On August 22, 1834 America astronomer Samuel Pierpont Langley is born in Boston Massachusetts (d. February 27, 1906).  His invention of the bolometer helped him measure infrared radiation, which helped Svante Arrhenius make the first calculations on the greenhouse effect.

Langley’s interest in astronomy began early in his youth with a small telescope owned by his father. By age 20 he and his brother were building their own.  As a young adult he taught at Harvard College Observatory the United States Naval Academy, until 1867, when he moved to Pittsburgh, Pennsylvania to direct the new Allegheny Observatory and serve as professor of astronomy at the University of Pittsburgh. 

In Pittsburgh he researched the Sun and the effect of its solar radiation on the Earth’s atmosphere.  To conduct his research, Langley invented the bolometer to measure infrared radiation, versions of his original design are still used today.

The bolometer is a radiant-heat detector that is sensitive to differences in temperature of one hundred-thousandth of a degree Celsius (0.00001 C) . Composed of two thin strips of metal, a Wheatstone bridge, a battery, and a galvanometer (an electrical current measuring device), this instrument enabled him to study solar irradiance (light rays from the sun) far into its infrared region and to measure the intensity of solar radiation at various wavelengths.  Langley’s measurement of interference of the infrared radiation by carbon dioxide in Earth's atmosphere was used by Svante Arrhenius in 1896 to make the first calculation of how climate would change from a future doubling of carbon dioxide levels.

In 1886, Langley received the Henry Draper Medal from the National Academy of Sciences for his contributions to solar physics. His publication in 1890 of infrared observations at the Allegheny Observatory in Pittsburgh together with Frank Washington Very was used by Svante Arrhenius to make the first calculations on the greenhouse effect.

By 1887, Langley became Secretary of the Smithsonian Institution Secretary of the Institution, where he would serve until his death in 1906, from paralytic stroke.  Pall beareres at Langley’s funeral included the Chief Justice of the United States Supreme Court Melville Fuller and Vice President Charles W Fairbanks.

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