IV CONTENTS OE VOL. XXX. SIXTH SERIES. 



NUMBER CLXXVL— AUGUST. 



Page 



Prof. F. Soddy and Miss A. F. R. Hitcliins on the Relation 

 between Uranium and Radium. — Fart VI. The Life-period 

 of Ionium 209 



Miss Jadwiga Szmidt (Petrograd) on the Excitation of 7 Bays 

 by Fays 220 



Prof. E. Taylor Jones on the most Effective Primary Capacity 

 for Induction-coils and Tesla Coils 224 



Prof. E. Marsden and Mr. "W. C. Lantsberry on the Passage 

 of a Particles through Hydrogen. — II 240 



Mr. K. F. Nesturch on the Probability of Ionization and 

 Radiation of Gas Molecules due to Collision with Electrons. 244 



Prof. P. J. Daniell on the Coefficient of End-Correction. — 

 Part II 248 



Dr. A. C. Crehore on Construction of the Diamond with 

 Theoretical Carbon Atoms 257 



Mr. E. H. Smart on the Third-Order Aberrations of a Sym- 

 metrical Optical Instrument 270 



Mr. "W. G. Brown on Reflexion from a Moving Mirror .... 282 



Prof. W. B. Morton and Mr. J. Vint on the Paths of the 

 Particles in some cases of Motion of Frictionless Fluid 

 in a Eotating Enclosure. (Plates I. & II.) 284 



Mr. Gr. H. Livens on the Electron Theory of Metallic Con- 

 duction.— IV 287 



Prof. 0. W. Bichardson on Metallic Conduction 295 



Prof. E. W. Wood : Experimental Determination of the 

 Law of Eeflexion of Gas Molecules. (Plate III.) 300 



Prof. W. H. Bragg on the Structure of the Spinel Group of 

 Crystals 305 



Mr. C. E. Mendenhall and Prof. B. W. Wood on the Effect 

 of Electric and Magnetic Fields on the Emission Lines of 

 Solids. (Plate IV.) 316 



NUMBER CLXXVIL— SEPTEMBEE. 



Sir J. J. Thomson on the Mobility of Negative Ions at Low 

 Pressures 321 



Lord Eayleigh on the Stability of the Simple Shearing Motion 

 of a Viscous Incompressible Fluid 329 



Sir E. Rutherford, Prof. J. Barnes, and Mr. H. Bichardson 

 on Maximum Frequency of the X Bays from a Coolidge 

 Tube for Different Voltages 339 



Sir E. Rutherford and Prof. J. Barnes on the Efficiency of 

 Production of X Rays from a Coolidge Tube 361 



Prof. J. Barnes on the High-Frequency Spectrum of Tungsten. 368 



