Vlll CONTENTS OF VOL. XX. SIXTH SERIES. 



Page 

 Prof. (). W. Richardson on the Positive Thermions emitted 



by the Alkali Sulphates. (Plate XX.) 981 



Prof. O. W. Richardson on the Positive Thermions emitted 



by the Salts of the Alkali Metals 999 



Lord Rayleigh on the Problem of the Whispering Gallery . 1001 



Prof. J. A. Ewing on Magnetic Hysteresis 1005 



Notices respecting New Books : — 



Prof. H. C.Jones's Introduction to Physical Chemistry. 1006 



Annuaire pour Tan 1911 1007 



Mr. G. W. de Tunzelmann's Treatise on Electrical 



Theory and the Problem of the Universe 1007 



U.S. Coast and Geodetic Survey 1008 



Proceedings of the Geological Society 1008-1009 



Index 1010 



P L A T E S. 



I. & II. Illustrative of Mr. J. Satterly's Paper on the Amount of 

 Radium Emanation in the Lower Regions of the Atmosphere 

 and its Variation with the Weather. 



III. Illustrative of Profs. O. W. Richardson and II. L. Cooke's 



Paper on the Heal developed during the Absorption of 

 Electrons by Platinum. 



IV. Illustrative of Prof. A. P. Chattock and Mr. A. M. Tvndall's 



Paper on the Ionizing Processes al a Point discharging in Air. 

 V. Illustrative of Mr. R. T. Beatty's Paper on the Production 

 of Cathode Particles by Homogeneous Rontgen Radiations, 

 and their Absorption by Hydrogen and Air. 

 VI. Illustrative of Prof. Silvanus P. Thompson's Paper on Hys- 

 teresis Loops and Lissajous' Figures. 

 VII.-IX. Illustrative of Prof. E. II.' Barton and Mr. T. F. Ebblewhite's 

 Paper on Vibration ( Inrves of Violin Bridge and Strings. 

 X. Illustrative of Dr. W. II. Eccles's Paper on the Energy Rela- 

 tions of Certain Detectors used in Wireless Telegraphy. 

 XL Illustrative of Mr. A. E. Garrett's Paper on Positive Electri- 

 fication due to Heating Aluminium Phosphate. 

 XII. Illustrative of Mr. G. II. Berry's Paper on the Pianoforte 

 Sounding-Board. 



XIII. Illustrative of Prof. Taylor Jones and Mr. Roberts's Paper 



on Musical Arc Oscillations in Coupled Circuits. 



XIV. Illustrative of Prof. R. W. Wood's Paper on a New Radiant 



Emission from the Spark. 

 XV. Illustrative of Dr. G. W. C. Kaye's Paper on a Method of 



Counting the Rulings of a Diffraction Grating. 

 XVI. Illustrative of Prof. A. Trowbridge's Paper on a Vacuum 

 Spectrometer. 

 XVII. Illustrative of Prof. R. W. Wood's Paper on the Echelette 

 Grating for the Infra-Red. 

 XVIII. Illustrative of Dr. W. Makower and Mr. E. J. Evans's Paper 

 on the Deflexion by a Magnetic Field of Radium B on recoil 

 from Radium A. 

 XIX. Illustrative of Mr. Manne Siegbahn's Paper on the Study of 

 Variable Currents by means of the " Rhaseograph." 

 XX. Illustrative of Prof. O. W. Richardson's Paper on the Positive 

 Thermions emitted by the Alkali Sulphates. 



