"Well, let us be serious," replied Michel quietly; "and instead of spelikans, let us put bones. This plain would then be nothing but an immense cemetery, on which would repose the mortal remains of thousands of extinct generations. Do you prefer that high-flown comparison?" "One is as good as the other," retorted Barbicane. "My word, you are difficult to please," answered Michel. "My worthy friend," continued the matter-of-fact Barbicane, "it matters but little what it _resembles_, when we do not know what it _is_." "Well answered," exclaimed Michel. "That will teach me to reason with savants." But the projectile continued to advance with almost uniform speed around the lunar disc. The travellers, we may easily imagine, did not dream of taking a moment's rest. Every minute changed the landscape which fled from beneath their gaze. About half-past one o'clock in the morning, they caught a glimpse of the tops of another mountain. Barbicane, consulting his map, recognized Eratosthenes. It was a ringed mountain 9000 feet high, and one of those circles so numerous on this satellite. With regard to this, Barbicane related Kepler's singular opinion on the formation of circles. According to that celebrated mathematician, these crater-like cavities had been dug by the hand of man. "For what purpose?" asked Nicholl. "For a very natural one," replied Barbicane. "The Selenites might have undertaken these immense works and dug these enormous holes for a refuge and shield from the solar rays which beat upon them during fifteen consecutive days." "The Selenites are not fools," said Michel. "A singular idea," replied Nicholl; "but it is probable that Kepler did not know the true dimensions of these circles, for the digging of them would have been the work of giants quite impossible for the Selenites." "Why? if weight on the moon's surface is six times less than on the earth?" said Michel. "But if the Selenites are six times smaller?" retorted Nicholl. "And if there are no Selenites?" added Barbicane. This put an end to the discussion. Soon Eratosthenes disappeared under the horizon without the projectile being sufficiently near to allow of close observation. This mountain separated the Apennines from the Carpathians. In the lunar orography they have discerned some chains of mountains, which are chiefly distributed over the northern hemisphere. Some, however, occupy certain portions of the southern hemisphere also. About two o'clock in the morning Barbicane found that they were above the twentieth lunar parallel. The distance of the projectile from the moon was not more than 600 miles. Barbicane, now perceiving that the projectile was steadily approaching the lunar disc, did not despair, if of reaching her, at least of discovering the secrets of her configuration. CHAPTER XIII. LUNAR LANDSCAPES.