Feb. 1, 1886.] 



KNOWLEDGE ♦ 



113 



does Mr. Crookes sustain his reputation in tlie tine voiume 

 before us, to the value and excellency of which probably 

 no more appreciable testimony could be offered than that 

 afforded by the fact that (addressinjj, as it does, a com 

 paratively limited public) it has already run into a secoinl 

 edition. For this is by no means an ordinary text-bocik, 

 exhaustively describing the everyday work of the general 

 analyst, but rather a laboratory companion for the ad- 

 vanced chemist, containing information to be sought in 

 vain in anj- of the numerous works usually employed by 

 the student. Not that the processes described in such 

 detail are of necessity in themselves diiBcult ; some 

 of them, in fact, beint^ a-s remarkable for their sim- 

 plicity as for their elegance ; but easy or operose 

 they one and all represent the latest developments 

 of the science of analysis, and show how it may be con- 

 ducted with the greatest certainty of attaining accurate 

 results. The various methods of separating the metal 

 Thallium, for example, from the substances with which 

 it is most frequently found in combination, will interest 

 all those who remember that the description of such 

 methods are written by the man to whom we are 

 indebted for the original discovery of the existence if 

 Thallium itself. Very full directions, too, are ijiven 

 for the separation of others of the rarer elements. 

 Some portions of Mr. Crookes's volume may fairly be 

 described as indispensable to all engaged in the pursuit 

 of chemistry ; such, for examj^le, as his elaborate direc- 

 tions for the rigidly-correct adjustment of weights, and 

 his admirable resume of various artifices in use in the 

 laboratory, which appear near the end of the book. As 

 an illustration at once of elegance of method and extreme 

 delicacy of reaction, we would instance the account of some 

 recent modes adopted for the detection of very minute 

 quantities of iodine, given on p. 560 et seq. Assuredly 

 this is a book without which no chemical library can be 

 considered in any sense complete. 



An Enormous Granite Slab. — To separate from the 

 main ledge a slab of granite 3-54 feet long, three to four 

 feet thick, and eleven feet wide, is no ordinary feat to 

 accomplish. But this has been done at the Flynt Granite 

 quarry, in Monson, Mass., and by the means usual in all 

 quarries for separating slabs or blocks from the main 

 ledge. A row of wedges were set, several hundred in 

 number, and the workmen beginning at one end crentlv 

 and carefully tapped the wedges, moving by degrees 

 down the line, until the other end of them was reached, 

 when the same operation was repeated. In this manner, 

 by careful and patient application, aided by favourable 

 conditions of the weather, the slab C'f the above pheno- 

 menal size was successfully separated from the main 

 rock. The value of this immense slab, if it could have 

 been transferred safely to one of our large cities, at not 

 too great cost, would have been several thousand dollars. 

 And it seemed almost sacrilegious that it was necessary 

 to cut it up into smaller blocks for transportation — and 

 finally used for ordinary building purposes. The possi- 

 bility of getting out a slab of such size without breaking 

 it indicates that the grain of the Monson granite not only 

 runs evenly, but that it possesses great tenacity. 



RoYAi, VicTOBiA Hall axd Coffee Taveen, Watebloo 

 Bbidge-hoad, S.E.— The Penny Science Lectures will shortlj 

 recommence at the above hall. The following are promised — 

 Taesday, Feb. 2, W. P. Bloxam, Esq., on •' Fire. Fuel, and lUumina- 

 tion." Feb. 9, J. JI. Thomson, Esq., on " Dirty Water and how to 

 Cleanse it." Feb. 16, Professor George Forbes, on " .■^hooting Stars 

 and Comets." Feb. 23, Wm. Lant Carpenter, Esq. March 2, T. C. 

 Porter, Esq., on •' English Cathedrals." March <i, Dr. J. A. Fleming, 

 on " Niagara." 



THE STORY OF THE EARTH.* 



EOLOGT shares with astronomy the inte- 

 rest arising from the study of the life of 

 worlds. In the star-depths we see un- 

 counted millions of suns of many order.=, 

 — in size, in structure, and in condition, 

 — but each probably like our own in 

 being the centre of its family of planets. 

 In our stm we study the one star near enough 

 to present to us the general features of sun-life. 

 In the solar system we see many planets, divisible into 

 different orders, whether we consider them in regard to 

 size and mass, or to age and condition. And lastly in 

 otu" own earth we study the one planet near enough to 

 admit of being thoroughly examined as regards its pre- 

 sent condition, affording evidence of great interest also 

 as to its past state, and telling us much even of its pro- 

 bable future. It is not only true that the study of 

 astronomy would be as incomplete without geology 88 

 the study of the stellar universe without the fullest 

 inquiry into solar physics, but it may be said that in 

 the study of the earth we have the fullest and most com- 

 plete evidence respecting planetary orbs, bodies which 

 probably outnumber many times the millions of suns 

 throughout the universe. 



Thus the student of astronomy, after examining the 

 general evidence afforded in the star-depths respecting 

 the nature and distribution of suns (our own sun being 

 his sample star) and inquiring further into the general 

 evidence afforded within our solar system respecting the 

 nature and distribution of worlds, turns to his fellow- 

 worker, the student of geology, to tell him all that has 

 been learned about otu- own world, its present condition 

 (in air, land, water, and beneath its crust), its past 

 history and its probable future. The position of the two 

 studies, astronomy and geology, has thus been com- 

 pletely altered from what it was in past ages, when men 

 in no sense regarded our earth as one among the bodies 

 circling round the sun, or the sun, moon, planets, and 

 stars, as orbs comparable with the earth in importance. 

 Then the study of astronomy was chiefly important as 

 throwing light on the nature of the orbs fashioned in the 

 beginning to serve the earth, to be her light by day and 

 her light by night, to be for signs and for seasons, and 

 for days and years. It would have seemed inconceivable 

 in those days that the time would ever come when the 

 sun and moon, the stars and the planets, would in part be 

 studied for the information which they can throw upon 

 the present constitution, the past history, and the future 

 fate of the earth, in those days regarded as infinitely 

 more important than any of the heavenly bodies. It 

 would have been equally inconceivable, also, that the 

 earth would ever be studied for the information it could 

 give as to the heavenly bodies, then regarded as entirely 

 different from the earth in nature. 



The study of the earth by the geologist is necessarily 

 associated with the study of other worlds by astronomers. 

 As Mr. Geikie remarks in the admirable work which is 

 now before us (in a new and improved edition) "whatever 

 is ascertainable by telescope, spectroscope, or chemical 

 analysis, regarding the constitution of the other heavenly 

 bodies, has a geological bearing."' In particular, it is 

 important to the geologist to inquire whether the various 

 orbs forming our solar system (the only region where we 

 can look for actual worlds) are all alike, in constitution 

 and condition. If he shall fuid reason to think they are 



*" Text-Book of Geology." By Archibald Geikie. Second 

 Edition. (London : Macmillan & Co.) 



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