CONTENTS OF VOL. XXXIX. SIXTH SERIES. Vll 



Page 

 Mr. G. H. Livens on the Mathematical Relations of the 



Magnetic Field '. . . . 673 



Dr. E.J. S. Sand on the Cadmium- Vapour Arc Lamp 678 



Sir J. J. Thomson on Mass, Energy, and Radiation 679 



Miss Aniela Muszkat on the /3-Recoil 690 



Prof. R. Whiddington on the X-ray Spectra of the Elements. 694 

 Notices respecting New Books : — 



Dr. E. K. Rideal and Dr. H. S. Taylor's Catalysis in 



Theory and Practice 697 



Dr. A. Macfarlane's Ten British Physicists 697 



Proceedings of the Geological Society : — 



Prof. J. E. Marr on the Pleistocene 'Deposits around 

 Cambridge 698 



Index 700 



