CONTENTS OF VOL. XXI. 



(SIXTH SEEIES). 



NUMBER CXXL— JANUARY 1911. 



Page 

 Dr. James G. Gray and Mr. Alexander D. Eoss on Magnetic 



Testing 1 



Prof. M. S. Smoluchowski : Some Kemarks on Conduction of 



Heat through Rarefied Gases 11 



Mr. S. B. McLaren on Hamilton's Equations and the Parti- 

 tion of Energy between Matter and Radiation 15 



Dr. A. S. Eve on the Ionization of the Atmosphere due to 



Radioactive Matter 26 



Mr. Hugh Mitchell on the Ratios which the Amounts of 



Substances in Radioactive Equilibrium bear to one another. 40 

 Mr. Norman Campbell on a Method of Determining Capacities 



in Measurements of Ionization = . . 42 



Dr. A. 0. Rankine on the Relation between Viscosity and 



Atomic Weight for the Inert Gases ; with its Application 



to the case of Radium Emanation . 45 



Lord Rayleigh on Bessel's Functions as applied to the 



Vibrations of a Circular Membrane 53 



Mr. Horace H. Poole on the Rate of Evolution of Heat by 



Pitchblende 58 



Dr. J. W. Nicholson on the Bending of Electric Waves round 



a Large Sphere. — III Cr2 



Mr. Clive Cuthbertson : New Determinations of some 



Constants of the Inert Gases 69 



Dr. R. A. Houstoun on Magnetostriction 78 



Dr. R. D. Kleeman: An Investigation of the Determinations 



of the Law of Chemical Attraction between Atoms from 



Physical Data 83 



Mr. Arnold L. Eletcher on the Radioactivity of the Leinster 



Granite 102 



Prof. Horace Lamb on the Uniform Motion of a Sphere 



through a Viscous Eluid 112 



Mr. E. A. Owen on the Change of Resistance of Nickel 



and Iron Wires placed longitudinally in Strong Magnetic 



Eields *" 122 



Messrs. Alexander S. Russell and Frederick Soddy on the 



y-Rays of Thorium and Actinium L30 



Dr. R. Pohl and Dr. P. Pringsheim on the Normal and the 



Selective Photoelectric Effect 1 ;,:i 



