632 Notices respecting New Boohs. 



and often apparently contradictory results of observation, the 

 author assumes that the motion of the air is at right angles to 

 the direction of the pressure gradient and has the velocity de- 

 duced from the gradient equation. The latter equation is derived 

 by assuming that the motion is under balanced forces depending 

 on the spin of the Earth and the spin in a small circle on the Earth. 

 This leads to a study of the relationship between the surface-wind 

 and the geostrophic wind at sea-level and of the variation of wind 

 with height. A summary is given of Taylor's theory of the 

 diffusion of eddy-motion, and comparisons are made between the 

 results calculated from it and those provided from observations 

 of pilot-balloons. The detailed discussion of the geometry and 

 mechanics of a travelling cyclone is very suggestive, and the dis- 

 tinction drawn by the author between the instantaneous kine- 

 matic centre, the tornado centre, and the dynamic curve as 

 shown by the isobars is an important one. A summary is given 

 of Rayleigh's exposition of the properties of a stationary column 

 of revolving fluid, and Aitken's experimental illustrations of the 

 dynamics of cyclones are critically discussed. Lord Bayleigh's 

 discussion neglected the effect of the rotation of the Earth, 

 and it is somewhat surprising that the results agree as well as 

 they do with observation. The reproduction of instrumental 

 records relative to several notable .storms and their discussion 

 help to give a clear idea as to the extent to which theory and 

 observation agree. 



The volume is an important contribution to meteorological 

 literature. We hope that the other Parts will be published at 

 an early date. H. S. J. 



Stereochemistry. By Alered W. Stewaet, D.Sc, Professor of 

 Chemistry in the Queen's University of Belfast. Second Edition. 

 Pp. xvi + 277. [Text Books of Physical Chemistry.] London: 

 Longmans, Green & Co., 1919. 



The chief alterations in this second edition are the following : 

 Recognition is made of the existence of optically active compounds 

 containing no carbon atom, the activity of aniline oxides, and 

 corresponding phosphorus derivatives, and of the preparation of 

 allylene analogues in active forms. 



The Walden inversion phenomena are given the place for 

 which they are worthy. On the other hand, we are glad to see 

 that the space previously devoted to steric hindrance has been cut 

 down. That branch of the subject seemed likely to spread as an 

 obsession over the whole subject — to its detriment. 



A short chapter is devoted to the arrangement of atoms in 

 crystals, in which the work of the Braggs (father and son) is 

 outlined. It would have been well, however, if the author had 

 submitted this • chapter for revision to a friend competent to 

 express an opinion on the subject. 



