Mount Wilson Observatory Optical Shop.

Founded in December 1904 by George Ellery Hale and funded by the Carnegie Institution, the Mount Wilson Observatory quickly became one of the 20th century's major astronomical research centers. Located just north of Los Angeles high atop the San Gabriel Mountains, the observatory took full advantage of Southern California's clear nights and uniquely steady air. The observatory's 60" telescope completed in 1908 was the largest then in existence. In 1917, another Mount Wilson telescope, 100" in diameter, claimed that title. The Optical Shop was the department responsible for repairing and maintaining these telescopes. Optical Shop workers ground and polished mirrors, lenses, and prisms: tasks requiring meticulous precision and technique. In addition to serving Mount Wilson, the Optical Shop produced optical instruments for observatories across the country. During the Second World War, the Mount Wilson Observatory Optical Shop played an important role in U.S. war effort. Shop technicians produced roof prisms for military optics on a large scale, eventually publishing an instruction manual for other optical workshops. Experiments with newly-invented Schmidt cameras helped develop the field of aerial photography. New camera shutters and film sweep mechanisms were invented. Procedures for measuring lens resolution were tested.