In exactly the same way Franklin achieved his greatest success, which at one bound placed him in the front rank of the scientific men of his century. On a visit to Boston he witnessed some experiments in electricity made by Dr. Spence, a scientific lecturer from England. They excited his curiosity. The recent invention of the Leyden jar had much advanced the knowledge of the subject and made it a matter of fashionable interest and entertainment. But to Franklin it was entirely new. On his return to Philadelphia he received an electrical tube with directions for using it. This was in 1746. Franklin repeated the experiments he had seen at Boston, became fascinated with the study, interested some friends in it, and then went on making experiments of his own, which nobody had ever witnessed before.
Soon he outstripped all the scientific lights of his time by the brilliancy of his achievements on a field on which the best minds of the period were competing. His was the theory of plus and minus, or positive and negative electricity; and then it struck him that lightning and electricity must be essentially the same thing. The way in which he formed his conclusion was exceedingly simple again. He observed that the electrical fluid strikingly agreed with lightning in several essential particulars. This he knew from seeing and experimenting. From this he concluded that they were probably the same thing. “But,” said he, “the electric fluid is attracted by points. We do not know whether this property is in lightning. But since they agree in all the particulars wherein we can already compare them, is it not likely they agree likewise in this? Let the experiment be made.” And he made it, again in a very simple way. He caught the lightning in a snare as it were, and then interrogated it.
Everybody has heard the story of the kite, and seen the picture. He stretched a large silk handkerchief on two
