April 28, 1898] 



NATURE 



605 



Seeliger, it is admitted, has by his suggestions and 

 revision materially improved the chapter on gravity. If 

 the section on telescopes had also been overlooked by a 

 competent authority, perhaps Herschel's giant telescope 

 would have been erected at Slough rather than at Bath ; 

 but wherever these eminent authorities have co-operated 

 with the author, it is needless to say that we have an 

 admirable result, correct in all important particulars. 



As an example of the character of the second part of 

 the work, entitled " Motion of the Celestial Bodies," we 

 select the chapter on the figure of the earth. We make 

 this selection the more readily because it affords an apt 

 instance, not only of the successful treatment of a difficult 

 subject, but illustrates the thoroughness attempted in 

 German popular works. In English books of similar 

 character the tendency is rather to adhere to subjects that 

 lend themselves to pictorial illustrations of an interesting 

 kind, or are capable of easy description, making no great 

 demand upon the attention. Sir Robert Ball, it is true, 

 has given us some charming chapters on the wanderings 

 of the Pole, but writers who wield a less facile pen have 

 generally left the subjects connected with geodetic 

 measurements severely alone. In the Ipswich Lectures, 

 Airy taught us how a base line was measured, and how 

 triangulation was effected ; but his example has not been 

 generally followed. Newer methods and more sensational 

 results have swallowed up the interest that once belonged 

 to the science of exact measurement. But to Dr. Meyer 

 the subject is not unwelcome. Adhering to his general 

 plan of first showing the main principles underlying any 

 process, without introducing needless niceties invented 

 to provide against sources of error, he keeps the attention 

 of the reader fixed on the main object of the investigation, 

 without being lost in the intricacies of detail. In this 

 way we see how latitude and longitude are determined, 

 the gradual elimination of errors from the observations, 

 and the regular approach to scientific accuracy. There 

 is nothing wearisome in the account of triangulation, for 

 it is brightened and relieved here and there by references 

 to ancient history, to past expeditions, and the results of 

 previous measurements. As might be anticipated, one 

 does not find much reference to English work, that is 

 not the object of the book ; it is not the history of results, 

 but the history of methods that is under consideration, 

 and the countryman of Bessel can find all he wants in 

 the writings of that astronomer and in the work of the 

 " Europaischen Gradmessung." The deviations of the 

 earth's figure from that of the surface of an ellipsoid of 

 revolution, and the variation of gravity with the causes 

 that contribute to it, are set out in great detail, showing 

 that the author expects an audience of very considerable 

 intelligence to follow him. This is a point that constitutes 

 for us the real interest of the book, the evidence it affords 

 of the existence of more general information than is 

 usually to be met with in English readers. The author 

 must have been aware of the eagerness of a large class 

 to possess exact information, and has catered for it ; but 

 we cannot imagine that this book would enjoy a very 

 large circulation in this country. Between the mathe- 

 matical reader and the "man in the street" there is a great 

 gulf fixed, which works of this character are calculated 

 to bridge, but which at present find no great support from 

 either description of reader. W. E. P. 



NO. 1487, VOL. 57] 



OUR BOOK SHELF. 



La Vie: Mode de Mouvement. Essai dune Th^orie 

 Physique des Phenomenes Vitaux. Par E. Prdaubert, 

 Professeur an Lyc^e d' Angers, &c. Pp. 310. (Paris r 

 F^lix Alcan, 1897.) 



We can hardly suppose that M. Pr^aubert intends his 

 remarkable speculation to be taken seriously. His con-^ 

 tention is that life is essentially a mode of motion of the 

 ether, and as such is closely allied with electricity and 

 magnetism ; finding, like these forces, its expression but 

 not its origin in ponderable matter. It is, he maintains, 

 in consequence of the failure to recognise the ether as 

 the true seat of vital activity that all attempts to explain 

 the phenomena of life on a purely chemical or physical 

 basis have hitherto broken down. With the removal of 

 " vitality " to the region of the ether, the material diffi- 

 culties vanish ; the connection between vitality and the 

 other forces of the physical universe becomes declared, 

 and biology resolves itself essentially into a mere ques- 

 tion of mechanics. What then is the true distinction^ 

 between life, on the one hand, and light, radiant heat 

 and electricity on the other ? The author answers that 

 life is a series, not of vibrations, but of vortex-move- 

 ments ; his discovery, in fact, could hardly be better 

 expressed than in the words of the puzzle-headed old 

 Athenian in the " Clouds " — 



It need, perhaps, scarcely be said that in support of his- 

 central position he has nothing to offer but a collection 

 of assumptions and analogies, the former practically 

 baseless, and the latter more or less loose. He seems,, 

 indeed, to forget in practice, though he recognises in. 

 words, the distinction between analogy and identity ; 

 and anything deserving the name of proof is conspicuously 

 lacking. Space will not allow us to deal with his state- 

 ments in detail ; he commits himself to many that would, 

 be called in question by both physiologists and mor- 

 phologists. We cannot, however, refrain from express- 

 ing our wonder that so many writers on evolution should' 

 virtually ignore the firm foundation laid by Darwin. So 

 far as M. Preaubert's biological arguments are con- 

 cerned, the theory of natural selection might almost as 

 well be non-existent. 



We doubted at the outset whether the author expected! 

 to be taken seriously. His closing passage contains 

 what is in effect a reductio ad absurdum of his whole- 

 theory. F. A. D. 



The Barometrical Determination of Heights. By F. J. B. 



Cordeiro, Surgeon U.S. Navy. Pp. 28. (London : 



E. and F. N. Spon, Ltd., 1898.) 

 In the calculation of mountain heights by means of the 

 mercurial barometer, accuracy depends on the efficiency 

 of the formulae employed. These formula? are based 

 necessarily on assumptions, as we do not know exactly 

 the varying conditions of the air, and we therefore fail 

 to take into account the exact data for the correct solu- 

 tion of the problem. As a rule, the formulae are at most 

 only approximations ; but it is astonishing what goodi 

 results niay be obtained by paying strict attention to all 

 details. 



In this neatly bound little book we have an essay on. 

 this subject, which was originally entered in the Hodgkin. 

 Prize Competition under the auspices of the Smithsonian 

 Institution, and was awarded honourable mention. The 

 author has briefly brought up to date the problem of 

 barometrical hypsometry discussed many years ago by 

 Guyot. He points out where the old theories were lack- 

 ing in accuracy, and furnishes a method which, besides 

 being rigidly correct in theory, gives trustworthy results in 

 practice. As an illustration of this, a series of observations^ 

 is added. In the appendix the author describes a form o£ 



