VI CONTENTS OF VOL. XLIX. FIFTH SERIES. 



Proceedings of the Geological Society : — Page 



Dr. W. T. Blanford on a Particular Form of Surface, 

 the result of Glacial and Subaerial Erosion, seen on 



Loch Lochy and Elsewhere 413 



Mr. C. A. Matley on the Geology of Northern Anglesey. 4L4 

 Mr. A. Octavius Watkins on the Formation of Dendrites. 415 

 Intelligence and Miscellaneous Articles : — 



On the Theory of the Function of the Condenser in an 

 Induction-Coil, by Dr. B. Walter 416 



NUMBER OCC— MAY. 



Dr. S. R. Milner on the Theory of Solution Pressure 417 



Dr. F. G. Donnan on the Relative Bates of Effusion of 



Argon, Helium, and some other Gases 423 



Mr. T. H. Blakesley on some Improved Formulae and Methods 



connected with Lenses 447 



Prof. Oliver Lodge on the Controversy concerning Yolta's 



Contact Force 454 



Mr. S. H. Burbury on certain supposed Irreversible Pro- 

 cesses 475 



Mr. W. A. Price on Petrovitch's Apparatus for integrating 



Differential Equations of the First Order 487 



Mr. T. S. Moore on the Reversibility of Voltaic Cells 491 



Notices respecting New Books : — 



Fred. Walleranfc's Groupements Crystallins 496 



A. Turpain's Recherches Experimentales sur les Oscil- 

 lations Electriques 497 



Dr. D. A. Murray's Plane Trigonometry for Colleges 



and Schools 498 



Dr. H. Landolt's Optical Activity and Chemical Com- 

 position 498 



Proceedings of the Geological Society : — 



Dr. J. W. Gregory on the Geology of British East Africa: 



Parts II. & III 499 



Mr. Philip Lake on Bala Lake and the River-System of 



North Wales 501 



Prof. T. G. Bonney on the Bunter Pebble-Beds of the 



Midlands and the Source of their Materials 501 



Intelligence and Miscellaneous Articles : — 



The Echelon Spectroscope, by E. W. Marchant 503 



On an Interference Method of Measuring the Diameters 

 of Distant Planets and Stars, byM. Maurice Hainy . . 503 



