Was Franklin's famous kite really struck by lightning?

Almost certainly not. The famous picture of a kite being hit by a bolt, with Benjamin Franklin gripping the string, is a myth. The best account says the kite was never struck, and if it had been, Franklin would probably have been seriously hurt or killed. What he actually did was quieter, and cleverer.

In June 1752, according to the best account, Franklin flew a kite in a thunderstorm with the help of his son William, to test whether lightning is electricity. The string was hemp, with a metal house key tied at the other end. A silk cord tied to the key kept the Franklins from touching the wet string, and they waited in an open shed to keep the silk dry.

No bolt came down. Instead, the storm cloud overhead induced an electrical charge on the kite and its string. Franklin saw loose threads on the string stand apart, repelling one another, which showed the string was charged. When he brought his hand near the key, a spark jumped to it, and he could move some of the charge into a Leyden jar, an early kind of capacitor.

That, combined with further experiments on the ground, showed that lightning and electricity are the same phenomenon. The kite was a small, careful experiment, and it was not even the first of its kind: a month earlier, Thomas-François Dalibard had carried out a rod version in northern France.