“Hans, to work!” cried my uncle.

The Icelander returned to the raft and soon came back with an iron bar which he made use of to bore a hole for the charge. This was no easy work. A hole was to be made large enough to hold fifty pounds of guncotton, whose expansive force is four times that of gunpowder.

I was terribly excited. Whilst Hans was at work I was actively helping my uncle to prepare a slow match of wetted powder encased in linen.

“This will do it,” I said.

“It will,” replied my uncle.

By midnight our mining preparations were over; the charge was rammed into the hole, and the slow match uncoiled along the gallery showed its end outside the opening.

A spark would now develop the whole of our preparations into activity.

“Tomorrow,” said the Professor.