The first
machine for developing electricity was made by Otto von Guericke of
Magdeburg, about 1680. His machine consisted of a ball of sulphur about
six inches in diameter, which could be rotated. If the dry hand were
held against the sulphur while it was being turned in a dark room, the
sphere appeared to emit light: it also gave out a peculiar hissing or
crackling sound. Newton experimented a little with electricity, and
noticed that the rubber was an important element in developing
electricity. He does not seem to have given to the subject the same
attention that he gave to some other departments of science. Had he done
so, it is probable that he would have advanced the study a hundred
years; that is to say, he would probably have left it at the place where
it actually was in 1790. So great were his abilities that in one
lifetime he made greater additions to human knowledge than all the rest
of mankind had made during the preceding thousand years. In the month of
June, 1752, Franklin made that memorable experiment which immortalized
him. He flew his kite to the thunder-cloud, practically asking the
question of the lightning whether or not it was identical with
electricity. The lightning came down the wetted twine to his hand, and
proclaimed its identity.

For the next forty years the natural philosophers in both Europe and
America only rung the changes upon what was known. They flew kites to
the clouds; they made and charged Leyden jars, and discharged them
through wires and chains and circuits of clasped hands, and studied the
attractions and repulsions manifested by electrified bodies; but they
added nothing of importance in the way of experiments.

In 1791 Galvani, a professor of anatomy at Bologna, announced a
manifestation of electricity that was new and of a remarkable character,
having its origin in the muscles of animals, and so was called animal
electricity. He had some frogs' legs prepared for eating; by chance they
were placed near an electrical machine with which Galvani was
experimenting, so that a spark would occasionally pass to the legs, when
they would contract as often as a spark passed to them. The motion was
first observed by his wife, who called his attention to the phenomenon;
and he very soon discovered that the thighs of a frog, skinned and
suspended, made a very good electroscope. While experimenting in this
way he made another and more important discovery; namely, that, when
the muscles a