the W. wall, are seen better than under any other
conditions. The border is loftiest on the E., where the ring-plain
Wrottesley abuts on it. It rises at this point to nearly 11,000 feet,
while on the opposite side it nowhere greatly exceeds 6000 feet above the
interior. The terraces, however, on the W. are much more numerous, and,
with the associated valleys, render this section of the wall one of the
most striking objects of its class. The N. border is conspicuously broken
by the many valleys from the region S. of Vendelinus, which run up to and
traverse it. On the S., also, it is intersected by gaps, and in one place
interrupted by a large crater. There is a remarkable bifurcation of the
border S. of Wrottesley. A lower section separates from the main rampart
and, extending to a considerable distance S.E. of it, encloses a wide and
comparatively level area which is crossed by two short clefts. The
central mountains of Petavius, rising at one peak to a height of nearly
6000 feet above the floor, form a noble group, exceeding in height those
in Gassendi by more than 2000 feet. The convexity of the interior is such
that the centre of it is about 800 feet higher than the margin, under the
walls; a protuberance which would, nevertheless, be scarcely remarked _in
situ_, as it represents no steeper gradient than about 1 in 300 on any
portion of its superficies. The great cleft, extending from the central
mountains to the S.E. wall, and perhaps beyond, was discovered by
Schroter on September 16, 1788, and can be seen in a 2 inch achromatic.
In larger instruments it is found to be in places bordered by raised
banks.

WROTTESLEY.--A formation, about 25 miles in diameter, closely associated
with the E. wall of Petavius, the shape of which it has clearly modified.
Its border on the E., of the linear type, rises nearly 9000 feet above a
light interior, where there is a small bright central mountain and some
mounds. There is a prominent valley running along the inner slope of the
W. wall.

PALITZSCH.--If this extraordinary formation is observed when the moon is
about three days old, it resembles a great trough, or deep elongated
gorge flanking the W. wall of Petavius, though it is a true ring-plain,
albeit of a very abnormal type, about 60 miles in length and 20 miles in
breadth, with a somewhat dusky interior. On the outer slope of its W.
wall is a bright ring-plain with a lofty border and a central mountain.

HASE.--An irregula