Lightning experiment. Artwork showing the sentry box lightning experiment. This experiment was proposed by the US scientist Benjamin Franklin (1706-1790), to discover the nature of lightning. A metal rod attached to the sentry box is pointed towards storm clouds in the hope of attracting charge and showing that lightning is the same phenomenon as electricity. This experiment was first carried out by French scientist Thomas-Francois Dalibard (1709-1799) on 10 May 1752, at Marly, France, a few weeks before Franklin conducted his famous kite experiment in June 1752. However, it is Franklin who is usually credited with the discovery of the nature of lightning. Illustration from 'Electric science : its history, phenomena, and applications' (1853) by Frederick C. Bakewell.