able in their
convictions, the father and son took their picks, their sticks, and
their lamps. They went about searching, sounding the rock with a sharp
blow, listening if it would return a favor-able sound. So long as the
soundings had not been pushed to the granite of the primary formation,
the Fords were agreed that the search, unsuccessful to-day, might
succeed to-morrow, and that it ought to be resumed. They spent their
whole life in endeavoring to bring Aberfoyle back to its former
prosperity. If the father died before the hour of success, the son was
to go on with the task alone.

It was during these excursions that Harry was more particularly struck
by certain phenomena, which he vainly sought to explain. Several times,
while walking along some narrow cross-alley, he seemed to hear sounds
similar to those which would be produced by violent blows of a pickax
against the wall.

Harry hastened to seek the cause of this mysterious work. The tunnel
was empty. The light from the young miner's lamp, thrown on the wall,
revealed no trace of any recent work with pick or crowbar. Harry would
then ask himself if it was not the effect of some acoustic illusion, or
some strange and fantastic echo. At other times, on suddenly throwing a
bright light into a suspicious-looking cleft in the rock, he thought he
saw a shadow. He rushed forward. Nothing, and there was no opening to
permit a human being to evade his pursuit!

Twice in one month, Harry, whilst visiting the west end of the pit,
distinctly heard distant reports, as if some miner had exploded a charge
of dynamite. 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