This mount situated in 9° north latitude and 20° east longitude, rose to a height of 10,600 feet above the surface of the moon. It is quite visible from the earth; and astronomers can study it with ease, particularly during the phase between the last quarter and the new moon, because then the shadows are thrown lengthways from east to west, allowing them to measure the heights. This Copernicus forms the most important of the radiating system, situated in the southern hemisphere, according to Tycho Brahé. It rises isolated like a gigantic lighthouse on that portion of the Sea of Clouds, which is bounded by the "Sea of Tempests," thus lighting by its splendid rays two oceans at a time. It was a sight without an equal, those long luminous trains, so dazzling in the full moon, and which, passing the boundary chain on the north, extends to the "Sea of Rains." At one o'clock of the terrestrial morning, the projectile, like a balloon borne into space, overlooked the top of this superb mountain. Barbicane could recognize perfectly its chief features. Copernicus is comprised in the series of ringed mountains of the first order, in the division of great circles. Like Kepler and Aristarchus, which overlook the Ocean of Tempests, sometimes it appeared like a brilliant point through the cloudy light, and was taken for a volcano in activity. But it is only an extinct one,—like all on that side of the moon. Its circumference showed a diameter of about twenty-two leagues. The glasses discovered traces of stratification produced by successive eruptions, and the neighbourhood was strewn with volcanic remains which still choked some of the craters. "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 towards the southern hemisphere?" "Well, I should say that it was still more beautiful," retorted Michel Ardan.