50. Four views of Mars, showing canals. (Lowell)
Note: this image is a thumbnail only.
49. Two views, showing seasonal change on Mars. (Lowell)
48. Three photographs of Mars, showing rotation. (Yerkes Obs.)
47. Drawing of Mars. (Trumpler, Lick Obs.)
46. Diagram of motions of earth and Mars, 1926.
45. Photograph of crescent Venus. (Barnard, Yerkes Obs.)
44. Motion of Venus as seen from earth. (Copyright)
43. Mercury, the swift messenger of the gods.
42. Key to photograph, No. 41.
41. Portion of moon. (Mt. Wilson Obs.)
Note: this is a thumbnail image only.
