Note 8 — Chapter III · THE COOLING OF THE PLANETS.
Reading edition
“Its mean density is less than that of any known planet, being less than one-seventh of the earth.”
Proctor, “Expanse of the Heavens,” p. 97.
Reading edition
“Its mean density is less than that of any known planet, being less than one-seventh of the earth.”
Proctor, “Expanse of the Heavens,” p. 97.