Deceubeb, 1902.] 



KNOWLEDGE. 



281 



while, in others, parts of the birds have been cut away in 

 mistake for the background. In this way, many of the i)hoto- 

 graphs have been spoilt, and we need only instance tlie figures 

 opposite to page 4ri, where the legs, beaks, and tails of the birds 

 have greatly suffered by this merciless pruning. We hope that 

 a favourable reception of his book will induce Mr. Sharp to 

 give us further '■ chats " about the birds of his garden, and that 

 no mechanical engraver will be allowed in future to "improve '' 

 the photogra|ihs. 



" ExPKRiMKXTs IN Aeko-dy.namiis.'' By S. P. Langley. 

 (Published by Smithsonian Institution.) — This classical work 

 reappears in a fresh edition, with but little addition to the 

 subject matter as published in IS',11. The central fact, on which 

 depends the importance of the long and exhaustive experiments 

 dealt with, is practiciUy a refutation of the statement found in 

 elementirj' text-books, that if a ball be shot from a cannon 

 horizontally at any given height alx)ve the ground, and if a second 

 ball be dropped vertically at the s;ime instant as the discharge, 

 the two projectiles will reach the ground at the same time. 

 Substituting for the cinnon ball a thin material ])lane projected 

 horizontally in its own plane, Prof. Langley shows that the 

 body behaves almost as though deprived of weight, supplying 

 thereby a phenomenon possibly analogous to that of the rapid 

 skater travelling in safety over thin ice. The general conclusion 

 to which the ma-ster experimentalist is led is that we already 

 possess in steam engines iis now constructed, or in other heat 

 engines, more than the requisite ])Ower to urge a system of rigid 

 jdanes tlu-ough the air at a great velocity, making them not only 

 self-sustaining but capable ot ciirrying other than their own 

 weight. The volume must remain one of the most unique and 

 valuable of the Smithsonian contributions to knowledge. 



"Aerial Navk:.\tion.'' By Frederick Walker. (Crosby 

 Lockwood & Son.) — The author of this unpretending little 

 volume, " the aim of which," we are informed, " is to convey 

 elementary instruction in a popular manner," has succeeded in 

 packing a certain amount of useful and practical matter within 

 its hundred and fifty pages. The opening chapter introduces 

 us to a comparison of the capabilities of winged creatures, from 

 the albatro.ss to the flying fish, and is of a readable nature. The 

 succeeding chapters, however, deiiling with Aerostatics and 

 Aerodynamics, are, unfortunately, difficult to follow, giving the 

 idea of having been compiled in too great haste. In addition 

 to mere slips ot the jien, there are loosely- worded sentences 

 which are ungrammatical or obscure, and instances where 

 formulae are faulty and statements or reasoning inaccurate. As 

 e.\amples we may point to the following : — '' Altitude in feet 

 (A) may be computed from the log. of barometer reading in inches 

 (A) from the formula 4771 - 6 X 6-ilili) X t =: A, where 4771 is 

 M log.," and to a very remarkable sentence or two on page 16. 

 A chapter dealing with air-ships is copiously illustrated and well 

 compiled for the purposes of a technical manual. Whether the 

 little volume will bo found to be really what it professes to be 

 — " a practical handbook on the construction of dirigible 

 balloons, aerostats, &c." — may perhaps be doubted, but it is 

 not without information valuable to the mechanic, and contains 

 useful tables which will be handy for reference. 



■'TnK Primrose and Darwinism.'' By A Field Naturalist, 

 M.A.CCAMB.). xiv. + 'JSS pp. ((xraiit Richiirds.) — It will be 

 admitted that an author sets before himself no easy task when 

 he tries to show that Darwin's famous observations on the 

 cross- fertilisation of flowers were for the most part faulty, and 

 that the accepted theories, based on these observations, are 

 unscientific and absurd. Such, however, is the object of the 

 present book. The author repeatedly criticises Darwin's use of 

 the net to exclude insects from the flowers under observation ; 

 yet he does not, we believe, bring forward any experimental 

 evidence that the net really has the sterilising influence he 

 attributes to it. He is surely acquainted with the method of 

 blank experiment! Similarly, commenting upon Fritz Midler's 

 observations upon orchids, he says the flowers were, " in all 

 probability, under jirotection in a greenhouse," and then 

 proceeds to criticise the "probable' conditions of the experi- 

 ments. Further, in face of Darwin's explicit statement that 

 " the cowslip is habitually visited during the day by the larger 

 humble-bees, and at night by moths,'' the critic includes the 

 cowslip in a list of "a dozen of our brightest and most con- 

 spicuous common flowers which are rarely, and in some cases 



never, visited by bees at all." It is interesting, therefore, to 

 find the anonymous author declaring that " for Darwin to sot 

 up as a juilgo in Nature's divorce court . . . transgresses a little, 

 wo think, the bounds of modesty.'' In sjiito of the flaws wo 

 have indicjited, we believe Darwin would have been the first to 

 welcome this volume. It at least makes clear the necessity for 

 further investigation of the subject. The twenty-three illustra- 

 tions arc admirable. 



"Astronomy with ax Oi'i'.RA-fJi.ASs. A Popular Intro- 

 duction to the Study of the Starry Heavens with the Simplest 

 of Optical Instruments." By Garrett P. Serviss. Eighth 

 Edition, (llirschfeld Brothers.) — This is a re-issue of the eighth 

 edition, published by D. Appleton and Co. in Ig'.'G. Instead 

 of the dark-blue cover of the earlier book, where fair Andro- 

 meda hangs chained in a starry sky, and a pair of opera-glasses 

 occupies the right-hand corner of the foreground, the volume 

 is now clothed iu green with a picture of Saturn and his Kings, 

 in exact conformity with "The Pleasures of a Telescope,' and 

 " Other Worlds,'' by the same author. This cover is not so 

 appro])riato to this book as to the others, since Saturn offers no 

 opportunities to the astronomer with an opera-glass, save that 

 of tracing his slow motions through the stars. Those who have 

 read anything from Mr. Serviss' pen will not need any recom- 

 mendation of the jirescnt volume. His close acquaintance with, 

 and enthusiasm for his subject, his fresh and easy style, render 

 all his writings attractive, and he is especially at home in the 

 subject of this present volume. He has not confined himself 

 in it to a mere description of the objects as they may be seen 

 with a binocular, but has supplemented it by what has been 

 learned concerning them by means of more powerful instru- 

 ments, and by the histories, folk-lore, and traditions that have 

 come down to us concerning them. Perhaps the most inte- 

 resting account in a book where there is nothing dull is that 

 of the Pleiades. He relates the traditional or proved changes 

 in the brightness of the various stars and of the nebula ; of 

 Merope, who married a mortal and whose star therefore became 

 dim amougst her sisters; of Eleclra, whose tears at the burning 

 of Troy blotted out her star ; of Asterope, the reputed spouse 

 of Mars. Electra is now the brightest star of the group save 

 Alcyone ; Asterope is only visible in the glass ; whilst iterope 

 now shines plainly to be seen with the naked eye. And from 

 this Mr. Serviss deduces the quite unastronomical moral that, 

 " notwithstanding an occasional temporary eclipse, it is, in the 

 long run, better to marry a plain mortal than a god." In this 

 new issue it is to be regretted that no notice is taken of the 

 changes of the new star in Perseus, nor of the great naked-eye 

 comet of PJOl, both of which offered good fields for observation 

 with the opera-glass. 



"Index to the Literatcre of the Spectroscope (1887- 

 mOlt, BOTH iNri.usiVE)." By -\lfi-ed Tuckerman. 1<H)2. — This 

 is one of the Smithsonian Miscellaneous Collections, and is a 

 continuation of the ])revious Index by the siime author pub- 

 lished in 1888. It consists of two parts — Author-Index and 

 Subject-Index. The preparation and publication of these 

 bibliographies places the student under a very heavy debt to 

 Mr. Tuckerman. There seems, however, one criticism to be 

 made on the manner in which Mr. Tuckerman has carried out 

 his task — viz., that the papers catalogued are by no means 

 confined to spectro.scopy, but embrace a considerable number 

 relating to general astronomy, selected without any obvious 

 pur])ose, and, in many cases, not even remotely connected with 

 the title of the bibliography. This is a pity, as, on the one 

 hand, it unduly swells the book, and may often cause the 

 student to refer to papers that have no reference to his special 

 line of research, whilst, on the other hand, it entirely fails to 

 fill the larger ]>rogramme of a bibliography of astronomy as a 

 whole. 



" Manual of Astronomy." By Prof. C. A. Young, pii.d., 

 LI..D. (trinn & Co.) — Prof. Young has already issued two 

 text-books in astronomy, " The Elements of Astronomy," and 

 " (ieucral Astronomy,'' both of which arc models of their kind. 

 The present book is for the u.se of those who find the first not 

 sufficiently extended for their purpose, but for whom the 

 second is too largo for convenience. A most excellent 

 text book it is, clear, full and yet not redundant, from the 

 " Preliminary Considerations and Definitions,'' which con- 

 stitute Chapter 1., to the Appendix, giving instructions for 



