During the fifteen years, up to the time when she was saved by Harry, they must have lived in some secret abyss of the mine.
The old overman, full of mingled compassion and anger, made known to the engineer and Harry all that the name of Silfax had revealed to him.

It explained the whole mystery.

Silfax was the mysterious being so long vainly sought for in the depths of New Aberfoyle.
"So you knew him, Simon ?" demanded Mr.Starr.
"Yes, that I did," replied the overman.

"The Harfang man, we used to call him.

Why, he was old then! He must be fifteen or twenty years older than I am.