Sir John Ambrose Fleming FRS (29 November 1849 – 18 April 1945) was a British electrical engineer and physicist. He is known for inventing the first thermionic valve or vacuum tube. 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.