The aperture, which was almost round, was about five feet in diameter; the dark passage was cut out in the live rock and lined with a coat of the eruptive matter which formerly issued from it; the interior was level with the ground outside, so that we were able to enter without difficulty. We were following a horizontal plane, when, only six paces in, our progress was interrupted by an enormous block just across our way.

“Accursed rock!” I cried in a passion, finding myself suddenly confronted by an impassable obstacle.

Right and left we searched in vain for a way, up and down, side to side; there was no getting any farther. I felt fearfully disappointed, and I would not admit that the obstacle was final. I stopped, I looked underneath the block: no opening. Above: granite still. Hans passed his lamp over every portion of the barrier in vain. We must give up all hope of passing it.

I sat down in despair. My uncle strode from side to side in the narrow passage.

“But how was it with Saknussemm?” I cried.