This achievement earned Douglass' reputation as the "father of dendrochronology."īy 1909, Douglass published tree-ring research results that he said suggested a close relationship between climate and the 11.3-year sunspot cycle. Douglass' greatest technical discovery, made in 1911, was the technique of crossdating tree rings, or matching ring patterns to extend the record of precise tree ages back through time. This model is the most complete and efficient version of Douglass' cycloscopes," Kinsley said.ĭouglass, first director of the Lowell Observatory in Flagstaff and later founder of the UA Steward Observatory in Tucson, began studying tree-rings for information on climate before he joined the UA faculty in 1906. "He designed this particular instrument in 1935, had Stanford University build it in 1936, and named it the Merriam Cycloscope in honor of the then-president of the Carnegie Institution of Washington, which funded the project. "Douglass began developing the cycloscope in 1913," he said.
He recently gave an informal talk about it at the UA Laboratory of Tree-Ring Research. Last September, Kinsley reported on Douglass' complex invention at the 21st Scientific Instrument Symposium in Athens, Greece, and at the Antique Telescope Society Convention at Trinity College, Dublin, Ireland. He also found film footage of Douglass, assisted by Edmund Schulman, demonstrating the cycloscope. Kinsley reviewed 180 boxes of Douglass' material archived at the museum and at UA Special Collections for the history of the cycloscope.
A wheel on the track measures how far the mirrors are from the optics, which tells the length, in years, of a pattern's cycle. The mirrors reflect light into the optics so that observers can immediately see when plots match and when they don't. The apparatus, a far bigger device than any of its predecessors, features an "Illuminator-Comparator" ? an attachment that shines light through displays of tree-ring-width skeleton plots and cyclograms of sunspot numbers - two mirrors that move along a track that extends to 40 feet, and sophisticated optics on a two-tier analyzing bench, Kinsley discovered.Ī lightbox of ten, 60-watt light bulbs spaced 4 inches apart illuminates the display plots, shining the subsequent light patterns onto the mirrors along the moveable track. Kinsley said Arizona State Museum conservator Nancy Odegaard tipped him off to Douglass' "dendrochronology unit" stored at the state museum. Kinsley also is knowledgeable about the photographic equipment that John Wesley Powell used on his 1871 journey down the Colorado River. "My interest in instruments centers more on the 16th and 17th centuries, but there simply aren't very many artifacts from that period floating around in Arizona," said Kinsley, who works at the UA Center for Creative Photography until the end of June. Three years ago Kinsley earned a master's degree in the history of science from Oxford University, where he studied science instruments dating from 1470 to 1930. "Douglass made a substantial contribution to American science and designed some extraordinary instruments." A science historian has discovered how a famous early University of Arizona scientist used his amazing contraption called the "cycloscope" in a long but futile quest to discover predictable cycles of solar activity in tree rings.Īndrew Ellicott Douglass (1867 ? 1962) "was a polymath of the first order, engaged in astronomy, physics, botany, climatology, photography and archaeology," said Shaw D.
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