Experiment to measure speed of electricity. 19th-century illustration of the Royal Society experiment carried out in 1747 to ascertain whether electric current could be carried from one side of the River Thames to the other. An electrostatic generator was used to charge a Leyden jar connected to a wire which was suspended above the Thames at Westminster Bridge. On each side of the river a participant held the wire in one hand whilst an iron rod was dipped into the river with the other. When the circuit was completed the Leyden jar discharged its current. The shock was felt by the participants on both sides of the river. Those taking part included Martin Folkes (President of the Royal Society), Lord Charles Cavendish, John Bevis and William Watson. The experiment was one of a series carried out at this location. Later experiments were conducted over longer distances at other locations. The results were published in the Royal Society's Philosophical Transactions. Artwork published in 1867.