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There is nothing more dangerous to growing cities than fires. Other causes operate slowly, and almost imperceptibly ; but these in a moinent render abortive the labours 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. This example was soon followed by others, and there are now numerous fire companies in this city and liberties. To these may be attributed in a great degree the activity of extinguishing fires, for which the citizens of Philadelphia are distinguished, and the inconsiderable damage which this city has sustained from this cause. Some time after, Franklin suggested the plan of an association for insuring houses from losses by fire, which was adopted ; and the association continues to this day. The advantages expe. rienced from it have been great.

From the first establishment of Pennsylvania a spi. rit of dispute appears to have prevailed amongst its inhabitants. During the life time of William Penn, the constitution had been three times altered. After this period, the History of Pennsylvania is little else than a recital of the quarrels between the proprietaries, or their governors, and the assembly. The proprietaries contended for the right of exempting their land froni taxes ; to which the assembly would by no means consent. This subject of dispute interfered in almost every question, and prevented the most salutary laws from being enacted. This at times subjected the people to great inconveniences. In the year 1744, during a war between France and Great Britain, some French and Indians had made inroads upon the frontier inhabitants of the province, who were unprovided for such an attack. It became necessary that the citizens should arm for their defence. Governor Thomas recommended to the assembly, who were then sitting, to pass a militia law. To this they would agree only aipon condition that he should give his assent to certain laws, which appeared to them calculated to promote the interest of the people. As he thought these laws would be injurious to the proprietaries, he refused his assent to them; and the assembly broke up without passing a militia law. The situation of the province was at this time truly alarming : exposed to the continual inroads of an enemy, and destitute of every means of defence. At this crisis Franklin stepped forth, and proposed to a meeting of the citizens of Philadelphia, a plan of a voluntary association for the defence of the province. This was approved of, and signed by twelve hundred persons immediately. .

Copies of it were circulated throughout the province, and in a short time the number of signers amounted to ten tliousand. Franklin was chosen colonel of the Philadelphia regiment, but he did not think proper to accept of the honor.

Pursuits of a different nature now occupied the greatest part of his attention for some years. He engaged in a course of electrical experiments, with all the ardor and thirst for discovery which characterized the philosophers of that day. Of all the branches of experimental philosophy, electricity had been least explored. The attractive power of amber is mentioned by Theophrastus and Pliny, and, from them, by later naturalists. In the year 1600, Gilbert, an English physician, enlarged considerably the catalogue of substances which have the property of attracting light. bodies. Boyle, Otto Guericke, a burgomaster of Magdeburg, celebrated as the inventor of the airpump, Dr. Wall, and Sir Isaac Newton added some facts. Guericke first observed the repulsive power of electricity, and the light and noise produced by it. In 1709, Hawkesbec communicated some important observations and experiments to the world. For seyeral years electricity was entirely neglected, untii Mr. Gray applied himself to it, in 1728, with great assiduity. He, and his friend Mr. Wheeler, made a great Variety of experiments; in which they demonstrated, that electricity may be communicated from one body to another, even without being in contact, and in this way may be conducted to a great distance. Mr. Gray afterwards found, that, by suspending rods of iron by silk or hair lines, and bringing an excited tube under *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 vitreous and resinous ; the former produced by rubbing glass, the latter from excited sul. phur, sealing-wax, &c. But this idea he afterwards gave up as erroneous. Between the years 1739 and 1742, Defaguliers made a number of experiments, but added little of importance. He first used the terms conductors and electrics, per 82. In 1742, several ingenious Germans engaged in the subject. Of these the principal were, professor Boze of Wittem. bergh, 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 produce phenomena which had been hithorto unobserved. 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 ex periments ; 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 23, 1747. In these he makes known the power of points in drawing and throwing off the electrical matter, which had hitherto escaped the notice of electri. cians. He also made the grand ciiscovery of a plus and minus, or of a positive and negative state of electricity. We gave 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 Muss chenbroeck of Leyden, which had much perplexed philosophers. He showed 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 experia 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 and grand idea of ascere. "taining the truth of his doctrine, by actually drawing down the forked lightning, by means of sharp pointed iron rods raised into the region of the clouds. Even in this uncertain state, his passion to be useful to man. kind displays itself in a powerful manner. Adinitting the identy of electricity and lightning, and knowing the power of points in rcpelling bodies charged with olectricity, and in conducting their fire silently and imperceptibly, he suggests the idea of securing licusesy ships, &c. froin being damaged by lightning, by erecer ing pointed iron rods, which should rise some fect above the most elevated part, and descend some fcet into the ground or the water. The effect of these, he concluded, would be either to prevent a stroke by rcm -pelling the cloud beyond the striking dictance, or tr drawing off the electrical fire which it contained; or, if they could not effect this, they would at least con> duct the stroke to the carth, without any injury to the building. · It was not until the summer of 1752, that he was enabled to complete his grand and unparalleled disé covery, by experiment. The plan which he had originally proposed, was, to erect on some high tower, or other elevated place, a centry box, from which should rise a pointed iron rod, insulated by being fixed in a cake of lesin. Electrifiecl clouds passing over this, would, he conceived, impart to it a portion of their electricity, which would be rendered evident to the senses by sparks being emitted, when a key, a knuckle, or other conductor, was presented to it. Philadelphia at this time afforded no opportunity of trying an ex. periment of this kind Whilst Franklin was waiting for the erection of a spire, it occurred to him, that he might have more ready access to the region of clouds by means of a common kite. He prepared one by ats taching two cross sticks to a silk handkerchief, which would not suffer so much from the rain as paper. To his upright stick was affixed an iron point. The string

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