s in extreme length, of very
abnormal shape, on the E. side of the Mare, N.N.E. of Theophilus, with a
wall rising at a peak on the E. to a height of more than 7000 feet above
a dusky floor, which does not apparently contain any detail. A small
crater breaks the uniformity of the border on the W. Beyond the wall on
the S.E. lies the fine bright crater Hypatia A, with another less
prominent adjoining it on the S.W.

THEOPHILUS.--The most northerly of three of the noblest ring-mountains on
the visible surface of the moon, situated on the N.E. side of the Mare
Nectaris. It is nearly 64 miles in diameter, and is enclosed by a mighty
rampart towering above the floor at one peak on the W. to the height of
18,000 feet, and at two other peaks on the opposite side to nearly 16,000
and 14,000. The border, though appearing nearly circular with low powers,
is seen, under greater magnification, to be made up of several more or
less linear sections, which give it a polygonal outline. It is
prominently terraced within, the loftier terraces on the W. rising nearly
to the height of the crest of the wall, and including several craters and
elongated depressions. On the W. _glacis_ is a row of large inosculating
craters; and near its foot, S.E. of Madler, a short unrecorded rill-
valley. The magnificent bright central mountain is composed of many
distinct masses surmounted by lofty peaks, one of which is about 6000
feet above the floor, and covers an area of at least 300 square miles.
Except a distinct crater on the S.W. quarter, this appears to be the only
object within the ring.

CYRILLUS.--The massive border of Theophilus partially overlaps the N.W.
side of this great walled-plain, which is even more complex than that of
its neighbour, and far more irregular in form, exhibiting many linear
sections. Its crest on the S.E. is clearly inflected towards the
interior, a peculiarity that has already been noticed in connection with
Copernicus and some other objects. On the inner slope of this wall there
is a large bright crater, in connection with which have been detected two
delicate rills extending to the summit. I have not seen these, but one of
the crater-rows shown by Schmidt, between this crater and the crest, has
often been noted. The N.E. wall is very remarkable. It appears to be
partially wrecked. If observed at an early stage of sunrise, a great
number of undulating ridges and rows of hillocks will be seen crossing
the region E. of T