CONTENTS OF VOL. XX. SIXTH SERIES. Vll 



Page 

 Mr. John Satterly : Some experiments on the Absorption of: 



Radium Emanation by Coconut Charcoal 778 



Mr. Andrew Stephenson on Displacements in the Spectrum 



due* to Pressure 788 



Proceedings of the Geological Society 790 



NUMBER CXIX.— NOVEMBER. 



Mr. E. B. Young on the Critical Phenomena of Ether .... 793 

 Dr. J. W. Nicholson on the Accelerated Motion of a Dielectric 



Sphere . . 828 



Prof. Harold A. "Wilson on the Electron Theory of the Optical 



Properties of Metals 835 



Mr. A. Stephenson on the Intensity of Periodic Fields of Force 844 

 Dr. Alois F. Kovarik on Absorption and Reflexion of the 



/3-Particles by Matter , 849 



Dr. Alois F. Kovarik and Mr. W. Wilson on the Reflexion 



of Homogeneous /3-Particles of Different Velocities 866 



Messrs. J. A. Gray and W. Wilson on the Heterogeneity of 



the /3 Rays from a Thick Layer of Radium E 870 



Drs. Sidney Russ and Walter Makower on the Deflexion 



by an Electrostatic Field of Radium B on Recoil from 



Radium A 875 



Dr. W. Makower and Mr. E. J. Evans on the Deflexion by 



a Magnetic Field of Radium B on recoil from Radium A. 



(Plate XVITI.) 882 



Profs. A. Trowbridge and R. W. Wood on Groove-Form and 



Energy Distribution of Diffraction Gratings 886 



Profs. A. Trowbridge and R. W. Wood on Jnfra-Red In- 

 vestigations with the Echelette Grating 898 



Dr. R. D. Kleeman on Molecular Attraction 901 



Prof. P. Lenard on the Electricity of Mercury -falls and on 



very large Ions 903 



Prof. H. A. Wilson on the Statistical Theory of Radiation . . 904 



NUMBER CXX.— DECEMBER. 



Dr. R. D. Kleeman on the Attraction Constant of a Molecule 

 of a Substance and its Chemical Properties - . 905 



Mr. D. C. H. Florance on Primary and Secondary y-Rays . . 921 



Dr. J. W. Nicholson on the Approximate Calculation of 

 Bessel Functions of Imaginary Argument 938 



Prof. J. H. Jeans on Non-Newtonian Mechanical Systems, 



and Planck's Theory of Radiation 943 



Dr. R. W. Boyle on the Volatilization of Radium Emana- 

 tion at Low Temperatures 955 



Mr. T. H. Blakesley on a Means of Measuring the Apparent 



Diameter of the Pupil of the Eye, in very feeble Light . . 966 



Mr. Manne Siegbahn on the Study of Variable Currents by 

 means of the " Phaseograph." (Plate XIX.) 969 



