English: Caricature of a treatment better known as Perkins Tractors, named after its inventor, Elisha Perkins (1741-1799), an American physician. Two tapered rods made of different metals – normally brass and silver – were passed over the body and, it was claimed, drew out disease using electricity. The tractors were said to be charged from the natural electricity present in the user’s body. Perkins patented his invention in 1796. Despite claims that Perkin’s invention cured over five thousand people in England of various complaints, the treatment was widely discredited and was labelled by many as ‘quackery’.