Fleming valve valve proved to be the start of a technological revolution. After reading Fleming's 1905 paper on his oscillation valve, American engineer Lee DeForest in 1906 created a three-element vacuum tube, the Audion, by adding a wire grid between cathode and anode. It was the first electronic amplifying device, allowing the creation of amplifiers and continuous wave oscillators. De Forest quickly refined his device into the triode, which became the basis of long-distance telephone and radio communications, radars, and early digital computers for 50 years, until the advent of the transistor in the 1960s. Fleming sued De Forest for infringing his
William Petrie (electrical engineer) William Petrie (electrical engineer) William Petrie (1821–1908) was an English electrical engineer, known for the development of the arc lamp. Born at King's Langley, Hertfordshire, on 21 January 1821, he was eldest of four sons of William Petrie (born 1784), a War Office official, and his wife Margaret Mitton, daughter of the banker Henry Mitton, of the Chase, Enfield. In 1829 his father was sent to the Cape of Good Hope, where he acted until 1837 as deputy commissary-general, with as neighbour Sir John Herschel, the astronomer, who was a significant influence on the younger William Petrie's interest in science.