Under a high sun they generally appear as white spots, more or less ill-
defined, as on the floors of Archimedes, Fracastorius, Plato, and many
other formations, which include a great number, all of which are probably
crater cones, although only a few have been seen as such. It is a
significant fact that in these situations they are always found to be
closely associated with the light streaks which traverse the interior of
the formations, standing either on their surface or close to their edges.
The instrumental and meteorological requirements necessary for a
successful scrutiny of the smallest type of these features, are beyond
the reach of the ordinary observer in this country, as they demand direct
observation in large telescopes under the best atmospheric conditions.

Some years ago Dr. Klein of Cologne called attention to some very
interesting types of crater-cones, which may be found on certain dark or
smoky-grey areas on the moon. These, he considers, may probably represent
active volcanic vents, and urges that they should be diligently examined
and watched by observers who possess telescopes adequate to the task. The
most noteworthy examples of these objects are in the following
positions:--(1) West of a prominent ridge running from Beaumont to the
west side of Theophilus, and about midway between these formations; (2)
in the Mare Vaporum, south of Hyginus; (3) on the floor of Werner, near
the foot of the north wall; (4) under the east wall of Alphonsus, on the
dusky patch in the interior; (5) on the south side of the floor of Atlas.
I have frequently described elsewhere with considerable detail the
telescopic appearance of these features under various phases, and have
pointed out that though large apertures and high powers are needed to see
these cones to advantage, the dusky areas, easily traced on photograms,
might be usefully studied by observers with smaller instruments, as if
they represent the _ejecta_ from the crater-cones which stand upon them,
changes in their form and extent could very possibly be detected. In