SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE, VOL. XXXIV. 



PLATE XXII. 



MARE TRANQUIL1TATIS AND SURROUNDINGS. PHOTOGRAPHED BY R1TCHEY, AUGUST 3, 1901, 



TWO HOURS THIRTY MINUTES A. M., CENTRAL STANDARD TIME. EXPOSURE, 



THREE-FOURTHS SECOND. SCALE, THREE-FOURTHS 



METER TO MOON'S DIAMETER. 



