PROCEEDINGS 
OF 
THE GEOLOGICAL SOCIETY OF LONDON. 
4 
Vout. III. Parr II. 1842. No. 90. 
June 1.—William Ghrimes Kell, Esq., of 43 Bedford Row, was 
elected a Fellow of this Society. 
A paper was first read entitled, ‘‘ Notice of some Experiments on 
the Electric Currentsin Pennance Mine, near Falmouth.” By Robert 
Were Fox, Esq. Communicated by the President. 
The Pennance mine is situated in killas, but to its N.W. is a 
granite range. 'l'wo veins have been worked ; the more northerly, 
which is about five feet wide and has a slight northerly dip, to the 
depth of sixteen fathoms; and the other, which is about two feet thick 
and dips apparently to the south, to the depth of eight fathoms. Both 
veins nearly coincide with the magnetic meridian in their horizontal 
bearing. They abound with arsenical and iron pyrites interspersed 
with oxide of tin and sulphurets of copper and lead, arranged in many 
parts in nearly vertical layers parallel to the sides of the veins. 
The author was assisted in his experiments by Mr. J. Fox. ‘The ap- 
paratus employed was adapted only for experiments on not: very 
feeble electric currents, and consisted of copper wires from. 2th to _ 
zoth of an inch in diameter, and plates of different metals, with other 
contrivances for varying the methods of producing contact with the 
ore-points selected in the veins. The galvanometer had only-oue 
needle 24 inches long, 1th of an inch wide, and jth thick, having 
an agate cup and moving on a steel point. A. fine brass wire was 
coiled forty-eight times round the box which contained the needle. 
The ore-points connected with the two extremities of the appa- 
ratus were, in some instances, only six or eight fathoms apart, but 
in others thirty, forty, and even 100. The small portion of the south 
vein which could be tried produced a deflection in the needle of about 
20° from the point of rest, after the circuit had been repeatedly made 
and broken; the currents passing from east to west through the ap- 
paratus. In the north vein the deflections amounted to 45°, 60°, 
and 80° in different levels, the direction ofthe currents being the 
same as in the south vein; and in the ‘eastern portion of the six- 
fathom-level the needle traversed completely round and continued to 
revolve a short time after the circuit was broken. 
Sulphuret of lead being much more €lectro-positive: than arsenical 
copper or iron pyrites, contact was made with those ores, generally 
dry, without affecting the currents, when the ore-points thus varied 
were near together, and there was no defect in the contact with 
VOL. IIl. PART II. 3Q 
