Alexander Key
Rivets and Sprockets

    To All The Boys And Girls I Know, of all ages and especially the right age, beginning with Zan, and including Jerry, Scotty, Patsy, Nick, Christina, Gloria, Paul, Marty, Herman, lots of Johns and Bills and Franks, a good Joe, a nice Sarah, and all the way down and up the alphabet to Debbie, Cindy, Betsy, and little Alice.

    Chapter 1: They Are in Disgrace
    Chapter 2: They Put Their Heads Together
    Chapter 3: They Begin a Journey
    Chapter 4: They Abble the Professor
    Chapter 5: They Are Lost in Space
    Chapter 6: They Search for the Something
    Chapter 7: They Enter a Door
    Chapter 8: They Unravel Riddles
    Chapter 9: They Are Abbled and Plated
    Chapter 10: They Meet the Something

Chapter 1: They Are in Disgrace
    Sprockets, the Baileys’ little robot, and his brother, Rivets, the Baileys’ least robot, were lying helpless on the laboratory floor, quivering from shock. Their circuits were overheating, and in ten seconds – unless someone speedily turned off their switches – their brains would sizzle and pop, and they would be robot dummies for the rest of their lives. They had done a dreadful thing, much too awful for any proper robot to think about.
    Here is what they did, and why it was so very bad:
    Three days earlier – three days, five hours, fifty-two minutes, and seven seconds earlier, according to the clock in Sprockets’ special brain – Dr. Bailey’s son, young Jim Bailey, had made a great discovery. Jim was in the laboratory, fiddling with a radio he had built from odd parts, when suddenly he exclaimed: “Daddy, I’m getting a message from Mars! Daddy, listen!”
    “I will not,” said the doctor. “And you are not getting a message from Mars. Don’t interrupt me. Can’t you see I’m thinking deeply?”
    The doctor was a tall, thin man with thick glasses on the end of his nose, a thick mop of white hair that flopped in all directions when he thought deeply, and a perpetual frown that came from solving too many puzzles. His greatest puzzle, how to finish his Super-Magna Space Probe, was still unsolved.
    “But, Daddy,” Jim insisted, “I am getting a message, and I’m sure it’s from Mars! I aimed a signal there, and I’m getting a reply. Ask Sprockets. He’s never wrong.”
    “Humph!” grunted the doctor. He looked suspiciously at Sprockets, who had been made by accident at the robot factory and given a brain that no little robot put together from scraps should have had. It was forever upsetting him with its answers.
    “What’s this nonsense about?” the doctor demanded.
    Sprockets and his smaller brother, Rivets – they were about the size of smallish boys with biggish heads – were standing respectfully to one side as proper robots should, wide awake and ticking while they awaited orders. Each was wearing a pair of Jim’s cast-off overalls, neatly pressed; their joints were carefully oiled so they would not squeak, and there wasn’t a speck of dust or rust on them, for Mrs. Bailey was very particular about their appearance. Their eye lights were bright, and the rows of buttons across their foreheads glowed with color. Rivets, whose brain was only semi-positronic, didn’t have as many buttons as Sprockets, but in the short time he had been with the Baileys he had managed very well by keeping his pay-attention button turned on most of the time.
    “Sir,” said Sprockets in his earnest little voice, answering the doctor’s question, “according to my calculations – and I am well educated in several onomies, including astronomy – it is true that Jim is getting a message from Mars. And, sir, it sounds like a perfect dilly. If you will permit me—”
    “Absolutely not,” said the doctor. “If there were anything on Mars, which there isn’t, and if Jim were old enough to have the comprehension to know it, which he isn’t and doesn’t, he couldn’t possibly hear it without my Super-Magna Space Probe, which I haven’t quite properly perfected.”
    “Aw, Daddy,” Jim told him, “Sprockets and I whipped up a do-jigger that takes care of it. It doesn’t work too well, but—”
    Jim stopped. Louder sounds were coming from the radio. Strange and unearthly sounds that simply had to be Martian because they couldn’t be anything else.
    “Bless me!” muttered the doctor. Suddenly he dashed to the radio and began twiddling the knobs. “Miranda!” he called. “Come listen to this!”
    “I’m right here, listening, Barnabas,” said Mrs. Bailey, who had been sitting there all the time, mending the robots’ overalls, which had a way of wearing out at the knees. She was a short, plump little woman with a turned-up nose and quick birdlike blue eyes like Jim’s.
    “Miranda,” said the doctor, and his mop of white hair was standing almost straight up with excitement. “Do you know what this means?”
    “How could I, dear? I don’t speak Martian.”
    “No, no, no! That isn’t the meaning I mean. I mean, do you realize the imperious import of this discovery?”
    “What’s ‘imperious import’ mean, Daddy?” Jim asked.
    “It means anything from top drawer to battle stations. Don’t interrupt me. Miranda, I must revise my concept of the fourth planet. Miranda, there is Something on Mars! I absolutely must get in touch with that Something and find out what it is.”
    “My goodness,” said Mrs. Bailey, “from the sound of it I hope you never meet it in the dark. And, dear, I don’t think you’d better fiddle too much with Jim’s radio. You might burn out his do-jigger, and then you’ll never—”
    She spoke too late. There was a loud crackling, a flash of sparks, and flame suddenly shot from the tubes. There might have been a bad fire in the laboratory if Sprockets, his hands and feet twinkling as fast as thought, hadn’t snatched up a fire extinguisher and smothered the radio with foam.
    “Barnabas Bailey!” Mrs. Bailey exclaimed. “Look what you’ve done! Honestly—”
    The doctor stood snapping his fingers, quite vexed. All at once he brightened. “Tut,” he said. “Tut, tut. There’s nothing lost.”
    “Except my radio,” Jim said dolefully.
    “A mere detail,” said his father. “Think nothing of it. What has been made once can always be made again, only bigger and better. Jim, you may have the honor of helping me finish my Super-Magna Space Probe. That is, if you and Sprockets can remember how you put together that er-ah – that do-jigger thing. How about it, Sprockets? Do you remember?”
    “Sir,” said Sprockets, lifting his head proudly, “you forget that I have a genuine Asimov Positronic Brain with twenty trillion printed circuits. I remember all.”
    “Of course. Naturally. Then let us get busy. Immediately. It is absolutely emphatically imperative that we talk to that Something on Mars. We must find out the who, the what, and the why of it before some infamous and unspeakable rascal beats us to it.”
    “Sir,” said Sprockets, “are you referring to Prof. Vladimir Katz, who recently escaped from jail?”
    “I am,” snapped the doctor. “And don’t mention that unmentionable name in my presence again.”
    “But, sir, I regret to inform you that that unmentionable one is now in Mongolia, doing something secret for the Mongolian Planetary Monopoly.”
    “What?” The doctor seemed staggered. “How did you learn that?”
    “From my built-in microscopic positronic radio, sir. I can hear any message in the world when I properly tune my circuits.”
    “Great gobbling guns!” cried Dr. Bailey. “If Vladimir Katz is working for the Mongolians, there’s no time to lose! He’ll find out all about Mars and monopolize it just as sure as purple saucers fly. Everybody to work! Fast!”
    As they trotted behind the doctor, Rivets turned on his whisper button and asked, “Spwockets, who ith that unthpeakable, unmenthunable – oh dear, my thkwew ith looth again!”
    “Sh-h-h!” Sprockets whispered, and gave a quick tock that amounted to a gulp, for poor Rivets had a screw in his head that was always coming loose at the wrong time. It made him sound positively addled, if not actually aberrated – and an aberrated robot was something that no proper robot cared to think about. Sprockets was terribly afraid the doctor might find out about it and send Rivets back to the factory to be exchanged. Never that!
    “I’ll explain about that man some other time,” Sprockets said hurriedly. “Let me fix your screw.”
    Out from the pockets of his overalls came a tiny screwdriver and a can of oil, and in two ticks and a tock he had tightened the loose screw and oiled Rivets’ tongue.
    “We must be on our toes for this job,” he told Rivets. “Is your pay-attention button on full?”
    “All the way.”
    “Careful button?”
    “All the way.”
    “Your hurry-up button?”
    “All the way.”
    “Your balance button?”
    “All the way.”
    “Then you’d better keep them all the way all the time.”
    “But, Sprockets, I may burn out my battery!”
    “Oh, no. You have an atomic battery just like mine, and it will recharge itself every night if you lie down for six hours, fifty-seven minutes, and twelve seconds.”
    “Aw, if I have to recharge, how can I play marbles at night?”
    “A robot shouldn’t play marbles when important work is going on.”
    “But I like to play with marbles!” said Rivets. “It makes me feel almost like a real boy. Didn’t you ever play with marbles?”
    “Certainly not! And you shouldn’t – not in the laboratory.”
    “I will if I want to,” Rivets pouted. “The doctor hasn’t ordered me not to, and you can’t order me without orders to do so. You’re only a robot, too.”
    “Stop that whispering and get busy!” shouted the doctor. “We’ve got to build the do-jigger and beat the Mongolians!”
    They rushed to work.
    Never before had the Bailey laboratory been in such a bustle. Rivets helped Sprockets, Sprockets helped Jim, Jim helped the doctor, and the doctor tore about fitting this to that and that to this, and sometimes getting so tangled in the Super-Magna Space Probe that it took everyone to untangle him. The Super-Magna Space Probe, on which the doctor had been fussing for seven years, was a vast tangle of wires and tubes and glass that, quite naturally, looked like nothing on Earth, since it was concerned only with matters far away from Earth. All it needed was Jim’s do-jigger – a very big do-jigger – to make it work.
    They toiled that night until the doctor and Jim tottered to bed, too exhausted to lift a finger. The robots were far from exhausted, though their batteries were getting low. But Rivets, instead of recharging, crawled happily about the laboratory floor, playing with his marbles.
    “It’s such fun!” said Rivets. “Please come play with me. Won’t you, huh?”
    “No!” said Sprockets. “I’ve got to recharge, and so have you. If you had a cerebration button and an imagination button like mine, you’d realize how important it is.”
    “Aw, you’ve got too many buttons to have any fun.” Suddenly Rivets blinked his eye lights curiously. “Who is Prof. Vladimir Katz?”
    “A most unpleasant man.” Sprockets gave a little tock at the thought. “He steals secrets for the Russians and the Mongolians. The doctor and I had a very bad encounter with him in Mexico, before you were made.”
    “Was that the time you found the purple flying saucer?”
    “Yes. Now you’d better recharge.”
    “I wish I could meet the purple flying saucer people. Do you think they’ll ever come back?”
    “Maybe. Now please put your marbles away and recharge. And promise you’ll do it every night.”
    Reluctantly, Rivets did as his brother asked.
    The do-jigger took form the next day, and grew and grew twistily. By the end of the third day it looked not unlike a glass octopus stuffed inside a huge goldfish bowl, and strangled in miles and miles of wire. It needed only to be properly connected to the Super-Magna Space Probe, and the doctor would be able to signal to the Something on Mars.
    The doctor, all eagerness, his nose twitching and his mop of hair flopping with excitement, scurried up a stepladder with his hands full of tools. Sprockets and Rivets, all their buttons glowing and most of them on full, including their balance buttons, carefully raised the big do-jigger as the doctor directed.
    “Up!” said the doctor. “Up! Up! Careful!”
    Up went the do-jigger, and down came Sprockets’ foot just as something – a lot of somethings, round and hard – fell rolling on the floor.
    They were marbles from Rivets’ pocket.
    On the instant both robots were slipping and sliding in spite of all their buttons, and their circuits were overheating as they fought to balance the do-jigger and not let it drop. A robot must never, never destroy property or do anything to hurt his master. But not to do so now was utterly impossible, and in the next instant their feet were flying out from under them and the do-jigger was flying away from them.
    “Watch it!” screamed the doctor. “Oh! Oh! Oh!”
    With a horrible sound of breaking glass, the do-jigger smashed into the Super-Magna Space Probe. Had the power been on, both Sprockets and Rivets would have been melted on the instant. Instead, they could only lie twitching in the wreckage, their eye lights blinking ninety to the second while their circuits snapped and crackled from shock.
    At this moment it was exactly three days, five hours, and fifty-two minutes since Jim had been in touch with Mars. With every tick, the robots’ circuits were getting hotter and hotter from the shock of having done something so dreadful. Unless someone speedily turned off their switches, their brains would sizzle and pop, and they would be robot dummies for the rest of their lives.
    Dr. Bailey was too shocked himself to do anything but sputter and tear his hair.
    Jim was so shocked he could only gulp and say, “Grief and Moses!” over and over.
    But Mrs. Bailey, who had a private opinion about the Space Probe, and who was quite motherly as well as practical, said: “Oh, the poor little frightened dears! I hope they aren’t hurt!” It took her just seven seconds to pull them from the wreckage and reach for their switch boxes.
    CLICK! CLICK!
    Their twitching and ticking stopped. Both robots were turned off, and barely in time. They lay motionless and helpless, with only their thoughts to trouble them. But it was such a blessed relief to feel their circuits cooling that for the moment nothing else mattered.

Chapter 2: They Put Their Heads Together
    For long minutes the robots were aware only of the comforting ice packs that Mrs. Bailey had placed on their foreheads. Usually, when they were turned off, Rivets spent his time trying to count to a hundred without making a mistake, while Sprockets added – and sometimes multiplied – large imaginary numbers full of sevens and nines. But today, as their circuits cooled, all they could do was listen, for Dr. Bailey was losing his temper.
    “Seven years’ work!” stormed Dr. Bailey, his voice rising. “Ruined because of robots!”
    “It was because of marbles, dear,” Mrs. Bailey said sweetly. “I’m really to blame.”
    “Marbles!” screamed the Doctor. “What were they doing with marbles?”
    “I gave some to Rivets,” said Mrs. Bailey. “He did love them so.”
    “I won’t have a robot that plays with marbles!” howled Dr. Bailey. “I won’t have robots at all! They’ve wrecked my Space Probe! They’ve ruined my only chance of talking to that Something on Mars! They’ve unequivocally nullified, negated, and nonplussed the answer to the greatest scientific secret of the century – and given it to the Mongolians! They’ve—”
    “Daddy,” Jim interrupted, “what does unequivocally nullify, negate, and nonplus mean?”
    “Silence!” thundered the doctor, his mop of white hair flying this way and that. “Don’t you know better than to interrupt me when I’m furious? It means they’ve rocked the boat and sunk it, but good. I’m through with robots! Miranda, call the robot factory. Tell them to come and take these worthless mechanical contraptions out of my sight at once!”
    “Now, Barnabas,” said Mrs. Bailey, “you know very well they aren’t worthless. For a scientist so famous in so many ologies and onomies, you—”
    “They are worse than worthless!” roared the doctor. “They are addled, aberrated, destructive, and dangerous. I want ’em torn apart, dismembered, and pulverized! I want—”
    “Barnabas,” said Mrs. Bailey, very severely this time, “what you want is a cup of sassafras tea with honey in it to calm you down.”
    She made him a cup of sassafras tea, double strength, and put a large gob of sourwood honey in it. The doctor gulped it, and it did calm him a lot, though his nose still twitched.
    “Accidents happen in the very best of families,” Mrs. Bailey said. “It’s only fair that Sprockets and Rivets be allowed to speak for themselves. If you’ll turn them on—”
    “You turn them on,” snapped the doctor. “I absolutely refuse to touch them!”
    CLICK! CLICK!
    Sprockets and Rivets got up and stood stiffly at attention, their eye lights blinking worriedly. Their circuits were cool now, but their heads ached from the awful knowledge of what they had done.
    “You poor little dears,” Mrs. Bailey said kindly. “You’ve had a terrible experience. How do you feel?”
    “Horrid, ma’am,” said Sprockets, speaking for them both, as he usually did. “Perfectly ghastly. Words cannot begin to express our shame. But we are everlastingly grateful to you for saving our wits. And we earnestly hope we may be allowed to repair the damage we caused.”
    “R-repair the damage!” the doctor sputtered. “Ha! What madness is this?”
    “I betcha they could, Daddy,” said Jim. “How long would it take you, Sprockets?”
    “Seven days,” Sprockets answered. “If we may be allowed—”
    “Seven days to rebuild a machine that took me seven years to create?” the doctor waved a trembling hand at the tangled wreckage of the Space Probe. “Any robot who would make such a statement has lost his wits! Now I’m convinced you are mad, addled, aberrated, and entirely deranged!”
    “B-b-but, thir,” little Rivets burst out, not realizing his screw was loose again. “My brudder’s not abbled! He’th tho thmart he can fix enyfing!”
    Sprockets gave a tock of dismay. “Oh, sir, please!” he begged quickly. “Our circuits have had a most jellifying jolt, and we’ve hardly had time to recover. If I may be permitted to explain—”
    “You may not!” the doctor snapped. “I’ve had enough of you both. One of you is so abbled – I mean addled – he can’t even talk. And the other is downright deranged. I never want to see you in this laboratory again. Go to your room – and stay there till the robot factory sends for you!”
    With heads down, Sprockets and Rivets trudged dejectedly upstairs to their room next to Jim’s.
    “I’m tho thorry,” Rivets said, when they were alone.
    “It’s too late to be thorry – I mean sorry,” Sprockets told him. “You shouldn’t have spoken when your screw was looth – I mean loose – and I warned you about the marbles.”
    “I gueth I’m not quite wight bwight.”
    “Neither of us is quite right bright right now. Oh, my poor aching circuits! I’ve got to think as I’ve never thought before – and I can’t think when my circuits ache. Let me fix your looth – loose – screw.”
    He had just tightened the screw, and oiled Rivets’ tongue and his own, when Mrs. Bailey and Jim came into the room. Jim had some fresh ice packs in his hand, and Mrs. Bailey carried a large box of learning tapes.
    She wiped a tear from her eye, and said, “The robot factory can’t send for you until tomorrow, and that may give us time if we work fast.”
    “Time for what, ma’am?” Sprockets blinked at the learning tapes. The very sight of them made his circuits squirm.
    “Time to be superly-superly educated,” said Mrs. Bailey. “When the doctor sees you again – and I’ll make sure that he does – I want you both to be wide-eyed and bushy-tailed, and simply popping with knowledge. Then he’ll have to change his mind and decide to keep you – that is, if you can think of some way to beat the Mongolians.”
    “B-but, ma’am—”
    “No buts. You’ve only been half educated in a few onomies and ologies. I’m going to give you stacks more, and include some otomies and istics.”
    “Oh–no–no–no–no–no—”
    There was absolutely nothing, aside from being returned to the robot factory, that Sprockets and Rivets hated more than to have learning tapes run through their heads. The thought of it now, with their poor heads splitting, was enough to give them spasms.
    But it was either that or the robot factory; and in three ticks and a double tock they were sitting on their stools, and Mrs. Bailey had turned on their learning buttons and inserted a learning tape in the slot in the back of each robot’s head.
    “Let’s see,” said Mrs. Bailey, “linguistics would help a lot, as would statistics and ballistics. As for the otomies, there’s lobotomy, pneumotomy, monotomy – oh, dear, this is making me abbled! I don’t know why they don’t make a single tape for all the otomies, then I wouldn’t have to worry about them.”
    Neither of the robots could hear her, for new knowledge was screaming through their aching circuits, making them sizzle like frying fish. It was bad enough for Rivets, whose circuits were limited; but for poor Sprockets, who had twenty trillion to sizzle, all at the same time, it was absolutely horrendous. Their heads were blistering, but Jim put fresh ice packs on them whenever Mrs. Bailey put new tapes in their slots. When they finally stiffened from so much education, and passed out completely, they had to be turned off and put to bed.
    It seemed ages and ages before they were turned on and began to tick again.
    “Do you feel wide-eyed and bushy-tailed now?” Mrs. Bailey asked hopefully.
    “I feel wonnerful, ma’am!” said Rivets, bouncing to his feet, his loose screw only slightly loose. “I bet I can count to a hundert!”
    But poor Sprockets could hardly sit up. “I feel practically fused, ma’am. It must be remembered that my mechanism is far more sensitive and complicated than my brother’s, and that it has taken an awful walloping. It will be fourteen hours and eighteen seconds before I can click properly again.”
    “But, Sprockets!” Jim burst out. “The truck from the robot factory will be here before that! What are we going to do?”
    “Would it help if you turned on your cerebration button?” Mrs. Bailey asked.
    “I wouldn’t dare,” said Sprockets. “Then I’d really be fused.”
    Mrs. Bailey wiped a tear from her eye. “We can’t have you any more abbled than you are. Can’t anyone think of anything?”
    Rivets said: “Ma’am, my bwain’s only themi-pothitwonic, but I bet if it could be hooked up to Spwockets, we’d have a whole bwain between us. Then mebbe we could fink what to do.”
    Jim said, “Would it work, Sprockets?”
    “According to my new learning tapes, which include lobotomy,” Sprockets answered, “it would be like lobotomy in reverse. All we have to do is connect Rivets’ pay-attention button to my special perceptors. Then possibly I will have brains enough to cope with the Mongolian question.”
    Jim brought wires and tools and speedily made the connection.
    “Wow!” said Sprockets, as his buttons flashed and a halo of color began spinning about his head. “This is really super!”
    “Hurry up with the answer,” poor Rivets pleaded. “It may be thuper for you, but it ith orful hard on me!”
    “Patience,” said Sprockets. “First I must tune in on the Mongolians and find out what is happening.” Hastily he adjusted his built-in radio and listened.
    “Oh!” he said finally. “This is bad. It will make the doctor very unhappy.”
    “What’s cooking?” Jim asked. “Has Prof. Vladimir Katz found out about the Something on Mars?”
    “Not yet, but he will soon. It seems, as nearly as I can translate, that the secret on which Prof. Vladimir Katz was working for the Mongolians was not a Space Probe. It was a spaceship, and it has just been launched. The professor is now sixty-two thousand miles out in space, on his way to Mars.”
    Jim looked sick. “Daddy will never get over this,” he said dolefully. “And there’s not a thing we can do about it.”
    “There is just one thing,” said Sprockets. Very carefully, so as not to strain the wires connecting him to Rivets, he reached under his cot and brought forth a small box not much bigger than his hand. When he opened it, purple light flooded the room.
    Jim gaped at it in astonishment. “Is that the present the purple people gave you when you found the quantic moonstone for them?”
    “Yes,” said Sprockets. “It’s their signal box. They said if we ever needed them in an emergency, I was to press the button in this box, think real hard, and they would come.”
    Jim looked doubtful. “Aw, suppose they are way over on the other side of the Universe – a million light years away! How can they possibly hear a signal from a little box?”
    “Distance has nothing to do with it,” Sprockets told him. “It works by thought – and thought is quicker than light. I’m not sure that positronic thought will work, but this is an emergency of the most desperate kind, so we’ll have to try it. Turn on all your buttons, Rivets, and think hard!”
    “B-but how can I fink when I don’t know what to fink about?”
    Sprockets almost groaned. Rivets had never met Ilium and Leli, the purple people, and couldn’t possibly imagine what they were like, or how they talked. “Oh, just close your eyes and think of something purple-purple marbles if you have to. I’ll do the rest. Ready? Go!”
    As Rivets closed his eyes, Sprockets did the same, and pressed down on the button in the purple box. Ilium and Leli! he thought, using the singing language he had learned from them. Sprockets calling! We need your help. Come quickly!”
    Almost instantly from the box, very faintly, came a curious singing that only Sprockets could understand. It was so very, very faint that it must have come from an unimaginable distance, possibly some other universe.
    “We hear you, Sprockets,” came the singing from the box. “We are coming!”
    If there was more, Sprockets was not aware of it. Somewhere in his brain a safety relay buzzed and clicked off, to give his poor battered circuits a rest. It would be fourteen hours and eighteen seconds before it clicked on again.

Chapter 3: They Begin a Journey
    The truck from the robot factory, fortunately, arrived an hour late the next morning. Had it come earlier, the doctor would not have had time to drink three cups of sassafras tea with large gobs of sourwood honey in it, and Sprockets and Rivets might have been taken back to the factory. But the tea calmed the doctor, so much so that he wondered if he hadn’t been a bit hasty in his judgment. After all, he thought, little Rivets had his good points in spite of the marbles; and Sprockets, well, perhaps Sprockets could rebuild the Space Probe.
    But at that moment his thoughts were interrupted by the laboratory clock, which was connected with his observatory on the roof.
    “It is a quarter past ten,” said the clock, very precisely as if it were proud of its ability to keep time. “The day is clear and there are no flying saucers—” Then abruptly it flashed a red light and cried: “Correction! Correction! There is a flying saucer!” And all at once it was screaming: “Flying saucer! Flying saucer! Flying saucer!”
    The doctor upset his teacup, dashed madly upstairs, changed his mind, and dashed madly down again, turned around twice in his excitement, and dashed into the courtyard. He collided with the driver of the truck from the robot factory, who was staring upward, bug-eyed, at a purple flying saucer hovering overhead.
    “Ug!” said the truck driver, pointing. “Flying s-s-saucer! A p-p-purple one!”
    “Naturally it’s a purple one!” snapped the doctor. “Take that truck out of the way so it can land!”
    “B-but I came to pick up a pair of witless and deranged—”
    “We don’t have any! Some addle-pated idiot made a mistake! Return to the factory!” The doctor dashed back into the house and tore upstairs again, calling loudly: “Sprockets! Sprockets! Where are you? Come here this instant!”
    He found Sprockets asleep on his cot in the robots’ room. Standing beside him were Rivets, who was counting, Jim, who held a watch, and Mrs. Bailey, who had an instruction book on robots in her hand.
    “What’s going on here?” the doctor demanded impatiently.
    “Sprockets is asleep, dear,” Mrs. Bailey told him.
    “Robots never sleep!” snapped the doctor.
    “They do when they’ve had jellifying jolts and their safety relay clicks off,” Mrs. Bailey informed him. “It says so right here in the instruction book.”
    “But I can’t have him sleeping now!” cried the doctor. “Don’t you know the purple saucer has come to visit us?”
    “Of course I know it, dear. Sprockets sent for it.”
    “He sent for it? Bless me, how? Why? What for?”
    “To help solve the Mongolian question, dear.”
    “Then wake him up! Hurry!”
    “Daddy,” said Jim, “Sprockets can’t wake up till his safety relay clicks on again. It’s almost time.”
    “Fifty-wun,” Rivets was counting. “Fifty-two. Fifty-fwee...”
    At the count of “sixty” Sprockets opened his eyes, blinked, and suddenly bounced to his feet. For the first time since the accident he felt really wide-eyed and bushy-tailed, and in full possession of his circuits.
    “Sir,” he said to the doctor, “I hope you will accept my apologies for the trouble I have caused you. Has the purple flying saucer arrived yet?”
    “Of course it’s arrived!” cried the doctor. “Why do you think I’m standing here tearing my hair? Get down there and greet them! You know I can’t sing and twitter their language!”
    “Yes, sir!” said Sprockets, and was gone like a flash, oiling his tongue as he ran. The musical language of the purple people was the most difficult one he had ever learned, and very hard on the tongue bearings.
    Outside, he gave a joyous little tock at the sight of the purple saucer shimmering in the courtyard, and raced up the narrow stairway that had been lowered for him.
    “Ilium! Leli!” he sang to his friends, as they ran to him with outstretched hands.
    They were small, hardly taller than Jim, but very, very slender and beautiful, so that they reminded Sprockets of the slender-stemmed flowers in Mrs. Bailey’s garden. Everything about them, even their curious clothing, had a lovely purplelike glow that seemed one color one moment and another color the next.
    “It is purplishly, glowingly wonderful to see you again,” Leli sang, in the gay manner of the purple people, and she kissed him fondly on the end of the nose.
    “We came as quickly as we could,” Ilium told him. “But we were way over in the Globular Cluster beyond the Edge, twelve thought-laps away.” He smiled and added, “What can we do to help you?”
    “It’s about our fourth planet,” said Sprockets. “The red one we call Mars. It’s put us in an unpurplish pickle. Did you know there’s a Something on it?”
    “We didn’t even suspect it.” Ilium was suddenly interested, so much so that his eyes changed color and shone like opals. “It’s such a curiously worn-down place, and it seems lifeless except for the lichens. How did you learn about it?”
    Sprockets told him what had happened.
    “Then we must go to Mars and search for the Something. It is very important, most galactically so. All Somethings on all planets must be investigated. Tell the doctor we will be most spectrumly pleased if he will come with us.”
    “He will be most purplishly delighted to hear it,” Sprockets sang in reply. He turned as Jim, the doctor, and Rivets came up to the saucer’s slender stairway. “This is my new brother, Rivets,” he explained. “He’s only semi-positronic, but he’s the best brother a robot ever had. He helped me signal you when my circuits were jammed.”
    “I thought so!” Leli laughed. “When your signal came, we also received a distinct impression of marbles – purple marbles. We knew it wasn’t you. Anyway, we thought they might be needed, so we brought some along.”
    “He’ll love you for it,” Sprockets sang. “But I’m not so sure about the doctor.”
    Rivets was blinking at him in amazement. “Spwockets, how did you learn to twibble like that? You thound like a mocklingbird!”
    “S-h-h!” Sprockets whispered warningly. “Your screw—”
    But the doctor was far too excited over seeing his saucer friends again to notice anything else. His only difficulty was the matter of the musical language, which was far too fast and full of trills for an Earthman, even the doctor, to learn.
    “Bless me!” he sputtered. “Ig, ow, oh – what, how—”
    “Sir,” said Sprockets, “it’s all been arranged.”
    “Eh? Bless me again, what’s been arranged?”
    “The solution to the Mongolian question, sir. You’ve been told, no doubt, about what that unspeakable, unmentionable person—”
    Jim said: “He doesn’t know yet, Sprockets. You don’t think I’d tell him what Professor Katz has done, do you?”
    “Eh? What’s this about Vladimir Katz?” The doctor’s mop of white hair began to bristle. “Speak plainly, Sprockets. Mince no names.”
    “Yes, sir. No, sir. I regret to inform you, sir, that Prof. Vladimir Katz is on his way to monopolize Mars in a spaceship built by the Mongolian Planetary Monopoly. If he monopolizes Mars, he may learn about the Something and monopolize it.”
    The doctor was thunderstruck. But before he could bristle further, Sprockets added hastily: “However, sir, I am happy to inform you that I have just concluded arrangements for us to fly to Mars and search for the Something with Ilium and Leli. As you know, the saucer’s speed is such that we can easily fly circles around the professor and reach our destination many weeks ahead of him.”
    “Bless me!” said the doctor, quite overcome. “Bless me!” Then he exclaimed, “Mars!” and his voice fairly vibrated with rising excitement. “This is absolutely triply terrific! Now I can solve the secret of the Something – and do it face to face. I must tell Miranda and get my things.”
    Dr. Bailey turned and rushed down the stairway, with Jim panting eagerly at his heels.
    They found Mrs. Bailey in the kitchen, packing a lunch basket. “You don’t have to tell me,” she said. “You’re going to Mars – and meet that horrible Something face to face.”
    “Of course,” said the doctor. “Naturally. How else would we meet it?”
    “I don’t know, unless you use mirrors.” She wiped a tear from her eye. “I hope you don’t meet it in the dark.”
    “Never fear. We’ll carry flashlights. Now, if you’ll fix us a spot of lunch—”
    “I’m already fixing it, Barnabas. But all the way to Mars – and Jim is so young.”
    “Posh and twiddle, he’s going on ten, eleven, or maybe twelve,” said the doctor, who never could remember Jim’s age. “Anyway, he’s practically a juvenile adult.”
    “I’m quite aware of it, dear, and I’d never let you go bumbling so far from home without him. But – but Mars!”
    “Aw, Mom,” said Jim. “It’s only a bit farther than the Moon, sort of.”
    “Only a trifle, so to speak,” hastened the doctor. “Space is so readily relative, especially in a saucer. We’ll pop over, look at a canal or two, and pop right back.” He snapped his fingers. “Just like that. Nothing to it. You really should come along, Miranda, and see the Martian canals. They’re—”
    “Gracious, no! Someone in this family has to keep a firm foot on solid Earth. But I suppose you’re taking Sprockets and Rivets?”
    “Sprockets, yes. He’s needed. Rivets, no. I can’t risk being flumdiddled on the fourth planet by a piddling little robot that plays with marbles.”
    They were interrupted by Sprockets, who came hurrying to help the doctor pack.
    “Where’s Rivets?” the doctor demanded.
    “Sir, Ilium and Leli are running a language tape through his slot. They think he can learn a simplified version of their musical tongue. In which case, sir, he would be of inestimable help in communications whenever we are separated.”
    “Glurp!” gurgled the doctor. “That settles it. Sprockets, pack my ice skates and swimming trunks. We must be prepared to investigate the Martian canals, depending on their condition. But don’t bother with the space suits – Ilium has much better ones than ours.”
    By the time they were ready to leave, Mrs. Bailey had stuffed a huge lunch basket with sandwiches, fried chicken, cheese, sausage, olives, pickles, plums, ice cream and cake, and a special box of goodies for Ilium and Leli. Finally she handed Jim a big thermos bottle filled with sassafras tea with large gobs of sourwood honey in it.
    “Now mind, Jim. Whenever your daddy gets too excited, give him a cup of tea.”
    “Yes, Mom. What do you want me to bring you from Mars?”
    “Anything but that Something. I won’t have it in the house.”
    She kissed them all good-by except Rivets, who was still recovering from his language tape, and she stood waving to them while the saucer rose humming in the sunlight.
    They rose slowly at first, then Ilium switched on the under-gravity nullifiers and the saucer sped almost instantly into the darkness of space. With the nullifiers on, it seemed, even to Sprockets, that they were standing still. The only way he could tell that they were moving was to see Earth becoming smaller and smaller on one side, and space becoming blacker and blacker on the other – except for the small red dot that was Mars growing bigger and redder.
    “Whee!” said the doctor. “This is really whizzing. How does the saucer do it, Sprockets?”
    “Sir, as I’ve explained to you before, the saucer has hyper-sub-medio space inductors that are connected to a thought thingummy, so naturally we can fly as fast as thought.”
    “Naturally,” said the doctor, “I remember. Ilium has merely to think for it to go – this way or that way, and as fast as he wants – and that’s the way it goes. So of course we fly thoughtfully. Very simple indeed. How fast are we flying now?”
    Sprockets spoke to Ilium, then translated: “Only three hundred thousand miles a minute at the moment, sir. It is dreadfully slow, but he says if we go faster you might become abbled – I mean addled – even with the nullifiers on. At the present rate, sir, we will land on Mars in six hours and seven minutes. As for Professor Katz and the Mongolians, of course—”
    “Yes, yes? What about the rascals? Are we near them?”
    “Practically abeam, sir. As nearly as I can compute, sir, they are six thousand and three miles, seven hundred and forty-two feet off to starboard. Ilium wants to know if you would like to swing over and have a look at their spaceship.”
    “Indeed I would! I have the gravest suspicions about their ship,” said the doctor emphatically.
    “Daddy,” said Jim, “do you think their ship was built from the designs someone stole from you?”
    “Exactly,” snapped the doctor. “And I suspect Vladimir Katz. All he can do is filch and purloin, connive and prevaricate. He cannot create.”
    “Daddy, what does ‘filch and purloin, connive and prevaricate’ mean?”
    “It means less than I can say, and he’s a double-dyed rat to boot. Heaven preserve us! What’s that racket?”
    They turned to see Rivets sitting up, blinking his eye lights rapidly.
    “Yeedle-de-yee! Jiggle-le-je!” Rivets was singing. “Oh, Spwockets, I can twibble like a mocklingbird!”
    Sprockets had his screwdriver and oil can out in a flash. It took hardly a second to fix the screw, but it was too late to change what the doctor had heard.
    Dr. Bailey shook his head sadly. “If only I’d known in time, I could have sent him back to the factory. Now we’ll be stuck on Mars with an abbled robot.”

Chapter 4: They Abble the Professor
    Sprockets wanted desperately to explain about poor Rivets’ loose screw, which seemed to be getting looser no matter how he tightened it. But it was a bad moment to explain anything, for suddenly everyone’s attention was taken by the Mongolian spaceship, which appeared off to starboard.
    It was a long, gleaming rocketlike shape – exactly the shape of the spaceship model in the doctor’s laboratory. Sprockets thought it looked very handsome indeed as it streaked through space, with the stars bright as diamonds beyond it and a stream of blue fire shooting from its tail.
    “Very handsome,” said the doctor, thinking the same thing. “Very handsome, indeed. As naturally it would be, since I designed it.” Then all at once his mop of white hair began to bristle. “Sprockets, tell Ilium to take us closer. It will ease my ire to see Vladimir Katz befuddled – and he is bound to be befuddled when he sees who has overtaken him in a purple saucer.”
    “Yes, sir,” said Sprockets. “But I regret to remind you, sir, that although we will be able to see Professor Katz through our viewing ports, he will be unable to see us through ours. The saucer’s windows are of a special material that is transparent only from the inside.”
    Even so, it did seem to ease the doctor’s mind slightly when he saw the look on the professor’s face as the saucer swung close. Prof. Vladimir Katz was a fuming, wheezing, waddling barrel of a man with no hair on his head, no neck under it, and a great many chins, possibly four or five. Sprockets saw him flatten his big nose against the spaceship’s viewing port, and stare pop-eyed at the saucer like a great bullfrog ready to burst. The professor was completely astounded, though hardly befuddled. But the Mongolian crew behind him was completely befuddled, for they could be seen trembling and falling over each other in the corner of the control room.
    Sprockets hardly noticed the crew, for he had turned on his cerebration button while he checked the ship’s course. In two ticks and a sudden tock he made a most unpleasant discovery.
    “Sir,” he said to the doctor, “it is my sad duty to inform you that you are faced with a particularly paramount and perplexing problem in ethics.”
    “W-what’s ‘paramount and perplexing’—” Jim began.
    “Hold it!” ordered the doctor. “Ethics, did you say? Ethics?”
    “Yes, sir,” Sprockets replied. “Among my learning tapes, sir, was a very difficult one on that subject. It dealt with the good and bad in matters, and one’s proper conduct in a double dilemma.”
    “Hey, what’s ‘a double dilemma’?” Jim burst out.
    Sprockets was always surprised that Jim, who was so super-smart about most things, had so much trouble with words. But before he could answer, Rivets, whose screw was almost too tight now, exclaimed: “Oh, I know that one. A double dilemma is something with two horns, and you don’t know which horn to get stuck on.”
    “Enough of this posh and twiddle!” sputtered the doctor. “Sprockets, get to the point, or I’ll turn you off!”
    “Yes, sir! What I’m trying to tell you, sir, is that the Mongolian spaceship is a trifle off course. It is bound to miss Mars.”
    “Eh? Off course? Are you sure?”
    “Positive, sir. With my positronic computers, my radar vision, and my special tapes on astronomy, I am incapable of error. The Mongolian spaceship, naturally, being only a spaceship, and very slow compared with a purple saucer, must fly to a point where Mars will be nine weeks from now, and not where Mars is now.”
    “Naturally,” said the doctor. “Quite elemental. Proceed.”
    “Well, sir, I regret to say that Mars will not be there when they get there. Mars will be five hundred and eighty-two thousand, seven hundred and twenty-three and a half miles beyond them.”
    “Great jiggling jeepers!” muttered the doctor. “If they miss Mars that far, they’ll never be able to reach it before their atomic evaporators use up all their water. And if they can’t reach Mars and get more water for fuel, they’ll never see Earth again. Oh, Sprockets, why did you have to tell me this just now?”
    “Ethics, sir.”
    “What are you going to do, Daddy?” Jim asked.
    “I’m tempted,” the doctor growled, “to let the rascals float forever in space. Earth would be much better off without Prof. Vladimir Katz.”
    Sprockets blinked his eye light thoughtfully. “You are absolutely right, sir. But would that be ethical?”
    “It would not,” said the doctor. “And I will not have the life of Vladimir Katz on my conscience – not to mention a crew of mongrelly Mongolians. Sprockets, signal the spaceship and tell them their error.”
    “One moment, sir.”
    Sprockets turned on his built-in radio, adjusted his voice button, and said in a loud commanding tone: “Purple saucer calling spaceship! Purple saucer calling spaceship! Come in, please!”
    There was no answer, so he tried it again in Low German, Russian, two Mongolian dialects, and the Morse code in five languages for good measure.
    At last he said to the doctor: “I cannot raise them, sir. Their radio seems to be turned off.”
    The doctor was very upset. “Dear me!” he muttered. “Sprockets, there is only one thing to do. Ethics demands that one of us must somehow manage to board the spaceship and tell them in person. Er, ah, I expect it will have to be you.”
    Sprockets tried to say, “Yes, sir,” but all he could manage was a loud tock.
    Dr. Bailey stared at him. “Bless me, are you afraid, Sprockets?”
    “N-not exactly, sir. It – it’s only because I am so valuable, sir. If I were worthless, it would not matter. But I am worth double my weight in gold, and if anything happened to me your loss would be extreme.”
    “Then let’s get this uncertainty over with. The quicker the better.”
    “Y-yes, sir. But I may need some help from Rivets.”
    Rivets seemed upset. “D-do I have to go with you?”
    “I hope not. You’re to stand by for messages. Turn on your radio.”
    “Didn’t know I had one,” said Rivets.
    “Of course you have one! The button is on the back of your head, near your learning slot.” Sprockets turned it on for him.
    “Whee!” said Rivets. “It tickles.”
    “Keep it tickling. This is a ticklish situation.”
    Sprockets was not worried about getting aboard the spaceship, which was no problem at all. Ilium merely turned on the saucer’s force field, which acted as an air lock, and opened a port. Sprockets jumped through it, and floated weightless to the side of the spaceship. As he touched, he switched on the magnets in his feet, giving them just enough power for walking. Then he moved like a fly to the viewing port where Professor Katz was standing.
    The professor recognized him on the instant, and his big bullfroggy face nearly exploded with surprise, rage, and sudden frightening determination. The professor wasted not a moment in ordering the outer door of the ship’s air lock to be opened.
    Sprockets entered. He sealed the lock from the inside, waited for the place to be filled with air and the inner door to be opened, and walked bravely into the control room to face whatever fate awaited him.
    There was very little gravity in the spaceship, and Prof. Vladimir Katz and his crew were almost floating.
    “Well!” began Professor Katz in his horribly fumy, croaky voice. “Well! Well! W-e-l-l! If it isn’t Barnabas Bailey’s little two-bit robot that gave me such troubles in Mexico! What brings you here, foolish one?”
    “Sir, I have come to save your life.”
    “Bah! You come to pry into secrets that do not concern you.”
    “Not at all, sir. I have come to inform you, sir, that you have made an error in navigation. You will miss Mars by five hundred and eighty-two thousand, seven hundred and twenty-three and a half miles.”
    The professor stared at him. Then he hooked his thick thumbs into his bulging belt and suddenly roared so hard with laughter that he nearly floated to the ceiling. “Ha! Ha! Ha! Ho! Ho! Ho-o-o! Does Barnabas Bailey think he can keep me away from Mars by such a trick?”
    “It is no trick, sir. I’m an honest little robot, and it is impossible for me to twiddle with the truth. I suggest you check your computers if you want to save your skin. Good-by, sir.”
    Sprockets turned to go back into the air lock, but one of the Mongolian crewmen had closed the door and bolted it, and now stood guarding it.
    The professor’s big hand jerked Sprockets around. “You think to leave? Ha! You are my prisoner, foolish one. There is nothing wrong with my computers – but much will be wrong with you when I finish sizzling your circuits. You think I forget how you trick me in Mexico, and let Barnabas Bailey find the purple saucer? For that you will sizzle and sizzle and sizzle. I hate robots!”
    The very thought of what Professor Katz could do to his quivering circuits was almost enough to make poor Sprockets fall to his knees and beg for his life. But he realized that Rivets as well as the others would be listening; they had all strapped on their wrist radios before he left, and could hear every word that was being spoken. He was suddenly thankful that he not only had his own radio on, but most of his important buttons as well. He would need all his wits to escape.
    But how does a robot escape from such a predicament as this?
    He couldn’t do it alone. Rivets would have to help.
    “Sir,” he said to the professor, “since you are going to sizzle my circuits, do you mind if I sing?”
    “Sing? Sing? Who ever heard of a robot that could sing!”
    “Sir, I can sing like a mockingbird. Listen!”
    With a quick twitch of his fingers, Sprockets adjusted his voice button and began to sing. As the first rapid trills of the language of the purple people poured from his tongue, the professor’s mouth dropped in surprise, so that he looked more than ever like a startled bullfrog. The Mongolian crewmen gaped, then started to grin and jabber to each other.
    As he sang, Sprockets watched the purple saucer from the corner of his eye. He was relieved when it moved out of sight of the viewing ports. Presently, if everything went well, Rivets would have dropped unseen upon the tail of the spaceship.
    Suddenly there came a strange pounding upon the spaceship’s hull. The Mongolian crewmen stiffened, listening. Prof. Vladimir Katz stiffened too, and so quickly that he bounced to the ceiling.
    “W-what is that noise?” the professor stammered, as the pounding moved around the ship’s hull and crept ominously forward.
    “Sir,” said Sprockets in an awed voice, “it sounds to me like a space ghost.”
    “A space ghost!” gurgled the professor. “Nonsense! There is no such thing!”
    “Look!” Sprockets cried excitedly, pointing to the forward viewing port. “W-what’s that?”
    Something horrible and white was moving across the thick plastic glass of the forward port. It had a large formless head, like a ball of white, and a long formless white body that seemed to drift away in space.
    The thing scrabbled at the glass as if it wanted to get in. The Mongolian crew shrieked and fell tumbling over each other, trying to find corners to hide in. Only Prof. Vladimir Katz held his ground. Being a man of many ologies and onomies, he was not easily fooled, though he could be momentarily abbled.
    It took Professor Katz four and a half seconds to decide that the space ghost must be something from the purple saucer, and that more than likely it was another little robot with a sheet tied around him.
    The professor whirled, but he was a half second too late. It was all the time Sprockets needed to reach the unguarded door to the air lock, unbolt it, and wrench it open. He darted through into the air lock, slammed the door shut, and bolted it from the inside. Now he tugged frantically at the bolts to the outer door.
    In another second, Sprockets knew, the professor would remember the lever that operated the air lock by remote control. The professor had only to press his big hand down on the lever, and Sprockets would be trapped.
    As he tugged at the bolts, he could hear the professor roaring and wheezing and fuming in the control room, and speaking unspeakably in Low German, Russian, and two Mongolian dialects. It was quite awful to hear him.
    Sprockets got the bolts almost unfastened, but they snapped shut again as the professor threw his weight on the lever. Sprockets despaired.
    All at once he remembered there was very little gravity in the spaceship. The professor, though big as a barrel, weighed practically nothing and bounced easily. But a robot with magnets on his feet could not bounce – so long as the magnets held.
    In less time than it takes to think about it, Sprockets had turned on his magnets to full power, thrust his feet on the air lock door, and was jerking on the bolts with all his strength.
    The bolts slid back. The door flew open with a rush of escaping air, and Sprockets, in spite of his magnets, was blown out into space.

Chapter 5: They Are Lost in Space
    Had Sprockets remembered it in time, and known more about spaceships before opening the door, he would have found the air valve and emptied the air lock first. It would have made everything much easier. But with all the air escaping at once, it was like being shot from a gun. In a twinkling Sprockets was blown nearly a mile.
    His first thought was for Rivets. “Jump!” he called over his radio. “The saucer will pick us up.”
    He couldn’t hear his voice except for a tinny ringing inside his head, for there was no air to carry sound. How would it affect his radio?
    He was greatly relieved when he heard Rivets answer: “I’ve alweddy jumped – but I can’t thee a fing. I’m tangled in the theet and tumbling in thpace.”
    “Oh, dear, you must be over on the other side of the spaceship. I can’t see you on this side. Are you all right?”
    “I’m all wight ’thept for my looth thkwew. Can I turn off my wadio? It tickles.”
    “Oh, no! Don’t you dare turn it off, or Ilium won’t be able to find you. Don’t you realize that we are flying away from each other, and that soon we’ll be miles and miles and miles apart?”
    “Weally? Then I’ll keep it tickling. Why are we flying away from each other?”
    “Because we jumped in opposite directions, and there’s nothing to stop us. In space, you keep going and going and going.”
    “I’m worrit, Spwockets. Where’th the thauther?”
    Sprockets had been searching for the purple saucer, but there was no sign of it in the blackness around him. There was only the distant spaceship, so small now that it was a streak of blue against the stars. Away to the left of it was a tiny white dot that must be Rivets. Without using his radar vision or his special perceptors, Sprockets realized the only reason he could still see Rivets was because of the white sheet he wore. It reflected the sunlight, as did Earth and the Moon far below him. The sun was a fiery ball on his right, but it cast no glow in the empty airless blackness that was space.
    What could have happened to the purple saucer?
    “I can’t locate the saucer,” he told Rivets. “But I’m sure it’s around somewhere. There’s nothing to be worried about. Are you untangled?”
    “Yeth, but I can’t thee you.”
    “It’s because I’m not wearing a white sheet to reflect the sun. Save your sheet. It will make it easier for the saucer to find you.”
    “B-but, Spwockets, where ith the thauther?”
    “I can’t imagine, but it’s got to be somewhere around. I’ll see if I can raise Ilium.”
    Sprockets adjusted his voice button, and sang out – or rather he went through the motions of singing out, for it made only a small sound inside his head – “Ilium! Ilium! Sprockets calling. Where are you, Ilium?”
    There was no answer.
    Strange, for everyone in the saucer had a wrist radio, and surely by this time he should have heard from one of them. Something must be terribly wrong.
    Sprockets turned on his imagination button – but after three frightful tocks he turned it off quickly. It was definitely not the button to touch at a time like this. It must be awful to be a human, he thought, and have an imagination you couldn’t turn off.
    “I don’t know what’s happened,” he called to Rivets. “We’ll have to wait.”
    “But wait how long, Spwockets?”
    “Who knows? What does it matter? After all, we’re just robots – and that’s something to be thankful for.”
    “Mebbe tho, but I wisht I had my mobbles to play with.”
    “Aw, Rivets, you couldn’t play with mobbles – I mean marbles – out here.”
    “Well, I got to do sumfing and I don’t feel like counting. I fink I’ll make up poetwy.”
    “Poetry! Oh, no!”
    “Yeth. How’th thith?” And Rivets recited in his plaintive voice:
       “Two liddle wobots, lost in thpathe,
       Flying away at an orful pathe,
       If no wun findth the poor liddle dears,
       Where will they be in a hundert ears?”
    “Rivets!” Sprockets said in alarm. “Have you lost your screw entirely?”
    “Well, it wymes, even if it’th abbled. And who’d care after a hundert ears—”
    Rivets’ voice had stopped suddenly. Sprockets waited a moment, then called in alarm: “Rivets! What’s happened?”
    There was no reply.
    Sprockets called again and again. He searched the black distance, but even with his special perceptors to help, there was no sign of Rivets.
    “Oh, dear,” he told himself. “Maybe a space gobbler got him.” But immediately he added: “How silly! There’s no such thing as a space gobbler. I shouldn’t have turned on my imagination button when I did. It’s made me space wabbled – I mean abbled – I mean addled. Suppose I really did have to float for a hundert ears! I’d be just plain cuckoo.”
    It occurred to Sprockets that it might be a good thing if he turned himself off. Not right away, of course, but in time. Then he could float and add and subtract – not ordinary numbers full of sevens and nines, but great positronic numbers full of fractured fractions.
    It seemed that he had been drifting in space for weeks and weeks, but when he checked his built-in clock he was surprised to find that only thirty-three minutes and seven seconds had passed since he had been blown from the air lock. The doctor is right, he thought. Time and space are so readily relative.
    At that moment he turned his head and saw the purple saucer.
    In seven more seconds it had paused directly over him, and Rivets had hauled him aboard through the force field.
    Sprockets blinked his eye lights at the doctor and Jim, who were sprawled on a bunk holding their heads. They looked, well, quite abbled.
    “What happened?” he asked Rivets.
    “Don’t ask me,” said Rivets. “It was something about being gobbled, but—”
    “Gobbled! By what?”
    “All I know, Sprockets, is that I was mighty glad to be back and have Leli fix my screw. Space is no place to be lost in with a loose screw. I almost lost it – and then the sheet caught on my radio button and turned it off, and, and – You just don’t know!”
    Sprockets said earnestly, “Be thankful you haven’t got an imagination button.” He turned to Leli and said, “You were gobbled by something?”
    “Yes,” Leli sang to him. “We were gobbled by a space gobbler.”
    “A space gobbler!”
    Leli gave a little trill of laughter. “That’s what we call it. Actually it’s a sort of magnetic wave. They don’t affect old-fashioned spaceships, but they can do the most unpurplish things to saucers. We’re always running into them – this one bounced us five million miles. It was loads of fun – we love space gobblers – but it was hard on the doctor and Jim. So we gave them jumping pills.”
    “You gave them – pills that jump?”
    “Oh, no, the pills don’t jump.” She laughed again. “Jumping pills cure jumping sickness. Some people get it when they take quick jumps in space.”
    “I’m purplishly thankful I’m only a robot,” Sprockets told her. “How did you find Rivets and me so easily?”
    “Why shouldn’t we find you easily? Our locator could always hear you ticking, even though we couldn’t get a message to you.”
    Dr. Bailey stood up and looked around vaguely. “Bless me,” he muttered. “I feel so duddy-fuddyish. Something happened – but what?”
    Sprockets told him.
    “Ump!” said the doctor. “I wouldn’t care to go through that again.”
    “It made me hungry,” said Jim, reaching into the lunch basket. “How long before we’ll be on Mars?”
    “Yes,” the doctor began. “How long—” But suddenly he stopped and stared hard at Rivets. “What – have – you – got – there?”
    “Space marbles, sir,” Rivets replied brightly. “Leli gave them to me. Aren’t they super?” He flipped one, and it shot exactly three feet into the air and hung there motionless, purple and glowing. He flipped another and another, until six purple marbles hung in front of him. “See, sir? They float – and they don’t roll away.”
    The doctor’s hair was bristling. “Quite super-super. But I don’t approve of marbles for robots – and – you – know – why!”
    “Aw, Daddy,” Jim pleaded. “They’re such super-super-super marbles! Why can’t he keep them – especially after the ghosty way he abbled the professor?”
    “Bless me, so he did. H’mm, very well, he may keep them – on probation only. But about Mars. How long—”
    “Sir,” said Sprockets, “Ilium informs me that since you are full of jumping pills, it will be safe for you to go faster now. You can make it in an easy jump of thirty minutes.”
    The doctor’s long nose began to twitch with rising excitement. “Hot diggity!” he cried suddenly. “Let us proceed!”
    Since time and space are readily relative, especially in a purple saucer, it seemed that they were flying over Mars in practically no time. It expanded so fast from a small red dot to a huge red globe, and there was so much to see on it, that time became timeless and didn’t count except on Sprockets’ built-in clock, which he didn’t have time to think about.
    The huge red globe, swelling every second as they rushed toward it, had gleaming white snow at the poles, with dried-up seas and great mottled red deserts ringed with mountains in between. And all over it, connecting everything and nothing, ran the strange straight lines of canals, perfectly huge canals that ran for hundreds of miles without a twitch. The canals were dry like the seas, but many of them were edged with green, as if plants were growing there.
    The doctor was so excited that his spectacles kept falling off, and Sprockets was forever jumping to catch them before they dropped. The doctor really needed a cup of sassafras tea to calm him, but Jim was too excited to think about it, though not too excited to keep his hand out of the lunch basket.
    “Bless me!” said the doctor. “There’s no question of it now. No question at all.”
    “Sir?” said Sprockets. “No question of what?”
    “Martians,” said the doctor. “Those canals didn’t dig themselves. A great civilization flourished here once.”
    “But, Daddy” – and Jim was puzzled – “where did the Martians live? I don’t see any cities – not even ruined ones. And I don’t see any rubble where ruins might have been.”
    “I’ll be doubly blessed!” The doctor replaced his spectacles, which Sprockets had caught for him again. “You’re quite right, which you seldom are. No ruins, no rubble, no roads, no nothing. Nothing except canals! I don’t understand it. Why were the canals built – and who built them? They must be ancient – audaciously so.”
    “Sir,” said Sprockets, “Ilium tells me they are older than ancient, and even older than that – which means they were audaciously ancient when Earth was young. He says Mars is a riddle that has never been unraveled, although the purple people have been flying over it for a million years.”
    “And it’s been like this for a million years?”
    “Exactly, sir. He says the only change is seasonal. Then the vapor comes down the canals, and the lichens turn green.”
    “Eh? Vapor, did you say?”
    “Vapor, sir. There’s practically no water on Mars, and very little air. So when the polar frost melts, it merely turns to vapor and drifts down the canals, and the lichens suck it up. Ilium says the lichenlike plants are the only things alive on Mars. Naturally he was quite flumdiddled when I told him Mars had a Something on it.”
    “Naturally,” said the doctor. “I’m quite flumdiddled myself. The whole thing is most flumdiddling. The way to unriddle the ravel is to find that Something and talk to it face to face. The question is where to begin. Ask Ilium to take us lower while I think deeply.”
    The saucer swooped down over the curious red landscape and began drifting along one of the canals.
    “H’mm!” said the doctor, peering out and thinking deeply. “H’mmmm!”
    “Daddy,” Jim began, “can’t we—”
    “Silence,” said the doctor. “I’m arriving at a conclusion.”
    Sprockets had turned on his cerebration button, and now he turned on his instinct button as well. The doctor, he knew, was fairly itching to go tramping on Martian soil. But his instinct button told him this would be most unwise.
    Before Sprockets could speak, the doctor said: “Ah! I’m certain those lichens are a clue. Being the only known things alive on Mars, they should be examined.”
    “And I want one for my collection,” Jim burst out. “Can’t we land, Daddy? Please, Daddy, can’t we?”
    “Naturally we must land,” said the doctor. His nose was quivering, and his mop of white hair was vibrating with expectation. “We must land, look, examine, think, and consult.”
    “Sir,” Sprockets began earnestly. “It is my duty to warn you that the surface of Mars is most inhospitable to humans, and that furthermore—”
    “Naturally it is inhospitable,” the doctor said impatiently. “It is icy and practically airless. But we will wear space suits. Tell Leli to get them for us.”
    “Yes, sir. But I must advise you that my positronic instinct, which is extremely sensitive, reacts alarmingly—”
    “Drivel!” snapped the doctor. “Preposterous positronic drivel! Turn it off, or I’ll turn you off. Can’t you see that I want to put my feet on Mars?”
    “Yes, sir!”

Chapter 6: They Search for the Something
    As the saucer moved to the edge of the canal, Leli gave everyone a little belt with a switch in the middle of the curling buckle. It was a simplified space suit, which she called a force globe. When the wearer pressed the switch, he was instantly surrounded by a bubble of protecting force that furnished both air and heat.
    “You and Rivets must wear them too,” she told Sprockets. “Mars has dust storms. Perfectly unpurplish awful ones. They come up in a wink before you know it. If you ever get Martian dust in your joints, you’ll never get rid of your squeaks.”
    The saucer came down and hung poised over an open spot nearly surrounded by the lichenlike plants. The plants looked very much like the lichens on Earth, all spreading and mottled with green, yet full of puckers and wrinkles. But there was a difference in size.
    “Whew!” Jim exclaimed, staring out at them. “I never saw lichens as big as bushes! We could get lost in them.”
    “Bless me,” said the doctor, “so we could. We must be careful to keep our radios on and not stray too far. Turn on your force globes, everybody!”
    Everyone pressed the switch on his belt, and was immediately surrounded by a shimmering bubble of force. Ilium thought a command to the saucer, and the slender stairway opened below them. Eagerly the doctor and Jim stepped through the saucer’s force field and hurried down to the dusty red ground.
    “Look!” cried Jim, jumping six feet upward with ease. “I weigh eighty pounds at home – and only thirty-two pounds here!”
    “Be careful where you jump,” Sprockets warned him over his radio. “And watch out for dust storms.”
    “Aw, Sprockets, you’re such a worrywart,” Jim called back. “You act as if Mars were full of rattlesnakes.”
    Rivets said: “What’s the matter, Sprockets? Is something wrong?”
    “You wouldn’t ask such a question if you had an instinct button.”
    “If it bothers you, why don’t you turn it off?”
    “I had to turn it off because the doctor ordered it – but it had already told me something was wrong, and I can’t figure out what it is. Got your pay-attention button on?”
    “All the way.”
    “Your hurry-up button?”
    “All the way.”
    “Then keep your marbles in your pocket – and your eye lights blinking.”
    “Aw, I think you’re still space-abbled. How could there be any danger here?”
    Sprockets didn’t know. Surely everything seemed all right. He watched Ilium and Leli, shimmering with color in their force globes, go bouncing away through the lichens like two happy children – which they were, as he knew. Being only a hundred years old, they were classed as young children by the purple people. He also knew that they were slightly radioactive, so he was not too surprised to see the lichens actually bend away as they moved through them.
    The doctor and Jim were not radioactive, and they had the opposite effect on the lichens. The lichens seemed to be reaching toward them.
    Sprockets thought, My goodness, what an odd thing for a plant to do! With his cerebration button on, it took only an instant to figure out the reason. Mars had so little air that these plants were positively greedy for it.
    Suddenly he cried out on his radio: “Don’t touch those lichens! They’re dangerous!”
    His warning came a second too late. The doctor, absorbed in his study of the curious plants, was reaching among them to find one small enough to pluck. Before he could draw back, a mottled leaf had enclosed his arm, and another lichen was folding itself around him, squeezing the force globe and sucking at the air. Jim saw him struggling and jumped to help – but the jump carried him much too far and the greedy lichens had a second victim.
    Sprockets was already racing across the open area with Rivets at his heels. Ilium and Leli, hearing Sprockets’ cries, came running back. In spite of the gravity, it took all four of them to tear Jim and the doctor free and drag them to safety.
    “Oof! Ug! Glup!” sputtered the doctor, gasping for breath.
    “G-great grief an’ M-moses!” Jim stuttered. “They nearly drained me dry!”
    “Almost tore off my force globe,” said the doctor, staggering to his feet. “Let’s get out of here!”
    Sprockets helped the doctor back into the saucer. It took three cups of sassafras tea to calm him, and Jim nearly emptied the lunch basket – though where he put it all Sprockets couldn’t guess.
    “Why weren’t the rest of you attacked?” the doctor asked Sprockets.
    “Sir, the rest of us have a touch of radioactivity, which the plants seem to abhor.”
    “Of course! That explains it. H’mm! Who would have dreamed that a plant could be so revoltingly ravenous for oxygen? Bless me, there’s a valuable clue here. Let me think.” He reached absently into the lunch basket, found a pickle that Jim didn’t want, and began to nibble it thoughtfully.
    “Daddy,” Jim began. “I’ve an idea.”
    “Don’t interrupt my thinking. There’s a conclusion trying to elude me.”
    “But, Daddy,” Jim persisted, “can’t you see? The lichens are growing where they are for a purpose.”
    “Eh? Purpose?”
    “Daddy, they are the only things alive on Mars, and they grow only near the canals. Couldn’t their purpose be to suck up all the vapor that drifts down to them?”
    “Naturally,” said the doctor. “Practically the conclusion I was almost arriving at. Proceed.”
    “Well,” said Jim, “since they are so grubbily greedy for oxygen, it would seem that their purpose is to store it up for something.”
    “Yes? Yes?”
    “Maybe for a Something,” said Jim.
    “H’mm! Ah, h’mmmm! Bless me, that could be it!”
    “Then, Daddy, why don’t we just fly around Mars, and look for places where the lichens have been picked? Maybe it will show us where the Something lives.”
    “Sometimes,” said Dr. Bailey, “you show signs of, ah, an almost tolerable mentality – as naturally you should, since I’m your father. Sprockets, ask Ilium to take us around the daylight side of the planet. We must look for a place where lichens have been picked. Everybody on his toes! Sing out immediately if you see anything unusually unusual.”
    Since Mars is only a middling planet, and the daylight half of it little wider than from here to there, relatively speaking – or no more than a quickish zip from New York to London – they were able to zip back and forth from the edge of night to the edge of dawn in a very short time.
    On the first four zips they saw nothing at all unusually unusual. On the fifth zip they saw a dust storm. It came up so fast, and spread over so much of the planet, and it was so thick and red and boiling, that searching for signs of a Something in it was impossible. There was nothing to do but zip around to the night side of Mars and wait till dawn.
    While they waited, Ilium and Leli taught Rivets how to play curious games with the floating space marbles. Jim wanted to play, but he couldn’t keep his hands out of the lunch basket. Dr. Bailey kept pacing the saucer, impatiently snapping his fingers.
    Finally Sprockets said, “Sir, it occurs to me that we might save time by trying to signal the Something.”
    “Eh? Signal it? How? Has the saucer a radio?”
    “Not one that we could use, sir. The saucer’s radio works by thought. But since we’re right here on Mars, I believe my special positronic hookup might be adequate – if I give it full power and send the proper signal.”
    “What kind of signal would you send?”
    “I believe, sir, I can best get the Something’s attention by repeating the message we heard over Jim’s do-jigger.”
    “Impossible! Those sounds would abble a tape recorder! How could you remember them?”
    “Sir, I remember the sounds perfectly. My difficulty will be to repeat them. If you’ll turn on your wrist radio and listen, I’ll make the attempt.”
    The doctor was suddenly all eagerness. “Attention, everybody! Turn on your radios – Sprockets is going to signal the Something!”
    Sprockets gave his radio button a double turn, adjusted his voice button, and raised his head. In a deep, grinding, rumbling – though slightly tinny – tone, he called: “Grullu-grullu-grulluwug! Hiddewoggo-hiddewoggo-buskrozor-r-r! Guwulluggowrozorkorohiddewoggobuskrozor-r-r-r-r-r-r!”
    He knew it wasn’t quite grinding enough, but he repeated it three times, and waited hopefully.
    A second passed. Suddenly there was a little hum, and from everyone’s radio poured a terrible voice. It was rumbling, deep, and grinding, and so awful to hear that Jim turned pale and put his fingers in his ears.
    When it was over, the doctor’s mop of white hair was standing straight up, stiff as a brush. “Heaven preserve us!” he whispered. “I’m not at all sure I care to meet the owner of that voice face to face.”
    “I’ll take the lichens,” Jim muttered. “Any time.”
    But Leli sang gaily to Sprockets: “Wasn’t it the most spectrumly wonderful thing to hear? We simply must get acquainted with this Something.”
    With much reluctance Dr. Bailey said, “Er, ah, were you able to get the direction of it, Sprockets?”
    “Yes, sir,” Sprockets replied, turning off his special perceptors and pointing out into the Martian night. “It is approximately three hundred and seven miles, six hundred and fifty feet to the southeast. Shall I tell Ilium to take us there, sir?”
    “Um, ah, well, I suppose so,” said the doctor.
    So the saucer zipped southeastward, where the Martian dawn was paling the horizon. Presently it stopped and hung poised on the slope of a great rounded red hill. Below the hill stretched a desert that might have been a sea bottom when Mars was young. One of the ancient canals ran straight through it. In the vague light everyone could see that the distant canal was dotted with lichens.
    “Bless me,” said the doctor. “What a lonesome spot! There’s nothing here! Are you sure this is the right place, Sprockets?”
    “Positive, sir.”
    Jim said: “But where could anything, even a Something, live around here? A Something has to live somewhere, if it’s only a cave.”
    “It is very puzzling,” Sprockets admitted, peering out. “I see neither a cave nor an opening in the hill. Perhaps, if I signaled again—”
    “Oh, no,” the doctor said quickly. “Don’t bother to bother. We’ll, er, look around a bit first.”
    Jim said, “I’m not putting foot outside till I know what Sprockets’ instinct button has to tell us.”
    Sprockets turned on his instinct button. “Wow!” he exclaimed. “There’s something around here – only it’s way down under us. It has to be the Something.”
    “Is – is it inhospitable to humans?” the doctor asked.
    “W-e-l-l, not exactly. I don’t feel any particular danger – at least at the moment.”
    Ilium and Leli had already snapped on their force globes and were hurrying eagerly out into the dawn to explore. The doctor peered uneasily at the hill, then his nose began to twitch. “Let’s get going!” he said.
    They turned on their force globes and followed Ilium and Leli outside.
    “At least,” said Jim, “there are no lichens here on the hill. But there’s nothing else, either. I don’t know what to look for.”
    At that moment Sprockets gave a little tock, and silently pointed at something on the smooth red rock ahead.
    It was a fragment of a lichen. It looked as if it had been cut by a mowing machine.
    “Jeepers!” came Jim’s whispered voice over the radio. “How did that get here?”
    Suddenly the voices of Ilium and Leli were singing in Sprockets’ receiver. “Something has been this way! It dropped pieces of lichen.”
    All at once the trail was plain. It led halfway up the hill, then stopped abruptly before a high, curving expanse of rock that blocked their way. Along the bottom of the rock were small pieces of dead and dried lichen. It was almost as if they had fallen from some conveyance going through a door.
    But there was no door here, not the faintest sign of a door. There was only the bare red rock of the hillside, scoured smooth by countless Martian dust storms.
    The doctor stared at the blank rock in front of him. “Sprockets, turn on your special perceptors. Maybe you can see something we can’t.”
    “I’ve already tried that, sir. All I can see is solid rock.”
    Then Sprockets heard Leli singing: “Isn’t this the most spectrumly clever way for a Something to hide his outer door?”
    “It’s most spectrumly flumdiddling,” Sprockets sang back. “How do you know this is his outer door?”
    “It just has to be. This isn’t the first Something we’ve investigated.”
    “But how—”
    “You have another button,” she said. “Why don’t you use it?”
    Sprockets remembered the special button on the side of his head that controlled his ultraviolet perceptors. It was so very special that he wasn’t supposed to touch it except under the most ultraspecial circumstances, and then for only a few seconds at a time.
    Certainly this was a most ultraspecial circumstance.
    Sprockets turned the button. Instantly he shone all over with a strange violet fire. Violet fires danced about his head and shot in blazing streaks from his eyes. He looked like a hot hobgoblin. The sight of him would have scared a stranger out of seven years’ growth. But Leli clapped her hands in delight and sang, “Oh, Sprockets, I didn’t know you could be so positively purplishly beautiful!”
    Sprockets hardly heard her. He was able to look right through the rock. It really was a door, though a most curious one, and it opened into a large room within the hill.

Chapter 7: They Enter a Door
    Sprockets turned off his very special button and slumped down before the rock, feeling a little limp. The problem facing him was enough to give any small robot a limpish feeling, and he doubted that he could solve it with all his buttons turned on full.
    The others crowded about him, questioning.
    “The entire rock is a door,” he answered, trying not to sound as baffled as he felt. “I was unable to detect any possible way it could be opened from the outside. It’s nine feet thick, and it must weigh thousands of tons – even here on Mars.”
    “Oh, dear me!” muttered the doctor, and slumped down beside him, shaking his head. “This is most unsettling.”
    “Aw, there must be a trick to it,” Jim said, approaching confidently. “Did you notice any locks?”
    “Neither locks nor hinges. It seems to slide inward in some manner strange to me,” said Sprockets.
    “Why don’t we try pushing it?” Jim suggested. “If it’s balanced right, its weight wouldn’t count.”
    Jim and Rivets tried pushing it in a dozen different places. The great rock refused to budge.
    “But if it’s a door, it’s got to open someway,” Jim said. “Sprockets, ask Ilium and Leli what they think.”
    Sprockets did, and answered dolefully: “Ilium says there are only four ways to open a door: by force, by key, by order, and by request. He says the first is most unpurplish and primitive, and that he doesn’t recommend it. And he says the second is quite old-fashioned, and that no intelligent Something would bother with it.”
    “That leaves only order and request. B-but grief and Moses, how do you go about ordering a door like this to open?” asked Jim.
    “Ilium says it can’t be done unless you have mastery over the door,” Sprockets answered.
    Jim slumped down beside his father. “If that’s the case, no one can order the door to open except the Something. Do we have to request the Something to open it for us? How about it, Daddy?”
    “Er, h’mm. Bless me, I’m afraid that’s the only solution.”
    “Sir,” said Sprockets, “shall I signal the Something and – and attempt to make known our, er—”
    “Oh, no!” said the doctor, giving a slight shudder. “Not right now. Let’s all consider the problem deeply.”
    “But, my goodness,” Rivets began. “I can’t see any problem. I’m not awful bright, but I know my manners. If a door is closed, and you want to enter, the proper thing to do is knock.”
    And Rivets strode up to the great stone door and knocked, very politely.
    Almost instantly, it opened. It slid soundlessly out of sight into the hillside, exposing a large cavelike space with another door at the farther end.
    Ilium and Leli clapped their hands in delight, and each took Rivets by an arm and ran inside. “Hurry!” they sang to Sprockets. “It will close in a moment.”
    Dr. Bailey was too astounded to protest when Sprockets caught his hand and drew him in after the others. Before the doctor could turn around and say, “Bless me,” the great stone door had closed behind him.
    “I declare,” muttered the doctor, peering about. The place was dimly lighted by a strange blue light that seemed to come from nowhere. “I – I declare!”
    “Daddy,” said Jim. “We’re in an air lock. I can hear air rushing in from somewhere. We’d better watch the other door.”
    The other door opened as they turned toward it, and everyone hurried through it. They were now in a bright blue circular room covered with curious designs. Directly in front of them were two broad passages sloping downward.
    The passage on the left was lighted by a deep red glow. The one on the right was a rich blue-green, the color of seawater.
    At the sight of the passages the doctor’s nose began to twitch, and his mop of hair began to flop with rising excitement. “Sprockets,” he ordered, “test the air and tell me if it is safe for humans.”
    “One moment, sir.” Sprockets turned off his force globe and adjusted his nose button. Air was something he did not need, but his nose button was extremely sensitive to it, and if it contained the wrong mixtures, he would have known it on the instant.
    “Sir,” he announced, “you will find the air safe, warm, and delicious. It contains a touch of ozone and a whiff of spring blossoms.”
    Everyone turned off his force globe and inhaled deeply. “My!” exclaimed the doctor. “This is positively super! I’m beginning to revise my opinion of the Something. He certainly does well for himself here. Now, let’s all consult and decide. We are faced with a color choice.”
    “Sir,” said Sprockets, “Ilium tells me they are most purplishly curious to explore the red passage, and they would like to take Rivets with them. I think, sir, the red color leads to machinery. With my special audios I can hear a faint hum coming from that direction.”
    “Can you hear anything from the green passage?”
    “Sir, there are several peculiar sounds coming from it. I seem to detect water running, and – and the singing of birds.”
    “Impossible!”
    “That’s what it sounds like, sir.”
    “Then, by all means, let us explore the green route, while our friends try the red one. But we must be very careful, and keep in constant touch by radio.”
    Sprockets watched Rivets trot happily away between Ilium and Leli. It worried him to be separated from his brother, although his instinct button gave no immediate indication of danger.
    Dr. Bailey, all eagerness now, was hurrying down the green passage as fast as his long legs could carry him. It sloped sharply and began to spiral, going down, down, down, like a winding stairway.
    “If we had roller skates,” said Jim, “this would be a lot easier. Say, I’m hungry!”
    Sprockets thought: How could he be? – but wisely said nothing.
    “I’m famished myself,” the doctor said presently. “Sprockets, where’s the lunch basket?”
    “In the saucer, sir.”
    “Great sniveling puppies! Why didn’t you bring it? Are you trying to starve us?” asked the doctor.
    “Sir, there was little left in it but three pickles and some chicken bones.” Sprockets glanced accusingly at Jim.
    Jim said: “I meant to make some new food with the saucer’s atomic transmuter. You know, you put a slice of cake or something in one slot, and a pebble in the other, and the pebble turns into more cake, or whatever you want. Only—”
    “Only what?” demanded the doctor. “If you had to be so piggy and eat everything, why didn’t you make some new lunch for the rest of us?”
    “Because I couldn’t find any pebbles! Honest, Daddy, I haven’t seen a pebble on Mars. This is the craziest place. Everything is ground down and worn smooth, and there’s nothing left but bare rock and dust. This planet must be awful old!”
    “I’m not interested in the age of the fourth planet! At the moment my only concern is food.” The doctor sat down, exhausted, for they had been hurrying for a half hour. The winding passage seemed endless. “How in the fuming thunderation,” he complained, “do you expect me to face the Something on an empty stomach?”
    “Sir,” said Sprockets, touching his nose button again, “I think I detect a faint aroma in the distance that might possibly come from something edible.”
    “Praise be!” muttered the doctor, springing to his feet, his exhaustion forgotten.
    It was fully a dozen spirals, however, before they reached the end of the winding passage. Here they stopped abruptly, and for a minute no one could utter a word.
    Before them opened what seemed to be another world. It had been morning outside – but here it was evening, with the setting sun shining through trees. There were birds singing overhead, and beyond them was a brook that came cascading down over mossy rocks to make a series of blue pools bordered with flowers. All the trees had curious leaves of different colors. Some of them were covered with large blossoms; others were heavy with fruit.
    The only living creatures in sight were the bright birds. They sang merrily away, and paid not the slighest attention to the visitors from Earth.
    “Incredible!” Dr. Bailey whispered finally. “I – just – don’t – believe – it!”
    “Sir,” said Sprockets, “my special vision tells me this isn’t real. We are in a cave that’s been carefully arranged to look real. I would deduce—”
    Jim gasped, “I betcha that fruit’s real!” He made a dash for the nearest tree with fruit on it.
    “Don’t eat that!” cried his father, as Jim stuffed something into his mouth. “You don’t know what it is!”
    “Sure I do. U’mmm – yummy! It’s a plapple.”
    “A what?”
    “A plapple, Daddy. It couldn’t be anything else. It’s neither plum nor apple, but it’s like both – only better. So it has to be a plapple. I’m starved!” He stuffed more fruit into his mouth, and moved eagerly to another tree.
    Sprockets blinked at him incredulously. “How can you – after what you’ve eaten? You’ll have the worst stomachache on Mars.”
    “Aw, it must be past suppertime at home,” Jim protested between bites. “And anyhow, I’m a growing boy. U’mmm! Daddy, you should try this kind. It’s a figanana.”
    “Er, you mean like a fig – and a banana?”
    “Yes. And it grows already peeled. Wow!”
    The doctor, with an uneasy glance around as if to assure himself that no Something was watching, was already reaching for a plapple. Presently he, too, was stuffing himself with plapples and figananas.
    It was not until they had finished, and Jim was wading in the brook, that the doctor remembered Ilium and Leli. “My word!” he exclaimed. “Are they all right? I can hear them singing over the radio, but I can’t understand—”
    “Sir,” said Sprockets, “they’ve just found out about the lichens. They’ve located a sort of automatic reaper – it flies out through the air lock, cuts lichens, and brings them to another machine. This other machine takes oxygen from the lichens, and a lot of chemicals that are used here – or were used here once.”
    “Eh? Once, did you say?”
    “Yes, sir. I told Ilium what we’d found, and he was quite excited – especially when I mentioned the make-believe sun and the robot birds.”
    “Robot birds!”
    “Yes, sir,” Sprockets replied solemnly. “All the birds are robot birds. I can tell that without even using my special perceptors. Ilium says it’s given him the answer to the riddle of the Martian canals, which have been puzzling the purple people for a million years.”
    “Yes? Yes? The answer to the riddle?” The doctor was suddenly trembling with excitement. “What is it, Sprockets?”
    “He did not tell me, sir. He said he was sure the answer would be evident when we had explored further.”
    “Then let’s get going!” the doctor cried impatiently. “What in the world are we waiting for?”
    “Your nap, sir. You always take a nap after eating.”
    “But I don’t want a nap!” the doctor burst out. “Don’t you realize how much exploring we have to do?”
    “Certainly, sir. Ilium says we must find the power source before we can find the Something, and that might take hours. It’s getting dark here, sir, and you’ve had a long, hard day – and it’s nearly Jim’s bedtime. I promised Mrs. Bailey I’d see that you both got your rest; she wants you to be wide-eyed and bushy-tailed before you ever get near that Something.”
    They were interrupted by Jim, who came running with a small object in his hand. It was a strange red-and-gold bird, cunningly made of metal. “Hey, Daddy, look! Did you know that these birds are robot birds?” he asked.
    “I’ve just been made aware of it,” said Dr. Bailey. “And I must caution you to put it back exactly were you found it.”
    “Aw, Daddy, I want it! Why can’t I keep it?”
    “Because it undoubtedly belongs to the Something. Bless me, I hope he doesn’t mind the fruit we took.” Dr. Bailey peered uneasily around, and rubbed his eyes when he realized that imitation stars were now glittering where the imitation sun had shone. The singing of the robot birds had quieted, and from them came only drowsy bell-like notes that made the doctor yawn.
    “Why, it’s night already,” he said. “And we didn’t bring a flashlight! I guess we’ll have to take our naps, after all. Keep guard, Sprockets. Wake me the instant you see or hear anything suspicious.”

Chapter 8: They Unravel Riddles
    Jim and his father picked a mound of soft, reddish grass under a tree, and lay down to rest. Presently the doctor’s long steady snores could be heard above the clatter of the brook. Jim didn’t snore, but he muttered and tossed – as naturally he would after eating so many plapples.
    Carefully Sprockets circled the glade. Though he discovered much that made him blink, he was relieved when his instinct button found none of it immediately worrisome. Finally he sat down to watch and wait.
    He wished the doctor hadn’t ordered him to keep guard, for this would have been a good time to recharge. Not that he needed it yet, but something told him that he might not have a chance to do it later.
    Over his radio he could hear Ilium and Leli singing. They were eagerly searching for the power source, which lay somewhere in a vast tangle of passages connecting dozens of curious workshops, all automatic. As time passed, Sprockets began to wonder if the purple people ever took naps. They seemed tireless, and skipped about so quickly, that Rivets had trouble keeping up with them.
    He was about to call Rivets, and ask if his battery was getting low, when his attention was taken by an odd sound in the distance.
    It was a very faint beep-beep-beep.
    For a moment he thought it might be one of the drowsy robot birds, far on the other side of the glade. The sound came again, louder and closer: Beep-beep-beep!
    Sprockets jumped up. Before he could call out or take a step, there was a low hum and whirring, and something unseen rushed below the hillock of trees beyond him. From it came a loud, angry Beep! B-e-e-p! B-E-E-P! Then, with a quick hum and whir, it was gone.
    The racket brought Jim and the doctor to their feet.
    Jim was instantly wide awake. “W-what in the walloping doodads was that?”
    “Great gracious!” muttered the doctor, still a bit foggy. “Who – what – why—”
    “I was unable to see it,” said Sprockets. “But something came and went, very loud and fast.”
    “Bless me! Could it have been the Something?”
    “It was a machine,” said Sprockets. “It hummed and whirred.”
    “And it beeped,” said Jim. “It nearly beeped me out of my skin.”
    “Then it couldn’t have been the Something. This will have to be investigated.”
    “I – I’m not investigating any Beeper,” Jim said uneasily. “At least not till I’ve had some breakfast. What time is it, Sprockets?”
    “As nearly as I can calculate,” Sprockets told him, “it’s seventeen minutes to six, underground Martian time. It’s no longer the same as Martian surface time – which naturally has changed through the years. The imitation sun will be up in fourteen minutes.”
    “Impossible!” exclaimed the doctor. “I’ve hardly slept a minute!” The doctor always said this, even after he had napped for hours. “How do you figure this, anyway?”
    “Quite simple, sir. The Martian day is nearly the same length as an Earth day. The imitation sun is made to rise and set exactly like the real sun, and its purpose is to make underground Mars look exactly like surface Mars – I mean, like the surface of Mars used to look.”
    “Eh? But why?”
    “I’m sure, sir, the reason will be evident as soon as we explore ahead. I’ve been talking to Ilium and Leli. They think they are nearing the power source, and they are very anxious to hear what we find.”
    Dr. Bailey was suddenly wide awake, his nose twitching eagerly. Hurriedly he plucked a handful of plapples, stuck one in his mouth, and started across the glade. Jim did likewise.
    The imitation sky was turning pale as they reached a flight of carved stone steps leading down to a path. The glade ended here. But the path and the underground world were just beginning.
    Before them stretched a long valley. The brook went tumbling through it, and was soon lost in groves of trees where robot birds were beginning to sing. On either side of the valley were hundreds of small houses, as bright as frosted cakes. They nestled into the hillsides, one above the other, all the way up to the sky – or what seemed to be the sky.
    Jim stared at it. “Great crickety crimble!” he whispered in an awed voice. “Now I get it. This is where the Martians came to live!”
    The doctor nodded. “Of course! They dug the canals when the seas dried up, and when the air was nearly gone, they came underground.”
    “B-but, Daddy, that was a long, long, long time ago. So long ago that time has rubbed out everything above us that used to be, except the canals. Why does everything down here look so bright and fresh and new? D’you s’pose the Martians are still living here?”
    As he spoke, the imitation sun peeped over the hill, and the valley suddenly awoke. Sprinklers came on, watering trees and flowers. Dozens of bottle-shaped machines scooted from openings under the houses and began scurrying about, planting, picking, mending, cleaning, painting, and putting things in order. All had six rubbery wheels, two pincherlike arms, and wiggling snouts that could do anything from root in the ground to spray fresh plastic on the houses. When they wanted to climb, they merely hummed mysteriously and rose into the air like bees.
    Other than the bottle-shaped workers, and the robot birds, there was no sign of life. Underground Mars seemed to be inhabited only by machines.
    “I’ll be blessed!” the doctor finally exclaimed. “Sprockets, call Ilium and Leli and tell them—”
    “I’m talking to Ilium now,” Sprockets said hastily. “They’ve discovered the power source. It’s a dilly!”
    Ilium, Leli, and Rivets were all talking at once. “There’s not another like it in the Galaxy,” Ilium was singing. And Rivets was exclaiming: “All red and huge. Must be a mile across, or anyway yards and yards and yards—” and Leli was adding: “A dozen passages meet here, all different colors – and we’ve found the one that leads to the Something! We want you to come here as quickly as you can. It will be much better if we call on the Something together.”
    Sprockets could feel his circuits tingling. “But how can we find you, Leli?”
    “Get on one of the conveyances – be sure it’s a red one – and it will bring you straight here.”
    “There are conveyances?”
    “Of course! Haven’t you seen one yet?”
    “Does it go beep-beep-beep?”
    “No, but we’ve heard something that does. The conveyances are little automatic cars that stop beside you and tinkle. They save a purplish lot of walking. Blue tinklers follow blue passages – red tinklers follow red. Hurry and catch a red tinkler. We are so glowingly, spectrumly excited we can hardly wait!”
    Sprockets turned quickly to the doctor. “Sir, Ilium and Leli are practically at the door of the Something, and they want us to join them immediately. Leli says that we can reach them easily by catching a red tinkler.”
    “And what is a red tinkler?”
    Sprockets hastily explained about tinklers. “We should find one down the valley, sir. They seem to be waiting by every passage.”
    “I’ll ride in anything that doesn’t beep,” said Jim.
    They hurried down into the valley, searching for a tinkler. One of the little bottle-shaped workers skittered respectfully out of their way, and went humming up the side of a house with a sponge in its wiggling snoot. No one saw the tinkler until it drew up beside them, its tiny bell tinkling invitingly.
    It was shaped like a long peapod, and made of shiny plastic like the houses. There were four seats in it. It floated a foot above the ground on nothing at all – probably, thought Sprockets, on an invisible power wave sent out from the power source.
    “Hey,” said Jim, “this tinkler’s black. We’re supposed to catch a red one – but I don’t see one anywhere.”
    “Maybe we’d better ride in this till we find a red one,” said the doctor. “It might save time.”
    Something told Sprockets that a black tinkler was definitely not the one they should take. But the doctor and Jim were already trying to wedge themselves aboard, and the tinkler was tinkling impatiently and beginning to move. Sprockets leaped inside, and the tinkler shot away so fast they were almost jerked from their narrow seats.
    “W-wow! W-where are we going?” Jim cried, as the houses streaked past in a blur and everything suddenly darkened around them.
    “We’re in a tunnel now,” Sprockets said uneasily. “A black tunnel. I think we’ve taken the wrong tinkler.”
    “We’ve got to stop it!” cried the doctor. “Quick, how do you stop it, Sprockets?”
    “You’re supposed to push a button in front of the seat,” said Sprockets. “But there’s no button here.”
    “T-there are no b-buttons anywhere!” Jim panted. “If we can’t stop it, we’d better jump!”
    “No!” cried Sprockets. “We’re going fifty miles an hour. Don’t you dare jump till I can slow it someway.”
    Sprockets’ metal fingers tore frantically at the strip of plastic under his feet. There must be wires, or possibly power tubes, somewhere in the tinkler that he could loosen.
    As he struggled he was aware of areas of color flashing past, and realized they must be lighted passages crossing their route. The strip of plastic began to bend. Suddenly it snapped. Sprockets called out: “Turn on your force globes! Get ready to jump when I slow it!” The force globes should help cushion their fall.
    His exploring hands touched metal. Instantly a horrid jolt went through him. Sparks flashed. Green fires danced around him, and his circuits began to heat so quickly that it was all he could do to gasp, “It’s slowing – jump as soon as you can—”
    A robot must protect his master even though it completely sizzles his circuits. Poor Sprockets knew he was bound to be sizzled in a matter of seconds, but he tightened his fingers and managed to hang on until he saw the doctor and Jim leap to safety. Then he blanked out.
    When Sprockets was able to blink his eye lights again, the tinkler had stopped and everything was still black around him. He wondered what had stopped the tinkler, and discovered that the piece of metal he’d been holding had finally come loose. And just in time, he thought, or a little robot named Sprockets Bailey would have been melted to an unrecognizable lump, right in the middle of black nowhere.
    He sat up weakly, and realized that the buttons he’d been using had automatically clicked off when his circuits started to sizzle. He turned on his radio button – and immediately flicked it off again with a yelp. “O-o-o-oh! My poor blistering circuits,” he moaned.
    It would be impossible to use any of his buttons until he cooled. Without the help of his buttons, matters could be difficult.
    But his positronic clock was still working, and he was surprised to find that only a half hour had passed since the doctor and Jim had leaped to safety. They couldn’t be too far away.
    Slowly, stiffly, he got out of the black tinkler and turned around, expecting to see only blackness ahead. Instead, the passage was clearly lighted with a soft green glow.
    Incredulously, Sprockets looked back in the direction the tinkler was pointed. There everything was black again. He jerked around and walked a few steps forward. He was astounded to discover that the passage was always black in one direction, and always green in the other.
    “My goodness!” he exclaimed, blinking worriedly. “Why must this be so confusing?”
    Without the help of his cerebration button, it took poor Sprockets’ overheated brain nine full seconds to figure out the reason for the reversible colors, which he decided all the passages must have. This was so you couldn’t get lost in the tangle of Martian passages. If you started out for a pink destination, the way would always be pink till you got there. If you had to return to a yellow place, the right direction would always be yellow.
    He could imagine all sorts of interesting places where the different colors might lead, but he refused to think about the black passage. Some things, he decided, are much better unthought.
    Thankful that he was not color-blind, Sprockets began trudging back toward the valley as fast as his aching legs could carry him. Each step sent a jolt through his quivering circuits, and he wished he could be safely home, so Mrs. Bailey could put an ice pack on his head.
    What could have happened to Jim and the doctor? There was no sign of them as far down the green passage as he could see. Presently he reached the first cross passage, and paused a moment to study it. It had a blue glow on the right, but the glow changed to red when he looked to the left. The power source itself was red – and Leli had said to take a red tinkler to reach it.
    Sprockets hesitated. Could the doctor have turned left here to search for Ilium and Leli?
    His hand crept to his radio button. “Turn it on,” he told himself. “Go on – you’ve just got to!”
    But he didn’t turn it on. A sudden sound in the distance made him stiffen with alarm.
    Beep! Beep-beep! Beep! B-e-e-e-p!
    The Beeper was coming straight toward him, fast.

Chapter 9: They Are Abbled and Plated
    Sprockets flattened against the wall of the black passage. The Beeper rushed humming up to the cross passageway, and stopped short with a questioning beep. It was a jointed beetlelike machine on ten rubbery wheels, larger than a tinkler. It looked extremely fierce with its single eye, and its wide upcurving scoop, like a snout in front.
    The eye turned this way and that, glaring. The scoop swung that way and this, as if horribly eager to scoop something. Sprockets remained motionless, not daring to budge a cog. He hoped the Beeper didn’t have hearing, for surely it would notice his ticking. Suddenly, with a loud whir, the Beeper spun around and looked back down the length of the green passage. It beeped angrily as if it had missed seeing and scooping whatever it was after, spun about again, and charged noisily past into the blackness.
    Instantly Sprockets darted around the corner into the red passage, and began to run. His circuits were cooler now, and he should have been able to run like a flash, but his feet dragged strangely and it was all he could do to trot. “Oh, dear me,” he said plaintively, “what can be wrong? My battery can’t be down already.”
    But it was his battery, and no question about it. The black tinkler must have drained it in some way. He would have thought the awful shock it gave him would have had the opposite effect. Maybe Martian power worked backward.
    He had only a minute or two left to find a safe spot where he could lie down and recharge. And there wasn’t a hiding place in sight.
    At that moment he heard the Beeper returning.
    “Oh, goodness, goodness,” Sprockets moaned, “I’m going to be scooped for sure this time. This is what happened to the doctor and Jim. They must have been scooped too.”
    Beeping furiously, the Beeper whirled around the corner into the red passage and rushed upon him, its scoop working eagerly. Sprockets tried to run. He could not. His dragging feet stumbled, and he fell against the side of the passage. His hands beat desperately against the hard stone as if he would somehow force an opening where there was none.
    Miraculously, a section of the stone wall slid aside, just as the rock door of the air lock had done when Rivets had knocked politely upon it.
    Sprockets tottered through the opening, too weak to feel any surprise. The section of stone slid quickly back in place, shutting out the angry beeping in the passage.
    Around him now was more noise, and a great deal of movement. Things hummed, whirled, clanged, and thumped. Other things hissed, buzzed, rang, and went ratty-tat-tat. Something snatched at him, and he was lifted up and carried away.
    Oh, mercy me! thought Sprockets. Out of the frying pan, into the fire....
    It was Sprockets’ last thought. There was a click as his battery shut off for recharging. His eye lights went out, and he knew nothing more for much too long an interval.
    Six hours, fifty-seven minutes, and twelve seconds later, which is the proper time for a robot’s atomic battery to recharge itself – unless he has had too many jellifying jolts, in which case it might take twice as long – there was a sudden click and Sprockets sat up, blinking his eye lights rapidly.
    His first thought was that he felt positively super.
    His second thought, which came instantly after the first, was that he had no business being in some kind of Martian repair shop, where a small buzzing machine was trying to polish him.
    His third thought, which came as he bounced to his feet and whirled away from the polishing machine, was that he must locate Dr. Bailey and Jim immediately.
    As he ran through the shop, he turned on his radio button and cried out: “Dr. Bailey! Dr. Bailey! Sprockets calling! Can you hear me, sir?”
    “Thank heaven!” came the doctor’s worried voice. “I was afraid the tinkler had done for you. What happened?”
    “The tinkler almost did for my battery, sir. I’ve just finished recharging, and now I’m trying to find my way out of a repair shop. Where are you, sir?”
    “I’ll be bottled if I know!” The doctor sounded completely flumdiddled and flummoxed, and slightly abbled. “I’m thoroughly and completely flumdiddled and flummoxed by bottles,” he announced, and Sprockets could picture his mop of white hair flopping wildly in all directions. “If I don’t get out of this dumdiddled be-bottled place, I’m going to be worse than abbled. That blankety-blankety bottle-brained Beeper—”
    “It nearly scooped us,” Jim interrupted. “But a door opened somewhere just in time, and we got in this crazy bottle place. I never saw so many bottles! Acres and acres of bottles, and nothing to eat or drink for hours, and I’m famished and starving. There’re bottles, bottles, bottles, bottles—”
    “Easy,” said Sprockets soothingly, as he dodged past rows of mechanical arms that seemed eager to grab him and do things to him. “Don’t let the bottles rattle you. Think calmly. There’s bound to be a door—”
    “There’s no door anywhere!” cried the doctor. “We’ve searched for hours! There’re nothing but bottles, bottles, bottles—”
    “Easy, sir,” Sprockets said soothingly again. “There’s bound to be a solution. Have you called Ilium and Leli?”
    “How can I?” the doctor fairly screamed. “I’m no mockingbird! And I can’t raise Rivets—”
    “I’m sure the Beeper got him,” said Jim, almost on the point of tears. “It’s been bottles and bottles – I mean hours and hours – since we’ve heard him. If we don’t get away from these b-b-bottles—”
    “Patience,” said Sprockets, looking in vain for a way out of the shop, which seemed to stretch endlessly without a sign of a door. “I’ll get you out. What color is your bottle place?”
    “Color!” the doctor yelled. “What in the tinkling, dinkling difference does the color make? I want out of here!”
    “Yes, sir! But the color is important, sir.”
    Jim said: “It’s a kind of icky-funny green-oh, I know it! It’s a bottle green, of course!”
    “Of course!” said Sprockets. “I’ll get you out as soon as I can find a bottle-green passage. Hold everything.”
    Sprockets adjusted his voice button and sang: “Ilium! Ilium! Sprockets calling! Where are you?”
    “Riding a blue tinkler, searching for you,” Ilium sang back. “We’ve been riding tinklers of every color, hunting everywhere. We’re most spectrumly happy to hear you. What in the purple pickle happened?”
    Sprockets told him, and asked, “Where’s Rivets?”
    “We’ve lost him,” Leli’s voice answered miserably. “We left him at the power source to recharge, and when we got back he was gone. I’m awfully afraid that stupid beeping thing got him. It hasn’t much sense—”
    “It’s a sort of scavenger,” said Ilium. “It goes around scooping up everything that doesn’t beep back at it. We saw it earlier with a black tinkler in its scoop—”
    “A black one!” Sprockets exclaimed.
    “Yes. It must have been the one you wrecked. I should have warned you about black. It’s a very bad color, everywhere in the Universe. We never take our saucer through the Black Nebulae. Have you located the doctor?”
    “I was just speaking to him. He and Jim are in a bottle-green storage place full of bottles. They’re getting bottle-abbled because they can’t get out. Do you know the secret of the doors?”
    “Yes, you knock – the way Rivets did. There are doors everywhere. You simply keep knocking along any wall, and a door will always open. Wait – we’ve reached a bottle-green passage. Leli thinks we should catch a bottle-colored tinkler here and hurry to the doctor.”
    “It will save time,” sang Leli. “You should be hunting for Rivets – aren’t you in a shop of some kind? I’m unpurplishly worried about him! If that horrid beeping thing took him to a salvage shop, why – why anything could happen to him!”
    “Sizzling smoke!” Sprockets burst out. “Rivets must be in here with me. I’d better find him fast!”
    Sprockets was so upset he forgot to call Dr. Bailey and tell him that Ilium and Leli were coming for him. He turned frantically, blinking at the endless rows of automatic machines where thousands of metal arms were buzzing and hissing about, reaching and jerking, and humming greedily as they pried things open and reduced them to pieces. In the distance he glimpsed something black being rapidly taken apart, and realized with a sudden awful tock that it was the black tinkler.
    There wasn’t the least doubt that poor Rivets was in here too – what was left of Rivets. Cogs and wires, and bulbs and bolts and buttons. It was only by the skin of his teeth that he, Sprockets Bailey, had been caught by a row of polishing machines, and thoroughly shined instead of dismembered.
    Dodging the reaching arms, Sprockets raced madly around, searching. Terrible minutes passed. All at once he stopped, staring at something bright in the area of the polishing machines. As he blinked at it, the bright thing moved, and suddenly sat up.
    “Rivets!” Sprockets cried, and ran to him.
    Rivets bounced away from the polishing machine, and stood blinking at him in astonishment.
    “Sprockets!” he gasped. “What’s happened to you?”
    “What’s happened to you?” Sprockets gasped back. “Rivets! You shine!”
    “So do you!”
    “Yes, but you’ve been silver-plated!”
    “But, Sprockets, you’ve been silver-plated too!”
    They gaped at each other incredulously. Then they looked down at themselves, blinking ninety to the second. There was no doubt about it. They’d both been silver-plated, every inch of them. Even their overalls had been given some kind of silver treatment, for they shone lustrously.
    “What will the doctor think of us now?” they both exclaimed together.
    “He ought to love us,” said Rivets, beginning to strut. “We’re so super-gorgeous. Wow! All silver!”
    “Stop your strutting,” Sprockets told him. “Being silver doesn’t get us out of a pickle. We don’t even know where we are.” He ran over to the nearest wall and began to knock, searching for a door.
    Rivets paid no attention to him. He was digging frantically in his pockets. “My marbles!” he wailed. “My beautiful space marbles – they’re gone!”
    “Forget the marbles – we’ve got to get out of here.” A section of the wall had opened into a doorway. Sprockets caught Rivets by the arm and pulled him into the passage beyond.
    It was a new passage that Sprockets had not seen before. To the left it had a bright yellow glow. On the right the glow changed to red. He was wondering if he could catch a red tinkler here when he remembered he had not told the doctor that Ilium and Leli were coming.
    Instantly he turned up his radio button. “Dr. Bailey! Dr. Bailey! Sprockets calling! Come in, please.” When there was no reply he called again, louder: “Dr. Bailey! Jim! Where are you?”
    In sudden alarm he adjusted his voice button and sang: “Ilium! Leli! Something’s wrong with the doctor! Ilium! Can you hear me?”
    But instead of Ilium replying, the voice that came over his radio was a deep, rumbling, grinding sound, terrible to hear:
    “Grullu-grullu-grulluwug! Hiddewoggo-hiddewoggo-buskrozor-r-r!”

Chapter 10: They Meet the Something
    Rivets clutched Sprockets’ arm and huddled closer in the passage. “Oh, goodness me!” Rivets whispered. “He sounded awful near. I – I wish I had my marbles.”
    “What for? You wouldn’t want the Something to catch you playing with marbles, would you?”
    “But they’re space marbles – and they’re such a comfort when your circuits are jangled. D-didn’t he jangle your circuits too?”
    “A – a little,” Sprockets admitted, blinking fearfully around and wishing he had something comforting to hang onto, even if it was only a space marble. Worriedly he called Ilium and Leli again, and was immensely relieved when Leli’s merry singing came over his radio.
    “Oh, Sprockets, wasn’t that the most spectrumly wonderful voice you ever heard?” she asked. “I’m sure the Something knows we are looking for him. If we can just find the doctor—”
    Ilium sang: “We’re in the bottle place. There’s no sign of anyone here – though they may be hidden somewhere. You found Rivets unharmed?”
    “He’s all right-but the doctor—”
    “I’m not all right,” Rivets sang plaintively. “I lost my marbles and I’ve got to get them back!”
    Leli gave a tinkle of laughter. “Don’t worry about your marbles, dear. I’m sure you’ll find them over at the power source where you were playing with them last. Sprockets, have you any idea what could have happened to Jim and his father?”
    Sprockets gave his cerebration button a quick turn, and deduced that only two things could be wrong. “Either they’ve been overcome by something in the bottles, or they’ve taken off their wrist radios and can’t hear us.”
    “But why would they take off their wrist radios?”
    “To put their hands in water. Earth people wash in it, and even drink it.”
    “Water!” Ilium and Leli exclaimed together. “Who ever heard of such a thing?”
    Sprockets knew the purple people drank only liquid purple, and bathed only in purple light. He still didn’t know whether they took naps or not, but this was no time to ask.
    “I abhor water myself,” he admitted, shuddering at the thought of what a rain had once done to him. “But Earth people need lots of it. If Jim and the doctor are not in the bottle place, I would deduce that they opened a door and went to the nearest water, for they were very hot and thirsty after being bottled up so long. The nearest water is outside in the brook where the plapple trees grow. Shall we come and help you find them?”
    “Oh, no!” Leli sang. “Catch a red tinkler and go straight to the power source and wait for us. We mustn’t upset the Something by any more delays. I know he’s wondering why we haven’t come to pay our respects.”
    A red tinkler had already appeared in the passageway, and was tinkling invitingly beside them. With some misgivings, Sprockets followed Rivets aboard, and the tinkler shot away into the red glow ahead.
    In only seconds the tinkler stopped. They got out. Sprockets stared in front of him, awed.
    They were at the entrance to an immense circular place that glowed with the deepest red Sprockets had ever seen. All around it stretched a walkway where a dozen passages opened, each of a different color. In the center of it all shone the power source.
    It seemed to be a great humming globe of flame, but as Sprockets blinked at it he realized it was a succession of fiery globes going downward, each a brighter red. He could look right down through them to a glittering white spot that may have been the very heart of Mars.
    “Great goodness alive!” Sprockets burst out. “How the doctor would love to see this!”
    But Rivets paid no attention to it. “My marbles!” he cried, running along the walkway and pointing. “My beautiful space marbles – they’re floating away!”
    And so they were. Sprockets saw them in the air, floating along the edge of the fiery globe. Some invisible current seemed to be drawing them around the circle.
    “You follow them to the right,” Sprockets said, “and I’ll go the other way. Maybe we can head them off.”
    Sprockets trotted to the left around the walkway. Soon the great globe hid Rivets and the floating marbles on the other side. Sprockets hurried, expecting to see them come into view any moment. But after he had run more than halfway around the circle, he could see neither Rivets nor the marbles.
    “Rivets!” he called. “Where’d you go?”
    “Down the white passage!” Rivets cried. “Something’s abbled my marbles – they won’t stop!”
    Sprockets gave a tock when he saw the white passage. It was brighter than all the others, and he didn’t need an imagination button to know what lay at the other end of it. His circuits began to quiver as he turned into it, and his cogs rattled as he heard Rivets cry out: “Hey – s-stop tickling me! Lemme go! Sprockets! Help! It’s got me!”
    Sprockets raced down the passage and stopped short in the entrance to a large dome-shaped room, every inch of which was covered with flashing buttons. In the center of the room gleamed a great oval shape, like a pearly egg, that seemed to pulse and glow as he blinked at it. From the pearly egg stretched a pearly tentacle, which held Rivets off the floor. Poor Rivets was motionless, and his eye lights were out. The space marbles were floating over his head.
    In spite of his rattling cogs, Sprockets did not hesitate. As quick as a flash he dashed bravely forward, trying to reach Rivets. But the pearly egg was quicker. It shot forth another tentacle, seized Sprockets securely, and lifted him wiggling into the air.
    Sprockets, held ten feet off the floor, and quite helpless, could think of only one thing to say. “Grullu-grullu-grulluwug!” he cried accusingly. “W-what have you done to my brother?”
    “Oh, grulluwug yourself,” came an impatient voice from the pearly shape – which had to be the Something because it couldn’t be anything else. “I merely plucked his brain – what there was of it. What’s wrong with that?”
    “You – you plucked his brain?” gasped Sprockets. “Oh, how awful! D-don’t tell me you’re going to pluck mine!”
    “Certainly I’m going to pluck it,” said the Something. “How else can I learn anything? Besides, it’s quite customary – and I’m a stickler for customs. Stop wiggling, or I’ll turn you off too.”
    An eye had formed in the pearly shape. Sprockets stared at it, and saw that the eye was staring back at him curiously. At the same moment another tentacle formed below the eye, and began reaching eagerly forward.
    “Oh – no – no – no!” poor Sprockets begged, squirming in the grip that held him securely. “P-please don’t pluck my brain yet! I’m only a little robot belonging to Dr. Bailey, and we came here with the best intentions—”
    “Best intentions! Ha – I doubt that. I know all about you – as naturally I would after plucking your brother’s brain. How else do you think I learned this horrid language you call English?”
    “I – I wondered,” Sprockets admitted, fearfully eyeing the tentacle that was poised over his head, ready to pluck all he had in it. “But you’ve no right to call it horrid. It’s much better than that awful grulluwug talk you use to frighten us with.”
    The tentacle holding him shook him, so that his cogs rattled. “I don’t use it to frighten anyone. I simply try to locate my people with it. It’s the finest language there is – my people spoke it millions of years before English was born.”
    “I – I didn’t know, sir,” Sprockets said meekly. “What happened to your people?”
    “It’s a sad story,” replied the pearly shape, casually extending another tentacle and turning on Rivets’ switch. Rivets blinked his eye lights, began to wiggle, and suddenly he saw his precious space marbles floating past his nose. He snatched them up quickly and stuffed them into a pocket.
    “Lemme down, you mean ole fing! Lemme down!” Rivets cried.
    “I will not!” snapped his captor, giving Rivets a shaking. “That’s no way for an ignorant little robot to talk to the Brain of Mars!”
    “Jeepers!” Rivets exclaimed. “Are you a weal bwain?”
    “I’m practically real. I’m fully positronic and plus!”
    “Then you’re just a robot like us,” said Sprockets.
    “I’ll have you know I’m not just a robot,” snapped the Brain, quite miffed. “I’m decidedly super, with nine miles of memory banks. It takes a lot to keep Mars running – but I’ve got it.” The Brain extended a few more tentacles and pressed some of the buttons that covered the circular wall. “There is no telling when my people may come back, so I must keep everything ready for them – the air freshened, the trees growing, the houses shined – Not that I mind the job. It’s quite simple. I do it all by Matics.”
    “Matics, sir?” said Sprockets, wondering desperately how he could escape and reach the doctor. “What’s Matics?”
    “Super mathematics. Doesn’t take figures or figuring. Matics gives you the answer to anything right now. Stop wiggling – there’s a custom to be observed. We must observe customs. It’s time to pluck – your – brain.”
    Before Sprockets could squeal, the hovering tentacle snapped down, and pressed firmly on the top of his head. Sparks buzzed, and Sprockets felt a slight sinking sensation.
    “There,” said the Brain. “Was that so bad?”
    “You – you plucked it?” Sprockets said weakly. “So quickly?”
    “Simple with Matics – and there wasn’t much to pluck. Only nine new languages – and none the equal of mine.”
    “Oh, Mr. Bwain,” Rivets begged, squirming, “lemme go, pleath!”
    “Absolutely not,” said the Brain, shaking him. “Your intentions are in doubt. I see no evidence of presents.”
    “P-presents, sir?” Sprockets was dumfounded.
    “That’s what I said. Presents. When a visitor has good intentions, he brings a present. It’s one of the oldest customs. Not that I have any use for presents – it’s the custom that matters. Customs are very important.”
    Oh, dear, thought Sprockets. None of us brought a present for him! What am I going to do?
    “Please, Mr. Brain,” he said, trying not to sound as desperate as he felt, “I’m sure presents will be arranged. B-but I must remind you that Dr. Bailey is quite absentminded. If – if you’ll pardon me while I call him—”
    “No,” said the Brain. “Now that I know the awful languages my visitors speak, I will call them myself. Kindly observe silence – or I’ll turn you both off!”
    A curious humming rose within the pearly shape, which Sprockets decided was the Brain speaking over his radio. While he hummed, the Brain amused himself by tossing Sprockets and Rivets back and forth and expertly catching them with his tentacles. It was horribly cog-rattling.
    Finally the humming stopped, and the Brain said: “Dr. Bailey and the others will be here in three minutes – without presents, I fear. This is most upsetting. I dislike having to send some visitors away on a black tinkler, but—”
    “Oh, no, no!” Sprockets cried, horrified. “You wouldn’t do that to us, would you?”
    “It’s an old custom. My people did it all the time. Must I repeat the importance of a custom?”
    Rivets, whose screw was very loose, said: “I fink some are nithe, but black tinklers make me worrit. What happened to your people, Mr. Bwain? Did you thend them off on black tinklers?”
    “Certainly not! When Mars dried up, they came underground. I did the best I could for them, with an imitation sun and all – but they were surface people, and after a while everyone flew off, looking for a better surface to live on. I don’t know where they went. I keep signaling, but they haven’t replied yet. Matics tell me they are bound to come back in time – they’ve been gone only three million years, and that’s practically no time at all. Still, I do get a bit lonesome now and then. That’s why I like visitors – visitors with presents. Ah, Dr. Bailey!”
    A white tinkler had appeared suddenly, and the doctor – without a sign of a present on him, and his mop of white hair in a wild tangle – climbed unsteadily out. Jim followed, as wide-eyed and worried as his father; then came Ilium and Leli, looking as upset as Sprockets had ever seen them. No one had a present.
    Jim and the doctor gaped incredulously upward at Sprockets and Rivets. “I declare!” muttered the doctor. “What are the two of you doing up there?”
    “W-we’re hostages, for presents, sir. Don’t be alarmed, sir, while Mr. Brain plucks your brains,” Sprockets said.
    Jim stammered, “P-p-plucks our brains!”
    “Certainly,” said the Brain. “It’s quite customary. Hold still, please.”
    “It dothn’t hurt,” said Rivets, “but it tickles.”
    Four pearly tentacles reached out and touched four very worried and uncertain heads. “Fairly super,” the Brain commented, speaking English one moment, then switching over as smooth as butter into the purple language. “I believe I could enjoy a visit with you – if a final custom can be observed. It’s very important. I would deeply regret having to send you away on black tinklers.”
    “B-b-black tinklers!” Jim gasped. “Oh, no!”
    “Yes,” said the Brain. “It’s a custom I’m forced to observe – unless you all brought presents. Did you?”
    “B-bless me,” Dr. Bailey began, running an unsteady hand through his hair, as if he would somehow loosen a present in the tangle. “It’s, ah, this way. Er, Sprockets, can you possibly, er—”
    It was a horrible moment, and poor Sprockets, ten feet up in the air and hardly able to wiggle, was trying desperately to think of an idea. He was on the point of offering himself as a present, when Rivets spoke.
    “Oh, Mr. Bwain,” said Rivets. “Of course we bwought pwethenth! There’s a weal nice wun from each of uth. They are the motht wonnerful mobbles in the Univerthe!”
    Rivets held out his precious set of floating space marbles.
    Instantly the Brain encircled the floating marbles with a tentacle, and began flipping them experimentally from one tentacle to another. Suddenly he set Sprockets and Rivets carefully on the floor, and began spinning the glowing marbles in squares and circles overhead. “My!” he exclaimed, brightening all over. “These are the finest presents I’ve had since my people left. They are positively super-plus!”
    From that moment on, everything was quite all right. Leli hugged Rivets, and told him how gorgeous he was with his new silver plating. Everyone began talking at once, and the Brain played happily with his space marbles while he pushed buttons and explained how he ran underground Mars. The doctor had a deep discussion with him on Matics, and when they were ready to leave the Brain presented each of them with a singing robot bird, brought in by a small tinkler, and made them promise to visit him again.
    They rode two green tinklers back to the glade where the brook began; but since this was the end of the line, they had to climb the rest of the distance to the air lock, which was most exhausting. Aboard the purple saucer, the doctor was happy to discover that the thermos bottle still held one cup of sassafras tea, which he needed badly. Afterward he and Jim took jumping pills, and the purple saucer jumped them home in thirty minutes.
    Mrs. Bailey could hardly believe her eyes when she saw the robot birds and Sprockets and Rivets with their new silver plating. “Why, you’re too gleamily gorgeous for words!” she told them. “You’ll have to carry silver polish with you all the time and keep yourselves properly shined. Barnabas, how did they behave?”
    “Tolerable,” said the doctor. “Quite tolerable.” Which meant super-super.
    “Always gadding about in purple saucers,” said Mrs. Bailey. “I suppose next you’ll be gadding to some outlandish place like the purple planet.”
    “Naturally,” said the doctor. “The sooner, the better. I’m anxious to acquire a set of purple space marbles.”
    “Space marbles! What on earth for?”
    “To repay a debt,” said the doctor. “And you’d better pack an extra big lunch this time. I understand it’s quite a jump.”

    1964

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