at can be compared with these crater
mountains, which indicate that the Moon was at one time a fiery globe
convulsed by internal forces which found an outlet in the numerous
volcanoes scattered over her surface.

The most remarkable of these volcanic mountains have been named after
distinguished men. (1) Copernicus is one of the most imposing; its
crater is 56 miles in diameter, and situated at its centre is a mountain
with six peaks 2,400 feet in height. The ring by which it is surrounded
rises 11,000 feet above the floor of the crater, and consists of
terraces believed to have been created by the partial congelation and
periodic subsidence of a lake of molten lava which occupied the enclosed
area.

(2) Tycho is one of the most magnificent and perfect of lunar volcanoes,
and is also remarkable as being a centre from which, when the Moon is
full, there radiates a number of bright streaks which extend across the
lunar surface, over mountain and valley, through ring and crater, for
many hundreds of miles. Their nature is unknown, and nothing resembling
them is found on the Earth. Tycho has a diameter of 50 miles and a
depth of 17,000 feet. The peak which rises from the floor of the crater
attains a height of 6,000 feet, and the rampart consists of a series of
terraces which give variety to the appearance of the inner wall. The
surface of the Moon round Tycho is honeycombed with small volcanoes.

(3) Clavius is one of the most extensive of the walled plains; it has a
diameter of 142 miles and an area of 16,500 square miles. The rocky
annulus which surrounds it is very lofty and precipitous, and at one
point reaches a height of 17,300 feet. Upwards of 90 craters have been
counted within this space, one of the peaks attaining to an elevation of
24,000 feet above the level floor of the plain. It is believed that the
lowest depths of this wild and precipitous region are never penetrated
by sunlight, they are so overshadowed by towering crag and fell which
intercept the solar rays; and, as there is no atmosphere to cause
reflection, they are consequently enveloped in perpetual darkness.

(4) Plato has a diameter of about 60 miles and an area of 2,700 square
miles; its central peak rises to a height of 7,300 feet. It has an
irregular rampart which is broken up into terraces averaging about 4,000
feet high; three cones, each with an elevation of from 7,000 to 9,000
feet, rest on its western border.

(5) Theophilus is the dee