lOO 



NATURE 



[July 28, 1910 



variability of magnitude exhibited by minor planets is 

 accepted as evidence of dissymmetry, and this, in 

 turn, is taken as evidence for the initial cataclysm as 

 described. Torn by tidal stress, the dark sun was 

 disrupted while still solid, the dissymmetry showing 

 that the asteroids have never been in a fluid state. 



Jupiter as a semi-sun is discussed at some length, 

 its albedo of 0*75, as compared with Muller's o'72 for 

 clouds, being ascribed as possiblv due to intrinsic 

 light; the same explanation is offered for Saturn's 

 albedo of o'78. Jupiter's independence of the sun — its 

 belts of cloud are apparently not affected by the rota- 

 tion or revolution of the planet — serves as an illustra- 

 tion of the earlier condition of the earth, and other 

 planets, before the advent of the sun-sustained period. 



Of Saturn and Uranus but little is related, but the 

 story of Neptune's discovery is told at some length. 

 Rather more stress than usual is laid on Prof. 

 Pierce's demonstration that Galle's discovery was a 

 lucky accident. The problem solved by Leverrier and 

 Adams was capable of three solutions, and it was but 

 by chance that they attacked the right one. 



"Congruities " is the keynote for the chapter on 

 the formation of planets, and Prof. Lowell urges that 

 incongruities, discovered since Laplace's time, have 

 killed the nebular hypothesis. He then marshals the 

 mutually-sustaining facts in support of the planetes- 

 imal hypothesis. By curves showing the masses of the 

 planets relative to their solar distance, and others 

 demonstrating the analogies of satellites and primaries 

 in their departures from the common plane, he shows 

 that the congruities, on this hypothesis, are perfect — 

 to-day ; future discoveries may necessitate further 

 steps. 



Having thus brought us to the formation of planets 

 as discrete bodies, the author proceeds to outline the 

 probable history of the finished sphere. On the one 

 hand, we have the physical development, the cracks 

 and cataclysms which formed our geographical 

 features along lines necessarily different from those 

 obtaining on Mars, or any other world; on the other 

 is the chemical development, " as universal as the 

 universe itself." Evidence that darkness was spread 

 oyer the face of the earth is gleaned from many 

 quarters, all showing that our planet was a sunless 

 forcing-house; this was the self-sustained age. Then 

 the earth cooled, the dense cloud covering condensed, 

 admitting sunlight, and we arrived at the sun-sus- 

 tained epoch which we still enjoy. Here the story of 

 evolution is exceedingly interesting, especially that 

 dealing with the Ice age. Probably the statements 

 will be criticised by some geologists, but the author's 

 substitute for what he terms their " astrocomico " 

 suggestions is none the less attractively stated. The 

 extraordinary ellipticity of the orbit, to account for 

 the Glacial epoch, is rejected, and is replaced by one 

 in which excessive evaporation and precipitation, pro- 

 ducing polar ice-sheets of great thickness, play a 

 .i;reat part. It is also shown that the glaciation was 

 restricted to well-marked raised areas, such as Nor- 

 way, Scotland, Labrador, Keewatin, &c., and was 

 nothing more than a natural terrestrial phenomenon ; 

 observations of Mars show that, at the present time, 

 NO. 2126, VOL. 84] 



the polar highlands retain their covering of snow for 

 some time after the general melting of the cap has 

 separated them from the main body of it. 



In the last chapter the "Death of a World" is 

 discussed, and the possible modes of extinction 

 examined. It may be by collision with a dark sun, 

 but, failing that, it is inevitable by the action of tidal 

 friction and the diffusion of water and atmosphere. 

 Collating the facts gleaned from the previous study 

 of the several planets, it is shown that there is a more 

 or less orderly sequence culminating in the present 

 condition of our own satellite. Sans season, sans 

 day and night, sans water and sans atmosphere, the 

 worlds will await the quickening which can only 

 come by the advent of a cataclysm such as is described 

 in the earliest chapters. 



The printing and illustration of the volume are 

 beyond criticism, although the paper is rather heavy, 

 and with its graphic language, its sustained interest, 

 and clear story, the book is sure to appeal to the 

 general reader who would learn more of the past, and 

 of the probable future, of our earth and its fraternity. 

 William E. Rolston. 



NATURE-STUDY. 

 (i) The Nature-Study Idea. An Interpretation of the 

 New School-movement to put the Young into Rela- 

 tion and Sympathy with Nature. By L. H. Bailey. 

 Third edition, revised. Pp. ix + 246. (New York: 

 The Macmillan Company ; London : Macmillan and 

 Co., Ltd., 1909.) Price 4s. 6d. net. 



(2) Man and Nature on Tidal Waters. By Arthur H. 

 Patterson. Pp. xvi + 315. (London : Methuen and 

 Co., 1909.) Price 6s. 



(3) Tommy's Adventures in Natureland. A Nature 

 Story for Boys and Girls. By Sir Digby Pigott, 

 C.B. Pp. xvi + 180. (London: Witherby and Co., 

 1909.) Price 2s. 6d. net. 



(4) Animal Romances. By Graham Renshaw. Pp. 

 vi + 2o6. (London: Sherratt and Hughes, 1908.) 

 Price ys. 6d. 



(OTDROF. L. H. BAILEY is well known as a 

 -T botanist who believes in the practical and 

 educational value of his science, and he has shown 

 himself on many occasions able to give good reasons 

 for the faith that is in him. In the present volume 

 he discusses, in a lively and unconventional fashion, 

 the true inwardness of "nature-study," which is not 

 science, nor knowledge nor facts. " It is spirit. It is 

 an attitude of mind. It concerns itself with the 

 child's outlook on the world." "It would be better if 

 it were called nature-sympathy." We do not think 

 that professional educationists will quite agree with 

 Prof. Bailey in associating all the predagogical virtues 

 with nature-study (for many of them may be ex- 

 pressed in the study of history, for instance), but most 

 who have any sympathy at all with studying the 

 world around us will agree with the sound educational 

 sense which the book expresses. In a breezy and 

 interesting fashion he discusses how nature-study may 

 be taught, the school-garden, the rural-school problem, 

 the teacher's outlook on nature, and about half a 



