seen the banks with which it appears to be bounded (at any rate within
the formation), standing out as fine bright parallel lines amid the
shadow. On reaching the E. wall, it turns somewhat more to the N.,
becomes still coarser and more irregular in breadth, and ultimately
expands into a wide valley on the N.E. It is connected with the Ariadaeus
cleft by a branch which leaves the latter at an acute angle on the plain
E. of Silberschlag, and joins it about midway between its origin N. of
Agrippa and Hyginus. It is also probably joined to the Triesnecker system
by one or more branches E. of Hyginus.

On May 27, 1877, Dr. Hermann Klein of Cologne discovered, with a 5 1/2
inch Plosel dialyte telescope, a dark apparent depression without a rim
in the Mare Vaporum, a few miles N.W. of Hyginus, which, from twelve
years' acquaintance with the region, he was certain had not been visible
during that period. On the announcement of this discovery in the
_Wochenschrift fur Astronomie_ in March of the following year, the
existence of the object described by Dr. Klein was confirmed, and it was
sedulously scrutinised under various solar altitudes. To most observers
it appeared as an ill-defined object with a somewhat nebulous border,
standing on an irregularly-shaped dusky area, with two or more small dark
craters and many low ridges in its vicinity. A little E. of it stands a
curious spiral mountain called the Schneckenberg. The question as to
whether Hyginus N. (as the dusky spot is called) is a new object or not,
cannot be definitely determined, as, in spite of a strong case in favour
of it being so, there remains a residuum of doubt and uncertainty that
can never be entirely cleared away. After weighing, however, all that can
be said "for and against," the hypothesis of change seems to be the most
probable.

UKERT.--This bright crater, 14 miles in diameter, situated in the region
N.E. of Triesnecker, is surrounded by a very complicated arrangement of
mountains; and on the N. and W. is flanked by other enclosures. It has a
distinct central mountain. Its most noteworthy feature is the great
valley, more than 80 miles long, which extends from N.E. to S.W. on the
E. side of it. This gorge is at least six miles in breadth, of great
depth, and is only comparable in magnitude with the well-known valley
which cuts through the Alps, W. of Plato. A delicate cleft, not very
clearly traceable as a whole, begins near its N. end, and terminate