see exactly what the interior of a submarine torpedo boat was like.

A level floor extended throughout the entire length of the "Pollard."
Below this floor, reached by hatchways, were various small compartments
for storage. Under the level of this floor, too, were the "water tanks."
These were tanks that, when the craft lay or moved on the surface of the
ocean, were to contain only air. Whenever it was desired to sink the
torpedo boat, valves operated from the central room of the boat could be
opened so that the water tanks would fill, and the weight of the water
would sink the boat. In diving, the forward tanks could be filled
first, and then, when the desired depth was reached, the other tanks
could be filled entirely, or partly, in such a way as to control depth
and position.

With the boat below the surface, and the commander wishing to return to
the surface, compressed air could be forced into the water tanks,
expelling all the water in them, or a part of the water, if preferred.
The valves would then operate to keep more water from entering.

On the surface the "Pollard" was intended to be run by a powerful
six-cylinder gasoline engine. When below the surface the boat was to
be propelled by electric power supplied from storage batteries. Below
the waves the gasoline engine could not be used, as such an engine
consumes air and also creates bad vapors.

On the morning when our two young friends went to work the electrical
engine was fully installed, and had been tested. The gasoline engine
was in place, but the fittings had yet to be finished. In the course
of this latter work the necessary connections were to be made between
gasoline engine and dynamo.