Richard A. Proctor Quotes
Richard A. Proctor (1872). “Essays on astronomy: a series of papers on planets and meteors, the sun and sun-surrounding space, stars and star cloudets, and a dissertation on the approaching transits of venus : preceded by a scetch of the life and work of Sir John Herschel”, p.1
"Saturn and its System". Book by Richard Anthony Proctor, (2nd edition), Chapter 2, p. 32, 1882.