1. He anticipated Faraday in the discovery that the electricity in a charged Leyden jar resides on the glass and not on the metal coatings. He, however, made no generalizations from this discovery.
2. He advanced the fluid theory of electricity, recognizing clearly the dual nature of the varieties commonly called positive and negative from the mathematical symbols used to express them.
3. He established the identity of lightning and electricity.
To understand the importance of this last discovery we must remember with what terror the world had hitherto regarded this bewildering apparition of the sky. It was not so much the dread of feeling above one an irresponsible power subject to a law that knows no sympathy with human life, as the more debasing fear of superstition, that sees in the red thunderbolt a deadly instrument of vengeance hurled by the hand of an angry deity, and that loosens the inmost sinews of a man's moral courage. With the knowledge that lightning is only a magnified electrical spark, fell one of the last strongholds of false religion. And there is something eminently fit in the fact that this lurking mystery of the heavens was finally exploded by Dr. Franklin, the exponent of common sense.
I am told by a specialist that the neatness and thoroughness of the reasoning by which Franklin established his theory before proceeding to experimentation are most laudable, and I am sure his letters of explanation have a literary charm not often found in scientific writing. The paper in which Franklin developed his theory and showed how it might be tested by drawing lightning from the clouds by means of a pointed wire set up on a steeple, was sent to his friend in England, and there printed; and at the suggestion of the great Buffon the same paper was translated into French. The pamphlet created a sensation in France, and the proposed experiment was actually performed in the presence of the king. Before the report, however, of the successful experiment reached Franklin he had himself verified his theory, using a kite to attain an altitude, as there was no spire or high building in Philadelphia. Taking his son with him, he went to an old cow house in the country, before a storm, and there, to catch the electric fluid, sent up his kite made of an old silk handkerchief. A wire extended from the upright stick of the kite, and this was connected with the cord, which when wet acted as a good conductor. The part of the cord held in his hand was of silk, and between this and the wet hempen cord a key was inserted and connected with a Leyden jar. How successful the experiment proved to be, all the world knows. Somehow all the important events of Franklin's life are dramatic and picturesque, and this scene, especially, of the philosopher in the storm drawing down the very thunderbolts of heaven has always had a fascination for the popular mind. The detailed story of the experiment became public only through Franklin's conversation with his friends. When he learned that his theory had been previously verified in France, his modesty was so great that in writing he simply told how the experiment might be performed with a kite, never that he himself had actually accomplished it. In consequence of this discovery he was at once elected a member of the Royal Society of London, Yale and Harvard gave him the honorary degree of master of arts, and everywhere he was celebrated as the foremost philosopher of the day.
When the time comes we shall see that Franklin's scientific fame was a real aid to him in his diplomatic career; now we must turn our eyes backward and trace from the beginning his slow rise in political and civic power. And it is a peculiar feature of the day and of Franklin's individual character that many of his reforms took their start in the gayety of social intercourse. There was nothing morose, nothing stern, in our genial philosopher. Though always temperate, his vivacity and easy politeness made him welcome in any merry company of the day. He could sing with the best of the young blades and even compose his own ditties; and one of these songs, "The Old Man's Wish," he tells us he sang at least a thousand times. The chorus of the song is characteristic enough to be quoted:—
"May I govern my passions with absolute sway,
Grow wiser and better as my strength wears away,
Without gout or stone, by gentle decay;"
and another ballad in praise of his wife still has a kind of popularity:—