30 



KNOWLEDGE. 



January, 1913. 



out a working hypothesis is like building without a scaffold, 

 yet it is not many years ago since an eminent astronomer 

 said that we do not want theory, we want facts. The promise 

 of the preface is well sustained. In it the author says that 

 the time seems ripe for collecting the splendid array of new 

 solar knowledge which such unprecedented activity has pro- 

 duced, and for discussing the probable nature of the Sun in 

 the light gained. All this he has done most admirably. 



There are other explanations and generalizations that he 

 has evidently not read, hence he has not given us the whole 

 truth. He has, however, examined many obsolete explanations, 

 in the light of modern chemistry and physics and has shown 

 them to be wrong, such as the Laplace ring theory, and the 

 carbon cloud theory of the photosphere. This is especially 

 good work : we do not want false explanations to fossilize into 

 supposed firm fact, no matter how beautiful the errors may be. 

 The author argues conclusively that the photosphere is a 

 gaseous surface, but he does not seem to be aware that it is 

 almost certainly the limit of static equilibrium, all above it 

 being supported by kinetic energy ; the supporting power of 

 the reversing layer being the energy of volcanic projection, 

 and that of the chromosphere being molecular kinetic energy. 

 Nor does he seem to realize that if meteors have anything 

 to do with sunspots their function is probably similar to 

 the detonator of a dynamitic explosion. Meteors are, as 

 it were, the triggers, the dynamical rigidity of the Sun 

 supplying the effective energy. Altogether this is a 

 great book, fearless in the expression of new ideas, and 

 intensely sane in their advocacy. It will do much to render 

 solar information available, instead of remaining a lumber of 

 uncorrelated facts. A W R 



The Star Calendar for 1913. With Revolving Chart. —By 

 Mrs. H. Periam Hawkins. 10-in. XlO-in. 



(Simpkin, Marshall & Co. Price 1/- net.) 



Users of this chart will find it one of the very best forms of 

 planisphere yet designed. The area of the heavens visible at 

 any time is shown by an oval cut in a covering card. Hence 

 the zenith can be recognised at once. This card is hinged at 

 the top, so that it can be lifted to see the whole of the stars 

 ever visible in England. 



The chart has proved itself of great value to troops who 

 are studying marching by the stars. The explanations of how 

 to use it are very clearly described. 



It would be an improvement were the North Polar Circle 

 drawn to show precession, and also were the Milky Way 

 indicated by a faint whiteness. 



This is a most useful chart, and can be highly recommended. 



A. W. B. 



The Star Almanac, for 1913. — By Mrs. Periam Hawkins. 

 6 illustrations. 30-in.X24-in. 



(Simpkin, Marshall & Co. Price 6d. net.) 



Again Mrs. Periam Hawkins has introduced improvements 

 into this excellent Almanac. In addition to the star charts for 

 the four seasons, there is a diagram showing the North Polar 

 clock. She has also brought in a table of hints in connection 

 with marching and telling the time by the stars, the sun, and 

 the moon. There is all the usual information contained in a 

 star almanac. 



The Almanac would be most valuable on the walls of any 



astronomer's study or observatory. 



A. W. B. 



The A.B.C. Guide to Astronomy. Second Edition. By 

 Mrs. H. Periam Hawkins. 120 pages. 71-in. X5-in. 



(Simpkin, Marshall & Co. Price 1/6 net.) 



This little book is of the kind one is glad to see in its second 

 edition, for it is a very valuable contribution to Astronomy. 

 The first edition had a few misprints and slight errors from 

 which this edition seems quite free, as one would expect after 

 it had passed the keen eye of so able and accurate an 

 astronomer as Dr. A. C. D. Crommelin. Mrs. H. Periam 



Hawkins must have read very widely in preparing this book, 

 for there is scarcely an astronomical idea of importance the 

 meaning of which is not described with the utmost clearness. 

 The information is brought quite up to date. Good 

 abstracts of the latest correlations are given, some of which 

 are seldom seen in any astronomical work. This attention to 

 broad generalizations is of the utmost importance in these 

 days, when the mass of detail accumulated by astronomers 

 threatens to bury the essential facts out of sight. The A.B.C. 

 arrangement is also very useful in the case of points needing 

 reference. The book is strongly to be recommended to the 

 amateur astronomer. a w R 



A Primer of Astronomy. — By Sir Robert Ball. 222 

 pages. Numerous maps and illustrations. 7-in.X4i-in. 



(The Cambridge University Press. Price 1/- net.) 



This excellent little book has its value much increased in its 

 re-issue, by the addition of maps of the northern and southern 

 hemispheres, and by a new chapter of forty-two pages on 

 celestial objects. This chapter is written in Sir Robert Ball's 

 usual perspicuous style. It is exactly suited to the amateur 

 observer, every interesting object in both northern and 

 southern hemispheres being very fully described. The book 

 is thus rendered suitable to Africa and Australia. The 

 descriptions are brightened by interesting folklore. In the 

 older parts of the book one could have desired a few altera- 

 tions to bring it up to date. For instance, in the nebula of 

 Andromeda, which is described as showing rings elongated by 

 projection into ellipses, while the latest photographs leave no 

 room to doubt its spiral character. Some of the explanations 

 are also a little antiquated, and not quite in accord with 



modern chemical physics. 



A. W. B. 



A Beginner's Star-Book. — By K. McKready. 148 pages. 

 70 maps and illustrations. lOi-in. X 8-in. 



(G. P. Putnam's Sons. Price 9/- net.). 



The author says in his Preface that this book is "in a sense 

 but one effort more to help those who are without technical 

 equipment, to claim through the unaided eyes or through simple 

 optical instruments their heritage in things of the sky " ; " It is 

 intended for the general reader," and not as a text book, but 

 ' as a simple observational manual," and, further, " The 

 volume is also intended for those who wish to add to their 

 knowledge of the skies without aid of any kind " . . . . 

 " much of it is, necessarily, a recapitulation of elementary 

 facts; it is frankly a book for the beginner." These extracts 

 adequately explain the nature of this work and we heartily 

 congratulate the author in having so successfully accomplished 

 what he set himself to do. We are acquainted with most 

 books of this nature or aim published during the last forty 

 years, but we cannot recall the title of one that so well fills the 

 need of an elementary and progressive book on observational 

 astronomy for the beginner, young or old. Most err in being 

 either too easy or simple without the redeeming feature — given 

 in this book — of opportunities for promoting or satisfying 

 advancing knowledge ; too technical, too profuse or laborious 

 for the convenient and daily use of a beginner in out-door 

 astronomy ; or too much out of date to meet the recent 

 advances even in observational astronomy. To us this book 

 appears to be the bridge. 



Beyond the data or details in the book being brought 

 up-to-date there can be little that is new, nor does the author 

 claim that it is so. The principles of the book are to encourage 

 the beginner to learn from the objects, not from mere book 

 reading ; to proceed slowly, get a good grasp of one thing at a 

 time, and not to attempt too much at once. 



The book of one hundred and forty-eight pages is divided 

 into ten chapters or divisions: I, Introduction, brief but very 

 useful; 1 1, Objects to be seen. The Stellar World; III, Learning 

 to observe ; IV, Star maps ; V, Objects to be seen. The Solar 

 System; VI, Some Instruments of Observation; VII, An 

 Observer's Catalogue of Telescopic Objects; VIII, Statistical 





