0 feet above the
interior. It is very broad at its S. end, and its inner slope descends
with a gentle gradient to the floor. Towards the N., however, it rapidly
decreases in width, but apparently not in altitude, till near its bright
pointed N. extremity. Under a low sun, some long deformed crateriform
depressions may be seen on the slope, and a bright little crater on the
crest of the border near its N. end. The southern rampart is broken by
three large craters, and a fine valley, running some distance in a S.
direction, which diminishes gradually in width till it ultimately
resembles a cleft, and terminates at a small crater. The E. border is
very lofty and irregular, rising at the N. corner of the large triangular
formation, which is such a prominent feature upon it, to a height of 7000
feet, and at a point on the S.E. to considerably more than 8000 feet
above the floor. N. of the former peak it becomes much lower and
narrower, and is finally only represented by a very attenuated strip of
wall, hardly more prominent than the brighter portions of the border of
Stadius at sunrise, terminating at an obscure semi-ring-plain. Between
this and the pointed N. termination of the W. border there is a wide gap,
open to the north for a space of about 30 miles, appearing, except under
very oblique illumination, as smooth and as devoid of detail as the grey
surface of the Mare Nectaris itself. If, however, this interval is
observed at sunrise or sunset, it is seen to be not quite so
structureless as it appears under different conditions, for a number of
mounds and large humpy swellings, with low hills and craterlets, extend
across it, and occupy a position which we are justified in regarding as
the site of a section of the rampart, which, from some cause or other,
has been completely destroyed and overlaid with the material, whatever
this may be, of the Mare Nectaris. The floor of Fracastorius is, as
regards the light streaks and other features upon it, only second in
interest to those of Plato and Archimedes, and will repay systematic
observation. Between thirty and forty light spots and craters have been
recorded on its surface, most of them, as in these formations, being
situated either on or at the edges of the light streaks. On the higher
portion of the interior (near the centre) is a curious object consisting
apparently of four light spots, arranged in a square, with a craterlet in
the middle, all of which undergo (as I have