What the captain had in mind was the equalizing of pressures. Every time the Nautilus was lowered deeper in the water it was necessary to take a greater air pressure into the big diving chamber before the aquascope could be raised. The depth always showed on the depth-dial. Also the amount of air in the chamber was registered by a clock-like gauge. In a crevice on the steel wall hung a small framed schedule under glass showing the air pressure necessary to suit varying depths. As yet the process had not been made automatic. The engineer had to keep this whole proposition constantly in mind.
"See anything yet, Montey?" the captain asked of the superintendent as the Nautilus dropped slowly away into the depths.
Nothing by way of identification was yet discernible, even though the superintendent had turned on the powerful submarine searchlights with which the Nautilus was equipped, and, with the assistance of Jay, was sweeping the sides of the derelict.
For several minutes they cast about in the water, when of a sudden Jay exclaimed eagerly:
"Hold right there."
Instantly Captain Austin checked the movement of the diving outfit.
"There! That looks like E-70 to me," exclaimed Jay. The superintendent moved over beside him and as Jay withdrew from his port station peered out through the water.
With the glaring light of the Nautilus' reflectors shining more dazzlingly at this close range than any extraneous natural light that filtered through from the sun, Superintendent Brown beheld the crude yet only partially obliterated legend: "E-70."
"Fine and dandy!" he shouted. "It's proof positive. The craft out there is none other than the lost U. S. submarine chaser that was rammed last summer, as Captain Austin has told us. A fine feather in the cap of all of us. A find the first day out."