Every moment the light grew larger and plainer.
Then Frank saw that it occupied the whole size of the passage and at once understood that it was a chamber beyond illuminated.
This theory was borne out perfectly well, when, a few moments later, they came to the mouth of the passage.
A wonderful scene was spread before them.
They came out upon a sort of circular gallery about a deep amphitheater which lay below them.
The passage was only one of many leading into this gallery, and there were other galleries of similar sort.
It was far from being a new mine, as Frank saw at a glance.
Indeed, it might have been older than the mine they had just escaped from.
The light which illuminated the amphitheater, which was of large dimensions, was created by a large pitchwood fire burning in the center of the mine floor below.
Frank looked up and saw patches of the night sky through apertures in the roof of the mine, which was not far above their heads.