of it was of a dark chocolate hue, strongly contrasting with the grey tone of the surrounding district.  This appearance lasted till the interior was more than half illuminated, gradually becoming less pronounced as the sun rose higher on the ring.  E. and S.E. of Landsberg is a number of ring-plains and craters well worthy of careful examination.  Five of the largest are surrounded by a glistening halo, and one (that nearest to the formation) and another (the largest of the group) have each a minute crater on their N. wall.

EUCLIDES.—­One of the most brilliant objects on the moon; a crater 7 miles in diameter, standing on a large bright area in the Mare Procellarum, E. of the Riphaean Mountains.  Its E. rim rises nearly 2000 feet above the bright depressed floor; on the W. there is a bright little unrecorded crater.

WICHMANN.—­This bright crater, about 5 miles in diameter, stands on a light area in Oceanus Procellarum, N.N.W. of Letronne and nearly due E. of Euclides.  Some distance on the N.E. are the relics of what appears once to have been a large enclosure, represented now by a few isolated mountains.

HERIGONIUS.—­A ring-plain, about 7 miles in diameter, in the Mare Procellarum, N.W. of Gassendi.  There is a small crater a few miles S.E. of it, among the bright little mountains which flank this formation.  Herigonius has a small central mountain, which is a good test for moderate apertures.

GASSENDI.—­One of the most beautiful telescopic objects on the moon’s visible surface, and structurally one of the most interesting and suggestive.  It is a walled-plain, 55 miles in diameter, of a distinctly polygonal type, the N.W. and S.W. sections being practically straight, while the intermediate W. section exhibits a slightly convex curvature, or bulging in towards the interior.  There is also much angularity about the E. side, which is evident at an early stage of sunrise.  The wall on the N. is broken through and almost completely wrecked by the great ring-plain Gassendi A. The bright eastern section of the border is in places very lofty, rising at one peak, N. of the well-known triangular depression upon it, to 9000 feet, and at other peaks on the same side still higher.  It is very low on the S., being only about 500 feet above the surface.  The floor, however, on the N. stands 2000 feet above the Mare Humorum.  On the W. there is a peak towering 4000 feet above the wall, which is here about 5000 feet above the floor, and 8000 feet above the Mare Nubium.  A very notable feature in connection with this formation is the little bright plain bounding it on the N.W., and separated from it by merely a narrow strip of wall.  This enclosure is flanked on the N.E. by Gassendi A, and on the S.W. and N.W. by a coarse winding ridge, running from the W. wall and terminating at a large irregular dusky depression.  Gaudibert has detected a crater near the S.E. edge of this bright plain, which includes also some oval mounds.  The interior of Gassendi