At five o'clock we were two thousand feet above sea-level; at half past seven, about half a thousand. And we then decided to call it a day. Nor was I at all sorry to do so, even though we might be near some strange, even great discovery, for I was very tired, and sore from the top of my head to the end of my toes. I was in fair trim, and so was Milton Rhodes; but it would take us some time to get used to such work as this.
A very gentle current of air, so slight that it required experiment to detect it, was passing down the gallery. The temperature here was 62° Fahrenheit.
We had stopped before a cavity in the wall, and, in that little chamber, we passed the night, one holding watch whilst the other slept.
My dreams were dreadful, but otherwise the night was as peaceful as any that ever passed over Eden. Neither Rhodes nor I, during that strange, eerie vigil there in the heart of the living rock, heard even the faintest, the most fleeting sound. As the watcher sat there waiting and listening, whilst the minutes slowly passed, he found himself—at any rate, I know that I did—almost wishing that some pulsation would come, so heavy and awful was the stillness of the place.
But a sound we were to hear. We had been journeying for about an hour and a half and had just passed below sea-level. In that place Rhodes had left the aneroid. Of a sudden Milton, who was leading the way, halted with a low, sharp interjection for silence. When my look struck him, he was standing in an attitude of the most riveted attention.
"There!" he exclaimed. "Did you hear that, Bill?"
The air had pulsed to the faintest sound; now all was still again.
"What was it?" I asked, my voice a whisper.
"Don't know, Bill. Haven't an idea. There!"
Again that gentle pulsation touched the ear, and again it was gone. And a strange thing was that, for the life of me, I could not have told whether it came from below or from behind us.