﻿CONTENTS of N° 271.— Fourth Series. 



XIII. On the Cause of the Motion of Glaciers. By John Ball, 

 F.R.S page 81 



XIV. On the Chemical Composition and Microscopic Constitution 

 of certain Cornish Rocks. By J. Arthur Phillips, F.C.S., M. 

 Inst. C.E., &c 87 



XV. On the Light from the Sky, its Polarization and Colour. By 



the Hon. J. W. Strutt, Fellow of Trinity College, Cambridge .... 107 



XVI. Addendum to a Paper on the Theory of the Tides. By the 

 Rev. T. K. Abbott, Fellow and Tutor of Trinity College, Dublin . . 120 



XVII. On the Spectrum of the Aurora borealis. By F. Zollner. 122 



XVIII. On Athermogenic Condensation. By the Rev. J. M. 

 Heath 127 



XIX. On a small Universal Stellar Spectroscope. By M. Sigmtjnd 

 Merz. (With a Plate.) 129 



XX. Estimation of Zinc on Galvanized Iron. By Thomas T. P. 

 Bruce Warren 132 



XXI. Researches on the Specific Heats, Densities, and Expansions 



of some Liquids. By C. Marignac 134 



XXII. Proceedings of Learned Societies : — 



Geological Society: — The Rev. J. M. Mello on an altered 

 Clay-bed and Sections in Tidesw ell Dale, Derbyshire ; Dr. R. 

 Brown on the Physics of Arctic Ice as explanatory of the Gla- 

 cial Remains in Scotland 154-155 



Royal Geological Society of Ireland : — Mr. E. Hull on 

 the Geological Age of the Ballycastle Coai-field, and its rela- 

 tion to the Carboniferous Rocks of the West of Scotland .... 155 



XXIII. Intelligence and Miscellaneous Articles : — 



On some Hydro- and Thermoelectric Forces, reduced to Sie- 

 mens' s Unit of Resistance and Weber's Unit of Current, by 

 F. Kohlrausch 157 



On the Duration of Flashes of Lightning, by O. N. Rood .... 159 



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

 ion Court, Fleet Street, London. 



