istinctly stated that the laws of
Kepler are _the basis_ of the great principle, Gravitation. This idea
must have arisen from the fact that the suggestion of these laws by
Kepler, and his proving them _a posteriori_ to have an actual existence,
led Newton to account for them by the hypothesis of Gravitation, and,
finally, to demonstrate them _a priori_, as necessary consequences of
the hypothetical principle. Thus so far from the laws of Kepler being
the basis of Gravity, Gravity is the basis of these laws--as it is,
indeed, of all the laws of the material Universe which are not referable
to Repulsion alone.

The mean distance of the Earth from the Moon--that is to say, from the
heavenly body in our closest vicinity--is 237,000 miles. Mercury, the
planet nearest the Sun, is distant from him 37 millions of miles. Venus,
the next, revolves at a distance of 68 millions:--the Earth, which comes
next, at a distance of 95 millions:--Mars, then, at a distance of 144
millions. Now come the eight Asteroids (Ceres, Juno, Vesta, Pallas,
Astraea, Flora, Iris, and Hebe) at an average distance of about 250
millions. Then we have Jupiter, distant 490 millions; then Saturn, 900
millions; then Uranus, 19 hundred millions; finally Neptune, lately
discovered, and revolving at a distance, say of 28 hundred millions.
Leaving Neptune out of the account--of which as yet we know little
accurately and which is, possibly, one of a system of Asteroids--it will
be seen that, within certain limits, there exists an _order of interval_
among the planets. Speaking loosely, we may say that each outer planet
is twice as far from the Sun as is the next inner one. May not the
_order_ here mentioned--_may not the law of Bode--be deduced from
consideration of the analogy suggested by me as having place between the
solar discharge of rings and the mode of the atomic irradiation_?

The numbers hurriedly mentioned in this summary of distance, it is folly
to attempt comprehending, unless in the light of abstract arithmetical
facts. They are not practically tangible ones. They convey no precise
ideas. I have stated that Neptune, the planet farthest from the Sun,
revolves about him at a distance of 28 hundred millions of miles. So far
good:--I have stated a mathematical fact; and, without comprehending it
in the least, we may put it to use--mathematically. But in mentioning,
even, that the Moon revolves about the Earth at the comparatively
trifling distance of 2