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CONTENTS OF VOL. XV 
(SIXTH SEEIES). 
NUMBEE LXXXV— JANUARY 1908. 
Page 
Dr. D. E. Comstock od the Eelation of Mass to Energy .... 1 
Messrs. A. C. and A. E. Jessup on the Evolution and Devo- 
lution of the Elements. (Plate VII.) 21 
Mr. L. V. Meadowcroft on the Curvature and Torsion of a 
Helix on any Cylinder, and on a Surface of Revolution . . 55 
Prof. D. N. Mallik on a Potential Problem 63 
Prof. D. N. Mallik : Experimental Determination of Magnetic 
Induction in an Elongated Spheroid 65 
Prof. E. H. Barton on Spherical Eadiation and Vibrations in 
Conical Pipes 69 
Mr. W. Ellis Williams on the Rupture of Materials under 
Combined Stress : — Tension and Hydrostatic Pressure. ... 81 
Messrs. K. Honda, T. Terada, and D. Isitani on the Secondary 
Undulations of Oceanic Tides. (Plates I.-VI.) 88 
Mr. J. D. Hamilton Dickson on rhe Joule-Kelvin Inversion 
Temperature, and Olszewski's Experiment. (Plate VIII.) 126 
Dr. C. V. Burton on the Thermally excited Vibrations of an 
Atmosphere 147 
Mr. A. Campbell on the Use of Variable Mutual Inductances. 
(Plate IX.) 155 
Mr. G. A. Schott on the Electron Theory of Matter and the 
Explanation of Magnetic Properties 172 
Mr. J. A. Tomkins on the Eocometry of a Concave Lens . . 198 
Notices respecting New Books : — 
M. C. Cheneveau's Eecherches sur les Proprietes Optiques 
des Solutions et des Corps Dissous 200 
Eivista di Scienza 200 
Dr. A. Seidell's Solubilities of Inorganic and Organic 
Substances 201 
