"Ha!" The General spoke explosively. "That's expansion. That's a tip on their motive power. Expansion of gas. That accounts for the cold and the vapor. Suddenly expanded it would be intensely cold. The moisture of the air would condense, freeze. But how could they carry it? Or"--he frowned for a moment, brows drawn over deep-set gray eyes--"or generate it? But that's crazy--that's impossible!"

"So is the whole matter," the Secretary reminded him. "With the information Mr. Thurston and Mr. Riley have given us, the whole affair is beyond any gage our past experience might supply. We start from the impossible, and we go--where? What is to be done?"

"With your permission, sir, a number of things shall be done. It would be interesting to see what a squadron of planes might accomplish, diving on them from above. Or anti-aircraft fire."

"No," said the Secretary of War, "not yet. They have looked us over, but they have not attacked. For the present we do not know what they are. All of us have our suspicions--thoughts of interplanetary travel--thoughts too wild for serious utterance--but we know nothing.

"Say nothing to the papers of what you have told me," he directed Thurston. "Lord knows their surmises are wild enough now. And for you, General, in the event of any hostile move, you will resist."

"Your order was antic.i.p.ated, sir." The General permitted himself a slight smile. "The air force is ready."

"Of course," the Secretary of War nodded. "Meet me here to-night--nine o'clock." He included Thurston and Riley in the command. "We need to think ... to think ... and perhaps their mission is friendly."

"Friendly!" The two flyers exchanged glances as they went to the door.

And each knew what the other was seeing--a viscous ocherous ma.s.s that formed into a head where eyes devilish in their hate stared coldly into theirs....

"Think, we need to think," repeated Thurston later. "A creature that is just one big hideous brain, that can think an arm into existence--think a head where it wishes! What does a thing like that think of? What beastly thoughts could that--that _thing_ conceive?"

"If I got the sights of a Lewis gun on it," said Riley vindictively, "I'd make it think."

"And my guess is that is all you would accomplish," Thurston told him.

"I am forming a few theories about our visitors. One is that it would be quite impossible to find a vital spot in that big h.o.m.ogeneous ma.s.s."

The pilot dispensed with theories: his was a more literal mind. "Where on earth did they come from, do you suppose, Mr. Thurston?"

They were walking to their hotel. Thurston raised his eyes to the summer heavens. Faint stars were beginning to twinkle; there was one that glowed steadily.

"Nowhere on earth," Thurston stated softly, "nowhere on earth."

"Maybe so," said the pilot, "maybe so. We've thought about it and talked about it ... and they've gone ahead and done it." He called to a newsboy; they took the latest editions to their room.

The papers were ablaze with speculation. There were dispatches from all corners of the earth, interviews with scientists and near scientists.

The machines were a Soviet invention--they were beyond anything human--they were harmless--they would wipe out civilization--poison gas--blasts of fire like that which had enveloped the army flyer....

And through it all Thurston read an ill-concealed fear, a reflection of panic that was gripping the nation--the whole world. These great machines were sinister. Wherever they appeared came the sense of being watched, of a menace being calmly withheld. And at thought of the obscene monsters inside those spheres, Thurston's lips were compressed and his eyes hardened. He threw the papers aside.

"They are here," he said, "and that's all that we know. I hope the Secretary of War gets some good men together. And I hope someone is inspired with an answer."

"An answer is it?" said Riley. "I'm thinkin' that the answer will come, but not from these swivel-chair fighters. 'Tis the boys in the c.o.c.kpits with one hand on the stick and one on the guns that will have the answer."

But Thurston shook his head. "Their speed," he said, "and the gas!

Remember that cold. How much of it can they lay over a city?"

The question was unanswered, unless the quick ringing of the phone was a reply.

"War Department," said a voice. "Hold the wire." The voice of the Secretary of War came on immediately.

"Thurston?" he asked. "Come over at once on the jump, old man. h.e.l.l's popping."

The windows of the War Department Building were all alight as they approached. Cars were coming and going; men in uniform, as the Secretary had said, "on the jump." Soldiers with bayonets stopped them, then pa.s.sed Thurston and his companion on. Bells were ringing from all sides.

But in the Secretary's office was perfect quiet.

General Lozier was there, Thurston saw, and an imposing array of gold-braided men with a sprinkling of those in civilian clothes. One he recognized: MacGregor from the Bureau of Standards. The Secretary handed Thurston some papers.

"Radio," he explained. "They are over the Pacific coast. Hit near Vancouver; a.s.sociated Press says city destroyed. They are working down the coast. Same story--blast of hydrogen from their funnel shaped base.

Colder than Greenland below them; snow fell in Seattle. No real attack since Vancouver and little damage done--" A message was laid before him.

"Portland," he said. "Five mystery ships over city. Dart repeatedly toward earth, deliver blast of gas and then retreat. Doing no damage.

Apparently inviting attack. All commercial planes ordered grounded.

Awaiting instructions.

"Gentlemen," said the Secretary, "I believe I speak for all present when I say that, in the absence of first hand information, we are utterly unable to arrive at any definite conclusion or make a definite plan.

There is a menace in this, undeniably. Mr. Thurston and Mr. Riley have been good enough to report to me. They have seen one machine at close range. It was occupied by a monster so incredible that the report would receive no attention from me did I not know Mr. Thurston personally.

"Where have they come from? What does it mean--what is their mission?

Only G.o.d knows.

"Gentlemen, I feel that I must see them. I want General Lozier to accompany me, also Doctor MacGregor, to advise me from the scientific angle. I am going to the Pacific Coast. They may not wait--that is true--but they appear to be going slowly south. I will leave to-night for San Diego. I hope to intercept them. We have strong air-forces there; the Navy Department is cooperating."

He waited for no comment. "General," he ordered, "will you kindly arrange for a plane? Take an escort or not as you think best.

"Mr. Thurston and Mr. Riley will also accompany us. We want all the authoritative data we can get. This on my return will be placed before you, gentlemen, for your consideration." He rose from his chair. "I hope they wait for us," he said.

Time was when a commander called loudly for a horse, but in this day a Secretary of War is not kept waiting for transportation. Sirening motorcycles preceded them from the city. Within an hour, motors roaring wide open, propellers ripping into the summer night, lights slipping eastward three thousand feet below, the Secretary of War for the United States was on his way. And on either side from their plane stretched the arms of a V. Like a flight of gigantic wild geese, fast fighting planes of the Army air service bored steadily into the night, guarantors of safe convoy.

"The Air Service is ready," General Lozier had said. And Thurston and his pilot knew that from East coast to West, swift scout planes, whose idling engines could roar into action at a moment's notice, stood waiting; battle planes hidden in hangars would roll forth at the word--the Navy was cooperating--and at San Diego there were strong naval units, Army units, and Marine Corps.

"They don't know what we can do, what we have up our sleeve: they are feeling us out," said the Secretary. They had stopped more than once for gas and for wireless reports. He held a sheaf of typewritten briefs.

"Going slowly south. They have taken their time. Hours over San Francisco and the bay district. Repeating same tactics; fall with terrific speed to cushion against their blast of gas. Trying to draw us out, provoke an attack, make us show our strength. Well, we shall beat them to San Diego at this rate. We'll be there in a few hours."

The afternoon sun was dropping ahead of them when they sighted the water. "Eckener Pa.s.s," the pilot told them, "where the Graf Zeppelin came through. Wonder what these birds would think of a Zepp!

"There's the ocean," he added after a time. San Diego glistened against the bare hills. "There's North Island--the Army field." He stared intently ahead, then shouted: "And there they are! Look there!"

Over the city a cl.u.s.ter of meteors was falling. Dark underneath, their tops shone like pure silver in the sun's slanting glare. They fell toward the city, then buried themselves in a dense cloud of steam, rebounding at once to the upper air, vapor trailing behind them.

The cloud billowed slowly. It struck the hills of the city, then lifted and vanished.