Of its size, shape and general conditions the adventurers, as yet, could but guess. They could see it was a pleasant place, and one where there might be the means to sustain life. For, as the professor said afterward, he felt that where there were flowers there would be fruits, and where both of these provisions of nature were to be found there would likely be animal life, and even, perhaps, human beings.

But, for the time, they were content to look from the port on the beautiful scene that lay stretched out before them. The ship rested on an even keel and had landed so softly that none of the plates were strained.

“We have plenty of air, at all events,” said the professor as he took a deep breath. “I was afraid of that, but it seems there was no need. The air appears to be as good and fresh as that on the surface of the earth, only there is a curious property to it. It makes one feel larger. I imagine it must be thinner than the air of the earth, which is a rather strange thing, since the higher one goes the more rarefied the air becomes, and the lower, the more dense. Still we can not apply natural philosophy to conditions under the earth. All the usual theories may be upset. However, we should be content to take things as we find them, and be glad we were not dashed to pieces when the ship was caught in the terrible current.”

“What do you suppose caused the awful heat, and then made it go away again?” asked Jack.

“I can only make a guess at it,” Mr. Henderson answered. “There are many strange things we will come across if we stay here long, I believe. As for the fire I think we must have passed a sort of interior volcano.”

“But what sort of a place do you think we have come to, Professor?” asked Mark.

“It is hard to say,” the scientist replied. “We are certainly somewhere within the earth. Our gage tells us it is five hundred miles. That may or may not be correct, but I believe we are several hundred miles under the crust, at all events. As to what sort of a place it is, you can see for yourselves.”

“But how is it we can breathe here, and things can grow?” asked Bill, who was beginning to lose his fright at the thought of being practically buried alive.

“I do not know what makes such things possible,” Mr. Henderson replied, “but that there is air here is a certainty. I can hardly believe it is drawn from the surface of the earth, down the big hole, and I am inclined to think this place of the under-world has an atmosphere of its own, and one which produces different effects than does our own.”

“They certainly have larger flowers than we have,” said Mark. “See how big they grow, and what strong colors they have.”