Samuel Langley (22.08.1834-27.02.1906) was an American astrophysicist and physicist and a member of the National Academy of Sciences. He was born in Roxbury. He graduated from the Boston High School. In 1867 — 87 he was director of the observatory in Allegheny and from 1887 secretary of the Smithsonian Institution in Washington.
His research concerned the physics of the Sun, spectroscopy and the study of thermal radiation. In 1881 he built the bolometer. He was one of the first to carry out experimental studies of the distribution of energy in the spectrum of the thermal radiation of a black body at various temperatures, and he obtained the first curves describing this distribution (1884). He measured the intensity of the radiation of the Sun and determined the solar constant. He drew up (1901) an atlas of the lines of the infrared part of the solar spectrum.
A Fellow of the Royal Society and of the Royal Society of Edinburgh. The B. Rumford and H. Draper medals and others.