In 1752 the famous scientist and statesman conducted an experiment to find out if lightning was electricity. During a thunderstorm in Philadelphia, Pennsylvania, Franklin and his son William flew a homemade kite with a wire attached to it. Franklin expected lightning to strike the wire, then flow down the kite string to a key tied near the end.

The kite entered a rain cloud. Franklin touched his knuckle to the key. Zap! An electric spark! The experiment had worked. The lightning behaved like electricity. Franklin had been lucky. If the lightning strike had been stronger, he could have been hurt or killed. After this and other experiments, Franklin invented lightning rods to protect buildings from lightning strikes.