The solar corona. (Photographed by the Yerkes Observatory Eclipse Expedition, May 28, 1900. Barnard and Ritchey)
Big glass of the past.
When George Ellery Hale founded Yerkes Observatory in 1897, its 40-inch refracting telescope was the largest in the world. Refracting optical telescopes use glass lenses, as compared to reflecting telescopes, which use mirrors, such as the
Giant Magellan Telescope.
[[{"type":"media","view_mode":"media_original","fid":"2912","attributes":{"alt":"","class":"media-image","height":"589","typeof":"foaf:Image","width":"500"}}]] (University of Chicago Photographic Archive, apf6-01389, Special Collections Research Center, University of Chicago Library)
Double-slide plate holder on the Yerkes Observatory 40-inch refracting telescope.
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Sherburne W. Burnham observing at the top of the pier of the telescope.
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Alvan Graham Clark and
Carl Lundin with the telescope’s objective lens, which gathers and bends light to focus an image. (The eyepiece lens magnifies it.)