This hole was the "Black Lake"; it was Pluto, a deep circle which can be conveniently studied from the earth, between the last quarter and the new moon, when the shadows fall from west to east.
This black color is rarely met with on the surface of the satellite. As yet it has only been recognized in the depths of the circle of Endymion, to the east of the "Cold Sea," in the northern hemisphere, and at the bottom of Grimaldi's circle, on the equator, toward the eastern border of the orb.
Pluto is an annular mountain, situated in 51@ north latitude, and 9@ east longitude. Its circuit is forty-seven miles long and thirty-two broad.
Barbicane regretted that they were not passing directly above this vast opening. There was an abyss to fathom, perhaps some mysterious phenomenon to surprise; but the projectile's course could not be altered. They must rigidly submit. They could not guide a balloon, still less a projectile, when once enclosed within its walls. Toward five in the morning the northern limits of the "Sea of Rains" was at length passed. The mounts of Condamine and Fontenelle remained-- one on the right, the other on the left. That part of the disc beginning with 60@ was becoming quite mountainous. The glasses brought them to within two miles, less than that separating the summit of Mont Blanc from the level of the sea. The whole region was bristling with spikes and circles. Toward the 60@ Philolaus stood predominant at a height of 5,550 feet with its elliptical crater, and seen from this distance, the disc showed a very fantastical appearance.
Landscapes were presented to the eye under very different conditions from those on the earth, and also very inferior to them.
The moon having no atmosphere, the consequences arising from the absence of this gaseous envelope have already been shown.
No twilight on her surface; night following day and day following night with the suddenness of a lamp which is extinguished or lighted amid profound darkness-- no transition from cold to heat, the temperature falling in an instant from boiling point to the cold of space.
Another consequence of this want of air is that absolute darkness reigns where the sun's rays do not penetrate.
That which on earth is called diffusion of light, that luminous matter which the air holds in suspension, which creates the twilight and the daybreak, which produces the _umbrae_ and _penumbrae_, and all the magic of _chiaro-oscuro_, does not exist on the moon. Hence the harshness of contrasts, which only admit of two colors, black and white. If a Selenite were to shade his eyes from the sun's rays, the sky would seem absolutely black, and the stars would shine to him as on the darkest night. Judge of the impression produced on Barbicane and his three friends by this strange scene! Their eyes were confused. They could no longer grasp the respective distances of the different plains. A lunar landscape without the softening of the phenomena of _chiaro-oscuro_ could not be rendered by an earthly landscape painter; it would be spots of ink on a white page-- nothing more.
This aspect was not altered even when the projectile, at the height of 80@, was only separated from the moon by a distance of fifty miles; nor even when, at five in the morning, it passed at less than twenty-five miles from the mountain of Gioja, a distance reduced by the glasses to a quarter of a mile.
It seemed as if the moon might be touched by the hand!
It seemed impossible that, before long, the projectile would not strike her, if only at the north pole, the brilliant arch of which was so distinctly visible on the black sky.
Michel Ardan wanted to open one of the scuttles and throw himself on to the moon's surface! A very useless attempt; for if the projectile could not attain any point whatever of the satellite, Michel, carried along by its motion, could not attain it either.
At that moment, at six o'clock, the lunar pole appeared. The disc only presented to the travelers' gaze one half brilliantly lit up, while the other disappeared in the darkness. Suddenly the projectile passed the line of demarcation between intense light and absolute darkness, and was plunged in profound night!.
