CONTENTS OF VOL. XXX. SIXTH SERIES. Vll 



Prof. W. D. Harkins and Mr. E. D. Wilson on Energy 

 Relations involved in the Formation of Complex Atoms . . 723 



Prof. W. M. Hicks on the Calculation of Series in Spectra. . 734 



Dr. C. Statescu on the Dispersion of Carbon Dioxide in the 

 Infra-red Region of the Spectrum 737 



Dr. A. M. Tyndall on Ionic Mobilities in Hydrogen 743 



NUMBER CLXXX.— DECEMBER. 



Prof. C. Gr. Barkla and Mr. G-. Shearer on the Velocity of 

 Electrons expelled by X-rays 745 



Prof. P. J. DanieJl on Rotation of Elastic Bodies and the 

 Principle of Relativity 754 



Dr. J. R. Wilton on the Solution of Certain Problems of 

 Two-Dimension nl Physics 7G1 



Sir J. J. Thomson on a Method of Rinding the Coefficients 

 of Absorption of the Different Constituents of a Beam of 

 Heterogeneous Rontgen Rays, or the Periods and Co- 

 efficients of Damping of a Vibrating Dynamical System . . 780 



Dr. L. Silberstein on Radiation from an Electric Source, and 

 Line Spectra. (Third Paper.) (Plate XVIII.) 784 



Mr. H. Smith : A Comparison of the Positive Rays with the 

 Spectrum of the Positive Column in a Mixture of Helium 

 and Hydrogen .... 805 



Mr. A. B. Wood and Dr. W. Makower on the Recoil of 

 Radium D from Radium C 811 



Prof. R. R. Ramsey on the Variation of the Emanation 

 Content of Certain Springs 815 



Notices respecting New Books : — 



Dr. T. P. Nunn's The Teaching of Algebra ; and Exer- 

 cises in Algebra, including Trigonometry, Parts I., II. 818 



Index 819 



