They were passed aboard by the sentry and there on the deck welcomed
by the officers and members of the _Dewey's_ crew. Turned over to big
Bill Witt, one of the crew, they were directed to go below and be
assigned to their quarters.

Down through the hatchway clambered Witt, followed close by Ted and
Jack, and in another moment they found themselves in the engine room.
Electric lights glowed behind wired enclosures. Well aft were the
motors and oil engines, around them switchboards and other electrical
apparatus---a maze of intricate machinery that filled all the stern
space. The air was hazy and smelled strong of oils and gases. Huge
electric fans swept the foul air along the passageway and up through
the hatchways, while other fans placed near the ventilators distributed
the fresh air as it poured into the vessel, drawn by the suction.

From the engine room the boys walked forward into the control
chamber---the base of the conning tower---the very heart and brain of
the undersea ship. Here were the many levers controlling the ballast
tanks, Witt explaining to the boys that the submarine was submerged and
raised again by filling the tanks with water and expelling it again
to rise by blowing it out with compressed air. Here also was the depth
dial and the indicator bands that showed when the ship was going down
or ascending again, the figures being marked off in feet on the dial
just like a clock. Here also was the gyro-compass by which the ship
was steered when submerged; here also the torpedo control by means of
which the torpedoes were discharged in firing. And, yes, here was the
periscope---the great eye of the submarine---a long tube running up
through the conning tower twenty feet above the commander's turret of
steel.