This was the only way of communication which existed between the bottom of the Dochart pit and the open air.

As to air, that came in by the Yarrow shaft, from whence galleries communicated with another shaft whose orifice opened at a higher level; the warm air naturally escaped by this species of inverted siphon.
"I will follow you, my lad," said the engineer, signing to the young man to precede him.
"As you please, Mr.Starr." "Have you your lamp ?" "Yes, and I only wish it was still the safety lamp, which we formerly had to use!" "Sure enough," returned James Starr, "there is no fear of fire-damp explosions now!" Harry was provided with a simple oil lamp, the wick of which he lighted.
In the mine, now empty of coal, escapes of light carburetted hydrogen could not occur.

As no explosion need be feared, there was no necessity for interposing between the flame and the surrounding air that metallic screen which prevents the gas from catching fire.

The Davy lamp was of no use here.

But if the danger did not exist, it was because the cause of it had disappeared, and with this cause, the combustible in which formerly consisted the riches of the Dochart pit.
Harry descended the first steps of the upper ladder.