It must have taken at least twenty Indians.

No matter how many, they had succeeded in their design, and their victims were now helplessly enclosed in the dark catacomb--slowly, despairingly to perish.
"All up wi' us, I reck'n," said the guide, as he once more let himself down upon the ledge to communicate the particulars to his companion.
Hamersley ascended to see for himself.

They could only go one at a time.

He examined the edge of the orifice where the rock rested upon it.

He could only do so by the touch.