* * *
He ran back into the radio-telephone cubby, which was a division ofthe control car. The operator was sprawled there, limp in his seatbefore the shining, switch-studded panel. Chris removed the head-gearof ear-phones: then he hauled one of the cubby's port-holes open,letting in a rush of cleansing air. His fingers sped quickly over thepanel; a row of tubes glowed; the machinery hummed. Chris jerked offhis mask.
A last faint odor was present, but he hardly noticed it, for his lipswere at the mouthpiece and he was thrusting out a call for help.
"ZX-1 calling ... ZX-1 calling ... ZX-1--Hello!"
An answer from the flagship of the Black Fleet ahead had sounded.
"This is Travers, pilot on the ZX-1, speaking. We're coming dead foryou; full speed; you'll see us in minutes. Get some planes with mencapable of handling the dirigible up here immediately. The wholecrew's been laid out by gas; there was a contrivance planted aboard toblow up the ship and send it down in flames as the ZX-2 was. The thingthat did it--"
_Crack!_
A gun barked out from behind; something crashed and splintered on theradio panel. Chris felt a white-hot needle sear along the side of hishead. His brain reeled; with everything dancing queerly before him insplotches of gray and black he toppled down off the seat, knowing theradio-telephone had been put out of commission by the cessation ofsound in the ear-phones clamped to him.
He gripped his consciousness hard. It was like a delirium: he waslying sprawled beside the seat, twisted round so that he saw, hangingin the cubby's entrance door, an automatic, dribbling a wisp ofsmoke--the automatic that had just fired, but hanging there by itself,held by something he could not see!
He was only half conscious, for the scorching pain along his head wasthrobbing his brain dizzily, but he realized that the service repeaterhe had taken from the control car lay by his side, within easy reach.But, while on the verge of risking a wild grab for it, he heard avoice, speaking very softly and with a slight thickness of accent.
"Do not move," it said. "I fire if you do. Now, listen: What did youdo with the box that you found? Tell me quick, or die."
It was fantastic, unreal. There was--nothing, and yet a man, living,breathing, but invisible, was speaking! Chris could not understand;but it was at least a little relief to know he had a human to dealwith. For with humans, strategy can be used....
* * * * *
He groaned. He saw plainly that the unseen marauder had been aboardwhen he had thrown the box over, and thus had not seen it explode inmidair: did not know whether it had been tossed out or merely renderedharmless by being tampered with. If only the latter, it could bequickly repaired and set again. That must be the invisible man'sreasoning.
Again Chris groaned. He moved an arm weakly and whispered:
"Can't speak much. Come closer."
The service repeater was very close now to his right hand. And he felta thrill when he saw the automatic come forward through the air,descend, and pause right next to his head. He sensed a man closebehind him, and he heard:
"Well? Tell me, quick. Did you throw it over, or--?"
"Don't shoot!" Chris groaned. "I'll tell you. I didn't--throw it over.I took it apart to get the secret of it. I put it--there."
He pointed feebly with his right hand, thus leading the invisible manto turn his head. His legs braced imperceptibly. And then:
"Like hell!" roared Chris Travers, and shot his whole weightbackwards, grasping the service gun, whipping it around and yankingthe trigger three times at the same instant.
Shooting at nothing! But, even above the bunched roar of theexplosions, there pierced out a howl of agony that died quickly to asobbing moan. Chris saw the automatic drop to the floor, felt theinvisible body he had crashed into jerk away. He jumped to his feet,clutched at that body, and caught thin air. He swung around,listening, the service repeater in his hand.
Out of the air somewhere before him there came the sound of low,racking gasps, and also the slow noise of feet dragging heavilytowards the cubby's door, towards the ladder that led up to thefore-and-aft cat-walk.
Chris sprang, slashing the butt of the gun downwards. The lead wasfalse. He hurtled jarringly into the door jamb, the gun thumpingagainst the floor. The wind was knocked from him; the nausea of hiswound swept him again with a surge of dizziness. But the painfulscuffle of unseen feet ahead pulled him up once more; like apunch-drunk fighter he staggered out from the cubby to the ladder andhauled himself up the steps. He half-fell at the top, but his mind wasclearing; and as he swayed there he knew what he had to do--saw theduty that lay before him....
More slowly, he crawled after the dragging footsteps and the gasps ofthe invisible raider, following them through the vast dimness of theinterior of the dirigible ZX-1.
* * * * *
The chief operator on duty in the flagship of the Black Fleet swunground in his seat and yelled through into the bridge of the massivebattleship:
"Urgent, sir! From the ZX-1!"
A moment later the captain of the ship, for the fleet's admiral wasout in a launch inspecting what little of the fallen ZX-2 was stillfloating on the surface, was at the operator's side, listeningamazedly.
The operator read off, word for word, what Chris Travers had sent."... There was a contrivance planted aboard to blow up the ship andsend it down in flames as the ZX-2 was. The thing that did it is--" hefinished, and fell silent on that uncompleted sentence.
The captain's lined face expressed incredulity. "My God!" he burstout. "First the ZX-2, now-- That all?"
"Yes, sir. I can't get any answer or connection."
They stared at each other. Finally the captain spluttered:
"Is some maniac loose in this fleet? Don't sit there like a fool, man!Get in touch with the _Saratoga_; tell 'em what you received; tell 'emto send some men up to that dirigible, wherever she is. We can't loseboth of them!"
The operator's fingers skipped nimbly; even while he was speaking intothe microphone, the red-faced captain had rushed back into the controlbridge and was roaring:
"Signal the Admiral back here! Hurry!"
* * * * *
Things moved quickly then; small things, but significant. A casual eyeglancing over the ranks of the Black Fleet as it lay around the sceneof the tragedy, waiting for orders, would not have noticed anydifference. The launch containing the fleet's admiral, which had beenfussing about with its load of officers and various dignitaries,suddenly wheeled and pointed back for the mammoth flagship, inresponse to swift signals from the arms of a gob on her bridge; and,on the broad landing deck of the carrier, _Saratoga_, two three-seaterplanes, equipped with automatic clamps for a dirigible's rack, werewheeled up to the line.
Their props were spun over. But even before their cockpits had beenfilled, an officer on the bridge of the flagship, and a dozen othersthroughout the fleet, cried:
"There she is!"
Over the eastern horizon, a gleaming sliver in the sunlight, thunderedthe ZX-1, straight for the array of the Black Fleet. Only a few menwere aware of the drama-fraught message which had come down from herradio cubby, but her growing shape commanded the eyes of every sailorand officer alike who had time to watch. A few telescopic sights weretrained on her as she bellowed ahead; the keen old eyes of a veryperplexed and puzzled admiral were at one of them.
"Two planes hanging from her rack," he muttered, half to himself andhalf to the officers standing around him. "Both Navy. Say, they'redropping off! Not coming this way, either. Going northeast. Fast, too.Can't see 'em any more.... Those men getting up from the _Saratoga_?Good. We'll find out something soon. Here she comes!"
Closer and closer roared the dirigible. Two planes from the _Saratoga_were swooping up to enter her rack, but the other two planes thatshortly before had been suspended from it were gone--already vanishedinto the northeast.
"Don't understand this at all!" said the Admiral of the Black, orPacific, F
leet of the United States Navy.
* * * * *
Things had broken well, Chris Travers considered. He had only woundedthe invisible raider; but, luckily, had wounded him badly, so that,evidently, just one object was in the man's mind: to get back to wherehe came from, to where he could find help. He seemed oblivious of thescout that was following behind at the full speed of its mighty rotarymotor, following him to his base, wherever it was.
"Just as well I didn't kill him," Chris muttered.
The rush of wind had cleared his brain; his faculties were steady andnormal. Not so with the man in the plane he pursued. It was flyingcrazily, but clinging to one course, nevertheless--into the northeast,towards land, some two hundred and fifty miles over the horizon.
The great silver shape of the ZX-1, barren, now,