The captain stepped back and gazed for some minutes at this great machine which the disappearance of the water had revealed.

It was easy for him to comprehend it now.
"When I slipped and sank," he said to himself, "I pulled down that lever, and I opened the water-gate and let out the lake." The captain was a man whose mind was perfectly capable of appreciating novel and strange impressions, but with him such impressions always connected themselves, in one way or another, with action: he could not stand and wonder at the wonderful which had happened--it always suggested something he must do.

What he now wanted to do was to climb up to the great aperture which lighted the cavern, and see what was outside.

He could not understand how the lake could have gone from its basin without the sound of the rushing waters being heard by any one of the party.
With some difficulty, he climbed up to the cleft and got outside.

Here he had a much better view of the topography of the place than he had yet been able to obtain.