[ 526 ] 



LYII. Notices respecting New Boohs. 



A Theory of Time and Space. By Alfred A. Eobb. 

 1914. Cambridge University Press. 

 "TV/TINKOWSKI'S mathematical treatment of the theory of Eela- 

 -*-'•*■ tivity reduces time to imaginary space, and presents the 

 inter-relations of space and time in terms of the properties of a 

 four- dimensional space. Mr. Eobb in this truly remarkable book 

 approaches a similar outlook by an altogether different route. The 

 presentation is geometrical and of the approved modern type. That 

 is to say, there are laid down certain postulates from which, with 

 the aid of a series of closely connected theorems, there is con- 

 structed a geometry in which every element is determined by four 

 coordinates. The argument is difficult to follow ; and the full 

 bearing of the conclusions reached is not easy to appreciate. The 

 author is meanwhile content with having established a consistent 

 geometry, and leaves developments and applications for a further 

 volume. The fundamental notion which is the basis of the whole 

 is the recognition of what Mr. Eobb calls conical order. According 

 to this conception, an event which is neither before nor after 

 another is not necessarily simultaneous with it. The only events 

 which are really simultaneous are those which occur also at the 

 same place. When events occur at different places we may be 

 able to say that one is neither before nor after the other, but we 

 cannot say that they are simultaneous. In the four-dimensional 

 space which is thus imagined a point represents a state of a 

 particle at a given time, and " the theory of space becomes 

 absorbed in the theory of time." 



LVIII. Proceedings of Learned Societies, 



GEOLOGICAL SOCIETY. 



[Continued from p. 176.] 



June 28th, 1916.— Dr. Alfred Harker, F.E.S., President, 

 in the Chair. 



npHE following communications were read : — 



1. ' On a New Species of Edestus from the Upper Carboni- 

 ferous of Yorkshire.' By A. Smith Woodward, LL.D. F.E.S., 

 V.P.G.S. With a Geological Appendix by John Pringle, P.G-.S. 



2. ' The Tertiary Volcanic Eocks of Mozambique.' By Arthur 

 Holmes, B.Sc, A.E.C.Sc, D.I.C., F.G.S. 



Until recently, the district of Mozambique — geographically as 

 well as geologically — was one of the least known of the East 

 African coast-lands. During the seasons 1910-11, a prospecting 



