CONTENTS OF VOL. XX. — FOURTH SERIES. Vll 



Page 

 Prof. Owen on some small fossil Vertebra from near Frome, 



Somersetshire 401 



On the Law of the Propagation of Electricity in Imperfect Con- 

 ductors, by J. M. Gaugain 401 



Wood's Fusible Metal 403 



Description of an Apparatus for generating Hydrogen, Carbonic 



Acid, and Sulphuretted Hydrogen, by G. Gore, Esq 405 



On New Forms of Actinometers, by C. J. Burnett, Esq 406 



On Arsenic in Coal, by Dr. R. A. Smith 4Q8 



NUMBER CXXXV.— DECEMBER. 



Mr. D. Vaughan on the Form of Satellites revolving at small 



distances from their Primaries 409 



Mr. A. Cayley on the Cubic Centres of a Line with respect to 



Three Lines and a Line . 418 



Mr. D. Forbes on Darwinite, a new Mineral Species from Chile. 423 

 M. G. R. Dahlander on the Form assumed by a Fluid Shell re- 

 volving freely within a Hollow Spheroid 426 



Prof. Challis on a Theory of Galvanic Force 431 



Dr. P. L. Rijke on the Inductive Spark 441 



Mr. C. W. Merrifield on Approximation to the Integrals of Irra- 

 tional Functions by means of Rational Substitutions 446 



M. H. Ste. -Claire Deville on the Decomposition of Bodies by 

 Heat, and on Dissociation. ........................... 448 



Prof. W. Beetz on the Molecular Changes produced by Mag- 

 netization 458 



Proceedings of the Royal Society : — 



Major-General Sabine on the Solar-diurnal Variation of 



the Magnetic Declination at Pekin . . , 469 



Mr. T. Wharton Jones on the Focal Power of Eyes for 



Horizontal and Vertical Rays 480 



Proceedings of the Geological Society : — 



The Rev. O. Fisher on the Denudation of Soft Strata . . 483 

 Dr. Dawson on an undescribed Fossil Fern from the Lower 



Coal-measures of Nova Scotia 485 



Mr. C. Rickman on the Sections of Strata exposed in the 

 Excavations for the South High-level Sewer at Dulwich. 486 

 On the Relation between the Direction of the Vibration of Light 



and the Plane of Polarization, by Friedrich Eisenlohr 486 



On the Specific and Latent Heat of Naphthaline, by M. Alluard. 488 



NUMBER CXXXVI.— SUPPLEMENT. 



Prof. Sylvester on the Pressure of Earth on Revetment Walls 489 

 Mr. T. Tate's Experimental Researches on the Laws of Absorp- 

 tion of Liquids by Porous Substances 500 



