You know that optical instruments have acquired great perfection; certain telescopes increase objects six thousand, and bring the moon to within a distance of forty miles.

Now at that distance objects sixty feet square are perfectly visible.

The power of penetration of the telescope has not been increased, because that power is only exercised to the detriment of their clearness, and the moon, which is only a reflecting mirror, does not send a light intense enough for the telescopes to increase objects beyond that limit." "Very well, then, what do you mean to do ?" asked the general.

"Do you intend giving a diameter of sixty feet to your projectile ?" "No." "You are not going to take upon yourself the task of making the moon more luminous ?" "I am, though." "That's rather strong!" exclaimed Maston.
"Yes, but simple," answered Barbicane.

"If I succeed in lessening the density of the atmosphere which the moon's light traverses, shall I not render that light more intense ?" "Evidently." "In order to obtain that result I shall only have to establish my telescope upon some high mountain.