Ted and Jack hastened to follow their comrades down the hatchway. A
sea-gull flapping by squawked shrilly at them as the boys waited their
turn at the ladder. Instinctively they took another look around them
before dipping into the hold of the _Dewey_. They realized that here,
indeed, was the real thrill of submarining. The cap was lowered at
last and secured, and the crew hastened to their posts amid the
artificial light and busy hum of the ship's interior.

Now the Brighton boys were to learn how the _Dewey_ was to be submerged!
For one thing they noted that the oil engines used for surface cruising
were shut off and the locomotion of the vessel switched over to the
electric drive of the storage batteries. But their attention was
directed chiefly to Navigating Officer Binns, who had taken up his
position before a row of levers and water gauges amidships.

"Pump three hundred pounds into No. 1," was the command given by Binns.
One of the levers was thrown over, and immediately could be heard the
swirling of water. The boys were unable to grasp the full meaning of
what was going on until Bill Witt shuffled up and said: "I'll put you
fellows wise to what's going on, if you want me to."

Ted and Jack were glad to know what it was all about and listened
attentively to the commands of the navigating officer and the
interpretations given by their new-found friend. Bill explained that
the process of diving was called "trimming" in submarine cruising, and
that the pumping of the water being directed by Binns was done to fill
the ballast tanks, thus increasing the displacement of the _Dewey_ and
causing it to settle in the water. First one tank was filled, and then
another, until the vessel was submerged on an even keel. This was a