CONTENTS OF VOL. XLIII. SIXTH SERIES. Vll 



Page 



Dr. Dorothy Wrinch on the Orbits in the Field of a Doublet 993 



Dr. E. H. Kennard on a Simplified Proof for the Retarded Poten- 

 tials and Huyghens's Principle 1014 



Prof. S. P. Timoshenko on the Forced Vibrations of Bridges 1018 



Prof. Frank Horton and Miss A. C. Davies on the Occurrence of 



Ionization by Cumulative Effects 1020 



Prof. S. Timoshenko on the Buckling of Deep Beams 1023 



Mr. Frank M. Lidstone on the Measurement of Absolute Viscosity. 1(24 

 Intelligence and Miscellaneous Articles : — 



On the Measurement of Absolute Viscosity, by Jobn Satterly . 1024 



NUMBER CCLVIII.— JUNE. 



Dr. Albeit C. Crehore on the Hydrogen Molecule.— Ill 1025 



Mr. Allen G. Shenstone and Prof. Herman Schlundt on a Deter- 

 mination of the Number of a-Particles per Second emitted by 



Thorium C of known y-Ray Activity 1 038 



Mr. Arthur Fairbourne on Restricted Movements of Molecules at 

 very low pressures : A Limit of Applicability of the Second 



Law of Thermodynamics 1047 



Mr. E. J. Hartung on the Construction and Use of the Steele-Grant 



Microbalance 1056 



Mr. C. F. Bickerdike on the Interaction between Radiation and 



Electrons 1064 



Mr. D. Coster on the Spectra of X-rays and the Theory of Atomic 



Structure.— I. (Plate XXIII.) 1070 



Mr. V. A. Bailey on a Development of Maxwell's Capacity Bridge . 1107 

 Prof. N. Bohr on the Selection Principle of the Quantum Theory . 1112 

 Prof. R. Whiddington on X-ray Electrons. (Plate XXIV.) . .'. . 1116 

 Messrs. J. S. Townsend and V. A. Bailey on the abnormally long 



Free Paths of Electrons in Argon 1127 



Mr. Satvendra Ray on Viscosity of Air in a Transverse Electric 



Field * 1129 



Notices respecting New Books : — 



Prof. E. H. Neville's Multilinear Functions of Direction and 



their uses in differential geometry 1130 



Prof. H. S. Carslaw's Introduction to the Mathematical 



Theory of the Conduction of Heat in Solids 1131 



Sir George Beilbv's The Aggregation and Flow of Solids .... 1131 

 Prof. E. F. Burton's The Physical Properties of Colloidal 



Solutions 1132 



Dr. Norman R. Campbell's Series Spectra 1132 



Dr. Felix Auerbach's Moderne Magnetik 1134 



Proceedings of the Geological Society : — 



Mr. Henry Brewer Milner on the Nature and Origin of the 

 Pliocene Deposits of the County of Cornwall and their 

 bearing on the Pliocene Geography of the South- West of 



England 1135 



Mr. Launcelot Owen on the Phosphate Deposit of Ocean 

 Island 1136 



Index 1137 



