BAILLY.—­One of the largest wall-surrounded plains on the moon, almost a “sea” in miniature, extending 150 miles from N. to S., and fully as much from W. to E. When caught at a favourable phase, it is, despite its position, especially worthy of scrutiny.  The rampart on the W., of the linear type, is broken by several bright craters.  On the S.W. two considerable overlapping ring-plains interfere with its continuity.  On the S.E. several very remarkable parallel curved valleys traverse the border.  The E. wall, which at one point attains a height of nearly 15,000 feet, is beautifully terraced.  The floor on the eastern side includes several ring-plains (some of which are of a very abnormal type), many ridges, and two delicate dark lines, crossing each other near the S. end, probably representing clefts.

LEGENTIL.—­A large walled-plain, close to the limb, S. of Bailly.

FOURTH QUADRANT

WEST LONGITUDE 90 deg.  TO 60 deg.

KASTNER.—­A large walled-plain at the S. end of the Mare Smythii, too near the limb for satisfactory observation.

MACLAURIN.—­The principal member of a group of irregular ring-plains on the W. side of the Mare Foecunditatis, a little S. of the lunar equator.  Schmidt shows no details within it, except a small crater on the E. side of the floor.

WEBB.—­A ring-plain E. of Maclaurin, about 14 miles in diameter, with a dusky floor, enclosed by a bright rim, on the N.E. side of which there is a small crater.  Schmidt seems to have overlooked the central hill.

LANGRENUS.—­This noble circumvallation, the most northerly of the meridional chain of immense walled-plains, extending for more than 600 miles from near the equator to S. lat. 40 deg., would, but for its propinquity to the limb, rank with Copernicus (which in many respects it resembles) among the most striking objects on the surface of the moon.  Its length is about 90 miles from N. to S., and its breadth fully as much.  In shape it approximates very closely to that of a foreshortened regular hexagon.  The walls, which at one point on the E. rise to an altitude of nearly 10,000 feet, are continuous, except on this side, where they are broken by the interference of an irregular depression, and on the extreme S., where they are intersected by cross-valleys.  Within, the terraces are remarkably distinct, and the intervening valleys strongly marked.  The brilliant compound central mountain rises at its loftiest peak to a height of more than 3000 feet.  On the N. of it is an obscure circular ring, which may possibly merely represent a fortuitous combination of ridges, though it has all the appearance of a modified ring-plain.  On the Mare, some distance N.E. of the formation, is a group of three ring-plains, with two small craters (associated with a ridge) on the N. of them.  Two of the more westerly of these objects have prominent central mountains, and the third a very dark interior.  At least three bright streaks originate on the E. flank of Langrenus, which, diverging widely, traverse the Mare Foecunditatis.