 surface, as a wall or still water, it may be conveyed to a great 
 distance. Biot heard a flute clearly through a tube of cast-iron 
 (the water-pipes of Paris) 3120 feet long : the lowest whisper was 
 distinctly heard j indeed, the only way not to be heard was riot 
 to speak at all. 
 
 THE ROAR OF NIAGARA. 
 
 The very nature of the sound of running water pronounces 
 its origin to be the bursting of bubbles : the impact of water 
 against water is a comparatively subordinate cause, and could 
 never of itself occasion the murmur of a brook ; whereas, in 
 streams which Dr. Tyndall has examined, he, in all cases where 
 a ripple was heard, discovered bubbles caused by the broken 
 column of water. Now, were Niagara continuous, and without 
 lateral vibration, it would be as silent as a cataract of ice. In 
 all probability, it has its "contracted sections," after passing 
 which it is broken into detached masses, which, plunging suc- 
 cessively upon the air-bladders formed by their precursors, sud- 
 denly liberate their contents, and thus create the thunder of the 
 waterfall. 
 
 FIGURES PRODUCED BY SOUND. 
 
 Stretch a sheet of wet paper over the mouth of a glass tum- 
 bler which has a footstalk, and glue or paste the paper at the 
 edges. When the paper is dry, strew dry sand thinly upon its 
 surface. Place the tumbler on a table, and hold immediately 
 above it, and parallel to the paper, a plate of glass, which 
 you also strew with sand, having previously rubbed the edges 
 smooth with emery powder. Draw a violin-bow along any 
 part of the edges ; and as the sand upon the glass is made to 
 vibrate, it will form various figures, which will be accurately 
 imitated by the sand upon the paper ; or if a violin or flute be 
 played within a few inches of the paper, they will cause the 
 sand upon its surface to form regular lines and figures. 
 
 THE TUNING-FORK A FLUTE-PLAYER. 
 
 Take a common tuning-fork, and on one of its branches 
 fasten with sealing wax a circular piece of card of the size of 
 a small wafer, or sufficient nearly to cover the aperture of a 
 pipe, as the sliding of the upper end of a flute with the mouth 
 
Curiosities of Science. 29 
 
 stopped : it may be tuned in unison with the loaded tuning- 
 fork by means of the movable stopper or card, or the fork may 
 be loaded till the unison is perfect. Then set the fork in vi- 
 bration by a blow on the unloaded branch, and hold the card 
 closely over the mouth of the pipe, as in the engraving, when 
 a note, of surprising clearness and strength will be heard. In- 
 deed a flute may be made to " speak" perfectly well, by holding 
 close to the opening a vibrating tuning-fork, while the fingering 
 proper to the note of the fork is at the same time performed. 
 
 THEORY OF THE JEW^S HARP. 
 
 If you cause the tongue of this little instrument to vibrate, 
 it will produce a very low sound ; but if you place it before a 
 cavity (as the mouth) containing a column of air, which vi- 
 brates much faster, but in the proportion of any simple mul- 
 tiple, it will then produce other higher sounds, dependent upon 
 the reciprocation of that portion of the air. Now the bulk of 
 air in the mouth can be altered in its form, size, and other cir- 
 cumstances, so as to produce by reciprocation many different 
 sounds ; and these are the sounds belonging to the Jew's Harp. 
 
 A proof of this fact has been given by Mr. Eulen stein, who 
 fitted into a long metallic tube a piston, which being moved, 
 could be made to lengthen or shorten the efficient column of 
 air within at pleasure. A Jew's Harp was then so fixed that 
 it could be made to vibrate before the mouth of the tube, and 
 it was found that the column of air produced a series of sounds, 
 according as it was lengthened or shortened ; a sound being 
 produced whenever the length of the column was such that its 
 vibrations were a multiple of those of the Jew's Harp. 
 
 SOLAR AND ARTIFICIAL LIGHT COMPARED. 
 
 The most intensely ignited solid (produced by the flame of 
 Lieutenant Drummond's oxy-hydrogen lamp directed against a 
 surface of chalk) appears only as black spots on the disc of the 
 sun, when held between it and the eye ; or in other words, 
 Drummond's light is to the light of the sun's disc as 1 to 146. 
 Hence we are doubly struck by the felicity with which Galileo, 
 as early as 1612, by a series of conclusions on the smallness of 
 the distance from the sun at which the disc of Venus was no 
 longer visible to the naked eye, arrived at the result that the 
 blackest nucleus of the sun's spots was more luminous than 
 the brightest portions of the full moon. (See " The Sun's 
 Light compared with Terrestrial Lights," in Things not generally 
 Known, pp. 4, 5.) 
 
 SOURCE OF LIGHT. 
 
 Mr. Robert Hunt, in a lecture delivered by him at the 
 Russell Institution, " On the Physics of a Sunbeam," mentions 
 
30 Things not generally Known. 
 
 some experiments by Lord Brougham on the sunbeam, in which, 
 by placing the edge of a sharp knife just within the limit of 
 the light, the ray was inflected from its previous direction, and 
 coloured red ; and when another knife was placed on the op- 
 posite side, it was deflected, and the colour was blue. These 
 experiments (says Mr. Hunt) seem to confirm Sir Isaac New- 
 ton's theory, that light is a fluid emitted from the sun. 
 
 THE UNDULATORY SCALE OF LIGHT. 
 
 The white light of the sun is well known to be composed of 
 several coloured rays ; or rather, according to the theory of 
 undulations, when the rate at which a ray vibrates is altered, 
 a different sensation is produced upon the optic nerve. The 
 analytical examination of this question shows that to produce 
 a red colour the ray of light must give 37,640 undulations in 
 an inch, and 458,000,000,000,000 in a second. Yellow light re- 
 quires 44,000 undulations in an inch, and 535,000,000,000,000 
 in a second ; whilst the effect of blue results from 51,110 un- 
 dulations within an inch, and 622,000,000,000,000 of waves in 
 a second of time. Hunt's Poetry of Science. 
 
 VISIBILITY OF OBJECTS. 
 
 In terrestrial objects, the form, no less than the modes of 
 illumination, determines the magnitude of the smallest angle 
 of vision for the naked eye. Adams very correctly observed 
 that a long and slender staff can be seen at a much greater 
 distance than a square whose sides are equal to the diameter of 
 the staff. A stripe may be distinguished at a greater distance 
 than a spot, even when both are of the same diameter. 
 
 The minimum optical visual angle at which terrestrial ob- 
 jects can be recognised by the naked eye has been gradually 
 estimated lower and lower, from the time when Robert Hooke 
 fixed it exactly at a full minute, and Tobias Meyer required 
 34" to perceive a black speck on white paper, to the period 
 of Leuwenhoeck's experiments with spiders' threads, which are 
 visible to ordinary sight at an angle of 4" 7. In Hueck's most 
 accurate experiments on the problem of the movement of the 
 crystalline lens, white lines on a black ground were seen at an 
 angle of 1"'2 ; a spider's thread at 0"*6 ; and a fine glistening 
 wire at scarcely 0"*2. 
 
 Humboldt, when at Chillo, near Quito, where the crests of the 
 volcano of Pichincha lay at a horizontal distance of 90,000 feet, was 
 much struck by the circumstance that the Indians standing near distin- 
 guished the figure of Bonpland (then on an expedition to the volcano), 
 as a white point moving on the black basaltic sides of the rock, sooner 
 than Humboldt could discover him with a telescope. Bonplaud was 
 enveloped in a white cotton poncho : assuming the breadth across the 
 shoulders to vary from three to five feet, according as the mantle clung 
 
Curiosities of Science. 31 
 
 to the figure or fluttered in the breeze, and judging from the known 
 distance, the angle at which the moving object could be distinctly seen 
 varied from 7" to 12". White objects on a black ground are, according 
 to Hueck, distinguished at a greater distance than black objects on a 
 white ground. 
 
 Gauss's heliotrope light has been seen with the naked eye reflected 
 from the Brocken on Hobenhagen at a distance of about 227,000 feet, 
 or more than 42 miles ; being frequently visible at points in which the 
 apparent breadth of a three-inch mirror was only 0"'43. 
 
 THE SMALLEST BRIGHT BODIES. 
 
 Ehrenberg has found from experiments on the dust of dia- 
 monds, that a diamond superficies of Tro^h of a line in diameter 
 presents a much more vivid light to the naked eye than one of 
 quicksilver of the same diameter. On pressing small globules 
 of quicksilver on a glass micrometer, he easily obtained smaller 
 globules of the T <3c>th to the ^o^th of a line in diameter. In 
 the sunshine he could only discern the reflection of light, and 
 the existence of such globules as were ^th of a line in dia- 
 meter, with the naked eye. Smaller ones did not affect his 
 eye ; but he remarked that the actual bright part of the glo- 
 bule did not amount to more than no-oth of a line in diameter. 
 Spider threads of a^th m diameter were still discernible 
 from their lustre. Ehrenberg concludes that there are in or- 
 ganic bodies magnitudes capable of direct proof which are in 
 diameter Too ' 00() of a line ; and others, that can be indirectly 
 proved, which may be less than a six-millionth part of a Paris- 
 ian line in diameter. 
 
 VELOCITY OF LIGHT. 
 
 It is scarcely possible so to strain the imagination as to con- 
 ceive the Velocity with which Light travels. " What mere 
 assertion will make any man believe," asks Sir John Herschel, 
 " that in one second of time, in one beat of the pendulum of 
 a clock, a ray of light travels over 192,000 miles; and would 
 therefore perform the tour of the world in about the same time 
 that it requires to wink with our eyelids, and in much less time 
 than a swift runner occupies in taking a single stride 1 ?" Were 
 a cannon-ball shot directly towards the sun, and were it to main- 
 tain its full speed, it would be twenty years in reaching it; and 
 yet light travels through this space in seven or eight minutes. 
 
 The result given in the Annuaire for 1842 for the velocity 
 of light in a second is 77,000 leagues, which corresponds to 
 215,834 miles ; while that obtained at the Pulkowa Observatory 
 is 189,746 miles. William Richardson gives as the result of the 
 passage of light from the sun to the earth 8' 19" '28, from which 
 we obtain a velocity of 215,392 miles in a second. Memoirs of 
 the Astronomical Society ', vol. iv. 
 
32 Things not generally Known. 
 
 In other words, light travels a distance equal to eight times 
 the circumference of the earth between two beats of a clock. 
 This is a prodigious velocity; but the measure of it is very cer- 
 tain. -Professor Airy. 
 
 The navigator who has measured the earth's circuit by his 
 hourly progress, or the astronomer who has paced a degree of 
 the meridian, can alone form a clear idea of velocity, when we 
 tell him that light moves through a space equal to the circum- 
 ference of the earth in the eighth part of a second in the twink- 
 ling of an eye. 
 
 Could an observer, placed in the centre of the earth, see this moving 
 light, as it describes the earth's circumference, it would appear a lumin- 
 ous ring ; that is, the impression of the light at the commencement of 
 its journey would continue on the retina till the light had completed its 
 circuit. Nay, since the impression of light continues longer than the 
 fourth part of a second, two luminous rings would be seen, provided the 
 light made two rounds of the earth, and in paths not coincident. 
 
 APPARATUS FOR THE MEASUREMENT OF LIGHT. 
 
 Humboldt enumerates the following different methods 
 adopted for the Measurement of Light : a comparison of the 
 shadows of artificial lights, differing in numbers and distance ; 
 diaphragms ; plane-glasses of different thickness and colour ; 
 artificial stars formed by reflection on glass spheres ; the juxta- 
 position of two seven-feet telescopes, separated by a distance 
 which the observer could pass in about a second ; reflecting in- 
 struments in which two stars can be simultaneously seen and 
 compared, when the telescope has been so adjusted that the 
 star gives two images of like intensity ; an apparatus having 
 (in front of the object-glass) a mirror arid diaphragms, whose 
 rotation is measured on a ring ; telescopes with divided ob- 
 ject-glasses, on either half of which the stellar light is received 
 through a prism ; astrometers, in which a prism reflects the 
 image of the moon or Jupiter, and concentrates it through a 
 lens at different distances into a star more or less bright. 
 Cosmos ', vol. iii. 
 
 HOW FIZEAU MEASURED THE VELOCITY OF LIGHT. 
 
 This distinguished physicist has submitted the Velocity of 
 Light to terrestrial measurement by means of an ingeniously 
 constructed apparatus, in which artificial light (resembling 
 stellar light), generated from oxygen and hydrogen, is made 
 to pas? back, by means of a mirror, over a distance of 28,321 
 feet to the same point from which it emanated. A disc, hav- 
 ing 720 teeth, which made 12'6 rotations in a second, alter- 
 nately obscured the ray of light and allowed it to be seen 
 between the teeth on the margin. It was supposed, from the 
 marking of a counter, that the artificial light traversed 56,642 
 
Curiosities of Science. 33 
 
 feet, or the distance to and from the stations, in -j-g-Voth part of 
 a second, whence we obtain a velocity of 191,460 miles in a se- 
 cond.* This result approximates most closely to Delarnbre's 
 (which was 189,173 miles), as obtained from Jupiter's satellites. 
 
 The invention of the rotating mirror is due to Wheatstone, who made 
 an experiment with it to determine the velocity of the propagation of the 
 discharge of a Leyden battery. The most striking application of the 
 idea was made by Fizeau and Foucault, in 1853, in carrying out a pro- 
 position made by Arago, soon after the invention of the mirror : we have 
 here determined in a distance of twelve feet no less than the velocity 
 with which light is propagated, which is known to be nearly 200,000 
 miles a second; the distance mentioned corresponds therefore to the 
 77-millionth part of a second. The object of these measurements was 
 to compare the velocity of light in air with its velocity in water; which, 
 when the length is greater, is not sufficiently transparent. The most 
 complete optical and mechanical aids are here necessary: the mirror of 
 Foucault made from 600 to 800 revolutions in a second, while that of 
 Fizeau performed 1200 to 1500 in the same time. Prof. Helmholtz on 
 the Methods of Measuring very small Portions of Time. 
 
 WHAT IS DONE BY POLAEISATION OF LIGHT. 
 
 Malus, in 1808, was led by a casual observation of the light 
 of the setting sun, reflected from the windows of the Palais de 
 Luxembourg, at Paris, to investigate more thoroughly the phe- 
 nomena of double refraction, of ordinary and of chromatic po- 
 larisation, of interference and of diffraction of light. Among 
 his results may be reckoned the means of distinguishing between 
 direct and reflected light ; the power of penetrating, as it were, 
 into the constitution of the body of the sun and of its luminous 
 envelopes ; of measuring the pressure of atmospheric strata, 
 and even the smallest amount of water they contain ; of ascer- 
 taining the depths of the ocean and its rocks by means of a 
 tourmaline plate ; and in accordance with Newton's prediction, 
 of comparing the chemical composition of several substances 
 with their optical effects. 
 
 Arago, in a letter to Humboldt, states that by the aid of his polari- 
 scope, he discovered, before 1820, that the light of all terrestrial objects 
 in a state of incandescence, whether they be solid or liquid, is natural, 
 so long as it emanates from the object in perpendicular rays. On the 
 other hand, if such light emanate at an acute angle, it presents mani- 
 fest proofs of polarisation. This led M. Arago to the remarkable co:i- 
 clusion, that light is not generated on the surface of bodies only, but that 
 some portion is actually engendered within the substance itself, even in 
 the case of platinum. 
 
 A ray of light which reaches onr eyes after traversing many 
 millions of miles, from the remotest regions of heaven, an- 
 nounces, as it were of itself, in the polariscope, whether it is 
 
 * Fizeau gives his result in leagues, reckoning twenty-five to the equatorial 
 degree. He estimates the velocity of light at 70,000 such leagues, or about 
 210,000 miles in the second. 
 
34* Things not generally Known. 
 
 reflected or refracted, whether it emanates from a solid or fluid 
 or gaseous body ; it announces even the degree of its intensity. 
 Humboldt's Cosmos, vols. i. and ii. 
 
 MINUTENESS OF LIGHT. 
 
 There is something wonderful, says Arago, in the experi- 
 ments which have led natural philosophers legitimately to talk 
 of the different sides of a ray of light ; and to show that mil- 
 lions and millions of these rays can simultaneously pass through 
 the eye of a needle without interfering with each other ! 
 
 THE IMPORTANCE OF LIGHT. 
 
 Light affects the respiration of animals just as it affects the 
 respiration of plants. This is novel doctrine, but it is demon- 
 strable. In the day-time we expire more carbonic acid than 
 during the night; a fact known to physiologists, who explain 
 it as the effect of sleep : but the difference is mainly owing to 
 the presence or absence of sunlight ; for sleep, as sleep, increases, 
 instead of diminishing, the amount of carbonic acid expired, 
 and a man sleeping will expire more carbonic acid than if he 
 lies quietly awake under the same conditions of light and tem- 
 perature ; so that if less is expired during the night than during 
 the day, the reason cannot be sleep, but the absence of light. 
 Now we understand why men are sickly and stunted who live 
 in narrow streets, alleys, and cellars, compared with those who, 
 under similar conditions of poverty and dirt, live in the sun- 
 light. BlackwoocTs Edinburgh Magazine, 1858. 
 
 The influence of light on the colours of organised creation is well 
 shown in the sea. Near the shores we find seaweeds of the most beau- 
 tiful hues, particularly on the rocks which are left dry by the tides ; and 
 the rich tints of the actiniae which inhabit shallow water must often 
 have been observed. The fishes which swim near the surface are also 
 distinguished by the variety of their colours, whereas those which live at 
 greater depths are gray, brown, or black. It has been found that after 
 a certain depth, where the quantity of light is so reduced that a mere 
 twilight prevails, the inhabitants of the ocean become nearly colourless. 
 Hunt's Poetry of Science. 
 
 ACTION OF LIGHT ON MUSCULAR FIBRES. 
 
 That light is capable of acting on muscular fibres, indepen- 
 dently of the influence of the nerves, was mentioned by several 
 of the old anatomists, but repudiated by later authorities. M. 
 Brown Sequard has, however, proved to the Royal Society that 
 some portions of muscular fibre the iris of the eye, for example 
 are affected by light independently of any reflex action of the 
 nerves, thereby confirming former experiences. The effect is 
 produced by the illuminating rays only, the chemical and heat 
 rays remaining neutral. And not least remarkable is the fact, 
 
Curiosities of Science. 35 
 
 that the iris of an eel showed itself susceptible of the excite- 
 ment sixteen days after the eyes were removed from the creature's 
 head. So far as is yet known, this muscle is the only one on 
 which light thus takes effect. Phil. Trans. 1857. 
 
 LIGHT NIGHTS. 
 
 It is not possible, as well-attested facts prove, perfectly to 
 explain the operations at work in the much-contested upper 
 boundaries of our atmosphere. The extraordinary lightness of 
 whole nights in the year 1831, during which small print might 
 be read at midnight in the latitudes of Italy and the north of 
 Germany, is a fact directly at variance with all that we know, 
 according to the most recent and acute researches on the cre- 
 puscular theory and the height of the atmosphere. Biot. 
 
 PHOSPHORESCENCE OF PLANTS. 
 
 Mr. Hunt recounts these striking instances. The leaves of 
 the cenothera macrocarpa are said to exhibit phosphoric light 
 when the air is highly charged with electricity. The agarics 
 of the olive-grounds of Montpelier too have been observed to be 
 luminous at night ; but they are said to exhibit no light, even 
 in darkness, during the day. The subterranean passages of the 
 coal-mines near Dresden are illuminated by the phosphores- 
 cent light of the rkizomorpha pkosp/wreus, a peculiar fungus. 
 On the leaves of the Pindoba palm grows a species of agaric 
 which is exceedingly luminous at night; and many varieties 
 of the lichens, creeping along the roofs of caverns, lend to them 
 an air of enchantment by the soft and clear light which they 
 diffuse. In a small cave near Penryn, a luminous moss is 
 abundant; it is also found in the mines of Hesse. According 
 to Heinzmann, the rhizomorpha subterranea and aidulce are also 
 phosphorescent. See Poetry of /Science. 
 
 PHOSPHORESCENCE OF THE SEA, 
 
 By microscopic examination of the myriads of minute insects 
 which cause this phenomenon, no other fact has been elicited 
 than that they contain a fluid which, when squeezed out, leaves 
 a train of light upon the surface of the water. The creatures 
 appear almost invariably on the eve of some change of weather, 
 which would lead us to suppose that their luminous phenomena 
 must be connected with electrical excitation ; and of this Mr. C. 
 Peach of Fowey has furnished the most satisfactory proofs yet 
 obtained.* 
 
 LIGHT FROM THE JUICE OF A PLANT. 
 
 In Brazil has been observed a plant, conjectured to be an 
 
 * See Things not generally Known, p. 88. 
 
36 Things not generally Known. 
 
 Euphorbiura, very remarkable for the light which it yields when 
 cut. It contains a milky juice, which exudes as soon as the 
 plant is wounded, and appears luminous for several seconds. 
 
 LIGHT FROM FUNGUS. 
 
 Phosphorescent funguses have been found in Brazil by Mr. 
 Gardner, growing on the decaying leaves of a dwarf palm. They 
 vary from one to two inches across, and the whole plant gives 
 out at night a bright phosphorescent light, of a pale greenish 
 hue, similar to that emitted by fire-flies and phosphorescent 
 marine animals. The light given out by a few of these fungi 
 in a dark room is sufficient to read by. A very large phospho- 
 rescent species is occasionally found in the Swan River colony. 
 
 LIGHT FEOM BUTTONS. 
 
 Upon highly polished gilt buttons no figure whatever can 
 be seen by the most careful examination; yet, when they are 
 made to reflect the light of the sun or of a candle upon a piece 
 of paper held close to them, they give a beautiful geometrical 
 figure, with ten rays issuing from the centre, and terminating 
 in a luminous rim. 
 
 COLOURS OF SCRATCHES. 
 
 An extremely fine scratch on a well-polished surface may 
 be regarded as having a concave, cylindrical, or at least a 
 curved surface, capable of reflecting light in all directions; this 
 is evident, for it is visible in all directions. Hence a single 
 scratch or furrow in a surface may produce colours by the inter- 
 ference of the rays reflected from its opposite edges. Examine 
 a spider's thread in the sunshine, and it will gleam with vivid 
 colours. These may arise from a similar cause ; or from the 
 thread itself, as spun by the animal, consisting of several 
 threads agglutinated together, and thus presenting, not a cy- 
 lindrical, but a furrowed surface. 
 
 MAGIC BUST. 
 
 Sir David Brewster has shown how the rigid features of a 
 white bust may be made to move and vary their expression, 
 sometimes smiling and sometimes frowning, by moving rapidly 
 in front of the bust a bright light, so as to make the lights and 
 shadows take every possible direction and various degrees of 
 intensity ; and if the bust be placed before a concave mirror, 
 its image may be made to do still more when it is cast upon 
 wreaths of smoke. 
 
 COLOURS HIT MOST FREQUENTLY DURING BATTLE. 
 
 Jt would appear from numerous observations that soldiers 
 
Curiosities of Science. 37 
 
 are hit during battle according to the colour of their dress in 
 the following order : red is the most fatal colour ; the least 
 fatal, Austrian gray. The proportions are, red, 12 ; rifle-green, 
 7 ; brown, 6 ; Austrian bluish-gray, 5. Jameson's Journal, 1853. 
 
 TRANSMUTATION OF TOPAZ. 
 
 Yellow topazes may be converted into pink by heat ; but it 
 is a mistake to suppose that in the process the yellow colour is 
 changed into pink : the fact is, that one of the pencils being 
 yellow and the other pink, the yellow is discharged by heat, 
 thus leaving the pink unimpaired. 
 
 COLOURS AND TINTS. 
 
 M. Chevreul, the Directeur des Gobelins, has presented to the 
 French Academy a plan for a universal chromatic scale, and a 
 methodical classification of all imaginable colours. Mayer, a 
 professor at Gottingen, calculated that the different combina- 
 tions of primitive colours produced 819 different tints; but M. 
 Chevreul established not less than 14,424, all very distinct and 
 easily recognised, all of course proceeding from the three pri- 
 mitive simple colours of the solar spectrum, red, yellow, and 
 blue. For example, he states that in the violet there are twenty- 
 eight colours, and in the dahlia forty-two. 
 
 OBJECTS REALLY OF NO COLOUR. 
 
 A body appears to be of the colour which it reflects ; as we 
 see it only by reflected rays, it can but appear of the colour 
 of those rays. Thus grass is green because it absorbs all except 
 the green rays. Flowers, in the same manner, reflect the va- 
 rious colours of which they appear to us : the rose, the red rays ; 
 the violet, the blue; the daffodil, the yellow, &c. But these 
 are not the permanent colours of the grass and flowers; for 
 wherever you see these colours, the objects must be illuminated; 
 and light, from whatever source it proceeds, is of the same na- 
 ture, composed of the various coloured rays which paint the 
 grass, the flowers, and every coloured object in nature. Objects 
 in the dark have no colour, or are black, which is the same 
 thing. You can never see objects without light. Light is com- 
 posed of colours, therefore there can be no light without co- 
 lours ; and though every object is black or without colour in 
 the dark, it becomes coloured as soon as it becomes visible. 
 
 THE DIORAMA WHY SO PERFECT AN ILLUSION. 
 
 Because when an object is viewed at so great a distance 
 that the optic axes of both eyes are sensibly parallel when 
 directed towards it, the perspective projections of it, seen by 
 
38 Things not generally Known. 
 
 each eye separately, are similar ; and the appearance to the 
 two eyes is precisely the same as when the object is seen by 
 one eye only. There is, in such case, no difference between 
 the visual appearance of an object in relief and its perspective 
 projection ou a plane surface ; hence pictorial representations 
 of distant objects, when those circumstances which would pre- 
 vent or disturb the illusion are carefully excluded, may be 
 rendered such perfect resemblances of the objects they are in- 
 tended to represent as to be mistaken for them. The Diorama 
 is an instance of this. Professor W/ieatstone; Philosophical 
 Transactions, 1838. 
 
 CURIOUS OPTICAL EFFECTS AT THE CAPE. 
 
 Sir John Herschel, in his observatory at Feldhausen, at the 
 base of the Table Mountain, witnessed several curious optical 
 effects, arising from peculiar conditions of the atmosphere in- 
 cident to the climate of the Cape. In the hot season "the 
 nights are for the most part superb ;" but occasionally, during 
 the excessive heat and dryness of the sandy plains, " the op- 
 tical tranquillity of the air" is greatly disturbed. In some 
 cases, the images of the stars are violently dilated into nebular 
 balls or puffs of 15' in diameter; on other occasions they form 
 " soft, round, quiet pellets of 3' or 4' diameter," resembling 
 planetary nebulas. In the cooler months the tranquillity of 
 the image and the sharpness of vision are such, that hardly any 
 limit is set to magnifying power but that which arises from 
 the aberration of the specula. On occasions like these, optical 
 phenomena of extraordinary splendour are produced by viewing 
 a bright star through a diaphragm of cardboard or zinc pierced 
 in regular patterns of circular holes by machinery : these phe- 
 nomena surprise and delight every person that sees them. 
 When close double stars are viewed with the telescope, with a 
 diaphragm in the form of an equilateral triangle, the discs of 
 the two stars, which are exact circles, have a clearness and 
 perfection almost incredible. 
 
 THE TELESCOPE AND THE MICROSCOPE. 
 
 So singular is the position of the Telescope and the Micro- 
 scope among the great inventions of the age, that no other 
 process but that which they embody could make the slightest 
 approximation to the secrets which they disclose. The steam- 
 engine might have been imperfectly replaced by an air or an 
 ether-engine ; and a highly elastic fluid might have been, and 
 may yet be, found, which shall impel the "rapid car," or drag 
 the merchant- ship over the globe. The electric telegraph, 
 now so perfect and unerring, might have spoken to us in the 
 
Curiosities of Science. 39 
 
 rude " language of chimes ;" or sound, in place of electricity, 
 might have passed along the metallic path, and appealed to 
 the ear in place of the eye. For the printing-press and the 
 typographic art might have been found a substitute, however 
 poor, in the lithographic process ; and knowledge might have 
 been widely diffused by the photographic printing powers of 
 the sun, or even artificial light. But without the telescope and 
 the microscope, the human eye would have struggled in vain to 
 study the worlds beyond our own, and the elaborate structures 
 of the organic and inorganic creation could never have been 
 revealed. North- British Review, No. 50. 
 
 INVENTION OF THE MICROSCOPE. 
 
 The earliest magnifying lens of which we have any know- 
 ledge was one rudely made of rock-crystal, which Mr. Layard 
 found, among a number of glass bowls, in the north-west palace 
 of Nimroud ; but no similar lens has been found or described 
 to induce us to believe that, the microscope, either single or 
 compound, was invented and used as an instrument previous 
 to the commencement of the seventeenth century. In the 
 beginning of the first century, however, Seneca alludes to the 
 magnifying power of a glass globe filled with water ; but as he 
 only states that it made small and indistinct letters appear 
 larger and more distinct, we cannot consider such a casual re- 
 mark as the invention of the single microscope, though it might 
 have led the observer to try the effect of smaller globes, and 
 thus obtain magnifying powers sufficient to discover pheno- 
 mena otherwise invisible. 
 
 Lenses of glass were undoubtedly in existence at the time 
 of Pliny ; but at that period, and for many centuries after- 
 wards, they appear to have been used only as burning or as 
 reading glasses ; and no attempt seems to have been made to 
 form them of so small a size as to entitle them to be regarded 
 even as the precursors of the single microscope. North- British 
 Review, No. 50. 
 
 The rock-crystal leiis found at Nineveh was examined by Sir David 
 Brewster. It was not entirely circular in its aperture. Its general form 
 was that of a plano-convex lens, the plane side having been formed of one 
 of the original faces of the six-sided crystal quartz, as Sir David ascer- 
 tained by its action on polarised light: this was badly polished and 
 scratched. The convex face of the lens had not been ground in a dish- 
 shaped, tool, in the manner in which lenses are now formed, but was 
 shaped on a lapidary's wheel, or in some such manner. Hence it was 
 unequally thick ; but its extreme thickness was T 3 s ths of an inch, its 
 focal length being 4 inches. It had twelve remains of cavities, which 
 had originally contained liquids or condensed gases. Sir David has 
 assigned reasons why this could not be looked upon as an ornament, but 
 a true optical lens. In the same ruins were found, some decomposed 
 glass. 
 
40 Things not generally Known. 
 
 HOW TO MAKE THE FISH-EYE MICROSCOPE. 
 
 Very good microscopes may be made with the crystalline 
 lenses of fish, birds, and quadrupeds. As the lens of fishes is 
 spherical or spheroidal, it is absolutely necessary, previous to 
 its use, to determine its optical axis and the axis of vision 
 of the eye from which it is taken, and place the lens in such a 
 manner that its axis is a continuation of the axis of our own. 
 eye. In no other direction but this is the albumen of which 
 the lens consists symmetrically disposed in laminae of equal 
 density round a given line, which is the axis of the lens ; and 
 in no other direction does the gradation of density, by which 
 the spherical aberration is corrected, preserve a proper relation 
 to the axis of vision. 
 
 When the lens of any small fi.sh, such as a minnow, a par, or trout, 
 has been taken out, along with the adhering vitreous humour, from the 
 eye-ball by cutting the sclerotic coat with a pair of scissors, it should be 
 placed upon a piece of fine silver-paper previously freed from its minute 
 adhering fibres. The absorbent nature of the paper will assist in re- 
 moving all the vitreous humour from the lens ; and when this is care- 
 fully done, by rolling it about with another piece of silver-papei", there 
 will still remain, round or near the equator of the lens, a black ridge, 
 consisting of the processes by which it was suspended in the eye-ball. 
 The black circle points out to us the true axis of the lens, which is per- 
 pendicular to a plane passing through it. When the small crystalline 
 has been freed from all the adhering vitreous humour, the capsule which 
 contains it will have a surface as fine as a pellicle of fluid. It is then to 
 be dropped from the paper into a cavity formed by a brass rim, and its 
 position changed till the black circle is parallel to the circular rim, in 
 which case only the axis of the lens will be a continuation of the axis of 
 the observer's eye. Edin. Jour. Science, vol. ii. 
 
 LEUWENHOECK'S MICROSCOPES. 
 
 Leuwenhoeck, the father of microscopical discovery, com- 
 municated to the Royal Society, in 1673, a description of the 
 structure of a bee and a louse, seen by aid of his improved mi- 
 croscopes ; and from this period until his decease in 1723, he 
 regularly transmitted to the society his microscopical observa- 
 tions and discoveries, so that 375 of his papers and letters are 
 preserved in the society's archives, extending over fifty years. 
 He further bequeathed to the Royal Society a cabinet of twenty- 
 six microscopes, which he had ground himself and set in silver, 
 mostly extracted by him from minerals; these microscopes were 
 exhibited to Peter the Great when he was at Delft in 1698. In 
 acknowledging the bequest, the council of the Royal Society, 
 in 1724, presented Leuwenhoeck's daughter with a handsome 
 silver bowl, bearing the arms of the society. Weld's History 
 of the Royal Society, vol. i. 
 
 DIAMOND LENSES FOR MICROSCOPES. 
 
 In recommending the employment of Diamond and other 
 
Curiosities of Science. 41 
 
 gems in the construction of Microscopes, Sir David Brewster 
 has been met with the objection that they are too expensive for 
 such a purpose ; and, says Sir David, " they certainly are for 
 instruments intended merely to instruct and amuse. But if 
 we desire to make great discoveries, to unfold secrets yet hid 
 in the cells of plants and animals, we must not grudge even a 
 diamond to reveal them. If Mr. Cooper and Sir James South 
 have given a couple of thousand pounds a piece for a refracting 
 telescope, in order to study what have been miscalled * dots ' 
 and ' lumps ' of light on the sky ; and if Lord Rosse has ex- 
 pended far greater sums on a reflecting telescope for analysing 
 what has been called ' sparks of mud and vapour ' encumber- 
 ing the azure purity of the heavens, why should not other phi- 
 losophers open their purse, if they have one, and other noble- 
 men sacrifice some of their household jewels, to resolve the mi- 
 croscopic structures of our own real world, and disclose secrets 
 which the Almighty must have intended that we should know ?" 
 Proceedings of the British Association, 1857. 
 
 THE EYE AND THE BRAIN SEEN THROUGH A MICROSCOPE, 
 
 By a microscopic examination of the retina and optic nerve 
 and the brain, M. Bauer found them to consist of globules of 
 oyfrqth to 4o7K>th of an inch diameter, united by a transparent 
 viscid and coagulable gelatinous fluid. 
 
 MICROSCOPICAL FXAMINATION OF THE HAIR. 
 
 If a hair be drawn between the finger and thumb, from the 
 end to the root, it will be distinctly felt to give a greater resist- 
 ance and a different sensation to that which is experienced 
 when drawn the opposite way : in consequence, if the hair be 
 rubbed between the fingers, it will only move one way (travel- 
 ling in the direction of a line drawn from its termination to its 
 origin from the head or body), so that each extremity may thus 
 be easily distinguished, even in the dark, by the touch alone. 
 
 The mystery is resolved by the achromatic microscope. A 
 hair viewed on a dark ground as an opaque object with a high 
 power, not less than that of a lens of one-thirtieth of an inch 
 focus, and dully illuminated by a cup, the hair is seen to be in- 
 dented with teeth somewhat resembling those of a coarse round 
 rasp, but extremely irregular and rugged : as these incline all 
 in one direction, like those of a common file, viz. from the 
 origin of the hair towards its extremity, it sufficiently explains 
 the above singular property. 
 
 This is a singular proof of the acuteness of the sense of feel- 
 ing, for the said teeth may be felt much more easily than they 
 can be seen. We may thus understand why a razor will cut a 
 hair in two much more easily when drawn against its teeth than 
 in the opposite direction. Dr. Goring. 
 
42 Things not generally Known. 
 
 THE MICROSCOPE AND THE SEA. 
 
 What myriads has the microscope revealed to us of the rich 
 luxuriance of animal life in the ocean, and conveyed to our as- 
 tonished senses a consciousness of the universality of life ! In 
 the oceanic depths every stratum of water is animated, and 
 swarms with countless hosts of small luminiferous animalcules, 
 mammaria, Crustacea, peridinea, and circling nereides, which, 
 when attracted to the surface by peculiar meteorological condi- 
 tions, convert every wave into a foaming band of flashing light. 
 
 USE OF THE MICROSCOPE TO MINERALOGISTS. 
 
 M. Dufour has shown that an imponderable quantity of a 
 substance can be crystallised ; and that the crystals so obtained 
 are quite characteristic of the substances, as of sugar, chloride 
 of sodium, arsenic, and mercury. This process may be ex- 
 tremely valuable to the mineralogist and toxicologist when the 
 substance for examination is too small to be submitted to tests. 
 By aid of the microscope, also, shells are measured to the thou- 
 sandth part of an inch. 
 
 FIXE DOWN OF QUARTZ. 
 
 Sir David Brewster having broken in two a crystal of quartz 
 of a smoky colour, found both surfaces of the fracture abso- 
 lutely black ; and the blackness appeared at first sight to be 
 owing to a thin h'lm of opaque matter which had insinuated 
 itself into the crevice. This opinion, however, was untenable, 
 as every part of the surface was black, and the two halves of the 
 crystals could not have stuck together had the crevice extended 
 across the whole section. Upon further examination Sir David 
 found that the surface was perfectly transparent by transmitted 
 light, and that the blackness of the surfaces arose from their 
 being entirely composed of a fine down of quartz, or of short 
 and slender filaments, whose diameter was so exceedingly small 
 that they were incapable of reflecting a single ray of the strong- 
 est light ; and they could not exceed the one third of the mil- 
 lionth part of an inch This curious specimen is in the cabinet 
 of her grace the Duchess of Gordon. 
 
 MICROSCOPIC WRITING. 
 
 Professor Kelland has shown, in Paris, on a spot no larger 
 than the head of a small pin, by means of powerful microscopes, 
 several specimens of distinct and beautiful writing, one of them 
 containing the whole of the Lord's Prayer written within this 
 minute compass. In reference to this, two remarkable facts in 
 Layard's latest work on Nineveh show that the national records 
 of Assyria were written on square bricks, in characters so small 
 as scarcely to be legible without a microscope ; in fact, a micro- 
 scope, as we have just shown, was found in the ruins of Mmroud. 
 
Curiosities of Science. 43 
 
 HOW TO MAKE A MAGIC MIRROR. 
 
 Draw a figure with weak gum-water upon the surface of a 
 convex mirror. The thin film of gum thus deposited on the 
 outline or details of the figure will not be visible in dispersed 
 daylight ; but when made to reflect the rays of the sun, or those 
 of a divergent pencil, will be beautifully displayed by the lines 
 and tints occasioned by the diffraction of light, or the inter- 
 ference of the rays passing through the film with those which 
 pass by it. 
 
 SIR DAVID BREWSTER'S KALEIDOSCOPE. 
 
 The idea of this instrument, constructed for the purpose of 
 creating and exhibiting a variety of beautiful and perfectly 
 symmetrical forms, first occurred to Sir David Brewster in 1814, 
 when he was engaged in experiments on the polarisation of 
 light by successive reflections between plates of glass. The 
 reflectors were in some instances inclined to each other ; and 
 he had occasion to remark the circular arrangement of the 
 images of a candle round a centre, or the multiplication of the 
 sectors formed by the extremities of the glass plates. In repeat- 
 ing at a subsequent period the experiments of M. Biot on the 
 action of fluids upon light, Sir David Brewster placed the fluids 
 in a trough, formed by two plates of glass cemented together at 
 an angle ; and the eye being necessarily placed at one end, some 
 of the cement, which had been pressed through between the 
 plates, appeared to be arranged into a regular figure. The re- 
 markable symmetry which it presented led to Dr. Brewster's 
 investigation of the cause of this phenomenon ; and in so doing 
 he discovered the leading principles of the Kaleidoscope. 
 
 By the advice of his friends, Dr. Brewster took out a patent 
 for his invention ; in the specification of which he describes the 
 kaleidoscope in two different forms. The instrument, however, 
 having been shown to several opticians in London, became 
 known before he could avail himself of his patent ; and being 
 simple in principle, it was at once largely manufactured. It is 
 calculated that not less than 200,000 kaleidoscopes were sold 
 in three months in London and Paris ; though out of this num- 
 ber, Dr. Brewster says, not perhaps 1000 were constructed upon 
 scientific principles, or were capable of giving any thing like a 
 correct idea of the power of his kaleidoscope. 
 
 THE KALEIDOSCOPE THOUGHT TO BE ANTICIPATED. 
 
 In the seventh edition of a work on gardening and plant- 
 ing, published in 1739, by Richard Bradley, F.K.S., late Pro- 
 fessor of Botany in the University of Cambridge, we find the 
 following details of an invention, u by which the best de- 
 
44 Things not generally Known. 
 
 signers and draughtsmen may improve and help their fancies. 
 They must choose two pieces of looking-glass of equal bigness, 
 of the figure of a long square. These must be covered on the 
 back with paper or silk, to prevent rubbing off the silver. This 
 covering must be so put on that nothing of it appears about the 
 edges of the bright side. The glasses being thus prepared, must 
 be laid face to face, and hinged together so that they may be 
 made to open and shut at pleasure like the leaves of a book." 
 After showing how various figures are to be looked at in these 
 glasses under the same opening, and how the same figare may 
 be varied under the different openings, the ingenious artist thus 
 concludes: " If it should happen that the reader has any num- 
 ber of plans for parterres or wildernesses by him, he may by this 
 method alter them at his pleasure, and produce such innumer- 
 able varieties as it is not possible the most able designer could 
 ever have contrived." 
 
 MAGIC OF PHOTOGRAPHY. 
 
 Professor Moser of Konigsberg has discovered that all bo- 
 dies, even in the dark, throw out invisible rays ; and that these 
 bodies, when placed at a small distance from polished surfaces 
 of all kinds, depict themselves upon such surfaces in forms 
 which remain invisible till they are developed by the human 
 breath or by the vapours of mercury or iodine. Even if the 
 sun's image is made to pass over a plate of glass, the light 
 tread of its rays will leave behind it an invisible track, which 
 the human breath will instantly reveal. 
 
 Among the early attempts to take pictures by the rays of the sun 
 was a very interesting and successful experiment made by Dr. Thomas 
 Young. In 1802, when Mr. Wedgevvood was " making profiles by the 
 agency of light," and Sir Humphry Davy was " copying on prepared 
 paper the images of small objects produced by means of the solar micro- 
 scope," Dr. Young was taking photographs upon paper dipped in n so- 
 lution of nitrate of silver, of the coloured rings observed by Newton ; 
 and his experiments clearly proved that the agent was not the luminous 
 rays in the sun's light, but the invisible or chemical rays beyond the 
 violet. This experiment is described in the Bakerian Lecture, 1803. 
 
 Niepce (says Mr. Hunt) pursued a physical investigation of the cu- 
 rious change, and found that all bodies were influenced by this principle 
 radiated from the sun. Daguerre* produced effects from the solar pencil 
 which no artist could approach ; and Talbot and others extended the 
 application. Herschel took up the inquiry; and he, with his usual 
 
 * Some time before the first announcement of the discovery of sun-painting', 
 the following extract from Sir John Herschel's Treatise on Light, in the Encyclo- 
 pcediaMrtropolitana, appeared in a popular work entitled Parlour Magic: " Strain 
 a piece of paper or linen upon a wooden frame, and sponge it over with a solution 
 of nitrate of silver in water; place it behind a painting upon glass, or a stained 
 window-pane, and the light, traversing the painting or figures, will produce a 
 copy of it upon the prepared paper or linen ; those parts in which the rays were 
 least intercepted being the shadows of the picture." 
 
Curiosities of Science. 45 
 
 power of inductive search and of philosophical deduction, presented the 
 world with a class of discoveries which showed how vast a field of inves- 
 tigation was opening for the younger races of mankind. 
 
 The first attempts in photography, which were made at the insti- 
 gation of M. Arago, by order of the French Government, to copy the 
 Egyptian tombs and temples and the remains of the Aztecs in Central 
 America, were failures. Although the photographers employed suc- 
 ceeded to admiration, in Paris, in producing pictures in a few minutes, 
 they found often that an exposure of an hour was insufficient under the 
 bright and glowing illumination of a southern sky. 
 
 THE BEST SKY FOR PHOTOGRAPHY. 
 
 Contrary to all preconceived ideas, experience proves that 
 the brighter the sky that shines above the camera the more 
 tardy the action within it. Italy and Malta do their work 
 slower than Paris. Under the brilliant light of a Mexican sun, 
 half an hour is required to produce effects which in England 
 would occupy but a minute. In the burning atmosphere of 
 India, though photographical the year round, the process is 
 comparatively slow and difficult to manage ; while in the clear, 
 beautiful, and moreover cool, light of the higher Alps of Eu- 
 rope, it has been proved that the production of a picture re- 
 quires many more minutes, even with the most sensitive pre- 
 parations, than in the murky atmosphere of London. Upon 
 the whole, the temperate skies of this country may be pro- 
 nounced favourable to photographic action ; a fact for which 
 the prevailing characteristic of our climate may partially ac- 
 count, humidity being an indispensable condition for the 
 working state both of paper and chemicals. Quarterly Review. 
 No. 202. 
 
 PHOTOGRAPHIC EFFECTS OF LIGHTNING. 
 
 The following authenticated instances of this singular phe- 
 nomenon have been communicated to the Royal Society by 
 Andres Poey, Director of the Observatory at Havana : 
 
 Benjamin Franklin, in 1786, stated that about twenty years previ- 
 ous, a man who was standing opposite a tree that had just been struck 
 by "a thunderbolt" had on his breast an exact representation of that 
 tree. 
 
 In the New-York Journal of Commerce, August 26th, 1853. it is re- 
 lated that " a little girl was standing at a window, before which was a 
 young maple-tree ; after a brilliant flash of lightning, a complete image 
 of the tree was found imprinted on her body." 
 
 M. Raspail relates that, in 1855, a boy having climbed a tree for 
 the purpose of robbing a bird's nest, the tree was struck, and the boy 
 thrown upon the ground ; on his breast the image of the tree, with the 
 bird and nest on one of its branches, appeared very plainly. 
 
 M. Olioli, a learned Italian, brought before the Scientific Congress 
 at Naples the following four instances : 1. In September 1825, the fore- 
 mast of a brigantine in the Bay of St. Arniro was struck by lightning, 
 when a sailor sitting under the mast was struck dead, and on his back 
 
46 Things not generally Known. 
 
 was found an impression of a horse-shoe, similar even in size to that 
 fixed on the mast-head. 2. A sailor, standing in a similar position, 
 was struck by lightning, and had on his left breast the impression of the 
 number 4 4, with a dot between the two figures, just as they appeared at 
 the extremity of one of the masts. 3. On the 9th October 1836, a young 
 man was found struck by lightning ; he had on a girdle, with some gold 
 coins in it, which were imprinted on his skin in the order they were 
 placed in the girdle, a series of circles, with one point of contact, being 
 plainly visible. 4. In 1847, Mme. Morosa, an Italian lady of Lugano, 
 was sitting near a window during a thunderstorm, and perceived the 
 commotion, but felt no injury ; but a flower which happened to be in 
 the path of the electric current was perfectly reproduced on one of her 
 legs, and there remained permanently. 
 
 M. Poey himself witnessed the following instance in Cuba. On July 
 24th, 1852, a poplar-tree in a coffee -plantation was struck by lightning, 
 and on one of the large dry leaves was found an exact representation 
 of some pine-trees that lay 367 yards distant. 
 
 M. Poey considers these lightning impressions to have 
 been produced in the same manner as the electric images ob- 
 tained by Moser, Riess, Karster, Grove, Fox Talbot, and others, 
 either by statical or dynamical electricity of different intensi- 
 ties. The fact that impressions are made through the gar- 
 ments is easily accounted for by their rough texture not pre- 
 venting the lightning passing through them with the impres- 
 sion. To corroborate this view, M. Poey mentions an instance 
 of lightning passing down a chimney into a trunk, in which 
 was found an inch depth of soot, which must have passed 
 through the wood itself. 
 
 PHOTOGRAPHIC SURVEYING. 
 
 During the summer of 1854, in the Baltic, the British 
 steamers employed in examining the enemy's coasts and for- 
 tifications took photographic views for reference and minute 
 examination. With the steamer moving at the rate of fifteen 
 knots an hour, the most perfect definitions of coasts and bat- 
 teries were obtained. Outlines of the coasts, correct in height 
 and distance, have been faithfully transcribed ; and all details 
 of the fortresses passed under this photographic review are ac- 
 curately recorded. 
 
 It is curious to reflect that the aids to photographic development -all 
 date within the last half-century, and are but little older than photo- 
 graphy itself. It was not until 1811 that the chemical substance called 
 iodine, on which the foundations of all popular photography rest, was 
 discovered at all ; bromine, the only other substance equally sensitive, 
 not till 1826. The invention of the electro process was about simul- 
 taneous with that of photography itself. Gutta-percha only just pre- 
 ceded the substance of which collodion is made ; the ether and chloro- 
 form, which are used in some methods, that of collodion. We say 
 nothing of the optical improvements previously contrived or adapted 
 for the purpose of the photograph : the achromatic lenses, which cor- 
 rect the discrepancy between the visual and chemical foci ; the double 
 
Curiosities of Science. 47 
 
 lenses, which increase the force of the action ; the binocular lenses, 
 which do the work of the stereoscope ; nor of the innumerable other 
 mechanical aids which have sprung up for its use. 
 
 THE STEREOSCOPE AND THE PHOTOGRAPH. 
 
 When once the availability of one great primitive agent 
 is worked out, it is easy to foresee how extensively it will assist 
 in unravelling other secrets in natural science. The simple 
 principle of the Stereoscope, for instance, might have been 
 discovered a century ago, for the reasoning which led to it 
 was independent of all the properties of light ; but it could 
 never have been illustrated, far less multiplied as it now is, 
 without Photography. A few diagrams, of sufficient identity 
 and difference to prove the truth of the principle, might have 
 been constructed by hand, for the gratification of a few sages ; 
 but no artist, it is to be hoped, could have been found possessing 
 the requisite ability and stupidity to execute the two portraits, 
 or two groups, or two interiors, or two landscapes, identical in 
 every minutia of the most elaborate detail, and yet diffe/ing 
 in point of view by the inch between the two human eyes, by 
 which the principle is brought to the level of any capacity. 
 Here, therefore, the accuracy and insensibility of a machine 
 could alone avail ; and if in the order of things the cheap popu- 
 lar toy which the stereoscope now represents was necessary for 
 the use of man, the photograph was first necessary for the ser- 
 vice of the stereoscope. Quarterly Review, No. 202. 
 
 THE STEREOSCOPE SIMPLIFIED. 
 
 When we look at any round object, first with one eye, and 
 then with the other, we discover that with the right eye we 
 see most of the right-hand side of the object, and with the left 
 eye most of the left-hand side. These two images are combined, 
 and we see an object which we know to be round. 
 
 This is illustrated by the Stereoscope, which consists of two 
 mirrors placed each at an angle of 45 deg., or of two semi-lenses 
 turned with their curved sides towards each other. To view 
 its phenomena two pictures are obtained by the camera on pho- . 
 tographic paper of any object in two positions, corresponding 
 with the conditions of viewing it with the two eyes. By the 
 mirrors on the lenses these dissimilar pictures are combined 
 within the eye, and the vision of an actually solid object is 
 produced from the pictures represented on a plane surface. 
 Hence the name of the instrument, which signifies Solid I see. 
 Hunt's Poetry of Science. 
 
 PHOTO-GALVANIC ENGRAVING. 
 
 That which was the chief aid of Niepce in the humblest 
 dawn of the art, viz. to transform the photographic plate into 
 
48 Things not generally Known. 
 
 a surface capable of being printed, is in the above process 
 done by the cooperation of Electricity with Photography. This 
 invention of M. Pretsch, of Vienna, differs from all other 
 attempts for the same purpose in not operating upon the pho- 
 tographic tablet itself, and by discarding the usual means of 
 varnishes and bitings-in. The process is simply this : A glass 
 tablet is coated with gelatine diluted till it forms a jelly, and 
 containing bi-chromate of potash, nitrate of silver, and iodide 
 of potassium. Upon this, when dry, is placed face downwards 
 a paper positive, through which the light, being allowed to 
 fall, leaves upon the gelatine a representation of the print. It 
 is then soaked in water; and while the parts acted upon by the 
 light are comparatively unaffected by the fluid, the remainder 
 of the jelly swells, and rising above the general surface, gives 
 a picture in relief, resembling an ordinary engraving upon 
 wood. Of this intaglio a cast is now taken in gutta-percha, 
 to which the electro process in copper being applied, a plate 
 or matrix is produced, bearing on it an exact repetition of 
 the original positive picture. All that now remains to be done 
 is to repeat the electro process ; and the result is a copper-plate 
 in the necessary relievo, of which it has been said nature fur- 
 nished the materials and science the artist, the inferior work- 
 man being only needed to roll it through the press. Quarterly 
 Review, No. 202. 
 
 SCIENCE OF THE SOAP-BUBBLE. 
 
 Few of the minor ingenuities of mankind have amused so 
 many individuals as the blowing of bubbles with soap -lather 
 from the bowl of a tobacco-pipe ; yet how few who in child- 
 hood's careless hours have thus amused themselves, have in 
 after-life become acquainted with the beautiful phenomena of 
 light which the soap-bubble will enable us to illustrate ! 
 
 Usually the bubble is formed within the bowl of a tobacco- 
 pipe, and so inflated by blowing through the stern. It is also 
 produced by introducing a capillary tube under the surface of 
 soapy water, and so raising a bubble, which may be inflated to 
 any convenient size. It is then guarded with a glass cover, to 
 prevent its bursting by currents of air, evaporation, and other 
 causes. 
 
 When the bubble is first blown, its form is elliptical, into 
 which it is drawn by its gravity being resisted ; but the instant 
 it is detached from the pipe, and allowed to float in air, it be- 
 comes a perfect sphere, since the air within presses equally in 
 all directions. There is also a strong cohesive attraction in 
 the particles of soap and water, after having been forcibly dis- 
 tended ; and as a sphere or globe possesses less surface than 
 any other figure of equal capacity, it is of all forms the best 
 
Curiosities of Science. 49 
 
 adapted to the closest approximation of the particles of soap 
 and water, which is another reason why the bubble is globular. 
 The film of which the bubble consists is inconceivably thin 
 (not exceeding the two-millionth part of an inch) ; and by the 
 evaporation from its surface, the contraction and expansion of 
 the air within, and the tendency of the soap-lather to gravitate 
 towards the lower part of the bubble, and consequently to ren- 
 der the upper part still thinner, it follows that the bubble lasts 
 but a few seconds. If, however, it were blown in a glass vessel, 
 and the latter immediately closed, it might remain for some 
 time ; Dr. Paris thus preserved a bubble for a considerable period. 
 
 Dr. Hooke, by means of the coloured rings upon the soap- 
 bubble, studied the curious subject of the colours of thiii plates, 
 and its application to explain the colours of natural bodies. 
 Various phenomena were also discovered by Newton, who thus 
 did not disdain to make a soap-bubble the object of his study. 
 The colours which are reflected from the upper surface of the 
 bubble are caused by the decomposition of the light which falls 
 upon it ; and the range of the phenomena is alike extensive and 
 beautiful.* 
 
 Newton (says Sir D. Brewster), having covered the soap- 
 bubble with a glass shade, saw its colours emerge in regular 
 order, like so many concentric rings encompassing the top of 
 it. As the bubble grew thinner by the continual subsidence 
 of the water, the rings dilated slowly, and overspread the whole 
 of it, descending to the bottom, where they vanished succes- 
 sively. When the colours had all emerged from the top, there 
 arose in the centre of the rings a small round black spot, di- 
 lating it to more than half an inch in breadth till the bubble 
 burst. Upon examining the rings between the object-glasses, 
 Newton found that when they were only eight or nine in num- 
 ber, more than forty could be seen by viewing them through a 
 prism ; and even when the plate of air seemed all over uni- 
 formly white, multitudes of rings were disclosed by the prism. 
 By means of these observations Newton was enabled to form 
 his Scale of Colours, of great value in all optical researches. 
 
 Dr. Reade has thus produced a permanent soap-bubble : 
 
 Put into a six-ounce phial two ounces of distilled water, and set 
 the phial in a vessel of water boiling on the fire. The water in the 
 phial will soon boil, and steam will issue from its mouth, expelling the 
 whole of the atmospheric air from within. Then throw in a piece of 
 soap about the size of a small pea, cork the phial, and at the same in- 
 
 * In his book on Colours, Mr. Doyle informs us that divers, if not all, essen- 
 tial oils, as also spirits of wine, when shaken, "have a good store of bubbles, 
 which appear adorned with various and lively colours." He mentions also that 
 bubbles of soap and turpentine exhibit the same colours, which " vary according 
 to the incidence of the sight and the position of the eye;" and he had seen a 
 glass-blower blow bubbles of glass which burst, and displayed " the varying 
 colours of the rainbow, which were exceedingly vivid." 
 
 B 
 
50 Things not generally Known. 
 
 staiit remove it and the vessel from the fire. Then press the cork fur- 
 ther into the neck of the phial, and cover it thickly with sealing-wax ; 
 and when the contents are cold, a perfect vacuum will be formed within 
 the bottle, much better, indeed, than can be produced by the best- 
 constructed air-pump. 
 
 To form a bubble, hold the bottle horizontally in both hands, and 
 give it a sudden upward motion, which will throw the liquid into a wave, 
 whose crest touching the upper interior surface of the phial, the tena- 
 city of the liquid will cause a film to be retained all round the phial. Next 
 place the phial on its bottom ; when the film will form a section of the 
 cylinder, being nearly but never quite horizontal. The tilm will be now 
 colourless, since it reflects all the light which falls upon it. By re- 
 maining at rest for a minute or two, minute currents of lather will de- 
 scend by their gravitating force down the inclined plane formed by the 
 film, the upper part of which thus becomes drained to the necessary 
 thinness ; and this is the part to be observed. 
 
 Several concentric segments of coloured rings are produced ; 
 the colours, beginning from the top, being as follows : 
 
 1st order : Black, white, yellow, orange, red. 
 
 2d order : Purple, blue, white, yellow, red. 
 
 %d order : Purple, blue, green, yellowish-green, white, red. 
 
 4th order : Purple, blue, green, white, red. 
 
 5th order : Greenish-blue, very pale red. 
 
 6th order : Greenish-blue, pink. 
 
 7th order : Greenish-blue, pink. 
 
 As the segments advance they get broader, while the film be- 
 comes thinner and thinner. The several orders disappear up- 
 wards as the film becomes too thin to reflect their colours, 
 until the first order alone remains, occupying the whole surface 
 of the film. Of this order the red disappears first, then the 
 orange, and lastly the yellow. The film is now divided by a 
 line into two nearly equal portions, one black and the other 
 white. This remains for some time ; at length the film becomes 
 too thin to hold together, and then vanishes. The colours are 
 not faint and imperfect, but well defined, glowing with gor- 
 geous hues, or melting into tints so exquisite as to have no 
 rival through the whole circle of the arts. We quote these de- 
 tails from Mr. Tomlinson's excellent Student's Manual of Natu- 
 ral Philosophy. 
 
 We find the following anecdote related of Newton at the above 
 period. When Sir Isaac changed his residence, and went to live in 
 St. Martin's Street, Leicester Square, his next-door neighbour was a 
 widow lady, who was much puzzled by the little she obsei'ved of the 
 habits of the philosopher. A Fellow of the Royal Society called upon 
 her one day, when, among her domestic news, she mentioned that some 
 one had come to reside in the adjoining house who, she felt certain, was 
 a poor crazy gentleman, " because," she continued, " he diverts himself 
 in the oddest way imaginable. Every morning, when the sun shines so 
 brightly that we are obliged to draw the window-blinds, he takes his 
 seat on a little stool before a tub of soapsuds, and occupies himself for 
 hours blowing soap-bubbles through a common clay -pipe, which bubbles 
 
Curiosities of Science. 51 
 
 he intently watches floating about till they burst. He is doubtless," she 
 added, ' ' now at his favourite amusement, for it is a fine day ; do come 
 and look at him." The gentleman smiled, and they went upstairs ; 
 when, after looking through the staircase- window into the adjoining 
 court-yard, he turned and said : " My dear madam, the person whom 
 you suppose to be a poor lunatic is no other than the great Sir Isaac 
 Newton studying the refraction of light upon thin plates; a phenomenon 
 which is beautifully exhibited on the surface of a common soap-bubble." 
 
 LIGHT FROM QUARTZ. 
 
 Among natural phenomena (says Sir David Brewster) illus- 
 trative of the colours of thin plates, we find none more remark- 
 able than one exhibited by the fracture of a large crystal of 
 quartz of a smoky colour, and about two and a quarter inches 
 in diameter. The surface of fracture, in place of being a face 
 or cleavage, or irregularly conchoidal, as we have sometimes 
 seen it, was filamentous, like a surface of velvet, and consisted 
 of short fibres, so small as to be incapable of reflecting light. 
 Their size could not have been greater than the third of the 
 millionth part of an inch, or one-fourth of the thinnest part of 
 the soap-bubble when it exhibits the black spot where it bursts. 
 
 CAN THE CAT SEE IN THE DARK ? 
 
 No, in all probability, says the reader; but the opposite 
 popular belief is supported by eminent naturalists. 
 
 Buffon says : " The eyes of the cat shine in the dark somewhat like 
 diamonds, which throw out during the night the light with which they 
 were in a manner impregnated during the day." 
 
 Valmont de Bamare says : " The pupil of the cat is during the night 
 still deeply imbued with the light of the day ;" and again, " the eyes of 
 the cat are during the night so imbued with light that they then appear 
 very shining and luminous." 
 
 Spallanzani says : " The eyes of cats, polecats, and several other ani- 
 mals, shine in the dark like two small tapers ;" and he adds that this 
 light is phosphoric. 
 
 Treviranus says: ' ' The eyes of the cat shine where no rays of light 
 penetrate ; and the light must in many, if not in all, cases proceed from 
 the eye itself." 
 
 Now, that the eyes of the cat do shine in the dark is to a 
 certain extent true : but we have to inquire whether by dark 
 is meant the entire absence of light ; and it will be found that 
 the solution of this question will dispose of several assertions 
 and theories which have for centuries perplexed the subject. 
 
 Dr. Karl Ludwig Esser has published in Karsten's Archives 
 the results of an experimental inquiry on the luminous appear- 
 ance of the eyes of the cat and other animals, carefully distin- 
 guishing such as evolve light from those which only reflect it. 
 Having brought a cat into a half- darkened room, he observed 
 from a certain direction that the cat's eyes, when opposite the 
 
52 Things not generally Known. 
 
 window, sparkled brilliantly; but in other positions the light 
 suddenly vanished. On causing the cat to be held so as to ex- 
 hibit the light, and then gradually darkening the room, the 
 light disappeared by the time the room was made quite dark. 
 
 In another experiment, a cat was placed opposite the win- 
 dow in a darkened room. A few rays were permitted to enter, 
 and by adjusting the light, one or both of the cat's eyes were 
 made to shine. In proportion as the pupil was dilated, the eyes 
 were brilliant. By suddenly admitting a strong glare of light 
 into the room, the pupil contracted ; and then suddenly dark- 
 ening the room, the eye exhibited a small round luminous point, 
 which enlarged as the pupil dilated. 
 
 The eyes of the cat sparkle most when the animal is in a 
 lurking position, or in a state of irritation. Indeed, the eyes 
 of all animals, as well as of man, appear brighter when in rage 
 than in a quiescent state, which Collins has commemorated in 
 his Ode on the Passions : 
 
 " Next Anger rushed, his eyes on fire." 
 
 This brilliancy is said to arise from an increased secretion of the 
 lachrymal fluid on the surface of the eye, by which the re- 
 flection of the light is increased. Dr. Esser, in places absolutely 
 dark, never discovered the slightest trace of light in the eye 
 of the cat ; and he has no doubt that in all cases where cats' 
 eyes have been seen to shine in dark places, such as a cellar, 
 light penetrated through some window or aperture, and fell 
 upon the eyes of the animal as it turned towards the opening, 
 while the observer was favourably situated to obtain a view of 
 the reflection. 
 
 To prove more clearly that this light does not depend upon 
 the will of the animal, nor upon its angry passions, experiments 
 were made upon the head of a dead cat. The sun's rays were 
 admitted through a small aperture ; and falling immediately 
 upon the eyes, caused them to glow with a beautiful green light 
 more vivid even than in the case of a living animal, on account 
 of the increased dilatation of the pupil. It was also remarked 
 that black and fox-coloured cats gave a brighter light than 
 gray and white cats. 
 
 To ascertain the cause of this luminous appearance Dr. Es- 
 ser dissected the eyes of cats, and exposed them to a small re- 
 gulated amount of light after having removed different por- 
 tions. The light was not diminished by the removal of the 
 cornea, but only changed in colour. The light still continued 
 after the iris was displaced ; but on taking away the crystalline 
 lens it greatly diminished both in intensity and colour. Dr. 
 Esser then conjectured that the tapetum in the hinder part of 
 the eye must form a spot which caused the reflection of the 
 
Curiosities of Science. 53 
 
 incident rays of light, and thus produce the shining ; and this 
 appeared more probable as the light of the eye now seemed to 
 emanate from a single spot. Having taken away the vitreous 
 humour, Dr. Esser observed that the entire want of the pigment 
 in the hinder part of the choroid coat, where the optic nerve 
 enters, formed a greenish, silver-coloured, changeable oblong 
 spot, which was not symmetrical, but surrounded the optic 
 nerve so that the greater part was above and only the smaller 
 part below it ; wherefore the greater part lay beyond the axis 
 of vision. It is this spot, therefore, that produces the reflection 
 of the incident rays of light, and beyond all doubt, according 
 to its tint, contributes to the different colouring of the light. 
 It may be as well to explain that the interior of the eye is 
 coated with a black pigment, which has the same effect as the 
 black colour given to the inner surface of optical instruments : 
 it absorbs any rays of light that may be reflected within the eye, 
 and prevents them from being thrown again upon the retina 
 so as to interfere with the distinctness of the images formed 
 upon it. The retina is very transparent ; and if the surface be- 
 hind it, instead of being of a dark colour, were capable of re- 
 flecting light, the luminous rays which had already acted on 
 the retina would be reflected back again through it, and not 
 only dazzle from excess of light, but also confuse and render 
 indistinct the images formed on the retina. Now in the case 
 of the cat this black pigment, or a portion of it, is wanting ; and 
 those parts of the eye from which it is absent, having either a 
 white or a metallic lustre, are called the tapetum. The small- 
 est portion of light entering from it is reflected as by a concave 
 mirror ; and hence it is that the eyes of animals provided with 
 this structure are luminous in a very faint light. 
 
 These experiments and observations show that the shining 
 of the eyes of the cat does not arise from a phosphoric light, 
 but only from a reflected light ; that consequently it is not an 
 effect of the will of the animal, or of violent passions ; that 
 their shining does not appear in absolute darkness ; and that 
 it cannot enable the animal to move securely in the dark. 
 
 It has been proved by experiment that there exists a set of 
 rays of light of far higher refrangibility than those seen in the 
 ordinary Newtonian spectrum. Mr. Hunt considers it probable 
 that these highly refrangible rays, although under ordinary 
 circumstances invisible to the human eye, may be adapted to 
 produce the necessary degree of excitement upon which vision 
 depends in the optic nerves of the night-roaming animals. The 
 bat, the owl, and the cat may see in the gloom of the night 
 by the aid of rays which are invisible to, or inactive on, the 
 eyes of man or those animals which require the light of day 
 for perfect vision. 
 
54> Things not generally K 
 
 nown. 
 
 THE GREAT TRUTHS OF ASTRONOMY. 
 
 THE difficulty of understanding these marvellous truths has 
 been glanced at by an old divine (see Things not generally 
 Known, p. 1) ; but the rarity of their full comprehension by 
 those unskilled in mathematical science is more powerfully 
 urged by Lord Brougham in these cogent terms : 
 
 Satisfying himself of the laws which regulate the mutual actions of 
 the planetary bodies, the mathematician can convince himself of a truth 
 yet more sublime than Newton's discovery of gravitation, though flow- 
 ing from it ; and must yield his assent to the marvellous position, that 
 all the irregularities occasioned in the system of the universe by the 
 mutual attraction of its members are periodical, and subject to an eter- 
 nal law, which prevents them from ever exceeding a stated amount, and 
 secures through all time the balanced structure of a universe composed 
 of bodies whose mighty bulk and prodigious swiftness of motion mock 
 the utmost efforts of the human imagination. All these truths are to 
 the skilful mathematician as thoroughly known, and their evidence is as 
 clear, as the simplest proposition of arithmetic to common understand- 
 ings. But how few are those who thus know and comprehend them ! 
 Of all the millions that thoroughly believe these truths, certainly not a 
 thousand individuals are capable of foil owing even any considerable por- 
 tion of the demonstrations upon which they rest ; and probably not a 
 hundred now living have ever gone through the whole steps of these 
 demonstrations. Dissertations on Subjects of Science connected with 
 Natural Theology, vol. ii. 
 
 Sir David Brewster thus impressively illustrates the same 
 subject : 
 
 Minds fitted and prepared for this species of inquiry are capable of 
 appreciating the great variety of evidence by which the truths of the 
 planetary system are established ; but thousands of individuals, and 
 many who are highly distinguished in other branches of knowledge, are 
 incapable of understanding such researches, and view with a sceptical 
 eye the great and irrefragable truths of astronomy. 
 
 That the sun is stationary in the centre of our system ; that the earth 
 moves round the sun, and round its own axis ; that the diameter of 
 the earth is 8000 miles, and that of the sun one hundred and ten times 
 as great; that the earth's orbit is 190,000,000 of miles in breadth ; and 
 that if this immense space were filled with light, it would appear only 
 like a luminous point at the nearest fixed star, are positions absolutely 
 unintelligible and incredible to all who have not carefully studied the 
 subject. To millions of our species, then, the great Book of Nature is 
 absolutely sealed ; though it is in the power of all to unfold its pages, and 
 to peruse those glowing passages which proclaim the power and wisdom 
 of its Author. 
 
Curiosities of Science. 55 
 
 ASTRONOMY AND DATES ON MONUMENTS. 
 
 Astronomy is a useful aid in discovering the Dates of ancient 
 Monuments. Thus, on the ceiling of a portico among the ruins 
 of Tentyris are the twelve signs of the Zodiac, placed according 
 to the apparent motion of the sun. According to this Zodiac, 
 the summer solstice is in Leo ; from which it is easy to com- 
 pute, by the precession of the equinoxes of 50"' 1 annually, that 
 the Zodiac of Tentyris must have been made 4000 years ago. 
 
 Mrs. Somerville relates that she once witnessed the ascer- 
 tainment of the date of a Papyrus by means of astronomy. The 
 manuscript was found in Egypt, in a mummy-case ; and its an- 
 tiquity was determined by the configuration of the heavens at 
 the time of its construction. It proved to be a horoscope of the 
 time of Ptolemy. 
 
 " THE CRYSTAL VAULT OF HEAVEN." 
 
 This poetic designation dates back as far as the early period 
 of Anaximenes ; but the first clearly defined signification of the 
 idea on which the term is based occurs in Empedocles. This 
 philosopher regarded the heaven of the fixed stars as a solid 
 mass, formed from the ether which had been rendered crystal- 
 line by the action of fire. 
 
 In the Middle Ages, the fathers of the Church believed the 
 firmament to consist of from seven to ten glassy strata, incas- 
 ing each other like the different coatings of an onion. This 
 supposition still keeps its ground in some of the monasteries of 
 southern Europe, where Humboldt was greatly surprised to 
 hear a venerable prelate express an opinion in reference to the 
 fall of aerolites at Aigle, that the bodies we called meteoric 
 stones with vitrified crusts were not portions of the fallen stone 
 itself, but simply fragments of the crystal vault shattered by it 
 in its fall. 
 
 Empedocles maintained that the fixed stars were riveted to 
 the crystal heavens ; but that the planets were free and uncon- 
 strained. It is difficult to conceive how, according to Plato in 
 the TimcBus, the fixed stars, riveted as they are to solid spheres, 
 could rotate independently. 
 
 Among the ancient views, it may be mentioned that the 
 equal distance at which the stars remained, while the whole vault 
 of heaven seemed to move from east to west, had led to the 
 idea of a firmament and a solid crystal sphere, in which An- 
 axirnenes (who was probably not much later than Pythagoras) 
 had conjectured that the stars were riveted like nails. 
 
 MUSIC OF THE SPHERES. 
 
 The Pythagoreans, in applying their theory of numbers to 
 
56 Things not generally Known. 
 
 the geometrical consideration of the five regular bodies, to the 
 musical intervals of tone which determine a word and form 
 different kinds of sounds, extended it even to the system of 
 the universe itself; supposing that the moving, and, as it were, 
 vibrating planets, exciting sound-waves, must produce a spheral 
 music, according to the harmonic relations of their intervals of 
 space. " This music," they add, " would be perceived by the 
 human ear, if it was not rendered insensible by extreme famili- 
 arity, as it is perpetual, and men are accustomed to it from 
 childhood." 
 
 The Pythagoreans affirm, in order to justify the reality of the tones 
 
 ng take 
 where there is an alternation of sound and silence. The inaudibility of 
 
 , 
 produced by the revolution of the spheres, that hearing takes place only 
 
 the spheral music is also accounted for by its overpowering the senses. 
 Aristotle himself calls the Pythagorean tone-myth pleasing and ingeni- 
 ous, but untrue. 
 
 Plato attempted to illustrate the tones of the universe in an 
 agreeable picture, by attributing to each of the planetary spheres 
 a syren, who, supported by the stern daughters of Necessity, 
 the three Fates, maintain the eternal revolution of the world's 
 axis. Mention is constantly made of the harmony of the 
 spheres, though generally reproachfully, throughout the writ- 
 ings of Christian antiquity and the Middle Ages, from Basil the 
 Great to Thomas Aquinas and Petrus Alliacus. 
 
 At the close of the sixteenth century, Kepler revived these 
 musical ideas, and sought to trace out the analogies between 
 the relations of tone and the distances of the planets ; and Tycho 
 Brahe was of opinion that the revolving conical bodies were 
 capable of vibrating the celestial air (what we now call "resist- 
 ing medium") so as to produce tones. Yet Kepler, although he 
 had talked of Venus and the Earth sounding sharp in aphelion 
 and flat in perihelion, and the highest tone of Jupiter and that 
 of Venus coinciding in flat accord, positively declared there 
 to be " no such things as sounds among the heavenly bodies, 
 nor is their motion eo turbulent as to elicit noise from the attri- 
 tion of the celestial air." (See Things not generally Knoivn^. 44.) 
 
 " MORE WORLDS THAN ONE." 
 
 Although this opinion was maintained incidentally by va- 
 rious writers both on astronomy * and natural religion, yet M. 
 
 * The original idea is even attributed to Copernicus. M. Blundevile, in his 
 Treatise on Cosmogrnphy , 1594, has the following passage, perhaps the most dis- 
 tinct recognition of authority in our language: " How prooue (prove) you that 
 there is but one world ? By the authentic of Aristotle, who saieth that if there 
 were any other world out of this, then the earth of that world would mooue 
 (move) towards the centre of this world," &c. 
 
 Sir Isaac Newton, in a conversation with Conduitt, said he took "all the 
 planets to be composed of the same matter with the earth, viz. earth, water, aud 
 stone, but variously concocted." 
 
Curiosities of Science. 
 
 Fontenelle was the first individual who wrote a treatise on the 
 Plurality of Worlds, which appeared in 1685, the year before the 
 publication of Newton's Principia. Fontenelle's work consists 
 of five chapters: 1. The earth is a planet which turns round 
 its axis, and also round the sun. 2. The moon is a habitable 
 world. 3. Particulars concerning the world in the moon, and 
 that the other planets are also inhabited. 4. Particulars of the 
 worlds of Venus, Mercury, Mars, Jupiter, and Saturn. 5. The 
 fixed stars are as many suns, each of which illuminates a world. 
 In a future edition, 1719, Fontenelle added, 6. New thoughts 
 which confirm those in the preceding conversations, and the 
 latest discoveries which have been made in the heavens. The 
 next work on the subject was the Theory of the Universe, or 
 Conjectures concerning the Celestial Bodies and their Inhabitants, 
 1698, by Christian Huygens, the contemporary of Newton. 
 
 The doctrine is maintained by almost all the distinguished 
 astronomers and writers who have flourished since the true 
 figure of the earth was determined. Giordano Bruna of Nola, 
 Kepler, and Tycho Brahe, believed in it; and Cardinal Cusa 
 and Bruno, before the discovery of binary systems among the 
 stars, believed also that the stars were inhabited. Sir Isaac 
 Newton likewise adopted the belief; and Dr. Bentley, Master 
 of Trinity College, Cambridge, in his eighth sermon on the Con- 
 futation of Atheism from the origin and frame of the world, 
 has ably maintained the same doctrine. In our own day we 
 may number among its supporters the distinguished names of 
 the Marquis de la Place, Sir William and Sir John Herschel, 
 Dr. Chalmers, Isaac Taylor, and M. Arago. Dr. Chalmers main- 
 tains the doctrine in his Astronomical Discourses, which one 
 Alexander Maxwell (who did not believe in the grand truths of 
 astronomy) attempted to controvert, in 1820, in a chapter of a 
 volume entitled Plurality of Worlds. 
 
 Next appeared Of a Plurality of Worlds, attributed to the 
 Rev. Dr.Whewell, Master of Trinity College, Cambridge; urging 
 the theological not less than the scientific reasons for believing 
 in the old tradition of a single world, and maintaining that " the 
 earth is really the largest planetary body in the solar system, 
 its domestic hearth, and the only world in the universe." " I 
 do not pretend," says Dr. Whewell, " to disprove the plurality of 
 worlds ; but I ask in vain for any argument which makes the 
 doctrine probable." " It is too remote from knowledge to be 
 either proved or disproved." Sir David Brewster has replied 
 to Dr. Whewell's Essay, in More Worlds than One, the Creed 
 of the Philosopher and the Hope of the Christian, emphatically 
 maintaining that analogy strongly countenances the idea of all 
 the solar planets, if not all worlds in the universe, being peo- 
 pled with creatures not dissimilar in being and nature to the 
 
58 Things not generally Known. 
 
 inhabitants of the earth. This view is supported in Scientific 
 Certainties of Planetary Life, by T. C. Simon, who well treats one 
 point of the argument that mere distance of the planets from 
 the central sun does not determine the condition as to light 
 and heat, but that the density of the ethereal medium enters 
 largely into the calculation. Mr. Simon's general conclusion is, 
 that " neither on account of deficient or excessive heat, nor with 
 regard to the density of the materials, nor with regard to the force 
 of gravity on the surface, is there the slightest pretext for sup- 
 posing that all the planets of oar system are not inhabited by 
 intellectual creatures with animal bodies like ourselves, moral 
 beings, who know and love their great Maker, and who wait, 
 like the rest of His creation, upon His providence and upon His 
 care. " One of the leading points of Dr. WhewelFs Essay is, that 
 we should not elevate the conjectures of analogy into the rank 
 of scientific certainties; and that " the force of all the presump- 
 tions drawn from physical reasoning for the opinion of planets 
 and stars being either inhabited or uninhabited is so small, that 
 the belief of all thoughtful persons on this subject will be deter- 
 mined by moral, metaphysical, and theological considerations." 
 
 WORLDS TO COME ABODES OF THE BLEST. 
 
 Sir David Brewster, in his eloquent advocacy of the doc- 
 trine of " more worlds than one," thus argues for their peo- 
 pling : 
 
 Man, in his future state of existence, is to consist, as at present, 
 of a spiritual nature residing in a corporeal frame. He must live, there- 
 fore, upon a material planet, subject to all the laws of matter, and per- 
 forming functions for which a material body is indispensable. We must 
 consequently find for the race of Adam, if not races that may have 
 preceded him, a material home upon which they may reside, or by 
 which they may travel, by means unknown to us, to other localities in 
 the universe. At the present hour, the inhabitants of the earth are nearly 
 a thousand millions ; and by whatever process we may compute the 
 numbers that have existed before the present generation, and estimate 
 those that are yet to inherit the earth, we shall obtain a population 
 which the habitable parts of our globe could not possibly accommodate. 
 If there is not room, then, on our earth for the millions of millions 
 of beings who have lived and died upon its surface, and who may yet 
 live and die during the period fixed for its occupation by man, we can 
 scarcely doubt that their future abode must be on some of the primary 
 or secondary planets of the solar system, whose inhabitants have ceased 
 to exist like those on the earth, or upon planets in our own or in other 
 systems which have been in a state of preparation, as our earth was, 
 for the advent of intellectual life. 
 
 " GAUGING THE HEAVENS." 
 
 Sir William Herschel, in 1785, conceived the happy idea 
 of counting the number of stars which passed at different 
 
Curiosities of Science. 59 
 
 heights and in various directions over the field of view, of fif- 
 teen minutes in diameter, of his twenty-feet reflecting tele- 
 scope. The field of view each time embraced only 8a smooth of 
 the whole heavens ; and it would therefore require, according 
 to Struve, eighty-three years to gauge the whole sphere by a 
 similar process. 
 
 VELOCITY OF THE SOLAR SYSTEM. 
 
 M. E. W. G. Struve gives as the splendid result of the 
 united studies of MM. Argelander, 0. Struve, and Peters, 
 grounded on observations made at the three Russian observa- 
 tories of Dorpat, Abo, and Pulkowa, "that the velocity of the 
 motion of the solar system in space is such that the sun, with 
 all the bodies which depend upon it, advances annually to- 
 wards the constellation Hercules* 1*623 times the radius of the 
 earth's orbit, or 33,550,000 geographical miles. The possible 
 error of this last number amounts to 1,733,000 geographical 
 miles, or to a seventh of the whole value. We may, then, wager 
 400,000 to 1 that the sun has a proper progressive motion, and 
 1 to 1 that it is comprised between the limits of thirty-eight 
 and twenty-nine millions of geographical miles." 
 
 That is, taking 95,000,000 of English miles as the mean radius of 
 the Earth's orbit, we have 95 + 1 '623= 354-185 millions of miles; and 
 consequently, 
 
 English Miles. 
 The velocity of the Solar System . 154,185,000 in the year. 
 
 .... 422,424 in a day. 
 
 ,, .... 17,601 in an hour. 
 
 ,, ,, .... 293 in a minute. 
 
 .... 57 in a second. 
 
 The Sun and all his planets, primary and secondary, are therefore now 
 in rapid motion round an invisible focus. To that now dark and mys- 
 terious centre, from which no ray, however feeble, shines, we may in 
 another age point our telescopes, detecting perchance the great lu- 
 minary which controls our system and bounds its path : into that vast 
 orbit man, during the whole cycle of his race, may never be allowed to 
 round. North-British Review, No. 16. 
 
 NATURE OF THE SUN. 
 
 M. Arago has found, by experiments with the polariscope, 
 that the light of gaseous bodies is natural light when it issues 
 from the burning surface ; although this circumstance does not 
 prevent its subsequent complete polarisation, if subjected to 
 
 * Sir William Herschel ascertained that our solar system is advancing to- 
 wards the constellation Hercules, or more accurately to a point in space whose 
 right ascension is 245 52' 80", and north polar distance 40 22'; and that the 
 quantity of this motion is such, that to an astronomer placed in Sirius, our sun 
 would appear to describe an arc of little more than a second every year. North- 
 British Review, No. 3. 
 
60 Thinqs not qenerallii Known. 
 
 i7 y ./ 
 
 suitable reflections or refractions. Hence we obtain a most 
 simple method of discovering the nature of the sun at a distance 
 of forty millions of leagues. For if the light emanating from 
 the margin of the sun, arid radiating from the solar substance 
 at an acute angle, reach us without having experienced any 
 sensible reflections or refractions in its passage to the earth, 
 and if it offer traces of polarisation, the sun must be a solid or 
 a liquid body. But if, on the contrary, the light emanating 
 from the sun's margin give no indications of polarisation, the 
 incandescent portion of the sun must be gaseous. It is by means 
 of such a methodical sequence of observations that we may 
 acquire exact ideas regarding the physical constitution of the 
 sun. Note to Humboldt's Cosmos, vol. iii. 
 
 STRUCTURE OF THE LUMINOUS DISC OF THE SUN. 
 
 The extraordinary structure of the fully luminous Disc of 
 the Sun, as seen through Sir James South's great achromatic, 
 in a drawing made by Mr. Grwilt, resembles compressed curd, 
 or white almond -soap, or a mass of asbestos fibres, lying in 
 a quaquaversus direction, and compressed into a solid mass. 
 There can be no illusion in this phenomenon ; it is seen by 
 every person with good vision, and on every part of the sun's 
 luminous surface or envelope, which is thus shown to be not 
 & flame, but a soft solid or thick fluid, maintained in an incan- 
 descent state by subjacent heat, capable of being disturbed by 
 differences of temperature, and broken up as we see it when 
 the sun is covered with spots or openings in the luminous 
 matter. North- British Review, No. 16. 
 
 Copernicus named the sun the lantern of the world (lucerna irnindi}; 
 and Theon of Smyrna called it the heart of the universe. The mass of 
 the sun is, according to Encke's calculation of Sabine's pendulum for- 
 mula, 359,551 times that of the earth, or 355,499 times that of the earth 
 and moon together ; whence the density of the sun is only about (or 
 more accurately 0'252) that of the earth. The volume of the sun is 
 600 times greater, and its mass, according to Galle, 738 times greater, 
 than that of all the planets combined. It may assist the mind in con- 
 ceiving a sensuous image of the magnitude of the sun, if we remember 
 that if the solar sphere were entirely hollowed out, and the earth placed 
 in its centre, there would still be room enough for the moon to describe 
 its orbit, even if the radius of the latter were increased 160,000 geo- 
 graphical miles. A railway-engine, moving at the rate of thirty miles 
 an hour, would require 360 years to travel from the earth to the sun. 
 The diameter of the sun is rather more than one hundred and eleven 
 times the diameter of the earth. Therefore the volume or bulk of the 
 sun must be nearly one million four hundred thousand times that of the 
 earth. Lastly, if all the bodies composing the solar system were formed 
 into one globe, it would be only about the five-hundredth part of the 
 size of the sun. 
 
Curiosities of Science. 61 
 
 GREAT SIZE OF THE SUN ON THE HORIZON EXPLAINED. 
 
 The dilated size (generally) of the Sun or Moon, when seen 
 near the horizon, beyond what they appear to have when high 
 up in the sky, has nothing to do with refraction. It is an illu- 
 sion of the judgment, arising from the terrestrial objects inter- 
 posed, or placed in close comparison with them. In that situ- 
 ation we view and judge of them as we do of terrestrial objects 
 in detail, and with an acquired attention to parts. Aloft we 
 have no association to guide us, and their insulation in the 
 expanse of the sky leads us rather to undervalue than to over- 
 rate their apparent magnitudes. Actual measurement with a 
 proper instrument corrects our error, without, however, dis- 
 pelling our illusion. By this we learn that the sun, when just 
 on the horizon, subtends at our eyes almost exactly the same, 
 and the moon a materially less, angle than when seen at a 
 greater altitude in the sky, owing to its greater distance from 
 us in the former situation as compared with the latter. Sir 
 John HerscheVs Outlines. 
 
 TRANSLATORY MOTION OF THE SUN. 
 
 This phenomenon is the progressive motion of the centre 
 of gravity of the whole solar system in universal space. Its 
 velocity, according to Bessel, is probably four millions of miles 
 daily, in a relative velocity to that of 61 Cygni of at least 
 3,336,000 miles, or more than double the velocity of the revolu- 
 tion of the earth in her orbit round the sun. This change of the 
 entire solar system would remain unknown to us, if the ad- 
 mirable exactness of our astronomical instruments of measure- 
 ment, and the advancement recently made in the art of ob- 
 serving, did not cause our progress towards remote stars to be 
 perceptible, like an approximation to the objects of a distant 
 shore in apparent motion. The proper motion of the star 61 
 Cygni, for instance, is so considerable, that it has amounted 
 to a whole degree in the course of 700 years. Huntboldt's Cos- 
 mos, vol. i. 
 
 THE SUN'S LIGHT COMPARED WITH TERRESTRIAL LIGHTS. 
 
 Mr. Ponton has by means of a simple monochromatic pho- 
 tometer ascertained that a small surface, illuminated by mean 
 solar light, is 444 times brighter than when it is illuminated by 
 a moderator lamp, and 1560 times brighter than when it is 
 illuminated by a wax-candle (short six in the Ib.) the artifi- 
 cial light being in both instances placed at two inches' distance 
 from the illuminated surface. And three electric lights, each 
 
62 Things not generally Known. 
 
 equal to 520 wax-candles, will render a small surface as bright 
 as when it is illuminated by mean sunshine. 
 
 It is thence inferred, that a stratum occupying the entire 
 surface of the sphere of which the earth's distance from the 
 sun is the radius, and consisting of three layers of flame, each 
 10 ' 00 th of an inch in thickness, each possessing a brightness 
 equal to that of such an electric light, and all three embraced 
 within a thickness of -^th of an inch, would give an amount 
 of illumination equal in quantity and intensity to that of the 
 sun at the distance of 95 millions of miles from his centre. 
 
 And were such a stratum transferred to the surface of the 
 sun, where it would occupy 46,275 times less area, its thick- 
 ness would be increased to 94 feet, and it would embrace 
 138,825 layers of flame, equal in brightness to the electric light ; 
 but the same effect might be produced by a stratum about 
 nine miles in thickness, embracing 72 millions of layers, each 
 having only a brightness equal to that of a wax-candle.* 
 
 ACTINIC POWER OF THE SUN. 
 
 Mr. J. J. Waterston, in 1857, made at Bombay some ex- 
 periments on the photographic power of the sun's direct light, 
 to obtain data in an inquiry as to the possibility of measuring 
 the diameter of the sun to a very minute fraction of a second, 
 by combining photography with the principle of the electric 
 telegraph ; the first to measure the element space, the latter 
 the element time. The result is that about 20 ^ 00 th of a se- 
 cond is sufficient exposure to the direct light of the sun to 
 obtain a distinct mark on a sensitive collodion plate, when 
 developed by the usual processes ; and the duration of the 
 sun's full action on any one point is about ^Wth of a second. 
 
 M. Schatt, a young painter of Berlin, after 1500 experi- 
 ments, succeeded in establishing a scale of all the shades of 
 black which the action of the sun produces on photographic 
 paper ; so that by comparing the shade obtained at any given 
 moment on a certain paper with that indicated on the scale, 
 the exact force of the sun's light may be determined. 
 
 HEATING POWER OF THE SUN. 
 
 All moving power has its origin in the rays of the sun. 
 While Stephenson's iron tubular railway-bridge over the Menai 
 Straits, 400 feet long, bends but half an inch under the hea- 
 viest pressure of a train, it will bend up an inch and a half 
 from its usual horizontal line when the sun shines on it for 
 
 * See M. Arago's researches upon this interesting subject, in Things not gener- 
 ally Known, p. 4. 
 
Curiosities of Science. 63 
 
 some hours. The Bunker-Hill monument, near Boston, U.S., 
 is higher in the evening than in the morning of a sunny day ; 
 the little sunbeams enter the pores of the stone like so many 
 wedges, lifting it up. 
 
 In winter, the Earth is nearer the Sun by about $ than in 
 summer ; but the rays strike the northern hemisphere more 
 obliquely in winter than the other half year. 
 
 M. Pouillet has estimated, with singular ingenuity, from a 
 series of observations made by himself, that the whole quantity 
 of heat which the Earth receives annually from the Sun is 
 such as would be sufficient to melt a stratum of ice covering 
 the entire globe forty-six feet deep. 
 
 By the action of the sun's rays upon the earth, vegetables, 
 animals, and man, are in their turn supported ; the rays be- 
 come likewise, as it were, a store of heat, and " the sources of 
 those great deposits of dynamical efficiency which are laid up 
 for human use in our coal strata" (Herschel). 
 
 A remarkable instance of the power of the sun's rays is re- 
 corded at Stonehouse Point, Devon, in the year 1828. To lay 
 the foundation of a sea-wall the workmen had to descend in a 
 diving-bell, which was fitted with convex glasses in the upper 
 part, by which, on several occasions in clear weather, the sun's 
 rays were so concentrated as to burn the labourers' clothes 
 when opposed to the focal point, and this when the bell was 
 twenty- five feet under the surface of the water ! 
 
 CAUSE OF DAEK COLOUR OF THE SKIN. 
 
 Darkness of complexion has been attributed to the sun's 
 power from the age of Solomon to this day, "Look not upon 
 me, because I am black, because the sun hath looked upon 
 me :" and there cannot be a doubt that, to a certain degree, 
 the opinion is well founded. The invisible rays in the solar 
 beams, which change vegetable colour, and have been em- 
 ployed with such remarkable effect in the daguerreotype, act 
 upon every substance on which they fall, producing myste- 
 rious and wonderful changes in their molecular state, man not 
 excepted. Mrs. Somerville. 
 
 EXTREME SOLAR HEAT. 
 
 The fluctuation in the sun's direct heating power amounts 
 to Ts tn > which is too considerable a fraction of the whole in- 
 
 tensity not to aggravate in a serious degree the sufferings of 
 those who are exposed to it in thirsty deserts without shelter. 
 The amount of these sufferings, in the interior of Australia for 
 instance, are of the most frightful kind, and would seem far to 
 exceed what have ever been undergone by travellers in the 
 
64 Thinys not generally Known. 
 
 northern deserts of Africa. Thus Captain Sturt, in his account 
 of his Australian exploration, says : " The ground was almost 
 a molten surface ; and if a match accidentally fell upon it, it 
 immediately ignited." Sir John Herschel has observed the 
 temperature of the surface soil in South Africa as high as 159 
 Fahrenheit. An ordinary lucifer-match does not ignite when 
 simply pressed upon a smooth surface at 212 ; but in the act 
 of withdrawing it it takes fire, and the slightest friction upon 
 such a surface of course ignites it. 
 
 HOW DR. WOLLASTON COMPARED THE LIGHT OF THE SUN AND 
 THE FIXED STARS. 
 
 In order to compare the Light of the Sun with that of a 
 Star, Dr. Wollaston took as an intermediate object of compa- 
 rison the light of a candle reflected from a bulb about a quarter 
 of an inch in diameter, filled with quicksilver ; and seen by one 
 eye through a lens of two inches focus, at the same time that 
 the star on the sun's image, placed at a proper distance, was 
 viewed by the other eye through a telescope. The mean of 
 various trials seemed to show that the light of Sirius is equal 
 to that of the sun seen in a glass bulb -^th of an inch in dia- 
 meter, at the distance of 210 feet ; or that they are in the 
 proportion of one to ten thousand millions : but as nearly one 
 half of this light is lost by reflection, the real proportion be- 
 tween the light from Sirius and the sun is not greater than 
 that of one to twenty thousand millions. 
 
 " THE SUN DARKENED." 
 
 Humboldt selects the following example from historical 
 records as to the occurrence of a sudden decrease in the light 
 of the Sun : 
 
 A.D. 33, the year of the Crucifixion. "Now from the sixth hour 
 there was darkness over all the land till the ninth hour" (St. Matthew 
 xxvii. 45). According to St. Luke (xxiii. 45), " the sun was darkened.' 1 
 In order to explain and corroborate these narrations, Eusebius brings 
 forward an eclipse of the sun in the 2J2d Olympiad, which had been 
 noticed by the chronicler Phlegon of Tralles (Ideler, Handluch der 
 Mathem. Chronologic, Bd. ii. p. 417). Wurn, however, has shown that 
 the eclipse which occurred during this Olympiad, and was visible over 
 the whole of Asia Minor, must have happened as early as the 24th of 
 November 29 A.D. The day of the Crucifixion corresponded with the 
 Jewish Passover (Ideler, Bd. i. pp. 515-520), on the 14th of the month 
 Nisan, and the Passover was always celebrated at the time of the full 
 moon. The sun cannot therefore have been darkened for three hours by 
 the moon. The Jesuit Scheiner thinks the decrease in the light might 
 be ascribed to the occurrence of large sun-spots. 
 
 THE SUN AND TERRESTRIAL MAGNETISM. 
 
 The important influence exerted by the Sun's body, as a 
 
S Curiosities of Science. 65 
 
 mass, upon Terrestrial Magnetism, is confirmed by Sabine in 
 the ingenious observation, that the period at which the inten- 
 sity of the magnetic force is greatest, and the direction of the 
 needle most near to the vertical line, falls in both hemispheres 
 between the months of October and February ; that is to say, 
 precisely at the time when the earth is nearest to the sun, and 
 moves in its orbit with the greatest velocity. 
 
 IS THE HEAT OF THE SUN DECREASING ? 
 
 The Heat of the Sun is dissipated and lost by radiation, and 
 must be progressively diminished unless its thermal energy be 
 supplied. According to the measurements of M. Pouillet, the 
 quantity of heat given out by the sun in a year is equal to that 
 which would be produced by the combustion of a stratum of 
 coal seventeen miles in thickness ; and if the sun*s capacity for 
 heat be assumed equal to that of water, and the heat be sup- 
 posed drawn uniformly from its entire mass, its temperature 
 would thereby undergo a diminution of 20 '4 Fahr. annually. 
 On the other hand, there is a vast store of force in our system 
 capable of conversion into heat. If, as is indicated by the 
 small density of the sun, and by other circumstances, that 
 body has not yet reached the condition of incompressibility, 
 we have in the future approximation of its parts a fund of 
 heat, probably quite large enough to supply the wants of the 
 human family to the end of its sojourn here. It has been cal- 
 culated that an amount of condensation which would diminish 
 the diameter of the sun by only the ten-thousandth part, would 
 suffice to restore the heat emitted in 2000 years. 
 
 UNIVERSAL SUN-DIAL. 
 
 Mr. Sharp, of Dublin, exhibited to the British Association 
 in 1849 a Dial, consisting of a cylinder set to the day of the 
 month, and then elevated to the latitude. A thin plane of 
 metal, in the direction of its axis, is then turned by a milled 
 head below it till the shadow is a minimum, when a dial on 
 the top shows the hours by one hand, and the minutes by an- 
 other, to the precision of about three minutes. 
 
 LENGTH OF DAYS AT THE POLES. 
 
 During the summer, in the northern hemisphere y places 
 near the North Pole are in continual sunlight the sun never 
 sets to them ; while during that time places near the South 
 Pole never see the sun. When it is summer in the southern 
 hemisphere, and the sun shines on the South Pole without 
 setting, the North Pole is entirely deprived of his light. In- 
 deed, at the Poles there is bit one day and one night ; for the 
 
 p 
 
66 Things not generally Known. 
 
 sun shines for six months together on one Pole, and the other 
 six months on the other Pole. 
 
 HOW THE DISTANCE OF THE SUN IS ASCERTAINED BY THE 
 YARD-MEASURE. 
 
 Professor Airy, in his Six Lectures on Astronomy, gives a 
 masterly analysis of a problem of considerable intricacy, viz. 
 the determination of the parallax of the sun, and consequently 
 of his distance, by observations of the transit of Venus, the con- 
 necting link between measures upon the earth's surface and the 
 dimensions of our system. The further step of investigating 
 the parallax, and consequently the distance of the fixed stars 
 (where that is practicable), is also elucidated; and the author, 
 with evident satisfaction, thus sums up the several steps : 
 
 By means of a yard-measure, a base-line in a survey was measured ; 
 from this, by the tria.ngulations and computations of a survey, an arc of 
 meridian on the earth was measured ; from this, with proper observa- 
 tions with the zenith sector, the surveys being also repeated on different 
 parts of the earth, the earth's form and dimensions were ascertained ; 
 from these, and a previous independent knowledge of the proportions of 
 the distances of the earth and other planets from the sun, with observa- 
 tions of the transit of Venus, the sun's distance is determined ; and from 
 this, with observations leading to the parallax of the stars, the distance 
 of the stars is determined. And every step in the process can be dis- 
 tinctly referred to its basis, that is, the yard-measure. 
 
 HOW THE TIDES ARE PRODUCED BY THE SUN AND MOON. 
 
 Each of these bodies excites, by its attraction upon the 
 waters of the sea, two gigantic waves, which flow in the same 
 direction round the world as the attracting bodies themselves 
 apparently do. The two waves of the moon, on account of 
 her greater nearness, are about 3| times as large as those ex- 
 cited by the sun. One of these waves has its crest on the 
 quarter of the earth^s surface which is turned towards the 
 moon ; the other is at the opposite side. Both these quarters 
 possess the flow of the tide, while the regions which lie be- 
 tween have the ebb. Although in the open sea the height of 
 the tide amounts to only about three feet, and only in certain 
 narrow channels, where the moving water is squeezed together, 
 rises to thirty feet, the might of the phenomenon is never- 
 theless manifest from the calculation of Bessel, according to 
 which a quarter of the earth covered by the sea possesses dur- 
 ing the flow of the tide about 25,000 cubic miles of water 
 more than during the ebb ; and that, therefore, such a mass of 
 water must in 6 hours flow from one quarter of the earth to 
 the other. Professor Helmhottz. 
 
Curiosities of Science. 67 
 
 SPOTS ON THE SUN. 
 
 Sir John Herschel describes these phenomena, when watched 
 from day to day, or even from hour to hour, as appearing to en- 
 large or contract, to change their forms, and at length disappear 
 altogether, or to break out anew in parts of the surface where 
 none were before. Occasionally they break up or divide into 
 two or more. The scale on which their movements takes place 
 is immense. A single second of angular measure, as seen from 
 the earth, corresponds on the sun's disc to 461 miles ; and a 
 circle of this diameter (containing therefore nearly 167,000 
 square miles) is the least space which can be distinctly dis- 
 cerned on the sun as a visible area. Spots have been observed, 
 however, whose linear diameter has been upwards of 45,000 
 miles ; and even, if some records are to be trusted, of very much 
 greater extent. That such a spot should close up in six weeks 
 time (for they seldom last much longer), its borders must ap- 
 proach at the rate of more than 1000 miles a-day. 
 
 The same astronomer saw at the Cape of Good Hope, on the 
 29th March 1837, a solar spot occupying an area of near five 
 square minutes, equal to 3,780,000,000 square miles. "The 
 black centre of the spot of May 25th, 1837 (not the tenth part 
 of the preceding one), would have allowed the globe of our 
 earth to drop through it, leaving a thousand miles clear of 
 .contact on all sides of that tremendous gulf." For such an 
 amount of disturbance on the sun's atmosphere, what reason 
 can be assigned ? 
 
 The Rev. Mr. Dawes has invented a peculiar contrivance, 
 by means of which he has been enabled to scrutinise, under 
 high magnifying power, minute portions of the solar disc. He 
 places a metallic screen, pierced with a very small hole, in the 
 focus of the telescope, where the image of the sun is formed. 
 A small portion only of the image is thus allowed to pass 
 through, so that it may be examined by the eye-piece without 
 inconveniencing the observer by heat or glare. By this ar- 
 rangement, Mr. Dawes has observed peculiarities in the con- 
 stitution of the sun's surface which are discernible in no other 
 way. 
 
 Before these observations, the dark spots seen on the sun's 
 surface were supposed to be portions of the solid body of the 
 sun, laid bare to our view by those immense fluctuations in 
 the luminous regions of its atmosphere to which it appears to 
 be subject. It now appears that these dark portions are only 
 an additional and inferior stratum of a very feebly luminous 
 or illuminated portion of the sun's atmosphere. This again in 
 its turn Mr. Dawes has frequently seen pierced with a smaller 
 and usually much more rounded aperture, which would seem 
 
68 Things not generally Known. 
 
 at last to afford a view of the real solar surface of most intense 
 blackness. 
 
 M. Schwabe, of Dessau, has discovered that the abundance 
 or paucity of spots displayed by the sun's surface is subject to 
 a law of periodicity. This has been confirmed by M. Wolf, of 
 Berne, who shows that the period of these changes, from mini- 
 mum to minimum, is 11 years and 1 1-hundredths of a year, 
 being exactly at the rate of nine periods per century, the last 
 year of each century being a year of minimum. It is strongly 
 corroborative of the correctness both of M. Wolf's period and 
 also of the periodicity itself, that of all the instances of the 
 appearance of spots on the sun recorded in history, even before 
 the invention of the telescope, or of remarkable deficiencies in 
 the sun's light, of which there are great numbers, only two are 
 found to deviate as much as two years from M. Wolf's epochs. 
 Sir William Herschel observed that the presence or absence of 
 spots had an influence on the temperature of the seasons ; his 
 observations have been fully confirmed by M. Wolf. And, from 
 an examination of the chronicles of Zurich from A.D. 1000 to 
 A.D. 1800, he has come to the conclusion "that years rich in 
 solar spots are in general drier and more fruitful than those of 
 an opposite character ; while the latter are wetter and more 
 stormy than the former." 
 
 The most extraordinary fact, however, in connection with 
 the spots on the sun's surface, is the singular coincidence of 
 their periods with those great disturbances in the magnetic 
 system of the earth to which the epithet of " magnetic storms" 
 has been affixed. 
 
 These disturbances, during which, the magnetic needle is greatly 
 and universally ao-itated (not in a particular limited locality, but at one 
 and the same instant of time over whole continents^ or even over the 
 whole earth), are found, so far as obsei-vation has hitherto extended, 
 to maintain a parallel, both in respect of their frequency of occui-rence 
 and intensity in successive years, with the abundance and magnitude 
 of the spots'in the same years, too close to be regarded as fortuitous. 
 The coincidence of the epochs of maxima and minima in the two series 
 of phenomena amounts, indeed, to identity; a fact evidently of most 
 important significance, but which neither astronomical nor magnetic 
 science is yet sufficiently advanced to interpret. Herschel 's Outlines. 
 
 The signification and connection of the above varying phe- 
 nomena (Humboldt maintains) can never be manifested in their 
 entire importance until an uninterrupted series of representa- 
 tions of the sun's spots can be obtained by the aid of me- 
 chanical clock-work and photographic apparatus, as the result 
 of prolonged observations during the many months of serene 
 weather enjoyed in a tropical climate. 
 
 M. Schwabe has thus distinguished himself as an indefatigable ob- 
 server of the sun's spots, for his researches received the Royal Astrono- 
 
Curiosities of Science. 69 
 
 mical Society's Medal in 1857. " For thirty years," said the President 
 at the presentation, "never has the sun exhibited his disc above the 
 horizon of Dessau without being confronted by Schwabe's imperturbable 
 telescope ; and that appears to have happened on an average about 
 300 days a-year. So, supposing that he had observed but once a-day, 
 he has made 9000 observations, in the course of which he discovered 
 about 4700 groups. This is, I believe, an instance of devoted persist- 
 'ence unsurpassed in the annals of astronomy. The energy of one 
 man has revealed a phenomenon that had eluded the suspicion of astro- 
 nomers for 200 years." 
 
 HAS THE MOON AN ATMOSPHERE ? 
 
 The Moon possesses neither Sea nor Atmosphere of appreci- 
 able extent. Still, as a negative, in such case, is relative only 
 to the capabilities of the instruments employed, the search for 
 the indications of a lunar atmosphere has been renewed with 
 fresh augmentation of telescopic power. Of such indications, 
 the most delicate, perhaps, are those afforded by the occulta- 
 tion of a planet by the moon. The occultation of Jupiter, 
 which took place on January 2, 1857, was observed with this 
 reference, and is said to have exhibited no hesitation, or change 
 of form or brightness, such as would be produced by the refrac- 
 tion or absorption of an atmosphere. As respects the sea, if 
 water existed on the moon's surface, the sun's light reflected 
 from it should be completely polarised at a certain elongation 
 of the moon from the sun ; and no traces of such light have 
 been observed. 
 
 MM. Baer and Maedler conclude that the moon is not en- 
 tirely without an atmosphere, but, owing to the smallness of 
 her mass, she is incapacitated from holding an extensive cover- 
 ing of gas; and they add, "it is possible that this weak en- 
 velope may sometimes, through local causes, in some measure 
 dim or condense itself." But if any atmosphere exists on our 
 satellite, it must be, as Laplace says, more attenuated than 
 what is termed a vacuum in an air-pump. 
 
 Mr. Hopkins thinks that if there be any lunar atmosphere, 
 it must be very rare in comparison with the terrestrial atmo- 
 sphere, and inappreciable to the kind of observation by which 
 it has been tested ; yet the absence of any refraction of the 
 light of the stars during occultation is a very refined test. Mr. 
 Nasmyth observes that " the sudden disappearance of the stars 
 behind the moon, without any change or diminution of her 
 brilliancy, is one of the most beautiful phenomena that can be 
 witnessed." 
 
 Sir John Herschel observes : The fact of the moon turning 
 always the same face towards the earth is, in all probability, 
 the result of an elongation of its figure in the direction of a 
 line joining the centres of both the bodies, acting conjointly 
 
70 Things not generally Known. 
 
 with a non- coincidence of its centre of gravity with its centre 
 of symmetry. 
 
 If to this we add the supposition that the substance of the 
 moon is not homogeneous, ani that some considerable pre- 
 ponderance of weight is placed excentrically in it, it will be 
 easily apprehended that the portion of its surface nearer to that 
 heavier portion of its solid content, under all the circumstances 
 of the moon's rotation, will permanently occupy the situation 
 most remote from the earth. 
 
 In what regards its assumption of a definite level, air obeys precisely 
 the same hydrostatical laws as water. The lunar atmosphere would 
 rest upon the lunar ocean, and form in its basin a lake of air, whose 
 upper portions at an altitude such as we are now contemplating would 
 be of excessive tenuity, especially should the provision of air be less 
 abundant in proportion than our own. It by no means follows, then, 
 from the absence of visible indications of water or air on this side of the 
 moon, that the other is equally destitute of them, and equally unfitted 
 for maintaining- animal or vegetable life. Some slight approach to such 
 a state of things actually obtains on the earth itself. Nearly all the 
 land is collected in one of its hemispheres, and much the larger portion 
 of the sea in the opposite There is evidently an excess of heavy mate- 
 rial vertically beneath the middle of the Pacific ; while not very remote 
 from the point of the globe diametrically opposite rises the great table- 
 land of India and the Himalaj^a chain, on the summits of which the air 
 has not more than a third of the density it has on the sea-level, and 
 from which animated existence is for ever excluded. Herschel s Out- 
 5th edit. 
 
 LIGHT OF THE MOON. 
 
 The actual illumination of the lunar surface is not much 
 superior to that of weathered sandstone-rock in full sunshine. 
 Sir John Herschel has frequently compared the moon setting 
 behind the gray perpendicular faQade of the Table Mountain 
 at the Cape of Good Hope, illuminated by the sun just risen 
 from the opposite quarter of the horizon, when it has been 
 scarcely distinguishable in brightness from the rock in contact 
 with it. The sun and moon being nearly at equal altitudes, 
 and the atmosphere perfectly free from cloud or vapour, its 
 effect is alike on both luminaries. 
 
 HEAT OF MOONLIGHT. 
 
 M. Zantedeschi has proved, by a long series of experiments 
 in the Botanic Gardens at Venice, Florence, and Padua, that, 
 contrary to the general opinion, the diffused rays of moonlight 
 have an influence upon the organs of plants, as the Sensitive 
 Plant and the Desmodium gyrans. The influence was feeble 
 compared with that of the sun ; but the action is left beyond 
 further question. 
 
 Melloni has proved that the rays of the Moon give out a 
 

 Curiosities of Science. 71 
 
 slight degree of Heat (see Things not generally Known, p. 7) ; 
 and Professor Piazzi Smyth, from a point of the Peak of Tene- 
 riffe 8840 feet above the sea-level, has found distinctly per- 
 ceptible the heat radiated from the moon, which has been so 
 often sought for in vain in a lower region. 
 
 SCENERY OF THE MOON. 
 
 By means of the telescope, mountain-peaks are distinguished 
 in the ash-gray light of the larger spots and isolated brightly- 
 shining points of the moon, even when the disc is already 
 more than half illuminated. Lambert and Schroter have shown 
 that the extremely variable intensity of the ash-gray light of 
 the moon depends upon the greater or less degree of reflection 
 of the sunlight which falls upon the earth, according as it is 
 reflected from continuous continental masses, full of sandy de- 
 serts, grassy steppes, tropical forests, and barren rocky ground, 
 or from large ocean surfaces. Lambert made the remarkable 
 observation (14th of February 1774) of a change of the ash- 
 coloured moonlight into an olive-green colour bordering upon 
 yellow. " The moon, which then stood vertically over the 
 Atlantic Ocean, received upon its right side the green terres- 
 trial light which is reflected towards her when the sky is clear 
 by the forest districts of South America. " 
 
 Plutarch says distinctly, in his remarkable work On the Face 
 in the Moon, that we may suppose the spots to be partly deep 
 chasms and valleys, partly mountain -peaks, which cast long 
 shadows, like Mount Athos, whose shadow reaches Lemnos. 
 The spots cover about two-fifths of the whole disc. In a clear 
 atmosphere, and under favourable circumstances in the position 
 of the moon, some of the spots are visible to the naked eye ; 
 as the edge of the Apennines, the dark elevated plain Grimal- 
 dus, the enclosed Mare Crisium, and Tycho, crowded round with 
 numerous mountain ridges and craters. 
 
 Professor Alexander remarks, that a map of the eastern 
 hemisphere, taken with the Bay of Bengal in the centre, would 
 bear a striking resemblance to the face of the moon presented 
 to us. The dark portions of the moon he considers to be con- 
 tinental elevations, as shown by measuring the average height 
 of mountains above the dark and the light portions of the 
 moon. 
 
 The surface of the moon can be as distinctly seen by a good 
 telescope magnifying 1000 times, as it would be if not more 
 than 250 miles distant. 
 
 LIFE IN THE MOON. 
 
 A circle of one second in diameter, as seen from the earth, 
 on the surface of the moon contains about a square mile. 
 
72 Things not generally Known. 
 
 Telescopes, therefore, must be greatly improved before we 
 could expect to see signs of inhabitants, as manifested by edi- 
 fices or changes on the surface of the soil. It should, however, 
 be observed, that owing to the small density of the materials of 
 the moon, and the comparatively feeble gravitation of bodies 
 on her surface, muscular force would there go six times as far 
 in overcoming the weight of materials as on the earth. Owing 
 to the want of air, however, it seems impossible that any form 
 of life analogous to those on earth can subsist there. No 
 appearance indicating vegetation, or the slightest variation of 
 surface which can in our opinion fairly be ascribed to change of 
 season, can any where be discerned. Sir John Herschel's Out- 
 lines. 
 
 THE MOON SEEN THROUGH LORD ROSSE's TELESCOPE. 
 
 In 1846, the Rev. Dr. Scoresby had the gratification of ob- 
 serving the Moon through the stupendous telescope constructed 
 by Lord Rosse at Parsonstown. It appeared like a globe of 
 molten silver, and every object to the extent of 100 yards was 
 quite visible. Edifices, therefore, of the size of York Minster, 
 or even of the ruins of Whitby Abbey, might be easily per- 
 ceived, if they had existed. But there was no appearance of 
 any thing of that nature ; neither was there any indication of 
 the existence of water, or of an atmosphere. There were a 
 great number of extinct volcanoes, several miles in breadth ; 
 through one of them there was a line of continuance about 150 
 miles in length, which ran in a straight direction, like a rail- 
 way. The general appearance, however, was like one vast ruin 
 of nature ; and many of the pieces of rock driven out of the 
 volcanoes appeared to lie at various distances. 
 
 MOUNTAINS IN THE MOON. 
 
 By the aid of telescopes, we discern irregularities in the sur- 
 face of the moon which can be no other than mountains arid 
 valleys. for this plain reason, that we see the shadows cast 
 by the former in the exact proportion as to length which they 
 ought to have when we take into account the inclinations of 
 the sun's rays to that part of the moon's surface on which they 
 stand. From micrometrical measurements of the lengths of the 
 shadows of the more conspicuous mountains, Messrs. Baer and 
 Maedler have given a list of heights for no less than 1095 lunar 
 mountains, among which occur all degrees of elevation up to 
 22,823 British feet, or about 1400 feet higher than Chimbo- 
 razo in the Andes. 
 
 If Chimborazo were as high in proportion to the earth's 
 diameter as a mountain in the moon known by the name of 
 
Curiosities of Science. 73 
 
 Newton is to the moon's diameter, its peak would be more 
 than sixteen miles high. 
 
 Avago calls to mind, that with a 6000-fold magnifying 
 power, which nevertheless could not be applied to the moon 
 with proportionate results, the mountains upon the moon 
 would appear to us just as Mont Blanc does to the naked eye 
 when seen from the Lake of Geneva. 
 
 We sometimes observe more than half the surface of the 
 moon, the eastern and northern edges being more visible at 
 one time, and the western or southern at another. By means 
 of this libration we are enabled to see the annular mountain 
 Malapert (which occasionally conceals the moon's south pole), 
 the arctic landscape round the crater of Gioja, and the large 
 gray plane near Endymion, which conceals in superficial extent 
 the mare vaporum. 
 
 Three-sevenths of the moon are entirely concealed from our 
 observation ; and must always remain so, unless some new and 
 unexpected disturbing causes come into play. Humboldt. 
 
 The first object to which Galileo directed his telescope was tho 
 mountainous parts of the moon, when he showed how their summits 
 might be measured : he found in the moon some circular districts sur- 
 rounded on all sides by mountains similar to the form of Bohemia. 
 The measurements of the mountains were made by the method of the 
 tangents of the solar ray. Galileo, as Helvetius did still later, measured 
 the distance of the summit of the mountains from the boundary of the 
 illuminated portion at the moment when the mountain summit was 
 first struck by the solar ray. Humboldt found no observations of the 
 lengths of the slwdows of the mountains : the summits were " much 
 higher than the mountains on our earth " The comparison is remark- 
 able, since, according to Biccioli, very exaggerated ideas of the height 
 of our mo;.:;tains were then entertained. Galileo like all other observers 
 up to the close of the eighteenth century, believed in the existence of 
 many seas and of a lunar atmosphere. 
 
 THE MOON AND THE WEATHER. 
 
 The only influence of the Moon on the Weather of which 
 we have any decisive evidence is the tendency to disappearance 
 of clouds under the full moon, which Sir John Herschel refers 
 to its heat being much more readily absorbed in traversing 
 transparent media than direct solar heat, and being extinguished 
 in the upper regions of our atmosphere, never reaches the sur- 
 face of the atmosphere at all. 
 
 THE MOON'S ATTRACTION. 
 
 Mr. G. P. Bond of Cambridge, by some investigations to 
 ascertain whether the Attraction of the Moon has any effect 
 upon the motion of a pendulum, and consequently upon the 
 rate of a clock, has found the last to be changed to the amount 
 
74 Things not generally Known. 
 
 of TWO of a second daily. At the equator the moon's attrac- 
 tion changes the weight of a body only ?000 oo6 of the whole ; 
 yet this force is sufficient to produce the vast phenomena of 
 the tides ! 
 
 It is no slight evidence of the importance of analysis, that 
 Laplace's perfect theory of tides has enabled us in our astro- 
 nomical ephemerides to predict the height of spring-tides at 
 the periods of new and full moon, and thus put the inhabitants 
 of the sea on their guard against the increased danger attending 
 the lunar revolutions. 
 
 MEASURING THE EARTH BY THE MOON. 
 
 As the form of the Earth exerts a powerful influence on the 
 motion of other cosmical bodies, and especially on that of its 
 neighbouring satellite, a more perfect knowledge of the motion 
 of the latter will enable us reciprocally to draw an inference 
 regarding the figure of the earth. Thus, as Laplace ably re- 
 marks : " an astronomer, without leaving his observatory, may, 
 by a comparison of lunar theory with true observations, not 
 only be enabled to determine the form and size of the earth, 
 but also its distance from the sun and moon ; results that other- 
 wise could only be arrived at by long and arduous expeditions 
 to the most remote parts of both hemispheres." The compres- 
 sion which may be inferred from lunar inequalities affords an 
 advantage not yielded by individual measurements of degrees 
 or experiments with the pendulum, since it gives a mean 
 amount which is referable to the whole planet. Humboldt's 
 Cosmos, vol. i. 
 
 The distance of the moon from the earth is about 240,000 
 miles ; and if a railway-carriage were to travel at the rate of 
 1000 miles a-day, it would be eight months in reaching the 
 moon. But that is nothing compared with the length of time 
 it would occupy a locomotive to reach the sun from the earth : 
 if travelling at the rate of 1000 miles a-day, it would require 
 260 years to reach it. 
 
 CAUSE OF ECLIPSES. 
 
 As the Moon is at a very moderate distance from us (astro- 
 nomically speaking), and is in fact our nearest neighbour, while 
 the sun and stars are in comparison immensely beyond it, it 
 must of necessity happen that at one time or other it must 
 pass over, and occult or eclipse, every star or planet within its 
 zone, and, as seen from the surface of the earth, even some- 
 what beyond it. Nor is the sun itself exempt from being thus 
 hidden whenever any part of the moon's disc, in this her tor- 
 tuous course, comes to overlap any part of the space occupied 
 
Curiosities of Science. 75 
 
 in the heavens by that luminary. On these occasions is ex- 
 hibited the most striking and impressive of all the occasional 
 phenomena of astronomy, an Eclipse of the Sun, in which a 
 greater or less portion, or even in some conjunctures the whole 
 of its disc, is obscured, and, as it were, obliterated, by the su* 
 perposition of that of the moon, which appears upon it as a 
 circularly-terminated black spot, producing a temporary dimi- 
 nution of daylight, or even nocturnal darkness, so that the 
 stars appear as if at midnight. Sir John Herschel's Outlines. 
 
 VAST NUMBERS IN THE UNIVERSE. 
 
 The number of telescopic stars in the Milky Way uninter- 
 rupted by any nebulae is estimated at 18,000,000. To com- 
 pare this number with something analogous, Humboldt calls 
 attention to the fact, that there are not in the whole heavens 
 more than about 8000 stars, between the first and the sixth 
 magnitudes, visible to the naked eye. The barren astonish- 
 ment excited by numbers and dimensions in space when not 
 considered with reference to applications engaging the mental 
 and perceptive powers of man, is awakened in both extremes 
 of the universe in the celestial bodies as in the minutest 
 animalcules. A cubic inch of the polishing slate of Bilin con- 
 tains, according to Ehrenberg, 40,000 millions of the siliceous 
 shells of Galionellse. 
 
 FOR WHAT PURPOSE WERE THE STARS CREATED 1 
 
 Surely not (says Sir John Herschel) to illuminate our nights, 
 which an additional moon of the thousandth part of the size of 
 our own would do much better ; nor to sparkle as a pageant 
 void of meaning and reality, and bewilder us among vain con- 
 jectures. Useful, it is true, they are to man as points of exact 
 and permanent reference ; but he must have studied astronomy 
 to little purpose, who can suppose man to be the only object of 
 his Creator's care, or who does not see in the vast and wonder- 
 ful apparatus around us provision for other races of animated 
 beings. The planets derive their light from the sun ; but that 
 cannot be the case with the stars. These doubtless, then, are 
 themselves suns ; and may perhaps, each in its sphere, be the 
 presiding centre round which other planets, or bodies of which 
 we can form no conception from any analogy offered by our 
 own system, are circulating.* 
 
 NUMBER OF STARS. 
 
 Various estimates have been hazarded on the Number of 
 Stars throughout the whole heavens visible to us by the aid of 
 
 * This eloquent advocacy of the doctrine of " More Worlds than One" (refer- 
 red to at p. 51) is from the author's valuable Outlines of Astronomy. 
 
76 Things not generally Known. 
 
 our colossal telescopes. Struve assumes for Herschel's 20-feet 
 reflector, that a magnifying power of 180 would give 5,800,000 
 for the number of stars lying within the zones extending 30 
 on either side of the equator, and 20,374,000 for the whole 
 heavens. Sir William Herschel conjectured that 18,000,000 of 
 stars in the Milky Way might be seen by his still more powerful 
 40-feet reflecting telescope. Humboldt's Cosmos, vol. iii. 
 
 The assumption that the extent of the starry firmament is 
 literally infinite has been made by Dr. Gibers the basis of a 
 conclusion that the celestial spaces are in some slight degree 
 deficient in transparency ; so that all beyond a certain distance 
 is and must remain for ever unseen, the geometrical progres- 
 sion of the extinction of light far outrunning the effect of any 
 conceivable increase in the power of our telescopes. Were it 
 not so, it is argued that every part of the celestial concave 
 ought to shine with the brightness of the solar disc, since no 
 visual ray could be so directed as not, in some point or other of 
 its infinite length, to encounter such a disc. Edinburgh Re- 
 view, Jan. 1848. 
 
 STAKS THAT HAVE DISAPPEARED. 
 
 Notwithstanding the great accuracy of the catalogued po- 
 sitions of telescopic fixed stars and of modern star-maps, the 
 certainty of conviction that a star in the heavens has ac- 
 tually disappeared since a certain epoch can only be arrived at 
 with great caution. Errors of actual observation, of reduction, 
 and of the press, often disfigure the very best catalogues. The 
 disappearance of a heavenly body from the place in which it 
 had been before distinctly seen, may be the result of its own 
 motion as much as of any such diminution of its photometric 
 process as would render the waves of light too weak to excite 
 our organs of sight. What we no longer see, is not necessarily 
 annihilated. The idea of destruction or combustion, as ap- 
 plied to disappearing stars, belongs to the age of Tycho Brahe. 
 Even Pliny makes it a question. The apparent eternal cosmical 
 alternation of existence and destruction is not annihilation ; 
 it is merely the transition of matter into new forms, into com- 
 binations which are subject to new processes. Dark cosmical 
 bodies may by a renewed process of light again become lu- 
 minous. Humboldt's Cosmos, vol. iii. 
 
 THE POLE-STAB FOUR THOUSAND YEARS AGO. 
 
 Sir John Herschel, in his Outlines of Astronomy, thus shows 
 the changes in the celestial pole in 4000 years : 
 
 At the date of the erection of the Pyramid of Gizeh, which precedes 
 the present epoch by nearly 4000 years, the longitudes of all the stars 
 
Curiosities of Science. 77 
 
 were less by 55 45' than at present. Calculating from this datum 
 the place of the pole of the heavens among the stars, it will be found 
 to fall near a Draconis ; its distance from that star being 3 44' 25". 
 This being the roost conspicuous star in the immediate neighbourhood, 
 was therefore the Pole Star of that epoch. The latitude of Gizeh being 
 just 30 north, and consequently the altitude of the North Pole there 
 also 30, it follows that the star in question must have had at its 
 lowest culmination at Gizeh an altitude of 25 15' 35". Now it is a 
 remarkable fact, that of the nine pyramids still existing at Gizeh, six 
 (including all the largest) have the narrow passages by which alone they 
 can be entered (all which open out on the northern faces of their re- 
 spective pyramids) inclined to the horizon downwards at angles the 
 mean of which is 26 47'. At the bottom of every one of these passages, 
 therefore, the Pole Star must have been visible at its lower culmination ; 
 a circumstance which can hardly be supposed to have been uninten- 
 tional, and was doubtless connected (perhaps superstitiously) with the 
 astronomical observations of that star, of whose proximity to the pole 
 at the epoch of the erection of these wonderful structures we are thus 
 furnished with a monumental record of the most imperishable nature. 
 
 THE PLEIADES. 
 
 The Pleiades prove that, several thousand years ago even 
 as now, stars of the seventh magnitude were invisible to the 
 naked eye of average visual power. The group consists of 
 seven stars, of which six only, of the third, fourth, and fifth 
 magnitudes, could be readily distinguished. Of these Ovid 
 says (Fast. iv. 170) : 
 
 " Quae septem dici, sex tamen esse solent." 
 Aratus states there were only six stars visible in the Pleiades. 
 
 One of the daughters of Atlas, Merope, the only one who 
 was wedded to a mortal, was said to have veiled herself for 
 very shame and to have disappeared. This is probably the 
 star of the seventh magnitude, which we call Celaene ; for Hip- 
 parchus, in. his commentary on Aratus, observes that on clear 
 moonless nights seven stars may actually be seen. 
 
 The Pleiades were doubtless known to the rudest nations 
 from the earliest times ; they are also called the mariner's stars. 
 The name is from TrAeiv (plein), ' to sail.' The navigation of 
 the Mediterranean lasted from May to the beginning of Novem- 
 ber, from the early rising to the early setting of the Pleiades. 
 In how many beautiful effusions of poetry and sentiment has 
 " the Lost Pleiad" been deplored ! and, to descend to more fa- 
 miliar illustration of this group, the " Seven Stars," the sailors' 
 favourites, and a frequent river-side public-house sign, may be 
 traced to the Pleiades. 
 
 CHANGE OF COLOUR IN THE STARS. 
 
 The scintillation or twinkling of the stars is accompanied 
 by variations of colour, which have been remarked from a very 
 early age. M. Arago states, upon the authority of M. Babinet, 
 
78 Things not generally Known. 
 
 that the name of Barakesch, given by the Arabians to Sirius, 
 signifies th star of a thousand colours ; and Tycho Brahe, Kep- 
 ler, and others, attest to similar change of colour in twinkling. 
 Even soon after the invention of the telescope, Simon Marius 
 remarked that by removing the eye-piece of the telescope the 
 images of the stars exhibited rapid fluctuations of bright- 
 ness and colour. In 1814 Nicholson applied to the telescope 
 a smart vibration, which caused the image of the star to be 
 transformed into a curved line of light returning into itself, 
 and diversified by several colours ; each colour occupied about 
 a third of the whole length of the curve, and by applying ten 
 vibrations in a second, the light of Sirius in that time passed 
 through thirty changes of colour. Hence the stars in general 
 shine only by a portion of their light, the effect of twinkling 
 being to diminish their brightness. "This phenomenon M. Arago 
 explains by the principle of the interference of light. 
 
 Ptolemy is said to have noted Sirius as a red star, though 
 it is now white. Sirius twinkles with red and blue light, and 
 Ptolemy's eyes, like those of several other persons, may have 
 been more sensitive to the red than to the blue rays. Sir David 
 Brewster's More Worlds than One, p. 235. 
 
 Some of the double stars are of very different and dissimilar 
 colours ; and to the revolving planetary bodies which apparently 
 circulate around them, a day lightened by a red light is suc- 
 ceeded by, not a night, but a day equally brilliant, though illu- 
 minated only by a green light. 
 
 DISTANCE OF THE NEAREST FIXED STAE FROM THE EARTH. 
 
 Sir John Herschel wrote in 1833 : " What is the distance 
 of the nearest fixed star? What is the scale on which our 
 visible firmament is constructed ? And what proportion do its 
 dimensions bear to those of our own immediate system ? To this, 
 however, astronomy has hitherto proved unable to supply an 
 answer. All we know on this subject is negative." To these 
 questions, however, an answer can now be given. Slight 
 changes of position of some of the stars, called parallax, have 
 been distinctly observed and measured ; and among these stars 
 No. 61 Cygni of Flamstead's catalogue has a parallax of 5", and 
 that of a Centauri has a proper motion of 4" per annum. 
 
 The same astronomer states that each second of parallax in- 
 dicates a distance of 20 billions of miles, or 3J years' journey of 
 light. Now the light sent to us by the sun, as compared with 
 that sent by Sirius and a Centauri, is a,bout 22 thousand mil- 
 lions to 1. " Hence, from the parallax assigned above to that 
 star, it is easy to conclude that its intrinsic splendour, as com- 
 pared with that of our sun at equal distances, is 2*3247, that 
 of the sun being unity. The light of Sirius is four times that 
 
Curiosities of Science. 79 
 
 of a Centauri, and its parallax only 0'15". This, in effect, as- 
 cribes to it an intrinsic splendour equal to 96'63 times that of 
 a Centauri, and therefore 224' 7 times that of our sun." 
 
 This is justly regarded as one of the most brilliant triumphs 
 of astronomical science, for the delicacy of the investigation is 
 almost inconceivable ; yet the reasoning is as unimpeachable 
 as the demonstration of a theorem of Euclid. 
 
 LIGHT OF A STAE SIXTEENFOLD THAT OF THE SUN. 
 
 The bright star in the constellation of the Lyre, termed 
 Vega, is the brightest in the northern hemisphere ; and the com- 
 bined researches of Struve, father and son, have found that 
 the distance of this star from the earth is no less than 130 bil- 
 lions of miles ! Light travelling at the rate of 192 thousand 
 miles in a second consequently occupies twenty-one years in 
 passing from this star to the earth. Now it has been found, 
 by comparing the light of Vega with the light of the sun, that 
 if the latter were removed to the distance of 130 billions of 
 miles, his apparent brightness would not amount to more than 
 the sixteenth part of the apparent brightness of Vega. We 
 are therefore warranted in concluding that the light of Vega 
 is equal to that of sixteen suns. 
 
 DIVERSITIES OF THE PLANETS. 
 
 In illustration of the great diversity of the physical peculi- 
 arities and probable condition of the planets, Sir John Herschel 
 describes the intensity of solar radiation as nearly seven times 
 greater on Mercury than on the earth, and on Uranus 330 times 
 less ; the proportion between the two extremes being that of 
 upwards of 2000 to 1. Let any one figure to himself, (adds 
 Sir John,) the condition of our globe were the sun to be sep- 
 tupled, to say nothing of the greater ratio ; or were it dimi- 
 nished to a seventh, or to a 300th of its actual power ! 
 Again, the intensity of gravity, or its efficacy in counter- 
 acting muscular power and repressing animal activity, on Ju- 
 piter is nearly two-and-a-half times that on the earth ; on 
 Mars not more than one-half; on the moon one-sixth; and on 
 the smaller planets probably not more than one-twentieth ; 
 giving a scale of which the extremes are in the proportion of 
 sixty to one. Lastly, the density of Saturn hardly exceeds one- 
 eighth of the mean density of the earth, so that it must consist 
 of materials not much heavier than cork. 
 
 Jupiter is eleven times, Saturn ten times, Uranus five times, and 
 Neptune nearly six times, the diameter of our earth. 
 
 These four bodies revolve in space at such distances from the sun, 
 that if it were possible to start thence for each in succession, and to travel 
 at the railway speed of 33 miles per hour, the traveller would reach 
 
80 Things not generally Known. 
 
 Jupiter in . . 1712 years 
 
 Saturn .... 3113 
 
 Uranus . . . 6226 ,, 
 
 Neptune . . . 9685 
 
 If, thei'efore, a person had commenced his journey at the period of the 
 Christian era, he would now have to travel nearly 1300 years before he 
 would arrive at the planet Saturn ; more than 4300 years before he 
 would reach Uranus ; and no less than 7800 years before he could reach 
 the orbit of Neptune. 
 
 Yet the light which comes to us from these remote confines of the 
 solar system first issued from the sun, and is then reflected from the 
 surface of the planet. When the telescope is turned towards Neptune, 
 the observer's eye sees the object by means of light that issued from 
 the sun eight hours before, and which since then has passed nearly 
 twice through that vast space which railway speed would require al- 
 most a century of centuries to accomplish. Bouvier's Familiar Agtro- 
 
 GEAND RESULTS OF THE DISCOVERY OF JUPITER'S 
 SATELLITES. ' 
 
 This discovery, one of the first fruits of the invention of the 
 telescope, and of Galileo's early and happy idea of directing its 
 newly-found powers to the examination of the heavens, forms 
 one of the most memorable epochs in the history of astronomy. 
 The first astronomical solution of the great problem of the 
 longitude, practically the most important for the interests of 
 mankind which has ever been brought under the dominion of 
 strict scientific principles, dates immediately from this disco- 
 very. The final and conclusive establishment of the Coperni- 
 can system of astronomy may also be considered as referable 
 to the discovery and study of this exquisite miniature system, 
 in which the laws of the planetary motions, as ascertained by 
 Kepler, and specially that which connects their periods and 
 distances, were specially traced, and found to be satisfactorily 
 maintained. And (as if to accumulate historical interest on 
 this point) it is to the observation of the eclipses of Jupiter's 
 satellites that we owe the grand discovery of the aberration of 
 light, and the consequent determination of the enormous velo- 
 city of that wonderful element 192,000 miles per second. Mr. 
 Dawes, in 1849, first noticed the existence of round, well-de- 
 fined, bright spots on the belts of Jupiter. They vary in situa- 
 tion and number, as many as ten having been seen on one 
 occasion. As the belts of Jupiter have been ascribed to tho 
 existence of currents analogous to our trade-winds, causing tho 
 body of Jupiter to be visible through his cloudy atmosphere, Sir 
 John Herschel conjectures that those bright spots may possibly 
 be insulated masses of clouds of local origin, similar to the 
 cumuli which sometimes cap ascending columns of vapour in 
 our atmosphere. 
 
 It would require nearly 1300 globes of the size of our earth 
 
Curiosities of Science. 81 
 
 to make one of the bulk of Jupiter. A railway-engine travel- 
 ling at the rate of thirty- three miles an hour would travel 
 round the earth in a month, but would require more than 
 eleven months to perform a journey round Jupiter. 
 
 WAS SATURN'S RING KNOWN TO THE ANCIENTS ? 
 
 In Maurice's Indian Antiquities is an engraving of Sani, 
 the Saturn of the Hindoos, taken from an image in a very an- 
 cient pagoda, which represents the deity encompassed by a ring 
 formed of two serpents. Hence it is inferred that the ancients 
 were acquainted with the existence of the ring of Saturn. 
 
 Arago mentions the remarkable fact of the ring and fourth 
 satellite of Saturn having been seen by Sir W. Herschel with 
 his smaller telescope by the naked eye, without any eye- piece. 
 
 The first or innermost of Saturn's satellites is nearer to the 
 central body than any other of the secondary planets. Its dis- 
 tance from the centre of Saturn is 80,088 miles ; from the sur- 
 face of the planet 47,480 miles ; and from the outmost edge of 
 the ring only 4916 miles. The traveller may form to himself 
 an estimate of the smallness of this amount by remembering 
 the statement of the well-known navigator, Captain Beechey, 
 that he had in three years passed over 72,800 miles. 
 
 According to very recent observations, Saturn's ring is di- 
 vided into three separate rings, which, from the calculations 
 of Mr. Bond, an American astronomer, must be fluid. He is 
 of opinion that the number of rings is continually changing, 
 and that their maximum number, in the normal condition of 
 the mass, does not exceed twenty. Mr. Bond likewise maintains 
 that the power which sustains the centre of gravity of the ring 
 is not in the planet itself, but in its satellites ; and the satellites, 
 though constantly disturbing the ring, actually sustain it in the 
 very act of perturbation. M. Otto Struve and Mr. Bond have 
 lately studied with the great Munich telescope, at the observa- 
 tory of Pulkowa, the third ring of Saturn, which Mr. Lassell and 
 Mr. Bond discovered to \& fluid. They saw distinctly the dark 
 interval between this fluid ring and the two old ones, and even 
 measured its dimensions ; and they perceived at its inner mar- 
 gin an edge feebly illuminated, which they thought might bo 
 the commencement of a fourth ring. These astronomers are of 
 opinion, that the fluid ring is not of very recent formation, and 
 that it is not subject to rapid change; and they have come to 
 the extraordinary conclusion, that the inner border of the ring 
 has, since the time of Huygens, been gradually approaching to 
 the body of Saturn, and that we may expect, sooner or later, 
 perhaps in sortie dozen of years, to see the rings united with the 
 body of the planet. But this theory is by other observers pro- 
 nounced untenable. 
 
82 Things not generally Known. 
 
 TEMPERATURE OF THE PLANET MERCURY. 
 
 Mercury being so much nearer to the Sun than the Earth, 
 he receives, it is supposed, seven times more heat than the 
 earth. Mrs. Somerville says: "On Mercury, the mean heat 
 arising from the intensity of the sun's rays must be above that 
 of boiling quicksilver, and water would boil even at the poles." 
 But he may be provided with an atmosphere so constituted as 
 to absorb or reflect a great portion of the superabundant heat ; 
 so that his inhabitants (if he have any) may enjoy a climate as 
 temperate as any on our globe. 
 
 SPECULATIONS ON VESTA AND PALLAS. 
 
 The most remarkable peculiarities of these ultra-zodiacal 
 planets, according to Sir John Herschel, must lie in tin's condi- 
 tion of their state : a man place i on one of them would spring 
 with ease sixty feet high, and sustain no greater shock in his 
 descent than he does on the earth from leaping a yard. On 
 such planets, giants might exist ; and those enormous animals 
 which on the earth require the buoyant power of water to coun- 
 teract their weight, might there be denizens of the land. But 
 of such speculations there is no end. 
 
 IS THE PLANET MARS INHABITED ? 
 
 The opponents of the doctrine of the Plurality of Worlds 
 allow that a greater probability exists of Mars being inhabited 
 than in the case of any other planet. His diameter is 4100 
 miles ; and his surface exhibits spots of different hues, the 
 seas, according to Sir John Herschel, being green, and the laud 
 red. " The variety in the spots," says this astronomer, " may 
 arise from the planet not being destitute of atmosphere and 
 cloud ; and what adds greatly to the probability of this, is the 
 appearance of brilliant white spots at its poles, which have 
 been conjectured, with some probability, to be snow, as they 
 disappear when they have been long exposed to the sun, and are 
 greatest when emerging from the long night of their polar 
 winter, the snow-line then extending to about six degrees from 
 the pole." " The length of the day," says Sir David Brew- 
 ster, " is almost exactly twenty-four hours, the same as that 
 of the earth. Continents and oceans and green savannahs 
 have been observed upon Mars, and the snow of his polar re- 
 gions has been seen to disappear with the heat of summer. " 
 We actually see the clouds floating in the atmosphei-e of Mars, 
 and there is the appearance of land and water on his disc. 
 In a sketch of this planet, as seen in the pure atmosphere of 
 Calcutta by Mr. Grant, it appears, to use his words, " actually 
 
Curiosities of Science. 83 
 
 as a little world," and as the earth would appear at a distance, 
 with its seas and continents of different shades. As the dia- 
 meter of Mars is only about one half that of our earth, the 
 weight of bodies will be about one half what it would be if they 
 were placed upon our globe. 
 
 DISCOVERY OF THE PLANET NEPTUNE. 
 
 This noble discovery marked in a signal manner the matu- 
 rity of astronomical science. The proof, or at least the urgent 
 presumption, of the existence of such a planet, as a means 
 of accounting (by its attraction) for certain small irregularities 
 observed in the motions of Uranus, was afforded almost simul- 
 taneously by the independent researches of two geometers, 
 Mr. Adams of Cambridge, and M. Leverrier of Paris, who were 
 enabled from theory alone to calculate whereabouts it ought 
 to appear in the heavens, if visible, the places thus indepen- 
 dently calculated agreeing surprisingly. Within a single de- 
 gree of the place assigned by M. Leverrier's calculations, and 
 by him communicated to Dr. Galle of the Royal Observatory 
 at Berlin, it was actually found by that astronomer on the very 
 first night after the receipt of that communication, on turning 
 a telescope on the spot, and comparing the stars in its imme- 
 diate neighbourhood with those previously laid down in one of 
 the zodiacal charts. This remarkable verification of an indica- 
 tion so extraordinary took place on the 23d of September 1846.* 
 Sir John Herschels Outlines. 
 
 Neptune revolves round the sun in about 172 years, at a 
 mean distance of thirty, that of Uranus being nineteen, and 
 that of the earth one : and by its discovery the solar system 
 has been extended one thousand millions of miles beyond its 
 former limit. 
 
 Neptune is suspected to have a ring, but the suspicion has 
 not been confirmed. It has been demonstrated by the obser- 
 vations of Mr. Lassell, M. Otto Struve, and Mr. Bond, to be 
 attended by at least one satellite. 
 
 One of the most curious facts brought to light by the dis- 
 covery of Neptune, is the failure of Bode's law to give an ap- 
 proximation to its distance from the sun ; a striking exempli- 
 fication of the danger of trusting to the universal applicability 
 of an empirical law. After standing the severe test which led 
 
 * Professor Challis, of the Cambridge Observatory, directing the Northum- 
 berland telescope of that, institution to the place assigned by Mr. Adams's calcu- 
 lations and its vicinity on the 4th and 12 th of August 1846, saw the planet on 
 both those days, and noted its place (among those of other stars) for re-observa- 
 tion. He, however, postponed the comparison of the places observed, and not 
 possessing Dr. Bremiker's chart (which would at once have indicated the pre- 
 sence of an unmapped star), remained in ignorance of the planet's existence as a 
 visible object till the announcement of such by Dr. Galle. 
 
84- Things not generally Known. 
 
 to the discovery of the asteroids, it seemed almost contrary to 
 the laws of probability that the discovery of another member 
 of the planetary system should prove its failure as an univer- 
 sal rule. 
 
 MAGNITUDE OF COMETS. 
 
 Although Comets have a smaller mass than any other cos- 
 mical bodies being, according to our present knowledge, pro- 
 bably not equal to 3o ' 00 th part of the earth's mass yet they 
 occupy the largest space, as their tails in several instances ex- 
 tend over many millions of miles. The cone of luminous va- 
 pour which radiates from them has been found in some cases 
 (as in 1680 and 1811) equal to the length of the earth's distance 
 from the sun, forming a line that intersects both the orbits of 
 Venus and Mercury. It is even probable that the vapour of 
 the tails of comets mingled with our atmosphere in the years 
 1819 and 1823. Humboldt's Cosmos, vol. i. 
 
 COMETS VISIBLE IN SUNSHINE THE GREAT COMET OF 1843. 
 
 The phenomenon of the tail of a Comet being visible in 
 bright Sunshine, which is recorded of the comet of 1402, oc- 
 curred again in the case of the large comet of 1843, whose 
 nucleus and tail were seen in North America on February 28th 
 (according to the testimony of J. G. Clarke, of Portland, State 
 of Maine), between one and three o'clock in the afternoon. 
 The distance of the very dense nucleus from the sun's light 
 admitted of being measured with much exactness. The nu- 
 cleus and tail (a darker space intervening) appeared like a very 
 pure white cloud. American Journal of Science, vol. xiv. 
 
 E. C. Otte, the translator of Bonn's edition of Humboldt's 
 Cosmos, at New Bedford, Massachusetts, U.S., Feb. 28th, 1843, 
 distinctly saw the above comet between one and two in the 
 afternoon. The sky at the time was intensely blue, and the 
 sun shining with a dazzling brightness unknown in European 
 climates. 
 
 This very remarkable Comet, seen in England on the 17th 
 of March 1843, had a nucleus with the appearance of a planetary 
 disc, and the brightness of a star of the first or second magni- 
 tude. It had a double tail divided by a dark line. At the 
 Cape of Good Hope it was seen in full daylight, and in the im- 
 mediate vicinity of the sea ; but the most remarkable fact in 
 its history was its near approach to the sun, its distance from 
 his surface being only one- fourteenth of his diameter. The heat 
 to which it was exposed, therefore, was much greater than that 
 which Sir Isaac Newton ascribed to the comet of 1680, namely 
 200 times that of red-hot iron. Sir John Herschel has com- 
 puted that it must have been 24 times greater than that which 
 
Curiosities of Science. 85 
 
 was produced in the focus of Parker's burning lens, 32 inches 
 in diameter, which inelts crystals of quartz and agate.* 
 
 THE MILKY WAY UNFATHOMABLE. 
 
 M. Struve of Pulkowa has compared Sir William Herschel's 
 opinion on this subject, as maintained in 1785, with that to 
 which he was subsequently led ; and arrives at the conclusion 
 that, according to Sir W. Herschel himself, the visible extent 
 of the Milky Way increases with the penetrating power of the 
 telescopes employed ; that it is impossible to discover by his 
 instruments the termination of the Milky Way (as an inde- 
 pendent cluster of stars) ; and that even his gigantic telescope 
 of forty feet focal length does not enable him to extend our 
 knowledge of the Milky Way, which is incapable of being 
 sounded. Sir William Herschel's Theory of the Milky Way was 
 as follows : He considered our solar system, and all the stars 
 which we can see with the eye, as placed within, and consti- 
 tuting a part of, the nebula of the Milky Way, a congeries of 
 many millions of stars, so that the projection of these stars 
 must form a luminous track on the concavity of the sky ; and 
 by estimating or counting the number of stars in different di- 
 rections, he was able to form a rude judgment of the probable 
 form of the nebula, and of the probable position of the solar 
 system within it. 
 
 This remarkable belt has maintained from the earliest ages 
 the same relative situation among the stars ; and, when exa- 
 mined through powerful telescopes, is found (wonderful to 
 relate !) to consist entirely of stars scattered by millions, like 
 glittering dust, on the black ground of the general heavens. 
 
 DISTANCES OF NEBULA. 
 
 These are truly astounding. Sir William Herschel esti- 
 mated the distance of the annular nebula between Beta and 
 Gamma Lyrse to be from our system 950 times that of Sirius ; 
 and a globular cluster about 5g south-east of Beta Sir William 
 computed to be one thousand three hundred billions of miles 
 from our system. Again, in Scutum Sobieski is one nebula in 
 the shape of a horseshoe ; but which, when viewed with high 
 magnifying power, presents a different appearance. Sir William 
 Herschel estimated this nebula to be 900 times farther from us 
 than Sirius. In some parts of its vicinity he observed 588 
 stars in his telescope at one time ; and he counted 258,000 in 
 a space 10 long and 2 wide. There is a globular cluster 
 between the mouths of Pegasus and Equuleus, which Sir Wil- 
 
 * For several interesting details of Comets, see " Destruction of the World 
 by a Comet," in Popular Errors Explained and Illustrated, new edit. pp. 165-168. 
 
86 Things not generally Known. 
 
 Ham Herschel estimated to be 243 times farther from us than 
 Sirius. Caroline Herschel discovered in the right foot of An- 
 dromeda a nebula of enormous dimensions, placed at an incon- 
 ceivable distance from us : it consists probably of myriads of 
 solar systems, which, taken together, are but a point in the 
 universe. The nebula about 10 west of the principal star in 
 Triangulum is supposed by Sir William Herschel to be 344 
 times the distance of Sirius from the earth, which would be the 
 immense sum of nearly seventeen thousand billions of miles 
 from our planet. 
 
 INFINITE SPACE. 
 
 After the straining mind has exhausted all its resources in 
 attempting to fathom the distance of the smallest telescopic 
 star, or the faintest nebula, it has reached only the visible con- 
 fines of the sidereal creation. The universe of stars is but an 
 atom in the universe of space ; above it, and beneath it, and 
 around it, there is still infinity. 
 
 ORIGIN OF OUR PLANETARY SYSTEM. THE NEBULAR 
 HYPOTHESIS.* 
 
 The commencement of our Planetary System, including the 
 sun, must, according to Kant and Laplace, be regarded as an 
 immense nebulous mass filling the portion of space which is 
 now occupied by our system far beyond the limits of Neptune, 
 our most distant planet. Even now we perhaps see similar 
 masses in the distant regions of the firmament, as patches of 
 nebulae, and nebulous stars ; within our system also, comets, 
 the zodiacal light, the corona of the sun during a total eclipse, 
 exhibit resemblances of a nebulous substance, which is so thin 
 that the light of the stars passes through it unenfeebled and 
 unref meted. If we calculate the density of the mass of our 
 planetary system, according to the above assumption, for the 
 time when it was a nebulous sphere which reached to the path 
 of the outmost planet, we should find that it would require 
 several cubic miles of such matter to weigh a single grain. 
 Professor Helmholtz. 
 
 A quarter of a century ago, Sir John Herschel expressed his 
 opinion that those nebulae which were not resolved into indivi- 
 dual stars by the highest powers then used, might be hereafter 
 completely resolved by a further increase of optical power : 
 
 * The letters of Sir Isaac Newton to Dr. Bentley, containing suggestions for 
 the Boyle Lectures, po-sess a peculiar interest in the present day. " They show" 
 (says Sir Pavid Brewster) "that the nebulnr hypothesis, the dull and dangerous 
 heresy of the age, is incompatible with the established laws of the material uni- 
 verse, and that an omnipotent arm was required to give the planets their posi- 
 tions and motions in spare, and a presiding intelligence to assign to them the 
 different functions they had to perform." Life of Newton, vol. ii. 
 
Curiosities of Science. 87 
 
 In fact, this probability has almost been converted into a certainty 
 by the magnificent reflecting telescope constructed by Lord Rosse, of 
 6 feet in aperture, which has resolved, or rendered resolvable, multitudes 
 of nebulae which had resisted all inferior powers. The sublimity of the 
 spectacle afforded by that instrument of some of the larger globular and 
 other clusters is declared by all who have witnessed it to be such as no 
 words can express.* 
 
 Although, therefore, nebulae do exist, which even in this powerful 
 telescope appear as nebulae, without any sign of resolution, it may very 
 reasonably be doubted whether there be really any essential physical 
 distinction between nebulae and clusters of stars, at least in the nature of 
 the matter of which they consist ; and whether the distinction between 
 such nebulae as are easily resolved, barely resolvable with excellent tele- 
 scopes, and altogether irresolvable with the best, be any thing else than 
 one of degree, arising merely from the excessive minuteness and multi- 
 tude of the stars of which the latter, as compared with the former, con- 
 sist. Outlines of Astronomy, 5th edit. 1858. 
 
 It should be added, that Sir John Herschel considers the 
 " nebular hypothesis" and the above theory of sidereal aggre- 
 gation to stand quite independent of each other. 
 
 ORIGIN OF HEAT IN OUR SYSTEM. 
 
 Professor Helmholtz, assuming that at the commencement 
 the density of the nebulous matter was a vanishing quantity, 
 as compared with the present density of the sun and planets, 
 calculates how much work has been performed by the conden- 
 sation ; how much of this work still exists in the form of me- 
 chanical force, as attraction of the planets towards the sun, and 
 as vis viva of their motion ; and finds by this how much of the 
 force has been converted into heat. 
 
 The result of this calculation is, that only about the 45th part of 
 the original mechanical force remains as such, and that the remainder, 
 converted into heat, would be sufficient to raise a mass of water equal to 
 the sun and planets taken together, not less than 28,000,000 of degrees 
 of the centigrade scale. For the sake of comparison, Professor Helm- 
 holtz mentions that the highest tempernture which we can produce by 
 the oxy-hydrogen blowpipe, which is sufficient to vaporise even platina, 
 and which but few bodies can endure, is estimated at about 2000 degrees. 
 Of the action of a temperature of 28,000.000 of such degrees we can 
 form no notion. If the mass of our entire system were of pure coal, 
 by the combustion of the whole of it only the 350th part of the above 
 quantity would be generated. 
 
 The store of foixfe at present possessed by our system is equivalent 
 to immense quantities of heat. If our earth were by a sudden shock 
 brought to rest in her orbit which is not to be feared in the existing 
 arrangement of our system by such a shock a quantity of heat would 
 be generated equal to that produced by the combustion of fourteen such 
 earths of solid coal. Making the most unfavourable assumption as to 
 its capacity for heat, that is, placing it equal to that of water, the mass 
 
 * The constitution of the nebulae in the constellation of Orion has been re- 
 solved by this instrument; and by its aid the stars of which it is composed 
 burst upon the sight of man for the first time. 
 
88 Things not generally Known. 
 
 of the earth would thereby be heated ll^OO 3 ; it would therefore be quite 
 fused, and for the most part reduced to vapour. Tf, then, the earth, 
 after having been thus brought to rest, should fall into the sun, which 
 of course would be the case, the quantity of heat developed by the shock 
 would be 400 times greater. 
 
 AN ASTRONOMER'S DREAM VERIFIED. 
 
 The most fertile region in astronomical discovery during 
 the last quarter of a century has been the planetary members 
 of the solar system. In 1833, Sir John Herschel enumerated ten 
 planets as visible from the earth, either by the unaided eye or 
 by the telescope ; the number is now increased more than five- 
 fold. With the exception of Neptune, the discovery of new 
 planets is confined to the class called Asteroids. These all 
 revolve in eliptic orbits between those of Jupiter and Mars. 
 Zitius of Wittemberg discovered an empirical law, which 
 seemed to govern the distances of the planets from the sun ; 
 but there was a remarkable interruption in the law, according 
 to which a planet ought to have been placed between Mars and 
 Jupiter. Professor Bode of Berlin directed the attention of 
 astronomers to the possibility of such a planet existing ; and 
 in seven years' observations from the commencement of the 
 present century, not one but four planets were found, differing 
 widely from one another in the elements of their orbits, but 
 agreeing very nearly at their mean distances from the sun with 
 that of the supposed planet. This curious coincidence of the 
 mean distances of these four asteroids with the planet accord- 
 ing to Bode's law, as it is generally called, led to the conjecture 
 that these four planets were but fragments of the missing 
 planet, blown to atoms by some internal explosion, and that 
 many more fragments might exist, and be possibly discovered 
 by diligent search. 
 
 Concerning this apparently wild hypothesis, Sir John Her- 
 schel offered the following remarkable apology : " This may 
 serve as a specimen of the dreams in which astronomers, like 
 other speculators, occasionally and harmlessly indulge." 
 
 The dream, wild as it appeared, has been realised now. Sir 
 John, in the fifth edition of his Outlines of Astronomy , published 
 in 1858, tells us: 
 
 Whatever may be thought of such a speculation as a physical hypo- 
 thesis, this conclusion has been verified to a considerable extent as a 
 matter of fact by subsequent discovery, the I'esult of a careful and mi- 
 nute examination and mapping down of the smaller stars in and near 
 the zodiac, undertaken with that express object. Zodiacal charts of this 
 kind, the product of the zeal and Industry of many astronomers, have 
 been constructed, in which every star down to the ninth, tenth, or even 
 lower magnitudes, is inserted ; and these stars being compared with the 
 actual stars of the heavens, the intrusion of any stranger within their 
 limits cannot fail to be noticed when the comparison is systematically 
 
Curiosities of Science. 89 
 
 conducted. The discovery of Astraea and Hebe by Professor Hencke, 
 in 1845 and 1847, revived the flagging spirit of inquiry in this direction ; 
 with what success, the list of fifty-two asteroids, with their names and 
 the dates of their discovery, will best show. The labours of our indefa- 
 tigable countryman, Mr. Hind, have been rewarded by the discovery of 
 no less than eight of them. 
 
 FIRE-BALLS AND SHOOTING STARS. 
 
 Humboldt relates, that a friend at Popayan, at an elevation 
 of 5583 feet above the sea-level, at noon, when the sun was 
 shining brightly in a cloudless sky, saw his room lighted up by 
 a fire-ball : he had his back towards the window at the time, 
 and on turning round, perceived that great part of the path 
 traversed by the fire-ball was still illuminated by the brightest 
 radiance. The Germans call these phenomena star-snuff, from 
 the vulgar notion that the lights in the firmament undergo a 
 process of snuffing, or cleaning. Other nations call it a shot or 
 fall of stars, and the English star-shoot. Certain tribes of the 
 Orinoco term the pearly drops of dew which cover the beautiful 
 leaves of the heliconia star-spit. In the Lithuanian mythology, 
 the nature and signification of falling stars are embodied under 
 nobler and more graceful symbols. The Parca3, Werpeja, weave 
 in heaven for the new-born child its thread of fate, attaching 
 each separate thread to a star. When death approaches the 
 person, the thread is rent, and the star wanes and sinks to the 
 earth. Jacob Grimm. 
 
 THEORY AND EXPERIENCE. 
 
 In the perpetual vicissitude of theoretical views, says the 
 author of Giordano Bruno , "most men see nothing in philo- 
 sophy but a succession of passing meteors; whilst even the 
 grander forms in which she has revealed herself share the fate 
 of comets, - bodies that do not rank in popular opinion amongst 
 the external and permanent works of nature, but are regarded 
 as mere fugitive apparitions of igneous vapour." 
 
 METEORITES FROM THE MOON. 
 
 The hypothesis of the selenic origin of meteoric stones de- 
 pends upon a number of conditions, the accidental coincidence 
 of which could alone convert a possible to an actual fact. The 
 view of the original existence of small planetary masses in space 
 is simpler, and at the same time more analogous with those 
 entertained concerning the formation of other portions of the 
 solar system. 
 
 Diogenes Laertius thought aerolites came from the sun ; but Pliny 
 derides this theory. The fall of aerolites in bright sunshine, and when 
 the moon's disc was invisible, probably led to the idea of sun-stones. 
 Moreover Anaxagoras regarded the sun as " a molten fiery mass ;" and 
 
90 Things not generally Known. 
 
 Euripides, in Phaeton, terms the sun "a golden mass," that is to say, 
 a fire-coloured, brightly-shining matter, but not leading to the infer- 
 ence that aerolites are golden sun-stones. The Greek philosophers had 
 four hypotheses as to their origin : telluric, from ascending exhalations; 
 masses of stone raised by hurricanes ; a solar origin ; and lastly, an 
 origin in the regions of space, a* heavenly bodies which had long re- 
 mained invisible: the last opinion entirely according with that of the 
 present day. 
 
 Chladni states that an Italian physicist, Paolo Maria Terzago, on 
 the occasion of the fail of an aerolite at Milan, in 1660, by which a Fran- 
 ciscan monk was killed, was the first who surmised that aerolites were 
 ofselenic origin. Without any previous knowledge of this conjecture, 
 Olbers was led, in 1795 (after the celebrated fall at Siena, June 16th, 
 1794), to investigate the amount of the initial tangential force that 
 would be required to bring to the earth masses projected from the 
 moon. Olbers, Brandes, and Chaldni thought that "the velocity of 16 
 to 32 miles, with which fire-balls and shooting-stars entered our atmo- 
 sphere," furnished a refutation to the view of their seleiiic origin. Ac- 
 cording to Olbers, it would require to reach the earth, setting aside the 
 resistance of the air. an initial velocity of 8292 feet in the second ; ac- 
 cording to Laplace, 7862 ; to Biot, 8282 ; and to Poisson, 7595. Laplace 
 states that this velocity is only five or six times as great as that of a 
 cannon-ball ; but Olbers has shown that " with such an initial velocity 
 as 7500 or 8000 feet in a second, meteoric stones would arrive at the 
 surface of our earth with a velocity of only 35,000 feet." But the mea- 
 sured velocity of meteoric stones averages upwards of 114, 000 feet to a 
 second ; consequently the original velocity of projection from the moon 
 must be almost 110,000 feet, and therefore 14 times greater than Laplace 
 asserted. It must, however, be recollected, that the opinion then so pre- 
 valent, of the existence of active volcanoes in the moon, where air and 
 water are absent, has since been abandoned. 
 
 Laplace elsewhere states, that in all probability aerolites " come 
 from the depths of space ;" yet he in another passage inclines to the hy- 
 pothesis of their lunar origin, always, however, assuming that the stones 
 projected from the moon "become satellites of our earth, describing 
 around it more or less eccentric orbits, and thus not reaching its atmo- 
 sphere until several or even many revolutions have been accomplished." 
 
 In Syria there is a popular belief that aerolites chiefly fall on clear 
 moonlight nights. The ancients (Pliny tells us) looked for their fall 
 during lunar eclipses. Abridged from HumboldCs Cosmos, vol. i. (Bonn's 
 edition). 
 
 Dr. Laurence Smith, U.S., accepts the "lunar theory," and 
 considers meteorites to be masses thrown off from the moon, 
 the attractive power of which is but one-sixth that of the earth; 
 so that bodies thrown from the surface of the mocn experience 
 but one sixth the retarding force they would have when thrown 
 from the earth's surface. 
 
 Look again (says Dr. Smith) at the constitution of the meteorite, 
 made up principally of pure iron. It came evidently from some place 
 where there is little or no oxygen. Now the moon has no atmosphere, 
 and no water on its surface. There is no oxygen there. Hurled from 
 the moon, these bodies, these masses of almost pure iron, would 
 flame in the sun like polished steel, and on reaching our atmosphere 
 would burn in its oxygen until a black oxide cooled it ; and this we find 
 
Curiosities of Science. 91 
 
 to be the case with all meteorites, the black colour is only an external 
 covering. 
 
 Sir Humphry Davy, from facts contained in his researches 
 on flame, in 1817, conceives that the light of meteors depends, 
 not upon the ignition of inflammable gases, but upon that of 
 solid bodies ; that such is their velocity of motion, as to excite 
 sufficient heat for their ignition by the compression even of 
 rare air ; and that the phenomena of falling stars may be ex- 
 plained by regarding them as small incombustible bodies mov- 
 ing round the earth in very eccentric orbits, and becoming 
 ignited only when they pass with immense rapidity through 
 the upper regions of the atmosphere ; whilst those meteors 
 which throw down stony bodies are, similarly circumstanced, 
 combustible masses. 
 
 Masses of iron and nickel, having all the appearance of 
 aerolites or meteoric stones, have been discovered in Siberia, 
 at a depth of ten metres below the surface of the earth. From 
 the fact, however, that no meteoric stones are found in the 
 secondary and tertiary formations, it would seem to follow that 
 the phenomena of falling stones did not take place till the earth 
 assumed its present conditions. 
 
 VAST SHOWER OF METEORS. 
 
 The most magnificent Shower of Meteors that has ever been 
 known was that which fell during the night of November 12th, 
 1833, commencing at nine o'clock in the evening, and continu- 
 ing till the morning sun concealed the meteors from view. This 
 shower extended from Canada to the northern boundary of South 
 America, and over a tract of nearly 3000 miles in width. 
 
 IMMENSE METEORITE. 
 
 Mrs. Somerville mentions a Meteorite which passed within 
 twenty-five miles of our planet, and was estimated to weigh 
 600,000 tons, and to move with a velocity of twenty miles in a 
 second. Only a small fragment of this immense mass reached 
 the earth. Four instances are recorded of persons being killed 
 by their fall. A block of stone fell at Mgos Potamos, B.C. 465, 
 as large as two millstones; another at Narni, in 921, projected 
 like a rock four feet above the surface of the river, in which it 
 was seen to fall. The Emperor Jehangire had a sword forged 
 from a mass of meteoric iron, which fell in 1620 at Jahlinder 
 in the Punjab. Sixteen instances of the fall of stones in the 
 British Isles are well authenticated to have occurred since 1620, 
 one of them in London. It is very remarkable that no new 
 chemical element has been detected in any of the numerous 
 meteorites which have been analysed. 
 
92 Things not generally Known. 
 
 NO FOSSIL METEORIC STONES. 
 
 It is (says Olbers) a remarkable but hitherto unregarded 
 fact, that while shells are found in secondary and tertiary for- 
 mations, no Fossil Meteoric Stones have as yet been discovered. 
 May we conclude from this circumstance, that previous to the 
 present and last modification of the earth's surface no meteoric 
 stones fell on it, though at the present time it appears probable, 
 from the researches of Schreibers, that 700 fall annually?* 
 
 THE END OF OUR SYSTEM. 
 
 While all the phenomena in the heavens indicate a law of 
 progressive creation, in which revolving matter is distributed 
 into suns and planets, there are indications in our own system 
 that a period has been assigned for its duration, which, sooner 
 or later, it must reach. The medium which nils universal 
 space, whether it be a luminiferous ether, or arise from the 
 indefinite expansion of planetary atmospheres, must retard the 
 bodies which move in it, even were it 360,000 millions of times 
 more rare than atmospheric air ; and, with its time of revo- 
 lution gradually shortening, the satellite must return to its 
 planet, the planet to its sun, and the sun to its primeval nebula. 
 The fate of our system, thus deduced from mechanical laws, 
 must be the fate of all others. Motion cannot be perpetuated 
 in a resisting medium ; and where there exist disturbing forces, 
 there must be primarily derangement, and ultimately ruin. 
 From the great central mass, heat may again be summoned to 
 exhale nebulous matter ; chemical forces may again produce 
 motion, and motion may again generate systems ; but, as in 
 the recurring catastrophes which have desolated our earth, the 
 great First Cause must preside at the dawn of each cosrnical 
 cycle ; and, as in the animal races which were successively re- 
 produced, new celestial creations of a nobler form of beauty 
 and of a higher form of permanence nitty yet appear in the 
 sidereal universe. " Behold, I create new heavens and a new 
 earth, and the former shall not be remembered." "The new 
 heavens and the new earth shall remain before me." "Let us 
 look, then, according to this promise, for the new heavens and 
 the new earth, wherein dwelleth righteousness." North-British 
 Review, No. 3. 
 
 BENEFITS OF GLASS TO MAN. 
 
 Cuvier eloquently says : " It could not be expected that 
 those Phoenician sailors who saw the sand of the shores of 
 Bactica transformed by fire into a transparent Glass, should have 
 at once foreseen that this new substance would prolong the 
 
 * Several specimens of Meteoric Iron are to be seen in the Mineral ogical 
 Collection in the British Museum. 
 
Curiosities of Science. 93 
 
 pleasures of sight to the old ; that it would one day assist the 
 astronomer in penetrating the depths of the heavens, and in 
 numbering the stars of the Milky Way ; that it would lay open 
 to the naturalist a miniature world, as populous, as rich in 
 wonders as that which alone seemed to have been granted to 
 his senses and his contemplation : in fine, that the most simple 
 and direct use of it would enable the inhabitants of the coast 
 of the Baltic Sea to build palaces more magnificent than those 
 of Tyre and Memphis, and to cultivate, almost under the polar 
 circle, the most delicious fruit of the torrid zone." 
 
 THE GALILEAN TELESCOPE. 
 
 Galileo appears to be justly entitled to the honour of hav- 
 ing invented that form of Telescope which still bears his name ; 
 while we must accord to John Lippershey, the spectacle-maker 
 of Middleburg, the honour of having previously invented the 
 astronomical telescope. The interest excited at Venice by 
 Galileo's invention amounted almost to frenzy. On ascending 
 the tower of St. Mark, that he might use one of his telescopes 
 without molestation, Galileo was recognised by a crowd in the 
 street, who took possession of the wondrous tube, and detained 
 the impatient philosopher for several hours, till they had suc- 
 cessively witnessed its effects. These instruments were soon 
 manufactured in great numbers ; but were purchased merely as 
 philosophical toys, and were carried by travellers into every 
 corner of Europe. 
 
 WHAT GALILEO FIRST SAW WITH HIS TELESCOPE. 
 
 The moon displayed to him her mountain-ranges and her 
 glens, her continents and her highlands, now lying in dark- 
 ness, now brilliant with sunshine, and undergoing all those 
 variations of light and shadow which the surface of our own 
 globe presents to the alpine traveller or to the aeronaut. The 
 four satellites of Jupiter illuminating their planet, and suffer- 
 ing eclipses in his shadow, like our own moon ; the spots on 
 the sun's disc, proving his rotation round his axis in twenty- 
 five days ; the crescent phases of Venus, and the triple form 
 or the imperfectly developed ring of Saturn, were the other 
 discoveries in the solar system which rewarded the diligence of 
 Galileo. In the starry heavens, too, thousands of new worlds 
 were discovered by his telescope ; and the Pleiades alone, which 
 to the unassisted eye exhibit only seven stars, displayed to Gali- 
 leo no fewer than/o;t?/. North-British Review, No. 3. 
 
 The first telescope " the starry Galileo" constructed with a leaden 
 tube a few inches long, with a spectacle-glass, one convex and one con- 
 cave, at each of its extremities. It magnified three times. Telescopes 
 were made in London in February 1610, a year after Galileo had com- 
 
94 Things not generally Known. 
 
 pleted his own (Rigaud, On Harriot's Papers, 1833). They were at first 
 called cylinders. The telescopes which Galileo constructed, and others 
 of which he made use for observing Jupiter's satellites, the phases of 
 Venus, and the solar spots, possessed the gradually-increasing powers 
 of magnifying four, seven, and thirty-two linear diameters ; but they 
 never had a higher power. Arago, in the Annuaire for 1842. 
 
 Clock-work is now applied to the equatorial telescope, so as to allow 
 the observer to follow the course of any star, comet, or planet he may 
 wish to observe continuously, without using his hands for the mechani- 
 cal motion of the instrument. 
 
 ANTIQUITY OF TELESCOPES. 
 
 Long tubes were certainly employed by Arabian astrono- 
 mers, and very probably also by the Greeks and Romans ; the 
 exactness of their observations being in some degree attribut- 
 able to their causing the object to be seen through diopters or 
 slits. Abul Hassan speaks very distinctly of tubes, to the ex- 
 tremities of which ocular and object diopters were attached ; 
 and instruments so constructed were used in the observatory 
 founded by Hulagu at Meragha. If stars be more easily dis- 
 covered during twilight by means of tubes, and if a star be 
 sooner revealed to the naked eye through a tube than without 
 it, the reason lies, as Arago has truly observed, in the circum- 
 stance that the tube conceals a great portion of the disturbing 
 light diffused in the atmospheric strata between the star and 
 the eye applied to,,the tube. In like manner, the tube pre- 
 vents the lateral impression of the faint light which the par- 
 ticles of air receive at night from all the other stars in the 
 firmament. The intensity of the image and the size of the 
 star are apparently augmented. Humboldt's Cosmos, vol. iii. 
 p. 53. 
 
 NEWTON'S FIRST REFLECTING TELESCOPE. 
 
 The year 1668 may be regarded as the date of the invention 
 of Newton's Reflecting Telescope. Five years previously, James 
 Gregory had described the manner of constructing a reflecting 
 telescope with two concave specula ; but Newton perceived the 
 disadvantages to be so great, that, according to his statement, 
 he "found it necessary, before attempting any thing in the 
 practice, to alter the design, and place the eye-glass at the side 
 of the tube rather than at the middle." On this improved 
 principle Newton constructed his telescope, which was exa- 
 mined by Charles II. ; it was presented to the Royal Society 
 near the end of 1671, and is carefully preserved by that distin- 
 guished body, with the inscription : 
 "THE FIRST REFLECTING TELESCOPE ; INVENTED BY SIR ISAAC NEWTON, 
 
 AND MADE WITH HIS OWN HANDS." 
 
 Sir David Brewster describes this telescope as consisting of 
 a concave metallic speculum, the radius of curvature of which 
 
Curiosities of Science. 95 
 
 was 12f or 13 inches, so that " it collected the sun's rays at 
 the distance of 6 inches." The rays reflected by the specu- 
 lum were received upon a plane metallic speculum inclined 45 
 to the axis of the tube, so as to reflect them to the side of the 
 tube in which there was an aperture to receive a small tube 
 with a plano-convex eye-glass whose radius was one-twelfth 
 of an inch, by means of which the image formed by the specu- 
 lum was magnified 38 times. Such was the first reflecting 
 telescope applied to the heavens ; but Sir David Brewster de- 
 scribes this instrument as small and ill-made ; and fifty years 
 elapsed before telescopes of the Newtonian form became useful 
 in astronomy. 
 
 SIR WILLIAM HEESCHEL'S GREAT TELESCOPE AT SLOUGH. 
 
 The plan of this Telescope was intimated by Herschel, 
 through Sir Joseph Banks, to George III., who offered to de- 
 fray the whole expense of it ; a noble act of liberality, which 
 has never been imitated by any other British sovereign. Towards 
 the close of 1785, accordingly, Herschel began to construct his 
 reflecting telescope, forty feet in length, and having a speculum 
 fully four feet in diameter. The thickness of the speculum, 
 which was uniform in every part, was 3 2 inches, and its weight 
 nearly 2118 pounds ; the metal being composed of 32 copper, 
 and 1O7 of tin : it was the third speculum cast, the two pre- 
 vious attempts having failed. The speculum, when not in use, 
 was preserved from damp by a tin cover, fitted upon a rim of 
 close-grained cloth. The tube of the telescope was 39 ft. 4 in. 
 long, and its width 4 ft. 10 in. ; it was made of iron, and was 
 3000 Ibs. lighter than if it had been made of wood. The ob- 
 server was seated in a suspended movable seat at the mouth 
 of the tube, and viewed the image of the object with a magni- 
 fying lens or eye-piece. The focus of the speculum, or place 
 of the image, was within four inches of the lower side of the 
 mouth of the tube, and came forward into the air, so that there 
 was space for part of the head above the eye, to prevent it 
 from intercepting many of the rays going from the object to 
 the mirror. The eye-piece moved in a tube carried by a slider 
 directed to the centre of the speculum, and fixed on an ad- 
 justible foundation at the mouth of the tube. It was com- 
 pleted on the 27th August 1789; and the very first moment it 
 was directed to the heavens, a new body was added to the 
 solar system, namely, Saturn and six of its satellites ; and in 
 less than a month after, the seventh satellite of Saturn, " an 
 object," says Sir John Herschel, "of a far higher order of 
 difficulty." Abridged from the North-British Itevieu;No. 3. 
 
 This magnificent instrument stood on the lawn in the rear of Sir 
 William Herschel' a house at Slough ; and some of our readers, like our- 
 
96 Things not generally Known. 
 
 selves, may remember its extraordinary aspect when seen from the 
 Bath coach-road, and the road to Windsor. The difficulty of managing 
 so large an instrument requiring as it did two assistants in addition 
 to the observer himself and the person employed to note the time 
 prevented its being much used. Sir John Herschel, in a letter to Mr. 
 Weld, states the entire cost of its construction, 400CM., was defrayed by 
 George III. In 1839, the woodwork of the telescope being decayed, 
 Sir John Herschel had it cleared away ; and piers were erected, on 
 which the tube was placed, that being of iron, and so well preserved 
 that, although not more than one-twentieth of an inch thick, when in 
 the horizontal position it contained within all Sir John's family ; and 
 next the two reflectors, the polishing apparatus, and portions" of the 
 machinery, to the amount of a great many tons. Sir John attributes 
 this great strength and resistance to the internal structure of the tube, 
 very similar to that patented under the name of corrugated iron-roping. 
 Sir John Herschel also thinks that system of triangular arrangement 
 of the woodwork was upon the principle to which " diagonal bracing" 
 owes its strength. 
 
 THE EARL OF ROSSE's GREAT REFLECTING TELESCOPE. 
 
 Sir David Brewster has remarked, that " the long interval 
 of half a century seems to be the period of hibernation during 
 which the telescopic mind rests from its labours in order to ac- 
 quire strength for some great achievement. Fifty years elapsed 
 between the dwarf telescope of Newton and the large instru- 
 ments of Hadley ; other fifty years rolled on before Sir William 
 Herschel constructed his magnificent telescope ; and fifty years 
 more passed away before the Earl of Rosse produced that colos- 
 sal instrument which has already achieved such brilliant disco- 
 veries." * 
 
 In the improvement of the Reflecting Telescope, the first 
 object has always been to increase the magnifying power and 
 light by the construction of as large a mirror as possible ; and 
 to this point Lord Rosse's attention was directed as early as 
 1828, the field of operation being at his lordship's seat, Birr 
 Castle at Parsonstown, about fifty miles west of Dublin. For 
 this high branch of scientific inquiry Lord Rosse was well fitted 
 by a rare combination of " talent to devise, patience to bear 
 disappointment, perseverance, profound mathematical know- 
 ledge, mechanical skill, and uninterrupted leisure from other 
 pursuits ;"f all these, however, would not have been sufficient, 
 had not a great command of money been added ; the gigantic 
 telescope we are about to describe having cost certainly not 
 less than twelve thousand pounds. 
 
 Lord Rosse ground and polished specula fifteen inches, two feet, and 
 three feet in diameter before he commenced the colossal instrument. It 
 is impossible here to detail the admirable contrivances and processes by 
 which he prepared himself for this great work. He first ascertained 
 
 * Life of Sir Isaac Nfwton, vol. i. p. 62. 
 
 | Description of the Monster Telescope,, by Thomas Woods. M.D. 4th edit. 1851. 
 
Curiosities of Science. 97 
 
 the most useful combination of metals for specula, both in whiteness, 
 porosity, and hardness, to be copper and tin. Of this compound the re- 
 flector was cast in pieces, which were fixed on a bed of zinc and copper, 
 a species of brass which expanded in the same degree by heat as the 
 pieces of the speculum themselves. They were ground as one body to 
 a true surface, and then polished by machinery moved by a steam- 
 engine. The peculiarities of this mechanism were entirely Lord Rosse's 
 invention, and the result of close calculation and observation : they were 
 chiefly, placing the speculum with the face upward, regulating the tem- 
 perature by having it immersed in water, usually at 55 Fahr,, and re- 
 gulating the pressure and velocity. This was found to work a perfect 
 spherical figure in large surfaces with a degree of precision unattainable 
 by the hand ; the polisher, by working above and upon the face of the 
 speculum, being enabled to examine the operation as it proceeded with- 
 out removing the speculum, which, when a ton weight, is no easy matter. 
 The contrivance for doing this is very beautiful. The machine is 
 placed in a room at the bottom of a high tower, in the successive floors 
 of which trap-doors can be opened. A mast is elevated on the top of the 
 tower, so that its summit is about ninety feet above the speculum. A 
 dial-plate is attached to the top of the mast, and a small plane speculum 
 and eye-piece, with proper adjustments, are so placed that the combin- 
 ation becomes a Newtonian telescope, and the dial-plate the object. 
 The last and most important part of the process of working the specu- 
 lum, is to give it a true parabolic figure, that is, such a figure that each 
 portion of it should reflect the incident ray to the same focus. Lord 
 Eosse's operations for this purpose consist 1st, of a stroke of the first 
 eccentric, which carries the polisher along one-third of the diameter of 
 the speculum ; 2d, a transverse stroke twenty-one times slower, and 
 equal to 0'27 of the same diameter, measured on the edge of the tank, 
 or 1'7 beyond the centre of the polisher ; 3d, a rotation of the speculum 
 performed in the same time as thirty-seven of the first strokes ; and 
 4th, a rotation of the polisher in the same direction about sixteen times 
 slower. If these rules are attended to, the machine will give the true 
 parabolic figure to the speculum, whether it be six inches or three feet 
 in diameter In the three-feet speculum, the figure is so true with the 
 whole aperture, that it is thrown out of focus by a motion of less than 
 the thirti-.th of an inch, "and even with a single lens of one-eighth of 
 an inch focus, giving a power of 2592, the dots on a watch-dial are still 
 in some degree defined." 
 
 Thus was executed the three-feet speculum for the twenty- 
 six-feet telescope placed upon the lawn at Parsonstown, which, 
 in 1840, showed with powers up to 1000 and even 1600 ; and 
 which resolved nebulae into stars, and destroyed that symmetry 
 of form in globular nebulae upon which was founded the hypo- 
 thesis of the gradual condensation of nebulous matter into suns 
 and planets.* 
 
 Scarcely was this instrument out of Lord Rosse's hands, 
 when he resolved to attempt by the same processes to construct 
 
 * This instrument also discovered a multitude of new objects in the moon; 
 as a mountainous tract near Ptolemy, every rid^e of which is dotted with ex- 
 tremely minute craters, and two black parallel stripes in the bottom of Ar>star- 
 chus. Dr. Robinson, in his address to the British Association in 1843, stated that 
 in this telescope a building the size of the Court-house at Cork would be easily 
 visible on the lunar surface. 
 
98 Things not qenerally Known, 
 
 y u y 
 
 another reflector, with a speculum six feet in diameter 
 feet long ! and this magnificent instrument was completed early 
 in 1845. The focal length of the speculum is fifty-four feet. It 
 weighs four tons, and, with its supports, is seven times as heavy 
 as the four-feet speculum of Sir William Herschel. The specu- 
 lum is placed in one of the sides of a cubical wooden box, about 
 eight feet wide, and to the opposite end of this box is fastened 
 the tube, which is made of deal staves an inch thick, hooped 
 with iron clamp-rings, like a huge cask. It carries at its upper 
 end, and in the axis of the tube, a small oval speculum, six 
 inches in its lesser diameter. 
 
 The tube is about 50 feet long and 8 feet in diameter in 
 the middle, and furnished with diaphragms 6 feet in aperture. 
 The late Dean of Ely walked through the tube with an umbrella 
 up. 
 
 The telescope is established between two lofty castellated 
 piers 60 feet high, and is raised to different altitudes by a 
 strong chain-cable attached to the top of the tube. This cable 
 passes over a pulley on a frame down to a windlass on the 
 ground, which is wrought by two assistants. To the frame are 
 attached chain-guys fastened to the counterweights ; and the 
 telescope is balanced by these counterweights suspended by 
 chains, which are fixed to the sides of the tube and pass over 
 large iron pulleys. The immense mass of matter weighs about 
 twelve tons. 
 
 On the eastern pier is a strong semicircle of cast-iron, with 
 which the telescope is connected by a racked bar, with fric- 
 tion-rollers attached to the tube by wheel work, so that by 
 means of a handle near the eye-piece, the observer can move 
 the telescope along the bar on either side of the meridian, to 
 the distance of an hour for an equatorial star. 
 
 On the western pier are stairs and galleries. The observ- 
 ing gallery is moved along a railway by means of wheels and a 
 winch ; and the mechanism for raising the galleries to various 
 altitudes is very ingenious. Sometimes the galleries, filled with 
 observers, are suspended midway between the two piers, over 
 a chasm sixty feet deep. 
 
 An excellent description of this immense Telescope at 
 Birr Castle will be found in Mr. Weld's volume of Vacation 
 Rambles, 
 
 Sir David Brewster thus eloquently sketches the powers of 
 the telescope at the close of his able description of the instru- 
 ment, which we have in part quoted from his Life of Sir Isaac 
 Newton. 
 
 We have, in the mornings, walked again and again, and ever with 
 new delight, along its mystic tube, and at midnight, with its distin- 
 guished architect, pondered over the marvellous sights which it dis- 
 
Curiosities of Science. 99 
 
 closes, the satellites and belts and rings of Saturn, the old and new 
 ring, which is advancing with its crest of waters to the body of the 
 planet, the rocks, and mountains, and valleys, and extinct volcanoes 
 of the moon, the crescent of Venus, with its mountainous outline, 
 the systems of double and triple stars, the nebulae and starry clusters 
 of every variety of shape, and those spiral nebular formations which 
 baffle human compi-ehension, and constitute the greatest achievement 
 in modern discovery. 
 
 The Astronomer Royal, Mr. Airy, alludes to the impression 
 made by the enormous light of the telescope, partly by the 
 modifications produced in the appearance of nebulae already 
 figured, partly by the great number of stars seen at a distance 
 from the Milky Way, and partly from the prodigious brilliancy 
 of Saturn. The account given by another astronomer of the 
 appearance of Jupiter was that it resembled a coach-lamp in 
 the telescope ; and this well expresses the blaze of light which 
 is seen in the instrument. 
 
 The Rev. Dr. Scoresby thus records the results of his visits : 
 The range opened to us by the great telescope at Birr Castle is best, 
 perhaps, apprehended by the now usual measurement not of distances 
 in miles, or millions of miles, or diameters of the earth's orbit, but 
 of the progress of light in free space. The determination within, no 
 doubt, a small proportion of error of the parallax of a considerable 
 number of the fixed stars yields, according to Mr. Peters, a space be- 
 twixt us and the fixed stars of the smallest magnitude, the sixth, ordi- 
 narily visible to the naked eye, of 130 years in the flight of light. This 
 information enables us, on the principles of sounding the heavens, sug- 
 gested by Sir W. Herschel, with the photometrical researches on the 
 stars of Dr. Wollaston and others, to carry the estimation of distances, 
 and that by no means on vague assumption, to the limits of space 
 opened out by the most effective telescopes. And from the guidance 
 thus afforded us as to the comparative power of the six feet speculum 
 in the penetration of space as already elucidated, we might fairly as- 
 sume the fact, that if any other telescope now in use could follow the 
 sun if removed to the remotest visible position, or till its light would 
 require 10,000 years to reach us, the grand instrument at Parsonstown 
 would follow it so far that from 20,000 to 25,000 years would be spent in 
 the transmission of its light to the earth. But in the cases of clusters 
 of stars, and of nebulae exhibiting a mere speck of misty luminosity, 
 from the combined light of perhaps hundreds of thousands of suns, the 
 penetration into space, compared with the results of ordinary vision, 
 must be enormous ; so that it would not be difficult to show the proba- 
 bility that a million of years, in flight of light, would be requisite, in 
 regard to the most distant, to trace the enormous interval. 
 
 GIGANTIC TELESCOPES PROPOSED. 
 
 Hooke is said to have proposed the use of Telescopes having 
 a length of upwards of 10,000 feet (or nearly two miles), in 
 order to see animals in the moon ! an extravagant expectation 
 which Auzout considered it necessary to refute. The Capuchin 
 monk Schyrle von Rheita, who was well versed in optics, had 
 already spoken of the speedy practicability of constructing te- 
 
100 Things not generally Known. 
 
 lescopes that should magnify 4000 times, by means of which 
 the lunar mountains might be accurately laid down. 
 
 Optical instruments of such enormous focal lengths remind 
 us of the Arabian contrivances of measurement : quadrants with 
 a radius of about 190 feet, upon whose graduated limb the 
 image of the sun was received as in the gnomon, through a 
 small round aperture. Such a quadrant was erected at Sa- 
 marcand, probably constructed after the model of the older 
 sextants of Alchokandi, which were about sixty feet in height. 
 
 LATE INVENTION OF OPTICAL INSTRUMENTS. 
 
 A writer in the North-British Review, No. 50, considers it 
 strange that a variety of facts which must have presented 
 themselves to the most careless observer should not have led 
 to the earlier construction of Optical Instruments. The an- 
 cients, doubtless, must have formed metallic articles with con- 
 cave surfaces, in which the observer could not fail to see him- 
 self magnified ; and if the radius of the concavity exceeded 
 twelve inches, twice the focal distance of his eye, he had in 
 his hands an extempore reflecting telescope of the Newtonian 
 form, in which the concave metal was the speculum, and his 
 eye the eye-glass, and which would magnify and bring near him 
 the image of objects nearly behind him. Through the spheri- 
 cal drops of water suspended before his eye, an attentive ob- 
 server might have seen magnified, some minute body placed 
 accidentally in its anterior focus ; and in the eyes of fishes and 
 quadrupeds which he used for his food, he might have seen, 
 and might have extracted, the beautiful lenses which they 
 contain, and which he could not fail to regard as the principal 
 agents in the vision of the animals to which they belonged. 
 Curiosity might have prompted him to look through these re- 
 markable lenses or spheres ; and had he placed the lens of the 
 smallest minnow, or that of the bird, the sheep, or the ox, in 
 or before a circular aperture, he would have produced a micro- 
 scope or microscopes of excellent quality and different magni- 
 fying powers. No such observations seem, however, to have 
 been made ; and even after the invention of glass, and its con- 
 version into globular vessels, through which, when filled with 
 any fluid, objects are magnified, the microscope remained un- 
 discovered. 
 
 A TRIAD OF CONTEMPORARY ASTRONOMERS. 
 
 It is a remarkable fact in the history of astronomy (says 
 Sir David Brewster), that three of its most distinguished pro- 
 fessors were contemporaries. Galileo was the contemporary 
 of Tycho during thirty-seven years, and of Kepler during the 
 fifty-nine years of his life. Galileo was born seven years before 
 
Curiosities of Science. 101 
 
 Kepler, and survived him nearly the same time. We have not 
 learned that the intellectual triumvirate of the age enjoyed 
 any opportunity for mutual congratulation. What a privilege 
 would it have been to have contrasted the aristocratic dignity 
 of Tycho with the reckless ease of Kepler, and the manly and 
 impetuous mien of the Italian sage ! Brewster's Life of Newton. 
 
 A PEASANT ASTRONOMER. 
 
 At about the same time that Goodricke discovered the 
 variation of the remarkable periodical star Algol, or ft Persei, 
 one Palitzch, a farmer of Prolitz, near Dresden, a peasant by 
 station, an astronomer by nature, from his familiar acquaint- 
 ance with the aspect of the heavens, was led to notice, among 
 so many thousand stars, Algol, as distinguished from the rest 
 by its variation, and ascertained its period. The same Palitzch 
 was also the first to re-discover the predicted comet of Halley 
 in 1759, which he saw nearly a month before any of the as- 
 tronomers, who, armed with their telescopes, were anxiously 
 watching its return. These anecdotes carry us back to the era 
 of the Chaldean shepherds. Sir John HerscheVs Outlines. 
 
 SHIRBURN-CASTLE OBSERVATORY. 
 
 Lord Macclesfield, the eminent mathematician, who was 
 twelve years President of the Royal Society, built at his seat, 
 Shirburn Castle in Oxfordshire, an Observatory, about 1739. 
 It stood 100 ya.rds south from the castle-gate, and consisted of 
 a bed-chamber, a room for the transit, and the third for a mural 
 quadrant. In the possession of the Royal Astronomical So- 
 ciety is a curious print representing two of Lord Macclesfield's 
 servants taking observations in the Shirburn observatory ; they 
 are Thomas Phelps, aged 82, who, from being a stable-boy to 
 Lord-Chancellor Macclesfield, rose by his merit and genius to 
 be appointed observer. His companion is John Bartlett, ori- 
 ginally a shepherd, in which station he, by books and observa- 
 tion, acquired such a knowledge in computation, and of the 
 heavenly bodies, as to induce Lord Macclesfield to appoint 
 him assistant-observer in his observatory. Phelps was the 
 person who, on December 23d, 1743, discovered the great 
 comet, and made the first observation of it; an account of 
 which is entered in the Philosophical Transactions, but not the 
 name of the observer. 
 
 LACAILLE'S OBSERVATORY. 
 
 Lacaille, who made more observations than all his contem- 
 poraries put together, and whose researches will have the 
 highest value as long as astronomy is cultivated, had an ob- 
 servatory at the College Mazarin, part of which is now the 
 Palace of the Institute, at Paris. 
 
102 Things not generally Know?i. 
 
 For a long time it had been without observer or instruments ; under 
 Napoleon's reign it was demolished. Lacaille never used to illuminate 
 the wires of his instruments. The inner part of his observatory was 
 painted black ; he admitted only the faintest light, to enable him to 
 see his pendulum and his paper : his left eye was devoted to the service 
 of looking to the pendulum, whilst his right eye was kept shut. The 
 latter was only employed to look to the telescope, and during the time 
 of observation never opened but for this purpose. Thus the faintest 
 light made him distinguish the wires, and he very seldom felt the ne- 
 cessity of illuminating them. Part of these blackened walls were visible 
 long after the demolition of the observatory, which took place some- 
 what about 1811. Professor Mohl. 
 
 NICETY REQUIRED IN ASTRONOMICAL CALCULATIONS. 
 
 In the Edinburgh Review, 1850, we find the following illus- 
 trations of the enormous propagation of minute errors : 
 
 The rod used in measuring a base-line is commonly about ten feet 
 long ; and the astronomer may be said truly to apply that very rod to 
 mete the distance of the stars. An error in placing a tine dot which 
 fixes the length of the rod, amounting to one-five-thousandth of an inch 
 (the thickness of a single silken fibre), will amount to an error of 70 
 feet in the earth's diameter, of 316 miles in the sun's distance, and to 
 65,200,000 miles in that of the nearest fixed star. Secondly, as the 
 astronomer in his observatory has nothing further to do with ascertain- 
 ing lengths or distances, except by calculation, his whole skill and arti- 
 fice are exhausted in the measurement of angles ; for by these alone 
 spaces inaccessible can be compared. Happily, a ray of light is straight : 
 were it not so (in celestial spaces at least), there would be an end of 
 our astronomy. Now an angle of a second (3600 to a degree) is a subtle 
 thing. It has an apparent breadth utterly invisible to the unassisted 
 eye, unless accompanied with so intense a splendour (e. g. in the case of 
 a fixed star) as actually to raise by its effect on the nerve of sight a 
 spurious image having a sensible breadth. A silkworm's fibre, such as 
 we have mentioned above, subtends an angle of a second at 3.^ feet 
 distance ; a cricket-ball, 2 inches diameter, must be removed, in order 
 to subtend a second, to 43,000 feet, or about 8 miles, where it would 
 be utterly invisible to the sharpest sight aided even by a telescope of 
 some power. Yet it is on the measure of one single second that the 
 ascertainment of a sensible parallax in any fixed star depends ; and an 
 error of one-thousandth of that amount (a quantity still unmeasurable 
 by the most perfect of our instruments) would place the star too far or 
 too near by 200,000,000,000 miles ; a space which light requires 118 days 
 to travel. 
 
 CAN STARS BE SEEN BY DAYLIGHT ? 
 
 Aristotle maintains that Stars may occasionally be seen in 
 the Daylight, from caverns and cisterns, as through tubes. 
 Pliny alludes to the same circumstance, and mentions that 
 stars have been most distinctly recognised during solar eclipses. 
 Sir John Hersohel has heard it stated by a celebrated optician, 
 that his attention was first drawn to astronomy by the regular 
 appearance, at a certain hour, for several successive days, of a 
 considerable star through the shaft of a chimney. The chim- 
 ney-sweepers who have been questioned upon this subject agree 
 
Curiosities of Science. 103 
 
 tolerably well in stating that " they have never seen stars by 
 day, but that when observed at night through deep shafts, the 
 sky appeared quite near, and the stars larger." Saussure states 
 that stars have been seen with the naked eye in broad day- 
 light, on the declivity of Mont Blanc, at an elevation of 12,757 
 feet, as he was assured by several of the alpine guides. The 
 observer must be placed entirely in the shade, and have a thick 
 and massive shade above his head, else the stronger light of 
 the air will disperse the faint image of the stars ; these condi- 
 tions resembling those presented by the cisterns of the ancients, 
 and the chimneys above referred to. Humboldt, however, 
 questions the accuracy of these evidences, adding that in the 
 Cordilleras of Mexico, Quito, and Peru, at elevations of 15,000 
 or 16,000 feet above the sea-level, he never could distinguish 
 stars by daylight. Yet, under the ethereally pure sky of Cu- 
 maua, in the plains near the sea-shore, Humboldt has fre- 
 quently been able, after observing an eclipse of Jupiter's sa- 
 tellites, to find the planet again with the naked eye, and has 
 most distinctly seen it when the sun's disc was from 18 to 20 
 above the horizon. 
 
 LOST HEAT OF THE SUN. 
 
 By the nature of our atmosphere, we are protected from 
 the influence of the full flood of solar heat. The absorption 
 of caloric by the air has been calculated at about one-fifth of 
 the whole in passing through a column of 6000 feet, estimated 
 near the earth's surface. And we are enabled, knowing the 
 increasing rarity of the upper regions of our gaseous envelope, 
 in which the absorption is constantly diminishing, to prove 
 that about one-third of the solar heat is lost by vertical trans- 
 mission through the whole extent of our atmosphere. J. D. 
 Forbes, F.R.S. ; Bakerian Lecture, 1842. 
 
 THE LONDON MONUMENT USED AS AN OBSERVATORY. 
 
 Soon after the completion of the Monument on Fish Street 
 Hill, by Wren, in 1677, it was used by Hooke and other mem- 
 bers of the Royal Society for astronomical purposes, but aban- 
 doned on account of the vibrations being too great for the 
 nicety required in their observations. Hence arose the report 
 that the Monument was unsafe, which has been revived in our 
 time ; " but," says Elmes, " its scientific construction may bid 
 defiance to the attacks of all but earthquakes for centuries to 
 come." This vibration in lofty columns is not uncommon. 
 Captain Smythe, in his Cycle of Celestial^ Objects, tells us, that 
 when taking observations on the summit of Pompey's Pillar, 
 near Alexandria, the mercury was sensibly affected by tremor, 
 although the pillar is a solid. 
 
104 Things not generally Known. 
 
 ffieologg antr 
 
 IDENTITY OF ASTKONOMY AND GEOLOGY. 
 
 WHILE the Astronomer is studying the form and condition and 
 structure of the planets, in so far as the eye and the telescope 
 can aid him, the Geologist is investigating the form and con- 
 dition and structure of the planet to which he belongs ; and it 
 is from the analogy of the earth's structure, as thus ascertained, 
 that the astronomer is enabled to form any rational conjecture 
 respecting the nature and constitution of the other planetary bo- 
 dies. Astronomy and Geology, therefore, constitute the same 
 science the science of material or inorganic nature. 
 
 When the astronomer first surveys the concavity of the ce- 
 lestial vault, he finds it studded with luminous bodies differing 
 in magnitude and lustre, some moving to the east and others 
 to the west ; while by far the greater number seem fixed in 
 space ; and it is the business of astronomers to assign to each 
 of them its proper place and sphere, to determine their true 
 distance from the earth, and to arrange them in systems 
 throughout the regions of sidereal space. 
 
 In like manner, when the geologist surveys the convexity of 
 his own globe, he finds its solid covering composed of rocks 
 and beds of all shapes and kinds, lying at every possible angle, 
 occupying every possible position, and all of them, generally 
 speaking, at the same distance from the earth's centre. Every 
 where we see what was deep brought into visible relation with 
 what was superficial what is old with what is new what 
 preceded life with what followed it. 
 
 Thus displayed on the surface of his globe, it becomes the 
 business of the geologist to ascertain how these rocks came 
 into their present places, to determine their different ages, 
 and to fix the positions which they originally occupied, and 
 consequently their different distances from the centre or the 
 circumference of the earth. Raised from their original bed, 
 the geologist must study the internal forces by which they 
 were upheaved, and the agencies by which they were indurated; 
 and when he finds that strata of every kind, from the primitive 
 granite to the recent tertiary marine mud, have been thus 
 brought within his reach, and prepared for his analysis, he 
 reads their respective ages in the organic remains which they 
 entomb ; he studies the Banner iu which they have perished, 
 
Curiosities of Science. 105 
 
 and he counts the cycles of time and of life which they disclose. 
 Abridged from the North-British Review, No. 9. 
 
 THE GEOLOGY OF ENGLAND 
 
 is more interesting than that of other countries, because our 
 island is in a great measure an epitome of the globe ; and the 
 observer who is familiar with our strata, and the fossil remains 
 which they include, has not only prepared himself for similar 
 inquiries in other countries, but is already, as it were, by an- 
 ticipation, acquainted with what he is to find there. Trans- 
 actions of the Geological Society. 
 
 PROBABLE ORIGIN OF THE ENGLISH CHANNEL. 
 
 The proposed construction of a submarine tunnel across the 
 Straits of Dover has led M. Boue. For. Mem, Geol. Soc., to 
 point out the probability that the English Channel has not 
 been excavated by water-action only ; but owes its origin to 
 one of the lines of disturbance which have fissured this portion 
 of the earth's crust : and taking this view of the case, the fis- 
 sure probably still exists, being merely filled with compara- 
 tively loose material, so as to prove a serious obstacle to any 
 attempt made to drive through it a submarine tunnel. Pro- 
 ceedings of the Geological Society. 
 
 HOW BOULDERS ARE TRANSPORTED TO GREAT HEIGHTS. 
 
 Sir Roderick Murchison has shown that in Russia, when 
 the Dwina is at its maximum height, and penetrates into the 
 chinks of its limestone banks, when frozen and expanded 
 it causes disruptions of the rock, the entanglement of stony 
 fragments in the ice. In remarkable spring floods, the stream 
 so expands that in bursting it throws up its icy fragments to 
 15 or 20 feet above the stream ; and the waters subsiding, 
 these lateral ice-heaps melt away, and leave upon the bank the 
 rifled and angular blocks as evidence of the highest ice-mark. 
 In Lapland, M. Bohtlingk assures us that he has found large 
 granitic boulders weighing several tons actually entangled and 
 suspended, like birds'-nests, in the branches of pine-trees, at heights 
 of 30 or 40 feet above the summer level of the stream !* 
 
 * Mr. Hopkins supports his Glacial Theory by regarding the Waves of Trans- 
 lation, investigated by Mr. Scott Kussell, as furnishing a sufficient moving power 
 for the transportation of large rounded boulders, and the formation of drifted 
 gravel. When these waves of translation are produced by the sudden elevation 
 of the sin-face of the sea, the whole mass of water from the surface to the bottom 
 of the ocean moves onward, and becomes a mechanical agent of enormous power. 
 Following up this view. Mr. Hopkins has shown that " elevations of continental 
 masses of only 50 feet each, and from beneath an ocean having a depth of be- 
 tween 300 and 400 feet, would cause the most powerful divergent waves, which 
 could transport large boulders to great distances." 
 
106 Things not generally Known. 
 
 WHY SEA-SHELLS ABE FOUND AT GREAT HEIGHTS. 
 
 The action of subterranean forces in breaking through and 
 elevating strata of sedimentary rocks, of which the coast of 
 Chili, in consequence of a great earthquake, furnishes an ex- 
 ample, leads to the assumption that the pelagic shells found 
 by MM. Bonpland and Humboldt on the ridge of the Andes, at 
 an elevation of more than 15,000 English feet, may have been 
 conveyed to so extraordinary a position, not by a rising of the 
 ocean, but by the agency of volcanic forces capable of elevating 
 into ridges the softened crust of the earth. 
 
 SAND OF THE SEA AND DESERT. 
 
 That sand is an assemblage of small stones may be seen 
 with the eye unarmed with art ; yet how few are equally aware 
 of the synonymous nature of the sand of the sea and of the 
 land ! Quartz, in the form of sand, covers almost entirely the 
 bottom of the sea. It is spread over the banks of rivers, and 
 forms vast plains, even at a very considerable elevation above 
 the level of the sea, as the desert of Sahara in Africa, of Kobi 
 in Asia, and many others. This quartz is produced, at least 
 in part, from the disintegration of the primitive granite rocks. 
 The currents of water carry it along, and when it is in very 
 small, light, and rounded grains, even the wind transports it 
 from one place to another. The hills are thus made to move 
 like waves, and a deluge of sand frequently inundates the 
 neighbouring countries : 
 
 " So where o'er wide Numidian wastes extend, 
 Sudden the impetuous hurricanes descend." Addisoris C'ato. 
 
 To illustrate the trite axiom, that nothing is lost, let us 
 glance at the most important use of sand : 
 
 "Quartz in the form of sand," observes Maltebrun, "furnishes, by 
 fusion, one of the most useful substances we have, namely glass, which, 
 being less hard than the crystals of quartz, can be made equally trans- 
 parent, and is equally serviceable to our wants and to our pleasures. 
 There it shines in walls of crystal in the palaces of the great, reflecting 
 the charms of a hundred assembled beauties ; there, in the hand of the 
 philosopher, it discovers to us the worlds that revolve above us in the 
 immensity of space, and the no less astonishing wonders that we tread 
 beneath our feet." 
 
 PEBBLES. 
 
 The various heights and situations at which Pebbles are 
 found have led to many erroneous conclusions as to the period 
 of changes of the earth's surface. All the banks of rivers and 
 lakes, and the shores of the sea, are covered with pebbles, 
 rounded by the waves which have rolled them against each 
 
Curiosities of Science. 107 
 
 other, and which frequently seem to have brought them from 
 a distance. There are also similar masses of pebbles found 
 at very great elevations, to which the sea appears never to 
 have been able to reach. We find them in the Alps at Valor- 
 sina, more than 6000 feet above the level of the sea ; and on 
 the mountain of Bon Homme, which is more than 1000 feet 
 higher. There are some places little elevated above the level 
 of the sea, which, like the famous plain of Crau, in Provence, 
 are entirely paved with pebbles ; while in Norway, near Qued- 
 lia, some mountains of considerable magnitude seem to be 
 completely formed of them, and in such a manner that the 
 largest pebbles occupy the summit, and their thickness and 
 size diminish as you approach the base. We may include in 
 the number of these confused and irregular heaps most of the 
 depositions of matter brought by the river or sea, and left on 
 the banks, and perhaps even those immense beds of sand which 
 cover the centre of Asia and Africa. It is this circumstance 
 which renders so uncertain the distinction, which it is never- 
 theless necessary to establish, between alluvial masses created 
 before the commencement of history, and those which we see 
 still forming under our own eyes. 
 
 A charming monograph, entitled " Thoughts on a Pebble," 
 full of playful sentiment and graceful fancy, has been written 
 by the amiable .Dr. Mautell, the geologist. 
 
 ELEVATION OF MOUNTAIN-CHAINS. 
 
 Professor Ansted, in his Ancient World, thus characterises 
 this phenomenon : 
 
 These movements, described in a few words, were doubtless going 
 on for many thousands and tens of thousands of revolutions of our 
 planet. They were accompanied also by vast but slow changes of other 
 kinds. The expansive force employed in lifting up, by mighty move- 
 ments, the northern portion of the continent of Asia, found partial vent; 
 and from partial subaqueous fissures there were poured out the tabular 
 masses of basalt occurring in Central India ; while un extensive area of 
 depi'ession in the Indian Ocean, marked by the coral islands of the 
 Laccadives, the Maldives, the great Chagos bank, and some others, were 
 in the course of depression by a counteracting movement. 
 
 Hitherto the processes of denudation and of elevation have 
 been so far balanced as to preserve a pretty steady proportion 
 of sea and dry laud during geological ages ; but if the internal 
 temperature should be so far reduced as to be no longer ca- 
 pable of generating forces of expansion sufficient for this ele- 
 vatory action, while the denuding forces should continue to 
 act with unabated energy, the inevitable result would be, that 
 every mountain-top would be in time brought low. No earthly 
 barrier could declare to the ocean that there its proud waves 
 should be stayed. Nothing would stop its ravages till all dry 
 
108 Things not generally Known. 
 
 land should be laid prostrate, to form the bed over which it 
 would continue to roll an uninterrupted sea. 
 
 THE CHALK FORMATION. 
 
 Mr. Horner, F.R.S.. among other things in his researches 
 in the Delta, considers it extremely probable that every par- 
 ticle of Chalk in the world has at some period been circulating 
 in the system of a living animal. 
 
 WEAR OF BUILDING- STONES. 
 
 Professor Henry, in an account of testing the marbles used 
 in building the Capitol at Washington, states that evrey flash 
 of lightning produces an appreciable amount of nitric acid, 
 which, diffused in rain-water, acts on the carbonate of lime ; 
 and from specimens subjected to actual freezing, it was found 
 that in ten thousand years one inch would be worn from the 
 blocks by the action of frost. 
 
 In 1839, a report of the examination of Sandstones, Limestones, 
 and Oolites of Britain was made to the Government, with a view 
 to the selection of the best material for building the new Houses of 
 Parliament. For this purpose, 103 quarries were described, 96 build- 
 ings in England referred to, many chemical analyses of the stones were 
 given, and a great number of experiments related, showing, among 
 other points, the cohesive power of each stone, and the amount of dis- 
 integration apparent, when subjected to Brard's process. The magne- 
 sian limestone, or dolomite of Bolsover Moor, was recommended, and 
 finally adopted far the Bouses ; but the selection does not appear to 
 have been so successful as might have been expected from the skill and 
 labour of the investigation. It may be interesting to add, that the 
 publication of the above Report (for which see Year-Book of Facts, 1840, 
 pp. 78-80) occasioned Mr John Mallcott to remark in the Times journal, 
 " that all stone made use of in the immediate neighbourhood of its own 
 quarries is more likely to endure that atmosphere than if it be removed 
 therefrom, though only thirty or forty miles :" and the lapse of com- 
 paratively few years has proved the soundness of this observation.* 
 
 PHENOMENA OF GLACIERS ILLUSTRATED. 
 
 Professor Tyndall, being desirous of investigating some of 
 the phenomena presented by the large masses of mountain-ice, 
 those frozen rivers called Glaciers, devised the plan of send- 
 ing a destructive agent into the midst of a mass of ice, so as 
 to break down its structure in the interior, in order to see if 
 this method would reveal any thing of its internal constitu- 
 tion. Taking advantage of the bright weather of 1857, he con- 
 centrated a beam of sunlight by a condensing lens, so as to 
 
 It is scarcely too much to say, that from the collection of specimens of 
 building-stones made upon this occasion, and first deposited in a house in Craig's 
 Court, Charing Cross, originated, upon the suggestion of sir Henry Delabeche, 
 the magnificent Museum of Practical Geology in Jermyn Street; one of the most 
 eminently practical institutions of this scientific age. 
 
Curiosities of Science. 109 
 
 form the focus of the sun's rays in the midst of a mass of ice. 
 A portion of the ice was melted, but the surrounding parts 
 shone out as brilliant stars, produced by the reflection of the 
 faces of the crystalline structure. On examining these bril- 
 liant portions with a lens, Professor Tyndall discovered that 
 the structure of the ice had been broken down in symmetrical 
 forms of great beauty, presenting minute stars, surrounded by 
 six petals, forming a beautiful flower, the plane being always 
 parallel to the plane of congelation of the ice. He then pre- 
 pared a piece of ice, by making both its surfaces smooth and 
 parallel to each other. He concentrated in the centre of the 
 ice the rays of heat from the electric light ; and then, placing 
 the piece of ice in the electric microscope, the disc revealed 
 these beautiful ice-flowers. 
 
 A mass of ice was crushed into fragments ; the small frag- 
 ments were then placed in a cup of wood ; a hollow wooden 
 die, somewhat smaller than the cup, was then pressed into the 
 cup of ice-fragments by the pressure of a hydraulic press, and 
 the ice-fragments were immediately united into a compact cup 
 of nearly transparent ice. This pressure of fragments of ice 
 into a solid mass explains the formation of the glaciers and 
 their origin. They are composed of particles of ice or snow ; 
 as they descend the sides of the mountain, the pressure of 
 the snow becomes sufficiently great to compress the mass into 
 solid ice, until it becomes so great as to form the beautiful 
 blue ice of the glaciers. This compression, however, will not 
 form the solid mass unless the temperature of the ice be 
 near that of freezing water. To prove this, the lecturer cooled 
 a mass of ice, by wrapping it in a piece of tinfoil and ex- 
 posing it for some time to a bath of the ethereal solution of 
 solidified carbonic-acid gas, the coldest freezing mixture known. 
 This cooled mass of ice was crushed to fragments, and sub- 
 mitted to the same pressure which the other fragments had 
 been exposed to without cohering in the slightest degree. 
 Lecture at the Royal Institution^ 1858. 
 
 ANTIQUITY OF GLACIEES. 
 
 The importance of glacier agency in the past as well as 
 the present condition of the earth, is undoubtedly very great. 
 One of our most accomplished and ingenious geologists has. 
 indeed, carried back the existence of Glaciers to an epoch of 
 dim antiquity, even in the reckoning of that science whose 
 chronology is counted in millions of years. Professor Ramsay 
 has shown ground for believing that in the fragments of rock 
 that go to make up the conglomerates of the Permian strata, 
 intermediate between the Old and the New Red Sandstone, 
 there is still preserved a record of the action of ice, either in 
 
110 Things not generally Known. 
 
 glaciers or floating icebergs, before those strata were consoli- 
 dated. Saturday Review, No. 142. 
 
 FLOW OF THE HER DE GLACE. 
 
 Michel Devouasson of Ghamouni fell into a crevasse on the 
 Glacier of Talefre, a feeder of the Mer de Glace, on the 29th 
 of July 1836, and after a severe struggle extricated himself, 
 leaving his knapsack below. The identical knapsack reap- 
 peared in July 1846, at a spot on the surface of the glacier 
 four thousand three hundred feet from the place where it was 
 lost, as ascertained by Professor Forbes, who himself collected 
 the fragments ; thus indicating the rate of flow of the icy river 
 in the intervening ten years. Quarterly Review,, No. 202. 
 
 THE ALLUVIAL LAND OF EGYPT : ANCIENT POTTERY. 
 
 Mr. L. Horner, in his recent researches near Cairo, with the 
 view of throwing light upon the geological history of the allu- 
 vial land of Egypt, obtained from the lowest part of the boring 
 of the sediment at the colossal statue of Rameses, at a depth of 
 thirty-nine feet, this curious relic of the ancient world ; the 
 boring instrument bringing up a fragment of pottery about an 
 inch square and a quarter of an inch in thickness the two 
 surfaces being of a brick-red colour, the interior dark gray. 
 According to Mr. Homer's deductions, this fragment, having 
 been found at a depth of 39 feet (if there be no fallacy in his 
 reasoning), must be held to be a record of the existence of man 
 13,375 years before A.D. 1858, reckoning by the calculated rate 
 of increase of three inches and a half of alluvium in a century 
 11,517 years before the Christian era, and 7625 before the 
 beginning assigned by Lepsius to the reign of Menos, the 
 founder of Memphis. Moreover it proves in his opinion, that 
 man had already reached a state of civilisation, so far at least 
 as to be able to fashion clay into vessels, and to know how 
 to harden it by the action of strong heat. This calculation is 
 supported by the Chevalier Bunsen, who is of opinion that the 
 first epochs of the history of the human race demand at the 
 least a period of 20,000 years before our era as a fair starting- 
 point in the earth's history. Proceedings of Royal Soc., 1858. 
 
 Upon this theory, a Correspondent, "An Old Indigo -Planter," writes 
 to the Atkenoeum, No. 1509, the following suggestive note : " Having lived 
 many years on the banks of the Ganges, I have seen the stream encroach 
 on a' village, undermining the bank where it stood, and deposit, as a 
 natural result, bricks, pottery, &c. in the bottom of the stream. On 
 one occasion, I am certain that the depth of the stream where the bank 
 was breaking was above 40 feet ; yet in three years the current of the 
 river drifted so much, that a fresh deposit of soil took place over the 
 debris of the village, and the earth was raised to a level with the old 
 bank. Now had our traveller then obtained a bit of pottery from where 
 it had lain for only three years, could he reasonably draw the inference 
 that it had been made 13,000 years before ?" 
 
Curiosities of Science. Ill 
 
 SUCCESSIVE CHANGES OF THE TEMPLE OF SEEAPIS. 
 
 The Temple of Serapis at Puzzuoli, near Naples, is per- 
 haps, of all the structures raised by the hands of man, the one 
 which affords most instruction to a geologist. It has not only 
 undergone a wonderful succession of changes in past time, but 
 is still undergoing changes of condition. This edifice was ex- 
 humed in 1750 from the eastern shore of the Bay of Baise, con- 
 sisting partly of strata containing marine shells with frag- 
 ments of pottery and sculpture, and partly of volcanic matter 
 of sub-aerial origin. Various theories were proposed in the last 
 century to explain the perforations and attached animals ob- 
 served on the middle zone of the three erect marble columns 
 until recently standing ; Goethe, among the rest, suggesting 
 that a lagoon had once existed in the vestibule of the temple, 
 filled during a temporary incursion of the sea with salt water, 
 and that marine mollusca and annelids flourished for years in 
 this lagoon at twelve feet or more above the sea-level. 
 
 This hypothesis was advanced at a time when almost any 
 amount of fluctuation in the level of the sea was thought more 
 probable than the slightest alteration in the level of the solid 
 land. In 1807 the architect Niccolini observed that the pave- 
 ment of the temple was dry, except when a violent south wind 
 was blowing ; whereas, on revisiting the temple fifteen years 
 later, he found the pavement covered by salt water twice every- 
 day at high tide. From measurements made from 1822 to 
 1838, and thence to 1845, he inferred that the sea was gaining 
 annually upon the floor of the temple at the rate of about one- 
 third of an inch during the first period, and about three-fourths 
 of an inch during the second. Mr. Smith of Jordan Hill, from 
 his visits in 1819 and 1845, found an average rise of about an 
 inch annually, which was in accordance with visits made by 
 Mr. Babbage in 1828, and Professor James Forbes in 1826 and 
 1843. In 1852 Signor Scaecchi, at the request of Sir Charles 
 Lyell, compared the depth of water on the pavement with its 
 level taken by him in 1839, and found that it had gained only 
 4\ inches in thirteen years, and was not so deep as when MM. 
 Niccolini and Smith measured it in 1845 ; from which he in- 
 ferred that after 1845 the downward movement of the land 
 had ceased, and before 1852 had been converted into an up- 
 ward movement. 
 
 Arago and others maintained that the surface on which the 
 temple stands has been depressed, has remained under the sea, 
 and has again been elevated. Russager, however, contends that 
 there is nothing in the vicinity of the temple, or in the temple 
 itself, to justify this bold hypothesis. Every thing leads to the 
 belief that the temple has remained unchanged in the position 
 
Things not generally Known. 
 
 in which it was originally built ; but that the sea rose, sur- 
 rounded it to a height of at least twelve feet, and again re- 
 tired ; but the elevated position of the sea continued sufficiently 
 long to admit of the animals boring the pillars. This view can 
 even be proved historically; for Niccolini, in a memoir pub- 
 lished in 1840, gives the heights of the level of the sea in the 
 Bay of Naples for a period of 1900 years, and has with much 
 acuteness proved his assertions historically. The correctness 
 of Russager's opinion, he states, can be demonstrated and re- 
 duced to figures by means of the dates collected by Niccolini. 
 
 See Jameson s Journal, No. 58. 
 
 At the present time the floor is always covered with sea- water. 
 On the whole, there is little doubt that the ground has sunk 
 upwards of two feet during the last half -century. This gradual 
 subsidence confirms in a remarkable manner Mr. Babbage's 
 conclusions drawn from the calcareous incrustations formed 
 by the hot springs on the walls of the building and from the 
 ancient lines of the water-level at the base of the three columns 
 
 that the original subsidence was not sudden, but slow and 
 by successive movements. 
 
 Sir Charles Lyell (who, in his Principles of Geology, has 
 given a detailed account of the several upfillings of the temple) 
 considers that when the mosaic pavement was re-constructed, 
 the floor of the building must have stood about twelve feet 
 above the level of 1838 (or about 11 5 feet above the level of the 
 sea), and that it had sunk about nineteen feet below that level 
 before it was elevated by the eruption of Monte Nuovo. 
 
 We regret to add, that the columns of the temple are no 
 longer in the position in which they served so many years as a 
 species of self-registering hydrometer : the materials have been 
 newly arranged, and thus has been torn as it were from history 
 a page which can never be replaced. 
 
 THE GROTTO DEL CANE. 
 
 This " Dog Grotto" has been so much cited for its stratum 
 of carbonic-acid gas covering the floor, that all geological tra- 
 vellers who visit Naples feel an interest in seeing the wonder. 
 
 This cavern was known to Pliny. It is continually exhaling 
 from its sides and floor volumes of steam mixed with carbonic- 
 acid gas ; but the latter, from its greater specific gravity, accu- 
 mulates at the bottom, and flows over the step of the door. 
 The upper part of the cave, therefore, is free from the gas, 
 while the floor is completely covered by it. Addison, on his 
 visit, made some interesting experiments. He found that a 
 pistol could not be fired at the bottom ; and that on laying a 
 train of gunpowder and igniting it on the outside of the ca- 
 vern, the carbonic-acid gas " could not intercept the train of 
 
Curiosities of Science. 113 
 
 fire when it once began flashing, nor hinder it from running to 
 the very end." He found that a viper was nine minutes in 
 dying on the first trial, and ten minutes on the second ; this 
 increased vitality being, in his opinion, attributable to the 
 stock of air which it had inhaled after the first trial. Dr. 
 Daubeny found that phosphorus would continue lighted at 
 about two feet above the bottom ; that a sulphur-match went 
 out in a few minutes above it, and a wax-taper at a still higher 
 level. The keeper of the cavern has a dog, upon which he 
 shows the effects of the gas, which, however, are quite as well, 
 if not better, seen in a torch, a lighted candle, or a pistol. 
 
 " Unfortunately," says Professor Silliman, "like some other 
 grottoes, the enchantment of the ' Dog Grotto' disappears on 
 a near view." It is a little hole dug artificially in the side of a 
 hill facing Lake Agnano : it is scarcely high enough for a per- 
 son to stand upright in, and the aperture is closed by a door. 
 Into this narrow cell a poor little dog is very unwillingly dragged 
 and placed in a depression of the floor, where he is soon nar- 
 cotised by the carbonic acid. The earth is warm to the hand, 
 and the gas given out is very constant. 
 
 THE WATERS OF THE GLOBE GRADUALLY DECREASING. 
 
 This was maintained by M. Bory Saint Vincent, because 
 the vast deserts of sand, mixed up with the salt and remains of 
 marine animals, of which the surface of the globe is partly com- 
 posed, were formerly inland seas, which have insensibly become 
 dry. The Caspian, the Dead Sea, the Lake Baikal, &c. will 
 become dry in their turn also, when their beds will be sandy 
 deserts. The inland seas, whether they have only one outlet, 
 as the Mediterranean, the Red Sea, the Baltic, &c., or whether 
 they have several, as the Gulf of Mexico, the seas of O'Kotsk, 
 of Japan, China, &c., will at some future time cease to com- 
 municate with the great basins of the ocean ; they will become 
 inland seas, true Caspians, and in due time will become like- 
 wise dry. On all sides the waters of rivers are seen to carry 
 forward in their course the soil of the continent. Alluvial 
 lands, deltas, banks of sand, form themselves near the coasts, 
 and in the directions of the currents ; madreporic animals lay 
 the foundations of new lands ; and while the straits become 
 closed, while the depths of the sea fill up, the level of the sea, 
 which it would seem natural should become higher, is sensibly 
 lower. There is, therefore, an actual diminution of liquid 
 matter. 
 
 THE SALT LAKE OF UTAH. 
 
 Lieutenant Gunnison, who has surveyed the great basin of 
 the Salt Lake, states the water to be about one-third salt, 
 
 i 
 
114 Things not generally Known. 
 
 which it yields on boiling. Its density is considerably greater 
 than that of the Red Sea. One can hardly get the whole body 
 below the surface : in a sitting position the head and shoulders 
 will remain above the water, such is the strength of the brine ; 
 and on coming to the shore the body is covered with an incrus- 
 tation of salt in tine crystals. During summer the lake throws 
 on shore abundance of salt, while in winter it throws up Glau- 
 ber salt plentifully. " The reason of this," says Lieutenant 
 Gunnison, " is left for the scientific to judge, and also what 
 becomes of the enormous amount of fresh water poured into it 
 by three or four large rivers, Jordan, Bear, and Weber, as 
 there is no visible effect." 
 
 FOECE OF RUNNING WATER. 
 
 It has been proved by experiment that the rapidity at the 
 bottom of a stream is every where less than in any other part of 
 it, and is greatest at the surface. Also, that in the middle of 
 the stream the particles at the top move swifter than those at 
 the sides. This slowness of the lowest and side currents is pro- 
 duced by friction ; and when the rapidity is sufficiently great, 
 the soil composing the sides and bottom gives way. If the water 
 flows at the rate of three inches per second, it will tear up fine 
 clay ; six inches per second, fine sand ; twelve inches per second, 
 fine gravel; and three feet per second, stones the size of an 
 egg. Sir Charles Lyell. 
 
 THE ARTESIAN WELL OF GRENELLE AT PARIS. 
 
 M. Peligot has ascertained that the Water of the Artesian 
 Well of Grenelle contains not the least trace of air. Subterra- 
 nean waters ought therefore to be aerated before being used as 
 aliment Accordingly, at Grenelle, has been constructed a 
 tower, from the top of which the water descends in innumer- 
 able threads, so as to present as much surface as possible to 
 the air. 
 
 The boring of this Well by the Messrs. Mulct occupied seven 
 years, one month, twenty-six days, to the depth of 1794| Eng- 
 lish feet, or 194 feet below the depth at which M. Elie de 
 Beaumont foretold that water would be found. The sound, or 
 borer, weighed 20,000 lb., and was treble the height of that of 
 the dome of the Hdpital des Invalids at Paris. In May 1837, 
 when the bore had reached 1246 feet 8 inches, the great chisel 
 and 262 feet of rods fell to the bottom ; and although these 
 weighed five tons, M. Mulot tapped a screw on the head of the 
 rods, and thus, connecting another length to them, after fifteen 
 months' labour, drew up the chisel. On another occasion, this 
 chisel having been raised with great force, sank at one stroke 
 35 feet 3 inches into the chalk ! 
 
Curiosities of Science. 115 
 
 The depth of the Grenelle Well is nearly four times the height of 
 Strasburg Cathedral ; more than six times the height of the H6pital 
 des Invalides at Paris ; more than four times the height of St. Peter's 
 at Rome; nearly four times and a half the height of St. Paul's, and nine 
 times the height of the Monument, London. Lastly, suppose all the 
 above edifices to be piled one upon each other, from the base-line of the 
 Well of Grenelle, and they would but reach within 11 feet of its surface. 
 
 MM. Elie de Beaumont and Arago never for a moment doubted the 
 final success of the work ; their confidence being based on analogy, and 
 on a complete acquaintance with the geological structure of the Paris 
 basin, which is identical with that of the London basin beneath the 
 London clay. 
 
 In the duchy of Luxembourg is a well the depth of which surpasses 
 all others of the kind. It is upwards of 1000 feet more than that of 
 Grenelle near Paris. 
 
 HOW THE GULF- STREAM REGULATES THE TEMPERATURE OF 
 LONDON. 
 
 Great Britain is almost exactly under the same latitude as 
 Labrador, a region of ice and snow. Apparently, the chief 
 cause of the remarkable difference between the two climates 
 arises from the action of the great oceanic Gulf-Stream, whereby 
 this country is kept constantly encircled with waters warmed 
 by a West- Indian sun. 
 
 Were it not for this unceasing current from tropical seas, London, 
 instead of its present moderate average winter temperature of 6 above 
 the freezing-point, might for many months annually be ice-bound by a 
 settled cold of 10 to 30 J below that point, and have its pleasant summer 
 months replaced by a season so short as not to allow corn to ripen, or 
 only an alpine vegetation to flourish. 
 
 Nor are we without evidence afforded by animal life of a greater 
 cold having prevailed in this country at a late geological period. One 
 case in particular occurs within eighty miles of London, at the village 
 of Chillesford, near Woodbridge, where, in a bed of clayey sand of an 
 age but little (geologically speaking) anterior to the London gravel, Mr. 
 Prestwich has found a group of fossil shells in greater part identical 
 with species now living in the seas of Greenland and of similar latitudes, 
 and which must evidently, from their perfect condition and natural 
 position, have existed in the place where they are now met with. Lec- 
 tures on the Geology of Ctapham, &c. by Joseph Prestwich, A.R.S., F.G,S. 
 
 SOLVENT ACTION OF COMMON SALT AT HIGH TEMPERATURES. 
 
 Forchhammer, after a long series of experiments, has come 
 to the conclusion that Common Salt at high temperatures, such 
 as prevailed at earlier periods of the earth's history, acted as 
 a general solvent, similarly to water at common temperatures. 
 The amount of common salt in the earth would suffice to cover 
 its whole surface with a crust ten feet in thickness. 
 
 FREEZING CAVERN IN RUSSIA. 
 
 This famous Cavern, at Ithetz Kaya-Zastchita, in the Steppes 
 
116 Things not generally Known. 
 
 of the Kirghis, is employed by the inhabitants as a cellar. It 
 has the very remarkable property of being so intensely cold 
 during the hottest summers as to be then filled with ice, which 
 disappearing with cold weather, is entirely gone in winter, when 
 all the country is clad in snow. The roof is hung with ever- 
 dripping solid icicles, and the floor may be called a stalagmite 
 of ice and frozen earth. " If," says Sir R. Murchison, " as we 
 were assured, the cold is greatest when the external air is hottest 
 and driest, that the fall of rain and a moist atmosphere produce 
 some diminution of the cold in the cave, and that upon the set- 
 ting-in of winter the ice disappears entirely, then indeed the 
 problem is very curious." The peasants assert that in winter 
 they could sleep in the cave without their sheepskins. 
 
 INTERIOR TEMPERATURE OF THE EARTH : CENTRAL HEAT. 
 
 By the observed temperature of mines, and that at the bot- 
 tom of artesian wells, it has been established that the rate at 
 which such temperature increases as we descend varies consi- 
 derably in different localities, where the depths are compara- 
 tively small ; Hbut where the depths are great, we find a much 
 nearer approximation to a common rate of increase, which, as 
 determined by the best observation in the deepest mines, shafts, 
 and artesian wells in Western Europe, is very nearly 1 F. for 
 an increase in depth of fifty feet* W. Hopkins, M.A., F.R.S. 
 
 Humboldt states that, according to tolerably coincident 
 experiments in artesian wells, it has been shown that the heat 
 increases on an average about 1 for every 54*5 feet. If this 
 increase can be reduced to arithmetical relations, it will follow 
 that a stratum of granite would be in a state of fusion at a 
 depth of nearly twenty-one geographical miles, or between 
 four and five times the elevation of the highest summit of the 
 Himalaya. 
 
 The following is the opinion of Professor Silliman : 
 That the whole interior portion of the earth, or at least a great part 
 of it, is an ocean of melted rock, agitated by violent winds, though I 
 dare not affirm it, is still rendered highly probable by the phenomena 
 of volcanoes. The facts connected with their eruption have been ascer- 
 tained and placed beyond a doubt. How, then, are they to be accounted 
 for ? The theory prevalent some years since, that they are caused by 
 the combustion of immense coal-beds, is puerile and now entirely aban- 
 doned. All the coal in the world could not afford fuel enough for one 
 of the tremendous eruptions of Vesuvius. 
 
 This observed increase of temperature in descending be- 
 neath the earth's surface suggested the notion of a central 
 incandescent nucleus still remaining in a state of fluidity from 
 its elevated temperature. Hence the theory that the whole 
 mass of the earth was formerly a molten fluid mass, the exte- 
 rior portion of which, to some unknown depth, has assumed 
 
Curiosities of Science. 117 
 
 its present solidity by the radiation of heat into surrounding 
 space, and its consequent refrigeration. 
 
 The mathematical solution of this problem of Central Heat, 
 assuming such heat to exist, tells us that though the central 
 portion of the earth may consist of a mass of molten matter, 
 the temperature of its surface is not thereby increased by more 
 than the small fraction of a degree, Poisson has calculated 
 that it would require a thousand millions of centuries to reduce 
 this fraction to a degree by half its present amount, supposing 
 always the external conditions to remain unaltered. In such 
 cases, the superficial temperature of the earth may, in fact, be 
 considered to have approximated so near to its ultimate limit 
 that it can be subject to no further sensible change. 
 
 DISAPPEAEANCE OF VOLCANIC ISLANDS. 
 
 Many of the Volcanic Islands thrown up above the sea-level 
 soon disappear, because the lavas and conglomerates of which 
 they are formed spread over flatter surfaces, through the weight 
 of the incumbent fluid ; and the constant levelling process goes 
 on below the sea by the action of tides and currents. Such 
 islands as have effectually resisted this action are found to 
 possess a solid framework of lava, supporting or defending the 
 loose fragmentary materials. 
 
 Among the most celebrated of these phenomena in our times may be 
 mentioned the Isle of Sabrina, which rose off the coast of St. Michael's 
 in 1811, attained a circumference of one mile and a height of 300 feet, 
 and disappeared in less than eight months ; in the following year there 
 were eighty fathoms of water in its place. In July 1831 appeared Gra- 
 ham's Island off the coast of Sicily, which, attained a mile in circum- 
 ference and 150 or 160 feet in height ; its formation much resembled 
 that of Sabrina. 
 
 The line of ancient subterranean fire which we trace on the 
 Mediterranean coasts has had a strange attestation in Graham's 
 Island, which is also described as a volcano suddenly bursting 
 forth in the mid sea between Sicily and Africa ; burning for 
 several weeks, and throwing up an isle, or crater-cone of scorise 
 and ashes, which had scarcely been named before it was again 
 lost by subsidence beneath the sea, leaving only a shoal-bank 
 to attest this strange submarine breach in the earth's crust, 
 which thus mingled fire and water in one common action. 
 
 Floating islands are not very rare : in 1827, one was seen 
 twenty leagues to the east of the Azores ; it was three leagues 
 in width, and covered with volcanic products, sugar-canes, 
 straw, and pieces of wood. 
 
 PERPETUAL FIRE. 
 
 Not far from the Deliktash, on the side of a mountain in 
 Lycia, is the Perpetual Fire described some forty years since 
 
118 Things not generally Known. 
 
 by Captain Beaufort. It was found by Lieutenant Spratt and 
 Professor Forbes, thirty years later, as brilliant as ever, and 
 somewhat increased ; for besides the large flame in the corner 
 of the ruins described by Beaufort, there were small jets issuing 
 from crevices in the side of the crater- like cavity five or six feet 
 deep. At the bottom was a shallow pool of sulphureous and 
 turbid water, regarded by the Turks as a sovereign remedy for 
 all skin complaints. The soot deposited from the flames was 
 held to be efficacious for sore eyelids, and valued as a dye for 
 the eyebrows. This phenomenon is described by Pliny as the 
 flame of the Lycian Chimera. 
 
 AETESIAN FIRE- SPRINGS IN CHINA. 
 
 According to the statement of the missionary Imbert, the 
 Fire-Springs, " Ho-tsing" of the Chinese, which are sunk to 
 obtain a carburetted-hydrogen gas for salt-boiling, far exceed 
 our artesian springs in depth. These springs are very com- 
 monly more than 2000 feet deep ; and a spring of continued 
 flow was found to be 3197 feet deep. This natural gas has 
 been used in the Chinese province Tse-tschuan for several 
 thousand years ; and "portable gas" (in bamboo-canes) has for 
 ages been used in the city of Khiung-tscheu. More recently, 
 in the village of Fredonia, in the United States, such gas has 
 been used both for cooking and for illumination. 
 
 VOLCANIC ACTION THE GREAT AGENT OF GEOLOGICAL 
 CHANGE. 
 
 Mr. James Nasmyth observes, that " the floods of molten lava which 
 volcanoes eject are nothing less than remaining 1 portions of what was 
 once the condition of the entire globe when in the igneous state of its 
 early physical history, no one knows how many years ago ! 
 
 " When we behold the glow and feel the heat of molten lava, how 
 vastly does it add to the interest of the sight when we consider that the 
 heat we feel and the light we see are the residue of the once universal 
 condition of our entire globe, on whose cooled surface we now live and 
 have our being ! But so it is ; for if there be one great fact which geo- 
 logical research has established beyond all doubt, it is that we reside 
 on the cooled surface of what was once a molten globe, and that all the 
 phenomena which geology has brought to light can be most satisfac- 
 torily traced to the successive changes incidental to its gradual cooling 
 and contraction. 
 
 '" That the influx of the sea into the yet hot and molten interior of 
 the globe may occasionally occur, and enhance and vary the violence of 
 the phenomenon of volcanic action, there can be little doubt ; but the 
 action of water in such cases is only secondary. But for the pre-existing 
 high temperature of the interior of the earth, the influx of water would 
 produce no such discharges of molten lava as generally characterise vol- 
 canic eruptions. Molten lava is therefore a true vestige of the Natural 
 History of the Creation." 
 
Curiosities of Science. 1 1 9 
 
 THE SNOW-CAPPED VOLCANO. 
 
 It is but rarely that the elastic forces at work within the 
 interior of our globe have succeeded in breaking through the 
 spiral domes which, resplendent in the brightness of eternal 
 snow, crown the summits of the Cordilleras ; and even where 
 these subterranean forces have opened a permanent communi- 
 cation with the atmosphere, through circular craters or long 
 fissures, they rarely send forth currents of lava, but merely 
 eject ignited scoriae, steam, sulphuretted hydrogen gas, and 
 jets of carbonic acid. Humboldt's Cosmos, vol. i. 
 
 TRAVELS OF VOLCANIC DUST. 
 
 On the 2d of September 1845, a quantity of Volcanic Dust 
 fell in the Orkney Islands, which was supposed to have origin- 
 ated in an eruption of Hecla, in Iceland. It was subsequently 
 ascertained that an eruption of that volcano took place on the 
 morning of the above day (September 2), so as to leave no 
 doubt of the accuracy of the conclusion. The dust had thus 
 travelled about 600 miles ! 
 
 GEEAT ERUPTIONS OF VESUVIUS. 
 
 In the great eruption of Vesuvius, in August 1779, which 
 Sir William Hamilton witnessed from his villa at Pausilippo 
 in the bay of Naples, the volcano sent up white sulphureous 
 smoke resembling bales of cotton, exceeding the height and 
 size of the mountain itself at least four times ; and in the midst 
 of this vast pile of smoke, stones, scoriae, and ashes were thrown 
 up not less than 2000 feet. Next day a fountain of fire shot 
 up with such height and brilliancy that the smallest objects 
 could be clearly distinguished at any place within six miles or 
 more of Vesuvius. But on the following day a more stupen- 
 dous column of fire rose three times the height of Vesuvius 
 (3700 feet), or more than two miles high. Among the huge 
 fragments of lava thrown out during this eruption was a block 
 108 feet in circumference and 17 feet high, another block 
 66 feet in circumference and 19 feet high, and another 16 feet 
 high and 92 feet in circumference, besides thousands of smaller 
 fragments. Sir William Hamilton suggests that from a scene 
 of the above kind the ancient poets took their ideas of the 
 giants waging war with Jupiter. 
 
 The eruption of June 1794, which destroyed the greater 
 part of the town of Torre del Greco, was, however, the most 
 violent that has been recorded after the two great eruptions of 
 79 and 1631. 
 
 EARTH-WAVES. 
 
 The waves of an earthquake have been represented in their 
 
120 Things not generally Known. 
 
 progress, and their propagation, through rocks of different 
 density and elasticity ; and the causes of the rapidity of pro- 
 pagation, and its diminution by the refraction, reflection, and 
 interference of the oscillations have been mathematically in- 
 vestigated. Air, water, and earth waves follow the same laws 
 which are recognised by the theory of motion, at all events in. 
 space ; but the earth- waves are accompanied in their destruc- 
 tive action by discharges of elastic vapours, and of gases, and 
 mixtures of pyroxene crystals, carbon, and infusorial animal- 
 cules with silicious shields. The more terrific effects are, how- 
 ever, when the earth-waves are accompanied by cleavage ; and, 
 as in the earthquake of Riobamba, when fissures alternately 
 opened and closed again, so that men saved themselves by ex- 
 tending both arms, in order to prevent their sinking. 
 
 As a remarkable example of the closing of a fissure, Hum- 
 boldt mentions that, during the celebrated earthquake in 1851, 
 in the Neapolitan province of Basilicata, a hen was found caught 
 by both feet in the street-pavement of Barile, near Melfi. 
 
 Mr. Hopkins has very correctly shown theoretically that 
 the fissures produced by earthquakes are very instructive as 
 regards the formation of veins and the phenomenon of disloca- 
 tion, the more recent vein displacing the older formation. 
 
 RUMBLINGS OF EARTHQUAKES. 
 
 When the great earthquake of Coseguina, in Nicaragua, 
 took place, January 23, 1835, the subterranean noise the 
 sonorous waves in the earth was heard at the same time on 
 the island of Jamaica and on the plateau of Bogota, 8740 feet 
 above the sea, at a greater distance than from Algiers to Lon- 
 don. In the eruptions of the volcano on the island of St. 
 Vincent, April 30, 1812, at 2 A.M., a noise like the report of 
 cannons was heard, without any sensible concussion of the earth, 
 over a space of 160,000 geographical square miles. There have 
 also been heard subterranean thunderiugs for two years without 
 earthquakes. 
 
 HOW TO MEASURE AN EARTHQUAKE-SHOCK. 
 
 A new instrument (the Seismometer) invented for this pur- 
 pose by M. Kreil, of Vienna, consists of a pendulum oscillating 
 in every direction, but unable to turn round on its point of 
 suspension ; and bearing at its extremity a cylinder, which, by 
 means of mechanism within it, turns on its vertical axis once 
 in twenty-four hours. Next to the pendulum stands a rod bear- 
 ing a narrow elastic arm, which slightly presses the extremity 
 of a lead-pencil against the surface of the cylinder. As long as 
 the pendulum is quiet, the pencil traces an uninterrupted line 
 
Curiosities of Science. 
 
 on the surface of the cylinder ; but as soon as it oscillates, this 
 line becomes interrupted and irregular, and these irregularities 
 indicate the time of the commencement of an earthquake, to- 
 gether with its duration and intensity.* 
 
 Elastic fluids are doubtless the cause of the slight and per- 
 fectly harmless trembling of the earth's surface, which has often 
 continued for several days. The focus of this destructive agent, 
 the seat of the moving force, lies far below the earth's surface ; 
 but we know as little of the extent of this depth as we know of 
 the chemical nature of these vapours that are so highly com- 
 pressed. At the edges of two craters, Vesuvius and the tower- 
 ing rock which projects beyond the great abyss of Pichincha, 
 near Quito, Humboldt has felt periodic and very regular shocks 
 of earthquakes, on each occasion from twenty to thirty seconds 
 before the burning scoriae or gases were erupted. The intensity 
 of the shocks was increased in proportion to the time interven- 
 ing between them, and consequently to the length of time in 
 which the vapours were accumulating. This simple fact, which 
 has been attested by the evidence of so many travellers, furnishes 
 us with a general solution of the phenomenon, in showing that 
 active volcanoes are to be considered as safety-valves for the 
 immediate neighbourhood. There are instances in which the 
 earth has been shaken for many successive days in the chain of 
 the Andes, in South America. In certain districts, the inha- 
 bitants take no more notice of the number of earthquakes than 
 we in Europe take of showers of rain ; yet in such a district 
 Bonpland and Humboldt were compelled to dismount, from the 
 restiveness of their mules, because the earth shook in a forest 
 for fifteen to eighteen minutes without intermission. 
 
 EARTHQUAKES AND THE MOON. 
 
 From a careful discussion of several thousand earthquakes 
 which have been recorded between 1801 and 1850, and a com- 
 parison of the periods at which they occurred with the position 
 of the moon in relation to the earth, M. Perry, of Dijon, infers 
 that earthquakes may possibly be the result of attraction ex- 
 erted by that body on the supposed fluid centre of our globe, 
 somewhat similar to that which she exercises on the waters of 
 the ocean ; and the Committee of the Institute of France have 
 reported favourably upon this theory. 
 
 THE GREAT EARTHQUAKE OF LISBON. 
 
 The eloquent Humboldt remarks, that the activity of an ig- 
 
 * Mr. R. Mallet, F.R.S., and his son Dr. Mallet, have constructed a seismo- 
 graphic map of the world, with seismic bands in their position and relative 
 intensity; and small black discs to denote volcanoes, femaroles, and soltataras, 
 and shades indicating the areas of subsidence. 
 
Things not generally Known. 
 
 neous mountain, however terrific and picturesque the spectacle 
 may be which it presents to our contemplation, is always limited 
 to a very small space. It is far otherwise with earthquakes, 
 which, although scarcely perceptible to the eye, nevertheless 
 simultaneously propagate their waves to a distance of many 
 thousand miles. The great earthquake which destroyed the 
 city of Lisbon, November 1st, 1755, was felt in the Alps, on 
 the coast of Sweden, into the Antilles, Antigua, Barbadoes, 
 and Martinique ; in the great Canadian lakes, in Thuringia, in 
 the flat country of northern Germany, and in the small inland 
 lakes on the shores of the Baltic. Remote springs were inter- 
 rupted in their flow, a phenomenon attending earthquakes 
 which had been noticed among the ancients by Demetrius the 
 Callatian. The hot springs of Toplitz dried up and returned, 
 inundating every thing around, and having their waters co- 
 loured with iron ochre. At Cadiz, the sea rose to an elevation 
 of sixty-four feet ; while in the Antilles, where the tide usually 
 rises only from twenty-six to twenty-eight inches, it suddenly 
 rose about twenty feet, the water being of an inky blackness. 
 It has been computed that, on November 1st, 1755, a portion 
 of the earth's surface four times greater than that of Europe 
 was simultaneously shaken.* As yet there is no manifestation 
 of force known to us (says the vivid denunciation of the phi- 
 losopher), including even the murderous invention of our own 
 race, by which a greater number of people have been killed in 
 the short space of a few minutes : 60,000 were destroyed in 
 Sicily in 1693, from 30,000 to 40,000 in the earthquake of Rio- 
 bamba in 1797, and probably five times as many in Asia Minor 
 and Syria under Tiberius and Justinian the elder, about the 
 years 19 and 526. 
 
 GEOLOGICAL AGE OF THE DIAMOND. 
 
 The discovery of Diamonds in Russia, far from the tropical 
 zone, has excited much interest among geologists. In the de- 
 tritus on the banks of the Adolfskoi, no fewer than forty dia- 
 monds have been found in the gold alluvium, only twenty feet 
 above the stratum in which the remains of mammoths and rhi- 
 noceroses are found. Hence Humboldt has concluded that the 
 formation of gold-veins, and consequently of diamonds, is com- 
 paratively of recent date, and scarcely anterior to the destruc- 
 tion of the mammoths. Sir Roderick Murchison and M. Ver- 
 
 * It has been computed that the shock of this earthquake pervaded an area 
 of 700,000 miles, or the twelfth part of the circumference of the globe. This 
 dreadful shock lasted only five minutes; and nearly the whole of the population 
 being within the churches Con the feast of All Saints), no less than 30,COO per- 
 sons perished by the fall of these edifices. See Daubeny on Volcanoes; Translator's 
 note, Humboldfs Cosmos. 
 
Curiosities of Science. 123 
 
 neuil have been led to the same result by different argu- 
 ments.* 
 
 WHAT WAS ADAMANT ? 
 
 Professor Tennant replies, that the Adamant described by 
 Pliny was a sapphire, as proved by its form, and by the fact 
 that when struck on an anvil by a hammer it would make an 
 indentation in the metal. A true diamond, under such circum- 
 stances, would fly into a thousand pieces. 
 
 WHAT IS COAL ? 
 
 The whole evidence we possess as to the nature of Coal 
 proves it to have been originally a mass of vegetable matter. Its 
 microscopical characters point to its having been formed on the 
 spot in which we find it, to its being composed of vegetable 
 tissues of various kinds, separated and changed by maceration, 
 pressure, and chemical action, and to the introduction of its 
 earthy matter, in a large number of instances, in a state of so- 
 lution or fine molecular subdivision. Dr. Redfern, from whose 
 communication to the British Association we quote, knows 
 nothing to countenance the supposition that our coal-beds are 
 mainly formed of coniferous wood, because the structures found 
 in mother-coal, or the charcoal layer, have not the character of 
 the glandular tissue of such wood, as has been asserted. 
 
 Geological research has shown that the immense forests 
 from which our coal is formed teemed with life. A frog as 
 large as an ox existed in the swamps, and the existence of in- 
 sects proves that the higher order of organic creation flourished 
 at this epoch. 
 
 It has been calculated that the available coal-beds in Lanca- 
 shire amount in weight to the enormous sum of 8,400,000,000 
 tons. The total annual consumption of this coal, it has been 
 estimated, amounts to 3,400,120 tons; hence it is inferred that 
 the coal-beds of Lancashire, at the present rate of consumption, 
 will last 2470 years. Making similar calculations for the coal- 
 fields of South Wales, the north of England, and Scotland, it 
 will readily be perceived how ridiculous were the forebodings 
 which lecturing geologists delighted to indulge in a few years 
 ago. 
 
 TOKBANE-HILL COAL. 
 
 The coal of Torbane Hill, Scotland, is so highly inflammable, 
 that it has been disputed at law whether it be true coal, or 
 only asphaltum, or bitumen. Dr. Redfern describes it as laini- 
 
 * Mr. Murray mentions, on the authority of the Rev. Dr. Robinson, of the 
 Observatory at Armagh, that a rough diamond with a red tint, and valued by 
 Mr. Rundell at twenty guineas, was found in Ireland, many years since, in the 
 bed of a brook flowing through the county of Fermanagh. 
 
Things not generally Known. 
 
 nated, splitting with great ease horizontally, like many cannel 
 coals, and like them it may be lighted at a candle. In all parts 
 of the bed stigmaria and other fossil plants occur in greater 
 numbers than in most other coals ; their distinct vascular tissue 
 may be easily recognised by a common pocket lens, and 65 of 
 the mass consists of carbon. 
 
 Dr. Redfern considers that all our coals may be arranged in 
 a scale having the Torbane-Hill coal at the top and anthracite 
 at the bottom. Anthracite is almost pure carbon ; Torbane Hill 
 contains less fixed carbon than most other cannels : anthracite 
 is very difficult to ignite, and gives out scarcely any gas ; Tor- 
 bane-Hill burns like a candle, and yields 3000 cubic feet of gas 
 per ton, more than any other known coal, its gas being also of 
 greatly superior illuminating power to any other. The only 
 differences which the Torbane-Hill coal presents from others 
 are differences of degree, not of kind. It differs from other 
 coals in being the best gas-coal, and from other cannels in being 
 the best cannel. 
 
 HOW MALACHITE IS FORMED. 
 
 The rich copper-ore of the Ural, which occurs in veins or 
 masses, amid metamorphic strata associated with igneous rocks, 
 and even in the hollows between the eruptive rocks, is worked 
 in shafts. At the bottom of one of these, 280 feet deep, has 
 been found an enormous irregularly-shaped botryoidal mass of 
 Malachite (Greek malache, mountain-green), sending off strings 
 of green copper-ore. The upper surface of it is about 18 feet 
 long and 9 wide ; and it was estimated to contain 15,000 poods, 
 or half a million pounds, of pure and compact malachite. Sir 
 Roderick Murchison is of opinion that this wonderful subter- 
 raneous incrustation has been produced in the stalagmitic 
 form, during a series of ages, by copper solutions emanating 
 from the surrounding loose and sporous mass, and trickling 
 through it to the lowest cavity upon the subjacent solid rock. 
 Malachite is brought chiefly from one mine in Siberia ; its value 
 as raw material is nearly one-fourth that of the same weight of 
 pure silver, or in a manufactured state three guineas per pound 
 avoirdupois. * 
 
 LUMPS OF GOLD IN SIBERIA. 
 
 The gold mines south of Miask are chiefly remarkable for the 
 large lumps or pepites of gold which are found around the Za- 
 vod of Zarevo-Alexandroisk. Previous to 1841 were discovered 
 
 * The use of malachite in ornamental work is very extensive in Russia. 
 Thus, to the Great Exhibition of 1851 were sent a pair of folding-doors veneered 
 with malachite, 13 feet high, valued at 6000J.; malachite cases and pedestals from 
 1500/. to3000/. a-piece, malachite tables 400/., aud chairs 150/. each. 
 
Curiosities of Science. 125 
 
 here lumps of native gold ; in that year a lump of twenty-four 
 pounds was met with ; and in 1843 a lump weighing about 
 seventy-eight pounds English was found, and is now deposited 
 with others in the Museum of the Imperial School of Mines at 
 St. Petersburg. 
 
 SIR ISAAC NEWTON UPON SUBNET'S THEOEY OF THE EARTH. 
 
 In 1668, Dr. Thomas Burnet printed his Theoria Telluris 
 Sacra, "an eloquent physico-theological romance," says Sir 
 David Brewster, " which was to a certain extent adopted even 
 by Newton, Burnet's friend. Abandoning, as some of the 
 fathers had done, the hexaemeron, or six days of Moses, as a 
 physical reality, and having no knowledge of geological pheno- 
 mena, he gives loose reins to his imagination, combining pass- 
 ages of Scripture with those of ancient authors, and presump- 
 tuously describing the future catastrophes to which the earth 
 is to be exposed." Previous to its publication, Burnet pre- 
 sented a copy of his book to Newton, and requested his opinion 
 of the theory which it propounded. Newton took "exceptions 
 to particular passages," and a correspondence ensued. In one 
 of Newton's letters he treats of the formation of the earth, and 
 the other planets, out of a general chaos of the figure assumed 
 by the earth, of the length of the primitive days, of the for- 
 mation of hills and seas, and of the creation of the two ruling 
 lights as the result of the clearing up of the atmosphere. He 
 considers the account of the creation in Genesis as adapted 
 to the judgment of the vulgar. " Had Moses," he says, " de- 
 scribed the processes of creation as distinctly as they were in 
 themselves, he would have made the narrative tedious and con- 
 fused amongst the vulgar, and become a philosopher more than 
 a prophet." After referring to several u causes of meteors, such 
 as the breaking out of vapours from below, before the earth 
 was well hardened, the settling and shrinking of the whole 
 globe after the upper regions or surface began to be hard," 
 Newton closes his letter with an apology for being tedious, 
 which, he says, "he has the more reason to do, as he has not 
 set down any thing he has well considered, or will undertake to 
 defend." See the Letter in the Appendix to Sir D. Brewster's 
 Life of Newton, vol. ii. 
 
 The primitive condition of the earth, and its preparation for man, 
 was a subject of general speculation at the close of the seventeenth cen- 
 tury. Leibnitz, like his great rival (Newton), attempted to explain the 
 formation of the earth, and of the different substances which composed 
 jt ; and he had the advantage of possessing some knowledge of geolo- 
 gical phenomena : the earth he regarded as having been originally a 
 burning mass, whose temperature gradually diminished till the vapours 
 were condensed into a universal ocean, which covered the highest moun- 
 
126 Things not generally Known. 
 
 tains, and gradually flowed into vacuities and subterranean cavities pro- 
 duced by the consolidation of the earth's crust. He regarded fossils as 
 the real remains of plants and animals which had been buried in the 
 strata ; and, in speculating on the formation of mineral substances, he 
 speaks of crystals as the geometry of inanimate nature. Breioste^s Life 
 of Newton, vol. ii. p. 100, note. (See also "The Age of the Globe," in 
 Things not generally Known, p. 13.) 
 
 " THE FATHER OF ENGLISH GEOLOGY." 
 
 In 1769 was born, the son of a yeoman of Oxfordshire, Wil- 
 liam Smith. When a boy he delighted to wander in the fields, 
 collecting "pound-stones" (Eckinites), " pundibs" (TerebratulcR), 
 and other stony curiosities; and receiving little education be- 
 yond what he taught himself, he learned nothing of classics but 
 the name. Grown to be a man, he became a land-surveyor and 
 civil engineer, and was much engaged in constructing canals. 
 While thus occupied, he observed that all the rocky masses 
 forming the substrata of the country were gently inclined to 
 the east and south-east, that the red sandstones and marls 
 above the coal-measures passed below the beds provincially 
 termed lias-clay and limestone that these again passed un- 
 derneath the sands, yellow limestone, and clays that form the 
 table-land of the Coteswold Hills ; while they in turn plunged 
 beneath the great escarpment of chalk that runs from the coast 
 of Dorsetshire northward to the Yorkshire shores of the German 
 Ocean. He further observed that each formation of clay, sand, 
 or limestone, held to a very great extent its own peculiar suite 
 of fossils. The "snake-stones" (Ammonites) of the lias were 
 different in form and ornament from those of the inferior oolite ; 
 and the shells of the latter, again, differed from those of the 
 Oxford clay, Cornbrash, and Kimmeridge clay. Pondering 
 much on these things, he came to the then unheard-of con- 
 clusion that each formation had been in its turn a sea-bottom, 
 in the sediments of which lived and died marine animals now 
 extinct, many specially distinctive of their own epochs in time. 
 
 Here indeed was a discovery, made, too, by a man utterly 
 unknown to the scientific world, and having no pretension to 
 scientific lore. " Strata Smith's" find was unheeded for many 
 a long year ; but at length the first geologists of the day 
 learned from the land-surveyor that superposition of strata 
 is inseparably connected with the succession of life in time. 
 Hooke's grand vision was at length realised, and it was indeed 
 possible " to build up a terrestrial chronology from rotten shells" 
 imbedded in the rocks. Meanwhile he had constructed the 
 first geological map of England, which has served as a basis for 
 geological maps of all other parts of the world. William Smith 
 was now presented by the Geological Society with the Wollas- 
 ton Medal, and hailed as "the Father of English Geology." 
 
Curiosities of Science, 127 
 
 He died in 1840. Till the manner as well as the fact of the first 
 appearance of successive forms of life shall be solved, it is not 
 easy to surmise how any discovery can be made in geology 
 equal in value to that which we owe to the genius of William 
 Smith. Saturday Review, No. 140. 
 
 DK. BUCKLAND'S GEOLOGICAL LABOURS. 
 
 Sir Henry De la Beche, in his Anniversary Address to the 
 Geological Society in 1848, on presenting the Wollaston Medal 
 to Dr. Buckland, felicitously observed : 
 
 It may not be generally known that, while yet a child, at your 
 native town, Axminster in Devonshire, ammonites, obtained by your 
 father from the lime quarries in the neighbourhood, were presented to 
 your attention. As a scholar at Winchester, the chalk, with its flints, 
 was brought under your observation, and there it was that your collec- 
 tions in natural history first began. Removed to Oxford, as a scholar 
 of Corpus Christi College, the future teacher of geology in that Univer- 
 sity was fortunate in meeting with congenial tastes in our colleague 
 Mr. W. J. Broderip, then a student at Oriel College. It was during your 
 walks together to Shotover Hill, when his knowledge of conchology was 
 so valuable to you, enabling you to distinguish the shells of the Oxford 
 oolite, that you laid the foundation for those field-lectures, forming part 
 of your course of geology at Oxford, which no one is likely to forget who 
 has been so fortunate at any time as to have attended them. The fruits 
 of your walks with Mr. Broderip formed the nucleus of that great collec- 
 tion, more especially remarkable for the organic remains it contains, 
 which, after the labours of forty years, you have presented to the Geo- 
 logical Museum at Oxford, in grave recollection of the aid which the 
 endowments of that University, and the leisure of its vacations, had 
 afforded you for extensive travelling during a residence at Oxford of 
 nearly forty-five years. 
 
 DISCOVERIES OF M. AGASSIZ.* 
 
 This great paleontologist, in the course of his ichthyological 
 researches, was led to perceive that the arrangement by Cuvier 
 according to organs did not fulfil its purpose with regard to 
 fossil fishes, because in the lapse of ages the characteristics of 
 their structures were destroyed. He therefore adopted the only 
 other remaining plan, and studied the tissues, which, being 
 less complex than the organs, are.oftener found intact. The 
 result was the very remarkable discovery, that the tegumentary 
 membrane of fishes is so intimately connected with their orga- 
 nisation, that if the whole of the fish has perished except this 
 membrane, it is practicable, by noting its characteristics, to re- 
 construct the animal in its most essential parts. Of the value 
 of this principle of harmony, some idea may be formed from 
 the circumstance, that on it Agassiz has based the whole of that 
 
 * Longfellow has written some pleasing lines on " The Fiftieth Birthday of 
 M. Agassiz. May 28, 1857," appended to " The Courtship of Miles Standish," 
 1868. 
 
128 Things not generally Known. 
 
 celebrated classification of which he is the sole author, and by 
 which fossil ichthyology has for the first time assumed a precise 
 and definite shape. How essential its study is to the geologist 
 appears from the remark of Sir Roderick Murchison, that "fos- 
 sil fishes have every where proved the most exact chronometer 
 of the age of rocks." 
 
 SUCCESSION OF LIFE IN TIME. 
 
 In the Museum of Economic Geology, in Jermyn Street, may 
 be seen ores, metals, rocks, and whole suites of fossils strati- 
 graphically arranged in such a manner that, with an observant 
 eye for form, all may easily understand the more obvious scien- 
 tific meanings of the Succession of Life in Time, and its bearing 
 on geological economies. It is perhaps scarcely an exaggeration 
 to say, that the greater number of so-called educated persons 
 are still ignorant of the meaning of this great doctrine. They 
 would be ashamed not to know that there are many suns and 
 material worlds besides our own ; but the science, equally grand 
 and comprehensible, that aims at the discovery of the laws that 
 regulated the creation, extension, decadence, and utter extinc- 
 tion of many successive species, genera, and whole orders of life, 
 is ignored, or, if intruded on the attention, is looked on as an 
 uncertain and dangerous dream, and this in a country which 
 was almost the nursery of geology, and which for half a century 
 has boasted the first Geological Society in the world. Saturday 
 Review, No. 140. 
 
 PRIMITIVE DIVERSITY AND NUMBERS OF ANIMALS IN 
 GEOLOGICAL TIMES. . 
 
 Professor Agassiz considers that the very fact of certain stra- 
 tified rocks, even among the oldest formations, being almost 
 entirely made up of fragments of organised beings, should long 
 ago have satisfied the most sceptical that both animal and 
 vegetable life were as active and profusely scattered upon the whole 
 globe at all times, and during all geological periods, as they are 
 now. No coral reef in the Pacific contains a larger amount 
 of organic debris than some of the limestone deposits of the 
 tertiary, of the cretaceous, or of the oolitic, nay even of the 
 paleozoic period ; and the whole vegetable carpet covering the 
 present surface of the globe, even if we were to consider only 
 the luxuriant vegetation of the tropics, leaving entirely out of 
 consideration the entire expanse of the ocean, as well as those 
 tracts of land where, under less favourable circumstances, the 
 growth of plants is more reduced, would not form one single 
 seam of workable coal to be compared to the many thick beds 
 contained in the rocks of the carboniferous period alone. 
 
Curiosities of Science. 129 
 
 ENGLAND IN THE EOCENE PERIOD. 
 
 Eocene is Sir Charles Lyell's term for the lowest group of 
 the Tertiary system in which the dawn of recent life appears ; 
 and any one who wishes to realise what was the aspect pre- 
 sented by this country during the Eocene period, need only go 
 to Sheerness. If, leaving that place behind him, he walks 
 down the Thames, keeping close to the edge of the water, he 
 will find whole bushels of pyritised pieces of twigs and fruits. 
 These fruits and twigs belong to plants nearly allied to the 
 screw-pine and custard-apple, and to various species of palms 
 and spice-trees which now flourish in the Eastern Archipelago. 
 At the time they were washed down from some neighbouring 
 land, not only crocodilian reptiles, but sharks and innumerable 
 turtles, inhabited a sea or estuary which now forms part of the 
 London district ; and huge boa-constrictors glided amongst the 
 trees which fringed the adjoining shores. 
 
 Countless as are the ages which intervened between the 
 Eocene period and the time when the little jawbones of Stones- 
 field were washed down to the place where they were to await 
 the day when science should bring them again to light, not one 
 mammalian genus which now lives upon our plane has been 
 discovered amongst Eocene strata. We have existing families, 
 but nothing more. Professor Owen. 
 
 FOOD OF THE IGUANODON. 
 
 Dr. Mantell, from the examination of the anterior part of 
 the right side of the lower jaw of an Iguanodon discovered in a 
 quarry in Tilgate Forest, Sussex, has detected an extraordinary 
 deviation from all known types of reptilian organisation, and 
 which could not have been predicated ; namely, that this colos- 
 sal reptile, which equalled in bulk the gigantic Edentata of 
 South America, and like them was destined to obtain support 
 from comminuted vegetable substances, was also furnished with a 
 large prehensile tongue and fleshy lips, to serve as instruments 
 for seizing and cropping the foliage and branches of trees ; 
 while the arrangement of the teeth as in the ruminants, and 
 their internal structure, which resembles that of the molars of 
 the sloth tribe in the vascularity of the dentine, indicate adap- 
 tations for the same purpose. 
 
 Among the physiological phenomena revealed by paleonto- 
 logy, there is not a more remarkable one than this modification 
 of the type of organisation peculiar to the class of reptiles to 
 meet the conditions required by the economy of a lizard placed 
 under similar physical relations; and destined to effect the 
 same general purpose in the scheme of nature as the colossal 
 
130 Things not generally Known. 
 
 Edentata of former ages and the large herbivorous mammalia 
 of our own times. 
 
 THE PTEEODACTYL THE FLYING DEAGON. 
 
 The Tilgate beds of the Wealden series, just mentioned, have 
 yielded numerous fragments of the most remarkable reptilian 
 fossils yet discovered, and whose wonderful forms denote them 
 to have thronged the shallow seas and bays and lagoons of the 
 period. In the grounds of the Crystal Palace at Sydenham 
 the reader will find restorations of these animals sufficiently 
 perfect to illustrate this reptilian epoch. They include the iqua- 
 nodon, an herbivorous lizard exceeding in size the largest ele- 
 phant, and accompanied by the equally gigantic and carni- 
 vorous megalosaurus (great saurian), and by the two yet more 
 curious reptiles, the pylceosaurus (forest, or weald, saurian) and 
 the pterodactyl (from pteron, ( wing,' and dactylus, ' a finger'), 
 an enormous bat-like creature, now running upon the ground 
 like a bird ; its elevated body and long neck not covered with 
 feathers, but with skin, naked, or resplendent with glittering 
 scales ; its head like that of a lizard or crocodile, and of a size 
 almost preposterous compared with that of the body, with its 
 long fore extremities stretched out, and connected by a mem- 
 brane with the body and hind legs. 
 
 Suddenly this mailed creature rose in the air, and realised 
 or even surpassed in strangeness the flying dragon of fable: its 
 fore-arms and its elongated wing-finger furnished with claws ; 
 hand and fingers extended, and the interspace filled up by a 
 tough membrane ; and its head and neck stretched out like 
 that of the heron in its flight. When stationary, its wings 
 were probably folded back like those of a bird; though perhaps, 
 by the claws attached to its fingers, it might suspend itself from 
 the branches of trees. 
 
 MAMMALIA IN SECONDAEY EOCKS. 
 
 It was supposed till very lately that few if any Mammalia 
 were to be found below the Tertiary rocks, i. e. those above the 
 chalk ; and this supposed fact was very comfortable to those 
 who support the doctrine of " progressive development," and 
 hold, with the notorious Vestiges of Creation, that a fish by 
 mere length of time became a reptile, a lemur an ape, and 
 finally an ape a man. But here, as in a hundred other cases, 
 facts, when duly investigated, are against their theory. A 
 mammal jaw had been already discovered by Mr. Brodie on 
 the shore at the back of Swanage Point, in Dorsetshire, when 
 Mr. Beckles, F.G.S., traced the vein from which this jaw had 
 been procured, and found it to be a stratum about five in-.-iies 
 
Curiosities of Science. 131 
 
 thick, at the base of the Middle Purbeck beds ; and after remov- 
 ing many thousand tons of rock, and laying bare an area of 
 nearly 7000 square feet (the largest cutting ever made for purely 
 scientific purposes), he found reptiles (tortoises arid lizards) in 
 hundreds ; but the most important discovery was that of the 
 jaws of at least fourteen different species of mammalia. Some 
 of these were herbivorous, some carnivorous, connected with 
 our modern shrews, moles, hedgehogs, &c. ; but all of them per- 
 fectly developed and highly-organised quadrupeds. Ten years 
 ago, no remains of quadrupeds were believed to exist in the 
 Secondary strata. " Even in 1854," says Sir Charles Lyell (in 
 a supplement to the fifth edition of his Manual of Elementary 
 Geology}, " only six species of mammals from rocks older than 
 the Tertiary were known in the whole world." We now possess 
 evidence of the existence of fourteen species, belonging to eight 
 or nine genera, from the fresh-water strata of the Middle Pur- 
 beck Oolite. It would be rash now to fix a limit in past time 
 to the existence of quadrupeds. The Rev. C. Kingsley. 
 
 FOSSIL HUMAN BONES. 
 
 In the paleontological collection in the British Museum is 
 preserved a considerable portion of a human skeleton imbedded 
 in a slab of rock, brought from Guadaloupe, and often referred 
 to in opposition to the statement that hitherto no fossil human 
 bones have been found. The presence of these bones, however, 
 has been explained by the circumstance of a battle and the 
 massacre of a tribe of Galtibis by the Caribs, which took place 
 near the spot in which the bones were found about 130 years 
 ago ; for as the bodies of the slain were interred on the sea- 
 shore, their skeletons may have been subsequently covered by 
 sand-drift, which has since consolidated into limestone. 
 
 It will be seen by reference to the Philosophical Transac- 
 tions, that on the reading of the paper upon this discovery to 
 the Royal Society, in 1814, Sir Joseph Banks, the president, 
 considered the "fossil" to be of very modern formation, and 
 that probably, from the contiguity of a volcano, the tempera- 
 ture of the water may have been raised at some time, and dis- 
 solving carbonate of lime readily, may have deposited about 
 the skeleton in a comparatively short period hard and 'solid 
 stone. Every person may be convinced of the rapidity of the 
 formation and of the hardness of such stone by inspecting the 
 inside of tea-kettles in which hard water is boiled. 
 
 Descriptions of petrifactions of human bodies appear to refer to the 
 conversion of bodies into adipocere, and not into stone. All the sup- 
 posed cases of petrifaction are probably of this nature. The change 
 occurs only when the coffin becomes filled with water. The body, con- 
 verted into adipocere, floats on the water. The supposed cases of 
 
132 Things not generally Known. 
 
 changes of position in the grave, bursting open the coffin-lids, turning 
 over, crossing of limbs, &c., formerly attributed to the coming to life of 
 persons buried who were not dead, is now ascertained to be due to the 
 same cause. The chemical change into adipocere, and the evolution of 
 gases, produce these movements of dead bodies. Mr. Trail Green. 
 
 THE MOST ANCIENT FISHES. 
 
 Among the important results of Sir Roderick Murchison's 
 establishment of the Silurian system is the following : 
 
 That as the Lower Silurian group, often of vast dimensions, has 
 never afforded the smallest vestige of a Fish, though it abounds in nu- 
 merous species of the marine classes, corals, cnnoidea, mollusca, and 
 Crustacea ; and as in Scandinavia and Russia, where it is based on rocks 
 void of fossils, its lowest stratum contains facoids only, Sir R. Mur- 
 chison has, after fifteen years of laborious research stea iily directed to 
 this point, arrived at the conclusion, that a very long period elapsed 
 after life was breathed into the waters before the lowest order of verte- 
 brata was created ; the earliest fishes being those of the Upper Silurian 
 rocks, winch he was the first to discover, and which he described " as 
 the most ancient beings of their class which have yet been brought to 
 light." Though the Lower Silurian rocks of various parts of the world 
 have since been ransacked by multitudes of prying geologists, who have 
 exhumed from them myriads of marine fossils, not a single ichthyolite 
 has been found in any stratum of higher antiquity than the Upper 
 Silurian group of Murchison. 
 
 The most remarkable of all fossil fishes yet discovered have 
 been found in the Old Red Sandstone cliffs at Dorpat, where 
 the remains are so gigantic (one bone measuring two feet nine 
 inches in length) that they were at first supposed to belong to 
 saurians. 
 
 Sir Roderick's examination of Russia has, in short, proved 
 that the ichthyolites and mollusks which, in Western Europe, are 
 separately peculiar to smaller detached basins, were here (in the 
 British Isles} cohabitants of many parts of the same great sea. 
 
 EXTINCT CARNIVOROUS ANIMALS OF BRITAIN. 
 
 Professor Owen has thus forcibly illustrated the Carnivorous 
 Anim ils which preyed upon and restrained the undue multi- 
 plica ion of the vegetable feeders. First we have the bear 
 family, which is now represented in this country only by the 
 badger. We were once blest, however, with many bears. One 
 species seems to have been identical with the existing brown 
 bear of the European continent. Far larger and more formidable 
 was the gigantic cave-bear ((Jrsus spelceus), which surpassed in 
 size his grisly brother of North America. The skull of the cave- 
 bear differs very much in shape from that of its small brown 
 relative just alluded to ; the forehead, in particular, is much 
 higher, to be accounted for by an arrangement of air-cells simi- 
 lar to those which we have already remarked in the elephant. 
 
Curiosities of Science. Io3 
 
 The cave-bear has left its remains in vast abundance in Ger- 
 many. In our own caves, the bones of hysenas are found in 
 greater quantities. The marks which the teeth of the hyaena 
 make upon the bones which it gnaws are quite unmistakable. 
 Our English hyaenas had the most undiscriminating appetite, 
 preying upon every creature, their own species amongst others. 
 Wolves, not distinguishable from those which now exist in 
 France and Germany, seem to have kept company with the 
 hyaenas ; and the Felis spelcea, a sort of lion, but larger than 
 any which now exists, ruled over all weaker brutes. Here, 
 says Professor Owen, we have the original British Lion. A 
 species of Machairodus has left its remains at Kent's Hole, near 
 Torquay. In England we had also the beaver, which still 
 lingers on the Danube and the Rhone, and a larger species, 
 which has been called Trogontherium (gnawing beast), and a 
 gigantic mole. 
 
 THE GREAT CAVE TIGER OR LION OF BRITAIN. 
 
 Remains of this remarkable animal of the drift or gravel 
 period of this country have been found at Brentford and else- 
 where near London. Speaking of this animal, Professor Owen 
 observes, that "it is commonly supposed that the Lion, the 
 Tiger, and the Jaguar are animals peculiarly adapted to a 
 tropical climate. The genus Felis (to which these animals 
 belong) is, however, represented by specimens in high northern 
 latitudes, and in all the intermediate countries to the equator." 
 The chief condition necessary for the presence of such animals 
 is an abundance of the vegetable-feeding animals. It is thus 
 that the Indian tiger has been known to follow the herds of 
 antelope and deer in the lofty mountains of the Himalaya to the 
 verge of perpetual snow, and far into Siberia. " It need not, 
 therefore," continues Professor Owen, "excite surprise that 
 indications should have been discovered in the fossil relics of 
 the ancient mammalian population of Europe of a large feline 
 animal, the contemporary of the mammoth, of the tichorrhine 
 rhinoceros, of the great gigantic cave-bear and hyaena, and the 
 slayer of the oxen, deer, and equine quadrupeds that so 
 abounded during the same epoch." The dimensions of this 
 extinct animal equal those of the largest African lion or Bengal 
 tiger ; and some bones have been found which seem to imply 
 that it had even more powerful limbs and larger paws. 
 
 THE MAMMOTHS OF THE BRITISH ISLES. 
 
 Dr. Buckland has shown that for long ages many species 
 of carnivorous animals now extinct inhabited the caves of the 
 British islands. In low tracts of Yorkshire, where tranquil 
 lacustrine (lake-like) deposits have occurred, bones (even thoso 
 
134 Things not generally Known. 
 
 of the lion) have been found so perfectly unbroken and un- 
 worn, in fine gravel (as at Market Weigh ton), that few persons 
 would be disposed to deny that such feline and other animals 
 once roamed over the British isles, as well as other European 
 countries. Why, then, is it improbable that large elephants, 
 with a peculiarly thick integument, a close coating of wool, 
 and much long shaggy hair, should have been the occupants 
 of wide tracts of Northern Europe and Asia? This coating, 
 Dr. Fleming has well remarked, was probably as impenetrable 
 to rain and cold as that of the monster ox of the polar circle. 
 Such is the opinion of Sir Roderick Murchison, who thus ac- 
 counts for the disappearance of the mammoths from Britain : 
 
 When we turn from the great Siberian continent, which, anterior to 
 its elevation, was the chief abode of the mammoths, and look to the 
 other parts of Europe, where their remains also occur, how remarkable 
 is it that we find the number of these creatures to be justly proportion- 
 ate to the magnitude of the ancient masses of land which the labours 
 of geologists have denned ! Take the British isles, for example, and let 
 all their low, recently elevated districts be submerged ; let, in short, 
 England be viewed as the comparatively small island she was when the 
 ancient estuary of the Thames, including the plains of Hyde Park, 
 Chelsea, Hounslow, and Uxbridge, were under the water ; when the 
 Severn extended far into the heart of the kingdom, and large eastern 
 tracts of the island were submerged, and there will then remain but 
 moderately-sized feeding-grounds for the great quadrupeds whose bones 
 are found in the gravel of the adjacent rivers and estuaries. 
 
 This limited area of subsistence could necessarily only keep 
 Tip a small stock of such animals ; and, just as we might ex- 
 pect, the remains of British mammoths occur in very small 
 numbers indeed, when compared with those of the great char- 
 nel-houses of Siberia, into which their bones had been carried 
 down through countless ages from the largest mass of surface 
 which geological inquiries have yet shown to have been dry 
 land during that epoch. 
 
 The remains of the mammoth, says Professor Owen, have 
 been found in all, or almost all, the counties of England. Off 
 the coast of Norfolk they are met with in vast abundance. 
 The fishermen who go to catch turbot between the mouth of 
 the Thames and the Dutch coast constantly get their nets en- 
 tangled in the tusks of the mammoth. A collection of tusks 
 and other remains, obtained in this way, is to be seen at Rams- 
 gate. In North America, this gigantic extinct elephant must 
 have been very common ; and a large portion of the ivory 
 which supplies the markets of Europe is derived from the vast 
 mammoth graveyards of Siberia. 
 
 The mammoth ranged at least as far north as 60. There 
 is no doubt that, at the present day, many specimens of the 
 musk-ox are annually becoming imbedded in the mud and ice 
 of the North- American rivers. 
 
Curiosities of Science. 135 
 
 It is curious to observe, that the mammoth teeth which are 
 met with in caves generally belonged to young mammoths, who 
 probably resorted thither for shelter before increasing age and 
 strength emboldened them to wander far afield. 
 
 THE RHINOCEROS AND HIPPOPOTAMUS OF ENGLAND. 
 
 The mammoth was not the only giant that inhabited Eng- 
 land in the Pliocene or Upper Tertiary period. We had also 
 here the Rhinoceros tichorrhinus, or "strongly walled about the 
 nose," remains of which have been discovered in enormous 
 quantities in the brickfields about London. Pallas describes 
 an entire specimen of this creature, which was found near 
 Yakutsk, the coldest town on the globe. Another rhinoceros, 
 leptorrhinus (fine nose), dwelt with the elephant of Southern 
 Europe. In Siberia has been discovered the Elaimotherium, 
 forming a link between the rhinoceros and the horse. 
 
 In the days of the mammoth, we had also in England a 
 Hippopotamus, rather larger than the species which now in- 
 habits the Nile. Of our British hippopotamus some remains 
 were dug up by the workmen in preparing the foundations of 
 the New Junior United Service Club-house, in Regent-street. 
 
 THE ELEPHANT AND TORTOISE. 
 
 The idea of an Elephant standing on the back of a Tortoise 
 was often laughed at as an absurdity, until Captain Cautley 
 and Dr. Falconer at length discovered in the hills of Asia the 
 remains of a tortoise in a fossil state of such a size that an 
 elephant could easily have performed the above feat. 
 
 COEXISTENCE OF MAN AND THE MASTODON. 
 
 Dr. C. F. Winslow has communicated to the Boston Society 
 of Natural History the discovery of the fragment of a human 
 cranium 180 feet below the surface of the Table Mountain, 
 California. Now the mastodon's bones being found in the 
 same deposits, points very clearly to the probability of the ap- 
 peaiance of the human race on the western portions of North 
 America at least before the extinction of those huge creatures. 
 Fragments of mastodon and Elephas primigenius have been 
 taken ten and twenty feet below the surface in the above lo- 
 cality ; where this discovery of human and mastodon remains 
 gives strength to the possible truth of an old Indian tradition, 
 the contemporary existence of the mammoth and aboriginals 
 in this region of the globe. 
 
 HABITS OF THE MEGATHERIUM. 
 
 Much uncertainty has been felt about the habits of the Me- 
 gatherium, or Great Beast. It has been asked whether it bur- 
 
136 Things not generally Known. 
 
 rowed or climbed, or what it did ; and difficulties have pre- 
 sented themselves on all sides of the question. Some have 
 thought that it lived in trees as much larger than those which 
 now exist as the Megatherium itself is larger than the common 
 sloth. * This, however, is now known to be a mistake. It did 
 not climb trees it pulled them down ; and in order to do this 
 the hinder parts of its skeleton were made enormously strong, 
 and its prehensile fore-legs formed so as to give it a tremendous 
 power over any thing which it grasped. Dr. Buckland sug- 
 gested that animals which got their living in this way had 
 a very fair chance of having their heads broken. While Pro- 
 fessor Owen was still pondering over this difficulty, the skull 
 of a cognate animal, the Mylodon, came into his hands. Great 
 was his delight when he found that the mylodon not only had 
 his head broken, but broken in two different places, at two 
 different times ; and moreover so broken that the injury could 
 only have been inflicted by some such agent as a fallen tree. 
 The creature had recovered from the first blow, but had evi- 
 dently died of the second. This tribe had, as it turns out, 
 two skulls, an outer and an inner one given them, as it 
 would appear, expressly with a view to the very dangerous 
 method in which they were intended to obtain their necessary- 
 food. 
 
 The dentition of the megatherium is curious. The ele- 
 phant gets teeth as he wants them. Nature provided for the 
 comfort of the megatherium in another way. It did not get 
 new teeth, but the old ones went on for ever growing as long 
 as the animal lived ; so that as fast as one grinding surface be- 
 came useless, another supplied its place. 
 
 THE DINOTHEE1UM, OE TEEEIBLE BEAST. 
 
 The family of herbivorous Cetaceans are connected with the 
 Pachydermata of the land by one of the most wonderful of all 
 the extinct creatures with which geologists have made us ac- 
 quainted. This is the Dinotherium, or Terrible Beast. The re- 
 mains of this animal were found in Miocene sands at Eppels- 
 heim, about forty miles from Darmstadt. It must have been 
 larger than the largest extinct or living elephant. The most 
 remarkable peculiarity of its structure is the enormous tusks, 
 curving downwards and terminating its lower jaw. It appears 
 to have lived in the water, where the immense weight of these 
 formidable appendages would not be so inconvenient as on 
 land. What these tusks were used for is a mystery ; but perhaps 
 they acted as pickaxes in digging up trees and shrubs, or as 
 
 * The sloth only deserves its name when it is obliged to attempt to pioceed 
 along the ground ; when it has any thing which it can lay hold of it is agile 
 enough. 
 
Curiosities of Science. 137 
 
 harrows in raking the bottom of the water. Dr. Buckland used 
 to suggest that they were perhaps employed as anchors, by 
 means of which the monster might fasten itself to the bank of 
 a stream and enjoy a comfortable nap. The extreme length of 
 the Dinotherium was about eighteen feet. Professor Kemp, in 
 his restoration of the animal, has given it a trunk like that of 
 the elephant, but not so long, and the general form of the tapir. 
 Professor Owen. 
 
 THE GLYPTODON. 
 
 There are few creatures which we should less have expected 
 to find represented in fossil history by a race of gigantic brethren 
 than the armadillo. The creature is so small, not only in size 
 but in all its works and ways, that we with difficulty associate 
 it with the idea of magnitude. Yet Sir Woodbine Parish has 
 discovered evidences of enormous animals of this family having 
 once dwelt in South America. The huge loricated (plated over) 
 creature whose relics were first sent has received the name of 
 Glyptodon, from its sculptured teeth. Unlike the small arma- 
 dillos, it was unable to roll itself up into a ball ; though an 
 enormous carnivore which lived in those days must have made 
 it sometimes wish it had the power to do so. When attacked, 
 it must have crouched down, and endeavoured to make its huge 
 shell as good a defence as possible. Professor Owen. 
 
 INMATES OF AN AUSTRALIAN CAVERN. 
 
 From the fossil-bone caverns in Wellington Valley, in 1830, 
 were sent to Professor Owen several bones which belonged, as 
 it turned out, to gigantic kangaroos, immensely larger than 
 any existing species ; to a kind of wombat, to formidable das- 
 yures, and several other genera. It also appeared that the 
 bones, which were those of herbivores, had evidently belonged 
 to young animals, while those of the carnivores were full-sized ; 
 a fact which points to the relations between the two families 
 having been any thing but agreeable to the herbivores. 
 
 THE POUCH-LION OF AUSTRALIA. 
 
 The Thylacoleo (Pouch-Lion) was a gigantic marsupial car- 
 nivore, whose character and affinities Professor Owen has, with 
 exquisite scientific tact, made out from very small indications. 
 This monster, which had kangaroos with heads three feet long 
 to feed on, must have been one of the most extraordinary ani- 
 mals of the antique world. 
 
 THE CONEY OF SCRIPTURE. 
 
 Paleontologists have pointed out the curious fact that the 
 
138 Things not generally Known. 
 
 Hyrax, called ' coney' in our authorised version of the Bible, is 
 really only a diminutive and hornless rhinoceros. Remains have 
 been found at Eppelsheim which indicate an animal more like a 
 gigantic Hyrax than any of the existing rhinoceroses. To this 
 the name of Acerotherium (Hornless Beast) has been given. 
 
 A THREE-HOOFED HORSE. 
 
 Professor Owen describes the Hipparion, or Three-hoofed 
 Horse, as the first representative of a family so useful to man- 
 kind. This animal, in addition to its true hoof, appears to 
 have had two additional elementary hoofs, analogous to those 
 which we see in the ox. The object of these no doubt was to 
 enable the Hipparion to extricate his foot with greater ease 
 than he otherwise could when it sank through the swampy 
 ground on which he lived. 
 
 TWO MONSTER CARNIVORES OF FRANCE. 
 
 A huge carnivorous creature has been found in Miocene 
 strata in France, in which country it preyed upon the gazelle 
 and antelope. It must have been as large as a grisly bear, but 
 in general appearance and teeth more like a gigantic dog. 
 Hence the name of Amphicyon (Doubtful Dog) has been as- 
 signed to it. This animal must have derived part of its support 
 from vegetables. Not so the coeval monster which has been 
 called Machairodus (Sabre-tooth). It must have been some- 
 what akin to the tiger, and is by far the most formidable ani- 
 mal which we have met with in our ascending progress through 
 the extinct mammalia. Professor Owen. 
 
 GEOLOGY OF THE SHEEP. 
 
 No unequivocal fossil remains of the sheep have yet been 
 found in the bone-caves, the drift, or the more tranquil strati- 
 fied newer Pliocene deposits, so associated with the fossil bones 
 of oxen, wild-boars, wolves, foxes, otters, <fec., as to indicate 
 the coevality of the sheep with those species, or in such an 
 altered state as to indicate them to have been of equal anti- 
 quity. Professor Owen had his attention particularly directed 
 to this point in collecting evidence for a history of British 
 Fossil Mammalia. No fossil core-horns of the sheep have yet 
 been any where discovered ; and so far as this negative evi- 
 dence goes, we may infer that the sheep is not geologically 
 more ancient than man ; that it is not a native of Europe, but 
 has been introduced by the tribes who carried hither the germs 
 of civilisation in their migrations westward from Asia. 
 
 THE-TRILOBITE. 
 
 Among the earliest races we have those remarkable forms, 
 
Curiosities of Science. 139 
 
 the Trilobites, inhabiting the ancient ocean. These Crustacea 
 remotely resemble the common wood-louse, and like that ani- 
 mal they had the power of rolling themselves into a ball when 
 attacked by an enemy. The eye of the trilobite is a most re- 
 markable organ ; and in that of one species, Phacops caudatus, 
 not less than 250 lenses have been discovered. This remark- 
 able optical instrument indicates that these creatures lived 
 under similar conditions to those which surround the.crustacea 
 of the present day. Hunt's Poetry of Science. 
 
 PEOFITABLE SCIENCE. 
 
 In that strip of reddish colour which runs along the cliffs 
 of Suffolk, and is called the Redcrag, immense quantities of 
 cetacean remains have been found. Four different kinds of 
 whales, little inferior in size to the whalebone whale, have left 
 their bones in this vast charnel-house. In 1840, a singularly 
 perplexing fossil was brought to Professor Owen from this Red- 
 crag. No one could say what it was. He determined it to be 
 the tooth of a ceta'cean, a unique specimen. Now the remains 
 of cetaceans in the Suffolk crag have been discovered in such 
 enormous quantities, that many thousands a-year are made by 
 converting them into manure. 
 
 EXTINCT GIGANTIC BIEDS OF NEW ZEALAND. 
 
 In the islands of New Zealand have been found the bones of 
 large extinct wingless Birds, belonging to the Post Tertiary or 
 Recent system, which have been deposited by the action of rivers. 
 The bird is named Moa by the natives, and Dinornis by natu- 
 ralists : some of the bones have been found in two caves in the 
 North Island, and have been sold by the natives at an extraor- 
 dinary price. The caves occur in limestone rocks, and the bones 
 are found beneath earth and a soft deposit of carbonate of lime. 
 The largest of the birds is stated to have stood thirteen or four- 
 teen feet, or twice the height of the ostrich ; and its egg large 
 enough to fill the hat of a man as a cup. Several statements 
 have appeared of these birds being still in existence, but there 
 is every reason to believe the Moa to be altogether extinct. 
 
 An extensive collection of remains of these great wingless 
 birds has been collected in New Zealand by Mr. Walter Mantel], 
 and deposited in the British Museum. Among these bones 
 Professor Owen has discovered a species which he regards as 
 the most remarkable of the feathered class for its prodigious 
 strength and massive proportions, and which he names Dinor- 
 nis elepkantopus, or elephant-footed, of which the Professor has 
 been able to construct an entire lower limb : the length of the 
 metatarsal bone is 9^ inches, the breadth of the lower eud 
 
140 Things not generally Known. 
 
 being 5 finches. The extraordinary proportions of the meta- 
 tarsus of this wingless bird will, however, be still better under- 
 stood by comparison with the same bone in the ostrich, in 
 which the metatarsus is 19 inches in length, the breadth of its 
 lower end being only 2 inches. From the materials accumu- 
 lated by Mr. Mantell, the entire skeleton of the Dinornis ele- 
 phantopus has been reconstructed ; and now forms a worthy 
 companion of the Megatherium and Mastodon in the gallery of 
 fossil remains in the British Museum. This species of Dinornis 
 appears to have been restricted to the Middle Island of New 
 Zealand.* 
 
 Another specimen of the remains of the Dinornis is pre- 
 served in the Museum of the Royal College of Surgeons, in 
 Lincoln's-Inn Fields; and the means by which the college 
 obtained this valuable acquisition is thus graphically narrated 
 by Mr. Samuel Warren, F. R.S. : 
 
 In the year 1839, Professor Owen was sitting alone in his study, when 
 a shabbily-dressed man made his appearance, announcing that he had 
 got a great curiosity, which he had brought from New Zealand, and 
 wished to dispose of to him. It had the appearance of an old mar- 
 row-bone, about six inches in length, and rather more than two inches 
 in thickness, with both extremities broken off; and Professor Owen consi- 
 dered that, to whatever animal it mi^ht have belonged, the fragment 
 must have lain in the earth for centuries. At first he considered this 
 same marrow-bone to have belonged to an ox, at all events to a quad- 
 ruped ; for the wall or rim of the bone was six times as thick as the bone 
 of any bird, even of the ostrich. He compared it with the bones in the 
 skeleton of an ox, a horse, a camel, a tapir, and every quadruped ap- 
 parently possessing a bone of that size and configuration ; but it corre- 
 sponded with none. On this he very narrowly examined the surface of 
 the bony rim, and at length became satisfied that this fragment must 
 have belonged to a bird 1 to one at least as large as an ostrich, but of 
 a totally different species ; and consequently one never before heard of, 
 as an ostrich was by far the biggest bird known. 
 
 From the difference in the strength of the bone, the ostrich being un- 
 able to fly, so must have been unable this unknown bird ; and so our 
 anatomist came to the conclusion that this old shapeless bone indicated 
 the former existence in New Zealand of some huge bird, at least as 
 great as an ostrich, but of a far heavier and more sluggish kind. Pro- 
 fessor Owen was confident of the validity of his conclusions, but would 
 communicate that confidence to no one else ; and notwithstanding at- 
 tempts to dissuade him from committing his views to the public, he 
 Printed his deductions in the Transactions of the Zoological Society for 
 839, where fortunately they remain on record as conclusive evidence of 
 the fact of his having then made this guess, so to speak, in the dark. 
 He caused the bone, however, to be engraved ; and having sent a hun- 
 
 * Dr. A. Thomson has communicated to Jameson's Journal, No. 112, a De- 
 scription of the Caves in the North Island, with some general observations on 
 this genus of birds. He concludes them to have been indolent, dull, and stupid; 
 to have lived chiefly on vegetable food in mountain fastnesses and secluded 
 caverns. 
 
 In the picture-gallery at Drayton Manor, the seat of Sir Robert Peel, hangs a 
 portrait of Professor Owen, and in his hand is depicted the tibia of a Moa. 
 
Curiosities of Science. 141 
 
 dred copies of the engraving to New Zealand, in the hope of their being 
 distributed and leading to interesting results, he patiently waited for 
 three years, viz. till the year 1842, when he received intelligence 
 from Dr. Buckland, at Oxford, that a great box, just arrived from New 
 Zealand, consigned to himself, was on its way, unopened, to Professor 
 Owen, who found it filled with bones, palpably of a bird, one of which 
 bones was three feet in length, and much more than double the size of 
 any bone in the ostrich ! 
 
 And out of the contents of this box the Professor was positively en- 
 abled to articulate almost the entire skeleton of a huge wingless bird 
 between TEN and ELEVEN feet in height, its bony structure in strict con- 
 formity with the fragment in question ; and that skeleton may at any 
 time be seen at the Museum of the College of Surgeons, towering over, 
 and nearly twice the height of, the skeleton of an ostrich ; and at its feet 
 lying the old bone from which alone consummate anatomical science had 
 deduced such an astounding reality, the existence of an enormous ex- 
 tinct creature of the bird kind, in an island where previously no bird 
 had been known to exist larger than a pheasant or a common fowl t 
 Lecture on tke Moral and Intellectual Development of the present Age.* 
 
 "THE MAESTEICHT SAUKIAN FOSSIL" A FRAUD. 
 
 In 1795, there was stated to have been discovered in the 
 stone quarries adjoining Maestricht the remains of the gigan- 
 tic Mosoesaurus (Saurian of the Meuse), an aquatic reptile about 
 twenty-five feet long, holding an intermediate place between 
 the Monitors and Iguanas. It appears to have had webbed feet, 
 and a tail of such construction as to have served for a powerful 
 oar, and enabled the animal to stem the waves of the ocean, of 
 which Cuvier supposed it to have been an inhabitant. It is 
 thus referred to by Dr. Mantell, in his Medals of Creation : "A 
 specimen, with the jaws and bones of the palate, now in the 
 Museum at Paris, has long been celebrated ; and is still the most 
 precious relic of this extinct reptile hitherto discovered." An 
 admirable cast of this specimen is preserved in the British Mu- 
 seum, in a case near the bones of the Iguanodon. This is, how- 
 ever, useless, as Cuvier is proved to have been imposed upon in 
 the matter. 
 
 M. Schlegel has reported to the French Academy of Sciences, that 
 he has ascertained beyond all doubt that the famous fossil saurian of 
 the quarries of Maestricht, described as a wonderful curiosity by Cuvier, 
 is nothing more than an impudent fraud. Some bold impostor, it seems, 
 in order to make money, placed a quantity of bones in the quarries in 
 such a way as to give them the appearance of having been recently dug 
 up, and then passed them off as specimens of antediluvian creation. 
 Being successful in this, he went the length of arranging a number of 
 bones so as to represent an entire skeleton ; and had thus deceived the 
 
 * According to the law of correlation, so much insisted on by Cuvier, a supe- 
 rior character implies the existence of its inferiors, and that too in definite pro- 
 portions and constant connections ; so that we need only the assurance of one 
 character, to be able to reconstruct the whole animal. The triumph of this system 
 is seen in the reconstruction of extinct animals, as in the above case of the Di- 
 norais, accomplished by Professor Owen. 
 
142 Things not generally Known. 
 
 learned Cuvier. In extenuation of Cuvier's credulity, it is stated that 
 the bones were so skilfully coloxired as to make them look of immense 
 antiquity, and he was not allowed to touch them lest they should crumble 
 to pieces. But when M. Schlegel subjected them to rude handling, he 
 found that they were comparatively modern, and that they were placed 
 one by the other without that profound knowledge of anatomy which 
 was to have been expected from the man bold enough to execute such 
 an audacious fraud. 
 
 " THE OLDEST PIECE OF WOOD UPON EARTH." 
 
 The most remarkable vegetable relic which the Lower Old 
 Red Sandstone has given us is a small fragment of a coniferous 
 tree of the Araucarian family, which formed one of the chief 
 ornaments of the late Hugh Miller's museum, and to which he 
 used to point as the oldest piece of wood upon earth. He found 
 it in one of the ichthyolite beds of Cromarty, and thus refers to 
 it in his Testimony of the Rocks : 
 
 On what perished land of the early paleozoic ages did this venerably 
 antique tree cast root and flourish, when the extinct genera Pterichthys 
 and Coccoeteus were enjoying life by millions in the surrounding seas, 
 long ere the flora or fauna of the coal measures had begun to be? 
 
 The same nodule which enclosed this lignite contained part of another 
 fossil, the well-marked scales of Diplacanthus striatus, an ichthyolite re- 
 stricted to the Lower Old Red Sandstone exclusively. If there be any 
 value in paleontological evidence, this Cromarty lignite must have been 
 deposited in a sea inhabited by the Coccoeteus and Diplacanthus. It 
 is demonstrable that, while yet in a recent state, a Diplacanthus lay down 
 and died beside it ; and the evidence in the case is unequivocally this, 
 that in the oldest portion of the oldest terrestrial flora yet known there 
 occurs the fragment of a tree quite as high in the scale as the stately 
 Norfolk-Island pine or the noble cedar of Lebanon. 
 
 NO FOSSIL HOSE. 
 
 Professor Agassiz, in a lecture upon the trees of America, 
 states a remarkable fact in regard to the family of the rose, 
 which includes among its varieties not only many of the 
 most beautiful flowers, but also the richest fruits, as the apple, 
 pear, peach, plum, apricot, cherry, strawberry, raspberry, &c., 
 namely, that no fossil plants belonging to this family have ever 
 been discovered by geologists ! This M. Agassiz regards as con- 
 clusive evidence that the introduction of this family of plants 
 upon the earth was coeval with, or subsequent to, the creation 
 of man, to whose comfort and happiness they seem especially 
 designed by a wise Providence to contribute. 
 
 CHANGES ON THE EARTH'S SURFACE. 
 
 In the Imperial Library at Paris is preserved a manuscript 
 work by an Arabian writer, Mohammed Karurini, who nourished 
 in the seventh century of the Hegira, or at the close of the 
 thirteenth century of our era. Herein we find several curious 
 
Curiosities of Science. 143 
 
 remarks on aerolites and earthquakes, and the successive 
 changes of position which the land and sea have undergone. 
 Of the latter class is the following beautiful passage from the 
 narrative of Khidz, an allegorical personage : 
 
 I passed one day by a very ancient and wonderfully populous city, 
 and asked one of its inhabitants how long it had been founded. "It is 
 indeed a mighty city," replied he ; " we know not how long it has ex- 
 isted, and our ancestors were on this subject as ignorant as cm-selves." 
 Five centuries afterwards, as I passed by the same place, I could not 
 perceive the slightest vestige of the city. I demanded of a peasant who 
 was gathering herbs upon its former site how long it had been destroyed. 
 " In sooth, a strange question," replied he ; " the ground here has never 
 been different from what you now behold it." " Was there not of old," 
 said I, "a splendid city here ?" " Never," answered he, "so far as we 
 have seen ; and never did our fathers speak to us of any such." On my 
 return there five hundred years afterwards, I found the sea in the same 
 place ; and on its shores were a party of fishermen, of whom I inquired 
 how long the land had been covered by the waters. " Is this a question," 
 say they, " for a man like you ? This spot has always been what it is 
 now." I again returned five hundred years afterwards; the sea had 
 disappeared : I inquired of a man who stood alone upon the spot how 
 long this change had taken place, and he gave me the same answer as 
 I had received before. Lastly, on coming back again after an equal 
 lapse of time, I found there a flourishing city, more populous and more 
 rich in beautiful buildings than the city I had seen the first time ;. and 
 when I would fain have informed myself concerning its origin, the in- 
 habitants answered me, "Its rise is lost in remote antiquity : we are 
 ignorant how long it has existed, and our fathers were on this subject 
 as ignorant as ourselves." 
 
 This striking passage was quoted in the Examiner ', in 1834. 
 Surely in this fragment of antiquity we trace the " geological 
 changes" of modern science. 
 
 GEOLOGICAL TIME. 
 
 Many ingenious calculations have been made to approxi- 
 mate the dates of certain geological events ; but these, it must 
 be confessed, are more amusing than instructive. For example, 
 so many inches of silt are yearly laid down in the delta of the 
 Mississippi how many centuries will it have taken to accu- 
 mulate a thickness of 30, 60, or 100 feet ? Again, the ledges 
 of Niagara are wasting at the rate of so many feet per century 
 how many years must the river have taken to cut its way 
 back from Queeustown to the present Falls ? Again, lavas 
 and melted basalts cool, according to the size of the mass, at 
 the rate of so many degrees in a given time how many mil- 
 lions of years must have elapsed, supposing an original igneous 
 condition of the earth, before its crust had attained a state of 
 solidity ? or further, before its surface had cooled down to the 
 present mean temperature ? For these and similar computa- 
 tions, the student will at once perceive we want the necessaiy 
 
144 Things not generally Known. 
 
 uniformity of factor ; and until we can bring elements of cal- 
 culation as exact as those of astronomy to bear on geological 
 chronology, it will be better to regard our " eras" and " epochs" 
 and " systems" as so many terms, indefinite in their duration, 
 but sufficient for the magnitude of the operations embraced 
 within their limits. Advanced Textbook of Geology, by David 
 Page, F.G.S. 
 
 M. Rozet, in 1841, called attention to the fact, that the 
 causes which have produced irregularities in the structure of 
 the globe have not yet ceased to act, as is proved by earth- 
 quakes, volcanic eruptions, slow and continuous movements 
 of the crust of the earth in certain regions, &c. We may, 
 therefore, yet see repeated the great catastrophes which the 
 surface of the earth has undergone anteriorly to the histori- 
 cal period. 
 
 At the meeting of the British Association in 1855, Mr. Hop- 
 kins excited much controversy by his startling speculation 
 that 9000 years ago the site on which London now stands was 
 in the torrid zone ; and that, according to perpetual changes 
 in progress, the whole of England would in time arrive within 
 the Arctic circle. 
 
 CURIOUS CAUSE OF CHANGE OF LEVEL. 
 
 Professor Hennessey, in 1857, found the entire mass of rock 
 and hill on which the Armagh Observatory is erected to be slightly, 
 but to an astronomer quite perceptibly, tilted or canted, at one season 
 to the east, at another to the west. This he at first attributed to 
 the varying power of the sun's radiation to heat and expand 
 the rock throughout the year; but he subsequently had reason 
 to attribute it rather to the infiltration of water to the parts 
 where the clay-slate and limestone rocks met, the varying 
 quantity of the water exerting a powerful hydrostatic energy 
 by which the position of the rock is slightly varied. 
 
 Now Armagh and its observatory stand at the junction of 
 the mountain limestone with the clay-slate, having, as it were, 
 one leg on the former and the other on the latter ; and both 
 rocks probably reach downwards 1000 or 2000 feet. When 
 rain falls, the one will absorb more water than the other ; both 
 will gain an increase of conductive power ; but the one which 
 has absorbed most water will have the greatest increase, and 
 being thus the better conductor, will draw a greater portion of 
 heat from the hot nucleus below to the surface will become, in 
 fact, temporarily hotter, and, as a consequence, expand more 
 than the other. In a word, both rocks will expand at the wet 
 season; but the best conductor, or most absorbent rock, will expand 
 most, and seem to tilt the hill to one side; at the dry season it will 
 
Curiosities of Science. 145 
 
 subside most, and the hill will seem to be tilted in the opposite di- 
 rection. 
 
 The fact is curious, and not less so are the results deduci- 
 ble from it. First, hills are higher at one season than another ; 
 a fact we might have supposed, but never could have ascer- 
 tained by measurement. Secondly, they are highest, not, as we 
 should have supposed, at the hottest season, but at the wettest. 
 Thirdly, it is from the different rates of expansion of different 
 rocks that this has been discovered. Fourthly, it is by converse 
 with the heavens that it has been made known to us. A va- 
 riation of probably half a second, or less, in the right ascension 
 of three or four stars, observed at different seasons, no doubt 
 revealed the fact to the sagacious astronomer of Armagh, and 
 even enabled him to divine its cause. 
 
 Professor Hennessey observes in connection with this phenomenon, 
 that a very small change of ellipticity would suffice to lay bare or sub- 
 merge extensive tracts of the globe. If, for example, the mean ellip- 
 ticity of the ocean increased from ^ to | , the level of the sea would 
 be raised at the equator by about 228 feet, while under the parallel of 
 52 it would be depressed by 196 feet. Shallow seas and banks in the 
 latitudes of the British isles, and between them and the pole, would 
 thus be converted into dry land, while low-lying plains and islands near 
 the equator would be submerged. If similar phenomena occurred during 
 early periods of geological history, they would manifestly influence the 
 distribution of land and water during these periods ; and with such a 
 direction of the forces as that referred to, they would tend to increase 
 the proportion of land in the polar and temperate regions of the earth, 
 as compared with the equatorial regions during successive geological 
 epochs. Such maps as those published by Sir Charles Lyell on the dis- 
 tribution of land and water in Europe during the Tertiary period, and 
 those of M. Elie de Beaumont, contained in Beaudant's Geology, would, 
 if sufficiently extended, assist in verifying or disproving these views. 
 
 THE OUTLINES OF CONTINENTS NOT FIXED. 
 
 Continents (says M. Agassiz) are only a patchwork formed 
 by the emergence and subsidence of land. These processes are 
 still going on in various parts of the globe. Where the shores 
 of the continent are abrupt and high, the effect produced may 
 be slight, as in Norway and Sweden, where a gradual elevation 
 is going on without much alteration in their outlines. But if 
 the continent of North America were to be depressed 1000 feet, 
 nothing would remain of it except a few islands, and any ele- 
 vation would add vast tracts to its shores. 
 
 The west of Asia, comprising Palestine and the country 
 about Ararat and the Caspian Sea, is below the level of the 
 ocean, and a rent in the mountain-chains by which it is sur- 
 rounded would transform it into a vast gulf. 
 
146 Things not generally Known. 
 
 jfleteorologtcal 
 
 THE ATMOSPHERE. 
 
 A PHILOSOPHER of the East, with a richness of imagery truly 
 oriental, describes the Atmosphere as " a spherical shell which 
 surrounds our planet to a depth which is unknown to us, by 
 reason of its growing tenuity, as it is released from the pres- 
 sure of its own superincumbent mass. Its upper surface can- 
 not be nearer to us than 50, and can scarcely be more remote 
 than 500, miles. It surrounds us on all sides, yet we see it not; 
 it presses on us with a load of fifteen pounds on every square 
 inch of surface of our bodies, or from seventy to one hundred 
 tons on us in all, yet we do not so much as feel its weight. 
 Softer than the softest down, more impalpable than the finest 
 gossamer, it leaves the cobweb undisturbed, and scarcely stirs 
 the lightest flower that feeds on the dew it supplies ; yet it 
 bears the fleets of nations on its wings around the world, and 
 crushes the most refractory substances with its weight. When 
 in motion, its force is sufficient to level the most stately forests 
 and stable buildings with the earth to raise the waters of the 
 ocean into ridges like mountains, and dash the strongest ships 
 to pieces like toys. It warms and cools by turns the earth and 
 the living creatures that inhabit it. It draws up vapours from 
 the sea and land, retains them dissolved in itself or suspended 
 in cisterns of clouds, and throws them down again as rain or 
 dew when they are required. It bends the rays of the sun 
 from their path to give us the twilight of evening and of dawn ; 
 it disperses and refracts their various tints to beautify the ap- 
 proach and the retreat of the orb of day. But for the atmosphere 
 sunshine would burst on us and fail us at once, and at once 
 remove us from midnight darkness to the blaze of noon. We 
 should have no twilight to soften and beautify the landscape ; 
 no clouds to shade us from the searching heat ; but the bald 
 earth, as it revolved on its axis, would turn its tanned and 
 weakened front to the full and unmitigated rays of the lord of 
 day. It affords the gas which vivifies and warms our frames, 
 and receives into itself that which has been polluted by use 
 and is thrown off as noxious. It feeds the flames of life exactly 
 as it does that of the fire it is in both cases consumed and 
 affords the food of consumption in both cases it becomes 
 combined with charcoal, which requires it for combustion and 
 is removed by it when this is over." 
 
Curiosities of Science. 147 
 
 UNIVEKSALITY OF THE ATMOSPHERE. 
 
 It is only the girdling, encircling air that flows above and 
 around all that makes the whole world kin. The carbonic acid 
 with which to-day our breathing fills the air, to-morrow makes 
 its way round the world. The date- trees that grow round the 
 falls of the Nile will drink it in by their leaves ; the cedars of 
 Lebanon will take of it to add to their stature ; the cocoa- 
 nuts of Tahiti will grow rapidly upon it ; and the palms and ba- 
 nanas of Japan will change it into flowers. The oxygen we are 
 breathing was distilled for us some short time ago by the mag- 
 nolias of the Susquehanna; the great trees that skirt the Ori- 
 noco and the Amazon, the giant rhododendrons of the Hima- 
 layas, contributed to it, and the roses and myrtles of Cashmere, 
 the cinnamon-tree of Ceylon, and the forest, older than the 
 Flood, buried deep in the heart of Africa, far behind the Moun- 
 tains of the Moon. The rain we see descending was thawed 
 for us out of the icebergs which have watched the polar star 
 for ages ; and the lotus-lilies have soaked up from the Nile, and 
 exhaled as vapour, snows that rested on the summits of the 
 Alps. North-British Review. 
 
 THE HEIGHT OF THE ATMOSPHF.KE. 
 
 The differences existing between that which appertains to 
 the air of heaven (the realms of universal space) and that which 
 belongs to the strata of our terrestrial atmosphere are very 
 striking. It is not possible, as well-attested facts prove, per- 
 fectly to explain the operations at work in the much-contested 
 upper boundaries of our atmosphere. The extraordinary light- 
 ness of whole nights in the year 1831, during which small print 
 might be read at midnight in the latitudes of Italy and the north 
 of Germany, is a fact directly at variance with all we know 
 according to the researches on the crepuscular theory and the 
 height of the atmosphere. The phenomena of light depend 
 upon conditions still less understood ; and their variability at 
 twilight, as well as in the zodiacal light, excite our astonish- 
 ment. Yet the atmosphere which surrounds the earth is not 
 thicker in proportion to the bulk of our globe than the line of 
 a circle two inches in diameter when compared with the space 
 which it encloses, or the down on the skin of a peach in com- 
 parison with the fruit inside. 
 
 COLOURS OF THE ATMOSPHERE. 
 
 Pure air is blue, because, according to Newton, the mole- 
 cules of the air have the thickness necessary to reflect blue rays. 
 When the sky is not perfectly pure, and the atmosphere is 
 blended with perceptible vapours, the diffused light is mixed 
 
148 Things not generally Known. 
 
 with a large proportion of white. As the moon is yellow, the 
 blue of the air assumes somewhat of a greenish tinge, or, in 
 other words, becomes blended with yellow. Letter from Arago 
 toHumboldt; Cosmos, vol. iii. 
 
 BEAUTY OF TWILIGHT. 
 
 This phenomenon is caused by the refraction of solar light 
 enabling it to diffuse itself gradually over our hemisphere, ob- 
 scured by the shades of night, long before the sun appears, even 
 when that luminary is eighteen degrees below our horizon. It 
 is towards the poles that this reflected splendour of the great 
 luminary is longest visible, often changing the whole of the 
 night into a magic day, of which the inhabitants of southern 
 Europe can form no adequate conception. 
 
 HOW PASCAL WEIGHED THE ATMOSPHERE. 
 
 Pascal's treatise on the weight of the whole mass of air 
 forms the basis of the modern science of Pneumatics. In order 
 to prove that the mass of air presses by its weight on all the 
 bodies which it surrounds, and also that it is elastic and com- 
 pressible, he carried a balloon, half-filled with air, to the top 
 of the Puy de Dome, a mountain about 500 toises above Cler- 
 mont, in Auvergne. It gradually inflated itself as it ascended, 
 and when it reached the summit it was quite full, and swollen 
 as if fresh air had been blown into it ; or, what is the same 
 thing, it swelled in proportion as the weight of the column of 
 air which pressed upon it was diminished. When again brought 
 down it became more and more flaccid, and when it reached 
 the bottom it resumed its original condition. In the nine 
 chapters of which the treatise consists, Pascal shows that all 
 the phenomena and effects hitherto ascribed to the horror of a 
 vacuum arise from the weight of the mass of air ; and after ex- 
 plaining the variable pressure of the atmosphere in different 
 localities and in its different states, and the rise of water in 
 pumps, he calculates that the whole mass of air round our globe 
 weighs 8,983,889,440,000,000,000 French pounds. North- 
 British Review, No. 2. 
 
 It seems probable, from many indications, that the greatest 
 height at which visible clouds ever exint does not exceed ten 
 miles ; at which height the density of the air is about an eighth 
 part of what it is at the level of the sea. Sir John Herschel. 
 
 VARIATIONS OF CLIMATE. 
 
 History informs us that many of the countries of Europe 
 which now possess very mild winters, at one time experienced 
 severe cold during this season of the year. The Tiber, at Rome, 
 was often frozen over, and snow at one time lay for forty days 
 
Curiosities of Science. 149 
 
 in that city. The Euxine Sea was frozen over every winter 
 during the time of Ovid, and the rivers Rhine and Rhone used 
 to be frozen over so deep that the ice sustained loaded wagons. 
 The waters of the Tiber, Rhine, and Rhone, now flow freely 
 every winter; ice is unknown in Rome, and the waves of the 
 Euxiue dash their wintry foam uncrystallised upon the rocks. 
 Some have ascribed these climate changes to agriculture the 
 cutting down of dense forests, the exposing of the unturned soil 
 to the summer's sun, and the draining of great marshes. We 
 do not believe that such great changes could be produced on 
 the climate of any country by agriculture ; and we are certain 
 that no such theory can account for the contrary change of cli- 
 mate from warm to cold winters which history tells us has 
 taken place in other countries than those named. Greenland 
 received its name from the emerald herbage which once clothed 
 its valleys and mountains ; and its east coast, which is now in- 
 accessible on account of perpetual ice heaped upon its shores, 
 was in the eleventh century the seat of flourishing Scandina- 
 vian colonies, all trace of which is now lost. Cold Labrador was 
 named Vinland by the Northmen, who visited it A.D. 1000, and 
 were charmed with its then mild climate. The cause of these 
 changes is an important inquiry. Scientific American. 
 
 AVERAGE CLIMATES. 
 
 When we consider the numerous and rapid changes which 
 take place in our climate, it is a remarkable fact, that the mean 
 temperature of a place remains nearly the same. The winter may 
 be unusually cold, or the summer unusually hot, while the 
 mean temperature has varied even less than a degree. A very 
 warm summer is therefore likely to be accompanied with a 
 cold winter ; and in general, if we have any long period of 
 cold weather, we may expect a similar period at a higher tem- 
 perature. In general, however, in the same locality the rela- 
 tive distribution over summer and winter undergoes compara- 
 tively small variations ; therefore eveiy point of the globe has 
 an average climate, though it is occasionally disturbed by dif- 
 ferent atmospheric changes. North-British Review, No. 49. 
 
 THE FINEST CLIMATE IN THE WORLD. 
 
 Humboldt regards the climate of the Caspian Sea as the 
 most salubrious in the world : here he found the most delicious 
 fruits that he saw during his travels ; and such was the purity 
 of the air, that polished steel would not tarnish even by night 
 exposure. 
 
150 Things not generally Known. 
 
 THE PUBEST ATMOSPHEEES. 
 
 The cloudless purity and transparency of the atmosphere, 
 which last for eight mouths at Santiago, in Chili, are so great, 
 that Lieutenant Gilliss, with the first telescope ever constructed 
 in America, having a diameter of seven inches, was clearly able 
 to recognise the sixth star in the trapezium of Orion. If we 
 are to rely upon the statements of the Rev. Mr. Stoddart, an 
 American missionary, Oroouaiah, in Persia, seems to be, in so 
 far as regards the transparency of the atmosphere, the most 
 suitable place in the world for an astronomical observatory. 
 Writing to Sir John Herschel from that country, he mentions 
 that he has been enabled to distinguish with the naked eye the 
 satellites of Jupiter, the crescent of Venus, the rings of Saturn, 
 and the constituent members of several double stars. 
 
 SEA-BREEZES AND LAND-BREEZES ILLUSTRATED. 
 
 When a fire is kindled on the hearth, we may, if we will 
 observe the motes floating in the room, see that those nearest 
 the chimney are the first to feel the draught and to obey it, 
 they are drawn into the blaze. The circle of inflowing air is 
 gradually enlarged, until it is scarcely perceived in the remote 
 parts of the room. Now the laud is the hearth, the rays of the 
 sun the fire, and the sea, with its cool and calm air, the room ; 
 and thus we have at our firesides the sea-breeze in miniature. 
 
 When the sun goes down, the fire ceases ; then the dry laud 
 commences to give off its surplus heat by radiation, so that by 
 nine or ten o'clock it and the air above it are cooled below the 
 sea temperature. The atmosphere on the land thus becomes 
 heavier than that on the sea, and consequently there is a wind 
 seaward, which we call the land-breeze. Maury. 
 
 SUPERIOR SALUBRITY OF THE WEST. 
 
 All large cities and towns have their best districts in the 
 West ;* which choice the French savans, Pelouze, Pouillet. 
 Boussingault, and Elie de Beaumont, attribute to the law of 
 atmospheric pressure. " When," say they, " the barometric 
 column rises, smoke and pernicious emanations rapidly evapor- 
 ate in space. On the contrary, smoke aud^noxious vapours re- 
 
 * Not only at London, but at Paris, Vienna, Berlin, Turin St. Petersburg, 
 and almost every other capital in Europe ; at Liege. Caen, Montpellier. Toulouse, 
 and several other large towns. wherever, in fact, there are nut great local obsta- 
 cles, the tendency of the wealthier inhabitants to group themselves to the west 
 is as strongly marked as in the British metropolis. At Pompeii. tid other an- 
 cient towns, the same thing may be noticed ; and where the local configuration of 
 the town necessitates an increase in a different direction, the moment the obsta- 
 cle ceases houses spread towards the west. 
 
Curiosities of Science. 151 
 
 main in apartments, and on the surface of the soil. Now, 
 of all winds, that which causes the greatest ascension of the 
 barometric column is the east; and that which lowers it most 
 is the west. When the latter blows, it carries with it to the 
 eastern parts of the town all the deleterious gases from the 
 west ; and thus the inhabitants of the east have to support 
 their own smoke and miasma, and those brought by western 
 winds. When, on the contrary, the east wind blows, it purifies 
 the air by causing to ascend the pernicious emanations which it 
 cannot drive to the west. Consequently, the inhabitants of the 
 west receive pure air, from whatever part of the horizon it may 
 arrive ; and as the west winds are most prevalent, they are the 
 first to receive the air pure, and as it arrives from the country. 
 
 FERTILISATION OF CLOUDS. 
 
 As the navigator cruises in the Pacific Ocean among the 
 islands of the trade-wmd region, he sees gorgeous piles of cu- 
 muli, heaped up in fleecy masses, not only capping the island 
 hills, but often overhanging the lowest islet of the tropics, and 
 even standing above coral patches and hidden reefs ; " a cloud 
 by day." to serve as a beacon to the lonely mariner out there at 
 sea, and to warn him of shoals and dangers which no lead nor 
 seaman's eye has ever seen or sounded. These clouds, under 
 favourable circumstances, may be seen gathering above the low 
 coral island, preparing it for vegetation and fruitfulness in a 
 very striking manner. As they are condensed into showers, 
 one fancies that they are a sponge of the most exquisite and de- 
 licately elaborated material, and that he can see, as they " drop 
 down their fatness," the invisible but bountiful hand aloft that 
 is pressing and squeezing it out. Maury. 
 
 BAROMETRIC MEASUREMENT. 
 
 We must not place too implicit a dependence on Barometri- 
 cal Measurements. Ermann in Siberia, and Ross in the Antarc- 
 tic Seas, have demonstrated the existence of localities on the 
 earth's surface where a permanent depression of the barometer 
 prevails to the astonishing extent of nearly an inch. 
 
 GIGANTIC BAROMETER. 
 
 In the Great Exhibition Building of 1851 was a colossal 
 Barometer, the tube and scale reaching from the floor of the 
 gallery nearly to the top of the building, and the rise and fall 
 of the indicating fluid being marked by feet instead of by tenths 
 of inches. The column of mercury, supported by the pressure 
 of the atmosphere, communicated with a perpendicular tube of 
 
152 Things not generally Known. 
 
 smaller bore, which contained a coloured fluid much lighter 
 than mercury. When a diminution of atmospheric pressure oc- 
 curred, the mercury in the large tube descended, and by its fall 
 forced up the coloured fluid in the smaller tube ; the fall of the 
 one being indicated in a magnified ratio by the rise in the other. 
 
 THE ATMOSPHERE COMPARED TO A STEAM-ENGINE. 
 
 In this comparison, by Lieut. Maury, the South Seas them- 
 selves, in all their vast intertropical extent, are the boiler for 
 the engine, and the northern hemisphere is its condenser. The 
 mechanical power exerted by the air and the sun in lifting 
 water from the earth, in transporting it from one place to an- 
 other, and in letting it down again, is inconceivably great. 
 The utilitarian who compares the water-power that the Falls 
 of Niagara would afford if applied to machinery is astonished 
 at the number of figures which are required to express its equi- 
 valent in horse-power. Yet what is the Jiorse-power of the Nia- 
 gara, falling a few steps, in comparison with the horse-power 
 that is required to lift up as high as the clouds and let down 
 again all the water that is discharged into the sea, not only by 
 this river, but by all the other rivers in the world ? The calcu- 
 lation has been made by engineers ; and according to it, the 
 force of making and lifting vapour from each area of one acre 
 that is included on the surface of the earth, is equal to the 
 power of thirty horses ; and for the whole of the earth, it is 800 
 times greater than all the water-power in Europe. 
 
 HOW DOES THE RAIN-MAKING VAPOUR GET FROM THE 
 SOUTHERN INTO THE NORTHERN HEMISPHERE ? 
 
 This comes with such regularity, that our rivers never go 
 dry, and our springs fail not, because of the exact compensa- 
 tion of the grand machine of the atmosphere. It is exquisitely 
 and wonderfully counterpoised. Late in the autumn of the 
 north, throughout its winter, and in early spring, the sun is 
 pouring his rays with the greatest intensity down upon the 
 seas of the southern hemisphere; and this powerful engine, 
 which we are contemplating, is pumping up the water there 
 with the greatest activity ; at the same time, the mean temper- 
 ature of the entire southern hemisphere is about 10 higher 
 than the northern. The heat which this heavy evaporation 
 absorbs becomes latent, and with the moisture is carried 
 through the upper regions of the atmosphere until it reaches 
 our climates. Here the vapour is formed into clouds, con- 
 densed and precipitated ; the heat which held their water in the 
 state of vapour is set free, and becomes sensible heat ; and it is 
 that which contributes so much to temper our winter climate. 
 
Curiosities of Science. 1 53 
 
 It clouds up in winter, turns warm, and we say we are going 
 to have falling weather : that is because the process of con- 
 densation has already commenced, though no rain or snow may 
 have fallen. Thus we feel this southern heat, that has been col- 
 lected by the rays of the sun by the sea, been bottled away by 
 the winds in the clouds of a southern summer, and set free in 
 the process of condensation in our northern winter. 
 
 Thus the South Seas should supply mainly the water for 
 the engine just described, while the northern hemisphere con- 
 denses it ; we should, therefore, have more rain in the north- 
 ern hemisphere. The rivers tell us that we have, at least on 
 the land ; for the great water-courses of the globe, and half 
 the fresh water in the world, are found on the north side of 
 the equator. This fact is strongly corroborative of this hypo- 
 thesis. To evaporate water enough annually from the ocean 
 to cover the earth, on the average, five feet deep with rain ; to 
 transport it from one zone to another ; and to precipitate it 
 in the right places at suitable times and in the proportions 
 due, is one of the offices of the grand atmospherical machine. 
 This water is evaporated principally from the torrid zone. Sup- 
 posing it all to come thence, we shall have encircling the earth 
 a belt of ocean 3000 miles in breadth, from which this atmo- 
 sphere evaporates a layer of water annually sixteen feet in 
 depth. And to hoist up as high as the clouds, and lower down 
 again, all the water, in a lake sixteen feet deep and 3000 miles 
 broad and 24,000 long, is the yearly business of this invisible 
 machinery. What a powerful engine is the atmosphere ! and 
 how nicely adjusted must be all the cogs and wheels and springs 
 and compensations of this exquisite piece of machinery, that it 
 never wears out nor breaks down, nor fails to do its work at 
 the right time and in the right way ! Mauri/. 
 
 THE PHILOSOPHY OF EAIN. 
 
 To understand the philosophy of this beautiful and often 
 sublime phenomenon, a few facts derived from observation and 
 a long train of experiments must be remembered. 
 
 1. Were the atmosphere every where at all times at a uniform tem- 
 perature, we should never have rain, or hail, or snow. The water ab- 
 sorbed by it in evaporation from the sea and the earth's surface would 
 descend in an imperceptible vapour, or cease to be absorbed by the air 
 when it was once fully saturated. 
 
 2. The absorbing power of the atmosphere, and consequently its 
 capability to retain humidity, is proportionally greater in warm than in 
 cold air. 
 
 3. The air near the surface of the earth is warmer than it is in the 
 region of the clouds. The higher we ascend from the earth, the colder 
 do we find the atmosphere. Hence tho perpetual snow on very high 
 moxintains in the hottest climate. 
 
154 Things not generally Known. 
 
 Now when, from continued evaporation, the air is highly 
 saturated with vapour, though it be invisible and the sky cloud- 
 less, if its temperature is suddenly reduced by cold currents de- 
 scending from above or rushing from a higher to a lower lati- 
 tude, its capacity to retain moisture is diminished, clouds are 
 formed, and the result is rain. Air condenses as it cools, and, 
 like a sponge filled with water and compressed, pours out the 
 water which its diminished capacity cannot hold. What but 
 Omniscience could have devised such an admirable arrange- 
 ment for watering the earth ? 
 
 INORDINATE RAINY CLIMATE. 
 
 The climate of the Khasia mountains, which lie north-east 
 from Calcutta, and are separated by the valley of the Burram- 
 pooter River from the Himalaya range, is remarkable lor the 
 inordinate fall of rain the greatest, it is said, which lias ever 
 been recorded. Mr. Yule, an English gentleman, established that 
 in the single month of August 1841 there fell 264 inches of rain, 
 or 22 feet, of which 12^ feet fell in the space of five consecu- 
 tive days. This astonishing fact is confirmed by two other 
 English travellers, who measured 30 inches of rain in twenty- 
 four hours, and during seven months above 500 inches. This 
 great rain-fall is attributed to the abruptness of tiie moun- 
 tains which face the Bay of Bengal, and the intervening flat 
 swamps 200 miles in extent. The district of the excessive rain 
 is extrem ly limited; and but a few degrees farther west, rain 
 is said to be almost unknown, and the winter falls of snow to 
 seldom exceed two inches. 
 
 HOW DOES THE NORTH WIND DRIVE AWAY RAIN ? 
 
 We may liken it to a wet sponge, and the decrease of tem- 
 perature to the hand that squeezes that sponge. Finally, reach- 
 ing the cold latitudes, all the moisture that a dew-point of 
 zero, and even far below, can extract, is wrung from it ; and 
 this air then commences " to return according to his circuits" 
 as dry atmosphere. And here we can quote Scripture again : 
 " The north wind driveth away rain." This is a meteorolo- 
 gical fact of hig.i authority and great importance in the study 
 of the circulation of the atmosphere. Mauri/. 
 
 SIZE OF RAIN-DROPS. 
 
 The Drops of Rain vary in their size, perhaps from the 25th 
 to the of an inch in diameter. In parting from the clouds, 
 they precipitate their descent till the increasing resistance op- 
 posed by the air becomes equal to their weight, when they 
 continue to fall with uniform velocity. This velocity is, there 
 
Curiosities of Science. 155 
 
 fore, in a certain ratio to the diameter of the drops ; hence 
 thunder and other showers in which the drops are large pour 
 down faster than a drizzling rain. A drop of the 25th part of 
 an inch, in falling through the air, would, when it had arrived 
 at its uniform velocity, only acquire a celerity of 1 1^ feet per 
 second ; while one of of an inch would equal a velocity of 
 33 feet. Leslie. 
 
 RAINLESS DISTRICTS. 
 
 In several parts of the world there is no rain at all. In the 
 Old World there are two districts of this kind : the desert of 
 Sahara in Africa, and in Asia part of Arabia, Syria, and Per- 
 sia; the other district lies between north latitude 30 and 50, 
 and between 75 and 118 of east longitude, including Thibet, 
 Gobiar Shama, and Mongolia. In the New World the rain- 
 less districts are of much less magnitude, occupying two narrow 
 strips on the shores of Peru and Bolivia, and on the coast of 
 Mexico and Guatemala, with a small district between Trinidad 
 and Panama on the coast of Venezuela. 
 
 ALL THE RAIN IN THE WORLD. 
 
 The Pacific Ocean and the Indian Ocean may be considered 
 as one sheet of water covering an area quite equal in extent to 
 one half of that embraced by the whole surface of the earth ; 
 and the total annual fall of rain on the earth's surface is 186,240 
 cubic imperial miles. Not less than three-fourths of the vapour 
 which makes this rain comes from this waste of waters ; but, 
 supposing that only half of this quantity, that is 93,120 cubic 
 miles of rain, falls upon this sea, and that that much at least 
 is taken up from it again as vapour, this would give 255 cubic 
 miles as the quantity of water which is daily lifted up and 
 poured back again into this expanse. It is taken up at one 
 place, and rained down at another; and in this process, there- 
 fore, we have agencies for multitudes of partial and conflicting 
 currents, all, in their set strength, apparently as uncertain as 
 the winds. 
 
 The better to appreciate the operation of such agencies in 
 producing currents in the sea, imagine a district of 255 square 
 miles to be set apart in the midst of the Pacific Ocean as the 
 scene of operations for one day ; then conceive a machine cap- 
 able of pumping up in the twenty-four hours all the water to 
 the depth of one n'ile in this district. The machine must not 
 only pump up and bear off this immense quantity of water, but 
 it must dischnrgp it again into the sea on the same day, but 
 at some other place. 
 
 All i he great rivers of America, Europe, and Asia are lifted 
 
156 Things not generally Known. 
 
 up by the atmosphere, and flow in invisible streams back 
 through the air to their sources among the hills ; and through 
 channels so regular, certain, and well denned, that the quan- 
 tity thus conveyed one year with the other is nearly the same : 
 for that is the quantity which we see running down to the 
 ocean through these rivers ; and the quantity discharged an- 
 nually by each river is, as far as we can judge, nearly a con- 
 stant. Maury. 
 
 AN INCH OF BAIN ON THE ATLANTIC. 
 
 Lieutenant Maury thus computes the effect of a single Inch 
 of Rain falling upon the Atlantic Ocean. The Atlantic includes 
 an area of twenty-five millions of square miles. Suppose an 
 inch of rain to fall upon only one-fifth of this vast expanse. It 
 would weigh, says our author, three hundred and sixty thou- 
 sand millions of tons : and the salt which, as water, it held in 
 solution in the sea, and which, when that water was taken up 
 as vapour, was left behind to disturb equilibrium, weighed six- 
 teen millions more of tons, or nearly twice as much as all the 
 ships in the world could carry at a cargo each. It might fall 
 in an hour, or it might fall in a day ; but, occupy what time it 
 might hi falling, this rain is calculated to exert so much force 
 which is inconceivably great in disturbing the equilibrium 
 of the ocean. If all the water discharged by the Mississippi 
 river during the year were taken up in one mighty measure, 
 and cast into the ocean at one effort, it would not make a 
 greater disturbance in the equilibrium of the sea than would 
 the fall of rain supposed. And yet so gentle are the opera- 
 tions of nature, that movements so vast are unperceived. 
 
 THE EQUATOEIAL CLOUD-RING. 
 
 In crossing the Equatorial Doldrums, the voyager passes a 
 ring of clouds that encircles the earth, and is stretched around 
 our planet to regulate the quantity of precipitation in the rain- 
 belt beneath it ; to preserve the due quantum of heat on the 
 face of the earth ; to adjust the winds ; and send out for dis- 
 tribution to the four corners vapours in proper quantities, to 
 make up to each river-basin, climate, and season, its quota of 
 sunshine, cloud, and moisture. Like the balance-wheel of a 
 well-constructed chronometer, this cloud-ring affords the grand 
 atmospherical machine the most exquisitely arranged self-com- 
 pensation. Nature herself has hung a thermometer under this 
 cloud-belt that is more perfect than any that man can con- 
 struct, and its indications are not to be mistaken. Maury. 
 
 is another of these calm places. Besides being a region of 
 
Curiosities of Science. 157 
 
 calms and baffling winds, it is a region noted for its rains and 
 clouds, which make it one of the most oppressive and disagree- 
 able places at sea. The emigrant ships from Europe for Aus- 
 tralia have to cross it. They are often baffled in it for two or 
 three weeks ; then the children and the passengers who are of 
 delicate health suffer most. It is a frightful graveyard on the 
 wayside to that golden land. 
 
 BEAUTY OF THE DEW-DROP. 
 
 The Dew-drop is familiar to every one from earliest infancy. 
 Resting in luminous beads on the down of leaves, or pendent 
 from the finest blades of grass, or threaded upon the floating 
 lines of the gossamer, its " orient pearl" varies in size from 
 the diameter of a small pea to the most minute atom that can 
 be imagined to exist. Each of these, like the rain-drops, has 
 the properties of reflecting and refracting light ; hence, from so 
 many minute prisms, the unfolded rays of the sun are sent up 
 to the eye in colours of brilliancy similar to those of the rain- 
 bow. When the sunbeams traverse horizontally a very thickly- 
 bedewed grass-plot, these colours arrange themselves so as to 
 form an iris, or dew-bow ; and if we select any one of these 
 drops for observation, and steadily regard it while we gradually 
 change our position, we shall find the prismatic colours follow 
 each other in their regular order. Wells. 
 
 FALL OF DEW IN ONE YEAK. 
 
 The annual average quantity of Dew deposited in this coun- 
 try is estimated at a depth of about five inches, being about 
 one-seventh of the mean quantity of moisture supposed to be 
 received from the atmosphere all over Great Britain in the 
 year ; or about 22,161,337,355 tons, taking the ton at 252 im- 
 perial gallons. Wells. 
 
 GRADUATED SUPPLY OF DEW TO VEGETATION. 
 
 Each of the different grasses draws from the atmosphere 
 during the night a supply of dew to recruit its energies de- 
 pendent upon its form and peculiar radiating power. Every 
 flower has a power of radiation of its own, subject to changes 
 during the day and night, and the deposition of moisture on 
 it is regulated by the peculiar law which this radiating power 
 obeys ; and this power will be influenced by the aspect which 
 the flower presents to the sky, unfolding to the contemplative 
 mind the most beautiful example of creative wisdom.* 
 
 * By far the most complete set of experiments on the Radiation of Heat from 
 the Earth's Surface at Night which have been published since Dr. Wells's Me- 
 moir On Dew, are those of Mr. Glaisher, F.R.S., f kilos. Trans, for 1847. 
 
158 Things not generally Known. 
 
 WARMTH OF SNOW IN ARCTIC LATITUDES. 
 
 The first warm Snows of August and September (says Dr. 
 Kane), falling on a thickly-bleached carpet of grasses, heaths, 
 and willows., enshrine the flowery growths which nestle round 
 them in a non-conducting air chamber ; and as each successive 
 snow increases the thickness of the cover, we have, before the 
 intense cold of winter sets in, a light cellular bed covered by 
 drift, seven, eight, or ten feet deep, in whioh the plant retains 
 its vitality. Dr. Kane has proved by experiments that the 
 conducting power of the snow is proportioned to its compres- 
 sion by winds, rains, drifts, and congelation. The drifts that 
 accumulate during nine months of the year are dispersed in 
 well-defined layers of different density. We have first the 
 warm cellular snows of fall, which surround the plant ; next 
 the finely-impacted snow-dust of winter ; and above these the 
 later humid deposits of spring. In the earlier summer, in the 
 inclined slopes that face the sun, as the upper snow is melted 
 and sinks upon the more compact layer below it is to a great 
 extent arrested, and runs off like rain from a slope of clay. The 
 plant reposes thus in its cellular bed, safe from the rush of 
 waters, and protected from the nightly frosts by the icy roof 
 above it. 
 
 IMPURITY OF SNOW. 
 
 It is believed that in ascending mountains difficult breath- 
 ing is sooner felt upon snow than upon rock ; and M. Bous- 
 singault, in his account of the ascent of Chirnborazo, attributes 
 this to the sensible deficiency of oxygen contained in the pores 
 of the snow, which is exhaled when it melts. The fact that 
 the air absorbed by snow is impure, was ascertained by De 
 Saussure, and has been confirmed by Boussingault's experi- 
 ments. Quarterly Review, No. 202. 
 
 SNOW PHENOMENON. 
 
 Professor Dove of Berlin relates, in illustration of the for- 
 mation of clouds of Snow over plains situated at a distance 
 from the cooling summits of mountains, that on one occasion a 
 large company had gathered in a ballroom in Sweden. It was 
 one of those icy starlight nights which in that country are 
 so aptly called "iron nights." The weather was clear and 
 cold, and the ballroom was clear and warm ; and the heat was 
 so great, that several ladies fainted. An officer present tried 
 to open a window ; but it was frozen fast to the sill. As a last 
 resort, he broke a pane of glass ; the cold air rushed in, and it 
 snowed in the room. A minute before all was clear j but the 
 
Curiosities of S"iercr. ' 59 
 
 warm air of the room had sustained an amount of moisture in 
 a transparent condition which it was not able to maintain, 
 when mixed with the colder air from without. The vapour 
 was first condensed, and then frozen. 
 
 ABSENCE OF SNOW IN SIBERIA. 
 
 There is in Siberia, M. Ermann informs us, an entire district 
 in which during the winter the sky is constantly clear, and 
 where a single particle of snow never falls. Arago. 
 
 ACCURACY OF THE CHINESE AS OBSERVERS. 
 
 The beautiful forms of snow-crystals have long since at- 
 tracted Chinese observers ; for from a remote period there has 
 been met with in their conversation and books an axiomatic 
 expres ion, to the effect that "snow- flakes are hexagonal," 
 showing the Chinese to be accurate observers of nature. 
 
 PROTECTION AGAINST HAIL AND STORMS. 
 
 Arago relates, that when, in 1847, two small agricultural 
 districts of Bourgoyne had lost by Hail crops to the value of 
 a million and a half of francs, certain of the proprietors went 
 to consult him on the means of protecting them from like 
 disasters. Resting on the hypothesis of the electric origin of 
 hail, Arago suggested the discharge of the electricity of the 
 clouds by means of balloons communicating by a metallic wire 
 with the soil. This project was not carried out ; but Arago 
 persisted in believing in the effectiveness of the method pro- 
 
 Arago, in his Meteorological Esaays, inquires whether the firing of 
 cannon can dissipate storms. He cites several cases in its favour, and 
 others which seem to oppose it ; but he concludes by recommending it 
 to his successors. Whilst Arago was propounding these questions, a 
 person not conversant with science, the poet Me'ry, was collecting facts 
 supporting the view, which he has published in his Paris Futur. His 
 attention was attracted to the firing of cannon to dissipate storms in 
 1828, whilst an assistant in the " Ecole de Tir" at Vincennes. Having 
 observed that there was never any rain in the morning of the exercise 
 of firing, lie waited to examine military records, and found there, as he 
 says, facts which justified the expressions of " Le soleil d'Austerlitz," 
 " Le soleil de juillet," upon the morning of the Revolution of July-; and 
 he concluded by proposing to construct around Paris twelve towers of 
 great he ght, which he calls "tours imbrifuges," each carrying 100 can- 
 nons, which should be discharged into the air on the approach of a 
 storm. About this time an incident occurred which in nowise confirmed 
 the truth of M. Mery's theory The 14th of August was a fine day. On 
 the 15th, the fdte of the Empire, the sun shone out, the canron thun- 
 dered all day long, fireworks and illuminations were Mazing from nine 
 o'clock in the evening. Every thing conspired to verify the hypothesis 
 of M. Mery, and chase away storms for a long time. But towards 
 
160 Things not generally Known. 
 
 eleven in the evening a torrent of rain burst upon Paris, in spite of- the 
 pretended influence of the discharge of cannon, and gave an occasion 
 for the mobile Gallic mind to turn its attention in other directions. 
 
 TERRIFIC HAILSTORM. 
 
 Jansen describes, from the log-book of the Rhijin, Captain 
 Brandligt, iii the South -Indian Ocean (25 south latitude) 
 a Hurricane, accompanied by Hail, by which several of the 
 crew were made blind, others had their faces cut open, and 
 those who were in the rigging had their clothes torn off them. 
 The master of the ship compared the sea " to a hilly landscape 
 in winter covered with snow." Does it not appear as if the 
 " treasures of the hail" were opened, which were "reserved 
 against the time of trouble, against the day of battle and 
 war" ? 
 
 HOW WATERSPOUTS ARE FORMED IN THE JAVA SEA. 
 
 Among the small groups of islands in this sea, in the day 
 and night thunderstorms, the combat of the clouds appears to 
 make them more thirsty than ever. In tunnel form, when they 
 can no longer quench their thirst from the surrounding atmo- 
 sphere, they descend near the surface of the sea, and appear to 
 lap the water directly up with their black mouths. They are 
 not always accompanied by strong winds; frequently more 
 than one is seen at a time, whereupon the clouds whence they 
 proceed disperse, and the ends of the Waterspouts bending 
 over finally causes them to break in the middle. They seldom 
 last longer than five minutes. As they are going away, the 
 bulbous tube, which is as palpable as that of a thermometer, 
 becomes broader at the base ; and little clouds, like steam from 
 the pipe of a locomotive, are continually thrown off from the 
 circumference of the spout, and gradually the water is re- 
 leased, and the cloud whence the spout came again closes its 
 mouth. 
 
 COLD IN HUDSON'S BAY. 
 
 Mr. R. M. Ballantyne, in his journal of six years' residence 
 in the territories of the Hudson's Bay Company, tells us, that 
 for part of October there is sometimes a little warm, or rather 
 thawy, weather ; but after that, until the following April, the 
 thermometer seldom rises to the freezing point. In the depth 
 of winter, the thermometer falls from 30 to 40, 45, and even 
 49 below zero of Fahrenheit. This intense cold is not, however, 
 so much felt as one might suppose ; for during its continuance 
 the air is perfectly calm. Were the slightest breath of wind 
 to rise when the thermometer stands so low, no man could 
 show his face to it for a moment. Forty degrees below zero, 
 
Curiosities of Science. 161 
 
 and quite calm, is infinitely preferable to fifteen below, or 
 thereabout, with a strong breeze of wind. Spirit of wine is, 
 of course, the only thing that can be used in the thermometer ; 
 as mercury, were it exposed to such cold, would remain frozen 
 nearly half the winter. Spirit never froze in any cold ever 
 experienced at York Factory, unless when very much adulter- 
 ated with water ; and even then the spirit would remain liquid 
 in the centre of the mass. Quicksilver easily freezes in this 
 climate, and it has frequently been run into a bullet-mould, 
 exposed to the cold air till frozen, and in this state rammed 
 down a gun-barrel, and fired through a thick plank. The 
 average cold may be set down at about 15 or 16 below zero, 
 or 48 J of frost. The houses at the Bay are built of wood, with 
 double windows and doors. They are heated by large iron 
 stoves, fed with wood ; yet so intense is the cold, that when 
 a stove has been in places red-hot, a basin of water in the room 
 has been frozen solid. 
 
 PURITY OF WENHAM-LAKE ICE. 
 
 Professor Faraday attributes the purity of Wenham-Lake 
 Ice to its being free from air- bubbles and from salts. The 
 presence of the first makes it extremely difficult to succeed in 
 making a lens of English ice which will concentrate the solar 
 rays, and readily fire gunpowder ; whereas nothing is easier 
 than to perform this singular feat of igniting a combustible, 
 body by aid of a frozen mass if Wenham-Lake ice be employed. 
 The absence of salts conduces greatly to the permanence of the 
 ice ; for where water is so frozen that the salts expelled are 
 still contained in air-cavities and cracks, or form thin films 
 between the layers of ice, these entangled salts cause the ice to 
 melt at a lower temperature than 32 J , and the liquefied por- 
 tions give rise to streams and currents within the body of the 
 ice which rapidly carry heat to the interior. The mass then 
 goes on thawing within as well as without, and at tempera- 
 tures below 32 ; whereas pure, compact, Wenham-Lake ice 
 can only thaw at 32, and only on the outside of the mass. 
 Sir Charles LyeWs Second Visit to the United States. 
 
 ARCTIC TEMPERATURES. 
 
 Dr. Kane, in his Second Arctic Expedition, found the ther- 
 mometers beginning to show unexampled temperature : they 
 ranged from 60 to 70 below zero, and upon the taffrail of the 
 brig 65. The reduced mean of the best spirit-standards gave 
 67 or 99 below the freezing point of water. At these tem- 
 peratures chloric ether became solid, and chloroform exhibited 
 a granular pellicle on its surface. Spirit of naphtha froze at 54, 
 and the oil of turpentine was solid at 63 and 65. 
 
 M 
 
162 Things not generally Known. 
 
 DR. EAE'S ARCTIC EXPLORATIONS. 
 
 The gold medal of the Royal Geographical Society was in 
 1852 most rightfully awarded to this indefatigable Arctic ex- 
 plorer. His survey of the inlet of Boothia, in 1848, was unique 
 in its kind. In Repulse Bay he maintained his party on deer, 
 principally shot by himself; and spent ten months of an Arctic 
 winter in a hut of stones, with BO other fuel than a kind of hay 
 of the Andromeda tetragona. Thus he preserved his men to 
 execute surveying journeys of 1000 miles in the spring. Later 
 he travelled 300 miles on snow-shoes. In a spring journey over 
 the ice, with a pound of fat daily for fuel, accompanied by two 
 men only, and trusting solely for shelter to snow-houses, which 
 he taught his men to build, he accomplished 1060 miles in 
 thirty-nine days, or twenty-seven miles per day, including stop- 
 pages, a feat never equalled in Arctic travelling. In the 
 spring journey, and that which followed in the summer in 
 boats, 1700 miles were traversed in eighty days. Dr. Rae's 
 greatest sufferings, he once remarked to Sir George Back, arose 
 from his being obliged to sleep upon his frozen mocassins in 
 order to thaw them for the morning's use. 
 
 PHENOMENA OF THE ARCTIC CLIMATE. 
 
 Sir John Richardson, in his history of his Expedition to 
 these regions, describes the power of the sun in a cloudless sky 
 to have been so great, that he was glad to take shelter in the 
 water while the crews were engaged on the portages ; and he 
 has never felt the direct rays of the sun so oppressive as on 
 some occasions in the high latitudes. Sir John observes : 
 
 The rapid evaporation of both snow and ice in the winter and spring, 
 long before the action of the sun has prod viced the slightest thaw or 
 appearance of moisture, is evident by many facts of daily occurrence. 
 Thus when a shirt, after being washed, is exposed in the open air to a 
 temperature of from 4CP to 50 below zero, it is instantly rigidly frozen, 
 and may be broken if violently bent. If agitated when in this condition 
 by a strong wind, it makes a rustling noise like theatrical thunder, 
 
 In consequence of the extreme dryness of the atmosphere in winter, 
 most articles of English manufacture brought to Rupert's Land are 
 shrivelled, bent, and broken. The handles of razors and knives, combs, 
 ivory scales, &c., kept in the warm room, are changed in this way. The 
 human body also becomes vividly electric from the dryness of the skin. 
 One cold night I rose from my bed, and was going out to observe the 
 
 , 1 .1 L _1-J_T_i 1.1 a~ 1 Jl^i. J T 
 
 was elicited. Friction ot the skm at almost all times in winter pro- 
 duced the electric odour. 
 
 Even at midwinter we had but three hours and a half of daylight. 
 On December 20th I required a candle to write at the window at ten in 
 the morning. The sun was absent ten days, and its place in the heavens 
 
Curiosities of Science. 163 
 
 at noon was denoted by rays of light shooting into the sky above the 
 woods. 
 
 The moon in the long nights was a most beautiful object, that satel- 
 lite being constantly above the horizon for nearly a fortnight together. 
 Venus also shone with a brilliancy which is never witnessed in a sky 
 loaded with vapours ; and, unless in snowy weather, our nights were 
 always enlivened by the beams of the aurora. 
 
 INTENSE HEAT AND COLD OF THE DESERT. 
 
 Among crystalline bodies, rock-crystal, or silica, is the best 
 conductor of heat. This fact accounts for the steadiness of 
 temperature iii one set district, and the extremes of Heat and 
 Cold presented by day and night on such sandy wastes as the 
 Sahara. The sand, which is for the most part silica, drinks-in 
 the noon-day heat, and loses it by night just as speedily. 
 
 The influence of the hot winds from the Sahara has been 
 observed in vessels traversing the Atlantic at a distance of up- 
 wards of 1100 geographical miles from the African shores, by 
 the coating of impalpable dust upon the sails. 
 
 TRANSPORTING POWER OF WINDS. 
 
 The greatest example of their power is the sand-food of 
 Africa, which, moving gradually eastward, has overwhelmed 
 all the land capable of tillage west of the Nile, unless sheltered 
 by high mountains, and threatens ultimately to obliterate the 
 rich plain of Egypt. 
 
 EXHILARATION IN ASCENDING MOUNTAINS. 
 
 At all elevations of from 6000 to 11,000 feet, and not unfre- 
 quently for even 2000 feet more, the pedestrian enjoys a plea- 
 surable feeling, imparted by the consciousness of existence, 
 similar to that which is described as so fascinating by those 
 who have become familiar with the desert-life of the East. The 
 body seems lighter, the nervous power greater, the appetite is 
 increased; and fatigue, though felt for a time, is removed by 
 the shortest repose. Some travellers have described the sensa- 
 tion by the impression that they do not actually press the 
 ground, but that the blade of a knife could be inserted between 
 the sole of the foot and the mountain top. Quarterly Review, 
 No. 202. 
 
 TO TELL THE APPROACH OF STORMS. 
 
 The proximity of Storms has been ascertained with accuracy 
 by various indications of the electrical state of t'he atmosphere. 
 Thus Professor ^Scott, of Sandhurst College, observed in Shet- 
 land that drinking- glasses, placed in an inverted position upon 
 a shelf in a cupboard on the ground-floor of Belmont House, 
 
164- Things not generally Known. 
 
 occasionally emitted sounds as if they were tapped with a knife, 
 or raised a little and then let fall on the shelf. These sounds 
 preceded wind ; and when they occurred, boats and vessels were 
 immediately secured. The strength of the sound is said to be 
 proportioned to the tempest that follows. 
 
 REVOLVING STORMS. 
 
 By the conjoint labours of Mr. Redfield, Colonel Reid, and 
 Mr. Piddington, on the origin and nature of hurricanes, ty- 
 phoons, or revolving storms, the following important results 
 have been obtained. Their existence in moderate latitudes on 
 both sides the equator ; their absence in the immediate neigh- 
 bourhood of the equatorial regions; and the fcict, that while 
 in the northern latitudes these storms revolve in a direction 
 contrary to the hands of a watch the face of which is placed 
 upwards, in the southern latitudes they rotate in the opposite 
 direction, are shown to be so many additions to the long chain 
 of evidence by which the rotation of the earth as a physical 
 fact is demonstrated. 
 
 IMPETUS OF A STORM. 
 
 Captain Sir S. Brown estimates, from experiments made by 
 him at the extremity of the Brighton-Chain Pier in a heavy 
 south-west gale, that the waves impinge on a cylindrical sur- 
 face one foot high and one foot in diameter with a force equal 
 to eighty pounds, to which must be added that of the wind, 
 which in a violent storm exerts a pressure of forty pounds. He 
 computed the collective impetus of the waves on the lower part 
 of a lighthouse proposed to be built on the Wolf Rock (exposed 
 to the most violent storms of the Atlantic), of the surf on the 
 upper part, and of the wind on the whole, to be equal to 100 
 tons. 
 
 HOW TO MAKE A STORM-GLASS. 
 
 This instrument consists of a glass tube, sealed at one end, 
 and furnished with a brass cap at the other end, through which 
 the air is admitted by a very small aperture. Nearly fill the 
 tube with the following solution : camphor, 2| drams; nitrate 
 of potash, 38 grains ; muriate of ammonia, 38 grains ; water, 9 
 drams ; rectified spirit, 9 drams. Dissolve with heat. At the 
 ordinary temperature of the atmosphere, plumose crystals are 
 formed. On the approach of stormy weather, these crystals ap- 
 pear compressed into a compact mass at the bottom of the tube ; 
 while during fine weather they assume their plumose character, 
 and extend a considerable way up the glass. These results de- 
 pend upon the condition of the air, but they are not considered 
 to afford any reliable indication of approaching weather. 
 
Curiosities of Science. 165 
 
 SPLENDOUR OF THE AURORA BOREALIS. 
 
 Humboldt thus beautifully describes this phenomenon : 
 The intensity of this light is at times so great, that Lowenorn (on 
 June 29, 1786) recognised its coruscation in bright sunshine. Moticn 
 renders the phenomenon more visible. Round the point in the vault of 
 heaven which corresponds to the direction of the inclination of the 
 needle the beams unite together to form the so-called corona, the 
 crown of the Northern Light, which encircles the summit of the heavenly 
 canopy with a milder radiance and unflickex*ing emanations of light. 
 It is only iu rare instances that a perfect crown or circle is formed ; but 
 on its completion, the phenomenon has invariably reached its maximum, 
 and the radiations become less frequent, shorter, and more colourless. 
 The crown, and the luminous arches break up; and the whole vault of 
 heaven becomes covered with irregularly scattered, broad, faint, almost 
 ashy-gray, luminous, immovable patches, which in their turn disap- 
 pear, leaving nothing but a trace of a dark smoke-like segment on the 
 horizon. There often remains nothing of the whole spectacle but a white 
 delicate cloud with feathery edges, or divided at equal distances into 
 small roundish groups like cirro-cumuli Cosmos, vol. i. 
 
 Among many theories of this phenomenon is that of Lieu- 
 tenant Hooper, R.N., who has stated to the British Association 
 that he believes " the Aurora Borealis to be no more nor less 
 than the moisture in some shape (whether dew or vapour, liquid 
 or frozen), illuminated by the heavenly bodies, either directly, or 
 reflecting their rays from the frozen masses around the Pole, 
 or even from the immediately proximate snow-clad earth." 
 
 VARIETIES OF LIGHTNING. 
 
 According to Arago's investigations, the evolution of Light- 
 ning is of three kinds : zigzag, and sharply defined at the 
 edges; in sheets of light, illuminating a whole cloud, which 
 seems to open and reveal the light within it ; and in the form 
 of fire-balls. The duration of the first two kinds scarcely con- 
 tinues the thousandth part of a second ; but the globular light- 
 ning moves much more slowly, remaining visible for several 
 seconds. 
 
 WHAT IS SHEET-LIGHTNING ? 
 
 This electric phenomenon is unaccompanied by thunder, or 
 too distant to be heard : when it appears, the whole sky, but 
 particularly the horizon, is suddenly illuminated with a flicker- 
 ing flash. Philosophers differ much as to its cause. Mat- 
 teucci supposes it to be produced either during evaporation, or 
 evolved (according to Pouillet's theory) in the process of vege- 
 tation ; or generated by chemical action in the great laboratory 
 of nature, the earth, and accumulated in the lower strata of the 
 air in consequence of the ground being an imperfect conductor. 
 
 Arago and Kamtz, however, consider sheet-lightning as reflections 
 
166 Things not generally Known. 
 
 of distant thunderstorms, Saussure observed sheet-lightning in the di- 
 rection of Geneva, from the Hospice du Grimsel, on the 10th and llth 
 of July 1783 ; while at the same time a terrific thunderstorm raged at 
 Geneva. Howard, from Tottenham, near London, on July 31, 1813, 
 saw sheet-lightning towards the south-east, while the sky was bespan- 
 gled with stars, not a cloud floating in the air ; at the same time a thun- 
 derstorm raged at Hastings, and in France from Calais to Dunkirk. 
 Arago supports his opinion, that the phenomenon is reflected lightning, 
 by the following illustration : In 1803, when observations were being 
 made for determining the longitude, M. de Zach, on the Brocken, used 
 a few ounces of gunpowder as a signal, the flash of which was visible 
 from the Klenlenberg, sixty leagues off, although these mountains are 
 invisible from each other. 
 
 PRODUCTION OF LIGHTNING BY RAIN. 
 
 A sudden gust of rain is almost sure to succeed a violent 
 detonation immediately overhead. Mr. Birt, the meteorologist, 
 asks : Is this rain a cause or consequence of the electric discharge ? 
 To this he replies : 
 
 In the sudden agglomeration of many minute and feebly electrified 
 globules into one rain-drop, the quantity of electricity is increased in a 
 greater proportion than the surface over which (according to the laws of 
 electric distribution) it is spread. By tension, therefore, it is increased, 
 and may attain the point when it is capable of separating from the drop 
 to seek the surface of the cloud, or of the newly-formed descending body 
 of rain, which, under such circumstances, may be regarded as a conduct- 
 ing medium. Arrived at this surface, the tension, for the same reason, 
 becomes enormous, and a flash escapes. This theory Mr. Birt has con- 
 firmed by observation of rain in thunderstorms. 
 
 SERVICE OF LIGHTNING-CONDUCTORS. 
 
 Sir David Brewster relates a remarkable instance of a tree 
 in Clandeboye Park, in a thick mass of wood, and not the tallest 
 of the group, being struck by lightning, which passed down the 
 trunk into the ground, rending the tree asunder. This shows 
 that an object may be struck by lightning in a locality where 
 there are numerous conducting points more elevated than 
 itself ; and at the same time proves that lightning cannot be 
 diverted from its course by lofty isolated conductors, but that 
 the protection of buildings from this species of meteor can only 
 be effected by conductors stretching out in all directions. 
 
 Professor Silliman states, that lightning-rods cannot be re- 
 lied upon unless they reach the earth where it is permanently 
 wet ; and that the best security is afforded by carrying the rod, 
 or some good metallic conductor duly connected with it, to the 
 water in the well, or to some other water that never fails. The 
 professor's house, it seems, was struck ; but his lightning-rods 
 were not more than two or three inches in the ground, and were 
 therefore virtually of no avail in protecting the building. 
 
Curiosities of Science. 167 
 
 ANCIENT LIGHTNING-CONDUCTOR. 
 
 Humboldt informs us, that " the most important ancient 
 notice of the relations between lightning and conducting metals 
 is that of Ctesias, in his Indica, cap. iv. p. 190. He possessed 
 two iron swords, presents from the king Artaxerxes Mnemon 
 and from his mother Parasytis, which, when planted in the 
 earth, averted clouds, hail, and strokes of lightning. He had 
 himself seen the operation, for the king had twice made the 
 experiment before his eyes." Cosmos, vol. ii. 
 
 THE TEMPLE OF JERUSALEM PROTECTED FROM LIGHTNING. 
 
 We do not learn, either from the Bible or Josephus, that 
 the Temple at Jerusalem was ever struck by Lightning during 
 an interval of more than a thousand years, from the time of 
 Solomon to the year 70 ; although, from its situation, it was 
 completely exposed to the violent thunderstorms of Palestine. 
 
 By a fortuitous circumstance, the Temple was crowned with 
 lightning-conductors similar to those which we now employ, 
 and which we owe to Franklin's discovery. The roof, con- 
 structed in what we call the Italian manner, and covered with 
 boards of cedar, having a thick coating of gold, was garnished 
 from end to end with long pointed and gilt iron or steel lances, 
 which, Josephus says, were intended to prevent birds from roost- 
 ing on the roof and soiling it. The walls were overlaid through- 
 out with wood, thickly gilt. Lastly, there were in the courts 
 of the Temple cisterns, into which the rain from the roof was 
 conducted by metallic pipes. We have here both the lightning- 
 rods and a means of conduction so abundant, that Lichtenberg 
 is quite right in saying that many of the present apparatuses 
 are far from offering in their construction so satisfactory a 
 combination of circumstances. Abridged from Arago*s Meteoro- 
 logical Essays. 
 
 HOW ST. PAUL'S CATHEDRAL is PROTECTED FROM LIGHTNING. 
 
 In March 1769, the Dean and Chapter of St. Paul's ad- 
 dressed a letter to the Royal Society, requesting their opinion 
 as to the best and most effectual method of fixing electrical 
 conductors on the cathedral. A committee was formed for the 
 purpose, and Benjamin Franklin was one of the members ; their 
 report was made, and the conductors were fixed as follows : 
 
 The seven iron scrolls supporting the ball and ci-oss are connected 
 with other rods (used merely as conductors), which unite them with 
 Several large bars, descending obliquely to the stone-work of the lantern, 
 and connected by an iron ring with four other iron bars to the lead 
 covering of the great cupola, a distance of forty-eight feet ; thence the 
 
168 Things not generally Known. 
 
 communication is continued by the rain-water pipes to the lead-covered 
 roof, and thence by lead water-pipes which pass into the earth ; thus 
 completing the entire communication from the cross to the ground, 
 partly through iron, and partly through lead. On the clock-tower a 
 bar of iron connects the pine-apple at the top with the iron staircase, 
 and thence with the lead on the roof of the church. The bell-tower is 
 similarly protected. By these means the metal used in the building is 
 made available as conductors ; the metal employed merely for that pur- 
 pose being exceedingly small in quantity. Curiosities of London. 
 
 VARIOUS EFFECTS OF LIGHTNING. 
 
 Dr. Hibbert tells us that upon the western coast of Scot- 
 land and Ireland, Lightning cooperates with the violence of 
 the storm in shattering solid rocks, and heaping them in piles 
 of enormous fragments, both on dry land and beneath the 
 water. 
 
 Euler informs us, in his Letters to a German Princess, that 
 he corresponded with a Moravian priest named Divisch, who 
 assured him that he had averted during a whole summer every 
 thunderstorm which threatened his own habitation and the 
 neighbourhood, by means of a machine constructed upon the 
 principles of electricity ; that the machinery sensibly attracted 
 the clouds, and constrained them to descend quietly in a dis- 
 tillation, without any but a very distant thunderclap. Euler 
 assures us that " the fact is undoubted, and confirmed by irre- 
 sistible proof." 
 
 About the year 1811, in the village of Phillipsthal, in East- 
 ern Prussia, an attempt was made to split an immense stone 
 into a multitude of pieces by means of lightning. A bar of 
 iron, in the form of a conductor, was previously fixed to the 
 stone ; and the experiment was attended with complete success ; 
 for during the very first thunderstorm the lightning burst the 
 stone without displacing it. 
 
 The celebrated Duhamel du Monceau says, that lightning, 
 unaccompanied by thunder, wind, or rain, has the property of 
 breaking oat-stalks. The farmers are acquainted with this 
 effect, and say that the lightning breaks down the oats. This 
 is a well-received opinion with the farmers in Devonshire. 
 
 Lightning has in some cases the property of reducing solid 
 bodies to ashes, or to pulverisation, even the human body, 
 without there being any signs of heat. The effects of lightning 
 on paralysis are very remarkable, in some cases curing, in others 
 causing, that disease. 
 
 The returning stroke of lightning is well known to be due 
 to the restoration of the natural electric state, after it has been 
 disturbed by induction. 
 
Curiosities of Science. 169 
 
 A THUNDEESTOEM SEEN FEOM A BALLOON. 
 
 Mr. John West, the American aeronaut, in his observations 
 made during his numerous ascents, describes a storm viewed 
 from above the clouds to have the appearance of ebullition. 
 The bulging upper surface of the cloud resembles a vast sea of 
 boiling and upheaving snow ; the noise of the falling rain is 
 like that of a waterfall over a precipice ; the thunder above 
 the cloud is not loud, and the flashes of lightning appear like 
 streaks of intensely white fire on a surface of white vapour. 
 He thus describes a side view of a storm which he witnessed 
 June 3, 1852, in his balloon excursion from Portsmouth, Ohio : 
 Although the sun was shining on me, the rain and small hail were 
 rattling on the balloon. A rainbow, or prismatically-coloured arch or 
 horse-shoe, was reflected against the sun ; and as the point of observa- 
 tion changed laterally and perpendicularly, the perspective of this golden 
 grotto changed its hues and forms. Above and behind this arch was 
 going on the most terrific thunder ; but no zigzag lightning was per- 
 ceptible, only bright flashes, like explosions of " Roman candles" in 
 fireworks. Occasionally there was a- zigzag explosion in the cloud im- 
 mediately below, the thunder sounding like &feu-de-joie of a rifle-corps. 
 Then an orange-coloured wave of light seemed to fall from the upper to 
 the lower cloud; this was "still-lightning."- Meanwhile intense elec- 
 trical action was going on in the balloon, such as expansion, tremulous 
 tension, lifting papers ten feet out of the car below the balloon and 
 then dropping them, &c. The close view of this Ohio storm was truly 
 sublime ; its rushing noise almost appalling. 
 
 Ascending from the earth with a balloon, in the rear of a 
 storm, and mounted up a thousand feet above it, the balloon 
 will soon override the storm, and may descend in advance of 
 it. Mr. West has experienced this several times. 
 
 KEMAEKABLE AEEONAUTIC VOYAGE. 
 
 Mr. Sadler, the celebrated aeronaut, ascended on one occa- 
 sion in a balloon from Dublin, and was wafted across the Irish 
 Channel ; when, on his approach to the Welsh coast, the balloon 
 descended nearly to the surface of the sea. By this time the 
 sun was set, and the shades of evening began to close in. He 
 threw out nearly all his ballast, and suddenly sprang upward 
 to a great height ; and by so doing brought his horizon to dip 
 below the sun, producing the whole phenomenon of a western 
 sunrise. Subsequently descending in Wales, he of course 
 witnessed a second sunset on the same evening. Sir John 
 Herschel's Outlines of Astronomy. 
 
170 Things not generally Known. 
 
 tcal ffieograpljg of tfje 
 
 CLIMATES OF THE SEA. 
 
 THE fauna and flora of the Sea are as much the creatures 
 of Climate, and are as dependent for their well-being upon 
 temperature, as are the fauna and flora of the dry land. Were 
 it not so, we should find the fish and the algae, the marine 
 insect and the coral, distributed equally and alike in all parts 
 of the ocean ; the polar whale would delight hi the torrid 
 zone ; and the habitat of the pearl oyster would be also under 
 the iceberg, or in frigid waters colder than the melting ice. 
 
 THE CIRCULATION OF THE SEA. 
 
 The coral islands, reefs, and beds with which the Pacific 
 Ocean is studded and garnished, were built up of materials 
 which a certain kind of insect quarried from the sea- water. 
 The currents of the sea ministered to this little insect ; they 
 were its hod- carriers. When fresh supplies of solid matter 
 were wanted for the coral rock upon which the foundations of 
 the Polynesian Islands were laid, these hod-carriers brought 
 them in unfailing streams of sea-water, loaded with food and 
 building -materials for the coralline: the obedient currents 
 thread the widest and the deepest sea. Now we know that 
 its adaptations are suited to all the wants of every one of its 
 inhabitants, to the wants of the coral insect as well as those 
 of the whale. Hence we know that the sea has its system of 
 circulation : for it transports materials for the coral rock from 
 one part of the world to another ; its currents receive them 
 from rivers, and hand them over to the little mason for the 
 structure of the most stupendous works of solid masonry that 
 man has ever seen the coral islands of the sea. 
 
 TEMPERATURE OF THE SEA. 
 
 Between the hottest hour of the day and the coldest hour 
 of the night there is frequently a change of four degrees in 
 the Temperature of the Sea. Taking one-fifth of the Atlantic 
 Ocean for the scene of operation, and the difference of four 
 
 * The author is largely indebted for the illustrations in this new field of 
 research to Lieutenant Maury's valuable work, The Physical Geography of the Sea. 
 Sixth edition. Harper, New York ; Low, Son, and Co., London. 
 
Curiosities of Science. 171 
 
 degrees to extend only ten feet below the surface, the total and 
 absolute change made in such a mass of sea-water, by altering 
 its temperature two degrees, is equivalent to a change in its 
 volume of 390,000,000 cubic feet. 
 
 TEANSPAEENCY OF THE OCEAN. 
 
 Captain Glynn, U.S.N., has made some interesting obser- 
 vations, ranging over 200 of latitude, in different oceans, in 
 very high latitudes, and near the equator. His apparatus was 
 simple : a common white dinner-plate, slung so as to lie in 
 the water horizontally, and sunk by an iron pot with a line. 
 Numbering the fathoms at which the plate was visible below 
 the surface, Captain Glynn saw it on two occasions, at the 
 maximum, twenty-five fathoms (150 feet) deep ; the water was 
 extraordinarily clear, and to lie in the boat and look down was 
 like looking down from the mast-head ; and the objects were 
 clearly defined to a great depth. 
 
 THE BASIN OF THE ATLANTIC. 
 
 In its entire length, the basin of this sea is a long trough, 
 separating the Old World from the New, and extending pro- 
 bably from pole to pole. 
 
 This ocean-furrow was scored into the solid crust of our 
 planet by the Almighty hand, that there the waters which 
 " he called seas" might be gathered together so as to " let the 
 dry land appear," and fit the earth for the habitation of man. 
 
 From the top of Chimborazo to the bottom of the Atlan- 
 tic, at the deepest place yet recognised by the plummet in the 
 North Atlantic, the distance in a vertical line is nine miles. 
 
 Could the waters of the Atlantic be drawn off, so as to 
 expose to view this great sea-gash, which separates continents, 
 and extends from the Arctic to the Antarctic, it would present 
 a scene the most grand, rugged, and imposing. The very ribs 
 of the solid earth, with the foundations of the sea, would be 
 brought to light ; and we should have presented to us at one 
 view, in the empty cradle of the ocean, "a thousand fearful 
 wrecks," with that dreadful array of dead men's skulls, great 
 anchors, heaps of pearls and inestimable stones, which, in the 
 dreamer's eye, lie scattered on the bottom of the sea, making 
 it hideous with sights of ugly death. 
 
 GALES OF THE ATLANTIC. 
 
 Lieutenant Maury has, in a series of charts of the North 
 and South Atlantic, exhibited, by means of colours, the pre- 
 valence of Gales over the more stormy parts of the oceans for 
 each month in the year. One colour shows the region in which 
 
172 Things not generally Known. 
 
 there is a gale every six days; another colour every six to ten 
 days ; another every ten to fourteen days : and there is a sepa- 
 rate chart for each month and each ocean. 
 
 SOLITUDE AT SEA. 
 
 Between Humboldt's Current of Peru and the great equa- 
 torial flow, there is " a desolate region," rarely visited by the 
 whale, either sperm or right. Formerly this part of the ocean 
 was seldom whitened by the sails of a ship, or enlivened by the 
 presence of man. Neither the industrial pursuits of the sea 
 nor the highways of commerce called him into it. Now and 
 then a roving cruiser or an enterprising whalesman passed that 
 way ; but to all else it was an unfrequented part of the ocean, 
 and so remained until the gold-fields of Australia and the 
 guano islands of Peru made it a thoroughfare. All vessels 
 bound from Australia to South America now pass through it ; 
 and in the journals of some of them it is described as a region 
 almost void of the signs of life jn both sea and air. In the 
 South-Pacific Ocean especially, where there is such a wide ex- 
 panse of water, sea-birds often exhibit a companionship with 
 a vessel, and will follow and keep company with it through 
 storm and calm for weeks together. Even the albatross and 
 Cape pigeon, that delight in the stormy regions of Cape Horn 
 and the inhospitable climates of the Antarctic regions, not un- 
 frequently accompany vessels into the perpetual summer of the 
 tropics. The sea-birds that join the ship as she clears Aus- 
 tralia will, it is said, follow her to this region, and then dis- 
 appear. Even the chirp of the stormy petrel ceases to be heard 
 here, and the sea itself is said to be singularly barren of " mov- 
 ing creatures that have life." 
 
 BOTTLES AND CURRENTS AT SEA. 
 
 Seafaring people often throw a bottle overboard, with a 
 paper stating the time and place at which it is done. In the 
 absence of other information as to Currents, that afforded by 
 these mute little navigators is of great value. They leave no 
 track behind them, it is true, and their routes cannot be ascer- 
 tained ; but knowing where they are cast, and seeing where 
 they are found, some idea may be formed as to their course. 
 Straight lines may at least be drawn, showing the shortest dis- 
 tance from the beginning to the end of their voyage, with the 
 time elapsed. Admiral Beechey has prepared a chart, repre- 
 senting, in this way, the tracks of more than 100 bottles. 
 From this it appears that the waters from every quarter of the 
 Atlantic tend towards the Gulf of Mexico and its stream. Bot- 
 tles cast into the sea midway between the Old and the New 
 
Curiosities of Science. 173 
 
 Worlds, near the coasts of Europe, Africa, and America at the 
 extreme north or farthest south, have been found either in the 
 West Indies, or the British Isles, or within the well-known 
 range of Gulf-Stream waters. 
 
 " THE HOESE LATITUDES" 
 
 are the belts of calms and light airs which border the polar 
 edge of the north-east trade-winds. They are so called from 
 the circumstance that vessels formerly bound from New Eng- 
 land to the West Indies, with a deck-load of horses, were often 
 so delayed in this calm belt of Cancer, that, from the want of 
 water for their animals, they were compelled to throw a portion 
 of them overboard. 
 
 " WHITE WATER" AND LUMINOUS ANIMALS AT SEA. 
 
 Captain Kingman, of the American clipper-ship Shooting 
 Star, in lat. 8 46' S., long. 105 30' E., describes a patch of 
 white water, about twenty-three miles in length, making the 
 whole ocean appear like a plain covered with snow. He tilled 
 a 60-gallon tub with the water, and found it to contain small 
 luminous particles seeming to be alive with worms and in- 
 sects, resembling a grand display of rockets and serpents seen 
 at a great distance in a dark night ; some of the serpents ap- 
 pearing to be six inches in length, and very luminous. On 
 being taken up, they emitted light until brought within a few 
 feet of a lamp, when nothing was visible ; but by aid of a sex- 
 tant's magnifier they could be plainly seen a jelly-like sub- 
 stance, without colour. A specimen two inches long was visi- 
 ble to the naked eye ; it was about the size of a large hair, and 
 tapered at the ends. By bringing one end within about one- 
 fourth of an inch of a lighted lamp, the flame was attracted 
 towards it, and burned with a red light ; the substance crisped 
 in burning, something like hair, or appeared of a red heat 
 before being consumed. In a glass of the water there were 
 several small round substances (say r^th of an inch in diameter) 
 which had the power of expanding and contracting; when ex- 
 panded, the outer rim appeared like a circular saw, the teeth 
 turned inward. 
 
 The scene from the clipper's deck was one of awful gran- 
 deur : the sea having turned to phosphorus, and the heavens 
 being hung in blackness, and the stars going out, seemed to 
 indicate that all nature was preparing for that last grand con- 
 flagration which we are taught to believe will annihilate this 
 material world. 
 
 INVENTION OF THE LOG. 
 
 Long before the introduction of the Log, hour-glasses were 
 
174 Things not generally Known. 
 
 used to tell the distance in sailing. Columbus, Juan de la 
 Cosa, Sebastian Cabot, and Vasco de Grama, were not acquainted 
 with the Log and its mode of application ; and they estimated 
 the ship's speed merely by the eye, while they found the dis- 
 tance they had made by the running-down of the sand in the 
 ampotellas, or hour-glasses. The Log for the measurement of 
 the distance traversed is stated by writers on navigation not to 
 have been invented until the end of the sixteenth or the begin- 
 ning of the seventeenth century (see Encyclopaedia BritanniGoL 
 7th edition, 1842). The precise date is not known ; but it is 
 certain that Pigafetta, the companion of Magellan, speaks, in 
 1521, of the Log as a well-known means of finding the course 
 passed over. Navarete places the use of the log-line in English 
 ships in 1577. 
 
 LIFE OF THE SEA-DEEPS. 
 
 The ocean teems with life, we know. Of the four elements 
 of the old philosophers, fire, earth, air, and water, perhaps 
 the sea most of all abounds with living creatures. The space 
 occupied on the surface of our planet by the different families 
 of animals and their remains is inversely as the size of the indi- 
 vidual ; the smaller the animal, generally speaking, the greater 
 the space occupied by his remains. Take the elephant and his 
 remains, and a microscopic animal and his, and compare them ; 
 the contrast as to space occupied is as striking as that of the 
 coral reef or island with the dimensions of the whale. The 
 graveyard that would hold the corallines, is larger than the 
 graveyard that would hold the elephants. 
 
 DEPTHS OF OCEAN AND AIR UNKNOWN. 
 
 At some few places under the tropics, no bottom has been 
 found with soundings of 26,000 feet, or more than four miles ; 
 whilst in the air, if, according to Wollaston, we may assume 
 that it has a limit from which waves of sound may be rever- 
 berated, the phenomenon of twilight would incline us to assume 
 a height at least nine times as great. The aerial ocean rests 
 partly on the solid earth, whose mountain -chains and elevated 
 plateaus rise like green wooded shoals, and partly on the sea, 
 whose surface forms a moving base, on which rest the lower, 
 denser, and more saturated strata of air. Humboldt's Cosmos, 
 vol. i. 
 
 The old Alexandrian mathematicians, on the testimony of 
 Plutarch, believed the depth of the sea to depend on the height 
 of the mountains. Mr. W. Darling has propounded to the 
 British Association the theory, that as the sea covers three 
 times the area of the land, so it is reasonable to suppose that 
 the depth of the ocean, and that for a large portion, is three 
 
Curiosities of Science. 175 
 
 times as great as the height of the highest mountain. Recent 
 soundings show depths in the sea much greater than any ele- 
 vations on the surface of the earth ; for a line has been veered 
 to the extent of seven miles. Dr. 
 
 GKEATEST ASCERTAINED DEPTH OF THE SEA. 
 
 In the dynamical theory of the tides, the ratio of the effects 
 of the sun and moon depends, not only on the masses, dis- 
 tances, and periodic times of the two luminaries, but also on 
 the Depth of the Sea ; and this, accordingly, may be computed 
 when the other quantities are known. In this manner Pro- 
 fessor Haughton has deduced, from the solar and lunar co- 
 efficients of the diurnal tide, a mean depth of 5'12 miles; a 
 result which accords in a remarkable manner with that inferred 
 from the ratio of the semi-diurnal co-efficients as obtained by 
 Laplace from the Brest observations. Professor Hennessey 
 states, that from what is now known regarding the depth of the 
 ocean, the continents would appear as plateaus elevated above 
 the oceanic depressions to an amount which, although small 
 compared to the earth's radius, would be considerable when 
 compared to its outswelling at the equator and its flattening 
 towards the poles; and the surface thus presented would be 
 the true surface of the earth. 
 
 The greatest depths at which the bottom of the sea has been 
 reached with the plummet are in the North- Atlantic Ocean ; 
 and the places where it has been fathomed (by the United- 
 States deep-sea sounding apparatus) do not show it to be 
 deeper than 25,000 feet = 4 miles, 1293 yards, 1 foot. The 
 deepest place in this ocean is probably between the parallels 
 of 35 and 40 north latitude, and immediately to the south- 
 ward of the Grand Banks of Newfoundland. 
 
 It appeal's that, with one exception, the bottom of the North- At- 
 lantic Ocean, as far as examined, from the depth of about sixty fathoms 
 to that of more than two miles (2000 fathoms), is literally nothing but 
 a mass of microscopic shells. Not one of the animalcules from these 
 shells has been found living in the surface-waters, nor in shallow water 
 along the shore. Hence arises the question, Do they live on the bottom, 
 at the immense depths where the shells are found ; or are they borne by 
 submarine currents from their real habitat ? 
 
 RELATIVE LEVELS OF THE RED SEA AND MEDITERRANEAN. 
 
 The French engineers, at the beginning of the present cen- 
 tury, came to the conclusion that the Red Sea was about thirty 
 feet above the Mediterranean : but the observations of Mr. 
 Robert Stephenson, the English engineer, at Suez ; of M. Ne- 
 gretti, the Austrian, at Tineh, near the ancient Pelusium ; and 
 the levellings of Messrs. Talabat, Bourdaloue, and their assist- 
 
176 Things not generally Known. 
 
 ants between the two seas ; have proved that the low-water 
 mark of ordinary tides at Suez and Tineh is very nearly on the 
 same levels, the difference being that at Suez it is rather more 
 than one inch lower. Leonard Homer; Proceedings of the Royal 
 Society, 1855. 
 
 THE DEPTH OF THE MEDITERRANEAN. 
 
 Soundings made in the Mediterranean suffice to indicate 
 depths equal to the average height of the mountains girding 
 round this great basin ; and, if one particular experiment may 
 be credited, reaching even to 15,000 feet an equivalent to the 
 elevation of the highest Alps. This sounding was made about 
 ninety miles east of Malta. Between Cyprus and Egypt, 6000 
 feet of line had been let down without reaching the bottom. 
 Other deep soundings have been made in other places with 
 similar results. In the lines of sea between Egypt and the 
 Archipelago, it is stated that one sounding made by the Tar- 
 tarus between Alexandria and Rhodes reached bottom at the 
 depth of 9900 feet ; another, between Alexandria and Candia, 
 gave a depth of 300 feet beyond this. These single soundings, 
 indeed, whether of ocean or sea, are always open to the cer- 
 tainty that greater as well as lesser depths must exist, to which 
 no line has ever been sunk ; a case coming under that general 
 law of probabilities so largely applicable in every part of physics. 
 In the Mediterranean especially, which has so many aspects of 
 a sunken basin, there may be abysses of depth here and there 
 which no plummet is ever destined to reach. Edinburgh Ile- 
 
 COLOUR OF THE RED SEA. 
 
 M. Ehrenberg, while navigating the Red Sea, observed that 
 the red colour of its waters was owing to enormous quantities 
 of a new animal, which has received the name of oscillatoria 
 rubescenSj and which seems to be the same with what Haller 
 has described as a purple conferva swimming in water ; yet Dr. 
 Bonar, in his work entitled The Desert of Sinai, records : 
 
 Blue I have called the sea ; yet not strictly so, save in the far dis- 
 tance. It is neither a red nor a Hue sea, but emphatically i>-reen, yes, 
 green, of the most brilliant kind I ever saw. This is produced by the 
 immense tracts of shallow water, with yellow sand beneath, which always 
 gives this green to the sea, even in the absence of verdure on the shore 
 or sea-weeds beneath. The blue of the sky and the yellow of the sands 
 meeting and intermingling in the water, form the green of the sea ; the 
 water being the medium in which the mixing or fusing of the colours 
 takes place. 
 
 WHAT IS SEA-MILK ? 
 
 The phenomena with this name and that of " Squid" are 
 occasioned by the presence of phosphorescent animalcules. They 
 
Curiosities of Science. 177 
 
 are especially produced in the intertropical seas, and they ap- 
 pear to be chiefly abundant in the Gulf of Guinea and in the 
 Arabian Gulf. In the latter, the phenomenon was known to 
 the ancients more than a century before the Christian era, as 
 maybe seen from a curious passage from the geography of Aga- 
 tharcides : " Along this country (the coast of Arabia) the sea 
 has a white aspect like a river : the cause of this phenomenon 
 is a subject of astonishment to us." M. Quatrefages has dis- 
 covered that the Noctilucce which produce this phenomenon do 
 not always give out clear and brilliant sparks, but that under 
 certain circumstances this light is replaced by a steady clear- 
 ness, which gives in these animalcules a white colour. The 
 waters in which they have been observed do not change their 
 place to any sensible degree. 
 
 THE BOTTOM OF THE SEA A BUKIAL-PLACE. 
 
 Among the minute shells which have been fished up from 
 the great telegraphic plateau at the bottom of the sea between 
 Newfoundland and Ireland, the microscope has failed to detect 
 a single particle of sand or gravel ; and the inference is, that 
 there, if any where, the waters of the sea are at rest. There 
 is not motion enough there to abrade these very delicate or- 
 ganisms, nor current enough to sweep them about and mix 
 them up with a grain of the finest sand, nor the smallest par- 
 ticle of gravel from the loose beds of debris that here and there 
 strew the bottom of the sea. The animalcule probably do not 
 live or die there. They would have had no light there ; and, 
 if they lived there, their frail textures would be subjected in 
 their growth to a pressure upon them of a column of water 
 12,000 feet high, equal to the weight of 400 atmospheres. 
 They probably live and sport near the surface, where they 
 can feel the genial influence of both light and heat, and are 
 buried in the lichen caves below after death. 
 
 It is now suggested, that henceforward we should view the 
 surface of the sea as a nursery teeming with nascent organisms, 
 and its depths as the cemetery for families of living creatures 
 that outnumber the sands on the sea-shore for multitude. 
 
 Where there is a nursery, hard by there will be found also a 
 graveyard, such is the condition of the animal world. But it 
 never occurred to us before to consider the surface of the sea 
 as one wide nursery, its every ripple as a cradle, and its bottom 
 one vast burial-place. Lieut. Maury. 
 
 WHY IS THE SEA SALT ? 
 
 It has been replied, In order to preserve it in a state of 
 purity ; which is, however, untenable, mainly from the fact that 
 
 N 
 
178 Things not generally Known. 
 
 organic impurities in a vast body of moving water, whether 
 fresh or salt, become rapidly lost, so as apparently to have 
 called forth a special agency to arrest the total organised matter 
 in its final oscillation between the organic and inorganic worlds. 
 Thus countless hosts of microscopic creatures swarm in most 
 waters, their principal function being, as Professor Owen sur- 
 mises, to feed upon and thus restore to the living chain the 
 almost unorganised matter of various zones. These creatures 
 preying upon one another, and being preyed upon by others in 
 their turn, the circulation of organic matter is kept up. If we 
 do not adopt this view, we must at least look upon the Infuso- 
 ria and Foramiuifera as scavenger agents to prevent an undue 
 accumulation of decaying matter ; and thus the salt condition 
 of the sea is not a necessity. 
 
 Nor is the amount of saline matter in the sea sufficient to 
 arrest decomposition. That the sea is salt to render it of 
 greater density, and by lowering its freezing point to preserve 
 it from congelation to within a shorter distance of the poles, 
 though admissible, scarcely meets the entire solution of the 
 question. The freezing point of sea-water, for instance, is only 
 877 F. lower than that of fresh water ; hence, with the present 
 distribution of land and sea and still less, probably, with that 
 which obtained in former geological epochs no very important 
 effects would have resulted had the ocean been fresh instead of 
 salt. 
 
 Now Professor Chapman, of Toronto, suggests that the salt 
 condition of the sea is mainly intended to regulate evaporation, 
 and to prevent an undue excess of that phenomenon ; saturated 
 solutions evaporating more slowly than weak ones, and these 
 latter more slowly again than pure water. 
 
 Here, then, we have a self-adjusting phenomenon and admir- 
 able contrivance in the balance of forces. If from any tempo- 
 rary cause there be an unusual amount of saline matter in the 
 sea, evaporation goes on the more and more slowly ; and, on 
 the other hand, if this proportion be reduced by the addition of 
 fresh water in undue excess, the evaporating power is the more 
 and more increased thus aiding time, in either instance, to 
 restore the balance. The perfect system of oceanic circulation 
 may be ascribed, in a great degree at least, if not wholly, to 
 the effect produced by the salts of the sea upon the mobility and 
 circulation of its waters. 
 
 Now this is an office which the sea performs in the eco- 
 nomy of the universe by virtue of its saltness, and which it 
 could not perform were its waters altogether fresh. And thus 
 philosophers have a clue placed in their hands which will pro- 
 bably guide to one of the many hidden reasons that are em- 
 braced in the true answer to the question, " Why is the sea salt , ? " 
 
Curiosities of Science. 179 
 
 HOW TO ASCEKTAIN THE SALTNESS OF THE SEA. 
 
 Dry a towel in the sun, weigh it carefully, and note its 
 weight. Then dip it into sea-water, wring it sufficiently to 
 prevent its dripping, and weigh it again ; the increase of the 
 weight being that of the water imbibed by the cloth. It should 
 then be thoroughly dried, and once more weighed ; arid the ex- 
 cess of this weight above the original weight of the cloth shows 
 the quantity of the salt retained by it ; then, by comparing 
 the weight of this salt with that of the sea- water imbibed by 
 the cloth, we shall find what proportion of salt was contained 
 in the water. 
 
 ALL THE SALT IN THE SEA. 
 
 The amount of common Salt in all the oceans is estimated 
 by Schafhautl at 3,051,342 cubic geographical miles. This 
 would be about five times more than the mass of the Alps, and 
 only one- third less than that of the Himalaya. The sulphate of 
 soda equals 633,644*36 cubic miles, or is equal to the mass of 
 the Alps; the chloride of magnesium, 441, 811 '80 cubic miles; 
 the lime salts, 109,339*44 cubic miles. The above supposes the 
 mean depth to be but 300 metres, as estimated by Humboldt. 
 Admitting, with Laplace, that the mean depth is 1000 metres, 
 which is more probable, the mass of marine salt will be more 
 than double the mass of the Himalaya. Silliman's Journal, 
 No. 16. 
 
 Taking the average depth of the ocean at two miles, and 
 its average saltness at 3 5 per cent, it appears that there is salt 
 enough in the sea to cover to the thickness of one mile an area 
 of 7,000,000 of square miles. Admit a transfer of such a quan- 
 tity of matter from an average of half a mile above to one mile 
 below the sea level, and astronomers will show by calculation 
 that it would alter the length of the day. 
 
 These 7,000,000 of cubic miles of crystal salt have not made 
 the sea any fuller. 
 
 PROPERTIES OF SEA-WATER. 
 
 The solid constituents of sea-water amount to about 3| per 
 cent of its weight, or nearly half an ounce to the pound. Its 
 saltness is caused as follows : Rivers which are constantly flow- 
 ing into the ocean contain salts varying from 10 to 50, and 
 even 100, grains per gallon. They are chiefly common salt, 
 sulphate and carbonate of lime, magnesia,* soda, potash, and 
 iron ; and these are found to constitute the distinguishing cha- 
 racteristics of sea- water. The water which evaporates from the 
 
 * It is the chloride of magnesia which gives that damp sticky feeling to the 
 clothes of sailors that are washed or wetted with salt-water. 
 
180 Things not generally Known. 
 
 sea is nearly pure, containing but very minute traces of salts. 
 Falling as rain upon the land, it washes the soil, percolates 
 through the rocky layers, and becomes charged with saline 
 substances, which are borne seaward by the returning currents. 
 The ocean, therefore, is the great depository of every thing that 
 water can dissolve and carry down from the surface of the con- 
 tinents ; and as there is no channel for their escape, they con- 
 sequently accumulate ( Youmans 1 Chemistry). They would con- 
 stantly accumulate, as this very shrewd author remarks, were 
 it not for the shells and insects of the sea and other agents. 
 
 SCENERY AND LIFE OF THE ARCTIC REGIONS. 
 
 The late Dr. Scoresby, from personal observations made in 
 the course of twenty-one voyages to the Arctic Regions, thus 
 describes these striking characteristics : 
 
 The coast scenes of Greenland are generally of an abrupt character, 
 the mountains frequently rising in triangular profile ; so much so, that 
 it is sometimes not possible to effect their ascent. One of the most 
 notable characteristics of the Arctic lands is the deception to which tra- 
 vellers are liable in regard to distances. The occasion of this is the 
 quantity of light reflected from the snow, contrasted with the dark co- 
 lour of the rocks. Several persons of considerable experience have been 
 deceived in this way, imagining, for example, that they were close to 
 the shore when in fact they were more than twenty miles off. The trees 
 of these lands are not more than three inches above ground. 
 
 Many of the icebergs are five miles in extent, and some are to be 
 seen running along the shore measuring as much as thirteen miles. Dr. 
 Scoresby has seen a cliff of ice supported on those floating masses 402 
 feet in 'height. There is no place in the world where animal life is to 
 be found in greater profusion than in Greenland, Spitzbergen, Baffin's 
 Bay, and other portions of the Arctic regions. This is to be accounted 
 for by the abundance and richness of the food supplied by the sea. The 
 number of birds is especially remarkable. On one occasion, no less 
 than a million of little hawks'came in sight of Dr. Scoresby's ship within 
 a single hour. 
 
 The various phenomena of the Greenland sea are very interesting. 
 The different colours of the sea- water olive or bottle-green, reddish- 
 brown, and mustard have, by the aid of the microscope, been found 
 to be owing to animalculse of these various colours : in a single drop of 
 mustard-colonred water have been counted 26,450 animals. Another 
 remarkable characteristic of the Greenland sea-water is its warm tem- 
 perature one, two, and three degrees above the freezing-point even in 
 the cold season. This Dr. Scoresby accounts for by supposing the flow 
 in that direction of warm currents from the south. The polar fields of 
 ice are to be found from eight or nine to thirty or forty feet in thick- 
 ness. By fastening a hook twelve or twenty inches in these masses of 
 ice, a ship could ride out in safety the heaviest gales. 
 
 ICEBERG OF THE POLAR SEAS. 
 
 The ice of this berg, although opaque and vascular, is true 
 glacier ice, having the fracture, lustre, and other external cha- 
 
Curiosities of Science. 181 
 
 racters of a nearly homogeneous growth. The iceberg is true 
 ice, and is always dreaded by ships. Indeed, though modified 
 by climate, and especially by the alternation of day and night, 
 the polar glacier must be regarded as strictly atmospheric in 
 its increments, and not essentially differing from the glacier of 
 the Alps. The general appearance of a berg may be compared 
 to frosted silver ; but when its fractures are very extensive, 
 the exposed faces have a very brilliant lustre. Nothing can be 
 more exquisite than a fresh, cleanly fractured berg surface : it 
 reminds one of the recent cleavage of sulphate of strontian a 
 resemblance more striking from the slightly lazulitic tinge of 
 each. U. 8. Grinnel Expedition in Search of Sir J. Franklin. 
 
 IMMENSITY OF POLAR ICE. 
 
 The quantity of solid matter that is drifted out of the 
 Polar Seas through one opening Davis's Straits alone, and 
 during a part of the year only, covers to the depth of seven 
 feet an area of 3uO,000 square miles, and weighs not less than 
 18,000,000,000 tons. The quantity of water required to float 
 and drive out this solid matter is probably many times greater 
 than this. A quantity of water equal in weight to these two 
 masses has to go in. The basin to receive these inflowing wa- 
 ters, i. e. the unexplored basin about the North Pole, includes 
 an area of 1,500,000 square miles; and as the outflowing ice 
 and water are at the surface, the return current must be sub- 
 marine. 
 
 These two currents, therefore, it may be perceived, keep in 
 motion between the temperate and polar regions of the earth a 
 volume of water, in comparison with which the mighty Missis- 
 sippi in its greatest floods sinks down to a mere rill. Maury. 
 
 OPEN SEA AT THE POLE. 
 
 The following fact is striking : In 1662-3, Mr. Oldenburg, 
 Secretary to the Royal Society, was ordered to register a paper 
 entitled " Several Inquiries concerning Greenland, answered by 
 Mr. Gray, who had visited those parts. " The nineteenth query 
 was, " How near any one hath been known to approach the Pole. 
 Answer. I once met upon the coast of Greenland a Hollander, 
 that swore he had been but half a degree from the Pole, show- 
 ing me his journal, which was also attested by his mate; where 
 they had seen no ice or land, but all water." Boyle mentions 
 a similar account, which he received from an old Greenland 
 master, on April 5, 1765. 
 
 RIVER- WATER ON THE OCEAN. 
 
 Captain Sabine found discoloured water, supposed to be 
 that of the Amazon, 300 miles distant in the ocean from the 
 
Things not generally Known. 
 
 embouchure of that river. It was about 126 feet deep. Its spe- 
 cific gravity was = 1 '0204, and the specific gravity of the sea- 
 water = 1-0262. This appears to be the greatest distance from 
 land at which river-water has been detected on the surface of 
 the ocean. It was estimated to be moving at the rate of three 
 miles an hour, and had been turned aside by an ocean- current. 
 " It is not a little curious to reflect," says Sir Henry de la Beche, 
 " that the agitation and resistance of its particles should be suf- 
 ficient to keep finely comminuted solid matter mechanically 
 suspended, so that it would not be disposed freely to part with 
 it except at its junction with the sea-water over which it flows, 
 and where, from friction, it is sufficiently retarded. " 
 
 THE THAMES AND ITS SALT-WATER BED. 
 
 The Thames below Woolwich, in place of flowing upon a 
 solid bottom, really flows upon the liquid bottom formed by 
 the water of the sea. At the flow of the tide, the fresh water 
 is raised, as it were, in a single mass by the salt water which 
 flows in, and which ascends the bed of the river, while the fresh 
 water continues to flow towards the sea. Mr. Stevenson, in 
 Jameson's Journal. 
 
 FRESH SPRINGS IN THE MIDDLE OF THE OCEAN. 
 
 On the southern coast of the island of Cuba, at a few miles 
 from land, Springs of Fresh Water gush from the bed of the 
 Ocean, probably under the influence of hydrostatic pressure, and 
 rise through the midst of the salt water. They issue forth with 
 such force that boats are cautious in approaching this locality, 
 which has an ill repute on account of the high cross sea thus 
 caused. Trading vessels sometimes visit these springs to take 
 in a supply of fresh water, which is thus obtained in the open 
 sea. The greater the depth from which the water is taken, 
 the fresher it is found to be. 
 
 " THE BLACK WATERS." 
 
 In the upper portion of the basin of the Orinoco and its 
 tributaries, Nature has several times repeated the enigmatical 
 phenomenon of the so-called " Black Waters." The Atabapo, 
 whose banks are adorned with Carolinias and arborescent Me- 
 lastomas, is a river of a coffee-brown colour. In the shade of 
 the palm-groves this colour seems about to pass into ink-black. 
 When placed in transparent vessels, the water appears of a golden 
 yellow. The image of the Southern Constellation is reflected 
 with wonderful clearness in these black streams. When their 
 waters flow gently, they afford to the observer, when taking 
 astronomical observations with reflecting instruments, a most 
 excellent artificial horizon. These waters probably owe their 
 
Curiosities of Science. 183 
 
 peculiar colour to a solution of carburetted hydrogen, to the 
 luxuriance of the tropical vegetation, and to the quantity of 
 plants and herbs on the ground over which they flow. Hurn- 
 ooldt's Aspects of Nature, vol. i. 
 
 GKEAT CATARACT IN INDIA. 
 
 Where the river Shirhawti, between Bombay and Cape Co- 
 morin, falls into the Gulf of Arabia, it is about one-fourth of a 
 mile in width, and in the rainy season some thirty feet in depth. 
 This immense body of water rushes down a rocky slope 300 feet, 
 at an angle of 45, at the bottom of which it makes a perpen- 
 dicular plunge of 850 feet into a black and dismal abyss, with 
 a noise like the loudest thunder. The whole descent is there- 
 fore 1150 feet, or several times that of Niagara; but the volume 
 of water in the latter is somewhat larger than in the former. 
 
 CAUSE OF WAVES. 
 
 The friction of the wind combines with the tide in agitating 
 the surface of the ocean, and, according to the theory of undu- 
 lations, each produces its effect independently of the other. 
 Wind, however, not only raises waves, but causes a transfer of 
 superficial water also. Attraction between the particles of air 
 and water, as well as the pressure of the atmosphere, brings its 
 lower stratum into adhesive contact with the surface of the sea. 
 If the motion of the wind be parallel to the surface, there will 
 still be friction, but the water will be smooth as a mirror ; but 
 if it be inclined, in however small a degree, a ripple will appear. 
 The friction raises a minute wave, whose elevation protects the 
 water beyond it from the wind, which consequently impinges 
 on the surface at a small angle : thus each impulse, combining 
 with the other, produces an undulation which continually ad- 
 vances. Mrs. Somerville's Physical Geography. 
 
 HATE AT WHICH WAVES TRAVEL. 
 
 Professor Bache states, as one of the effects of an earthquake 
 at Simoda, on the island of Niphon, in Japan, that the harbour 
 was first emptied of water, and then came in an enormous wave, 
 which again receded and left the harbour dry. This occurred 
 several times. The United-States self-acting tide-gauge at San 
 Francisco, which records the rise of the tide upon cylinders 
 turned by clocks, showed that at San Francisco, 4800 miles from 
 the scene of the earthquake, the first wave arrived twelve hours 
 and sixteen minutes after it had receded from the harbour of 
 Simoda. It had travelled across the broad bosom of the Pacific 
 Ocean at the rate of six miles and a half a minute, and arrived 
 on the shores of California : the first wave being seven-tenths of 
 
184 Things not generally Known. 
 
 a foot in height, and lasting for about half an hour, followed by 
 seven lesser waves, at intervals of half an hour each. 
 
 The velocity with which a wave travels depends on the depth 
 of the ocean. The latest calculations for the Pacific Ocean give 
 a depth of from 14,000 to 18,000 fathoms. It is remarkable 
 how the estimates of the ocean's depth have grown less. La- 
 place assumed it at ten miles, Whewell at 3*5, while the above 
 estimate brings it down to two miles. 
 
 Mr. Findlay states, that the dynamic force exerted by Sea- 
 Waves is greatest at the crest of the wave before it breaks ; and 
 its power in raising itself is measured by various facts. At 
 Wasburg, in Norway, in 1820, it rose 400 feet; and on the 
 coast of Cornwall, in 1843, 300 feet. The author shows that 
 waves have sometimes raised a column of water equivalent to 
 a pressure of from three to five tons the square foot. He also 
 proves that the velocity of the waves depends on their length, 
 and that waves of from 300 to 400 feet in length from crest to 
 crest travel from twenty to twenty-seven and a half miles an 
 hour. Waves travel great distances, and are often raised by 
 distant hurricanes, having been felt simultaneously at St. He- 
 lena and Ascension, though 600 miles apart ; and it is probable 
 that ground-swells often originate at the Cape of Good Hope, 
 3000 miles distant. Dr. Scoresby found the travelling rate of 
 the Atlantic waves to be 32 67 English statute miles per hour. 
 
 In the winter of 1856, a heavy ground-swell, brought on by 
 five hours' gale, scoured away in fourteen hours 3,900,000 tons 
 of pebbles from the coast near Dover ; but in three days, with- 
 out any shift of wind, upwards of 3,000,000 tons were thrown 
 back again. These figures are to a certain extent conjectural; 
 but the quantities have been derived from careful measurement 
 of the profile of the beach. 
 
 OCEAN-HIGHWAYS I HOW SEA-EOUTES HAVE BEEN 
 SHORTENED. 
 
 When one looks seaward from the shore, and sees a ship 
 disappear in the horizon as she gains an offing on a voyage to 
 India, or the Antipodes perhaps, the common idea is that she 
 is bound over a trackless waste ; and the chances of another 
 ship sailing with the same destination the next day, or the 
 next week, coming up and speaking with her on the "path- 
 less ocean," would to most minds seem slender indeed. Yet 
 the truth is, the winds and the currents are now becoming so 
 well understood, that the navigator, like the backwoodsman 
 in the wilderness, is enabled literally to " blaze his way" across 
 the ocean ; not, indeed, upon trees, as in the wilderness, but 
 upon the wings of the wind. The results of scientific inquiry 
 
Curiosities of Science. 185 
 
 have so taught him how to use these invisible couriers, that 
 they, with the calm belts of the air, serve as sign-boards to 
 indicate to him the turnings and forks and crossings by the 
 way. 
 
 Let a ship sail from New York to California, and the next week let 
 a faster one follow ; they will cross each other's path many times, and 
 are almost sure to see each other by the way, as in the voyage of two 
 fine clipper-ships from New York to California. On the ninth day after 
 the Archer had sailed, the Flying Cloud put to sea. Both ships were 
 limning against time, but without reference to each other. The Archer, 
 with wind and current charts in hand, went blazing her way across the 
 calms of Cancer, and along the new route down through the north-east 
 trades to the equator ; the Cloud followed, crossing the equator upon 
 the trail of Thomas of the Archer. Off Cape Horn she came up with him, 
 spoke him, and handed him the latest New York dates. The Flying 
 Cloud finally ranged ahead, made her adieus, and disappeared among 
 the clouds that lowered upon the western horizon, being destined to 
 reach her port a week or more in advance of her Cape Horn consort. 
 Though sighting no land from the time of their separation until they 
 gained the offing of San Francisco, some six or eight thousand miles 
 off, the tracks of the two vessels were so nearly the same, that being 
 projected upon the chart, they appear almost as one. 
 
 This is the great course of the ocean: it is 15,000 miles in length. 
 Some of the most glorious trials of speed and of prowess that the world 
 ever witnessed among ships that " walk the waters" have taken place 
 over it. Here the modern clipper-ship the noblest work that has ever 
 come from the hands of man has been sent, guided by the lights of 
 science, to contend with the elements, to outstrip steam, and astonish 
 the world. Maury. 
 
 EKROR UPON ERROR. 
 
 The great inducement to Mr. Babbage, some years since, to 
 attempt the construction of a machine by which astronomical 
 tables could be calculated and even printed by mechanical 
 means, and with entire accuracy, was the errors in the re- 
 quisite tables. Nineteen such errors, in point of fact, were dis- 
 covered in an edition of Taylor's Logarithms printed in 1796 ; 
 some of which might have led to the most dangerous results in 
 calculating a ship's place. These nineteen errors (of which one 
 only was an error of the press) were pointed out in the Nauti- 
 cal Almanac for 1832. In one of these errata, the seat of the 
 error was stated to be in cosine of 14 18' 3". Subsequent 
 examination showed that there was an error of one second in 
 this correction, and accordingly, in the Nautical Almanac of 
 the next year a new correction was necessary. But in making 
 the new correction of one second, a new error was committed 
 of ten degrees, making it still necessary, in some future edition 
 of the Nautical Almanac, to insert an erratum in an erratum of 
 the errata in Taylor's Logarithms. Edinburgh Review, vol. 59. 
 
186 Things not generally Known. 
 
 of 
 
 THE LENGTH OF THE DAY AND THE HEAT OF THE EAKTH. 
 
 As we may judge of the uniformity of temperature from the 
 unaltered time of vibration of a pendulum, so we may also 
 learn from the unaltered rotatory velocity of the earth the 
 amount of stability in the mean temperature of our globe. 
 This is the result of one of the most brilliant applications of 
 the knowledge we had long possessed of the movement of the 
 heavens to the thermic condition of our planet. The rotatory 
 velocity of the earth depends on its volume ; and since, by the 
 gradual cooling of the mass by radiation, the axis of rotation 
 would become shorter, the rotatory velocity would necessarily 
 increase, and the length of the day diminish with a decrease of 
 the temperature. From the comparison of the secular inequa- 
 lities in the motions of the moon with the eclipses observed in 
 former ages, it follows that, since the time of Hipparchus, that 
 is, for full 2000 years, the length of the day has certainly not 
 diminished by the hundredth part of a second. The decrease 
 of the mean heat of the globe during a period of 2000 years has 
 not therefore, taking the extremest limits, diminished as much 
 as s^th of a degree of Fahrenheit.* Humboldtfs Cosmos, vol. i. 
 
 NICE MEASUREMENT OF HEAT. 
 
 A delicate thermometer, placed on the ground, will be af- 
 fected by the passage of a single cloud across a clear sky ; and 
 if a succession of clouds pass over, with intervals of clear sky 
 between them, such an instrument has been observed to fluc- 
 tuate accordingly, rising with each passing mass of vapour, and 
 falling again when the radiation becomes unrestrained. 
 
 EXPENDITURE OF HEAT BY THE SUN. 
 
 Sir John Herschel estimates the total Expenditure of Heat 
 by the Sun in a given time, by supposing a cylinder of ice 45 
 miles in diameter to be continually darted into the sun with 
 the velocity of light, and that the water produced by its fusion 
 were continually carried off : the heat now given off con- 
 
 * This fraction rests on the assumption that the dilatation of the suhstances 
 of which the earth is composed is equal to that of glass, that is to say, 1S * 00 for 
 1. Regarding this hypothesis, see Arago, in the Annuaire for 1834, pp. 177-190. 
 
Curiosities of Science. 187 
 
 stantly by radiation would then be wholly expended in its 
 liquefaction, on the one hand, so as to leave no radiant surplus ; 
 while, on the other, the actual temperature at its surface would 
 undergo no diminution. 
 
 The great mystery, however, is to conceive how so enor- 
 mous a conflagration (if such it be) can be kept up. Every 
 discovery in chemical science here leaves us completely at a 
 loss, or rather seems to remove further the prospect of probable 
 explanation. If conjecture might be hazarded, we should look 
 rather to the known possibility of an indefinite generation of 
 heat by friction, or to its excitement by the electric discharge, 
 than to any combustion of ponderable fuel, whether solid or 
 gaseous, for the origin of the solar radiation. Outlines* 
 
 DISTINCTIONS OF HEAT. 
 
 Among the curious laws of modern science are those which 
 regulate the transmission of radiant heat through transparent 
 bodies. The heat of our fires is intercepted and detained by 
 screens of glass, and, being so detained, warms them ; while 
 solar heat passes freely through raid produces no such effect. 
 " The more recent researches of Delaroche," says Sir John Her- 
 schel, "however, have shown that this detention is complete 
 only when the temperature of the source of heat is low ; but 
 that as the temperature gets higher a portion of the heat ra- 
 diated acquires a power of penetrating glass, and that the 
 quantity which does so bears continually a larger and larger pro- 
 portion to the whole, as the heat of the radiant body is more 
 intense. This discovery is very important, as it establishes a 
 community of nature between solar and terrestrial heat ; while 
 at the same time it leads us to regard the actual temperature of 
 the sun as far exceeding that of any earthly flame." 
 
 LATENT HEAT. 
 
 This extraordinary principle exists in all bodies, and may 
 be pressed out of them. The blacksmith hammers a nail until 
 it becomes red hot, and from it he lights the match with which 
 he kindles the fire of his forge. The iron has by this process 
 become more dense, and percussion will not again produce in- 
 candescence until the bar has been exposed in fire to a red heat, 
 when it absorbs heat, the particles are restored to their former 
 state, and we can again by hammering develop both heat and 
 light. R. Hunt, F.R.S. 
 
 * Electricity, traversing excessively rarefied air or vapours, gives out light, 
 and doubtless also heat. May not a continual current of electric matter be con- 
 stantly circulating in the sun's immediate neighbourhood, or traversing the 
 planetary spaces, and exerting in the upper regions of its atmosphere those 
 phenomena of which, on however diminutive a scale, we have yet an unequi- 
 vocal manifestation in our Aurora Borealia? 
 
188 Things not generally Known. 
 
 HEAT AND EVAPOKATION. 
 
 In a communication made to the French Academy, M. 
 Daubree calculates that the Evaporation of the Water on the 
 surface of the globe employs a quantity of heat about equal to 
 one-third of what is received from the sun ; or, in other words, 
 equal to the melting of a bed of ice nearly thirty-five feet in 
 thickness if spread over the globe. 
 
 HEAT AND MECHANICAL POWEK. 
 
 It has been found that Heat and Mechanical Power are 
 mutually convertible ; and that the relation between them is 
 definite, 772 foot-pounds of motive power being equivalent to 
 a unit of heat, that is, to the amount of heat requisite to raise a 
 pound of water through one degree of Fahrenheit. 
 
 HEAT OF MINES. 
 
 One cause of the great Heat of many of our deep Mines, 
 which appears to have been entirely lost sight of, is the chemi- 
 cal action going on upon large masses of pyritic matter in their 
 vicinity. The heat, which is so oppressive in the United Mines 
 in Cornwall that the miners work nearly naked, and bathe in 
 water at 80 to cool themselves, is without doubt due to the 
 decomposition of immense quantities of the sulphurets of iron 
 and copper known to be in this condition at a short distance 
 from these mineral works. R. Hunt, F.R.S. 
 
 VIBRATION OF HEATED METALS. 
 
 Mr. Arthur Trevelyan discovered accidentally that a bar of 
 iron, when heated and placed with one end on a solid block 
 of lead, in cooling vibrates considerably, and produces sounds 
 similar to those of an ^Eolian harp. The same effect is pro- 
 duced by bars of copper, zinc, brass, and bell-metal, when 
 heated and placed on blocks of lead, tin, or pewter. The bars 
 were four inches long, one inch and a half wide, and three- 
 eighths of an inch thick. 
 
 The conditions essential to these experiments are, That two 
 different metals must be employed the one soft and possessed 
 of moderate conducting powers, viz. lead or tin, the other hard ; 
 and it matters not whether soft metal be employed for the bar 
 or block, provided the soft metal be cold and the hard metal 
 heated. 
 
 That the surface of the block shall be uneven, for when ren- 
 dered quite smooth the vibration does not take place ; but the 
 bar cannot be too smooth. 
 
 That no matter be interposed, else it will prevent vibration, 
 
Curiosities of Science. 189 
 
 with the exception of a burnish of gold leaf, the thickness of 
 which cannot amount to the two-hundred-thousandth part of 
 an inch. Transactions of the Royal Society of Edinburgh. 
 
 EXPANSION OF SPIRITS. 
 
 Spirits expand and become lighter by means of heat in a 
 greater proportion than water, wherefore they are heaviest in 
 winter. A cubic inch of brandy has been found by many ex- 
 periments to weigh ten grains more in winter than in summer, 
 the difference being between four drams thirty-two grains and 
 four drams forty-two grains. Liquor-merchants take advan- 
 tage of this circumstance, and make their purchases in winter 
 rather than in summer, because they get in reality rather a 
 larger quantity in the same bulk, buying by measure. Notes in 
 Various Sciences. 
 
 HEAT PASSING THROUGH GLASS. 
 
 The following experiment is by Mr. Fox Talbot: Heat a 
 poker bright-red hot, and having opened a window, apply the 
 poker quickly very near to the outside of a pane, and the hand 
 to the inside ; a strong heat will be felt at the instant, which 
 will cease as soon as the poker is withdrawn, and may be again 
 renewed and made to cease as quickly as before. Now it is 
 well known, that if a piece of glass is so much warmed as to 
 convey the impression of heat to the hand, it will retain some 
 part of that heat for a minute or more ; but in this experiment 
 the heat will vanish in a moment : it will not, therefore, be the 
 heated pane of glass that we shall feel, but heat which has come 
 through the glass in a free or radiant state. 
 
 HEAT FROM GAS-LIGHTING. 
 
 In the winter of 1835, Mr. W. H. White ascertained the tem- 
 perature in the City to be 3 higher than three miles south of 
 London Bridge; and after the gas had been lighted in the City 
 four or five hours the temperature increased full 3, thus mak- 
 ing 6 difference in the three miles. 
 
 HEAT BY FRICTION. 
 
 Friction as a source of Heat is well known : we rub our 
 hands to warm them, and we grease the axles of carriage- wheels 
 to prevent their setting fire to the wood. Count Rumford 
 has established the extraordinary fact, that an unlimited sup- 
 ply of heat may be derived from friction by the same materials : 
 he made great quantities of water boil by causing a blunt borer 
 to rub against a mass of metal immersed in the water. Savages 
 light their fires by rubbing two pieces of wood : the modus opcr- 
 
190 Things not generally Known. 
 
 andi, as practised by the Kaffirs of South Africa, is thus de- 
 scribed by Captain Drayton : 
 
 Two dry sticks, one being of hard and the other of soft wood, were 
 the materials used. The soft stick was laid on the ground, and held 
 firmly down by one Kaffir, whilst another employed himself in scooping 
 out a little hole in the centre of it with the point of his assagy : into this 
 little hollow the end of the hard wood was placed, and held vertically. 
 These two men sat face to face, one taking the vertical stick between 
 the palms of his hands, and making it twist about very quickly, while 
 the other Kaffir held the lower stick firmly in its place ; the friction 
 caused by the end of one piece of wood revolving upon the other soon 
 made the two pieces smoke. When the Kaffir who twisted became tired, 
 the respective duties were exchanged. These operations having conti- 
 nued about a couple of minutes, sparks began to appear, and when they 
 became numerous, were gathered into some dry grass, which was then 
 swung round at arm's length until a blaze was established ; and a roar- 
 ing fire was gladdening the hearts of the Kaffirs with the anticipation of 
 a glorious feast in about ten minutes from the time that the operation 
 was first commenced. 
 
 HEAT BY FEICTION FEOM ICE. 
 
 When Sir Humphry Davy was studying medicine at Pen- 
 zance, one of his constant associates was Mr. Tom Harvey, a 
 druggist in the above town. They constantly experimented to- 
 gether ; and one severe winter's day, after a discussion on the 
 nature of heat, the young philosophers were induced to go to 
 Larigan river, where Davy succeeded in developing heat by rub- 
 bing two pieces of ice together so as to melt each other ;* an ex- 
 periment which he repeated with much eclat many years after, 
 in the zenith of his celebrity, at the Royal Institution. The 
 pieces of ice for this experiment are fastened to the ends of two 
 sticks, and rubbed together in air below the temperature of 
 32 : this Davy readily accomplished on the day of severe cold 
 at the Larigan river ; but when the experiment was repeated at 
 the Royal Institution, it was in the vacuum of an air-pump, 
 when the temperature of the apparatus and of the surrounding 
 air was below 32. It was remarked, that when the surface 
 of the rubbing pieces was rough, only half as much heat was 
 evolved as when it was smooth. When the pressure of the rub- 
 bing piece was increased four times, the proportion of heat 
 evolved was increased sevenfold. 
 
 WAEMING WITH ICE. 
 
 In common language, any thing is understood to be cooled 
 or warmed when the temperature thereof is made higher or 
 lower, whatever may have been the temperature when the 
 change was commenced. Thus it is said that melted iron is 
 
 * Could we by mechanical pressure force water into a solid state, an immense 
 nantity of he<it would be set free. 
 
Curiosities of Science. 191 
 
 cooled down to a sub-red heat, or mercury is cooled from the 
 freezing point to zero, or far below. By the same rule, solid 
 mercury, say 50 below zero, may, in any climate or tempera- 
 ture of the atmosphere, be immediately warmed and melted by 
 being imbedded in a cake of ice. Scientific American. 
 
 REPULSION BY HEAT. 
 
 If water is poured upon an iron sieve, the wires of which 
 are made red-hot, it will not run through ; but on cooling, it 
 will pass through rapidly. M. Boutigny, pursuing this curious 
 inquiry, has proved that the moisture upon the skin is sufficient 
 to protect it from disorganisation if the arm is plunged into 
 baths of melted metal. The resistance of the surfaces is so great 
 that little elevation of temperature is experienced. Professor 
 Pliicker has stated, that by washing the arm with ether previ- 
 ously to plunging it into melted metal, the sensation produced 
 while in the molten mass is that of freezing coldness. R. 
 Hunt, F.R.S. 
 
 PKOTECTION FKOM INTENSE HEAT. 
 
 The singular power which the body possesses of resisting 
 great heats, and of breathing air of high temperatures, has at 
 various times excited popular wonder. In the last century 
 some curious experiments were made on this subject. Sir 
 Joseph Banks, Dr. Solauder, and Sir Charles Blagden, entered 
 a room in which the air had a temperature of 198 Fahr., and 
 remained ten minutes. Subsequently they entered the room 
 separately, when Dr. Solander found the heat 210, and Sir 
 Joseph 211, whilst their bodies preserved their natural degree 
 of heat. Whenever they breathed upon a thermometer, it sank 
 several degrees ; every inspiration gave coolness to their nostrils, 
 and their breath cooled their fingers when it reached them. Sir 
 Charles Blagden entered an apartment when the heat was 1 
 or 2 above 260, and remained eight minutes, mostly on the 
 coolest spot, where the heat was above 240. Though very hot, 
 Sir Charles felt no pain : during seven minutes his breathing 
 was good ; but he then felt an oppression in his lungs, and his 
 pulse was 144, double its ordinary quickness. To prove the 
 heat of the room, eggs and a beefsteak were placed upon a tin 
 frame near the thermometer, when in twenty minutes the eggs 
 were roasted hard, and in forty-seven minutes the steak was 
 dressed dry ; and when the air was put in motion by a pair of 
 bellows upon another steak, part of it was well done in thirteen 
 minutes. It is remarkable, that in these experiments the same 
 person who experienced no inconvenience from air heated to 
 211, could just bear rectified spirits of wine at ISO 3 , cooling oil 
 at 129", cooling water at 123, and cooling quicksilver at 117. 
 
192 Things not generally Known. 
 
 Sir Francis Chantrey, the sculptor, however, exposed himself 
 to a temperature still higher than any yet mentioned, as de- 
 scribed by Sir David Brewster : 
 
 The furnace which he employs for drying his moulds is about fourteen 
 feet long, twelve feet high, and twelve feet broad. When it is raised to 
 its highest temperature, with the doors closed, the thermometer stands 
 at 350, and the iron floor is red-hot. The workmen often enter it at 
 a temperature of 340, walking over the iron floor with wooden clogs, 
 which are of course charred on the surface. On one occasion, Mr. Chan- 
 trey, accompanied by five or six of his friends, entered the furnace ; and 
 after remaining two minutes they brought out a thermometer which 
 stood at 320. Some of the party experienced sharp pains in the tips 
 of their ears and in the septum of the nose, while others felt a pain in 
 their eyes. Natural Magic, 1833. 
 
 In some cases the clothing worn by the experimenters con- 
 ducts away the heat. Thus, in 1828, a Spaniard entered a heated 
 oven, at the New Tivoli, near Paris ;. he sang a song while a 
 fowl was roasted by his side, he then ate the fowl and drank a 
 bottle of wine, and on coming out his pulse beat 176, and the 
 thermometer was at 110 Reaumur. He then stretched him- 
 self upon a plank in the oven surrounded by lighted candles, 
 when the mouth of the oven was closed ; he remained there 
 five minutes, and on being taken out, all the candles were ex- 
 tinguished and melted, and the Spaniard's pulse beat 200. 
 Now much of the surprise ceases when it is added that he 
 wore wide woollen pantaloons, a loose mantle of wool, and a 
 great quilted cap ; the several materials of this clothing being 
 bad conductors of heat. 
 
 In 1829 M. Chabert, the "Fire-King," exhibited similar 
 feats at the Argyll Rooms in Regent Street. He first swal- 
 lowed forty grains of phosphorus, then two spoonfuls of oil at 
 330, and next held his head over the fumes of sulphuric acid. 
 He had previously provided himself with an antidote for the 
 poison of the phosphorus. Dressed in a loose woollen coat, he 
 then entered a heated oven, and in five minutes cooked two 
 steaks ; he then came out of the oven, when the thermometer 
 stood at 380. Upon another occasion, at White Conduit House, 
 some of his feats were detected. 
 
 The scientific secret is as follows : Muscular tissue is an 
 extremely bad conductor ; and to this in a great measure the 
 constancy of the temperature of the human body in various 
 zones is to be attributed. To this fact also Sir Charles Blag- 
 den and Chantrey owed their safety in exposing their bodies to 
 a high temperature ; from the almost impervious character of 
 the tissues of the body, the irritation produced was confined to 
 the surface. 
 
Curiosities of Science. 193 
 
 an* (Elertricita* 
 
 ill 
 
 MAGNETIC HYPOTHESES. 
 
 As an instance of the obstacles which erroneous hypotheses 
 throw in the way of scientific discovery, Professor Faraday ad- 
 duces the unsuccessful attempts that had been made in Eng- 
 land to educe Magnetism from Electricity until Oersted showed 
 the simple way. Faraday relates, that when he came to the 
 Royal Institution as an assistant in the laboratory, he saw 
 Davy, Wollaston, and Young trying, by every way that sug- 
 gested itself to them, to produce magnetic effects from an elec- 
 tric current ; but having their minds diverted from the true 
 course by their existing hypotheses, it did not occur to them 
 to try the effect of holding a wire through which an electric 
 current was passing over a suspended magnetic needle. Had 
 they done so, as Oersted afterwards did, the immediate de- 
 flection of the needle would have proved the magnetic property 
 of an electric current. Faraday has shown that the magnetism 
 of a steel bar is caused by the accumulated action of all the 
 particles of which it is composed : this he proves by first mag- 
 netising a small steel bar, and then breaking it successively 
 into smaller and smaller pieces, each one of which possesses a 
 separate pole ; and the same operation may be continued until 
 the particles become so small as not to be distinguishable with- 
 out a microscope. 
 
 We quote the above from a late Number of the Philosophical 
 Magazine, wherein also we find the following noble tribute to 
 the genius and public and private worth of Faraday : 
 
 The public never can know and appreciate the national value of such 
 a man as Faraday. He does not work to please the public, nor to win 
 its guineas ; and the said public, if asked its opinion as to the practical 
 value of his researches, can see no possible practical issue there. The 
 public does not know that we need prophets more than mechanics in 
 science, inspired men, who, by patient self-denial and the exercise of 
 the high intellectual gifts of the Creator, bring us intelligence of His 
 doings in Nature. To them their pursuits are good in themselves. Their 
 chief reward is the delight of being admitted into communion with Na- 
 ture, the pleasure of tracing out and proclaiming her laws, wholly for- 
 getful whether those laws will ever augment our banker's account or 
 improve our knowledge of cookery. Such men, though not honoured by 
 the title of '" practical," are they which make practical men possible. They 
 bring us the tamed forces of Nature, and leave it to others to contrive 
 the machinery to which they may be yoked. If we are rightly informed, 
 it was Faradaic electricity which shot the glad tidings of the fall of Se- 
 bastopol from Balaklava to Varna. Had this man converted his talent 
 
 
 
194 Things not generally Known. 
 
 to commercial purposes, as so many do, we should not like to set a limit 
 to his professional income. The quality of his services cannot be ex- 
 pressed by pounds ; but that brave body, which for forty years has been 
 the instrument of that great soul, is a fit object for a nation's care, as 
 the achievements of the man are, or will one day be, the object of a 
 nation's pride and gratitude. 
 
 THE CHINESE AND THE MAGNETIC NEEDLE. 
 
 More than a thousand years before our era, a people living 
 in the extremest eastern portions of Asia had magnetic carri- 
 ages, on which the movable arm of the figure of a man con- 
 tinually pointed to the south, as a guide by which to find the 
 way across the boundless grass-plains of Tartary ; nay, even in 
 the third century of our era, therefore at least 700 years be- 
 fore the use of the mariner's compass in European seas, Chinese 
 vessels navigated the Indian Ocean under the direction of 
 Magnetic Needles pointing to the south. 
 
 Now the Western nations, the Greeks and the Romans, knew that 
 magnetism could be communicated to iron, and that that metal would 
 retain it for a length of time. The great discovery of the terrestrial 
 directive force depended, therefore, alone on this that no one in the 
 West had happened to observe an elongated fragment of magnetic iron- 
 stone, or a magnetic iron rod, floating by the aid of a piece of wood in 
 water, or suspended in the air by a thread, in such a position as to ad- 
 mit of free motion. Humboldts Cosmos, vol. i. 
 
 KIECHEE'S " MAGNETISM." 
 
 More than two centuries since, Athanasius Kircher pub- 
 lished his strange book on Magnetism, in which he anticipated 
 the supposed virtue of magnetic traction in the curative art, 
 and advocated the magnetism of the sun and moon, of the 
 divining-rod, and showed his firm belief in animal magnetism. 
 "In speaking of the vegetable world," says Mr. Hunt, "and 
 the remarkable processes by which the leaf, the flower, and the 
 fruit are produced, this sage brings forward the fact of the 
 diamagnetic (repelled by the magnet) character of the plant 
 which was in 1852 rediscovered; and he refers the motions of 
 the sunflower, the closing of the convolvulus, and the direc- 
 tions of the spiral formed by the twining plants, to this parti- 
 cular influence."* Nor were Kircher's anticipations random 
 guesses, but the result of deductions from experiment and ob- 
 servation ; and the universality of magnetism is now almost 
 recognised by philosophers. 
 
 MINUTE MEASUREMENT OF TIME. 
 
 By observing the magnet in the highly-convenient and deli- 
 cate manner introduced by Gauss and Weber, which consists 
 
 * See Mr. Hunt's popular work, The Poetry of Science; or, Studies of Physical 
 Phenomena of Nature. Third editiou, revised and enlarged. Bohn, 1854. 
 
Curiosities of Science. 195 
 
 m attaching a mirror to the magnet and determining the con- 
 stant factor necessary to convert the differences of oscillation 
 into differences of time, Professor Helmholtz has been able, 
 with comparatively simple apparatus, to make accurate deter- 
 minations up to the looooth part of a second. 
 
 POWER OF A MAGNET. 
 
 The Power of a Magnet is estimated by the weight its poles 
 are able to carry. Each pole singly is able to support a smaller 
 weight than when they both act together by means of a keeper, 
 for which reason horse-shoe magnets are superior to bar mag- 
 nets of similar dimensions and character. It has further been 
 ascertained that small magnets have a much greater relative 
 force than large ones. 
 
 When magnetism is excited in a piece of steel in the ordi- 
 nary mode, by friction with a magnet, it would seem that its 
 inductive power is able to overcome the coercive power of the 
 steel only to a certain depth below the surface ; hence we see 
 why small pieces of steel, especially if not very hard, are able 
 to carry greater relative weights than large magnets. Sir Isaac 
 Newton wore in a ring a magnet weighing only 3 grains, which 
 would lift 760 grains, i. e. 250 times its own weight. 
 
 Bar-magnets are seldom found capable of carrying more 
 than their own weight; but horse-shoe magnets of similar steel 
 will bear considerably more. Small ones of from half an ounce 
 to 1 ounce in weight will carry from 30 to 40 times their own 
 weight ; while such as weigh from 1 to 2 Ibs. will rarely carry 
 more than from 10 to 15 times their weight. The writer found 
 a 1 Ib. horse-shoe magnet that he impregnated by means of the 
 feeder able to bear 26 times its own weight ; and Fischer, hav- 
 ing adopted the like mode of magnetising the steel, which he 
 also carefully heated, has made magnets of from 1 to 3 Ibs. 
 weight that would carry 30 times, and others of from 4 to 6 Ibs. 
 weight that would carry 20 times, their own weight. Professor 
 PescM. 
 
 HOW ARTIFICIAL MAGNETS ARE MADE. 
 
 In 1750, Mr. Canton, F.R.S., "one of the most successful 
 experimenters in the golden age of electricity,"* communicated 
 to the Royal Society his " Method of making Artificial Mag- 
 nets without the use of natural ones." This he effected by 
 using a poker and tongs to communicate magnetism to steel 
 bars. He derived his first hint from observing them one even- 
 ing, as he was sitting by the fire, to be nearly in the same di- 
 rection with the earth as the dipping needle. He thence con- 
 cluded that they must, from their position and the frequent 
 
 * Canton was the first who in England verified Dr. Franklin's idea of the 
 similarity of lightning and the electric fluid, July 1752. 
 
196 Things not generally Known. 
 
 blows they receive, have acquired some magnetic virtue, which 
 on trial he found to be the case ; and therefore he employed 
 them to impregnate his bars, instead of having recourse to the 
 natural loadstone. Upon the reading of the above paper, Can- 
 ton exhibited to the Royal Society his experiments, for which 
 the Copley Medal was awarded to him in 1751. 
 
 Canton had, as early as 1747, turned his attention, with 
 complete success, to the production of powerful artificial mag- 
 nets, principally in consequence of the expense of procuring 
 those made by Dr. Gowan Knight, who kept his process secret. 
 Canton for several years abstained from communicating his 
 method even to his most intimate friends, lest it might be 
 injurious to Dr. Knight, who procured considerable pecuniary 
 advantages by touching needles for the mariner's compass. 
 
 At length Dr. Knight's method of making artificial magnets 
 was communicated to the world by Mr. Wilson, in a paper 
 published in the 69th volume of the Philosophical Transactions. 
 He provided himself with a large quantity of clean iron-filings, 
 which he put into a capacious tub about half full of clear 
 water ; he then agitated the tub to and fro for several hours, 
 until the filings were reduced by attrition to an almost im- 
 palpable powder. This powder was then dried, and formed 
 into paste by admixture with linseed-oil. The paste was then 
 moulded into convenient shapes, which were exposed to a mo- 
 derate heat until they had attained a sunicient degree of hard- 
 ness. 
 
 After allowing them to remain for some time in this state, Dr, 
 Knight gave them their magnetic virtue in any direction he pleased, 
 by placing them between* the extreme ends of his large magazine of 
 artificial magnets for a second or more, as he saw occasion. By this 
 method the virtue they acquired was such, that when any one of these 
 pieces was held between two of his best ten-guinea bars, with its poles 
 purposely inverted, it immediately of itself turned about to recover its 
 natural direction, which the force of those very powerful bars was not 
 sufficient to counteract. 
 
 Dr. Knight's powerful battery of magnets above mentioned 
 is in the possession of the Royal Society, having been presented 
 by Dr. John FothergiU in 1776. 
 
 POWER OF THE SUN'S BAYS IN INCREASING THE STRENGTH 
 OF MAGNETS. 
 
 Professor Barlocci found that an armed natural loadstone, 
 which would carry 1 Roman pounds, had its power nearly 
 doubled by twenty-four hours' exposure to the strong light of 
 the sun. M. Zantedeschi found that an artificial horse-shoe 
 loadstone, which carried 13 oz., carried 3J more by three days' 
 exposure, and at last arrived to 31 oz. by continuing it in the 
 sun's light. He found that while the strength increased in 
 
Curiosities of Science. 197 
 
 oxidated magnets, it diminished in those which were not oxi- 
 dated, the diminution becoming insensible when the loadstone 
 was highly polished. He now concentrated the solar rays upon 
 the loadstone by means of a lens ; and he found that, both in 
 oxidated and polished magnets, they acquire strength when 
 their north pole is exposed to the sun's rays, and lose strength 
 when the south pole is exposed. /Sir David Bi 
 
 COLOUR OF A BODY AND ITS MAGNETIC PROPERTIES. 
 
 Solar rays bleach dead vegetable matter with rapidity, while 
 in living parts of plants their action is frequently to strengthen 
 the colour. Their power is perhaps best seen on the sides of 
 peaches, apples, &c., which, exposed to a midsummer's sun, 
 become highly coloured. In the open winter of 1850, Mr. Adie, 
 of Liverpool, found in a wallflower plant proof of a like effect : 
 in the dark months there was a slow succession of one or two 
 flowers, of uniform pale yellow hue ; in March streaks of a 
 darker colour appeared on the flowers, and continued to slowly 
 increase till in April they were variegated brown and yellow, 
 of rich strong colours. On the supposition that these changes 
 are referable to magnetic properties, may hereafter be explained 
 Mrs. Somerville's experiments on steel needles exposed to the 
 sun's rays under envelopes of silk of various colours ; the mag- 
 netisation of steel needles has failed in the coloured rays of the 
 spectrum, but Mr. Adie considers that under dyed silk the ef- 
 fect will hinge on the chemical change wrought in the silk and 
 its dye by the solar rays. 
 
 THE ONION AND MAGNETISM. 
 
 A popular notion has long been current, more especially on 
 the shores -of the Mediterranean, that if a magnetic rod be 
 rubbed with an onion, or brought in contact with the emana- 
 tions of the plant, the directive force will be diminished, while 
 a compass thus treated will mislead the steersman. It is diffi- 
 cult to conceive what could have given rise to so singular a 
 popular error.* Humboldt's Cosmos, vol. v. 
 
 DECLINATION OF THE NEEDLE THE EARTH A MAGNET. 
 
 The Inclination or Dip of the Needle was first recorded by 
 Robert Norman, in a scarce book published in 1576 entitled The 
 New Attractive; containing a short Discourse of the Magnet or 
 Loadstone, &c. 
 
 Columbus has not only the merit of being the first to dis- 
 cover a line without magnetic variation, but also of having first 
 
 * This is mentioned in Prodi Diadochi Paraphrasis Ptolem., 1635. (Delambre, 
 Hist, de I' Astronomie ancienne.) 
 
198 Things not generally Known. 
 
 excited a ta^te for the study of terrestrial magnetism in Europe, 
 by means of his observations on the progressive increase of 
 western declination in receding from that line. 
 
 The first chart showing the variation of the compass,* or 
 the declination of the needle, based on the idea of employing 
 curves drawn through points of equal declination, is due to 
 Halley, who is justly entitled the father and founder of terres- 
 trial magnetism. And it is curious to find that in No. 195 of 
 the Philosophical Transactions, in 1683, Halley had previously 
 expressed his belief that he has put it past doubt that the 
 globe of the earth is one great magnet, having four magnetical 
 poles or points of attraction, near each pole of the equator two; 
 and that in those parts of the world which lie near adjacent to 
 any one of those magnetical poles, the needle is chiefly go- 
 verned thereby, the nearest pole being always predominant 
 over the more remote. 
 
 " To Halley" (says Sir John Herschel) " we owe the first ap- 
 preciation of the real complexity of the subject of magnetism. 
 It is wonderful indeed, and a striking proof of the penetration 
 and sagacity of this extraordinary man, that with his means of 
 information he should have been able to draw such conclusions, 
 and to take so large and comprehensive a view of the subject 
 as he appears to have done. " 
 
 And, in our time, " the earth is a great magnet," says 
 Faraday : "its power, according to Gauss, being equal to that 
 which would be conferred if every cubic yard of it contained 
 six one-pound magnets ; the sum of the force is therefore equal 
 to 8,464,000,000,000,000,000,000 such magnets." 
 
 THE AURORA BOREALIS. 
 
 Halley, upon his return from his voyage to verify his theory 
 of the variation of the compass, in 1700, hazarded the conjec- 
 ture that the Aurora Barealis is a magnetic phenomenon. And 
 Faraday's brilliant discovery of the evolution of light by mag- 
 netism has raised Halley's hypothesis, enounced in 1714, to 
 the rank of an experimental certainty. 
 
 EFFECT OF LIGHT ON THE MAGNET. 
 
 In 1854. Sir John Ross stated to the British Association, in 
 proof of the effect of every description of light on the magnet, 
 that during h ; s last voyage in the Felix, when frozen in about 
 one hundred miles north of the magnetic pole, he concentrated 
 
 * The fivst Vnr'aHon-Oomnnss was constructed, before 1525, by nn ingenious 
 apothecary of Seville. Pelisse Guillen. So earnest were the endeavours to learn 
 more exactly the. direction of tlie curves of magnetic declination, that in 1585 
 Juan Jayine sailed wirli Prune! sco Gali from Manilla to Acsipnlco, for the sole 
 purpose of trying in the Pacific a declination instrument which lie had invented. 
 Humboldt. 
 
Curiosities of Science. 199 
 
 the rays of the full moon on the magnetic needle, when he found 
 it was nve degrees attracted by it. 
 
 MAGNETO-ELECTRICITY. 
 
 In 1820, the Copley Medal was adjudicated to M. Oersted 
 of Copenhagen, "when," says Dr. Whewell, "the philosopher 
 announced that the conducting-wire of a voltaic circuit acts 
 upon a magnetic needle ; and thus recalled into activity that 
 endeavour to connect magnetism with electricity which, though 
 apparently on many accounts so hopeful, had hitherto been at- 
 tended with no success. Oersted found that the needle has a 
 tendency to place itself at right anyles to the wire ; a kind of 
 action altogether different from any which had been suspected." 
 
 ELECTRO-MAGNETS OF THE HORSE-SHOE FORM 
 
 were discovered by Sturgeon in 1825. Of two Magnets made by 
 a process devised by M. Elias, and manufactured by M. Loge- 
 meur at Haerlem, one, a single horse-shoe magnet weighing 
 about 1 lb., lifts 28 \ Ibs. ; the other, a triple horse-shoe magnet 
 of about 10 Ibs. weight, is capable of lifdng about 150 Ibs. Si- 
 milar magnets are made by the same person capable of sup- 
 porting 5 cwt. In the process of making them, a helix of 
 copper and a galvanic battery are used. The smaller magnet 
 has twice the power expressed by Haecker's formula for the 
 best artificial steel magnet. 
 
 Subsequently Henry and Ten Eyk, in America, constructed 
 some electro-magnets on a large scale. One horse-shoe magnet 
 made by them, weighing 60 Ibs., would support more than 
 2000 Ibs. 
 
 In September 1858, there were constructed for the Atlan- 
 tic-telegraph cable at Valentia two permanent magnets, from 
 which the electric induction is obtained : each is composed of 
 30 horse-shoe magnets, 2 feet long and from 4 to 5 inches 
 broad ; the induction coils attached to these each contain six 
 miles of wire, and a shock from them, if passed through the 
 human body, would be sufficient to destroy life. 
 
 ROTATION-MAGNETISM. 
 
 The unexpected discovery of Rotation- Magnetism by Arago, 
 in 1825, has shown practically that every kind of matter is sus- 
 ceptible of magnetism ; and the recent investigations of Fara- 
 day on diamagnetic substances have, under special conditions 
 of meridian or equatorial direction, and of solid, fluid, or gaseous 
 inactive conditions of the bodies, confirmed this important re- 
 sult. 
 
200 Things not generally Known. 
 
 INFLUENCE OF PENDULUMS ON EACH OTHEE. 
 
 About a century since it became known, that when two 
 clocks are in action upon the same shelf, they will disturb each 
 other : that the pendulum of the one will stop that of the other ; 
 and that the pendulum that was stopped will after a while re- 
 sume its vibrations, and in its turn stop that of the other clock. 
 When two clocks are placed near one another in cases .very 
 slightly fixed, or when they stand on the boards of a floor, they 
 will affect a little each other's pendulum. Mr. ElHcote observed 
 that two clocks resting against the same rail, which agreed to a 
 second for several days, varied one minute thirty-six seconds in 
 twenty-four hours when separated. The slower, having a longer 
 pendulum, set the other in motion in 16 J minutes, and stopped 
 itself in 36 minutes. 
 
 WEIGHT OF THE EARTH ASCERTAINED BY THE PENDULUM. 
 
 By a series of comparisons with Pendulums placed at the 
 surface and the interior of the Earth, the Astronomer- Royal has 
 ascertained the variation of gravity in descending to the bottom 
 of a deep mine, as the Harton coal-pit, near South Shields. By 
 calculations from these experiments, he has found the mean 
 density of the earth to be 6-566, the specific gravity of water 
 being represented by unity. In other words, it has been ascer- 
 tained by these experiments that if the earth's mass possessed 
 every where its average density, it would weigh, bulk for bulk, 
 6*566 times as much as water. It is curious to note the dif- 
 ferent values of the earth's mean density which have been 
 obtained by different methods. The Schehallien experiment 
 indicated a mean density equal to about 4 ; the Cavendish 
 apparatus, repeated by Baily and Reich, about 5^ ; and Pro- 
 fessor Airy's pendulum experiment furnishes a value amounting 
 to about 65. 
 
 The immediate result of the computations of the Astro- 
 nomer-Royal is : supposing a clock adjusted to go true time at 
 the top of the mine, it would gain 2J seconds per day at the 
 bottom. Or it may be stated thus : that gravity is greater at 
 the bottom of a mine than at the top by TST^yth part. Letter to 
 James Mather, Esq., South Shields. See also Professor Airy's Lec- 
 ture, 1854. 
 
 ORIGIN OF TERRESTRIAL MAGNETISM. 
 
 The earliest view of Terrestrial Magnetism supposed the ex- 
 istence of a magnet at the earth's centre. As this does not ac- 
 cord with the observations on declination, inclination, and in- 
 tensity, Tobias Meyer gave this fictitious magnet an eccentric 
 position, placing it one-seventh part of the earth's radius from 
 the centre. Hansteen imagined that there were two such mag- 
 
Curiosities of Science. 201 
 
 nets, different in position and intensity. Ampere set aside these 
 unsatisfactory hypotheses by the view, derived from his discov- 
 ery, that the earth itself is an electro-magnet, magnetised by an 
 electric current circulating about it from east to west perpen- 
 dicularly to the plane of the magnetic meridian, to which the 
 same currents give direction as well as magnetise the ores of 
 iron : the currents being thermo-electric currents, excited by the 
 action of the sun's heat successively on the different parts of the 
 earth's surface as it revolves towards the east. 
 
 William Gilbert,* who wrote an able work on magnetic and 
 electric forces in the year 1600, regarded terrestrial magnetism 
 and electricity as two emanations of a single fundamental source 
 pervading all matter, and he therefore treated of both at once. 
 According to Gilbert's idea, the earth itself is a magnet; whilst 
 he considered that the inflections of the lines of equal declina- 
 tion and inclination depend upon the distribution of mass, the 
 configuration of continents, or the form and extent of the deep 
 intervening oceanic basins. 
 
 Till within the last eighty years, it appears to have been the 
 received opinion that the intensity of terrestrial magnetism was 
 the same at all parts of the earth's surface. In the instructions 
 drawn up by the French Academy for the expedition under La 
 Perouse, the first intimation is given of a contrary opinion. It 
 is recommended that the time of vibration of a dipping-needle 
 should be observed at stations widely remote, as a test of the 
 equality or difference of the magnetic intensity; suggesting also 
 that such observations should particularly be made at those parts 
 of the earth where the dip was greatest and where it was least. 
 The experiments, whatever their results may have been, which, 
 in compliance with this recommendation, were made in the ex- 
 pedition of La Perouse, perished in its general catastrophe ; but 
 the instructions survived. 
 
 In 1811, Hansteen took up the subject, and in 1819 pub- 
 lished his celebrated work, clearly demonstrating the fluctua- 
 tions which this element has undergone during the last two 
 centuries ; confirming in great detail the position of Halley, 
 that " the whole magnetic system is in motion, that the mov- 
 ing force is very great as extending its effects from pole to pole, 
 and that its motion is not per saltum, but a gradual and regular 
 motion. " 
 
 THE NORTH AND SOUTH MAGNETIC POLES. 
 
 The knowledge of the geographical position of both Mag- 
 netic Poles is due to the scientific energy of the same naviga- 
 
 * Gilbert was surgeon to Queen Elizabeth and James I., and died in 1603. 
 Whewell justly assigns him an important place among tlie " practical reformers 
 of the physical sciences." He adopted the Copernican doctrine, which Lord Ba- 
 con's inferior aptitude for physical research led him to reject. 
 
Things not generally Knoivn. 
 
 tor, Sir James Ross. His observations of the Northern Mag- 
 netic Pole were made during the second expedition of his uncle, 
 Sir John Ross (1829-1833) ; and of the Southern during the 
 Antarctic expedition under his own command (1839-1843). The 
 Northern Magnetic Pole, in 70 5' lat., 96 43' W. long., is 5 of 
 latitude farther from the ordinary pole of the earth than the 
 Southern Magnetic Pole, 75 35' lat., 154 10' E. long. ; whilst 
 it is also situated farther west from Greenwich than the North- 
 ern Magnetic Pole. The latter belongs to the great island of 
 Boothia Felix, which is situated very near the American conti- 
 nent, and is a portion of the district which Captain Parry had 
 previously named North Somerset. It is not far distant from 
 the western coast of Boothia Felix, near the promontory of Ade- 
 laide, which extends into King William's Sound and Victoria 
 Strait. 
 
 The Southern Magnetic Pole has been directly reached in 
 the same manner as the Northern Pole. On 17th February 
 1841, the Erebus penetrated as far as 76 12' S. lat., and 164 
 E. long. As the inclination was here only 88 40', it was assumed 
 that the Southern Magnetic Pole was about 160 nautical miles 
 distant. Many accurate observations of declination, determin- 
 ing the intersection of the magnetic meridian, render it very 
 probable that the South Magnetic Pole is situated in the inte- 
 rior of the great Antarctic region of South Victoria Land, west 
 of the Prince Albert mountains, which approach the South Pole 
 and are connected with the active volcano of Erebus, which is 
 12,400 feet in height. Humboldt's Cosmos, vol. v. 
 
 MAGNETIC STORMS. 
 
 The mysterious course of the magnetic needle is equally af- 
 fected by time and space, by the sun's course^ and by changes 
 of place on the earth's surface. Between the tropics the hour 
 of the day may be known by the direction of the needle as well 
 as by the oscillations of the barometer. It is affected instantly, 
 but transiently, by the northern light. 
 
 When the uniform horary motion of the needle is disturbed 
 by a magnetic storm, the perturbation manifests itself simulta* 
 neously, in the strictest sense of the word, over hundreds and 
 thousands of miles of sea and land, or propagates itself by de- 
 grees in short intervals every where over the earth's surface. 
 
 Among numerous examples of perturbations occurring simul- 
 taneously and extending over wide portions of the earth's sur- 
 face, one of the most remarkable is that of September 25th, 1841, 
 which was observed at Toronto in Canada, at the Cape of Good 
 Hope, at Prague, and partially in Van JDiemen's Land. Sa- 
 bine adds, "The English Sunday, on which it is deemed sin- 
 ful, after midnight on Saturday, to register an observation, and 
 
Curiosities of Science. 203 
 
 to follow out the great phenomena of creation in their perfect 
 development, interrupted the observation in VanDiemen's Land, 
 where, in consequence of the difference of the longitude, the 
 magnetic storm fell on Sunday." 
 
 It is but justice to add. that to the direct instrumentality of the Bri- 
 tish Association we are indebted for this system of observation, which 
 would not have been possible without some such machinery for concerted 
 action. It being known that the magnetic needle is subject to oscilla- 
 tions, the nature, the periods, and the laws of which were unascertained, 
 under the direction of a committee of the Association magnetic observa- 
 tories were established in various places for investigating these strange 
 disturbances. As might have been anticipated, regularly recurring per- 
 turbations were noted, depending on the hour of the day and the season 
 of the year. Magnetic storms were observed to sweep simultaneously over 
 the whole face of the earth, and these too have now been ascertained to 
 follow certain periodic laws. 
 
 But the most startling result of the combined magnetic observations 
 is the discovery of marked perturbations recurring at intervals of ten 
 years ; a period which seemed to have no analogy to any thing in the 
 universe, but which M. Schwabe has found to correspond with the varia- 
 tion of the spots on the sun, both attaining their maximum and mini- 
 mum developments at the same time. Here, for the present, the dis- 
 covery stops ; but that which is now an unexplained coincidence may 
 hereafter supply the key to the nature and source of Terrestrial Magne- 
 tism : or, as Dr. Lloyd observes, this system of magnetic observation 
 has gone beyond our globe, and opened a new range for inquiry, by 
 showing us that this wondrous agent has power in other parts of the 
 solar system. 
 
 FAMILIAR GALVANIC EFFECTS. 
 
 By means of the galvanic agency a variety of surprising 
 effects have heen produced. Gunpowder, cotton, and other in- 
 flammable substances have been set on fire ; charcoal has been 
 made to burn with a brilliant white flame ; water has been de- 
 composed into its elementary parts ; metals have been melted 
 and set on fire ; fragments of diamond, charcoal, and plumbago 
 have been dispersed as if evaporated ; platina, the hardest and 
 the heaviest of the metals, has been melted as readily as wax 
 in the flame of a candle ; the sapphire, quartz, magnesia, lime, 
 and the firmest compounds in nature, have been fused. Its 
 effects on the animal system are no less surprising. 
 
 The agency of galvanism explains why porter has a different 
 and more pleasant taste when drunk out of a pewter-pot than 
 out of glass or earthenware ; why works of metal which are 
 soldered together soon tarnish in the place where the metals are 
 joined ; and why the copper sheathing of ships, when fastened 
 with iron nails, is soon corroded about the place of contact. In 
 all these cases a galvanic circle is formed which produces the 
 effects. 
 
 THE SIAMESE TWINS GALVANISED. 
 
 It will be recollected that the Siamese twins, brought to 
 
Things not generally Known. 
 
 England in the year 1829, were united by a jointed cartilagi- 
 nous band. A silver tea spoon being placed on the tongue of 
 one of the twins and a disc of zinc on the tongue of the other, 
 the moment the two metals were brought into contact both 
 the boys exclaimed, " Sour, sour ;" thus proving that the gal- 
 vanic influence passed from the one to the other through the 
 connecting band. 
 
 MINUTE AND VAST BATTERIES. 
 
 Dr. Wollaston made a simple apparatus out of a silver thim- 
 ble, with its top cut off. It was then partially flattened, and 
 a small plate of zinc being introduced into it, the apparatus was 
 immersed in a weak solution of sulphuric acid. With this mi- 
 nute battery, Dr. Wollaston was able to fuse a wire of platinum 
 fto'ooth of an inch in diameter a degree of tenuity to which no 
 one had ever succeeded in drawing it. 
 
 Upon the same principle (that of introducing a plate of zinc 
 between two plates of other metals) Mr. Children constructed 
 his immense battery, the zinc plates of which measured six feet 
 by two feet eight inches ; each plate of zinc being placed be- 
 tween two of copper, and each triad of plates being enclosed in 
 a separate cell. With this powerful apparatus a wire of plati- 
 num, Voth of an inch in diameter and upwards of five feet long, 
 was raised to a red heat, visible even in the broad glare of day- 
 light. 
 
 The great battery at the Royal Institution, with which Sir 
 Humphry Davy discovered the composition of the fixed alkalies, 
 was of immense power. It consisted of 200 separate parts, each 
 composed of ten double plates, and each plate containing thirty- 
 two square inches ; the number of double plates being 2000, and 
 the whole surface 128,000 square inches. 
 
 Mr. Highton, C.E., has made a battery which exposes a sur- 
 face of only T-j^yth part of an inch : it consists of but one cell ; it 
 is less than 10 oooth part of a cubic inch, and yet it produces 
 electricity more than enough to overcome all the resistance in 
 the inventor's brother's patent Gold-leaf Telegraph, and works 
 the same powerfully. It is, in short, a battery which, although 
 it will go through the ei/e of a needle, will yet work a telegraph 
 well. Mr. Highton had previously constructed a battery in size 
 less than -^th of a cubic inch : this battery, he found, would 
 for a month together ring a telegraph-bell ten miles off. 
 
 ELECTRIC INCANDESCENCE OF CHARCOAL POINTS. 
 
 The most splendid phenomenon of this kind is the combus- 
 tion of charcoal points. Pointed pieces of the residuum ob- 
 tained from gas retorts will answer best, or Bunsen's composi- 
 tion may be used for this purpose. Put two such charcoal 
 
Curiosities of Science. 05 
 
 points in immediate contact with the wires of your battery ; 
 bring the points together, and they will begin to burn with a 
 dazzling white light. The charcoal points of the large appara- 
 tus belonging to the Royal Institution became incandescent at 
 a distance of ^th of an inch ; when the distance was gradually 
 increased till they were four inches asunder, they continued to 
 burn with great intensity, and a permanent stream of light 
 played between them. Professor Bunsen obtained a similar 
 flame from a battery of four pairs of plates, its carbon surface 
 containing 29 feet. The heat of this flame is so intense, that 
 stout platinum wire, sapphire, quartz, talc, and lime are re- 
 duced by it to the liquid form. It is worthy of remark, that no 
 combustion, properly so called, takes place in the charcoal it- 
 self, which sustains only an extremely minute loss in its weight 
 and becomes rather denser at the points. The phenomenon is 
 attended with a still more vivid brightness if the charcoal points 
 are placed in a vacuum, or in any of those gases which are not 
 supporters of combustion. Instead of two charcoal points, one 
 only need be used if the following arrangement is adopted : lay 
 the piece of charcoal on some quicksilver that is connected with 
 one pole of the battery, and complete the circuit from the other 
 pole by means of a strip of platinum. When Professor Peschel 
 used a piece of well-burnt coke in the manner just described, 
 he obtained a light which was almost intolerable to the eyes. 
 
 VOLTAIC ELECTRICITY. 
 
 On January 31, 1793, Volta announced to the Royal Society 
 his discovery of the development of electricity in metallic bodies. 
 Galvani had given the name of Animal Electricity to the power 
 which caused spontaneous convulsions in the limbs of frogs 
 when the divided nerves were connected by a metallic wire. 
 Volta, however, saw the true cause of the phenomena described 
 by Galvani. Observing that the effects were far greater when 
 the connecting medium consisted of two different kinds of 
 metal, he inferred that the principle of excitation existed in 
 the metals, and not in the nerves of the animal ; and he as- 
 sumed that the exciting fluid was ordinary electricity, produced 
 by the contact of the two metals ; the convulsions of the frog 
 consequently arose from the electricity thus developed passing 
 along its nerves and muscles. 
 
 In 1800 Volta invented what is now called the Voltaic 
 Pile, or compound Galvanic circle. 
 
 The term Animal Electricity (says Dr. Whewell) has been superseded 
 by others, of which Galvanism is the most familiar; but I think that 
 V olta's office in this discovery is of a much higher and more philosophi- 
 cal kind than that of Galvani ; and it would on this account be more fit- 
 ting to employ the term Voltaic Electricity, which, indeed, is very com- 
 
206 Things not generally Known. 
 
 monly used, especially by our most recent and comprehensive writers. 
 The Voltaic pile was a more important step in the history of electricity 
 than the Ley. I en jar had been Hist. Ind. Sciences, vol. lii. 
 
 No one who wishes to judge impartially of the scientific history of 
 these times and of its leaders, will consider Galvani and Volta as equals, 
 or deny the vast superiority of the latter over all his opponents or fellow- 
 workers, more especially over those of the Bologna s hool. We shall 
 scarcely again lind in one man gifts so rich and so calculated for research 
 as were combined in Volta. He possessed that " incomprehensible 
 talent," as Dove has called it, for separating the essential from the im- 
 material in complicated phenomena ; that boldness of invention which, 
 must precede experiment, controlled by the most strict and cautious 
 mode of manipulation ; that unremitting attention which allows no cir- 
 cumstance to pass unnoticed ; lastly, with so much acuteness, so much 
 simplicity, so much grandeur of conception, combined with such depth 
 of thought, he had a hand which was the hand of a workman. Jame- 
 son's Journal, No. 106. 
 
 THE VOLTAIC BATTERY AND THE GYMNOTUS. 
 
 " We boast of our Voltaic Batteries," says Mr. Smee. " I 
 should hardly be believed if I were to say that I did not feel 
 pride in having constructed my own, especially when I consider 
 the extensive operations which it has conducted. But when I 
 compare my battery with the battery which nature has given 
 to the electrical eel and the torpedo, how insignificant are hu- 
 man operations compared with those of the Architect of living 
 beings ! The stupendous electric eel in the Polytechnic Insti- 
 tution, when he seeks to kill his prey, encloses him in a circle ; 
 then, by volition, causes the voltaic force to be produced, and 
 the hapless creature is instantly killed. It would probably re- 
 quire ten thousand of my artificial batteries to effect the same 
 object, as the creature is killed instanteron receiving the shock. 
 As much, however, as my battery is inferior to that of the elec- 
 tric fish, so is man superior to the same animal. Man is en- 
 dowed with a power of mind competent to appreciate the force 
 of matter, and is thus enabled to make the battery. The eel 
 can but use the specific apparatus which nature has bestowed 
 upon it." 
 
 Some observations upon the electric current around the 
 gymnotus, and notes of experiments with this and other electric 
 fish, will be found in Things not generally Known, p. 199. 
 
 VOLTAIC CURRENTS IN MINES. 
 
 Many years ago, Mr. R. W. Fox, from theory entertaining 
 a belief that a connection existed between voltaic action in the 
 interior of the earth and the arrangement of metalliferous veins, 
 and also the progressive increase of temperature in the strata as 
 we descend from the surface, endeavoured to verify the same 
 from experiment in the mine of Huel Jewel, in Cornwall. His 
 
Curiosities of Science. 207 
 
 apparatus consisted of small plates of sheet-copper, which were 
 fixed in contact with a plate in the veins with copper nails, or 
 else wedged closely against them with wooden props stretched 
 across the galleries. Between two of these plates, at different 
 stations, a communication was made by means of a copper 
 wire TjVth of an inch in diameter, which included a galvanometer 
 in its circuit. In some instances 300 fathoms of copper wire 
 were employed. It was then found that the intensity of the 
 voltaic current was generally greater in proportion to the 
 greater abundance of copper ore in the veins, and in some de- 
 gree to the depth of the stations. Hence Mr. Fox's discovery 
 promised to be of practical utility to the miner in discovering 
 the relative quantity of ore in the veins, and the directions in 
 which it most abounds. 
 
 The result of extended experiments, mostly made by Mr. 
 Robert Hunt, has not, however, confirmed Mr. Fox's views. 
 It has been found that the voltaic currents detected in the lodes 
 are due to the chemical decomposition going on there ; and the 
 more completely this process of decomposition is established, 
 the more powerful are the voltaic currents. Meanwhile these 
 have nothing whatever to do with the increase of temperature 
 with depth. Recent observations, made in the deep mines of 
 Cornwall under the direction of Mr. Fox, do not appear consis- 
 tent with the law of thermic increase as formerly established, 
 the shallow mines giving a higher ratio of increase than the 
 deeper ones. 
 
 GEKMS OF ELECTRIC KNOWLEDGE. 
 
 Two centuries and a half ago, Gilbert recognised that the 
 property of attracting light substances when rubbed, be their 
 nature what it may, is not peculiar to amber, which is a con- 
 densed earthy juice cast up by the waves of the sea, and in 
 which flying insects, ants, and worms lie entombed as in eter- 
 nal sepulchres. The force of attraction (Gilbert continues) be- 
 longs to a whole class of very different substances, as glass, 
 sulphur, sealing-wax, and all resinous substances rock crystal 
 and all precious stones, alum and rock-salt. Gilbert measured 
 the strength of the excited electricity by means of a small 
 needle not made of iron which moved freely on a pivot, and 
 perfectly similar to the apparatus used by Haiiy and Brewster 
 in testing the electricity excited in minerals by heat and fric- 
 tion. "Friction," says Gilbert further, "is productive of a 
 stronger effect in dry than in humid air ; and rubbing with 
 silk cloths is most advantageous." 
 
 Otto von Guerike, the inventor of the air-pump, was the 
 first who observed any thing more than mere phenomena of 
 attraction. In his experiments with a rubbed piece of sulphur 
 
208 Things not generally Known. 
 
 he recognised the phenomena of repulsion, which subsequently 
 led to the establishment of the laws of the sphere of action and 
 of the distribution of electricity. He heard the first sound, and 
 saw the first light, in artificially -produced electricity. In an ex- 
 periment instituted by Newton in 1675, the first traces of an 
 electric charge in a rubbed plate of glass were seen. 
 
 TEMPERATURE AND ELECTRICITY. 
 
 Professor Tyndall has shown that all variations of tempera- 
 ture, in metals at least, excite electricity. When the wires of 
 a galvanometer are brought in contact with the two ends of a 
 heated poker, the prompt deflection of the galvanometer-needle 
 indicates that a current of electricity has been sent through 
 the instrument. Even the two ends of a spoon, one of which 
 has been dipped in hot water, serve to develop an electric 
 current. ; and in cutting a hot beefsteak with a steel knife and 
 a silver fork there is an excitement of electricity. The mere 
 heat of the finger is sufficient to cause the deflection of the 
 galvanometer ; and when ice is applied to the part that has 
 been previously warmed, the galvanometer-needle is deflected 
 in the contrary direction. A small instrument invented by 
 Melloni is so extremely sensitive of the action of heat, that 
 electricity is excited when the hand is held six inches from it. 
 
 VAST ARRANGEMENT OF ELECTRICITY. 
 
 Professor Faraday has shown that the Electricity which de- 
 composes, and that which is evolved in the decomposition of, 
 a certain quantity of matter, are alike. What an enormous 
 quantity of electricity, therefore, is required for the decompo- 
 sition of a single grain of water ! It must be in quantity suf- 
 ficient to sustain a platinum wire r^th of an inch in thickness 
 red-hot in contact with the air for three minutes and three- 
 quarters. It would appear that 800,000 charges of a Leyden 
 battery, charged by thirty turns of a very large and powerful 
 plate-machine in full action, are necessary to supply electricity 
 sufficient to decompose a single grain of water, or to equal the 
 quantity of electricity which is naturally associated with the 
 elements of that grain of water, endowing them with their mu- 
 tual chemical affinity. Now the above quantity of electricity, 
 if passed at once through the head of a rat or a cat, would kill 
 it as by a flash of lightning. The quantity is, indeed, equal to 
 that which is developed from a charged thunder- cloud. 
 
 DECOMPOSITION OF WATER BY ELECTRICITY. 
 
 Professor Andrews, by an ingenious arrangement, is enabled 
 to show that water is decomposed by the common machine; 
 
Curiosities of Science. 209 
 
 and by using an electrical kite, he was able, in fine weather, to 
 produce decomposition, although so slowly that only rooWoth 
 of a grain of water was decomposed per hour. Faraday has 
 proved that the decomposition of one single grain of water pro- 
 duces more electricity than is contained in the most powerful 
 flash of lightning. 
 
 ELECTRICITY IN BREWING. 
 
 Mr. Black, a practical writer upon Brewing, has found that 
 by the practice of imbedding the fermentation- vats in the earth, 
 and connecting them by means of metallic pipes, an electrical 
 current passes through the beer and causes it to turn sour. As 
 a preventive, he proposed to place the vats upon wooden blocks, 
 or on any other non-conductors, so that they may be insulated. 
 It has likewise been ascertained that several brewers who had 
 brewed excellent ale on the south side of the street, on re- 
 moving to the north have failed to produce good ale. 
 
 ELECTRIC PAPER. 
 
 Professor Schonbein has prepared paper, as transparent as 
 glass and impermeable to water, which develops a very ener- 
 getic electric force. By placing some sheets on each other, 
 and simply rubbing them once or twice with the hand, it be- 
 comes difficult to separate them. If this experiment is per- 
 formed in the dark, a great number of distinct flashes may be 
 perceived between the separated surfaces. The disc of the 
 electrophorus, placed on a sheet that has been rubbed, pro- 
 duces sparks of some inches in length. A thin and very dry 
 sheet of paper, placed against the wall, will adhere strongly 
 to it for several hours if the hand be passed only once over it. 
 If the same sheet be passed between the thumb and fore-finger 
 in the dark, a luminous band will be visible. Hence with this 
 paper may be made powerful and cheap electrical machines. 
 
 DURATION OF THE ELECTRIC SPARK. 
 
 By means of Professor Wheatstone's apparatus, the Dura- 
 tion of the Electric Spark has been ascertained not to exceed 
 the twenty-five-thousandth part of a second. A cannon-ball, 
 if illumined in its flight by a flash of lightning, would, in 
 consequence of the momentary duration of the light, appear to 
 be stationary, and even the wings of an insect, that move ten 
 thousand times in a second, would seem at rest. 
 
 VELOCITY OF ELECTRIC LIGHT. 
 
 On comparing the velocities of solar, stellar, and terrestrial 
 light, which are all equally refracted in the prism, with the 
 
 p 
 
Things not generally Known. 
 
 velocity of the light of frictional electricity, we are disposed, 
 in accordance with Wheatstone's ingeniously-conducted experi- 
 ments, to regard the lowest ratio in which the latter excels the 
 former as 3 : 2. According to the lowest results of Wheatstone's 
 apparatus, electric light traverses 288,000 miles in a second. 
 If we reckon 189,938 miles for stellar light, according to Struve, 
 we obtain the difference of 95,776 miles as the greater velocity 
 of electricity in one second. 
 
 From the experiment described in Wheatstone's paper (Phi- 
 losophical Transactions for 1834), it would appear that the hu- 
 man eye is capable of perceiving phenomena of light whose 
 duration is limited to the millionth part of a second. 
 
 In Professor Airy's experiments with the electric telegraph 
 to determine the difference of longitude between Greenwich 
 and Brussels, the time spent by the electric current in passing 
 from one observatory to the other (270 miles) was found to be 
 0-109", or rather more than the ninth part of a second; and 
 this determination rests on 2616 observations : a speed which 
 would " girdle the globe" in ten seconds. 
 
 IDENTITY OF ELECTEIC AND MAGNETIC ATTRACTION. 
 
 This vague presentiment of the ancients has been verified 
 in our own times. " When electrum (amber)," says Pliny, "is 
 animated by friction and heat, it will attract bark and dry 
 leaves precisely as the loadstone attracts iron." The same 
 words may be found in the literature of an Asiatic nation, and 
 occur in a eulogium on the loadstone by the Chinese physicist 
 Knopho, in the fourth century: "The magnet attracts iron 
 as amber does the smallest grain of mustard-seed. It is like a 
 breath of wind, which mysteriously penetrates through both, 
 and communicates itself with the rapidity of an arrow." 
 
 Humboldt observed with astonishment on the woody banks of the 
 Orinoco, in the sports of the natives, that the excitement of electricity 
 by friction was known to these savage races. Children may be seen to 
 rub the dry, flat, and shining seeds or husks of a trailing plant until 
 they are able to attract threads of cotton and pieces of bamboo-cane. 
 What a chasm divides the electric pastime of these naked copper-co- 
 loured Indians from the discovery of a metallic conductor discharging 
 its electric shocks, or a pile formed of many chemically-decomposing 
 substances, or a light-engendering magnetic apparatus ! In such a 
 ch ism lie buried thousands of years, that compose the history of the in- 
 tellectual development of mankind. Humbvldt's Cosmos, vol. i. 
 
 THEORY OF THE ELECTRO-MAGNETIC ENGINE. 
 
 Several years ago a speculative American set the industrial 
 world of Europe in excitement by this proposition. The Mag- 
 neto-Electric Machines often made use of in the case of rheu- 
 matic disorders are well known. By imparting a swift rotation 
 
Curiosities of Science. 
 
 to the magnet of such a machine, we obtain powerful currents 
 of electricity. If these be conducted through water, the latter 
 will be reduced to its two components, oxygen and hydrogen. 
 By the combustion of hydrogen water is again generated. _ If 
 this combustion takes place, not in atmospheric air, in which 
 oxygen only constitutes a fifth part, but in pure oxygen, and 
 if a bit of chalk be placed in the flame, the chalk will be raised 
 to a white heat, and give us the sun-like Drummond light : at 
 the same time the flame develops a considerable quantity of 
 heat. Now the American inventor proposed to utilise in this 
 way the gases obtained from electrolytic decomposition ; and 
 asserted that by the combustion a sufficient amount of heat 
 was generated to keep a small steam-engine in action, which 
 again drove his magneto-electric machine, decomposed the 
 water, and thus continually prepared its own fuel. This would 
 certainly have been the most splendid of all discoveries, a per- 
 petual motion which, besides the force that kept it going, 
 generated light like the sun, and warmed all around it. The 
 affair, however, failed, as was predicted by those acquainted 
 with the physical investigations which bear upon the subject. 
 Professor Helmholtz. 
 
 MAGNETIC CLOCK AND WATCH. 
 
 In the Museum of the Royal Society are two curiosities of 
 the seventeenth century which are objects of much interest in 
 association with the electric discoveries of our day. These are 
 a Clock, described by the Count Malagatti (who accompanied 
 Cosmo III., Grand Duke of Tuscany, to inspect the Museum 
 in 1669) as more worthy of observation than all the other ob- 
 jects in the cabinet. Its " movements are derived from the 
 vicinity of a loadstone, and it is so adjusted as to discover the 
 distance of countries at sea by the longitude." The analogy 
 between this clock and the electric clock of the present day is 
 very remarkable. Of kindred interest is " Hook's Magnetic 
 Watch," often alluded to in the Royal Society's Journal-book 
 of 1669 as " going slower or faster according to the greater or 
 less distance of the loadstone, and so moving regularly in any 
 posture." 
 
 WHEATSTONE'S ELECTKO-MAGNETIC CLOCK. 
 In this ingenious invention, the object of Professor Wheat- 
 stone was to enable a simple clock to indicate exactly the same 
 time in as many different places, distant from each other, as 
 may be required. A standard clock in an observatory, for ex- 
 ample, would thus keep in order another clock in each apart- 
 ment, and that too with such accuracy, that all of them, how- 
 ever numerous, will beat dead seconds audibly with as great pre- 
 
Things not generally Known. 
 
 cision as the standard astronomical time-piece with which they are 
 connected. But, besides this, the subordinate time-pieces thus 
 regulated require none of the mechanism for maintaining or 
 regulating the power. They consist simply of a face, with its 
 second, minute, and hour hands, and a train of wheels which 
 communicate motion from the action of the second-hand to 
 that of the hour-hand, in the same manner as an ordinary clock- 
 train. Nor is this invention confined to observatories and large 
 establishments. The great horologe of St. Paul's might, by a 
 suitable network of wires, or even by the existing metallic 
 pipes of the metropolis, be made to command and regulate all 
 the other steeple-clocks in the city, and even every clock within 
 the precincts of its metallic bounds. As railways and tele- 
 graphs extend from London nearly to the remotest cities and 
 villages, the sensation of time may be transmitted along with 
 the elements of language ; and the great cerebellum of the 
 metropolis may thus constrain by its sympathies, and regulate 
 by its power, the whole nervous system of the empire. 
 
 HOW TO MAKE A COMMON CLOCK ELECTRIC. 
 
 M. Kammerer of Belgium effects this by an addition to any 
 clock whereby it is brought into contact with the two poles of 
 a galvanic battery, the wires from which communicate with a 
 drum moved by the clockwork ; and every fifteen seconds the 
 current is changed, the positive and the negative being trans- 
 mitted alternately. A wire is continued from the drum to the 
 electric clock, the movement of which, through the plate-glass 
 dial, is seen to be two pairs of small straight electro-magnets, 
 each pair having their ends opposite to the other pair, with about 
 half an inch space between. Within this space there hangs a 
 vertical steel bar, suspended from a spindle at the top. The rod 
 has two slight projections on each side parallel to the ends of 
 the wire-coiled magnets. When the electric current comes on 
 the wire from the positive end of the battery (through the 
 drum of the regulator- clock) the positive magnets attract the 
 bar to it, the distance being perhaps the sixteenth of an inch. 
 When, at the end of fifteen seconds, the negative pole operates, 
 repulsion takes effect, and the bar moves to the opposite side. 
 This oscillating bar gives motion to a wheel which turns the 
 minute and hour hands. 
 
 M. Kammerer states, that if the galvanic battery be at- 
 tached to any particular standard clock, any number of clocks, 
 wherever placed, in a city or kingdom, and communicating with 
 this by a wire, will indicate precisely the same time. Such is 
 the precision, that the sounds of three clocks thus beating simul- 
 taneously have been mistaken as proceeding from one clock. 
 
Curiosities of Science. 213 
 
 DR. FRANKLIN'S ELECTRICAL KITE. 
 
 Several philosophers had observed that lightning and elec- 
 tricity possessed many common properties ; and the light which 
 accompanied the explosion, the crackling noise made by the 
 flame, and other phenomena, made them suspect that lightning 
 might be electricity in a highly powerful state. But this con- 
 nection was merely the subject of conjecture until, in the year 
 1750, Dr. Franklin suggested an experiment to determine the 
 question. While he was waiting for the building of a spire at 
 Philadelphia, to which he intended to attach his wire, the ex- 
 periment was successfully made at Marly-la- Ville, in France, in 
 the year 1 752 ; when lightning was actually drawn from the 
 clouds by means of a pointed wire, and it was proved to be 
 really the electric fluid. 
 
 Almost every early electrical discovery of importance was made by 
 Fellows of the Royal Society, and is to be found recoi'ded in the Philo- 
 sophical Transactions. In the forty-fifth volume occurs the first men- 
 tion of Dr. Franklin's name, and his theory of positive and negative 
 electricity. In 1756 he was elected into the Society, " without any fee 
 or other payment." His previous communications to the Transactions, 
 particularly the account of his electrical kite, had excited great intei-est. 
 ( Welds History of the Royal Society.} It is thus described by him in a 
 letter dated Philadelphia, October 1, 1752 : 
 
 " As frequent mention is made in the public papers from Europe of 
 the success of the Marly-la- Ville experiment for drawing the electric fire 
 from clouds by means of pointed rods of iron erected on high buildings, 
 &c., it may be agreeable to the curious to be informed that the same 
 experiment has succeeded in Philadelphia, though made in a different 
 and more easy manner, which any one may try, as follows : 
 
 Make a small cross of two light strips of cedar, the arms so long as 
 to reach to the four corners of a large thin silk handkerchief when ex- 
 tended. Tie the corners of the handkerchief to the extremities of the 
 cross ; so you have the body of a kite, which, being properly accommo- 
 dated with a tail, loop, and string, will rise in the air like a kite made 
 of paper ; but this, being of silk, is fitter to bear the wet and wind of a 
 thunder-gust without tearing. To the top of the upright stick of the 
 cross is to be fixed a very sharp-pointed wire, rising a foot or more 
 above the wood. To the end of the twine, next the band, is to be tied 
 a silk ribbon ; and where the twine and silk join a key may be fastened. 
 
 The kite is to be raised when a thunder-gust appears to be coming 
 on, and the person who holds the string must stand within a door or 
 window, or under some cover, so that the silk ribbon may not be wet ; 
 and care must be taken that the twine does not touch the frame of the 
 door or window. As soon as any of the thunder-clouds come over the 
 kite, the pointed wire will draw the electric fire from them ; and the 
 kite, with all the twine, will be electrified ; and the loose filaments of 
 the twine will stand out every way, and be attracted by an approaching 
 finger. 
 
 When the rain has wet the kite and twine, so that it can conduct 
 the electric fire freely, you will find it stream out plentifully from the 
 key on the approach of your knuckle. At this key the phial may be 
 charged ; and from electric fire thus obtained spirits may be kindled, 
 
Things not generally Known. 
 
 and all the other electrical experiments be performed which are usually 
 done by the help of a rubbed-glass globe or tube ; and thus the same- 
 ness of the electric matter with that of lightning is completely demon- 
 strated." Philosophical Transactions. 
 
 Of all this great man's (Franklin's) scientific excellencies, 
 the most remarkable is the smallness, the simplicity, the ap- 
 parent inadequacy of the means which he employed in his 
 experimental researches. His discoveries were all made with 
 hardly any apparatus at all ; and if at any time he had been 
 led to employ instruments of a somewhat less ordinary descrip- 
 tion, he never rested satisfied until he had, as it were, after- 
 wards translated the process by resolving the problem with 
 such simple machinery that you might say he had done it 
 wholly unaided by apparatus. The experiments by which the 
 identity of lightning and electricity was demonstrated were 
 made with a sheet of brown paper, a bit of twine or silk thread, 
 and an iron key ! Lord Brougham.* 
 
 FATAL EXPERIMENT WITH LIGHTNING. 
 
 These experiments are not without danger ; and a flash of 
 lightning has been found to be a very unmanageable instrument. 
 In 1753, M. Richman, at St. Petersburg, was making an ex- 
 periment of this kind by drawing lightning into his room, when, 
 incautiously bringing his head too near the wire, he was struck 
 dead by the flash, which issued from it like a globe of blue fire, 
 accompanied by a dreadful explosion. 
 
 FARADAY'S ELECTRICAL ILLUSTRATIONS. 
 
 The following are selected from the very able series of lec- 
 tures delivered by Professor Faraday at the Royal Institution : 
 
 The Two Electricities. After having shown by various experiments 
 the attractions and repulsions of light substances from excited glass and 
 from an excited tube of gutta-percha, Professor Faraday proceeds to 
 point out the difference in the character of the electricity produced by 
 the friction of the two substances. The opposite characters of the elec- 
 tricity evolved by the friction of glass and of that excited by the friction 
 of gutta-percha and shellac are exhibited by several experiments, in 
 which the attraction of the positive and negative electricities to each 
 other and the neutralisation of electrical action on the combination of 
 the two forces are distinctly observable. Though adopting the terms 
 " positive" and " negative" in distinguishing the electricity excited by 
 glass from that excited by gutta-percha and resinous bodies, Professor 
 Faraday is strongly opposed to the Franklinian theory from which these 
 terms are derived. According to Franklin's view of the nature of elec- 
 trical excitement, it arises from the disturbance, by friction or other 
 means, of the natural quantity of one electric fluid which is possessed 
 by all bodies ; an excited piece of glass having more than its natural 
 
 * This illustration, it will be seen, does not literally correspond with the 
 details which precede it. 
 
Curiosities of Science. 215 
 
 share, which has been taken from the rubber, the latter being conse- 
 quently in a minus or negative state. This theory Professor Faraday 
 considers to be opposed to the distinct characteristic actions of the two 
 forces ; and, in his opinion, it is impossible to deprive any body of elec- 
 tricity, and reduce it to the minus state of Franklin's hypothesis. 
 Taking a Zamboni's pile, he applies its two ends separately to an elec- 
 ti-ometer, to show that each end pi-oduces opposite kinds of electricity, 
 and that the zero, or absence of electrical excitement, only exists in the 
 centre of the pile. To prove how completely the two electricities neu- 
 tralise each other, an excited rod of gutta-percha and the piece of flannel 
 with which it has been rubbed are laid on the top of the electrometer 
 without any sign of electricity whilst they are together ; but when either 
 is removed, the gold leaves diverge with positive and negative electri- 
 city alternately. The Professor dwells strongly on the peculiarity of the 
 dual force of electricity, which, in respect of its duality, is unlike any 
 other force in nature. He then contrasts its phenomena of instanta- 
 neous conduction with those of the somewhat analogous force of heat; 
 and he illustrates by several striking experiments the peculiar property 
 which static electricity possesses of being spread only over the surfaces 
 of bodies. A metal ice-pail is placed on an insulated stand and electri- 
 fied, and a metal ball suspended by a string is introduced, and touches 
 the bottom and sides without having any electricity imparted to it, but 
 on touching the outside it becomes strongly electrical. The experiment 
 is repeated with a wooden tub with the same result ; and Professor Fa- 
 raday mentions the still more remarkable manner in which he has 
 proved the surface distribution of electi'icity by having a small chamber 
 constructed and covered with tinfoil, which can be insulated ; and whilst 
 torrents of electricity are being evolved from the external surface, he 
 enters it with a galvanometer, and cannot perceive the slightest mani- 
 festation of electricity within. 
 
 The Two Threads. A curious experiment is made with two kinds of 
 thread used as the conducting force. From the electric machine on the 
 table a silk thread is first carried to the indicator a yard or two off, and 
 is shown to be a non-conductor when the glass tube is rubbed and ap- 
 plied to the machine (although the silk, when wetted, conducted) ; while 
 a metallic thread of the same thickness, when treated in the same way, 
 conducts the force so much as to vehemently agitate the gold leaves 
 within the indicator. 
 
 Non-conducting Bodies. The action that occurs in bodies which 
 cannot conduct is the most important part of electrical science. The 
 principle is illustrated by the attraction arid repulsion of an electrified 
 ball of gilt paper by a glass tube, between which and the ball a sheet 
 of shellac is suspended. The nearer a ball of another description an 
 tmelectrical insulated body is brought to the Leyden jar when charged, 
 the greater influence it is seen to possess over the gold leaf within the 
 indicator, by induction, not by conduction. The questions, how elec- 
 tricities attract each other, what kind of electricity is drawn from the 
 machine to the hand, how the hand was electric, are thus illustrated. 
 To show the divers operations of this wonderful force, a tub (a bad con- 
 ductor) is placed by the electric machine. When the latter is charged, 
 a ball, having been electrified from it, is held in the tub, and rattles 
 against its sides and bottom. On the application of the ball to the indi- 
 cator, the gold leaf is shown not to move, whereas it is agitated mani- 
 festly when the same process is gone through with the exception that 
 the ball is made to touch the outside only of the tub. Similar experi- 
 
216 Things not generally Known. 
 
 ments with a ball in an ice-pail and a vessel of wire -gauze, into the 
 latter of which is introduced a mouse, which is shown to receive no 
 shock, and not to be frightened at all ; while from the outside of the 
 vessel electric sparks are rapidly produced. This latter demonstration 
 proves that, as the mouse, so men and women, might be safe inside a 
 building with proper conductors while lightning played about the ex- 
 terior. The wire-gauze being turned inside out, the principle is shown 
 to be irreversible in spite of the change what has been the un electrical 
 inside of the vessel being now, when made the outside portion, capable 
 of receiving and ti-ansmitting the power, while the original outside is 
 now unelectrical. 
 
 Repulsion of Bodies. A remarkable and playful experiment, by 
 which the repulsion of bodies similarly electrified is illustrated, consists 
 in placing a basket containing a heap of small pieces of paper on an in- 
 sulated stand, and connecting it with the prime conductor of the electri- 
 cal machine ; when the pieces of paper rise rapidly after each other into 
 the air, and descend on the lecture-tablelike a fall of snow. The effect 
 is greatly increased when a metal disc is substituted for the basket. 
 
 ORIGIN OF THE LEYDEN JAR. 
 
 Muschenbroek and Linnaeus had made various experiments 
 of a strong kind with water and wire. The former, as appears 
 from a letter of his to Reaumur, filled a small bottle with water, 
 and having corked it up, passed a wire through the cork into 
 the bottle. Having rubbed the vessel on the outside and sus- 
 pended it to the electric machine, he was surprised to find that 
 on trying to pull the wire out he was subjected to an awfully 
 severe shock in his joints and his whole body, such as he de- 
 clared he would not suffer again for any experiment. Hence 
 the Leyden jar, which owes its name to the University of Ley- 
 den, with which, we believe, Muschenbroek was connected. 
 Faraday. 
 
 DANGER TO GUNPOWDER MAGAZINES. 
 
 By the illustration of a gas globule, which is ignited from a 
 spark by induction, Mr. Faraday has proved in a most interest- 
 ing manner that the corrugated-iron roofs of some gunpowder- 
 magazines, on the subject of which he had often been consulted 
 by the builders, with a view to the greater safety of these manu- 
 factories, are absolutely dangerous by the laws of induction ; 
 as, by the return of induction, while a storm was discharging 
 itself a mile or two off, a secondary spark might ignite the build- 
 ing. 
 
 ARTIFICIAL CRYSTALS AND MINERALS. " THE CROSSE MITE." 
 
 Among the experimenters on Electricity in our time who 
 have largely contributed to the " Curiosities of Science," An- 
 drew Crosse is entitled to special notice. In his school- days he 
 became greatly attached to the study of electricity ; and on set- 
 
Curiosities of Science. 217 
 
 tling on his paternal estate, Fyne Court, on the Quantock Hills 
 in Somersetshire, he there devoted himself to chemistry, min- 
 eralogy, and electricity, pursuing his experiments wholly inde- 
 pendently of theories, and searching only for facts. In Holwell 
 Cavern, near his residence, he observed the sides and the roof 
 covered with Arragonite crystallisations, when his observations 
 led him to conclude that the crystallisations were the effects, 
 at least to some extent, of electricity. This induced him to 
 make the attempt to form artificial crystals by the same means, 
 which he began in 1807. He took some water from the cave, 
 filled a tumbler, and exposed it to the action of a voltaic bat- 
 tery excited by water alone, letting the platinum-wires of the 
 battery fall on opposite sides of the tumbler from the opposite 
 poles of the battery. After ten days' constant action, he pro- 
 duced crystals of carbonate of lime ; and on repeating the ex- 
 periment in the dark, he produced them in six days. Thus Mr. 
 Crosse simulated in his laboratory one of the hitherto most mys- 
 terious processes of nature. 
 
 He pursued this line of research for nearly thirty years at 
 Fyne Court, where his electrical-room and laboratory were on 
 an enormous scale : the apparatus had cost some thousands of 
 pounds, and the house was nearly full of furnaces. He carried 
 an insulated wire above the tops of the trees around his house 
 to the length of a mile and a quarter, afterwards shortened to 
 1800 feet. By this wire, which was brought into connection 
 with the apparatus in a chamber, he was enabled to see con- 
 tinually the changes in the state of the atmosphere, and could 
 use the fluid so collected for a variety of purposes. In 1816, 
 at a meeting of country gentlemen, he prophesied that, " by 
 means of electrical agency, we shall be able to communicate our 
 thoughts simultaneously with the uttermost ends of the earth." 
 Still, though he foresaw the powers of the medium, he did not 
 make any experiments in that direction, but confined himself 
 to the endeavour to produce crystals of various kinds. He ul- 
 timately obtained forty-one mineral crystals, or minerals uucrys- 
 tallised, in the form in which they are produced by nature, in- 
 cluding one sub-sulphate of copper an entirely new mineral, 
 neither found in nature nor formed by art previously. His be- 
 lief was that even diamonds might be produced in this way. 
 
 Mr. Crosse worked alone in his retreat until 1836, when, 
 attending the meeting of the British Association at Bristol, 
 he was induced to explain his experiments, for which he was 
 highly complimented by Dr. Buckland, Dr. Dalton, Professor 
 Sedgwick, and others.* 
 
 * Mr. Crosse gave to the meeting a general invitation to Fyne Court; one of 
 the first to accept which was Sir Richard Phillips, who, on his return to Brigh- 
 ton, described in a very attractive manner, at the Sussex Institution, Mr. Crosse's 
 
218 Things not generally Known. 
 
 Shortly after Mr. Crosse's return to Fyne Court, while pur- 
 suing his experiments for forming crystals from a highly caus- 
 tic solution out of contact with atmospheric air, he was greatly 
 surprised by the appearance of an insect. Black flint, burnt to 
 redness and reduced to powder, was mixed with carbonate of 
 potash, and exposed to a strong heat for fifteen minutes ; and the 
 mixture was poured into a black-lead crucible in an air furnace. 
 It was reduced to powder while warm, mixed with boiling 
 water, kept boiling for some minutes, and then hydrochloric 
 acid was added to supersaturation. After being exposed to vol- 
 taic action for twenty-six days, a perfect insect of the Acari 
 tribe made its appearance, and in the course of a few weeks 
 about a hundred more. The experiment was repeated in other 
 chemical fluids with the like results ; and Mr. Weeks of Sand- 
 wich afterwards produced the Acari inferrocyanerret of potas- 
 sium. The Acarus of Mr. Crosse was found to contribute a new 
 species of that genus, nearly approaching the Acari found in 
 cheese and flour, or more nearly, Hermann's Acarus dimidiatus. 
 
 This discovery occasioned great excitement. The possibility 
 was denied, though Mr. Faraday is said to have stated in the 
 same year that he had seen similar appearances in his own elec- 
 trical experiments. Mr. Crosse was now accused of impiety and 
 aiming at creation, to which attacks he thus replied : 
 
 As to the appearance of the acari under long-continued electrical 
 action, I have never in thought, word, or deed given any one a right 
 to suppose that I considered them as a creation, or even as a formation, 
 from inorganic matter. To create is to form a something out of a no- 
 thing. To annihilate is to reduce that something to a nothing. Both of 
 these, of course, can only be the attributes of the Almighty. In fact, I 
 can assure you most sacredly that I have never dreamed of any theory 
 sufficient to account for their appearance. I confess that I was not a 
 little surprised, and am so still, and quite as much as I was when the 
 acari made their first appearance. Again, I have never claimed any 
 merit as attached to these experiments. It was a matter of chance ; I 
 was looking for silicious formations, and animal matter appeared in- 
 stead. 
 
 These Acari, if removed from their birthplace, lived and pro- 
 pagated; but uniformly died on the first recurrence of frost, and 
 were entirely destroyed if they fell back into the fluid whence 
 they arose. 
 
 One of Mr. Crosse's visitors thus describes the vast electrical 
 room at Fyne Court: 
 
 Here was an immense number of jars and gallipots, containing fluids 
 on which electricity was operating for the production of crystals. But 
 you are startled in the midst of your observations by the smart crackling 
 sound that attends the passage of the electrical spark ; you hear also 
 
 experiments and apparatus ; a report of which being communicated to the 
 Brighton Herald, was quoted in the Literary Gazette, and thence copied generally 
 into the newspapers of the day. 
 
Curiosities of Science. 219 
 
 the rumbling of distant thunder. The rain is already plashing in great 
 drops against the glass, and the sound of the passing sparks continues 
 to startle your ear ; you see at the window a huge brass conductor, with 
 a discharging rod near it passing into the floor, and from the one knob to 
 the other sparks are leaping with increasing rapidity and noise, every 
 one of which would kill twenty men at one blow, if they were linked to- 
 gether hand in hand and the spark sent through the circle. From this 
 conductor wires pass off without the window, and the electi'ic fluid is 
 conducted harmlessly away. Mr. Crosse approached the instrument as 
 boldly as if the flowing stream of fire were a harmless spark. Armed 
 with his insulated rod, he sent it into his batteries : having charged 
 them, he showed how wire was melted, dissipated in a moment, by its 
 passage ; how metals silver, gold, and tin were inflamed and burnt 
 like paper, only with most brilliant hues. He showed you a mimic au- 
 rora and a falling-star, and so proved to you the cause of those beauti- 
 ful phenomena. 
 
 Mr. Crosse appears to have produced in all "about 200 varie- 
 ties of minerals, exactly resembling in all respects similar ones 
 found in nature." He tried also a new plan of extracting gold 
 from its ores by an electrical process, which succeeded, but was 
 too expensive for common use. He was in the habit of saying 
 that he could, like Archimedes, move the world "if he were 
 able to construct a battery at once cheap, powerful, and dura- 
 ble." His process of extracting metals from their ores has been 
 patented. Among his other useful applications of electricity 
 are the purifying by its means of brackish or sea water, and the 
 improving bad wine and brandy. He agreed with Mr. Quekett 
 in thinking that it is by electrical action that silica and other 
 mineral substances are carried into and assimilated by plants. 
 Negative electricity Mr. Crosse found favourable to no plants 
 except fungi ; and positive electricity he ascertained to be in- 
 jurious to fungi, but favourable to every thing else. 
 
 Mr. Crosse died in 1855. His widow has published a very 
 interesting volume of Memorials of the ingenious experimenter, 
 from which we select the following : 
 
 On one occasion Mr. Crosse kept a pair of soles under the electric 
 action for three months ; and at the end of that time they were sent to 
 a friend, whose domestics knew nothing of the experiment. Before the 
 cook dressed them, her master asked her whether she thought they were 
 fresh, as he had some doubts. She replied that she was sure they were 
 fresh ; indeed, she said she could swear that they were alive yesterday ! 
 When served at table they appeared like ordinary fish ; but when the 
 family attempted to eat them, they were found to be perfectly tasteless 
 the electric action had taken away all the essential oil, leaving the 
 fish unfit for food. However, the process is exceedingly useful for keep- 
 ing fish, meat, &c. fresh and good for ten days or a fortnight. I have 
 never heard a satisfactory explanation of the cause of the antiseptic 
 power communicated to water by the passage of the electric current. 
 Whether ozone has not something to do with it, may be a question. 
 The same effect is produced whichever two dissimilar metals are used. 
 
Things not generally Known. 
 
 2Cfje Electric 
 
 ANTICIPATIONS OF THE ELECTEIC TELEGEAPH. 
 
 THE great secret of ubiquity, or at least of instantaneous trans- 
 mission, has ever exercised the ingenuity of mankind in various 
 romantic myths ; and the discovery of certain properties of the 
 loadstone gave a new direction to these fancies. 
 
 The earliest anticipation of the Electric Telegraph of this 
 purely fabulous character forms the subject of one of the Pro- 
 lusiones Academiccs of the learned Italian Jesuit Strada, first 
 published at Rome in the year 1617. Of this poem a free 
 translation appeared in 1750. Strada's fancy was this : " There 
 is," he supposes, "a species of loadstone which possesses such 
 virtue, that if two needles be touched with it, and then bal- 
 anced on separate pivots, and the one be turned in a parti- 
 cular direction, the other will sympathetically move parallel 
 to it. He then directs each of these needles to be poised and 
 mounted parallel on a dial having the letters of the alphabet 
 arranged round it. Accordingly, if one person has one of the 
 dials, and another the other, by a little pre-arrangement as to 
 details a correspondence can be maintained between them at 
 any distance by simply pointing the needles to the letters of 
 the required words. Strada, in his poetical reverie, dreamt that 
 some such sympathy might one day be found to hold up the 
 Magnesian Stone." 
 
 Strada's conceit seems to have made a profound impression 
 on the master-minds of the day. His poem is quoted in many 
 works of the seventeenth and eighteenth centuries ; and Bishop 
 Wilkins, in his book on Cryptology, is strangely afraid lest 
 his readers should mistake Strada's fancy for fact. Wilkins 
 writes : " This invention is altogether imaginary, having no 
 foundation in any real experiment. You may see it frequently 
 confuted in those that treat concerning rnagnetical virtues." 
 
 Again, Addison, in the 241st No. of the Spectator, 1712, 
 describes Strada's "Chimerical correspondence," and adds that, 
 " if ever this invention should be revived or put in practice," 
 he " would propose that upon the lover's dial -plate there 
 should be written not only the four-and-twenty letters, but se- 
 veral entire words which have always a place in passionate epis- 
 tles, as flames, darts, die, language, absence, Cupid, heart, eyes, 
 being, drown, and the like. This would very much abridge the 
 lover's pains in this way of writing a letter, as it would enable 
 
Curiosities of Science. 
 
 him to express the most useful and significant words with a 
 single touch of the needle." 
 
 After Strada and his commentators comes Henry Van Etten, 
 who shows how " Claude, being at Paris, and John at Rome, 
 might converse together, if each had a needle touched by a 
 stone of such virtue that as one moved itself at Paris the other 
 should be moved at Rome :" he adds, " it is a fine invention, 
 but I do not think there is a magnet in the world which has 
 such virtue ; besides, it is inexpedient, for treasons would be 
 too frequent and too much protected. (Recreations Mathema- 
 tiques: see 5th edition, Paris, 1660, p. 158.) Sir Thomas Browne 
 refers to this " conceit" as " excellent, and, if the effect would 
 follow, somewhat divine ;" but he tried the two needles touched 
 with the same loadstone, and placed in two circles of letters, 
 " one friend keeping one and another the other, and agreeing 
 upon an hour when they will communicate, " and found the tra- 
 dition a failure that, "at what distance of place soever, when 
 one needle shall be removed unto any letter, the other, by a 
 wonderful sympathy, will move unto the same." (See Vulgar 
 Errors, book ii. ch. iii.) 
 
 Glanvill's Vanity of Dogmatizing, a work published in 1661, 
 however, contains the most remarkable allusion to the prevail- 
 ing telegraphic fancy. Glanvill was an enthusiast, and he clearly 
 predicts the discovery and general adoption of the electric tele- 
 graph. "To confer," he says, "at the distance of the Indies 
 by sympathetic conveyance may be as usual to future times as 
 to us in a literary correspondence." By the word " sympathe- 
 tic" he evidently intended to convey magnetic agency ; for he 
 subsequently treats of "conference at a distance by impreg- 
 nated needles," and describes the device substantially as it is 
 given by Sir Thomas Browne, adding, that though it did not 
 then answer, " by some other such way of magnetic efficiency 
 it may hereafter with success be attempted, when magical his- 
 tory shall be enlarged by riper inspection ; and 'tis not unlikely 
 but that present discoveries might be improved to the perform- 
 ance." This may be said to close the most speculative or my- 
 thical period in reference to the subject of electro-telegraphy. 
 
 Electricians now began to be sedulous in their experiments 
 upon the new force by friction, then the only known method 
 of generating electricity. In 1729, Stephen Gray, a pensioner 
 of the Charter-house, contrived a method of making electrical 
 signals through a wire 765 feet long ; yet this most important 
 experiment did not excite much attention. Next Dr. Watson, 
 of the Royal Society, experimented on the possibility of trans- 
 mitting electricity through a large circuit from the simple fact of 
 Le Mourner's account of his feeling the stroke of the electrified 
 fires through two of the basins of the Tuileries (which occupy 
 
Things not generally Known 
 
 nearly an acre), by means of an iron chain lying upon the ground 
 and stretched round half their circumference. In 1 745, Dr. Wat- 
 son, assisted by several members of the Royal Society, made a 
 series of experiments to ascertain how far electricity could be 
 conveyed by means of conductors. " They caused the shock to 
 pass across the Thames at Westminster Bridge, the circuit being 
 completed by making use of the river for one part of the chain 
 of communication. One end of the wire communicated with 
 the coating of a charged phial, the other being held by the ob- 
 server, who in his other hand held an iron rod which he dipped 
 into the river. On the opposite side of the river stood a gentle- 
 man, who likewise dipped an iron rod in the river with one 
 hand, and in the other held a wire the extremity of which 
 might be brought into contact with the wire of the phial. Upon 
 making the discharge, the shock was felt simultaneously by 
 both the observers." (Priestley's History of Electricity.} Sub- 
 sequently the same parties made experiments near Shooter's 
 Hill, when the wires formed a circuit of four miles, and con- 
 veyed the shock with equal facility, "a distance which without 
 trial," they observed, " was too great to be credited."* These 
 experiments in 1747 established two great principles : 1, that 
 the electric current is transmissible along nearly two miles and 
 a half of iron wire ; 2, that the electric current may be completed 
 by burying the poles in the earth at the above distance. 
 
 In the following year, 1748, Benjamin Franklin performed 
 his celebrated experiments on the banks of the Schuylkill, near 
 Philadelphia ; which being interrupted by the hot weather, they 
 were concluded by a picnic, when spirits were fired by an elec- 
 tric spark sent through a wire in the river, and a turkey was 
 killed by the electric shock, and roasted by the electric jack 
 before a fire kindled by the electrified bottle. 
 
 In the year 1753, there appeared in the Scots' Magazine, vol. 
 xv., definite proposals for the construction' of an electric tele- 
 graph, requiring as many conducting wires as there are letters 
 in the alphabet ; it was also proposed to converse by chimes, 
 by substituting bells for the balls. A similar system of tele- 
 graphing was next invented by Joseph Bozolus, a Jesuit, at 
 Rome ; and next by the great Italian electrician Tiberius Ca- 
 vallo, in his treatise on Electricity. 
 
 In 1787, Arthur Young, when travelling in France, saw a 
 model working telegraph by M. Lomond : " You write two or 
 three words on a paper," says Young; "he takes it with him 
 into a room, and turns a machine enclosed in a cylindrical case, 
 
 * These experiments were performed at the expense of the Royal Society, and 
 cost 10^. 5s. 6d. In the Paper detailing the experiments, printed in the 45th 
 volume of the Philosophical Transactions, occurs the first mention of Dr. Franklin's 
 name, and of his theory of positive and negative electricity. Weld's Hist. Eoya.1 
 Soc. vol. i. p. 467. 
 
Curiosities of Science. 
 
 at the top of which is an electrometer a small fine pith-ball ; 
 a wire connects with a similar cylinder and electrometer in a 
 distant apartment; and his wife, by remarking the correspond- 
 ing motions of the ball, writes down the words they indicate : 
 from which it appears that he has formed an alphabet of mo- 
 tions. As the length of the wire makes no difference in the 
 effect, a correspondence might be carried on at any distance. 
 Whatever the use may be, the invention is beautiful." 
 
 We now reach a new epoch in the scientific period the dis- 
 covery of the Voltaic Pile. In 1794, according to Voiat's Maga- 
 zine, Reizen made use of the electric spark for the telegraph ; 
 and in 1798 Dr. Salva of Madrid constructed a similar tele- 
 graph, which the Prince of Peace subsequently exhibited to the 
 King of Spain with great success. 
 
 In 1809, Soemmering exhibited a telegraphic apparatus 
 worked by galvanism before the Academy of Sciences at Munich, 
 in which the mode of signalling consisted in the development 
 of gas-bubbles from the decomposition of water placed in a 
 series of glass tubes, each of which denoted a letter of the al- 
 phabet. In 1813, Mr. Sharpe, of Doe Hill near Alfreton, de- 
 vised a voltaic-electric telegraph, which he exhibited to the 
 Lords of the Admiralty, who spoke approvingly of it, but de- 
 clined to carry it into effect. In the following year, Soemmer- 
 ing exhibited a voltaic-electric telegraph of his own construction, 
 which, however, was open to the objection of there being as 
 many wires as signs or letters of the alphabet. 
 
 The next invention is of much greater importance. Upon 
 the suggestion of Cavallo, already referred to, Francis Ronalds 
 constructed a perfect electric telegraph, employing frictional 
 electricity notwithstanding Volta's discoveries had been known 
 in England for sixteen years. This telegraph was exhibited at 
 Hammersmith in 1816 :* it consisted of a single insulated wire, 
 the indication being by pith-balls in front of a dial. When the 
 wire was charged, the balls were divergent, but collapsed when 
 the wire was discharged ; at the same time were employed two 
 clocks, with lettered discs for the signals. " If, as Paley asserts 
 (and Coleridge denies), * he alone discovers who proves,' Ro- 
 nalds is entitled to the appellation of the first discoverer of an 
 efficient electric telegraph. " (Saturday Review, No. 147 t) Never- 
 theless the Government of the day refused to avail itself of this 
 admirable contrivance. 
 
 In 1819, Oersted made his great discovery of the deflection, 
 by a current of electricity, of a magnetic needle at right angles 
 
 * In this year Andrew Crosse said : "I prophesy that by means of the electric 
 agency we shall be enabled to communicate our thoughts instantaneously with 
 the uttermost parts of the earth." 
 
 f To which paper the writer is indebted for many of these details. 
 
224* Things not generally Known. 
 
 to such current. Dr. Hamel of St. Petersburg states that 
 Baron Schilling was the first to apply Oersted's discovery to 
 telegraphy ; Ampere had previously suggested it, but his plan 
 was very complicated, and Dr. Hamel maintains that Schil- 
 ling first realised the idea by actually producing an electro- 
 magnetic telegraph simpler in construction than that which 
 Ampere had imagined. In 1836, Professor Muncke of Heidel- 
 berg, who had inspected Schilling's telegraphic apparatus, ex- 
 plained the same to William Fothergill Cooke, who in the 
 following year returned to England, and subsequently, with 
 Professor Wheatstone, laboured simultaneously for the intro- 
 duction of the electro -magnetic telegraph upon the English 
 railways; the first patent for which was taken out in the joint 
 names of these two gentlemen. 
 
 In 1844, Professor Wheatstone, with one of his telegraphs, 
 formed a communication between King's College and the lofty 
 shot-tower on the opposite bank of the Thames : the wire was 
 laid along the parapets of the terrace of Somerset House and 
 Waterloo Bridge, and thence to the top of the tower, about 150 
 feet high, where a telegraph was placed ; the wire then de- 
 scended, and a plate of zinc attached to its extremity was 
 plunged into the mud of the river, whilst a similar plate at- 
 tached to the extremity at the north side was immersed in the 
 water. The circuit was thus completed by the entire breadth 
 of the Thames, and the telegraph acted as well as if the circuit 
 were entirely metallic. 
 
 Shortly after this experiment, Professor Wheatstone and 
 Mr. Cooke laid down the first working electric telegraph on the 
 Great Western Railway, from Paddington to Slough. 
 
 ELECTRIC GIRDLE FOR THE EARTH. 
 
 One of our most profound electricians is reported to have 
 exclaimed: " Give me but an unlimited length of wire, with a 
 small battery, and I will girdle the universe with a sentence in 
 forty minutes." Yet this is no vain boast ; for so rapid is the 
 transition of the electric current along the line of the telegraph 
 wire, that, supposing it were possible to carry the wires eight 
 times round the earth, the transit would occupy but one second 
 of time ! 
 
 CONSUMPTION OF THE ELECTRIC TELEGRAPH. 
 
 It is singular to see how this telegraphic agency is mea- 
 sured by the chemical consumption of zinc and acid. Mr. Jones 
 (who has written a work upon the Electric Telegraphs of Ame- 
 rica) estimates that to work 12,000 miles of telegraph about 
 3000 zinc cups are used to hold the acid : these weigh about 
 9000 Ibs. , and they undergo decomposition by the galvanic 
 
Curiosities of Science. 
 
 action in about six months, so that 18,000 Ibs. of zinc are con- 
 sumed in a year. There are also about 3600 porcelain cups to 
 contain nitric acid ; it requires 450 Ibs. of acid to charge them 
 once, and the charge is renewed every fortnight, making about 
 12,000 Ibs. of nitric acid in a year. 
 
 TIME LOST IN ELECTKIC MESSAGES. 
 
 Although it may require an hour, or two or three hours, to 
 transmit a telegraphic message to a distant city, yet it is the 
 mechanical adjustment by the sender and receiver which really 
 absorbs this time ; the actual transit is practically instanta- 
 neous, and so it would be from here to the antipodes, so far as 
 the current itself is concerned. 
 
 THE ELECTKIC TELEGRAPH IN ASTEONOMY AND THE 
 DETERMINATION OF LONGITUDE. 
 
 The Electric Telegraph has become an instrument in the 
 hands of the astronomer for determining the difference of lon- 
 gitude between two observatories. Thus in 1854 the difference 
 of longitude between London and Paris was determined within 
 a limit of error which amounted barely to a quarter of a second. 
 The sudden disturbances of the magnetic needle, when freely 
 suspended, which seem to take place simultaneously over whole 
 continents, if not over the whole globe, from some unexplained 
 cause, are pointed out as means by which the differences of lon- 
 gitude between the magnetic observatories may possibly be deter- 
 mined with greater precision than by any yet known method. 
 
 So long ago as 1839 Professor Morse suggested some expe- 
 riments for the determination of Longitudes ; and in June 
 1844 the difference of longitude between Washington and Bal- 
 timore was determined by electric means under his direction. 
 Two persons were stationed at these two towns, with clocks 
 carefully adjusted to the respective spots ; and a telegraphic 
 signal gave the means of comparing the two clocks at a given 
 instant. In 1 847 the relative longitudes of New York, Phila- 
 delphia, and Washington were determined by means of the 
 electric telegraph by Messrs. Keith, Walker, and Loomis. 
 
 NON-INTERFERENCE OF GALVANIC WAVES ON THE SAME WIRE. 
 
 One of the most remarkable facts in the economy of the 
 telegraph is, that the line, when connected with a battery in 
 action, propagates the hydro-galvanic waves in either direction 
 without interference. As several successive syllables of sound 
 may set out in succession from the same place, and be on their 
 way at the same time, to a listener at a distance, so also, where 
 the telegraph-line is long enough, several waves may be on 
 their way from the signal station before the first one reaches 
 
 Q 
 
226 Things not generally Known. 
 
 the receiving station ; two persons at a distance may pro- 
 nounce several syllables at the same time, and each hear those 
 emitted by the other. So, on a telegraph-line of two or three 
 thousand miles in length in the air, and the same in the 
 ground, two operators may at the same instant commence a 
 series of several dots and lines, and each receive the other's 
 writings, though the waves have crossed each other on the way. 
 
 EFFECT OF LIGHTNING UPON THE ELECTKIC TELEGRAPH. 
 
 In the storm of Sunday April 2, 1848, the lightning had a 
 very considerable effect on the wires of the electric telegraph, 
 particularly on the line of railway eastward from Manchester 
 to Normanton. Not only were the needles greatly deflected, 
 and their power of answering to the handles considerably weak- 
 ened, but those at the Normanton station were found to have 
 had their poles reversed by some action of the electric fluid in 
 the atmosphere. The damage, however, was soon repaired, and 
 the needles again put in good working order. 
 
 ELECTRO-TELEGRAPHIC MESSAGE TO THE STARS. 
 
 The electric fluid travels at the mean rate of 20,000 miles 
 in a second under ordinary circumstances ; therefore, if it were 
 possible to establish a telegraphic communication with the star 
 61 Cygni, it would require ninety years to send a message there. 
 
 Professor Henderson and Mr. Maclear have fully confirmed 
 the annual parallax of a Centauri to amount to a second of arc, 
 which gives about twenty billions of miles as its distance from 
 our system ; a ray of light would arrive from a Centauri to us in 
 little more than three years, and a telegraphic despatch would 
 arrive there in thirty years. 
 
 THE ATLANTIC TELEGRAPH. 
 
 The telegraphic communication between England and the 
 United States is so grand a conception, that it would be impos- 
 sible to detail its scientific and mechanical relations within the 
 limits of the present work. All that we shall attempt, there- 
 fore, will be to glance at a few of the leading operations. 
 
 In the experiments made before the Atlantic Telegraph was 
 finally decided on, 2000 miles of subterranean and submarine 
 telegraphic wires, ramifying through England and Ireland and 
 under the waters of the Irish Sea, were specially connected for 
 the purpose ; and through this distance of 2000 miles 250 dis- 
 tinct signals were recorded and printed in one minute. 
 
 First, as to the Cable. In the ordinary wires by the side of 
 a railway the electric current travels on with the speed of light- 
 ning uninterrupted by the speed of lightning ; but when a 
 wire is encased in gutta-percha, or any similar covering, for sub- 
 
Curiosities of Science. 
 
 mersion in the sea, new forces come into play. The electric ex- 
 citement of the wire acts by induction, through the envelope, 
 upon the particles of water in contact with that envelope, and 
 calls up an electric force of an opposite kind. There are two 
 forces, in fact, pulling against each other through the gutta- 
 percha as a neutral medium, that is, the electricity in the 
 wire, and the opposite electricity in the film of water imme- 
 diately surrounding the cable ; and to that extent the power of 
 the current in the enclosed wire is weakened. A submarine 
 cable, when in the water, is virtually a lengthened-out Leyden 
 jar ; it transmits signals while being charged and discharged, 
 instead of merely allowing a stream to flow evenly along it : it 
 is a bottle for holding electricity rather than a pipe for carrying 
 it ; and this has to be filled for every time of using. The wire 
 being carried underground, or through the water, the speed be- 
 comes quite measurable, say a thousand miles in a second, in- 
 stead of two hundred thousand, owing to the retardation by in- 
 duced or retrograde currents. The energy of the currents and 
 the quality of the wire also affect the speed. Until lately it 
 was supposed that the wire acts only as a conductor of electri- 
 city, and that a long wire must produce a weaker effect than a 
 short one, on account of the consequent attenuation of the elec- 
 trical influence ; but it is now known that, the cable being a re- 
 servoir as well as a conductor, its electrical supply is increased 
 in proportion to its length. 
 
 The electro-magnetic current is employed, since it possesses 
 a treble velocity of transmission, and realises consequently a 
 threefold working speed as compared with simple voltaic electri- 
 city. Mr. Wildraaii Whitehouse has determined by his inge- 
 nious apparatus that the speed of the voltaic current might be 
 raised under special circumstances to 1800 miles per second ; 
 but that of the induced current, or the electro-magnetic, might 
 be augmented to 6000 miles per second. 
 
 Next as to a Quantity Battery employed in these investiga- 
 tions. To effect a charge, and transmit a current through some 
 thousand miles of the Atlantic Cable, Mr. Whitehouse had a 
 piece of apparatus prepared consisting of twenty -five pairs of 
 zinc and silver plates about the 20th part of a square inch 
 large, and the pairs so arranged that they would hold a drop of 
 acidulated water or brine between them. On charging this Lil- 
 liputian battery by dipping the plates in salt and water, mes- 
 sages were sent from it through a thousand miles of cable with 
 the utmost ease ; and not only so, pair after pair was dropped 
 out from the series, the messages being still sent on with equal 
 facility, until at last only a single pair, charged by one single 
 drop of liquid, was used. Strange to say, with this single pair 
 and single drop distinct signals were effected through the thou- 
 
Things not generally Known. 
 
 sand miles of the cable ! Each signal was registered at the end 
 of the cable in less than three seconds of time. 
 
 The entire length of wire, iron and copper, spun into the 
 cable amounts to 332,500 miles, a length sufficient to engirdle 
 the earth thirteen times. The cable weighs from 19 cwt. to a 
 ton per mile, and will bear a strain of 5 tons. 
 
 The Perpetual Maintenance Battery, for working the cable at 
 the bottom of the sea, consists of large plates of platinated sil- 
 ver and amalgamated zinc, mounted in cells of gutta-percha. 
 The zinc plates in each cell rest upon a longitudinal bar at the 
 bottom, and the silver plates hang upon a similar bar at the top 
 of the cell ; so that there is virtually but a single stretch of 
 silver and a single stretch of zinc in operation. Each of the 
 ten cells contains 2000 square inches of acting surface ; and 
 the combination is so powerful, that when the broad strips of 
 copper-plate which form the polar extensions are brought into 
 contact or separated, brilliant flashes are produced, accompa- 
 nied by a loud crackling sound. The points of large pliers are 
 made red-hot in five seconds when placed between them, and 
 even screws burn with vivid scintillation. The cost of main- 
 taining this magnificent ten-celled Titan battery at work does 
 not exceed a shilling per hour. The voltaic current generated 
 in this battery is not, however, the electric stream to be sent 
 across the Atlantic, but is only the primary power used to call 
 up and stimulate the energy of a more speedy traveller by a 
 complicated apparatus of " Double Induction Coils." Nor is 
 the transmission-current generated in the inner wire of the 
 double induction coil, and which becomes weakened when it 
 has passed through 1800 or 1900 miles, set to work to print or 
 record the signals transmitted. This weakened current merely 
 opens and closes the outlet of a fresh battery, which is to do 
 the printing labour. This relay-instrument (as it is called), 
 which consists of a temporary and permanent magnet, is so sen- 
 sitive an apparatus, that it may be put in action by a fragment 
 of zinc and a sixpence pressed against the tongue. 
 
 The attempts to lay the cable in August 1 857 failed through 
 stretching it so tightly that it snapped and went to the bottom, 
 at a depth of 12,000 feet, forty times the height of St. Paul's. 
 
 This great work was resumed in August 1858 ; and on the 
 5th the first signals were received through two thousand and 
 fifty miles of the Atlantic Cable. And it is worthy of remark, 
 that just 111 years previously, on the 5th of August 1747, Dr. 
 Watson astonished the scientific world by practically proving 
 that the electric current could be transmitted through a wire 
 hardly two miles and a half long* 
 
 * These illustrations have been in the main selected and abridged from papers 
 in the Companion to the Almanac, 1858, and the Penny Cyclopaedia, 2d supp. 
 
Curiosities of Science. 
 
 JttteceHattea. 
 
 HOW MAKINE CHRONOMETERS ARE RATED AT THE ROYAL 
 OBSERVATORY, GREENWICH. 
 
 THE determination of the Longitude at Sea requires simply 
 accurate instruments for the measurement of the positions of 
 the heavenly bodies, and one or other of the two following, 
 either perfectly correct watches or chronometers, as they are 
 now called or perfectly accurate tables of the lunar motions. 
 
 So early as 1696 a report was spread among the members of 
 the Royal Society that Sir Isaac Newton was occupied with the 
 problem of finding the longitude at sea ; but the rumour having 
 no foundation, he requested Halley to acquaint the members 
 "that he was not about it."* (Sir David Brewster' s Life of 
 Newton. ) 
 
 In 1714 the legislature of Queen Anne passed an Act offer- 
 ing a reward of 20,000. for the discovery of the longitude, the 
 problem being then very inaccurately solved for want of good 
 watches or lunar tables. About the year 1749, the attention 
 of the Royal Society was directed to the improvements effected 
 in the construction of watches by John Harrison, who received 
 for his inventions the Copley Medal. Thus encouraged, Har- 
 rison continued his labours with unwearied diligence, and 
 produced in 1758 a timekeeper which was sent for trial on a 
 voyage to Jamaica. After 161 days the error of the instru- 
 ment was only l m 5 s , and the maker received from the nation 
 5QOOL The Commissioners of the Board of Longitude subse- 
 quently required Harrison to construct under their inspection 
 chronometers of a similar nature, which were subjected to 
 trial in a voyage to Barbadoes, and performed with such accu- 
 racy, that, after having fully explained the principle of their 
 construction to the commissioners, they awarded him 10,000. 
 more ; at the same time Euler of Berlin and the heirs of Mayer 
 of Gottingen received each 30001. for their lunar tables. 
 
 * Newton was, however, much pestered with inquirers ; and a Correspondent 
 of the Gentleman's Magazine,, in 1784, relates that he once had a transient view of 
 a Ms. in Pope's handwriting, in which he read a verified anecdote relating to the 
 above period. Sir Isaac being often interrupted by ignorant pretenders to the 
 discovery of the longitude, ordered his porter to inquire of every stranger who 
 desired admission whether he came about the longitude, and to exclude such as 
 answered in the affirmative. Two lines in Pope's Ms., as the Correspondent re- 
 collects, ran thus : 
 
 " ' Is it about the longitude you come?' 
 The porter asks : ' Sir Isaac 's not at home.' " 
 
230 Things not generally Known. 
 
 The account of the trial of Harrison's watch is very interesting. In 
 April 1766, by desire of the Commissioners of the Board, the Lords of 
 the Admiralty delivered the watch into the custody of the Astronomer- 
 Royal, the Rev. Dr. Nevil Maskelyne. It was then placed at the Royal 
 Observatoiy at Greenwich, in a box having two different locks, fixed to 
 the floor or wainscot, with a plate of glass in the lid of the box, so that 
 it might be compared as often as convenient with the regulator and the 
 variation set down. The form observed by Mr. Harrison in winding up 
 the watch was exactly followed ; and an officer of Greenwich Hospital 
 attended every day, at a stated hour, to see the watch wound up, and 
 its comparison with the regulator entered. A key to one of the locks 
 was kept at the Hospital for the use of the officer, and the other re- 
 mained at the Observatory for the use of the Astronomer-Royal or his 
 assistant. 
 
 The watch was then tried in various positions till the beginning of 
 July ; and from thence to the end of February following in a horizontal 
 position with its face upwards. 
 
 The variation of the watch was then noted down, and a register was 
 kept of the barometer and thermometer; and the time of comparing 
 the same with the regulator was regularly kept, and attested by the 
 Astronomer- Royal or his assistant and such of the officers as witnessed 
 the winding up and comparison of the watch. 
 
 Under these conditions Harrison's watch was received by the Astro- 
 nomer-Royal at the Admiralty on May 5, 1766, in the presence of Philip 
 Stephens, Esq., Secretary of the Admiralty ; Captain Baillie, of the Royal 
 Hospital, Greenwich ; and Mr. Kendal the watchmaker, who accom- 
 panied the Astronomer-Royal to Greenwich, and saw the watch started 
 and locked up in the box provided for it. The watch was then com- 
 pared with the transit clock daily, and wound up in the presence of the 
 officer of Greenwich Hospital. From May 5 to May 17 the watch was 
 kept in a horizontal position with its face upwards ; from May 18 to 
 July 6 it was tried first inclined at an angle of 20 to the horizon, with 
 the face upwards, and the hours 12, 6, 3, and 9, highest successively ; 
 then in a vertical position, with the same hours highest in order ; lastly, 
 in a horizontal position with the face downwards. From July 16, 1766, 
 to March 4, 1767, it was always kept in a horizontal position with its 
 face upwards, lying upon the same cushion, and in the same box in 
 which Mr. Harrison had kept it in the voyage to Barbadoes. 
 
 From the observed transits of the sun over the meridian, according 
 to the time of the regulator of the Observatory, together with the at- 
 tested comparisons of Mr. Harrison's watch with the transit clock, the 
 watch was found too fast on several days as follows : 
 
 h. m. s. 
 
 1766. May 6 too fast 16'2 
 
 ,,17 03 51-8 
 
 July 6 
 Aug. 6 
 Sept. 17 
 Oct. 29 
 Dec. 10 
 1767. Jan. 21 
 March 4 
 
 14 14 
 
 2.3 58 4 
 
 32 15 6 
 
 42 20 9 
 
 54 468 
 
 1 28-6 
 1 11 23-0 
 
 From May 6, which was the day after the watch arrived at the Royal 
 Observatory, to March 4, 1767, there were six periods of six weeks each 
 in which the watch was tried in a horizontal position ; when the gaining 
 in these several periods was as follows : 
 
Curiosities of Science. 
 
 During the first 6 weeks it gained 13m 20", answering to 3 20' of longitude. 
 In the 2d period of 6\ 
 
 weeks (from Aug. 6 to L 8 17 24 
 
 Sept. 17) 
 In the 3d period (from") 10 ^ o QI 
 
 Sept. 17 to Oct. 29) ) " 
 In the 4th period (from ") 1 o 9 Q 
 
 Oct. 29 to Dec. 20) j " 12 26 
 In the 5th period (from\ K 40 1 OK 
 
 Dec. 20 to Jan. 21) J 
 In the 6th period (from \ in p, o 4 q 
 
 Jan. 21 to Mar. 4) / " 
 
 It was thence concluded that Mr. Harrison's watch could 
 not be depended upon to keep the longitude within a West- 
 India voyage of six weeks, nor to keep the longitude within 
 half a degree for more than a fortnight ; arid that it must be 
 kept in a place where the temperature was always some degrees 
 above freezing.* (However, Harrison's watch, which was made 
 by Mr. Kendal subsequently, succeeded so completely, that after 
 it had been round the world with Captain Cook, in the years 
 1772-1775, the second 10,000 was given to Harrison.) 
 
 In the Act of 12th Queen Anne, the comparison of chrono- 
 meters was not mentioned in reference to the Observatory duties ; 
 but after this time they became a serious charge upon the Ob- 
 servatory, which, it must be admitted, is by far the best place 
 to try chronometers : the excellence of the instruments, and the 
 frequent observations of the heavenly bodies over the meridian, 
 will always render the rate of going of the Observatory clock 
 better known than can be expected of the clock in most other 
 places. 
 
 After Mr. Harrison's watch was tried, some watches by Earn- 
 shaw, Mudge, and others, were rated and examined by the As- 
 tronomer-Royal. 
 
 At the Royal Observatory, Greenwich, there are frequently 
 above 100 chronometers being rated, and there have been as 
 many as 170 at one time. They are rated daily by two ob- 
 servers, the process being as follows. At a certain time every 
 day two assistants in charge repair to the chronometer-room, 
 where is a time-piece set to true time ; one winds up each with 
 its own key, and the second follows after some little time and 
 verifies the fact that each is wound. One assistant then looks 
 at each watch in succession, counting the beats of the clock 
 whilst he compares the chronometer by the eye ; and in the 
 course of a few seconds he calls out the second shown by the 
 chronometer when the clock is at a whole minute. This num- 
 ber is entered in a book by the other assistant, and so on till 
 all the chronometers are compared. Then the assistants change 
 
 * In trying the merits of Harrison's chronometers. Dr. Maskelyne acquired 
 that knowledge of the wants of nautical astronomy which afterwards led to the 
 formation of the Nautical Almanac. 
 
232 
 
 Things not generally Known. 
 
 places, the second comparing and the first writing down. From 
 these daily comparisons the daily rates are deduced, by which 
 the goodness of the watch is determined. The errors are of 
 two classes that of general bad workmanship, and that of 
 over or under correction for temperature. In the room is an 
 apparatus in which the watch may be continually kept at tem- 
 peratures exceeding 100 by artificial heat ; and outside the 
 window of the room is an iron cage, in which they are subjected 
 to low temperatures. The very great care taken with all chro- 
 nometers sent to the Royal Observatory, as well as the perfect 
 impartiality of the examination which each receives, afford 
 encouragement to their manufacture, and are of the utmost 
 importance to the safety and perfection of navigation. 
 
 We have before us now the Report of the Astronomer- Royal 
 on the Rates of Chronometers in the year 1854, in which the 
 following are the successive weekly sums of the daily rates of 
 the first there mentioned : 
 
 Week ending sees. 
 
 Jan. 21, loss in the week 2-2 
 40 
 
 Feb. 4 
 11 
 18 
 25 
 
 Mar. 4 
 ., 11 
 ., 18 
 .. 25 
 
 Apr. 1 
 it 8 
 
 1-1 
 50 
 49 
 55 
 60 
 60 
 1-5 
 4-5 
 4-0 
 1-5 
 
 Week ending sees. 
 
 Apr. 22, gain in the week 26 
 29, loss in the week 1-4 
 May 6 , 2-1 
 
 18 
 
 20 
 27 
 
 June 3 
 10 
 17 
 24 
 
 July 1 
 8 
 
 3-0 
 51 
 3-3 
 2-8 
 1-8 
 2-0 
 3-0 
 2-5 
 1-2 
 
 15, gain in the week 4 
 
 Till February 4 the watch was exposed to the external air 
 outside a north window ; from February 5 to March 4 it was 
 placed in the chamber of a stove heated by gas to a moderate 
 temperature ; and from April 29 to May 20 it was placed in the 
 chamber when heated to a high temperature. 
 
 The advance in making chronometers since Harrison's cele- 
 brated watch was tried at the Royal Observatory, more than 
 ninety years since, may be judged by comparing its rates with 
 those above. 
 
 GEOMETEY OF SHELLS. 
 
 There is a mechanical uniformity observable in the descrip- 
 tion of shells of the same species which at once suggests the 
 probability that the generating figure of each increases, and 
 that the spiral chamber of each expands itself, according to some 
 simple geometrical law common to all. To the determination 
 of this law the operculum lends itself, in certain classes of 
 shells, with remarkable facility. Continually enlarged by the 
 animal, as the construction of its shell advances so as to fill up 
 
Curiosities of Science. 
 
 its mouth, the operculum measures the progressive widening of 
 the spiral chamber by the progressive stages of its growth. 
 
 ******* 
 
 The animal, as he advances in the construction of his shell, 
 increases continually his operculum, so as to adjust it to his 
 mouth. He increases it, however, not by additions made at the 
 same time all round its margin, but by additions made only on 
 one side of it at once. One edge of the operculum thus re- 
 mains unaltered as it is advanced into each new position, and 
 placed in a newly-formed section of the chamber similar to the 
 last but greater than it. 
 
 That the same edge which fitted a portion of the first less 
 section should be capable of adjustment so as to fit a portion 
 of the next similar but greater section, supposes a geometri- 
 cal provision in the curved form of the chamber of great com- 
 plication and difficulty. But God hath bestowed upon this 
 humble architect the practical skill of the learned geometri- 
 cian ; and he makes this provision with admirable precision in 
 that curvature of the logarithmic spiral which he gives to the 
 section of the shell. This curvature obtaining, he has only 
 to turn his operculum slightly round in its own place, as he 
 advances it into each newly-formed portion of his chamber, to 
 adapt one margin of it to a new and larger surface and a dif- 
 ferent curvature, leaving the space to be filled up by increasing 
 the operculum wholly on the outer margin. 
 
 ******* 
 
 Why the Mollusks, who inhabit turbinated and discoid shells, 
 should, in the progressive increase of their spiral dwellings, af- 
 fect the peculiar law of the logarithmic spiral, is easily to be 
 understood. Providence has subjected the instinct which 
 shapes out each to a rigid uniformity of operation. Professor 
 Mostly : Philos. Trans. 1838. 
 
 HYDRAULIC THEORY OF SHELLS. 
 
 How beautifully is the wisdom of God developed in shaping 
 out and moulding shells ! and especially in the particular value 
 of the constant angle which the spiral of each species of shell 
 affects, a value connected by a necessary relation with the 
 economy of the material of each, and with its stability and 
 the conditions of its buoyancy. Thus the shell of the Nautilus 
 PompiLius has, hydrostatically, an A-statical surface. If placed 
 with any portion of its surface upon the water, it will imme- 
 diately turn over towards its smaller end, and rest only on its 
 mouth. Those conversant with the theory of floating bodies 
 will recognise in this an interesting property. Ibid. 
 
Things not generally Known. 
 
 SEKVICES OF SEA-SHELLS AJSD ANIMALCULES. 
 
 Dr. Maury is disposed to regard these beings as having much 
 to do in maintaining the harmonies of creation, and the prin- 
 ciples of the most admirable compensation in the system of 
 oceanic circulation. "We may even regard them as regula- 
 tors, to some extent, of climates in parts of the earth far re- 
 moved from their presence. There is something suggestive 
 both of the grand and the beautiful in the idea that while the 
 insects of the sea are building up their coral islands in the per- 
 petual summer of the tropics, they are also engaged in dispens- 
 ing warmth to distant parts of the earth, and in mitigating the 
 severe cold of the polar winter." 
 
 DEPTH OF THE PKIMEVAL SEAS. 
 
 Professor Forbes, in a communication to the Royal Society, 
 states that not only the colour of the shells of existing mollusks 
 ceases to be strongly marked at considerable depths, but also 
 that well-defined patterns are, with very few and slight excep- 
 tions, presented only by testacea inhabiting the littoral, circum- 
 littoral, and median zones. In the Mediterranean, only one in 
 eighteen of the shells taken from below 100 fathoms exhibit 
 any markings of colour, and even the few that do so are ques- 
 tionable inhabitants of those depths. Between 30 and 35 fa- 
 thoms, the proportion of marked to plain shells is rather less 
 than one in three ; and between the margin and two fathoms 
 the striped or mottled species exceed one-half of the total num- 
 ber. In our own seas, Professor Forbes observes that testacea 
 taken from below ] 00 fathoms, even when they are individuals 
 of species vividly striped or banded in shallower zones, are quite 
 white or colourless. At between 60 and 80 fathoms, striping 
 and banding are rarely presented by our shells, especially in the 
 northern provinces ; from 50 fathoms, shallow bands, colours, 
 and patterns, are well marked. The relation of these arrange- 
 ments of colour to the degree of light penetrating the different zones 
 of depth is a subject well worthy of minute inquiry. 
 
 NATURAL WATER-PURIFIERS. 
 
 Mr. Warrington kept for a whole year twelve gallons of water 
 in a state of admirably balanced purity by the following beauti- 
 ful action : 
 
 In the tank, or aquarium, were two gold fish, six water-snails, and 
 two or three specimens of that elegant aquatic plant Valisperia spora- 
 lis, which, before the introduction of the water-snails, by its decayed 
 leaves caused a growth of slimy mucus, and made the water turbid and 
 likely to destroy both plants and fish. But under the improved ar- 
 rangement the slime, as fast as it was engendered, was consumed by 
 the water- snails, which reproduced it in the shape of young snails, which 
 
Curiosities of Science. 235 
 
 furnished a succulent food to the fish. Meanwhile the' Valisperia plants 
 absorbed the carbonic acid exhaled by the respiration of their compa- 
 nions, fixing the carbon in their growing stems and luxuriant blossoms, 
 and refreshing the oxygen (during sunshine in visible little streams) for 
 the respiration of the snails and the fish. The spectacle of perfect equi- 
 librium thus simply maintained between animal, vegetable, and inor- 
 ganic activity, was strikingly beautiful ; and such means might possibly 
 hereafter be made available on a large scale for keeping tanked water 
 sweet and clean. Quarterly Preview, 1850. 
 
 HOW TO IMITATE SEA-WATEE. 
 
 The demand for Sea-water to supply the Marine Aquarium 
 now to be seen in so many houses induced Mr. Gosse to at- 
 tempt the manufacture of Sea-water, more especially as the 
 constituents are well known. He accordingly took Scheveit- 
 zer's analysis of Sea- water for his guide. In one thousand 
 grains of sea-water taken off Brighton, it gave : water, 964*744; 
 chloride of sodium, 27*059 ; chloride of magnesium, 3*666 ; 
 chloride of potassium, 9*755 ; bromide of magnesium, 0'29 ; 
 sulphate of magnesia, 2*295 ; sulphate of lime, 1*407 ; carbon- 
 ate of lime, 0*033 : total, 999*998. Omitting the bromide of 
 magnesium, the carbonate of lime, and the sulphate of lime, as 
 being very small quantities, the component parts were reduced 
 to common salt, 3 oz. ; Epsom salts, oz. ; chloride of mag- 
 nesium, 200 grains troy ; chloride of potassium, 40 grains 
 troy ; and four quarts of water. Next day the mixture was 
 filtered through a sponge into a glass jar, the bottom covered 
 with shore-pebbles and fragments of stone and fronds of green 
 sea-weed. A coating of green spores was soon deposited on the 
 sides of the glass, and bubbles of oxygen were copiously thrown 
 off every day under the excitement of the sun's light. In a 
 week Mr. Gosse put in species of Actinia Bowerlankia, Cellu- 
 laria, Serpula, <fec. with some red sea-weeds; and the whole 
 throve well. 
 
 VELOCITY OF IMPRESSIONS TRANSMITTED TO THE BRAIN. 
 
 Professor Helmholtz of Konigsberg has, by the electro- 
 magnetic method,* ascertained that the intelligence of an im- 
 pression made upon the ends of the nerves in communication 
 with the skin is transmitted to the brain with a velocity of 
 about 195 feet per second. Arrived at the brain, about one- 
 tenth of a second passes before the will is able to give the com- 
 mand to the nerves that certain muscles shall execute a certain 
 motion, varying in persons and times. Finally, about 
 
 A slight electric shock is given to a man at a certain portion of the skin ; 
 and he is directed the moment he feels the stroke to make a certain motion, as 
 quickly as he possibly can, with the hands or with the teeth, by which the time- 
 measuring current is interrupted. 
 
Things not generally Known. 
 
 of a second passes after the receipt of the command before the 
 muscle is in activity. In all, therefore, from the excitation 
 of the sensitive nerves till the moving of the muscle, 1^ to T %ths 
 of a second are consumed. Intelligence from the great toe ar- 
 rives about g^th of a second later than from the ear or the face. 
 Thus we see that the differences of time in the nervous im- 
 pressions, which we are accustomed to regard as simultaneous, 
 lie near our perception. We are taught by astronomy that, on 
 account of the time taken to propagate light, we now see what 
 has occurred in the fixed stars years ago ; and that, owing to 
 the time required for the transmission of sound, we hear after 
 we see is a matter of daily experience. Happily the distances 
 to be traversed by our sensuous perceptions before they reach 
 the brain are so short that we do not observe their influence, 
 and are therefore unprejudiced in our practical interest. With 
 an ordinary whale the case is perhaps more dubious ; for in all 
 probability the animal does not feel a wound near its tail until 
 a second after it has been inflicted, and requires another second 
 to send the command to the tail to defend itself. 
 
 PHOTOGRAPHS ON THE EETINA. 
 
 The late Rev. Dr. Scoresby explained with much minute- 
 ness and skill the varying phenomena which presented them- 
 selves to him after gazing intently for some time .on strongly- 
 illuminated objects, as the sun, the moon, a red or orange or 
 yellow wafer on a strongly-contrasted ground, or a dark object 
 seen in a bright field. The doctor explained, upon removing 
 the eyes from the object, the early appearance of the picture or 
 image which had been thus "photographed on the Retina/' 
 with the photochromatic changes which the picture underwent 
 while it still retained its general form and most strongly-marked 
 features ; also, how these pictures, when they had almost faded 
 away, could at pleasure, and for a considerable time, be renewed 
 by rapidly opening and shutting the eyes. 
 
 DIRECT EXPLORATION OF THE INTERIOR OF THE EYE. 
 
 Dr. S. Wood of Cincinnati states, that by means of a small 
 double convex lens of short focus held near the eye, that or- 
 gan looking through it at a candle twelve or fifteen feet distant, 
 there will be perceived a large luminous disc, covered with 
 dark and light spots and dark streaks, which, after a momen- 
 tary confusion, will settle down into an unchanging picture, 
 which picture is composed of the organs or internal parts of the 
 eye. The eye is thus enabled to view its own internal organis- 
 ation, to have a beautiful exhibition of the vessels of the cor- 
 nea, of the distribution of the lachrymas secretions in the act 
 
Curiosities of Science. 237 
 
 of winking, and to see into the nature and cause of muscce wli- 
 tantes. 
 
 NATUEE OF THE CANDLE-FLAME. 
 
 M. Volger has subjected this Flame to a new analysis. 
 
 He finds that the so-called flame-bud, a globular blue flaminule, is 
 first produced at the summit of the wick : this is the result of the com- 
 bustion of carbonic oxide, hydrogen, and carbon, and is surrounded by 
 a reddish-violet halo, the veil. The increased heat now gives rise to 
 the actual flame, which shoots forth from the expanding bud, and is 
 then surrounded at its inferior portion only by the latter. The interior 
 consists of a dark gaseous cone, containing the immediate products of 
 the decomposition of the fatty acids, and surrounded by another dark 
 hollow cone, the inner cap. Here we already meet with carbon and 
 hydrogen, which have resulted from the process of decomposition ; and 
 we distinguish this cone from the inner one by its yielding soot. The 
 external cap constitutes the most luminous portion of the flame, in which 
 the hydrogen is consumed and the carbon rendered incandescent. The 
 surrounding portion is but slightly luminous, deposits no soot, and in it 
 the carbon and hydrogen are consumed. Lieliy's Annual Report. 
 
 HOW SOON A COEPSE DECAYS. 
 
 Mr. Lewis, of the General Board of Health, from his exami- 
 nation of the contents of nearly 100 coffins in the vaults and 
 catacombs of London churches, concludes that the complete 
 decomposition of a corpse, and its resolution into its ultimate 
 elements, takes place in a leaden coffin with extreme slowness. 
 In a wooden coffin the remains, with the exception of the bones, 
 vanish in from two to five years. This period depends upon the 
 quality of the wood, 'and the free access of air to the coffins. 
 But in leaden coffins, 50, 60, 80, and even 100 years are re- 
 quired to accomplish this. " I have opened," says Mr. Lewis, 
 " a coffin in which the corpse had been placed for nearly a cen- 
 tury ; and the ammoiiiacal gas formed dense white fumes when 
 Drought in contact with hydrochloric-acid gas, and was so power- 
 ful that the head could not remain in it for more than a few 
 seconds at a time." To render the human body perfectly inert 
 after death, it should be placed in a light wooden coffin, in a 
 pervious soil, from five to eight feet deep. 
 
 MUSKET-BALLS FOUND IN IVOEY. 
 
 The Ceylon sportsman, in shooting elephants, aims at a spot 
 just above the proboscis. If he fires a little too low, the ball 
 passes into the tusk-socket, causing great pain to the animal, 
 but not endangering its life ; and it is immediately surrounded 
 by osteo-dentine. It has often been a matter of wonder how 
 such bodies should become completely imbedded in the sub- 
 stance of the tusk, sometimes without any visible aperture ; or 
 how leaden bullets become lodged in the solid centre of a very 
 
Things not generally Known. 
 
 large tusk without having been flattened, as they are found by 
 the ivory-turner. 
 
 The explanation is as follows : A musket-ball aimed at the head of 
 an elephant may penetrate the thin bony socket and the thinner ivory 
 parietes of the wide conical pulp-cavity occupying the inserted base of 
 the tusk ; if the projectile force be there spent, the ball will gravitate 
 to the opposite and lower side of the pulp-cavity. The pulp becomes 
 inflamed, irregular calcification ensues, and osteo-dentine is formed 
 around the ball. The pulp then resumes its healthy state and functions, 
 and coats the osteo-dentine enclosing the ball, together with the root of 
 the conical cavity into which the mass projects, with layers of normal 
 ivoiy. The hole formed by the ball is soon replaced, and filled up by 
 osteo-dentine, and coated with cement. Meanwhile, by the continued 
 progress of growth, the enclosed ball is pushed forward to the middle of 
 the solid tusk ; or if the elephant be young, the ball may be carried 
 forward by growth and wear of the tusk until its base has become the 
 apex, and become finally exposed and discharged by the continual abra- 
 sion to which the apex of the tusk is subjected. Professor Owen. 
 
 NATURE OF THE SUN. 
 
 To the article at pp. 59-60 should be added the result ob- 
 tained by Dr. Woods of Parsonstown, and communicated to the 
 Philosophical Magazine for July 1854. Dr. Woods, from photo- 
 graphic experiment, has no doubt that the light from the centre 
 of flame acts more energetically than that from the edge on a 
 surface capable of receiving its impression ; and that light from 
 a luminous solid body acts equally powerfully from its centre 
 or its edges : wherefore Dr. Woods concludes that, as the sun 
 aifects a sensitive plate similarly with flame, it is probable its 
 light-producing portion is of a similar nature. 
 
 Note to " Is THE HEAT OF THE SUN DECREASING ?" at page 65. 
 Dr. Vaughan of Cincinnati has stated to the British Association : 
 t( From a comparison of the relative intensity of solar, lunar, and arti- 
 ficial light, as determined by Euler and Wollaston, it appears that the 
 rays of the sun have an illuminating power equal to that ot 14,000 can- 
 dles at a distance of one foot, or of 3500, 000000, 000000, OuOOOO, 000000 
 candles at a distance of 95,000,000 miles. It follows that the amount 
 of light which flows from the solar orb could be scarcely produced by 
 the daily combustion of 200 globes of tallow, each equal to the earth in 
 magnitude. A sphere of combustible matter much larger than the sun 
 itself should be consumed every ten years in maintaining its wonderful 
 brilliancy; and its atmosphere, if pure oxygen, would be expended be- 
 fore a few days in supporting so great a conflagration. An illumination 
 on so vast a scale coul 1 be kept up only by the inexhaustible magazine 
 of ether disseminated through space, and ever ready to manifest its lu- 
 ciferous properties on large spheres, whose attraction renders it suffi- 
 ciently dense for the play of chemical affinity. Accordingly suns de- 
 rive the power of shedding perpetual light, not from their chemical 
 constitution, but from their immense mass and their superior attractive 
 power." 
 
Curiosities of Science. 
 
 239 
 
 PLANETOIDS. 
 
 Name. 
 
 Date of 
 Discovery. 
 
 Discoverer. 
 
 Place of 
 Discovery. 
 
 No. disco- 
 vered by each 
 astronomer. 
 
 Mercury Mars, ) 
 
 Known to the > 
 
 
 
 
 Earth, Saturn) J 
 Uranus 
 
 ancients, j 
 
 1781, March 13.. 
 1846 Sept 23 
 
 W. Herschel 
 Galle 
 
 Bath 
 Berlin 
 
 - 
 
 1 Ceres 
 2 Pallas 
 
 1801, Jan. 1 
 1802, March 28.. 
 
 Piazzi 
 Olbers 
 
 Palermo 
 Bremen 
 
 1 
 
 1 
 
 3 Juno 
 
 4 Vesta 
 
 1804, Sept. 1 
 1807, March 29.. 
 
 Harding .... 
 Olbers 
 
 Lilienthal.... 
 Bremen 
 
 1 
 2 
 
 
 1845, Dec. 8 
 
 Eucke 
 
 Driesen 
 
 1 
 
 6 Hebe 
 7 iris 
 
 1847, July 1 
 1847, August 13. 
 
 Encke 
 Hind 
 
 Drieseu 
 London 
 
 2 
 1 
 
 8 Flora 
 9 Metis 
 
 1847, Oct. 18 
 1848, April 25 ... 
 
 Hind 
 Graham.... 
 
 London 
 Markree 
 
 2 
 1 
 
 10 Hygeia 
 11 Parthenope.. 
 12 Victoria 
 13 Egeria 
 
 1849, April 12 ... 
 1850, May 11 
 1850, Sept. 13.... 
 1850 Nov 2 
 
 Gasperis 
 Gasperis 
 Hind 
 
 Naples 
 Naples 
 London 
 Naples 
 
 1 
 2 
 3 
 3 
 
 14 Irene 
 
 1851, May 19 
 1851, July 29 
 
 Hind 
 
 London 
 Naples 
 
 4 
 4 
 
 16 Psyche 
 17 Thetis 
 
 1852, March 17.. 
 1852, April 17 ... 
 
 Gasperis 
 Luther 
 
 Naples 
 Bilk 
 
 5 
 1 
 
 18 Melpomene 
 
 1852, June 24.... 
 
 Hind .. 
 
 London 
 
 5 
 
 19 Fortuna 
 
 1852, August 22 
 
 Hind 
 
 Londop 
 
 6 
 
 20 Massilia 
 
 1852, Sept. 19.... 
 185' ? Nov 15 
 
 Gasperis 
 
 Naples 
 Paris . 
 
 6 
 I 
 
 22 Calliope 
 
 1852, Nov. 16.... 
 
 Hind . 
 
 London 
 
 7 
 
 23 Thalia 
 
 1852, Dec. 15. ... 
 
 Hind 
 
 London 
 
 g 
 
 24 Themis 
 25 Phocea 
 26 Proserpine... 
 
 27 Euterpe 
 
 1853, April 5 
 1853, April 6 
 1853, May 5 
 
 1853, Nov. 8... 
 
 Gasperis 
 Chacornac.... 
 Luther 
 Hind 
 
 Naples 
 Marseilles ... 
 Bilk 
 
 7 
 1 
 2 
 9 
 
 28 Belkma 
 
 1854, March 1 ... 
 
 Luther 
 
 Bilk 
 
 3 
 
 29 Amphitrite 
 
 1854 March 1 
 
 Marth 
 
 
 1 
 
 30 Urania 
 
 1854, July 22.... 
 
 Hind . 
 
 London 
 
 10 
 
 31 Euphrosyne, 
 32 Pomona 
 
 1854, Sept. 1 
 1854 Oct 26 
 
 Furguson . ... 
 Goldschmidt 
 
 Washington. 
 Paris 
 
 1 
 2 
 
 33 Polyhymnia 
 
 1854 Oct 28 
 
 
 Paris 
 
 2 
 
 34 Circe .' 
 35 Leucothea. 
 
 1855, April 6 
 1855, April 19 
 
 Chacornac.... 
 Luther 
 
 Paris 
 Bilk 
 
 3 
 4 
 
 36 Atalante 
 37 Fides 
 
 1855, Oct. 5 
 1855, Oct. 5 ... 
 
 Goldschmidt 
 
 Paris 
 Bilk 
 
 3 
 5 
 
 38 Leda 
 
 1856 Jan 12 
 
 
 Paris .... 
 
 4 
 
 39 Laetitia 
 
 1856, Feb. 8 . 
 
 
 Paris 
 
 5 
 
 40 Harmonia.... 
 41 Daphne 
 42 Isis 
 
 1856, March 31.. 
 1856, May 22 ... 
 1856, May 23.... 
 
 Goldschmidt 
 Goldschmidt 
 
 Paris 
 Paris 
 Oxford 
 
 4 
 5 
 1 
 
 43 Ariadne 
 
 1857, April 15 
 
 Pogson 
 
 Oxford 
 
 2 
 
 44 Nysa 
 
 1857, May 27 
 
 
 Paris 
 
 6 
 
 45 Eugenia 
 46 Hastia 
 
 1857, June 28.... 
 1857, August 16 
 
 Goldschmidt 
 
 Paris 
 Oxford .. 
 
 7 
 3 
 
 47 Aglaia 
 
 1857, Sept. 15 . . 
 
 
 Bilk 
 
 6 
 
 48 Doris 
 49 Pales 
 
 1857, Sept. 19.... 
 1857 Sept 19 
 
 Goldschmidt 
 
 Paris 
 
 Paris 
 
 8 
 g 
 
 50 Virginia 
 51 Nemausa 
 62 Europa 
 
 1857, Oct. 4 
 1858, Jan. 22 
 1858, Feb 6 
 
 Furguson.... 
 Laurent 
 Goldschmidt 
 
 Washington. 
 Nismes 
 Paris 
 
 2 
 1 
 
 10 
 
 53 Calypso 
 
 1858, April 8 
 
 Luther 
 
 Bilk 
 
 7 
 
 54 Alexandra ... 
 
 1858, Sept 11 
 
 
 Pans. 
 
 11 
 
 55 (Not named). 
 
 1858, iSept. 11.... 
 
 Searle 
 
 Albany 
 
 1 
 
 Through the calculations of M. Le Verrier. 
 
240 Things not generally Known. 
 
 THE COMET OF DONATI. 
 
 While this sheet was passing through the press, the attention 
 of astronomers, and of the public generally, was drawn to the 
 fact of the above Comet passing (on Oct. 18) within nine mil- 
 lions of miles of the planet Venus, or less than yfo-ths of the 
 earth's distance from the Sun. " And (says Mr. Hind, the as- 
 tronomer), it is obvious that if the comet had reached its least 
 distance from the sun a few days earlier than it has done, the 
 planet might have passed through it ; and I am very far from 
 thinking that close proximity to a comet of this description 
 would be unattended with danger. The inhabitants of Venus 
 will witness a cometary spectacle far superior to that which 
 has recently attracted so much attention here, inasmuch as the 
 tail will doubtless appear twice as long from that planet as 
 from the earth, and the nucleus proportionally more brilliant." 
 
 This Comet was first discovered by Dr. G. B. Donati, astro- 
 nomer at the Museum of Florence, on the evening of the 2d of 
 June, in right ascension 141 18', and north declination 23 47', 
 corresponding to a position near the star Leonis. Previous to 
 this date we had no knowledge of its existence, and therefore 
 it was not a predicted comet ; neither is it the one last ob- 
 served in 1556. At the date of discovery it was distant from 
 the earth 228,000,000 of miles, and was an excessively faint ob- 
 ject in the largest telescopes. 
 
 The tail, from October 2 to 16, when the comet was most 
 conspicuous, appears to have maintained an average length 
 of at least 40,000,000 miles, subtending an angle varying from 
 30 to 40. The dark line or space down the centre, fre- 
 quently remarked in other great comets, was a striking cha- 
 racteristic in that of Donati. The nucleus, though small, was 
 intensely brilliant in powerful instruments, and for some time 
 bore high magnifiers to much greater advantage than is usual 
 with these objects. In several respects this comet resembled 
 the famous ones of 1744, 1680, and 1811, particularly as re- 
 gards the signs of violent agitation going on in the vicinity of 
 the nucleus, such as the appearance of luminous jets, spiral 
 offshoots, &c., which rapidly emanated from the planetary point 
 and as quickly lost themselves in the general nebulosity of the 
 head. 
 
 On the 5th Oct. the most casual observer had an opportu- 
 nity of satisfying himself as to the accuracy of the mathematical 
 theory of the motions of comets in the near approach of the 
 nucleus of Donati's to Arcturus, the principal star in the con- 
 stellation Bootes. The circumstance of the appulse was very 
 nearly as predicted by Mr. Hind. 
 
 The comet, according to the investigations by M. Loewy, 
 
Curiosities of Science. 
 
 of the Observatory of Vienna, arrived at its least distance from 
 the sun a few minutes after eleven o'clock on the morning of 
 the 30th of September ; its longitude, as seen from the sun at 
 this time, being 36 13', and its distance from him 55,000,000 
 miles. The longer diameter of its orbit is 184 times that of 
 the earth's, or 35,100,000,000 miles; yet this is considerably 
 less than ToWth of the distance of the nearest fixed star. As 
 an illustration, let any one take a half-sheet of note-paper, and 
 marking a circle with a sixpence in one corner of it, describe 
 therein our solar system, drawing the orbits of the earth and 
 the inferior planets as small as he can by the aid of a magnify - 
 ing-glass. If the circumference of the sixpence stands for the 
 orbit of Neptune, then an oval filling the page will fairly repre- 
 sent the orbit of Donati's comet ; and if the paper be laid upon 
 the pavement under the west door of St. Paul's Cathedral, Lon- 
 don, the length of that edifice will inadequately represent the 
 distance of the nearest fixed star. The time of revolution re- 
 sulting from Mr. Loewy's calculations is 2495 years, which is 
 about 500 years less than that of the comet of 1811 during the 
 period it was visible from the earth. 
 
 That the comet should take more than 2000 years to travel 
 round the above page of note-paper is explained by its great 
 diminution of speed as it recedes from the sun. At its perihelion 
 it travelled at the rate of 127,000 miles an hour, or more than 
 twice as fast as the earth, whose motion is about 1000 miles a 
 minute. At its aphelion, however, or its greatest distance from 
 the sun, the comet is a very slow body, sailing at the rate of 
 480 miles an hour, or only eight times the speed of a railway 
 express. At this pace, were it to travel onward in a straight 
 line, the lapse of a million of years would find it still travelling 
 half way between our sun and the nearest fixed star. 
 
 As this comet last visited us between 2000 and 2495 years 
 since, we know that its appearance was at an interesting period 
 of the world's history. It might have terrified the Athenians 
 into accepting the bloody code of Draco. It might have an- 
 nounced the destruction of Nineveh, or of Babylon, or the 
 capture of Jerusalem by Nebuchadnezzar. It might have been 
 seen by the expedition which sailed round Africa in the reign 
 of Pharaoh Necho. It might have given interest to the found- 
 ation of the Pythian games. Within the probable range of its 
 last visitation are comprehended the whole of the great events 
 of the history of Greece ; and among the spectators of the comet 
 may have been the so-called sages of Greece and even the pro- 
 phets of Holy Writ : Thales might have attempted to calculate 
 its return, and Jeremiah might have tried to read its warning. 
 
 Abridged from a Communication from Mr. Hind to the Times, and from a Leader 
 in that Journal. 
 
GENEEAL INDEX. 
 
 ABODES of the Blest, 58. 
 
 Acarus of Crosse and "Weeks, 218. 
 
 Accuracy of Chinese Observers, 
 159. 
 
 Adamant, What was it ? 123. 
 
 Aeronautic Voyage, Remarkable, 
 169. 
 
 Agassiz, Discoveries of, 127. 
 
 Air, Weight of, 14. 
 
 All the World in Motion, 11. 
 
 Alluvial Land of Egypt, 110. 
 
 Ancient World, Science of the, 1. 
 
 Animals in Geological Times, 128. 
 
 Anticipations of the Electric Tele- 
 graph, 220-224. 
 
 Arago on Protection from Storms, 
 159. 
 
 Arctic Climate, Phenomena of, 
 162. 
 
 Arctic Explorations, Rae's, 162. 
 
 Arctic Regions, Scenery and Life 
 of, 180. 
 
 Arctic Temperature, 161. 
 
 Armagh Observatory Level, 
 Change of, 144. 
 
 Artesian Fire-Springs, 118. 
 
 Artesian Well of Grenelle, 114. 
 
 Astronomer, Peasant, 101. 
 
 Astronomer's Dream verified, 88. 
 
 Astronomers, Triad of Contempo- 
 rary, 100. 
 
 Astronomical Observations, Nicety 
 of, 102. 
 
 Astronomy and Dates on Monu- 
 ments, 55. 
 
 Astronomy and Geology, Identity 
 of, 104. 
 
 Astronomy, Great Truths of, 54. 
 
 Atheism, Folly of, 3. 
 
 Atlantic, Basin of the, 171. 
 
 Atlantic, Gales of the, 171. 
 
 Atlantic Telegraph, the, 226-228. 
 
 Atmosphere, Colours of the, 147. 
 
 Atmosphere compared to a Steam- 
 engine, 152. 
 
 Atmosphere, Height of, 147. 
 
 Atmosphere, the, 146. 
 
 Atmosphere, the purest, 150. 
 
 Atmosphere, Universality of the, 
 147. 
 
 Atmosphere weighed by Pascal, 
 148. 
 
 Atoms of Elementary Bodies, 13. 
 
 Atoms, the World of, 13. 
 
 Aurora Borealis, Halley's hypo- 
 thesis of, 198. 
 
 Aurora Borealis, Splendour of the, 
 165. 
 
 Australian Cavern, Inmates of, 
 137. 
 
 Australian Pouch-Lion, 137. 
 
 Axis of Rotation, the, 11. 
 
 BAROMETER, Gigantic, 151. 
 
 Barometric Measurement, 151. 
 
 Batteries, Minute and Vast, 204. 
 
 Birds, Gigantic, of New Zealand, 
 Extinct, 139. 
 
 "Black Waters, the," 182. 
 
 Bodies, Bright, the Smallest, 31. 
 
 Bodies, Compression of, 12. 
 
 Bodies, Fall of, 16. 
 
 Bottles and Currents at Sea, 172. 
 
 Boulders, How transported to 
 Great Heights, 105. 
 
 Boyle on Colours, 49. 
 
 Boyle, Researches of, 6. 
 
 Brain, Impressions transmitted to, 
 235. 
 
 Buckland, Dr., his Geological La- 
 bours, 127. 
 
 Building-Stone, Wear of, 108. 
 
 Burnet's Theory of the Earth, 125. 
 
 Bust, Magic, 36. 
 
 CANDLE-FLAMK, Nature of, 237. 
 Canton's Artificial Magnets, 196. 
 Carnivora of Britain, Extinct, 132. 
 Carnivores, Monster, of France, 
 138. 
 
INDEX. 
 
 243 
 
 Cataract, Great, in India, 183. 
 Cat, Can it see in the Dark ? 51. 
 Caves of New Zealand and its Gi- 
 gantic Birds, 140. 
 Cave Tiger or Lion of Britain, 133. 
 Central Heat, Theory of, 116. 
 Chabert, "the Fire King," 192. 
 Chalk Formation, the, 108. 
 Changes on the Earth's Surface, 
 
 142. 
 Chantrey, Heat-Experiments by, 
 
 192. 
 
 Children's powerful Battery, 204. 
 Chinese, the, and the Magnetic 
 
 Needle, 194. 
 Chronometers, Marine, How rated 
 
 at Greenwich Observatory, 229. 
 Climate, finest in the World, 149. 
 Climate, Variations of, 148. 
 Climates, Average, 149. 
 Clock, How to make Electric, 212. 
 Cloud-ring, the Equatoiial, 156. 
 Clouds, Fertilisation of, 151. 
 Coal, Torbane-Hill, 123. 
 Coal, What is it? 123. 
 Cold in Hudson's Bay, 160. 
 Colour of a Body, and its Magnetic 
 
 Properties, 197. 
 
 Colours and Tints, Chevreulou, 37. 
 Colours most frequently hit in 
 
 Battle, 36. 
 
 Comet, the, of Donati, 240, 241. 
 Comet, Great, of 1843, 84. 
 Comets, Magnitude of, 84. 
 Comets visible in Sunshine, 84. 
 Computation, Power of, 10. 
 Coney of Scripture, 137. 
 Conic Sections, 10. 
 Continent Outlines not fixed, 145. 
 Coi-pse, How soon it decays, 237. 
 " Cosmos, Science of the, ' 10. 
 Crosse, Andrew, his "Artificial 
 
 Crystals and Minerals, 216-219. 
 Crosse Mite, the, 218. 
 Crystallisation, Reproductive, 26. 
 Crystallisation, Theory of, 24. 
 Crystallisation, Visible, 25. 
 Crystals, Immense, 24. 
 "Crystal Vault of Heaven," 55. 
 
 DAVY, SIR HUMPHRY, obtains 
 
 Heat from Ice, 390. 
 Davy's great Battery at the Eoyal 
 
 Institution, 204. 
 Day, Length of, and Heat of the 
 
 Earth, 186. 
 
 Day's Length at the Poles, 65. 
 
 Declination of the Needle, 197. 
 
 Descartes' Labours in Physics, 9. 
 
 Desert, Intense Heat and Cold of 
 the, 163. 
 
 Dewdrop, Beauty of the, 157. 
 
 Dew-fall in one year, 157. 
 
 Dew graduated to supply Vegeta- 
 tion, 157. 
 
 Diamond, Geological Age of, 122. 
 
 Diamond Lenses for Microscopes, 
 40. 
 
 " Diamond," Newton's Dog, 8. 
 
 Dinornis elephantopus, the, 139, 
 
 Dinotherium, or Terrible Beast, 
 
 the, 136. 
 Diorama, Illusion of the, 37. 
 
 EARTH and Man compared, 22. 
 
 Earth, Figure of the, 21. 
 
 Earth, Mass and Density of, 21. 
 
 Earth's Annual Motion, 12. 
 
 Earth's Magnitude, to ascertain, 
 21. 
 
 Earth's Surface, Mean Tempera- 
 ture of, 23. 
 
 Earth's Temperature, Interior, 116. 
 
 Earth's Temperature Stationary, 
 23. 
 
 Earth, the, a Magnet, 197. 
 
 Earthquake, the Great Lisbon, 
 121. 
 
 Earthquakes and the Moon, 121. 
 
 Earthquakes, Eumblings of, 120. 
 
 Earthquake-Shock, How to mea- 
 sure, 120. 
 
 Earth-Waves, 119. 
 
 Eclipses, Cause of, 74. 
 
 Egypt, Alluvial Land of, 110. 
 
 Electric Girdle for the Earth, 224. 
 
 Electric Incandescence of Charcoal 
 Points, 204. 
 
 Electric Knowledge, Germs of, 
 207. 
 
 Electric Light, Velocity of, 209. 
 
 Electric Messages, Time lost in, 
 225. 
 
 Electric Paper, 209. 
 
 Electric Spark, Duration of, 209. 
 
 Electric Telegraph, Anticipations 
 of the, 220-224. 
 
 Electric Telegraph, Consumption 
 of, 224. 
 
 Electric Telegraph in Astronomy 
 and Longitude, 225. 
 
244 
 
 INDEX. 
 
 Electric Telegraph and Lightning, 
 226. 
 
 Electric and Magnetic Attraction, 
 Identity of, 210. 
 
 Electrical Kite, Franklin's, 213. 
 
 Electricity and Temperature, 208. 
 
 Electricity in Brewing, 209. 
 
 Electricity, Vast Arrangement of, 
 208. 
 
 Electricity, Water decomposed 
 by, 208. 
 
 Electricities, the Two, 214. 
 
 Electro-magnetic Clock, Wheat- 
 stone's, 211. 
 
 Electro-magnetic Engine, Theory 
 of, 210. 
 
 Electro-magnets, Horse-shoe, 199. 
 
 Electro-telegraphic Message to the 
 Stars, 226. 
 
 Elephant and Tortoise of India, 
 135. 
 
 End of our System, 92. 
 
 England in the Eocene Period, 
 129. 
 
 English Channel, Probable Origin 
 of, 105. 
 
 Eocene Period, the, 129. 
 
 Equatorial Cloud-ring, 156. 
 
 " Equatorial Doldrums," 156. 
 
 Error upon Error, 1 85. 
 
 Exhilaration in ascending Moun- 
 tains, 163. 
 
 Eye and Brain seen through a Mi- 
 croscope, 41. 
 
 Eye, interior, Exploration of, 236. 
 
 FALL of Bodies, Rate of, 16. 
 
 Falls, Height of, 16. 
 
 Faraday, Genius and Character of, 
 193. 
 
 Faraday's Electrical Illustrations, 
 214. 
 
 " Father of English Geology, the," 
 126. 
 
 Fertilisation of Clouds, 151. 
 
 Fire, Perpetual, 117. 
 
 Fire-balls and Shooting Stars, 
 89. 
 
 Fire-Springs, Artesian, 118. 
 
 Fishes, the most Ancient, 132. 
 
 Flying Dragon, the, 130. 
 
 Force neither created nor de- 
 stroyed, 18. 
 
 Force of Running Water, 114. 
 
 Fossil Human Bones, 131. 
 
 Fossil Meteoric Stones, none, 92. 
 
 Fossil Rose, none, 142. 
 Foucault'sPendulumExperiments, 
 
 22. 
 
 Franklin's Electrical Kite, 213. 
 Freezing Cavern in Russia, 115. 
 Fresh Water in Mid-Ocean, 182. 
 
 GALILEAN Telescope, the, 93. 
 
 Galileo, What he first saw with the 
 Telescope, 93. 
 
 Galvani and Volta, 205. 
 
 Galvanic Effects, Familiar, 203. 
 
 Galvanic Waves on the same Wire, 
 Non-interference of, 225. 
 
 " Gauging the Heavens," 58. 
 
 Genius, Relics of, 5. 
 
 Geology and Astronomy, Identity 
 of, 104. 
 
 Geology of England, 105. 
 
 Geological Time, 143. 
 
 George III., His patronage of Her- 
 schel, 95. 
 
 Gilbert on Magnetic and Electric 
 forces, 201. 
 
 Glacial Theory, by Hopkins, 105. 
 
 Glaciers, Antiquity of, 109. 
 
 Glaciers, Phenomena of, Illus- 
 trated, 108. 
 
 Glass, Benefits of, to Man, 92. 
 
 Glass broken by Sand, 26. 
 
 Glyptodon, the, 137. 
 
 Gold, Lumps of, in Siberia, 124. 
 
 Greenwich Observatory, Chrono- 
 meters rated at, 229-232. 
 
 Grotto del Cane, the, 112. 
 
 Gulf-Stream and the Temperature 
 of London, 115. 
 
 Gunpowder - Magazines, Danger 
 to, 216. 
 
 Gymnotus and the Voltaic Bat- 
 tery, 206. 
 
 Gyroscope, Foucault's, 22. 
 
 HAIL and Storms, Protection 
 
 against, 159. 
 
 Hail-storm, Terrific, 160. 
 Hair, Microscopical Examination 
 
 of, 41. 
 Harrison's Prize Chronometers, 
 
 229-232. 
 
 Heat and Evaporation, 188. 
 Heat and Mechanical Power, 188. 
 Heat, by Friction, 189. 
 Heat, Distinctions of, 187. 
 Heat, Expenditure of, by the Sun, 
 
 186. 
 
INDEX. 
 
 245 
 
 Heat from Gas-lighting, 189. 
 
 Heat from Wood and Ice, 190. 
 
 Heat, Intense, Protection from, 
 191, 192. 
 
 Heat, Latent, 187. 
 
 Heat of Mines, 188. 
 
 Heat, Nice Measurement of, 186. 
 
 Heat, Origin of, in our System, 87. 
 
 Heat passing through Glass, 189. 
 
 Heat, Repulsion by, 191. 
 
 Heated Metals, Vibration of, 188. 
 
 Heavy Persons, Lifting, 17. 
 
 Heights and Distances, to Calcu- 
 late, 19. 
 
 Herschel's Telescopes at Slough, 
 95. 
 
 Highton's Minute Battery, 204. 
 
 Hippopotamus of Britain, 135. 
 
 " Horse Latitudes, the," 173. 
 
 Horse, Three-hoofed, 138. 
 
 Hour-glass, Sand in the, 20. 
 
 ICE, Heat from, 190. 
 Ice, Warming with, 190. 
 Icebergs of the Polar Seas, 180. 
 Iguanodon, Food of the, 129. 
 Improvement, Perpetuity of, 5. 
 Inertia Illustrated, 14. 
 
 JERUSALEM, Temple of, How pro- 
 tected from Lightning, 167. 
 
 Jew's Harp, Theory of the, 29. 
 
 Jupiter's Satellites, Discovery of, 
 80. 
 
 KALEIDOSCOPE, Sir David Brew- 
 
 ster's, 43. 
 Kaleidoscope, the, thought to be 
 
 anticipated, 43. 
 Kircher's " Magnetism," 194. 
 
 LEANING TOWER, Stability of, 15. 
 
 Level, Curious Change of, 144. 
 
 Leyden Jar, Origin of the, 216. 
 
 Lifting Heavy Persons, 17. 
 
 Light, Action of, on Muscular Fi- 
 bres, 34. 
 
 Light, Apparatus for Measuring, 
 32. 
 
 Light from Buttons, 36. 
 
 Light, Effect of, on the Magnet, 198. 
 
 Light from Fungus, 36. 
 
 Light from the Juice of a Plant, 35. 
 
 Light, Importance of, 34. 
 
 Light, Minuteness of, 34. 
 
 Light Nights, 35. 
 
 Light, Polarisation of, 33. 
 
 Light, Solar and Artificial Com- 
 pared, 29. 
 
 Light, Source of, 29. 
 
 Light, Undulatory Scale of, 30. 
 
 Light, Velocity of, 31. 
 
 Light, Velocity of, Measured by 
 Fizeau, 32. 
 
 Light from Quartz, 51. 
 
 Lightning-Conductor, Ancient,167. 
 
 Lightning-Conductors, Service of, 
 166. 
 
 Lightning Experiment, Fatal, 214. 
 
 Lightning, Photographic Effects 
 of, 45. 
 
 Lightning produced by Rain, 166. 
 
 Lightning, Sheet, What is it? 
 165. 
 
 Lightning, Varieties of, 165. 
 
 Lightning, Various Effects of, 168. 
 
 Log, Invention of the, 173. 
 
 London Monument used as an Ob- 
 servatory, 103. 
 
 " MAESTRICHT Saurian Fossil," the, 
 
 141. 
 
 Magnet, Power of a, 195. 
 Magnets, Artificial, How made, 
 
 195. 
 
 Magnetic Clock and Watch, 211. 
 Magnetic Electricity discovered, 
 
 199. 
 
 Magnetic Hypotheses, 193. 
 Magnetic Needle and the Chinese, 
 
 J94. 
 Magnetic Poles, North and South, 
 
 201. 
 
 Magnetic Storms, 202. 
 "Magnetism," Kircher's, 194. 
 Malachite, How formed, 124. 
 Mammalia in Secondary Rocks, 
 
 130. 
 
 Mammoth of the British Isles, 133. 
 Mammoth, Remains of the, 134. 
 Mars, the Planet, Is it inhabited ? 
 
 82. 
 Mastodon coexistent with Man, 
 
 135. 
 
 Matter, Divisibility of, 14. 
 Maury's Physical Geography of the 
 
 Sea, 170. 
 
 Mediterranean, Depth of, 176. 
 Megatherium, Habits of the, 135. 
 Mercury, the Planet, Temperature 
 
 of, 82. 
 Mer de Glace, Flow of the, 110. 
 
246 
 
 INDEX. 
 
 Meteoric Stones, no Fossil, 92. 
 
 Meteorites, Immense, 91. 
 
 Meteorites from the Moon, 89. 
 
 Meteors, Vast Shower of, 91. 
 
 Microscope, the Eye, Brain, and 
 Hair seen by, 41. 
 
 Microscope, Fish -eye, How to 
 make, 40. 
 
 Microscope, Invention of the, 39. 
 
 Microscope for Mineralogists, 42. 
 
 Microscope and the Sea, 42. 
 
 Microscopes, Diamond Lenses for. 
 40. 
 
 Microscopes, Leuwenhoeck's, 40. 
 
 Microscopic Writing, 42. 
 
 Milky Way, the, Unfathomable, 85. 
 
 Mineralogy and Geometry, Union 
 of, 25. 
 
 Mirror, Magic, How to make, 43. 
 
 Moon's Attraction, the, 73. 
 
 Moon, Has it an Atmosphere ? 69. 
 
 Moon, Life in the, 71. 
 
 Moon, Light of the, 70. 
 
 Moon, Mountains in, 72. 
 
 Moon, Measuring the Earth by, 74. 
 
 Moon seen through the Rosse Te- 
 lescope, 72. 
 
 Moon, Scenery of, 71. 
 
 Moon and Weather, the, 73. 
 
 Moonlight, Heat of, 70. 
 
 "More Worlds than One," 56, 57. 
 
 Mountain-chains, Elevation of, 107. 
 
 Music of the Spheres, 55. 
 
 Musket-balls found in Ivory, 237. 
 
 NATURAL and Supernatural, the, 6. 
 
 Nautical Almanac, Errors in, 185. 
 
 Nebulae, Distances of, 85. 
 
 Nebular Hypothesis, the, 86. 
 
 Neptune, the Planet, Discovery of, 
 83. 
 
 Newton, Sir Isaac, his "Apple- 
 tree," 8. 
 
 Newton upon Burnet's Theory of 
 the Earth, 125. 
 
 Newton's Dog "Diamond," 8. 
 
 Newton's first Keflecting Teles- 
 cope, 94. 
 
 Newton's " Principia," 9. 
 
 Newton's Rooms at Cambridge, 7. 
 
 Newton's Scale of Colours, 49. 
 
 Newton's Soap - bubble Experi- 
 ments, 49, 50. 
 
 New Zealand, Extinct Birds of, 
 139. 
 
 Niagara, the Roar of, 28. 
 
 Nineveh, Rock-crystal Lens found 
 
 at, 39. 
 
 Non-conducting Bodies, 215. 
 Nothing Lost in the Material 
 
 World, 18. 
 
 Objects really of no Colour, 37. 
 Objects, Visibility of, 30. 
 Observation, the Art of, 3. 
 Observatory, Lacaille's, 101. 
 Observatory, the London Monu- 
 ment, 103. 
 
 Observatory, Shirburn Castle, 101. 
 Ocean and Air, Depths of unknown, 
 
 Ocean Highways, 184. 
 
 Ocean, Stability of the, 12. 
 
 Ocean, Transparency of the, 171. 
 
 " Oldest piece of Wood upon the 
 Earth," 142. 
 
 Optical Effects, Curious, at the 
 Cape, 38. 
 
 Optical Instruments, Late Inven- 
 tion of, 100. 
 
 Oxford arid Cambridge, Science 
 at, 1. 
 
 PASCAL, How he weighed the At- 
 mosphere, 148. 
 
 Pebbles, on, 106. 
 
 Pendulum Experiments, 16-22. 
 
 Pendulum, the Earth weighed by, 
 200. 
 
 Pendulums, Influence of on each 
 other, 200. 
 
 Perpetual Fire, 117. 
 
 Petrifaction of Human Bodies, 131. 
 
 Phenomena, Mutual Relations of, 4. 
 
 Philosophers' False Estimates, 5. 
 
 Phosphorescence of Plants, 35. 
 
 Phosphoi*escence of the Sea, 35. 
 
 Photo-galvanic Engraving, 47. 
 
 Photograph and Stereoscope, 47. 
 
 Photographic effects of Lightning, 
 45. 
 
 Photographic Surveying, 46. 
 
 Photographs on the Retina, 236. 
 
 Photography, Best Sky for, 45. 
 
 Photography, Magic of, 44. 
 
 Pisa, Leaning Tower of, 15. 
 
 Planetary System, Origin of our, 
 86. 
 
 Planets. Diversities of, 79. 
 
 Planetoids, List of the, and their 
 Discoverers, 239. 
 
 Plato's Survey of the Sciences, 2. 
 
INDEX. 
 
 247 
 
 Pleiades, the, 77. 
 Plurality of Worlds, 57. 
 Polar Ice, Immensity of, 181. 
 Polar Iceberg, 180. 
 Polarisation of Light, 33. 
 Pole, Open Sea at the, 181. 
 Pole-Star of 4000 years ago, 76. 
 Profitable Science, 139. 
 Pterodactyl, the, 130. 
 Pyramid, Duration of the, 14. 
 
 QUARTZ, Down of, 42. 
 
 EAIN, All in the World, 155. 
 Eain, an Inch on the Atlantic, 156. 
 Bain-Drops, Size of, 154. 
 Rain, How the North Wind drives 
 
 it away, 154. 
 Rain, Philosophy of, 153. 
 Rainless Districts, 155. 
 Rain-making Vapour, from South 
 
 to North, 152. 
 
 Rainy Climate, Inordinate, 154. 
 Red Sea and Mediterranean Levels, 
 
 175. 
 
 Red Sea, Colour of, 176. 
 Repulsion of Bodies, 216. 
 Rhinoceros of Britain, 135. 
 River- water on the Ocean, 181. 
 Rose, no Fossil, 142. 
 Rosse, the Earl of, his "Telescope," 
 
 96-99. 
 Rotation - Magnetism discovered, 
 
 199. 
 Rotation, the Axis of, 11. 
 
 ST. PAUL'S CATHEDRAL, how pro- 
 tected from Lightning, 167. 
 
 Salt, All in the Sea, 179. 
 
 Salt Lake of Utah, 113. 
 
 Salt, Solvent Action of, 115. 
 
 Sal tn ess of the Sea', How to tell, 
 179. 
 
 Sand in the Hour-glass, 20. 
 
 Sand of the Sea and Desert, 106. 
 
 Saturn's Ring, Was it known to 
 the Ancients? 81. 
 
 Schwabe, on Sun-Spots, 68. 
 
 Science at Oxford and Cambridge, 
 
 Science of the Ancient World, 1. 
 
 Science, Theoretical, Practical Re- 
 sults of, 4. 
 
 Sciences, Plato's Survey of, 2. 
 
 Scientific Treatise, the Earliest En- 
 glish, 5. 
 
 Scoresby, Dr., on the Rosse Tele- 
 scope, 99. 
 
 Scratches, Colours of, 36. 
 
 Sea, Bottles and Currents at, 172. 
 
 Sea, Bottom of, a burial-place, 177. 
 
 Sea, Circulation of the, 170. 
 
 Sea, Climates of the, 170. 
 
 Sea, Deep, Life of the, 174. 
 
 Sea, Greatest ascertained Depth 
 of, 175. 
 
 Sea, Solitude at, 172. 
 
 Sea, Temperature of the, 170. 
 
 Sea, Why is it Salt? 177. 
 
 Seas, Primeval, Depth of, 234. 
 
 Sea-breezes and Land-breezes il- 
 lustrated, 150. 
 
 Sea-milk, What is it? 176. 
 
 Sea-routes, How shortened, 184. 
 
 Sea-shells and Animalcules, Ser- 
 vices of, 234. 
 
 Sea-shells, Why found at Great 
 Heights, 106. 
 
 Sea-water, to imitate, 235. 
 
 Sea-water, Properties of, 179. 
 
 Serapis, Temple of, Successive 
 Changes in, 111. 
 
 Sheep, Geology of the, 138. 
 
 Shells, Geometry of, 232. 
 
 Shells, Hydraulic Theory of, 233. 
 
 Siamese Twins, the, galvanised, 
 203. 
 
 Skin, Dark Colour of the, 63. 
 
 Smith, William, the Geologist, 126. 
 
 Snow, Absence of in Siberia, 159. 
 
 Snow, Impurity of, 158. 
 
 Snow Phenomenon, 158. 
 
 Snow, Warmth of, in Arctic La- 
 titudes, 158. 
 
 Snow-capped Volcano, the, 119. 
 
 Snow - crystals observed by the 
 Chinese, 159. 
 
 Soap-bubble, Science of the, 48. 
 
 Solar Heat, Extreme, 63. 
 
 Solar System, Velocity of, 59. 
 
 Sound, Figures produced by, 28. 
 
 Sound in rarefied Air, 27. 
 
 Sounding Sand, 27. 
 
 Space, Infinite, 86. 
 
 Speed, Varieties of, 17. 
 
 Spheres, Music of the, 55. 
 
 Spots on the Sun, 67. 
 
 Star, Fixed, the nearest, 78. 
 
 Stars' Colour, Change in, 77. 
 
 Star's Light sixteen times that of 
 the Sun, 79. 
 
 Stars, Number of, 75. 
 
248 
 
 INDEX. 
 
 Stars seen by Daylight, 102. 
 
 Stars that have disappeared, 76. 
 
 Stars, Why created, 75. 
 
 Stereoscope and Photograph, 47. 
 
 Stereoscope simplified, 47. 
 
 Storm, Impetus of, 164. 
 
 Storms, Kevolving, 164. 
 
 Storms, to tell the Approach of, 
 163. 
 
 Storm-glass, How to make, 164. 
 
 Succession of Life in Time, 128. 
 
 Sun, Actinic Power of, 62. 
 
 Sun and Fixed Stars' Light com- 
 pared, 64. 
 
 Sun and Terrestrial Magnetism. 64. 
 
 " Sun Darkened," 64. 
 
 Sun, Great Size of, on Horizon, 61. 
 
 Sun, Heating Power of, 62. 
 
 Sun, Lost Heat of, 103. 
 
 Sun, Luminous Disc of, 60. 
 
 Sun, Nature of the, 59, 238. 
 
 Sun, Spots on, 67. 
 
 Sun, Translatory Motion of, 61. 
 
 Sun's Distance by the Yard Mea- 
 sure, 66. 
 
 Sun's Heat, Is it decreasing ? 65. 
 
 Sun's Kays increasing the Strength 
 of Magnets, 196. 
 
 Sun's Light and Terrestrial Lights, 
 61. 
 
 Sun-dial, Universal, 65. 
 
 TELEGRAPH, the Atlantic, 226. 
 
 Telegraph, the Electric, 220. 
 
 Telescope and Microscope, the, 38. 
 
 Telescope, Galileo's, 93. 
 
 Telescope, Herschel's, 95. 
 
 Telescope, Newton's first Reflect- 
 
 Telescopes, Antiquity of, 94. 
 
 Telescopes, Gigantic, proposed, 99. 
 ing, 94. 
 
 Telescopes, the Earl of Rosse's, 96. 
 
 Temperature and Electricity, 208. 
 
 Terrestrial Magnetism, Origin of, 
 200. 
 
 Thames, the, and its Salt-water 
 Bed, 182. 
 
 Threads, the two Electric, 215. 
 
 Thunderstorm seen from a Bal- 
 loon, 169. 
 
 Tides, How produced by Sun and 
 Moon, 66. 
 
 Time an Element of Force, 19. 
 Time, Minute Measurement of. 
 
 194. 
 
 Topaz, Transmutation of, 37. 
 Trilobite, the, 138. 
 Tuning-fork a Flute-player, 28. 
 Twilight, Beauty of. 148. 
 
 UNIVERSE, Vast Numbers in, 75. 
 Utah, Salt Lake of, 113. 
 
 VELOCITY of the Solar System, 59. 
 Vesta and Pallas, Speculations on, 
 
 82. 
 
 Vesuvius, Great Eruptions of, 119. 
 Vibration of Heated Metals, 188. 
 Visibility of Objects, 30. 
 Voice, Human, Audibility of, 27. 
 Volcanic Action and Geological 
 
 Change, 118. 
 
 Volcanic Dust, Travels of, 119. 
 Volcanic Islands, Disappearance 
 
 of, 117. 
 Voltaic Battery and the Gymno- 
 
 tus, 206. 
 
 Voltaic Currents in Mines, 206. 
 Voltaic Electricity discovered, 205. 
 
 WATCHES, Harrison's Prize, 229. 
 
 Water decomposed by Electricity, 
 208. 
 
 Water, Running, Force of, 114. 
 
 Waters of the Globe gradually de- 
 creasing, 113. 
 
 Water-Purifiers, Natural, 234. 
 
 Waterspouts, How formed in the 
 Java Sea, 160. 
 
 Waves, Cause of, 1 83. 
 
 Waves, Force of, 184. 
 
 Waves, Rate of Travelling, 183. 
 
 Wenham-Lake Ice, Purity of, 
 161. 
 
 West, Superior Salubrity of, 150. 
 
 " White Water," and "Luminous 
 Animals at Sea, 173. 
 
 Winds, Transporting Power of, 
 163. 
 
 Wollaston's Minute Battery, 204. 
 
 World, All the, in Motion, 11. 
 
 World, the, in a Nutshell, 13. 
 
 Worlds, More than One, 56. 
 
 Worlds to come, 58. 
 
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26 W. KENT AND CO.'s CATALOGUE. 
 
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 [86, FLEET STREET, AND 
 
W. KENT AND CO.'s CATALOGUE. 29 
 
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 Cassell's Lessons in Latin : Being an Elementary Gram- 
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 J. R. BEARD, D.D. Reprinted from the " Popular Educator." 
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 A Key to Cassell's Lessons in Latin: Containing 
 
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 By Professors E. A. ANDREWS and S. STODDARD. Revised and 
 Corrected. Price Is. paper covers, or Is. 6d. neat cloth. As a 
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W. KENT AND CO.'s CATALOGUE. 31 
 
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W. KENT AND CO.'S CATALOGUE. 33 
 
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 G9 
 
 INDEX. 
 
 Acting Charades 
 
 Algebra (Cassell-s) .... 
 Architectural Works . . . 
 Arithmetic (Cassell's) . . . 
 
 for the Young . . 
 
 Arnold's (Edwin) Poems . . 
 
 Astronography 
 
 Balance of Beauty .... 
 
 Ball Koom Polka 
 
 Preceptor . . . 
 
 Beattie and Collins .... 
 Bertie's Indestructible Books 
 Bible Gallery 
 
 Women of the 
 
 Bingley's Tales 
 
 Biographical Dictionary .... 
 Boat (The) and the Caravan . . . 
 Book and its Story 
 
 of the Months 
 
 Boswell's Johnson 
 
 Botany, The Outlines of .... 
 
 Boyhood of Great Men 
 
 Boy Princes 
 
 Boy's Own Book 
 
 Treasury . 
 
 Brandon's Architectural Works . 
 British Empire, Greatness of the 
 Bunyan's Pilgrim's Progress . . 
 
 Byron Beauties 
 
 Illustrated ...;.. 
 
 Capern's Poems 
 
 CasselTs Educational Works . . . 
 Cheever's Whaleman's Adventures . 
 
 Childs' Drawing Books 
 
 Child's First Lesson Book .... 
 Christian Graces in Olden Time . 
 Christmas with the Poets .... 
 
 Classical Library 
 
 Colling's Gothic Architecture . . 
 
 Ornament . . . 
 
 Comic Works 
 
 Almanack 
 
 Comical Creatures from Wurtenu 
 
 burg . . . 
 
 People 
 
 Story Books 
 
 Cottage Gardener's Dictionary . . 
 
 Cow per 's Poems 
 
 Cracker Bon-Bon for Christmas . . 
 Cropland s Memorable Women . . 
 Cruikshank's (Geo.) Works . . . 
 
 . Fairy Library. 
 
 Curiosities of Modern Travel . - . . 
 
 Dale's Poems 
 
 De Lplme's French Manual . . . 
 Dibdin's Water Colours .... 
 
 Easy Drawing Book . . 
 
 Dictionaries 
 
 10 
 
 "7 
 H 
 
 51 
 9 
 
 36 
 11 
 
 11 
 o 
 
 22 
 -1 
 4 
 21 
 33 
 19 
 
 yo 
 
 24 
 24 
 32 
 
 6 
 
 6 
 
 19 
 20 
 
 7 
 34 
 
 3 
 ' 3 
 
 3 
 
 10 
 26 
 10 
 23 
 20 
 
 3 
 
 1 
 CO 
 
 PAGE 
 
 Domestic Architecture 8 
 
 Hints 24 
 
 Drawing Books ,23 
 
 Edgar's Boyhood of Great Men . . 18 
 
 Foot prints of Famous Men 18 
 
 Boy Princes 18 
 
 History tor Boys .... 18 
 
 Educator, The Popular .... 26 
 
 Biblical . . . .26 
 
 Historical . . .26 
 
 The Child's ..... 31 
 
 Emma de Lissau ....... 20 
 
 England, Cassell's History of . . 82 
 History of ...... 33 
 
 38 
 30 
 
 -- ('1 he) Language, its Ele- 
 ments and Form ...... 32 
 
 Etiquette for the Ladies .... 11 
 
 Gentlemen .... 11 
 
 of Courtship ..... 11 
 
 English without a Master . 
 
 Cassell's Lessons in . 
 
 Euclid, Symbolical ...... 24 
 
 Cassell's ....... 31 
 
 Fables of JEf 
 
 Footprints of Famous Men . . 
 
 Footprints of Travellers . . . 
 Ford's Easy Lessons in Landscape 
 
 French, Cassell's Lessons in . . 
 
 Dictionary, Caseell's . . 
 
 Miniature . 
 
 without a Master 
 
 France, The History of ... 
 Games for Christmas .... 
 Geography, Cassell's Elementary 
 German, Cassell's Lessons in 
 
 Dictionary (Cussell) 
 
 without a Master 
 
 15 
 G 
 
 34 
 23 
 27 
 
 27 
 18 
 
 31 
 10 
 31 
 28 
 28 
 38 
 Glennys Handbook to 1- lower-garden 25 
 
 Catechism of Gardening . 25 
 
 Garden Almanac ... 25 
 
 Glossary of Architecture .... 8 
 
 Goldsmith's Works 24 
 
 Graces, Gallery of the 4 
 
 Greek, Cassell's Lessons in ... 30 
 Orimm's Household Stories ... 19 
 Guizot's Young Student .... 20 
 Gutch's Scientific Pocket Book . . 12 
 Handbook of Pencil Drawing . .23 
 Harding's Drawing Books . . 8, 23 
 
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