In elliptical orbits, the attracting body always occupies one of the foci; so that at one moment the satellite is nearer, and at another farther from the orb around which it gravitates. When the earth is nearest the sun she is in her perihelion; and in her aphelion at the farthest point. Speaking of the moon, she is nearest to the earth in her perigee, and farthest from it in her apogee. To use analogous expressions, with which the astronomers' language is enriched, if the projectile remains as a satellite of the moon, we must say that it is in its "aposelene" at its farthest point, and in its "periselene" at its nearest. In the latter case, the projectile would attain its maximum of speed; and in the former its minimum. It was evidently moving toward its aposelenitical point; and Barbicane had reason to think that its speed would decrease up to this point, and then increase by degrees as it neared the moon.
This speed would even become _nil_, if this point joined that of equal attraction. Barbicane studied the consequences of these different situations, and thinking what inference he could draw from them, when he was roughly disturbed by a cry from Michel Ardan.
"By Jove!" he exclaimed, "I must admit we are down-right simpletons!""I do not say we are not," replied Barbicane; "but why?""Because we have a very simple means of checking this speed which is bearing us from the moon, and we do not use it!""And what is the means?"
"To use the recoil contained in our rockets.""Done!" said Nicholl.
"We have not used this force yet," said Barbicane, "it is true, but we will do so.""When?" asked Michel.
"When the time comes. Observe, my friends, that in the position occupied by the projectile, an oblique position with regard to the lunar disc, our rockets, in slightly altering its direction, might turn it from the moon instead of drawing it nearer?""Just so," replied Michel.
"Let us wait, then. By some inexplicable influence, the projectile is turning its base toward the earth. It is probable that at the point of equal attraction, its conical cap will be directed rigidly toward the moon; at that moment we may hope that its speed will be _nil_; then will be the moment to act, and with the influence of our rockets we may perhaps provoke a fall directly on the surface of the lunar disc.""Bravo!" said Michel. "What we did not do, what we could not do on our first passage at the dead point, because the projectile was then endowed with too great a speed.""Very well reasoned," said Nicholl.
"Let us wait patiently," continued Barbicane. "Putting every chance on our side, and after having so much despaired, I may say I think we shall gain our end."This conclusion was a signal for Michel Ardan's hips and hurrahs.
And none of the audacious boobies remembered the question that they themselves had solved in the negative. No! the moon is not inhabited; no! the moon is probably not habitable. And yet they were going to try everything to reach her.
One single question remained to be solved. At what precise moment the projectile would reach the point of equal attraction, on which the travelers must play their last card. In order to calculate this to within a few seconds, Barbicane had only to refer to his notes, and to reckon the different heights taken on the lunar parallels. Thus the time necessary to travel over the distance between the dead point and the south pole would be equal to the distance separating the north pole from the dead point.
The hours representing the time traveled over were carefully noted, and the calculation was easy. Barbicane found that this point would be reached at one in the morning on the night of the 7th-8th of December. So that, if nothing interfered with its course, it would reach the given point in twenty-two hours.
The rockets had primarily been placed to check the fall of the projectile upon the moon, and now they were going to employ them for a directly contrary purpose. In any case they were ready, and they had only to wait for the moment to set fire to them.
"Since there is nothing else to be done," said Nicholl, "I make a proposition.""What is it?" asked Barbicane.
"I propose to go to sleep."
"What a motion!" exclaimed Michel Ardan.
"It is forty hours since we closed our eyes," said Nicholl.
"Some hours of sleep will restore our strength.""Never," interrupted Michel.
"Well," continued Nicholl, "every one to his taste; I shall go to sleep." And stretching himself on the divan, he soon snored like a forty-eight pounder.
"That Nicholl has a good deal of sense," said Barbicane;"presently I shall follow his example." Some moments after his continued bass supported the captain's baritone.
"Certainly," said Michel Ardan, finding himself alone, "these practical people have sometimes most opportune ideas."And with his long legs stretched out, and his great arms folded under his head, Michel slept in his turn.
But this sleep could be neither peaceful nor lasting, the minds of these three men were too much occupied, and some hours after, about seven in the morning, all three were on foot at the same instant.
The projectile was still leaving the moon, and turning its conical part more and more toward her.
