AGRIPPA.—­A ring-plain 28 miles in diameter on the N. of the last, with a terraced border rising to a height of between 7000 and 8000 feet above the floor, which contains a large bright central mountain and two craters on the S. The shape of this formation deviates very considerably from circularity, the N. wall, on which stands a small crater, being almost lineal.  On the W., at a distance of a few miles, runs the prominent mountain range, extending northwards nearly up to the E. flank of Julius Caesar, which bounds the E. side of the great Ariadaeus plain.  Between this rocky barrier and Agrippa is a very noteworthy enclosure containing much minute detail and a long straight ridge resembling a cleft.  A few miles N. of Agrippa stands a small crater; at a point W. of which the Hyginus cleft originates.

SILBERSCHLAG.—­A very brilliant crater, 8 or 9 miles in diameter, connected with the great mountain range just referred to.  The Ariadaeus cleft cuts through the range a few miles N. of it.  This neighbourhood at sunrise presents a grand spectacle.  With high powers under good atmospheric conditions, the plain E. of the mountains is seen to be traversed by a number of shallow winding valleys, trending towards Agrippa, and separated by low rounded hills which have all the appearance of having been moulded by the action of water.

BOSCOVICH.—­This is not a very striking telescopic object under any phase, on account of its broken, irregular, and generally ill-defined border.  It is, however, remarkable as being one of the darkest spots on the visible surface:  in this respect a fit companion to Julius Caesar, its neighbour on the W. Schmidt shows some ridges within it.

RHAETICUS.—­A very interesting formation, about 25 miles in diameter, situated near the lunar equator, with a border intersected by many passes.  A deep rill-like valley winds round its eastern glacis, commencing on the S. at a small circular enclosure standing at the end of a spur from the wall; and, after crossing a ridge W. of a bright little crater on the N. of the formation, apparently joins the most easterly cleft of the Triesnecker system.  A cleft traverses the N. side of the floor of Rhaeticus, and extends across the plain on the E. as far as the N. side of Reaumur.

TRIESNECKER.—­Apart from being the centre of one of the most remarkable rill-systems on the moon, this ring-plain, though only about 14 miles in diameter, is an object especially worthy of examination under every phase.  At sunrise, and for some time afterwards, owing to the superior altitude of the N.W. section of the wall, a considerable portion of the border on the N. and N.E. is masked by its shadow, which thus appears to destroy its continuity.  On more than one occasion, friends, to whom I have shown this object under these conditions, have likened it to a breached volcanic cone, a comparison which at a later stage is seen to be very inappropriate.  The rampart is terraced within, and exhibits many