A. E. Douglass

Andrew Ellicott Douglass ( born July 5, 1867 in Windsor, Vermont, † March 20, 1962 in Tucson, Arizona) was an American astronomer and is considered the founder of dendrochronology.

Life and work

Leonardo da Vinci already suspected that the tree rings reflect the climatic growing circumstances in an annual rhythm. In the 17th and 18th centuries it was known generally and used to determine the age of trees. End of the 19th century Arthur has " overlap " of Seckendorf Gudent - ring series of trees, but it was not until Douglass, by means of the " overlap" technique (cross- dating method) to determine the age of dead and built tree samples. Douglass drilled the first well of trees to obtain information about the climatic growth conditions and the suspected relationship to the solar activity by means of the thickness of the annual rings.

Douglass first worked at the Harvard College Observatory. After he had taken Percival Lowell, he led from 1894 to 1906 at the Lowell Observatory in Flagstaff mainly Mars observations and began the first research on the relationships of tree rings to the solar activity. In 1906, Douglass taught in Tucson and worked at the systematic development of dendrochronology. In 1918 he began with the dating of tree samples from ancient Aztec ruins, 1929, he was unable to allocate a 585 -year tree-ring chronology of yellow pine (Pinus ponderosa ) archaeological finds. Between 1919 and 1936 his Climate Cycles and Tree Growth was published in three volumes. From 1923 to 1937 he was director of the newly founded Steward Observatory of the University of Arizona. After his retirement, he wrote many essays on dendrochronology and climate research.

The dating of tree samples by means of dendrochronology can now be regarded as a mature and established science. More difficult the relationship between the tree-ring growth and the solar activity is to be detected, because correlations only transiently, ie at times seem to occur.