telescope, even of moderate power, the
surface of the moon presents a scene of astonishing complexity, in which
strangeness, beauty, and grandeur are all combined. The half of the moon
turned earthward contains an area of 7,300,000 square miles, a little
greater than the area of South America and a little less than that of
North America. Of these 7,300,000 square miles, about 2,900,000 square
miles are occupied by the gray, or dusky, expanses, called in lunar
geography, or selenography, _maria_--i.e., "seas." Whatever they may
once have been, they are not now seas, but dry plains, bordered in many
places by precipitous cliffs and mountains, varied in level by low
ridges and regions of depression, intersected occasionally by immense
cracks, having the width and depth of our mightiest river canons, and
sprinkled with bright points and crater pits. The remaining 4,400,000
square miles are mainly occupied by mountains of the most extraordinary
character. Owing partly to roughness of the surface and partly to more
brilliant reflective power, the mountainous regions of the moon appear
bright in comparison with the dull-colored plains.

Some of the lunar mountains lie in long, massive chains, with towering
peaks, profound gorges, narrow valleys, vast amphitheaters, and beetling
precipices. Looking at them with a powerful telescope, the observer
might well fancy himself to be gazing down from an immense height into
the heart of the untraveled Himalayas. But these, imposing though they
are, do not constitute the most wonderful feature of the mountain
scenery of the moon.

Appearing sometimes on the shores of the "seas," sometimes in the midst
of broad plains, sometimes along the course of mountain chains, and
sometimes in magnificent rows, following for hundreds of miles the
meridians of the lunar globe, are tremendous, mountain-walled, circular
chasms, called craters. Frequently they have in the middle of their
depressed interior floors a peak, or a cluster of peaks. Their inner and
outer walls are seamed with ridges, and what look like gigantic streams
of frozen lava surround them. The resemblance that they bear to the
craters of volcanoes is, at first sight, so striking that probably
nobody would ever have thought of questioning the truth of the statement
that they are such craters but for their incredible magnitude. Many of
them exceed fifty miles in diameter, and some of them sink two, three,
four, and more miles below th