"Did not these fires cause any explosion?" asked the engineer quickly.

"Yes, little partial explosions," replied Ford, "such as I used to cause myself when I wished to ascertain the presence of fire-damp. Do you remember how formerly it was the custom to try to prevent explosions before our good genius, Humphry Davy, invented his safety-lamp?"

"Yes," replied James Starr. "You mean what the 'monk,' as the men called him, used to do. But I have never seen him in the exercise of his duty."

"Indeed, Mr. Starr, you are too young, in spite of your five-and-fifty years, to have seen that. But I, ten years older, often saw the last 'monk' working in the mine. He was called so because he wore a long robe like a monk. 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. But I knew the plan, and by its means I discovered the presence of firedamp and consequently that of a new seam of coal in the Dochart pit."