[Illustration: THE ASCENT.]
Rollo found, after a while, that he did not need the strapmen; so he let Josie have them both. Josie put his staff through the loops of the straps, and took hold of the ends of it, while the men walked before him, and pulled him up the rocks.
Rollo kept ahead. He climbed faster than the rest of the train, but he stopped now and then on some projecting mass of lava to wait for them to come up. Next to Rollo came Josie, with the two strapmen pulling him up by their straps. Then the refreshment man, with his basket of provisions on his head. Last of all came the bearers of the portantina, with Rosie in the chair. Mr. George followed immediately after. He kept close to Rosie all the way, for he thought she would be afraid to be left alone with such wild and rough-looking men.
Indeed, she doubtless would have been afraid, for the men were rough and wild in their demeanor, as well as in their looks. They made a great deal of noise, shouting and scolding all the way. Every now and then they would stop to rest, and then they would clamor for buono manos, sometimes begging for the money in very earnest and noisy, but suppliant tones, and sometimes demanding it in a very loud and threatening manner. Mr. George, however, paid no heed to these requests, but steadily refused to give the men any money, saying simply that Philippe would pay. At length the men, finding that Mr. George was cool and collected, and that he did not seem to be at all intimidated by their violent and boisterous demeanor, became quiet, and performed their duty in a more steady and orderly manner.
The party went on climbing in this way for nearly an hour, and finally reached the summit.
CHAPTER VII. THE SUMMIT.
On coming out upon the brow of the mountain, Rollo saw at a short distance before him an immense column of dense white vapor pouring up into the air. His first impulse was to run forward up the sandy slope that still remained between the place where he stood and the margin of the crater; but he checked himself, and stopped where he was, to wait for the rest of the party. As soon as the portantina bearers reached the place where he stood, they set down the chair, and immediately the whole set crowded around Mr. George, and again demanded buono manos.
"Philippe payera," said Mr. George, pointing down the mountain to the Hermitage-"Philippe payera, là bas," which means, "Philippe will pay when you go down."
Mr. George said this in a very quiet manner, and then proceeded to help Rosie out of her chair. The guide who had come up the mountain with them then led the way, and Mr. George, Rollo, Rosie and Josie followed, towards the crater.
And here I must stop a moment in my story to explain a little what a crater is, and how it is formed. A crater is a great circular pit or depression in the top of a volcano, formed by the sinking of the ground in that part. This sinking of the ground is caused apparently by the cooling and shrinking of the melted matter below, after a time when it has been unusually heated.
Most boys have observed an effect similar to this in casting lead. When you attempt to cast any thing of lead,-a cannon, for example, or anchor, or even a bullet,-you will observe that as the lead cools, the portion of it which comes at the top of the mould shrinks and falls in, forming a little pit or depression, which you have to fill up by pouring in a little more lead. The reason is, that lead, as well as most other melted substances, shrinks when it cools. In the case of the bullet, for instance, all the lead which forms the mass of the bullet within the mould shrinks. The effect of this would be to collapse the sides, were it not that the sides have already become solid by contact with the cold mould. But the lead at the top, having been poured in last, is still fluid; and so that settles down as the lead cools below, and forms the little pit or depression, which the boy presently fills up by pouring in a little more lead.
It is much the same with a volcano. For some reason or other,-no one as yet knows what it is,-the interior of a volcano changes its temperature very much at different times. Sometimes for a period of several months, or years, it seems to be all the time growing hotter and hotter. The substances below become more and more melted, and formed into lava. The water, which is all the time filtering in through the crevices and openings, in the rocks around the sides of the mountain, is forced down under this molten mass by the immense pressure given to it by the height of the mountain. There it is turned into steam. For a time it is kept down by the vast weight of the lava which is over it, but after a time the elastic force of it gets so great that a bubble of it bursts up, and comes out at the top of the mountain in a great, thundering puff, bringing up some portion of the melted lava with it, and throwing it high into the air.
The lava thus thrown up falls down again, and when there is no wind it falls down close around the opening. Some of it falls into the opening, where it is melted again. The rest falls on the sides, and in process of time it begins to build up a small hill, as it were, all around the opening, though the puffs and explosions of steam that are continually coming out keep a mouth open at the top.
Things go on in this way for some time, until at length, for some mysterious reason which nobody understands, the interior of the mountain begins to moderate its heat, and finally to grow cool-not entirely cool, but cooler than it has been. The puffs and explosions gradually cease. The lava within the bowels of the mountain shrinks as it cools. The sides of the mountain being firm and solid, do not collapse; but the top, being still more or less soft, falls in, not suddenly, but by a slow and gradual motion, corresponding with the progress of the cooling below. So slow, indeed, is this progress, that sometimes the ground continues sinking slowly in this way for several years before the crater is fully formed.
All this time, although the puffs and explosions have in a great measure ceased, the steam continues to blow out, more or less steadily, from a great many small openings, some of them in the bottom of the crater, and some, perhaps, in the sides. This steam is changed into visible vapor when it comes out where the air is cool, and the several streams, mingling together as they rise into the air, form a cloudy column, which is often called smoke. Strictly speaking, however, it is not smoke. It is almost entirely composed of steam.
After continuing in this state for some time, the interior of the mountain begins to grow hot again. Then the steam and hot lava begin to puff out at some one or other of the vents in the bottom of the crater. If the heating goes on, the lava comes out hotter and hotter from the opening, and by melting away the sides of it and blowing it out, it gradually enlarges it. The lava that is blown out, too, falls down all around the hole, and gradually builds up a mound around it, like a little dome, while the successive blasts keep the outlet open all the time at the top. This small cone, rising up gradually thus, in the bottom of the crater formed by the sinking in of the mountain before, and the chimney opening up through the centre of it, gives vent to all the steam from below, while a great many of the other orifices are stopped up by the lava which comes up out of the great opening falling into them. After a time, the lava that is thrown out spreads over the whole floor of the crater in a mass of black, corrugated slag, with the small cone rising from the centre of it, and the opening at the top glowing like the mouth of a fiery furnace, and bursting out every now and then, with explosions of steam, and red-hot stones, and melted lava.
This was precisely the condition of Vesuvius at the time that Rollo visited it. The top of the mountain had fallen in, in two places, some time before, on account of the cooling below, and two great craters had been formed. Now, the furnace had been for some time heating up again, and in each crater a black cone, with a fiery mouth open at the apex of it, was gradually growing up, and covering the whole floor of the crater with the black and molten matter which it was ejecting.