-the
whole forming a V-shaped arrangement. On the S. there is a narrow break
in the wall, and the S.W. section of it seems to overlap and extend some
distance beyond the S.E. section. The border on the S.W. is remarkable
for the great width of its _glacis_. Eratosthenes exhibits a marked
departure from circularity, especially on the E., where the wall consists
of two well-marked linear sections, with an intermediate portion where
the crest for 20 miles or more bends inwards or towards the centre. From
the S.E. flank of this formation extends towards the W. side of Stadius
one of the grandest mountain arms on the moon's visible surface, rising
at one place 9000 feet, and in two others 5000 and 3000 feet respectively
above the Mare Imbrium. If this magnificent object is observed when the
morning terminator falls a little E. of Stadius, it affords a spectacle
not easily forgotten. I have often seen it at this phase when its broad
mass of shadow extended across the well-known crater-row W. of
Copernicus, some of the component craters appearing between the spires of
shade representing the loftiest peaks on the mountain arm. There is a
prominent little crater on the crest of the arm between two of the peaks,
and another on the plain to the west.

STADIUS.--An inconspicuous though a very interesting formation, 43 miles
in diameter, W. of Copernicus, with a border scarcely exceeding 200 feet
in height. Hence it is not surprising that it was for a long time
altogether overlooked by Madler. Except as a known object, it is only
traceable under very oblique illumination, and even then some attention
is required before its very attenuated wall can be followed all round. It
is most prominent on the W., where it apparently consists of a S.
extension of the Eratosthenes mountain-arm, and is associated with a
number of little craters and pits. This is succeeded on the S.W. by a
narrow strip of bright wall, and on the S. by a section made up of a
piece of straight wall and a strip curving inwards, forming the S. side.
On the E. the border assumes a very ghostly character, and appears to be
mainly defined by rows of small depressions and mounds. On the N.E., N.,
and N.W. it is still lower and narrower; so much so, that it is only for
an hour or so after sunrise or before sunset that it can be traced at
all. On every side, with the exception of the curved piece on the S., the
wall consists of linear sections. The interior contains a great n