hed twin screws of a
novel design that gave great speed and controlled the submarine easily.
The gasoline engines were of fifteen hundred horse-power each, and the
electrical had a trifle lower capacity.

In the engine room, too, were the powerful pumps used for emptying or
filling the submarine's submergence tanks as it was desired to rise or
descend. Aft of the engine room came the gasoline tanks, the storage
batteries, and some minor machinery, such as an ice-making plant, air
compressor, and so on. In the engine room, too, was a comfortable
upholstered lounge for the engineer on duty to rest upon. Several dials
and gauges were on the walls of this compartment, enabling the engineer
to know at all times under just what conditions the submarine was
proceeding.

It was in the engines themselves that the inventor had excelled all
other types of submarines, as well as in the peculiar attributes of the
hull. Extra tanks were provided whereby, in the event of the main supply
of gasoline giving out at any time, the _Peacemaker_ could be run quite
a distance on those alone.

"How long could you stay below the surface?" asked Rob, as they came
back into the main cabin once more. There they took their seats on broad
leather divans which at night time could be converted into beds or bunks
by pulling a lever which caused them to turn over and reveal a snug
resting place.

"I have not yet made an exhaustive test of that," rejoined Mr. Barr,
"but I estimate that we could remain below, if necessary, forty-eight
hours."

"Forty-eight hours!" gasped Rob incredulously.

The inventor nodded calmly.

"My air purifying device makes this supposable. I have a plan by which
fresh, pure air is almost manufactured. At the same time the foul air is
forced out."

"I suppose you boys are aching to take a trip," laughed Ensign
Hargreaves.

"Aching is no word for it," Rob assured him.

"Well, you may have a chance to-morrow," said Mr. Barr; "I am going to
test out the whole craft thoroughly, and you boys can come along if I
go."

For the next five minutes nothing could be heard but enthusiastic
shouts. The boys fairly went wild with delight at the prospect of a trip
below the ocean's surface. Soon afterward the party emerged from the
submarine in time to see the _Seneca_ making out to sea on her return
journey. She carried letters from the boys to their families, as they
were by no means sure when they would get the next opportunit