II

Five men were seated about the Morey library, discussing the results of

the last raid, in particular as related to Arcot and Morey. Fuller, and

President Morey, as well as Dr. Arcot, senior, and the two young men

themselves, were there. They had consistently refused to tell what their

trip had revealed, saying that pictures would speak for them. Now they

turned their attention to a motion picture projector and screen that

Arcot junior had just set up. At his direction the room was darkened;

and he started the projector. At once they were looking at the three

dimensional image of the mail-room aboard the air liner.

Arcot commented: "I have cut out a lot of useless film, and confined the

picture to essentials. We will now watch the pirate at work."

Even as he spoke they saw the door of the mail-room open a bit, and

then, to their intense surprise, it remained open for a few seconds,

then closed. It went through all the motions of opening to admit

someone, yet no one entered!

"Your demonstration doesn't seem to show much yet, son. In fact, it

shows much less than I had expected," said the senior Arcot. "But that

door seemed to open easily. I thought they locked them!"

"They did, but the pirate just burned holes in them, so to save property

they leave 'em unlocked."

Now the scene seemed to swing a bit as the plane hit an unusually bad

air bump, and through the window they caught a glimpse of one of the

circling Air Guardsmen. Then suddenly there appeared in the air within

the room a point of flame. It hung in the air above the safe for an

instant, described a strangely complicated set of curves; then, as it

hung for an instant in mid-air, it became a great flare. In an instant

this condensed to a point of intensely brilliant crimson fire. This

described a complex series of curves and touched the top of the safe. In

an inconceivably short time, the eight-inch thickness of tungsto-iridium

alloy flared incandescently and began to flow sluggishly. A large circle

of the red flame sprang out to surround the point of brilliance, and

this blew the molten metal to one side, in a cascade of sparks.

In moments, the torch had cut a large disc of metal nearly free;

seemingly on the verge of dropping into the safe. Now the flame left the

safe, again retracting itself in that uncanny manner, no force seeming

either to supply it with fuel or to support it thus, though it burned

steadily, and worked rapidly and efficiently. Now, in mid-air, it hung

for a second.

"I'm going to work the projector for a few moments by hand so that you

may see this next bit of film." Arcot moved a small switch and the

machine blinked, giving a strange appearance to the seemingly solid

images that were thrown on the screen.

The pictures seemed to show the flame slowly descending till it again

touched the metal. The tungsto-iridium glowed briefly; then, as suddenly

as the extinguishing of a light, the safe was gone! It had disappeared

into thin air! Only the incandescence of the metal and the flame itself

were visible.

"It seems the pirate has solved the secret of invisibility. No wonder

the Air Guardsmen couldn't find him!" exclaimed Arcot, senior.

The projector had been stopped exactly on the first frame, showing the

invisibility of the safe. Then Arcot backed it up.

"True, Dad," he said, "but pay special attention to this next frame."

Again there appeared a picture of the room, the window beyond, the mail

clerk asleep at his desk, everything as before, except that where the

safe had been, _there was a shadowy, half visible safe_, the metal

glowing brightly. Beside it there was visible a shadowy man, holding

the safe with a shadowy bar of some sort. And through both of them the

frame of the window was perfectly visible, and, ironically, an Air

Guardsman plane.

"It seems that for an instant his invisibility failed here. Probably it

was the contact with the safe that caused it. What do you think, Dad?"

asked Arcot, junior.

"It does seem reasonable. I can't see off-hand how his invisibility is

even theoretically possible. Have you any ideas?"

"Well, Dad, I have, but I want to wait till tomorrow night to

demonstrate them. Let's adjourn this meeting, if you can all come

tomorrow."

* * * * *

The next evening, however, it seemed that it was Arcot himself who could

not be there. He asked Morey, junior, to tell them he would be there

later, when he had finished in the lab.

Dinner was over now, and the men were waiting rather impatiently for

Arcot to come. They heard some noise in the corridor, and looked up, but

no one entered.

"Morey," asked Fuller, "what did you learn about that gas the pirate was

using? I remember Arcot said he would have some samples to analyze."

"As to the gas, Dick found out but little more than we had already

known. It is a typical organic compound, one of the metal radical type,

and contains one atom of thorium. This is a bit radioactive, as you

know, and Dick thinks that this may account in part for its ability to

suspend animation. However, since it was impossible to determine the

molecular weight, he could not say what the gas was, save that the

empirical formula was C_{62}TH H_{39}O_{27}N_{5}. It broke down at a

temperature of only 89° centigrade. The gases left consisted largely of

methane, nitrogen, and methyl ether. Dick is still in the dark as to

what the gas is." He paused, then exclaimed: "Look over there!"

The men turned with one accord toward the opposite end of the room,

looked, and seeing nothing particularly unusual, glanced back rather

puzzled. What they then saw, or better, failed to see, puzzled them

still more. Morey had disappeared!

"Why--why where--ohhh! Quick work, Dick!" The senior Arcot began

laughing heartily, and as his astonished and curious companions looked

toward him, he stopped and called out, "Come on, Dick! We want to see

you now. And tell us how it's done! I rather think Mr. Morey here--I

mean the visible one--is still a bit puzzled."

There was a short laugh from the air--certainly there could be nothing

else there--then a low but distinct click, and both Morey and Arcot were

miraculously present, coming instantaneously from nowhere, if one's

senses could be relied on. On Arcot's back there was strapped a large

and rather hastily wired mechanism--one long wire extending from it out

into the laboratory. He was carrying a second piece of apparatus,

similarly wired. Morey was touching a short metal bar that Arcot held

extended in his hand, using a table knife as a connector, lest they get

radio frequency burns on making contact.

"I've been busy getting the last connection of this portable apparatus

rigged up. I have the thing in working order, as you see--or rather,

didn't see. This other outfit here is the thing that is more important

to us. It's a bit heavy, so if you'll clear a space, I'll set it down.

Look out for my power supply there--that wire is carrying a rather

dangerously high E.M.F. I had to connect with the lab power supply to do

this, and I had no time to rig up a little mechanism like the one the

pirate must have.

"I have duplicated his experiment. He has simply made use of a principle

known for some time, but as there was no need for it, it hasn't been

used. It was found back in the early days of radio, as early as the

first quarter of the twentieth century, that very short wavelengths

effected peculiar changes in metals. It was shown that the plates of

tubes working on very short waves became nearly transparent. The waves

were so short, however, that they were economically useless. They would

not travel in usable paths, so they were never developed. Furthermore,

existing apparatus could not be made to handle them. In the last war

they tried to apply the idea for making airplanes invisible, but they

could not get their tubes to handle the power needed, so they had to

drop it. However, with the tube I recently got out on the market, it is

possible to get down there. Our friend the pirate has developed this

thing to a point were he could use it. You can see that invisibility,

while interesting, and a good thing for a stage and television

entertainment, is not very much of a commercial need. No one wants to be

invisible in any honest occupation. Invisibility is a tremendous weapon

in war, so the pirate just started a little private war, the only way he

could make any money on his invention. His gas, too, made the thing

attractive. The two together made a perfect combination for criminal

operations.

"The whole thing looks to me to be the work of a slightly unbalanced

mind. He is not violently insane; probably just has this one particular

obsession. His scientific bump certainly shows no sign of weakness. He

might even be some new type of kleptomaniac. He steals things, and he

has already stolen far more than any man could ever have any need of,

and he leaves in its place a 'stock' certificate in his own company. He

is not violent, for hasn't he carefully warned the men not to use the

C-32L mask? You'll remember his careful instructions as to how to revive

the people!

"He has developed this machine for invisibility, and naturally he can

fly in and out of the air guard, without their knowing he's there,

provided their microphonic detectors don't locate him. I believe he uses

some form of glider. He can't use an internal combustion engine, for the

explosions in the cylinders would be as visible as though the cylinders

were made of clear quartz. He cannot have an electric motor, for the

storage cells would weigh too much. Furthermore, if he were using any

sort of prop, or a jet engine, the noise would give him away. If he used

a glider, the noise of the big plane so near would be more than enough

to kill the slight sounds. The glider could hang above the ship, then

dive down upon it as it passed beneath. He has a very simple system of

anchoring the thing, as I discovered to my sorrow. It's a powerful

electro-magnet which he turns on when he lands. The landing deck of the

big plane was right above our office aboard, and I found my watch was

doing all sorts of antics today. It lost an hour this morning, and this

afternoon it gained two. I found it was very highly magnetized--I could

pick up needles with the balance wheel. I demagnetized it; now it runs

all right.

"But to get back, he anchors his ship, then, leaving it invisible, he

goes to the air lock, and enters. He wears a high altitude suit, and on

his back he has a portable invisibility set and the fuel for his torch.

The gas has already put everyone to sleep, so he goes into the ship,

still invisible, and melts open the safe.

"His power supply for the invisibility machine seems to be somewhat of a

problem, but I think I would use a cylinder of liquid air, and have a

small air turbine to run a high voltage generator. He probably uses the

same system on a larger scale to run his big machine on the ship. He

can't use an engine for that either.

"That torch of his is interesting, too. We have had atomic hydrogen

welding for some time, and atomic hydrogen releases some 100,000

calories per mole of molecular hydrogen; two grains of gas give one

hundred thousand calories. Oxygen has not been prepared in any

commercial quantity in the atomic state. From watching that man's torch,

from the color of the flame and other indications, I gather that he uses

a flame of atomic oxygen-atomic hydrogen for melting, and surrounds it

with a preheating jacket of atomic hydrogen. The center flame probably

develops a temperature of some 4000° centigrade, and will naturally make

that tungsten alloy run like water.

"As to the machine here--it is, as I said, a machine which impresses

very high frequencies on the body it is connected with. This puts the

molecules in vibration at a frequency approaching that of light, and

when the light impinges upon it, it can pass through readily. You know

that metals transmit light for short distances, but in order that the

light pass, the molecules of metal must be set in harmonic vibration at

a rate approaching the frequency of light. If we can impress such a

vibration on a piece of matter, it will then transmit light very freely.

If we impress this vibration on the matter, say the body, electrically,

we get the same effect and the body becomes perfectly transparent. Now,

since it is the vibration of the molecules that makes the light pass

through the material, it must be stopped if we wish to see the machine.

Obviously it is much easier to detect me here among solid surroundings,

than in the plane high in the sky. What chance has one to detect a

machine that is perfectly transparent when there is nothing but

perfectly transparent air around it? It is a curious property of this

vibrational system of invisibility that the index of refraction is made

very low. It is not the same as that of air, but the difference is so

slight that it is practically within the limits of observation error; so

small is the difference that there is no 'rainbow' effect. The

difference of temperature of the air would give equal effect.

"Now, since this vibration is induced by radio impulse, is it not

possible to impress another, opposing radio impulse, that will overcome

this tendency and bring the invisible object into the field of the

visible once more? It is; and this machine on the table is designed to

do exactly that. It is practically a beam radio set, projecting a beam

of a wavelength that alone would tend to produce invisibility. But in

this case it will make me visible. I'm going to stand right here, and

Bob can operate that set."

Arcot strode to the middle of the room, and then Morey turned the

reflector of the beam set on him. There was a low snap as Arcot turned

on his set, then he was gone, as suddenly as the coming of darkness when

a lamp is extinguished. He was there one moment, then they were staring

at the chair behind him, knowing that the man was standing between them

and it and knowing that they were looking through his body. It gave them

a strange feeling, an uncomfortable tingling along the spine. Then the

voice--it seemed to come from the air, or some disembodied ghost as the

invisible man called to Morey.

"All right, Bob, turn her on slowly."

There was another snap as the switch of the disrupter beam was turned

on. At once there was a noticeable fogginess in the air where Arcot had

been. As more and more power was turned into the machine, they saw the

man materialize out of thin air. First he was a mere shadowy outline

that was never fully above the level of conscious vision. Then slowly

the outlines of the objects behind became dimmer and dimmer, as the body

of the man was slowly darkened, till at last there was only a wavering

aura about him. With a snap Morey shut off his machine and Arcot was

gone again. A second snap and he was solid before them. He had shut off

his apparatus too.

"You can see now how we intend to locate our invisible pirate. Of course

we will depend on directional radio disturbance locating devices to

determine the direction for the invisibility disrupter ray. But you are

probably marvelling at the greatness of the genius who can design and

construct this apparatus all in one day. I will explain the miracle. I

have been working on short wave phenomena for some time. In fact, I had

actually made an invisibility machine, as Morey will testify, but I

realized that it had no commercial benefits, so I didn't experiment with

it beyond the laboratory stunt stage. I published some of the theory in

the Journal of the International Physical Society--and I wouldn't be

surprised to learn that the pirate based his discovery on my report.

"I am still working on a somewhat different piece of apparatus that I

believe we will find very relevant to this business. I'll ask you to

adjourn after tonight's meeting for another twenty-four hours till I can

finish the apparatus I am working on. It is very important that you be

here, Fuller. I am going to need you in the work to follow. It will be

another problem of design if this works out, as I hope it will."

"I'll certainly make every effort to be here, Arcot," Fuller assured

him.

"I can promise you a tough problem as well as an interesting one." Arcot

smiled. "If the thing works, as I expect it to, you'll have a job that

will certainly be a feather for your cap. Also it will be a change."

"Well, with that inducement, I'll certainly be here. But I think that

pirate could give us some hints on design. How does he get his glider

ten miles up? They've done some high-altitude gliding already. The

distance record took someone across the Atlantic in 2009, didn't it? But

it seems that ten miles straight up is a bit too steep for a glider.

There are no vertical air currents at that height."

"I meant to say that his machine is not a true glider, but a

semi-glider. He probably goes up ten miles or more with the aid of a

small engine, one so small it probably takes him half a day to get

there. And it would be easy for a plane to pass through the lower

traffic lanes, then, being invisible, mount high and wait for the air

liner. He can't use a very large engine, for it would drag him down, but

one of the new hundred horsepower jobs would weigh only about fifty

pounds. I think we can draw a pretty good picture of his plane from

scientific logic. It probably has a tremendous wingspread and a very

high angle of incidence to make it possible to glide at that height, and

the engine and prop will be almost laughably small."

* * * * *

The next evening the men got together for dinner, and there was

considerable speculation as to the nature of the discovery that Arcot

was going to announce, for even his father had no knowledge of what it

was. The two men worked in separate laboratories, except when either had

a particularly difficult problem that might be solved by the other. All

knew that the new development lay in the field of short wave research,

but they could not find out in what way it concerned the problem in

hand.

At last the meal was over, and Arcot was ready to demonstrate.

"Dad, I believe that you have been trying to develop a successful solar

engine. One that could be placed in the wings of a plane to generate

power from the light falling on that surface. In all solar engines what

is the greatest problem to be solved?"

"Well, the more I investigate the thing, the more I wonder which is the

greatest. There are a surprising number of annoying problems to be met.

I should say, though, that the one big trouble with all solar engines,

eliminating the obvious restriction that they decidedly aren't

dependable for night work, is the difficulty of getting an area to

absorb the energy. If I could get enough area, I could use a very low

efficiency and still have cheap power, for the power is absolutely free.

The area problem is the greatest difficulty, no doubt."

"Well," Arcot junior said quietly, "I think you have a fairly good area

to use, if you can only harness the energy it absorbs. I have really

developed a very efficient solar engine. The engine itself requires no

absorbing area, as I want to use it; it takes advantage of the fact that

the Earth is absorbing quintillions of horsepower. I have merely tapped

the power that the Earth has already absorbed for me. Come here."

He led the way down the corridor to his laboratory, and switched on the

lights. On the main laboratory bench was set up a complicated apparatus

of many tubes and heavy bus bar connectors. From the final tube two thin

wires ran to a long tubular coil. To the left of this coil was a large

relay switch, and a rheostat control.

"Turn on the relay, Dad, then slowly rotate the controller to the left.

And remember that it is rather powerful; I know this doesn't look like a

solar engine, and nine o'clock at night seems a peculiar hour to

demonstrate such a thing, but I'll guarantee results--probably more than

you expect."

Dr. Arcot stepped up to the controls and closed the switch. The lights

dimmed a bit, but immediately brightened again, and from the other end

of the room came a low, steady hum as the big transformer took up the

load.

"Well, from the sound of that ten K.W. transformer there, if this engine

is very efficient we ought to get a terrific amount of power out of it."

Dr. Arcot was smiling amusedly at his son. "I can't very well control

this except by standing directly in front of it, but I suppose you know

what you're doing."

"Oh, this is a laboratory model, and I haven't gotten the thing into

shape really. Look at the conductors that lead to the coil; they

certainly aren't carrying ten K.W."

Dr. Arcot slowly rotated the rheostat. There was a faint hum from the

coil; then it was gone. There seemed to be no other result. He rotated

it a bit more; a slight draught sprang up within the room. He waited,

but when nothing more startling occurred, he gave the rheostat a sharp

turn. This time there was absolutely no doubt as to the result. There

was a roar like a fifty-foot wind tunnel, and a mighty blast of cold air

swept out of that coil like a six-inch model of a Kansas cyclone. Every

loose piece of paper in the laboratory came suddenly alive and whirled

madly before the blast of air that had suddenly leaped out. Dr. Arcot

was forced back as by a giant hand; in his backward motion his hand was

lifted from the relay switch, and with a thud the circuit opened. In an

instant the roar of sound was cut off, and only a soft whisper of air

told of the furious blast that had been there a moment before.

The astonished physicist came forward and looked at the device a moment

in silence, while each of the other men watched him. Finally he turned

to his son, who was smiling at him with a twinkle in his eye.

"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.