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.