attention to what they were passing. Already
they had seen it twice. But never had either of them seen a craft like
that they were in. It was one of those long, low racing boats, steered
with a wheel like a motor-car, and slopingly decked over in front to
shield the driver. And it roared like an aeroplane as it tore through
the water. For the boys in the boat were rushing toward their goal
almost as swiftly as their comrades on land.

What most interested Henry and Roy was the array of buttons and knobs
and other instruments on the dashboard, like the lighting buttons and
speedometer on an automobile.

"I wonder what they are for," said Roy to Henry. "I never saw a boat
like this before."

"Nor I, either," replied Henry.

"Right you are," said one of their companions. "There probably isn't
another like it. It's both a motor-boat and an electric boat.
Sometimes we have to be very quiet about our work and then we would
never dare go roaring along as we are now. You can hear us a mile
away. So we have an electric motor and storage batteries for quiet
work. When we run by electricity, we don't make any more noise than a
swan."

The boys expressed their admiration. "And nobody could see you,
either," said Roy. "The boat's exactly the color of the water. When
it's as dark as this, I'll bet you couldn't see it fifty yards away."

"Well, you may have a chance to test your belief," said the agent with
a smile.

"What do you think will happen?" asked Roy.

"I don't know. But when that German motor-boat goes into Echo Bay,
we've got to go after it; and we don't dare be seen, either."

"What's the bay like?" inquired Henry.

"It's an irregular little sheet of water with several small islands in
it; and if these Germans go clear in, we'll nab them easily. But if
they don't, we may have a lively chase."

On rushed the motor-boat. Past Classon Point, past the long projecting
finger of land known as Throgs Neck, with Fort Schuyler at its
extremity, then northward again into ever widening waters, past Elm
Point, and Hewlett Point, and Barker Point until they were fairly in
the wider reaches of Long Island Sound.

On the right loomed the high and precipitous shores of Long Island,
hardly visible in the cloudy darkness. On the left, far across the
waving waters, was the unseen ragged coast of the mainland, broken by a
hundred irregular indentations, studded with numberless little
promontories, and fringed