[13] Monthly Notices. 74, 699, 1914.
[14] Annalen der Wiener Sternwarte, 20, 1907.
[15] Astronomische Nachrichten, 214, 425, 1921.
[16] Publications of the Lick Observatory, 13, 1918.
[17] Since C is constant for all nebulae in a given class, the linear relation between Δ log d and C for the different classes is something more than a mere geometrical relation arising from the observed equality of the mean mT in the various classes.
[18] This is apparent even among the observed classes. Referring to [formula (3)], mT + 5 log b will be constant in so far as Ce + 5 log (1 – e) is constant. The following table indicates that the latter term is approximately constant throughout the sequence of elliptical nebulae. The values of Ce were read from the smooth curve in [Fig. 6].
| e | Ce | 5 log (1 – e) | C0 | Res. |
|---|---|---|---|---|
| 0 | 10.30 | 0.0 | 10.30 | –0.14 |
| 1 | 10.65 | – .23 | 10.42 | – .02 |
| 2 | 11.00 | .48 | 10.52 | + .10 |
| 3 | 11.35 | 0.78 | 10.57 | + .13 |
| 4 | 11.70 | 1.11 | 10.59 | + .15 |
| 5 | 12.05 | 1.50 | 10.55 | + .11 |
| 6 | 12.40 | 1.99 | 10.41 | – .03 |
| 7 | 12.75 | –2.62 | 10.13 | –0.31 |
| Mean | 10.44 | 0.12 |
[19] Mt. Wilson Contr., No. 191; Astrophysical Journal, 52, 162, 1920.
[20] Pease, Mt. Wilson Comm., No. 51; Proceedings of the National Academy of Sciences, 4, 21, 1918.
[21] Pease, Mt. Wilson Comm., No. 32: ibid., 2, 517, 1916.