by Jules Verne
It will be agreed that it was enough to exasperate the most patient observers. It was precisely the unknown hemisphere that was hidden from their eyes. That face which a fortnight sooner or a fortnight later had been, or would be, splendidly lighted up by the solar rays, was then lost in absolute darkness. Where would the projectile be in another fortnight? Where would the hazards of attraction have taken it? Who could say?
It is generally admitted that the invisible hemisphere of the moon is, by its constitution, absolutely similar to the visible hemisphere. One-seventh of it is seen in those movements of libration Barbicane spoke of. Now upon the surface seen there were only plains and mountains, amphitheatres and craters, like those on the maps. They could there imagine the same arid and dead nature. And yet, supposing the atmosphere to have taken refuge upon that face? Suppose that with the air water had given life to these regenerated continents? Suppose that vegetation still persists there? Suppose that animals people these continents and seas? Suppose that man still lives under those conditions of habitability? How many questions there were it would have been interesting to solve! What solutions might have been drawn from the contemplation of that hemisphere! What delight it would have been to glance at that world which no human eye has seen!
The disappointment of the travellers in the midst of this darkness may be imagined. All observation of the lunar disc was prevented. The constellations alone were visible, and it must be acknowledged that no astronomers, neither Faye, Chacornac, nor the Secchi, had ever been in such favourable conditions to observe them.
In fact, nothing could equal the splendour of this starry world, bathed in limpid ether. Diamonds set in the celestial vault threw out superb flames. One look could take in the firmament from the Southern Cross to the North Star, those two constellations which will in 12,000 years, on account of the succession of equinoxes, resign their _rôles_ of polar stars, the one to Canopus in the southern hemisphere, the other to Wega in the northern. Imagination lost itself in this sublime infinitude, amidst which the projectile was moving like a new star created by the hand of man. From natural causes these constellations shone with a soft lustre; they did not twinkle because there was no atmosphere to intervene with its strata unequally dense, and of different degrees of humidity, which causes this scintillation.
The travellers long watched the constellated firmament, upon which the vast screen of the moon made an enormous black hole. But a painful sensation at length drew them from their contemplation. This was an intense cold, which soon covered the glasses of the port-lights with a thick coating of ice. The sun no longer warmed the projectile with his rays, and it gradually lost the heat stored up in its walls. This heat was by radiation rapidly evaporated into space, and a considerable lowering of the temperature was the result. The interior humidity was changed into ice by contact with the window-panes, and prevented all observation.
Nicholl, consulting the thermometer, said that it had fallen to 17° (centigrade) below zero (1° Fahr). Therefore, notwithstanding every reason for being economical, Barbicane was obliged to seek heat as well as light from gas. The low temperature of the bullet was no longer bearable. Its occupants would have been frozen to death.
"We will not complain about the monotony of the journey," said Michel Ardan. "What variety we have had, in temperature at all events! At times we have been blinded with light, and saturated with heat like the Indians of the Pampas! Now we are plunged into profound darkness amidst boreal cold, like the Esquimaux of the pole! No, indeed! We have no right to complain, and Nature has done many things in our honour!"
"But," asked Nicholl, "what is the exterior temperature?"
"Precisely that of planetary space," answered Barbicane.
"Then," resumed Michel Ardan, "would not this be an opportunity for making that experiment we could not attempt when we were bathed in the solar rays?"
"Now or never," answered Barbicane, "for we are usefully situated in order to verify the temperature of space, and see whether the calculations of Fourier or Pouillet are correct."
"Any way it is cold enough," said Michel. "Look at the interior humidity condensing on the port-lights. If this fall continues the vapour of our respiration will fall around us in snow."
"Let us get a thermometer," said Barbicane.
It will be readily seen that an ordinary thermometer would have given no result under the circumstances in which it was going to be exposed. The mercury would have frozen in its cup, for it does not keep liquid below 44° below zero. But Barbicane had provided himself with a spirit thermometer, on the Walferdin system, which gives the minima of excessively low temperature.
Before beginning the experiment this instrument was compared with an ordinary thermometer, and Barbicane prepared to employ it.
"How shall we manage it?" asked Nicholl.
"Nothing is easier," answered Michel Ardan, who was never at a loss. "Open the port-light rapidly, throw out the instrument; it will follow the projectile with exemplary docility; a quarter of an hour after take it in."
"With your hand?" asked Barbicane.
"With my hand," answered Michel.
"Well, then, my friend, do not try it," said Barbicane, "for the hand you draw back will be only a stump, frozen and deformed by the frightful cold."
"Really?"
"You would feel the sensation of a terrible burn, like one made with a red-hot iron, for the same thing happens when heat is brutally abstracted from our body as when it is inserted. Besides, I am not sure that objects thrown out still follow us."
"Why?" said Nicholl.
"Because if we are passing through any atmosphere, however slightly dense, these objects will be delayed. Now the darkness prevents us verifying whether they still float around us. Therefore, in order not to risk our thermometer, we will tie something to it, and so easily pull it back into the interior."
Barbicane's advice was followed. Nicholl threw the instrument out of the rapidly-opened port-light, holding it by a very short cord, so that it could be rapidly drawn in. The window was only open one second, and yet that one second was enough to allow the interior of the projectile to become frightfully cold.
"_Mille diables!_" cried Michel Ardan, "it is cold enough here to freeze white bears!"
Barbicane let half-an-hour go by, more than sufficient time to allow the instrument to descend to the level of the temperature of space. The thermometer was then rapidly drawn in.
Barbicane calculated the quantity of mercury spilt into the little phial soldered to the lower part of the instrument, and said--
"One hundred and forty degrees centigrade below zero!" (218° Fahr.)
M. Pouillet was right, not Fourier. Such was the frightful temperature of sidereal space! Such perhaps that of the lunar continents when the orb of night loses by radiation all the heat which she absorbs during the fifteen days of sunshine.
CHAPTER XV.
HYPERBOLA OR PARABOLA.
Our readers will probably be astonished that Barbicane and his companions were so little occupied with the future in store for them in their metal prison, carried along in the infinitude of ether. Instead of asking themselves where they were going, they lost their time in making experiments, just as if they had been comfortably installed in their own studies.
It might be answered that men so strong-minded were above such considerations, that such little things did not make them uneasy, and that they had something else to do than to think about their future.
The truth is that they were not masters of their projectile--that they could neither stop it nor alter its direction. A seaman can direct the head of his ship as he pleases; an aëronaut can give his balloon vertical movement. They, on the contrary, had no authority over their vehicle. No manoeuvre was possible to them. Hence their not troubling themselves, or "let things go" state of mind.
Where were they at that moment, 8 a.m. during that day called upon earth the sixth of December? Certainly in the neighbourhood of the moon, and even near en
ough for her to appear like a vast black screen upon the firmament. As to the distance which separated them, it was impossible to estimate it. The projectile, kept up by inexplicable forces, has grazed the north pole of the satellite at less than twenty-five miles' distance. But had that distance increased or diminished since they had been in the cone of shadow? There was no landmark by which to estimate either the direction or the velocity of the projectile. Perhaps it was going rapidly away from the disc and would soon leave the pure shadow. Perhaps, on the contrary, it was approaching it, and would before long strike against some elevated peak in the invisible atmosphere, which would have terminated the journey, doubtless to the detriment of the travellers.
A discussion began upon this subject, and Michel Ardan, always rich in explanations, gave out the opinion that the bullet, restrained by lunar attraction, would end by falling on the moon like an aërolite on to the surface of the terrestrial globe.
"In the first place," answered Barbicane, "all aërolites do not fall upon the surface of the earth; only a small proportion do so. Therefore, if we are aërolites it does not necessarily follow that we shall fall upon the moon."
"Still," answered Michel, "if we get near enough--"
"Error," replied Barbicane. "Have you not seen shooting stars by thousands in the sky at certain epochs?"
"Yes."
"Well, those stars, or rather corpuscles, only shine by rubbing against the atmospheric strata. Now, if they pass through the atmosphere, they pass at less than 16 miles from our globe, and yet they rarely fall. It is the same with our projectile. It may approach very near the moon, and yet not fall upon it."
"But then," asked Michel, "I am curious to know how our vehicle would behave in space."
"I only see two hypotheses," answered Barbicane, after some minutes' reflection.
"What are they?"
"The projectile has the choice between two mathematical curves, and it will follow the one or the other according to the velocity with which it is animated, and which I cannot now estimate."
"Yes, it will either describe a parabola or an hyperbola."
"Yes," answered Barbicane, "with some speed it will describe a parabola, and with greater speed an hyperbola."
"I like those grand words!" exclaimed Michel Ardan. "I know at once what you mean. And what is your parabola, if you please?"
"My friend," answered the captain, "a parabola is a conic section arising from cutting a cone by a plane parallel to one of its sides."
"Oh!" said Michel in a satisfied tone.
"It is about the same trajectory that the bomb of a howitzer describes."
"Just so. And an hyperbola?" asked Michel.
"It is a curve formed by a section of a cone when the cutting plane makes a greater angle with the base than the side of the cone makes."
"Is it possible?" exclaimed Michel Ardan in the most serious tone, as if he had been informed of a grave event. "Then remember this, Captain Nicholl, what I like in your definition of the hyperbola--I was going to say of the hyperhumbug--is that it is still less easy to understand than the word you pretend to define."
Nicholl and Barbicane paid no attention to Michel Ardan's jokes. They had launched into a scientific discussion. They were eager about what curve the projectile would take. One was for the hyperbola, the other for the parabola. They gave each other reasons bristling with _x_'s. Their arguments were presented in a language which made Michel Ardan jump. The discussion was lively, and neither of the adversaries would sacrifice his curve of predilection.
This scientific dispute was prolonged until Michel Ardan became impatient, and said--
"I say, Messrs. Cosine, do leave off throwing your hyperbolas and parabolas at one's head. I want to know the only interesting thing about the business. We shall follow one or other of your curves. Very well. But where will they take us to?"
"Nowhere," answered Nicholl.
"How nowhere?"
"Evidently they are unfinished curves, prolonged indefinitely!"
"Ah, _savants_! What does it matter about hyperbola or parabola if they both carry us indefinitely into space?"
Barbicane and Nicholl could not help laughing. They cared for art for its own sake. Never had more useless question been discussed at a more inopportune moment. The fatal truth was that the projectile, whether hyperbolically or parabolically carried along, would never strike against either the earth or the moon.
What would become of these bold travellers in the most immediate future? If they did not die of hunger or thirst, they would in a few days, when gas failed them, die for want of air, if the cold had not killed them first!
Still, although it was so important to economise gas, the excessive lowness of the surrounding temperature forced them to consume a certain quantity. They could not do without either its light or heat. Happily the caloric developed by the Reiset and Regnault apparatus slightly elevated the temperature of the projectile, and without spending much they could raise it to a bearable degree.
In the meantime observation through the port-lights had become very difficult. The steam inside the bullet condensed upon the panes and froze immediately. They were obliged to destroy the opacity of the glass by constant rubbing. However, they could record several phenomena of the highest interest.
In fact, if the invisible disc had any atmosphere, the shooting stars would be seen passing through it. If the projectile itself passed through the fluid strata, might it not hear some noise echoed--a storm, for instance, an avalanche, or a volcano in activity? Should they not see the intense fulgurations of a burning mountain? Such facts, carefully recorded, would have singularly elucidated the obscure question of the lunar constitution. Thus Barbicane and Nicholl, standing like astronomers at their port-lights, watched with scrupulous patience.
But until then the disc remained mute and dark. It did not answer the multifarious interrogations of these ardent minds.
This provoked from Michel a reflection that seemed correct enough.
"If ever we recommence our journey, we shall do well to choose the epoch when the moon is new."
"True," answered Nicholl, "that circumstance would have been more favourable. I agree that the moon, bathed in sunlight, would not be visible during the passage, but on the other hand the earth would be full. And if we are dragged round the moon like we are now, we should at least have the advantage of seeing the invisible disc magnificently lighted up."
"Well said, Nicholl," replied Michel Ardan. "What do you think about it, Barbicane?"
"I think this," answered the grave president: "if ever we recommence this journey, we shall start at the same epoch, and under the same circumstances. Suppose we had reached our goal, would it not have been better to find the continents in full daylight instead of dark night? Would not our first installation have been made under better circumstances? Yes, evidently. As to the invisible side, we could have visited that in our exploring expeditions on the lunar globe. So, therefore, the time of the full moon was well chosen. But we ought to have reached our goal, and in order to have reached it we ought not to have deviated from our road."
"There is no answer to make to that," said Michel Ardan. "Yet we have passed a fine opportunity for seeing the moon! Who knows whether the inhabitants of the other planets are not more advanced than the _savants_ of the earth on the subject of their satellites?"
The following answer might easily have been given to Michel Ardan's remark:--Yes, other satellites, on account of their greater proximity, have made the study of them easier. The inhabitants of Saturn, Jupiter, and Uranus, if they exist, have been able to establish communication with their moons much more easily. The four satellites of Jupiter gravitate at a distance of 108,260 leagues, 172,200 leagues, 274,700 leagues, and 480,130 leagues. But these distances are reckoned from the centre of the planet, and by taking away the radius, which is 17,000 to 18,000 leagues, it will be seen that the first satellite is at a much less distance from the surface of Jupiter than the moon is from
the centre of the earth. Of the eight moons of Saturn, four are near. Diana is 84,600 leagues off; Thetys, 62,966 leagues; Enceladus, 48,191 leagues; and lastly, Mimas is at an average distance of 34,500 leagues only. Of the eighteen satellites of Uranus, the first, Ariel, is only 51,520 leagues from the planet.
Therefore, upon the surface of those three stars, an experiment analogous to that of President Barbicane would have presented less difficulties. If, therefore, their inhabitants have attempted the enterprise, they have, perhaps, acquainted themselves with the constitution of the half of the disc which their satellite hides eternally from their eyes. But if they have never left their planet, they do not know more about them than the astronomers of the earth.
In the meantime the bullet was describing in the darkness that incalculable trajectory which no landmark allowed them to find out. Was its direction altered either under the influence of lunar attraction or under the action of some unknown orb? Barbicane could not tell. But a change had taken place in the relative position of the vehicle, and Barbicane became aware of it about 4 a.m.
The change consisted in this, that the bottom of the projectile was turned towards the surface of the moon, and kept itself perpendicular with its axis. The attraction or gravitation had caused this modification. The heaviest part of the bullet inclined towards the invisible disc exactly as if it had fallen towards it.
Was it falling then? Were the travellers at last about to reach their desired goal? No. And the observation of one landmark, inexplicable in itself, demonstrated to Barbicane that his projectile was not nearing the moon, and that it was following an almost concentric curve.
This was a flash of light which Nicholl signalised all at once on the limit of the horizon formed by the black disc. This point could not be mistaken for a star. It was a reddish flame, which grew gradually larger--an incontestable proof that the projectile was getting nearer it, and not falling normally upon the surface of the satellite.