680 SCIENCE PROGRESS 



appearance of various forgotten theories for which the authors claim some 

 kinship with Einstein's fundamental ideas. In general, these are produc- 

 tions of the genus " crank," and are entirely devoid of logical development. 

 The theory under review is not of this nature, in so far as it is an attempt 

 logically to develop the consequences of certain postulates which are clearly 

 stated at the beginning. In one respect the author may be considered to 

 have anticipated Einstein. He assumes that the normal form of space is 

 the Euclidean form ; that the presence of matter causes a slight deviation 

 from the homogeneous Euclidean form, and that this deviation is accom- 

 panied by appropriate forces in the substance of the ether which tend to 

 restore the spatial relations of its parts to the mathematical relations of 

 Euclidean geometry. 



We have to admit, however, that we fail to follow the author's argument. 

 It appears, however, to lead to Newtonian dynamics and gravitation law, 

 though this cannot be interpreted as evidence for the theory, but rather 

 that the argument has been adjusted to the result which it is required to 

 establish. As with other theories claiming to account for gravitation, it is 

 not amenable to testing by observation and is not likely, therefore, to com- 

 mand acceptance. 



H. S. J. 



ASTRONOMY 



Problems of Cosmogony and Stellar Dynamics; Being an Essay to which 

 the Adams Prize of the University of Cambridge for the year 1917 

 was adjudged. By J. H. Jeans, M.A., F.R.S. [Pp. viii + 293, 

 with 5 plates and 45 figures.] (Cambridge University Press, 191 9. 

 Price 21s. net.) 



The Adams Prize of the University of Cambridge, which is awarded 

 biennially for an essay on some subject in mathematical physics, an- 

 nounced beforehand by the adjudicators, provides a valuable incentive to 

 investigators to collect together their own researches on that subject, to 

 extend them, and to weld them on to earlier work in the same direction, so 

 as to make a homogeneous whole. Attached to the award is the valuable 

 stipulation that the essay must be published. In this way, mathematical 

 physics has been enriched with a number of volumes of high intrinsic merit, 

 several of which have become recognised classics : among such, for instance, 

 may be mentioned Sir Joseph Larmor's " ^Ether and Matter." 



The subject announced for the 1917 Essay was " The cause of evolu- 

 tion of the configurations possible for a rotating and gravitating fluid mass, 

 including the discussion of the stabilities of the various forms." This 

 problem had already been attacked in important papers by Darwin, Poincare, 

 Liapounoff and others, but divergent conclusions had been arrived at by 

 Darwin and Liapounoff regarding the stability of the rotating pear-shaped 

 figure ; moreover, their researches had been concerned only with the two 

 extreme cases of an incompressible or an infinitely compressible fluid. There 

 thus remained a wide field for investigation. At that time Mr. Jeans had 

 for some years been engaged in an attack on the problem, and the oppor- 

 tune choice by the adjudicators of the problem as the subject for the 191 7 

 essay was probably coupled with the hope that Mr. Jeans would be 

 able to find time to pursue further his investigations. If so, they have 

 been well rewarded. The volume under review contains the prize 

 essay enlarged by the addition of some further results which had been 

 obtained in the interval before publication ; it will demand the serious study 

 of all who are investigating the general problem of cosmic evolution. 



