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ly, and thus rendered it a better vehicle for advertisements, &c. Franklin, in his turn, enjoyed these advantages, by being appointed post-master of Philadelphia in 1737. Bradford, while in office, had acted ungenerously towards Franklin, preventing as much as possible the circulation of his paper. He had now an opportunity of retaliating; but his nobleness of soul prevented him from making use of it.

The police of Philadelphia had early appointed watchmen, whose duty it was to guard the citizens against the midnight robber, and to give an imme diate alarm in case of fire. This duty is, perhaps, one of the most important that can be committed to any set of men. The regulations, however, were not sufficiently strict. Franklin saw the dangers arising from this cause, and suggested an alteration, so as to oblige the guardians of the night to be more watchful over the lives and property of the citizens. The propriety of this was immediately perceived, and a reform was effected.

This

There is nothing more dangerous to growing cities than fires. Other causes operate slowly, and almost imperceptibly; but these in a moment render abortive the labors of ages. On this account there should be, in all cities, ample provisions to prevent fires from spreading. Franklin early saw the necessity of these; and about the year 1738, formed the first fire company in this city. example was soon followed by others; and there are now numerous fire companies in the city and fiberties. To these may be attributed in a great degree the activity in extinguishing fires, for which the citizens of Philadelphia are distinguished, and the inconsiderable damage which this city has spsTained from this cause.Some time after, Franklin

silk or hair lines, and bringing an excited tube un« der them, sparks might be drawn, and a light perceived at the extremities in the dark. M. Du Faye, intendant of the French king's gardens, made a number of experiments, which added not a little to the science. He made the discovery of two kinds of electricity, which he called vitrous and resinous; the former produced by rubbing glass, the latter from excited sulphur, sealing-wax, &c. But this idea he afterwards gave up as erroneous. Between the years 1739 and 1742, Desaguliers made a num. ber of experiments, but added little of importance. He first used the terms conductors and electrics, per se. In 1742, several ingenious Germans engaged in this subject. Of these the principal were, pro fessor Boze of Whittemberg, professor Winkler of Leipsic, Gordon, a Scotch Benedictine monk, professor of philosophy at Erfurt, and Dr. Ludolf of Berlin. The result of their researches astonished the philosophers of Europe. Their apparatus was large, and by means of it they were enabled to collect large quantities of electricity, and thus to prodoce phenomena which had been hitherto unob served. They killed small birds, and set spirits on fire. Their experiments excited the curiosity of other philosophers. Collinson, about the year 1745, sent to the library company of Philadelphia an account of these experiments, together with a tube, and directions how to use it. Franklin, with some of his friends, immediately engaged in a course of experiments; the result of which is well known. He was enabled to make a number of important discoveries, and to propose theories to account for various phenomena; which have been universally adopted, and which bid fair to endure for ages. His observations he communicated, in a series of

letters, to his friend Collinson; the first of which is dated March 28, 1747. In these he makes known the power of points in drawing and throwing off 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 honor 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 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 shewed clearly that the bottle, when charged, contained no more electricity than before, but that as much was taken from the one side as was thrown on the other; and that to discharge it, nothing was necessary but to make 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 experi ments, that the electricity did not reside in the coating, as had been supposed, but in the pores of the glass itself. After a 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 the aurora borealis, upon electrical principles.

He

points out many particulars in which lightning and electricity agree; and he adduces many facts, and reasoning from facts, in support of his positions. In the same year he conceived the astonishingly bold

gion of the clouds.
s passion to be useful to mankind displays itself
a powerful manner. Admitting the identity of
ectricity and lightning, and knowing the power
points in repelling bodies charged with electricity,
d in conducting their fire silently and impercepti
y, he suggests the idea of securing houses, ships,
c. from being damaged by lightning, by erecting
inted iron rods, which should rise some feet above
e most elevated part, and descend some feet into
e ground or the water. The effect of these, he
ncluded, would be either to prevent a stroke by
pelling the cloud beyond the striking distance, or
drawing off the electrical fire which it contained;
, if they could not effect this, they would at least
nduct the stroke to the earth, without any injury
the building.

Even in this uncertain state,

It was not until the summer of 1752, that he was abled to complete his grand and unparalleled discoery by experiment. The plan which he had origilly proposed, was, to erect on some high tower, other elevated place, a centry-box, from which ould rise a pointed iron rod, insulated by being ked in a cake of rosin. Electrified clouds passg over this, would, he conceived, impart to it a poron of their electricity, which would be rendered ident to the senses by sparks being emitted, hen a key, a knuckle, or other conductor, was resented to it. Philadelphia at this time afforded O opportunity of trying an experiment of this kind. Whilst Franklin was waiting for the erection of a ire, it occurred to him, that he might have more ady access to the region of clouds by means of a

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as usual, of hemp, except the lower end, which was silk, Where the hempen string was terminated a key was fastened. With this apparatus, on the appearance of a thunder-gust approaching, he wen out into the commons, accompanied by his son, to whom alone he communicated his intentions, well knowing the ridicule which, too generally for the interest of science, awaits unsuccessful experiments in philosophy. He placed himself under a shed to avoid the rain. His kite was raised. A thunder cloud passed over it. No sign of electricity appear ed. He almost despaired of success; when sud denly he observed the loose fibres of his string to move towards an erect position. He now presented his knuckle to the key, and received a strong spark. How exquisite must his sensations have been at this moment! On this experiment depended the fate of his theory. If he succeeded, his name would rank high amongst those who have improved science; if he failed, he must inevitably be subjected to the derision of mankind, or, what is worse, their pity, as a well meaning man, but a weak, silly projector. The anxiety with which he looked for the result of his experiment, may easily be conceived. Doubts and despair had begun to prevail, when the fact was ascertained in so clear a manner, that even the most incredulous could no longer withhold their assent. Repeated sparks were drawn from the key a vial was charged, a shock given, and all the ex periments made, which are usually performed with electricity.

About a month before this period, some ingeni ous Frenchmen had completed the discovery, in

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