CENSORINUS.—A brilliant little crater, with very bright surroundings, in the Mare Tranquilitatis, nearly on the moon's equator, in W. long. 32 deg. 22 min. Another smaller but less conspicuous crater adjoins it on the W. On the Mare to the S. extends a delicate cleft which trends towards the Sabine and Ritter rill system.
CAPELLA.—Forms with Isodorus, its companion on the E. (which it partially overlaps), a very noteworthy object. It is about 30 miles in diameter, with finely terraced walls, broken on the S.W. by broad intrusive rill-valleys. The rampart on the N.E. is also cut through by a magnificent valley, which extends for many miles beyond the limits of the formation. There is a fine central mountain, on which M. Gaudibert discovered a crater, the existence of which has been subsequently verified by Professor Weinek on a Lick observatory negative.
ISODORUS.—The rampart of this fine ring-plain, which is of about the same size as Capella, rises at a peak on the W. to a height of more than 13,000 feet above the interior, which, except a small bright crater at the foot of the E. wall and a smaller one adjoining it on the N., contains no detail. The region between Isodorus and the equator includes many interesting objects, among them Isodorus b, an irregular formation open towards the N., and containing several craters.
BOHNENBERGER.—A ring-plain about 22 miles in diameter, situated on the W. side of the Mare Nectaris, under the precipitous flanks of the Pyrenees, whose prominent shadows partially conceal it for many hours after sunrise. The circular border is comparatively low, and, except on the N., continuous. Here there is a gap, and on the W. of it an intrusive mass of rock. From its very peculiar shadow at sunrise, the wall on the E. appears to be very irregular. The club-shaped central mountain is of considerable size, but not conspicuous. S. of Bohnenberger stands the very attenuated ring, Bohnenberger A. It is of about the same diameter, has a large deep crater on its N. rim, and a smaller one, distinguished with difficulty, on its S.E. rim. On the N. of Bohnenberger there is a bright little ring-plain connected with the formation by a lofty ridge, under the E. flank of which Schmidt shows a crater-chain. An especially fine cleft originates on the E. side of this crater, which, following an undulating course over the Mare Nectaris, terminates at Rosse, N. of Fracastorius.
TORRICELLI.—A remarkable little formation in the Mare Tranquilitatis, N. of Theophilus, consisting of two unequal contiguous craters ranging from W. to E., whose partition wall has nearly disappeared, so that, under a low sun, when the interior of both is filled with shadow, the pair resemble the head of a javelin. The larger, western, ring is about 10 miles in diameter, and the other about half this size. There is a gap in the W. wall of the first, and a long spur projecting from its S. side; and a minute crater on the S. border of the smaller object. Torricelli is partially enclosed on the S. by a circular arrangement of ridges. There is a delicate cleft running in a meridional direction on the Mare, E. of the formation, and another on the N., running from W. to E.
HYPATIA.—A ring-plain, about 30 miles 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 Theophilus. They resemble a consolidated stream of "ropy" lava which has flowed through and over the wall and down the glacis. The arrangement of the ridges within Cyrillus is very noteworthy, as is also the triple mountain near the centre of the floor. The fine curved cleft thereon traverses the W. side, sweeping round the central mountains, and then turning to the south. I have only occasionally seen it in its entirety. There are also two oblong dark patches on the S. side of the interior. The S. wall of Cyrillus is broken by a narrow pass opening out into a valley situated on the plateau which bounds the W. side of the oblong formation lying between it and Catherina, and overlooking a curious shallow square-shaped enclosure abutting on the S.W. side of Cyrillus.
CATHERINA.—The largest of the three great formations: a ring-plain with a very irregular outline, extending more than 70 miles in a meridional direction, and of still greater width. The wall is comparatively narrow and low on the N.E. (8000 feet above the floor), but on the N.W. it rises to more than double this height, and is broken by some large depressions. The inner slope on the S.E. is very gentle, and includes two bright craters, but exhibits only slight indications of terraces. The most remarkable features on an otherwise even interior are the large low narrow ring (with a crater within it), occupying fully a third of the area of the floor, and a large ring-plain on the S. side.
MADLER.—The interest attaching to this formation is not to be measured by its size, for it is only about 20 miles in diameter, but by the remarkable character of its surroundings. Its bright regular wall, rising 6000 feet on the E. and only about half as much on the W., above a rather dark interior, is everywhere continuous, except at one place on the N. Here there is a narrow gap (flanked on the E. by a somewhat obscure little crater) through which a curious bent ridge coming up from the N. passes, and, extending on to the floor, expands into something resembling a central mountain. Under a high sun Madler has a very peculiar appearance. The lofty E. wall is barely perceptible, while the much lower W. border is conspicuously brilliant; and the E. half of the floor is dark, while the remainder, with two objects representing the loftier portions of the intrusive ridge, is prominently white. Under an evening sun, with the terminator lying some distance to the W., a very remarkable obscure ring with a low border, a valley running round it on the W. side, and two large central mounds, may be easily traced. This object is connected with Madler by what appears to be under a higher sun a bright elbow-shaped marking, in connection with which I have often suspected a delicate cleft. Between the obtuse-angled bend of this object and the W. wall of Madler, two large circular dark spots may be seen under a high sun; and on the surface of the Mare N. of it, a great number of delicate white spots.