rater on a dark surface, with
companions, referred to under the Third Quadrant.

Encke. There is a light-surrounded crater S. of this.

Kepler. A noted ray-centre. It is surrounded by an extensive halo,
especially well developed on the E., across the Mare Procellarum.

Bessarion. Two bright craters: the more northerly is prominently
light-surrounded, while its companion is less conspicuously so.

Aristarchus.--The most conspicuous bright centre on the moon, the
origin of a complicated ray-system.

Delisle. S. of this formation there is a tolerably bright spot on the
site of some hills.

Timaeus. A ray-centre.

Euler. Feeble halo with streaks.

Galileo. Between this and Reiner is a curious bright formation with short
rays, referred to in the Catalogue, under Reiner.

Cavalerius. A light streak originating in the W. wall, and extending on
to the Oceanus Procellarum.

Olbers. A considerable ray-system, but seldom distinctly visible.

Lichtenberg. Faintly light-surrounded.

THIRD QUADRANT.

Tycho. The largest and best known system on the visible surface.

Zuchius. A remarkable ray-system, but one which is only well seen when
libration is favourable.

Bailly. N. of the centre of this great enclosure are two very distinct
radiating streaks.

Schickard. Four conspicuous light spots, probably craters, on the S.E.

Byrgius A. A brilliant ray-centre, most of the rays trending eastward
from a nimbus.

Hainzel. There are several bright spots E. of this formation.

Mersenius. Two or three light-rays originate from a point on the W.
rampart.

Mersenius C. A light-surrounded crater with short rays.

Grimaldi. There are three bright spots on the W. wall.

Damoiseau. A light-surrounded crater W. of Damoiseau, E. long. 58 deg.,
S. lat. 6 deg.

Flamsteed C. A light-surrounded crater on a dark surface.

Lubieniezky A. Crater with halo on a dark surface.

Lubieniezky F. Crater with halo on a dark surface.

Lubieniezky G. Crater with halo on a dark surface.

Birt _a_. A light-surrounded crater.

Landsberg. E. of Landsberg, four light-surrounded craters, forming
with Landsberg A (in the Second Quadrant) an interesting group.

Lohrmann A. A light-surrounded crater, with a light area a few miles N.
of it. S. lat. 1 deg., E. long. 61 deg.

Euclides. Has a conspicuous nimbus with traces of rays, a typical
example.

Guerike. There is a crater, with nimbus, W. of this, in E. long. 12 deg.,
S. lat. 11 deg. 5