LANGLEY, Samuel Pierpont, Ameritan astronomer, physicist and pioneer designer of airplanes: b. Roxbury, Boston, 22 Aug. 1834; d. Aiken, S. C., 27 Feb. 1906. He was gradu ated from a high school, studied architecture and civil engineering and after a two years' trip abroad became an assistant in the Harvard Observatory in 1865, and later assistant pro fessor bf mathematics in the United States Naval Academy, and in 1867 was appointed director of Allegheny Observatory. In 1887 he became secretary of the Smithsonian Insti tution. He organized in 1::1 an expedition to Mount Whitney, Cal., where he was successful in re-establishing the color constant and in extending the invisible solar spectrum. He also devised the bolometer, or thermic balance, a contrivance for detecting minute differences of radiant heat and measuring accurately to less than one ten thousandth of a degree Fahrenheit. He established the Astrophysical Observatory and the National Zoological at Washington and in 1887 was president of the American Association for the Advancement of Science. His name became generally known
through his experiments in connection with the problem of mechanical flight. In 1896 a motor driven airplane designed by him accomplished. the first sustained flight. Further experiments were not so successful, but his design of ap paratus has been shown to be correct; in fact, in 1914, Glen Curtiss installed a more power ful engine in Langley's machine of 1903 and made a successful flight with it at Hammond sport, N. Y. Congress voted Langley $5,000 to carry out his ideas. Criticism and lack of support, led him to abandon his experiments, which, if persevered in, would have been suc cessfully eventually, as aeronautical engineers now recognize the correctness of Langley's reasoning and the value of his contributions in this field of science. Among his writings are New Astronomy' ; 'Experiments in Aero Dynamics,' and 'Internal Work of the Wind.'