[33] This was a discovery of the very ingenious Mr. Kinnersley, and
by him communicated to me.
[34] To charge a bottle commodiously through the coating, place it on
a glass stand; form a communication from the prime conductor to the
coating, and another from the hook to the wall or floor. When it is
charged, remove the latter communication before you take hold of the
bottle, otherwise great part of the fire will escape by it.
[35] I have since heard that Mr. Smeaton was the first who made use
of panes of glass for that purpose.
[36] Contrived by Mr. Kinnersley.
[37] We have since found it fatal to small animals, though not to
large ones. The biggest we have yet killed is a hen. 1750.
[38] This was afterwards done with success by Mr. Kinnersley.
[39] Probably the ground is never so dry.
[40] We afterwards found that it failed after one stroke with a large
bottle; and the continuity of the gold appearing broken, and many of
its parts dissipated, the electricity could not pass the remaining
parts without leaping from part to part through the air, which always
resists the motion of this fluid, and was probably the cause of the
gold's not conducting so well as before; the number of interruptions
in the line of gold, making, when added together, a space larger,
perhaps, than the striking distance.
[41] The river that washes one side of Philadelphia, as the Delaware
does the other; both are ornamented with the summer habitations of
the citizens, and the agreeable mansions of the principal people of
this colony.
[42] As the possibility of this experiment has not been easily
conceived, I shall here describe it.--Two iron rods, about three
feet long, were planted just within the margin of the river, on the
opposite sides. A thick piece of wire, with a small round knob at
its end, was fixed on the top of one of the rods, bending downwards,
so as to deliver commodiously the spark upon the surface of the
spirit. A small wire fastened by one end to the handle of the spoon,
containing the spirit, was carried a-cross the river, and supported
in the air by the rope commonly used to hold by, in drawing the
ferry-boats over. The other end of this wire was tied round the
coating of the bottle; which being charged, the spark was delivered
from the hook to the top of the rod standing in the water on that
side. At the same instant the rod on the other side delivered a spark
into the spoon, and fired the spirit; the electric fire returning to
the coating of the bottle, through the handle of the spoon and the
supported wire connected with them.
That the electric fire thus actually passes through the water, has
since been satisfactorily demonstrated to many by an experiment of
Mr. Kinnersley's, performed in a trough of water about ten feet long.
The hand being placed under water in the direction of the spark
(which always takes the strait or shortest course, if sufficient, and
other circumstances are equal) is struck and penetrated by it as it
passes.