can, "but
it is even still more striking in the neighborhood of _Theophilus_ on
the borders of _Mare Nectaris_."

"That's _Mare Nectaris_, the gray spot over there on the southwest,
isn't it?" asked M'Nicholl; "is there any likelihood of our getting a
better view of it?"

"Not the slightest," answered Barbican, "unless we go round the Moon and
return this way, like a satellite describing its orbit."

By this time they had arrived at a point vertical to the mountain
centre. _Copernicus's_ vast ramparts formed a perfect circle or rather a
pair of concentric circles. All around the mountain extended a dark
grayish plain of savage aspect, on which the peak shadows projected
themselves in sharp relief. In the gloomy bottom of the crater, whose
dimensions are vast enough to swallow Mont Blanc body and bones, could
be distinguished a magnificent group of cones, at least half a mile in
height and glittering like piles of crystal. Towards the north several
breaches could be seen in the ramparts, due probably to a caving in of
immense masses accumulated on the summit of the precipitous walls.

As already observed, the surrounding plains were dotted with numberless
craters mostly of small dimensions, except _Gay Lussac_ on the north,
whose crater was about 12 miles in diameter. Towards the southwest and
the immediate east, the plain appeared to be very flat, no protuberance,
no prominence of any kind lifting itself above the general dead level.
Towards the north, on the contrary, as far as where the peninsula
jutted on _Oceanus Procellarum_, the plain looked like a sea of lava
wildly lashed for a while by a furious hurricane and then, when its
waves and breakers and driving ridges were at their wildest, suddenly
frozen into solidity. Over this rugged, rumpled, wrinkled surface and in
all directions, ran the wonderful streaks whose radiating point appeared
to be the summit of _Copernicus_. Many of them appeared to be ten miles
wide and hundreds of miles in length.

The travellers disputed for some time on the origin of these strange
radii, but could hardly be said to have arrived at any conclusion more
satisfactory than that already reached by some terrestrial observers.

To M'Nicholl's question:

"Why can't these streaks be simply prolonged mountain crests reflecting
the sun's rays more vividly by their superior altitude and comparative
smoothness?"

Barbican readily replied:

"These streaks _can't_ be mountain crests,