"That scared me more than anything.
"I remembered all Otto's' stories about the 'knockers,' and, though I didn't believe them, I couldn't get them out of my head. Somebody, something, was knocking softly underground!
"It wasn't human, that was sure!
"It couldn't be Anton, because he'd been told to tap in threes. It couldn't be Jim, for the ticks were too close together to be the strokes of a pick; besides, I knew that Jim had left his tools behind. It couldn't be rescuers, because the sound was near me. Near me? It was almost at my ear.
"Sometimes breaking timber cracks. It might be a prop gradually giving way, I thought, just ready to let down a new fall of rock on my head. But a creaking timber is sometimes loud, sometimes soft, and this ticking, as I said, was regular, like a big clock.
"Then I guessed!
"It was drops of water falling!
"I could have shouted with relief, but down there, in the dark and the stillness, the silence was so heavy that I was afraid to shout.
"I felt my way forward, one step and then a second, and the ticking stopped.
"I took a third step and it began again. I stepped backward, and a little to one side, and the drop fell on my bare shoulder.