Hewitt-Sperry Automatic Airplane and Lawrence Sperry decided that he would be the test pilot. While taxiing it on ice, he hit some slushy snow, and wrecked the plane, though Sperry was unhurt. A second airplane was fitted out, and Sperry managed to get it in the air, but lost control when the automatic pilot was engaged. After two complete rolls, Sperry managed to regain control and land safely. Clearly, though, more attention to flight testing the basic design was needed, particularly in the area of handling qualities. Sperry and his assistant, N. W. Dalton, obtained a Marmon automobile, and mounted the Curtiss-Sperry Flying
Invention of the telephone receiver. Gray did not convert his caveat into a patent application until after the caveat had expired and hence left the field open to Bell. When Gray applied for a patent for the variable resistance telephone transmitter, the Patent Office determined "while Gray was undoubtedly the first to conceive of and disclose the (variable resistance) invention, as in his caveat of 14 February 1876, his failure to take any action amounting to completion until others had demonstrated the utility of the invention deprives him of the right to have it considered." The carbon microphone was independently developed around 1878 by