Every eight hours Seaton launched his all-embracing ultra-detector, but day after day pa.s.sed and the instruments remained motionless after each cast of that gigantic net. For several days the Galaxy behind them had been dwindling from a ma.s.s of stars down to a huge bright lens; down to a small, faint lens; down to a faintly luminous patch. At the previous cast of the detector it had still been visible as a barely-perceptible point of light in the highest telescopic power of the visiplate. Now, as Dorothy and Seaton, alone in the control room, stared into that visiplate, everything was blank and black; sheer, indescribable blackness; the utter and absolute absence of everything visible or tangible.

"This is awful, d.i.c.k.... It's just too darn horrible. It simply scares me pea-green!" she shuddered as she drew herself to him, and he swept both his mighty arms around her in a soul-satisfying embrace.

"'Sall right, darling. That stuff out there'd scare anybody--I'm scared purple myself. It isn't in any finite mind to understand anything infinite or absolute. There's one redeeming feature, though, cuddle-pup--we're together."

"You chirped it, lover!" Dorothy returned his caresses with all her old-time fervor and enthusiasm. "I feel lots better now. If it gets to you that way, too, I know it's perfectly normal--I was beginning to think maybe I was yellow or something ... but maybe you're kidding me?"

she held him off at arm's length, looking deep into his eyes: then, rea.s.sured, went back-into his arms. "Nope, you feel it, too," and her glorious auburn head found its natural resting-place in the curve of his mighty shoulder.

"Yellow!... You?" Seaton pressed his wife closer still! and laughed aloud. "Maybe--but so is picric acid; so is nitroglycerin; and so is pure gold."

"Flatterer!" Her low, entrancing chuckle bubbled over. "But you know I just revel in it. I'll kiss you for that!"

"It _is_ awfully lonesome out here, without even a star to look at," she went on, after a time, then laughed again. "If the Cranes and Shiro weren't along, we'd be really 'alone at last,' wouldn't we?"

"I'll say we would! But that reminds me of something. According to my figures, we might have been able to detect the Fenachrone on the last test, but we didn't. Think I'll try 'em again before we turn in."

Once more he flung out that tenuous net of force, and as it reached the extreme limit of its travel, the needle of the micro-ammeter flickered slightly, barely moving off its zero mark.

"Whee! Whoopee!" he yelled. "Mart, we're on 'em!"

"Close?" demanded Crane, hurrying into the control room upon his beam.

"Anything but. Barely touched 'em--current something less than a thousandth of a micro-ampere on a million to one step-up. However, it proves our ideas are O. K."

The next day--_Skylark III_ was running on Eastern Standard Time, of the Terrestrial United States of America--the two mathematicians covered sheet after sheet of paper with computations and curves. After checking and rechecking the figures, Seaton shut off the power, released the molecular drive, and applied acceleration of twenty-nine point six oh two feet per second; and five human beings breathed as one a profound sigh of relief as an almost-normal force of gravitation was restored to them.

"Why the let-up?" asked Dorothy. "They're an awful long ways off yet, aren't they? Why not hurry up and catch them?"

"Because we're going infinitely faster than they are now. If we kept up full acceleration, we'd pa.s.s them so fast that we couldn't fight them at all. This way, we'll still be going a lot faster than they are when we get close to them, but not enough faster to keep us from maneuvering relatively to their vessel, if things should go that far. Guess I'll take another reading on 'em."

"I do not believe that I should," Crane suggested, thoughtfully. "After all, they may have perfected their instruments, and yet may not have detected that extremely light touch of our ray last night. If so, why put them on guard?"

"They're probably on guard, all right, without having to be put there--but it's a sound idea, anyway. Along the same line I'll release the fifth-order screens, with the fastest possible detector on guard.

We're just about within reach of a light copper-driven ray right now, but it's a cinch they can't send anything heavy this far, and if they think we're overconfident, so much the better."

"There," he continued, after a few minutes at the keyboard. "All set. If they put a detector on us, I've got a force set to make a noise like a New York City fire siren. If pressed, I'd reluctantly admit that in my opinion we're carrying caution to a point ten thousand degrees below the absolute zero of sanity. I'll bet my shirt that we don't hear a yip out of them before we touch 'em off. Furthermore...."

The rest of his sentence was lost in a crescendo bellow of sound.

Seaton, still at the controls, shut off the noise, studied his meters carefully, and turned around to Crane with a grin.

"You win the shirt, Mart. I'll give it to you next Wednesday, when my other one comes back from the laundry. It's a fifth-order detector ray, coming in beautifully on band forty-seven fifty, right in the middle of the order."

"Aren't you going to put a ray on 'em?" asked Dorothy in surprise.

"Nope--what's the use? I can read theirs as well as I could one of my own. Maybe they know that too--if they don't we'll let 'em think we're coming along, as innocent as Mary's little lamb, so I'll let their ray stay on us. It's too thin to carry anything, and if they thicken it up much I've got an axe set to chop it off." Seaton whistled a merry lilting refrain as his fingers played over the stops and keys.

"Why, d.i.c.k, you seem actually pleased about it." Margaret was plainly ill at ease.

"Sure am. I never did like to drown baby kittens, and it kinda goes against the grain to stab a guy in the back, when he ain't even looking, even if he is a Fenachrone. If they can fight back some I'll get mad enough to blow 'em up happy."

"But suppose they fight back too hard?"

"They can't--the worst that can possibly happen is that we can't lick them. They certainly can't lick us, because we can outrun 'em. If we can't get 'em alone, we'll beat it back to Norlamin and bring up re-enforcements."

"I am not so sure," Crane spoke slowly. "There is, I believe, a theoretical possibility that sixth-order rays exist. Would an extension of the methods of detection of fifth-order rays reveal them?"

"_Sixth_? Sweet spirits of niter! n.o.body knows anything about them.

However, I've had one surprise already, so maybe your suggestion isn't as crazy as it sounds. We've got three or four days yet before either side can send anything except on the sixth, so I'll find out what I can do."

He flew at the task, and for the next three days could hardly be torn from it for rest; but

"O. K., Mart," he finally announced. "They exist, all right, and I can detect 'em. Look here," and he pointed to a tiny receiver, upon which a small lamp flared in brilliant scarlet light.

"Are they sending them?"

"No, fortunately. They're coming from our bar. See, it shines blue when I put a grounded shield between it and the bar, and stays blue when I attach it to their detector ray."

"Can you direct them?"

"Not a chance in the world. That means a lifetime, probably many lifetimes, of research, unless somebody uses a fairly complete pattern of them close enough to this detector so that I can a.n.a.lyze it. 'Sa good deal like calculus in that respect. It took thousands of years to get it in the first place, but it's easy when somebody that already knows it shows you how it goes."

"The Fenachrone learned to direct fifth-order rays so quickly, then, by an a.n.a.lysis of our fifth-order projector there?"

"Our secondary projector, yes. They must have had some neutronium in stock, too--but it would have been funny if they hadn't, at that--they've had intra-atomic power for ages."

Silent and grim, he seated himself at the console, and for an hour he wove an intricate pattern of forces upon the inexhaustible supply of keys afforded by the ultra-projector before he once touched a plunger.

"What are you doing? I followed you for a few hundred steps, but could go no farther."

"Merely a little safety-first stuff. In case they should send any real pattern of sixth-order rays this set-up will a.n.a.lyze it, record the complete a.n.a.lysis, throw out a screen against every frequency of the pattern, throw on the molecular drive, and pull us back toward the galaxy at full acceleration, while switching the frequency of our carrier wave a thousand times a second, to keep them from shooting a hot one through our open band. It'll do it all in about a millionth of a second, too--I want to get us all back alive if possible! Hm--m. They've shut off their ray--they know we've tapped onto it. Well, war's declared now--we'll see what we can see."

Transferring the a.s.sembled beam to a plunger, he sent out a secondary projector toward the Fenachrone vessel, as fast as it could be driven, close behind a widespread detector net. He soon found the enemy cruiser, but so immense was the distance that it was impossible to hold the projection anywhere in its neighborhood. They flashed beyond it and through it and upon all sides of it, but the utmost delicacy of the controls would not permit of holding even upon the immense bulk of the vessel, to say nothing of holding upon such a relatively tiny object as the power bar. As they flashed repeatedly through the warship, they saw piecemeal and sketchily her formidable armament and the hundreds of men of her crew, each man at battle station at the controls of some frightful engine of destruction. Suddenly they were cut off as a screen closed behind them--the Earth-men felt an instant of unreasoning terror as it seemed that one-half of their peculiar dual personalities vanished utterly. Seaton laughed.

"That was a funny sensation, wasn't it? It just means that they've climbed a tree and pulled the tree up after them."

"I do not like the odds, d.i.c.k," Crane's face was grave. "They have many hundreds of men, all trained; and we are only two. Yes, only one, for I count for nothing at those controls."

"All the better, Mart. This board more than makes up the difference.

They've got a lot of stuff, of course, but they haven't got anything like this control system. Their captain's got to issue orders, whereas I've got everything right under my hands. Not so uneven as they think!"

Within battle range at last, Seaton hurled his utmost concentration of direct forces, under the impact of which three courses of Fenachrone defensive screen flared through the ultra-violet and went black. There the ma.s.sed direct attack was stopped--at what cost the enemy alone knew--and the Fenachrone countered instantly and in a manner totally unexpected. Through the narrow slit in the fifth-order screen through which Seaton was operating, in the bare one-thousandth of a second that it was open, so exactly synchronized and timed that the screens did not even glow as it went through the narrow opening, a gigantic beam of heterodyned force struck full upon the bow of the _Skylark_, near the sharply-pointed prow, and the stubborn metal instantly flared blinding white and exploded outward in puffs of incandescent gas under the awful power of that t.i.tanic thrust. Through four successive skins of inoson, the theoretical ultimate of possible strength, toughness, and resistance, that frightful beam drove before the automatically-reacting detector closed the slit and the impregnable defensive screens, driven by their mighty uranium bars, flared into incandescent defense. Driven as they were, they held, and the Fenachrone, finding that particular attack useless, shut off their power.

"Wow! They sure have got something!" Seaton exclaimed in unfeigned admiration. "They sure gave us a solid kick that time! We will now take time out for repairs. Also, I'm going to cut our slit down to a width of one kilocycle, if I can possibly figure out a way of working on that narrow a band, and I'm going to step up our shifting speed to a hundred thousand. It's a good thing they built this ship of ours in a lot of layers--if that'd go through the interior we would have been punctured for fair. You might weld up those holes, Mart, while I see what I can do here."

Then Seaton noticed the women, white and trembling, upon a seat.