ons; the hoop will before long be made to rotate eccentrically, and
eventually be brought into destructive collision with the central
planet.

It was here that Laplace left the problem. Nothing could have been more
unsatisfactory than his result, though it was accepted for nearly half a
century unquestioned. He had shown that a weighted fine hoop may
possibly turn around a central attracting mass without destructive
changes of position, but he had not proved more than the bare
possibility of this, while nothing in the appearance of Saturn's rings
suggests that any such arrangement exists. Again, manifestly a multitude
of narrow hoops, so combined as to form a broad flat system of rings,
would be constantly in collision _inter se_. Besides, each one of them
would be subjected to destructive strains. For though a fine uniform
hoop set rotating at a proper rate around an attracting mass at its
centre would be freed from all strains, the case is very different with
a hoop so weighted as to have its centre of gravity greatly displaced.
Laplace had saved the theoretical stability of the motions of a fine
ring at the expense of the ring's power of resisting the strains to
which it would be exposed. It seems incredible that such a result
(expressed, too, very doubtingly by the distinguished mathematician who
had obtained it) should have been accepted so long almost without
question. There is nothing in nature in the remotest degree resembling
the arrangement imagined by Laplace, which indeed appears on _a priori_
grounds impossible. It was not claimed for it that it removed the
original difficulties of the problem; and it introduced others fully as
serious. So strong, however, is authority in the scientific world that
none ventured to express any doubts except Sir W. Herschel, who simply
denied that the two rings were divided into many, as Laplace's theory
required. As time went on and the signs of many divisions were at times
recognised, it was supposed that Laplace's reasoning had been justified;
and despite the utter impossibility of the arrangement he had suggested,
that arrangement was ordinarily described as probably existing.

At length, however, a discovery was made which caused the whole question
to be reopened.

On November 10, 1850, W. Bond, observing the planet with the telescope
of the Harvard Observatory, perceived within the inner bright ring a
feeble illumination which he was at a loss to understand. On the ne