CONTENTS OF VOL. XIII. SIXTH SERIES. 



NUMBEE LXXVL— APEIL. 



Page 

 Prof. A. Gray on the Attraction of Ellipsoidal Shells and of 



Solid Ellipsoids at External and Internal Points, with some 



Historical Notes 3S5 



Dr. A. H. Bucherer on a New Principle of Eelativity in 



Electromagnetisin , 413 



Mr. A. Eussell on the Magnetic Eield and Inductance 



Coefficients of Circular, Cylindrical, and Helical Currents . 420 

 Prof. E. H. Barton and Mr. J. Penzer on Simultaneous 



Vibration-Curves of String and Bridge photographically 



obtained from a Monoehord. (Plates XL & XII.) 446 



Prof. L. T. More and Dr. H. S. Fry on the Appreciation of 



Difference of Phase of Sound-Waves 452 



Mr. J. Prescott on Convective Equilibrium of a Spherical Mass 



of G-as subject only to the Mutual Gravitation of its parts . 459 

 Prof. T. E. Lyle on Transformer Indicator Diagrams. (Plate 



XIII.) 468 



Mr. F. Twynian on Improvements in the Hiifner Type of 



Spectrophotometer 481 



Sir Oliver Lodge on the Density of the iEther 488 



Prof. "W. H. Bragg on the Influence of the Velocity of the 



a particle upon the Stopping Power of the Substance 



through which it passes 507 



Mr. J. P. Dalton on the Saturation Constants according to 



van der Waals's Equation 517 



Mr. J. P. Dalton on the Variation of Specific Heats with 



Temperature and Density 525 



Mr. J. P. Dalton on the Specific Heat of Saturated Vapours . . 536 

 Mr. F. B. Young on the Eelation of the Field at the Point of 



an Electrified Needle to the Mechanical Force resulting . . 542 

 Dr. T. M. Lowry on Osmotic Pressure from the Standpoint 



of the Kinetic Theory 552 



Notices respecting New Books : — 



Messrs. A. Cotton et H. Mouton's Les ITltramicroscopes 



et les Objets Ultramicroscopiques 559 



J. Pierpont's Lectures on the Theory of Functions of 

 Heal Variables 560 



NUMBEE LXXVII.— MAT. 



Prof. J. J. Thomson on Eays of Positive Electricity 561 



Mr. J. M. Adams on a Spectrum of the Eontgen Eays from 

 a Focus Tube, and the relatively Selective Absorption of 

 Eontgen Eays in certain Metals. (Plate XIV.) 576 



