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A. E. (Andrew Ellicott) Douglass (July 5, 1867 in
Windsor, Vermont Windsor is a town in Windsor County, Vermont, United States. As the "Birthplace of Vermont", the town is where the Constitution of Vermont was adopted in 1777, thus marking the founding of the Vermont Republic, a sovereign state until 1791, when ...
– March 20, 1962 in
Tucson, Arizona , "(at the) base of the black ill , nicknames = "The Old Pueblo", "Optics Valley", "America's biggest small town" , image_map = , mapsize = 260px , map_caption = Interactive map ...
) was an American
astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either obse ...
. He discovered a correlation between
tree ring Dendrochronology (or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed. As well as dating them, this can give data for dendroclimatology, the study of climate and atmos ...
s and the
sunspot cycle The solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surfac ...
, and founded the discipline of
dendrochronology Dendrochronology (or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed. As well as dating them, this can give data for dendroclimatology, the study of climate and atmos ...
, which is a method of dating wood by analyzing the growth ring pattern. He started his discoveries in this field in 1894 when he was working at the
Lowell Observatory Lowell Observatory is an astronomical observatory in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark ...
. During this time he was an assistant to
Percival Lowell Percival Lowell (; March 13, 1855 – November 12, 1916) was an American businessman, author, mathematician, and astronomer who fueled speculation that there were canals on Mars, and furthered theories of a ninth planet within the Solar System. ...
, but fell out with him when his experiments made him doubt the existence of artificial "
canals Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface flow un ...
" on
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmosp ...
and visible cusps on
Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...
. Craters on the
Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
and Mars are named in his honor.


Founding of Steward Observatory

After a 5-year hiatus from astronomy, Douglass left
Flagstaff, Arizona Flagstaff ( ) is a city in, and the county seat of, Coconino County in northern Arizona, in the southwestern United States. In 2019, the city's estimated population was 75,038. Flagstaff's combined metropolitan area has an estimated population o ...
in 1906 and accepted a position as Assistant Professor of Physics and Geography at the
University of Arizona The University of Arizona (Arizona, U of A, UArizona, or UA) is a public land-grant research university in Tucson, Arizona. Founded in 1885 by the 13th Arizona Territorial Legislature, it was the first university in the Arizona Territory. Th ...
in
Tucson, Arizona , "(at the) base of the black ill , nicknames = "The Old Pueblo", "Optics Valley", "America's biggest small town" , image_map = , mapsize = 260px , map_caption = Interactive map ...
. Almost immediately upon his arrival in Tucson, Douglass re-established his astronomical research programs using an 8-inch refracting telescope on loan from the
Harvard College Observatory The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, United St ...
and actively began to pursue funding to construct a large research-class telescope in Tucson. Over the next 10 years Douglass was unable to secure funding from the university and the Arizona Territorial (and later State) Legislatures. During this period Douglass served the University of Arizona as Head of the Dept. of Physics and Astronomy, Interim President, and finally Dean of the College of Letters, Arts, & Sciences. On October 18, 1916, University President Rufus B. von KleinSmid announced that an anonymous donor had given the university
US$ The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...
60,000 "... to be used to buy a telescope of huge size"; the donor was later revealed to be Mrs. Lavinia Steward of
Oracle, Arizona Oracle is a census-designated place (CDP) in Pinal County, Arizona, United States. The population was 3,686 at the 2010 Census, falling to 3,051 at the 2020 Census. Buffalo Bill Cody owned the High Jinks Gold Mine in Oracle briefly and, in 191 ...
, a wealthy widow with an interest in astronomy and a desire to commemorate her late husband, Henry Steward. Douglass made plans to use the Steward gift to construct a 36-inch Newtonian reflecting telescope. The Warner & Swayze Company of
Cleveland, Ohio Cleveland ( ), officially the City of Cleveland, is a city in the U.S. state of Ohio and the county seat of Cuyahoga County. Located in the northeastern part of the state, it is situated along the southern shore of Lake Erie, across the U.S. ...
was contracted to build the telescope, but the United States entry into World War I delayed the contract since Warner & Swayze had war contracts that took priority. Until this time expertise in large telescope mirror making was in Europe, but the war made it impossible to contract with a European company, so Douglass had to find an American glass company willing to develop this expertise. After a couple of failed castings, the Spencer Lens Co. of
Buffalo, New York Buffalo is the second-largest city in the U.S. state of New York (behind only New York City) and the seat of Erie County. It is at the eastern end of Lake Erie, at the head of the Niagara River, and is across the Canadian border from Southe ...
produced the mirror for the Steward Telescope. The telescope was finally installed in the observatory building in July 1922, and the
Steward Observatory Steward Observatory is the research arm of the Department of Astronomy at the University of Arizona (UArizona). Its offices are located on the UArizona campus in Tucson, Arizona (US). Established in 1916, the first telescope and building were ...
was officially dedicated on April 23, 1923. In his dedication address, Douglass recounted the trials and tribulations of establishing the observatory, then gave the following eloquent justification for the scientific endeavor:
This installation is to be devoted to scientific research. Scientific research is business foresight on a large scale. It is knowledge obtained before it is needed. Knowledge is power, but we cannot tell which fact in the domain of knowledge is the one which is going to give the power, and we therefore develop the idea of knowledge for its own sake, confident that some one fact or training will pay for all the effort. This I believe is the essence of education wherever such education is not strictly vocational. The student learns many facts and has much training. He can only dimly see which fact and which training will be of eminent use to him, but some special part of his education will take root in him and grow and pay for all of the effort which he and his friends have put into it. So it is with the research institutions. In this Observatory I sincerely hope and expect that the boundaries of human knowledge will be advanced along astronomical lines. Astronomy was the first science developed by our primitive ancestors thousands of years ago because it measured time. Performing that same function, it has played a vast part in human history, and today it is telling us facts, forever wonderful, about the size of our universe; perhaps tomorrow it will give us practical help in showing us how to predict climatic conditions in the future.


Collaboration with the American Museum of Natural History

In 1909
Clark Wissler Clark David Wissler (September 18, 1870 – August 25, 1947) was an American anthropologist, ethnologist, and archaeologist. Early life Clark David Wissler was born in Cambridge City, Indiana on September 18, 1870 to Sylvania (née Needler) an ...
of the
American Museum of Natural History The American Museum of Natural History (abbreviated as AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. In Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 26 inte ...
organized the Archer M. Huntington Survey. One objective of this survey was to determine temporal arrangement of the American Southwest's prehistoric ruins. Wissler, who had read about Douglass's work concerning the relationship between precipitation and tree growth, later contacted Douglass saying:
Your work suggests to me a possible help in the archaeological investigation of the Southwest…We do not know how old these ruins are, but I should be glad to have an opinion from you as to whether it might be possible to connect up with your modern and dated trees specimens ith wood specimensfrom these rehistoricruins by correlating the curves of growth.Nash 1999, p. 23
On June 19, 1914, the curator of the American Museum of Natural History wrote a letter to Douglass expressing his desire to begin archaeological analysis as early as possible. In 1916 Douglass began obtaining and analyzing archaeological samples first collected during an expedition to northwest New Mexico by the University of Colorado and the American Museum of Natural History. In April 1918 Wissler asked Douglass whether or not it would be possible to assign relative dates to samples that could not be dated absolutely. Although this information would not associate particular sites with exact years, it would reveal whether or not ruins were constructed within the same time period. On May 22, 1919, Douglass informed Wissler that six specimens from Aztec Ruin, New Mexico were cut down within a two-year period, and estimated that samples from Pueblo Bonito in New Mexico were possibly 25 years older than those collected at Aztec Ruin. Upon receiving this news, Wissler was certain that Douglass would make a crucial contribution to archaeology. Douglass continued comparing samples between the two sites and concluded Pueblo Bonito actually predated Aztec Ruin by 40 to 45 years. These findings led to realization that relative dating could be used on many of the other ruins in the Southwest. Although promising steps had been made in solving the mystery of the ruins in the Southwest, in 1920 the American Museum of Natural History discontinued funding Douglass's research.


Beam Expeditions with the National Geographic Society

On January 22, 1922, Douglass was informed that the
National Geographic Society The National Geographic Society (NGS), headquartered in Washington, D.C., United States, is one of the largest non-profit scientific and educational organizations in the world. Founded in 1888, its interests include geography, archaeology, and ...
could be a potential source of funding. By May of that year the idea of a Beam Expedition funded by the National Geographic Society was conceived (Nash 1999: 30–31), and expeditions took place in 1923 and 1928. They produced a floating chronology of 585 years for Southwestern ruins, and extended Douglass's Flagstaff chronology of Ponderosa Pine, which was 500 years long in 1914, to 1260. However, these expeditions failed to bridge the gap that existed between these two chronologies.Fritts 1976, p. 8


Discovery of HH-39

In 1929 Douglass set out on a third Beam Expedition, explicitly targeting samples that would potentially bridge the gap between the two chronologies. Finally, on June 22, 1929, a beam labeled HH-39 was extracted at the Show Low site in Arizona. This beam took the Flagstaff chronology back to 1237. Later that day, the inner rings of HH-39 were successfully cross-dated against the outer rings of Douglass's floating chronology. Over 15 years after he began working with Clark Wissler, Douglass had bridged the gap and, as a result, had a continuous record of tree-ring data dating back to 700. For the first time in history, dates could be assigned to Southwestern ruins with certainty. Cliff dwelling at Tsegi Canyon, Mesa Verde, and Canyon de Chelly dated back to the 13th century. It was determined that Aztec Ruin was constructed during a period ranging from 1111 to 1120. Pueblo Bonito was found to be built in the latter portion of the 11th century.


Publication

Douglass formally reported his findings in the December 1929 issue of National Geographic. He wrote:
Its inner rings overlapped the late decades of the old chronology by 49 years, the final ring resting on the year 537 of that sequence; its outer ones overlapped the earliest 120 years of the new, the last one reaching to 1380. Thus the 26 years from 1260 to 1286, which belonged to both chronologies, were definitely matched and their union confirmed by HH-39, which in American archaeology is destined to hold a place comparable to Egypt's Rosetta Stone…With careful archaeological study we shall perhaps be able to trace the movement of clans and test tribal traditions which have been so often quoted as the early history of these people.


Formalization of dendrochronology

Douglass returned to the University of Arizona where he became the first person to formally teach classes in dendrochronology. In 1937 Douglass established the
Laboratory of Tree-Ring Research The Laboratory of Tree-Ring Research (LTRR) was established in 1937 by A.E. Douglass, founder of the modern science of dendrochronology. The LTRR is a research unit in the College of Science at the University of Arizona in Tucson. Since its fo ...
at the
University of Arizona The University of Arizona (Arizona, U of A, UArizona, or UA) is a public land-grant research university in Tucson, Arizona. Founded in 1885 by the 13th Arizona Territorial Legislature, it was the first university in the Arizona Territory. Th ...
. The A.E. Douglass papers are held at the University of Arizona Special Collections Library.


Applications of dendrochronology

Since Douglass's discovery in the US Southwest, his dendroarchaeological techniques have been used to date structures around the world. Tree rings are used to reconstruct events including fire regimes, volcanic activity, hurricane activity, glacial movement, precipitation, mass movements, and hydrology, helping to analyze the past and predict future trends. His research led him to the Hopi villages in Arizona. The village of Oraibi had been occupied since before the coming of white men in 1540. He wanted to study the logs used in buildings. The Hopis were not necessarily excited about the intrusion. Native Americans were famous for accepting gifts from white men in exchange for favors or gifts. Dr. Douglass, being aware of this tendency, presented the chief with many yards of purple chiffon velvet fabric. The chief was further pacified when Dr. Douglass' team placed pieces of turquoise in holes that were drilled into the logs to extract cores of wood. This turquoise would "appease the spirit of decay". This trade led to the discovery of one section of timber which revealed a very clear series of rings covering a period from 1260 to 1344. It had been in Hopi use from the time it was cut till the village was abandoned in 1906.Wormington, H. M.Prehistoric Indians of the Southwest. The Denver Museum of Natural History, 1978, p. 16


Selected works

Douglass, A.E. * (1944) "Tabulation of Dates for Bluff Ruin" Tree-Ring Bulletin Vol. 9, No. 2 * (1941) "Age of Forestdale Ruins Excavated in 1939" Tree-Ring Bulletin Vol. 8, No. 2 * (1940) "Tree-Ring Dates from the Forestdale Valley, East-Central Arizona" Tree-Ring Bulletin Vol. 7, No. 2 * (1921) "Dating Our Prehistoric Ruins: How Growth Rings in Timbers Aid in Establishing the Relative Ages in Ruined Pueblos of the Southwest" Natural History Vol. 21, No. 2


See also

* Jack Eddy


Notes


References

* Creasman, P.P., B. Bannister, R.H. Towner, J.S. Dean, and S.W. Leavitt. 2012. "Reflections on the Foundation, Persistence, and Growth of the Laboratory of Tree-Ring Research, circa 1930–1960". ''Tree-Ring Research'' 68(2): 81–89. * Douglass, A.E. 1929. "The secret of the Southwest solved by talkative tree rings". ''National Geographic Magazine'' 56(6): 736–770. * Fritts, H.C. 1976. ''Tree rings and climate''. Blackburn Press, Caldwell, NJ. * Haury, E.W. 1962. "HH-39: Recollections of a Dramatic Moment in Southwestern Archaeology". ''Tree-Ring Bulletin'' 24: 3–4. * Nash, S.E. 1999. ''Time, Trees, and Prehistory: Tree-Ring Dating and the Development of North American Archaeology 1914–1950''. Salt Lake City: University of Utah Press. * Stokes, M.A. and T.L. Smiley. 1968. ''An Introduction to Tree Ring Dating''. University of Chicago Press. Chicago.


External links


A.E. Douglass
Short biography from the
Lowell Observatory Lowell Observatory is an astronomical observatory in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark ...
.
American Museum of Natural History

Laboratory of Tree-Ring Research at the University of Arizona

Steward Observatory at the University of Arizona
* {{DEFAULTSORT:Douglass, Andrew 1867 births 1962 deaths University of Arizona faculty American astronomers People from Windsor, Vermont People associated with the American Museum of Natural History Trinity College (Connecticut) alumni Scientists from Vermont