Abbildungen der Seite
PDF
EPUB

U*ve been sold in one year; which must be consi toivti as a very large number, especially when we reflect, that this country was, at that tune, but vhinly peopled. It cannot be doubted that the salutary maxims contained in these almanacs must have made a favourable impression upon many of the readers of them.

It was not long before Franklin entered upon his political career. In the year 1736, he was appointed clerk to the general assembly of Pennsylvania; and was re-elected by succeeding assemblies for several years, until he was chosen a representative for the city of Philadelphia.

Bradford was possessed of some advantages over Franklin, by bemg postmaster, thereby having an opportunity of circulating his paper more extensively, and thus rendering 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 ci :ulation 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 immediate 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 sufncicntly 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.

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 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 com* pany m this city. This example was soon followed by others; and there are now numerous fire companies in the city and liberties. To thesemay 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 sustained from this cause. Sometime after, Franklin suggested the plan of an association for inauriug houses from losses by fire, which was adopted; and the association continues to this day. The advantages experienced from it have been great.

From the first establishment of Pennsylvania, a spirit 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 lands from taxes; to which the Assembly would by no means consent. This subject of dispute interfered in almost every question, and prevented the most salutarylaws from being enacted. This at times subjected the people to great inconveniences. In the year I744, durmg 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 necessury 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 upon condition that he should give his assent to certain laws, which appeared tc Ihem calculated to promote the interests of the peo ole. 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 inroad of an erie. my, 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 were instantly circulated throughout the provmce; and, in a short time the number of signers amounted to ten thousand. Franklin was chosen colonel of the Philadelphia regiment; but he did not think proper to accept of the honour.

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 ardour 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 Theoplsrastus 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 air-pump, 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 I709, Hawkesbeu communicated some important observations and experiments to the world. For several years electricity was entirely neglected, until Mr. Grey applied himself to it, m 1728, with great assiduity. He and his friend Mr. Wheeler, made a great variety of experiments; :n which they demonstrated, that electricity may be communicated from (Hie Uxi) to another, even without being in contact, and in thu way^nay be conducted to a great distance. Mr. Grei ftenvards found, that, by suspending rods of iron oi eilk or hairlines, and bringing an excited tube under them, sparks might be drawn, and a light perceived at the extremities in the dark. M. Du F'aie, inten riant of the French king's gardens, made a numbci of experiments, which iddednot a little to the science. He made the discovery of two kinds of electricity, which he called vitreous and resinous; the former produced bv rubbing glass, the latter from excited sulphur, sealing-wax, &c. But this idea he afterwards gave up as erroneous. Between the years 1739 and I742, DesauguViers made a number of expert' uenls, but added little of importance. He first used the terms conductors and electrics per se. In 1742, several ingenious Germans engaged in this subject; nf these the principal were, pro&ssor Boze, of Witlemberg, 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 the electric fluid, and thus to produce phenomena which had been hitherto unobserved. They killed small birds, and set spirits on fire. Their experiments excited the curiosity of other philosophers. Colliuson, about tha year 1745, sent to the Library Company of Fhiladelphia, an account of these experiments, together with a tube, and directions how to use it. Franklin, voth some ofhis 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 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 foi their countryman. Dr. Watson. Watson's paper is dated January 2I,I748; Franklin's, July II, I747; 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 tha Lottie, when charged, contained no more electricity than before, but that as much was taken from one tide u wan thrown on the other; and that, to discharge it, nothing was necessary but to produce a communication between thetwo sides by which the equilibrium might be restored, and that then no signt o? electricity would remain. He afterwards demonstrated, by experiments, that the electricity did not reside in tli* 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 I7-19, he first suggested his idea of explaining the phenomena of thundergusls, and of the auroraborcalis, upon electrical 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 region of the clouds. Even in this uncertain state, his passion to be useful to mankind displays 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 their fire silently and imperceptibly, he suggested the idea of securing houses, ships, &c. 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 the water. The effect of these, he concluded, would be either to prevent a stroke by repelling the cloud beyond the striking distance, or by drawing off the electrical fire which it contained; or, if they could not effect this, they would et leasj conduct the electric matter to the earth, without any injury to the building.

[ocr errors]

It was not until the summer of 1752, that he was enabled to complete his grand and unparalleled discovery by experiment. The plan which he had originally propose*1, was to erect on some high tower, or other elevated place, a sentrvbox, from which should rise a pointed iron rod, insulated by being fixed in a cake of resin. Electrified clouds passing over this.

« ZurückWeiter »