Abbildungen der Seite
PDF
EPUB

ly, and thus rendered it a better Vehicle for adver, iisements, &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 earh/ appointed watchmen, whose duty it was to guard the citizens against the midnight robber, arid 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 sufficiently strict. Franklin saw the dangers arising from this cause, and suggested an alteration, *o 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 tcitks than fires. Other causes operate slowly, arid almost imperceptibly; but these in a moment rentier abortive the labors of ages. On this account there should be, in all cities, ample provisions t3 prevent fires from spreading. Franklin early saW the necessity of these 5 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 the city and liberties. To these may be attributed in a great degree the activitv in extinguishing fires, for which the citizens of Philadelphia are distinguished, anu\ the inconsiderable damage Which this city has sns*" taiued from this eause—Some tiajv aftt)> E»»*i#ft

suggested the plan of an association for "risunn.g 'Jiouses from losses hy 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 land from taxes ; to which the assemble. 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 inconvenience. 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 nect ssarv that the citizens should arm for their defence. Governor Thomas recommended to the assemblv, who were then sitting, to pass a militia law. To this thiy i would agree only on condition that he should give .his assent to certain laws, which appeared to the'n calculated to promote the interest of the people. As i he thought these laws -would be injurious to the proprietaries, he refused his assent to them; and the assemblv 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 enemv, and destitute of everv means of defence.— At this crisis Franklin stepped forth, and proposed fc> a meeting of the citizens of Philadelphia, a plan 'ef a voluntary association for the defence of the pro. vince. 1'his was approved of, and signed by twelve hundred persons immediately. Copies of it were circulate d throughout the province; and in a short time the number of signers amounted to ttn thousand. 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, e'ec ricity has been. the least explored.

The elective 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 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 bv it. In 1709, Hawkesbec communicated some important observations and experiments to the world. For several years electricity was entirely neglected^ until Mr. Gray applied himself to i:. in 17^8, with great assiduity. He, and his friend Mr. Wheeler, made a great variety of experiments; ;in which they demonstrated that electricitv may be . communicated from one body to another, even without being in contact, and in this wav may be conducted to a great distance. Mr. Grav after* wmds found, that by suspending rods of iron by

silk or hair lines, and bringing an excited tube tin* tier them, sparks might be drawn, and a light perreived 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 cf 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 number of experiments, but added little of importance. He first used the terras conductors and electrics, pe<r se. In 1742, several ingenious Germans engaged in this subject. Of these the principal were, professor 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 pro•dnce phenomena which had been hitherto unobserved. They killed small birds, and set spirits on fire. Their experiments excited the curiosity of ©ther philosophers. Collinson, about the year 1745, »ent to the library company of Philadelphia an account of these experiments, together with a tube, and directions how to use it. Franklin, with some ©f his friends, immediately engaged in a course of experiments; the result of which is well known. Jle 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 faif to endure for ages, iiis observations he commudicateii, in a aerie.* «£ 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 monihs 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 JLeyden, 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 sidt.s, 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 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

« ZurückWeiter »