"What if a storm came up?"

"It is always calm in the Sargasso Sea, so Bluewater Bill told me. The
great mass of tangled weed prevents the waves breaking while the
severest storm may be raging all about. Nothing more alarming than a
gentle swell ever disturbs its repose."

Frank, the mechanical-minded, already had fished out an envelope, and
on its back was scribbling the rough outlines of the aluminum
pontoons, he had frequently made a mental resolve to attach to the
aeroplane, so as to render it safe on the water as well as over the
land. He had no intention then of embarking on the enterprise that
Billy had outlined--at least he didn't think he had--but any
suggestion of aeroplane improvement always interested the boy keenly
and set his inventive mind at work.

While the three boys had been discussing Bluewater Bill's strange tale
there had been a fourth auditor whose presence, had they known it,
would have caused them to talk in lowered voices. Sanborn, the
mechanic, from behind the canvas screen where he was supposed to have
been eating his breakfast, had been listening greedily to every word
the young reporter said. His eyes fairly burned in his head as he
listened and a half-formed resolve entered his mind.

There might be other persons who would be interested in learning of
the treasure ship which Sanborn's greedy mind already had regarded as
a reality.

"Guess I'll take a run down to Bluewater Bill's myself to-night," he
said to himself as he prepared to go to work on the aeroplane, at