reflects light to a greater extent than that on similar formations;
indeed it appears so bright that when the moon is new and the whole of
this part of the disc is dark, Aristarchus can still be seen with a
telescope, and this gave rise in the past to the idea that it was a
volcano in actual eruption. The explanation is, however, more prosaic,
because the mountain is really brought into view by earthshine on its
bright covering. When the moon is new the earth is almost fully lighted
on the side toward the moon, and sheds a faint light on the dark portion
of its disc, thus producing the phenomenon known as 'the old moon in the
new moon's arms.'

"Close to Aristarchus you will notice another ring-plain, which is
called Herodotus, about twenty-three miles in diameter, with a floor
7000 feet depressed; but this formation is not nearly so bright as its
neighbour. That high plateau between them is notable on account of the
T-shaped cleft in it, which runs into that other long zig-zag cleft (in
some parts two miles wide and 1600 feet in depth), whose direction
changes abruptly several times in its length of over one hundred miles.

"Turning from this towards the south-west you will see the most majestic
formation to be found upon the moon--the great ring-plain called
'Copernicus,' after the founder of our present system of astronomy. It
is about sixty miles in diameter, only roughly circular in shape, and as
it stands isolated upon the great ocean-bed it is most favourably
situated for observation. A large number of very high ridges, separated
by deep valleys, radiate from it in all directions to a distance of
hundreds of miles, presenting the appearance of a grand system of
buttresses to the mountain walls. These walls are high, and contain a
very large number of peaks which, when seen through the telescope as
they catch the sunlight, look like a string of bright pearls shining on
the border of the ring. A peak on one side is 12,000 feet in altitude,
on the other side is one only 1000 feet lower, whilst, rising from near
the central part of the floor, are no less than five small mountain
peaks. Owing to its size, brightness, and isolated position, this
splendid ring-mountain can be seen from the earth without the aid of a
glass; but even a field-glass will reveal much in this and similar
formations which cannot be detected by the unaided eye.

"The Rev. T.W. Webb has termed Tycho, in the southern hemisphere, 'the
Metropolit