he E.
border of the great valley, more than 80 miles long, and in places fully
10 miles wide, which runs from S.S.W. to N.N.E. on the W. side of
Herschel, and bears a close resemblance to the well-known Ukert Valley.
Herschel _d_ is a large but shallow ring-plain on the E. of Herschel,
with a brilliant but smaller crater on the W. of it.

North of Herschel, on a plateau concentric with its outline, stands the
large polygonal ring-plain Herschel _a_, a formation of a very
interesting character, with a low broken wall, exhibiting many gaps, and
including some craters of a minute class. The largest of these stands on
the S.W. wall. Mr. W.H. Maw has detected some of these objects on the N.
side, both in connection with the border and beyond it.

FLAMMARION.--A large incomplete walled-plain N.E. of Herschel, open
towards the N., with a border rising about 3000 feet above the floor. The
brilliant crater, Mosting A, stands just outside the wall on the E.

PTOLEMAEUS.--Taking its very favourable position into account, this is
undoubtedly the most perfect example of a walled-plain on the moon's
visible superficies. It is the largest and most northerly component of
the fine linear chain of great enclosures, which extend southwards, in a
nearly unbroken line, to Walter. It exhibits a very marked departure from
circularity, the outline of the border approximating in form to a hexagon
with nearly straight sides. It includes an area of about 9000 square
miles, the greatest distance from side to side being about 115 miles. It
is, in fact, about equal in size to the counties of York, Lancashire, and
Westmorland combined; and were it possible for one to stand near the
centre of its vast floor, he might easily suppose that he was stationed
on a boundless plain; for, except towards the west, not a peak, or other
indication of the existence of the massive rampart would be discernible;
and even in this direction he would only see the upper portion of a great
mountain on the wall.

The border is much broken by gaps and intersected by passes, especially
E. and S., where there are several valleys connecting the interior with
that of Alphonsus. The loftiest portion of the wall, which includes many
crateriform depressions, is on the W., where one peak rises to nearly
9000 feet. Another on the N.E. is about 6000 feet above the interior. On
the N.W. is a remarkable crater-row, called, from its discoverer, "Webb's
furrow," running from a point a