of time Otto Guericke added to these simple discoveries that of electric
light, still further established by Isaac Newton, with his glass globe.
A Dutch philosopher at Leyden, having observed that excited electrics
soon lost their electricity in the open air, especially when the air was
full of moisture, conceived the idea that the electricity of bodies
might be retained by surrounding them with bodies which did not conduct
it; and in 1745 the Leyden jar was invented, which led to the knowledge
that the force of electricity could be extended through an indefinite
circuit. The French savants conveyed the electric current through a
circuit of twelve thousand feet.

It belonged to Franklin, however, to raise the knowledge of electricity
to the dignity of a science. By a series of experiments, extending from
1747 to 1760, he established the fact that electricity is not created by
friction, but merely collected from its state of diffusion through other
matter to which it has been attracted. He showed further that all the
phenomena produced by electricity had their counterparts in lightning.
As it was obvious that thunder clouds contained an immense quantity of
the electrical element, he devised a means to draw it from the clouds by
rods erected on elevated buildings. As this was not sufficiently
demonstrative he succeeded at length in drawing the lightning from the
clouds by means of a kite and silken string, so as to ignite spirits and
other combustible substances by an electric spark similar to those from
a Leyden jar. To utilize his discovery of the identity of lightning with
electricity he erected lightning-rods to protect buildings, that is, to
convey the lightning from the overhanging clouds through conductors to
the ground. The importance of these lightning-rods was doubtless
exaggerated. It is now thought by high scientific authorities that tall
trees around a house are safer conductors in a thunder storm than
metallic rods; but his invention was universally prized most highly for