SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE, VOL. XXXIV. 



PLATE XXI. 



MARE NUBIUM AND SURROUNDINGS. PHOTOGRAPHED BY R1TCHEY, NOVEMBER 21, 1901, 



SEVEN HOURS THIRTY-TWO MINUTES P. M. EXPOSURE, ONE SECOND. 



SCALE, ONE-HALF METER TO MOON'S DIAMETER. 



