ed to the ground. When it struck
there came a roar and a flash and the whole earth seemed to shake. The
helicopter shot upward into the air and forward, both its elevating
fans and its propellers whirling blurs of light. The airplane followed
at its sharpest climbing angle, but was helpless to compete with its
swifter climbing rival.

"He's got away!" groaned Carnes.

"Not yet, old dear!" cried the Doctor hopping with excitement. "He
isn't safe yet. I never told you, but one Breslau gun had been made
and it is on that plane. It has deadly accuracy and is good for
fifteen miles. That's Lieutenant Dreen at the controls and Mason at
the gun."

As he spoke the plane swung around and made a half loop. For a few
yards it flew upside down and then whirled swiftly. As it turned there
came a sharp report and a puff of smoke from its rear cockpit. High
above, the helicopter had ceased climbing and hovered motionless. As
the plane fired, the helicopter shot forward like an arrow from a bow,
and thereby spelled its doom. Not for nothing did Captain Mason bear
the title of the best aerial gunner in the Air Corps. He had foreseen
what the action of his opponent would be and had allowed for just such
a move. Far up in the sky came a blinding flash and a cloud of smoke.
When the smoke cleared the sky was empty, except for a little
scattered debris falling slowly to the ground.

* * * * *

"And that's that!" exclaimed Dr. Bird as he finished his examination
of the underground laboratory with which the gun platform connected.
"The lamp has gone to glory with Breslau's gun model and two of the
best brains of the Young Labor party. I am sure that Stanesky was one
of those two men. I wish the whole gang had been on board."

"Don't you think that this is the end of it, Doctor?" asked Carnes.

"No, Carnes, I don't. We know that the real brains of this outfit is
Saranoff, and Saranoff is still alive. He probably won't try to use
his black lamp again, because I will have a defence against it in a
short time, now that I have seen it in action, but he'll try something
else. The whole object of life to a loyal citizen of Bolshevikia is to
reduce the whole world to the barbarous level in which they hold
Russia, and they will spare no pains or effort to accomplish it. The
greatest obstacle to their success at present is the President of the
United States. He is loved and respected by the whole world, and if he