Said Milton Rhodes:
"All that we see or seem
Is but a dream within a dream.
"But come, Bill," he added, "don't let this a priori stuff bowl you over. In the first place, it isn't dark down there—when you get down far enough."
"In heaven's name, how do you know that?"
"Why, for one thing, if this subterranean world was one of unbroken darkness, the angel (and the demon) would be blind, like those fishes in the Mammoth Cave. But she is no more blind than you or I. Ergo, if for no other reason, we shall find light down there."
"Of course, they have artificial light, or"
"I don't mean that. If there had not been some other illumination, this strange race (of whose very existence science has never even dreamed) would have ceased to exist long ago—if, indeed, it ever could have begun."
"But no gleam of sunlight can ever find its way to that world."
"It never can, of course. But there are other sources of light—nebulas and comets in the heavens, for example, and auroras, phosphorus and fireflies here on earth. The phenomena of phosphorescence are by no means so rare as might be imagined. Why, as Nichol showed—though any man who uses his eyes can see it him-self —there is light inherent even in clouds."
All this, and more, Rhodes explained
to me, succinctly but
clearly.
"Oh, we'll find light, Bill," said he.
All the same this subterranean world for which we were bound presented some unpleasant possibilities, in addition, that is, to those concomitant to its being a habitat of demons
—and heaven only knew what be-sides.
"And, then, there is the air," I said. "As we descend, it will be-come denser and denser, until at last we shall be able to use these ice-picks on it."
Rhodes, who was removing his creepers, laughed.
"We will have to make a vertical descent of three and one-half miles below the level of the sea—a vertical descent of near five miles from this spot where we stand, Bill—before we reach a pressure of even two atmospheres."
"The density then increases rapidly, doesn't it?"
"Oh, yes. Three and a half miles more, and we are under a pressure of four atmospheres, or about sixty pounds to the square inch. Throe and a half miles farther down, or ten and one-half miles in all below the level of the sea, and we have a pressure upon us of eight atmospheres. Fourteen miles, and it will be sixteen atmospheres. At thirty-four miles the air will have the density of water; at forty-eight miles it will be as dense as mercury, and at fifty miles we shall have it as dense as gold."
"That will do!" I told him. "We can never get down that far."
"I have no idea how far we can go down, Bill."
"You know that we could never stand such pressures as those."
"I know that. But, as a matter of fact, I don't know what the pressures are at those depths. Nor does any other man know. What I said a moment ago is, of course, according to the law; but there is something wrong with the law, founded upon that of Mariotte—as any physicist will tell you."
"What's wrong with it?"
"At any rate, the law breaks down as one goes upward, and I have no doubt that it will be found to do so as one descends below the level of the
