July i, 1897] 



NATURE 



»95 



force, and the two corresponding gravitational systems 

 are well illustrated by problems introduced, throughout 

 the mechanics section, among those on C.G.S. measure- 

 ments. 



This takes us as far as is at present, perhaps, possible 

 in the direction of a compromise to which many teachers 

 of physics are now looking forward — the recognition, 

 namely, of two distinct systems of measurements only ; 

 one the C.G.S. with its derived practical system, for 

 scientific and electrical purposes, the other the system 

 used by engineers, and based on the units of length, 

 time, s.x\^ force. 



Among other noteworthy features is a good set of 

 problems on dynamos and alternating currents, another 

 on wave and harmonic motions in connection with sound, 

 and a third on gravitational potential in the section on 

 work and energy. Less commendable, however, is the 

 reference to water-levels in connection with electrical 

 potentials. The most perfect " water analogy," and the 

 one which, in our experience, appeals most directly to 

 students, is that in which conductors are represented by 

 water-filled cavities in a large block of india-rubber ; it 

 affords, indeed, almost the only means of enabling the 

 average beginner to realise how the potential of a body 

 or of a point in space may be altered by altering the 

 charge on another body at a distance. 



It is a pity that those problems which adm.it of solu- 

 tions are not all supplied with them. Many are of the 

 nature of examination questions, requiring long answers 

 in words, and to these, naturally, no answers are given ; 

 but of the rest, not more than about three-fourths are 

 solved. 



We have noticed the following slips. The answers to 

 Nos. 251, 759, 775, 776, 837 are either wholly or par- 

 tially wrong ; in No. 607 the water-worth of the dish 

 should be given ; and the headings to pp. 204 and 221 

 want altering. These are, however, small blemishes on 

 an otherwise very useful work. A. P. C. 



COSMIC ETHICS. 

 Cosmic Ethics ; or., the Mathematical Theory of Evolution. 

 By W. Cave Thomas. Pp. xxii -I- 296. (London : 

 Smith, Elder, and Co., 1896.) 



IN styling his book " Cosmic Ethics," Mr. Cave Thomas 

 means to imply that not only in morals as a depart- 

 ment of " the wider hygiene," but throughout the universe, 

 there is but one law of rightness, that of balance, propor- 

 tion, or the mean. By "mathematical evolution" he 

 desires to signify that evolution is "the becoming of the 

 proportioned," its goal being "the at-mean-ment of 

 nature." 



Starting from the admitted applicability of the idea of 

 quantity throughout the concrete world, and from the 

 progress which the sciences undoubtedly make when 

 measurement or quantitative formulae can be used in 

 them, Mr. Thomas advances to an apotheosis of the 

 average, and offers principia of the science of proportion 

 and applications of quantification throughout the whole 

 range of human knowledge. By somewhat elementary 

 numerical formuhe we can determine the beau-ideal in 

 the arts, attain to a quantitative ethic, discover that a 

 man ought to drink neither too much nor too little, that 

 NO. 1444. VOL. 56] 



his morning tub should not vary much in temperature 

 from that of the human body, that the combination of 

 great athletic and great intellectual effort leads to a 

 break-down, and that technical and specialist education 

 is inferior to general education. 



Of the principia we may quote as an instance : " The 

 mean of fraction \% \\ it is the fraction which is equally 

 indifferent to the two extreme fractional limits of \ and 

 J." (I) Of the exemplifications of the formuhe, we may 

 point out that they are purely arbitrary. We ought to aim, 

 we are told, at not diverging from the average, which is the 

 ideal, to any extent which carries us beyond the middle 

 third of our scale. Why not the middle fifth or seventh? 

 There is no attempt to point out how the qualitative kind 

 to which any particular scale is applicable is determined, 

 and this despite of the fact that in a quotation which he 

 makes from Reynolds — one of a constantly recurring set 

 of quotations — that point is definitely raised. 



Mr. Thomas accepts the Darwinian theory, though 

 how the importance which that theory ascribes to "acci- 

 dental variations " from type, can be reconciled with his 

 own views as they stand, it is difficult to see. In fact, 

 as they are here put before the reader, Mr. Thomas's 

 doctrines will not allow of being harmonised into an 

 intelligible system. This is the more to be regretted, as 

 there is no doubt that an adequate elucidation of the 

 theory of quantity, number, and measurement, would be 

 of very great service to applied science. Nay, it is 

 perhaps not too much to say that from the Gallon 

 system of composite photography, and from the statis- 

 tical results of anthropometry, to which the author refers, 

 conclusions of considerable value for art may be drawn. 

 But they are not those drawn by Mr. Cave Thomas, nor 

 to be drawn by his methods ; though his considerable 

 judgment in art and his grasp of the distinction between 

 the organic fitness of an object for its purpose and its 

 appositeness to human taste, make this department of his 

 investigations the least unpromising. 



His quotation of the headings of the chapters in 

 Aristotle syggests the suspicion that Mr. Thomas has 

 not studied that author in the Greek. Otherwise the 

 attribution to him of a system of quantitative ethics 

 would be, despite of the great authorities for that view, 

 less pardonable than it is. Yet to the Greeks Mr. 

 Thomas has chosen to go in his quasi-Pythagorean 

 glorification of quantity. H. W. B. 



OUR BOOK SHELF. 

 The Flora of the Alps. By Alfred W. Bennett, M.A., 



B.Sc, F.L.S. 2 vols., with 120 coloured plates. Pp. 



x.xii -I- 165 ; vi -I- 223. (London : J. C. Nimmo, 1896.) 

 The Alpine wanderer will not be very grateful to Mr. 

 Bennett and his publishers for this new " Flora of the 

 Alps." The net is spread widely ; for, in addition to the 

 whole Swiss flora, there are included here plants from 

 adjacent mountain districts, and also the Pyrenees. The 

 result is a rather cumbrous affair, and yet unsatisfying in 

 detail. The species of each genus are enumerated with 

 very short and sometimes rather inadequate characters, 

 so that the identifying of specimens is not always as easy 

 as it might be. That the book is arranged according to 

 the system of Bentham and Hooker we may regard as a 

 welcome innovation in Alpine floras, which have been 

 too long wedded to the irritating Linnaean system. The 



