458 Geological Society: Mr. Fox's Notice of 



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 of the 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 electro-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 

 them. These results were not apparently modified by the method of 

 making the contact, or by the metal employed to effect it, provided an 

 adequate degree of pressure was employed. For instance, a point of 

 a copper wire pressed against a given ore-point was mostly as effec- 

 tual as a plate of that metal similarly treated ; and when zinc and 

 platinum were successively substituted for copper no change was 

 produced. 



It is, therefore, evident, Mr. Fox remarks, that these electric cur- 

 rents were independent of extraneous causes, and were derived from 

 the veins only. 



Towards the eastern part of the north mine arsenical pyrites 

 abounded immediately under the surface. On one extremity of the 

 apparatus being connected with it and the other with an ore-point 

 to the westward in the six-fathom-level, twenty-four fathoms of wire 

 being employed for this purpose, the current, which was from E. to 

 W., deflected the needle fifty to sixty degrees. Again, contact was 

 made with the ore-point in the six-fathom-level by means of a small 

 plate of copper attached to one of the wires and wedged against the 

 ore by a wooden pole, the other copper wire being firmly pressed 

 against the arsenical pyrites at the surface by means of a brass screw 

 passed through a block of wood, which was retained in its place by 

 a pole wedged against it. This arrangement admitted of the screw 

 being loosened in the block, and the metal in contact with the ore- 

 point being changed without inconvenience. Zinc was used after the 

 copper for making the contact with the ore-point, but without produ- 

 cing any modification of the current, which continued to deflect the 

 needle from fifty to sixty degrees; notwithstanding that any action be- 

 tween the copper in the six-fathom-level and the zinc at the surface, 

 if it h id existed, would have been in an opposite direction, and have 

 tended more or less to counteract the influence of the actual current. 

 Its energy, however, was sufficient to render a short bar of iron of a 

 horse-shoe form, with several coils of copper wire around it, feebly 

 magnetic, and affect a needle about two inches long, moving on a 



