Inventors

by Philip Gengembre Hubert

In 1748 Franklin, being then forty-two years old, and in the enjoyment of an ample income from his business as printer and publisher, sold out to his foreman, David Hall, and was free to devote himself wholly to his beloved experiments. He had built himself a home in a retired spot on the outskirts of Philadelphia, and with an income which in our days would be equivalent to $15,000 or $20,000 a year, he was considered a fairly rich man. Having thus settled his business affairs in a manner which proved that he knew perfectly well what money was worth, he took up his electrical studies again and extended them from the machine to the part played in nature by electricity. The patience with which he observed the electrical phenomena of the heavens, the acuteness displayed by him in drawing plausible inferences from his observations, and the rapidity with which he arrived at all that we now know of thunder and lightning, still excite the astonishment of all who read the narratives he has left us of his proceedings. During the whole winter of 1748-49 and the summer following, he was feeling his way to his final conclusions on the subject. Early in 1749 he drew up a series of fifty-six observations, entitled "Observations and Suppositions towards forming a new Hypothesis for explaining the several Phenomena of Thundergusts." Nearly all that he afterward demonstrated on this subject is anticipated in this truly remarkable paper, which was soon followed by the most famous of all his electrical writings, that entitled "Opinions and Conjectures concerning the Properties and Effects of the Electrical Matter, and the Means of preserving Buildings, Ships, etc., from Lightning; arising from Experiments and Observations made at Philadelphia, 1749."

Franklin sets forth in this masterly paper the similarity of electricity and lightning, and the property of points to draw off electricity. It is this treatise which contains the two suggestions that gave to the name of Franklin its first celebrity. Both suggestions are contained in one brief passage, which follows the description of a splendid experiment, in which a miniature lightning-rod had conducted harmlessly away the electricity of an artificial thunder-storm.

"If these things are so," continues the philosopher, after stating the results of his experiment, "may not the knowledge of this power of points be of use to mankind in preserving houses, churches, ships, etc., from the stroke of lightning, by directing us to fix on the highest part of those edifices upright rods of iron, made sharp as a needle and gilt to prevent rusting, and from the foot of those rods, a wire down the outside of the building into the ground, or down round one of the shrouds of a ship, and down her side till it reaches the water? Would not these pointed rods probably draw the electrical fire silently out of a cloud before it came nigh enough to strike, and thereby secure us from that most sudden and terrible mischief?"

The second of these immortal suggestions was one that immediately arrested the attention of European electricians when the paper was published. It was in these words:

"To determine the question, whether the clouds that contain lightning are electrified or not, I would propose an experiment to be tried where it may be done conveniently. On the top of some high tower or steeple, place a kind of sentry-box, big enough to contain a man and an electric stand. From the middle of the stand let an iron rod rise and pass, bending out of the door, and then upright twenty or thirty feet, pointed very sharp at the end. If the electrical stand be kept clean and dry, a man standing on it, when such clouds are passing low, might be electrified and afford sparks, the rod drawing fire to him from a cloud. If any danger to the man should be apprehended (though I think there would be none), let him stand on the floor of his box, and now and then bring near to the rod the loop of a wire that has one end fastened to the leads, he holding it by a wax handle; so the sparks, if the rod is electrified, will strike from the rod to the wire and not affect him."

A friend once asked Franklin how he came to hit upon such an idea. His reply was to quote an extract from the minutes he kept of the experiments he made. This extract, dated November 7, 1749, was as follows: "Electrical fluid agrees with lightning in these particulars: 1. Giving light. 2. Color of the light. 3. Crooked direction. 4. Swift motion. 5. Being conducted by metals. 6. Crack or noise in exploding. 7. Subsisting in water or ice. 8. Rending bodies it passes through. 9. Destroying animals. 10. Melting metals. 11. Firing inflammable substances. 12. Sulphurous smell. 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 probable they agree likewise in this? Let the experiment be made."

In this discovery, therefore, there was nothing of chance; it was a legitimate deduction from patiently accumulated facts.

It was not until the spring of 1752 that Franklin thought of making his suggested experiment with a kite. The country around Philadelphia presents no high hills, and he was not aware till later that the roof of any dwelling-house would have answered as well as the peak of Teneriffe. There were no steeples in Philadelphia at that day. The vestry of Christ Church talked about erecting a steeple, but it was not begun until 1753. On the 15th of June, 1752, Franklin decided to fly that immortal kite. Wishing to avoid the ridicule of a failure, he took no one with him except his son, who, by the way, was not the small boy shown in countless pictures of the incident, but a stalwart young man of twenty-two. The kite had been made of a large silk handkerchief, and fitted out with a piece of sharpened iron wire. Part of the string was of hemp, and the part to be held in the hand was of silk. At the end of the hempen string was tied a key, and in a convenient shed was a Leyden jar in which to collect some of the electricity from the clouds. When the first thunder-laden clouds reached the kite, there were no signs of electricity from Franklin's key, but just as he had begun to doubt the success of the experiment, he saw the fibres of the hempen string begin to rise. Approaching his hand to the key, he got an electric spark, and was then able to charge the Leyden jar and get a stronger shock. Then the happy philosopher drew in his wet kite and went home to write his modest account of one of the most notable experiments made by man.

Franklin's fame as the first to suggest the identity of lightning and electricity would have been safe, however, even without the famous kite-flying achievement. A month before that June thunderstorm his suggestions had been put into practice in Europe with complete success. Mr. Peter Collinson, to whom Franklin addressed from time to time long letters about his experiments and conjectures, had caused them to be read at the meetings of the Royal Society, of which he (Collinson) was a member. That learned body, however, did not deem them worthy of publication among its transactions, and a letter of Franklin's containing the substance of his conjectures respecting lightning was laughed at. The only news that reached Philadelphia concerning these letters was that Watson and other English experimenters did not agree with Franklin. It was only in May, 1751, that a pamphlet was finally published in London, entitled "New Experiments and Observations in Electricity, made at Philadelphia, in America." A copy having been presented to the Royal Society, Watson was requested to make an abstract of its contents, which he did, giving generous praise to the author.

Before the year came to a close Franklin was famous. There was something in the drawing down, for mere experiment, of the dread electricity of heaven that appealed not less powerfully to the imagination of the ignorant than to the understanding of the learned. And the marvel was the greater that the bold idea should have come from so remote a place as Philadelphia. By a unanimous vote the Royal Society elected Franklin a member, and the next year bestowed upon him the Copley medal. Yale College and then Harvard bestowed upon him the honorary degree of Master of Arts.