alvanometer wire was
connected with the outside coating of the battery, and then both these with
the discharging train; the end A of the galvanometer wire was connected
with a discharging rod by a wet thread four feet long; and finally, when
the battery (291.) had been positively charged by about forty turns of the
machine, it was discharged by the rod and the thread through the
galvanometer. The needle immediately moved.

297. During the time that the needle completed its vibration in the first
direction and returned, the machine was worked, and the battery recharged;
and when the needle in vibrating resumed its first direction, the discharge
was again made through the galvanometer. By repeating this action a few
times, the vibrations soon extended to above 40 deg. on each side of the line
of rest.

298. This effect could be obtained at pleasure. Nor was it varied,
apparently, either in direction or degree, by using a short thick string,
or even four short thick strings in place of the long fine thread. With a
more delicate galvanometer, an excellent swing of the needle could be
obtained by one discharge of the battery.

299. On reversing the galvanometer communications so as to pass the
discharge through from B to A, the needle was equally well deflected, but
in the opposite direction.

300. The deflections were in the same direction as if a voltaic current had
been passed through the galvanometer, i.e. the positively charged surface
of the electric battery coincided with the positive end of the voltaic
apparatus (268.) and the negative surface of the former with the negative
end of the latter.

301. The battery was then thrown out of use, and the communications so
arranged that the current could be passed from the prime conductor, by the
discharging rod held against it, through the wet string, through the
galvanometer coil, and into the discharging train (292), by which it was
finally dispersed. This current could be stopped at any moment, by removing
the discharging rod, and either stopping the machine or connecting the
prime conductor by another rod with the discharging train; and could be as
instantly renewed. The needle was so adjusted, that whilst vibrating in
moderate and small arcs, it required time equal to twenty-five beats of a
watch to pass in one direction through the arc, and of course an equal time
to pass in the other direction.

302. Thus arranged, and the needle being stationary, the current, d