About that time Harry unexpectedly made a discovery which, in part at least, accounted for the apparition of the fire-maidens among the ruins of Dundonald Castle at Irvine.
During several days he had been engaged in exploring the remote galleries of the prodigious excavation towards the south.

At last he scrambled with difficulty up a narrow passage which branched off through the upper rock.

To his great astonishment, he suddenly found himself in the open air.

The passage, after ascending obliquely to the surface of the ground, led out directly among the ruins of Dundonald Castle.
There was, therefore, a communication between New Aberfoyle and the hills crowned by this ancient castle.

The upper entrance to this gallery, being completely concealed by stones and brushwood, was invisible from without; at the time of their search, therefore, the magistrates had been able to discover nothing.
A few days afterwards, James Starr, guided by Harry, came himself to inspect this curious natural opening into the coal mine.