"Land at once," requested the Secretary. A flash of silver countermanded the order.

It hung there before them, a great gleaming globe, keeping always its distance ahead. It was elongated at the base, Thurston observed. From that base shot the familiar blast that turned steamy a hundred feet below as it chilled the warm air. There were round orifices, like ports, ranged around the top, where an occasional jet of vapor showed this to be a method of control. Other spots shone dark and gla.s.sy. Were they windows? He hardly realized their peril, so interested was he in the strange machine ahead.

Then: "Dodge that vapor," ordered General Lozier. The plane wavered in signal to the others and swung sharply to the left. Each man knew the flaming death that was theirs if the fire of their exhaust touched that explosive mixture of hydrogen and air. The great bubble turned with them and paralleled their course.

"He's watching us," said Riley, "giving us the once over, the slimy devil. Ain't there a gun on this ship?"

The General addressed his superior. Even above the roar of the motors his voice seemed quiet, a.s.sured. "We must not land now," he said. "We can't land at North Island. It would focus their attention upon our defenses. That thing--whatever it is--is looking for a vulnerable spot.

We must.... Hold on--there he goes!"

The big bulb shot upward. It slanted above them, and hovered there.

"I think he is about to attack," said the General quietly. And, to the commander of their squadron: "It's in your hands now, Captain. It's your fight."

The Captain nodded and squinted above. "He's got to throw heavier stuff than that," he remarked. A small object was falling from the cloud. It pa.s.sed close to their ship.

"Half-pint size," said Cyrus Thurston, and laughed in derision. There was something ludicrous in the futility of the attack. He stuck his head from a window into the gale they created. He sheltered his eyes to try to follow the missile in its fall.

They were over the city. The criss-cross of streets made a grill-work of lines; tall buildings were dwarfed from this three thousand foot alt.i.tude. The sun slanted across a projecting promontory to make golden ripples on a blue sea and the city sparkled back in the clear air. Tiny white faces were ma.s.sed in the streets, huddled in cl.u.s.ters where the futile black missile had vanished.

And then--then the city was gone....

A white cloud-bank billowed and mushroomed. Slowly, it seemed to the watcher--so slowly.

It was done in the fraction of a second. Yet in that brief time his eyes registered the chaotic sweep in advance of the cloud. There came a crashing of buildings in some monster whirlwind, a white cloud engulfing it all.... It was rising--was on them.

"G.o.d," thought Thurston, "why can't I move!" The plane lifted and lurched. A thunder of sound crashed against them, an intolerable force.

They were crushed to the floor as the plane was hurled over and upward.

Out of the mad whirling tangle of flying bodies, Thurston glimpsed one clear picture. The face of the pilot hung battered and blood-covered before him, and over the limp body the hand of Slim Riley clutched at the switch.

"Bully boy," he said dazedly, "he's cutting the motors...." The thought ended in blackness.

There was no sound of engines or beating propellers when he came to his senses. Something lay heavy upon him. He pushed it to one side. It was the body of General Lozier.

He drew himself to his knees to look slowly about, rubbed stupidly at his eyes to quiet the whirl, then stared at the blood on his hand. It was so quiet--the motors--what was it that happened? Slim had reached for the switch....

The whirling subsided. Before him he saw Slim Riley at the controls. He got to his feet and went unsteadily forward. It was a battered face that was lifted to his.

"She was spinning," the puffed lips were muttering slowly. "I brought her out ... there's the field...." His voice was thick; he formed the words slowly, painfully. "Got to land ... can you take it? I'm--I'm--"

He slumped limply in his seat.

Thurston's arms were uninjured. He dragged the pilot to the floor and got back of the wheel. The field was below them. There were planes taxiing out; he heard the roar of their motors. He tried the controls.

The plane answered stiffly, but he managed to level off as the brown field approached.

Thurston never remembered that landing. He was trying to drag Riley from the battered plane when the first man got to him.

"Secretary of War?" he gasped. "In there.... Take Riley; I can walk."

"We'll get them," an officer a.s.sured him. "Knew you were coming. They sure gave you h.e.l.l! But look at the city!"

Arms carried him stumbling from the field. Above the low hangars he saw smoke clouds over the bay. These and red rolling flames marked what had been an American city. Far in the heavens moved five glinting specks.

His head reeled with the thunder of engines. There were planes standing in lines and more erupting from hangars, where khaki-clad men, faces tense under leather helmets, rushed swiftly about.

"General Lozier is dead," said a voice. Thurston turned to the man. They were bringing the others. "The rest are smashed up some," the officer told him, "but I think they'll pull through."

The Secretary of War for the United States lay beside him. Men with red on their sleeves were slitting his coat. Through one good eye he squinted at Thurston. He even managed a smile.

"Well, I wanted to see them up close," he said. "They say you saved us, old man."

Thurston waved that aside. "Thank Riley--" he began, but the words ended in the roar of an exhaust. A plane darted swiftly away to shoot vertically a hundred feet in the air. Another followed and another. In a cloud of brown dust they streamed endlessly out, zooming up like angry hornets, eager to get into the fight.

"Fast little devils!" the ambulance man observed. "Here come the big boys."

A leviathan went deafeningly past. And again others came on in quick succession. Farther up the field, silvery gray planes with rudders flaunting their red, white and blue rose circling to the heights.

"That's the Navy," was the explanation. The surgeon straightened the Secretary's arm. "See them come off the big airplane carriers!"

If his remarks were part of his professional training in removing a patient's thoughts from his pain, they were effective. The Secretary stared out to sea, where two great flat-decked craft were shooting planes with the regularity of a rapid fire gun. They stood out sharply against a bank of gray fog. Cyrus Thurston forgot his bruised body, forgot his own peril--even the inferno that raged back across the bay: he was lost in the sheer thrill of the spectacle.

Above them the sky was alive with winged shapes. And from all the disorder there was order appearing. Squadron after squadron swept to battle formation. Like flights of wild ducks the true sharp-pointed Vs soared off into the sky. Far above and beyond, rows of dots marked the race of swift scouts for the upper levels. And high in the clear air shone the glittering menace trailing their five plumes of gas.

A deeper detonation was merging into the uproar. It came from the ships, Thurston knew, where anti-aircraft guns poured a rain of sh.e.l.ls into the sky. About the invaders they bloomed into cl.u.s.ters of smoke b.a.l.l.s. The globes shot a thousand feet into the air. Again the sh.e.l.ls found them, and again they retreated.

"Look!" said Thurston. "They got one!"

He groaned as a long curving arc of speed showed that the big bulb was under control. Over the ships it paused, to balance and swing, then shot to the zenith as one of the great boats exploded in a cloud of vapor.

The following blast swept the airdrome. Planes yet on the ground went like dry autumn leaves. The hangars were flattened.

Thurston cowered in awe. They were sheltered, he saw, by a slope of the ground. No ridicule now for the bombs!

A second blast marked when the gas-cloud ignited. The billowing flames were blue. They writhed in tortured convulsions through the air. Endless explosions merged into one rumbling roar.

MacGregor had roused from his stupor; he raised to a sitting position.

"Hydrogen," he stated positively, and pointed where great volumes of flame were sent whirling aloft. "It burns as it mixes with air." The scientist was studying intently the mammoth reaction. "But the volume,"