David Rumsey Historical Map Collection
16. San Francisco Aerial Negative.
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Set of 164 black and white negatives of the same Harrison Ryker Aerial 1938 Survey that we scanned for the San Francisco Library (our 5852.000). Negatives have been scanned to positive and the digital files provided by the Western Neighborhoods Project. The database, image processing, and large composite image by David Rumsey.
San Francisco County (Calif.)
San Francisco (Calif.)
16. Aerial Negative. City and County of San Francisco. August 27, 1938. Scale: 1" = 500 Feet. (Aerial Photographs).
Aerial Negatives. City and County of San Francisco. August 27, 1938. Scale: 1" = 500 Feet.
(Continued from Note field above). Shortly after 1938 Ryker established his company address as Harrison C. Ryker, Inc., at 1000 Ashby Avenue, Berkeley, California (relocating to east Oakland in the 1950s). He subsequently manufactured pocket and desktop stereoscopes and a vertical Sketchmaster, instruments that were extensively used by educational institutions and the military, especially during World War II. His experience in aerial photography led to further involvement in photo interpretation and cartography. An article in the journal The Timberman (1933) describes means of distinguishing individual species of forest trees on aerial photos; later applications were terrain analysis for petroleum geology and unmasking of ground camouflage during wartime. His largest product was the Wernstedt Mahan map plotter, patented in 1954, which was a standard cartographic device for its time. His instruments are in use today in libraries, air photo collections, and earth sciences departments throughout America; they are in the instrument collections of the Archives of the History of American Psychology, and the Institute of Geographical Exploration at Harvard University has the Ryker M-11 Reflecting Stereoscope. Among his patents were the (1) the adjustable pocket stereoscope filed with the United States Patent Office: Patented December 1940. Patent No. 2,225,602, and the (2) the stereoscope filed with the United States Patent Office: Filed September 1, 1937, Serial No. 161,973; Patented January 21, 1941, Patent No. 2,229,309. Harrison Ryker pioneered research in aerial photo interpretation. His work has been noted by A. Everett Wieslander, an early (1930s – 1950s) leader in the mapping of California vegetation and soils, in his Oral History produced by The Bancroft Library, and in a letter by Robert Colwell, Forestry Professor at the University of California, Berkeley.
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