The sounds of pursuit came in their rear.
All was dense blackness in the shaft and they were obliged to rush on blindly.
Lights were seen in their rear, and at times it seemed as if their pursuers must surely overtake them.
But Frank was possessed of a deadly resolution.
He knew that if he was caught it would be certain death.
Of course in the darkness there was imminent danger at any moment of falling into some dangerous pit or hole.
But the young inventor preferred such a fate to certain capture.
Barney kept at his heels closely.
Thus they rushed on at full speed.
Every moment new passages were encountered. Frank adopted the tactics of dodging into every one he could come to and keeping to the right.