CONTENTS op N° 238.— Fourth Series. 



XXXIX. On " Inductive Circuits," or the Application of Ohm's Law 

 to Problems of Electrostatic. By F. C. Webb, M.I.C.E page 325 



XL. On a new form of Voltameter and Voltastat. By Frederick 

 Guthrie, Ph.D., F.R.S.E., Professor of Physics and Chemistry, 

 Royal College, Mauritius 334 



XLI. Investigation of the Alteration produced by Heat in the Velo- 

 city of Propagation of Light in Water. By Richard Rfhlmann . . 336 



XLII. On Mr. Grove's " Experiment in Magneto-electric Induc- 

 tion." In a Letter to W. R. Grove, F.R.S. By J. Clerk Maxwell, 

 F.R.S 360 



XLIII. On Geological Time, and the probable Date of the Glacial 

 and the Upper Miocene Period. By James Croll, of the Geological 

 Survey of Scotland 363 



XLIV. On the Specific Magnetism of Iron. By Pliny Earle 

 Chase 384 



XLV. Proceedings of Learned Societies : — 



Royal Society: — Mr. J. Clerk Maxwell on Governors .... 385 

 Geological Society : — Mr. J. Prestwich on the Structure of 

 the Crag-beds of Norfolk and Suffolk, with some observations 

 on their Organic remains 398 



XLVI. Intelligence and Miscellaneous Articles: — 



On Stellar Spectra, by Father Secchi 400 



On an Optical Phenomenon, by Professor Robert Ball, Esq. . . 404 

 On an Apparatus for proving that the Electric Spark does not 

 pass through an Absolute Vacuum, by MM. Alvergniat .... 404 



%* It is requested that all Communications for this Work may be addressed, 

 post-paid, to the Care of Messrs. Taylor and Francis, Printing Office, Red 

 Lion Court, Fleet Street, London. 



