CONTENTS OF VOL. XXX. FOURTH SERIES. Vll 



Page 



Prof. Cayley on a Property of Commutants 411 



Prof. Cayley on the Signification of an Elementary Formula of 



Solid Geometry . . 413 



Mr. G. Gore on Chemical Reactions obtained by employing 



Anhydrous Liquids as Solvents 414 



Dr. W. von Bezold on Twilight 419 



M. W. Holtz on a new Electrical Machine. (With a Plate.) . 425 



Mr. R. Templeton on Fractions for the Value of M 434 



Mr. J. J. Waterston on Electric Conduction, and the possibility 

 of curing the retardation of Electric Waves in Submarine 



Telegraph Lines 440 



Dr. Atkinson's Chemical Notices from Foreign Journals ..... 443 

 Proceedings of the Geological Society : — 



Mr. R. A. C. Godwin-Austen on the Submarine Forest- 

 beds in Porlock Bay 452 



The Rev. R. Boog Watson on the Marine Origin of the 



" Parallel Roads " of Glen Roy 452 



On the Electricity of the Torpedo, by M. Ch. Matteucci .... 453 

 On a New Aventurine, with Chrome as a Base, by M. J. 



Pelouze 455 



On the Detection of Poisoning by Carbonic Oxide, by M. Hoppe- 



Seyler 456 



Relation of the Weight of a Magnetizing Spiral to the Magne- 

 tizing Force, by Dr. Menzzer 457 



Another New Form of the Heliotrope, by K. A. Steinheil .... 458 

 Index 460 



PLATES. 



I. Illustrative of Prof. Magnus's Paper on the different properties of 

 the Heat radiated by Rough and by Bright Surfaces. 



II. Illustrative of Sir David Brewster's Paper on the Polarization of the 

 Atmosphere. 



III. Illustrative of M. A. Thalen's Paper on the Determination of the 



Limit of Elasticity in Metals. 



IV. Illustrative of Mr. A. Bird's Paper on a Water-Barometer. 



V. Illustrative of M. W. Holtz's Paper on a new Electrical Machine. 



