They moved toward the rear of the house. A hullabaloo of whistles broke out in the harbor. The girl turned toward the professor.
"Teddy already?"
The professor frowned.
"He hasn't had time." He went to a window and looked out, inspecting the sky keenly. A slender black splinter hung suspended in the air. The professor flung open the window, and a musical humming filled the room. As they watched a smoking object detached itself from the black flyer and fell downward.
"That must be Varrhus," said the professor.
A winged flyer with the insignia of the American aviation corps painted on the under surface of its wings darted into their field of vision. Black smoke trailed behind it as it shot toward the sinister black craft. There was an instant's pause, and then little puffs of white mist appeared before the propeller of the aëroplane.
"He's firing his machine gun!" said the reporter excitedly.
As he spoke the black flyer dropped like a stone, and the American plane shot above it. Almost instantly the black flyer checked in mid-air and rose vertically with amazing speed. The American plane drove on for a second, and then wavered. It began to climb, stalled, and dropped toward the earth in a series of side slips and maple-leaf turns. It came down erratically, crazily.
"Killed!" said the professor with compressed lips.
His daughter uttered a cry: