Langley, Samuel

Langley, Samuel (Pierpont)

(born Aug. 22, 1834, Roxbury, Mass., U.S.—died Feb. 27, 1906, Aiken, S.C.) U.S. astronomer and aeronautics pioneer. He taught for many years at the future University of Pittsburgh. He studied the effect of solar activity on weather and invented the bolometer (1878), a radiant-heat detector sensitive to extremely small temperature differences. He began conducting experiments on lift and drag of wings by building flying machines, and in 1896 one of his heavier-than-air machines became the first to achieve sustained unmanned flight, flying 3,000 ft (900 m) along the Potomac River.

---

Langley, Samuel (Pierpoint) (1834–1906) inventor, aeronautical pioneer; born in Roxbury, Mass. Although he had no formal higher education, he served for twenty years as director of the Allegheny Observatory (1867–87). While director, he created a system of regulating railroad time that became standard. In 1878 he invented a bolometer, an electrical thermometer, which he used to conduct experiments on solar and lunar radiation. From 1887 to 1906 he served as secretary of the Smithsonian Institution. He built several models of heavier-than-air mechanically propelled flying machines, and in 1896 he achieved the first free flights. His subsequent attempt to build and fly a man-carrying machine failed.