hich is dated March 28, 1747. In these he shows
the power of points in drawing and throwing off the electrical matter,
which had hitherto escaped the notice of electricians. He also made the
grand discovery of a _plus_ and _minus_, or of a _positive_ and
_negative_ state of electricity. We give him the honour of this without
hesitation; although the English have claimed it for their countryman,
Dr. Watson. Watson's paper is dated January 21, 1748; Franklin's July
11, 1747, several months prior. Shortly after Franklin, from his
principles of the _plus_ and _minus_ state, explained in a satisfactory
manner the phenomena of the Leyden phial, first observed by Mr. Cuneus,
or by Professor Muschenbroeck, of Leyden, which had much perplexed
philosophers. He showed clearly that when charged the bottle contained
no more electricity than before, but that as much was taken from one
side as thrown on the other; and that to discharge it nothing was
necessary but to produce a communication between the two sides by which
the equilibrium might be restored, and that then no signs of electricity
would remain. He afterwards demonstrated by experiments that the
electricity did not reside in the coating as had been supposed, but in
the pores of the glass itself. After the phial was charged he removed
the coating, and found that upon applying a new coating the shock might
still be received. In the year 1749, he first suggested his idea of
explaining the phenomena of thunder gusts and of _aurora borealis_ upon
electric principles. He points out many particulars in which lightning
and electricity agree; and he adduces many facts, and reasonings from
facts, in support of his positions.

"In the same year he conceived the astonishingly bold and grand idea of
ascertaining the truth of his doctrine by actually drawing down the
lightning, by means of sharp pointed iron rods raised into the regions
of the clouds. Even in this uncertain state his passion to be useful to
mankind displayed itself in a powerful manner. Admitting the identity of
electricity and lightning, and knowing the power of points in repelling
bodies charged with electricity, and in conducting fires silently and
imperceptibly, he suggested the idea of securing houses, ships and the
like from being damaged by lightning, by erecting pointed rods that
should rise some feet above the most elevated part, and descend some
feet into the ground or water. The effect of these he concluded wou