Doheny Memorial Library, Los Angeles, CA 90089-0189 Public Domain. Release under the CC BY Attribution license--http://creativecommons.org/licenses/by/3.0/--Credit both “University of Southern California. Libraries” and “California Historical Society” as the source. Digitally reproduced by the USC Digital Library; From the California Historical Society Collection at the University of Southern California Send requests to address or e-mail given USC Libraries Special Collections specol@usc.edu
Description
Photograph of the horizontal snow telescope at Mount Wilson Observatory, ca.1930. The walls of the telescope are layered. Several pulley contraptions and the lens sit on an open platform at the eye of the telescope. Utility lines zigzags across the tree covered area. "The Snow Telescope, the oldest telescope on the mountain, is named after its benefactor, Helen Snow. She donated money for its construction at Yerkes Observatory in Williams Bay, Wisconsin. George Ellery Hale moved the telescope to Mount Wilson in 1904 to make observations of the Sun. Dr. Hale took the telescope on loan from Yerkes, although it has been here ever since. Unlike the two tower solar telescopes (which were built later), the light path for the Snow Telescope is horizontal. The building is long and originally was covered in canvas. This was a great fire hazard, and the crude building was replaced with an aluminum shell in 1911. Light from the Sun is reflected off the coelostat mirror (on the right partially in shadow) to another 30-inch mirror (at center) and reflected nearly horizontally 100 feet to the back of the building. There, it falls on a 24-inch concave mirror with a 60-foot focal length and is then brought to a focus at the entrance slit of the spectrograph as an image 6 1/2 inches across. The spectrograph is located in a 15-foot pit. Despite its simple construction, the horizontal light path of the Snow Telescope made observations difficult because heat from the sunlit ground affected the observational seeing. Therefore, shortly after being put into operation in 1904, plans were made to build the 60-foot Solar Tower." -- unknown author.
Type
image
Format
2 photographs : glass photonegative, photoprint, b&w 21 x 26 cm. glass plate negatives photographic prints photographs
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