"Therefore," said Barbican, now taking up the subject, "an experiment analogous to ours, starting from either of these three planets, would have encountered fewer difficulties. But the whole question resolves itself into this. If the Jovians and the rest have been able to quit their planets, they have probably succeeded in discovering the invisible sides of their satellites. But if they have not been able to do so, why, they're not a bit wiser than ourselves—But what's the matter with the Projectile? It's certainly shifting!"
Shifting it certainly was. While the path it described as it swung blindly through the darkness, could not be laid down by any chart for want of a starting point, Barbican and his companions soon became aware of a decided modification of its relative position with regard to the Moon's surface. Instead of its side, as heretofore, it now presented its base to the Moon's disc, and its axis had become rigidly vertical to the lunar horizon. Of this new feature in their journey, Barbican had assured himself by the most undoubted proof towards four o'clock in the morning. What was the cause? Gravity, of course. The heavier portion of the Projectile gravitated towards the Moon's centre exactly as if they were falling towards her surface.
But were they falling? Were they at last, contrary to all expectations, about to reach the goal that they had been so ardently wishing for? No! A sight-point, just discovered by M'Nicholl, very soon convinced Barbican that the Projectile was as far as ever from approaching the Moon, but was moving around it in a curve pretty near concentric.
M'Nicholl's discovery, a luminous gleam flickering on the distant verge of the black disc, at once engrossed the complete attention of our travellers and set them to divining its course. It could not possibly be confounded with a star. Its glare was reddish, like that of a distant furnace on a dark night; it kept steadily increasing in size and brightness, thus showing beyond a doubt how the Projectile was moving—in the direction of the luminous point, and not vertically falling towards the Moon's surface.
"It's a volcano!" cried the Captain, in great excitement; "a volcano in full blast! An outlet of the Moon's internal fires! Therefore she can't be a burnt out cinder!"
"It certainly looks like a volcano," replied Barbican, carefully investigating this new and puzzling phenomenon with his night-glass. "If it is not one, in fact, what can it be?"
"To maintain combustion," commenced Ardan syllogistically and sententiously, "air is necessary. An undoubted case of combustion lies before us. Therefore, this part of the Moon must have an atmosphere!"
"Perhaps so," observed Barbican, "but not necessarily so. The volcano, by decomposing certain substances, gunpowder for instance, may be able to furnish its own oxygen, and thus explode in a vacuum. That blaze, in fact, seems to me to possess the intensity and the blinding glare of objects burning in pure oxygen. Let us therefore be not over hasty in jumping at the conclusion of the existence of a lunar atmosphere."
This fire mountain was situated, according to the most plausible conjecture, somewhere in the neighborhood of the 45th degree, south latitude, of the Moon's invisible side. For a little while the travellers indulged the fond hope that they were directly approaching it, but, to their great disappointment, the path described by the Projectile lay in a different direction. Its nature therefore they had no opportunity of ascertaining. It began to disappear behind the dark horizon within less than half an hour after the time that M'Nicholl had signalled it. Still, the fact of the uncontested existence of such a phenomenon was a grand one, and of considerable importance in selenographic investigations. It proved that heat had not altogether disappeared from the lunar world; and the existence of heat once settled, who can say positively that the vegetable kingdom and even the animal kingdom have not likewise resisted so far every influence tending to destroy them? If terrestrial astronomers could only be convinced, by undoubted evidence, of the existence of this active volcano on the Moon's surface, they would certainly admit of very considerable modifications in the present doubts regarding her inhabitability.
Thoughts of this kind continued to occupy the minds of our travellers even for some time after the little spark of light had been extinguished in the black gloom. But they said very little; even Ardan was silent, and continued to look out of the window. Barbican surrendered himself up to a reverie regarding the mysterious destinies of the lunar world. Was its present condition a foreshadowing of what our Earth is to become? M'Nicholl, too, was lost in speculation. Was the Moon older or younger than the Earth in the order of Creation? Had she ever been a beautiful world of life, and color, and magnificent variety? If so, had her inhabitants—
Great Mercy, what a cry from Ardan! It sounded human, so seldom do we hear a shriek so expressive at once of surprise and horror and even terror! It brought back his startled companions to their senses in a second. Nor did they ask him for the cause of his alarm. It was only too clear. Right in their very path, a blazing ball of fire had suddenly risen up before their eyes, the pitchy darkness all round it rendering its glare still more blinding. Its phosphoric coruscation filled the Projectile with white streams of lurid light, tinging the contents with a pallor indescribably ghastly. The travellers' faces in particular, gleamed with that peculiar livid and cadaverous tinge, blue and yellow, which magicians so readily produce by burning table salt in alcohol.
"Sacré!" cried Ardan who always spoke his own language when much excited. "What a pair of beauties you are! Say, Barbican! What thundering thing is coming at us now?"
"Another bolide," answered Barbican, his eye as calm as ever, though a faint tremor was quite perceptible in his voice.
"A bolide? Burning in vacuo? You are joking!"
"I was never more in earnest," was the President's quiet reply, as he looked through his closed fingers.
He knew exactly what he was saying. The dazzling glitter did not deceive him. Such a meteor seen from the Earth could not appear much brighter than the Full Moon, but here in the midst of the black ether and unsoftened by the veil of the atmosphere, it was absolutely blinding. These wandering bodies carry in themselves the principle of their incandescence. Oxygen is by no means necessary for their combustion. Some of them indeed often take fire as they rush through the layers of our atmosphere, and generally burn out before they strike the Earth. But others, on the contrary, and the greater number too, follow a track through space far more distant from the Earth than the fifty miles supposed to limit our atmosphere. In October, 1844, one of these meteors had appeared in the sky at an altitude calculated to be at least 320 miles; and in August, 1841, another had vanished when it had reached the height of 450 miles. A few even of those seen from the Earth must have been several miles in diameter. The velocity with which some of them have been calculated to move, from east to west, in a direction contrary to that of the Earth, is astounding enough to exceed belief—about fifty miles in a second. Our Earth does not move quite 20 miles in a second, though it goes a thousand times quicker than the fastest locomotive.
Barbican calculated like lightning that the present object of their alarm was only about 250 miles distant from them, and could not be less than a mile and a quarter in diameter. It was coming on at the rate of more than a mile a second or about 75 miles a minute. It lay right in the path of the Projectile, and in a very few seconds indeed a terrible collision was inevitable. The enormous rate at which it grew in size, showed the terrible velocity at which it was approaching.
You can hardly imagine the situation of our poor travellers at the sight of this frightful apparition. I shall certainly not attempt to describe it. In spite of their singular courage, wonderful coolness, extraordinary