Autopilot reducing the pilot's workload. Lawrence Sperry (the son of famous inventor Elmer Sperry) demonstrated it in 1914 at an aviation safety contest held in Paris. At the contest, Sperry demonstrated the credibility of the invention by flying the aircraft with his hands away from the controls and visible to onlookers of the contest. Elmer Sperry Jr., the son of Lawrence Sperry, and Capt Shiras continued work after the war on the same autopilot, and in 1930 they tested a more compact and reliable autopilot which kept a US Army Air Corps aircraft on a true heading and altitude for three
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