In any case they might hope to be able to discover some phenomena of the highest interest.
But up to this time the disc remained dumb and dark. It did not answer the multiplicity of questions put by these ardent minds; a matter which drew this reflection from Michel, apparently a just one:
"If ever we begin this journey over again, we shall do well to choose the time when the moon is at the full."
"Certainly," said Nicholl, "that circumstance will be more favorable. I allow that the moon, immersed in the sun's rays, will not be visible during the transit, but instead we should see the earth, which would be full. And what is more, if we were drawn round the moon, as at this moment, we should at least have the advantage of seeing the invisible part of her disc magnificently lit."
"Well said, Nicholl," replied Michel Ardan. "What do you think, Barbicane?"
"I think this," answered the grave president: "If ever we begin this journey again, we shall start at the same time and under the same conditions. Suppose we had attained our end, would it not have been better to have found continents in broad daylight than a country plunged in utter darkness? Would not our first installation have been made under better circumstances? Yes, evidently. As to the invisible side, we could have visited it in our exploring expeditions on the lunar globe. So that the time of the full moon was well chosen. But we ought to have arrived at the end; and in order to have so arrived, we ought to have suffered no deviation on the road."
"I have nothing to say to that," answered Michel Ardan. "Here is, however, a good opportunity lost of observing the other side of the moon."
But the projectile was now describing in the shadow that incalculable course which no sight-mark would allow them to ascertain. Had its direction been altered, either by the influence of the lunar attraction, or by the action of some unknown star? Barbicane could not say. But a change had taken place in the relative position of the vehicle; and Barbicane verified it about four in the morning.
The change consisted in this, that the base of the projectile had turned toward the moon's surface, and was so held by a perpendicular passing through its axis. The attraction, that is to say the weight, had brought about this alteration. The heaviest part of the projectile inclined toward the invisible disc as if it would fall upon it.
Was it falling? Were the travelers attaining that much desired end? No. And the observation of a sign-point, quite inexplicable in itself, showed Barbicane that his projectile was not nearing the moon, and that it had shifted by following an almost concentric curve.
This point of mark was a luminous brightness, which Nicholl sighted suddenly, on the limit of the horizon formed by the black disc. This point could not be confounded with a star. It was a reddish incandescence which increased by degrees, a decided proof that the projectile was shifting toward it and not falling normally on the surface of the moon.
"A volcano! it is a volcano in action!" cried Nicholl; "a disemboweling of the interior fires of the moon! That world is not quite extinguished."
"Yes, an eruption," replied Barbicane, who was carefully studying the phenomenon through his night glass. "What should it be, if not a volcano?"
"But, then," said Michel Ardan, "in order to maintain that combustion, there must be air. So the atmosphere does surround that part of the moon."
"Perhaps so," replied Barbicane, "but not necessarily.
The volcano, by the decomposition of certain substances, can provide its own oxygen, and thus throw flames into space. It seems to me that the deflagration, by the intense brilliancy of the substances in combustion, is produced in pure oxygen. We must not be in a hurry to proclaim the existence of a lunar atmosphere."
The fiery mountain must have been situated about the 45@ south latitude on the invisible part of the disc; but, to Barbicane's great displeasure, the curve which the projectile was describing was taking it far from the point indicated by the eruption. Thus he could not determine its nature exactly.