The second time, after many careful researches, he found that a pillar had just been blown up.
By the light of his lamp, Harry carefully examined the place attacked by the explosion.

It had not been made in a simple embankment of stones, but in a mass of schist, which had penetrated to this depth in the coal stratum.

Had the object of the explosion been to discover a new vein?
Or had someone wished simply to destroy this portion of the mine?
Thus he questioned, and when he made known this occurrence to his father, neither could the old overman nor he himself answer the question in a satisfactory way.
"It is very queer," Harry often repeated.

"The presence of an unknown being in the mine seems impossible, and yet there can be no doubt about it.

Does someone besides ourselves wish to find out if a seam yet exists?
Or, rather, has he attempted to destroy what remains of the Aberfoyle mines?
But for what reason?
I will find that out, if it should cost me my life!" A fortnight before the day on which Harry Ford guided the engineer through the labyrinth of the Dochart pit, he had been on the point of attaining the object of his search.