[1. "The Heavens," p. 251.

2. "Edinburgh Review," October, 1874, p. 205.]

{p. 85}

In the years 1767 and 1779 Lexell's comet passed though the midst of
Jupiter's satellites, and became entangled temporarily among them.
But not one of the satellites altered its movements to the extent of
a hair's breadth, or of a tenth of an instant."[1]

But it must be remembered that we had no glasses then, and have none
now, that could tell us what were the effects of this visitation upon
the surface of Jupiter or its moons. The comet might have covered
Jupiter one hundred feet--yes, one hundred miles--thick with gravel
and clay, and formed clouds of its seas five miles in thickness,
without our knowing anything about it. Even our best telescopes can
only perceive on the moon's surface--which is, comparatively
speaking, but a few miles distant from us--objects of very great
size, while Jupiter is sixteen hundred times farther away from us
than the moon.

But it is known that Lexell's comet was very much demoralized by
Jupiter. It first came within the influence of that planet in 1767;
it lost its original orbit, and went bobbing around Jupiter until
1779, when it became entangled with Jupiter's moons, and then it lost
its orbit again, and was whisked off into infinite space, never more,
perhaps, to be seen by human eyes. Is it not reasonable to suppose
that an event which thus demoralized the comet may have caused it to