“No!” Chick had sharp eyes. “It isn’t the modern kind, anyhow. It’s what they call a ‘helicopter,’ Garry.”
Garry looked a second time, carefully.
“Chick’s right,” he murmured to Don. “He says it’s a helicopter—it has the lifting blades that let it rise straight upward and then it has a ‘tractor’ propeller forward that sends it through the air horizontally. It can go higher by giving the horizontal blades more speed, stay almost stationary by adjusting speed, or settle lower by slowing the blades. The tractor prop gives it forward speed. Chick’s right.”
Don nodded. That had been the reason he shook his head, to correct Garry’s terminology, because all the more modern auto-gyros he had seen employed an adjustable-angle horizontal set of blades for both upward and forward speed, and had refined the tractor propeller at the nose.
“But what is a helicopter doing over the swamp?” he wondered, “and where did it come from?”
With a meeting arranged between the amphibian Dragonfly and the big trans-Atlantic liner, there was no time to investigate.
“Does that helicopter have anything to do with the mystery?” Garry spoke through the Gossport tube.
Don could not give an answer.
“It might,” Garry continued. “Only I don’t see just how. The spook ships we saw come together in the sky were old-fashioned biplanes. They weren’t real, either, because you flew right into the cloud, Don.”
The pilot nodded. Their speed rapidly took them Eastward, and away from the swamp; but as he set his course, bearing slightly North, crossing one of the Island’s flying fields at a good altitude and with Barren Island’s new Bennett field back of the right wing’s trailing edge, he puzzled his brain a great deal about that strange ship rising from the swamps. Why was it there at all? Had it been forced to settle there? Or—did someone keep it there? If so, he thought, for what purpose?