But the way was by no means free yet; huge lumps of ice were suspended upon the neighboring icebergs, and their fall threatened to close the exit.
Hatteras saw their situation in a flash of the eye.
"Wolston!" he shouted.
The gunner hastened to him.
"Captain!" he said.
"Put a triple charge in the forward gun, and ram it in as hard as possible!"
"Are we going to batter the iceberg down with cannon-balls?" asked the doctor.
"No," answered Hatteras. "That would do no good. No balls, Wolston, but a triple charge of powder. Be quick!"
In a few moments the gun was loaded.
"What is he going to do without a ball?" muttered Shandon between his teeth.