IV CONTENTS OF VOL. XXI. SIXTH SERIES. 



Page 



Mr. Andrew Stephenson on the Maintenance of Periodic 

 Motion by Solid Friction 161 



Mr. Andrew Stephenson on a Peculiar Property of the 

 Asymmetric System 166 



Mr. T. Eoyds on the Eenective Power of Lamp- and Platinum- 

 Black 167 



Proceedings of the Geological Society 173 



NUMBEE CXXIL— FEBEUAEY. 



Lord Eayleigh : Hydrodynamical Notes 177 



Prof. Louis T. More on the Eecent Theories of Electricity . . 196 

 Messrs. G-. F. C. Searle, A. C. W. Aldis and G. M. B. Dobson 

 on a Eevolving Table Method of determining the Curvature 



of Spherical Surfaces 218 



Sir J. J. Thomson on Rays of Positive Electricity. (Plate L) 225 

 Profs. H. Reubens and E. W. Wood on Focal Isolation of 



Long Heat-Waves , 249 



Prof. E, W. Wood on the Eesonance Spectra of Iodine .... 261 

 Prof. E. W. Wood and Mr. J. Franck : Transformation of a 

 Eesonance Spectrum into a Band-Spectrum by Presence of 



Helium. (Plate II.) . 265 



Dr. James Eobinson on Electric Dust Figures 268 



Prof. C. G, Barkla and Mr. T. Ayres on the Distribution of 



Secondary X-rays and the Electromagnetic Pulse Theory . 270 

 Notices respecting New Books : — 



Mr, Hastings Berkeley's Mysticism in Modern Mathe- 

 matics P — , . , . 278 



Proceedings of the Geological Society :— 



Mr. Linsdall Eichardson on the Eh^tic and Contiguous 

 Deposits of West, Mid, and Part of East Somerset . . 279 



NUMBEE CXXIIL— MARCH, 



Dr f J, W. Nicholson on the Bending of Electric Waves 

 round a Large Sphere. — IV. ....... T 281 



Dr. Eichard C. Tolman : Note on the Derivation from the 

 Principle of Eelativity of the Fifth Fundamental Equation 

 of the Maxwell-Lorentz Theory , 296 



Mr. O. W. Griffith on the Measurement of the Refractive 

 Index of Liquids 301 



Prof. R. W. Wood on the Destruction of the Fluorescence of 

 Iodine and Bromine Vapour by other Gases. (Plate III.). 309 



Mr. J. Franck and Prof. E. W. Wood on the Influence upon 

 the Fluorescence of Iodine and Mercury of Gases with 

 different Affinities for Electrons 314 



