FOOTNOTES
[1] Her mountains by some have been calculated nine miles high; but Dr. Herschell’s telescopes, which magnify 6500 times, have reduced her highest hills to about two miles. Mr. Shroeter apprehends that the mountain Leibnitz is not less than 25,000 feet high. The Craters of the Moon are from 4 to 15 miles diameter. He discovers some new spots on the Moon, and calculates her atmosphere to be 5376 feet high, an height so inconsiderable that it might escape our best telescopes or most minute observations.
[2] It is rather curious how the antients saw so much of him as that his period was tolerably guessed, at least so far back as the days of Cicero.—De Nat. Deor. II. 20. They knew it to be less than the Earth’s: which, though far from accurate, was a nearer calculation than could be then expected. And this is the more remarkable if Cicero had it from Plato, and he from Ægypt and Syria.
[3] If the Earth turned round its axis in 84 minutes and 43 seconds, the centrifugal force would be equal to the power of gravity at the equator; and all bodies there would entirely lose their weight. If the Earth revolved quicker, they would all fly off and leave it.
[4] The velocity of a cannon-ball is about eight miles per minute.
| Of the Comet in its perihelion | 14,600 |
| Of Light | 12,000,000 |
[5] Perhaps the inhabitants of one system may be destined successively to pass from planet to planet, and from systems to other systems. This would answer, on an immense scale, to the analogy existing on Earth. It is stated as a conjecture with much energy and beauty in a late work. Illustrat. of Proph. T. II. p. 557, Anno 1796.