﻿IV CONTENTS OF VOL. XXIII. SIXTH SERIES. 



NUMBEE CXXXIV.— FEBEUAEY. 



Page 

 Prof. J. Joly on the Eadioactivity of the Eocks of the 



St. G-othard Tunnel 201 



Mr. L. Yegard on the Properties of the Eays producing 



Aurora Borealis , 211 



Mr. Louis Vessot King on the Cosine Law of Eadiation. . . . 237 

 Mr. Louis Vessot King on Absorption Problems in Eadio- 

 activity. (Plate VII.) 242 



Mr. J. IT. T. Eoberts on a Method of Investigating the 



Transpiration oE Gases through Tubes 250 



Dr. J. Eobinson on Photo-Electric Fatigue 255 



Prof. O. W. Richardson on the Electron Theory of Contact 



Electromotive Force and Thermoelectricity 263 



Mr. Arnold L. Fletcher on the Eadium Content of Secondary 



Eocks 279 



Drs. F. Fajans and TV. Makovver on the Growth of Eadium C 



from Eadium B 292 



Mr. H. G. J. Moseley and Br. "W. Makower on y Eadiation 



from Eadium B .' 302 



Prof. E. W. Wood on Diffraction Gratings with Controlled 



Groove Form and Abnormal Distribution of Intensitv. . . . 310 

 Prof. C. G. Barkla and Mr. L. Simons on Ionization in 



Gaseous Mixtures bv Eontgen Eadiation 317 



Intelligence and Miscellaneous Articles: — 



Note to Paper in the December number, by Dr. J. "W. 



Nicholson " 333 



On Methods of Harmonic Analysis, bv Prof. T. E. Lvle 



and Prof. S. P. Thompson * * . . 334 



On relations between Atomic Volumes and Spectra, by 

 Prof. Dr. N. Eeinganum 336 



NUMBEE CXXXV.— MAECH. 



Prof. Percival Lowell on the Asteroids 337 



Dr. Gwilym Owen and Mr. J. H. T. Eoberts on the Effect 



of Clouds on Ionization 352 



Messrs. J. H. T. Eoberts and E. Meigh on the Instability 



of Gaseous Jets 368 



Prof. Ei chard C. Tolman : Non-Newtonian Mechanics, The 



Mass of a Moving Body 375 



Prof. A. Anderson : Theory of the Behaviour of the Quadrant 



Electrometer 380 



Dr. C. V. Burton on the Micro-Azimometer : an Instrument 



for measuring small Angular Displacements 385 



Dr. Norman Campbell on Ionization by Collision 400 



Messrs. Karl Scheel and "Wilhelm Heuse : Concerning the 



Thermal Expansion of Mercury, Remarks on a Paper by 



Callendar and Moss 412 



