CONTENTS OF VOL, VIIL 



(FIFTH SEEIES). 



NUMBEE XLYI.— JULY 1879. 



Page 

 Dr. F. Auerbach on the Passage of the Galvanic Current 



through Iron. (Plate I.) 1 



Prof. S. P. Thompson and Dr. 0. J. Lodge on Unilateral Con- 

 ductivity in Tourmaline Crystals 18 



Mr. F. Guthrie on the Fracture of Colloids. (Plates II. & III.) 25 

 Professors J. Perry and W. E. Ayrton on a neglected Principle 



that may be employed in Earthquake Measurements. 



(Plate IV.) 30 



Prof. D. E. Hughes on an Induction- balance and Experimental 



Eesearches therewith. (Plate V.) 50 



Mr. W. C. Roberts on the Examination of certain Alloys 



by the Aid of the Induction-balance. (Plate VI.) 57 



Mr. 0. Heaviside on the Theory of Faults in Cables 60 



Mr. 1ST. D. C. Hodges on the Size of Molecules 74 



Dr. J. W. Draper on a new Form of Spectrometer, and on the 



Distribution of the Intensity of Light in the Spectrum .... 75 



On the Electric Light, by M. J. Jamin 81 



On the Deviations of Ampere's Theory of Magnetism from 



the Theory of the Electromagnetic Forces, by J. Stefan . . 83 

 On the Production of Barium from Barium -amalgam, by Julius 



Donath, of Graz 84 



NUMBEE XLVIL— AUGUST. 



Dr. J. Kerr's Electro-optic Observations on various Liquids. 85 

 Prof. H. A. Eowland on Professors Ayrton and Perry's new 

 Theory of the Earth's Magnetism, with a Note on a new 



Theory of the Aurora 102 



Prof. Piazzi Smyth on Carbon and Carbo-Hydrogen, Spectro- 

 scoped and Spectrometed in 1879 107 



