CONTENTS OF VOL. XXVI. FIFTH SERIES. VU 



NUMBER CLXin.— DECEMBER. 



Dr. S. P. Thompson on the Conditions of Self-Excitation in a 

 Dynamo Machine , 469 



Mr. C. Tomlinson on the Weathering of Bocks, and certain 

 Electrical Phenomena, suggested by some Statements in a 

 popular Novel 475 



Mr. O. Heaviside on Electromagnetic Waves, especially in re- 

 lation to the Vorticity of the Impressed Forces j and the 

 Forced Vibrations of Electromagnetic Systems 488 



Note by Sir VT. Thomson on his Article on Reflexion and Re- 

 fraction of Light in the November Number 500 



Mr. J. Brown on Figures Produced bv Electric Action on 

 Photographic Dry Plates. (Plates VI. & VII.) 502 



Prof. S. P. Langley on the Invisible Solar and Lunar Spectrum 505 



Mr. R. T. Glazebrook on the Application of Sir "W. Thomson's 

 Theory of a Contractile iEther to Double Refraction, Dis- 

 persion, Metallic Reflexion, and other Optical Problems . . 521 



Compressibility of the Gases Oxygen, Hydrogen, Nitrogen, 

 and Air up to 3000 Atmospheres, by M. E. H. Amagat . . 541 



Observations on Brewster's Neutral Point, by MM. J. L. 

 Soret and C. Soret 542 



Index 544 



PLATES. 



I. Illustrative of Messrs. Gee and Holden's Paper on Irreciprocal 

 Conduction. 



II. Illustrative of Mr. J. Joly's Paper on a Hydrostatic Balance. 



III. Illustrative of Dr. E. H. Cook's Paper on the Existence of an 



L ndulatory Movement accompanying the Electric Spark. 



IV. & V. Illustrative of Mr. Tanakadate's Paper on the Mean In- 



tensity of Magnetization of Soft Iron Bars of Various Lengths 

 in a Uniform Magnetic Field. 



VI. & VII. Illustrative of Mr. J. Brown's Paper on Figures produced by 

 Electric Action on Photographic Dry Plates. 



