One day he saw a boy flying a kite, and the thought instantly occurred to him that here was the straight road from the earth to the thunderclouds. Accordingly, he at once set to make a kite for his intended experiments; but fearing he would incur the ridicule of his sober fellow-citizens in engaging in what might seem to them a childish undertaking, he kept the whole matter a profound secret. The kite he made was not distinguished from those used by boys except of being made of silk instead of paper so as to be able to stand the wet. Franklin took an ordinary silk pocket-handkerchief, and fastened it over a cross made of two light strips of cedar, by simply tying the four corners of the handkerchief to the ends of the sticks. He next fastened a thin iron wire, a foot long, to the top of the kite, and having provided it with a loop and tail, attaching to the former a roll of twine, all was ready for the experiment. Watching the skies diligently, he saw a dark thundercloud coming up over Philadelphia late in the evening of July 4, 1752, and at once sallied forth from his house, situated at the corner of Race and Eight streets, into a neighbouring field. There was nobody with him but his eldest son, a lad of about twenty; and, in order to get protection against the heavy downpour, as well as to hide from the gaze of passers-by, the two sought shelter under an old cow-shed. Very likely, had they been seen here at the time, the philosopher and son might have been taken for two escaped lunatics, seeking so propitious an occasion as a thunderstorm to fly their darling kite. Perhaps Franklin too felt a little foolish, for he was about relinquishing his experiment after several flashes of lightning which had not in the least disturbed his kite, when a cloud darker than the previous one came rolling up. All on a sudden, Franklin felt a smart shock, and saw a spark flashing before his eyes. He had fastened the twine holding his kite to a silk ribbon which he held in his hand, joining twine and silk by a large key, attached to a Leyden jar. The latter at once became heavily charged, and as shock followed upon shock, and flash upon flash, there vanished all doubt from Franklin’s mind as to the absolute truth of the grand discovery he had made. It may be imagined with what inward satisfaction the great citizen of Philadelphia drew in his kite, and crept out from under the cow-shed, when the storm was over, and went home exultingly, the happiest of philosophers.