Hewitt-Sperry Automatic Airplane for eight years, and yet Sperry became intrigued with the concept of applying radio control to them. He realized that for radio control to be effective, automatic stabilization would be essential, so he decided to adapt his naval gyro-stabilizers (which he had developed for destroyers). In 1913, the Navy provided a flying boat to test and evaluate the gyro-based autopilot. Sperry's son Lawrence served as an engineer during the test phase. In 1914, Lawrence Sperry was in Europe and observed the developing techniques of aerial warfare, including the use of aircraft. In 1916, the two Sperrys joined Peter Hewitt, an
Invention of the telephone David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, and most historians credit him with its invention. Thomas Alva Edison took the next step in improving the telephone with his invention in 1878 of the carbon grain "transmitter" (microphone) that provided a strong voice signal on the transmitting circuit that made long-distance calls practical. Edison discovered that carbon grains, squeezed between two metal plates, had a variable electrical resistance that was related