No matter for that.

The noise made in its descent told them of projecting points or ledges that might give them a foothold.
They lost not a moment of time, but commenced letting themselves down into the funnel-shaped shaft, the guide going first.
Slowly and silently they went down--like ghosts through the stage of a theatre--soon disappearing in the gloom below, and leaving upon the rock-strewn platform no trace to show that human foot had ever trodden it..