"Hi, Percival Van Schravendyck Stevens!" Nadia strode purposely into Stevens' room and seized him by the shoulder. "Are you going to sleep all the way to Saturn? You answered me when I pounded on the partition with a hammer, but I don't believe that you woke up at all. Get up, you—breakfast will be all spoiled directly!"

"Huh?" Stevens opened one sluggish eye; then, as the full force of the insult penetrated his consciousness, he came wide awake. "Lay off those names, ace, or you'll find yourself walking back home!" he threatened.

"All x by me!" she retorted. "I might as well go home if you're going to sleep all the time!" and she widened her expressive eyes at him impishly as she danced blithely back into the control room. As she went out she slammed his door with a resounding clang, and Stevens pried himself out of his bunk one joint at a time, dressed, and made himself presentable.

"Gosh!" he yawned mightily as he joined the girl at breakfast. "I don't know when I've had such a gorgeous sleep. How do you get by on so little?"

"I don't. I sleep a lot, but I do it every night, instead of working for four days and nights on end and then trying to make up all those four nights' sleep at once. I'm going to break you of that, too, Steve, if it's the last thing I ever do."

"There might be certain advantages in it, at that," he conceded, "but sometimes you've got to do work when it's got to be done, instead of just between sleeps. However, I'll try to do better. Certainly it is a wonderful relief to get out of that mess, isn't it?"

"I'll say it is! But I wish that those folks were more like people. They're nice, I think, really, but they're so ... so ... well, so ghastly that it simply gives me the blue shivers just to look at one of them!"

"They're pretty gruesome, no fooling," he agreed, "but you get used to things like that. I just about threw a fit the first time I ever saw a Martian, and the Venerians are even worse in some ways—they're so clammy and dead-looking—but now I've got real friends on both planets. One thing, though, gives me the pip. I read a story a while ago—the latest best-seller thing of Thornton's named 'Interstellar Slush' or some such tr...."

"Cleophora—An Interstellar Romance," she corrected him. "I thought it was wonderful!"

"I didn't. It's fundamentally unsound. Look at our nearest neighbors, who probably came from the same original stock we did. A Tellurian can admire, respect, or like a Venerian, yes. But for loving one of them—wow! Beauty is purely relative, you know. For instance, I think that you are the most perfectly beautiful thing I ever saw; but no Venerian would think so. Far from it. Any Martian that hadn't seen many of us would have to go rest his eyes after taking one good look at you. Considering what love means, it doesn't stand to reason that any Tellurian woman could possibly fall in love with any man not of her own breed. Any writer is wrong who indulges in interplanetary love affairs and mad passions. They simply don't exist. They can't exist—they're against all human instincts."

"Interplanetary—in this solar system—yes. But the Dacrovos were just like us, only nicer."

"That's what gives me the pip. If our own cousins of the same solar system are so repulsive to us, how would we be affected by entirely alien forms of intelligence?"

"May be you're right, of course—but you may be wrong, too," she insisted. "The Universe is big enough, so that people like the Dacrovos may possibly exist in it somewhere. May be the Big Three will discover a means of interstellar travel—then I'll get to see them myself, perhaps."

"Yes, and if we do, and if you ever see any such people, I'll bet that the sight of them will make your hair curl right up into a ball, too! But about Barkovis—remember how diplomatic the thoughts were that he sent us? He described our structure as being 'compact,' but I got the undertone of his real thoughts, as well. Didn't you?"

"Yes, now that you mention it, I did. He really thought that we were white-hot, under-sized, overpowered, warty, hairy, hideously opaque and generally repulsive little monstrosities—thoroughly unpleasant and distasteful. But he was friendly, just the same. Heavens, Steve! Do you suppose that he read our real thoughts, too?"

"Sure he did; but he is intelligent enough to make allowances, the same as we are doing. He isn't any more insulted than we are. He knows that such feelings are ingrained and cannot be changed."

Breakfast over, they experienced a new sensation. For the first time in months they had nothing to do! Used as they were to being surrounded by pressing tasks, they enjoyed their holiday immensely for a few hours. Sitting idly at the communicator plate, they scanned the sparkling heavens with keen interest. Beneath them Jupiter was a brilliant crescent not far from the sun in appearance, which latter had already grown perceptibly smaller and less bright. Above them, and to their right, Saturn shone refulgently, his spectacular rings plainly visible. All about them were the glories of the firmament, which never fail to awe the most seasoned observer. But idleness soon became irksome to those two active spirits, and Stevens prowled restlessly about their narrow quarters.

"I'm going to go to work before I go dippy," he soon declared. "They've got lots of power, and we can rig up a transmitter unit to send it over here to our receptor. Then I can start welding the old Hope together without waiting until we get to Titan to start it. Think I'll signal Barkovis to come over, and see what he thinks about it."

The Titanian commander approved the idea, and the transmitting field was quickly installed. Nadia insisted that she, too, needed to work, and that she was altogether too good a mechanic to waste; therefore the two again labored mightily together, day after day. But the girl limited rigidly their hours of work to those of the working day; and evening after evening Barkovis visited with them for hours. Dressed in his heavy space-suit and supported by a tractor beam well out of range of what seemed to him terrific heat radiated by the bodies of the Terrestrials, he floated along unconcernedly; while over the multiplex cable of the thought-exchanger he conversed with the man and woman seated just inside the open outer door of their air-lock. The Titanian's appetite for information was insatiable—particularly did he relish everything pertaining to the earth and to the other inner planets, forever barred to him and to his kind. In return Stevens and Nadia came gradually to know the story of the humanity of Titan.

"I am glad beyond measure to have known you," Barkovis mused, one night. "Your existence proves that there is truth in mythology, as some of us have always believed. Your visit to Titan will create a furor in scientific circles, for you are impossibility incarnate—personifications of the preposterous. In you, wildest fancy had become commonplace. According to many of our scientists, it is utterly impossible for you to exist. Yet you say, and it must be, that there are millions upon millions of similar beings. Think of it! Venerians, Tellurians, Martians, the satellite dwellers of the lost space-ship, and us—so similar mentally, yet physically how different!"

"But where does the mythology come in?" thought Nadia.

"We have unthinkably ancient legends which say that once Titan was extremely hot, and that our remote ancestors were beings of fire, in whose veins ran molten water instead of blood. Since our recorded history goes back some tens of thousands of Saturnian years, and since in that long period there has been no measurable change in us, few of us have believed in the legends at all. They have been thought the surviving figments of a barbarous, prehistoric worship of the sun. However, such a condition is not in conflict with the known facts of cosmogony, and since there actually exists such a humanity as yours—a humanity whose bodily tissues actually are composed largely of molten water—those ancient legends must indeed have been based upon truth.

"What an evolution! Century after century of slowly decreasing temperature—one continuous struggle to adapt the physique to a constantly changing environment. First they must have tried to maintain their high temperature by covering and heating their cities.—Then, as vegetation died, they must have bred into their plants the ability to use as sap purely chemical liquids, such as our present natural fluids—which also may have been partly synthetic then—instead of the molten water to which they had been accustomed. They must have modified similarly the outer atmosphere; must have made it more reactive, to compensate for the lowered temperature at which metabolism must take place. As Titan grew colder and colder they probably dug their cities deeper and ever deeper; until humanity came finally to realize that it must itself change completely or perish utterly.

"Then we may picture them as aiding evolution in changing their body chemistry. For thousands, and thousands of years there must have gone on the gradual adaptation of blood stream and tissue to more and more volatile liquids, and to lower and still lower temperatures. This must have continued until Titan arrived at the condition which has now obtained for ages—a condition of thermal equilibrium with space upon one hand and upon the other the sun, which changes appreciably only in millions upon millions of years. In equilibrium at last—with our bodily and atmospheric temperatures finally constant at their present values, which seem as low to you as yours appear high to us. Truly, an evolution astounding to contemplate!"

"But how about power?" asked Stevens. "You seem to have all you want, and yet it doesn't stand to reason that there could be very much generated upon a satellite so old and so cold."

"You are right. For ages there has been but little power produced upon Titan. Many cycles ago, however, our scientists had developed rocket-driven space-ships, with which they explored our neighboring satellites, and even Saturn itself. It is from power plants upon Saturn that we draw energy. Their construction was difficult in the extreme, since the pioneers had to work in braces because of the enormous force of gravity. Then, too, they had to be protected from the overwhelming pressure and poisonous qualities of the air, and insulated from a temperature far above the melting point of water. In such awful heat, of course, our customary building material, water, could not be employed...."

"But all our instruments have indicated that Saturn is cold!" Stevens interrupted.

"Its surface temperature, as read from afar, would be low," conceded Barkovis, "but the actual surface of the planet is extremely hot, and is highly volcanic. Practically none of its heat is radiated because of the great density and depth of its atmosphere, which extends for many hundreds of your kilometers. It required many thousands of lives and many years of time to build and install those automatic power plants, but once they were in operation, we were assured of power for many tens of thousands of years to come."

"Our system of power transmission is more or less like yours, but we haven't anything like your range. Suppose you'd be willing to teach me the computation of your fields?"

"Yes, we shall be glad to give you the formulae. Being an older race, it is perhaps natural that we should have developed certain refinements as yet unknown to you. But I am, I perceived, detaining you from your time of rest—goodbye," and Barkovis was wafted back toward his mirrored globe.

"What do you make of this chemical solution blood of theirs, Steve?" asked Nadia, watching the placidly floating form of the Titanian captain.

"Not much. I may have mentioned before that there are one or two, or perhaps even three men who are better chemists than I am. I gathered that it is something like a polyhydric alcohol and something like a substituted hydrocarbon, and yet different from either in that it contains flourin in loose combination. I think it is something that our Tellurian chemists haven't got yet; but they've got so many organic compounds now that they may have synthesized it, at that. You see, Titan's atmosphere isn't nearly as dense as ours, but what there is of it is pure dynamite. Ours is a little oxygen, mixed with a lot of inert ingredients. Theirs is oxygen, heavily laced with flourin. It's reactive, no fooling! However, something pretty violent must be necessary to carry on body reactions at such a temperature as theirs."

"Probably; but I know even less about that kind of thing than you do. Funny, isn't it, the way he thinks 'water' when he means ice, and always thinks of our real water as being molten?"

"Reasonable enough when you think about it. Temperature differences are logarithmic, you know, not arithmetic—the effective difference between his body temperature and ours is perhaps even greater than that between ours and that of melted iron. We never think of iron as being a liquid, you know."

"That's right, too. Well, good night, Steve dear."

"'Bye, little queen of space—see you at breakfast," and the Forlorn Hope became dark and silent.

Day after day the brilliant sphere flew toward distant Saturn, with the wreckage of the Forlorn Hope in tow. Piece by piece that wreckage was brought together and held in place by the Titanian tractors; and slowly but steadily, under Stevens' terrific welding projector, the stubborn steel flowed together, once more to become a seamless, spaceworthy structure. And Nadia, the electrician, followed close behind the welder. Wielding torch, pliers and spanner with practised hand, she repaired or cut out of circuit the damaged accumulator cells and reunited the ends of each severed power lead. Understanding Nadia's work thoroughly, the Titanians were not particularly interested in it; but whenever Stevens made his way along an outside seam, he had a large and thrillingly horrified gallery. Everyone who could possibly secure permission to leave the sphere did so, each upon his own pencil of force, and went over to watch the welder. They did not come close to him—to venture within fifty feet of that slow moving spot of scintillating brilliance, even in a space-suit, meant death—but, poised around him in space, they watched with shuddering, incredulous amazement, the monstrous human being in whose veins ran molten water instead of blood; whose body was already so fiercely hot that it could exist unharmed while working practically without protection, upon liquefied metal!

Finally the welding was done. The insulating space was evacuated and held its vacuum—outer and inner shells were bottle-tight. The two mechanics heaved deep sighs of relief as they discarded their cumbersome armor and began to repair what few of their machine tools had been damaged by the slashing plane of force which had so neatly sliced the Forlorn Hope into sections.

"Say, big fellow, you're the guy that slings the ink, ain't you?" Nadia extinguished her torch and swaggered up to Stevens, hands on hips, her walk an exaggerated roll. "Write me out a long walk. This job's all played out, so I think I'll get me a good job on Titan. I said give me my time, you big stiff!"

"You didn't say nothing!" growled Stevens in his deepest bass, playing up to her lead as he always did. "Bounce back, cub, you've struck a rubber fence! You signed on for duration and you'll stick—see?"

Arm in arm they went over to the nearest communicator plate. Flipping the switch, Stevens turned the dial and Titan shone upon the screen; so close, that it no longer resembled a moon, but was a world toward which they were falling with an immense velocity.

"Not close enough to make out much detail yet—let's take another look at Saturn," and Stevens projected the visiray beam out toward the mighty planet. It was now an enormous full moon, almost five degrees in apparent diameter,1 its visible surface an expanse of what they knew to be billowing cloud, shining brilliantly white in the pale sunlight, broken only by a dark equatorial band.

"Those rings were such a gorgeous spectacle a little while ago!" Nadia mourned. "It's a shame that Titan has to be right in their plane, isn't it? Think of living this close to one of the most wonderful sights in the Solar System, and never being able to see it. Think they know what they're missing, Steve?"

"We'll have to ask Barkovis," Stevens replied. He swung the communicator beam back toward Titan, and Nadia shuddered.

"Oh, it's hideous!" she exclaimed. "I thought that it would improve as we got closer, but the plainer we can see it, the worse it gets. Just to think of human beings, even such cold-blooded ones as those over there, living upon such a horrible moon and liking it, gives me the blue shivers!"

"It's pretty bleak, no fooling," he admitted, and peered through the eyepiece of the visiray telescope, studying minutely the forbidding surface of the satellite they were so rapidly approaching.

Larger and larger it loomed, a cratered, jagged globe of desolation indescribable; of sheer, bitter cold incarnate and palpable; of stark, sharp contrasts. Gigantic craters, in whose yawning depths no spark of warmth had been generated for countless cycles of time, were surrounded by vast plains eroded to the dead level of a windless sea. Every lofty object cast a sharply outlined shade of impenetrable blackness, beside which the weak light of the sun became a dazzling glare. The ground was either a brilliant white or an intense black, unrelieved by half-tones.

"I can't hand it much, either, Nadia, but it's all in the way you've been brought up, you know. This is home to them, and just to look at Tellus would give them the pip. Ha! Here's something you'll like, even if it does look so cold that it makes me feel like hugging a couple of heater coils. It's Barkovis' city the one we're heading for, I think. It's close enough now so that we can get it on the plate," and he set the communicator beam upon the metropolis of Titan.

"Why, I don't see a thing, Steve—where and what is it?" They were dropping vertically downward toward the center of a vast plain of white, featureless and desolate; and Nadia stared in disappointment.

"You'll see directly—it's too good to spoil by telling you what to look for or wh...."

"Oh, there it is!" she cried. "It is beautiful, Steve, but how frightfully, utterly cold!"

A flash of prismatic color had caught the girl's eye, and, one transparent structure thus revealed to her sight, there had burst into view a city of crystal. Low buildings of hexagonal shape, arranged in irregularly variant hexagonal patterns, extended mile upon mile. From the roofs of the structures lacy spires soared heavenward; inter-connected by long, slim cantilever bridges whose prodigious spans seemed out of all proportion to the gossamer delicacy of their construction. Buildings, spires, and bridges formed fantastic geometrical designs, at which Nadia exclaimed in delight.

"I've just thought of what that reminds me of—it's snowflakes!"

"Sure—I knew it was something familiar. Snowflakes—no two are ever exactly alike, and yet every one is symmetrical and hexagonal. We're going to land on the public square—see the crowds? Let's put on our suits and go out."

The Forlorn Hope lay in a hexagonal park, and near it the Titanian globe had also come to rest. All about the little plot towered the glittering buildings of crystal, and in its center played a fountain; a series of clear and sparkling cascades of liquid jewels. Under foot there spread a thick, soft carpet of whitely brilliant vegetation. Throngs of the grotesque citizens of Titania were massed to greet the space-ships; throngs clustering close about the globular vessel, but maintaining a respectful distance from the fiercely radiant Terrestrial wedge. All were shouting greetings and congratulations—shouts which Stevens found as intelligible as his own native tongue.

"Why, I can understand every word they say, Steve!" Nadia exclaimed, in surprise. "How come, do you suppose?"

"I can, too. Don't know—must be from using that thought telephone of theirs so much, I guess. Here comes Barkovis—I'll ask him."

The Titanian commander had been in earnest conversation with a group of fellow-creatures and was now walking toward the Terrestrials, carrying the multiple headsets. Placing them upon the white sward, he backed away, motioning the two visitors to pick them up.

"It may not be necessary, Barkovis," Stevens said, slowly and clearly. "We do not know why, but we can understand what your people are saying, and it may be that you can now understand us."

"Oh, yes, I can understand your English perfectly. A surprising development, but perhaps, after all, one that should have been expected, from the very nature of the device we have been using. I wanted to tell you that I have just received grave news, which makes it impossible for us to help you immediately, as I promised. While we were gone, one of our two power-plants upon Saturn failed. In consequence, Titan's power has been cut to a minimum, since maintaining our beam at that great distance required a large fraction of the output of the other plant. Because of this lack, the Sedlor walls were weakened to such a point that in spite of the Guardian's assurances, I think trouble is inevitable. At all events, it is of the utmost importance that we begin repairing the damaged unit, for that is to be a task indeed."

"Yes, it will take time," agreed Stevens, remembering what the Titanian captain had told him concerning the construction of those plants—generators which had been in continuous and automatic operation for thousands of Saturnian years.

"It will take more than time—it will take lives," replied Barkovis, gravely. "Scores, perhaps hundreds, of us will never again breathe the clear, pure air of Titan. In spite of all precaution and all possible bracing and insulation, man after man after man will be crushed by his own weight, volatilized by the awful heat, poisoned by the foul atmosphere, or will burst into unthinkable flames at the touch of some flying spark from the inconceivably hot metals with which we shall have to work. A horrible fate, but we shall not lack for volunteers."

"Sure not; and of course you yourself would go. And I never thought of the effect a spark would have on you—your tissues would probably be wildly inflammable. But say, I just had a thought. Just how hot is the air at those plants and just what is the actual pressure?"

"According to the records, the temperature is some forty of your centigrade degrees above the melting-point of water, and the pressure is not far short of two of your meters of mercury. I find it almost impossible to think of mercury as a liquid, however."

"You find it impossible, since you use it as a metal, for wires in coils and so on. But plus forty, while pretty warm, isn't impossible, by any means; and we could stand double our air pressure for quite a while. Both my partner and I are pretty fair mechanics and we've got quite a line of machine tools, such as you could not possibly have here. We'll give it a whirl, since we owe you something already. Lead us to it, ace—but wait a minute! We can't see through the fog, so couldn't find the plants, and probably your wiring diagrams would explode if I touched them."

"I never thought of your helping us," mused Barkovis. "The idea of any living being existing in that inferno has always been unthinkable, but the difficulties you mention are slight. We have already built in our vessel communicators similar to yours, and radio sets. With these we can guide you and explain the plants to you as you work, and our tractor beams will be of assistance to you in moving heavy objects, even at such distances from the surface as we Titanians shall have to maintain. If you will set out a flask of your atmosphere, we will analyze it, for the thought has come to me that perhaps, being planet-dwellers yourselves, the air of Saturn might not be as poisonous to you as it is to us."

"That's a thought, too," and, the news broadcast, it was not long until the two ships leaped into the air, to the accompaniment of the cheers and plaudits of a watching multitude.

In a wide curve they sped toward Saturn. Passing so close to the enormous rings that the individual meteoric fragments could almost be seen with the unaided eye, they flashed on and on, slowing down long before they approached the upper surface of the envelope of cloud. The spherical space-ship stopped and Stevens, staring into his useless screen, drove the Forlorn Hope downward mile after mile, solely under Barkovis' direction, changing course and power from time to time as the Titanian's voice came from the speaker at his elbow. Slower and slower became the descent, until finally, almost upon the broad, flat roof of the power-plant, Stevens saw it in his plate. Breathing deeply in relief, he dropped quickly down upon a flat pavement, neutralized his controls, and turned to Nadia.

"Well, old golf-shootist, we're here at last—now we'll go out and see what's gone screwy with the works. Remember that gravity is about double normal here, and conduct yourself accordingly."

"But it's supposed to be only about nine-tenths," she objected.

"That's at the outer surface of the atmosphere," he replied. "And it's some atmosphere—not like the thin layer we've got on Tellus."

They went into the airlock, and Stevens admitted air until their suits began to collapse. Then, face-plate valves cracked, he sniffed cautiously, finally opening his helmet wide. Nadia followed suit and the man laughed as she wrinkled her nose in disgust as two faint, but unmistakable odors smote her olfactory nerves.

"I never cared particularly for hydrogen sulphide and sulphur dioxide, either," he assured her, "but they aren't strong enough to hurt us in the short time we'll be here. Those Titanian chemists know their stuff, though."

He opened the outer valves slowly, then opened the door and they stepped down upon the smooth, solid floor, which Stevens examined carefully.

"I thought so, from his story. Solid platinum! This whole plant is built of platinum, iridium, and noble alloys—the only substances known that will literally last forever. Believe me, ace of my bosom, I don't wonder that it cost them lives to build it—with their conditions, I don't see how they ever got it built at all."

Before them rose an immense, flat-topped cone of metal, upon the top of which was situated the power plant. Twelve massive pillars supported a flat roof, but permitted the air to circulate freely throughout the one great room which housed the machinery. They climbed a flight of stairs, passed between two pillars, and stared about them. There was no noise, no motion—there was nothing that could move. Twelve enormous masses of metallic checkerwork, covered with wide cooling fins, almost filled the vast hall. From the center of each mass great leads extended out into a clear space in the middle of the room, there uniting in mid-air to form one enormous bus-bar. This bar, thicker than a man's body, had originally curved upward to the base of an immense parabolic structure of latticed bars. Now, however, it was broken in midspan and the two ends bent toward the floor. Above their heads, a jagged hole gaped in the heavy metal of the roof, and a similar hole had been torn in the floor. The bar had been broken and these holes had been made by some heavy body, probably a meteorite, falling with terrific velocity.

"This is it, all right," Stevens spoke to distant Barkovis. "Sure there's nothing on this beam? If it should be hot and I should short circuit or bridge it with my body, it would be just too bad."

"We have made sure that nothing is connected to it," the Titanian assured him. "Do you think you can do anything?"

"Absolutely. We've got jacks that'll bend heavier stuff than that, and after we get it straightened the welding will be easy, but I'll have to have some metal. Shall I cut a piece off the pavement outside?"

"That will not be necessary. You will find ample stores of spare metal piled at the base of each pillar."

"All x. Now we'll get the jack, Nadia," and they went back to their vessel, finding that upon Saturn, their combined strength was barely sufficient to drag the heavy tool along the floor.

"Stand aside, please. We will place it for you," a calm voice sounded in their ears, and a pale blue tractor beam picked the massive jack lightly from the floor, and as lightly lifted it to its place beneath the broken bus-bar and held it there while Stevens piled blocks and plates of platinum beneath its base.

"Well, here's where I peel down as far as the law allows. This is going to be real work, girl—no fooling. It'd help a lot if this outfit were sending out a few thousand kilo-franks instead of standing idle."

"How would that help?"

"It's a heat-engine, you know—works by absorbing heat. The cold air sinks—I imagine it pretty nearly blows a gale down the side of this cone when it's working—and hot air rushes in to take its place. I could use a little cool breeze right now," and Stevens, stripped to the waist, bent to the lever of the powerful hydraulic jack.

Beads of sweat gathered upon his broad back, uniting to form tiny rivulets, and the girl became highly concerned about him.

"Let me help you, Steve—I'm pretty husky, too, you know."

"Sure you are, ace, but this is a job for a truck-horse, not a tenderly-nurtured maiden of the upper classes. You can help, though, by breaking out that welding outfit and getting it ready while I'm doing this bending to prepare for the welding."

Under the urge of that mighty jack the ends of the broken bus-bar rose into place, while far off in space the Titanians clustered about their visiray screens, watching, in almost unbelieving amazement, the supernatural being who labored in that reeking inferno of heat and poisonous vapor—who labored almost naked and entirely unprotected, refreshing himself from time to time with drafts of molten water!

"All x, Barkovis—that's high, I guess." Stevens flipped perspiration from his hot forehead with a wet finger and straightened his weary back. "Now you can put this jack away where we had it. Then you might trundle me over enough of that spare metal to fill up this hole, and I'll put on my suit and goggles and practice welding on this floor and the roof, to get the feel of the metal before I tackle the bar."

The hole in the floor was filled with scrap and soon sparks were flying wildly as the searing beam of Stevens' welding projector bit viciously into the stubborn alloy of noble metals; fashioning a smooth, solid floor where the yawning aperture had been. Then, lifted with his tools and plates to the roof, the man repaired that hole also.

"Now I know enough about it to do a good job on the bar," he decided, and brick after brick of alloy was fused into the crack, until only a smoothly rounded bulge betrayed that a break had ever existed in that mighty rod of metal.

"Give 'em the signal to draw power, and see if that's all that was the matter," Stevens instructed, as he relaxed in the grateful coolness of their control room. "Whew, that was a warm job, Nadia—and this air of ours does smell good!"

"It was a horrible job, and I'm glad it's done," she declared. "But say, Steve, that thing looks as little like a power-plant as anything I can imagine. How does it work? You said that it worked on heat, but I don't quite see how. But don't draw diagrams and please don't integrate!"

"No ordinary plant such as we use could run for centuries without attention," he replied. "This is a highly advanced heat-engine—something like a thermo-couple, you know. This whole thing is simply the hot end, connected to the cold end on Titan by a beam instead of wires. When it's working, this metal must cool off something fierce. That's what the checkerwork and fins are for—so that it can absorb the maximum amount of heat from the current of hot, moist air I spoke about. It's a sweet system—we'll have to rig up one between Tellus and the moon. Or even between the Equator and the Arctic Circle there'd be enough thermal differential to give us a million kilofranks. We haven't got the all x signal yet, but it's working—look at it sweat as it cools down!"

"I'll say it's sweating—the water is simply streaming off it!" In their plate they saw that moisture was already beginning to condense upon the heat-absorber: moisture running down the fins in streams and creeping over the dull metal floor in sluggish sheets; moisture which, turning into ice in the colder interior of the checkerwork, again became fluid at the inrush of hot, wet Saturnian air.

"There's the signal—all x, Barkovis? By the way it's condensing water, it seems to be functioning again."

"Perfect!" came the Titanian's enthusiastic reply, "You two planet-dwellers have done more in three short hours than the entire force of Titan could have accomplished in months. You have earned, and shall receive, the highest...."

"As you were, ace!" Stevens interrupted, embarrassed. "This job was just like shooting fish down a well, for us. Since you saved our lives, we owe you a lot yet. We're coming out—straight up!"

The Forlorn Hope shot upward, through mile after mile of steaming fog, until at last she broke through into the light, clear outer atmosphere. Stevens located the Titanian space-ship, and the two vessels once more hurtling together through the ether toward Titan, he turned to his companion.

"Take the controls, will you, Nadia? Think I'll finish up the tube. I brought along a piece of platinum from the power plant, and something that I think is tantalum from Barkovis' description of it. With those and the fractions we melted out, I think I can make everything we'll need."

Now that he had comparatively pure metal with which to work, drawing the leads and filaments was relatively a simple task. Working over the hot-bench with torch and welding projector, he made short work of running the leads through the almost plastic glass of the great tube and of sealing them in place. The plates and grids presented more serious problems; but they were solved and, long before Titan was reached, the tube was out in space, supported by a Titanian tractor beam between the two vessels. Stevens came into the shop, holding a modified McLeod gauge which he had just taken from the interior of the tube. When it had come to equilibrium, he read it carefully and yelled.

"Eureka, little fellow! She's down to where I can't read it, even on this big gauge—so hard that it won't need flashing—harder than any vacuum I ever got on Tellus, even with a Rodebush-Michalek super-pump!"

"But how about occluded and absorbed gas in the filaments and so on when they heat up?" demanded Nadia, practically.

"All gone, ace. I out-gassed 'em plenty out there—seven times, almost to fusion. There isn't enough gas left in the whole thing to make a deep breath for a microbe."

He took up his welding projector and a beam carried him back to the tube. There, in the practically absolute vacuum of space, the last openings in the glass were sealed, and man and great transmitting tube were wafted lightly back into the Terrestrial cruiser.

Hour after hour mirrored Titanian sphere and crude-fashioned terrestrial wedge bored serenely on through space, and it was not until Titan loomed large beneath them that the calm was broken by an insistent call from Titan to the sphere.

"Barkodar, attention! Barkodar, attention!" screamed from the speakers, and they heard Barkovis acknowledge the call.

"The Sedlor have broken through and are marching upon Titania. The order has gone out for immediate mobilization of every unit."

"There's that word 'Sedlor' again—what are they, anyway, Steve?" demanded Nadia.

"I don't know. I was going to ask him when he sprung it on us first, but he was pretty busy then and I haven't thought of it since. Something pretty serious, though—they've jumped their acceleration almost to Tellurian gravity, and none of them can live through much of that."

"Tellurians?" came the voice of Barkovis from the speaker. "We have just...."

"All x—we were on your wave and heard it," interrupted Stevens. "We're with you. What are those Sedlor, anyway? Maybe we can help you dope out something."

"Perhaps—but whatever you do, do not use your heat-projector. That would start a conflagration raging over the whole country, and we shall have enough to do without fighting fire. But it may be that you have other weapons, of which we are ignorant, and I can use a little time in explanation before we arrive. The Sedlor are a form of life, something like your..." he paused, searching through his scanty store of Earthly knowledge, then went on, doubtfully, "perhaps some thing like your insects. They developed a sort of intelligence, and because of their fecundity, adapted themselves to their environment as readily as did man; and for ages they threatened man's supremacy upon Titan. They devoured vegetation, crops, animals, and mankind. After a world-wide campaign, however, they were finally exterminated, save in the neighborhood of one great volcanic crater, which they so honeycombed that it is almost impregnable. All around that district we have erected barriers of force, maintained by a corps of men known as 'Guardians of the Sedlor.' These barriers extend so far into the ground and so high into the air that the Sedlor can neither burrow beneath them nor fly over them. They were being advanced as rapidly as possible, and in a few more years the insects would have been destroyed completely—but now they are again at large. They have probably developed an armor or a natural resistance greater than the Guardians thought possible, so that when the walls were weakened, they came through in their millions, underground and undetected. They are now attacking our nearest city—the one you know, and which you have called Titania."

"What do you use—those high-explosive bombs?"

"The bombs were developed principally for use against them, but proved worse than useless, for we found that when a Sedlor was blown to pieces, each piece forthwith developed into a new, complete creature. Our most efficient weapons are our heat rays—not yours remember—and poison gas. I must prepare our arms."

"Would our heat-ray actually set them afire, Steve?" Nadia asked, as the plate went blank.

"I'll say it would. I'll show you what heat means to them—showing you will be plainer than any amount of explanation," and he shot the visiray beam down toward the city of Titania. Into a low-lying building it went, and Nadia saw a Titanian foundry in full operation. Men clad in asbestos armor were charging, tending, and tapping great electric furnaces and crucibles; shrinking back and turning their armored heads away as the hissing, smoking melt crackled into the molds from their long-handled ladles. Nadia studied the foundry for a moment, interested, but unimpressed.

"Of course it's hot there—foundries always are hot," she argued.

"Yes, but you haven't got the idea yet." Stevens turned again to the controls, following the sphere toward what was evidently a line of battle. "That stuff that they are melting and casting and that is so hot, is not metal, but ice! Remember that the vital fluid of all life here, animal and vegetable, corresponding to our water, is probably more inflammable than gasoline. If they can't work on ice-water without wearing suits of five-ply asbestos, what would a real heat-ray do to them? It'd be about like our taking a dive into the sun!"

"Ice!" she exclaimed. "Oh of course—but you couldn't really believe a thing like that without seeing it, could you? Oh, Steve—how utterly horrible!"

The "Barkodar" had dropped down into a line of sister ships, and had gone into action in midair against a veritable swarm of foes. Winged centipedes they were—centipedes fully six feet long, hurling themselves along the ground and through the air in furious hordes. From the flying globes emanated pale beams of force, at the touch of which the Sedlor disappeared in puffs of vapor. Upon the ground huge tractors and trucks, manned by masked soldiery, mounted mighty reflectors projecting the same lethal beam. From globes and tanks there sounded a drumming roar and small capsules broke in thousands among the foe; emitting a red cloud of gas in which the centipedes shriveled and died. But for each one that was destroyed two came up from holes in the ground and the battle-line fell back toward Titania, back toward a long line of derrick-like structures which were sinking force-rods into the ground in furious haste.

Stevens flashed on his ultra-violet projector and swung it into the thickest ranks of the enemy. In the beam many of the monsters died, but the Terrestrial ray was impotent compared with the weapons of the Titanians, and Stevens, snapping off the beam with a bitter imprecation, shot the visiray out toward the bare, black cone of the extinct volcano and studied it with care.

"Barkovis, I've got a thought!" he snapped into the microphone. "Their stronghold is in that mountain, and there's millions of them in there yet, coming out along their tunnels. They've got all the vegetation eaten away for miles, so there's nothing much left there to spread a fire if I go to work on that hill, and, I'll probably melt enough water to put out most of the fires I start. Detail me a couple of ships to drop your fire-foam bombs on any little blazes that may spread, and I'll give them so much to worry about at home, that they'll forget all about Titania."

The Forlorn Hope darted toward the crater, followed closely by two of the dazzling globes. They circled the mountain until Stevens found a favorable point of attack—a stupendous vertical cliff of mingled rock and crystal, upon the base of which he trained his terrific infra-red projector.

"I'm going to draw a lot of power," he warned the Titanians then. "I'm giving this gun everything she'll take."

He drove the massive switches in, and as that dull red beam struck the cliff's base there was made evident the awful effect of a concentrated beam of real and pure heat upon such an utterly frigid world. Vast columns of fire roared aloft, helping Stevens, melting and destroying the very ground as the bodies of the Sedlor in that gigantic ant-heap burst into flames. Clouds of superheated steam roared upward, condensing into a hot rain which descended in destructive torrents upon the fastnesses of the centipedes. As the raging beam ate deeper and deeper into the base of the cliff, the mountain itself began to disintegrate; block after gigantic block breaking off and crashing down into the flaming, boiling, seething cauldron which was the apex of that ravening beam.

Hour after hour Stevens drove his intolerable weapon into the great mountain, teeming with Sedlorean life; and hour after hour a group of Titanian spheres stood by, deluging the surrounding plain with a flood of heavy fumes, through which the holocaust could not spread for lack of oxygen. Not until the mountain was gone—not until in its stead there lay a furiously boiling lake, its flaming surface hundreds of feet below the level of the plain—did Stevens open his power circuits and point the deformed prow of the Forlorn Hope toward Titania.

1 (return)
The moon subtends an angle of about one-half of a degree.