His proper name was the 'fireman.' At that time there was no other means of destroying the bad gas but by dispersing it in little explosions, before its buoyancy had collected it in too great quantities in the heights of the galleries.

The monk, as we called him, with his face masked, his head muffled up, all his body tightly wrapped in a thick felt cloak, crawled along the ground.

He could breathe down there, when the air was pure; and with his right hand he waved above his head a blazing torch.

When the firedamp had accumulated in the air, so as to form a detonating mixture, the explosion occurred without being fatal, and, by often renewing this operation, catastrophes were prevented.
Sometimes the 'monk' was injured or killed in his work, then another took his place.

This was done in all mines until the Davy lamp was universally adopted.