SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE, VOL. XXXIV. 



PLATE XXIII. 



MARE IMBKIUM AND SURROUNDINGS. PHOTOGRAPHED BY RITCHEY, NOVEMBER 21, 1901, 



SEVEN HOURS THIRTY-TWO MINUTES P. M., CENTRAL STANDARD TIME. 



EXPOSURE, ONE SECOND. SCALE, ONE-HALF METER 



TO MOON'S DIAMETER. 



see 







