through the fort.

The magazine had blown up. It was a wonder that the prison itself had
not been hurled to the ground.

"Thank Heaven, we have escaped!" exclaimed Oliver.

The attacking vessels still continued firing, and after a short interval
the fort once more replied, but evidently with fewer guns than before.

A crash was heard over their heads, and down fell a mass of timber,
plank, and tiles just above the door. Looking up, the clear sky could
be seen, from out of which a crescent moon shone brightly.

No one was injured, for the shot, having torn its way through the roof,
had fallen outside.

"Hurrah! thanks to that shot, we may make our escape out of this, for
the Frenchmen are too much engaged at the guns to see us!" cried Jack.
"Let us get down to the shore, and when we are once there we may manage
to find our way aboard the ship. The chances are we shall find some
fishing boat or other on the beach. May we try, sir, what we can do?"

"What do you say, Oliver? Shall we make the attempt Jack proposes?"
asked Rayner. "If we go we must take Le Duc with us, I wish that we
could find something to knock off his chains, and we might set the other
poor fellows at liberty."

To climb out would be no difficult matter, as Brown found that by
standing on Tom's and Jack's shoulders he could reach the lower part of
the roof. But Rayner positively refused to go without first setting Le
Duc at liberty. He told Brown to try and dislodge a piece of stone from
the wall with which they might break the prisoners' chains.

Suddenly Tom recollected that he had stowed away one of the files which
Le Duc himself had brought in his pocket.

"Hand it here," cried Rayner; and heat once began filing away.

In the meantime Brown managed to get hold of one of the upper stones of
the wall. It was hard, and had a sharp side.

"Here it is, sir," he said, clambering down and bringing it to Rayner.
A few blows on the bench served to sever the link already partly filed
through.

"Oh! set us free, monsieur?" cried the other prisoners.

"What does he say?" asked Brown.

"There won't be time to set you both free, but I'll see what I can do
for one of you;" and he began filing away, and with the help of the
stone he managed to liberate the arm of one of the men.

"Here, take the file and see what you can do for your comrade," he said.

The rest of the party had in the meantime begun to mount the wall.

CHAPTER THIRT