here when he
first began to observe, they really did decline, and they really
disappeared; but this disappearance was only for a time--they again came
into view. They were then subjected to ceaseless examination, until
gradually their nature became unfolded. With increased telescopic power
it was found that the two bodies which Galileo had described as globes
on either side of Saturn were not really spherical--they were rather two
luminous crescents with the concavity of each turned towards the central
globe. It was also perceived that these objects underwent a remarkable
series of periodic changes. At the beginning of such a series the planet
was found with a truly circular disc. The appendages first appeared as
two arms extending directly outwards on each side of the planet; then
these arms gradually opened into two crescents, resembling handles to
the globe, and attained their maximum width after about seven or eight
years; then they began to contract, until after the lapse of about the
same time they vanished again.

The true nature of these objects was at length discovered by Huyghens in
1655, nearly half a century after Galileo had first detected their
appearance. He perceived the shadow thrown by the ring upon the globe,
and his explanation of the phenomena was obtained in a very
philosophical manner. He noticed that the earth, the sun, and the moon
rotated upon their axes, and he therefore regarded it as a general law
that each one of the bodies in the system rotates about an axis. It is
true, observations had not yet been made which actually showed that
Saturn was also rotating; but it would be highly, nay, indeed,
infinitely, improbable that any planet should be devoid of such
movement. All the analogies of the system pointed to the conclusion that
the velocity of rotation would be considerable. One satellite of Saturn
was already known to revolve in a period of sixteen days, being little
more than half our month. Huyghens assumed--and it was a most reasonable
assumption--that Saturn in all probability rotated rapidly on its axis.
It was also to be observed that if these remarkable appendages were
attached by an actual bodily connection to the planet they must rotate
with Saturn. If, however, the appendages were not actually attached it
would still be necessary that they should rotate if the analogy of
Saturn to other objects in the system were to be in any degree
preserved. We see satellites near Jupiter whic