August 31, igi 1] 



NATURE 



2/5 



lines, touches on chronographs and synchronisation 

 of clocks, and gives extracts from the annual trial- 

 numbers from the Greenwich volumes, showing the 

 improvements makers have been able to secure in the 

 last sixty odd years. W. W. B. 



COSMIC AL PHYSIC>. 



Researches on the Evolution of the Stellar Systems. 

 By Prof. T. J. J. See. Vol. ii., "The Capture 

 Theory of Cosmical Evolution, founded on Dyna- 

 mical Principles and Illustrated by Phenomena 

 Observed in the Spiral Nebulas, the Planetary 

 System, the Double and Multiple Stars and 

 Clusters, and the Star-clouds of the Milky Way." 

 Pp. viii + 734. (Lynn, Mass.: T. P. Nichols and 

 Sons; London: W. Wesley and Son, 1910.) 



IT is with mingled feelings that, after reading 

 through this immense volume of Dr. See's, the 

 reviewer attempts to present it fairly to the readers 

 of this journal. This book and the theory presented 

 therein is " the culmination of continued labor ex- 

 tending over more than a quarter of a century." It 

 calls therefore for a full and careful discussion. It is 

 a great pity that the writer over and over again 

 by loose dogmatic statements repels the critic, and 

 that lie so frequently makes claims as to the rigorous- 

 ness of the methods he employs, claims which a care- 

 ful examination quite fails to endorse. As an ex- 

 ample of the former fault we choose the extraordinary 

 statement on p. 152, which comes at the end of an 

 account of some quite inconclusive mathematical 

 work on the effect of a resisting medium. The 

 italic-, are the author's. 



" Whatever doubt may arise as to the effect of the 

 resisting medium in the present state of the solar 

 sysli'iu, there can be no possible doubt as to its power 

 in our system at the epoch when the planets were 

 formed. The observed roundness of the orbits of the 

 planets is an everlasting witness to the presence of 

 a resisting medium against which these bodies re- 

 volved for immeasurable ages. There is no other 

 admissible explanation of tliis phenomenon, and as 

 the resisting medium is a vera causa, on the secular 

 effects of which all mathematicians are agreed, we 

 may hold that it has as surely rounded up these orbits 

 as if we had witnessed the transformation within the 

 short period of human history covered by exact 

 observations." 



For the author's claims to mathematical rigorous- 

 ness of treatment reference may be made to pp. 237, 

 259. The answer to these claims is twofold. On the 

 one hand rigorous proof is from the nature of the 

 case impossible in cosmogony. Too many uncer- 

 tainties are necessarily involved in the premises for 

 any amount of exact mathematical reasoning to lead 

 to a rigorous proof, and even in this mathematical 

 reasoning Dr. See is by no means perfect. It is a 

 pity that his reply to the mathematical point raised 

 by Mr. Brodetskv in the Astronomische Nachrichten 

 (No. 440S) should be limited to the suggestion that 

 " Mr. Brodetskv is unfortunate in writing from Cam- 

 bridge." If Dr. See's views do not meet with the 

 NO. 2183, VOL. 87] 



full attention that he desires for them (or to do them 

 justice, that they deserve), the fault lies partly with 

 his method of presenting them. 



After these strictures we may turn to the more 

 pleasant task of dwelling on the theory that Dr. See 

 has built up. In his view the solar system has de- 

 veloped from a spiral nebula. Condensations round 

 various nuclei have gradually developed into planets. 

 The resistance of the medium through which these 

 bodies have revolved about the central condensation 

 or sun, has led to the gradual falling in and round- 

 ing of their orbits, and also to the capture by the 

 planets of all their satellites. Thus the moon, which 

 originally revolved outside the present orbit of Nep- 

 tune, was captured by the earth while in the process 

 of falling into the sun through the slow decrease of 

 its orbit. The theory is supported by arguments 

 adduced from many branches of astronomical re- 

 search. Some of the material which Dr. See has 

 brought together to support his views is of very 

 decided interest, notably chapter ix. on the capture 

 of comets, and chapter xxi. with its welcome ex- 

 tracts from the papers of Herschel. Dr. See has been 

 very generous in the extracts he quotes from the 

 work of other people. It is not obvious, however, 

 why chapter xii., with its long extracts on lunar 

 motion, should figure in this work. There is no 

 independent criticism made of the controversies re- 

 ferred to, and a bare statement of the results arrived 

 at, with references, should have amply sufficed. In 

 some of his criticisms of other contributions to 

 cosmogony, Dr. See is much happier than in his own 

 constructive work. Thus some of his criticisms of 

 Messrs. Chamberlain and Moulton on p. 106 are 

 distinctly to the point; while independently of other 

 workers in the same field, he has brought forward 

 some cogent reasons against the nebular hypothesis 

 of Laplace in its ordinary form; he also criticises 

 some conclusions frequently drawn (though not 

 always correctly) from the papers of Sir George 

 Darwin. 



Many points of detail offer themselves for criticism 

 in the treatment accorded by Dr. See to all the 

 problems discussed in his book. But we have said 

 enough to give the general scope of the work. While 

 not able to accept Dr. See's views as to the important 

 part played by the resisting medium in the evolution 

 of our system, we are prepared to find in this re- 

 sisting medium a vera causa the effect of which has 

 been frequently overlooked by other workers. This 

 book is an exaggeration. It may serve to restore 

 the true balance of forces. 



It remains to be added that the book has been very 

 well prepared for publication. It is produced _ in a 

 manner that does credit to its author and publishers 

 alike. The photographic reproductions are very 

 good. The moon, nebulse, and star-clouds are well 

 represented in a series of very fine plates. It is a 

 pity that the headings used were added to the fine 

 photographs by Barnard. A useful summary of the 

 whole book is added in chapter xxiv., which gives a 

 formidable list of problems explained by the theory. 



