"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 with islands as a woman's throat is girt with a necklace of beads. Ahead of them stretched untold miles of gently heaving water. And there, too, blazed two beacons to point the path for mariners—the Sands Point Light, topping the eastern bluff, and the fiery eye of Execution Rocks, that reared their jagged pinnacles far out from the shore, to tear the bottoms of unwary ships.