"Well, Harry," cried his father, "do you want us all to break our necks on the way back to the cottage ?" Harry did not answer.

He wondered if he ought to suspect the hand of a mysterious being in this last accident?
Could there possibly exist in these depths an enemy whose unaccountable antagonism would one day create serious difficulties?
Had someone an interest in defending the new coal field against any attempt at working it?
In truth that seemed absurd, yet the facts spoke for themselves, and they accumulated in such a way as to change simple presumptions into certainties.
In the meantime the explorers' situation was bad enough.

They had now, in the midst of black darkness, to follow the passage leading to the Dochart pit for nearly five miles.

There they would still have an hour's walk before reaching the cottage.
"Come along," said Simon Ford.

"We have no time to lose.