Slow, hard, and disheartening as the work had been at first, Stevens had never slackened his pace, and after a time, as his facilities increased, the exasperating setbacks decreased in number and severity and his progress became faster and faster. Large as the "Forlorn Hope" was, space was soon at a premium, for their peculiarly-shaped craft became a veritable factory, housing a variety of machinery and equipment unknown in any single earthly industrial plant. Nothing was ornamental—everything was stripped to its barest fundamental necessities—but every working part functioned with a smooth precision to delight the senses of any good mechanic.

In a cavern under the falls was the great turbine, to be full-fed by the crude but tight penstock which clung to the wall of the gorge, angling up to the brink of that stupendous cataract. Bedded down upon solid rock there was a high-tension alternator capable of absorbing the entire output of the mighty turbine. This turbo-alternator was connected to a set of converters from which the energy would flow along three great copper cables—the receptors of the lifeboats being altogether too small to carry the load—to the now completely exhausted accumulators of the "Forlorn Hope." All high-tension apparatus was shielded and grounded, so that no stray impulses could reveal to the possible detectors of the Jovians the presence of this foreign power plant. Housings, frames, spiders, all stationary parts were rough, crude and massive; but bearings, shafts, armatures, all moving parts, were of a polished and finished accuracy and balance that promised months and years of trouble-free operation. Everything ready for the test, Stevens took off his frayed and torn leather coveralls and moccasins and climbed nimbly up the penstock. He never walked down. Opening the head-gate, he poised sharply upon its extremity and took off in a perfect swan-dive; floating unconcernedly down toward that boiling maelstrom two hundred feel below. He struck the water with a sharp, smooth "slup!" and raced ashore, seizing his suit as he ran toward the turbo-alternator. It was running smoothly, and, knowing that everything was tight at the receiving end, he lingered about the power plant until he was assured that nothing would go wrong and that his home manufactured lubricating oil and grease would keep those massive bearings cool.

Hunger assailed him, and glancing at the sun, he noted that it was well past dinner-time.

"Wow!" he exclaimed aloud. "The boss just loves to wait meals—she'll burn me up for this!"

He ran lightly toward "home," eager to tell his sweetheart that the long awaited moment had arrived—that power was now flowing into their accumulators.

"Hi, Diana of the silver bow!" he called. "How come you no blow the dinner bell? Power's on—come give it a look!"

There was no answer to his hail, and Stevens paused in shocked amazement. He knew that never of her own volition would she be out so late—Nadia was gone! A rapid tour of inspection quickly confirmed that which he already knew only too well. Forgotten was his hunger, forgotten the power plant, forgotten everything except the fact that his Nadia, the buoyant spirit in whom centered his Universe, was lost or ... he could not complete the thought, even to himself.

Swiftly he came to a decision and threw off his suit, revealing the body of a Hercules—a body ready for any demand he could put upon it. Always in hard training, months of grinding physical labor and of heavy eating had built him up to a point at which he would scarcely have recognized himself, could he have glanced into a mirror. Mighty but pliable muscles writhed and swelled under his clear skin as he darted here and there, selecting equipment for what lay ahead of him. He donned the heavily armored space-suit which they had prepared months before, while they were still suspicious of possible attack. It was covered with heavy steel at every point, and the lenses of the helmet, already of unbreakable glass, had been re-enforced with thick steel bars. Tank and valves supplied air at normal pressure, so that his powerful body could function at full efficiency, not handicapped by the lighter atmosphere of Ganymede. The sleeves terminated in steel-protected rubber wristlets which left his hands free, yet sheltered from attack—wristlets tight enough to maintain the difference in pressure, yet not tight enough to cut off the circulation. He took up his mighty war-bow and the full quiver of heavy arrows—full-feathered and pointed with savagely barbed, tearing heads of forged steel—and slipped into their sheaths the long and heavy razor-sharp sword and the double-edged dirk, which he had made and ground long since for he knew not what emergency, and whose bell-shaped hilts of steel further protected his hands and wrists. Thus equipped, he had approximately his normal earthly weight; a fact which would operate to his advantage, rather than otherwise, in case of possible combat. With one last look around the "Forlorn Hope," whose every fitting spoke to him of the beloved mistress who was gone, he filled a container with water and cooked food and opened the door.

"It won't be long now; now it won't be long." Nadia caroled happily, buckling on her pack straps and taking up bow and arrows for her daily hunt. "I never thought that he could do it, but what it takes to do things, he's got lots of," she continued to improvise the song as she left the "Hope" with its multitudinous devices whose very variety was a never-failing delight to her; showing as it did the sheer ability of the man, whose brain and hands had almost finished a next-to-impossible task.

Through the canyon and up a well-worn trail she climbed, and soon came out upon the sparsely timbered bench that was her hunting grounds. Upon this day, however, she was full of happy anticipation and her mind was everywhere except upon her work. She was thinking of Stevens, of their love, of the power which he might turn on that very day, and of the possible rescue for which she had hitherto scarcely dared to hope. Thus it was that she walked miles beyond her usual limits without having loosed an arrow, and she was surprised when she glanced up at the sun to see that half the morning was gone and that she was almost to the foothills, beyond which rose a towering range of mountains.

"Snap out of it, girl!" she reprimanded herself. "Go on wool-gathering like this and your man will go hungry—and he'll break you right off at the ankles!" She became again the huntress, and soon saw an animal browsing steadily along the base of a hill. It was a six-legged, deer-like creature, much larger than anything she had as yet seen. But it was meat and her time was short, therefore she crept within range and loosed an arrow with the full power of her hunting bow. Unfamiliar as she was with the anatomy of the peculiar creature, the arrow did not kill. The "hexaped," as she instantly named it, sped away and she leaped after it. She, like her companion, had developed amazingly in musculature, and few indeed were the denizens of Ganymede, who could equal her speed upon that small globe, with its feeble gravitational force.

Up the foothills it darted. Beyond the hills and deep into a valley between two towering peaks the chase continued before Nadia's third arrow brought the animal down. Bending over the game, she became conscious of a strange but wonderful sweet perfume and glanced up, to see something which she certainly had not noticed when the hexaped had fallen. It was an enormous flower, at least a foot in diameter and indescribably beautiful in its crimson and golden splendor. Almost level with her head the gorgeous blossom waved upon its heavy stem; based by a massive cluster of enormous, smooth, dark green leaves. Entranced by this unexpected and marvelous floral display, Nadia breathed deeply of the inviting fragrance—and collapsed senseless upon the ground. Thereupon the weird plant moved over toward her, and the thick leaves began to enfold her knees. This carnivorous thing, however, did not like the heavy cloth of her suit and turned to the hexaped. It thrust several of its leaves into the wounds upon the carcass and fed, while two other leaves rasped together, sending out a piercing call.

In answer to the sound the underbrush crackled, and through it and upon the scene there crashed a vegetable-animal nightmare—the parent of the relatively tiny thing whose perfume had disabled the girl.

Its huge and gorgeous blossom was supported by a long, flexible, writhing stem, and its base was composed of many and highly specialized leaves. There were saws and spears and mighty, but sinuous tendrils; there were slender shoots which seemed to possess some sense of perception; there was the massive tractor base composed of extensible leaves which by their contraction and expansion propelled the mass along the ground. Parent and child fell upon the hexaped and soon bones and hair were all that remained The slender shoots then wandered about the unconscious girl in her strange covering, and as a couple of powerful tendrils coiled about her and raised her into the air over the monstrous base of the thing, its rudimentary brain could almost be perceived working as it sluggishly realized that, now full fed, it should carry this other victim along, to feed its other offspring when they should return to its side.

Barely outside the door of the "Forlorn Hope" Stevens whirled about with a bitter imprecation. He had already lost time needlessly—with a lookout plate he could cover more ground in ten minutes than he could cover afoot in a week. He flipped on the power and shot the violet beam out over the plateau to the district where he knew Nadia was wont to hunt. Not finding her there, he swung the beam in an ever widening circle around that district. Finally he saw a few freshly broken twigs, and scanned the scene with care. He soon found the trail of fresh blood which marked the path of the flight of the hexaped, and with the peculiar maneuverability of the device he was using, it was not long until he was studying the scene where the encounter had taken place. He gasped when he saw the bones and perceived three of Nadia's arrows, but soon saw that the skeleton was not human and was reassured. Casting about in every direction, he found Nadia's bow, and saw a peculiar, freshly trampled path leading from the kill, past the bow, down the valley. He could not understand the spoor, but it was easily followed, and he shot the beam along it at headlong speed until he came up with the monstrous creature that was making it—until he saw what burden that organism was carrying.

He leaped to the controls of the lifeboat, then dropped his hand. While the stream of power now flowing was ample to operate the lookout plates, yet it would be many hours before the accumulator cells would be in condition to drive the craft even that short distance.

"It'll take over an hour to get there—here's hoping I can check in all x," he muttered savagely, as he took careful note of the location and direction of the creature's trail and set off at a fast jog-trot.

The carnivorous flower's first warning that all was not well was received when Stevens' steel-shod feet landed squarely upon its base and one sweeping cut of his sword lopped off the malignant blossom and severed the two tendrils that still held the unconscious Nadia. With a quick heave of his shoulder, he tossed her lightly backward into the smooth-beaten track the creature had made and tried to leap away—but the instant he had consumed in rescuing the girl had been enough for the thing to seize him, and he found himself battling for his very life. No soft-leaved infant this, but a full-grown monster, well equipped with mighty weapons of offense and defense. Well it was for the struggling man that he was encased in armor steel as those saw-edged, hard-spiked leaves drove against him with crushing force; well it was for him that he had his own independent air supply, so that that deadly perfume eddied ineffective about his helmeted head! Hard and fiercely driven as those terrible thorns were, they could do no more than dent his heavy armor. His powerful left arm, driving the double-razor-edged dirk in short, resistless arcs, managed to keep the snaky tendrils from coiling about his right arm, which was wielding the heavy, trenchant sword. Every time that mighty blade descended it cleaved its length through snapping spikes and impotently grinding leaves; but more than once a flailing tendril coiled about his neck armor and held his helmet immovable as though in a vise, while those frightful, grinding saws sought to rip their way through the glass to the living creature inside the peculiar metal housing. Dirk and saber and magnificent physique finally triumphed, but it was not until each leaf was literally severed from every other leaf that the outlandish organism gave up the ghost.

Nadia had been tossed out into pure air, beyond the zone of the stupefying perfume, and she recovered her senses in time to see the finish of the battle. Stevens, assured that his foe was hors du combat, turned toward the spot where he had thrown Nadia's body. He saw that she was unharmed, and sprang toward her in relief. He was surprised beyond measure, however, to see her run away at a pace he could not hope to equal, encumbered as he was; motioning frantically at him the while to keep away from her. He stopped, astounded, and started to unscrew his helmet, whereupon she dashed back toward him, signaling him emphatically to leave his armor exactly as it was. He stood still and stared at her, an exasperated question large upon his face, until she made clear to him that he was to follow her at a safe distance, then she set off at a rapid walk. She led him back to where the hexaped had fallen, where she retrieved her bow and arrows; then, keeping a sharp lookout upon all sides, she went on to a small stream of water. She made the dumbfounded man go out into the middle of the creek and lie down and roll over in the water, approaching him sniffing cautiously between immersions. She made him continue the bathing until she could detect not even the slightest trace of the sweet, but noxious fragrance of that peculiarly terrible form of Ganymedean life. Only then did she allow him to remove his helmet, so that she could give him the greeting for which they both had longed and tell him what it was all about.

"So that's it, ace!" he exclaimed, still holding her tightly in his iron embrace. "Great balls of fire! I thought maybe you were still a little cuckoo. Anaesthetic perfume, huh? Hot stuff, I'd say—no wonder you bit—I would, too. It's lucky for us I was air-tight—we'd both be fee...."

"Stop it!" she interrupted him sharply, "Forget it—don't ever even think of it!"

"All x, ace. It's out like the well known light. What to do? It's getting darker than a hat, and we're a long way from home. Don't know whether I could find my way back in the dark or not; and just between you and me, I'm not particularly keen on night travel in these parts after what's just happened. Are you?"

"Anything else but," she assured him, fervently. "I'd lots rather stay hungry until tomorrow."

"No need of that—I've brought along enough supper for both of us. I'm hungry as a wolf, too, now that I have time to think of it. We'll eat and den up somewhere—or climb a tree. Those wampuses probably can't climb trees!"

"There's a nice little cave back there about a hundred meters. We'll pretend it's the Ritz," and they soon had a merry fire blazing in front of the retreat. There they ate of the provisions Stevens had brought. Then, while the man rolled up boulders before the narrow entrance of the cave, Nadia gathered leaves and made a soft bed upon its warm, dry floor.

"Good night, lover," and the girl, untroubled and secure now that Stevens was at her side, was almost instantly asleep; but the man was not sleepy. He thought of the power plant, even now sending its terrific stream of energy into his accumulators. He thought of the ultra radio—where could he get all the materials needed? He thought of his friends, wondering whether or not they would receive his message. He thought of Breckenridge and the other human beings who had been aboard the Arcturus, wondering poignantly as to their fate. He thought of Newton and of his own people, who had certainly given them up for dead long since.

But above all he thought of the beautiful, steel-true companion lying there asleep at his mailed feet, and he gazed down at her, his heart in his eyes. The firelight shone through the chinks between the boulders, casting a flickering ruddy light throughout the little cavern. Nadia lay there her head pillowed upon one strong, brown little hand. Her lips were red and sweetly curved, her cheek was smooth and firm as so much brown velvet. She was literally aglow with sheer beauty and with perfect health; and the man reflected, as he studied her hungrily, that this wild life certainly had agreed with her—she was becoming more surpassingly beautiful with every passing day.

"You little trump—you wonderful, lovely, square little brick!" he breathed silently, and bent over to touch her cheek lightly with his lips. Slight as the caress was, it disturbed her, and even in her sleep her subconscious mind sent out an exploring hand, to touch her Steve and thus be reassured. He pressed her hand and she settled back comfortably, with a long, deep breath; and he stretched his iron-clad length beside her and closed his eyes, firmly resolved not to waste a minute of this wonderful night in sleep.

When he opened them an instant later, it was broad daylight, the boulders had been rolled away, the fragrance of roasting meat permeated the atmosphere, and Nadia was making a deafening clamor, beating his steel breastplate lustily with the flat of his huge saber.

"Daylight in the swamp, you sleeper!" she exclaimed. "Roll out or roll up! Come and get it, before I throw it away!"

"I must have been kind of tired," he said sheepishly, when he saw that she had shot a bird and had cooked breakfast for them both while he had been buried in oblivion.

"Peculiar, too, isn't it?" Nadia asked, pointedly. "You only did about ten days' work yesterday in ten minutes, swinging this frightful snickersnee of yours. Why, you played with it as though it were a knitting-needle, and when I wanted to wake you up with it, I could hardly lift it."

"Thought you didn't want that subject even mentioned?" he tried to steer the talk away from his prowess with the broadsword.

"That was yesterday," airily. "Besides, I don't mind talking about you—it's thinking about us being ... you know ... that I can't stand."

"All x, ace. I get you right. Let's eat."

Breakfast over, they started down the valley, Stevens carrying his helmet under his arm. Hardly had they started however, than Nadia's keen eyes saw a movement through the trees, and, she stopped and pointed. Stevens looked once, then hand in hand they dashed back to their cave.

"We'll pile up some of the boulders and you lie low," he instructed her as he screwed on his helmet. She snapped open his face-plate.

"But what about you? Aren't you coming in, too?" she demanded.

"Can't—they'd surround us and starve us out. I'm safe in this armor—thank Heaven we made it as solid as we did—and I'll fight 'em in the open. I'll show 'em what the bear did to the buckwheat!"

"All right, I guess, but I wish I had my armor, too," she mourned as he snapped shut his plate and walled her into the cave with the same great rocks he had used the night before. Then, Nadia safe from attack, he drew his quiver of war-arrows into position over his shoulder, placed one at the ready on his bow-string and turned to face the horde of things rushing up the valley toward him. Wild animals he had supposed them, but as he stood firm and raised his weapon shrill whistles sounded in the throng, and he gasped as he realized that those frightful creatures must be intelligent beings, for not only did they signal to each other, but he saw that they were armed with bows and arrows, spears, and slings!

Six-limbed creatures they were, of a purplish-red color, with huge, tricornigerous heads and with staring, green, phosphorescent eyes. Two of the six limbs were always legs, two always arms; the intermediate two, due to a mid-section jointing of the six-foot-long, almost cylindrical body, could be used at will as either legs or arms. Now, out of range, as they supposed, they halted and gathered about one who was apparently their leader; some standing erect and waving four hands while shaking their horns savagely in Stevens' direction, others trotting around on four legs, busily gathering stones of suitable size for their vicious slings.

Too far away to use their own weapons and facing only one small four-limbed creature, they considered their game already in the bag, but they had no comprehension of earthly muscles, nor any understanding of the power and range of a hundred-pound bow driving a steel-headed war arrow. Thus, while they were arguing, Stevens took the offensive, and a cruelly barbed steel war-head tore completely through the body of their leader and mortally wounded the creature next beyond him. Though surprised, they were not to be frightened off, but with wild, shrill screams rushed to the attack. Stevens had no ammunition to waste, and every time that mighty bow twanged a yard-long arrow transfixed at least one of the red horde—and a body through which had torn one of those ghastly, hand-forged arrow-heads was of very little use thereafter. Accurately-sped arrows splintered harmlessly against the re-enforced windows of his helmet and against the steel guards protecting his hands. He was almost deafened by the din as the stone missiles of the slingers rebounded from his reverberating shell of steel, but he fired carefully, steadily, and powerfully until his last arrow had been loosed. Then, the wicked dirk in his left hand and the long and heavy saber weaving a circular path of brilliance in the sun, he stepped forward a couple of paces to meet the attackers. For a few moments nothing could stand before that fiercely driven blade—severed heads, limbs, and fragments of torsos literally filled the air, but sheer weight of numbers bore him down. As he fell, he saw the white shaft of one of Nadia's hunting-arrows flash past his helmet and bury itself to the flock in the body of one of the horde above him. Nadia knew that her arrows could not harm her lover, and through a chink between two boulders she was shooting into the thickest of the mob speeding her light arrows with the full power of her bow.

Though down, the savages soon discovered that Stevens was not out. In such close quarters he could not use his sword, but the fourteen-inch blade of the dirk, needle-pointed as it was and with two razor-sharp, serrated cutting edges, was itself no mean weapon, and time after time he drove it deep, taking life at every thrust. Four more red monsters threw themselves upon the prostrate man, but not sufficiently versed in armor to seek out its joints, their fierce short spear thrusts did no damage. Presently four more corpses lay still and Stevens, with his, to them incredible, earthly strength, was once more upon his feet in spite of their utmost efforts to pinion his mighty limbs, and was again swinging his devastating weapon. Half their force lying upon the field, wiped out by a small, but invincible and apparently invulnerable being, the remainder broke and ran, pursued by Stevens to the point where the red monsters had first halted. He recovered his arrows and returned to the cave, opening his face-plate as he came.

"All x, sweetheart?" he asked, rolling away the boulders. "Didn't get anything through to you, did they?"

"No, they didn't even realize that I was taking part in the battle, I guess. Did they hurt you while they had you down? I was scared to death for a minute."

"No, the old armor held. One of them must have gnawed on my ankle some, between the greave and the heel-plate, but he couldn't quite get through. 'Sa darn small opening there, too—must have bent my foot 'way around to get in at all. Have to tighten that joint up a little, I guess. I'll bet I've got a black spot and blue spot there the size of my hand—maybe it's only the size of yours, though."

"You won't die of that, probably. Heavens, Steve, that cleaver of yours is a frightful thing in action! Suppose it's safe for us to go home?"

"Absolutely—right now is the best chance we'll ever have, and something tells me that we'd better make it snappy. They'll be back, and next time they won't be so easy to take."

"All x, then—hold me, Steve, I can't stand the sight of that—-let alone wade through it. I'm going to faint or something, sure."

"As you were!" he snapped. "You aren't going to pass out now that it's all over! It's a pretty ghastly mess, I know, but shut your eyes and I'll carry you out of sight."

"Aren't we out of sight of that place yet?" she demanded after a time.

"I have been for quite a while," he confessed, "but you're sitting pretty, aren't you? And you aren't very heavy—not here on Ganymede, anyway!"

"Put me down!" she commanded. "After that crack I won't play with you any more at all—I'll pick up my marbles and go home!"

He released her and they hurried hack toward their waterfall, keeping wary eyes sharp-set for danger in any form, animal or vegetable. On the way back across the foothills Stevens shot another hexaped, and upon the plateau above the river Nadia bagged several birds and small animals, but it was not until they were actually in their own little canyon that their rapid pace slackened and their vigilance relaxed.

"After this, ace, we hunt together and we go back to wearing armor while we're hunting. It scared me out of a year's growth when you checked up missing."

"We sure do, Steve," she concurred emphatically. "I'm not going to get more than a meter away from you from now on. What do you suppose those horrible things are?"

"Which?"

"Both."

"Those flowers aren't like anything Tellus ever saw, so we have no basis of comparison. They may be a development of a flycatching plant, or they may be a link between the animal and the vegetable kingdom. However, we don't intend to study 'em, so let's forget 'em. Those animals were undoubtedly intelligent beings; they probably are a race of savages of this satellite."

"Then the really civilized races are probably...."

"Not necessarily—there may well be different types, each struggling toward civilization. They certainly are on Venus, and they once were on Mars."

"Why haven't we seen anything like that before, in all these months? Things have been so calm and peaceful that we thought we had the whole world to ourselves, as far as danger or men were concerned."

"We never saw them before because we never went where they lived—you were a long ways from your usual stamping-grounds, you know. That animal-vegetable flower is probably a high-altitude organism, living in the mountains and never coming as low as we are down here. As for the savages—whatever they are—they probably never come within five kilometers of the falls. Many primitive peoples think that waterfalls are inhabited by demons, and maybe these folks are afflicted the same way."

"We don't know much about our new world yet, do we?"

"We sure don't—and I'm not particularly keen on finding out much more about it until we get organized for trouble, either. Well, here we are—just like getting back home to see the 'Hope,' isn't it?"

"It is home, and will be until we get one of our own on earth," and after Stevens had read his meters, learning with satisfaction that the full current was still flowing into the accumulators, he began to cut up the meat.

"Now that you've got the power-plant running at last, what next?" asked Nadia, piling the cuts in the freezer.

"Brandon's ultra-radio comes next, but it's got more angles to it than a cubist's picture of a set of prisms; so many that I don't know where to begin. There, that job's done—let's sit down and I'll talk at you awhile. Maybe between us we can figure out where to start. I've got everything to build it lined up except for the tube, but that's got me stopped cold. You see, fields of force are all right in most places, but I've got to have one tube, and it's got to have the hardest possible vacuum. That means a mercury-vapor super pump. Mercury is absolutely the only thing that will do the trick and the mercury is one thing that is conspicuous by its absence in these parts. So are tungsten for filaments, tantalum for plates, and platinum for leads; and I haven't found anything that I can use as a getter, either—a metal, you know, to flash inside the tube to clean up the last traces of atmosphere in it."

"I didn't suppose that such a simple thing as a radio tube could hold you up, after the perfectly unbelievable things that you have done already—but I see now how it could. Of course, the tubes in our receiver over there are too small?"

"Yes, they are only receiver and communicator tubes, and I need a high-power transmitting tube—a fifty-kilowatter, at least. I'd give my left leg to the knee joint for one of those big water-cooled, sixty-kilowatt ten-nineteens right now—it would save us a lot of grief."

"Maybe you could break up those tubes and use the plates and so on?"

"I thought of that, but it won't work—there isn't half enough metal in the lot, and the filaments in particular are so tiny that I couldn't possibly work them over into a big one. Then, too, we haven't got many spare tubes, and if I smash the ones we're using, I put our communicators out of business for good, so that we can't yell for help if we have to drift home—and I still don't get any mercury."

"Do you mean to tell me there's no mercury on this whole planet?"

"Not exactly; but I do mean that I haven't been able to find any, and that it's probably darned scarce. And since all the other metals I want worst are also very dense and of high atomic weight, they're probably mighty scarce here, too. Why? Because we're on a satellite, and no matter what hypothesis you accept for the origin of satellites, you come to the same conclusion—that heavy metals are either absent or most awfully scarce and buried deep down toward the center. There are lots of heavy metals in Jupiter somewhere, but we probably couldn't find them. Jupiter's atmosphere is one mass of fog, and we couldn't see, since we haven't got an infra-red transformer. I could build one, in time, but it would take quite a while—and we couldn't work on Jupiter, anyway, because of its gravity and probably because of its atmosphere. And even if we could work there, we don't want to spend the rest of our lives prospecting for mercury." Stevens fell silent, brow wrinkled in thought.

"You mean, dear, that we're..." Nadia broke off, the sentence unfinished.

"Gosh, no! There's lots of things not tried yet, and we can always set out to drift it. I was thinking only of building the tube. And I'm trying to think ... say, Nadia, what do you know about Cantrell's Comet?"

"Not a thing, except that I remember reading in the newspapers that it was peculiar for something or other. But what has Cantrell's Comet got to do with the high cost of living—or with radio tubes? Have you gone cuckoo all of a sudden?"

"You'll be surprised!" Stevens grinned at her puzzled expression. "Cantrell's Comet is one of Jupiter's comet family and is peculiar in being the most massive one known to science. It was hardly known until after they built those thousand-foot reflectors on the Moon, where the seeing is always perfect, but it has been studied a lot since then. Its nucleus is small, but extremely heavy—it seems to have an average density of somewhere around sixteen. There's platinum and everything else that's heavy there, girl! They ought to be there in such quantity that even such a volunteer chemist as I am could find them!"

"Heavens, Steve!" A look of alarm flashed over Nadia's face, then disappeared as rapidly as it had come into being. "But of course, comets aren't really dangerous."

"Sure not. A comet's tail, which so many people are afraid of as being poison gas, is almost a perfect vacuum, even at its thickest, and we'd have to wear space-suits anyway. And speaking of vacuum ... whoopee! We don't need mercury any more than a goldfish needs a gas-mask. When we get Mr. Tube done, we'll take him out into space, leaving his mouth open, and very shortly he'll be as empty as a flapper's skull. Then we'll seal him up, flash him out, come back here, and start spilling our troubles into Brandon's shell-like ear!"

"Wonderful, Steve! You do get an idea occasionally, don't you? But how do we get out there? Where is this Cantrell's Comet?"

"I don't know, exactly—there's one rub. Another is that I haven't even started the transmitter and receptor units. But we've got some field-generators here on board that I can use, so it won't be so bad. And our comet is in this part of the solar system somewhere fairly close. Wish we had an Ephemeris, a couple of I-P solar charts, and a real telescope."

"You can't do much without an Ephemeris, I should think. It's a good thing you kept the chronometers going. You know the I-P time, day, and dates, anyway."

"I'll have to do without some things, that's all," and the man stared absently at the steel wall. "I remember something about its orbit, since it is one thing that all I-P vessels have to steer clear of. Think I can figure it close enough so that we'll be able to find it in our little telescope, or even on our plate, since we'll be out of this atmosphere. And it might not be a bad idea for us to get away, anyway. I'm afraid of those folks on that space-ship, whoever they were, and they must live around here somewhere. Cantrell's Comet swings about fifty million kilometers outside Jupiter's orbit at aphelion—close enough for us to reach, and yet probably too far for them to find us easily. By the time we get back here, they probably will have quit looking for us, if they look at all. Then too, I expect these savages to follow us up. What say, little ace—do we try it or do we stay here?"

"You know best, Steve. As I said before, I'm with you from now on, in whatever you think best to do. I know that you think it best to go out there. Therefore, so do I."

"Well," he said, finally, "I'd better get busy, then—there's a lot to do before we can start. The radio doesn't come next, after all—the transmitter and receptor units come ahead of it. They won't mean wasted labor, in any event, since we'll have to have them in case the radio fails. You'd better lay in a lot of supplies while I'm working on that stuff, but don't go out of sight, and yell like fury if you see anything. We'd both better wear full armor every time we go out-of-doors—unless I'm all out of control we aren't done with those savages yet. Even though they may be afraid of the demons of the falls, I think they'll have at least one more try at us."

While Nadia brought in meat and vegetables and stored them away, Stevens attacked the problem of constructing the pair of tight-beam, auto-dirigible transmitter and receptor units which would connect his great turbo-alternator to the accumulators of their craft, wherever it might be in space. From the force-field generators of the "Forlorn Hope" he selected the two most suitable for his purpose, tuned them to the exact frequency he required, and around them built a complex system of condensers and coils.

Day after day passed. Their larder was full, the receptor was finished, and the beam transmitter was almost ready to attach to the turbo-alternator before the calm was broken.

"Steve!" Nadia shrieked. Glancing idly into the communicator plate, she had been perfunctorily surveying the surrounding territory. "They're coming! Thousands of them! They're all over the bench up there, and just simply pouring down the hills and up the valley!"

"Wish they'd waited a few hours longer—we'd have been gone. However, we're just about ready for them," he commented grimly, as he stared over her shoulder into the communicator plate. "We'll make a lot of those Indians wish that they had stayed at home with their papooses."

"Have you got all those rays and things fixed up?"

"Not as many as I'd like to have. You see, I don't know the composition of the I-P ray, since it is outlawed to everybody except the police. Of course I could have found out from Brandon, but never paid any attention to it. I've got some nice ultra-violet, though, and a short-wave oscillatory that'll cook an elephant to a cinder in about eight seconds. We'll keep them amused, no fooling! Glad we had time to cover our open sides, and it looks as though that meteorite armor we put over the projectors may be mighty useful, too."

On and on the savages came, massed in formations showing some signs of rude discipline. This time there was neither shrieking nor yelling; the weird creatures advanced silently and methodically. Here and there were massed groups of hundreds, dragging behind them engines which Stevens studied with interest.

"Hm ... m ... m. Catapults," he mused. "You were right, girl of my dreams—armor and bows and arrows wouldn't help us much right now. They're going to throw rocks at us that'll have both mass and momentum. With those things they can cave in our side-armor, and might even dent our roof. When one of those projectiles hits, we want to know where it ain't, that's all."

Stevens cast off the heavily-insulated plug connecting the power plant leads to his now almost fully charged accumulators, strapped himself and Nadia into place at the controls, and waited, staring into the plate. Catapult after catapult was dragged to the lip of the little canyon, until six of them bore upon the target. The huge stranded springs of hair, fiber, and sinew were wound up to the limit, and enormous masses of rock were toilsomely rolled upon the platforms. Each "gunner" seized his trip, and as the leader shrieked his signal the six ponderous masses of metalliferous rock heaved into the air as one. But they did not strike their objective, for as the signal was given, Stevens shot power into his projectors. The "Forlorn Hope" leaped out of the canyon and high into the air over the open meadow, just as the six great projectiles crashed into the ground upon the spot which, an instant before, she had occupied.

Rudimentary discipline forgotten, the horde rushed down into the canyon and the valley, in full clamor of their barbaric urgings. Horns and arms tossed fiercely, savage noises rent the air, and arrows splintered harmlessly upon steel plate as the mystified and maddened warriors upon the plain below gave vent to their outraged feelings.

"Look, Nadia! A whole gang of them are smelling around that power plug. Pretty soon somebody's going to touch a hot spot, and when he does, we'll cut loose on the rest of them."

The huge insulating plug, housing the ends of the three great cables leading to the converters of the turbo-alternator, lay innocently upon the ground, its three yawning holes invitingly open to savage arms. The chief, who had been inspecting the power-plant, walked along the triplex lead and joined his followers at its terminus. Pointing with his horns, he jabbered orders and three red monsters, one at each cable, bent to lift the plug, while the leader himself thrust an arm into each of the three contact holes. There was a flash of searing flame and the reeking smoke of burning flesh—those three arms had taken the terrific no-load voltage of the three-phase converter system, and the full power of the alternator had been shorted directly to ground through the comparatively small resistance of his body.

Stevens had poised the "Forlorn Hope" edgewise in mid-air, so that the gleaming, heavily armored parabolic reflectors of his projectors, mounted upon the leading edge of the fortress, covered the scene below. As the charred corpse of the savage chieftain dropped to the ground, it seemed to the six-limbed creatures that the demons of the falls had indeed been annoyed beyond endurance by their intrusion; for, as if in response to the flash of fire from the power plug, that structure so peculiarly and so stolidly hanging in the air came plunging down toward them. From it there reached down twin fans of death and destruction: one flaming and almost invisibly incandescent violet which tore at the eyes and excruciatingly disintegrated brain and nervous tissues; the other dully glowing an equally invisible red, at the touch of which body temperature soared to lethal heights and foliage burst cracklingly into spontaneous flame.

In their massed hundreds, the savages dropped where they stood, life rived away by the torturing ultra-violet, burned away by the blast of pure heat, or consumed by the conflagrations that raged instantly wherever that wide-sweeping fan encountered combustible material. In the face of power supernatural they lost all thought of attack or of conquest, and sought only and madly to escape. Weapons were thrown away, the catapults were abandoned, and, every man for himself, the mob fled in wildest disorder, each striving to put as much distance as possible between himself and that place of dread mystery, the waterfall.

"Well, I guess that'll hold 'em for a while," Stevens dropped their craft back into its original quarters in the canyon. "Whether they ever believed before that this falls was inhabited by devils or not, they think so now. I'll bet that it will be six hundred Jovian years before any of them ever come within a hundred kilometers of it again. I'm glad of it, too, because they'll let our power plant alone now. Well, let's get going—we've got to make things hum for a while!"

"Why all the rush? You just said that we have scared them away for good."

"The savages, yes, but not those others. We've just turned loose enough radiation to affect detectors all over the system, and it's up to us to get this beam projector set up, get away from here, and get our power shut off before they can trace us. Snap it up, ace!"

The transmitter unit was installed at the converters, the cable was torn out, and, having broken the last material link between it and Ganymede, Stevens hurled the "Forlorn Hope" out into space, using the highest acceleration Nadia could endure. Hour after hour the massive wedge of steel bored outward, away from Jupiter; hour after hour Stevens' anxious eyes scanned his instruments; hour after hour hope mounted and relief took the place of anxiety as the screens remained blank throughout every inquiring thrust into the empty ether. But they knew they would have to keep sharp vigilance.

PART II

Spacehounds of IPC

One of the most fascinating mysteries of the heavens is the comet. It goes through space, gets near enough to the earth to be seen, and then goes off and disappears in celestial distance. Often it has a hyperbolic orbit, which would make it impossible to come back. Yet it may return—apparently contradicting the geometry of conic sections. This only goes to prove once more that it is risky to say anything is impossible—even that our hero of this story manages beautifully, with the aid of Cantrell's Comet, to avoid complete annihilation while stranded in interstellar space.

Read "what went before" and then continue the second instalment.

What Went Before:

The Interplanetary Vessel Arcturus sets out for Mars, with Breckenridge as chief pilot, carrying on board, besides its regular crew and some passengers, the famous Dr. Stevens, designer of space ships and computer. He checks computations made by astronomers stationed in floating observatories, and after he has located any trouble and suggests a plan for minimizing the hazards of the trip from the earth to Mars, he reports his findings and suggestions to Mr. Newton, chief of the Interplanetary Corporation.

Stevens then takes Nadia, Mr. Newton's beautiful young daughter, on a specially conducted sight-seeing tour of the Arcturus and thoroughly explains to her all of the works of the vessel. Nadia has herself had a good science education. While they are down at the bottom of the ship—nearing the end of their tour—Stevens feels a barely perceptible movement of the vessel from its course. When he turns on the visiplate, he is horrified to find that a mysterious ray of unparalleled power has neatly sliced the Arcturus in several places.

Nadia and Stevens are completely separated from the rest of the crew and passengers of the ship, so they get into a lifeboat, which is equipped for a limited amount of space travel. Despite the strict and apparently effective vigilance of the enemy destroyer, Stevens and Nadia make their getaway in the lifeboat, which they aptly call "Forlorn Hope," and finally make a safe landing on Ganymede, where Stevens plans to build a power-plant and a radio transmitter, to enable him to communicate with the earth or with the IPV Sirius, which is used by Westfall and Brandon (two of the world's best scientists) as a floating laboratory.

With the very scant apparatus and material available, Stevens sets to work on his power plant. Just as they have it completed and ready to start for Cantrell's Comet, where Stevens believes he can obtain the necessary metal for his giant transmitting tube, they experience a close call with carnivorous plants on the satellite and later with savage inhabitants, which precipitates their trip to the comet.