"There exist," said Barbicane, "several kinds of circles on the surface of the moon, and it is easy to see that Copernicus belongs to the radiating class. If we were nearer, we should see the cones bristling on the inside, which in former times were so many fiery mouths. A curious arrangement, and one without an exception on the lunar disc, is that the interior surface of these circles is the reverse of the exterior, and contrary to the form taken by terrestrial craters. It follows, then, that the general curve of the bottom of these circles gives a sphere of a smaller diameter than that of the moon.""And why this peculiar disposition?" asked Nicholl.
"We do not know," replied Barbicane.
"What splendid radiation!" said Michel. "One could hardly see a finer spectacle, I think.""What would you say, then," replied Barbicane, "if chance should bear us toward the southern hemisphere?""Well, I should say that it was still more beautiful," retorted Michel Ardan.
At this moment the projectile hung perpendicularly over the circle.
The circumference of Copernicus formed almost a perfect circle, and its steep escarpments were clearly defined. They could even distinguish a second ringed enclosure. Around spread a grayish plain, of a wild aspect, on which every relief was marked in yellow.
At the bottom of the circle, as if enclosed in a jewel case, sparkled for one instant two or three eruptive cones, like enormous dazzling gems. Toward the north the escarpments were lowered by a depression which would probably have given access to the interior of the crater.
In passing over the surrounding plains, Barbicane noticed a great number of less important mountains; and among others a little ringed one called Guy Lussac, the breadth of which measured twelve miles.
Toward the south, the plain was very flat, without one elevation, without one projection. Toward the north, on the contrary, till where it was bounded by the "Sea of Storms," it resembled a liquid surface agitated by a storm, of which the hills and hollows formed a succession of waves suddenly congealed.
Over the whole of this, and in all directions, lay the luminous lines, all converging to the summit of Copernicus.
The travelers discussed the origin of these strange rays; but they could not determine their nature any more than terrestrial observers.
"But why," said Nicholl, "should not these rays be simply spurs of mountains which reflect more vividly the light of the sun?""No," replied Barbicane; "if it was so, under certain conditions of the moon, these ridges would cast shadows, and they do not cast any."And indeed, these rays only appeared when the orb of day was in opposition to the moon, and disappeared as soon as its rays became oblique.
"But how have they endeavored to explain these lines of light?"asked Michel; "for I cannot believe that savants would ever be stranded for want of an explanation.""Yes," replied Barbicane; "Herschel has put forward an opinion, but he did not venture to affirm it.""Never mind. What was the opinion?"
