DOPPELMAYER.—­Under a high sun this large ring-plain, 40 miles in diameter, resembles a great bay open to the N.W., without a trace of detail to break the monotony of the surface on the side facing the Mare Humorum.  When, however, it is viewed under oblique morning illumination, a low broad ridge is easily traceable, extending across the opening, indicating the site of a ruined wall.  There is an isolated mountain at the S.W. end of this, which casts a fine spire of shadow across the floor at sunrise.  The interior contains a massive bright central mountain and several little hills.  The crest of the wall on the E. is much broken.

FOURIER.—­A large ring-plain, 30 miles in diameter, S.W. of Vieta, with a border rising at a peak on the W. more than 9000 feet above the floor, There are two craters on the outer slope of the N.W. wall, a prominent crater on the S. wall, and (according to Schmidt) a small central crater on the floor, which I have not seen.  In the region between Fourier and Vieta there are three ring-plains, two (the more westerly) standing side by side, and on the W., towards the Mare, are two others much larger, that nearer to Fourier being traversed by one cleft, and the other by two clefts, crossing near the centre of the floor.

CLAUSIUS.—­A small bright ring-plain in an isolated position N.W. of Schickard, with a crater both on its N. and S. rim, and a faint central hill.

LACROIX.—­A ring-plain 20 miles in diameter, N. of Schickard.  It has a prominent central mountain.

SCHICKARD.—­One of the largest wall-surrounded plains on the visible surface of the moon, extending about 134 miles from N. to S., and about the same from E. to W., enclosing a nearly level area, abounding in detail.  Its border, to a great extent linear, is very irregular, and much broken by the interposition of small ring-plains and craters, and on the N. by cross-valleys.  Its general height is about 4000 feet, the loftiest peak on the W. wall rising to more than 9000 feet above the floor.  The inner slopes of this vast rampart are very complex, especially on the E., where many terraces and depressions may be seen under suitable illumination.  There are three large ring-plains in the interior, all of them S. of the centre; and at least five smaller ones near the inner foot of the E. wall, which can only be well observed when libration is favourable.  The two more easterly of the large ring-plains are connected by a cleft, and there are several short clefts and crater-rows associated with the smaller ring-plains.  On the N. side of the area is a number of minute craters.  The floor is diversified by two large dark markings—­an oblong patch on the S.W. side, abutting on the wall, being the more remarkable; and a dusky area, occupying a great portion of the N. part of the floor, and extending up to the N. border.  This is traversed by a light streak running from N. to S., which is the site of a row of minute craters.