CONTENTS OF VOL. XXTI. 



(FIFTH SERIES). 



NUMBER CXXXIY.— JULY 1886. 



Page 

 The Rev. 0. Fisher on the Variations of Gravity at certain 

 Stations of the Indian Arc of the Meridian in Relation to 

 their Bearing upon the Constitution of the Earth's Crust . . 1 

 Mr. S. Bidwell on a Modification of Wheatstone's Rheostat . 29 

 Drs. W. Ramsay and S. Young on some Thermodvnamical 



Relations.— Parts IY. & Y " 32 



Prof. E. A. Letts and Dr. N. Collie on a new Method for the 



Preparation of Tin Tetrethyl 41 



Mr. E. F. J. Love on M. Mascart's Paper, " On Magnetiza- 

 tion " 46 



Mr. W. Baily on a Theorem relating to Curved Diffraction- 

 gratings 47 



Prof. Gr. Widemann's Magnetic Researches. (Plate I.) .... 50 

 Prof. W. Ostwald on the Seat of the Electromotive Forces in 



the Yoltaic Cell 70 



Proceedings of the Geological Society : — 



Mr. R. M. Deeley on the Pleistocene Succession in the 



Trent Basin 72 



Mr. R. N. Worth on the Existence of a Submarine Tri- 



assic Outlier in the English Channel off the Lizard . . 73 

 Dr. H. Hicks on the Pre-Cambrian Age of Certain Grani- 

 toid, Felsitic, and other Rocks in North-western Pem- 

 brokeshire 73 



Prof. T. G-. Bonney on some Rock-specimens collected by 



Dr. Hicks in North-western Pembrokeshire 74 



Mr. Aubrey Strahan on the Grlaciation of South Lan- 

 cashire, Cheshire, and the "Welsh Border 75 



Mr. J. Durham on the Yolcanic Rocks of North-eastern 



Fife 77 



Mr. F. Rutley on some Eruptive Rocks from the Neigh- 

 bourhood of St. Minver, Cornwall 78 



Mr. H. W. Monckton and Mr. R. S. Hemes on the Bag- 

 shot Beds of the London Basin 78 



Absolute Spherical Electrometer, by M. Lippmann 79 



Simple Demonstration of the Electrical Residue, by Fr. 

 Stenger 80 



