"Who knows?" answered the sailor. "Perhaps there may be some valuable substance in this volcano, which it will spout forth, and which we may turn to good account!"

Cyrus Harding shook his head with the air of a man who augured no good from the phenomenon whose developments had been so sudden. He did not regard so lightly as Pencroft the results of an eruption. If the lava, in consequence of the position of the crater, did not directly menace the wooded and cultivated parts of the island, other complications might present themselves. In fact, eruptions are not unfrequently accompanied by earthquakes; and an island of the nature of Lincoln Island formed of substances so varied, basalt on one side, granite on the other, lava on the north, rich soil on the south, substances which consequently could not be firmly attached to each other, would be exposed to the risk of disintegration. Although, therefore, the spreading of the volcanic matter might not const.i.tute a serious danger, any movement of the terrestrial structure which should shake the island might entail the gravest consequences.

"It seems to me," said Ayrton, who had reclined so as to place his ear to the ground, "it seems to me that I can hear a dull, rumbling sound, like that of a wagon loaded with bars of iron."

The colonists listened with the greatest attention, and were convinced that Ayrton was not mistaken. The rumbling was mingled with a subterranean roar, which formed a sort of _rinforzando_, and died slowly away, as if some violent storm had pa.s.sed through the profundities of the globe. But no explosion, properly so termed, could be heard. It might therefore be concluded that the vapours and smoke found a free pa.s.sage through the central shaft; and that the safety-valve being sufficiently large, no convulsion would be produced, no explosion was to be apprehended.

"Well, then!" said Pencroft, "are we not going back to work? Let Mount Franklin smoke, groan, bellow, or spout forth fire and flame as much as it pleases, that is no reason why we should be idle! Come, Ayrton, Neb, Herbert, Captain Harding, Mr Spilett, every one of us must turn to at our work to-day! We are going to place the keelson, and a dozen pair of hands would not be too many. Before two months I want our new _Bonadventure_--for we shall keep the old name, shall we not?--to float on the waters of Port Balloon! Therefore there is not an hour to lose!"

All the colonists, their services thus requisitioned by Pencroft, descended to the dockyard, and proceeded to place the keelson, a thick ma.s.s of wood which forms the lower portion of a ship and unites firmly the timbers of the hull. It was an arduous undertaking, in which all took part.

They continued their labours during the whole of this day, the 3rd of January, without thinking further of the volcano, which could not, besides, be seen from the sh.o.r.e of Granite House. But once or twice, large shadows, veiling the sun, which described its diurnal arc through an extremely clear sky, indicated that a thick cloud of smoke pa.s.sed between its disc and the island. The wind, blowing on the sh.o.r.e, carried all these vapours to the westward. Cyrus Harding and Gideon Spilett remarked these sombre appearances, and from time to time discussed the evident progress of the volcanic phenomena, but their work went on without interruption. It was, besides, of the first importance from every point of view, that the vessel should be finished with the least possible delay. In presence of the eventualities which might arise, the safety of the colonists would be to a great extent secured by their ship. Who could tell that it might not prove some day their only refuge?

In the evening, after supper, Cyrus Harding, Gideon Spilett, and Herbert, again ascended the plateau of Prospect Heights. It was already dark, and the obscurity would permit them to ascertain if flames or incandescent matter thrown up by the volcano were mingled with the vapour and smoke acc.u.mulated at the mouth of the crater.

"The crater is on fire!" said Herbert, who, more active than his companions, first reached the plateau.

Mount Franklin, distant about six miles, now appeared like a gigantic torch, around the summit of which turned fuliginous flames. So much smoke, and possibly scoriae and cinders were mingled with them, that their light gleamed but faintly amid the gloom of the night. But a kind of lurid brilliancy spread over the island, against which stood out confusedly the wooded ma.s.ses of the heights. Immense whirlwinds of vapour obscured the sky, through which glimmered a few stars.

"The change is rapid!" said the engineer. "That is not surprising,"

answered the reporter. "The re-awakening of the volcano already dates back some time. You may remember, Cyrus, that the first vapours appeared about the time we searched the sides of the mountain to discover Captain Nemo's retreat. It was, if I mistake not, about the 15th of October."

"Yes," replied Herbert, "two months and a half ago!"

"The subterranean fires have therefore been smouldering for ten weeks,"

resumed Gideon Spilett, "and it is not to be wondered at that they now break out with such violence!"

"Do not you feel a certain vibration of the soil?" asked Cyrus Harding.

"Yes," replied Gideon Spilett, "but there is a great difference between that and an earthquake."

"I do not affirm that we are menaced with an earthquake," answered Cyrus Harding, "may G.o.d preserve us from that! No; these vibrations are due to the effervescence of the central fire. The crust of the earth is simply the sh.e.l.l of a boiler, and you know that such a sh.e.l.l, under the pressure of steam, vibrates like a sonorous plate. It is this effect which is being produced at this moment."

"What magnificent flames!" exclaimed Herbert.

At this instant a kind of bouquet of flames shot forth from the crater, the brilliancy of which was visible even through the vapours. Thousands of luminous sheets and barbed tongues of fire were cast in various directions. Some, extending beyond the dome of smoke, dissipated it, leaving behind an incandescent powder. This was accompanied by successive explosions, resembling the discharge of a battery of mitrailleuses.

Cyrus Harding, the reporter, and Herbert, after spending an hour on the plateau of Prospect Heights, again descended to the beach, and returned to Granite House. The engineer was thoughtful and preoccupied, so much so, indeed, that Gideon Spilett inquired if he apprehended any immediate danger, of which the eruption might directly or indirectly be the cause.

"Yes, and no," answered Cyrus Harding.

"Nevertheless," continued the reporter, "would not the greatest misfortune which could happen to us be an earthquake which would overturn the island? Now, I do not suppose that this is to be feared, since the vapours and lava have found a free outlet."

"True," replied Cyrus Harding, "and I do not fear an earthquake in the sense in which the term is commonly applied to convulsions of the soil provoked by the expansion of subterranean gases. But other causes may produce great disasters."

"How so, my dear Cyrus?"

"I am not certain. I must consider. I must visit the mountain. In a few days I shall learn more on this point."

Gideon Spilett said no more, and soon, in spite of the explosions of the volcano, whose intensity increased, and which were repeated by the echoes of the island, the inhabitants of Granite House were sleeping soundly.

Three days pa.s.sed by--the 4th, 5th, and 6th of January. The construction of the vessel was diligently continued, and without offering further explanations the engineer pushed forward the work with all his energy. Mount Franklin was now hooded by a sombre cloud of sinister aspect, and, amid the flames, vomited forth incandescent rocks, some of which fell back into the crater itself. This caused Pencroft, who would only look at the matter in the light of a joke, to exclaim--

"Ah! the giant is playing at cup and ball; he is a conjuror."

In fact, the substances thrown up fell back again into the abyss, and it did not seem that the lava, though swollen by the internal pressure, had yet risen to the orifice of the crater. At any rate, the opening on the north-east, which was partly visible, poured out no torrent upon the northern slope of the mountain.

Nevertheless, however pressing was the construction of the vessel, other duties demanded the presence of the colonists on various portions of the island. Before everything it was necessary to go to the corral, where the flocks of musmons and goats were enclosed, and replenish the provision of forage for those animals. It was accordingly arranged that Ayrton should proceed thither the next day, the 7th of January; and as he was sufficient for the task, to which he was accustomed, Pencroft and the rest were somewhat surprised on hearing the engineer say to Ayrton--

"As you are going to-morrow to the corral I will accompany you."

"But, Captain Harding," exclaimed the sailor, "our working days will not be many, and if you go also we shall be two pair of hands short!"

"We shall return to-morrow," replied Cyrus Harding, "but it is necessary that I should go to the corral. I must learn how the eruption is progressing."

"The eruption! always the eruption!" answered Pencroft, with an air of discontent. "An important thing, truly, this eruption! I trouble myself very little about it."

Whatever might be the sailor's opinion, the expedition projected by the engineer was settled for the next day. Herbert wished to accompany Cyrus Harding, but he would not vex Pencroft by his absence.

The next day, at dawn, Cyrus Harding and Ayrton, mounting the cart drawn by two onagas, took the road to the corral and set off at a round trot.

Above the forest were pa.s.sing large clouds, to which the crater of Mount Franklin incessantly added fuliginous matter. These clouds, which rolled heavily in the air, were evidently composed of heterogeneous substances. It was not alone from the volcano that they derived their strange opacity and weight. Scorias, in a state of dust, like powdered pumice-stone, and greyish ashes as small as the finest feculae, were held in suspension in the midst of their thick folds. These ashes are so fine that they have been observed in the air for whole months. After the eruption of 1783 in Iceland for upwards of a year the atmosphere was thus charged with volcanic dust through which the rays of the sun were only with difficulty discernible.

But more often this pulverised matter falls, and this happened on the present occasion. Cyrus Harding and Ayrton had scarcely reached the corral when a sort of black snow like fine gunpowder fell, and instantly changed the appearance of the soil. Trees, meadows, all disappeared beneath a covering several inches in depth. But, very fortunately, the wind blew from the north-east, and the greater part of the cloud dissolved itself over the sea.

"This is very singular, Captain Harding," said Ayrton.

"It is very serious," replied the engineer. "This powdered pumice-stone, all this mineral dust, proves how grave is the convulsion going forward in the lower depths of the volcano."

"But can nothing be done?"

"Nothing, except to note the progress of the phenomenon. Do you, therefore, Ayrton, occupy yourself with the necessary work at the corral. In the meantime I will ascend just beyond the source of Red Creek and examine the condition of the mountain upon its northern aspect. Then--"

"Well, Captain Harding?"

"Then we will pay a visit to Dakkar Grotto. I wish to inspect it. At any rate I will come back for you in two hours."

Ayrton then proceeded to enter the corral, and, while waiting the engineer's return, busied himself with the musmons and goats, which seemed to feel a certain uneasiness in presence of these first signs of an eruption.

Meanwhile Cyrus Harding ascended the crest of the eastern spur, pa.s.sed Red Creek, and arrived at the spot where he and his companions had discovered a sulphureous spring at the time of their first exploration.

How changed was everything! Instead of a single column of smoke he counted thirteen, forced through the soil as if violently propelled by some piston. It was evident that the crust of the earth was subjected in this part of the globe to a frightful pressure. The atmosphere was saturated with gases and carbonic acid, mingled with aqueous vapours.

Cyrus Harding felt the volcanic tufa with which the plain was strewn, and which were but pulverised cinders hardened into solid blocks by time, tremble beneath him, but he could discover no traces of fresh lava.

The engineer became more a.s.sured of this when he observed all the northern part of Mount Franklin. Pillars of smoke and flame escaped from the crater; a hail of scorias fell on the ground; but no current of lava burst from the mouth of the volcano, which proved that the volcanic matter had not yet attained the level of the superior orifice of the central shaft.

"But I would prefer that it were so," said Cyrus Harding to himself.

"At any rate, I should then know that the lava had followed its accustomed track. Who can say that they may not take a new course? But the danger does not consist in that! Captain Nemo foresaw it clearly!