VI CONTENTS OK VOL. XLI. SIXTH SERIES. 



Page 

 Notices respecting New Books : — 



Alphonse Berget's Ou en est la Meteorologie ? 632 



Proceedings of the Geological Society : — 



Prof. A. H. Cox and Mr. A. K. Wells on the Lower 

 Paleozoic Rocks of the Arthog-Dolgelley District 



(Merionethshire) , 683 



Mr. J. W. D. Robinson on the Devonian of Ferques 

 (Lower Boulonnais) 684 



NUMBER CCXLV.— MAT. 



The Research Staff of the General Electric Company, London, 

 on the Disappearance of Gas in the Electric Discharge. — II. 685 



Dr. Norman Campbell and Prof. E. C. C. Baly on the Physical 

 Significance of the Least Common Multiple 707 



Dr. J. S. G. Thomas on a Null-Deflexion Constant Current 

 Type of Hot- Wire xlnemometer, for use in the Determi- 

 nation of Slow Rates of Plow of Gases, together with an 

 Investigation of the Effect of the Pree Convection Current 

 upon such Determinations 716 



Dr. Tycho E:son Auren on Scattering and Absorption of 

 Hard X-Rays in the Lightest Elements 733 



Prof. S. P. Timoshenko on the Correction for Shear of the 

 Differential Equation for Transverse Vibrations of Pris- 

 matic Bars 744 



Prof. H. J. Priestley on the Einstein Spectral Line Effect . . 747 



Prof. A. H. Compton on the Degradation of Gamma-Ray 

 Energy 749 



Prof. A. H. Compton on the Wave-Length of Hard Gamma 

 Rays 770 



Prof. A. LI. Hughes on Dissociation of Hydrogen and Nitrogen 

 by Electron Impacts 778 



Messrs. D. L. Chapman and H. J. George on the Abnormality 

 of Strong Electrolytes 799 



Prof. W. B. Morton on the Discontinuous Plow of Liquid 

 past a Wedge 801 



Prof. A. Taber Jones on the Motion of a Simple Pendulum 

 after the String has become Slack 809 



Mr. H. Ericke and Prof. T. Lyman on the Spectrum of Helium 

 in the Extreme Ultra- Violet 814 



Mr. J. H. J. Poole on the possibility of separating Mercury 

 into its Isotopic Forms by Centrifuging 818 



Mr. F. W. Hill and Dr. J. B. Jeffery on the Gravitational 

 Field of a Particle on Einstein's Theory 823 



Dr. B:ilth. van der Pol on Systems with " Propagated 

 Coupling" ; with a Note by A. W. Porter and R. E. Gibbs. 826 



Proceedings of the Geological Society : — 



Mr. H. S. Warren on a Natural " Eolith " Factory 

 beneath the Thanet Sand 828 



