March .lo, . 1910] 



NATURE 



of detail. No .book of a similar scope is published 

 ill English, and it may be recommended without hesi- 

 tntion to students desiring^ a succinct statement of 

 facts and their bearing on modern theories of matter. 

 Having said so much, we may perhaps be permitted 

 to point out various small blemishes. 



Chapter i. gives an account^ in forty pages, of the 

 chief results obtained by the study of gaseous con- 

 duction. The usual revolving paddle-wheel is given 

 as an instance of the mechanical effects produced by 

 kathode ra\s, but it has been shown by Stark that 

 this is due to the heating and not to the momentum 

 of the rays. The properties of positive rays are given 

 in one short paragraph; as they are of outstanding 

 interest at the present time, it might have been 

 expected that something more recent than W. Wien's 

 original experiments would be mentioned. 



On p. 61 the extinguishing action of radium on a 

 long spark is ascribed to the conductivity produced, 

 but, as P«ck and the present writer have shown, a 

 far greater conductivity may be produced by Rontgen 

 rays without producing extinction- 

 Chapter iii. should be especially useful to chemists, 

 dealing as it does with the instruments used and the 

 methods of standardising them; Wilson's tilted 

 electroscope might have been included. 



On p. 127 a method is given of demonstrating the 

 positive -charge carried by o rays ; actually the indica- 

 tions of the electroscope would be the same, if the 

 rays were uncharged; all the experiment shows is 

 that the 3 rays, are charged negatively. The proper 

 demonstration is given later. 



The deduction of the transformation constants from 

 the decay curves is exceptionally well done, as is also 

 the question of electromagnetic mass. In connection 

 with the latter. Sir J. J. Thomson has given reasons 

 for thinking that the number of electrons in an atom 

 is small; these reasons should have been mentioned 

 in the discussion of atomic architecture. 



Chapter xi, gives an accoynt of conduction in metals 

 according .to the electronic theory. A difficultv, not 

 mentioned here, is the fact that on this theory, accord- 

 ing to Thomson, the energj- required to raise, say, a 

 gram of silver one degree is about ten times that 

 shown by experiment. 



F"inally, in a book of such a scope we should expect 

 to find some reference to the work of Campbell and 

 ethers on the radio-activity of the cornmoner elements. 



R. S. W. 



POVULATi ASTROXOMY. 



(i) Astronomical Curiosities, Facts and Fallacies. 

 By J. Ellard Gore. Pp. x+370. (London : Chatto 

 and Windus, 1909.) 

 (2) Curiosities of the Sky. A Popular Presentation of 

 the Great Riddles and Mysteries of Astronomy. By 

 . Garrett P. Serviss. Pp. xvi + 268. (New York and 

 London : Harper and Brothers, 1909.) Price 65. net. 

 T T is admittedly unwise to judge a book by its 

 ■»- cover. It would seem to be quite unsafe to 

 judge it by its title. Two books, by a quaint coinci- 

 dence very alike in their titles, demand notice 

 NO. 2ic/i, VOL. 83] 



together. Notwithstanding their initial similarity, 

 they each appeal to a -distinctly -different class, of 

 readers. 



(i) To anyone with an already developed interest in 

 general astronomy the collection of "curious facts, 

 ■fallacies and paradoxes" contained in Mr. -Gore's 

 book will doubtless prove interesting and suggestive. 

 It does not pretend to tell a connected story. It cer- 

 tainly does not. Neither -does it present a fairly com- 

 plete picture of the astronomy of to-daj-. Elements 

 of the subject are not dealt with, and facts loom 

 larger than theories. It is essentially a book of 

 "extras." 



The information given, which the author believes 

 will not be found in popular works on astronomy, has 

 apparently been gleaned mostly, though of course not 

 exclusively, from English and American publications 

 of recent years. Each fact is presented in all its . 

 individuality with a local habitation and a name. 

 It is in effect an excellent astronomical scrap-book, 

 with the scraps arranged into chapters and with refer- 

 ences scrupulously and copiously given. 



The sun and the planets are each dealt with in 

 sequence. The first nine pages contain statements 

 about the sun's "stellar magnitude," temperature, 

 possible length of life and source of heat. Remarks 

 as to the discovery of argon and neon in the sun's 

 chromosphere (which is probably an erroneous identi- 

 fication), about various observations of D3 and con- 

 cerning the discovery of sun-spots, all find a place in 

 this first chapter. From this some rough idea of 

 the character of the work may be gathered. Con- 

 sidering the great and growing importance of solar 

 physics,' this chapter might have been enlarged with 

 profit. To allot no more space to the sun than to 

 each of the planets in turn is surely an unbalanced 

 treatment. The succeeding chapters devoted to 

 comets, to double, binar}- and variable stars, and to 

 nebulae, will be found closely packed with information. 

 Following these comes a rather large section of 73 

 pages concerned with mythological and modern de- 

 tails about the constellations and their included stars. 

 The temperament that found a dictionan,- the -most 

 readable of books would have gloried in these 

 chapters. That the general reader will struggle 

 through them it is difficult to believe. 



It is not to be supposed because the work suffers 

 from its limitations that it is not valuable. .\s a well- 

 written compendium of facts it satisfies a distinct 

 v.-ant. Where such want exists it can be recom- 

 mended. The book is well printed and bound. It is 

 fully indexed, and is light and pleasant to handle. 



(2) "Curiosities of the Sky" is a book of quite 

 another type. Here the selecting hand of the artist 

 has been at work. " Facts " are included only when 

 they help the presentation of the subject. The series 

 of chapter-essays into which the publication is divided 

 are excellently written and generally well informed. 

 Astronomical "coal sacks," under the title of "The 

 Windows of Absolute Night," star clusters, star 

 streams and stellar migrations form the subject-matter 

 of the first fifty pages. An interesting chapter en 

 the passing of the constellations follows. Here the 



