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falling into a pool. Many of these are fifty
or sixty miles across, some more. They are
generally spoken of as resembling craters of
volcanoes, active or extinct, on the earth.
But some of those who have most fully stud-
ied the shapes of craters deny altogether
their resemblance to the circular objects on
the moon. These so-called craters, in many
parts, are seen to be closely grouped, espe-
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