the people who were watching me through glass peep-holes, would not work, and so I had to return to normal pressure.'
"So, you see, Bill, it is the low tension of the oxygen and not the diminished pressure that produces the distress and suffering and even death."
"All this is very interesting, but our problem is not one of rarefied air; the atmosphere here is compressed."
"And, in compressed air," said Milton Rhodes, "it is the oxygen again that produces the symptoms. Subject a sparrow to a pressure of twenty atmospheres, and the bird is thrown into convulsions, stronger than those produced by tetanus or strychnin, convulsions which soon end in death. If pure oxygen is used, a pressure of only five atmospheres kills the sparrow. But—and mark this—if the air be deficient in oxygen, the pressure of twenty atmospheres does not produce even a tremor. So, you see, Bill," he concluded, "we could descend to a very great depth in an atmosphere poor in oxygen."
"But how do we know that the atmosphere down there is poor in oxygen? It may be nothing of the kind. It may be saturated with it."
"Of course, we don't know. All we know is that we know nothing. And that reminds me of Socrates. That is what he said—that all he knew was that he didn't know anything. Arcesilaus declared that Socrates didn't even know that! However, hope is as cheap as despair. And, remember, here are our Hypogeans. They can ascend to our world, to a height of eight thousand feet above the level of the sea, and that, so far as we know, without suffering the slightest inconvenience."
"Something queer about that," was my comment.
"It is queer, Bill. However, we know that they can live in the (to them) rarefied air of our world; why, then, think that conditions down there, whether five miles down or fifty miles, will prove fatal to us?"
On the following morning, we
were under way at an early hour.
The route led down a great tunnel;
we could not have got lost now if we
had tried. Shortly before noon, the
welcome sounds of narranawnzee
were heard, and there was a large
stream gushing out of the wall. At
times, as we advanced, the stream
would move along dreamy and silent;
then it would be seen rushing and
glancing and again growling and
foaming in lovely cascades.
Steadily, save for the noon halt, we toiled our onward and downward way. It was half past 7 when we halted—the eery silence of the place broken by the soft, musical murmuring of the narranawnzee. Again Rhodes ascertained the boiling-point of water. It was 251° Fahrenheit. We were, therefore, under a pressure of two atmospheres; we had reached the depth of 18,500 feet. In other words, we were three miles and a half below the level of the sea!
It seems strange that I awoke, for I was dreaming the loveliest dream—a dream of fairy landscapes, birds and flowers, with lovely Cinderella in the midst of them. Nor do I know why I turned over onto my right side, for I was very comfortable as it was. But turn I did. And I was just going to close my eyes, to return to the dreamland of the fairies. But I did not close them. Instead, my heart gave a wild leap, and I opened them wide. The next instant I was sitting up, straining my eyes as I
