"Now, look at the access tube." The captain was pointing now to the long cylindrical tube that led away forward from the bow of the Jules Verne. "That is the way we get into the Nautilus. Oh, yes, the Nautilus is really the big secret of our plan. It is the small diving compartment that sets out there in the water."
"You mean the flatiron-shaped section nearly awash?" queried Dick.
"Exactly," replied the captain. "Call it a diving bell if you will. What we have here is two distinct vessels connected by a long passageway. 'The Subway' as Superintendent Brown calls it. First we go aboard the Jules Verne. Then we find the lost ship on the bottom of the sea that we want to work on. When we are ready we lower the access tube and the Nautilus right over the wreck. Down goes the tube. Down we climb just like walking down an enclosed ladder. Through the air-lock—and there we are in the Nautilus! Don't you get it?"
Jay and Dick nodded understandingly.
"Tell us more about the Nautilus," asked Dick inquisitively.
"Well, the Nautilus is nothing more or less than a submarine diving chamber," explained Austin. "It is set on the end of the access tube by means of a huge differential that enables it to work back and forth like a flexible hinge. Under the Nautilus and under the access tube are ballast tanks. You boys who have been in the submarine and the diving business in the Navy know how easily that works. We raise or lower the diving compartment simply by 'trimming,' or blowing the tanks. In case the ballast apparatus gets out of commission, we have the Nautilus suspended on cables. They will bring her up again if she gets stuck down there."
"Oh, I commence to see it now," interrupted Jay. "The mother boat, or Jules Verne, is like your shoulder. The access tube through which you effect an entrance into the Nautilus is like your arm. The Nautilus is like your hand. You raise or lower at will, and you can put the Nautilus down in the water at a distance equal to the length of the access tube, or arm. Isn't that it?"
"Exactly, my boy," countered "Cap" Austin. "And can't you see the advantages of such an equipment? Heretofore, we have had to send you divers down to go groping around over the bottom of the sea after we found our quarry. You had to prod and dig and scratch around to find out the condition of the lost ship, how best she was to be entered, and all that. And by that time, you were pretty well played out and had to stop until you got in good trim again."
"To say nothing of the tides and the storms that kept pulling us away from our work," added Dick.