Barlow's wheel, March 1822. Original sketch
© Royal Institution / Science & Society Picture Library
Barlow's wheel, March 1822. Original sketch accompanying a letter from the English mathematician and physicist Peter Barlow (1776- 1862) to Michael Faraday (1791-1867). This device, considered to be one of the first models of an electric motor supplied by continuous current, was projected and built by Barlow in 1822.