Professor Adolphus Hall of the U.S. Naval Observatory looking through the 26” telescope, August 18, 1924.

LC-DIG-NPCC-26047: Professor Adolphus Hall of the U.S. Naval Observatory looking through the 26” telescope, August 18, 1924. (8/21/2015). Foto: National Museum of the U.S. Navy, Quelle: Flickr, Lizenz: Public Domain Mark 1.0