Page:Works of the Late Doctor Benjamin Franklin (1793).djvu/112

102 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 hitherto 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 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 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 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,