by Various
The Second Satellite
_By Edmond Hamilton_
_The city of the frog-men!_]
[Sidenote: Earth-men war on frog-vampires for the emancipation of thehuman cows of Earth's second satellite.]
Norman and Hackett, bulky in their thick flying suits, seemed to fillthe little office. Across the room Harding, the field superintendent,contemplated them. Two planes were curving up into the dawn togetherfrom the field outside, their motors thunderous as they roared overthe building. When their clamor had receded, Harding spoke:
"I don't know which of you two is crazier," he said. "You, Norman, topropose a fool trip like this, or you, Hackett, to go with him."
Hackett grinned, but the long, lean face of Norman was earnest. "Nodoubt it all sounds a little insane," he said, "but I'm convinced I'mright."
The field superintendent shook his head. "Norman, you ought to bewriting fiction instead of flying. A second satellite--and Fellows andthe others on it--what the devil!"
"What other theory can account for their disappearance?" asked Normancalmly. "You know that since the new X-type planes were introduced,hundreds of fliers all over Earth have been trying for altituderecords in them. Twenty-five miles--thirty--thirty-five--the recordshave been broken every day. But out of the hundreds of fliers whohave gone up to those immense heights, four have never come down norbeen seen again!
"One vanished over northern Sweden, one over Australia, one over LowerCalifornia, and one, Fellows, himself, right here over Long Island.You saw the globe on which I marked those four spots, and you saw thatwhen connected they formed a perfect circle around the Earth. The onlyexplanation is that the four fliers when they reached a forty-mileheight were caught up by some body moving round Earth in that circularorbit, some unknown moon circling Earth inside its atmosphere, asecond satellite of Earth's whose existence has until now never beensuspected!"
* * * * *
Harding shook his head again. "Norman, your theory would be all rightif it were not for the cold fact that no such satellite has ever beenglimpsed."
"Can you glimpse a bullet passing you?" Norman retorted. "The twofliers at Sweden and Lower California vanished within three hours ofeach other, on opposite sides of the Earth. That means that thissecond satellite, as I've computed, circles Earth once every sixhours, and travelling at that terrific speed it is no more visible tous of Earth than a rifle bullet would be."
"Moving through Earth's atmosphere at such speed, indeed, one wouldexpect it to burn up by its own friction with the air. But it doesnot, because its own gravitational power would draw to itself enoughair to make a dense little atmosphere for itself that would cling toit and shield it as it speeds through Earth's upper air. No, I'mcertain that this second satellite exists, Harding, and I'm as certainthat it's responsible for the vanishing of those four fliers."
"And now you and Hackett have figured when it will be passing overhere and are going up in an X-type yourselves to look for it,"Harding said musingly.
"Look for it?" echoed Hackett. "We're not going to climb forty milesjust to get a look at the damn thing--we're going to try landing onit!"
"You're crazy sure!" the field superintendent exploded. "If Fellowsand those others got caught by the thing and never came down again,why in the name of all that's holy would you two want--" He stoppedsuddenly. "Oh, I think I see," he said, awkwardly. "Fellows was rathera buddy of you two, wasn't he?"
"The best that ever flew a crippled Nieuport against three Fokkers topull us out of a hole," said Norman softly. "Weeks he's been gone, andif it had been Hackett and I he'd be all over the sky looking forus--the damned lunatic. Well, we're not going to let him down."
"I see," Harding repeated. Then--"Well, here comes your mechanic,Norman, so your ship must be ready. I'll go with you. It's an event tosee two Columbuses starting for another world."
* * * * *
The gray dawn-light over the flying field was flushing to faint roseas the three strode out to where the long X-type stood, its strangelycurved wings, enclosed cabin and flat, fan-like tail gleaming dully.Its motor was already roaring with power and the plane's stubby wheelsstrained against the chocks. In their great suits Norman and Hackettwere like two immense ape-figures in the uncertain light, to the eyesof those about them.
"Well, all the luck," Harding told them. "You know I'm pulling foryou, but--I suppose it's useless to say anything about being careful."
"I seem to have heard the words," Hackett grinned, as he and Normanshook the field superintendent's hand.
"It's all the craziest chance," Norman told the other. "And if wedon't come down in a reasonable time--well, you'll know that ourtheory was right, and you can broadcast it or not as you please."
"I hope for your sake that you're dead wrong," smiled the official."I've told you two to get off the Earth a lot of times, but I nevermeant it seriously."
Harding stepped back as the two clambered laboriously into the crampedcabin. Norman took the controls, the door slammed, and as the chockswere jerked back and the motor roared louder the long plane curved upat a dizzy angle from the field into the dawn. Hackett waved a thickarm down toward the diminishing figures on the field below; thenturned from the window to peer ahead with his companion.
The plane flew in a narrow ascending spiral upward, at an angle thatwould have been impossible to any ship save an X-type. Norman's eyesroved steadily over the instrument as they rose, his earsunconsciously alert for each explosion of the motor. Earth recededswiftly into a great gray concave surface as they climbed higher andhigher.
By the time the five-mile height was reached Earth's surface hadchanged definitely from concave to convex. The plane was ascending bythen in a somewhat wider spiral, but its climb was as steady and sureas ever. Frost begin to form quickly on the cabin's windows, creepingout from the edges. Norman spoke a word over the motor's muffledthunder, and Hackett snicked on the electrical radiators. The frostcrept back as their warm, clean heat flooded the cabin.
Ten miles--fifteen--they had reached already altitudes impossible buta few years before, though it was nothing to the X-types. As theypassed the ten-mile mark, Hackett set the compact oxygen-generatorgoing. A clean, tangy odor filled the cabin as it began functioning.Twenty miles--twenty-two--
* * * * *
After a time Norman pointed mutely to the clock on the instrumentboard, and Hackett nodded. They were well within their time schedule,having calculated to reach the forty-mile height at ten, the hourwhen, by its computed orbit, the second satellite should be passingoverhead. "--26--27--28--" Hackett muttered the altimeter figures tohimself as the needle crept over them.
Glancing obliquely down through the window he saw that Earth was now ahuge gray ball beneath them, white cloud-oceans obscuring the drabdetails of its surface here and there. "--31--32--" The plane wasclimbing more slowly, and at a lesser angle. Even the X-type had tostruggle to rise in the attenuated air now about them. Only thesuper-light, super-powered plane could ever have reached the terrificheight.
It was at the thirty-four mile level that the real battle for altitudebegan. Norman kept the plane curving steadily upward, handling it withsurpassing skill in the rarefied air. Frost was on its windows nowdespite the heating mechanism. Slowly the altimeter needle crept tothe forty mark. Norman kept the ship circling, its wings tiltedslightly, but not climbing, Earth a great gray misty ball beneath.
"Can't keep this height long," he jerked. "If our second satellitedoesn't show up in minutes we've had a trip for nothing."
"All seems mighty different up here," was Hackett's shouted comment."Easy enough to talk down there about hopping onto the thing, but uphere--hell, there's nothing but air and mighty little of that!"
Norman grinned. "There'll be more. If I'm right about this thing wewon't need to hop it--its own atmosphere will pick us up."
Both looked anxious as the motor sputtered briefly. But in
a moment itwas again roaring steadily. Norman shook his head.
"Maybe a fool's errand after all. No--I'm still sure we're right! Butit seems that we don't prove it this time."
"Going down?" asked Hackett.
"We'll have to, in minutes. Even with its own air-feed the motor can'tstand this height for--"
* * * * *
Norman never finished the words. There was a sound, a keen rising,rushing sound of immense power that reached their ears over themotor's roar. Then in an instant the universe seemed to go mad aboutthem: they saw the gray ball of Earth and the sun above skyrocketingaround them as the plane whirled madly.
The rushing sound was in that moment thunderous, terrible, and aswinds smashed and rocked the plane like giant hands, Hackett glimpsedanother sphere that was not the sphere of Earth, a greenish globe thatexpanded with lightning speed in the firmament beside their spinningplane! The winds stilled; the green globe changed abruptly to alandscape of green land and sea toward which the plane was falling!Norman was fighting the controls--land and sea were gyrating up tothem with dizzy speed--crash!
With that cracking crash the plane was motionless. Sunlight pouredthrough its windows, and great green growths were all around it.Hackett, despite Norman's warning cry, forced the door open and wasbursting outside, Norman after him. They staggered and fell, withcurious lightness and slowness, on the ground outside, then clutchedthe plane for support and gazed stupefiedly around them.
The plane had crashed down into a thicket of giant green reeds thatrose a yard over their heads, its pancake landing having apparentlynot damaged it. The ground beneath their feet was soft and soggy, theair warm and balmy, and the giant reeds hid all the surroundinglandscape from view.
In the sky the sun burned near one horizon with unusual brilliance.But it was dwarfed, in size, by the huge gray circle that filled halfthe heavens overhead. A giant gray sphere it was, screened here andthere by floating white mists and clouds, that had yet plain on itthe outlines of dark continents and gleaming seas. A quakingrealization held the two as they stared up at it.
* * * * *
"Earth!" Norman was babbling. "It's Earth, Hackett--above us; my God,I can't believe even yet that we've done it!"
"Then we're on--the satellite--the second satellite!--" Hackett foughtfor reality. "Those winds that caught us--"
"They were the atmosphere of this world, of the second satellite! Theycaught us and carried us on inside this smaller world's atmosphere,Hackett. We're moving with it around Earth at terrific speed now!"
"The second satellite, and we on it!" Hackett whispered,incredulously. "But these reeds--it can't all be like this--"
They stepped together away from the plane. The effort sent each ofthem sailing upward in a great, slow leap, to float down more than ascore of feet from the plane. But unheeding in their eagerness thisstrange effect of the satellite's lesser gravitational power, theymoved on, each step a giant, clumsy leap. Four such steps took themout of the towering reeds onto clear ground.
It was a gentle, grassy slope they were on, stretching away along agray-green sea that extended out to the astoundingly near horizon ontheir right. To the left it rose into low hills covered with densemasses of green junglelike vegetation. Hackett and Norman, though,gazed neither at sea or hills for the moment, but at the half-scoregrotesque figures who had turned toward them as they emerged from thereeds. A sick sense of the unreal held them as they gazed, frozen withhorror. For the great figures returning their gaze a few yards fromthem were--frog-men!
* * * * *
Frog-men! Great mottled green shapes seven to eight feet in height,with bowed, powerful legs and arms that ended in webbed paws. Theheads were bulbous ones in which wide, unwinking frog-eyes were set atthe sides, the mouths white-lipped and white-lined. Three of thecreatures held each a black metal tube-and-handle oddly like atarget-pistol.
"Norman!" Hackett's voice was a crescendo of horror. "_Norman!_"
"Back to the plane!" Norman cried thickly. "The plane--"
The two staggered back, but the frog-men, recovering from their ownfirst surprise, were running forward with great hopping steps! The twofliers flung themselves back in a floating leap toward the reeds, butthe green monsters were quick after them. A croaking cry came from oneand as another raised his tube-and-handle, something flicked from itthat burst close beside Norman. There was no sound or light as itburst, but the reeds for a few feet around it vanished!
* * * * *
A hoarse cry from Hackett--the creatures had reached him, grasped himat the edge of the reeds! Norman swerved in his floating leap tostrike the struggling flier and frog-men. The scene whirled around himas he fought them, great paws reaching for him. With a sick, franticrage he felt his clenched fist drive against cold, green, billowybodies. Croaking cries sounded in his ears; then, Hackett and he werejerked to their feet, held tightly by four of the creatures.
"My God, Norman," panted Hackett, helpless. "What arethey--frog-things?--"
"Steady, Hackett. They're the people of the second satellite, itseems; wait!"
One of the armed frog-men approached and inspected them, and thencroaked an order in a deep voice. Then, still holding the two tightly,the party of monsters began to move along the slope, skirting thesea's edge. In a few minutes they reached two curious objects restingon the slope. They seemed long black metal boats, slender and withsharp prow and stern. A compact mechanism and control-board filledthe prow, while at the stern and sides were long tubes mounted onswivels like machine-guns.
The frog-men motioned Norman and Hackett into one, fastening the twoprisoners and themselves into their seats with metal straps providedfor the purpose. Four had entered the one boat, the others that of thecaptives. One at the prow moved his paws over the control-board andwith a purring of power the boat, followed by the other, rose smoothlyinto the air. It headed out over the gray-green sea, land droppingquickly from sight behind, the horizons water-bounded on all sides.From their nearness Norman guessed that this second satellite ofEarth's was small indeed beside its mother planet. He had to look upto earth's great gray sphere overhead to attain a sense of reality.
Hackett was whispering beside him, the frog-men watchful. "Norman, it'snot real--it can't be real! These things--these boats--intelligent likemen--"
The other sought to steady him. "It's a different world, Hackett.Gravitation different, light different, everything different, andevolution here has had a different course. On Earth men evolved to bethe most intelligent life-forms, but here the frog-races, it seems."
"But where are they taking us? Could we ever find the plane again?"
"God knows. If we ever get away from these things we might. And we'vegot to find Fellows, too; I wonder where he is on this world."
* * * * *
For many minutes the two boats raced on at great speed over theendless waters before the watery skyline was broken far ahead bysomething dark and unmoving. Hackett and Norman peered with intenseinterest toward it. It seemed at first a giant squat mountain risingfrom the sea, but as they shot nearer they saw that its outline wastoo regular, and that colossal as it was in size it was the work ofintelligence. They gasped as they came nearer and got a better view ofit.
For it was a gigantic dome of black metal rising sheer from the lonelysea, ten miles if anything in diameter, a third that in greatestheight. There was no gate or window or opening of any kind in it. Justthe colossal, smooth black dome rearing from the watery plain. Yet thetwo boats were flashing lower toward it.
"They can't be going inside!" Hackett conjectured. "There's no way inand what could be in there? The whole thing's mad--"
"There's some way," Norman said. "They're slowing--"
The flying-boats were indeed slowing as they dipped lower. They werevery near the dome now, its curving wall a looming, sky-high barrierbefore them. Su
ddenly the boats dipped sharply downward toward thegreen sea. Before the two fliers could comprehend their purpose, coulddo aught more than draw instinctive great breaths in preparation, thetwo craft had shot down into the waters and were arrowing down throughthe green depths.
Blinded, flung against his metal strap by the resistance of the watersthey ripped through, Norman yet retained enough of consciousness toglimpse beams of light that stabbed ahead from the prows of theirrushing boats, to see vaguely strange creatures of the deep blunderingin and out of those beams as the boats hurtled forward. The water thatforced its way between his lips was fresh, he was vaguely aware, andeven as he fought to hold his breath was aware too that the frog-menseemed in no way incommoded by the sudden transition into the water,their amphibian nature allowing them to stay under it far longer thanany human could do.
The boats ripped through the waters at terrific speed and in a fewseconds there loomed before them the giant metal wall of the greatdome, going down into the depths here. Norman glimpsed vaguely thatthe whole colossal dome rested on a vast pedestal-like mountain ofrock that rose from the sea's floor almost to the surface. Then agreat round opening in the wall; the boats flashed into it and werehurtling along a water-filled tunnel. Norman felt his lungs nearbursting--when the tunnel turned sharply upward and the boats whizzedup and abruptly out of the water-tunnel into air!
* * * * *
But it was not the open air again. They were beneath the giganticdome! For as Norman and Hackett breathed deep, awe fell on their facesas they took in the scene. Far overhead stretched the dome'scolossally curving roof, and far out on all sides. It was lit beneaththat roof by a clear light that the two would have sworn was sunlight.The dome was in effect the roof of a gigantic, illuminated building,and upon its floor there stretched a mighty city.
The city of the frog-men! Their boats were rising up over it andNorman and Hackett saw it clear. Square mile upon square mile ofstructures stretched beneath the dome, black buildings often ofimmense size, varying in shape, but all of square, rectangularproportions. Between them moved countless frog-hordes, swirlingthrongs in streets and squares, and over the roofs darted thick swarmsof flying-boats. And at the city's center, in a great, circular, clearspace, lay a wide, round, green pool--the opening of the water-tunnelup through which they had come.
Norman pointed down toward it. "That's your answer!" he cried. "Theonly entrance to this frog-city is from the sea, up through thatwater-tunnel!"
"Good God, an amphibian city!" Hackett was shaken, white-faced.
The two boats were driving quickly over the city, through the swarmingcraft. Norman glimpsed towering buildings that might have beenpalaces, temples, laboratories. They slowed and dipped toward oneblock-like building not far from the water-tunnel's opening. Armedfrog-guards were on its roof, and other boats rested there. The twocame to rest and the two captives were jerked out, the guards seizingthem.
Half-dragged and half-floating they were led toward an opening in theroof from which a stair led downward. They passed down thus into thebuilding's interior, lit by many windows. Norman glimpsed long hallsending in barred doors, guards here and there. Tube-lines ran alongthe walls and somewhere machines were throbbing dully. They came atlast to a barred door whose guard opened it at the croaking order ofthe frog-men who held the two, and they were thrust inside, as thedoor clanged. They turned, and exclaimed in amazement. The room heldfully a half-hundred men!
They were men such as the two fliers had never seen before, likehumans except that their skins were a light green instead of thenormal white and pink. They were dressed in dark short tunics, andkept talking to each other in a tongue quite unintelligible to Normanand Hackett. They came closer, flocking curiously around the two men,with a babel of voices quite meaningless to the two. Then one of themen uttered an exclamation, and all turned.
* * * * *
The barred door had swung open and a half-dozen frog-guards entered,followed by two frog-men carrying a square little mechanism from whichtubing led back out through the door.
"Norman--these men--" Hackett was whispering rapidly. "If there aremen in this world too, it may be that--"
"Quiet, Hackett--look at what they're doing."
The two frog-men had set their mechanism in place and then croaked outa brief word or order. Slowly, reluctantly, one of the green men movedtoward them. Quickly they removed a metal disk fastened to his arm,exposing a small orifice like an unhealed wound. Onto this theyfastened a suckerlike object from which a transparent tube led backthrough the mechanism. The machine hummed and at once a red streampulsed through the tube and back through the mechanism. The man towhom it was attached was growing rapidly pale!
Norman, sick with horror, clutched his companion. "Hackett--thesefrog-men are sucking his blood from him!"
"Good God! And look--they're doing it with another!"
"All of these men--kept prisoners to furnish them with blood. It mustbe the damned creatures' food! And we here with the others--"
A common horror shook the two. It did not seem to affect the green menin the room, though, who advanced to the mechanism one by one with areluctant air as of cows unwilling to be milked. Each was attached tothe mechanism by the sucking disk on his arm, and out of each theblood poured through the tube. The metal disk was replaced on his armthen and he went back to the others. Norman saw that the frog-men tookonly from each an amount of blood that they could lose and yet live,since, though each came back pale and weak from the mechanism, theywere able to walk.
"It must be their food--human blood!" Norman repeated. "They may havethousands on thousands of humans penned up like this, like so manyherds of cows, and perhaps they live entirely on the life-blood theymilk from them. Human cows--God!"
"Norman--look--they're calling to us!"
* * * * *
The two stiffened. All the others in the room had taken their turn atthe blood-sucking mechanism and now the frog-men croaked their orderto the two fliers. They had forgotten their own predicament in thehorror of the scene, but now it became real to them. They backedagainst the room's wall, quivering, dangerous.
The frog-guards came forward to drag them to the machine. A webbed pawwas outstretched but Hackett with a wild blow drove the frog-man backand downward. The frog-guards leaped, and Norman and Hackett struckthem back with all the greater strength the lesser gravitation gavethem. The room was in an uproar, the green men shouting hoarsely andseeming on the point of rushing to their aid.
But the menacing force-pistols of the other frog-guards held back theshouting men and in moments the two fliers were overpowered by sheerweight of frog-bodies. Norman felt himself dragged to the machine.
Pain needled his upper arm as an incision was made. He felt thesucking-disk attached; then the machine hummed, and a sickening nauseaswept him as the blood drained from his body. Held tightly by theguards he went dizzy, weak, but at last felt the sucker removed and ametal disk fastened over the incision. He was jerked aside andHackett, his face deathly white, was dragged into his place. In amoment some of the latter's blood had been pumped from him also.
The machine was withdrawn, Norman and Hackett were released, and thefrog-men, with their black force-pistols watchfully raised, withdrew,the door clanging. The room settled back to quietness, the green menstretching in lassitude on the metal bunks around it. The two flierscrouched down near the door, shuddering nausea and weakness stillholding them.
Norman found that Hackett was laughing weakly. "To think thattwenty-four hours ago I was in New York," he half-laughed,half-sobbed. "On Earth--Earth--"
The other gripped his arm. "It's horrible, Hackett, I know. But itisn't instant death, and we've still a chance to escape. Hell, candamn frog-men keep us here? Where's your nerve, man?"
A voice beside them made them turn in amazement. "You are men fromEarth?" it asked, in queerly accented English. "From Earth?"
* * * * *
Astonishment held them as they saw who spoke. It was one of the greenmen in the room, who had settled down by their side. A tall figurewith superb muscles and frank, clean countenance, his dark eyes afirewith eagerness.
"English?" Norman exclaimed. "You know English--you understand me?"
The other showed his teeth in a smile. "I know, yes. I'm Sarja, and Ilearned to speak it from Fallas, in my city, before the Ralas caughtme."
"Fallas--" Norman repeated, puzzled; then suddenly he flamed. "By God,he means Fellows!"
"Fallas, yes," said the other. "From the sky he fell into our city ina strange flying-boat that was smashed. He was hurt but we cared forhim, and he taught me his speech, which I heard you talking now."
"Then Fellows is in your city now?" asked Hackett eagerly. "Where isthat?"
"Across this sea--back in the hills," the other waved. "It is far fromthe sea but I was rash one day and came too near the water in myflying-boat. The Ralas were out raiding and they saw me, caught me,and brought me here. No escape now, until I die."
"The Ralas--you mean these frog-men?" Norman asked.
Sarja nodded. "Of course. They are the tyrants and oppressors of thisworld. Our little world is but a tenth or less the size of your greatEarth which it circles, but it has its lands and rivers, and this onegreat fresh-water sea into which the latter empty. In this sea longago developed the Ralas, the great frog-men who acquired suchintelligence and arts that they became lords of this world.
"Through the centuries, while on the land our races of green men havebeen struggling upward, the Ralas have oppressed them. Long ago theRalas left all their other cities to build this one great amphibiancity at the sea's center. Entrance to it is only by the water-tunnelfrom without, and being frog-people entrance thus is easy for themsince they can move for many minutes under water, though they drownlike any other breathing animal if kept under too long. Humans darenot try to enter it thus by the water-tunnel, since, before they couldfind it and make their way up through it, they would have drowned.
* * * * *
"So the Ralas have ruled from this impregnable amphibian city. Itscolossal metal dome is invulnerable to ordinary attack, and thoughsolid and without openings it is always as light beneath the dome hereas outside, since the Ralas' scientists contrived light-condensers andconductors that catch light outside and bring it in to release inside.So when it is day outside the sunlight is as bright here, and whennight comes the Earth-light shines here the same as without.
"From this city their raiding parties have gone out endlessly to swoopdown on the cities of us green men. Since we learned to makeflying-boats like theirs, with molecular-motors, and to make the gunslike theirs that fire shells filled with annihilating force, we haveresisted them stoutly but their raids have not ceased. And always theyhave brought their prisoners back in to this, their city.
"Tens of thousands of green men they have prisoned here like us, forthe sole purpose of supplying them with blood. For the Ralas live onthis blood alone, changing it chemically to fit their own bodies andthen taking it into their bodies. It eliminates all necessity for foodhere for them. Every few days they drain blood from us, and since weare well fed and cared for to keep us good blood-producers, we will behere for a long time before we die."
"But haven't you made any attempt to get out of here--to escape?"Norman asked.
Sarja smiled. "Who could escape the city of the Ralas? In all recordedhistory it has never been done, for even if by some miracle you got aflying-boat, the opening of the water-tunnel that leads outward isguarded always."
"Guards or no guards, we're going to try it and not sit here tofurnish blood for the Ralas," Norman declared. "Are you willing tohelp, to try to get to Fellows and your city?"
The green man considered. "It is hopeless," he said, "but as well todie beneath the force-shells of the Ralas as live out a lifetime here.Yes, I will help, though I cannot see how you expect to escape evenfrom this room."
"I think we can manage that," Norman told him. "But first--not a wordto these others. We can't hope to escape with them all, and there isno knowing what one might not betray us to the frog-men."
He went on then to outline to the other two the idea that had come tohim. Both exclaimed at the simpleness of the idea, though Sarjaremained somewhat doubtful. While Hackett slept, weak still from hisloss of blood, Norman had the green man scratch on the metal floor aswell as possible a crude map of the satellite's surface, and foundthat the city, where Fellows was, seemed some hundreds of miles backfrom the sea.
* * * * *
While they talked, the sunlight, apparently sourceless, that camethrough the heavily barred windows of the room faded rapidly, and dusksettled over the great amphibian city beneath the giant dome, keptfrom total darkness by a silvery pervading light that Norman reflectedmust be the light from Earth's great sphere. With the dusk's comingthe activities in the frog-city lessened greatly.
With dusk, too, frog-guards entered the room bearing long metaltroughs filled with a red jellylike substance, that they placed onracks along the wall. As the guards withdrew the men in the roomrushed toward the troughs, elbowing each other aside and strikingeach other to scoop up and eat as much of the red jelly as possible.It was for all the world like the feeding of farm-animals, and Hackettand Norman so sickened at the sight that they had no heart to try thefood. Sarja, though, had no such scruples and seemed to make a heartymeal at one of the troughs.
After the meal the green men sought the bunks and soon were stretchedin sonorous slumber. It was, Norman reflected, exactly the existenceof domesticated animals--to eat and sleep and give food to theirmasters. A deeper horror of the frog-men shook him, and a deeperdetermination to escape them. He waited until all in the room weresleeping before beckoning to Sarja and Hackett.
"Quiet now," he whispered to them. "If these others wake they'll makesuch a clamor we won't have a chance in the world. Ready, Sarja?"
The green man nodded. "Yes, though I still think such a thing'simpossible."
"Probably is," Norman admitted. "But it's the one chance we've got,the immensely greater strength of our Earth-muscle that the frog-menmust have forgotten when they put us in here."
They moved silently to the room's great barred door, outside which afrog-guard paced. They waited until he had passed the door and on downthe hall, then Norman and Hackett and Sarja grasped together one ofthe door's vertical bars. It was an inch and a half in thickness, ofsolid metal, and it seemed ridiculous that any men could bend it bythe sheer strength of their muscles.
Norman, though, was relying on the fact that on the second satellite,with its far lesser gravitational influence, their Earth-muscles gavethem enormous strength. He grasped the bar, Hackett and Sarja grippingit below him, and then at a whispered word they pulled with all theirforce. The bar resisted and again, with sweat starting on theirforeheads, they pulled. It gave a little.
* * * * *
They shrank back from it as the guard returned, moving past. Thengrasping the bar again they bent all their force once more upon it.Each effort saw it bending more, the opening in the door's barswidening. They gave a final great wrench and the bent bar squealed alittle. They shrank back, appalled, but the guard had not heard ornoticed. He moved past it on his return along the hall, and no soonerwas past it than Norman squeezed through the opening and leapedsilently for the great frog-man's back.
It went down with a wild flurry of waving webbed paws and croakingcries, stilled almost instantly by Norman's terrific blows. There wassilence then as Hackett and Sarja squeezed out after him, themomentary clamor of the battle having aroused no one.
The three leaped together toward the stairs. In two great floatingleaps they were on the floor above, Hackett and Norman dragging Sarjabetween them. They were not seen, were sailing in giant steps upanother stair, hopes rising high. The last stair--th
e roof-openingabove; and then from beneath a great croaking cry swelled instantlyinto chorus of a alarmed shouts.
"They've found the door--the guard!" panted Hackett.
They were bursting out onto the roof. Frog-guards were on it who camein a hopping rush toward them, force-pistols raised. But a giant leaptook Hackett among them, to amaze them for a moment with greatflailing blows. Sarja had leaped for the nearest flying-boat restingon the roof, and was calling in a frantic voice to Norman and Hackett.Norman was turning toward Hackett, the center of a wild combat, butthe latter emerged from it for a brief second to motion himfrantically back.
"No use, Norman--get away--get away!" he cried hoarsely, frenziedly.
"Hackett--for God's sake--!" Norman half-leaped to the other, but anarm caught him, pulled him desperately onto the boat's surface. It wasSarja, the long craft flying over the roof beneath his control.
"They come!" he panted. "Too late now--" Frog-men were pouring up ontothe roof from below. Sarja sent the craft rocketing upward, as Hackettgestured them away for a last frantic time before going down beneaththe frog-men's onslaught.
* * * * *
The roof and the combat on it dropped back and beneath them like astone as their craft ripped across the silvery dusk over the mightyfrog-city. They were shooting toward the city's center, toward thegreen pool that was the entrance to the water-tunnel, while behind andbeneath an increasing clamor of alarm spread swiftly. Norman ragedfutilely.
"Hackett--Hackett! We can't leave him--"
"Too late!" Sarja cried. "We cannot help him but only be capturedagain. We escape now and come back--come back--"
The truth of it pierced Norman's brain even in the wild moment.Hackett had fought and held back the frog-guards only that they mightescape. He shouted suddenly.
"Sarja--the water-tunnel!" A half-dozen boats with frog-guards on themwere rising round it in answer to the alarm!
"The force-gun!" cried the green man. "Beside you--!"
Norman whirled, glimpsed the long tube on its swivel beside him,trained it on the boats rising ahead as they rocketed nearer. Hefumbled frantically at a catch at the gun's rear, then felt a streamof shells flicking out of it. Two of the boats ahead vanished as theshells released their annihilating force, another sagged and fell.From the remaining three invisible force-shells flicked around them,but in an instant Sarja had whirled the boat through them and downinto the water-tunnel!
Norman clung desperately to his seat as the boat flashed down throughthe waters, and then, as Sarja sent it flying out through the greattunnel's waters, glimpsed, close behind, the beams of the three Ralaboats as they pursued them through the tunnel, overtaking them. Couldthe force-shells be fired under water? Norman did not know, butdesperately he swung the force-gun back as they rushed through thewaters, and pressed the catch. An instant later beams and boats behindthem in the tunnel vanished.
His lungs were afire; it seemed that he must open them to thestrangling water. The boat was ripping the waters at such tremendousspeed that he felt himself being torn from his hold on it. Pain seemedpoured like molten metal through his chest--he could hold out nolonger; and then the boat stabbed up from the waters into clear air!
* * * * *
Norman panted, sobbed. Behind them rose the colossal metal dome of thefrog-city, gleaming dully in the silvery light that flooded thefar-stretching seas. That light poured down from a stupendous silvercrescent in the night skies. Norman saw dully the dark outlines on itbefore he remembered. Earth! He laughed a little hysterically. Sarjawas driving the flying-boat out over the sea and away from thefrog-city at enormous speed. At last he glanced back. Far behind themlay the great dome and up around it gleaming lights were pouring,lights of pursuing Rala boats.
"We escape," Sarja cried, "the city of the Ralas, from which none everbefore escaped!"
Remembrance smote Norman. "Hackett! Held off those frog-men so wecould get away--we'll come back for him, by God!"
"We come back!" said Sarja. "We come back with all the green men ofthis world to the Ralas' city, yes! I know what Fallas has planned."
"Can you find your way to him--to your city?" Norman asked.
Sarja nodded, looking upward. "Before the next sun has come and gonewe can reach it."
The boat flew onward, and the great dome and the searching lightsaround it dropped beneath the horizon. Norman felt the warm winddrying his drenched garments as they rushed onward. Crouched on theboat he gazed up toward the silver crescent of Earth sinking towardthe horizon ahead. That meant, he told himself, that the satelliteturned slowly on its axis as it whirled around Earth. It came to himthat its night and day periods must be highly irregular.
When the sun climbed from the waters behind them they were flyingstill over a boundless waste of waters, but soon they sighted on thehorizon ahead the thin green line of land. Sarja slowed as theyreached it, took his bearings, and sent the craft flying onward.
They passed over a green coastal plain and then over low hills joinedin long chains and mantled by dense and mighty jungles, towering greengrowths of unfamiliar appearance to Norman. He thought he glimpsed,more than once, huge beastlike forms moving in them. He did see twicein the jungles great clearings where were fair-sized cities ofbright-green buildings, a metal tower rising from each. But when hepointed to them Sarja shook his head.
* * * * *
At last, as they passed over another range of hills and came intosight of a third green city with its looming tower, the other pointed,his face alight.
"My city," he said. "Fallas there."
Fellows! Norman's heart beat faster.
They shot closer and lower and he saw that the buildings wereobviously green to lend them a certain protective coloration similarto that of the green jungles around them. The tower with itssurmounting cage puzzled him though, but before he could ask Sarjaconcerning it his answer came in a different way. A long metal tubepoked slowly out of the cage on the tower's top and sent a hail offorce-shells flicking around them.
"They're firing on us!" Norman cried. "This can't be your city!"
"They see our black boat!" Sarja exclaimed. "They think we're Ralaraiders and unless we let them know they'll shoot us out of the air!Stand up--wave to them--!"
Both Norman and Sarja sprang to their feet and waved wildly to thosein the tower-cage, their flying-boat drifting slowly forward.Instantly the force-shells ceased to hail toward them, and as theymoved nearer a sirenlike signal broke from the cage. At once scores offlying-boats like their own, but glittering metal instead of black,shot up from the city where they had lain until now, and surroundedthem.
As Sarja called in his own tongue to them the green men on thesurrounding boats broke into resounding cries. They shot down towardthe city, Norman gazing tensely. Great crowds of green men in theirdark tunics had swarmed out into its streets with the passing of thealarm, and their craft and the others came to rest in an open squarethat was the juncture of several streets.
The green men that crowded excitedly about Norman and Sarja gave wayto a half-dozen hurrying into the square from the greatest of thebuildings facing on it. All but one were green men like the others.But that one--the laughing-eyed tanned face--the worn brown clothing,the curious huge steps with which he came--Norman's heart leapt.
"Fellows!"
"Great God--Norman!" The other's face was thunderstruck. "Norman--howby all that's holy did you get here?"
* * * * *
Norman, mind and body strained to the breaking point, was incoherent."We guessed how you'd gone--the second satellite, Fellows--Hackettand I came after you--taken to that frog-city--"
As Norman choked the tale, Fellows' face was a study. And when it wasfinished he swallowed, and gripped Norman's hand viselike.
"And you and Hackett figured it out and came after me--took that risk?Crazy, both of you. Crazy--"
"Fellows, H
ackett's still there, if he's alive! In the Rala city!"
Fellows' voice was grim, quick. "We'll have him out. Norman, if hestill lives. And living or dead, the Ralas will pay soon for this andfor all they've done upon this world in ages. Their time nears--yes."
He led Norman, excited throngs of the green men about them, into thegreat building from which he had emerged. There were big rooms inside,workshops and laboratories that Norman but vaguely glimpsed inpassing. The room to which the other led him was one with a long metalcouch. Norman stretched protestingly upon it at the other's bidding,drifted off almost at once into sleep.
He woke to find the sunlight that had filled the room gone andreplaced by the silvery Earth-light. From the window he saw that thesilver-lit city outside now held tremendous activity, immense hordesof green men surging through it with masses of weapons and equipment,flying-boats pouring down out of the night from all directions. Heturned as the door of the room clicked open behind him. It was his oldfriend Fellows.
"I thought you'd be awake by now, Norman. Feeling fit?"
"As though I'd slept a week," Norman said, and the other laughed hisold care-free laugh.
"You almost have, at that. Two days and nights you've slept, but itall adds up to hardly more than a dozen hours."
"This world!" Norman's voice held all his incredulity. "To think thatwe should be on it--a second satellite of Earth's--it seems almostbeyond belief."
* * * * *
"Sometimes it seems so to me, too," Fellows said thoughtfully. "Butit's not a bad world--not the human part of it, at least. When thissatellite's atmosphere caught me and pitchforked me down among thesegreen men, smashing the plane and almost myself, they took care of me.You say three others vanished as I did? I never heard of them here;they must have crashed into the sea or jungles. Of course, I'd havegot back to Earth on one of these flying-boats if I'd been able, buttheir molecular power won't take them far from this world's surface,so I couldn't.
"As it was, the green men cared for me, and when I found how thosefrog-men have dominated this world for ages, how that city of theRalas has spread endless terror among the humans here, I resolved tosmash those monsters whatever I did. I taught some of the green menlike Sarja my own speech, later learning theirs, and in the weeks I'vebeen here I've been working out a way to smash the Ralas.
"You know that amphibian city is almost impregnable because humans canhardly live long enough under the water to get into it, let alonefight under water as the frog-men can. To meet them on even terms thegreen men needed diving-helmets with an oxygen supply. They'd neverheard of such an idea, too afraid of the sea ever to experiment in it,but I convinced them and they've made enough helmets for all theirforces. In them they can meet the Ralas under water on equal terms.
"And there's a chance we can destroy that whole Rala city with theirhelp. It's built on a giant pedestal of rock rising from the sea'sfloor, as you saw, and I've had some of the green men make hugeforce-shells or force-bombs that ought to be powerful enough to splitthat pedestal beneath the city. If we can get a chance to place thosebombs it may smash the frog-men forever on this world. But one thingis sure: we're going to get Hackett out if he still lives!"
"Then you're, going to attack the Rala city now?" Norman cried.
Fellows nodded grimly. "While you have slept all the forces of thegreen men on this world have been gathering. Your coming has onlyprecipitated our plans, Norman--the whole soul of the green races hasbeen set upon this attack for weeks!"
* * * * *
Norman, half bewildered at the swiftness with which events rushed uponhim, found himself striding with Fellows in great steps out throughthe building into the great square. It was shadowed now by mass onmass of flying-boats, crowded with green men, that hung over it andover the streets. One boat, Sarja at its controls, waited on theground and as they entered and buckled themselves into the seats thecraft drove up to hang with the others.
A shattering cheer greeted them. Norman saw that in the silvery lightof Earth's great crescent there stretched over the city andsurrounding jungle now a veritable plain of flying-boats. On each weregreen men and each bristled with force-guns, and had as many greatgoggled helmets fastened to it as it had occupants. He glimpsed largerboats loaded with huge metal cylinders--the force-bombs Fellows hadmentioned.
Fellows rose and spoke briefly in a clear voice to the assembled greenmen on their craft, and another great shout roared from them, and fromthese who watched in the city below. Then as he spoke a word, Sarjasent their craft flying out over the city, and the great mass ofboats, fully a thousand in number, were hurtling in a compact columnafter them.
Fellows leaned to Norman as the great column of purring craft shot onover the silver-lit jungles. "We'll make straight for the Rala cityand try setting into it before they understand what's happening."
"Won't they have guards out?"
"Probably, but we can beat them back into the city before their wholeforces can come out on us. That's the only way in which we can getinside and reach Hackett. And while we're attacking the force-bombscan be placed, though I don't rely too much on them."
"If the attack only succeeds in getting us inside," Norman said,grim-lipped, "we'll have a chance--"
"It's on the knees of the gods. These green men are doing anunprecedented thing in attacking the Ralas, the masters of this world,remember. But they've got ages of oppression to avenge; they'llfight."
The fleet flew on, hills and rivers a silver-lit panorama unreelingbeneath them. Earth's crescent sank behind them, and by the time theyflashed out over the great fresh-water sea, the sun was rising like aflaming eye from behind it. Land sank from sight behind and the greenmen were silent, tense, as they saw stretching beneath only the graywaters that for ages had been the base of the dread frog-men. Butstill the fleet's column raced on.
* * * * *
At last the column slowed. Far ahead the merest bulge broke the levelline where sky and waters met. The amphibian city of the Ralas! AtFellows' order-the flying-boats sank downward until they moved justabove the waters. Another order made the green hosts don the grotesquehelmets. Norman found that while cumbersome their oxygen supply wasunfailing. They shot on again at highest speed, but as the giganticblack dome of the frog-city grew in their vision there darted up fromaround it suddenly a far-flung swarm of black spots.
"Rala boats!"
The muffled exclamation was Fellows'. There needed now no order on hispart, though. Like hawks, leaping for prey, the fleet of the green mensprang through the air. Norman, clutching the force-gun between hisknees, had time only to see that the Rala craft were a few hundred innumber and that, contemptuous of the greater odds that favored thesehumans they had so long oppressed, they were flying straight to meetthem. Then the two fleets met--and were spinning side by side abovethe waters.
Norman saw the thing only as a wild whirl of Rala boats toward andbeside them, great green frog-men crowding the craft, their force-gunshailing shells. Automatically, with the old air-fighting instinct, hisfingers had pressed the catch of the gun between his knees and as itsshells flicked toward the rushing boats he saw areas of nothingnessopening suddenly in their mass, shells striking and exploding inannihilating invisibility there and in their own fleet.
The two fleets mingled and merged momentarily, the battle becoming athing of madness, a huge whirl of black and glittering flying-boatstogether, striking shells exploding nothingness about them. The Ralaswere fighting like demons.
The merged, terrific combat lasted but moments; could last butmoments. Norman, his gun's magazine empty, seemed to see the mass ofstruggling ships splittering, diverging; then saw that the black craftwere dropping, plummeting downward toward the waves! The Ralas,stunned by that minute of terrific combat, were fleeing. Muffled criesand cheers came from about him as the glittering flying-boats of thegreen men shot after them. They crashed down into the waters andc
urved deeply into their green-depths, toward the gigantic dome.
* * * * *
Ahead the Rala boats were in flight toward their city, and now theirpursuers were like sharks striking after them. There in the depths theforce-guns of black and glittering boats alike were spitting, andgiant waves and underwater convulsions rocked pursued and pursuers asthe exploding shells annihilated boats and water about them. Thetunnel! Its round opening yawned in the looming wall ahead, and Normansaw the Rala craft, reduced to scores in number, hurtling into it, torouse all the forces of the great amphibian city. Their own boats wereflashing into the opening after them. He glimpsed as he glanced backfor a moment the larger craft with the great force-bombs veering asidebehind them.
It was nightmare in the water-tunnel. Flashing beams of the craftahead and waters that rocked and smashed around them as in flight theRalas still rained back force-shells toward them in a chaos of action.Once the frog-men turned to hold them back in the tunnel, but by sheerweight the rushing ships of the green men crashed them onward. Boatswere going into nothingness all around them. A part of Norman's brainwondered calmly why they survived even while another part kept his gunagain working, with refilled magazine. Fellows and Sarja weregrotesque shapes beside him. Abruptly the tunnel curved upward and asthey flashed up after the remaining Rala craft their boats ripped upinto clear air! They were beneath the giant dome!
The frog-men chased inward spread out in all directions over theirmighty, swarming city and across it a terrific clamor of alarm raninstantly as the green men emerged after them! Norman saw flying-boatsbeginning to rise across all the city and realized that moments wouldsee all the immense force of the Ralas, the thousands of craft theycould muster, pouring upon them. He pointed out over the city to ablock-like building, and shouted madly through his helmet to Fellowsand Sarja:
"Hackett!"
But already Sarja had sent their craft whirling across the city towardthe structure, half their fleet behind it, with part still emergingfrom the water-tunnel. Rala boats rose before them, but nothing couldstop them now, their force-shells raining ahead to clear a path fortheir meteor-flight. They shot down toward the block-structure, andNorman, half-crazed by now, saw that to descend and enter was suicidein the face of the frog-forces rising now over all the city. He criedto Fellows, and with two of the guns as they swooped lower theysprayed force-shells along the building's side.
* * * * *
The shells struck and whiffed away the whole side, exposing the levelon the building's interior. Out from it rushed swarms of crazed greenmen, sweeping aside the frog-men guards, while far over the city theinvading craft were loosing shells on the block-like buildings thatheld the prisoners, tens of thousands of them swarming forth. In thethrong below as they raced madly forth Norman saw one, and shoutedwildly. The one brown garbed figure looked up, saw their boat swoopinglower, and leaped for it in a tremendous forty-foot spring thatbrought his fingers to its edge. Norman pulled him frenziedly up.
"Norman!" he babbled. "In God's name--Fellows--!"
"That helmet, Hackett!" Fellows flung at him. "My God, look at thoseprisoners--Norman!"
The countless thousands of green men released from the buildings whosewalls had vanished under the shells of the invaders had poured forthto make the amphibian city a chaos of madness. Oblivious to all elsethey were throwing themselves upon the city's crowding frog-men in abattle whose ferocity was beyond belief, disregarding all else in thissupreme chance to wreak vengeance on the monstrous beings who had fedupon their blood. In the incredible insanity of that raging fury thecraft of the green men hanging over the city were all but forgotten.
Suddenly the city and the mighty dome over it quivered violently, andthen again. There came from beneath a dull, vast, grinding roar.
"The great force-bombs!" Fellows screamed. "They've set them off--thecity's sinking--out of here, for the love of God!"
The boat whirled beneath Sarja's hands toward the pool of thewater-tunnel, all their fleet rushing with them. The grinding roar waslouder, terrible; dome and city were shaking violently now; but in theinsensate fury of their struggle the frog-men and their releasedprisoners were hardly aware of it. The whole great dome seemed sinkingupon them and the city falling beneath it as Sarja's craft ripped downinto the tunnel's waters, and then out, at awful speed, as the greattunnel's walls swayed and sank around them! They shot out into thegreen depths from it to hear a dull, colossal crashing through thewaters from behind as the great pedestal of rock on which the city hadstood, shattered by the huge force-bombs, collapsed. And as theirboats flashed up into the open air they saw that the huge dome of thecity of the Ralas was gone.
Beneath them was only a titanic whirlpool of foaming waters in whichonly the curved top of the settling dome was visible for a moment asit sank slowly and ponderously downward, with a roar as of the roar offalling worlds. Buckling, collapsing, sinking, it vanished in thefoam-wild sea with all the frog-men who for ages had ruled the secondsatellite, and with all those prisoners who had at the last draggedthem down with them to death! Ripping off their helmets, with all thegreen men shouting crazily about them, Norman and Fellows and Hackettstared down at the colossal maelstrom in the waters that was the tombof the masters of a world.
Then the depression's sides collapsed, the waters rushing together ...and beneath them was but troubled, tossing sea....
* * * * *
Earth's great gray ball was overhead again and the sun was sinkingagain to the horizon when the three soared upward in the long,gleaming plane, its motor roaring. Norman, with Hackett and Fellowscrowding the narrow cabin beside him, waved with them through itswindows. For all around them were rising the flying-boats of the greenmen.
They were waving wildly, shouting their farewells, Sarja's tall figureerect at the prow of one. Insistent they had been that the threeshould stay, the three through whom the monstrous age-old tyranny ofthe frog-men had been lifted, but Earth-sickness was on them, and theyhad flown to where the plane lay still unharmed among the reeds, ahundred willing hands dragging it forth for the take-off.
The plane soared higher, motor thundering, and they saw theflying-boats sinking back from around them. They caught the wave ofSarja's hand still from the highest, and then that, too, was gone.
Upward they flew toward the great gray sphere, their eyes on the darkoutlines of its continents and on one continent. Higher--higher--greenland and gray tea receding beneath them; Hackett and Fellows intentand eager as Norman kept the plane rising. The satellite lay, agreenish globe, under them. And as they went higher still a rushingsound came louder to their ears.
"The edge of the satellite's atmosphere?" Fellows asked, as Normannodded.
"We're almost to it--here we go!"
As he shot the plane higher, great forces smote it, gray Earth andgreen satellite and yellow sun gyrating round it as it reeled andplunged. Then suddenly it was falling steadily, gray Earth and itsdark continent now beneath, while with a dwindling rushing roar itssecond satellite whirled away above them, passing and vanishing.Passing as though, to Norman it seemed, all their strange sojourn onit were passing; the frog-men and their mighty city, Sarja and theirmad flight, the green men and the last terrific battle; all whirlingaway--whirling away.
HISTORIC EXPERIMENT PROVES EARTH'S ROTATION
The famous experiment which proves that the "earth do move" by lettingthe observer actually see it twisting underneath his feet, anexperiment invented by the French mathematician Jean B. L. Foucaultnearly a century ago was repeated recently under unusually impressivecircumstances before an international scientific congress at Florence,Italy, the same city where Galileo once was persecuted for holding thesame opinion.
From the center of the dome of the Church of Santa Maria di Fiore,Father Guido Alfani, director of the Astronomical Observatory,suspended a 200-pound weight on a wire 150 feet long. On the bottom ofthis weight was a tiny proje
cting point which traced a line on atable-top sprinkled with sand, as the great pendulum swung slowly backand forth. At a given signal Father Alfani set the pendulum toswinging. While the assembled scientists watched it, slowly the linetraced across the sand table-top changed direction.
As Foucault proved long ago and as the watching scientists well knew,the table was being twisted underneath the pendulum by the rotation ofthe earth.
A REVOLUTIONARY AIRPLANE
A new airplane propeller has recently been patented by J. Kalmanson ofBrooklyn, N. Y. Greater speed and marked saving in fuel is claimed forthe invention, which may be attached to any type of airplane.
The device is in two parts, which may be used separately as front andrear propellers or combined into a single blade. The principle is thatthe front one acts to bring air to the other, giving the propellermore of a hold, so to speak, and greater power. This is accomplishedby four air-spoons, one on each side of each blade of the propeller.
It is said that the device can double the speed of an airplane andraise it from the ground in ninety feet instead of the 200 feet mostairplanes now require. It is also claimed that the new propeller willprevent the plane from making a nose drive unless the pilot forces itto do so, and enable it to make a safe landing within a shortdistance. Because of the increase in power and speed, the device wouldsave a large amount of gasoline and oil, as well as guarding the motorfrom part of the strain on it.
The device is said to be also applicable to ships, the same principleoperating in water as well as air.
