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| 1904 |
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| John Ambrose Fleming (1849–1945) devised the diode thermionic valve (radio tube); Lee de Forest (1873–1961) invented the Audion (1906), a three-electrode vacuum tube (triode amplifier), thereby providing the basis for the development of electronics. | 1 |
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| 1909–27 |
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| The “heroic age” of aviation commenced with Louis Blériot's (1872–1936) flight (1909) across the English Channel; included the exploits of the aerial aces of World War I, the flight (1919) of John W. Alcock (1892–1919) and Arthur Whitten Brown (1886–1948) across the Atlantic (Newfoundland to Galway), Richard E. Byrd's (1888–1957) flight (1926) across the North Pole; and culminated in Charles A. Lindbergh's (1902–74) solo nonstop flight from New York to Paris in The Spirit of St. Louis (1927). Many technical improvements were made, including the first engine specifically intended for aircraft by Glenn Curtiss (1904) and the gyroscope stabilizer of Elmer A. Sperry (1913). | 2 |
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| 1911 |
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| Charles F. Kettering (1876–1958), who had previously invented lighting and ignition systems for the automobile, perfected the electric self-starter. The first fully automatic transmission, perfected by Earl A. Thompson, was introduced commercially in 1939. Harry Vickers and Francis W. Davis began work on hydraulic power-assisted steering systems in 1925 and 1926 respectively, and in 1951 power steering was introduced for passenger cars. | 3 |
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| 1913 |
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| Diesel-electric railway engines first used in Sweden. Coming into use in the United States during the late 1930s, they largely replaced steam locomotives. (See Technological Developments) | 4 |
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