Stephen
Gray, in 1729, discovered
that the electric force, made
by rubbing glass, could be
sent for long distances
over a wire. The electricity
could, thus, be separated
from the rubbed bodies and
wasn't an exclusive property of
some material.
The
figure shows that the electric force of a rubbed glass
could be sent, through a wire, to the body of a person. There
is not a direct contact.