t that moment, sounded the tinkle of a mandolin. It came,
apparently, from the room nearer the front door. The two foreigners
began to hum softly to the accompaniment of their instrument.

"May-be it was a lucky thing it never occurred to the pair to search me,"
murmured the submarine boy. "Probably they wouldn't have left this box
of matches in my possession."

Lighting one of the matches, Jack began to explore. The cellar was much
like any other, and wholly empty. On each side was a little, low window,
probably not large enough for the submarine boy to crawl through. Even
at that the openings had been bricked up and looked as though they would
resist a long assault.

At the rear of the cellar were steps, leading up to a stout-looking
bulkhead. It was padlocked, on the under side, with stout hasp and
staples.

"Nothing doing here, either," muttered Jack. "Yet--hold on--blazes!"

Almost feverishly he felt in an inner pocket. It was there--a case
containing seven or eight small, fine saws and other tools often employed
by machinists in constructing small devices or models. He had been using
some of the instruments on the boat that afternoon.

"Wow!" sputtered the submarine boy, joyously. "And again--some more
_wow_!"

Lighting another match, carefully selecting his saw, and then lighting
still another match, he took a look at the padlock, trying to find some
portion of the ring where the metal was more slender. The saw was
intended for use on metals. After he had made a sufficient notch in the
ring, young Benson was able to work, much of the time, in darkness.

"Blessings on that mandolin," chuckled this industrious young human
beaver. "If it wasn't for their jolly old twang-twang those Italians
might hear my fairy buzz-saw at work."

Yet, though he progressed, what a fearful length of time this task
appeared to take!

"And, if it turns out that there's another padlock in place on the
outside, this will be just another case of love's labor lose," sighed
the boy.

Occasionally, when the mandolin sounds ceased for a few moments, Benson
rested, too. It would never do to take the risk of having his slight
noise overheard.

At last! The saw went through the ring, proclaiming the task all but
finished. First, with trembling fingers, the submarine boy replaced the
saw in its case. Then, with another tough little tool, he started
patiently to bend the severed ends of the ring metal sufficiently f