Keywords: blackandwhite monochrome black and white LC-DIG-NPCC-26048: Professor Adolphus Hall of the U.S. Naval Observatory looking through the 26” telescope, August 18, 1924. (8/21/2015). LC-DIG-NPCC-26048: Professor Adolphus Hall of the U.S. Naval Observatory looking through the 26” telescope, August 18, 1924. (8/21/2015). |