minator" is the boundary between the lighted and the dark
portion of the disc.

[5] Those who have seen the undercliff in the Isle of Wight will be able
to form some idea of the terraces of the lunar ring-mountains, as they
are very similar formations.

[6] This is the case as regards separate satellites; but it may be
pointed out that a similar thing must occur in regard to the rings of
Saturn. The rings are composed of swarms of satellites so small that
they can only be termed particles, and these particles at the inner edge
of the "crape ring" revolve round Saturn in 5 hours and 33 minutes, the
inner edge of the ring being only about 47,000 miles from the centre of
the planet. The planet itself revolves on its axis in 10-1/4 hours.
Thus, an immense number of these minute satellites must revolve round
the planet in less time than it takes the planet to make one rotation.
It is calculated that the particles in the outer edge of the next ring
complete one revolution round the planet in 14 hours and 28 seconds.

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