In observing the full moon in a cloudless sky no one has failed to remark this brilliant point of the southern hemisphere. Michel Ardan used every metaphor that his imagination could supply to designate it by. To him this Tycho was a focus of light, a center of irradiation, a crater vomiting rays. It was the tire of a brilliant wheel, an _asteria_ enclosing the disc with its silver tentacles, an enormous eye filled with flames, a glory carved for Pluto’s head, a star launched by the Creator’s hand, and crushed against the face of the moon! Tycho forms such a concentration of light that the inhabitants of the earth can see it without glasses, though at a distance of 240,000 miles! Imagine, then, its intensity to the eye of observers placed at a distance of only fifty miles! Seen through this pure ether, its brilliancy was so intolerable that Barbicane and his friends were obliged to blacken their glasses with the gas smoke before they could bear the splendor. Then silent, scarcely uttering an interjection of admiration, they gazed, they contemplated. All their feelings, all their impressions, were concentrated in that look, as under any violent emotion all life is concentrated at the heart. Tycho belongs to the system of radiating mountains, like Aristarchus and Copernicus; but it is of all the most complete and decided, showing unquestionably the frightful volcanic action to which the formation of the moon is due. Tycho is situated in 43° south latitude, and 12° east longitude. Its center is occupied by a crater fifty miles broad. It assumes a slightly elliptical form, and is surrounded by an enclosure of annular ramparts, which on the east and west overlook the outer plain from a height of 15,000 feet. It is a group of Mont Blancs, placed round one common center and crowned by radiating beams. What this incomparable mountain really is, with all the projections converging toward it, and the interior excrescences of its crater, photography itself could never represent. Indeed, it is during the full moon that Tycho is seen in all its splendor. Then all shadows disappear, the foreshortening of perspective disappears, and all proofs become white—a disagreeable fact: for this strange region would have been marvelous if reproduced with photographic exactness. It is but a group of hollows, craters, circles, a network of crests; then, as far as the eye could see, a whole volcanic network cast upon this encrusted soil. One can then understand that the bubbles of this central eruption have kept their first form. Crystallized by cooling, they have stereotyped that aspect which the moon formerly presented when under the Plutonian forces.