ervers 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
addition to those already referred to, a number of mysterious dark spots
were discovered by Schmidt in the dusky region about midway between
Copernicus and Gambart, which Klein describes as perforated like a sieve
with minute craters. A short distance south-west of Copernicus stands a
bright crater-cone surrounded by a grey nimbus, which may be classed with
these objects. It is well seen under a high light, as indeed is the case
with most of these features.

CRATERLETS, CRATER-PITS.--To a great extent the former term is needless
and misleading, as the so-called craters merge by imperceptible
gradations into very minute objects, as small as half a mile in diameter,
and most probably, if we could more accurately estimate their size, still
less. The crater-pit, however, has well-marked peculiarities which
distinguish it from all other types, such as the absence of a
distinguishable rim and extreme shallowness. They appear to be most
numerous on the high-level plains and plateaus in the south-western
quadrant, and may be counted by hundreds under good atmospheric
conditions on the outer slopes of Walter, Clavius, and other large
enclosures. In these positions they are often so closely aggregated that,
as Nasmyth remarks, they remind one of an accumulation of froth. Even in
an 8 1/2 inch reflector I have frequently seen the outer slope of the
large ring-plain on the north-western side of Vendelinus, so perforated
with these objects that it resembled pumice or vesicul