The Sirius loafed along through the ether at normal acceleration just outside the orbit of Mars and a million miles north of the ecliptic plane. In the control room, which had been transformed into a bewilderingly complete laboratory, Norman Brandon strode up and down, waving his arms, his unruly black hair on end, addressing savagely his friend and fellow-scientist, who sat unmoved and at ease.

"For cat's sake, Quince, let's get busy! They're outside somewhere, since the police have scoured every cubic kilometer within range of the power plants without finding a trace of them. We've got the power question licked right now—with these fields we can draw sixty thousand kilofranks from cosmic radiation, which is lots more than we'll ever need. We haven't drawn a frank from a plant in a month, and we've had to cut our field strength down to a whisper to keep from burning out our accumulators. We can hunt as far as Neptune easy—we can go to Alpha Centauri if we want to. This thing of piffling and monkeying around here's pulling my cork, and for the ten thousand four hundred and sixty seventh time I say let's prowl and prowl now! In fact, I'm getting so sick of sticking around doing nothing that I'm going out anyway, if I have to go alone in a lifeboat!"

Impetuous and violent as Brandon had always been, never before had he gone to such lengths as to suggest a disruption of the partnership; and Westfall, knowing that Brandon, in his most violent moments, never threatened idly, thought long before he replied.

"You will not go alone, of course. If you insist upon going without further preparation I will go too, no matter how foolish I think such a course to be. We have power, it is true, but in all other respects we are in no condition to meet an opponent having command of such resources as must certainly be possessed by those who attacked the Arcturus. Our detectors are inefficient, our system of vision is crude, to say the least, and many other things are still in the experimental stage. We have not the slightest idea whom or what we may encounter. It is all too probable that we would simply be throwing away uselessly the lives of more good men. It is also foolish from a general viewpoint, for as you already know, we and our assistants happen to be in better position to study these things than is any one else at the present time. However, I will compromise with you. We can learn much in a month if you will really try, instead of wasting time in fuming around the ship and indulging in these idiotic tantrums. If you will buckle down and really study the problems confronting us for thirty days, we will set out at the end of that time, ready or not."

"All x. I hate to do it, but we've been together too long to bust it up now," and Brandon turned toward his bench. Scarcely had he reached it when a series of dots and dashes roared from an amplifier. Both men leaped for the receiver which had so unexpectedly burst into sound, reaching it just as it relapsed into silence, and from the tape of the recorder they read the brief message.

"...h four seven ganymede point oh four seve...."

"That's Steve!" yelled Brandon. "Nobody else could build an ultra-sender! Direction?"

"No need of calculating distance or direction. Ganymede is the third major satellite of Jupiter."

"Sure. Of course, Quince—never thought of that. Dope enough—point oh four seven."

As Stevens had told Nadia, the message was completely informing to those for whom it was intended, and soon Brandon's answer was flying toward the distant satellite. He then started to call the officers of the Interplanetary Corporation, but was restrained by his conservative friend.

"It would be better to wait a while, Norman. In a few hours we will know what to tell them."

At high acceleration the Sirius drove toward the Jupiter-Earth-North plane, and Brandon calculated from his own bearings and from the current issue of the "Ephemeris" the time at which Stevens' reply should be received. Two minutes before that time he was pacing up and down in front of the ultra-receiver, and fifteen seconds after it he snapped:

"Come on, Perce, get busy! Shake a leg!"

"Oh, come, Norman; give him a few minutes' leeway, at least," said Westfall, with amused tolerance. "Even if your calculations are that accurate—which of course they are," he added hastily at a stormy glance from hot black eyes, "since we received that message direct, instead of through one of our relay stations, Stevens probably has been throwing it around for hours or perhaps days, looking for us, and the shock of hearing from us at last might well have put him out of control for a minute or two."

The carrier wave hissed into the receiver, forestalling Brandon's fiery reply, followed closely by the code signals they had been expecting. As soon as the story had been told, and while Brandon was absorbed in the scientific addenda of Stevens, Westfall thoughtfully called up Newton, Nadia's father.

"Nadia is alive, free, safe, well, and happy," he shot out without preliminary or greeting, as soon as the now lined features of the director showed upon the communicator screen, and the careworn countenance smoothed magically into the keen face of the fighting Newton of old, as Westfall recounted rapidly the tale of the castaways.

"They apparently have not suffered in any way," he concluded. "All that Stevens wants is some cigarettes, and your daughter's needs, while somewhat more numerous than his, seem to be only clothes, powder, perfume, and candy. Therefore we need not worry about them. The fate of the others is still unknown, but there seems to be a slight possibility that some of them may yet be rescued. You may release as much or as little of this story as may seem desirable. Stevens is still sending data of a highly technical nature. We shall arrive there at 21:32 next Tuesday."

In due time the message from Ganymede ended and Brandon, with many pages of his notebook crammed with figures and equations, snapped off the power of the receiver and turned to his bench. Gone was the storming, impetuous rebel; his body was ruled solely by the precise and insatiable brain of the research scientist.

"He's great, that kid Perce! When I see him, I'm going to kiss him on both cheeks. He's got enough dope on them to hang them higher than Franklin's kite, and we'll nail those jaspers to the cross or I'm a polyp! He's crazier than a loon in most of his hunches, but he's filled four of our biggest gaps. There is such a thing, as a ray-screen, you kill-joy, and there are also lifting or tractor rays—two things I've been trying to dope out and that you've been giving me the Bronx cheer on. The Titanians have had a tractor ray for ages—he sent me complete dope on it—and the Jovians have got them both. We'll have them in three days, and it ought to be fairly simple to dope out the opposite of a tractor, too—a pusher or presser beam. Say, round up the gang, will you, while I'm licking some of this stuff into shape for you to tear apart? Where are Venus and Mars? Um ... m ... m. Tell Alcantro and Fedanzo to come over here pronto—give 'em a special if necessary. We'll pick up Dol Kenor and Pyraz Amonar on the way—no, get them to Tellus, too. Then we'll get action quicker. Those four are all I want—get anybody else you want to come along."

His hands playing over the keys of an enormous calculating machine, Brandon was instantly immersed in a profound mathematico-physical problem; deaf and blind to everything about him. Westfall, knowing well that far-reaching results would follow Brandon's characteristic attack, sat down at the controls of the communicator. He first called Mars, the home planet of Alcantro and Fedanzo, the foremost force-field experts of three planets; and was assured in no uncertain terms that those rulers of rays were ready and anxious to follow wherever Brandon and Westfall might lead. Thence to Venus, where Dol Kenor, the electrical wizard, and Pyraz Amonar, the master of mechanism, also readily agreed to accompany the expedition. He then called the General-in-Chief of the Interplanetary Police, requesting a detail of two hundred picked men for the hazardous venture. These most important calls out of the way, he was busy for over an hour giving long-distance instructions so that everything would be in readiness for the servicing of the immense space-cruiser the following Tuesday night.

Having guarded against everything his cautious and far-seeing mind could envisage, he went over to Brandon's desk and sat down, smoking contemplatively until the idea had been roughed out in mathematical terms.

"Here's the rough draft of the ray screen, Quince. We generate a blanket frequency, impressed upon the ultra carrier wave. That's old stuff, of course. Here's the novelty, in equation 59. With two fields of force, set up from data 27 to 43, it will be possible actually to project a pure force of such a nature that it will react to de-heterodyne the blanketing frequency at any predetermined distance. That, of course, sets up a barrier against any frequency of the blanketed band. Incidentally, an extension of the same idea will enable us to see anywhere we want to look—calculate a retransmitting field."

"One thing at a time, please. That screen may be possible, but those fields will never generate it. Look at datum 31, in which your assumptions are unsound. In order to make any solution at all possible you have assumed cosine squared theta negligible. Mathematically, it is of course vanishingly small compared to the first power of the cosine, but fields of that type must be exact, and your neglect of the square is indefensible. Since you cannot integrate with the squared term in place, your whole solution fails."

"Not necessarily. We'll go back to 29, and put in sine squared theta minus one equal to z sub four. That gives us a coversed sine in 30, and then we integrate...."

Thus the argument raged, and all the assistants whose work was not too pressing gathered around unobtrusively, for it was from just such fierce discussions as this that the ultra-radio and other epoch-making discoveries had come into being. Yard after yard of calculator paper was filled with equations and computations. Weirdly shaped curves were drawn, with arguments at every point—arguments hot and violent from Brandon, from Westfall cold and precise, backed by lightning calculations and with facts and diagrams culled from the many abstruse works of reference, which by this time literally covered the bench and overflowed upon the floor.

It was in this work that the strikingly different temperaments and abilities of the two scientists were revealed. Brandon never stood still, but walked around jerkily, chewing savagely the stem of an ancient and reeking pipe, gesticulating vigorously, the while his keen and agile mind was finding a way over, around, or through the apparently insuperable obstacles which beset their path; by means of mathematical and physical improvisations, which no one not inspired by sheer genius could have evolved. Westfall, seated quietly at the calculator, mercilessly shredded Brandon's theories to ribbons, pointing out their many flaws with his cold, incisive reasoning and with rapid calculations of the many factors involved. Then Brandon would find a remedy for each weakness in turn and, when Westfall could no longer find a single flaw in the structure, they would toss the completed problem upon a table and attack the next one with unabated zeal. Brandon, in his light remark that the two made one real scientist, had far understated the case—those two brains, each so powerful and each so perfectly complementing the other, comprised the master-scientist who was to revolutionize science completely in a few short years.

To such good purpose did they labor that the calculations were practically finished by the time they reached the earth. There the ship was serviced with a celerity that spoke volumes for the importance of her mission—even the Aldebaran, the dazzlingly gold-plated queen of the fleet, waited unattended and disregarded on minus time while the entire force of the Interplanetary Corporation concentrated upon the battle-scarred old hulk of the Sirius. Brandon was surprised when he saw the two companies of police, but characteristically accepted without question the wisdom of any decision of his friend, and cordially greeted Inspector-General Crowninshield, only a year or so older than himself, but already in charge of a Division.

"Keen-looking bunch, Crown. Lot of different outfits—volunteers for special duty from the whole Tellurian force?"

"Yes. Everybody wanted to go, and there threatened to be trouble over the selection, so we picked the highest ratings from the whole Service. If there ever was such a thing as a picked force, we shall have it with us."

"What d'you mean, 'us'? You aren't going, are you?"

"Try to keep me from it! The names of all five of us I-G's were put in a hat, and I was lucky."

"Well, you may come in handy, at that," Brandon conceded. "And here's the big boss himself. Hi, Chief!"

"Ho, Brandon! Ho, Westfall!" Newton, Chairman of the Board of Directors of the IPC, shook hands with the two scientists. "Your Martians and Venerians are in Lounge Fifteen. I suppose that you have a lot of things to thrash out, so you may as well start now. Everything is being attended to—I'll take charge now."

"You going along, too?" asked Brandon.

"Going along, too? I'm running this cruise!" Newton declared. "I may take advice from you on some things and from Crowninshield on others, but I am in charge!"

"All x—it's a relief, at that," and Brandon and Westfall went to join their fellow-scientists in the designated room of the space-cruiser.

What a contrast was there as the representatives of three worlds met! All six men were of the same original stock or of a similar evolution—science has not, even yet, decided the question definitely. Their minds were very much alike, but their respective environments had so variantly developed their bodily structures that to outward seeming they had but little in common.

Through countless thousands of generations the Martians had become acclimated to a planet having little air, less water, and characterized by abrupt transitions from searing heat to bitter cold: from blinding light to almost impenetrable darkness. Eight feet tall and correspondingly massive, they could barely stand against the gravitational force of the Earth, almost three times as great as that of Mars, but the two Martian scientists struggled to their feet as the Terrestrials entered.

"As you were, fellows—lie down again and take it easy." Brandon suggested in the common Interplanetarian tongue. "We'll be away from here very soon, then we can ease off."

"We greet our friends standing as long as we can stand," and, towering a full two feet above Brandon's own six-feet-two, Alcantro and Fedanzo in turn engulfed his comparatively tiny hand in a thick-shelled paw and lifted briefly the inner lids of quadruply-shielded eyes. For the Martian skin is not like ours. It is of incredible thickness; dry, pliable, rubbery, and utterly without sensation: heavily lined with fat and filled throughout its volume with tiny air-cells which make it an almost perfect non-conductor of heat and which prevent absolutely the evaporation of the precious moisture of the body. For the same reasons their huge and cat-like eyes are never exposed, but look through sealed, clear windows of membrane, over which may be drawn at will one or all of four pairs of lids—lids transparent, insensible, non-freezable, air-spaced insulators. Even the air they exhale carries from their bodies a minimum of the all-important heat and moisture, for the passages of their nostrils do not lead directly to the lungs, as do ours. They are merely the intakes for a tortuous system of tubes comprising a veritable heat-exchanger, so that the air finally expelled is in almost perfect equilibrium with the incoming supply in temperature and in moisture content. A grayish tan in color, naked and hairless—though now, out of deference to Terrestrial conventions, wearing light robes of silk—indifferent alike to any extreme of heat or cold, light or darkness: such were the two forbidding beings who arose to greet their Terrestrial friends, then again reclined.

"I suppose that you have been given to drink?" Westfall made sure that they had been tendered the highest hospitality of Mars.

"We have drunk full deeply, thanks; and it was not really necessary, for we drank scarcely three weeks ago."

Brandon and Westfall turned then and greeted the two Venerians, as different from the Martians as they were from the Terrestrials. Of earthly stature, form, and strength, yet each was encased in a space-suit stretched like a drum-head, and would live therein or in the special Venerian rooms of the vessel as long as the journey should endure. For the atmosphere of Venus is more than twice as dense as ours, is practically saturated with water-vapor, carries an extremely high concentration of carbon dioxide, and in their suits and rooms is held at a temperature of one hundred and ten degrees Fahrenheit. The lenses of their helmets were of heavy, yellowish-red composition, protecting their dead-white skins and red eyes from all actinic rays—for the Venerian lives upon the bottom of an everlasting sea of fog and his thin epidermis, utterly without pigmentation, burns and blisters as frightfully at the least exposure to actinic light as does ours at the touch of a red-hot iron.

Out in space at last, cruising idly with the acceleration set at a point bearable for the Martians, Westfall called the meeting to order and outlined the situation facing them. Brandon then handed around folios of papers, upon which the Venerians turned the invisible infra-red beams of the illuminators upon their helmets, thus flooding them with the "light" to which their retinas were most responsive.

"Here's the data," Brandon began. "As you see from Sheet 1, we can already draw any amount of power we shall need from cosmic radiation alone...."

"Perpetual motion—ridiculous!" snapped from the sending disk upon the helmet of the master of mechanism.

"Not at all, Amonar," put in his fellow Venerian, "any more than a turbo-generator at the foot of a waterfall is perpetual motion. Those radiations originate we know not where, probably as a result of intra-atomic reactions. The fields of force of our hosts merely intercept these radiations, as a water-driven turbine intercepts the water. We merely use a portion of their energy before permitting them to go on, to we know not what end. Truly you have made a notable achievement in science, Tellurian friends, and we congratulate you upon its accomplishment. Please proceed."

"Upon the following sheets are described the forces employed by the Jovians, as we shall call them until we find out who or what they really are. We will discuss these forces later. For each force we have already calculated a screen, and we have also calculated various other forces of our own, with which we hope to arm ourselves before we reach Ganymede. The problems facing us are complex, since there are some nine thousand forcebands of the order in which we are working, each differing from all the others as much as torque differs from tension, or as much as red differs from green. Therefore we have appealed to you for help, knowing that we could do but little alone. Alcantro and Fedanzo will supervise the construction of the generators of the various fields from these calculations. Dol Kenor will correlate power and electricity to and with the fields. Westfall and I will help work out the theoretical difficulties as they arise. Pyraz Amonar, who can devise and build a machine to perform any conceivable mechanical task, will help us all in the many mechanical difficulties we shall certainly encounter. Discussion of any point is now in order."

Step by step and equation after equation the calculations and plans were gone over, until every detail was clear in each mind. Then the men bent to their tasks; behind them not only the extraordinarily complete facilities of that gigantic workshop which was the Sirius; but also the full power of the detachment of police—the very cream of the young manhood of the planet. Week after toilsome week the unremitting labor went on, and little by little the massive cruiser of the void became endowed with an offensive and defensive armament incredible. An armament conceived in the fertile and daring brain of a sheer genius, guided only by the knowledge that such things were already in existence somewhere; reduced to working theory by a precise, mathematical logician; translated into fields of force by the greatest known experts; powered by the indefatigable efforts of an electrical wizard; made possible by the artful mechanical devices of the greatest inventor that three worlds had ever known! Thus it was that they approached Ganymede, ready, with blanketing screens full out, save for one narrow working band, and with a keen-eyed observer at every plate. When even the hyper-critical Westfall was convinced that their preparations were as complete as they could be made with the limited information at hand, Brandon directed a beam upon the satellite and tapped off a brief message:

"stevens ganymede will arrive in about ten hours direct carrier beam toward sun we can detect it and will follow it to wherever you are sirius."

"ipv sirius," came the reply, "everything here, all x glad to see you thanks newton and stevens."

Brandon, at the controls, scanning his screens narrowly, dropped the vessel down to within a mile or two of the point of origin of Stevens' carrier beam without incident; then spoke to Westfall, at his side, with a grin.

"Nice layout the kid's got down there, Quince. It's too bad—don't look like we're going to get any action for our money a-tall. 'Sa shame, too—what's the use of wasting it, now that we've got it all made?"

"We are not done yet," cautioned Westfall, and even as he spoke an alarm bell burst into strident clamor—one of their far-flung detector screens was telling the world that it had encountered a dangerous frequency. The new ultra-lights flared instantly along the line automatically laid down by the detector, and upon the closely ruled micrometer screen of Brandon's desk there glowed in natural color the image of a globular space-ship, approaching them with terrific speed.

"Men all stationed, of course, Crown?"

"Stationed and ready." Crowninshield, phones at his ears and microphone at his lips, was staring intently into his own plate.

"Kinda think I'll do most of it from here, but you can't always tell. If they get inside my guard you all know what to do."

"All x."

Expecting another such hollow victory as the other Hexan vessel had won over the defenseless Arcturus, the small stranger flashed nearer and nearer that huge and featureless football of armor steel. Within range, she launched her flaming plane of energy, but this time that Jovian sheet of force did not encounter unprotected and non-resisting steel. Upon the outer ray-screen, flaming white into incandescent defense, the furious bolt spent itself, and in the instant of the launching of the searing blade of flame, Brandon had gone into action. Switch after switch drove home, and one after another those frightful fields of force, those products of the mightiest minds of three planets, were hurled out against the tiny Jovian sphere. Driven as they were by the millions upon millions of horsepower stored in the accumulators of the Sirius they formed a coruscating spherical shell of intolerable energy all around the enemy vessel, but even their prodigious force was held at bay by the powerful defensive screens of the smaller space-ship. But attack the Jovian could not, every resource at her command being necessary to fend off the terrific counter-attack of her intended prey, and she turned in flight. Small and agile as she was, the enormous mass of the Sirius precluded any possibility of maneuvering with the Jovian, but Brandon had no intention of maneuvering. Rapid as the motions of the stranger were and frantic as was her dodging, the terrific forces of the tractor beams of the Interplanetary Vessel held her in an unbreakable grip, and although she dragged the massive Sirius hither and thither, she could not escape.

"Hm ... m ... m," mused Brandon. "We seem to be getting nowhere fast. How much power we using, Mac, and how much have we got coming in?"

"Output eighty-five thousand kilofranks," replied MacDonald, the first assistant. "Intake forty-nine thousand."

"Not so good—can't hold out forever at that rate. Shove out the receptor screens to the limit and drive 'em. They figure a top of sixty thousand, but we ought to pick up a little extra from that blaze out there. Drive 'em full out or up to sixty-five, whichever comes first. Can't seem to crush his screens, so I guess we'll have to try something else," and a thoughtful expression came over his face as he slowly extended his hand toward another switch, with a questioning glance at Westfall.

"Better not do that yet, Norman. Use that only as a last resort, after everything else has failed."

"Yeah—I'm scared to death of trying it, and it isn't necessary yet. He must have an open slit somewhere to work through, just as we have. I'll feel around for it a while."

"Is there any way of hetrodyning the new visiray upon the exploring frequency?"

"Hm ... m.... Never thought of that—it would be nice, too.... I think we can do it, too. Watch 'em, Quince, and holler if they start anything."

He abandoned his desk and established the necessary connections between the visiray apparatus and the controls of his board. There was a fierce violet-white glare from the plate as he closed the switch, and he leaped back with his hands over his eyes, temporarily blinded.

"Wow, that's hot stuff!" he exclaimed. "It works, all x, to the queen's taste," as he donned his heavy ray-goggles and resumed his place.

After making certain that the visiray was precisely synchronized and phased with the searching frequency, he built up the power of that beam until it was using twenty thousand kilofranks. Then, by delicately manipulating the variable condensers and inductances of his sensitive shunting relay circuits, he slowly shifted that frightful rod of energy from frequency to frequency, staring into the brilliant blankness of his micrometer screen as he did so. After a few minutes of search the screen darkened somewhat, revealing the image of the Jovian globe. Brandon instantly shifted into that one channel the entire power of his attack; steadying the controls to bring the sphere of the Jovians into the sharpest possible focus, knowing that he had found the open slit and that through it there was pouring upon the enemy the full power of his terrible weapon.

In the fraction of a second before the Jovians could detect the attack and close the slit, he saw a portion of the wall of their vessel flare into white heat and literally explode outward in puffs and gouts of flaming, molten metal and of incandescent gases. But the thrust, savage as it was, had not been fatal and the enemy countered instantly. Now that the crushing force of the full-coverage attack was lessened for a moment, through another slit there poured a beam of energy equal to the Terrestrials' own—a beam of such intense power that the outer screen of the Sirius flared from red through the spectrum, to and beyond the violet, and went black in less than a second, and the inner screen had almost gone down before Brandon's lightning hands could restore the complete coverage that so effectively blanketed the forces of the enemy.

"Well, we're back to the status quo," announced Brandon, calmly. "It's a good gag they didn't have time to locate our working slit—if they had pushed that stuff through our open channel, we'd have gotten frizzled up some around the edges. As it was, we got the edge on that exchange—take it from your Uncle Dudley, Quince, that bird knows that he's been nudged!"

Again he searched the entire band for an opening, but could find none. The enemy had apparently retired into a tightly closed shell of energy. The small vessel no longer struggled, nor even moved, but was merely resisting passively.

"Not an open channel, not even one for him to work through—he can't wiggle. Well, that won't get him anything. We're so much bigger than he is, that we can outlast him and will get him some time, since he's bound to run out of power before we do. I don't believe he can receive anything, sealed up as he is, and he can't have accumulators enough more efficient than ours to make up the difference, can he, Quince?"

"It is quite possible. For instance, although we have never heard of any progress being made along such lines, it has been pointed out repeatedly that synthesis of a radio-active element of very high atomic weight would theoretically yield an almost perfect accumulator—one many thousands of times as efficient as ours in mass-to-energy ratio. Then, too, you realize, of course, that there is a bare possibility that intra-atomic energy may not be absolutely impossible."

"Nix on that, Quince. I'll stand for a lot, but not for that last idea! It's hard to say that anything's impossible, of course, except things made so by definition or by being contrary to observational facts, but the best work shows that intra-atomic energy is just about as impossible as anything can well be. It has been shown pretty conclusively that all ordinary matter is already in its most stable state, so that work must be done upon any ordinary atom to decompose it. Besides, if he had either radioactive accumulators or intra-atomic energy, he would have cut us up long ago. Nope, the answer is that he's probably yelled for help and is trying to hold out until it gets here," was Brandon's rejoinder.

"What can we do about it?" asked Quince.

"Don't know yet. I do know, though, that we aren't half as ready for trouble as I thought we were. There's a dozen things I want to do that I can't because we haven't got the stuff. Don't say 'I told you so,' either—I know you did! You're the champion ground-and-lofty thinker of the century. Alcantro!"

"Here!"

"Round up the gang, will you, and figure me out a screen and a set of meters that will indicate an open band? We lose too much time feeling around anyhow, and we're too apt to take one on the chin while we're doing it. Also, you ought to make it so it'll shoot a jolt into the opening, while you're at it," said Brandon.

"We shall begin at once," and the massive Martian as he replied, stepped over to the calculating machine.

"Well, Quince, we can't do much to him this way—he's crawled into a hole and pulled the hole in after him. Gosh, I wish we had more stuff!"

"After all, we have everything whose necessity and practicability could have been foreseen in the light of our information. We can, of course, go further."

"You chirped it! But we can't let things ride this way or we'll get our hair singed. We'll have to decorate him with the grand slam, I guess."

"Yes, it seems as though the time for emergency measures has arrived."

"Put everything on the center of the band?"

"That is probably the best frequency to use in a case of this kind."

"He can't control, so we'll push him down close to the ground before we go to work on him—so we don't have so far to fall if anything goes screwy with the works. Here's hoping nothing gives away!"

The Sirius, almost against the flaming screens of the Jovian, and both vessels very close to the surface of the satellite, Brandon tested the power leads briefly, adjusted dials and coils, then touched the button which actuated the relays—relays which in turn drove home the gigantic switches that launched a fearsome and as yet untried weapon. Instantly released, the full seven hundred thousand kilofranks of their stupendous batteries of accumulators drove into the middle frequency of the attacking band, and Brandon's heart was in his mouth as he stared into the plate to see what would happen. He saw! Everything in the Sirius held fast, and under the impact of the inconceivable plane of force, the screens of the enemy vessel flared instantly into an even more intense incandescence and in that same fleeting instant went down, and all defenses vanished as the metal sphere fell apart into two halves, as would an apple under the full blow of a broad-axe.

Brandon quickly shut off his power and stared in relief into the central compartment of the globular ship of space, now laid open, and saw there figures, one or two of which were moving weakly. As he looked, one of these feebly attempted to raise a peculiar, tubular something toward a helplessly fettered body. Even as Brandon snatched away the threatening weapon with a beam of force, he recognized the captive.

"Great Cat, there's Breckenridge!" he gasped, and directed a lifting beam upon the bound and unconscious prisoner. Rapidly, but carefully, he was brought through the double airlock and into the control room, where his shackles were cut away and where he soon revived under vigorous and skilful treatment.

"Any more of you in there? Did I hit any of you with that beam?" demanded Brandon, intensely, as soon as Breckenridge showed signs of understanding.

"King's in there somewhere, and there's a Callistonian human being that you mustn't kill," the chief pilot replied, weakly and with great effort in every word. "Don't believe that you hit anybody direct, but the shock was pretty bad." Having delivered his message, he lay back, exhausted.

"All x. Crown, give me a squad...."

"Not on your life!" barked the general. "This is my job and I'll do it myself. Your job is fighting the Sirius—stay with it!"

"Not in seven thousand years—I'm in on this, too," Brandon protested, but was decisively overruled by Newton.

"You belong right here at this board, since no one else can handle it the way you can. Stay here!" he commanded.

"All right," grudgingly assented the physicist, and held the Sirius upright, with her needle-sharp stern buried a few feet deep in the ground.

He watched the wreckage jealously while Crowninshield and forty helmeted men issued from the service door in the lower ultra-light compartment and advanced upon the two halves of the enemy vessel. As no hostile demonstrations ensued, scaling ladders were quickly placed and with weapons at the alert the police boarded the hemispheres, manacled the still helpless beings visible, and, after laying down a fog of stupefying gas, vanished into compartments beyond the metal partitions. After a short time they reappeared and climbed down the scaling ladders, carrying several inert forms, and Brandon spoke into his transmitter.

"King all x, Crowninshield?"

"I think so. Not being in the control room he was not as badly shocked by the passage of the beam as were Breckenridge and those you saw. The things in the other rooms were about ready to fight, so we gave them a little whiff of tritylamin, but Captain King will be as good as ever in a few minutes."

"Fine business!" The police entered the Sirius, the service doors clanged shut, and Brandon turned to Westfall.

"While they're coming up, I guess I'll pick up Perce and Miss Newton. We'd better get them aboard and beat it, while we're all in one piece!"

But even before he could send out the exploring beam of his communicator, the voice of Stevens came from the receiver.

"Hi, Brandon and Westfall! We've watched the whole show. Congratulations, fellows! Welcome to Ganymede! You are in our valley—we're upstream from you about three hundred meters; just below the falls, on the meadow side."

"All x," Brandon acknowledged. "We saw you. Come on out where we can pick you up. We've got to get away from here, and get away fast!"

"We'll carry off the pieces of that ship, too, Quince—we may be able to get a lot of pointers from it," and Brandon swung mighty tractor beams upon the severed halves of the Jovian vessel, then extended a couple of smaller rays to meet the two little figures racing across the smooth green meadow toward the Sirius.