January 30, 1896] 



NATURE 



293 



astronomical interpretation." For example, the story of 

 the halcyon days is hypothetically explained in this way : 

 it " originally referred to some astronomical phenomenon, 

 probably in connection with, the Pleiades, of which con- 

 stellation Alcyone is the principal star ".(p. 31). A criticism 

 of any one such explanation would be impossible in a 

 limited space, even if the present writer were qualified 

 to undertake it. Suffice it to say, that even if it could be 

 proved that every one of these interpretations is wrong, 

 and that simpler methods are applicable, yet credit would 

 be still due to the man who indicated a possible way of 

 dealing with these difficulties, and one which would not 

 be likely to occur to the ordinary book-scholar. We must 

 of course be on our guard against the danger of missing 

 our footing while we thus gaze into the heavens for a 

 missing clue ; but I venture to say that any one who 

 will carefully study the whole of the passage from 

 which a sentence was just now quoted, or that in which 

 is discussed the fable of the Swan and the Eagle, will 

 hardly avoid the conclusion that there may be an astro- 

 nomical aspect of the folk-lore of some peoples, which 

 has still to be scientifically investigated. 



In conclusion, it may be asked what contribution there 

 is in this volume to zoological science. Positively and 

 directly, there cannot well be any ; the identification of 

 species is in most cases too doubtful to allow us to com- 

 pare them with those now familiar to us in regard to 

 distribution, migration, nesting habits, &c. But, as a 

 contribution to the history of the science, this book will 

 be of great value, and the future editor of Aristotle's 

 Hisioria animalium will find himself relieved by it in 

 many particulars from a great deal of tedious research. 



The revision of the proofs has evidently been carried 

 out with scrupulous care — no easy task, considering the 

 innumerable proper names and Greek quotations ; and 

 the accentuation of Greek words seems to be remarkably 

 accurate. In a few unimportant points, I should differ 

 from the author's views ; but of these I will only mention 

 one, about which I am confident. He declines to identify 

 Aristotle's aypivikos as the reed bunting, on the ground 

 that that species {Emberiza schaeniclus) does not flick its 

 tail as other buntings do. But the reed bunting does?^\(^ 

 its tail, as I have every reason to know, and I believe 

 the old identification to be probably right. I may just 

 add that I see no difficulty in identifying Aristotle's 

 Kvavo'i with the wall-creeper, though he says that it is 

 Kvavovi oXof ; for the Greeks were weak in discriminating 

 colours, and I can testify that it is not so easy as one 

 might expect to catch the crimson of the wing-coverts 

 when the bird is on a rock high above you. And it is 

 not likely that the Greeks should have been able to 

 procure specimens of this shy species for closer ex- 

 amination. W. W.4RDE Fowler. 



OUR BOOK SHELF, 

 Polyphase Electric Currents and Alternate Current 



Motors. By S. P. Thompson. (London : E. and F. 



N. Spon, 1895.) 

 This book resembles others by the same author, in being 

 an amplification of a course of lectures. Every one who 

 knows Prof Thompson's later work, will expect to find 

 evidence of a good deal of study ; nor will he be dis- 



NO. 1370, VOL. 53] 



appointed. Not the least important part of the book is 

 the list of works and articles which have been written 

 upon this comparatively new department of electrical 

 engineering. A chapter and many other paragraphs are 

 of an historical nature, and if in some cases those who 

 have been behind the scenes more than the author, may 

 consider that he has not been quite fair in his conclusions, 

 yet every one will admit that impartial fairness has always 

 been aimed at by Prof Thompson. 



Here and there a little more care might have been 

 exercised. On p. 24 the lettering on Fig. 28 is wrong. 

 j The views of M. Goerges on the comparative economy in 

 copper when used with one, two, and three phases is not 

 at all clearly put. The author has a liking for new terms^ 

 The " stator " and " rotor " of a dynamo or motor have 

 an unpleasant sound, and are not so good as the French 

 "inducteur" and "induit," but they will serve their pur- 

 pose. *'Star" and "mesh" groupings do not explain 

 their meaning (referring to the connections for a three- 

 phase system) so well as the old and appropriate symbols 

 Y and A- 



The mathematical theory of polyphase systems has 

 been worked out by many writers and on different lines. 

 The method selected by the author has the merit of being 

 simple, and easily followed by those who do not handle 

 mathematics easily. The parts of the book which relate 

 to the design of machinery are not very complete, and 

 would hardly suffice to enable the average electrical 

 engineer to make a good polyphase dynamo or motor. 

 But we must remember that this was a fault of the first 

 edition of " Dynamo Electric Machinery," by the same 

 author, which has steadily improved with each new 

 i edition, and has become one of the leading text-books of 

 I its kind. So, also, we expect that the book before us has 

 j in it at least the germ of a treatise which will be a 

 I standard work of great value as it passes through suc- 

 cessive editions. As it stands, the book should be on the 

 shelves of all those who are engaged in developing that 

 most useful auxiliary of the electrician, a polyphase 

 system for distributing electrical motive power. 



G. F. 



Elementary Physical Geography. By R. S. Tarr, B.S.» 

 F.G.S.A. (New York and London : Macmillan and 

 Co., 1895.) 



The most prominent feature of this book is the wealth 

 and excellence of its illustrations ; in less than 500 pages 

 there are close upon 300 of them, many being new, while 

 numerous others are from official publications which 

 are not accessible to most elementary students. The 

 admirable photographic reproductions, illustrating a 

 great variety of natural phenomena, are especially note- 

 worthy, as are also the illustrative maps. The three 

 main divisions of the book treat of the atmosphere, the 

 ocean, and the land. Strangely enough, " the earth as a 

 planet " falls into the first division, and meteorological 

 instruments and methods are relegated to an appendix. 

 " To present facts and furnish information " is the avowed 

 object of the book, and although it is recognised that 

 "the average mind learns unconnected facts with much 

 less ease than those which are philosophically related," 

 many objections to this method of teaching might be 

 made. One of the defects of the method is the liability 

 to employ terms without sufficient explanation, and we 

 find the author so using the terms " waves of ether," 

 specific heat, density, and temperature. Again, a student 

 would be very much wiser for a demonstration that the 

 air has weight, than for a mere statement of the fact. It 

 is true that the introduction of laboratory and field work 

 is strongly advocated, and some very useful suggestions 

 for such work are made. If the facts and information 

 furnished by the book are supplemented by laboratory 

 and field study, the course may be made one of great 

 educational value. Otherwise, to use the author's words 



