"Look! the door is broken open!" Ford's comparison was justified by the appearance of an excavation, the depth of which could not be calculated.

Harry was about to spring through the opening; but the engineer, though excessively surprised to find this cavity, held him back.

"Allow time for the air in there to get pure," said he.
"Yes! beware of the foul air!" said Simon.
A quarter of an hour was passed in anxious waiting.

The lantern was then fastened to the end of a stick, and introduced into the cave, where it continued to burn with unaltered brilliancy.

"Now then, Harry, go," said Starr, "and we will follow you." The opening made by the dynamite was sufficiently large to allow a man to pass through.