Sir John Ambrose Fleming FRS (29 November 1849 – 18 April 1945) was an English electrical engineer and physicist. He is known for inventing the first thermionic valve or vacuum tube, the diode, later called the kenotron in 1904. He is also famous for the left hand rule (for electric motors). He was born the eldest of seven children of James Fleming DD (died 1879), a Congregational minister, and his wife, Mary Ann, at Lancaster, Lancashire and baptised on 11 February 1850.He was a devout Christian and preached on one occasion at St Martin-in-the-Fields in London on the topic of evidence for the resurrection. In 1932, along with Douglas Dewar and Bernard Acworth, he helped establish the Evolution Protest Movement. Having no children, he bequeathed much of his estate to Christian charities, especially those that helped the poor. He was an accomplished photographer and, in addition, he painted watercolours and enjoyed climbing in the Alps.