Transcriber's Note:

 This etext was produced from Astounding Stories April 1932. Extensive research did not uncover any evidence that the U. S. Copyright on this publication was renewed. 

 [Illustration: "_Once more! Will you give me the recognition signal?"_]

 The Great Dome on Mercury

 By Arthur L. Zagat

 * * * * *

[Sidenote: Trapped in the great dome, Darl valiantly defends Earth'soutpost against the bird-man of Mars and his horde of pigmy henchmen. ]

Darl Thomas mopped the streams of perspiration from his bronzed faceand lean-flanked, wiry body, nude save for clinging shorts and fibersandals. "By the whirling rings of Saturn, " he growled as he gazeddisconsolately at his paper-strewn desk. "I'd like to have thosedirectors of ITA here on Mercury for just one Earth-month. I'll betthey wouldn't be so particular about their quarterly reports afterthey'd sweated a half-ton or so of fat off their greasy bellies. 'Fuel consumption per man-hour. ': Now what in blazes does that mean?Hey, Jim!" He swiveled his chair around to the serried bank ofgauge-dials that was Jim Holcomb's especial charge, then sprang to hisfeet with a startled, "What's the matter?"

The chunky, red-haired control-man was tugging at a lever, his musclesbulging on arms and back, his face white-drawn and tense. "Look!" hegrunted, and jerked a grim jaw at one of the dials. The long needlewas moving rapidly to the right. "I can't hold the air pressure!"

"Wow, what a leak!" Darl started forward. "How's it below, in themine?"

"Normal. It's the Dome air that's going!"

"Shoot on the smoke and I'll spot the hole. Quick, man!"

"Okay!"

Thomas' long legs shot him out of the headquarters tent. Just beyondthe entrance flap was one of the two gyrocopters used for flyingwithin the Dome. He leaped into the cockpit and drove home thestarter-piston. The flier buzzed straight up, shooting for the mistedroof. 

 * * * * *

The Earthman fought to steady his craft against the hurricane wind, while his gray eyes swept the three-mile circle of the vault's base. He paled as he noted the fierce speed with which the white smoke-jetswere being torn from the pipe provided for just such emergencies. Hisglance followed the terrific rush of the vapor. Big as a man's head, ahole glared high up on the Dome's inner surface. Feathered wisps oftell-tale vapor whisked through it at blurring speed. 

"God, but the air's going fast, " Darl groaned. The accident he hadfeared through all the months he had captained Earth's outpost onMercury had come at last. The Dome's shell was pierced! A half-milehigh, a mile across its circling base, the great inverted bowl was allthat made it possible for man to defy the white hell of Mercury'ssurface. Outside was an airless vacuum, a waste quivering under theheat of a sun thrice the size it appears from Earth. The silveredexterior of the hemisphere shot back the terrific blaze; itsquartz-covered network of latticed steel inclosed the air that allbeings need to sustain life. 

Darl tugged desperately at the control-stick, thrust the throttle overfull measure. A little more of this swift outrush and the precious airwould be gone. He caught a glimpse of the Dome floor beneath him andthe shaft-door that gave entrance to the mine below. Down there, inunderground tunnels whose steel-armored end-walls continued the Dome'sprotection below the surface, a horde of friendly Venusians werelaboring. If the leak were not stopped in a few minutes that shaftdoor would blow in, and the mine air would whisk through the hole inits turn. Only the Dome would remain, a vast, rounded sepulcher, hiding beneath its curve the dead bodies of three Earthmen and thesilent forms of their Venusian charges. 

 * * * * *

Darl's great chest labored as he strove to reach the danger spot. Invisible fingers seemed to be clamped about his throat. His eyesblurred. The gyrocopter was sluggish, dipped alarmingly when it shouldhave darted, arrow-like, to its mark. With clenched teeth, theTerrestrian forced the whirling lifting vanes to the limit of theirpower. They bit into the fast thinning air with a muffled whine, raised the ship by feet that should have been yards. 

By sheer will he forced his oxygen-starved faculties to function, andrealized that he had reached the wall. He was drifting downward, thehole draining the Dome's air was five feet above him, beyond hisreach. The driven vanes were powerless to stem the craft's fall. 

One wing-tip scraped interlaced steel, a horizontal girder, part ofthe vault's mighty skeleton. Darl crawled along the wing, draggingwith him a sheet of flexible quartzite. The metal foil sagged underhim and slanted downward, trying like some animate thing to rid itselfof the unwonted burden. He clutched the beam, hung by one leg and onearm as his craft slid out from beneath him. The void below dragged athim. He put forth a last tremendous spurt of effort. 

Two thousand feet below, Jim Holcomb, dizzy and gasping, manipulatedthe controls frenziedly, his eyes fastened on the droppingpressure-gauge. From somewhere outside the tent a dull thud sounded. "Crashed! Darl's crashed! It's all over!" Hope gone, only the instinctof duty held him to his post. But the gauge needle quivered, ceasedits steady fall and began a slow rise. Jim stared uncomprehendingly atthe dial, then, as the fact seeped in, staggered to the entrance. "That's better, a lot better, " he exclaimed. "But, damn it, what wasthat crash?"

 * * * * *

The headquarters tent was at one edge of the circular plain. Jim'sbleary eyes followed the springing arch of a vertical girder, up andup, to where it curved inward to the space ship landing lock that hungsuspended from the center of the vaulted roof. Within that bulge, atthe very apex, was the little conning-tower, with its peri-telescope, its arsenal of ray-guns and its huge beam-thrower that was the Dome'sonly means of defense against an attack from space. Jim's gazeflickered down again, wandered across the brown plain, past the longrows of canvas barracks and the derrick-like shaft-head. Hard by thefurther wall a crumpled white heap lay huddled. 

"My God! It was his plane!" The burly Earthman sobbed as his ten-footleaps carried him toward the wreck. 

Darl was his friend as well as Chief, and together they had served theInterplanetary Trading Association, ITA, for years, working andfighting together in the wilds of the outer worlds. A thought struckhim, even as he ran. "What in th' name o' Jupiter's nine moons stoppedth' leak?" He glanced up, halted, his mouth open in amazement. "Well, I'm a four-tailed, horn-headed Plutonian if there ain't th' boyhimself!"

Far up in the interlaced steel of the framework, so high that to hisstaring comrade he seemed a naked doll, Darl stood outstretched on alevel beam, his tiny arms holding a minute square against the wall. Lucky it was that he was so tall and his arms so long. For the savingplate just lapped the upper rim of the hole, and stemmed the fiercecurrent by only a half-inch margin. 

 * * * * *

The throbbing atmosphere machine in the sub-surface engine-room wasreplacing the lost air rapidly, and now the increasing pressure wasstrong enough to hold the translucent sheet against the wall by itsown force. Jim saw the extended arms drop away. The manikin waved downto him, then turned to the shell again, as if to examine the emergencyrepair. For a moment Darl stood thus, then he was running along thegirder, was climbing, ape-like, along a latticed beam that curved upand in, to swing down and merge with the bulge of the air-lock'swall. 

"Like a bloomin' monkey! Can't he wait till I get him down with th'spare plane?"

But Darl wasn't thinking of coming down. Something he had seen throughthe translucent repair sheet was sending him to the look-out towerwithin the air-lock. Hand over hand he swung, tiny above that vastimmensity of space. In his forehead a pulse still jumped as his hearthurried new oxygen to thirsty cells. He held his gaze steadily to theroof. A moment's vertigo, a grip missed by the sixteenth of an inch, the slightest failure in the perfect team-play of eye and brain, andrippling muscle, and he would crash, a half mile beneath, against hardrock. 

At last he reached the curving side of the landing lock. But theplatform at the manhole entrance jutted diagonally below him, fifteenfeet down and twelve along the bellying curve. Darl measured the anglewith a glance as he hung outstretched, then his body became a humanpendulum over the sheer void. Back and forth, back and forth he swung, then, suddenly, his grasp loosened and a white arc flashed through theair. 

Breathless, Jim saw the far-off figure flick across the chasm towardthe jutting platform. He saw Darl strike its edge, bit his lip as hisfriend teetered on the rim and swayed slowly outward. Then Darl foundhis balance. An imperative gesture sent the watcher back to his post, his sorrel-topped head shaking slowly in wonderment. 

 * * * * *

Darl Thomas ran headlong up the staircase that spiralled through thedim cavern. "No mistake about it, " he muttered. "I saw somethingmoving outside that hole. Two little leaks before, and now this bigone. There's something a lot off-color going on around here. "

Quickly he reached the little room at the summit. He flung the canvascover from the peri-telescope screen. Tempered by filters as it wasthe blaze of light from outside hit him like a physical blow. Headjusted the aperture and beat eagerly over the view-table. 

Vacation jaunts and travel view-casts have made the moon's landscapefamiliar to all. Very similar was the scene Darl scanned, save thatthe barren expanse, pitted and scarred like Luna's, glowed almostliquid under the beating flame of a giant sun that flared in a blacksky. Soundless, airless, lifeless, the tumbled plain stretched to ajagged horizon. 

The Earthman depressed the instrument's eye, and the silvered outsideof the Dome, aflame with intolerable light, swept on to the screendisk. The great mirror seemed alive with radiant heat as it shot backthe sun's withering darts. The torrid temperature of the oven within, unendurable save to such veterans of the far planets as Darl and JimHolcomb, was conveyed to it through the ground itself. The direct raysof the sun, nearer by fifty million miles than it is to Earth, wouldhave blasted them, unprotected, to flaked carbon in an eye-blink. 

An exclamation burst from Darl. A half-inch from the Dome's blazingarc, a hundred yards in actuality, the screen showed a black fleck, moving across the waste! Darl quickly threw in the full-power lens, and the image leaped life-size across the table. The black fleck wasthe shadow of a space-suited figure that lumbered slowly through theviscous, clinging footing. How came this living form, clad in gleamingsilver, out there in that blast-furnace heat? In one of the spacesuit's claw-like hands a tube flashed greenly. 

 * * * * *

Darl's hand shot out to the trigger of the beam-thrower. Aimed by thetelescope's adjustment, the ray that could disintegrate a giant spaceflier utterly flared out at his finger's pressure. Against the lambentbrown a spot glowed red where the beam struck. But, warned by someuncanny prescience, the trespasser leaped aside in the instant betweenThomas' thought and act. Before Darl could aim and fire again the foehad dodged back and was protected by the curve of the Dome itself. 

Two white spots showed on either side of Darl's nostrils. His mouthwas a thin white slit, his eyes gray marbles. Standing against thewall beside him was a space suit, mirror-surfaced and double-walledagainst the planet's heat. In a few moments he was encased within it, had snatched a pocket ray-gun from the long rack, and was through thedoor to the auxiliary air-lock. The air soughed out in response to hisswift thrust at a lever, a second door opened, and he was on theoutside, reeling from the blast of that inferno of light and heat. 

For a moment the Earthman was dazzled, despite the smoked quartzeye-pieces in his helmet. Then, as his eyes grew used to the glare, hesaw, far below, the erect figure of the stranger. The man was standingstill, waiting. His immobility, the calm confidence with which hestood there, was insolently challenging. Darl's rage flared higher atthe sight. 

 * * * * *

Scorning the ladder that curved along the Dome to the ground, he threwhimself at the polished round side of the great hemisphere. Withincreasing speed he slid downward, the gleaming surface breaking onlyslightly the velocity of his fall. On Earth this would have beensuicidal. Even here, where the pull of gravity was so much less, thefeat was insanely reckless. But the heat-softened ground, the strengthof his metal suit, brought Darl safely through. 

He whirled to meet the expected onslaught of the interloper. The greentube was aimed straight at him! The Earthman started to bring his ownweapon up when something exploded in his brain. There was a moment ofblackness; then he was again clear-minded. But he could not move--notso much as the tiny twist of his wrist that would have brought his ownweapon into play. 

Frozen by this strange paralysis, Darl Thomas saw the giant figureapproach. The apparition bent and slung him to its shoulder. Glowingwalls rose about him, dimmed. The Terrestrian knew that he was beingcarried down into one of the myriad openings that honeycombed theterrain. The luminescence died; there was no longer light enough topenetrate to his helmet's darkened goggles. 

Frantic questions surged through the captured Earthman's mind. Who washis captor? From where, and how, had he come to Mercury? Jim, AngusMcDermott, and himself were the only Terrestrians on the planet; ofthat he was certain. Only one or two of the reptile-skinned Venusianlaborers had sufficient intelligence to manipulate a space suit, andthey were unquestionably loyal. 

This individual was a giant who towered far above Darl's own six feet. The Mercurian natives--he had seen them when ITA's expedition hadcleaned out the burrows beneath the Dome and sealed them up--weremidgets, the tallest not more than two feet in height. Whatever hewas, why was the stranger trying to destroy the Dome? ApparentlyThomas himself was not to be killed offhand: the jolting journey wascontinuing interminably. With enforced patience the Earthman resignedhimself to wait for the next scene in this strange drama. 

 * * * * *

In the headquarters tent Jim's usual grin was absent as he movedrestlessly among the switches and levers that concentrated control ofall the Dome's complex machinery. "Darl's been gone a devilish longtime, " he muttered to himself. "Here it's almost time for shifts tochange and he's not back yet. "

A bell clanged, somewhere up in the mass of cables that rose from thecontrol board. For the next ten minutes Holcomb had no time for worryas he rapidly manipulated the innumerable wheels and handles in accordwith the vari-colored lights that flickered on a huge ground-glass mapof the sub-Mercurian passages. On the plain outside there was a vastrustling, a many-voiced twittering and squeaking that was not quitebird-like in tone. Through the opened tent-flap one could see thestream of Venusian workers, their work-period ended, pouring out ofthe shaft-head and filing between the ordered ranks of others whoselabors were about to begin. 

They were queer-looking specimens, these gentle, willing allies of theEarthmen. Their home planet is a place of ever-clouded skies andconstant torrential rains. And so the Venusians were amphibians, web-footed, fish-faced, their skin a green covering of horny scalesthat shed water and turned the sharp thorns of their native jungles. When intrepid explorers discovered in the mazes of Mercury's spongyinterior the _surta_ that was so badly needed as a base material forsynthetic food to supply Earth's famine-threatened population, it wasto these loyal and amiable beings that ITA's engineers turned forworkers who could endure the stifling heat of the undergroundworkings. 

The tent-flap was thrust aside, and a hawk-nosed Scot came sleepilyin, to be enthusiastically greeted by Jim. 

"Hello, you old Caledonian. 'Bout time you showed up. "

 * * * * *

The newcomer fixed the speaker with a dour gaze. "An' why should Icommence my tour o' dooty befair the time?"

"Because your chief, Mr. Darl Thomas, decided that he's a filliloobird or somethin', flew to his little nest up top, an' forgot to comedown again. "

"Is this ain o' your jests, James Holcomb? I eenquire mairly that Imay ken when to laugh. "

"It's no joke, Mac. Last I see o' him he's skippin' around the rooflike he has a buzzin' propeller stuck to his shoulder blades. Helights on th' air-lock platform, pops inside, an' goes dead for all Iknow. "

From his bony legs to his scrawny neck the Scotchman's angular body, as nearly nude as that of the others, radiated the doubt that wasexpressed in every seam and wrinkle of his hatchet face. 

"That's straight, Angus, may I kiss a pink-eared _vanta_ if it ain't. Here's what happened. " The bantering grin disappeared from Jim'scountenance as he detailed the events that had preceded Darl'svanishing. "That was two hours ago, " he concluded, "and I've beengetting pretty uneasy about him. "

"Why did na ye call me, so that ain o' us micht eenvestigate?"

"Hell. Darl wasn't born yesterday, he can take care of himself. Besides, your last shift was pretty strenuous, an' I thought I'd letyou sleep. No tellin' what might happen next; this forsaken place hasbeen givin' me the jim-jams lately. "

"Your conseederation is touching, but--" A scratching at the door, accompanied by a high squeak, interrupted him. 

 * * * * *

To Jim's shouted "Come in, " there entered a Venusian, whose redrosette fastened to the green scales of his skin marked him anoverseer. In the thread-like fingers of his hand he held a time-sheet, but the nervous pulsing of his gill-membranes caused Holcomb toexclaim anxiously: "What's wrong, Ran-los? No accident, I hope?"

The shrill combination of squeaks and twitterings that came from theman-reptile's toothless mouth meant nothing to the Scot, but Jim'slast service had been on Venus and he had gained a working knowledgeof the language. Finally the interchange was ended, and Ran-los bowedhimself out. Jim turned to his companion. 

"There's some more queer stuff for you, Angie. Just beforeshift-change, Ran-los heard odd sounds from the other side of thebarrier at the end of gallery M-39. Says they seemed like signals o'some kind. He's a wise old bird and if he's worried about somethingit's damn well worth lookin' into. I don't know whether to find outfirst what's happened to Darl, or--"

Again there was an interruption; this time from the usually silentradio-communication set in the far corner. Jim leaped to theinstrument and snapped on the head-set. Angus leaned over him, watching his intent face. 

Faintly, as from an immense distance, came the thin whistle ofspace-radio. "S-W-A . . . S-W-A . . . S-W-A. . . . " The general attentionsignal for all Earth's far-flung outposts from Jupiter to Mercury! Thesignal was coming from "M-I-T-A, " the Earth company's home station onthe Moon, outside the Heaviside layer. "S-W-A . . . S-W-A . . . M-I-T-A . . . M-I-T-A. " Again the signal rose and fell. 

 * * * * *

Jim reached for the sending key and pounded out his acknowledgement:"K; M-E-R . . . K; M-E-R . . . K; M-E-R. " He listened again, heard Venusanswer, and Jupiter. Across five hundred million miles of space ITAmen were responding to the roll-call of Earth. A reminiscent smilecrossed Jim's face as he recognized the stuttering fist of RadePerrin, on Eros. Rade always sent as if he were afraid the instrumentwould snap at his fingers. 

M-I-T-A was signalling again, and now came the message: "S-W-A. Alltrading posts, mines and colonies are warned to prepare for possibleattack. The Earth Government has just announced the receipt of anultimatum from--" A raucous howl cut across the message and drowned itout. The siren blast howled on and on, mocking Jim's straining ears. "Well I'll be--Interference! Deliberate blanketing! The rats! The--"He blazed into a torrent of profanity whose imaginativeness wasmatched only by its virulence. 

Mac was clutching his shoulder, stirred for once out of his vaunted"deegnity. " "What is it, mon, what is it?"

"War, you bloody Scotchman, war! That's what it is!"

"War! Foosh, man, 'tis eempossible!"

"The hell it's impossible! Damn, and Darl not here! Take over, Mac;I've got to go up an' get him!"

 * * * * *

In the meantime Thomas' helpless journey had come to an end. After aninterminable descent in what to him had been pitch darkness, the giantwho was carrying him halted. Darl had heard the whistling inrush ofair into some lock, then the clanging of a door. He felt himselfhurled to the ground. Fumbling hands tugged at him, drew off his spacesuit. 

The dim light of the cavern, as the helmet was dragged from his head, hurt Darl's eyes. Salt sweat stung them. It was hot, hotter than theDome, hot as it was in the surta mine, where only the nervelessVenusians could work for any length of time. 

Darl struggled to focus his eyes on a blurred blue form that toweredabove him. He felt sharp claws scratch at him and realized that cordswere being passed around his limp body. They cut tightly into his legsand his arms. Then he was staring at a tube in the hand of his captor. Its end glowed with a brilliant purple light, and he felt a flood ofreawakened energy warm him. His head jerked up, he strained againstthe taut, strong fibers binding him. The paralysis was gone, but hewas still helpless. 

A husky, rumbling voice broke the silence. "I wouldn't struggle, Earthman, if I were you. Even should you get free I still have myray-tube. And my little friends would ask nothing better than yourbody to play with. "

Darl writhed to a sitting posture. Now he could see his mysteriousabductor clearly. This eight-foot, blue-feathered individual, withcurved beak and beady eyes glittering from his naked, repulsivelywrinkled head, was a Martian! Despite the human shape of his body, despite his jointed limbs and thumbed hands, this denizen of the redplanet resembled a vulture far more than he did any other Earthcreature. 

 * * * * *

The Earthman's pride of race came to his rescue. "What's the game?" hegrowled. "Looking for trouble?" There was nothing in Darl's voice toshow the fear that chilled him. Behind the Martian he could seevaguely a group of little yellow Mercurians. 

"I'll ask all the questions here. And you'll answer them, too, ifyou're wise. Even your dull mind should comprehend that you are in mypower. "

Darl decided to proceed more cautiously. "What do you want from me?"he asked. 

"I want, " the Martian answered, "the recognition signal of Earth'sspace-ships. "

"What!" The ejaculation burst from Darl's throat. This alien wantedthe secret code, the watch-word that distinguished Earth's spaceships, that gained for them free admittance to ITA's armed posts onthe outer planets! This could mean only one thing, that the longrivalry, the ancient dispute between Earth and Mars was about to flareinto open war. Any friendly visit from a foreign flier would beheralded by word from M-I-T-A. Thomas' face became a stony mask, covering the tumult of his mind. 

"You understood. I want the Earth recognition signal at once--andafter that, the surrender of the Dome. " The very calmness of the huskytones was a threat. 

"Never!"

"I warn you, Darl Thomas. It would be the better part of wisdom foryou to yield willingly what I ask. You will give in eventually, andthe means of persuasion I shall use will not be exactly--pleasant. "

"You'll get nothing from me!"

The outlander's lidless eyes were filmed with a gray membrane. Hishead thrust forward, the feathered ruff beneath it bristled. Darlbraced himself to withstand the swooping pounce that seemed imminent, the slash of the sharp beak. A burring rattle broke the momentaryhush. The Martian relaxed, turned to the Mercurian from whom the soundhad come and replied with staccato vibrance. 

 * * * * *

As the cave filled with a whirring tumult Darl had a chance to examinethe Mercurian natives crowding around his prostrate body. They werelittle yellow midgets, ranging from eighteen inches to two feet inheight. Half of their small stature was taken up by snouted heads, with saucer-like, crimson eyes, and long white tusks jutting fromfoam-flecked mouths. The trunks were globular. The spindling legs andthin arms ended in sharp claws. There was an impression of animalferocity about these tiny beings that stamped them as utter savages. 

His captor was speaking to the Earthman again, his horny beak partedin what might have been a grim smile. "My friends remind me that Ipromised you to them. They have not forgotten how you and your fellowsdrove them from their burrows. "

Darl was suddenly cold, though the sweat still streamed from his boundbody. An uncontrollable shudder took him as he saw what the diminutiveclaws of the midgets held. While the Dome was still an unfinishedframework one of the Terrestrian artisans had somehow been isolatedfrom his fellows. Thomas had been of the party that found what wasleft of him, and the memory was still a throbbing nightmare. 

"Once more! Will you give me the recognition signal?"

Darl shook his head, and prayed for sudden death. The Martian spoke tothe dwarfs. They started forward, saliva drooling from their tusks. Darl gritted his teeth. He would hold out as long as was humanlypossible. 

A shrill rhythmic whistle came from somewhere outside. The blue giantstarted and snapped something to the Mercurians. Then he turned toDarl. "I must leave you for a little while, " he said. "You have tillI return to change your mind. " With a parting admonition to thesavages he was gone through a side door that Thomas had not noticedbefore. 

 * * * * *

Grateful for the postponement, however short, of the inescapableordeal, Darl took stock of his situation. He lay, firmly bound, on thegritty rock floor of a low-ceiled cave about twelve feet square. Inone wall was a door of red metal. The portal through which the Martianhad vanished was next to it. Darl repressed an exclamation when he sawthe opposite wall. It was of solid metal, bluishly iridescent. Thatwas beryllium steel, the alloy from which the barriers at theterminals of the surta mine were fashioned. He forced his head higher. There were the marks of the jointures, the weldings that he himselfhad made. 

The discovery seemed only to emphasize the helplessness of hispredicament. His faithful Venusians, Ran-los, Ta-ira, and the restwere just on the other side of the three-inch plate of toughenedsteel. Three inches--yet it might have been as many hundred miles forall the help they could give him. 

The yellow pigmies were circling in a macabre dance, their crimsoneyes turned always toward him, hate glowing from their crawlingdepths. The whistle beyond changed in character. Darl recognized it. It was a Martian space-radio, the code of which Earth scientists hadnever been able to decipher. The Mercurian circle tightened, the fetidsmell of the dwarfs was overpowering. Low at first, then louder andlouder came the rattling cacophony of their chant. It filled theconfined space with an overpowering clamor. 

Darl writhed again, rolling over and over till he had reached thebarrier. The pigmies gave way before him; evidently they had beenwarned to keep their claws off. With his insteps Thomas could reachthe helmet of his space suit, where it had been dropped against thewall. He drove it against the metal and the clangor of its strikingreverberated through the chamber. Darl managed to regulate the sound. He was now hammering out double knocks, long and short, spaced in thedots and dashes of the Morse code. "H-E-L-P D-A-R-L H-E-L-P D-A-R-LH-E-L-P. . . . "

It was like some scene out of a madman's dream, this dim-lit cavernwith its circling, dancing pigmies, the human figure lying sidewise onthe ground, the rattling, savage chant and the metallic tattoo ofDarl's hopeless message. A diabolic orgy of weird sound andcrisscrossing shadows. 

 * * * * *

It seemed hours that he pounded the helmet against the wall, hopingthat the sound of it would be audible above the clamor of the midgets. His knees and hips were aching and numb, his leg ripped, almost to thebone by the sharp edges of the jagged floor. A sudden thought struckhim. The fiber thongs that bound him were also rubbing against therock. His flesh was terribly torn. Perhaps the thongs, too, had beenfrayed, weakened by the long continued friction. 

He stopped the pounding signals and began to force his knees apartwith all the power of his burly calves. The cords cut into his bulgingmuscles, cut into and through his skin. The veins stood out on hisforehead, his neck was a corded pillar, his teeth bit through his lipas he stifled a scream of pain. Then, startlingly, the fibers snapped. His legs at least were free! He could fight, die fighting, and takethese others with him into oblivion!

Darl leaped to his feet. Before the astounded natives realized whatwas up he was charging into their circle. A well aimed kick sent onecrashing against the further wall. Another crunched against the rock. Then they were on him, a frothing wave of tiny furies. A score ormore, they swarmed over him as a pack of African wild dogs swarms overa huge water-buffalo marked for the kill. Their claws scratched andtore, their sharp fangs stabbed into his flesh. His arms were stilltightly bound to his sides, and he lashed out with his sandaled feet, swung his shoulders like battering rams, whirled in a dervish dance. Their brittle bones cracked under his hammer blows. They dropped fromhim like squashed flies. But, small as they were, he was terrificallyoutnumbered. By sheer weight of numbers they dragged him down, andpiled on top of him as he lay, quivering and half-conscious, on theblood-soaked floor. 

 * * * * *

Through the blackness that welled and burst in his brain, one thoughtheld. He had fooled the Martian, for in another instant the enragedsavages, would kill him and the password to Earth's outposts would besafe. Already, he felt their fangs at his throat. 

A whirring rattle cut through the turmoil like a whip-lash, and theheap of pigmies swiftly scattered. The man-bird from Mars was in theroom. To Darl he was a blurred blueness from which glittered those twojet beads of eyes. As from a distance he heard a rumble, its meaningbeating dully to him. "Not so easy, Thomas, not so easy. I want thatsignal, and by Tana, I'm going to have it. "

The Earthman felt a current of cooler air. Instinctively he drew itinto his lungs. It swept him up from the blackness that was closing inabout him, brought him back to consciousness and despair. Thechattering Mercurians crowded round to commence their interruptedorgy. "For the last time, Earthman, will you talk?"

Darl shook his head weakly and closed his eyes. In a moment--

Suddenly there was a crash of metal on metal. Another! The clangor offalling steel. Now someone was shouting, "Darl, Darl, are you alive?"All about him were shrill twitterings, squeaking calls, squeals andscutterings. Darl's nostrils stung with the odor of burned flesh. Adoor slammed. . . . 

He opened his eyes on a confused riot, saw Jim crouched, flashingray-gun in hand. There was a hole in the barrier, and a mob ofgreen-scaled Venusians were crowding through. Jim's ray caught thelast Mercurian and the dwarf vanished in a cloud of acrid, greasysmoke. 

"Thank God you've come!" Darl managed to gasp. Then cool blacknessclosed around him. 

 * * * * *

Darl Thomas lay on a cot in the headquarters tent, swathed from headto foot in an inch-thick wrapping of bandages. Jim's theory was thatif one bandage was good, two were better, and he had cleaned out thepost's slender stock. The red-haired Earthman was seated at the cot'sside, watching the taciturn Scot operating the control board. He wastelling Darl of the stirring message from M-I-T-A, and of theblanketing interference that marred the completion of the message. 

"I didn't know what to do first, " he continued, "whether to go downbelow and find out what Ran-los was battin' about, or shoot up to youin the connin' tower with the message. Like the thick-head I am, Ipicked the wrong thing. I sure got the gimmicks when I found thelook-out empty, an' a space suit an' ray-gun gone. " Jim grinnedmirthlessly. "I was runnin' around in circles. You were outside, Godalone knows how long. Believe me, I had you crossed off the list! Thatleft two of us. With a war on, somebody had to stand guard in thelook-out, the control board here had to be watched, an' somebody elsehad to get below. 

"I was just tryin' to figure out a way o' cuttin' myself in half whenI thought o' Ran-los. For a Weenie he's got a heck of a lot of sense. I zoomed down, hauled him out o' his bunk, scooted back up, showed himhow to work the peri-telescope an' the big beam-thrower, an' left himthere on guard. "

"Best thing you could have done. " Darl's voice was muffled by thebandages in which his head, as well as the rest of his body, wasswathed. "He's got a head on his shoulders, that bird. "

"Somethin' told me to take a ray-gun down in the mine with me. I wasjust steppin' out o' the elevator when I caught your last signal; -L-PD-A-R-L was all I got, but it was enough. How you ever got the otherside of the barrier had me wingin', but you were there right enough, and yellin' for help. Ran-los had been doin' some repairs on a headsupport an' his weldin' machine was still there. Takin' an awfulchance on there bein' air on the other side, I butted it up againstthe wall, shot the flame against the steel, and when she was softenough had some of the Weenies smash her in with sledge-hammers. Firstthing I see is you, stretched out in a pool o' blood, with a couple ofthose yellow imps just gettin' to work on you. I clipped themfirst--that gave the Martian a chance to get away. An' then--well, youknow the rest. "

 * * * * *

"I owe you one for that, Jim. Too bad, though, the big fellow escaped;we'll hear from him again, or I don't know the breed. Wonder how hegot on the planet. "

"The sucker must 'a' stowed away on the last recruit ship from Venus, slipped in a case o' tools or somethin'. Mars has labor agents there, too, you know, for their farms on Ganymede. "

"Possibly. He knew my name, and that I was chief here. He's rigged upan air-lock out there, though I can't figure out how he gets the air. "

"That's easy. While I was repairin' the barrier I found a pipe runnin'through. He's been stealin' ours. Which, by the same token, is why hewas punchin' holes in the Dome rather than down below, where he wouldhave been safer from discovery. "

"So that's it. Get anything more on the space-radio?"

"Nope. Angus has kept the ear-flaps on, but the ether is still jammed. Hey, what're you up to?"

Darl was swinging his bandaged body up from the cot that had been setup in the headquarters tent at his insistence. "Can't lie on my back, "he panted, "with that devil loose on the planet. Lord knows what he'sup to now. We're short-handed enough as it is. "

He rose to his feet, staggering with weakness and loss of blood. Buthis indomitable will drove him on. "I'll take over the control board. Send Angus up to relieve Ran-los, and you get below and speed upproduction. Earth will need double quantities of surta for food, nowthat there's a war on. "

 * * * * *

Jim turned to convey the order to the Scot, but he whirled to thetent-flap instead as a riot of sound exploded outside. He tore asidethe canvas, and now there was a burst of shrill, frightened Venusiancries, and a deeper, rattling chorus. Out on the Dome floor, pouringfrom the shaft-head in a panic torrent, came the Venusians. And amongthem, leaping, slashing, dragging them down, were countless littleyellow men, their fangs and tusks and curving claws crimson with theblood of their victims. 

"Darl, Mac, they've broken through! The Mercs have broken through!"The brown plain was a blood-spattered battlefield. Here and therelittle groups of the green men, braver than the rest, fought withspanner and hammer and whatever improvised weapon they may have found. "Come on, give 'em hell!" The three Earthmen dashed out, weapons inhand. But friend and foe were so intermingled that they could not usethe devastating ray of their hand-guns. The fighting Venusians werevanishing under a tossing sea of yellow imps. And still the dwarfspoured forth from the mine entrance. 

A blue form towered, far back, where all green had vanished, and onlyMercurians were left. The Martian's beak opened in a rattling call. Agroup of hundreds of pigmies suddenly left the main fight, and cameforward with short, swift steps. They dashed straight for the Earthtrio and cut them off from the Venusians they were running to aid. 

 * * * * *

Side by side the three fought. Their weapons grew hot in their handsas the beams cut great swaths in the seething ranks. The attackershalted, gave back, then surged forward again as the roar of theiralien commander lashed them on. 

The Earthmen faced the frenzied throng. A cleared circle was stillaround them. Beyond, the Venusians were all down. The Mercurian mobwas closing in, the Terrestrians' rays had lost half their range. Inmoments now the ray-guns would be exhausted. 

"The plane!" Darl shouted. "Back to the plane, it's our only chance. "

The gyrocopter that could carry them aloft, out of the rout, was fiftyfeet away. They fought through to it and reached it just as the lastfaint charge flashed from Mac's tube. Jim was at the controls, Darlsmashed his useless projector into the chattering face of a dwarf thathad leaped on the Scot's shoulders and dragged Angus into the cockpit. 

The overloaded flier zoomed to the landing at the lofty air-lock'smanhole and hovered as Darl and Angus slipped home the hooks that heldit to the platform. "The spy has the Dome, " Jim grunted, "but by God, he hasn't got us. We'll be safe in the lock up here, till help comes. And then--"

"Safe is it?" Angus broke in. "Mon, luik ye what those bairns fra hellare up to the noo. "

A yellow tide was rising about the base of each of the latticed steelarches that vaulted to the Earthmen's refuge. On every side the dwarfswere climbing, were swarming up the walls in numbers so great thatthey concealed the metal beneath. Up, up they came, slowly but surely. And right in the center of the plain, ankle-deep in the torn fragmentsof the murdered Venusians, was the Martian, directing the attack. 

 * * * * *

Jim groaned. "I might've known he'd never let us get away. It's slowbells for us, I guess. Hey, where's Darl?"

"Gone weethin. No, guid losh, he's here!"

Darl appeared, his features pale and drawn, carrying an armful ofray-guns. "Grab these, " he snapped. "We're not licked yet. "

"Licked, hell!" Jim's roar reverberated. "We've just begun to fight!"The Scot was silent, but the battle light shone in his eyes. Inanother moment the Terrestrians were kneeling, were raking the roofgirders as the mounting Mercurians came within range. Each had tworay-guns in his hands, and a little pile of extra tubes beside him. They fought silently, wasting not a single blast. 

Six white rays flamed through the misty, humid air, and striking theteeming girders, swept them clean. A greasy, horrible smoke cloudgathered along the shell and drifted slowly down, till the concreteblocks from which the steel framework sprang were hidden in a blackpall. Fighters, these three, true ITA men who had left memories oftheir battle-prowess on more than one wild planet! Gaunt-bodieddemi-gods of war, they hurled crackling bolts of destruction fromtheir perch at the Dome top. By hundreds, by thousands, the Mercurianpigmies vanished in dark vapor, or plunged, blackened corpses, intothe fog that billowed below. 

One by one the tubes were discharged and tossed down at the seethingmob. The heaped weapons dwindled, and still the climbing hordesrenewed themselves, came on in endless mounting streams to suredestruction. The open tunnel vomited forth a torrent of gibberingdwarfs. From the uttermost burrows of the planet the pigmies wereflooding in at the call of the Martian who stood scatheless beneathand lashed them on with the strange dominance he held over them. TheEarthmen fought on, endlessly, till they were sick of killing, nauseated with slaughter. And still the snouted, red-eyed imps cameon. 

 * * * * *

Jim snatched up his last two ray-guns. Out of the corner of his eye henoted that Darl was using but one, the other, his last, was thrustinto the chief's belt. He wondered at this, but a new spurt of yellowabove the oily fog wiped the question from his lips. "Swallow that, you filthy lice! Hope you like the way it tastes!" His guns spouteddeath. 

"I'm through!" The call came at last from McDermott. "Me too!" JimHolcomb hurled his final, futile tubes down at the blue figure of theMars man. A moment's hush held the trio. Then Jim flexed his greathands. "Well, these'll take care of a couple more o' them before Icheck in. "

"No you don't, " Darl barked, his face a graven image. "Inside withyou. The lock will hold 'em off. "

"Yeah? Look. "

Thomas swung in the direction Jim was pointing. Rising above the murk, something glinted in the pale light. On the furthest upright a clumpedgroup of climbing savages were struggling to drag up one of thewelding machines, a long black hose snaking from its cylindrical bulk. 

"They'll cut through the steel in fifteen minutes with that. Thebloody bugger ain't missin' a trick. "

"Inside, I tell you. " Darl's crisp tone of command brooked no denial. The three crowded into the cool recesses of the manmade aerie. Angusslammed the steel door shut. Even if by some miracle the Dome wallshould be pierced and the air in the main vault dissipated into outerspace, this air-tight compartment hung from the hemisphere's roofwould remain, a last refuge, till the atmosphere within had becomepoisonous through the Earthmen's slow breathing. But the Martian hadanticipated Darl's final move. The oxy-hydrogen jet of the weldingmachine the dwarfs were hoisting would make short work of their finaldefense. 

 * * * * *

From the conning-tower above Ran-los called excitedly. Through all thelong battle the Venusian had remained steadfast at the peri-telescope, scanning the vacant terrain outside, and the heavens. As Darl and Jimdashed for the stairs Mac ran after them, crying out, "What did he say, mon?"

"Space ship in sight, " Darl flung over his shoulder as he reached theupper landing. 

"Praise be! Noo the haythan weel get his desairts!"

"Yeah, maybe--if it's an Earth ship. But we won't be here to see it. "

Jim's red head was bending over the peri-telescope view-screen. "She'sstill thirty thousand miles away. Give her a speed of fifteen persecond--she'll have to slow up to land, can't make it under forty-fiveminutes. By then we'll be in little pieces. It took me ten minutes toburn through the barrier when I rescued Darl, and it won't take theMercs any longer to get at us. "

Darl was very sober as he looked on with narrowed eyes. Against abackground of velvet black, gold spangled, the slim space-travelershowed. The sun's rays caught her, and she was a tiny silver fish inthe boundless void. 

"Luik ye, mon, luik ye!" Angus, fairly dancing with excitement, elbowed Darl aside. "She's from Airth, richt enow!" At the nose of theoncoming flier a rapid succession of colored lights had flashed, therecognition signal that should give her safe access to the Dome. Againthere was a coruscation of coded flashes. "She's a battle cruiser, what's mair!" the Scot exclaimed. 

 * * * * *

Darl sprang to the keyboard that manipulated the signal lights fromthe Dome's roof. "No use, " he said, after a short while. "The Martianhas cut off the current from the dynamos. I can't warn the ship. " Hemade a hopeless gesture. 

Jim looked at him wonderingly. "Warn 'em? What for? Even if we are alldead when she reaches here, at least she'll clean up the Mercs, andretake the Dome for Earth. "

"Don't you see it? When the Mars man has once blasted his way in hereand disposed of us, he'll be ready for the space ship. Her captaincan't suspect anything wrong. He must have left Earth at the time ofthe ultimatum, and would easily get here before any ship could be sentout from Mars. He'll come on till he's within range of thebeam-thrower, and the Martian will aim, press the trigger and theEarth ship and her crew of a half a thousand brave lads will bestar-dust. "

"Oh God!" Jim was white-faced. "Isn't there anything we can do? Maybeif he doesn't get our all-clear signal he'll sheer off. " This wasclutching at straws. 

"Why should he? He must know how short-handed we are, and will simplythink we're not on watch, or that our signal lights are out of order. Matter of fact, if he were at all suspicious he should be alternatinghis course right now--and he hasn't. Look. "

Seemingly motionless, but really splitting the ether with terrificspeed, the warship was coming straight on to garrison the beleagueredpost. She had never wavered from her straight course for the Dome. Thelittle group was silent, watching the help that was coming at last, coming too late. 

 * * * * *

From below there came a thunder of sound. Jim slid down the stairs. Anirregular disk on the wall was glowing cherry-red from the heat of theblow-torch without, and the metal was quivering under the Mercurian'ssledge-hammer blows. "Darl's right, " he almost sobbed as he gazedhelplessly. "They'll be through in no time. The Dome's gone, we'regone, the space ship's gone!"

"Let me pass, Jim. " Thomas' quiet voice sounded behind him. Holcombturned. His leader was in a space suit, the helmet still unfastened. 

"Blazes! Where the devil are you going?"

"Here, cover me with this till I reach the gyrocopter, then get backquick, and seal the air-lock. " Darl thrust into Jim's hand the ray-gunhe had previously reserved. "There's only one way to kill off theMartian and his mob. I'm taking it. "

Suddenly Jim Holcomb understood. "No, Darl, no--you can't do it! Notyou! Let me go! I'm just a dumbhead. Let me go!"

"Thanks, Jimmy, but it's my place. " Darl's voice was low, and verycalm. "I was in charge, and I lost the Dome. If I can save the boys onthe ship, and you two, it's the least I can do. Good-by, old man. Givemy regards to Earth. "

Thomas' face was gray-white. The thick bandages that still swathedhim, Jim glimpsed them through the open neckpiece of the suit, gavehim the semblance of a mummy. The helmet clicked shut. Swallowing alump that rose in his throat, Jim pulled open the door. A wave ofMercurians surged in, to be seared into nothingness by his weapon. Hewas in the doorway, his ray sweeping the platform clear. 

Darl was out now, stepping into the flier that still hung by itshooked moorings. Jim caught a flash of blue and looked up. The Martianwas hanging to a girder just above, his green tube pointing straightat Darl. A white ray spurted from Jim's gun. The Martian's weapon andthe hand that held it vanished in the sizzling blast. The plane wasloose! Jim leaped inside the air-lock, slammed the steel door shut, clamped it, and sprang for the quartz peer-hole. 

 * * * * *

Darl's gyrocopter was diving on a long slant for the Dome wall. Fasterand faster it went, till all Jim could see was a white streak in thesmoky dimness. And now he could see the vast interior, the teemingplain, the dwarf-festooned girders and roof-beams. He stood rigid, waiting breathlessly. Then the plane struck--fair in the center of agreat panel of quartz. The wall exploded in a burst of flying, shattered splinters. A deafening crash rocked the Dome. 

Jim clung to his port-hole, tears rolling down his cheeks, unashamed. The plane, and Darl, vanished. Jim saw the black smoke masses whirlthrough the jagged hole in the Dome's wall as the air burst out in acyclonic gust. He saw the vast space filled with falling Mercurians, saw a blue form plunge down and crash far below. He knew that in allthat huge hemisphere, and in the burrows beneath it, there was no lifesave himself, and Angus, and the faithful Ran-los. For only in thiscompartment that clung to the roof of the Dome was there left air tobreathe. And, from the void beyond, the silver space ship sped ontoward Mercury, sped on to a safe landing that, but for Darl Thomas'ssacrifice, would have been her doom. . . . 

Guided by Jim and Angus, a party of men from the battle-flier, equipped with oxygen respirators, went to the aid of Darl. They dughim out from under his crumpled plane and the piled splinters ofquartz. His metal was dented and twisted, but unpierced. They carriedhim tenderly to the space ship, and carefully set him down. The ship'sphysician listened long with his stethoscope, then looked up andsmiled. 

"He's alive, " the doctor said, "just barely alive. The thick paddingof bandages must have saved him from the full shock of the crash. They're hard to kill, these ITA men. I'll be able to bring him around, God willing. "

 * * * * *