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Abbot, Charles Greeley

Charles Greeley Abbot (May 31, 1872 ““ December 17, 1973) was an American astrophysicist and astronomer born in Wilton, New Hampshire. He graduated from Phillips Academy in 1891 and MIT in 1894, with a degree in chemical physics.

In 1895 Abbot was hired by Samuel Pierpont Langley as an assistant at the Smithsonian Astrophysical Observatory (SAO) despite his lack of experience in astronomy. Hired originally for his laboratory skills, Abbot became acting director of the SAO in 1896. When Langley died in 1906, Abbot succeeded him as director (in 1907). Abbot, responsible for the observatory’s solar observations, designed and built devices for measuring solar radiation, including a greatly improved bolometer which measured the Sun’s inner corona at the 1900 solar eclipse in Wadesboro, NC. He also proposed a more accurate value of 1.93 cal/cm²/min for the solar constant (the modern value is measured in watts per square meter).

In 1918 Abbot became Assistant Secretary of the Smithsonian Institution. He succeeded Charles Walcott as Secretary in 1928, and guided the Institution through the Great Depression and World War II. In 1941, he became original standing committee member of the Foundation for the Study of Cycles. He retired as both SAO director and Smithsonian Secretary in 1944, becoming the first Smithsonian Secretary not to die in office. He delegated the National Museum largely to his Assistant Secretary,Alexander Wetmore, who succeeded him as Secretary in 1944.

Abbot pursued the idea that the Sun’s radiation was variable and that variability could influence the weather. He persistently searched for variations in the solar constant, hoping that these could be used for weather forecasting, and believed that he had detected such variations, on the order of 3% to 10%. However, modern measurements of greater accuracy indicate that such variability does not occur, apart from tiny variations due to sunspots and faculae. He completed the mapping of the infrared solar spectrum and carried out systematic studies of variation in solar radiation, its relation to the sunspot cycle, and its effect on weather variation. He also studied the nature of atmospheric transmission and absorption. Abbot perfected various standardized instruments now widely used for measuring the sun’s heat, and he invented devices utilizing solar energy.

In 1938, Abbot authored possibly his most singular study, although he did so anonymously. This was his contribution to the Journal of Parapsychology, detailing his studies into clairvoyance. He stated that clairvoyance had become as evidential to him as gravitation. His findings were later recognized to represent the first statistical identification of the “displacement effect” in parapsychology. He published a replication of his findings, this time under his own name, in the Journal in 1949.

Awards Abbot recieved include the Henry Draper Medal of the National Academy of Sciences in 1910 and the Rumford Prize of the American Academy of Arts and Sciences in 1915. The crater Abbot on the Moon is named after him (an exception was made and it was named after him while he was still alive). He became the oldest inventor to ever receive a patent at the age of 101. He died in Washington D.C. in 1973.

Abbot Charles Greeley