Smithsonian Contributions to Knowledge. Vol. XXXIV. 



Plate XXI. 



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



SEVEN HOURS THH^TY-TWO MINUTES P. M. EXPOSURE, ONE SECOND. 



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



