Appendix
Dates, and age of the moon, when the twenty-one serial photographs were made at the Yerkes Observatory, by Mr. Wallace, with the 12-inch telescope and a special color filter constructed by him:
| No. 1, | February 19, 1904; | Moon’s Age 3.85 Days |
| No. 2, | September 24, 1903; | Moon’s Age 3.87 Days |
| No. 3, | July 29, 1903; | Moon’s Age 5.54 Days |
| No. 4, | November 24, 1903; | Moon’s Age 5.74 Days |
| No. 5, | July 1, 1903; | Moon’s Age 6.24 Days |
| No. 6, | November 26, 1903; | Moon’s Age 7.75 Days |
| No. 7, | July 2, 1903; | Moon’s Age 7.24 Days |
| No. 8, | August 31, 1903; | Moon’s Age 9.22 Days |
| No. 9, | August 2, 1903; | Moon’s Age 8.97 Days |
| No. 10, | November 30, 1903; | Moon’s Age 11.78 Days |
| No. 11, | December 1, 1903; | Moon’s Age 12.98 Days |
| No. 12, | September 4, 1903; | Moon’s Age 13.27 Days |
| No. 13, | September 5, 1903; | Moon’s Age 14.40 Days |
| No. 14, | August 26, 1904; | Moon’s Age 15.65 Days |
| No. 15, | August 28, 1904; | Moon’s Age 17.41 Days |
| No. 16, | August 29, 1904; | Moon’s Age 18.62 Days |
| No. 17, | October 10, 1903; | Moon’s Age 20.06 Days |
| No. 18, | September 29, 1904; | Moon’s Age 20.50 Days |
| No. 19, | August 16, 1903; | Moon’s Age 23.81 Days |
| No. 20, | August 17, 1903; | Moon’s Age 24.84 Days |
| No. 21, | August 19, 1903; | Moon’s Age 26.89 Days |