VI CONTENTS OF VOL. VI. SIXTH SERIES. 



Page 

 Messrs. Y. Crcmieu and H. Pender on the Magnetic Effect of 



Electric Convection , 442 



Mr. G. W. "Walker on the Theory of Refraction in Gases. 



(Plate XIX.) ■ 464 



Sir W. Ramsay end Dr. B. D. Steele on the Vapour-Densities 



of some Carbon Compounds ; an Attempt to Determine 



their correct Molecular Weights. (Plate XX.) 492 



Mr. Edgar Buckingham on a Modification of the Plug 



Experiment 518 



Mr. Thomas H. Blakesley on Single-Piece Lenses. (Plate 



XXI.) 521 



Mr. R. J. Sowter on Astigmatic Aberration 524 



Mr. R. Chartres on " Minimum Deviation through a Prism " . 529 

 Mr. S. H. Burburj on Mr. J. H. Jeans' Theory of Gases . . 529 

 Mr. G. W. Walker on Unsymmetrical Broadening of Spectral 



Lines 536 



Notices respecting New Books : — • 



Aide-Memoire de Photographic pour 1903 540 



Dr. W. Voigt's Thermodynamik 540 



Proceedings of the Geological Society 541-548 



NUMBER XXXV.— NOVEMBER. 



Prof. Thomas R. Lyle : Preliminary Account of a Wave- 

 Tracer and Analyser. (Plates XXII & XXIII.) 549 



Mr. H. S. Allen on tlie Effect of Errors in Ruling on the 

 Appearance of a Diffraction-Grating. (Plate XXIV.). .. . 559 



Mr. E. P. Adams on Water Radioactivity 563 



Messrs. J. E. Petavel and R. S. Hutton on the Effect of 

 Pressure upon Arc Spectra. (Plate XXV.) 569 



Prof. R. W. Wood on Photographic Reversals in Spectrum 

 Photographs. (Plate XXVI.) 577 



Hon. R. J. Strutt on an Experiment to Exhibit the Loss of 

 Negative Electricity by Radium . 588 



Mr. G. C. Simpson on Charging through Ion Absorption 

 and its Bearing on the Earth's Permanent Negative Charge. 589 



Prof. J. S. Townsend on the Genesis of Ions by the Motion 

 of Positive Ions in a Gas, and a Theory of the Sparking 

 Potential .* 598 



Mr. Norman R. Campbell on some Experiments on the Elec- 

 trical Discharge from a Point to a Plane 618 



Notices respecting New Books : — 



Dr. L. Decombe's La Compressibilite des Gaz Reels. . . . 627 

 Prof. H. C. Jones's Principles of Inorganic Chemistry. 627 

 II Moto dei loni nelle Scariche Elettriche 628 



Proceedings of the Geological Society 629-636 



