Where the light came from it was impossible to say, for the roof of the cavern appeared to be formed, like the walls, of solid rock; but from the fact that shafts of light were plainly visible overhead, issuing from the walls and roof, I conjectured that the light entered the cavern through rifts in the rock, and that its greenish tinge was imparted to it by the foliage through which it filtered prior to its passage through the rifts.
