at he was losing strength, and that to regain the mouth of the
tunnel he would need all that was left to him. But he still pushed
forward. The air had now turned foul; his head and chest ached, as
when he had been long under water, and his legs were like lead. He was
just upon the point of abandoning his purpose when there rose before
him a solid wall. He staggered to it, and, leaning against it,
joyfully beat upon it with his fists. He knew that at last only a few
feet separated him from the man he had set out to save. So great was
his delight and so anxious was he that Rojas should share in it, that
without considering that no slight sound could penetrate the barrier,
he struck three times upon it with the butt of his revolver, and then,
choking and gasping like a drowning man, staggered back toward the
opening. Half-way he was met by McKildrick and Peter, who, finding no
pressure on the end of the rope, had drawn it to them and, fearing for
Roddy's safety, had come to his rescue. They gave him an arm each,
and the fresh air soon revived him. He told McKildrick what he had
seen, and from his description of the second wall the engineer
described how it should be opened.

"But without a confederate on the other side," he said, "we can do
nothing."

"Then," declared Roddy, "the time has come to enroll Vicenti in the
Honorable Order of the White Mice."

On their return to Roddy's house they sent for Vicenti, and Roddy,
having first forced him to subscribe to terrifying oaths, told the
secret of the tunnel.

Tears of genuine happiness came to the eyes of the amazed and
delighted Venezuelan. In his excitement he embraced Roddy and
protested that with such companions and in such a cause he would
gladly give his life. McKildrick assured him that when he learned of
the part he was to play in the rescue he would see that they had
already taken the liberty of accepting that sacrifice. It was
necessary, he explained, that the wall between the tunnel and the cell
should fall at the first blow. An attempt to slowly undermine it, or
to pick it to pieces, would be overheard and lead to discovery. He
therefore intended to rend the barrier apart by a single shock of
dynamite. But in this also there was danger; not to those in the
tunnel, who, knowing at what moment the mine was timed to explode,
could retreat to a safe distance, but to the man they wished to set
free. The problem, as McKildrick pointed it out, was to make the
cha