Geological Society. 413 



will feel grateful to M. Maurain for the exceedingly useful account 

 of what has already been done in this branch of experimental 

 science. Beginning with a general account of the phenomena of 

 magnetic induction, the author briefly describes the various methods 

 of measuring magnetic quantities, and the instruments used for 

 this purpose. Next follows a detailed study of the magnetic 

 qualities of iron and steel. This is succeeded by a chapter dealing 

 with the vexed question of viscous hysteresis ; and the next two 

 chapters are devoted to a discussion of the dissipation of energy 

 by hysteresis, and the effects of temperature changes. A short 

 sketch of the theories of magnetic induction concludes this little 

 book, which we can unhesitatingly recommend to all interested 

 in magnetic research. 



Le Phenomene de Zeeman. Par A. Cotton. Paris : Georges Carre 

 & C. Naud, 1899. Pp. 1 -100. 



Another excellent little book belonging to the same series as 

 that referred to in the last notice. 



The steady improvement which has, since the commencement 

 of the 19th century, been taking place in the construction of 

 physical measuring instruments, has produced important results 

 in enabling the physicist to study many phenomena whose very 

 existence could not be detected by the crude apparatus at the dis- 

 posal of some of the early workers in physical science. What 

 Paraday looked for, but looked for in vain, it has been reserved 

 for Zeeman, equipped with the wonderfully perfect instruments 

 now available, to discover and interpret. In the little book before 

 us, the author gives a connected account of the various phenomena 

 directly or indirectly related to the Zeeman effect. After a brief 

 discussion of the various forms of diffraction-gratings, the author 

 considers how a change in the wave-length of a given radiation 

 may be produced. Next comes a short historical accouut of the 

 researches which preceded Zeeman's great discovery, and this is 

 followed by a detailed account of the discovery itself. The re- 

 mainder of the book deals with the most recent experiments 

 bearing on this subject. Numerous references to original sources 

 of information are given. The book will prove extremely useful 

 to all interested in the subject with which it deals. 



XXXVIII. Proceedings of Learned Societies, 



GEOLOGICAL SOCIETY. 

 [Continued from p. 328.] 



January 10th, 1900.— W. Whitaker, B.A., F.R.S., President, 

 in the Chair. 

 npHE following communications were read : — 

 ■*- 1. 'On a Particular Form of Surface, the Result of Glacial 

 and Subaerial Erosion, seen on Loch Lochy and Elsewhere.' By 

 Dr. W. T. Blanford, F.B.S., Treas.G.S. 



This form of surface, first noticed by the author on Lake Como, 

 was afterwards observed in the Great Glen of Scotland and in 



