Critique of Practical Reason and Other Works on Ethics

MEMOIR OF KANT.

...has been verified. He also conjectured, based on his hypothesis regarding how the ring was formed, that the maximum speed of rotation for the particles of the inner ring would be the same as the speed of the planet’s equator. From this idea, combined with the assumption that the ring follows Kepler’s third law Kepler's third law: A mathematical relationship stating that the square of a planet's orbital period is proportional to the cube of its average distance from the Sun., he calculated the time of the planet’s rotation. He highlighted this specifically as the first prediction of its kind. His calculation, however, has not been proven correct. Saturn’s actual rotation time is nearly double what it should be according to Kant’s theory.^1 Another of his conjectures, which was later verified, was that there are planets beyond Saturn. Later, he also conjectured the existence of a planet between Mars and Jupiter.^2 This refers to the asteroid belt, specifically Ceres, discovered in 1801.

Kant then expands his view to the sidereal system The system of the stars; the galaxy.. He states that the first person to suggest to him that the fixed stars formed a system was Wright, of Durham.^3 Kant develops this concept further. If gravitation is a...

1 Kant assumed too hastily that Kepler’s third law applies to the individual particles of the ring, which assumes that their effects on each other are negligible. Yet, considering the form of the rings, this is not an unreasonable hypothesis.
2 Physical Geography original: Phys. Geogr., p. 449.
3 Wright’s work was entitled, An Original Theory; or, a New Hypothesis of the Universe founded on the Laws of Nature. By Thomas Wright, of Durham. London, 1750. It is remarkable that the ideas of this clever and original writer were saved from being forgotten in his own country by Kant, who learned of them through a German magazine. Professor De Morgan described Wright’s work at some length in the Philosophical Magazine for April, 1848; but De Morgan’s attention was only drawn to it by Arago’s mention in the Yearbook original: Annuaire for 1842. Arago, who had not actually seen the book, only knew of it through Kant’s reference. There is an account of Wright in the Gentleman’s Magazine, 1793, volume 63, part 1.