The radiation of the planet Earth to space.

Washington:: Smithsonian Institution, 1929., 1929. At head of title: Smithsonian Miscellaneous Collections, Vol. 82, No. 3, November 16, 1929. Hodgkins Fund. 242 x 162 mm. 8vo. [ii], 12 pp. 7 tables, 2 large folding plates (i.e.: printed on both sides). Printed wrappers. Fine. In 1907 Charles Abbot determined the solar constant (the quantity of ray energy crossing one square centimeter of surface set perpendicular to the solar rays outside the earth's atmosphere or one astronomical unit from the sun). Freeman was with the Langley Memorial Aeronautical Laboratory.