Chapter III: Prologue (2)

"Dick, I think you have 'loaded the dice' in a way that is even more lucrative than any other method ever invented! If the principle of this machine is what I think it is, you have certainly solved the secret of a sufficiently absorbing area for a solar engine."

"Well," remarked the elderly Morey, shivering a bit in the chill air of the room, "loaded dice have long been noted for their ability to make money, but I don't see how that explains that working model of an Arctic tornado. _Burr_ it's still too cold in here. I think he'll need considerable area for heat absorption from the sun, for that engine certainly does cool things down! What's the secret?"

"The principle is easy enough, but I had considerable difficulty with the application. I think it is going to be rather important though--"

"Rather important," broke in the inventor's father, with a rare display of excitement. "It will be considerably more than that. It's the biggest thing since the electric dynamo! It puts airplanes in the junk heap! It means a new era in power generation. Why, we'll never have to worry about power! It will make interplanetary travel not only possible, but commercially economical."

Arcot junior grinned broadly. "Dad seems to think the machine has possibilities! Seriously, I believe it will antiquate all types of airplanes, prop or jet. It's a direct utilization of the energy that the sun is kindly supplying. For a good many years now men have been trying to find out how to control the energy of atoms for air travel, or to release the energy of the constitution of matter.

"But why do it at all? The sun is doing it already, and on a scale so gargantuan that we could never hope nor desire to approach it. Three million tons of matter go into that colossal furnace every second of time, and out of that comes two and a half decillion ergs of energy. With a total of two and a half million billion billion billions of ergs to draw on, man will have nothing to worry about for a good many years to come! That represents a flood of power vaster than man could comprehend. Why try to release any more energy? We have more than we can use; we may as well tap that vast ocean of power.

"There is one thing that prevents us getting it out, the law of probability. That's why Dad mentioned loaded dice, for dice, as you know, are the classical example of probability when they aren't loaded. Once they are loaded, the law still holds, but the conditions are now so changed that it will make the problem quite different."

Arcot paused, frowning, then resumed half apologetically, "Excuse the lecture--but I don't know how else to get the thought across. You are familiar with the conditions in a liter of helium gas in a container--a tremendous number of molecules, each dashing along at several miles a second, and an equal number dashing in the opposite direction at an equal speed. They are so thickly packed in there, that none of them can go very far before it runs into another molecule and bounces off in a new direction. How good is the chance that all the molecules should happen to move in the same direction at the same time? One of the old physicists of Einstein's time, a man named Eddington, expressed it very well:

'If an army of monkeys were playing on typewriters they
might write all the books in the British Museum. The
chance of their doing so is decidedly more favorable
than the chance that all the molecules in a liter of
gas should move in the same direction at the same
time.'

The very improbability of this chance is the thing that is making our problem appear impossible.

"But similarly it would be improbable--impossible according to the law of chance--to throw a string of aces indefinitely. It is impossible--unless some other force influences the happening. If the dice have bits of iridium stuck under the six spots, they will throw aces. Chance makes it impossible to have all the molecules of gas move in the same direction at the same time--unless we stack the chances. If we can find some way to influence them, they may do so.

"What would happen to a metal bar if all the molecules in it decided to move in the same direction at the same time? Their heat motion is normally carrying them about at a rate of several miles a second, and if now we have them all go in one way, the entire bar must move in that direction, and it will start off at a velocity as great as the velocity of the individual molecules. But now, if we attach the bar to a heavy car, it will try to start off, but will be forced to drag the car with it, and so will not be able to have its molecules moving at the same rate. They will be slowed down in starting the mass of the car. But slowly moving molecules have a definite physical significance. Molecules move because of temperature, and lack of motion means lack of heat. These molecules that have been slowed down are then cold; they will absorb heat from the air about them, and since the molecule of hydrogen gas at room temperature is moving at about seven miles a second, when the molecules of the confined gas in our car, or the molecules of the metal bar are slowed down to but a few hundred miles an hour, their temperature drops to some hundreds of degrees below zero, and they absorb energy very rapidly, for the greater the difference in temperature, the greater the rate of heat absorption.

"I believe we will be able to accelerate the car rapidly to a speed of several miles a second at very high altitudes, and as we will be able to use a perfectly enclosed streamlined car, we should get tremendous speeds. We'll need no wings, of course, for with a small unit pointed vertically, we'll be able to support the car in the air. It will make possible a machine that will be able to fly in reverse and so come to a quick stop. It will steer us or it will supply us with electrical power, for we merely have to put a series of small metal bars about the circumference of the generator, and get a tremendously powerful engine.

"For our present need, it means a tremendously powerful engine--and one that we can make invisible.

"I believe you can guess the source of that breeze we had there? It would make a wonderful air-conditioning unit."

"Dick Arcot," began Morey, his voice tight with suppressed excitement, "I would like to be able to use this invention. I know enough of the economics of the thing, if not its science, to know that the apparatus before us is absolutely invaluable. I couldn't afford to buy the rights on it, but I want to use it if you'll let me. It means a new era in transcontinental air travel!"

He turned sharply to Fuller. "Fuller, I want you to help Arcot with the ship to chase the Pirate. You'll get the contract to design the new airliners. Hang the cost. It'll run into billions--but there will be no more fuel bills, no oil bills, and the cost of operation will be negligible. Nothing but the Arcot short wave tubes to buy--and each one good for twenty-five thousand hours service!"

"You'll get the rights on this if you want them, of course," said Arcot quietly. "You're maintaining these laboratories for me, and your son helped me work it out. But if Fuller can move over here tomorrow, it will help things a lot. Also I'd like to have some of your best mechanics to make the necessary machines, and to start the power units."

"It's done," Morey snapped.

III

Early the next morning Fuller moved his equipment over to the laboratory and set up his table for work. There Arcot and Morey joined him, and the designing of the new machine was started.

"First, let's get some idea of the most advisable shape," Fuller began methodically. "We'll want it streamlined, of course; roughly speaking, a cylinder modified to fit the special uses to which it will be put. But you probably have a general plan in mind, Arcot. Suppose you sketch it for us."

The big physicist frowned thoughtfully. "Well, we don't know much about this yet, so we'll have to work it out. You'll have plenty of fun figuring out strains in this machine, so let's be safe and use a factor of safety of five. Let's see what we'll need.

"In the first place, our machine must be proof against the Pirate's gas, for we won't be riding a beam with instruments to guide us safely, if we pass out. I've thought that over, and I think that the best system is just what we used in the sample bottles--a vacuum. His gas is stopped by nothing, so to speak, but there is no substance that will stop it! It will no doubt penetrate the outer shell, but on reaching the vacuum, it will tend to stay there, between the inner and outer walls. Here it will collect, since it will be fighting air pressure in going either in or out. The pressure inside will force it back, and the pressure outside will force it in. If we did not pump it out, it would soon build up pressure enough to penetrate the interior wall. Now, since the stuff can leak through any material, what kind of a pump shall we use? It won't be pushed by a piston, for it will leak through either the cylinder walls or the piston. A centrifugal pump would be equally ineffective. A mercury vapor pump will take it out, of course, and keep a high vacuum, but we'd never make any progress.

"Our new machine gives us the answer. With it we can just have a number of openings in the wall of the outer shell, and set in them one of these molecular motion directors, and direct the molecules into the outside air. They can't come in through it, and they will go out!"

"But," Morey objected, "the vacuum that keeps out the gas will also keep out heat, as well! Since our generator is to run on heat energy, it will be rather chilly inside if we don't remedy that. Of course, our power units could be placed outside, where the blast of air will warm them, but we really won't have a very good streamline effect if we hang a big electric generator outside."

"I've thought of that too," Arcot answered. "The solution is obvious--if we can't bring the generator to the air, we must bring the air to it." He began sketching rapidly on the pad before him, "We'll have all the power equipment in this room here in the back, and the control room up in front, here. The relays for controlling will be back here, so we can control electrically the operation of the power equipment from our warm, gas-tight room. If it gets too warm in there, we can cool it by using a little of the heat to help accelerate the ship. If it is too cold, we can turn on an electric heater run by the generator. The air for the generator can come in through a small sort of scoop on top, and leave through a small opening in the rear. The vacuum at the tail will assure us a very rapid circulation, even if the centrifugal pump action of the enclosed generator isn't enough."

His thoughts began moving more rapidly than his words. "We'll want the generator greatly over power to run tests over a greater range. Won't need more than one hundred kilowatts altogether, but should install about a thousand--A.C., of course. Batteries in the keel for starting the generator.... Self-supporting when it's rolling....

"But let's set down some actual figures on this."

For the rest of the day the three men were working on the general plan of the new ship, calculating the strengths needed, supplementing mathematics with actual experiments with the machines on hand. The calculating machines were busy continuously, for there were few rules that experience could give them. They were developing something entirely new, and though they were a designing staff of three of the foremost mathematicians in the world, it was a problem that tested their ingenuity to the utmost.

By the evening of the first day, however, they had been able to give the finished designs for the power units to the mechanics who were to make them. The order for the storage battery and the standard electrical equipment had been placed at once. By the time they had completed the drawings for the mail casting, the materials were already being assembled in a little private camp that Morey owned, up in the hills of Vermont. The giant freight helicopters could land readily in the wide field that had been cleared on the small plateau, in the center of which nestled a little blue lake and a winding trout brook.

The mechanics and electrical engineers had been sent up there already--officially on vacation. The entire program could be carried out without attracting the least attention, for such orders from the great Transcontinental lines were so frequent that no importance was attached to them.

Four days after the final plans had been completed the last of the supplies were being assembled in the portable metal shed that was to house the completed machine. The shining tungsto-steel alloy frame members were rapidly being welded in place by cathode ray welding torches in the hands of skilled artisans.

Already at the other end of the shop the generator had been arranged for use with the molecular motion power units. The many power units to drive and support the ship were finished and awaiting installation as the crew quit work on the fourth evening. They would be installed on the frame in the morning, and the generator would be hoisted into place with the small portable crane. The storage batteries were connected, and in place in the hull. The great fused quartz windows rested in their cases along one wall, awaiting the complete application of the steel alloy plates. They were to be over an inch thick, an unnecessary thickness, perhaps, but they had no need to economize weight, as witnessed by their choice of steel instead of light metal alloys throughout the construction.

The three men had arrived late that afternoon in a small helicopter, and had gone directly to the shops to see what progress had been made. They had been forced to remain in New York to superintend the shipment of the necessary supplies to the camp site, and since no trouble was anticipated in the making of the steel framework, they had not felt it necessary to come. But now they would be needed to superintend the more delicate work.

"She's shaping up nicely, isn't she?" Arcot gazed at the rapidly rounding frame with a critical eye. Unhindered as they were by the traditional shapes, by wings or other protuberances, they had been able to design a machine of striking beauty. The ship was to retain its natural metallic sheen, the only protection being a coat of "passivity paint"--a liquid chemical that could be brushed or sprayed on iron, chromium, nickel or cobalt alloys, rendering them passive to practically all chemical agents. The new "paint" left the iron or steel as brilliantly glossy as ever, but overcast with a beautiful iridescence, and immune to the most powerful reagents.

The three men walked around the rapidly growing hull, and looked with excited interest at the heavy welded joints and the great beams. The ship seemed capable of withstanding a fall of several hundred feet with little damage. The location of the power units was plainly visible and easily recognized, for at each point there came together four or five great beams, welded into one great mass of tough metal, and in it there were set heavy tungsten bolts that would hold the units in place.

They inspected each joint minutely for signs of flaws, using a small portable X-ray fluoroscope to see the interior of the metal. Each joint seemed perfect. They retired, satisfied that everything was ready for the work of the next day.

The morning began early with a long swim in the lake, and a hearty breakfast of country cured ham and eggs. Then the work on the great framework was continued, and that day saw the power units bolted in place, removable if change was thought advisable. Each power unit was equipped with long streamlined copper fins lying close to the rounded hull, that they might absorb heat more rapidly.

Day by day the structure drew nearer completion, and, with the large crew of highly skilled workers, the craft was practically complete within a week. Only the instruments remained to be installed. Then at last even these had been put in place, and with the aid of Fuller, Morey junior, and his own father, Arcot had connected their many complicated circuits.

"Son," remarked Arcot senior, looking critically at the great switchboard, with its maze of connections, its many rheostats and controls, and its heavy bus bar connectors behind it, "no one man can keep an eye on all those instruments. I certainly hope you have a good-sized crew to operate your controls! We've spent two days getting all those circuits together, and I'll admit that some of them still have me beat. I don't see how you intend to watch all those instruments, and at the same time have any idea what's going on outside."

"Oh," laughed Arcot junior, "these aren't intended for constant watching. They're merely helps in a lot of tests I want to make. I want to use this as a flying laboratory so I can determine the necessary powers and the lowest factor of safety to use in building other machines. The machine is very nearly completed now. All we need is the seats--they are to be special air-inflated gyroscopically controlled seats, to make it impossible for a sudden twist of the ship to put the strain in the wrong direction. Of course the main gyroscopes will balance the ship laterally, horizontally, and vertically, but each chair will have a separate gyroscopic mounting for safety."

"When do you expect to start after the Pirate?" Fuller asked.

"I plan to practice the manipulation of the machine for at least four days," Arcot replied, "before I try to chase the Pirate. I'd ordinarily recommend the greatest haste, but the man has stolen close to ten million already, and he's still at it. That would not be done by anyone in his right mind. I suppose you've heard, the War Department considers his new gas so important that they've obtained a pardon for him on condition they be permitted to have the secret of it. They demand the return of the money, and I have no doubt he has it. I am firmly convinced that he is a kleptomaniac. I doubt greatly if he will stop taking money before he is caught. Therefore it will be safe to wait until we can be sure of our ability to operate the machine smoothly. Any other course would be suicidal. Also, I am having some of those tool-makers make up a special type of molecular motion machine for use as a machine gun. The bullets are steel, about three inches long, and as thick as my thumb. They will be perfectly streamlined, except for a little stabilizer at the tail, to guide 'em. They won't spin as a rifle bullet does, and so there will be no gyroscopic effect to hold them nose on, but the streamlining and the stabilizer will keep them on their course. I expect them to be able to zip right through many inches of armour plate, since they will have a velocity of over four miles a second.

"They'll be fed in at the rate of about two hundred a minute--faster if I wish, and started by a small spring. They will instantly come into the field of a powerful molecular motion director, and will be shot out with terrific speed. It will be the first rifle ever made that could shoot bullets absolutely parallel to the ground.

"But that is all we can do today. The guns will be mounted outside, and controlled electrically, and the charts will be installed tomorrow. By the day after tomorrow at eight A.M. I plan to take off!"

The work the next day was rushed to completion far earlier than Arcot had dared to hope. All the men had been kept isolated at the farm, lest they accidentally spread the news of the new machine. It was with excited interest that they helped the machine to completion. The guns had not been mounted as yet, but that could wait. Mid-afternoon found the machine resting in the great construction shed, completely equipped and ready to fly!

"Dick," said Morey as he strode up to him after testing the last of the gyroscopic seats, "she's ready! I certainly want to get her going--it's only three-thirty, and we can go around to the sunlight part of the world when it gets dark at the speeds we can travel. Let's test her now!"

"I'm just as anxious to start as you are, Bob. I've sent for a U.S. Air Inspector. As soon as he comes we can start. I'll have to put an 'X' license indication on her now. He'll go with us to test it--I hope. There will be room for three other people aboard, and I think you and Dad and I will be the logical passengers."

He pointed excitedly. "Look, there's a government helicopter coming. Tell the men to get the blocks from under her and tow her out. Two power trucks should do it. Get her at least ten feet beyond the end of the hangar. We'll start straight up, and climb to at least a five mile height, where we can make mistakes safely. While you're tending to that, I'll see if I can induce the Air Inspector to take a trip with us."

Half an hour later the machine had been rolled entirely out of the shed, on the new concrete runway.

The great craft was a thing of beauty shimmering in the bright sunlight The four men who were to ride in it on its maiden voyage stood off to one side gazing at the great gleaming metal hull. The long sweeping lines of the sides told a story of perfect streamlining, and implied high speed, even at rest. The bright, slightly iridescent steel hull shone in silvery contrast to the gleaming copper of the power units' heat-absorption fins. The great clear windows in the nose and the low, streamlined air intake for the generator seemed only to accentuate the graceful lines of the machine.

"Lord, she's a beauty, isn't she, Dick!" exclaimed Morey, a broad smile of pleasure on his face.

"Well, she did shape up nicely on paper, too, didn't she. Oh, Fuller, congratulations on your masterpiece. It's even better looking than we thought, now the copper has added color to it. Doesn't she look fast? I wish we didn't need physicists so badly on this trip, so you could go on the first ride with us."

"Oh, that's all right, Dick, I know the number of instruments in there, and I realize they will mean a lot of work this trip. I wish you all luck. The honor of having designed the first ship like that, the first heavier-than-air ship that ever flew without wings, jets, or props--that is something to remember. And I think it's one of the most beautiful that ever flew, too."

"Well, Dick," said his father quietly, "let's get under way. It should fly--but we don't really know that it will!"

The four men entered the ship and strapped themselves in the gyroscopic seats. One by one they reported ready.

"Captain Mason," Arcot explained to the Air Inspector, "these seats may seem to be a bit more active than one generally expects a seat to be, but in this experimental machine, I have provided all the safety devices I could think of. The ship itself won't fall, of that I am sure, but the power is so great it might well prove fatal to us if we are not in a position to resist the forces. You know all too well the effect of sharp turns at high speed and the results of the centrifugal force. This machine can develop such tremendous power that I have to make provision for it.

"You notice that my controls and the instruments are mounted on the arm of the chair really; that permits me to maintain complete control of the ship at all times, and still permits my chair to remain perpendicular to the forces. The gyroscopes in the base here cause the entire chair to remain stable if the ship rolls, but the chair can continue to revolve about this bearing here so that we will not be forced out of our seats. I'm confident that you'll find the machine safe enough for a license. Shall we start?"

"All right, Dr. Arcot," replied the Air Inspector. "If you and your father are willing to try it, I am."

"Ready, Engineer?" asked Arcot.

"Ready, Pilot!" replied Morey.

"All right--just keep your eye on the meters, Dad, as I turn on the system. If the instruments back there don't take care of everything, and you see one flash over the red mark--yank open the main circuit. I'll call out what to watch as I turn them on."

"Ready son."

"Main gyroscopes!" There was a low snap, a clicking of relays in the rear compartment, and then a low hum that quickly ran up the scale. "Main generators!" Again the clicking switch, and the relays thudding into action, again the rising hum. "Seat-gyroscopes." The low click was succeeded by a quick shrilling sound that rose in moments above the range of hearing as the separate seat-gyroscopes took up their work. "Main power tube bank!" The low hum of the generator changed to a momentary roar as the relays threw on full load. In a moment the automatic controls had brought it up to speed.

"Everything is working perfectly so far. Are we ready to start now, son?"

"Main vertical power units!" The great ship trembled throughout its length as the lift of the power units started. A special instrument had been set up on the floor beside Arcot, that he might be able to judge the lift of his power units; it registered the apparent weight of the ship. It had read two hundred tons. Now all eyes were fixed on it, as the pointer dropped quickly to 150-100-75-50-40-20-10--there was a click and the instrument flopped back to 300--it was registering in pounds now! Then the needle moved to zero, and the mighty structure floated into the air, slowly moving down the field as a breeze carried it along the ground.

The men outside saw it rise swiftly into the sky, straight toward the blue vault of heaven. In two or three minutes it was disappearing. The glistening ship shrank to a tiny point of light; then it was gone! It must have been rising at fully three hundred miles an hour!

To the men in the car there had been a tremendous increase in weight that had forced them into the air cushions like leaden masses. Then the ground fell away with a speed that made them look in amazement. The house, the construction shed, the lake, all seemed contracting beneath them. So quickly were they rising that they had not time to adjust their mental attitude. To them all the world seemed shrinking about them.

Now they were at a tremendous height; over twenty miles they had risen into the atmosphere; the air about them was so thin that the sky seemed black, the stars blazed out in cold, unwinking glory, while the great fires of the sun seemed reaching out into space like mighty arms seeking to draw back to the parent body the masses of the wheeling planets. About it, in far flung streamers of cold fire shone the mighty zodiacal light, an Aurora on a titanic scale. For a moment they hung there, while they made readings of the meters.

Arcot was the first to speak and there was awe in his voice. "I never began to let out the power of this thing! What a ship! When these are made commercially, we'll have to use about one horsepower generators in them, or people will kill themselves trying to see how fast they can go."

Methodically the machine was tried out at this height, testing various settings of the instruments. It was definitely proven that the values that Arcot and Morey had assigned from purely theoretical calculations were correct to within one-tenth of one percent. The power absorbed by the machine they knew and had calculated, but the terrific power of the driving units was far beyond their expectations.

"Well, now we're off for some horizontal maneuvers," Arcot announced. "I'm sure we agree the machine can climb and can hold itself in the air. The air pressure controls seem to be working perfectly. Now we'll test her speed."

Suddenly the seats swung beneath them; then as the ship shot forward with ever greater speed, ever greater acceleration, it seemed that it turned and headed upward, although they knew that the main stabilizing gyroscopes were holding it level. In a moment the ship was headed out over the Atlantic at a speed no rifle bullet had ever known. The radio speedometer needle pushed farther and farther over as the speed increased to unheard of values. Before they left the North American shoreline they were traveling faster than a mile a second. They were in the middle of the Atlantic before Arcot gradually shut off the acceleration, letting the seats drop back into position.

A hubbub of excited comments rose from the four men. Momentarily, with the full realization of the historical importance of this flight, no one paid any attention to anyone else. Finally a question of the Air Inspector reached Arcot's ears.

"What speed did we attain, Dr. Arcot? Look--there's the coast of Europe! How fast are we going now?"

"We were traveling at the rate of three miles a second at the peak." Arcot answered. "Now it has fallen to two and a half."

Again Arcot turned his attention to his controls. "I'm going to try to see what the ultimate ceiling of this machine is. It must have a ceiling, since it depends on the operation of the generator to operate the power-units. This, in turn, depends on the heat of the air, helped somewhat by the sun's rays. Up we go!"

The ship was put into a vertical climb, and steadily the great machine rose. Soon, however, the generator began to slow down. The readings of the instruments were dropping rapidly. The temperature of the exceedingly tenuous air outside was so close to absolute zero that it provided very little energy.

"Get up some forward speed," Morey suggested, "so that you'll have the aid of the air scoop to force the air in faster."

"Right, Morey." Arcot slowly applied the power to the forward propulsion units. As they took hold, the ship began to move forward. The increase in power was apparent at once. The machine started rising again. But at last, at a height of fifty-one miles, her ceiling had been reached.

The cold of the cabin became unbearable, for every kilowatt of power that the generator could get from the air outside was needed to run the power units. The air, too, became foul and heavy, for the pumps could not replace it with a fresh supply from the near-vacuum outside. Oxygen tanks had not been carried on this trip. As the power of the generator was being used to warm the cabin once more, they began to fall. Though the machine was held stable by the gyroscopes, she was dropping freely; but they had fifty miles to fall, and as the resistance of the denser air mounted, they could begin to feel the sense of weight return.

"You've passed, but for the maneuvers, Dr. Arcot!" The Air Inspector was decidedly impressed. "The required altitude was passed so long ago--why we are still some miles above it, I guess! How fast are we falling?"

"I can't tell unless I point the nose of the ship down, for the apparatus works only in the direction in which the ship is pointed. Hold on, everyone, I am going to start using some power to stop us."

It was night when they returned to the little field in Vermont. They had established a new record in every form of aeronautical achievement except endurance! The altitude record, the speed record, the speed of climb, the acceleration record--all that Arcot could think of had been passed. Now the ship was coming to dock for the night. In the morning it would be out again. But now Arcot was sufficiently expert with the controls to maneuver the ship safely on the ground. They finally solved the wind difficulty by decreasing the weight of the ship to about fifty pounds, thus enabling the three men to carry it into the hanger!

* * * * *

The next two days were devoted to careful tests of the power factors of the machine, the best operating frequency, the most efficient altitude of operation, and as many other tests as they had time for. Each of the three younger men took turns operating, but so great were the strains of the sudden acceleration, that Arcot senior decided it would be wisest for him to stay on the ground and watch.

In the meantime reports of the Pirate became fewer and fewer as less and less money was shipped by air.

Arcot spent four days practicing the manipulation of the machine, for though it handled far more readily than any other craft he had ever controlled, there was always the danger of turning on too much power under the stress of sudden excitement.

The night before, Arcot had sailed the ship down and alighted on the roof of Morey senior's apartment, leaving enough power on to reduce the weight to but ten tons, lest it fall through the roof, while he went down to see the President of the Lines about some "bait" for the Pirate.

"Send some cash along," said Arcot, when he saw Morey senior, "say a quarter of a million. Make it more or less public knowledge, and talk it up so that the Pirate may think there's a real haul on board. I am going to accompany the plane at a height of about a quarter of a mile above. I will try to locate him from there by means of radar, and if I have my apparatus on, I naturally can't locate him. I hope he won't be scared away--but I rather believe he won't. At any rate, you won't lose on the try!"

IV

Again Morey and Arcot were looking at the great Jersey aerodrome, out on the fields that had been broad marshes centuries before. Now they had been filled in, and stretched for miles, a great landing field, close to the great city across the river.

The men in the car above were watching the field, hanging inert, a point of glistening metal, high in the deep velvet of the purple sky, for fifteen miles of air separated them from the Transcontinental machine below. Now they saw through their field glasses that the great plane was lumbering slowly across the field, gaining momentum as it headed westward into the breeze. Then it seemed to be barely clearing the great skyscrapers that towered twenty-four hundred feet into the air, arching over four or five city blocks. From this height they were toys made of colored paper, soft colors glistening in the hot noon sunlight, and around and about them wove lines of flashing, moving helicopters, the individual lost in the mass of the million or so swiftly moving machines. Only the higher, steadily moving levels of traffic were visible to them.

"Just look at that traffic! Thousands and thousands coming back into the city after going home to lunch--and every day the number of helicopters is increasing! If it hadn't been for your invention of this machine, conditions would soon be impossible. The airblast in the cities is unbearable now, and getting worse all the time. Many machines can't get enough power to hold themselves up at the middle levels; there is a down current over one hundred miles an hour at the 400-foot level in downtown New York. It takes a racer to climb fast there!

"If it were not for gyroscopic stabilizers, they could never live in that huge airpocket. I have to drive in through there. I'm always afraid that somebody with an old worn-out bus will have stabilizer failure and will really smash things." Morey was a skillful pilot, and realized, as few others did, the dangers of that downward airblast that the countless whirring blades maintained in a constant roar of air. The office buildings now had double walls, with thick layers of sound absorbing materials, to stop the roar of the cyclonic blast that continued almost unabated twelve hours a day.

"Oh, I don't know about that, Morey," replied Arcot. "This thing has some drawbacks. Remember that if we had about ten million of these machines hung in the air of New York City, there would be a noticeable drop in the temperature. We'd probably have an Arctic climate year in and year out. You know, though, how unbearably hot it gets in the city by noon, even on the coldest winter days, due to the heating effect of the air friction of all those thousands of blades. I have known the temperature of the air to go up fifty degrees. There probably will have to be a sort of balance between the two types of machines. It will be a terrific economic problem, but at the same time it will solve the difficulties of the great companies who have been fermenting grain residues for alcohol. The castor bean growers are also going to bring down their prices a lot when this machine kills the market. They will also be more anxious to extract the carbon from the cornstalks for reducing ores of iron and of other metals."

As the ship flew high above the Transcontinental plane, the men discussed the economic values of the different applications of Arcot's discoveries from the huge power stations they could make, to the cooling and ventilating of houses.

"Dick, you mentioned the cooling effect on New York City; with the millions on millions of these machines that there will be, with huge power plants, with a thousand other different applications in use, won't the terrific drain of energy from the air cause the whole world to become a little cooler?" asked Fuller.

"I doubt it, Bob," said Arcot slowly. "I've thought of that myself. Remember that most of the energy we use eventually ends up as heat anyway. And just remember the decillions of ergs of energy that the sun is giving off! True, we only get an infinitesimal portion of that energy--but what we do get is more than enough for us. Power houses can be established very conveniently in the tropics, where they will cool the air, and the energy can be used to refine metals. That means that the surplus heat of the tropics will find a use. Weather control will also be possible by the direction-control of great winds. We could set huge director tubes on the tops of mountains, and blow the winds in whatever direction best suited us. Not the blown wind itself, but the vast volume of air it carried with it, would be able to cool the temperate zones in the summer from the cold of the poles, and warm it in winter with the heat of the tropics."

After a thoughtful silence, Arcot continued, "And there is another thing it may make possible in the future--a thing that may be hard to accept as a commercial proposition. We have a practically inexhaustible source of energy now, but we have no sources of minerals that will last indefinitely. Copper is becoming more and more rare. Had it not been for the discoveries of the great copper fields of the Sahara and in Alaska, we wouldn't have any now. Platinum is exhausted, and even iron is becoming more and more valuable. We are facing a shortage of metals. Do you realize that within the next two centuries we will be unable to maintain this civilization unless we get new sources of certain basic raw materials?

"But we have one other chance now. The solution is--there are nine planets in this solar system! Neptune and Uranus are each far vaster than Earth; they are utterly impossible for life as we know it, but a small colony might be established there to refine metals for the distant Earth. We might be able to build domed and sealed cities. But first we could try the nearer planets--Mars, Venus, or some satellites such as our Moon. I certainly hope that this machine will make it possible."

For some time they sat in silence as they sped along, high above the green plains of Indiana. Chicago lay like some tremendous jewel far off on the horizon to the right and ahead. Five miles below them the huge bulk of the Transcontinental plane seemed a toy as it swung slowly across the fields--actually traveling over six hundred miles an hour. At last Morey spoke.

"You're right, Arcot. We'll have to think of the interplanetary aspects of this some day. Oh, there's Chicago! We'd better start the vacuum gas protector. And the radar. We may soon see some action."

The three men immediately forgot the somewhat distant danger of the metal shortage. There were a number of adjustments to be made, and these were quickly completed, while the machine forged evenly, steadily ahead. The generator was adjusted to maximum efficiency, and the various tubes were tested separately, for though they were all new, and each good for twenty-five thousand hours, it would be inconvenient, to say the least, if one failed while they were in action. Each tested perfect; and they knew from the smooth functioning of the various relays that governed the generator, as the loads on it varied, that it must be working perfectly, at something less than one-half maximum rating.

Steadily they flew on, waiting tensely for the first sign of a glow from the tiny neon tube indicator on the panel before Morey.

"This looks familiar, Dick," said Morey, looking about at the fields and the low line of the blue mountains far off on the western horizon. "I think it was about here that we took our little nap in the 'Flying Wheel chair', as the papers called it. It would be about here th-- LOOK! It is about here! Get ready for action, Fuller. You're taking the machine gun, I'll work the invisibility disrupter, and Arcot will run the ship. Let's go!"

On the board before him the tiny neon tube flickered dully, glowed briefly like a piece of red-hot iron, then went out. In a moment it was glowing again, and then quickly its brilliance mounted till it was a line of crimson. Morey snapped the switch from the general radar to the beam receiver, that he might locate the machine exactly. It was fully a minute before the neon tube flashed into life once more. The pirate was flying just ahead of the big plane, very likely gassing them. All around him were the Air Guardsmen, unaware that the enemy was so near. As the disrupter beam could be projected only about a mile, they would have to dive down on the enemy at once; an instant later the great plane beneath them seemed to be rushing upward at a terrific speed.

The two radar beams were kept focused constantly on the Pirate's craft. When they were about two miles from the two planes, the neon tube blazed brilliantly with a clash of opposing energy. The Pirate was trying to maintain his invisibility, while the rapidly growing strength of the machine above strove to batter it down. In moments the ammeter connected with the disrupter beam began to rise so rapidly that Morey watched it with some concern. Despite the ten-kilowatt set being used to project the beam, the resistance of the apparatus on board the pirate ship was amazing.

Abruptly the three became aware of a rapidly solidifying cloud before them. The interference of the beam Morey was sending had begun breaking down the molecular oscillation that permitted the light to pass freely through the pirate's craft. Suddenly there was a circle of blue light about the shadow form, and a moment later the ionized air relapsed into normal condition as the pirate's apparatus broke down under the strain. At once Morey shut off his apparatus, convinced by the sudden change that the pirate's apparatus had blown out. He glanced up quickly as Arcot called to him, "Morey--look at him go!"

Too late. Already the plane had shot off with terrific speed. It had flashed up and to their left, at a rate of climb that seemed unbelievable--except that the long trail of flaming gas told the story! The plane was propelled by rockets! The terrific acceleration carried it out of their range of vision in an instant, and as Arcot swung the ship to bring him again within sight of the windows, they gasped, for already he was many miles away.

There was a terrific wrench as Arcot threw on all the power he dared, then quickly leveled the machine, following the pirate at lightning speed. He increased the acceleration further as the men grew accustomed to the force that weighed them down. Ahead of them the pirate was racing along, but quickly now they were overhauling him, for his machine had wings of a sort! They produced a tremendous amount of head resistance at their present velocity, for already the needle of the radio speedometer had moved over to one mile a second. They were following the fleet plane ahead at the rate of 3600 miles an hour. The roar of the air outside was a tremendous wave of sound, yet to them, protected by the vacuum of the double walls, it was detectable only by the vibration of the car.

Rapidly the pirate's lead was cut down. It seemed but a moment before he would be within range of their machine gun. Suddenly he nosed down and shot for the ground, ten miles below, in a power dive. Instantly Arcot swung his machine in a loop that held him close to the tail of the pirate. The swift maneuvers at this speed were a terrific strain on both men and machines--the acceleration seemed crushing them with the weight of four men, as Arcot followed the pirate in a wide loop to the right that ended in a straight climb, the rocket ship standing on its tail, the rocket blast roaring out behind a stream of fire a half mile long.

The pirate was climbing at a speed that would have distanced any other machine the world had ever seen, but the tenacious opponent behind him clung ever tighter to the tiny darting thing. He had released great clouds of his animation suspending gas. To his utter surprise, the ship behind him had driven right through it, entirely unaffected! He, who knew most about the gas, had been unable to devise a material to stop it, a mask or a tank to store it, yet in some way these men had succeeded! And that hurtling, bullet-shaped machine behind! Like some miniature airship it was, but with a speed and an acceleration that put even his ship to shame! It could twist, turn, dive, rise and shoot off on the straight-away with more flashing speed than anything aloft. Time and again he tried complicated maneuvers that strained him to the utmost, yet that machine always followed after him!

There was one more thing to do. In outer space his rockets would support him. In a straight climb he shot up to the blazing sun above, out into space, while the sky around him grew black, and the stars shone in solemn splendor around him. But he had eyes for only one thing, the shining car that was rising with more than equal speed behind him. He knew he must be climbing over two thousand miles an hour, yet the tracker came ever closer. Just out of sighting range for the machine gun now ... in a moment ... but, she was faltering!

The men in the machine behind sat white-lipped, tense, as the whirling shocks of sudden turns at terrific speed twisted the gyroscopic seats around like peas in a rolling ball. Up, down, left, right, the darting machine ahead was twisting with unbelievable speed. Then suddenly the nose was pointed for the zenith again, and with a great column of flame shooting out behind him, he was heading straight toward space!

"If he gets there, I lose him, Morey!" said Arcot. The terrific acceleration of the climb seemed to press them to their seats with a deadly weight. It was labor to talk--but still the car ahead shot on--slowly they seemed to be overhauling him. Now that the velocities were perforce lowered by the effects of gravity, and the air resistance of the atmosphere was well nigh gone, only the acceleration that the human body could stand was considered. The man ahead was pushing his plane ahead with an acceleration that would have killed many men!

Slowly the acceleration of the machine was falling. Arcot pushed the control over to the last ampere, and felt the slight surge, as greater power rushed through the coils momentarily. Soon this was gone too, as the generator behind faltered. The driving power of the atmospheric heat was gone. More than sixty miles below them they could see the Earth as a greenish brown surface, slightly convex, and far to the east they could distinguish a silvery line of water! But they had no eyes but for the column of shooting flame that represented the fleeing raider! Out in airless space now, he was safe from them. They could not follow. Arcot turned the plane once more, parallel to the Earth, watching the plane above through the roof window. Slowly the machine sank to the fifty-mile level, where there was just sufficient air to maintain it in efficient operation.

"Well, he beat us! But there is only one thing for us to do. He must hang there on his rockets till we leave, and we can hang here indefinitely, if we can only keep this cabin decently warm. He has no air to cool him, and he has the sun to warm him. The only thing that is worrying him right now is the heat of his rockets. But he can throw most of that out with the gases. Lord, that's some machine! But eventually his rockets will give out, and down he will come, so we'll just hang here beneath him and--whoa--not so fast--he isn't going to stay there, it seems; he is angling his ship off a bit, and shooting along, so that, besides, holding himself up, he is making a little forward progress. We'll have to follow! He's going to do some speeding, it seems! Well, we can keep up with him, at our level."

"Dick, no plane ever made before would have stood the terrific pulls and yanks that his plane got. He was steering and twisting on the standard type air rudders, and what strains he had! The unique type of plane must be extremely strong. I never saw one shaped like his before, though--it is the obvious shape at that! It was just a huge triangular arrowhead! Did you ever see one like it?"

"Something like it, yes, and so have you. Don't you recognize that as the development of the old paper gliders you used to throw around as a kid? It has the same shape, the triangular wings with the point in the lead, except that he undoubtedly had a slight curve to the wings to increase the efficiency. Something like the flying wings of fifty years ago. I hope that man is only a kleptomaniac, because he can be cured of that, and I may then have a new laboratory partner. He has some exceedingly intelligent ideas!

"He's an ingenious man, but I wish he didn't store quite so much fuel in his rocket tubes! It's unbearably cold in here, and I can't sacrifice any power just for comfort. The rocket ship up there seems to be getting more and more acceleration in the level. He has me dropping steadily to get air to run the generator. He is going fast enough!"

They followed beneath the pirate, faster and faster as the rockets of the ship began to push it forward more and more.

"Dick, why is it he didn't use all his rockets at first instead of gradually increasing the power this way?"