Could a fresh exploration of the mine, undertaken by the engineer, account for such a long absence?
Certainly not.
It was intensely dark all round.

The lamps held by the men gave light only just where they were standing.

Suddenly Jack Ryan uttered a cry.
"Look there, there!" His finger was pointing to a tolerably bright light, which was moving about in the distance.

"After that light, my men!" exclaimed Sir William.
"It's a goblin light!" said Ryan.

"So what's the use?
We shall never catch it." The president and his men, little given to superstition, darted off in the direction of the moving light.