Soon the Nemo had backed away from her moorings and was headed out into Long Island Sound, the most of the divers and those members of the crew not actually engaged in the ship's navigation standing out on deck in enjoyment of the balmy spring morning.
"I guess you would not be averse to knowing something about this craft," began Captain Austin after a half hour's run. He had strolled forward to where Jay, Dick and Larry were watching the backwash of the water as the steel prow of the Nemo sliced its way forward with knife-like precision.
Indeed they would! The three veterans of the war, two of whom had quite a fund of submarine knowledge from their own experiences abroad, were wondering what the Nemo was like. Was it possible that the submersible was a diving bell from which divers could make their exit while it lay on the ocean bed? Were trap doors opened and the pressure of sea water held in abeyance by dense volumes of compressed air? Or did divers go down from the deck of the submarine just as from any other craft? If so, why the submarine, with its narrow, cramped quarters, in preference to any other type of vessel?
These were some of the questions flitting through their minds as they embarked on their first treasure-hunting voyage.
The whole thing was soon to be unfolded by Captain Austin.
"With this craft we do most of our locating," he began. "By that I mean that we are here equipped with special apparatus for finding the lost ships. Many a salvaging company has found that it is one thing to explore a sunken ship or even raise it, but quite another thing to actually locate the submerged ship. It is one thing to know the approximate position where a ship has been sunk, but another thing to know the exact spot. Some charts may give you the exact spot where a ship has foundered, but this spot may measure five miles or more, and if the ship is located in any channel or such parts of the ocean where there is an undertow or heavy undercurrents, the ship will soon be covered with sand, moss or barnacles, and hard for divers to locate."
Plainly, this new salvage company must have some new method of finding ships all their own. The boys were keenly interested and awaiting eagerly the explanation.
"There are several ways to locate lost ships," resumed Captain Austin. "Divers can be sent down with powerful flashlights, but this is a lengthy procedure, and very often takes weeks of patient search. Then again, grappling irons or anchors may be dragged from the salvage ship. This is even less satisfactory than sending down divers. But the Bridgeford Company has a new scheme all its own. And now you shall see."
The Nemo's captain climbed into the turret and motioned the boys to follow him below deck. Dropping straight down into the heart of the ship the boys followed the captain into a small compartment that he was pleased to style "the listening post."