ans so striking an object as a glance at its representation on a chart
of the moon would lead one to expect; for the border, in nearly every
part of it, bears unmistakable evidence of wreck and ruin, its continuity
being interrupted by depressions, transverse valleys, and gaps, and it
nowhere attains a great altitude. This imperfect enclosure extends 97
miles from N. to S., and about 88 miles from E. to W., and in shape
approximates to that of a rhombus with curved sides. One of the most
prominent bright craters on its border is Hipparchus G, on the W.
Another, of about the same size, is Hipparchus E, on the N. of Horrocks.
On the E. there is a moderately bright crater, Hipparchus F; and S. of
this, on the same side, two others, K and I. The interior is crossed by
many ridges, and near the centre includes the relics of a low ring,
traversed by a narrow rill-like valley. Schmidt shows a cleft running
from F across the floor to the S. border.

[A valuable monograph of Hipparchus, by Mr. W.B. Birt, was published in
1870.]

HORROCKS.--This fine ring-plain, 18 miles in diameter, stands on the N.
side of the interior of Hipparchus, close to the border. It has a
continuous wall, rising on the E. to a height of nearly 8000 feet above
the interior, and a distinct central mountain.

HALLEY.--A ring-plain, 21 miles in diameter, on the S.W. border of
Hipparchus, with a bright wall, rising at one point on the E. to a height
of 7500 feet above the floor, which is depressed about 4000 feet below
the surface. Two craterlets on the floor, one discovered by Birt on
Rutherfurd's photogram of 1865, and the other by Gaudibert, raised a
suspicion of recent lunar activity within this ring. A magnificent
valley, shown in part by Schmidt as a crater-row, runs from the S. of
Halley to the W. side of Albategnius.

HIND.--A ring-plain, 16 miles in diameter, a few miles W. of Halley, with
a peak on its E. wall 10,000 feet above the floor. The border is broken
both on the S.E. and N.E. by small craters.

[Horrocks, Halley, and Hind may be regarded as strictly belonging to
Hipparchus.]

ALBATEGNIUS.--A magnificent walled-plain, 65 miles in diameter, adjoining
Hipparchus on the S., surrounded by a massive complex rampart,
prominently terraced, including many depressions, and crossed by several
valleys. It is surmounted by very lofty peaks, one of which on the N.E.
stands nearly 15,000 feet above the floor. The great ring-plain
Albategnius A, 28