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tissues provided to issue thoughts or actions. The tissues 

 do not suffer by reason of their employment, so long as 

 their nutrition is maintained. Brain and muscle can be 

 very fairly likened to machinery." From this it is evident 

 that the author considers that both mental and muscular 

 activity involve a consumption of nutriment material ac- 

 cording to their amount. Of muscular action this is no 

 do'jbt correct, for the .amount of work performed can be 

 measured by foot-pounds without difficulty ; but as it is 

 inconceivable that we should be able to say that one pound 

 falling through one foot is equivalent to so much thought, 

 or so much of an argument, not because of the difficulty 

 in measuring, but because of the total absence of relation 

 between the one and the other ; so it is necessary to 

 believe that thought is not a mode of motion, is 

 not capable of being correlated with the other physical 

 forces, and does not involve the consumption of nutrient 

 fluid. If the brains of different individuals are compared 

 to running streams, in which the waters exhibit different 

 degrees of clearness, as brains give evidences of differ- 

 ences in quality, their thoughts may be compared to the 

 reflections of surrounding objects on the surfaces of the 

 streams, different in intensity according to the clearness 

 of the water or the quality of the brain cells. Upon this 

 analogy it is evident that the relative intensity of different 

 reflections is not dependent at all on the stream itself, but 

 on the illuminating power of the objects reflected ; in like 

 manner we cannot conceive that the amount of nerve tissue 

 disintegrated by the greatest minds at the time that they 

 are evolving their mightiest thoughts is in excess of that 

 which is wasted during the same time by the most 

 commonplace member of every community. Thought is 

 as intimately connected with the reception of external im- 

 pressions by the healthy human brain as reflections from 

 water are with the illumination of the surrounding 

 objects ; they are involuntary when cause for their deve- 

 lopment is present. 



The chapters on headache and on sleep are amongst 

 those which show how backward is our knowledge of 

 some of the simplest of the phenomena of life. We may 

 be able to recognise that " sick headache" and nightmare 

 have something to do with the presence of indigestible 

 matter in the stomach, but as to the true relation between 

 the two we are still completely in the dark. In speaking of 

 " taking cold " the author tells us that " cold contracts al- 

 most all substances, and when the skin is exposed to its in- 

 fluence the contraction becomes visible to the eye, and the 

 appearance it presents is caWcd goosc'-si in, from its resem- 

 blance to the natural condition 'of the skin of the goose." 

 This will, we fear, mislead those readers who are pure 

 physicists as to what is the index of expansion of skin 

 for heat, the fact being that the cold, by stimulating the 

 small arteries of the coriuni, causes them to contract, and 

 so prevents the blood from entering its substance, whicli 

 gives it the shrunken, plucked-bird like appearance that 

 it presents. We are told also that " no danger need ever 

 be apprehended from the application of cold water . . . 

 to the naked body, if it be made immediately after re- 

 maining some time exposed to a high temperature." With 

 this it is difficult to agree, for the epistaxis, or nose-bleed- 

 ing, which sometimes occurs on entering the cold plunge 

 of the Turkish bath shows that the blood-pressure is 

 thereby suddenly augmented to a degree which cannot 



but be dangerous in some cases, especially when the walls 

 of the arterial system are not as strong as they might 

 be. 



In conclusion we strongly recommend this work to non- 

 professional readers, from the lucid and logical manner in 

 which the physiological problems of everyday life are 

 stated. The public cannot be too forcibly impressed with 

 the importance of removing causes rather than combat- 

 ing effects by direct means, and on these points the 

 authors lay considerable stress. The principles of such 

 subjects as ventilation and gymnastics cannot be too fre- 

 quently taught, and when expounded by writers so capa- 

 ble as those of the work before us they arc doubly 

 impressive. 



OUR BOOK SHELF 



Annual Record of Science and Industry for 1873. 

 Edited by Spencer F. Baird, with the assistance of 

 eminent men of Science. — (New York : Harper and 

 Brothers, 1874.) 



The Year Book of Facts in Science and Art : exhibiting 

 the most important discoveries of the past year. By 

 John Timbs. — (London : Lockwood and Co., 1874.) 



These books, like M. Figuier's "L'Annee scientifique,' 

 give a fair general idea of the progress of Science and 

 the mechanical arts during the year. They are scarcely 

 sufficiently comprehensive and exact for the man of 

 Science, but are decidedly useful for the ordinary well- 

 educated reader, who takes an interest in the discoveries 

 of Science. Mr. Baird's book is perhaps something more 

 than this : it is carefully arranged, and enters into detail 

 in most cases ; it is also preceded by a " General Summary 

 of Scientific Progress," of somewhat more thin a hun- 

 dred pages. From this we learn that five new planets 

 were discovered during 1873 — the last "Sophrosyne" 

 being the 134th in order, starting from " Ceres," which 

 was discovered in iSoi. Seven comets were seen during 

 last year, three of them new ones ; five out of the seven 

 were first seen in Marseilles by those indefatigable ob- 

 servers, Stephan, Coggia, and Borelli. In Physics there 

 appears to have been no discovery of any particular note. 

 In Chemistry the copper-zinc couple of Dr. Gladstone 

 and Mr. Tribe, and its results are described as among the 

 most interesting work of the year. Further on we find an 

 account of the cruise of the Challenger, and favourable 

 mention of Sir William Thomson's suggestions that' 

 steel pianoforte-wire should be used for a sounding line 

 in place of the usual hempen cord, whicli offers far greater 

 resistance, and requires a heavy weight at the bottom. 

 Under the head of " Mechanics and Engineering," we 

 find some interesting statistics of American iron-industry. 

 The production of pig-iron in the United States is esti- 

 mated (for 1873) a-t 2,406,637 gross tons. The total 

 number of furnaces is 636, and their estimated capacity 

 4,371,277 net tons. There are eight Bessemer works in 

 the country, with a total capacity of 170,000 tons. The 

 great Hoosac tunnel, \\ miles long, was completed during 

 the year. In Tinibs' "Year Book" we find too many 

 evidences of careless compilation, and great want of 

 method in grouping the different subjects. We read, 

 " Dr. Odling, President of the Chemical Society, read a 

 paper On the preparation of the Standard Trial plates to 

 be used in verifying the composition of the coinage : '" — 

 the paper was by Mr. Roberts, not Dr. Odling. Among 

 the so-called chemical subjects, we find '" Sunlight for the 

 sick," "Transparent paper," and "Opium-smoking in 

 New York." It is unfortunate also that non-scientific 

 journals are so often made to guarantee scientific facts. 



