nows how many comets, in his hundred
hands. The moons, of those solar planets which have them, represent the
epi-epicyclical orbits of the Ptolemaic theory. It is curious, and also
touching, to notice how often the errors of man are thus the shadows of
truth. Were it not for the preceding shadows, indeed, the substance
would never arrive; and therefore the Ptolemaics of the world are
second, in value and in merit, only to epochal discoverers like
Copernicus.

Suppose the sun to be represented by a radiant little orb two feet in
diameter, in order to bring it within the measure of our eye; then this
great globe of ours, with all its stupendous histories, is no bigger
than a full-sized pea in proportion, revolving at the distance of 215
feet. Neptune, the outermost and last discovered of the planets, would
stand at the distance of a mile and a quarter from a sun of that
imaginary size, and it would be no larger than a cherry. Another cherry
at the distance of three-quarters of a mile would stand for Uranus.
Saturn would be a small orange at two-fifths of a mile from our two-feet
solar body. A middle-sized orange, at the distance of a quarter of a
mile, would be his Jupiter. At some 500 feet the nine little planets,
commonly called asteroids, probably enough the fragments of an exploded
orb, and now moving in a sort of group, would be represented by as many
grains of sand. A pin-head, at 327 feet, would do for Mars. Then comes
the earth. Still nearer the sun, namely at 142 feet from our present
model, revolves Venus, of the dimensions of a pea. And finally little
Mercury wheels along his orbit, with a radius of 82 feet, and the
dimensions of a mustard seed.

Add the terrestrial moon, the four moons of Jupiter, the ring within
ring that whirls round Saturn like an endless moon, the eight ordinary
moons of that extraordinary planet, the moons of Uranus and Neptune (yet
uncertain in their number), and it is impossible to say how many comets,
not to forget the enormous groups or hosts of comparatively small stones
or meteors, which are believed to be revolving round the solar centre
like pigmy asteroids; and the Copernican conception of the mere
constitution of the solar system, as developed by time and toil, is
completed. The sun is 882,000 miles in diameter; the earth is 7926; Juno
is 79; Saturn, 79,160, and so forth. The earth is more than five times
as heavy as water; Saturn is as light as cork. The earth rotates in
twen