Barbicane made his companions observe that the height of this mountain above the surrounding plain was far from equalling the depth of its crater. This enormous hole was beyond all measurement, and formed a gloomy abyss, the bottom of which the sun's rays could never reach. There, according to Humboldt, reigns utter darkness, which the light of the sun and the earth cannot break. Mythologists could well have made it the mouth of hell. "Newton," said Barbicane, "is the most perfect type of these annular mountains, of which the earth possesses no sample. They prove that the moon's formation, by means of cooling, is due to violent causes; for whilst under the pressure of internal fires the reliefs rise to considerable height, the depths withdraw far below the lunar level." "I do not dispute the fact," replied Michel Ardan. Some minutes after passing Newton, the projectile directly overlooked the annular mountain of Moret. It skirted at some distance the summits of Blancanus, and at about half-past seven in the evening reached the circle of Clavius. This circle, one of the most remarkable of the disc, is situated in 58° south lat., and 15° east long. Its height is estimated at 22,950 feet. The travellers, at a distance of twenty-four miles (reduced to four by their glasses), could admire this vast crater in its entirety. Illustration: CAN YOU PICTURE TO YOURSELVES? "Terrestrial volcanoes," said Barbicane, "are but molehills compared with those of the moon. Measuring the old craters formed by the first eruptions of Vesuvius and Etna, we find them little more than three miles in breadth. In France the circle of Cantal measures six miles across; at Ceyland the circle of the island is forty miles, which is considered the largest on the globe. What are these diameters against that of Clavius, which we overlook at this moment?" "What is its breadth?" asked Nicholl. "It is 150 miles," replied Barbicane. "This circle is certainly the most important on the moon, but many others measure 150, 100, or 75 miles." "Ah! my friends," exclaimed Michel, "can you picture to yourselves what this now peaceful orb of night must have been when its craters, filled with thunderings, vomited at the same time smoke and tongues of flame. What a wonderful spectacle then, and now what decay! This moon is nothing more than a thin carcase of fireworks, whose squibs, rockets, serpents and suns, after a superb brilliancy, have left but sadly broken cases. Who can say the cause, the reason, the motive force of these cataclysms?" Barbicane was not listening to Michel Ardan; he was contemplating those ramparts of Clavius, formed by large mountains spread over several miles. At the bottom of the immense cavity burrowed hundreds of small extinguished craters, riddling the soil like a colander, and overlooked by a peak 15,000 feet high.