e fused by the friction and changed to dust. Larger
ones are partially fused, and often split into fragments in the upper
air. The moon, having no atmosphere, is quite unprotected in this
respect; and meteorites moving at enormous speeds, probably over forty
miles in a second, travel unchecked and unaltered in character until
they strike the lunar surface. It is estimated that immense numbers
constantly enter our atmosphere and are destroyed; but the moon must be
continually exposed to bombardment by meteorites of considerable size.

"Many of our ships have been lost at sea in calm weather, and their fate
has remained a profound mystery; but it is not at all improbable that
some of them have been destroyed by large meteorites, for several
instances are recorded of ships having very narrow escapes from these
dangerous missiles from outer space."

Passing on towards the south-west, we had a long look at the magnificent
formation named Tycho. It is a ring-plain nearly fifty-six miles in
diameter, the mountain walls having some peaks over 17,000 feet in
height. I drew their attention to the long bright ray-streaks which
radiate in all directions for many hundreds of miles from the
neighbourhood of this formation, to which I alluded when we had been
looking at the rays from Proclus. Tycho and these bright streaks can be
seen from the earth when the moon is full without the aid of a
telescope, if one possesses good eyesight.

An enormous number of ring-plains and ring-mountains exists all over the
southern half of the moon's disc; in many cases there are rings within
rings, and others where they have overlapped or cut into previously
formed rings.

Moving almost due south, we passed the large but partially ruined walled
plain known as Maginus. This ring has a floor which is no less than
14,000 feet below the lunar surface. We then arrived at that favourite
object for telescopic observers which is named Clavius. This is an
enormous ring-plain, being over 142 miles in diameter, and encloses an
area of 16,000 square miles, thus being half the area of Scotland. It
has a very depressed floor, and some of the mountains are 16,000 to
17,000 feet in altitude.

Farther on, and close to the south pole, we saw the very deepest of the
lunar walled plains, which is named after Newton, who possessed probably
the deepest intellect of any of our astronomers. A smaller formation
south of Plato was originally named after him, but was not