CONTENTS OF VOL. XVIII. FIFTH SERIES. V 



Page 

 Rev. A. Irving on the Dyas (Permian) and Trias of Central 

 Europe and the true divisional line of these two forma- 

 tions 228 



On the Ellipticity of Planets, by L. d'Auria, late G-eodetical 



Engineer of the Italian Army 229 



On Idunium, a new Element, by Martin Websky 232 



NUMBER CXIIL— OCTOBER. 



Mr. J. J. Thomson on the Chemical Combination of Gases . . 233 



Dr. J. Croll on the Cause of Mild Polar Climates 268 



Mr. S. P. Langley on the Amount of the Atmospheric Ab- 

 sorption 289 - 



Prof. A. Kundt on the Electromagnetic Rotation of the Plane 

 of Polarization of Light by means of Iron, Cobalt, and 



Nickel 308 



Mr. D. J. Blaiklev's Experiments on the Velocity of Sound in 



Air. (Plate VII.) 328 



Mr. A. M. Worthington on the Surface Eorces in Eluids. 



(Plate VIII.) 334 



Mr. W. W. J. Nicol on the Nature of Solution.— Part II. 



Boiling-Points of Salt-Solutions . 364 



Mr. W. Moon on a Method of Calculating the Constant y, 

 expressing the Relation of the Specific Heat at Constant 



Pressure to the Specific Heat at Constant Volume 372 



Prof. J. J. Sylvester on Contrariants, a New Species of 



Invariants 374 



Proceedings of the Oeological Society : — 



Dr. Henry Hicks on the Pre-Cambrian Rocks of Pem- 

 brokeshire, with especial reference to the St. David's 



District 376 



Rev. J. Magens Mello on a specimen of Iron Amianthus. 377 

 Dr. C. Callaway on the Archaean and Lower Palaeozoic 



Rocks of Anglesey 378 



Lt.-Col. H. H. Godwin-Austen and Mr. W. Whitaker on 



the new Railway-cutting at Guildford 378 



Mr. H. G-. Spearing on the Recent Encroachment of the 



Sea at Westward Ho !, North Devon 380 



Mr. H. J. Eunson on the Range of the Palaeozoic Rocks 



beneath Northampton 380 



Mr. "W. F. Stanley on a Correction in the assumed 

 Amount of Energy developed by the Secular Cooling of 

 the Earth as stated by Robert Mallet, M.A., F.R.S. . . 382 

 Prof. J. W. Judd on the Jurassic Rocks which underlie 

 London 382 



