IV CONTENTS OF VOL. XLIX. FOURTH SERIES. 



Page 



Dr. Attfield on the Spectrum of Carbon 106 



Mr. L. Schwendler on the General Theory of Duplex Tele- 

 graphy 108 



Prof. O. Silvestri on the Eruption of Etna on the 29th of 



August, 1874 126 



Sir James Cockle on Primary Forms 134 



Prof. J. C. Draper on the Projection of the Fraunhofer Lines 



of Diffraction and Prismatic Spectra on a Screen 142 



Proceedings of the Royal Society : — 



Mr. R. Mallet on Volcanic Energy 144 



Mr. W. Spottiswoode on Combination of Colour by means 



of Polarized Light 146 



Prof. J. Tyndall on the Transmission of Sound 151 



Proceedings of the Geological Society : — 



ColoneljC. W. Jenks on the Occurrence of Sapphires and 

 Rubies in situ with Corundum, at the Culsagee Corun- 

 dum Mines, Macon Co., North Carolina 152 



Mr. R. Etheridge on the Relationship existing between the 



Echinothuridae and the Perischoechinidse 152 



Mr. W. Shone on the Discovery of Poraminifera &c. in 



the Boulder-clays of Cheshire 153 



Mr.* C. Callaway on the Occurrence of a Tremadoc Area 

 near the Wrekin in South Shropshire, with description 



of a new Fauna 153 



On the Expression of the Work relative to an Elementary 



Transformation, by J. Moutier 154 



On the Analogies presented by the Liberation of Oases from 

 their Supersaturated Solutions and the Decomposition of 



certain Explosive Bodies, by D. Oernez 157 



On Venus as a Luminous Ring, by Prof. C. S. Lyman ...... 159 



NUMBER CCCXXIV.— MARCH. 



Dr. H. F. Weber on the Specific Heat of the Elements Carbon, 

 Boron, and Silicon. — Part I. The Relation between the Spe- 

 cific Heat of these Elements in the free state and the Tem- 

 perature. (With a Plate.) 161 



Lord Rayleigh on a Statical Theorem 183 



Prof. E. Bouty's Studies on Magnetism 186 



Mr. F. Guthrie on Salt Solutions and Attached Water 206 



Lord Rayleigh on General Theorems relating to Equilibrium 



and Initial and Steady Motions 218 



Notices respecting New Books : — 



C. Ruchonnet's Exposition Gcometrique des Proprietcs 



Generales des Courbes , 225 



C. Ruchonnet's Elements de Calcul Approximatif 227 



