136 MR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. 
from one to the other, it required a force of nearly one hundred pounds to 
break the contact. The pole to the left in the figure is the marked pole *. 
45. The indicating galvanometer, in all experiments made with this magnet, 
was about eight feet from it, not directly in front of the poles, but about 16° or 
17° on one side. It was found that on making or breaking the connexion of 
the poles by soft iron, the instrument was slightly affected ; but all error of ob- 
servation arising from this cause was easily and carefully avoided. 
46. The electrical effects exhibited by this magnet were very striking. When 
a soft iron cylinder thirteen inches long was put through the compound hollow 
helix, with its ends arranged as two general terminations (39.), these connected 
with the galvanometer, and the iron cylinder brought in contact with the two 
poles of the magnet (fig. 5.), so powerful a rush of electricity took place that the 
needle whirled round many times in succession ■'f~. 
47- Notwithstanding this great power, if the contact was continued, the 
needle resumed its natural position, being entirely uninfluenced by the posi- 
tion of the helix (30.). But on breaking the magnetic contact, the needle was 
whirled round in the opposite direction with a force equal to the former. 
48. A piece of copper plate wrapped once round the iron cylinder like a 
socket, hut with interposed paper to prevent contact, had its edges connected 
with the wires of the galvanometer. When the iron was brought in contact 
with the poles, the galvanometer was strongly affected. 
49. Dismissing the helices and sockets, the galvanometer wire was passed 
over, and consequently only half round the iron cylinder (fig. 6.); but even then 
a strong effect upon the needle was exhibited, when the magnetic contact was 
made or broken. 
50. As the helix with its iron cylinder was brought towards the magnetic- 
poles, but without making contact, still powerful effects were produced. When 
the helix, without the iron cylinder, and consequently containing no metal but 
* To avoid any confusion as to the poles of the magnet, I shall designate the pole pointing to the 
north as the marked pole ; I may occasionally speak of the north and south ends of the needle, but do 
not mean thereby north and south poles. That is by many considered the true north pole of a needle 
which points to the south ; but in this country it is often called the south pole. 
t A soft iron bar in the form of a lifter to a horse-shoe magnet, when supplied with a coil of this 
kind round the middle of it, becomes, by juxta-position with a magnet, a ready source of a brief but 
determinate current of electricity. 
