Douglass, Andrew Ellicott (1867-1962)

American astronomer and archaeologist

Andrew E. Douglass invented and named dendrochronology, the technique of counting and studying the rings in tree trunks to determine not only the ages of trees, but also the past climatological, geological, agricultural, social, and economic conditions of the local area .

Born in Windsor, Vermont, on July 5, 1867, Douglass received his bachelor's degree with honors in 1889 from Trinity College in Hartford, Connecticut. After working five years for the Harvard University Observatory, including an expedition to Arequippa, Peru, from 1891 to 1893 to establish Harvard's Southern Hemisphere Observatory, he accepted the offer of astronomer Percival Lowell (1855–1916) to build an observatory in the American Southwest. They founded Lowell Observatory in 1894 by erecting an 18-inch telescope on a mesa outside Flagstaff, Arizona. Lowell was preoccupied with Mars, and some historians argue that Lowell may have skewed Douglass' data in order to support his theories of Martian life and civilization. The two scientists'increasingly hostile disagreements about the proper use of data led Lowell to fire Douglass in 1901.

Douglass then taught school in the Flagstaff area, won an election for probate judge, and around 1904, began to note the connection between tree rings and solar cycles. In 1906, he

moved to Tucson and joined the astronomy faculty of the University of Arizona. Increasingly interested in the possibility of using tree rings for archaeological dating, he concentrated his research on the ponderosa pine, the Douglas fir, and, in collaboration with Ellsworth Huntington (1876–1947), the giant sequoia. Beginning in 1909 his work received support from Clark Wissler (1870–1947) of the American Museum of Natural History in New York City and philanthropist Archer Milton Huntington (1870–1955). By the second decade of the twentieth century, dendrochronology was widely recognized as an important scientific insight.

After convincing Lavinia Steward (d. 1917) to found a new observatory at the University of Arizona with a bequest of $60,000 from the estate of her late husband, Henry B. Steward (d. 1902), Douglass became the first director of Steward Observatory in 1916. Its 36-inch reflecting telescope, one of the first in the nation, became operational in 1922 and the facility was dedicated in 1923.

Douglass retired from the observatory in 1937, but served the University of Arizona from 1937 until 1958 as the founding director of the Laboratory of Tree-Ring Research. He continued actively engaging in dendrochronological studies until within two years of his death in Tucson on March 20, 1962. His manuscripts and notes, held by the University of Arizona Library Special Collections, reveal an extraordinarily precise, flexible, and meticulous scientist.

See also Archeological mapping; Dating methods; Precipitation; Solar energy; Sun; Weathering and weathering series