air, clearing the leading truck by inches. The truck halted and hastily mounted a machine gun.

"Too late!" laughed the lieutenant. "Now it's our turn for some fun."

He tapped the key of his radio transmitter. In a few seconds he received an answer.

"They have reduced Fort Novadwinskaja," he reported to the rear cockpit, "but they don't know what to fire at next. Their largest guns will reach the factory easily. Shall I start some fireworks?"

"You may fire when ready, Gridly," chuckled Dr. Bird.

Again the lieutenant depressed his key. From their altitude of four thousand feet, they could see the Denver. From its forward turret came a puff of smoke. There were a few moments of pause and then a cloud of black rose from the plain below them, half a mile from the factory. McCready reported the position of the burst to the ship. A second shell burst beyond the factory and the third just in front of it.

"It's a clear bracket," said McCready. "Now watch the gun. I'll give them a salvo."

From the side of the Denver came a cloud of black smoke as all of her turret guns fired in unison. The aim was perfect. For a few moments all was quiet and then the factory disappeared in a smother of bursting high explosive shells.

Hardly had the shells landed than a terrific sheet of lightning ripped across the sky. The thunderclap which seemed to come simultaneously, rocked the plane like a feather. Sheet after sheet of lightning illuminated the sky while the roar of thunder was continuous. Rain fell in solid sheets. Even as they watched, it began to turn into snow. The air grew bitterly cold.

"The solar magnet is wrecked," shouted the doctor, "and these storms are the efforts of nature to return to normal."

"If they get any worse, we're doomed."

"But in a good cause."

Through the storm the plane raced. Suddenly the motor died with sickening suddenness.

"Our haywire battery connections are gone," shouted McCready. "Say your prayers."

The wind tossed the plane about like a feather. Rapidly it lost altitude. A building loomed up before them. As a crash seemed imminent, a gust of wind caught the plane and tossed it up into the air again. For several minutes the ground could not be seen through the rain. Suddenly the plane hit an airpocket and dropped like a stone. With a splash it fell into the sea. A rift came for a moment in the curtain of rain.

"Look!" cried Carnes.

A hundred yards away, the Denver rode at anchor.

"I'm only sorry about one thing," said Carnes ten minutes later as they changed to dry clothes aboard the battle cruiser, "and that is that Saranoff wasn't in the factory when that salvo fell on it."

"I'm glad he was away," replied Dr. Bird. "With him absent, we succeeded in destroying it. If he had been there, our task would have been more difficult and perhaps impossible. I am an enemy of Saranoff's, but I don't underrate his colossal genius."