"It is quite on a par with the other," muttered Barbican.
"He's hard to please, Captain," continued Ardan, "but let us try him again! Does not this plain look like—?"
"My worthy friend," interrupted Barbican, quietly, but in a tone to discourage further discussion, "what you think the plain looks like is of very slight import, as long as you know no more than a child what it really is!"
"Bravo, Barbican! well put!" cried the irrepressible Frenchman. "Shall I ever realize the absurdity of my entering into an argument with a scientist!"
But this time the Projectile, though advancing northward with a pretty uniform velocity, had neither gained nor lost in its nearness to the lunar disc. Each moment altering the character of the fleeting landscape beneath them, the travellers, as may well be imagined, never thought of taking an instant's repose. At about half past one, looking to their right on the west, they saw the summits of another mountain; Barbican, consulting his map, recognized Eratosthenes.
This was a ring mountain, about 33 miles in diameter, having, like Copernicus, a crater of immense profundity containing central cones. Whilst they were directing their glasses towards its gloomy depths, Barbican mentioned to his friends Kepler's strange idea regarding the formation of these ring mountains. "They must have been constructed," he said, "by mortal hands."
"With what object?" asked the Captain.
"A very natural one," answered Barbican. "The Selenites must have undertaken the immense labor of digging these enormous pits at places of refuge in which they could protect themselves against the fierce solar rays that beat against them for 15 days in succession!"
"Not a bad idea, that of the Selenites!" exclaimed Ardan.
"An absurd idea!" cried M'Nicholl. "But probably Kepler never knew the real dimensions of these craters. Barbican knows the trouble and time required to dig a well in Stony Hill only nine hundred feet deep. To dig out a single lunar crater would take hundreds and hundreds of years, and even then they should be giants who would attempt it!"