little east of the ring-plain Arago, where there are two nearly equal
circular mounds, at least ten miles in diameter, resembling tumuli seen
from above. Similar, but more irregular, objects of a like kind are very
plentiful in many other quarters.

It is a suggestive peculiarity of many of the lunar ridges, both on the
Maria and elsewhere, that they are very generally found in association
with craters of every size. Illustrations of this fact occur almost
everywhere. Frequently small craters are found on the summits of these
elevations, but more often on their flanks and near their base. Where a
ridge suddenly changes its direction, a crater of some prominence
generally marks the point, often forming a node, or crossing-place of
other ridges, which thus appear to radiate from it as a centre. Sometimes
they intrude within the smaller ring-mountains, passing through gaps in
their walls as, for example, in the cases of Madler, Lassell, &c. Various
hypotheses have been advanced to account for them. The late Professor
Phillips, the geologist, who devoted much attention to the telescopic
examination of the physical features of the moon, compared the lunar
ridges to long, low, undulating mounds, of somewhat doubtful origin,
called "kames" in Scotland, and "eskers" in Ireland, where on the low
central plain they are commonly found in the form of extended banks
(mainly of gravel), with more or less steep sides, rising to heights of
from 20 to 70 feet. They are sometimes only a few yards wide at the top,
while in other places they spread out into large humps, having circular
or oval cavities on their summits, 50 or 60 yards across, and as much as
40 feet deep. Like the lunar ridges, they throw out branches and exhibit
many breaches of continuity. By some geologists they are supposed to
represent old submarine banks formed by tidal currents, like harbour
bars, and by others to be glacial deposits; in either case, to be either
directly or indirectly due to alluvial action. Their outward resemblance