Electric Currents in Pennance Mine. 459 



pivot in a close box. Each pole of the needle was about three inches 

 from the extremity of the bar, and was deflected about 2° from its 

 point of rest, on the current being made through the coils of wire ; 

 and where the direction of the current was reversed, a similar de- 

 flection of the needle to the opposite side was produced. The effect, 

 Mr. Fox observes, would have been greater had the experiment been 

 made entirely in the six-fathom-level, where the electric action was 

 stronger, or if the needle had been suspended and not mounted on 

 a pivot. 



Having removed the electro-magnet, and other things remaining 

 the same, a glass tube in the form of a V, having moistened clay at 

 the bottom, was placed in the circuit with water in one branch and 

 a solution of sulphate of copper in the other. Small cylinders of cop- 

 per pyrites, taken from the same piece of ore, were employed to con- 

 nect these liquids respectively with the opposite wires, the ore at the 

 positive end of the wire having been partly dipped in water, and that 

 at the negative end in the solution of sulphate of copper. The wires 

 were kept at some distance above the level of the liquids, and as a 

 further precaution, the portions not in contact with the ore were 

 coated with sealing-wax. The liquids in both branches were at the 

 same level, and corks were inserted to retain the pyrites in the same 

 positions. This apparatus remained undisturbed for three days, 

 when the column of the solution of sulphate of copper was found to 

 have increased in height at the expense of the water in the other 

 branch, the difference being about one-tenth of an inch. On the 

 copper pyrites in the solution of sulphate of copper being examined, 

 it was found to be partly coated with metallic copper. 



Both these effects were, therefore, produced, Mr. Fox observes, 

 solely by means known to exist in the earth, and the experiments, 

 he adds, seem, therefore, to have a direct and unequivocal bearing, not 

 only on the decomposition of metallic salts under the surface, but on 

 the causes which affect the different levels of subterranean springs, 

 and the purification of water from bodies which it may hold in solution. 



A memoir " On the Elevation and Denudation of the District of 

 the Lakes of Cumberland and Westmoreland." By William Hop- 

 kins, Esq., F.G.S., was then laid before the Society, an abstract of 

 which has already appeared in the Phil. Mag. S. 3. vol. xxi. p. 468. 



June 15, 1842. — A paper was first read " On the packing of Ice in 

 the river St. Lawrence ; on a Landslip in the modern deposits of its 

 valley ; and on the existence of Marine Shells in those deposits as 

 well as upon the mountain of Montreal." By W. E. Logan, Esq., 

 F.G.S. 



1. The paper commences with a general description of the river 

 St. Lawrence, from the junction of the Ottawa in Lake St. Louis, 

 above Montreal, to Lake St. Peter, fifty miles below it, with a more 

 particular account of the rapids of Lachine and the Sault Normand, 

 produced by ledges or floors of trap rock. The author then proceeds 

 to give an account of the packing of the ice near Montreal. 



The frosts commence about the end of November, and a margin of 

 ice of some strength soon forms along the shores $ and wherever the 



