proceeded to get up steam.

The propelling power of the craft has already been described. In order
to make the ship sink beneath the water all that was necessary was to
incline the rudder and open certain valves in the four tanks, when the
water, rushing in, would sink her. There was a tank on either side, and
one each fore and aft. If it was desired to sink straight down all four
tanks were filled at once. If the professor wanted to descend slanting
either to the front or back, only one of the end tanks was filled,
according to the direction desired. The deflecting rudder also aided
greatly in this movement.

To cause the ship to rise the tanks were emptied of the water by means
of powerful pumps. The filling of the tanks, as well as the emptying of
them, the starting or stopping of the engine that moved the boat, as
well as the control of most of the important machinery on the craft
could be accomplished from the conning or steering tower, as well as
from the engine-room.

There were numerous gages to tell the depth to which the ship had sunk,
the steam pressure, density of the water, and other necessary details.

There were dynamos to make light, motors to run the pumps, and a great
storage battery, so that in case of a breakdown to the turbine engine
the craft could be run entirely by electricity for a time.

The cooking was all done by this useful current, and all that was
necessary to make a cup of coffee or fry a beefsteak was to turn a small
switch of the electric stove.

The professor was busy over the machine for generating gas, that
furnished the heat to create steam. Soon a hissing told that it was
working. In a few minutes the hum and throb of the engine told that it
was ready to start.

"We are only going down a little way," the professor said, "and only
going to travel a short distance under water for the first time. I think
there is no danger, but if any of you want to back out, now is your
chance."

No one seemed inclined to withdraw, though Mark said afterward he
thought Washington got as pale as it is possible for a colored man to
get.

"We will all put on life preservers," the inventor went on, "and one of
you will be stationed near the emergency exit. In case anything goes
wrong, and I cannot make the ship rise, by pulling the lever the top of
the craft will be forced off, and, we can at least save our lives. I
think we are all ready now. Mark, you clamp down the manhole cover, and
Jack,