As a boy I had read wild works of fiction about lands in the interior of the earth, with a sun at the centre, which gave them the light of a perpetual day.

These, I knew, were only the creations of fiction; yet, after all, it seemed possible that the earth might contain vast hollow spaces in its interior--realms of eternal darkness, caverns in comparison with which the hugest caves on the surface were but the tiniest cells.

I was now being borne on to these.

In that case there might be no sudden plunge, after all.

The stream might run on for many thousand miles through this terrific cavern gloom, in accordance with natural laws; and I might thus live, and drift on in this darkness, until I should die a lingering death of horror and despair.
There was no possible way of forming any estimate as to speed.