As the lad spoke he took a ball of strong string from his pocket and tied one end to the cage which lay at the bottom of the shaft.
"Now we can go anywhere we please," he chuckled, "and when we want to return, all we've got to do is to follow the string."
"Quite an idea!" laughed Tommy.
The boys proceeded along the gangway, walking between the rails of the tramway by means of which the coal was delivered at the bottom of the shaft. The experience was a novel one to them. The dark walls of the passage, the echoes which came from the counter gangways, the monotonous dripping of water, as it seeped through seams and crevices in the rock, all gave a weird and uncanny expression to the place.
After walking for some distance the boys came to a level which showed several inches of water.
"We can't wade through that!" Tommy declared.
"Well," Sandy suggested, "if we go back a little ways, we can follow a cross heading and get into the mine by another way."
The boys followed this plan, and, after winding about several half-loaded cars which had been left on the tramway, found themselves in a large chamber from which numerous benches were cut.
"Where does all this gas come from?" asked Tommy stopping short and putting a hand to his nose.
"There must be a blower somewhere," Sandy explained.