[211] More Worlds Than One, p. 45.
[212] Herschel's Outlines, VI. Sect. 400.
[213] Dr. George Wilson, F. R. S. E., in Edinburgh Phil. Journal, V. p. 53.
[214] Somerville's Connection of the Physical Sciences, p. 360.
[215] Dick's Sidereal Heavens, chap. xx.
[216] Nichol's Solar System, p. 76.
[217] Cosmos, III. p. 27.