"Spillikins?" cried his companions, somewhat surprised. "Yes, Spillikins! These rocks, these blocks, these peaks, these streaks, these cones, these cracks, these ramparts, these escarpments,--what are they but a set of spillikins, though I acknowledge on a grand scale? I wish I had a little hook to pull them one by one!" [Illustration: AN IMMENSE BATTLEFIELD.] "Oh, do be serious, Ardan!" cried Barbican, a little impatiently. "Certainly," replied Ardan. "Let us be serious, Captain, since seriousness best befits the subject in hand. What do you think of another comparison? Does not this plain look like an immense battle field piled with the bleaching bones of myriads who had slaughtered each other to a man at the bidding of some mighty Caesar? What do you think of that lofty comparison, hey?" "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!"